WorldWideScience

Sample records for intestinal intra-luminal impedance

  1. Impedance Scaling and Impedance Control

    International Nuclear Information System (INIS)

    Chou, W.; Griffin, J.

    1997-06-01

    When a machine becomes really large, such as the Very Large Hadron Collider (VLHC), of which the circumference could reach the order of megameters, beam instability could be an essential bottleneck. This paper studies the scaling of the instability threshold vs. machine size when the coupling impedance scales in a ''normal'' way. It is shown that the beam would be intrinsically unstable for the VLHC. As a possible solution to this problem, it is proposed to introduce local impedance inserts for controlling the machine impedance. In the longitudinal plane, this could be done by using a heavily detuned rf cavity (e.g., a biconical structure), which could provide large imaginary impedance with the right sign (i.e., inductive or capacitive) while keeping the real part small. In the transverse direction, a carefully designed variation of the cross section of a beam pipe could generate negative impedance that would partially compensate the transverse impedance in one plane

  2. Mechanical impedance

    OpenAIRE

    Couroussé, Damien

    2007-01-01

    International audience; Mechanical impedance is a transposition to mechanics of the term impedance that is used and defined in circuit theory. The theory of circuit (theory of Kirchhoff networks) is basically applicable to electric networks but can be considered more generally as a unifying simplified theory of physics available in several domains like mechanics, electromagnetism, aero-acoustics and fluids mechanics.

  3. Extensive Intestinal Resection Triggers Behavioral Adaptation, Intestinal Remodeling and Microbiota Transition in Short Bowel Syndrome

    Directory of Open Access Journals (Sweden)

    Camille Mayeur

    2016-03-01

    Full Text Available Extensive resection of small bowel often leads to short bowel syndrome (SBS. SBS patients develop clinical mal-absorption and dehydration relative to the reduction of absorptive area, acceleration of gastrointestinal transit time and modifications of the gastrointestinal intra-luminal environment. As a consequence of severe mal-absorption, patients require parenteral nutrition (PN. In adults, the overall adaptation following intestinal resection includes spontaneous and complex compensatory processes such as hyperphagia, mucosal remodeling of the remaining part of the intestine and major modifications of the microbiota. SBS patients, with colon in continuity, harbor a specific fecal microbiota that we called “lactobiota” because it is enriched in the Lactobacillus/Leuconostoc group and depleted in anaerobic micro-organisms (especially Clostridium and Bacteroides. In some patients, the lactobiota-driven fermentative activities lead to an accumulation of fecal d/l-lactates and an increased risk of d-encephalopathy. Better knowledge of clinical parameters and lactobiota characteristics has made it possible to stratify patients and define group at risk for d-encephalopathy crises.

  4. Advances In Impedance Theory

    International Nuclear Information System (INIS)

    Stupakov, G.

    2009-01-01

    We review recent progress in the following areas of the impedance theory: calculation of impedance of tapers and small angle collimators; optical approximation and parabolic equation for the high-frequency impedance; impedance due to resistive inserts in a perfectly conducting pipe.

  5. Intestinal Cancer

    Science.gov (United States)

    ... connects your stomach to your large intestine. Intestinal cancer is rare, but eating a high-fat diet ... increase your risk. Possible signs of small intestine cancer include Abdominal pain Weight loss for no reason ...

  6. Impedance plethysmography of thoracic region: impedance cardiography.

    Directory of Open Access Journals (Sweden)

    Deshpande A

    1990-10-01

    Full Text Available Impedance plethysmograms were recorded from thoracic region in 254 normal subjects, 183 patients with coronary artery disease, 391 patients with valvular heart disease and 107 patients with congenital septal disorder. The data in 18 normal subjects and 55 patients showed that basal impedance decreases markedly during exercise in patients with ischaemic heart disease. Estimation of cardiac index by this technique in a group of 99 normal subjects has been observed to be more consistent than that of the stroke volume. Estimation of systolic time index from impedance plethysmograms in 34 normal subjects has been shown to be as reliable as that from electrocardiogram, phonocardiogram and carotid pulse tracing. Changes in the shape of plethysmographic waveform produced by valvular and congenital heart diseases are briefly described and the role of this technique in screening cardiac patients has been highlighted.

  7. Nonsynchronous Noncommensurate Impedance Transformers

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Kim, K

    2012-01-01

    Nonsynchronous noncommensurate impedance transformers consist of a combination of two types of transmission lines: transmission lines with a characteristic impedance equal to the impedance of the source, and transmission lines with a characteristic impedance equal to the load. The practical...... advantage of such transformers is that they can be constructed using sections of transmission lines with a limited variety of characteristic impedances. These transformers also provide comparatively compact size in applications where a wide transformation ratio is required. This paper presents the data...... which allows to estimate the achievable total electrical length and in-band reflection coefficient for transformers consisting of up to twelve transmission line sections in the range of transformation ratios r = 1:5 to 10 and bandwidth ratios  = 2 to 20. This data is obtained using wave transmission...

  8. Impedance and Collective Effects

    CERN Document Server

    Metral, E; Rumolo, R; Herr, W

    2013-01-01

    This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Chapter '4 Impedance and Collective Effects' with the content: 4 Impedance and Collective Effects Introduction 4.1 Space Charge 4.2 Wake Fields and Impedances 4.3 Coherent Instabilities 4.4 Landau Damping 4.5 Two-Stream Effects (Electron Cloud and Ions) 4.6 Beam-Beam Effects 4.7 Numerical Modelling

  9. Intestinal Obstruction

    Science.gov (United States)

    ... the obstruction along the intestines. Treatment Suction via nasogastric tube Fluids given by vein Surgery for strangulation Sometimes ... nose and placed in the stomach (called a nasogastric tube) or into the intestine. Suction is applied to ...

  10. LHC Bellows Impedance Calculations

    CERN Document Server

    Dyachkov, M

    1997-01-01

    To compensate for thermal expansion the LHC ring has to accommodate about 2500 bellows which, together with beam position monitors, are the main contributors to the LHC broad-band impedance budget. In order to reduce this impedance to an acceptable value the bellows have to be shielded. In this paper we compare different designs proposed for the bellows and calculate their transverse and longitudinal wakefields and impedances. Owing to the 3D geometry of the bellows, the code MAFIA was used for the wakefield calculations; when possible the MAFIA results were compared to those obtained with ABCI. The results presented in this paper indicate that the latest bellows design, in which shielding is provided by sprung fingers which can slide along the beam screen, has impedances smaller tha those previously estimated according to a rather conservative scaling of SSC calculations and LEP measurements. Several failure modes, such as missing fingers and imperfect RF contact, have also been studied.

  11. Impedance and component heating

    CERN Document Server

    Métral, E; Mounet, N; Pieloni, T; Salvant, B

    2015-01-01

    The impedance is a complex function of frequency, which represents, for the plane under consideration (longitudinal, horizontal or vertical), the force integrated over the length of an element, from a “source” to a “test” wave, normalized by their charges. In general, the impedance in a given plane is a nonlinear function of the test and source transverse coordinates, but it is most of the time sufficient to consider only the first few linear terms. Impedances can influence the motion of trailing particles, in the longitudinal and in one or both transverse directions, leading to energy loss, beam instabilities, or producing undesirable secondary effects such as excessive heating of sensitive components at or near the chamber wall, called beam-induced RF heating. The LHC performance limitations linked to impedances encountered during the 2010-2012 run are reviewed and the currently expected situation during the HL-LHC era is discussed.

  12. Electrical Impedance Tomography Technology

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal for the Electrical Impedance Tomography Technology (EITT) project is to develop a reliable portable, lightweight device providing two-dimensional...

  13. The LEP impedance model

    Energy Technology Data Exchange (ETDEWEB)

    Zotter, B. [European Organization for Nuclear Research, Geneva (Switzerland)

    1996-08-01

    This report describes a number of measurements and computations of the impedance of the Large Electron Positron collider LEP at CERN. The work has been performed over several years, together with D. Brandt, K. Cornelis, A. Hofmann, G. Sabbi and many others. The agreement between measurements of single bunch instabilities on the machine and computer simulations is in general excellent and gives confidence in the impedance model used. (author)

  14. Impeded Dark Matter

    International Nuclear Information System (INIS)

    Kopp, Joachim; Liu, Jia; Slatyer, Tracy R.; Wang, Xiao-Ping; Xue, Wei

    2016-01-01

    We consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario “Impeded Dark Matter”. We demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.

  15. Impeded Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Joachim; Liu, Jia [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,Staudingerweg 7, 55099 Mainz (Germany); Slatyer, Tracy R. [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States); Wang, Xiao-Ping [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,Staudingerweg 7, 55099 Mainz (Germany); Xue, Wei [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States)

    2016-12-12

    We consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario “Impeded Dark Matter”. We demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.

  16. Impedance of accelerator components

    International Nuclear Information System (INIS)

    Corlett, J.N.

    1996-05-01

    As demands for high luminosity and low emittance particle beams increase, an understanding of the electromagnetic interaction of these beams with their vacuum chamber environment becomes more important in order to maintain the quality of the beam. This interaction is described in terms of the wake field in time domain, and the beam impedance in frequency domain. These concepts are introduced, and related quantities such as the loss factor are presented. The broadband Q = 1 resonator impedance model is discussed. Perturbation and coaxial wire methods of measurement of real components are reviewed

  17. Implantable Impedance Plethysmography

    Directory of Open Access Journals (Sweden)

    Michael Theodor

    2014-08-01

    Full Text Available We demonstrate by theory, as well as by ex vivo and in vivo measurements that impedance plethysmography, applied extravascularly directly on large arteries, is a viable method for monitoring various cardiovascular parameters, such as blood pressure, with high accuracy. The sensor is designed as an implant to monitor cardiac events and arteriosclerotic progression over the long term.

  18. Impedance plethysmography: basic principles.

    Directory of Open Access Journals (Sweden)

    Babu J

    1990-04-01

    Full Text Available Impedance Plethysmography technique has been discussed with explanation of two compartment model and parallel conductor theory for the estimation of peripheral blood flow and stroke volume. Various methods for signal enhancement to facilitate computation of blood flow are briefly described. Source of error in the estimation of peripheral blood flow is identified and the correction has been suggested.

  19. Intestine transplantation

    Directory of Open Access Journals (Sweden)

    Tadeja Pintar

    2011-02-01

    Conclusion: Intestine transplantation is reserved for patients with irreversible intestinal failure due to short gut syndrome requiring total paranteral nutrition with no possibility of discontinuation and loss of venous access for patient maintenance. In these patients complications of underlying disease and long-term total parenteral nutrition are present.

  20. Meaning of the negative impedance

    Energy Technology Data Exchange (ETDEWEB)

    Conciauro, G.; Puglisi, M.

    1981-06-01

    It is shown that the negative real part of an input impedance does not mean instability of the related circuit. A negative real part of the input impedance means only that the concerned circuit is active.

  1. Meaning of the negative impedance

    International Nuclear Information System (INIS)

    Conciauro, G.; Puglisi, M.

    1981-06-01

    It is shown that the negative real part of an input impedance does not mean instability of the related circuit. A negative real part of the input impedance means only that the concerned circuit is active

  2. Technical aspects of impedance plethysmography.

    Directory of Open Access Journals (Sweden)

    Bhuta A

    1990-04-01

    Full Text Available This paper describes the basic methods for measurement of body impedance, electrodes and their configuration, and the measuring instrument with its limitations. A microcomputer assisted impedance plethysmograph system, developed at BARC and different lead configurations for impedance plethysmographic investigation are also described. Typical impedance plethysmographic waveforms recorded from a normal subject and measurement of their amplitude and various time intervals are illustrated.

  3. SSC kicker impedances

    International Nuclear Information System (INIS)

    Colton, E.P.; Wang, T.F.

    1985-01-01

    The longitudinal and transverse complex impedances Z/sub l//n and Z/sub t/, respectively, have been calculated for both the SSC injection and abort kickers. The calculations assumed that no attempt was made to shield the beam from the kickers. We took the injection and abort kickers to be as specified. The injection kickers were ferrite with a single-turn design, and the abort kickers were of a ''window-frame design'' with tape wound cores

  4. Gynecologic electrical impedance tomograph

    Science.gov (United States)

    Korjenevsky, A.; Cherepenin, V.; Trokhanova, O.; Tuykin, T.

    2010-04-01

    Electrical impedance tomography extends to the new and new areas of the medical diagnostics: lungs, breast, prostate, etc. The feedback from the doctors who use our breast EIT diagnostic system has induced us to develop the 3D electrical impedance imaging device for diagnostics of the cervix of the uterus - gynecologic impedance tomograph (GIT). The device uses the same measuring approach as the breast imaging system: 2D flat array of the electrodes arranged on the probe with handle is placed against the body. Each of the 32 electrodes of the array is connected in turn to the current source while the rest electrodes acquire the potentials on the surface. The current flows through the electrode of the array and returns through the remote electrode placed on the patient's limb. The voltages are measured relative to another remote electrode. The 3D backprojection along equipotential surfaces is used to reconstruct conductivity distribution up to approximately 1 cm in depth. Small number of electrodes enables us to implement real time imaging with a few frames per sec. rate. The device is under initial testing and evaluation of the imaging capabilities and suitability of usage.

  5. What's new in Osmosin and intestinal perforation?

    Science.gov (United States)

    Laidler, P; Maslin, S C; Gilhome, R W

    1985-07-01

    New formulations of drugs may have unexpected side effects. Osmosin is a new osmotic-pump controlled-release formulation of Indomethacin, designed to prevent gastrointestinal irritation. However, in a small number of cases the use of Osmosin has coincided with perforation of the small and large intestine, probably because passage of the tablet through the gastrointestinal tract was impeded.

  6. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J.S. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1996-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impedance. This paper discusses three aspects of broadband impedance modelling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f. cavity. The last is a discussion of requirements for the mathematical form of an impedance which follow from the general properties of impedances. (author)

  7. Impedance Determination from Bench Measurements

    CERN Document Server

    Caspers, Friedhelm

    2000-01-01

    The concept of the coaxial wire technique as a bench method for beam coupling impedance measurements is presented. Starting with the lumped element impedance model formulae are given for impedance evaluation from measured scattering parameters, both for the longitudinal and transverse case and also for the loss-factor. Followed by a section on distributed impedances many hints, precautions and practical aspects for the proper use of the measuring instrument are mentioned. The paper concludes with a brief discussion on special methods in particular for simulation of slow beams, measurements beyond waveguide cutoff and resonator techniques for evaluation of very small impedances.

  8. Intestinal Ischemia

    Science.gov (United States)

    ... weight loss Intestinal ischemia Symptoms & causes Diagnosis & treatment Advertisement Mayo Clinic does not endorse companies or products. ... a Job Site Map About This Site Twitter Facebook Google YouTube Pinterest Mayo Clinic is a not- ...

  9. Intestinal Coccidia

    OpenAIRE

    MJ Ggaravi

    2007-01-01

    Intestinal Coccidia are a subclass of Apicomplexa phylum. Eucoccidida are facultative heteroxenous, but some of them are monoxenous. They have sexual and asexual life cycle. Some coccidia are human pathogens, for example: Cryptosporidium: Cryptosporidiums has many species that are mammalian intestinal parasites.C. Parvum specie is a human pathogenic protozoa. Cryptosporidum has circle or ellipse shapes and nearly 4-6 mm. It is transmitted in warm seasons. Oocyst is obtained insexual life cycl...

  10. LIA longitudinal coupling impedance

    International Nuclear Information System (INIS)

    Faltens, A.

    1980-01-01

    The beam generated fields enter into the problems of waveform generation and longitudinal stability. In the former, provision must be made for the longitudinally defocusing forces due to the space charge and the beam loading effects on the accelerating voltage due to the current of a presumably known bunch. In the latter, the concern is for the growth of unintentional perturbations to unacceptably large values through the interaction of the charge and current fluctuations with the rest of the beam and the surrounding structures. These beam generated electric fields may be related to the beam current through a coupling impedance

  11. RF impedance measurement calibration

    International Nuclear Information System (INIS)

    Matthews, P.J.; Song, J.J.

    1993-01-01

    The intent of this note is not to explain all of the available calibration methods in detail. Instead, we will focus on the calibration methods of interest for RF impedance coupling measurements and attempt to explain: (1). The standards and measurements necessary for the various calibration techniques. (2). The advantages and disadvantages of each technique. (3). The mathematical manipulations that need to be applied to the measured standards and devices. (4). An outline of the steps needed for writing a calibration routine that operated from a remote computer. For further details of the various techniques presented in this note, the reader should consult the references

  12. Small Intestine Disorders

    Science.gov (United States)

    ... disease Crohn's disease Infections Intestinal cancer Intestinal obstruction Irritable bowel syndrome Ulcers, such as peptic ulcer Treatment of disorders of the small intestine depends on the cause.

  13. Electrical impedance tomography.

    Science.gov (United States)

    Costa, Eduardo L V; Lima, Raul Gonzalez; Amato, Marcelo B P

    2009-02-01

    Electrical impedance tomography (EIT) is a noninvasive, radiation-free monitoring tool that allows real-time imaging of ventilation. The purpose of this article is to discuss the fundamentals of EIT and to review the use of EIT in critical care patients. In addition to its established role in describing the distribution of alveolar ventilation, EIT has been shown to be a useful tool to detect lung collapse and monitor lung recruitment, both regionally and on a global basis. EIT has also been used to diagnose with high sensitivity incident pneumothoraces during mechanical ventilation. Additionally, with injection of hypertonic saline as a contrast agent, it is possible to estimate ventilation/perfusion distributions. EIT is cheap, noninvasive and allows continuous monitoring of ventilation. It is gaining acceptance as a valuable monitoring tool for the care of critical patients.

  14. Ultra-wideband impedance sensor

    Science.gov (United States)

    McEwan, T.E.

    1999-03-16

    The ultra-wideband impedance sensor (UWBZ sensor, or Z-sensor) is implemented in differential and single-ended configurations. The differential UWBZ sensor employs a sub-nanosecond impulse to determine the balance of an impedance bridge. The bridge is configured as a differential sample-and-hold circuit that has a reference impedance side and an unknown impedance side. The unknown impedance side includes a short transmission line whose impedance is a function of the near proximity of objects. The single-ended UWBZ sensor eliminates the reference side of the bridge and is formed of a sample and hold circuit having a transmission line whose impedance is a function of the near proximity of objects. The sensing range of the transmission line is bounded by the two-way travel time of the impulse, thereby eliminating spurious Doppler modes from large distant objects that would occur in a microwave CW impedance bridge. Thus, the UWBZ sensor is a range-gated proximity sensor. The Z-sensor senses the near proximity of various materials such as metal, plastic, wood, petroleum products, and living tissue. It is much like a capacitance sensor, yet it is impervious to moisture. One broad application area is the general replacement of magnetic sensors, particularly where nonferrous materials need to be sensed. Another broad application area is sensing full/empty levels in tanks, vats and silos, e.g., a full/empty switch in water or petroleum tanks. 2 figs.

  15. Impedance source power electronic converters

    CERN Document Server

    Liu, Yushan; Ge, Baoming; Blaabjerg, Frede; Ellabban, Omar; Loh, Poh Chiang

    2016-01-01

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding control methods. Presents the latest power conversion solutions that aim to advance the role of pow...

  16. Impedance Source Power Electronic Converters

    DEFF Research Database (Denmark)

    Liu, Yushan; Abu-Rub, Haitham; Ge, Baoming

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable...... and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key...... features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding...

  17. Intra-luminal exposure of murine airways to peroxynitrite causes inflammation but not hyperresponsiveness

    NARCIS (Netherlands)

    Muijsers, RBR; van der Veeken, A; Habernickel, J; Folkerts, G; Postma, DS; Nijkamp, FP

    Objective and design: There is increasing evidence for the involvement of reactive nitrogen species like peroxynitrite (ONOO-) in airway pathology, for example during allergic airway inflammation. Therefore, the effect of peroxynitrite exposure on airway responsiveness and inflammation was studied.

  18. Electrical impedance of acupuncture meridians: the relevance of subcutaneous collagenous bands.

    Directory of Open Access Journals (Sweden)

    Andrew C Ahn

    2010-07-01

    Full Text Available The scientific basis for acupuncture meridians is unknown. Past studies have suggested that acupuncture meridians are physiologically characterized by low electrical impedance and anatomically associated with connective tissue planes. We are interested in seeing whether acupuncture meridians are associated with lower electrical impedance and whether ultrasound-derived measures--specifically echogenic collagenous bands--can account for these impedance differences.In 28 healthy subjects, we assessed electrical impedance of skin and underlying subcutaneous connective tissue using a four needle-electrode approach. The impedances were obtained at 10 kHz and 100 kHz frequencies and at three body sites - upper arm (Large Intestine meridian, thigh (Liver, and lower leg (Bladder. Meridian locations were determined by acupuncturists. Ultrasound images were obtained to characterize the anatomical features at each measured site. We found significantly reduced electrical impedance at the Large Intestine meridian compared to adjacent control for both frequencies. No significant decrease in impedance was found at the Liver or Bladder meridian. Greater subcutaneous echogenic densities were significantly associated with reduced impedances in both within-site (meridian vs. adjacent control and between-site (arm vs. thigh vs. lower leg analyses. This relationship remained significant in multivariable analyses which also accounted for gender, needle penetration depth, subcutaneous layer thickness, and other ultrasound-derived measures.Collagenous bands, represented by increased ultrasound echogenicity, are significantly associated with lower electrical impedance and may account for reduced impedances previously reported at acupuncture meridians. This finding may provide important insights into the nature of acupuncture meridians and the relevance of collagen in bioelectrical measurements.

  19. Impedance pneumography using textile electrodes.

    Science.gov (United States)

    Fiedler, P; Biller, S; Griebel, S; Haueisen, J

    2012-01-01

    The acquisition of physiological parameters using textile and textile-integrated sensors has become an important alternative for mobile and long-term monitoring. We analyzed to different commercially available electrically conductive textiles concerning their applicability for textile-based impedance pneumography. We immersed the textiles to four corroding solutions and observed no considerable changes in the absolute value as well as the phase shift of the material impedances. Subsequently, we performed impedance pneumography tests with different current amplitudes and frequencies. Using silver coated synthetic textile electrodes it was possible to detect the correct respiration frequency during normal, flat as well as slow, deep respiration.

  20. Impedance of electrochemically modified graphite.

    Science.gov (United States)

    Magdić, Katja; Kvastek, Krešimir; Horvat-Radošević, Višnja

    2014-01-01

    Electrochemical impedance spectroscopy, EIS, has been applied for characterization of electrochemically modified graphite electrodes in the sulphuric acid solution. Graphite modifications were performed by potential cyclization between potentials of graphite oxide formation/reduction, different number of cycles, and prolonged reduction steps after cyclization. Impedance spectra measured at two potential points within double-layer region of graphite have been successfully modeled using the concept of porous electrodes involving two different electrolyte diffusion paths, indicating existence of two classes of pores. The evaluated impedance parameter values show continuous changes with stages of graphite modification, indicating continuous structural changes of pores by number of potential cycles applied. Differences of impedance parameter values at two potential values indicate the potential induced changes of solution properties within the pores of modified graphite.

  1. Small Signal Loudspeaker Impedance Emulator

    DEFF Research Database (Denmark)

    Iversen, Niels Elkjær; Knott, Arnold

    2014-01-01

    Specifying the performance of audio amplifiers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterized by the mechanical resonance between the mass of the diaphragm and the compliance of its suspension which vary f...... to emulate the loudspeaker impedance with an electric circuit and that its resonance frequency can be changed by tuning two resistors....

  2. Beam-beam and impedance

    CERN Document Server

    White, S.

    2014-07-17

    As two counter-rotating beams interact they can give rise to coherent dipole modes. Under the influence of impedance these coherent beam-beam modes can couple to higher order head-tail modes and lead to strong instabilities. A fully self-consistent approach including beam-beam and impedance was used to characterize this new coupled mode instability and study possible cures such as a transverse damper and high chromaticity.

  3. Intestinal pseudo-obstruction

    Science.gov (United States)

    Primary intestinal pseudo-obstruction; Acute colonic ileus; Colonic pseudo-obstruction; Idiopathic intestinal pseudo-obstruction; Ogilvie syndrome; Chronic intestinal pseudo-obstruction; Paralytic ileus - pseudo-obstruction

  4. Intestinal myiasis

    Directory of Open Access Journals (Sweden)

    U S Udgaonkar

    2012-01-01

    Full Text Available Purpose: Intestinal myiasis is a condition when the fly larvae inhabit the gastrointestinal tract and are passed out in faeces. This type of infestation results when eggs or larvae of the fly, deposited on food are inadvertently taken by man. They survive the unfavourable conditions within the gastrointestinal tract and produce disturbances, which may vary from mild to severe. The condition is not uncommon and is often misdiagnosed as pinworm infestation. Correct diagnosis by the clinical microbiologist is important to avoid unnecessary treatment. Materials and Methods: We had 7 cases of intestinal myiasis. In 2 cases the larvae were reared to adult fly in modified meat and sand medium (developed by Udgaonkar. This medium is simple and can be easily prepared in the laboratory. Results: Of the 7 larvae, 5 were Sarcophaga haemorrhoidalis, 1 Megaselia species and 1 was identified as Muscina stabulans. Conclusions: S. haemorrhoidalis was the commonest maggot involved. A high index of suspicion is required for clinical diagnosis when the patient complains of passing wriggling worms in faeces for a long period without any response to antihelminthics. The reason for long duration of illness and recurrence of infestation is baffling. The nearest to cure was colonic wash. We feel prevention is of utmost importance, which is to avoid eating food articles with easy access to flies.

  5. Intestinal Failure (Short Bowel Syndrome)

    Science.gov (United States)

    Intestinal Failure (Short Bowel Syndrome) What is intestinal failure? Intestinal failure occurs when a significant portion of the small ... intestine does. Who is at risk for intestinal failure? N Babies (usually premature) who have had surgery ...

  6. A-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Galigekere, Veda Prakash

    2016-01-01

    A novel A-source impedance network is proposed in this letter. The A-source impedance network uses an autotransformer for realizing converters for any application that demand a very high dc voltage gain. The network utilizes a minimal turns ratio compared to other Magnetically Coupled Impedance S...... with an example single-switch 400 W dc-dc converter. For the closed-loop control design and stability assessment, a small signal model and its analysis of the proposed network are also presented in brief....... Source (MCIS) networks to attain a high voltage gain. In addition, the proposed converter draws a continuous current from the source, and hence it is suitable for many types of renewable energy sources. The derived network expressions and theoretical analysis are finally validated experimentally...

  7. Acoustic impedances of ear canals measured by impedance tube

    DEFF Research Database (Denmark)

    Ciric, Dejan; Hammershøi, Dorte

    2007-01-01

    During hearing sensitivity tests, the sound field is commonly generated by an earphone placed on a subject ear. One of the factors that can affect the sound transmission in the ear is the acoustic impedance of the ear canal. Its importance is related to the contribution of other elements involved...

  8. Microfabricated Thin Film Impedance Sensor & AC Impedance Measurements

    Science.gov (United States)

    Yu, Jinsong; Liu, Chung-Chiun

    2010-01-01

    Thin film microfabrication technique was employed to fabricate a platinum based parallel-electrode structured impedance sensor. Electrochemical impedance spectroscopy (EIS) and equivalent circuit analysis of the small amplitude (±5 mV) AC impedance measurements (frequency range: 1 MHz to 0.1 Hz) at ambient temperature were carried out. Testing media include 0.001 M, 0.01 M, 0.1 M NaCl and KCl solutions, and alumina (∼3 μm) and sand (∼300 μm) particulate layers saturated with NaCl solutions with the thicknesses ranging from 0.6 mm to 8 mm in a testing cell, and the results were used to assess the effect of the thickness of the particulate layer on the conductivity of the testing solution. The calculated resistances were approximately around 20 MΩ, 4 MΩ, and 0.5 MΩ for 0.001 M, 0.01 M, and 0.1 M NaCl solutions, respectively. The presence of the sand particulates increased the impedance dramatically (6 times and 3 times for 0.001 M and 0.1 M NaCl solutions, respectively). A cell constant methodology was also developed to assess the measurement of the bulk conductivity of the electrolyte solution. The cell constant ranged from 1.2 to 0.8 and it decreased with the increase of the solution thickness. PMID:22219690

  9. Short-circuit impedance measurement

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen; Nielsen, Arne Hejde; Poulsen, Niels Kjølstad

    2003-01-01

    Methods for estimating the short-circuit impedance in the power grid are investigated for various voltage levels and situations. The short-circuit impedance is measured, preferably from naturally occurring load changes in the grid, and it is shown that such a measurement system faces different...... kinds of problems at different locations in the grid. This means that the best measurement methodology changes depending on the location in the grid. Three typical examples with different measurement problems at 400 kV, 132 kV and 400 V voltage level are discussed....

  10. Y-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Loh, Poh Chiang; Blaabjerg, Frede

    2014-01-01

    This letter introduces a new versatile Y-shaped impedance network for realizing converters that demand a very high-voltage gain, while using a small duty ratio. To achieve that, the proposed network uses a tightly coupled transformer with three windings, whose obtained gain is presently not matched...... by existing networks operated at the same duty ratio. The proposed impedance network also has more degrees of freedom for varying its gain, and hence, more design freedom for meeting requirements demanded from it. This capability has been demonstrated by mathematical derivation, and proven in experiment...

  11. Hybrid-Source Impedance Networks

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang

    2010-01-01

    Hybrid-source impedance networks have attracted attention among researchers because of their flexibility in performing buck-boost energy conversion. To date, three distinct types of impedance networks can be summarized for implementing voltage-type inverters with another three types summarized...... the cascaded networks would have a higher output voltage gain and other unique advantages that currently have not been investigated yet. It is anticipated that these advantages would help the formed inverters find applications in photovoltaic and other renewable systems, where a high voltage gain is usually...

  12. Electrochemical properties and electrochemical impedance ...

    African Journals Online (AJOL)

    Polypyrrole (PPy) films of different thickness were characterized by electrochemical impedance spectroscopy (EIS) measurements in acetonitrile and aqueous solutions, containing 0.1 M NaClO4 or sodium dodecylsulfate as the dopant. The PPy films were electrochemically deposited on Pt, and their electrochemical ...

  13. Small Signal Loudspeaker Impedance Emulator

    DEFF Research Database (Denmark)

    Iversen, Niels Elkjær; Knott, Arnold

    2014-01-01

    Specifying the performance of audio amplifiers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterized by the mechanical resonance between the mass of the diaphragm and the compliance of its suspension which vary...

  14. Impedance measurements in the biomedical sciences.

    Science.gov (United States)

    Coffman, Frederick D; Cohen, Stanley

    2013-01-01

    Biological organisms and their component organs, tissues and cells have unique electrical impedance properties. Impedance properties often change with changes in structure, composition, and metabolism, and can be indicative of the onset and progression of disease states. Over the past 100 years, instruments and analytical methods have been developed to measure the impedance properties of biological specimens and to utilize these measurements in both clinical and basic science settings. This chapter will review the applications of impedance measurements in the biomedical sciences, from whole body analysis to impedance measurements of single cells and cell monolayers, and how cellular impedance measuring instruments can now be used in high throughput screening applications.

  15. Macrophages in intestinal homeostasis and inflammation

    Science.gov (United States)

    Bain, Calum C; Mowat, Allan McI

    2014-01-01

    The intestine contains the largest pool of macrophages in the body which are essential for maintaining mucosal homeostasis in the face of the microbiota and the constant need for epithelial renewal but are also important components of protective immunity and are involved in the pathology of inflammatory bowel disease (IBD). However, defining the biological roles of intestinal macrophages has been impeded by problems in defining the phenotype and origins of different populations of myeloid cells in the mucosa. Here, we discuss how multiple parameters can be used in combination to discriminate between functionally distinct myeloid cells and discuss the roles of macrophages during homeostasis and how these may change when inflammation ensues. We also discuss the evidence that intestinal macrophages do not fit the current paradigm that tissue-resident macrophages are derived from embryonic precursors that self-renew in situ, but require constant replenishment by blood monocytes. We describe our recent work demonstrating that classical monocytes constantly enter the intestinal mucosa and how the environment dictates their subsequent fate. We believe that understanding the factors that drive intestinal macrophage development in the steady state and how these may change in response to pathogens or inflammation could provide important insights into the treatment of IBD. PMID:24942685

  16. Reducing the SPS Machine Impedance

    CERN Document Server

    Collier, Paul; Guinand, R; Jiménez, J M; Rizzo, A; Spinks, Alan; Weiss, K

    2002-01-01

    The SPS as LHC Injector project has been working for some time to prepare the SPS for its role as final injector for the LHC. This included major work related to injection, acceleration, extraction and beam instrumentation for the LHC beams [1]. Measurements carried out with the high brightness LHC beam showed that a major improvement of the machine impedance would also be necessary [2]. In addition to removing all lepton related components (once LEP operation ended in 2000), the decision was made to shield the vacuum system pumping port cavities. These accidental cavities had been identified as having characteristic frequencies in the 1-1.5GHz range. Since the SPS vacuum system contains roughly 1000 of these cavities, they constitute a major fraction of the machine impedance. As removal of the ports and associated bellows is not possible, transition shields (PPS) had to be designed to insert within the pumping port cavities.

  17. Tapping mode microwave impedance microscopy

    KAUST Repository

    Lai, K.

    2009-01-01

    We report tapping mode microwave impedance imaging based on atomic force microscope platforms. The shielded cantilever probe is critical to localize the tip-sample interaction near the tip apex. The modulated tip-sample impedance can be accurately simulated by the finite-element analysis and the result agrees quantitatively to the experimental data on a series of thin-film dielectric samples. The tapping mode microwave imaging is also superior to the contact mode in that the thermal drift in a long time scale is totally eliminated and an absolute measurement on the dielectric properties is possible. We demonstrated tapping images on working nanodevices, and the data are consistent with the transport results. © 2009 American Institute of Physics.

  18. Impedance-matched Marx generators

    Directory of Open Access Journals (Sweden)

    W. A. Stygar

    2017-04-01

    Full Text Available We have conceived a new class of prime-power sources for pulsed-power accelerators: impedance-matched Marx generators (IMGs. The fundamental building block of an IMG is a brick, which consists of two capacitors connected electrically in series with a single switch. An IMG comprises a single stage or several stages distributed axially and connected in series. Each stage is powered by a single brick or several bricks distributed azimuthally within the stage and connected in parallel. The stages of a multistage IMG drive an impedance-matched coaxial transmission line with a conical center conductor. When the stages are triggered sequentially to launch a coherent traveling wave along the coaxial line, the IMG achieves electromagnetic-power amplification by triggered emission of radiation. Hence a multistage IMG is a pulsed-power analogue of a laser. To illustrate the IMG approach to prime power, we have developed conceptual designs of two ten-stage IMGs with LC time constants on the order of 100 ns. One design includes 20 bricks per stage, and delivers a peak electrical power of 1.05 TW to a matched-impedance 1.22-Ω load. The design generates 113 kV per stage and has a maximum energy efficiency of 89%. The other design includes a single brick per stage, delivers 68 GW to a matched-impedance 19-Ω load, generates 113 kV per stage, and has a maximum energy efficiency of 90%. For a given electrical-power-output time history, an IMG is less expensive and slightly more efficient than a linear transformer driver, since an IMG does not use ferromagnetic cores.

  19. Impedance-matched Marx generators

    Science.gov (United States)

    Stygar, W. A.; LeChien, K. R.; Mazarakis, M. G.; Savage, M. E.; Stoltzfus, B. S.; Austin, K. N.; Breden, E. W.; Cuneo, M. E.; Hutsel, B. T.; Lewis, S. A.; McKee, G. R.; Moore, J. K.; Mulville, T. D.; Muron, D. J.; Reisman, D. B.; Sceiford, M. E.; Wisher, M. L.

    2017-04-01

    We have conceived a new class of prime-power sources for pulsed-power accelerators: impedance-matched Marx generators (IMGs). The fundamental building block of an IMG is a brick, which consists of two capacitors connected electrically in series with a single switch. An IMG comprises a single stage or several stages distributed axially and connected in series. Each stage is powered by a single brick or several bricks distributed azimuthally within the stage and connected in parallel. The stages of a multistage IMG drive an impedance-matched coaxial transmission line with a conical center conductor. When the stages are triggered sequentially to launch a coherent traveling wave along the coaxial line, the IMG achieves electromagnetic-power amplification by triggered emission of radiation. Hence a multistage IMG is a pulsed-power analogue of a laser. To illustrate the IMG approach to prime power, we have developed conceptual designs of two ten-stage IMGs with L C time constants on the order of 100 ns. One design includes 20 bricks per stage, and delivers a peak electrical power of 1.05 TW to a matched-impedance 1.22 -Ω load. The design generates 113 kV per stage and has a maximum energy efficiency of 89%. The other design includes a single brick per stage, delivers 68 GW to a matched-impedance 19 -Ω load, generates 113 kV per stage, and has a maximum energy efficiency of 90%. For a given electrical-power-output time history, an IMG is less expensive and slightly more efficient than a linear transformer driver, since an IMG does not use ferromagnetic cores.

  20. Impedance analysis of acupuncture points and pathways

    International Nuclear Information System (INIS)

    Teplan, Michal; Kukucka, Marek; Ondrejkovicová, Alena

    2011-01-01

    Investigation of impedance characteristics of acupuncture points from acoustic to radio frequency range is addressed. Discernment and localization of acupuncture points in initial single subject study was unsuccessfully attempted by impedance map technique. Vector impedance analyses determined possible resonant zones in MHz region.

  1. Electrical Impedance Tomography of Breast Cancer

    Science.gov (United States)

    2004-06-01

    Algorithm in Magnetic Resonance Electrical Impedance Tomography (MREIT): Phantom Experiment for Static Resistivity Images," IEEE Trans. on Medical Imaging...Tomography MREIT: Magnetic Resonance Electrical Impedance Tomography FEM: Finite Element Method EIS: Electrical Impedance Scanning OPAMP : Operational...transconductance amplifier was designed and built using three LM741 OPAMP circuits to convert the voltage from the signal generator into a current

  2. A spatial impedance controller for robotic manipulation

    NARCIS (Netherlands)

    Fasse, Ernest D.; Fasse, Ernest; Broenink, Johannes F.

    1997-01-01

    Mechanical impedance is the dynamic generalization of stiffness, and determines interactive behavior by definition. Although the argument for explicitly controlling impedance is strong, impedance control has had only a modest impact on robotic manipulator control practice. This is due in part to the

  3. Impedance analysis of acupuncture points and pathways

    Science.gov (United States)

    Teplan, Michal; Kukučka, Marek; Ondrejkovičová, Alena

    2011-12-01

    Investigation of impedance characteristics of acupuncture points from acoustic to radio frequency range is addressed. Discernment and localization of acupuncture points in initial single subject study was unsuccessfully attempted by impedance map technique. Vector impedance analyses determined possible resonant zones in MHz region.

  4. Electrical impedance tomography: topology optimization

    International Nuclear Information System (INIS)

    Miranda, Lenine Campos

    2013-01-01

    The Electrical Impedance Tomography (EIT) is a study of body parts who use electric current. Is studied through computers resistance or conductivity of these parts, producing an image used for medical diagnosis. A body is wrapped in a blanket placed with small electrodes and receivers of electric current, potential difference. Based on data obtained from a series of measurements at the electrodes, one by one, sending and receiving, you can perform a numerical phantom, where each 'voxel' of the image formed computationally represents the impedance of biological tissue. In Brazil, studies on electrical impedance tomography (EIT) has not yet started. Such equipment are measured tensions - potential difference - between each electrode / sensor one by one, as a way to Simple Combinatorial Analysis. The sequence and the way it is measured strains are in the final image quality. Finite Element Method Interactive, whose algorithm is based on Dialectical Method. We use an initial function with the objective of maximizing the data quantitatively, for better qualitative analysis. Topology Optimization methods are used to improve the image reconstruction. Currently the study is quite primitive related to the theory that shows how to power the new science studied. The high quality images requires a difficulty in obtaining. This work is not intended for detailed for analysis in any tissue or organ specific, but in general terms. And the formation of the 2D image. 3D need a reconstructor to part. (author)

  5. Intestinal microbiome landscaping

    NARCIS (Netherlands)

    Shetty, Sudarshan A.; Hugenholtz, Floor; Lahti, Leo; Smidt, Hauke; Vos, de Willem M.

    2017-01-01

    High individuality, large complexity and limited understanding of the mechanisms underlying human intestinal microbiome function remain the major challenges for designing beneficial modulation strategies. Exemplified by the analysis of intestinal bacteria in a thousand Western adults, we discuss

  6. Small Intestine Cancer Treatment

    Science.gov (United States)

    ... all of an organ that contains cancer. The resection may include the small intestine and nearby organs (if the cancer has spread). The doctor may remove the section of the small intestine that contains cancer and perform an anastomosis (joining the cut ends of the intestine together). ...

  7. Observations involving broadband impedance modelling

    International Nuclear Information System (INIS)

    Berg, J.S.

    1995-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impendance. This paper discusses three aspects of broadband impendance modeling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f cavity. The last is a discussion of requirements for the mathematical form of an impendance which follow from the general properties of impendances

  8. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2003-10-01

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  9. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2004-02-01

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  10. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2003-04-01

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a thin film sensor conformal with the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is capacitively coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD

  11. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2003-01-30

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a thin film sensor conformal with the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is capacitively coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD

  12. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba; Christopher J. Ziolkowski

    2005-01-17

    This project aimed at developing a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GTI. GTI proposed to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or non-metallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment

  13. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2002-11-27

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a thin film sensor conformal with the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is capacitively coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD

  14. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2004-05-03

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  15. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba; Christopher J. Ziolkowski

    2004-06-30

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  16. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba; Christopher J. Ziolkowski

    2004-10-29

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or non-metallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  17. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2002-08-30

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a thin film sensor conformal with the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is capacitively coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD

  18. Spheromak Impedance and Current Amplification

    International Nuclear Information System (INIS)

    Fowler, T K; Hua, D D; Stallard, B W

    2002-01-01

    It is shown that high current amplification can be achieved only by injecting helicity on the timescale for reconnection, τ REC , which determines the effective impedance of the spheromak. An approximate equation for current amplification is: dI TOR 2 /dt ∼ I 2 /τ REC - I TOR 2 /τ closed where I is the gun current, I TOR is the spheromak toroidal current and τ CLOSED is the ohmic decay time of the spheromak. Achieving high current amplification, I TOR >> I, requires τ REC CLOSED . For resistive reconnection, this requires reconnection in a cold zone feeding helicity into a hot zone. Here we propose an impedance model based on these ideas in a form that can be implemented in the Corsica-based helicity transport code. The most important feature of the model is the possibility that τ REC actually increases as the spheromak temperature increases, perhaps accounting for the ''voltage sag'' observed in some experiments, and a tendency toward a constant ratio of field to current, B ∝ I, or I TOR ∼ I. Program implications are discussed

  19. Pumping slots: impedances and power losses

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S. [Maryland Univ., College Park, MD (United States). Dept. of Physics

    1996-08-01

    Contributions of pumping slots to the beam coupling impedances and power losses in a B-factory ring are considered. While their leading contribution is to the inductive impedance, for high-intensity machines with short bunches like e{sup +}e{sup -} B-factories the real part of the impedance and related loss factors are also important. Using an analytical approach we calculate the coupling impedances and loss factors due to slots in a ring with an arbitrary cross section of the vacuum chamber. Effects of the slot tilt on the beam impedance are also considered, and restrictions on the tilt angle are derived from limitations on the impedance increase. The power leakage through the slots is discussed briefly. The results are applied to the KEK B-factory. (author)

  20. Impedance studies on Li-ion cathodes

    Energy Technology Data Exchange (ETDEWEB)

    NAGASUBRAMANIAN, GANESAN

    2000-04-17

    This paper describes the author's 2- and 3-electrode impedance results of metal oxide cathodes. These results were extracted from impedance data on 18650 Li-ion cells. The impedance results indicate that the ohmic resistance of the cell is very nearly constant with state-of-charge (SOC) and temperature. For example, the ohmic resistance of 18650 Li-ion cells is around 60 m{Omega} for different SOCS (4.1V to 3.0V) and temperatures from 35 C to {minus}20 C. However, the interfacial impedance shows a modest increase with SOC and a huge increase of between 10 and 100 times with decreasing temperature. For example, in the temperature regime (35 C down to {minus}20 C) the overall cell impedance has increased from nearly 200 m{Omega} to 8,000 m{Omega}. Most of the increase in cell impedance comes from the metal oxide cathode/electrolyte interface.

  1. Electrical impedance tomography of electrolysis.

    Directory of Open Access Journals (Sweden)

    Arie Meir

    Full Text Available The primary goal of this study is to explore the hypothesis that changes in pH during electrolysis can be detected with Electrical Impedance Tomography (EIT. The study has relevance to real time control of minimally invasive surgery with electrolytic ablation. To investigate the hypothesis, we compare EIT reconstructed images to optical images acquired using pH-sensitive dyes embedded in a physiological saline agar gel phantom treated with electrolysis. We further demonstrate the biological relevance of our work using a bacterial E.Coli model, grown on the phantom. The results demonstrate the ability of EIT to image pH changes in a physiological saline phantom and show that these changes correlate with cell death in the E.coli model. The results are promising, and invite further experimental explorations.

  2. Electrical Impedance Tomography of Electrolysis

    Science.gov (United States)

    Meir, Arie; Rubinsky, Boris

    2015-01-01

    The primary goal of this study is to explore the hypothesis that changes in pH during electrolysis can be detected with Electrical Impedance Tomography (EIT). The study has relevance to real time control of minimally invasive surgery with electrolytic ablation. To investigate the hypothesis, we compare EIT reconstructed images to optical images acquired using pH-sensitive dyes embedded in a physiological saline agar gel phantom treated with electrolysis. We further demonstrate the biological relevance of our work using a bacterial E.Coli model, grown on the phantom. The results demonstrate the ability of EIT to image pH changes in a physiological saline phantom and show that these changes correlate with cell death in the E.coli model. The results are promising, and invite further experimental explorations. PMID:26039686

  3. Gastric and intestinal surgery.

    Science.gov (United States)

    Fossum, Theresa W; Hedlund, Cheryl S

    2003-09-01

    Gastric surgery is commonly performed to remove foreign bodies and correct gastric dilatation-volvulus and is less commonly performed to treat gastric ulceration or erosion, neoplasia, and benign gastric outflow obstruction. Intestinal surgery, although commonly performed by veterinarians, should never be considered routine. The most common procedures of the small intestinal tract performed in dogs and cats include enterotomy and resection/anastomosis. Surgery of the large intestine is indicated for lesions causing obstruction, perforations, colonic inertia, or chronic inflammation.

  4. Intestinal parasites and tuberculosis

    Directory of Open Access Journals (Sweden)

    Anuar Alonso Cedeño-Burbano

    2017-10-01

    Conclusions: The available evidence was insufficient to affirm that intestinal parasites predispose to developing tuberculous. The studies carried out so far have found statistically insignificant results.

  5. High temperature impedance spectroscopy of barium stannate ...

    Indian Academy of Sciences (India)

    ... differential thermal analysis, thermogravimetric analysis and Fourier transform infrared techniques. Electrical properties were studied using a.c. impedance spectroscopy technique in the temperature range of 50–650 °C and frequency range of 10 Hz–13 MHz. The complex impedance plots at temperature ≥ 300 °C show ...

  6. Battery impedance spectroscopy using bidirectional grid connected ...

    Indian Academy of Sciences (India)

    The converter is grid connected and controlled to operate at unity power factor. Additional requirements on filter design and control structure of battery converter for impedance measurement are discussed. An algorithm has been developed to measure impedance by frequency sweep, avoiding transients. The measured ...

  7. High temperature impedance spectroscopy of barium stannate

    Indian Academy of Sciences (India)

    ... differential thermal analysis, thermogravimetric analysis and Fourier transform infrared techniques. Electrical properties were studied using a.c. impedance spectroscopy technique in the temperature range of 50–650 °C and frequency range of 10 Hz–13 MHz. The complex impedance plots at temperature ≥ 300 °C show ...

  8. Impedance of a slotted-pipe kicker

    Energy Technology Data Exchange (ETDEWEB)

    Feng Zhou [Academia Sinica, Beijing, BJ (China). Inst. of High Energy Physics

    1996-08-01

    This paper introduces the principle of a new slotted kicker simply, which is made by using vacuum pipe itself with proper slits as current conductors, and then, presents a rough estimation of its longitudinal and transverse impedance, respectively. Calculation shows that its impedance is reduced significantly compared to our present air-coil kicker. (author)

  9. Estimating the short-circuit impedance

    DEFF Research Database (Denmark)

    Nielsen, Arne Hejde; Pedersen, Knud Ole Helgesen; Poulsen, Niels Kjølstad

    1997-01-01

    through a RLS-algorithm. The algorithms have been tested and implemented on a PC at a 132 kV substation supplying a rolling mill. Knowing the short-circuit impedance gives the rolling mill an opportunity to adjust the arc furnace operation to keep flicker below a certain level. Therefore, the PC performs...... a simultaneously measurement of impedance and flicker....

  10. Segmental bioelectrical impedance analysis: an update.

    Science.gov (United States)

    Ward, Leigh C

    2012-09-01

    Bioelectrical impedance analysis is a popular, noninvasive and practical method for assessment of body composition. The last decade has seen the development of impedance analyzers designed to assess the composition of body segments as well as the whole body. This review outlines the theoretical basis for segmental impedance analysis, validity and use in practice. Segmental impedance analysis tends to underestimate fat-free mass and overestimate fat mass when compared to reference techniques, although the magnitude of these differences can be small. Performance is improved with population-specific prediction equations; algorithms in-built into instrument firmware should not be relied upon. Prediction of whole-body composition from the sum of the individual segments, although theoretically preferable, shows little advantage over whole body wrist to ankle impedance approaches. Prediction of appendicular skeletal muscle mass, although promising, requires further research. The use of measured impedance data directly as indices of composition, rather than for prediction, has not found extensive application in nutritional research despite its success in other fields. Segmental bioimpedance techniques have advanced substantially in recent years due to availability of simple-to-use analyzers and simplified measurement protocols. The method has been well validated and increasingly adopted in nutritional and clinical practice. Segmental impedance, like conventional whole body impedance approaches, provides indirect prediction of body composition whose accuracy is yet to achieve that of reference techniques such as magnetic reference imaging. This lack of accuracy, however, is outweighed by the method's practicality of use in many settings.

  11. Battery impedance spectroscopy using bidirectional grid connected ...

    Indian Academy of Sciences (India)

    Battery impedance can provide valuable insight into the condition of the battery. Commercially available impedance measurement instruments are expensive. Hence their direct use in a battery management system is not justifiable. In this work, a 3-kW bi-directional converter for charging and discharging a batterybank has ...

  12. Impedance of finite length resistive cylinder

    Directory of Open Access Journals (Sweden)

    S. Krinsky

    2004-11-01

    Full Text Available We determine the impedance of a cylindrical metal tube (resistor of radius a, length g, and conductivity σ attached at each end to perfect conductors of semi-infinite length. Our main interest is in the asymptotic behavior of the impedance at high frequency (k≫1/a. In the equilibrium regime, ka^{2}≪g, the impedance per unit length is accurately described by the well-known result for an infinite length tube with conductivity σ. In the transient regime, ka^{2}≫g, where the contribution of transition radiation arising from the discontinuity in conductivity is important, we derive an analytic expression for the impedance and compute the short-range wakefield. The analytic results are shown to agree with numerical evaluation of the impedance.

  13. Fractional Order Element Based Impedance Matching

    KAUST Repository

    Radwan, Ahmed Gomaa

    2014-06-24

    Disclosed are various embodiments of methods and systems related to fractional order element based impedance matching. In one embodiment, a method includes aligning a traditional Smith chart (|.alpha.|=1) with a fractional order Smith chart (|.alpha.|.noteq.1). A load impedance is located on the traditional Smith chart and projected onto the fractional order Smith chart. A fractional order matching element is determined by transitioning along a matching circle of the fractional order Smith chart based at least in part upon characteristic line impedance. In another embodiment, a system includes a fractional order impedance matching application executed in a computing device. The fractional order impedance matching application includes logic that obtains a first set of Smith chart coordinates at a first order, determines a second set of Smith chart coordinates at a second order, and determines a fractional order matching element from the second set of Smith chart coordinates.

  14. Impedance Spectroscopy of Dielectrics and Electronic Conductors

    DEFF Research Database (Denmark)

    Bonanos, Nikolaos; Pissis, Polycarpos; Macdonald, J. Ross

    2013-01-01

    Impedance spectroscopy is used for the characterization of materials, such as electroceramics, solid and liquid electrochemical cells, dielectrics and also fully integrated devices, such as fuel cells. It consists of measuring the electrical impedance - or a closely related property, such as admi......Impedance spectroscopy is used for the characterization of materials, such as electroceramics, solid and liquid electrochemical cells, dielectrics and also fully integrated devices, such as fuel cells. It consists of measuring the electrical impedance - or a closely related property......, and procedures for the correction of measurement errors. The applications of impedance spectroscopy are illustrated with examples from electroceramics and polymer-based dielectric systems. The way in which the technique is applied to the two classes of materials is compared with reference to the different models...

  15. Thoracic impedance change equation deduced on the basis of parallel impedance model and Ohm's law.

    Science.gov (United States)

    Qiu-Jin, Xiao; Zhen, Wang; Ming-Xing, Kuang; Ping, Wen; Pei, Liu; Jian-Feng, Ji

    2012-02-01

    The aim of the present study is to investigate an impedance change equation suited with the measurement of the impedance cardiograph (ICG). Based on a parallel impedance model and Ohm's law, an impedance change equation differed from Nyboer's equation is deduced. It is verified with the experiments of the impedance cardiography in 100 healthy adults. This equation shows that the thoracic impedance change (ΔZ) is directly proportional to the value of the volume change (ΔV) of the blood vessel, to the ratio of the basic impedance to the body height (Z(0)/H), while it is inversely proportional to the square of the chest circumference (C(t) (2)). These are supported by the experimental results in the measurement of the ICG. The equation proposed in the present paper is coincident with the actual condition in the measurement of the ICG.

  16. adhesive intestinal obstruction

    African Journals Online (AJOL)

    2006-06-01

    Jun 1, 2006 ... ABSTRACT. Background: Adhesions after abdominal and pelvic surgery are a major cause of intestinal obstruction in the western world and the pathology is steadily gaining prominence in our practice. Objective: To determine the magnitude of adhesive intestinal obstruction; to determine the types.

  17. Intestinal Barrier and Behavior.

    Science.gov (United States)

    Julio-Pieper, M; Bravo, J A

    2016-01-01

    The intestinal barrier function contributes to gut homeostasis by modulating absorption of water, electrolytes, and nutrients from the lumen into the circulation while restricting the passage of noxious luminal substances and microorganisms. Chronic conditions such as rheumatoid arthritis, inflammatory bowel disease, and celiac disease are associated to intestinal barrier dysfunction. Here, the hypothesis is that a leaky intestinal wall allowing for indiscriminate passage of intraluminal compounds to the vascular compartment could in turn lead to systemic inflammation. An increasing number of studies are now investigating the association between gut permeability and CNS disorders, under the premise that translocation of intestinal luminal contents could affect CNS function, either directly or indirectly. Still, it is unknown whether disruption of intestinal barrier is a causative agent or a consequence in these situations. Here, we discuss the latest evidence pointing to an association between increased gut permeability and disrupted behavioral responses. © 2016 Elsevier Inc. All rights reserved.

  18. Tracking of electrochemical impedance of batteries

    Science.gov (United States)

    Piret, H.; Granjon, P.; Guillet, N.; Cattin, V.

    2016-04-01

    This paper presents an evolutionary battery impedance estimation method, which can be easily embedded in vehicles or nomad devices. The proposed method not only allows an accurate frequency impedance estimation, but also a tracking of its temporal evolution contrary to classical electrochemical impedance spectroscopy methods. Taking into account constraints of cost and complexity, we propose to use the existing electronics of current control to perform a frequency evolutionary estimation of the electrochemical impedance. The developed method uses a simple wideband input signal, and relies on a recursive local average of Fourier transforms. The averaging is controlled by a single parameter, managing a trade-off between tracking and estimation performance. This normalized parameter allows to correctly adapt the behavior of the proposed estimator to the variations of the impedance. The advantage of the proposed method is twofold: the method is easy to embed into a simple electronic circuit, and the battery impedance estimator is evolutionary. The ability of the method to monitor the impedance over time is demonstrated on a simulator, and on a real Lithium ion battery, on which a repeatability study is carried out. The experiments reveal good tracking results, and estimation performance as accurate as the usual laboratory approaches.

  19. Identification of irradiated potatoes by impedance

    International Nuclear Information System (INIS)

    Singh, Rita; Singh, Antaryami; Wadhawan, A.K.

    1997-01-01

    The electrical impedance of potatoes irradiated at 60, 90, 150 and 1000 Gy was measured using various frequencies of alternating current. The impedance of the irradiated potatoes was higher than the unirradiated potatoes particularly in the frequency range of 100 Hz to 10 kHz. The ratio of the impedance at 5 kHz to that at 50 Hz (Z5k/Z50) was found to be the best indicator for detection of radiation treatment. (author). 4 refs., 2 figs

  20. Wearable impedance monitoring system for dialysis patients.

    Science.gov (United States)

    Bonnet, S; Bourgerette, A; Gharbi, S; Rubeck, C; Arkouche, W; Massot, B; McAdams, E; Montalibet, A; Jallon, P

    2016-08-01

    This paper describes the development and the validation of a prototype wearable miniaturized impedance monitoring system for remote monitoring in home-based dialysis patients. This device is intended to assess the hydration status of dialysis patients using calf impedance measurements. The system is based on the low-power AD8302 component. The impedance calibration procedure is described together with the Cole parameter estimation and the hydric volume estimation. Results are given on a test cell to validate the design and on preliminary calf measurements showing Cole parameter variations during hemodialysis.

  1. RHIC ABORT KICKER WITH REDUCED COUPLING IMPEDANCE

    International Nuclear Information System (INIS)

    HAHN, H.; DAVINO, D.

    2002-01-01

    Kicker magnets typically represent the most important contributors to the transverse impedance budget of accelerators and storage rings. Methods of reducing the impedance value of the SNS extraction kicker presently under construction and, in view of a future performance upgrade, that of the RHIC abort kicker have been thoroughly studied at this laboratory. In this paper, the investigation of a potential improvement from using ferrite different from the BNL standard CMD5005 is reported. Permeability measurements of several ferrite types have been performed. Measurements on two kicker magnets using CMD5005 and C2050 suggest that the impedance of a magnet without external resistive damping, such as the RHIC abort kicker, would benefit

  2. Electrical Impedance Measurements of PZT Nanofiber Sensors

    Directory of Open Access Journals (Sweden)

    Richard Galos

    2017-01-01

    Full Text Available Electrical impedance measurements of PZT nanofiber sensors were performed using a variety of methods over a frequency spectrum ranging from DC to 1.8 GHz. The nanofibers formed by electrospinning with diameters ranging from 10 to 150 nm were collected and integrated into sensors using microfabrication techniques. Special matching circuits with ultrahigh input impedance were fabricated to produce low noise, measurable sensor outputs. Material properties including resistivity and dielectric constant are derived from the impedance measurements. The resulting material properties are also compared with those of individual nanofibers being tested using conductive AFM and Scanning Conductive Microscopy.

  3. Mycotoxins and the intestine

    Directory of Open Access Journals (Sweden)

    Leon Broom

    2015-12-01

    Full Text Available Fungal biochemical pathways can yield various compounds that are not considered to be necessary for their growth and are thus referred to as secondary metabolites. These compounds have been found to have wide ranging biological effects and include potent poisons (mycotoxins. Mycotoxins invariably contaminate crops and (thus animal feeds. The intestine is the key link between ingested mycotoxins and their detrimental effects on the animal. Effects on the intestine, or intestinal environment, and immune system have been reported with various mycotoxins. These effects are almost certainly occurring across species. Most, if not all, of the reported effects of mycotoxins are negative in terms of intestinal health, for example, decreased intestinal cell viability, reductions in short chain fatty acid (SCFA concentrations and elimination of beneficial bacteria, increased expression of genes involved in promoting inflammation and counteracting oxidative stress. This challenge to intestinal health will predispose the animal to intestinal (and systemic infections and impair efficient digestion and absorption of nutrients, with the associated effect on animal productivity.

  4. Impedance and collective effects in the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Gareyte, J. [European Organization for Nuclear Research, Geneva (Switzerland)

    1996-08-01

    After a review of the main LHC parameters, and a brief description of the RF and vacuum systems, the coupling impedances of the main machine elements are given, as well as the resulting thresholds for instabilities. (author)

  5. Modeling degradation in SOEC impedance spectra

    DEFF Research Database (Denmark)

    Jensen, Søren Højgaard; Hauch, Anne; Knibbe, Ruth

    2013-01-01

    Solid oxide cell (SOC) performance is limited by various processes. One way to investigate these processes is by electrochemical impedance spectroscopy. In order to quantify and characterize the processes, an equivalent circuit can be used to model the SOC impedance spectra (IS). Unfortunately......, the optimal equivalent circuit is often unknown and to complicate matters further, several processes contribute to the SOC impedance - making detailed process characterization difficult. In this work we analyze and model a series of IS measured during steam electrolysis operation of an SOC. During testing......, degradation is only observed in the Ni/YSZ electrode and not in the electrolyte or the LSM/YSZ electrode. A batch fit of the differences between the IS shows that a modified Gerischer element provides a better fit to the Ni/YSZ electrode impedance than the frequently used RQ element - albeit neither...

  6. Intestinal solute carriers

    DEFF Research Database (Denmark)

    Steffansen, Bente; Nielsen, Carsten Uhd; Brodin, Birger

    2004-01-01

    A large amount of absorptive intestinal membrane transporters play an important part in absorption and distribution of several nutrients, drugs and prodrugs. The present paper gives a general overview on intestinal solute carriers as well as on trends and strategies for targeting drugs and...... membrane transporters in the small intestine in order to increase oral bioavailabilities of drug or prodrug, the major influence on in vivo pharmacokinetics is suggested to be dose-dependent increase in bioavailability as well as prolonged blood circulation due to large capacity facilitated absorption...

  7. Intestinal solute carriers

    DEFF Research Database (Denmark)

    Steffansen, Bente; Nielsen, Carsten Uhd; Brodin, Birger

    2004-01-01

    membrane transporters in the small intestine in order to increase oral bioavailabilities of drug or prodrug, the major influence on in vivo pharmacokinetics is suggested to be dose-dependent increase in bioavailability as well as prolonged blood circulation due to large capacity facilitated absorption......A large amount of absorptive intestinal membrane transporters play an important part in absorption and distribution of several nutrients, drugs and prodrugs. The present paper gives a general overview on intestinal solute carriers as well as on trends and strategies for targeting drugs and...

  8. Small-signal Loudspeaker Impedance Emulator

    DEFF Research Database (Denmark)

    Knott, Arnold; Iversen, Niels Elkjær

    2014-01-01

    Specifying the performance of audio ampliers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterised by the mechanical resonance between the mass of the diaphragm and the compliance of its' suspension which vary fr...... the loudspeaker impedance with an electric circuit and that its' resonance frequency can be changed by tuning two resistors....

  9. Wave impedance retrieving via Bloch modes analysis

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Ha, S.; Sukhorukov, A.

    2011-01-01

    -ciples violation, like antiresonance behaviour with Im(ε) wave impedances by the surface and volume aver-aging of the electromagnetic field...... of the Bloch mode, respectively. Case studies prove that our ap-proach can determine material and wave effective parameters of lossy and lossless metamaterials. In some examples when the passivity is violated we made further analysis and showed that this is due to the failure of concept of impedance retrieving...

  10. Acoustic Impedance Measurement for Underground Surfaces.

    Science.gov (United States)

    Cockcroft, Paul William

    Available from UMI in association with The British Library. Requires signed TDF. This thesis investigates the measurement of acoustic impedance for surfaces likely to be found in underground coal mines. By introducing the concepts of industrial noise, the effects of noise on the ear and relevant legislation the need for the protection of workers can be appreciated. Representative acoustic impedance values are vital as input for existing computer models that predict sound levels in various underground environments. These enable the mining engineer to predict the noise level at any point within a mine in the vicinity of noisy machinery. The concepts of acoustic intensity and acoustic impedance are investigated and different acoustic impedance measurement techniques are detailed. The possible use of either an impedance tube or an intensity meter for these kinds of measurements are suggested. The problems with acoustic intensity and acoustic impedance measurements are discussed with reference to the restraints that an underground environment imposes on any measurement technique. The impedance tube method for work in an acoustics laboratory is shown and the theory explained, accompanied by a few representative results. The use of a Metravib intensity meter in a soundproof chamber to gain impedance values is explained in detail. The accompanying software for the analysis of the two measured pressure signals is shown as well as the actual results for a variety of test surfaces. The use of a Nagra IV-SJ tape recorder is investigated to determine the effect of recording on the measurement and subsequent analysis of the input signals, particularly with reference to the phase difference introduced between the two simultaneous pressure signals. The subsequent use of a Norwegian Electronic intensity meter, including a proposal for underground work, is shown along with results for tests completed with this piece of equipment. Finally, recommendations are made on how to link up

  11. Analysis of impedance measurements of a suspension of microcapsules using a variable length impedance measurement cell

    Directory of Open Access Journals (Sweden)

    Dejan Krizaj

    2012-10-01

    Full Text Available Electrical impedance measurements of the suspensions have to take into account the double layer impedance that is due to a very thin charged layer formed at the electrode-electrolite interface. A dedicated measuring cell that enables variation of the distance between the electrodes was developed for investigation of electrical properties of suspensions using two electrode impedance measurements. By varying the distance between the electrodes it is possible to separate the double layer and the suspension impedance from the measured data. From measured and extracted impedances electrical lumped models have been developed. The error of non inclusion of the double layer impedance has been analyzed. The error depends on the frequency of the measurements as well as on the distance between the electrodes.

  12. The intestinal barrier function and its involvement in digestive disease.

    Science.gov (United States)

    Salvo Romero, Eloísa; Alonso Cotoner, Carmen; Pardo Camacho, Cristina; Casado Bedmar, Maite; Vicario, María

    2015-11-01

    The gastrointestinal mucosal surface is lined with epithelial cells representing an effective barrier made up with intercellular junctions that separate the inner and the outer environments, and block the passage of potentially harmful substances. However, epithelial cells are also responsible for the absorption of nutrients and electrolytes, hence a semipermeable barrier is required that selectively allows a number of substances in while keeping others out. To this end, the intestine developed the "intestinal barrier function", a defensive system involving various elements, both intra- and extracellular, that work in a coordinated way to impede the passage of antigens, toxins, and microbial byproducts, and simultaneously preserves the correct development of the epithelial barrier, the immune system, and the acquisition of tolerance against dietary antigens and the intestinal microbiota. Disturbances in the mechanisms of the barrier function favor the development of exaggerated immune responses; while exact implications remain unknown, changes in intestinal barrier function have been associated with the development of inflammatory conditions in the gastrointestinal tract. This review details de various elements of the intestinal barrier function, and the key molecular and cellular changes described for gastrointestinal diseases associated with dysfunction in this defensive mechanism.

  13. Broadband impedance of the NESTOR storage ring

    International Nuclear Information System (INIS)

    Androsov, V.P.; Gladkikh, P.I.; Gvozd, A.M.; Karnaukhov, I.M.; Telegin, Yu.N.

    2011-01-01

    The contributions from lossy and inductive vacuum chamber components to the broadband impedance of the NESTOR storage ring are obtained by using both low-frequency analytical approaches and computer simulations. As was expected considering the small ring circumference (15.44m), the main contributions both to the longitudinal impedance Z || /n and the loss factor k loss come from the RF-cavity. Cavity impedance was also estimated with CST Microwave Studio (CST Studio Suite TM 2006) by simulating coaxial wire method commonly used for impedance measurements. Both estimates agree well. Finally, we performed the simulations of a number of inductive elements with CST Particle Studio 2010 by using wake field solver. We have also evaluated the bunch length in NESTOR taking the conservative estimate of 3 Ohm for the ring broadband impedance and have found that the bunch length s z = 0.5 cm could be obtained in steady state operation mode for the designed bunch current of 10 mA and RF-voltage of 250 kV.

  14. Elimination of the Respiratory Effect on the Thoracic Impedance Signal with Whole-body Impedance Cardiography

    Czech Academy of Sciences Publication Activity Database

    Jurák, Pavel; Halámek, Josef; Vondra, Vlastimil; Viščor, Ivo; Lipoldová, J.; Plachý, M.

    2010-01-01

    Roč. 37, - (2010), s. 1051-1054 ISSN 0276-6574 R&D Projects: GA AV ČR IAA200650801 Institutional research plan: CEZ:AV0Z20650511 Keywords : respiratory effect * thoracic impedance signal * impedance cardiography Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://cinc.mit.edu/archives/2010/pdf/1051.pdf

  15. Lung Impedance Contributions to the Total Impedance based on a FDM Model and Lead Field Theory.

    Science.gov (United States)

    Patterson, Robert; Yang, Fei

    2005-01-01

    Predicting tissue resistivity is of significance in medical diagnosis due to the fact that disease induces related tissue resistivity change. Studies have shown that the lung and tissues tumors reflect significant impedance change with disease states. It is hypothesized that the impedance measurement with the largest contribution from the organ of interest will result in less error. In this paper, we determined the percentage contribution of the lung impedance to the total impedance for five different external electrode configurations using a high resolution finite difference model (FDM) of the thorax along with lead field theory. The electrode combinations showed a contribution by the lungs of approximately 20% of the total impedance. Many configurations showed contributions of 15%. The results also showed that each lung could be isolated from the opposite lung.

  16. Impedance plethysmographic observations in thoracic outlet syndrome.

    Directory of Open Access Journals (Sweden)

    Nerurkar S

    1990-07-01

    Full Text Available Forty patients with symptoms of neuro-vascular compression in the upper extremities were subjected to impedance plethysmographic study using Parulkar′s method. Two patients recorded decreased blood flow (BFI in supine position and were diagnosed as having partial occlusion at subclavian level. Sixteen of the patients recorded decreased BFI on 90 degrees abduction and hyper-abduction. Twelve of these patients had radiological evidence of anomalous cervicle ribs. In remaining four patients extrinsic impression on the subclavian artery due to fibrous deposits was confirmed by arteriography. Remaining 22 patients recorded normal impedance plethysmograms. Impedance plethysmography thus provided a non-invasive modality for confirmation of vascular compression in thoracic outlet syndrome.

  17. Cascaded impedance networks for NPC inverter

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang

    2010-01-01

    Multilevel inverters are getting more and more attracted because they have better output waveform quality and lower semiconductor voltage stress. The Z-source NPC is a kind of single stage multilevel inverter which has the ability of voltage boost. But the boost capability is relatively low when...... they are subject to the renewable sources. To date, three distinct types of impedance networks can be summarized for implementing a hybrid source impedance network, which can in principle be combined and cascaded before connected to a NPC inverter by proposed two ways. The resulting cascaded impedance network NPC...... would have a higher output voltage gain. It is anticipated that it would help the formed inverters find applications in photovoltaic and other renewable systems, where a high voltage gain is usually requested. Experimental testing has already been conducted and verifies the theory....

  18. Body fat estimation using bioelectrical impedance.

    Science.gov (United States)

    Shaikh, M G; Crabtree, N J; Shaw, N J; Kirk, J M W

    2007-01-01

    Although childhood obesity is a major problem, routine assessment methods do not reflect fat mass. Body mass index, which is most commonly used, gives an indication of weight for height and not a degree of adiposity. Bioelectrical impedance and dual-energy X-ray absorptiometry (DEXA) were used in a group of obese children to assess body fat. Comparison between DEXA and commercial bioelectrical impedance scales in 46 children showed a highly significant correlation (R = 0.944, p bioelectrical impedance was 2.4 kg lower compared to measurement using DEXA. These bioelectrical scales may prove useful in the management of childhood obesity as they are able to provide important clinical information regarding fat mass and adiposity. Copyright 2007 S. Karger AG, Basel.

  19. Determination of corrosion rate by ac impedance

    Energy Technology Data Exchange (ETDEWEB)

    Novitskii, V.S.; Orishchenko, M.Ya.; Kuzub, V.S.

    1988-07-01

    Computerized graphical and chemical analyses were used to study the effect of frequency on corrosion impedance for the systems: Armco iron/H/sub 2/SO/sub 4/ and St3 steel/H/sub 2/SO/sub 4/ with and without the addition of propargyl alcohol inhibitor, St3/NaCl, and St3/circulated water. The Epelboin equation for the effect of frequency on the impedance of anodic iron dissolution in sulfuric acid was confirmed between 10/sup /minus/2/ and 10/sup /minus/3/ Hz. The equation was analyzed theoretically. Corrosion rates found by extrapolating low-frequency conductance to zero frequency, with correction for nonlinearity, agreed with rates obtained gravimetrically with a root-mean-square deviation of no more than 20%. The impedance method was found to be useful for continuously monitoring corrosion rates in industry.

  20. Diagnosis of intestinal and extra intestinal amoebiasis

    International Nuclear Information System (INIS)

    Lopez, Myriam Consuelo; Quiroz, Damian Arnoldo; Pinilla, Analida Elizabeth

    2007-01-01

    The objective is to carry out a review of the national and international literature as of the XXth century in order to update the advances for the diagnosis of complex odd Entamoeba histolytic / Entamoeba dispar and that of intestinal and extra intestinal amoebiasis that may be of use to the scientific community. As well as to unify the diagnostic criteria of this parasitosis known as a public health problem, and as a consequence of that, optimize the quality of population care. Data source: there was a systematic search for the scientific literature Publisher in Spanish and English since 1960 until today, this selection started on the first semester of 2006 until 2007, in the development of the line on intestinal and extra-intestinal amoebiasis of the Medical School of the National University of Colombia. A retrospective search process was carried out, systematically reviewing the most relevant articles as well as the products of this research line. In deciding how to make this article, there was a continuous search in different data bases such as Medline, SciELO and other bases in the library of the National University of Colombia, as well as other classical books related to the subject. For that purpose the terms amoebiasis, odd Entamoeba histolytic, Entamoeba, diagnosis, epidemiology, dysentery, amoebic liver abscess, were used. Studies selection: titles and abstracts were reviewed to select the original publications and the most representative ones related to this article's subject. Data extraction: the articles were classified according to the subject, the chronology and the authors according to the scientific contribution to solve the problem. Synthesis of the data: in the fi rst instance, a chronological critical analysis was carried out to order and synthesize the progress made in the diagnosis until confirmation of the experts' agreements in the field of amoebiasis was obtained throughout the world. Conclusion: this article summarizes what has taken place

  1. Magneto-mechanical impedance of metallic structures.

    Science.gov (United States)

    Zagrai, Andrei N

    2009-01-01

    Impedance measurements with a magneto-elastic active sensor are explored for inferring the magneto-mechanical impedance (MMI) of a metallic structure. It is shown that the MMI contains electrical response of the sensor and both electrical and mechanical structural responses. An analytical model is suggested that accounts for electrical characteristics of the sensor, sensor/structure electromagnetic interaction, and multimodal structural dynamic behavior. The model is validated with a set of MMI experiments demonstrating feasibility of deducing structural natural frequencies and structural vibration modes.

  2. Study of Body Composition by Impedance Analysis

    Science.gov (United States)

    González-Solís, J. L.; Vargas-Luna, M.; Sosa-Aquino, M.; Bernal-Alvarado, J.; Gutiérrez-Juárez, G.; Huerta-Franco, R.; Sanchis-Sabater, A.

    2002-08-01

    This work presents a set of impedance measurements and preliminary results on the analysis of body composition using impedance spectroscopy. This study is made using a pork meat sample and spectra from fat and flesh region were independently obtained using the same electrodes array. From these measurements, and theoretical considerations, it is possible to explain the behavior of the composite sample flesh-fat-flesh and, fitting the electrical parameters of the model, it shows the plausibility of a physical and quantitative application to human corporal composition.

  3. Pumping slots: Coupling impedance calculations and estimates

    International Nuclear Information System (INIS)

    Kurennoy, S.

    1993-08-01

    Coupling impedances of small pumping holes in vacuum-chamber walls have been calculated at low frequencies, i.e., for wavelengths large compared to a typical hole size, in terms of electric and magnetic polarizabilities of the hole. The polarizabilities can be found by solving and electro- or magnetostatic problem and are known analytically for the case of the elliptic shape of the hole in a thin wall. The present paper studies the case of pumping slots. Using results of numerical calculations and analytical approximations of polarizabilities, we give formulae for practically important estimates of slot contribution to low-frequency coupling impedances

  4. Quadratic Boost A-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Chub, Andrii

    2016-01-01

    A novel quadratic boost A-source impedance network is proposed to realize converters that demand very high voltage gain. To satisfy the requirement, the network uses an autotransformer where the obtained gain is quadratically dependent on the duty ratio and is unmatched by any existing impedance...... source networks and normal dc-dc converters with coupled magnetics at the same duty ratio and turns ratio. The term “Quadratic Boost A-Source” indicates its quadratic varying gain in the operating principle of the converter. The proposed converter draws a continuous current from the source and suits...

  5. Estimating the short-circuit impedance

    DEFF Research Database (Denmark)

    Nielsen, Arne Hejde; Pedersen, Knud Ole Helgesen; Poulsen, Niels Kjølstad

    1997-01-01

    and current are derived each period, and the short-circuit impedance is estimated from variations in these components created by load changes in the grid. Due to the noisy and dynamic grid with high harmonic distortion it is necessary to threat the calculated values statistical. This is done recursively...... through a RLS-algorithm. The algorithms have been tested and implemented on a PC at a 132 kV substation supplying a rolling mill. Knowing the short-circuit impedance gives the rolling mill an opportunity to adjust the arc furnace operation to keep flicker below a certain level. Therefore, the PC performs...

  6. Electrochemical Impedance Spectroscopy Of Metal Alloys

    Science.gov (United States)

    Macdowell, L. G.; Calle, L. M.

    1993-01-01

    Report describes use of electrochemical impedance spectroscopy (EIS) to investigate resistances of 19 alloys to corrosion under conditions similar to those of corrosive, chloride-laden seaside environment of Space Transportation System launch site. Alloys investigated: Hastelloy C-4, C-22, C-276, and B-2; Inconel(R) 600, 625, and 825; Inco(R) G-3; Monel 400; Zirconium 702; Stainless Steel 304L, 304LN, 316L, 317L, and 904L; 20Cb-3; 7Mo+N; ES2205; and Ferralium 255. Results suggest electrochemical impedance spectroscopy used to predict corrosion performances of metal alloys.

  7. Intestinal anisakidosis (anisakiosis).

    Science.gov (United States)

    Takei, Hidehiro; Powell, Suzanne Z

    2007-10-01

    A case of intestinal anisakidosis in a 42-year-old man in Japan is presented. His chief complaint was an acute onset of severe abdominal pain. Approximately 12 hours before the onset of this symptom, he had eaten sliced raw mackerel ("sashimi"). Upper endoscopy was unremarkable. At exploratory laparotomy, an edematous, diffusely thickened segment of jejunum was observed, which was resected. The postoperative course was uneventful. The segment of small intestine showed a granular indurated area on the mucosal surface, and microscopically, a helminthic larva penetrating the intestinal wall, which was surrounded by a cuff of numerous neutrophils and eosinophils, as well as diffuse acute serositis. A cross section of the larva revealed the internal structures, pathognomonic of Anisakis simplex. Although anisakidosis is rare in the United States, with the increasing popularity of Japanese cuisine, the incidence is expected to increase, and pathologists should be familiar with this disease.

  8. Intestinal failure: a review

    Science.gov (United States)

    Allan, Philip; Lal, Simon

    2018-01-01

    Intestinal failure (IF) is the inability of the gut to absorb necessary water, macronutrients (carbohydrate, protein, and fat), micronutrients, and electrolytes sufficient to sustain life and requiring intravenous supplementation or replacement. Acute IF (types 1 and 2) is the initial phase of the illness and may last for weeks to a few months, and chronic IF (type 3) from months to years. The challenge of caring for patients with IF is not merely the management of the underlying condition leading to IF or the correct provision of appropriate nutrition or both but also the prevention of complications, whether thromboembolic phenomenon (for example, venous occlusion), central venous catheter-related bloodstream infection, IF-associated liver disease, or metabolic bone disease. This review looks at recent questions regarding chronic IF (type 3), its diagnosis and management, the role of the multidisciplinary team, and novel therapies, including hormonal treatment for short bowel syndrome but also surgical options for intestinal lengthening and intestinal transplant. PMID:29399329

  9. Small intestine diverticuli

    International Nuclear Information System (INIS)

    Pomakov, P.; Risov, A.

    1991-01-01

    The routine method of contrast matter passage applied to 850 patients with different gastrointestinal diseases proved inefficient to detect any small-intestinal diverticuli. The following modiffications of the method have been tested in order to improve the diagnostic possibilities of the X-ray: study at short intervals, assisted passage, enteroclysm, pharmacodynamic impact, retrograde filling of the ileum by irrigoscopy. Twelve diverticuli of the small-intestinal loops were identified: 5 Meckel's diverticuli, 2 solitary of which one of the therminal ileum, 2 double diverticuli and 1 multiple diverticulosis of the jejunum. The results show that the short interval X-ray examination of the small intestines is the method of choice for identifying local changes in them. The solitary diverticuli are not casuistic scarcity, its occurrence is about 0.5% at purposeful X-ray investigation. The assisted passage method is proposed as a method of choice for detection of the Meckel's diverticulum. 5 figs., 3 tabs. 18 refs

  10. Chronic intestinal pseudoobstruction syndrome

    International Nuclear Information System (INIS)

    Yeon, Kyung Mo; Seo, Jeong Kee; Lee, Yong Seok

    1992-01-01

    Chronic intestinal pseudoobstruction syndrome is a rare clinical condition in which impaired intestinal peristalsis causes recurrent symptoms of bowel obstruction in the absence of a mechanical occlusion. This syndrome may involve variable segments of small or large bowel, and may be associated with urinary bladder retention. This study included 6 children(3 boys and 3 girls) of chronic intestinal obstruction. Four were symptomatic at birth and two were of the ages of one month and one year. All had abdominal distension and deflection difficulty. Five had urinary bladder distension. Despite parenteral nutrition and surgical intervention(ileostomy or colostomy), bowel obstruction persisted and four patients expired from sepses within one year. All had gaseous distension of small and large bowel on abdominal films. In small bowel series, consistent findings were variable degree of dilatation, decreased peristalsis(prolonged transit time) and microcolon or microrectum. This disease entity must be differentiated from congenital megacolon, ileal atresia and megacystis syndrome

  11. Small Intestinal Infections.

    Science.gov (United States)

    Munot, Khushboo; Kotler, Donald P

    2016-06-01

    Small intestinal infections are extremely common worldwide. They may be bacterial, viral, or parasitic in etiology. Most are foodborne or waterborne, with specific etiologies differing by region and with diverse pathophysiologies. Very young, very old, and immune-deficient individuals are the most vulnerable to morbidity or mortality from small intestinal infections. There have been significant advances in diagnostic sophistication with the development and early application of molecular diagnostic assays, though these tests have not become mainstream. The lack of rapid diagnoses combined with the self-limited nature of small intestinal infections has hampered the development of specific and effective treatments other than oral rehydration. Antibiotics are not indicated in the absence of an etiologic diagnosis, and not at all in the case of some infections.

  12. The intestinal calcistat

    Directory of Open Access Journals (Sweden)

    M K Garg

    2013-01-01

    Full Text Available The main physiological function of vitamin D is maintenance of calcium homeostasis by its effect on calcium absorption, and bone health in association with parathyroid gland. Vitamin D deficiency (VDD is defined as serum 25-hydroxy vitamin D (25OHD levels <20 ng/ml. Do all subjects with VDD have clinical disease according to this definition? We hypothesize that there exist an intestinal calcistat, which controls the calcium absorption independent of PTH levels. It consists of calcium sensing receptor (CaSR on intestinal brush border, which senses calcium in intestinal cells and vitamin D system in intestinal cells. CaSR dampens the generation of active vitamin D metabolite in intestinal cells and decrease active transcellular calcium transport. It also facilitates passive paracellular diffusion of calcium in intestine. This local adaptation adjusts the fractional calcium absorption according the body requirement. Failure of local adaptation due to decreased calcium intake, decreased supply of 25OHD, mutation in CaSR or vitamin D system decreases systemic calcium levels and systemic adaptations comes into the play. Systemic adaptations consist of rise in PTH and increase in active vitamin D metabolites. These adaptations lead to bone resorption and maintenance of calcium homeostasis. Not all subjects with varying levels of VDD manifest with secondary hyperparathyroidism and decreased in bone mineral density. We suggest that rise in PTH is first indicator of VDD along with decrease in BMD depending on duration of VDD. Hence, subjects with any degree of VDD with normal PTH and BMD should not be labeled as vitamin D deficient. These subjects can be called subclinical VDD, and further studies are required to assess beneficial effect of vitamin D supplementation in this subset of population.

  13. Intestinal microbiota and ulcerative colitis.

    Science.gov (United States)

    Ohkusa, Toshifumi; Koido, Shigeo

    2015-11-01

    There is a close relationship between the human host and the intestinal microbiota, which is an assortment of microorganisms, protecting the intestine against colonization by exogenous pathogens. Moreover, the intestinal microbiota play a critical role in providing nutrition and the modulation of host immune homeostasis. Recent reports indicate that some strains of intestinal bacteria are responsible for intestinal ulceration and chronic inflammation in inflammatory bowel diseases (IBD) such as ulcerative colitis (UC) and Crohn's disease (CD). Understanding the interaction of the intestinal microbiota with pathogens and the human host might provide new strategies treating patients with IBD. This review focuses on the important role that the intestinal microbiota plays in maintaining innate immunity in the pathogenesis and etiology of UC and discusses new antibiotic therapies targeting the intestinal microbiota. Copyright © 2015 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  14. Small intestine aspirate and culture

    Science.gov (United States)

    ... ency/article/003731.htm Small intestine aspirate and culture To use the sharing features on this page, please enable JavaScript. Small intestine aspirate and culture is a lab test to check for infection ...

  15. Impedance spectroscopy of changes in skin-electrode impedance induced by motion.

    Science.gov (United States)

    Cömert, Alper; Hyttinen, Jari

    2014-11-18

    The motion artifact is an ever-present challenge in the mobile monitoring of surface potentials. Skin-electrode impedance is investigated as an input parameter to detect the motion artifact and to reduce it using various methods. However, the impact of the used impedance measurement frequency on the relationship between measured impedance and the motion artifact and the relationship between the impedance and the motion is not well understood. In this paper, for the first time, we present the simultaneous measurement of impedance at 8 current frequencies during the application of controlled motion to the electrode at monitored electrode mounting force. Three interwoven frequency groupings are used to obtain a spectrum of 24 frequencies between 25 Hz and 1 MHz for ten volunteers. Consequently, the surface potential and one channel of ECG are measured from the electrode subject to controlled motion. The signals are then analyzed in time and frequency domain. The results show that the different frequencies of impedance measurements do not reflect the motion in the same manner. The best correlation between impedance and the applied motion was seen at impedance current frequencies above 17 kHz. For resistance this relationship existed for frequencies above 11 kHz, Reactance did not show good time domain correlation, but had good frequency domain correlation at frequencies higher than 42 kHz. Overall, we found that the impedance signal correlated well with the applied motion; however impedance had lower correlation to actual motion artifact signal. Based on our results, we can conclude that the current frequency used for the impedance measurement has a great effect on the relationship of the measurement to the applied motion and its relationship with the resulting motion artifact. Therefore, when flat textile contact biopotential electrodes are used, frequencies higher than 17 kHz are best suited for impedance measurements intended for the estimation of electrode

  16. Introduction to impedance for short relativistic bunches

    International Nuclear Information System (INIS)

    Morton, P.L.

    1993-02-01

    The purpose of this paper is to introduce the concept of impedance to calculate the wake field forces left behind by a short bunch which travels at relativistic speed through a structure with discontinuities. We will try to be as intuitive as possible and leave the more rigorous derivations to the second paper on this subject by J. Wang

  17. Battery impedance spectroscopy using bidirectional grid connected ...

    Indian Academy of Sciences (India)

    Shimul Kumar Dam

    Impedance spectroscopy; grid connection; battery converter; state of charge; health monitoring. 1. Introduction. Batteries play an important role as energy storage devices for renewable energy sources, electric vehicle and many other applications. A battery bank is interfaced to load through a power converter, which controls ...

  18. Microwave transmission-line impedance data

    CERN Document Server

    Gunston, M A R

    1996-01-01

    A compendium of data for computing the characteristic impedance of transmission lines based on physical dimensions. Covers both conventional structures and unusual geometries, including coaxial, eccentric and elliptic coaxial, twin-wire, wire-above-ground, microstrip and derivatives, stripline, slabline and trough line. Also details numerous configurations of coupled lines.

  19. Magnetotelluric impedance tensor analysis for identification of ...

    Indian Academy of Sciences (India)

    G Pavan Kumar

    2017-07-18

    Jul 18, 2017 ... Magnetotelluric impedance tensor analysis for identification of transverse tectonic feature in the Wagad uplift, Kachchh, northwest India. G Pavan Kumar*, Virender Kumar, Mehul Nagar, Dilip Singh,. E Mahendar, Pruthul Patel and P Mahesh. Institute of Seismological Research (ISR), Raisan, Gandhinagar ...

  20. Impedances in lossy elliptical vacuum chambers

    International Nuclear Information System (INIS)

    Piwinski, A.

    1994-04-01

    The wake fields of a bunched beam caused by the resistivity of the chamber walls are investigated for a vacuum chamber with elliptical cross section. The longitudinal and transverse impedances are calculated for arbitrary energies and for an arbitrary position of the beam in the chamber. (orig.)

  1. Variable impedance control for aerial interaction

    NARCIS (Netherlands)

    Mersha, A.Y.; Stramigioli, Stefano; Carloni, Raffaella

    This paper presents a versatile control architecture for aerial robots in interactive tasks. The control architecture is characterized by its unique capability of varying the apparent impedance of the controlled aerial robot as well as the interaction force, when in contact. This work finds its way

  2. High temperature impedance spectroscopy of barium stannate ...

    Indian Academy of Sciences (India)

    temperature solid-state reac- tion technique. X-ray diffraction analysis indicated the formation of a single-phase cubic structure with lattice parameter: a = (4·1158 ± 0·0003) .... the equation for the impedance of this circuit. Z = Z − jZ = (. 1/Rg + jωCg. )−1.

  3. Explicit Expressions of Impedances and Wake Functions

    Energy Technology Data Exchange (ETDEWEB)

    Ng, K.Y.; /Fermilab; Bane, K,; /SLAC

    2012-06-11

    Sections 3.2.4 and 3.2.5 of the Handbook of Accelerator Physics and Engineering on Landau damping are combined and updated. The new addition includes impedances and wakes for multi-layer beam pipe, optical model, diffraction model, and cross-sectional transition.

  4. High temperature impedance spectroscopy of barium stannate ...

    Indian Academy of Sciences (India)

    High temperature impedance spectroscopy of barium stannate, BaSnO3. SHAIL UPADHYAY. Department of Physics, Institute of Technology, Banaras Hindu University, Varanasi 221 005, India. MS received 29 May 2012; revised 14 July 2012. Abstract. Polycrystalline powder of BaSnO3 was prepared at 1300 ◦C using a ...

  5. Impedance-matched drilling telemetry system

    Science.gov (United States)

    Normann, Randy A [Edgewood, NM; Mansure, Arthur J [Albuquerque, NM

    2008-04-22

    A downhole telemetry system that uses inductance or capacitance as a mode through which signal is communicated across joints between assembled lengths of pipe wherein efficiency of signal propagation through a drill string, for example, over multiple successive pipe segments is enhanced through matching impedances associated with the various telemetry system components.

  6. Electrical impedance spectroscopy measurements to estimate the ...

    Indian Academy of Sciences (India)

    Administrator

    emission measurements during the uniaxial compression tests on Misis fault breccia and showed that certain ... If a variable a.c. voltage is applied to a material, the ratio of voltage to current is known as the impedance. ... mechanical performance of engines, corrosion and so on. Although this technique is a highly popular ...

  7. Determination of Transmission Line Impedance Matching Parameters

    African Journals Online (AJOL)

    The analysis of measured and computed matching parameters show that the values obtained are within the acceptable standard threshold values of Voltage Standing Wave Ratio ≤1.50 and Return loss ≥ +14dB used by telecommunication transmission designers worldwide. Keywords: Impedance matching, voltage ...

  8. Generalized impedances and wakes in asymmetric structures

    International Nuclear Information System (INIS)

    Heifets, S.; Wagner, A.; Zotter, B.

    1998-01-01

    In rotationally structures, the dominant m = 0 longitudinal impedance does not depend on the offsets of either the leading or the trailing particles, while the dominant m = 1 transverse impedance is proportional to the offset of the leading particles, while it is still independent of the offsets of the trailing ones. This behavior is no longer true in rotationally non-symmetric structures, where in general all impedances depend on the offsets of both the leading and the trailing particles. The same behavior is shown by wake functions and wake potentials. The concept of generalized impedances or generalized wake functions must be used to calculate the effect of leading particles on trailing ones with different offsets, each described by two transverse coordinates. This dependence of wake potentials on four additional parameters (two for each offset) would make their use very cumbersome. Fortunately, it was found that the transverse wake potentials can be separated into superpositions of dipolar components, which are proportional to the offset of the leading bunch, and quadrupolar components, which are proportional to the offset of the trailing particles. Higher multipole components are much smaller, and can be neglected for most structures without rotational symmetry. In this report, the authors derive analytical expressions for these multipolar components, which permits estimates of the size of the neglected terms. In particular, when structures have one or two transverse symmetry planes, the expressions simplify and explain the behavior of wake potentials which had been computed for rotationally non-symmetric structures

  9. Impedance and collective effects in the KEKB

    Energy Technology Data Exchange (ETDEWEB)

    Chin, Yongho [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan); Oide, Katsunobu

    1996-08-01

    This paper focuses on beam instabilities due to single-beam collective effects, impedances from various beamline elements, ion trapping, photo-electrons, and other issues in the KEKB. We will also discuss the power deposition generated by a beam in the form of the Higher-Order-Mode (HOM) losses by interacting with its surroundings. (author)

  10. Impedance Control of a Redundant Parallel Manipulator

    DEFF Research Database (Denmark)

    Méndez, Juan de Dios Flores; Schiøler, Henrik; Madsen, Ole

    2017-01-01

    This paper presents the design of Impedance Control to a redundantly actuated Parallel Kinematic Manipulator. The proposed control is based on treating each limb as a single system and their connection through the internal interaction forces. The controller introduces a stiffness and damping...

  11. Bioelectrical Impedance and Body Composition Assessment

    Science.gov (United States)

    Martino, Mike

    2006-01-01

    This article discusses field tests that can be used in physical education programs. The most common field tests are anthropometric measurements, which include body mass index (BMI), girth measurements, and skinfold testing. Another field test that is gaining popularity is bioelectrical impedance analysis (BIA). Each method has particular strengths…

  12. Magnetotelluric impedance tensor analysis for identification of ...

    Indian Academy of Sciences (India)

    We present the results of magnetotelluric (MT) impedance tensors analyses of 18 sites located along a profile cutting various faults in the uplifted Wagad block of the Kachchh basin. The MT time series of 4–5 days recording duration have been processed and the earth response functions are estimated in broad frequency ...

  13. impedance calculations of induction machine rotor conductors.

    African Journals Online (AJOL)

    Dr Obe

    This paper describes a method of' calculating the impedance of Rectangular and Trapezoidal rotor bars. An R-L parallel network is used to model each of the Rotor bars. A computer optimisation Algorithm is developed and from which the Rotor circuit parameters at several frequencies are estimated. The model solutions ...

  14. Measuring mechanical impedance in clayey gravelly soils

    Directory of Open Access Journals (Sweden)

    R. Stolf

    1998-06-01

    Full Text Available Mechanical impedance of clayey and gravelly soils is often needed to interpret experimental results from tillage and other field experiments. Its measurement is difficult with manual and hydraulic penetrometers, which often bend or break in such soils. The purpose of this study was to evaluate the feasibility of a hand-operated "Stolf" impact penetrometer to measure mechanical impedance (soil resistance. The research was conducted in Raleigh, North Carolina, USA (35º 45'N, 78º 42'W, elevation 75 m. Corn was planted on April 19, 1991. Penetrometer measurements were taken on May 10, 1991, in 5 cm intervals to 60 cm at 33 locations on a transect perpendicular to the corn rows in each of four tillage treatments. The data permitted three-dimensional displays showing how mechanical impedance changed with depth and distance along the transect. The impact penetrometer proved to be a useful tool to collect quantitative mechanical impedance data on "hard" clayey and/or gravelly soils which previously were difficult to reliably quantify.

  15. Loudspeaker impedance emulator for multi resonant systems

    DEFF Research Database (Denmark)

    Iversen, Niels Elkjær; Knott, Arnold

    2015-01-01

    Specifying the performance of audio amplifiers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterised by its electrical, mechanical and acoustical properties. Therefore a loudspeaker emulator capable of adjusting...

  16. Ambulatory monitoring of the impedance cardiogram

    NARCIS (Netherlands)

    Willemsen, G.; de Geus, E.J.C.; klaver, C.H.A.M.; van Doornen, L.J.P.; Carroll, D.

    1996-01-01

    The growing need for more advanced ambulatory monitoring has led to the development of an ambulatory monitor for impedance cardiography (VU-AMD). This paper presents two studies addressing the validity of the VU-AMD. In the first study, the cardiovascular responses of 25 subjects during various

  17. Development of highly selective electrochemical impedance sensor ...

    Indian Academy of Sciences (India)

    with MIP were employed as a sensor for 5CDNT by applying electrochemical impedance spectroscopy (EIS) as transduction principle. The charge transfer resistance obtained by impedimetric analysis is proportional to the concentration of 5CDNT over a wide concentration range: 10 nM to 100 μM. A linear determination ...

  18. Battery impedance spectroscopy using bidirectional grid connected ...

    Indian Academy of Sciences (India)

    Shimul Kumar Dam

    battery management system one needs to track two vari- ables—state of ... demand is high, thus improving the power quality. The .... the aging effect. To find out usefulness of measurements at different frequencies, the impedance of a 12 V, 9 Ah VRLA battery is measured by a standard commercial equipment. Solartron ...

  19. impedance calculations of induction machine rotor conductors.

    African Journals Online (AJOL)

    Dr Obe

    ABSTRACT. The exact calculation of the impedance of induction machine rotor conductors at several operating frequencies are necessary if the dynamic behaviour of the machine is to give a good correlation between the simulated starting torque and current and the experimental results. This paper describes a method of'.

  20. A rigorous uniform diffraction analysis of the electromagnetic scattering from impedance edges and junctions

    Science.gov (United States)

    Fortney, Joseph C.

    1991-12-01

    This paper investigates the scattering from impedance strips and impedance-loaded conducting strips. The impedance strips are analyzed using Senior's impedance half plane formulation. Once the primary diffraction from the impedance half plane is presented, it is used to develop multiple diffraction mechanisms on an impedance strip. The scattering from impedance-loaded strips are analyzed using Maliuzhinets' impedance wedge formulation. The primary diffraction mechanism from an impedance wedge is used to develop the multiple diffractions on an impedance double wedge. The multiple diffractions on both types of strips are developed using the Extended Spectral Ray Method. Sample calculations are made for impedance strips and impedance-loaded strips for a large purely capacitive impedance, a large purely inductive impedance, a large real impedance, and a small real impedance. Measurements are made for impedance strips and impedance loaded strips and are used to compare against predictions. The impedance materials used are two magnetic radar absorbing materials and two resistive materials.

  1. Stages of Small Intestine Cancer

    Science.gov (United States)

    ... all of an organ that contains cancer. The resection may include the small intestine and nearby organs (if the cancer has spread). The doctor may remove the section of the small intestine that contains cancer and perform an anastomosis (joining the cut ends of the intestine together). ...

  2. Intestinal inflammatory myofibroblastic tumour

    African Journals Online (AJOL)

    abdominal X-ray of patients 1, 3 and 4 demonstrated dilated small bowel loops with fluid levels in keeping with intestinal ... myxoid/vascular pattern characterised by a variable admixture of capillary-calibre blood vessels, .... in the present study had a past history of abdominal trauma or surgery. Ancillary histopathological ...

  3. Small intestine and microbiota.

    Science.gov (United States)

    Cotter, Paul D

    2011-03-01

    To highlight the recent studies which have enhanced our appreciation of the composition of the microbiota in the human small intestine and its relevance to the health of the host. In the past number of years, the composition of the microorganisms present in our small intestines has been the subject of greater scrutiny than ever before. These investigations have been possible as a consequence of the development and utilization of new molecular tools which have revolutionized the field of microbial ecology and have focused predominantly on the small intestinal microbiota associated with pediatric celiac disease, inflammatory bowel disease, irritable bowel syndrome and pouchitis. The impact of invasive procedures, such as small bowel transplant, ileostomy and ileal pouch anal anastomosis, on the ileal microbiota has also been investigated. The ever greater appreciation of the link between the small intestinal microbiota and the health status of the host has the potential to lead to the development of new strategies to alter this microbiota in a targeted way to prevent or treat specific disorders.

  4. Intestinal obstruction repair

    Science.gov (United States)

    ... Ileostomy and your diet Ileostomy - caring for your stoma Ileostomy - changing your pouch Ileostomy - discharge Ileostomy - what to ask your doctor Intestinal or bowel obstruction - discharge Low-fiber diet Surgical wound care - open Types of ileostomy When you have nausea ...

  5. adhesive intestinal obstruction

    African Journals Online (AJOL)

    2006-06-01

    Jun 1, 2006 ... obstruction. Brit. I. Surg. 1998; 85: 1071-1074. The acute abdomen: Intestinal obstruction. In: Primary surgery, Vol. 1. Edited by Maurice King et al. Oxford. Med. PubL, Oxford. 1990; 142-169. Fluids and electrolyte management. In: Essentials of pediatric surgery. Edited by Marc Rowe et al. Mosby,. St. Louis ...

  6. Intestinal Complications of IBD

    Science.gov (United States)

    ... localized pocket of pus caused by infection from bacteria. More common in Crohn’s than in colitis, an abscess may form in the intestinal wall—sometimes causing it to bulge out. Visible abscesses, such as those around the anus, look like boils and treatment often involves lancing. Symptoms of ...

  7. Intestinal failure in childhood

    African Journals Online (AJOL)

    Short bowel syndrome (SBS) was one of the first recognised conditions of protracted IF. With the increasing and successful use of long-term PN during the last three decades, several other causes of IF have emerged. Long-term PN and home-PN are the mainstay of therapy, independent of the nature of “Intestinal failure” ...

  8. AC impedance technique in PEM fuel cell diagnosis - A review

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Xiaozi; Wang, Haijiang; Colin Sun, Jian; Zhang, Jiujun [Institute for Fuel Cell Innovation, National Research Council (Canada)

    2007-12-15

    Because the AC impedance technique, also known as electrochemical impedance spectroscopy (EIS), is being utilized by more and more researchers in proton exchange membrane (PEM) fuel cell studies, the technique has developed into a primary tool in such research. In this paper the recent work on PEM fuel cells using the AC impedance technique is reviewed. Both in situ and ex situ impedance measurements are discussed, with primary focus on the in situ measurements. Within the domain of in situ studies, various methods for measuring the impedance of a PEM fuel cell are examined, and typical impedance spectra in several common scenarios are presented. Representative applications of the AC impedance technique in PEM fuel cell research are also discussed. Finally, the necessity of a time domain rapid AC impedance technique is briefly discussed. (author)

  9. Iterative Reconstruction Methods for Hybrid Inverse Problems in Impedance Tomography

    DEFF Research Database (Denmark)

    Hoffmann, Kristoffer; Knudsen, Kim

    2014-01-01

    For a general formulation of hybrid inverse problems in impedance tomography the Picard and Newton iterative schemes are adapted and four iterative reconstruction algorithms are developed. The general problem formulation includes several existing hybrid imaging modalities such as current density...... impedance imaging, magnetic resonance electrical impedance tomography, and ultrasound modulated electrical impedance tomography, and the unified approach to the reconstruction problem encompasses several algorithms suggested in the literature. The four proposed algorithms are implemented numerically in two...

  10. Enhanced Method for Cavity Impedance Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Frank Marhauser, Robert Rimmer, Kai Tian, Haipeng Wang

    2009-05-01

    With the proposal of medium to high average current accelerator facilities the demand for cavities with extremely low Higher Order Mode (HOM) impedances is increasing. Modern numerical tools are still under development to more thoroughly predict impedances that need to take into account complex absorbing boundaries and lossy materials. With the usually large problem size it is preferable to utilize massive parallel computing when applicable and available. Apart from such computational issues, we have developed methods using available computer resources to enhance the information that can be extracted from a cavities? wakefield computed in time domain. In particular this is helpful for a careful assessment of the extracted RF power and the mitigation of potential beam break-up or emittance diluting effects, a figure of merit for the cavity performance. The method is described as well as an example of its implementation.

  11. Multifrequency electrical impedance tomography using spectral constraints.

    Science.gov (United States)

    Malone, Emma; Sato Dos Santos, Gustavo; Holder, David; Arridge, Simon

    2014-02-01

    Multifrequency electrical impedance tomography (MFEIT) exploits the dependence of tissue impedance on frequency to recover an image of conductivity. MFEIT could provide emergency diagnosis of pathologies such as acute stroke, brain injury and breast cancer. We present a method for performing MFEIT using spectral constraints. Boundary voltage data is employed directly to reconstruct the volume fraction distribution of component tissues using a nonlinear method. Given that the reconstructed parameter is frequency independent, this approach allows for the simultaneous use of all multifrequency data, thus reducing the degrees of freedom of the reconstruction problem. Furthermore, this method allows for the use of frequency difference data in a nonlinear reconstruction algorithm. Results from empirical phantom measurements suggest that our fraction reconstruction method points to a new direction for the development of multifrequency EIT algorithms in the case that the spectral constraints are known, and may provide a unifying framework for static EIT imaging.

  12. Impedance Issues in the CERN SPS

    CERN Document Server

    Linnecar, Trevor Paul R

    1999-01-01

    The future use of the CERN SPS accelerator as injector for the Large Hadron Collider, LHC, and the possible use of the SPS as a neutrino source for the Gran Sasso experiment are pushing the maximum intensity requirements of the accelerator much higher than achieved up to now. At the same time the requirements on beam quality are becoming far more stringent. The SPS machine, built in the 70's, is not a ``smooth" machine. It contains many discontinuities in vacuum chamber cross-section and many cavity-like objects, as well as the 5 separate RF systems at present installed. All these lead to a high impedance, seen by the beam, spread over a wide frequency range. As a result there is a constant fight against instabilities, both single and multi bunch, as the intensity increases. A programme of studies is under way in the SPS to identify, reduce, and remove where possible the sources of these impedances.

  13. Impedance of a beam tube with antechamber

    Energy Technology Data Exchange (ETDEWEB)

    Barry, W.; Lambertson, G.R.; Voelker, F.

    1986-08-01

    A beam vacuum chamber was proposed to allow synchrotron light to radiate from a circulating electron beam into an antechamber containing photon targets, pumps, etc. To determine the impedance such a geometry would present to the beam, electromagnetic measurements were carried out on a section of chamber using for low frequencies a current-carrying wire and for up to 16 GHz, a resonance perturbation method. Because the response of such a chamber would depend on upstream and downstream restrictions of aperture yet to be determined, the resonance studies were analyzed in some generality. The favorable conclusion of these studies is that the antechamber makes practically no contribution to either the longitudinal or the transverse impedances.

  14. Beam measurements of the SPS longitudinal impedance

    CERN Document Server

    Lasheen, A

    2017-01-01

    Longitudinal instabilities are one of the main limitationsin the CERN SPS to reach the beam parameters requiredfor the High Luminosity LHC project. In preparation tothe SPS upgrade, possible remedies are studied by perform-ing macroparticle simulations using the machine impedancemodel obtained from electromagnetic simulations and mea-surements. To benchmark the impedance model, the resultsof simulations are compared with various beam measure-ments. In this study, the reactive part of the impedance wasprobed by measuring the quadrupole frequency shift withintensity, obtained from bunch length oscillations at mis-matched injection into the SPS. This method was appliedover many last years to follow up the evolution of the SPSimpedance, injecting bunches with the same bunch length.A novel approach, giving significantly more information,consists in varying the injected bunch length. The compari-son of these measurements with macroparticle simulationsallowed to test the existing model and identify some missingSPS i...

  15. Microwave impedance imaging on semiconductor memory devices

    Science.gov (United States)

    Kundhikanjana, Worasom; Lai, Keji; Yang, Yongliang; Kelly, Michael; Shen, Zhi-Xun

    2011-03-01

    Microwave impedance microscopy (MIM) maps out the real and imaginary components of the tip-sample impedance, from which the local conductivity and dielectric constant distribution can be derived. The stray field contribution is minimized in our shielded cantilever design, enabling quantitative analysis of nano-materials and device structures. We demonstrate here that the MIM can spatially resolve the conductivity variation in a dynamic random access memory (DRAM) sample. With DC or low-frequency AC bias applied to the tip, contrast between n-doped and p-doped regions in the dC/dV images is observed, and p-n junctions are highlighted in the dR/dV images. The results can be directly compared with data taken by scanning capacitance microscope (SCM), which uses unshielded cantilevers and resonant electronics, and the MIM reveals more information of the local dopant concentration than SCM.

  16. Detecting stochastic inclusions in electrical impedance tomography

    Science.gov (United States)

    Barth, Andrea; Harrach, Bastian; Hyvönen, Nuutti; Mustonen, Lauri

    2017-11-01

    This work considers the inclusion detection problem of electrical impedance tomography with stochastic conductivities. It is shown that a conductivity anomaly with a random conductivity can be identified by applying the factorization method or the monotonicity method to the mean value of the corresponding Neumann-to-Dirichlet map provided that the anomaly has high enough contrast in the sense of expectation. The theoretical results are complemented by numerical examples in two spatial dimensions.

  17. Applications of Nonlinear Electrochemical Impedance Spectroscopy (NLEIS)

    KAUST Repository

    Adler, S. B.

    2013-08-31

    This paper reviews the use of nonlinear electrochemical impedance spectroscopy (NLEIS) in the analysis of SOFC electrode reactions. By combining EIS and NLEIS, as well as other independent information about an electrode material, it becomes possible to establish quantitative links between electrochemical kinetics and materials properties, even when systems are unstable with time. After a brief review of the method, this paper summarizes recent results analyzing the effects of Sr segregation in thin-film LSC electrodes. © The Electrochemical Society.

  18. IMPEDANCE SPECTROSCOPY OF POLYCRYSTALLINE TIN DIOXIDE FILMS

    Directory of Open Access Journals (Sweden)

    D. V. Adamchuck

    2016-01-01

    Full Text Available The aim of this work is the analysis of the influence of annealing in an inert atmosphere on the electrical properties and structure of non-stoichiometric tin dioxide films by means of impedance spectroscopy method. Non-stoichiometric tin dioxide films were fabricated by two-step oxidation of metallic tin deposited on the polycrystalline Al2O3 substrates by DC magnetron sputtering. In order to modify the structure and stoichiometric composition, the films were subjected to the high temperature annealing in argon atmosphere in temperature range 300–800 °С. AC-conductivity measurements of the films in the frequency range 20 Hz – 2 MHz were carried out. Variation in the frequency dependencies of the real and imaginary parts of the impedance of tin dioxide films was found to occur as a result of high-temperature annealing. Equivalent circuits for describing the properties of films with various structure and stoichiometric composition were proposed. Possibility of conductivity variation of the polycrystalline tin dioxide films as a result of аnnealing in an inert atmosphere was demonstrated by utilizing impedance spectroscopy. Annealing induces the recrystallization of the films, changing in their stoichiometry as well as increase of the sizes of SnO2 crystallites. Variation of electrical conductivity and structure of tin dioxide films as a result of annealing in inert atmosphere was confirmed by X-ray diffraction analysis. Analysis of the impedance diagrams of tin dioxide films was found to be a powerful tool to study their electrical properties. 

  19. PHEMT Distributed Power Amplifier Adopting Broadband Impedance Transformer

    DEFF Research Database (Denmark)

    Narendra, K.; Limiti, E.; Paoloni, C.

    2013-01-01

    A non-uniform drain line distributed power amplifier (DPA) employing a broadband impedance transformer is presented. The DPA is based on GaAs PHEMT technology. The impedance transformer employs asymmetric coupled lines and transforms a low output impedance of the amplifier to a standard 50 Ω tran...

  20. Estimating the Transverse Impedance in the Fermilab Recycler

    Energy Technology Data Exchange (ETDEWEB)

    Ainsworth, Robert [Fermilab; Adamson, Philip [Fermilab; Burov, Alexey [Fermilab; Kourbanis, Ioanis [Fermilab; Yang, Ming-Jen [Fermilab

    2016-06-01

    Impedance could represent a limitation of running high intensity bunches in the Fermilab recycler. With high intensity upgrades foreseen, it is important to quantify the impedance. To do this, studies have been performed measuring the tune shift as a function of bunch intensity allowing the transverse impedance to be derived.

  1. Concentration Impedance in Testing of Solid Oxide Cells Revisited

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Ebbesen, Sune Dalgaard; Jensen, Søren Højgaard

    2017-01-01

    The concentration impedance originating from diffusion and reactant conversion impedance of the Ni-YSZ supported fuel electrode in solid oxide cell has been treated many times during the latest couple of decades. In spite of this, the separation of the diffusion impedance from the conversion...

  2. Small intestinal transplantation.

    LENUS (Irish Health Repository)

    Quigley, E M

    2012-02-03

    The past few years have witnessed a considerable shift in the clinical status of intestinal transplantation. A great deal of experience has been gained at the most active centers, and results comparable with those reported at a similar stage in the development of other solid-organ graft programs are now being achieved by these highly proficient transplant teams. Rejection and its inevitable associate, sepsis, remain ubiquitous, and new immunosuppressant regimes are urgently needed; some may already be on the near horizon. The recent success of isolated intestinal grafts, together with the mortality and morbidity attendant upon the development of advanced liver disease related to total parenteral nutrition, has prompted the bold proposal that patients at risk for this complication should be identified and should receive isolated small bowel grafts before the onset of end-stage hepatic failure. The very fact that such a suggestion has begun to emerge reflects real progress in this challenging field.

  3. Bioelectrical impedance analysis of bovine milk fat

    International Nuclear Information System (INIS)

    Veiga, E A; Bertemes-Filho, P

    2012-01-01

    Three samples of 250ml at home temperature of 20°C were obtained from whole, low fat and fat free bovine UHT milk. They were analysed by measuring both impedance spectra and dc conductivity in order to establish the relationship between samples related to fat content. An impedance measuring system was developed, which is based on digital oscilloscope, a current source and a FPGA. Data was measured by the oscilloscope in the frequency 1 kHz to 100 kHz. It was showed that there is approximately 7.9% difference in the conductivity between whole and low fat milk whereas 15.9% between low fat and free fat one. The change of fatness in the milk can be significantly sensed by both impedance spectra measurements and dc conductivity. This result might be useful for detecting fat content of milk in a very simple way and also may help the development of sensors for measuring milk quality, as for example the detection of mastitis.

  4. Bioelectrical impedance analysis of bovine milk fat

    Science.gov (United States)

    Veiga, E. A.; Bertemes-Filho, P.

    2012-12-01

    Three samples of 250ml at home temperature of 20°C were obtained from whole, low fat and fat free bovine UHT milk. They were analysed by measuring both impedance spectra and dc conductivity in order to establish the relationship between samples related to fat content. An impedance measuring system was developed, which is based on digital oscilloscope, a current source and a FPGA. Data was measured by the oscilloscope in the frequency 1 kHz to 100 kHz. It was showed that there is approximately 7.9% difference in the conductivity between whole and low fat milk whereas 15.9% between low fat and free fat one. The change of fatness in the milk can be significantly sensed by both impedance spectra measurements and dc conductivity. This result might be useful for detecting fat content of milk in a very simple way and also may help the development of sensors for measuring milk quality, as for example the detection of mastitis.

  5. Application of impedance spectroscopy to SOFC research

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, G.; Mason, T.O. [Northwestern Univ., Evanston, IL (United States); Pederson, L.R. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-12-31

    With the resurgence of interest in solid oxide fuel cells and other solid state electrochemical devices, techniques originally developed for characterizing aqueous systems are being adapted and applied to solid state systems. One of these techniques, three-electrode impedance spectroscopy, is particularly powerful as it allows characterization of subcomponent and interfacial properties. Obtaining accurate impedance spectra, however, is difficult as reference electrode impedance is usually non-negligible and solid electrolytes typically have much lower conductance than aqueous solutions. Faidi et al and Chechirlian et al have both identified problems associated with low conductivity media. Other sources of error are still being uncovered. Ford et al identified resistive contacts with large time constants as a possibility, while Me et al showed that the small contact capacitance of the reference electrode was at fault. Still others show that instrument limitations play a role. Using the voltage divider concept, a simplified model that demonstrates the interplay of these various factors, predicts the form of possible distortions, and offers means to minimize errors is presented.

  6. Beam impedance of ferrite kicker magnets

    International Nuclear Information System (INIS)

    Voelker, F.; Lambertson, G.

    1989-03-01

    We have measured the longitudinal beam impedance of a typical pulsed magnet that will be used in the Advanced Light Source. The magnets are of a ferrite window-frame design with a single plate conductor on each side. Two separate power supplies are used to drive current in opposite directions in the two conductors. The continuity of the ferrite yoke is interrupted by two copper plates 1 mm thick in the center of the top and bottom of the window frame. This increases the reluctance of the magnetic path, and thus decreases the flux which couples the beam. The measurements were made by exciting a 1/8'' rod along the beam path through the magnet. This makes a 185 ohm transmission line, and it was terminated in a resistive divider at the exit end. A 3 GHz network analyzer was used to measure S 21 through the magnet, and longitudinal beam impedance was calculated from this data. The impedance is dominated by two low frequency resonances in the magnet winding and drive current. 8 figs

  7. AC impedance diagnosis of a 500 W PEM fuel cell stack . Part I: Stack impedance

    Science.gov (United States)

    Yuan, Xiaozi; Sun, Jian Colin; Blanco, Mauricio; Wang, Haijiang; Zhang, Jiujun; Wilkinson, David P.

    Diagnosis of stack performance is of importance to proton exchange membrane (PEM) fuel cell research. This paper presents the diagnostic testing results of a 500 W Ballard Mark V PEM fuel cell stack with an active area of 280 cm 2 by electrochemical impedance spectroscopy (EIS). The EIS was measured using a combination of a FuelCon test station, a TDI loadbank, and a Solartron 1260 Impedance/Gain-Phase Analyzer operating in the galvanostatic mode. The method described in this work can obtain the impedance spectra of fuel cells with a larger geometric surface area and power, which are normally difficult to measure due to the limitations on commercial load banks operating at high currents. By using this method, the effects of temperature, flow rate, and humidity on the stack impedance spectra were examined. The results of the electrochemical impedance analysis show that with increasing temperature, the charge transfer resistance decreases due to the slow oxygen reduction reaction (ORR) process at low temperature. If the stack is operated at a fixed air flow rate, a low frequency arc appears and grows with increasing current due to the shortage of air. The anode humidification cut-off does not affect the spectra compared to the cut-off for cathode humidification.

  8. The Influence of Segmental Impedance Analysis in Predicting Validity of Consumer Grade Bioelectrical Impedance Analysis Devices

    Science.gov (United States)

    Sharp, Andy; Heath, Jennifer; Peterson, Janet

    2008-05-01

    Consumer grade bioelectric impedance analysis (BIA) instruments measure the body's impedance at 50 kHz, and yield a quick estimate of percent body fat. The frequency dependence of the impedance gives more information about the current pathway and the response of different tissues. This study explores the impedance response of human tissue at a range of frequencies from 0.2 - 102 kHz using a four probe method and probe locations standard for segmental BIA research of the arm. The data at 50 kHz, for a 21 year old healthy Caucasian male (resistance of 180φ±10 and reactance of 33φ±2) is in agreement with previously reported values [1]. The frequency dependence is not consistent with simple circuit models commonly used in evaluating BIA data, and repeatability of measurements is problematic. This research will contribute to a better understanding of the inherent difficulties in estimating body fat using consumer grade BIA devices. [1] Chumlea, William C., Richard N. Baumgartner, and Alex F. Roche. ``Specific resistivity used to estimate fat-free mass from segmental body measures of bioelectrical impedance.'' Am J Clin Nutr 48 (1998): 7-15.

  9. Small intestinal cytochromes P450.

    Science.gov (United States)

    Kaminsky, L S; Fasco, M J

    1991-01-01

    Small intestinal cytochromes P450 (P450) provide the principal, initial source of biotransformation of ingested xenobiotics. The consequences of such biotransformation are detoxification by facilitating excretion, or toxification by bioactivation. P450s occur at highest concentrations in the duodenum, near the pylorus, and at decreasing concentrations distally--being lowest in the ileum. Highest concentrations occur from midvillus to villous tip, with little or none occurring in the crypts of Lieberkuehn. Microsomal P4503A, 2C8-10, and 2D6 forms have been identified in human small intestine, and P450s 2B1, possibly 2B2, 2A1, and 3A1/2 were located in endoplasmic reticulum of rodent small intestine, while P4502B4 has been purified to electrophoretic homogeneity from rabbit intestine. Some evidence indicates a differential distribution of P450 forms along the length of the small intestine and even along the villus. Rat intestinal P450s are inducible by xenobiotics--with phenobarbital (PB) inducing P4502B1, 3-methylcholanthrene (3-MC) inducing P4501A1, and dexamethasone inducing two forms of P4503A. Induction is most effectively achieved by oral administration of the agents, and is rapid--aryl hydrocarbon hydroxylase (AHH) was increased within 1 h of administration of, for example, 3-MC. AHH, 7-ethoxycoumarin O-deethylase (ECOD), and 7-ethoxyresorufin O-deethylase (EROD) have been used most frequently as substrates to characterize intestinal P450s. Dietary factors affect intestinal P450s markedly--iron restriction rapidly decreased intestinal P450 to beneath detectable values; selenium deficiency acted similarly but was less effective; Brussels sprouts increased intestinal AHH activity 9.8-fold, ECOD activity 3.2-fold, and P450 1.9-fold; fried meat and dietary fat significantly increased intestinal EROD activity; a vitamin A-deficient diet increased, and a vitamin A-rich diet decreased intestinal P450 activities; and excess cholesterol in the diet increased intestinal

  10. Effect of rib-cage structure on acoustic chest impedance

    DEFF Research Database (Denmark)

    Zimmermann, Niels Henrik; Møller, Henrik; Hansen, John

    2011-01-01

    even weak sounds originating from e.g. the heart. The acoustic impedance is influenced by the structure of the ribcage; hence the acoustic impedance will change depending on if the coupler has been placed on a top of a rib or between the ribs (the intercostal). The impedance of the chest is measured....... The measurements reveal the structure of the ribcage from an acoustic point of view in addition to describing the variation of the impedance depending on the position of the coupler. The measurements are carried out on a small number of subjects. The assessment of the ribcage structure based on impedance...

  11. Acoustic impedances of audiometric earphones coupled to different loads

    DEFF Research Database (Denmark)

    Ciric, Dejan; Hammershøi, Dorte

    2005-01-01

    . The importance of this impedance is related to the contribution of other elements involved in transmission such as ear canal impedance or impedance of the coupler seen from outside. In order to determine the acoustic impedances of five audiometric earphones, the standardized method for measurement of complex......, audiometric earphones are coupled to different loads. Thus, they are placed on different terminations of the tube including metal plate, artificial rubber pinna and upper part of the standardized coupler. The results show that the impedances of earphones are different, but they also differ from radiation...... in investigations of coupling of audiometric earphones to human ears and to the same coupler....

  12. Bioelectrical Impedance Methods for Noninvasive Health Monitoring: A Review

    Science.gov (United States)

    Bera, Tushar Kanti

    2014-01-01

    Under the alternating electrical excitation, biological tissues produce a complex electrical impedance which depends on tissue composition, structures, health status, and applied signal frequency, and hence the bioelectrical impedance methods can be utilized for noninvasive tissue characterization. As the impedance responses of these tissue parameters vary with frequencies of the applied signal, the impedance analysis conducted over a wide frequency band provides more information about the tissue interiors which help us to better understand the biological tissues anatomy, physiology, and pathology. Over past few decades, a number of impedance based noninvasive tissue characterization techniques such as bioelectrical impedance analysis (BIA), electrical impedance spectroscopy (EIS), electrical impedance plethysmography (IPG), impedance cardiography (ICG), and electrical impedance tomography (EIT) have been proposed and a lot of research works have been conducted on these methods for noninvasive tissue characterization and disease diagnosis. In this paper BIA, EIS, IPG, ICG, and EIT techniques and their applications in different fields have been reviewed and technical perspective of these impedance methods has been presented. The working principles, applications, merits, and demerits of these methods has been discussed in detail along with their other technical issues followed by present status and future trends. PMID:27006932

  13. Impedance pattern of vaginal and vestibular mucosa in cyclic goats

    Directory of Open Access Journals (Sweden)

    Ivo Křivánek

    2008-01-01

    Full Text Available The changes of vaginal and vestibular impedance during the oestrous cycle in goats were examined. The onset of oestrus was teased with a buck once a day during the experiment. Impedance was mea­sured by a four-terminal method. The vaginal impedance was recorded under slight pressure of electrodes to the vaginal dorsal wall at the cervix. The vestibular impedance was recorded under slight pressure of electrodes to the vestibular dorsal wall 5 cm from the vulva and at the vulva. The im­pe­dan­ce was measured once a day from 4 days before the expected oestrus to 6 days after onset of oestrus. The vaginal impedance at the cervix decreased during pro-oestrus (P < 0.01 and increased du­ring oestrus (P < 0.01. The vestibular impedance 5 cm from the vulva decreased during pro-oestrus (P < 0.01 and increased after oestrus (P < 0.01. The decrease of vaginal impedance during peri-oestrus was nearly twofold in comparison with the vestibular impedance 5 cm from the vulva. No sig­ni­fi­cant decrease of the vestibular impedance at the vulva was found during the oestrous cycle. The results indicate that the vaginal impedance at the cervix and vestibular impedance 5 cm from the vulva measured by means of a four-terminal method during the oestrous cycle display cyclic changes that are closely related to the oestrous behaviour of goats.

  14. Mechanism of the formation for thoracic impedance change.

    Science.gov (United States)

    Kuang, Ming-Xing; Xiao, Qiu-Jin; Cui, Chao-Ying; Kuang, Nan-Zhen; Hong, Wen-Qin; Hu, Ai-Rong

    2010-03-01

    The purpose of this study is to investigate the mechanism of the formation for thoracic impedance change. On the basis of Ohm's law and the electrical field distribution in the cylindrical volume conductor, the formula about the thoracic impedance change are deduced, and they are demonstrated with the model experiment. The results indicate that the thoracic impedance change caused by single blood vessel is directly proportional to the ratio of the impedance change to the basal impedance of the blood vessel itself, to the length of the blood vessel appearing between the current electrodes, and to the basal impedance between two detective electrodes on the chest surface, while it is inversely proportional to the distance between the blood vessel and the line joining two detective electrodes. The thoracic impedance change caused by multiple blood vessels together is equal to the algebraic addition of all thoracic impedance changes resulting from the individual blood vessels. That is, the impedance changes obey the principle of adding scalars in the measurement of the electrical impedance graph. The present study can offer the theoretical basis for the waveform reconstruction of Impedance cardiography (ICG).

  15. Superconducting fault current-limiter with variable shunt impedance

    Science.gov (United States)

    Llambes, Juan Carlos H; Xiong, Xuming

    2013-11-19

    A superconducting fault current-limiter is provided, including a superconducting element configured to resistively or inductively limit a fault current, and one or more variable-impedance shunts electrically coupled in parallel with the superconducting element. The variable-impedance shunt(s) is configured to present a first impedance during a superconducting state of the superconducting element and a second impedance during a normal resistive state of the superconducting element. The superconducting element transitions from the superconducting state to the normal resistive state responsive to the fault current, and responsive thereto, the variable-impedance shunt(s) transitions from the first to the second impedance. The second impedance of the variable-impedance shunt(s) is a lower impedance than the first impedance, which facilitates current flow through the variable-impedance shunt(s) during a recovery transition of the superconducting element from the normal resistive state to the superconducting state, and thus, facilitates recovery of the superconducting element under load.

  16. Mechanical Impedance Modeling of Human Arm: A survey

    Science.gov (United States)

    Puzi, A. Ahmad; Sidek, S. N.; Sado, F.

    2017-03-01

    Human arm mechanical impedance plays a vital role in describing motion ability of the upper limb. One of the impedance parameters is stiffness which is defined as the ratio of an applied force to the measured deformation of the muscle. The arm mechanical impedance modeling is useful in order to develop a better controller for system that interacts with human as such an automated robot-assisted platform for automated rehabilitation training. The aim of the survey is to summarize the existing mechanical impedance models of human upper limb so to justify the need to have an improved version of the arm model in order to facilitate the development of better controller of such systems with ever increase in complexity. In particular, the paper will address the following issue: Human motor control and motor learning, constant and variable impedance models, methods for measuring mechanical impedance and mechanical impedance modeling techniques.

  17. Longitudinal impedance calculation of coated ceramic vacuum chamber at HLS

    International Nuclear Information System (INIS)

    Wang Lin; Xu Hongliang; Shang Lei; Wang Xiangqi; Li Weimin

    2003-01-01

    The purpose of this paper is to estimate the longitudinal coupling impedance of the coated ceramic vacuum chamber employed in new injection system of Hefei Light Source. For the regular axially symmetric boundary, the analytical results of the impedance for the coated ceramic chamber can be easily obtained by application field matching techniques to Maxwell equations in cylindrical coordinate system. For the irregular boundary used in HLS, it is very hard to obtain analytical result of impedance. Based on the impedance measurement principle of coaxial wire method, the impedance of ceramic chamber was numerically calculated. The calculated results showed that, although coating inside ceramic chamber can reduce impedance by some factor, the coated ceramic chamber is one of the main impedance sources of HLS storage ring

  18. Lipo sarcoma in small intestine

    International Nuclear Information System (INIS)

    Rodriguez Iglesias, J.; Pineyro Gutierrez, A.; Taroco Medeiros, L.; Fein Kolodny, C.; Navarrete Pedocchi, H.

    1987-01-01

    A case is presented by primitive liposarcoma in small intestine , an extensive bibliographical review foreigner and national in this case. It detach the exceptional of the intestinal topography of the liposarcomas; and making stress in the relative value of the computerized tomography and ultrasonography in the diagnose of the small intestine tumors . As well as in the sarcomas of another topography, chemo and radiotherapy associated to the exeresis surgery, it can be of benefit [es

  19. Hereditary intestinal polyposis syndromes.

    Science.gov (United States)

    Dean, P A

    1996-01-01

    Colorectal cancer is one of the most common cancers in the world, with overall mortality exceeding 40% even with treatment. Effective efforts for screening and prevention are most likely to succeed in patient groups identified as high risk for colorectal cancer, most notably the hereditary intestinal polyposis syndromes. In these syndromes, benign polyps develop throughout the intestinal tract prior to the development of colorectal cancer, marking the patient and associated family for precancer diagnosis followed by either close surveillance or preventive treatment. This review article was undertaken to discuss the most recent developments in the knowledge of hereditary intestinal polyposis syndromes, emphasizing the clinical approach to diagnosis and treatment relative to preventing the development of cancer. The most common of the hereditary polyposis syndromes is familial adenomatous polyposis (FAP), which is characterized by the development of hundreds to thousands of adenomatous polyps in the colon followed at an early age by colorectal cancer. Colorectal cancer can be prevented in this autosomal dominant condition by prophylactic colectomy, though a risk for other tumors, including periampullary cancers, remains throughout life. Variant of FAP associated with fewer and smaller polyps (hereditary flat adenoma syndrome), or even CNS tumors (Turcot's syndrome) also carry this high risk of colorectal cancer. Hereditary hamartomatous polyposis syndromes such as juvenile polyposis and Peutz-Jeghers syndrome (also autosomal dominant) are characterized by less frequent polyps. Though these are generally benign polyps, they are also associated with a significant risk of colorectal and other cancers. Other polyposis syndromes, including neurofibromatosis and Cowden's disease, do not carry this increased risk of colorectal cancer, and therefore affect different treatment strategies. Analysis of genetic factors responsible for these and other hereditary syndromes with

  20. Broadband Planar 5:1 Impedence Transformer

    Science.gov (United States)

    Ehsan, Negar; Hsieh, Wen-Ting; Moseley, Samuel H.; Wollack, Edward J.

    2015-01-01

    This paper presents a broadband Guanella-type planar impedance transformer that transforms so 50 omega to 10 omega with a 10 dB bandwidth of 1-14GHz. The transformer is designed on a flexible 50 micrometer thick polyimide substrate in microstrip and parallel-plate transmission line topologies, and is Inspired by the traditional 4:1 Guanella transformer. Back-to-back transformers were designed and fabricated for characterization in a 50 omega system. Simulated and measured results are in excellent agreement.

  1. Real-Time Thevenin Impedance Computation

    DEFF Research Database (Denmark)

    Sommer, Stefan Horst; Jóhannsson, Hjörtur

    2013-01-01

    Stable and secure operation of power systems becomes increasingly difficult when a large share of the power production is based on distributed and non-controllable renewable energy sources. Real-time stability assessment is dependent on very fast computation of different properties of the grid......, and parallelization, we develop an algorithm for computing Thevenin impedances an order of magnitude faster than previous approaches. We test the factor-and-solve algorithm with data from several power grids of varying complexity, and we show how the algorithm allows realtime stability assessment of complex power...

  2. Techniques for beam impedance measurements above cutoff

    International Nuclear Information System (INIS)

    Lambertson, G.R.; Jacob, A.F.; Rimmer, R.A.; Voelker, F.

    1990-08-01

    Methods for measuring beam impedance above cutoff have been very limited. For design work on the ALS we have developed two techniques that yield data in the frequency domain with high sensitivity. The first is an extension of the wire method; the second utilizes traveling TM waves to simulate the beam's fields at the wall, and thus avoids the mechanical difficulties of mounting the wire. It is also more sensitive than the other method but the interpretation is complicated by the presence of higher order modes. With either method we were able to detect resonant peaks smaller than 1 Ohm at 10 GHz

  3. Variational constraints for electrical-impedance tomography

    International Nuclear Information System (INIS)

    Berryman, J.G.; Kohn, R.V.

    1990-01-01

    The task of electrical-impedance tomography is to invert boundary measurements for the conductivity distribution of a body. This inverse problem can be formulated so the primary data are the measured powers dissipated across injection electrodes. Then, since these powers are minima of the pertinent (dual) variational principles, feasibility constraints can be found for the nonlinear inversion problem. When power may be measured accurately, the existence of these dual variational principles implies that any exact solution must lie at a point of intersection of the two feasibility boundaries

  4. Transferring human impedance regulation skills to robots

    CERN Document Server

    Ajoudani, Arash

    2016-01-01

    This book introduces novel thinking and techniques to the control of robotic manipulation. In particular, the concept of teleimpedance control as an alternative method to bilateral force-reflecting teleoperation control for robotic manipulation is introduced. In teleimpedance control, a compound reference command is sent to the slave robot including both the desired motion trajectory and impedance profile, which are then realized by the remote controller. This concept forms a basis for the development of the controllers for a robotic arm, a dual-arm setup, a synergy-driven robotic hand, and a compliant exoskeleton for improved interaction performance.

  5. Magnetically Coupled Impedance-Source Inverters

    DEFF Research Database (Denmark)

    Loh, Poh Chiang; Blaabjerg, Frede

    2013-01-01

    input-to-output gain and the presence of an impedance network. The former means a high dc-link voltage, which can stress the semiconductor switches unnecessarily. The latter leads to increases in cost and size, which similarly are undesirable. To lessen these concerns, an interesting approach is to use...... magnetically coupled transformers or inductors to raise the gain and modulation ratio simultaneously, while reducing the number of passive components needed. A study of the approach is now presented to show how various existing magnetically coupled inverters can be derived by applying a generic methodology...

  6. Method for conducting nonlinear electrochemical impedance spectroscopy

    Science.gov (United States)

    Adler, Stuart B.; Wilson, Jamie R.; Huff, Shawn L.; Schwartz, Daniel T.

    2015-06-02

    A method for conducting nonlinear electrochemical impedance spectroscopy. The method includes quantifying the nonlinear response of an electrochemical system by measuring higher-order current or voltage harmonics generated by moderate-amplitude sinusoidal current or voltage perturbations. The method involves acquisition of the response signal followed by time apodization and fast Fourier transformation of the data into the frequency domain, where the magnitude and phase of each harmonic signal can be readily quantified. The method can be implemented on a computer as a software program.

  7. Impedance matched thin metamaterials make metals absorbing.

    Science.gov (United States)

    Mattiucci, N; Bloemer, M J; Aközbek, N; D'Aguanno, G

    2013-11-13

    Metals are generally considered good reflectors over the entire electromagnetic spectrum up to their plasma frequency. Here we demonstrate an approach to tailor their absorbing characteristics based on the effective metamaterial properties of thin, periodic metallo-dielectric multilayers by exploiting a broadband, inherently non-resonant, surface impedance matching mechanism. Based on this mechanism, we design, fabricate and test omnidirectional, thin ( 99%) over a frequency range spanning from the UV to the IR. Our approach opens new venues to design cost effective materials for many applications such as thermo-photovoltaic energy conversion devices, light harvesting for solar cells, flat panel display, infrared detectors, stray light reduction, stealth and others.

  8. Development of the impedance void meter

    International Nuclear Information System (INIS)

    Chung, Moon Ki; Song, Chul Hwa; Won, Soon Yeon; Kim, Bok Deuk

    1994-06-01

    An impedance void meter is developed to measure the area-averaged void fraction. Its basic principle is based on the difference in the electrical conductivity between phases. Several methods of measuring void fraction are briefly reviewed and the reason why this type of void meter is chosen to develop is discussed. Basic principle of the measurement is thoroughly described and several design parameters to affect the overall function are discussed in detail. As example of applications is given for vertical air-water flow. It is shown that the current design has good dynamic response as well as very fine spatial resolution. (Author) 47 refs., 37 figs

  9. Bioelectrical impedance analysis--part I

    DEFF Research Database (Denmark)

    Kyle, Ursula G; Bosaeus, Ingvar; De Lorenzo, Antonio D

    2004-01-01

    The use of bioelectrical impedance analysis (BIA) is widespread both in healthy subjects and patients, but suffers from a lack of standardized method and quality control procedures. BIA allows the determination of the fat-free mass (FFM) and total body water (TBW) in subjects without significant...... of the estimate. The determination of changes in body cell mass (BCM), extra cellular (ECW) and intra cellular water (ICW) requires further research using a valid model that guarantees that ECW changes do not corrupt the ICW. The use of segmental-BIA, multifrequency BIA, or bioelectrical spectroscopy in altered...

  10. Bioelectrical Impedance Assessment of Wound Healing

    Science.gov (United States)

    Lukaski, Henry C; Moore, Micheal

    2012-01-01

    Objective assessment of wound healing is fundamental to evaluate therapeutic and nutritional interventions and to identify complications. Despite availability of many techniques to monitor wounds, there is a need for a safe, practical, accurate, and effective method. A new method is localized bioelectrical impedance analysis (BIA) that noninvasively provides information describing cellular changes that occur during healing and signal complications to wound healing. This article describes the theory and application of localized BIA and provides examples of its use among patients with lower leg wounds. This promising method may afford clinicians a novel technique for routine monitoring of interventions and surveillance of wounds. PMID:22401341

  11. LHC MD 232: Longitudinal Impedance Evaluation

    CERN Document Server

    Esteban Muller, Juan; Baudrenghien, Philippe; Shaposhnikova, Elena; CERN. Geneva. ATS Department

    2017-01-01

    The aim of the MDstudies presented here was to evaluate the imaginary part of the longitudinal impedance of the LHC by means of synchrotron frequency shift measurements. Single bunches with similar longitudinal emittance but different intensities were studied at flat top. Based on the beam parameters, a maximum shift of about 0.2 Hz was expected between the different bunches. A detailed analysis still needs to be carried out to determine the measured synchrotron frequency shift. The measurements took place between 8:00 p.m. on 26th and 2:00 a.m. on 27th July 2016

  12. Modeling of Impedance of Porous Electrodes

    Science.gov (United States)

    Lasia, Andrzej

    Porous electrodes are very important in practical applications of electrocatalysis, where an increase in the real surface area leads to an increase in catalytic activity. Porous electrodes are used in gas evolution (water electrolysis, hydrogen and oxygen evolution, chlorine evolution), electrocatalytic hydrogenation or oxidation of organic compounds, in batteries, fuel cells, etc. Good knowledge of the porous electrode theory permits for the construction of the electrodes with optimal utilization of the active electrode material. The porous electrode model was first developed by several authors for dc conditions (1-6) and later applied to the impedance studies.

  13. Electrochemical impedance spectroscopy of polynucleotide adsorption

    Czech Academy of Sciences Publication Activity Database

    Strašák, Luděk; Dvořák, Jakub; Hasoň, Stanislav; Vetterl, Vladimír

    2002-01-01

    Roč. 56, 1/2 (2002), s. 37-41 ISSN 1567-5394 R&D Projects: GA AV ČR IAA4004002; GA AV ČR IBS5004107; GA ČR GV204/97/K084 Grant - others:GA FRVŠ(XC) G40583; GA FRVŠ(XC) F40564 Institutional research plan: CEZ:AV0Z5004920 Keywords : electrochemical impedance spectroscopy * DNA adsorption * poly A adsorption Subject RIV: BO - Biophysics Impact factor: 1.463, year: 2002

  14. The electrochemical impedance of metal hydride electrodes

    DEFF Research Database (Denmark)

    Valøen, Lars Ole; Lasia, Andrzej; Jensen, Jens Oluf

    2002-01-01

    , explaining the experimental impedances in a wide frequency range for electrodes of hydride forming materials mixed with copper powder, were obtained. Both charge transfer and spherical diffusion of hydrogen in the particles are important sub processes that govern the total rate of the electrochemical...... hydrogen absorption/desorption reaction. To approximate the experimental data, equations describing the current distribution in porous electrodes were needed. Indications of one or more parallel reduction/oxidation processes competing with the electrochemical hydrogen absorption/desorption reaction were...

  15. Intestinal parasites : associations with intestinal and systemic inflammation

    NARCIS (Netherlands)

    Zavala, Gerardo A; García, Olga P; Camacho, Mariela; Ronquillo, Dolores; Campos-Ponce, Maiza; Doak, Colleen; Polman, Katja; Rosado, Jorge L

    2018-01-01

    AIMS: Evaluate associations between intestinal parasitic infection with intestinal and systemic inflammatory markers in school-aged children with high rates of obesity. METHODS AND RESULTS: Plasma concentrations of CRP, leptin, TNF-α, IL-6 and IL-10 were measured as systemic inflammation markers and

  16. Ischemic small intestine-in vivo versus ex vivo bioimpedance measurements.

    Science.gov (United States)

    Strand-Amundsen, Runar J; Reims, Henrik M; Tronstad, Christian; Kalvøy, Håvard; Martinsen, Ørjan G; Høgetveit, Jan O; Ruud, Tom E; Tønnessen, Tor I

    2017-05-01

    Bioimpedance has been used to investigate changes in electrical parameters during ischemia in various tissues. The small intestine is a multi-layered structure, with several distinct tissue types, and ischemia related changes occur at different times in the different intestinal layers. When investigating how the electrical properties in the small intestine is affected by ischemia, some researchers have used ex vivo models while others have used in vivo models. In this study, we compare ischemic time development of electrical parameters in ischemic in vivo versus ex vivo small intestine. Measurements were performed using a two-electrode setup, with a Solartron 1260/1294 impedance gain-phase analyser. Electrodes were placed on the surface of ischemic pig jejunum, applying a voltage and measuring the resulting electrical admittance. In each pig, 4 segments of the jejunum were made ischemic by clamping the mesenteric arteries and veins, resulting in a 30 cm central zone of warm ischemia and edema. The in vivo part of the experiment lasted 10 h, after which 3 pieces of perfused small intestine were resected, stored in Ringer-acetat at 38 °C, and measured during a 10 h ex vivo experiment. Main results and significance: We found significant differences (p  vivo and ex vivo measurements as a function of ischemic time development. We also observed some similarities in the trends. In vivo, we measured an overall decrease in impedance during the duration of the experiment, probably as a result from the formation of edema. Ex vivo, the low frequency impedance increased initially for approximately 3 h before starting to decrease.

  17. Study on Impedance Characteristics of Aircraft Cables

    Directory of Open Access Journals (Sweden)

    Weilin Li

    2016-01-01

    Full Text Available Voltage decrease and power loss in distribution lines of aircraft electric power system are harmful to the normal operation of electrical equipment and may even threaten the safety of aircraft. This study investigates how the gap distance (the distance between aircraft cables and aircraft skin and voltage frequency (variable frequency power supply will be adopted for next generation aircraft will affect the impedance of aircraft cables. To be more precise, the forming mechanism of cable resistance and inductance is illustrated in detail and their changing trends with frequency and gap distance are analyzed with the help of electromagnetic theoretical analysis. An aircraft cable simulation model is built with Maxwell 2D and the simulation results are consistent with the conclusions drawn from the theoretical analysis. The changing trends of the four core parameters of interest are analyzed: resistance, inductance, reactance, and impedance. The research results can be used as reference for the applications in Variable Speed Variable Frequency (VSVF aircraft electric power system.

  18. Cytokines and intestinal inflammation.

    Science.gov (United States)

    Bamias, Giorgos; Cominelli, Fabio

    2016-11-01

    Cytokines of the intestinal microenvironment largely dictate immunological responses after mucosal insults and the dominance of homeostatic or proinflammatory pathways. This review presents important recent studies on the role of specific cytokines in the pathogenesis of intestinal inflammation. The particular mucosal effects of cytokines depend on their inherent properties but also the cellular origin, type of stimulatory antigens, intermolecular interactions, and the particular immunological milieu. Novel cytokines of the interleukin-1 (IL-1) family, including IL-33 and IL-36, have dominant roles in mucosal immunity, whereas more established ones such as IL-18 are constantly enriched with unique properties. Th17 cells are important mucosal constituents, although their profound plasticity, makes the specific set of cytokines they secrete more important than their mere numbers. Finally, various cytokines, such as tumor necrosis factor-α, IL-6, tumor necrosis factor-like cytokine 1A, and death receptor, 3 demonstrate dichotomous roles with mucosa-protective function in acute injury but proinflammatory effects during chronic inflammation. The role of cytokines in mucosal health and disease is increasingly revealed. Such information not only will advance our understanding of the pathogenesis of gut inflammation, but also set the background for development of reliable diagnostic and prognostic biomarkers and cytokine-specific therapies.

  19. Hippo signalling directs intestinal fate

    DEFF Research Database (Denmark)

    le Bouteiller, Marie Catherine M; Jensen, Kim Bak

    2015-01-01

    Hippo signalling has been associated with many important tissue functions including the regulation of organ size. In the intestinal epithelium differing functions have been proposed for the effectors of Hippo signalling, YAP and TAZ1. These are now shown to have a dual role in the intestinal epit...

  20. MDCT in blunt intestinal trauma

    Energy Technology Data Exchange (ETDEWEB)

    Romano, Stefania [Department of Diagnostic Imaging, ' A.Cardarelli' Hospital, 80131 Naples (Italy)]. E-mail: stefromano@libero.it; Scaglione, Mariano [Department of Diagnostic Imaging, ' A.Cardarelli' Hospital, 80131 Naples (Italy); Tortora, Giovanni [Department of Diagnostic Imaging, ' A.Cardarelli' Hospital, 80131 Naples (Italy); Martino, Antonio [Trauma Center, ' A.Cardarelli' Hospital, 80131 Naples (Italy); Di Pietto, Francesco [Department of Diagnostic Imaging, ' A.Cardarelli' Hospital, 80131 Naples (Italy); Romano, Luigia [Department of Diagnostic Imaging, ' A.Cardarelli' Hospital, 80131 Naples (Italy); Grassi, Roberto [Department ' Magrassi-Lanzara' , Section of Radiology, Second University of Naples, 80138 Naples (Italy)

    2006-09-15

    Injuries to the small and large intestine from blunt trauma represent a defined clinical entity, often not easy to correctly diagnose in emergency but extremely important for the therapeutic assessment of patients. This article summarizes the MDCT spectrum of findings in intestinal blunt lesions, from functional disorders to hemorrhage and perforation.

  1. MDCT in blunt intestinal trauma

    International Nuclear Information System (INIS)

    Romano, Stefania; Scaglione, Mariano; Tortora, Giovanni; Martino, Antonio; Di Pietto, Francesco; Romano, Luigia; Grassi, Roberto

    2006-01-01

    Injuries to the small and large intestine from blunt trauma represent a defined clinical entity, often not easy to correctly diagnose in emergency but extremely important for the therapeutic assessment of patients. This article summarizes the MDCT spectrum of findings in intestinal blunt lesions, from functional disorders to hemorrhage and perforation

  2. Immunity to intestinal pathogens: lessons learned from Salmonella

    Science.gov (United States)

    McSorley, Stephen J.

    2014-01-01

    Summary Salmonella are a common source of food or water-borne infection and cause a wide range of clinical disease in human and animal hosts. Salmonella are relatively easy to culture and manipulate in a laboratory setting, and the infection of laboratory animals induces robust innate and adaptive immune responses. Thus, immunologists have frequently turned to Salmonella infection models to expand understanding of immunity to intestinal pathogens. In this review, I summarize current knowledge of innate and adaptive immunity to Salmonella and highlight features of this response that have emerged from recent studies. These include the heterogeneity of the antigen-specific T-cell response to intestinal infection, the prominence of microbial mechanisms to impede T and B-cell responses, and the contribution of non-cognate pathways for elicitation of T-cell effector functions. Together, these different issues challenge an overly simplistic view of host-pathogen interaction during mucosal infection but also allow deeper insight into the real-world dynamic of protective immunity to intestinal pathogens. PMID:24942689

  3. Impedance analysis of the PEP-II vacuum chamber

    International Nuclear Information System (INIS)

    Ng, C.K.; Weiland, T.

    1995-05-01

    The PEP-II high energy ring (HER) vacuum chamber consists of a copper tube with periodically spaced pumping slots. The impedance of the vacuum chamber due to the slots is analyzed. Both narrow-band and broadband impedances are considered as well as longitudinal and transverse components thereof. It is found that although the broad-band impedance is tolerable, the narrow-band impedance may exceed the instability limit given by the natural damping with no feedback system on. Traveling wave modes in the chamber are the major source of this high value narrow-band impedance. We also study the dependences of the impedance on the slot length and the geometrical cross section

  4. [Body composition assessment by anthropometry and bioelectrical impedance].

    Science.gov (United States)

    Aristizábal, Juan Carlos; Restrepo, María Teresa; Estrada, Alejandro

    2007-06-01

    Anthropometry and electric impedance methods are widely used for body composition assessment. However the evidence is unclear whether the results obtained from the two methods can be compared. Two methods are compared for assessment of body composition; anthropometry and electric impedance. Body composition was measured in 70 women; aged 22 to 56 and 53 men; aged 24 to 54, using anthropometry (Durning/Womersley and Jackson/Pollock skinfolds equations) and electric impedance (foot to foot electric impedance) to obtain percentage body fat. The mean percentage body fat was significant higher with Durning/Womersley (25.2%) than Jackson/Pollock (20.1%) and electric impedance (19.3%) for men (pimpedance (27.6%) for women (p0.77) however, the concordance between methods to classify obesity subjects was low (Kbioelectrical impedance method. A significant difference was found between methods applied in men and women, and therefore these methods are not comparable.

  5. Transverse impedance measurement in RHIC and the AGS

    Energy Technology Data Exchange (ETDEWEB)

    Biancacci, Nicolo [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Blaskiewicz, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Dutheil, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Liu, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Mernick, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Minty, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; White, S. M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-05-12

    The RHIC luminosity upgrade program aims for an increase of the polarized proton luminosity by a factor 2. To achieve this goal a significant increase in the beam intensity is foreseen. The beam coupling impedance could therefore represent a source of detrimental effects for beam quality and stability at high bunch intensities. For this reason it is essential to quantify the accelerator impedance budget and the major impedance sources, and possibly cure them. In this MD note we summarize the results of the 2013 transverse impedance measurements in the AGS and RHIC. The studies have been performed measuring the tune shift as a function of bunch intensity and deriving the total accelerator machine transverse impedance. For RHIC, we could obtain first promising results of impedance localization measurements as well.

  6. Gastric dysrythmia in infants with gastrointestinal diseases measured by epigastric impedance

    DEFF Research Database (Denmark)

    Lange, Aksel; Funch-Jensen, Peter; Schiøtz, Peter Oluf

    2003-01-01

      Background: Gastrointestinal symptoms have been reported in association with myoelectrical dysrhythmia, where different types of gastric electrical activity have been described. These types of gastric myoelectrical activity and dysrhythmia can be measured by electrogastrography using cutaneous...... of impedance gastrography in control infants compared to infants with different gastrointestinal diseases, before and after treatment of their disease.Method: 21 patients (0-2 months) and 40 healthy infants (0-2 months) were investigated. The patients suffered from partial or total intestinal obstruction......, necrotising enterocolitis or pyloric stenosis.     All infants were fasting and were studied during periods of at least one hour. The patients were examined in the acute state and after treatment when possible.Results: A pathological result was found in 90 % of the patients. A persistent phasic activity...

  7. Electrochemical Characterization of a PEMEC Using Impedance Spectroscopy

    OpenAIRE

    Elsøe, Katrine; Grahl-Madsen, L.; Hjelm, Johan; Scherer, G.G.; Hjelm, Johan; Mogensen, Mogens Bjerg

    2017-01-01

    In this study, electrochemical impedance spectroscopy (EIS) is applied in combination with cyclic voltammetry (CV) and current density – cell voltage curves (iV-curves) to investigate the processes contributing to the total impedance of a polymer electrolyte membrane electrolysis cell (PEMEC). iV-curves were linear above 0.35 A cm−2 implying ohmic processes to be performance limiting, however the impedance spectra showed three arcs indicating three electrochemical reactions at these condition...

  8. Management of Elevated Therapeutic Impedances on Deep Brain Stimulation Leads

    OpenAIRE

    Wissam Deeb; Amar Patel; Michael S. Okun; Aysegul Gunduz

    2017-01-01

    Clinical Vignette: A 64-year-old male with a history of essential tremor with bilateral thalamic ventralis intermedius deep brain stimulation implants had elevated therapeutic impedance values despite normal lead integrity impedances and good response to stimulation.Clinical Dilemma: Do elevated therapeutic impedance values indicate a sign of hardware malfunction? What are the guidelines to approach deep brain stimulation hardware malfunction?Clinical Solution: Lead integrity i...

  9. Positive impedance humidity sensors via single-component materials

    OpenAIRE

    Qian, Jingwen; Peng, Zhijian; Shen, Zhenguang; Zhao, Zengying; Zhang, Guoliang; Fu, Xiuli

    2016-01-01

    Resistivity-type humidity sensors have been investigated with great interest due to the increasing demands in industry, agriculture and daily life. To date, most of the available humidity sensors have been fabricated based on negative humidity impedance, in which the electrical resistance decreases as the humidity increases, and only several carbon composites have been reported to present positive humidity impedance. However, here we fabricate positive impedance humidity sensors only via sing...

  10. Modulation of Intestinal Microbiome Prevents Intestinal Ischemic Injury

    Directory of Open Access Journals (Sweden)

    Alessandra Bertacco

    2017-12-01

    Full Text Available Background: Butyrate protects against ischemic injury to the small intestine by reducing inflammation and maintaining the structure of the intestinal barrier, but is expensive, short-lived, and cannot be administered easily due to its odor. Lactate, both economical and more palatable, can be converted into butyrate by the intestinal microbiome. This study aimed to assess in a rat model whether lactate perfusion can also protect against intestinal ischemia.Materials and Methods: Rat intestinal segments were loaded in an in vitro bowel perfusion device, and water absorption or secretion was assessed based on fluorescence of FITC-inulin, a fluorescent marker bound to a biologically inert sugar. Change in FITC concentration was used as a measure of ischemic injury, given the tendency of ischemic cells to retain water. Hematoxylin and eosin-stained sections at light level microscopy were examined to evaluate intestinal epithelium morphology. Comparisons between the data sets were paired Student t-tests or ANOVA with p < 0.05 performed on GraphPad.Results: Lactate administration resulted in a protective effect against intestinal ischemia of similar magnitude to that observed with butyrate. Both exhibited approximately 1.5 times the secretion exhibited by control sections (p = 0.03. Perfusion with lactate and methoxyacetate, a specific inhibitor of lactate-butyrate conversion, abolished this effect (p = 0.09. Antibiotic treatment also eliminated this effect, rendering lactate-perfused sections similar to control sections (p = 0.72. Perfusion with butyrate and methoxyacetate did not eliminate the observed increased secretion, which indicates that ischemic protection was mediated by microbial conversion of lactate to butyrate (p = 0.71.Conclusions: Lactate's protective effect against intestinal ischemia due to microbial conversion to butyrate suggests possible applications in the transplant setting for reducing ischemic injury and ameliorating intestinal

  11. Microgrid Reactive and Harmonic Power Sharing Using Enhanced Virtual Impedance

    DEFF Research Database (Denmark)

    He, Jinwei; Wei Li, Yun; Guerrero, Josep M.

    2013-01-01

    To address the load sharing problem in islanding microgrids, this paper proposes an improved approach which regulates the distributed generation (DG) unit interfacing virtual impedance at fundamental and selected harmonic frequencies. In contrast to the conventional virtual impedance control where...... feeder impedances can be properly compensated, resulting in accurate reactive and harmonic power sharing at the same time. In addition, this paper shows that the microgrid PCC harmonic voltages can be mitigated by reducing the magnitude of DG unit equivalent harmonic impedance. Finally, an improved...

  12. Evaluation of ring impedance of the Photon Factory storage ring

    International Nuclear Information System (INIS)

    Kiuchi, T.; Izawa, M.; Tokumoto, S.; Hori, Y.; Sakanaka, S.; Kobayashi, M.; Kobayakawa, H.

    1992-05-01

    The loss parameters of the ducts in the Photon Factory (PF) storage ring were evaluated using the wire method and the code TBCI. Both the measurement and the calculation were done for a different bunch length (σ) ranging from 23 to 80 ps. The PF ring impedance was estimated to be |Z/n|=3.2 Ω using the broadband impedance model. The major contribution to the impedance comes from the bellows and the gate valve sections. Improvements of these components will lower the ring impedance by half. (author)

  13. Impedance of the PEP-II DIP screen

    Energy Technology Data Exchange (ETDEWEB)

    Ng, C.-K. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Weiland, T.

    1996-08-01

    The vacuum chamber of a storage ring normally consists of periodically spaced pumping slots. The longitudinal impedance of slots are analyzed in this paper. It is found that although the broad-band impedance is tolerable, the narrow-band impedance, as a consequence of the periodicity of the slots, may exceed the stability limit given by natural damping with no feedback system on. Based on this analysis, the PEP-II distributed-ion-pump (DIP) screen uses long grooves with hidden holes cut halfway to reduce both the broad-band and narrow-band impedances. (author)

  14. Impedance Analysis of SOGI-FLL-Based Grid Synchronization

    DEFF Research Database (Denmark)

    Yi, Hao; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    The latest research has pointed out that the Phase-Locked Loop (PLL) plays an important role in shaping the impedance of grid-connected converters, yet most of the works so far merely focus on the synchronous reference-frame PLL. Alternatively, this letter presents the impedance analysis of the S......The latest research has pointed out that the Phase-Locked Loop (PLL) plays an important role in shaping the impedance of grid-connected converters, yet most of the works so far merely focus on the synchronous reference-frame PLL. Alternatively, this letter presents the impedance analysis...

  15. In vivo impedance spectroscopy of deep brain stimulation electrodes

    Science.gov (United States)

    Lempka, Scott F.; Miocinovic, Svjetlana; Johnson, Matthew D.; Vitek, Jerrold L.; McIntyre, Cameron C.

    2009-08-01

    Deep brain stimulation (DBS) represents a powerful clinical technology, but a systematic characterization of the electrical interactions between the electrode and the brain is lacking. The goal of this study was to examine the in vivo changes in the DBS electrode impedance that occur after implantation and during clinically relevant stimulation. Clinical DBS devices typically apply high-frequency voltage-controlled stimulation, and as a result, the injected current is directly regulated by the impedance of the electrode-tissue interface. We monitored the impedance of scaled-down clinical DBS electrodes implanted in the thalamus and subthalamic nucleus of a rhesus macaque using electrode impedance spectroscopy (EIS) measurements ranging from 0.5 Hz to 10 kHz. To further characterize our measurements, equivalent circuit models of the electrode-tissue interface were used to quantify the role of various interface components in producing the observed electrode impedance. Following implantation, the DBS electrode impedance increased and a semicircular arc was observed in the high-frequency range of the EIS measurements, commonly referred to as the tissue component of the impedance. Clinically relevant stimulation produced a rapid decrease in electrode impedance with extensive changes in the tissue component. These post-operative and stimulation-induced changes in impedance could play an important role in the observed functional effects of voltage-controlled DBS and should be considered during clinical stimulation parameter selection and chronic animal research studies.

  16. Electrode contact impedance sensitivity to variations in geometry

    International Nuclear Information System (INIS)

    Cardu, Roberto; Leong, Philip H W; Jin, Craig T; McEwan, Alistair

    2012-01-01

    Electrode contact impedance is a crucial factor in physiological measurements and can be an accuracy-limiting factor when performing electroencephalography and electrical impedance tomography. In this work, standard flat electrodes and micromachined multipoint spiked electrodes are characterized with a finite-element method electromagnetic solver and the dependence of the contact impedance on geometrical factors is explored. It is found that flat electrodes are sensitive to changes in the outer skin layer properties related to hydration and thickness, while spike electrodes are not. The impedance as a function of the effective contact area, number of spikes and penetration depth has also been studied and characterized. (paper)

  17. Proceedings of the impedance and bunch instability workshop

    Energy Technology Data Exchange (ETDEWEB)

    1990-04-01

    This report discusses the following topics: impedance and bunch lengthening; single bunch stability in the ESRF; a longitudinal mode-coupling instability model for bunch lengthening; high-frequency behavior of longitudinal coupling impedance; beam-induced energy spreads at beam-pipe transitions; on the calculation of wake functions using MAFIA-T3 code; preliminary measurements of the bunch length and the impedance of LEP; measurements and simulations of collective effects in the CERN SPS; bunch lengthening in the SLC damping rings; and status of impedance measurements for the spring-8 storage ring.

  18. Multilayer tube impedance and external radiation

    Directory of Open Access Journals (Sweden)

    M. Ivanyan

    2008-08-01

    Full Text Available The paper describes a method for calculating the longitudinal and transverse impedances of the laminated round pipe with many layers of different materials. The charge is moving along the pipe axis with arbitrary constant velocity. The study is based on the field-matching technique applied for the arbitrary harmonic of the electromagnetic field. The matrix formalism has been developed to describe the field transitions through the subsequent layers that allow coupling the electromagnetic fields inside and outside the pipe. The number of equations to be solved is then reduced to four algebraic equations. The solutions and ultrarelativistic limits for the field harmonics in the inner and outer regions of the pipe are derived.

  19. Bioelectrical impedance analysis. What does it measure?

    Science.gov (United States)

    Schoeller, D. A.

    2000-01-01

    Bioelectrical impedance analysis (BIA) has been proposed for measuring fat-free mass, total body water, percent fat, body cell mass, intracellular water, and extracellular water: a veritable laboratory in a box. Although it is unlikely that BIA is quite this versatile, correlations have been demonstrated between BIA and all of these body compartments. At the same time, it is known that all of the compartments are correlated among themselves. Because of this, it is difficult to determine whether BIA is specific for any or all of these compartments. To investigate this question, we induced acute changes in total body water and its compartments over a 3-h period. Using this approach, we demonstrated that multifrequency BIA, using the Cole-Cole model to calculate the zero frequency and infinite frequency resistance, measures extracellular and intracellular water.

  20. Coupled Transmission Lines as Impedance Transformer

    DEFF Research Database (Denmark)

    Jensen, Thomas; Zhurbenko, Vitaliy; Krozer, Viktor

    2007-01-01

    A theoretical investigation of the use of a coupled line section as an impedance transformer is presented. We show how to properly select the terminations of the coupled line structures for effective matching of real and complex loads in both narrow and wide frequency ranges. The corresponding...... circuit configurations and the design procedures are proposed. Synthesis relations are derived and provided for efficient matching circuit construction. Design examples are given to demonstrate the flexibility and limitations of the design methods and to show their validity for practical applications....... Wideband matching performance with relative bandwidth beyond 100% and return loss > 20 dB is demonstrated both theoretically and experimentally. Good agreement is achieved between the measured and predicted performance of the coupled line transformer section....

  1. Relating membrane potential to impedance spectroscopy

    Directory of Open Access Journals (Sweden)

    Eugen Gheorghiu

    2011-12-01

    Full Text Available Non-invasive, label-free assessment of membrane potential of living cells is still a challenging task. The theory linking membrane potential to the low frequency α dispersion exhibited by suspensions of spherical shelled particles (presenting a net charge distribution on the inner side of the shell has been pioneered in our previous studies with emphasis on the permittivity spectra. Whereas α dispersion is related to a rather large variation exhibited by the permittivity spectrum, we report that the related decrement presented by the impedance magnitude spectrum is either extremely small, or occurs (for large cells at very small frequencies (~mHz explaining the lack of experimental bioimpedance data on the matter. We stress that appropriate choice of the parameters (as revealed by the microscopic model may enable access to membrane potential as well as to other relevant parameters when investigating living cells and charged lipid vesicles. We analyse the effect on the low frequency of the permittivity and impedance spectra of: I. Parameters pertaining to cell membrane i.e. (i membrane potential (through the amount of the net charge on the inner side of the membrane, (ii size of the cells/vesicles, (iii conductivity of the membrane; II. Parameters of the extra cellular medium (viscosity and conductivity. The applicability of the study has far reaching implications for basic (life sciences (providing non-invasive access to the dynamics of relevant cell parameters as well as for biosensing applications, e.g. assessment of cytotoxicity of a wide range of stimuli. doi:10.5617/jeb.214 J Electr Bioimp, vol. 2, pp. 93-97, 2011

  2. Chronic intestinal ischaemia: measurement of the total splanchnic blood flow.

    Science.gov (United States)

    Zacho, Helle D

    2013-04-01

    A redundant collateral network between the intestinal arteries is present at all times. In case of ischaemia in the gastrointestinal tract, the collateral blood supply can develop further, thus accommodating the demand for oxygen even in the presence of significant stenosis or occlusion of the intestinal arteries without clinical symptoms of intestinal ischaemia. Symptoms of ischemia develop when the genuine and collateral blood supply no longer can accommodate the need for oxygen. Atherosclerosis is the most common cause of obliteration in the intestinal arteries. In chronic intestinal ischaemia (CII), the fasting splanchnic blood flow (SBF) is sufficient, but the postprandial increase in SBF is inadequate and abdominal pain will therefore develop in relation to food intake causing the patient to eat smaller meals at larger intervals with a resulting weight loss. Traditionally, the CII-diagnosis has exclusively been based upon morphology (angiography) of the intestinal arteries; however, substantial discrepancies between CII-symptoms and the presence of atherosclerosis/stenosis in the intestinal arteries have been described repeatedly in the literature impeding the diagnosis of CII. This PhD thesis explores a method to determine the total SBF and its potential use as a diagnostic tool in patients suspected to suffer from CII. The SBF can be measured using a continuous infusion of a tracer and catheterisation of a hepatic vein and an artery. By measuring the SBF before and after a standard meal it is possible to assess the ability or inability to enhance the SBF and thereby diagnosing CII. In Study I, measurement of SBF was tested against angiography in a group of patients suspected to suffer from CII due to pain and weight loss. A very good agreement between the postprandial increase in SBF and angiography was found. The method was validated against a well-established method independent of the hepatic extraction of tracer using pAH in a porcine model (study II

  3. Modeling and Grid impedance Variation Analysis of Parallel Connected Grid Connected Inverter based on Impedance Based Harmonic Analysis

    DEFF Research Database (Denmark)

    Kwon, JunBum; Wang, Xiongfei; Bak, Claus Leth

    2014-01-01

    This paper addresses the harmonic compensation error problem existing with parallel connected inverter in the same grid interface conditions by means of impedance-based analysis and modeling. Unlike the single grid connected inverter, it is found that multiple parallel connected inverters and grid...... impedance can make influence to each other if they each have a harmonic compensation function. The analysis method proposed in this paper is based on the relationship between the overall output impedance and input impedance of parallel connected inverter, where controller gain design method, which can...

  4. Megacystis microcolon intestinal hypoperistalsis syndrome

    Science.gov (United States)

    Hiradfar, Mehran; Shojaeian, Reza; Dehghanian, Paria; Hajian, Sara

    2013-01-01

    Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is a multisystemic disorder in which impaired intestinal motor activity causes recurrent symptoms of intestinal obstruction in the absence of mechanical occlusion, associated with bladder distention without distal obstruction of the urinary tract. MMIHS and prune belly syndrome may overlap in most of the clinical features and discrimination of these two entities is important because the prognosis, management and consulting with parents are completely different. MMIHS outcome is very poor and in this article we present two neonates with MMIHS that both died in a few days. PMID:23729700

  5. INFANTS’ INTESTINAL COLICS. MODERN DATA

    Directory of Open Access Journals (Sweden)

    N.I. Ursova

    2011-01-01

    Full Text Available The article analyzes modern data on infants’ intestinal colics. Peculiarities of nutrition, intestinal microbiocenose in healthy infants, methods of colcs’ correction are discussed. Author describes the principles of probiotics choice based on their clinical effectiveness in infants. Milk formula «Nan Comfort» can be useful in prophylaxis and treatment of functional disorders of gastrointestinal tract in children.Key words: infants, gastrointestinal tract, anatomy, physiology, intestinal colics, nutrition, probiotics.(Voprosy sovremennoi pediatrii — Current Pediatrics. 2011; 10 (2: 125–131

  6. Determination of beam coupling impedance in the frequency domain

    Energy Technology Data Exchange (ETDEWEB)

    Niedermayer, Uwe

    2016-07-01

    The concept of beam coupling impedance describes the electromagnetic interaction of uniformly moving charged particles with their surrounding structures in the Frequency Domain (FD). In synchrotron accelerators, beam coupling impedances can lead to beam induced component heating and coherent beam instabilities. Thus, in order to ensure the stable operation of a synchrotron, its impedances have to be quantified and their effects have to be controlled. Nowadays, beam coupling impedances are mostly obtained by Fourier transform of wake potentials, which are the results of Time Domain (TD) simulations. However, at low frequencies, low beam velocity, or for dispersive materials, TD simulations become unhandy. In this area, analytical calculations of beam coupling impedance in the FD, combined with geometry approximations, are still widely used. This thesis describes the development of two electromagnetic field solvers to obtain the beam coupling impedance directly in the FD, where the beam velocity is only a parameter and dispersive materials can be included easily. One solver is based on the Finite Integration Technique (FIT) on a staircase mesh. It is implemented both in 2D and 3D. However, the staircase mesh is inefficient on curved structures, which is particularly problematic for the modeling of a dipole source, that is required for the computation of the transverse beam coupling impedance. This issue is overcome by the second solver developed in this thesis, which is based on the Finite Element Method (FEM) on an unstructured triangular mesh. It is implemented in 2D and includes an optional Surface Impedance Boundary Condition (SIBC). Thus, it is well suited for the computation of longitudinal and transverse impedances of long beam pipe structures of arbitrary cross-section. Besides arbitrary frequency and beam velocity, also dispersive materials can be chosen, which is crucial for the computation of the impedance of ferrite kicker magnets. Numerical impedance

  7. Electrical impedance spectroscopy for measuring the impedance response of carbon-fiber-reinforced polymer composite laminates

    KAUST Repository

    Almuhammadi, Khaled

    2017-02-16

    Techniques that monitor the change in the electrical properties of materials are promising for both non-destructive testing and structural health monitoring of carbon-fiber-reinforced polymers (CFRPs). However, achieving reliable monitoring using these techniques requires an in-depth understanding of the impedance response of these materials when subjected to an alternating electrical excitation, information that is only partially available in the literature. In this work, we investigate the electrical impedance spectroscopy response at various frequencies of laminates chosen to be representative of classical layups employed in composite structures. We clarify the relationship between the frequency of the electrical current, the conductivity of the surface ply and the probing depth for different CFRP configurations for more efficient electrical signal-based inspections. We also investigate the effect of the amplitude of the input signal.

  8. Sources and effects of electrode impedance during deep brain stimulation.

    Science.gov (United States)

    Butson, Christopher R; Maks, Christopher B; McIntyre, Cameron C

    2006-02-01

    Clinical impedance measurements for deep brain stimulation (DBS) electrodes in human patients are normally in the range 500-1500 Omega. DBS devices utilize voltage-controlled stimulation; therefore, the current delivered to the tissue is inversely proportional to the impedance. The goals of this study were to evaluate the effects of various electrical properties of the tissue medium and electrode-tissue interface on the impedance and to determine the impact of clinically relevant impedance variability on the volume of tissue activated (VTA) during DBS. Axisymmetric finite-element models (FEM) of the DBS system were constructed with explicit representation of encapsulation layers around the electrode and implanted pulse generator. Impedance was calculated by dividing the stimulation voltage by the integrated current density along the active electrode contact. The models utilized a Fourier FEM solver that accounted for the capacitive components of the electrode-tissue interface during voltage-controlled stimulation. The resulting time- and space-dependent voltage waveforms generated in the tissue medium were superimposed onto cable model axons to calculate the VTA. The primary determinants of electrode impedance were the thickness and conductivity of the encapsulation layer around the electrode contact and the conductivity of the bulk tissue medium. The difference in the VTA between our low (790 Omega) and high (1244 Omega) impedance models with typical DBS settings (-3 V, 90 mus, 130 Hz pulse train) was 121 mm3, representing a 52% volume reduction. Electrode impedance has a substantial effect on the VTA and accurate representation of electrode impedance should be an explicit component of computational models of voltage-controlled DBS. Impedance is often used to identify broken leads (for values > 2000 Omega) or short circuits in the hardware (for values impedance values also represent an important parameter in defining the spread of stimulation during DBS.

  9. Development of impedance matching technologies for ICRF antenna arrays

    Energy Technology Data Exchange (ETDEWEB)

    Pinsker, R.I.

    1998-03-01

    All high power ICRF heating systems include devices for matching the input impedance of the antenna array to the generator output impedance. For most types of antennas used, the input impedance is strongly time-dependent on timescales as rapid as 10-4 s, while the rf generators used are capable of producing full power only into a stationary load impedance. Hence, the dynamic response of the matching method is of great practical importance. In this paper, world-wide developments in this field over the past decade are reviewed. These techniques may be divided into several classes. The edge plasma parameters that determine the antenna array`s input impedance may be controlled to maintain a fixed load impedance. The frequency of the rf source can be feedback controlled to compensate for changes in the edge plasma conditions, or fast variable tuning elements in the transmission line between the generator output and the antenna input connections can provide the necessary time-varying impedance transformation. In lossy passive schemes, reflected power due to the time-varying impedance of the antenna array is diverted to a dummy load. Each of these techniques can be applied to a pre-existing antenna system. If a new antenna is to be designed, recent advances allow the antenna array to have the intrinsic property of presenting a constant load to the feeding transmission lines despite the varying load seen by each antenna in the array.

  10. Modified impedance source inverter for power conditioning system

    Indian Academy of Sciences (India)

    ... generalized discussion and design of impedance network elements are presented. Comparison with the classical impedance source inverter is presented. Using simulation, analytical results are presented that ensure stability. The proposed voltage type inverter has reduced inrush current at startup, less capacitor voltage ...

  11. Electrochemical impedance measurement of a carbon nanotube probe electrode

    International Nuclear Information System (INIS)

    Inaba, Akira; Takei, Yusuke; Kan, Tetsuo; Shimoyama, Isao; Matsumoto, Kiyoshi

    2012-01-01

    We measured and analyzed the electrochemical impedance of carbon nanotube (CNT) probe electrodes fabricated through the physical separation of insulated CNT bridges. The fabricated CNT electrodes were free-standing CNTs that were completely covered with an insulator, except for their tips. Typical dimensions of the nanoelectrodes were 1–10 nm in CNT diameter, 80–300 nm in insulator diameter, 0.5–4 μm in exposed CNT length and 1–10 μm in probe length. The electrochemical impedance at frequencies ranging from 40 Hz to 1 MHz was measured in physiological saline. The measured impedance of the CNT electrode was constant at 32 MΩ at frequencies below 1 kHz and was inversely proportional to frequency at frequencies above 10 kHz. By means of comparison with the parasitic capacitive impedance of the insulator membrane, we confirmed that the electrode was sufficiently insulated such that the measured constant impedance was given by the exposed CNT tip. Consequently, we can use the CNT electrode for highly localized electrochemical impedance measurements below 1 kHz. Considering an equivalent circuit and the nanoscopic dimensions of the CNT electrode, we demonstrated that the constant impedance was governed by diffusion impedance, whereas the solution resistance, charge-transfer resistance and double-layer capacitance were negligible. (paper)

  12. Synthesis of adaptive impedance control for bipedal robot mechanisms

    OpenAIRE

    Petrović Milena; Rodić Aleksandar

    2008-01-01

    The paper describes the impedance algorithm in locomotion of humanoid robot with proposed parameter modulation depending on the gate phase. The analysis shows influence of walking speed and foot elevation on regulator's parameters. Chosen criterion cares for footpath tracking and needed energy for that way of walking. The experiments give recommendation for impedance regulator tuning.

  13. Impedance Modeling of Solid Oxide Fuel Cell Cathodes

    DEFF Research Database (Denmark)

    Mortensen, Jakob Egeberg; Søgaard, Martin; Jacobsen, Torben

    2010-01-01

    A 1-dimensional impedance model for a solid oxide fuel cell cathode is formulated and applied to a cathode consisting of 50/50 wt% strontium doped lanthanum cobaltite and gadolinia doped ceria. A total of 42 impedance spectra were recorded in the temperature range: 555-852°C and in the oxygen...

  14. Impedance-Source Networks for Electric Power Conversion Part II

    DEFF Research Database (Denmark)

    Siwakoti, Yam P.; Peng, Fang Zheng; Blaabjerg, Frede

    2015-01-01

    Impedance-source networks cover the entire spectrum of electric power conversion applications (dc-dc, dc-ac, ac-dc, ac-ac) controlled and modulated by different modulation strategies to generate the desired dc or ac voltage and current at the output. A comprehensive review of various impedance...... topology at a certain power level, switching frequency and demanded dynamic response....

  15. Impedance study for the PEP-II B-factory

    International Nuclear Information System (INIS)

    Heifets, S.; Daly, C.E.; Ko, K.

    1995-06-01

    The paper summarizes results of the impedance studies of the components of the B-factory. The prime goal of this activity was to support the design of the vacuum chamber and, at the same time, to get a reasonable model of the machine impedance, which can be used later for detail studies of collective effects

  16. Disorders of the Small Intestine

    Science.gov (United States)

    ... that move down the intestine in a peristaltic fashion (Phase III). Phase III represents a continuation of ... Activities, Legislative & Regulatory Research Leadership Contact us News Industry Treatment News Medical News Legislative & Regulatory News Press ...

  17. Defence Mechanisms during Intestinal Infection

    Directory of Open Access Journals (Sweden)

    André Buret

    1991-01-01

    Full Text Available This review examines and compares host defence mechanisms during intestinal infection with three types of organisms: a virus, a bacterium and a nematode parasite (ie, transmissible gastroenteritis virus [TGEV], Helicobacter jejuni and Trichinella spiralis. Diarrhea is commonly associated with all of these infections. It appears that T spiralis initiates the most elaborate defence system of the three organisms, involving full range humoral and cellular immunity, as well as mucus hypersecretion, epithelial alterations, altered gut motility and parasite impairment (morphological and physiological. In contrast, intestinal defence against H jejuni and TGEV involves fewer components. The latter seems to initiate the most rudimentary host response. Despite such differences, these mechanisms exhibit many similarities, thus further illustrating the relatively limited repertoire of defence systems that the intestine can mount. The mediators translating the insult of any intestinal pathogen into a common response deserve further investigation.

  18. INTESTINAL INTUSSUSCEPTION DUE TO CONCURRENT ...

    African Journals Online (AJOL)

    Administrator

    Hymenolepis nana and Dentostomella ... worms (H. nana and D. translucida) were observed in the lumen of the intestine with severe cellular infiltration .... helminthosis and Balantidosis in Red monkey (Erythrocebus patas) in Ibadan Nigeria Nigerian ...

  19. Development on electromagnetic impedance function modeling and its estimation

    International Nuclear Information System (INIS)

    Sutarno, D.

    2015-01-01

    Today the Electromagnetic methods such as magnetotellurics (MT) and controlled sources audio MT (CSAMT) is used in a broad variety of applications. Its usefulness in poor seismic areas and its negligible environmental impact are integral parts of effective exploration at minimum cost. As exploration was forced into more difficult areas, the importance of MT and CSAMT, in conjunction with other techniques, has tended to grow continuously. However, there are obviously important and difficult problems remaining to be solved concerning our ability to collect process and interpret MT as well as CSAMT in complex 3D structural environments. This talk aim at reviewing and discussing the recent development on MT as well as CSAMT impedance functions modeling, and also some improvements on estimation procedures for the corresponding impedance functions. In MT impedance modeling, research efforts focus on developing numerical method for computing the impedance functions of three dimensionally (3-D) earth resistivity models. On that reason, 3-D finite elements numerical modeling for the impedances is developed based on edge element method. Whereas, in the CSAMT case, the efforts were focused to accomplish the non-plane wave problem in the corresponding impedance functions. Concerning estimation of MT and CSAMT impedance functions, researches were focused on improving quality of the estimates. On that objective, non-linear regression approach based on the robust M-estimators and the Hilbert transform operating on the causal transfer functions, were used to dealing with outliers (abnormal data) which are frequently superimposed on a normal ambient MT as well as CSAMT noise fields. As validated, the proposed MT impedance modeling method gives acceptable results for standard three dimensional resistivity models. Whilst, the full solution based modeling that accommodate the non-plane wave effect for CSAMT impedances is applied for all measurement zones, including near-, transition

  20. Development on electromagnetic impedance function modeling and its estimation

    Energy Technology Data Exchange (ETDEWEB)

    Sutarno, D., E-mail: Sutarno@fi.itb.ac.id [Earth Physics and Complex System Division Faculty of Mathematics and Natural Sciences Institut Teknologi Bandung (Indonesia)

    2015-09-30

    Today the Electromagnetic methods such as magnetotellurics (MT) and controlled sources audio MT (CSAMT) is used in a broad variety of applications. Its usefulness in poor seismic areas and its negligible environmental impact are integral parts of effective exploration at minimum cost. As exploration was forced into more difficult areas, the importance of MT and CSAMT, in conjunction with other techniques, has tended to grow continuously. However, there are obviously important and difficult problems remaining to be solved concerning our ability to collect process and interpret MT as well as CSAMT in complex 3D structural environments. This talk aim at reviewing and discussing the recent development on MT as well as CSAMT impedance functions modeling, and also some improvements on estimation procedures for the corresponding impedance functions. In MT impedance modeling, research efforts focus on developing numerical method for computing the impedance functions of three dimensionally (3-D) earth resistivity models. On that reason, 3-D finite elements numerical modeling for the impedances is developed based on edge element method. Whereas, in the CSAMT case, the efforts were focused to accomplish the non-plane wave problem in the corresponding impedance functions. Concerning estimation of MT and CSAMT impedance functions, researches were focused on improving quality of the estimates. On that objective, non-linear regression approach based on the robust M-estimators and the Hilbert transform operating on the causal transfer functions, were used to dealing with outliers (abnormal data) which are frequently superimposed on a normal ambient MT as well as CSAMT noise fields. As validated, the proposed MT impedance modeling method gives acceptable results for standard three dimensional resistivity models. Whilst, the full solution based modeling that accommodate the non-plane wave effect for CSAMT impedances is applied for all measurement zones, including near-, transition

  1. Development of galvanostatic Fourier transform electrochemical impedance spectroscopy.

    Science.gov (United States)

    Nam, Kwang-Mo; Shin, Dong-Hyup; Jung, Namchul; Joo, Moon G; Jeon, Sangmin; Park, Su-Moon; Chang, Byoung-Yong

    2013-02-19

    Here, we report development of the galvanostatic Fourier transform electrochemical impedance spectroscopy (FTEIS), which monitors impedance of electrochemical reactions activated by current steps. We first derive relevant relations for potential change upon application of a step current, obtain impedances theoretically from the relations by simulation, and verify them with experimental results. The validity of the galvanostatic FTEIS technique is demonstrated by measuring impedances of a semiconductive silicon wafer using the conventional frequency response analysis (FRA), the potentiostatic FTEIS, and the galvanostatic FTEIS methods, and the results are in excellent agreement with each other. This work is significant in that the galvanostatic FTEIS would allow one to record impedance changes during charge/discharge cycles of secondary batteries and fuel cells as well as electrochemically irreversible systems which may produce noise level chronoamperometric currents by potentiostatic techniques.

  2. Mechanical impedance of the human body in vertical direction.

    Science.gov (United States)

    Holmlund, P; Lundström, R; Lindberg, L

    2000-08-01

    The mechanical impedance of the human body in sitting posture and vertical direction was measured during different experimental conditions, such as vibration level (0.5-1.4 m/s2), frequency (2-100 Hz), body weight (57-92 kg), relaxed and erect upper body posture. The outcome shows that impedance increases with frequency up to a peak at about 5 Hz after which it decreases in a complex manner which includes two additional peaks. The frequency at which the first and second impedance peak occurs decreases with higher vibration level. Erect, compared with relaxed body posture resulted in higher impedance magnitudes and with peaks located at somewhat higher frequencies. Heavy persons show higher impedance magnitudes and peaks at lower frequencies.

  3. Advanced impedance modeling of solid oxide electrochemical cells

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Hjelm, Johan

    2014-01-01

    Impedance spectroscopy is a powerful technique for detailed study of the electrochemical and transport processes that take place in fuel cells and electrolysis cells, including solid oxide cells (SOCs). Meaningful analysis of impedance measurements is nontrivial, however, because a large number...... techniques to provide good guesses for the modeling parameters, like transforming the impedance data to the distribution of relaxation times (DRT), together with experimental parameter sensitivity studies, is the state-of-the-art approach to achieve good EC model fits. Here we present new impedance modeling......) constraining the parameter values during fitting to ranges of physically reasonable values. Using these methods, the number of fitting parameters for four impedance spectra measured with isolated changes to the fuel and oxidant gas compositions, has been reduced from 80 to 21-34 depending on the model...

  4. Modeling the Impedance of Nanostructured PV in Simulink/matlab

    Science.gov (United States)

    Houshmand, Mohammad; Zandi, Mohammad. H.; Gorji, Nima E.

    2013-08-01

    Impedance measurement is a common method to study the electrical properties of thin film photovoltaics. For the first time, we use the MATLAB/Simulink environment to extract the complex impedance of the nanostructured heterojunction solar cells. The impedance magnitude, phase and Nyquist plot of the PV are simulated in LTI Viewer and Impedance versus Frequency analysis tools of SimPower GUI block of Simulink. We examined a variety of the equivalent circuits consisting of capacitance, series and shunt resistances representing the solar cell structure. The model uses the parameters with values reported in the literature at room temperature and zero bias. The effect of the additional capacitance and resistances in the equivalent circuits on the impedance components of the cells is considered by Simulink environment.

  5. Compensation for longitudinal space charge forces as inductive wall impedances

    International Nuclear Information System (INIS)

    Rees, G.H.

    1979-01-01

    In particle accelerators and storage rings the longitudinal coupling impedance between the beam and its environment arises from the longitudinal space charge forces and the vacuum chamber component impedance. A scheme is considered for compensating the total longitudinal coupling impedance within a restricted frequency range. For the low-β case, when the net longitudinal impedance is a negative inductance, compensation is achieved by means of adding either passive inductive wall elements or actively excited inductive elements. In the latter case, the excitation is by current pulses which exactly simulate amplified beam current pulses, in shape and sign. For the high-γ case, when the net longitudinal impedance is a positive inductance, an active inductance wall element is again introduced but the exciting signal is reversed in sign from the previous case

  6. Tuned driving of piezoelectric resonators: impedance matching

    Directory of Open Access Journals (Sweden)

    Pons, J. L.

    2006-06-01

    Full Text Available For optimal operation of piezoelectric resonators, the electrical impedance of electronic drivers and the resonator itself must be matched. Lack of matching results in a non smooth transmission of electrical power between the drive and the load which, in turn, leads to heating and poor efficiency. The rest of properties of the driving voltage (frequency, amplitude and phase are also affected by this mismatch. This paper presents the optimal design of power drivers for piezoelectric resonators. This approach is based on a first stage of electro-mechanical experimental characterization. This first step sets the basis for an impedance matching process. The approach has been experimentally validated on a well known piezoelectric resonator: the ultrasonic motor.

    La operación óptima de un resonador piezoeléctrico requiere de la adaptación de impedancia eléctrica entre el circuito de excitación y el propio resonador. La falta de adaptación se traduce en una pobre transmisión de potencia desde el excitador hasta el resonador, lo que a su vez se traduce en calentamiento y pérdida de eficienca en la operación. Las características morfológicas de la tensión de excitación (amplitud, frecuencia y fase también quedan afectadas por esta falta de adaptación. Este artículo analiza el diseño óptimo de la etapa de potencia de un circuito eléctrico de excitación para resonadores piezoeléctricos. Se trata la caracterización electromecánica del resonador y, en base a ésta, la adaptación de impedancias entre circuito y resonador. La contrastación experimental se ha llevado a cabo con un resonador bien estudiado en la literatura: un motor ultrasónico.

  7. Parenteral Nutrition and Intestinal Failure.

    Science.gov (United States)

    Bielawska, Barbara; Allard, Johane P

    2017-05-06

    Severe short bowel syndrome (SBS) is a major cause of chronic (Type 3) intestinal failure (IF) where structural and functional changes contribute to malabsorption and risk of micronutrient deficiencies. Chronic IF may be reversible, depending on anatomy and intestinal adaptation, but most patients require long-term nutritional support, generally in the form of parenteral nutrition (PN). SBS management begins with dietary changes and pharmacologic therapies taking into account individual anatomy and physiology, but these are rarely sufficient to avoid PN. New hormonal therapies targeting intestinal adaptation hold promise. Surgical options for SBS including intestinal transplant are available, but have significant limitations. Home PN (HPN) is therefore the mainstay of treatment for severe SBS. HPN involves chronic administration of macronutrients, micronutrients, fluid, and electrolytes via central venous access in the patient's home. HPN requires careful clinical and biochemical monitoring. Main complications of HPN are related to venous access (infection, thrombosis) and metabolic complications including intestinal failure associated liver disease (IFALD). Although HPN significantly impacts quality of life, outcomes are generally good and survival is mostly determined by the underlying disease. As chronic intestinal failure is a rare disease, registries are a promising strategy for studying HPN patients to improve outcomes.

  8. Anatomic correlates of deep brain stimulation electrode impedance.

    Science.gov (United States)

    Satzer, David; Maurer, Eric W; Lanctin, David; Guan, Weihua; Abosch, Aviva

    2015-04-01

    The location of the optimal target for deep brain stimulation (DBS) of the subthalamic nucleus (STN) remains controversial. Electrode impedance affects tissue activation by DBS and has been found to vary by contact number, but no studies have examined association between impedance and anatomic location. To evaluate the relationship between electrode impedance and anatomic contact location, and to assess the clinical significance of impedance. We gathered retrospective impedance data from 101 electrodes in 73 patients with Parkinson's disease. We determined contact location using microelectrode recording (MER) and high-field 7T MRI, and assessed the relationship between impedance and contact location. For contact location as assessed via MER, impedance was significantly higher for contacts in STN, at baseline (111 Ω vs STN border, p=0.03; 169 Ω vs white matter, pimpedance was lowest in contacts situated at STN border (p=0.03). Impedance did not vary by contact location as assessed via imaging. Location determination was 75% consistent between MER and imaging. Impedance was inversely related to absolute symptom reduction during stimulation (-2.5 motor portion of the Unified Parkinson's Disease Rating Scale (mUPDRS) points per 1000 Ω, p=0.01). In the vicinity of DBS electrodes chronically implanted in STN, impedance is lower at the rostral STN border and in white matter, than in STN. This finding suggests that current reaches white matter fibres more readily than neuronal cell bodies in STN, which may help explain anatomic variation in stimulation efficacy. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  9. Haemorrhage and intestinal lymphoma

    Directory of Open Access Journals (Sweden)

    Attilia M. Pizzini

    2013-04-01

    Full Text Available Background: The prevalence of coeliac disease is around 1% in general population but this is often unrecognised. The classical presentation of adult coeliac disease is characterized by diarrhoea and malabsorption syndrome, but atypical presentations are probably more common and are characterized by iron deficiency anaemia, weight loss, fatigue, infertility, arthralgia, peripheral neuropathy and osteoporosis. Unusual are the coagulation disorders (prevalence 20% and these are due to vitamin K malabsorption (prolonged prothrombin time. Clinical case: A 64-year-old man was admitted to our Department for an extensive spontaneous haematoma of the right leg. He had a history of a small bowel resection for T-cell lymphoma, with a negative follow-up and he didn’t report any personal or familiar history of bleeding. Laboratory tests showed markedly prolonged prothrombin (PT and partial-thromboplastin time (PTT, corrected by mixing studies, and whereas platelet count and liver tests was normal. A single dose (10 mg of intravenous vitamin K normalized the PT. Several days before the patient had been exposed to a superwarfarin pesticide, but diagnostic tests for brodifacoum, bromadiolone or difenacoum were negative. Diagnosis of multiple vitamin K-dependent coagulationfactor deficiencies (II, VII, IX, X due to intestinal malabsorption was made and coeliac disease was detected. Therefore the previous lymphoma diagnosis might be closely related to coeliac disease. Conclusions: A gluten free diet improves quality of life and restores normal nutritional and biochemical status and protects against these complications.

  10. [Malaria and intestinal protozoa].

    Science.gov (United States)

    Rojo-Marcos, Gerardo; Cuadros-González, Juan

    2016-03-01

    Malaria is life threatening and requires urgent diagnosis and treatment. Incidence and mortality are being reduced in endemic areas. Clinical features are unspecific so in imported cases it is vital the history of staying in a malarious area. The first line treatments for Plasmodium falciparum are artemisinin combination therapies, chloroquine in most non-falciparum and intravenous artesunate if any severity criteria. Human infections with intestinal protozoa are distributed worldwide with a high global morbid-mortality. They cause diarrhea and sometimes invasive disease, although most are asymptomatic. In our environment populations at higher risk are children, including adopted abroad, immune-suppressed, travelers, immigrants, people in contact with animals or who engage in oral-anal sex. Diagnostic microscopic examination has low sensitivity improving with antigen detection or molecular methods. Antiparasitic resistances are emerging lately. Copyright © 2016 Elsevier España, S.L.U. y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  11. Adult intestinal failure

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, J., E-mail: Jdavidson@doctors.org.u [Salford Royal Hospital, Salford (United Kingdom); Plumb, A.; Burnett, H. [Salford Royal Hospital, Salford (United Kingdom)

    2010-05-15

    Intestinal failure (IF) is the inability of the alimentary tract to digest and absorb sufficient nutrition to maintain normal fluid balance, growth, and health. It commonly arises from disease affecting the mesenteric root. Although severe IF is usually managed in specialized units, it lies at the end of a spectrum with degrees of nutritional compromise being widely encountered, but commonly under-recognized. Furthermore, in the majority of cases, the initial enteric insult occurs in non-specialist IF centres. The aim of this article is to review the common causes of IF, general principles of its management, some commoner complications, and the role of radiology in the approach to a patient with severe IF. The radiologist has a crucial role in helping provide access for feeding solutions (both enteral and parenteral) and controlling sepsis (via drainage of collections) in an initial restorative phase of treatment, whilst simultaneously mapping bowel anatomy and quality, and searching for disease complications to assist the clinicians in planning a later, restorative phase of therapy.

  12. [Intestinal failure: from adaptation to transplantation].

    Science.gov (United States)

    Messing, B; Corcos, O; Amiot, A; Joly, F

    2009-01-01

    Optimised Home Parenteral Nutrition is still, after 35 years of progress, the of benign but chronic Intestinal Failure. A better recognition of chronic Intestinal Failure, in its multiple facets, is warranted for a better approach of associated treatment to Home Parenteral Nutrition, i.e., intestinal trophic factors (growth hormone, Glucagon Like Peptide-2), rehabilitative surgery (reestablishment of colonic continuity, reverse jejunal segment in severe short gut type II) and/or reconstructive surgery (intestinal transplantation for end stage intestinal failure patients). Boundaries of permanent, judged irreversible, intestinal failure will be certainly modified in the following years by combining the various and effective therapies which optimise management by ameliorating absorption of the remnant short gut. The work done on short bowel syndrome in the past 20 years should be done in the next years for chronic-intestinal - pseudo-obstruction patients presenting with intestinal failure on a large European scale because chronic-intestinal - pseudo-obstruction is a group of heterogeneous but rare intestinal diseases. Intestinal transplantation is now a mature therapy with formal indication especially in case of Home Parenteral Nutrition failure (mainly Home Parenteral Nutrition-associated severe liver disease) where combined Liver-intestine transplantation is indicated before end-stage liver failure occurs. For high-risk patients, "preemptive" indication for intestinal transplantation alone will be discussed before home parenteral nutrition complications occur. No doubt that, for improving overall outcome in intestinal failure patients, reference centres should have in expert hands the whole spectrum of medicosurgical therapies for intestinal failure.

  13. Electrochemical impedance spectroscopy of oxidized porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Mula, Guido, E-mail: guido.mula@unica.it [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Tiddia, Maria V. [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Ruffilli, Roberta [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Falqui, Andrea [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Palmas, Simonetta; Mascia, Michele [Dipartimento di Ingegneria Meccanica Chimica e dei Materiali, Università degli Studi di Cagliari, Piazza d' Armi, 09126 Cagliari (Italy)

    2014-04-01

    We present a study of the electrochemical oxidation process of porous silicon. We analyze the effect of the layer thickness (1.25–22 μm) and of the applied current density (1.1–11.1 mA/cm{sup 2}, values calculated with reference to the external samples surface) on the oxidation process by comparing the galvanostatic electrochemical impedance spectroscopy (EIS) measurements and the optical specular reflectivity of the samples. The results of EIS were interpreted using an equivalent circuit to separate the contribution of different sample parts. A different behavior of the electrochemical oxidation process has been found for thin and thick samples: whereas for thin samples the oxidation process is univocally related to current density and thickness, for thicker samples this is no more true. Measurements by Energy Dispersive Spectroscopy using a Scanning Electron Microscopy confirmed that the inhomogeneity of the electrochemical oxidation process is increased by higher thicknesses and higher currents. A possible explanation is proposed to justify the different behavior of thin and thick samples during the electrochemical process. - Highlights: • A multidisciplinary approach on porous Si electrochemical oxidation is proposed. • Electrochemical, optical, and structural characterizations are used. • Layer thickness and oxidation current effects are shown. • An explanation of the observed behavior is proposed.

  14. High Speed impedance tomography for cardiac imaging

    International Nuclear Information System (INIS)

    Tehrani, J.N.; Jin, C.; Schaik, Andre

    2010-01-01

    Full text: Electrical Impedance Tomography (EIT) calculates the internal conductivity distribution within a body using electrical contact measurements. Previous investigation has shown that optimizing electrode placement can give better information about the stroke volume and better separation between the ventricles and atria than with the electrodes attached in the transverse plane. In our investigation we are developing fast three dimensional imaging of the heart (two planes of 16 electrodes) including internal electrodes in esophagus. The reconstruction speed in EIT is one of the main limitations for real time imaging when using a detailed three dimensional finite element mesh. For that reason we investigated new iterative algorithms for solving large scale LJ regularization. In this research we compare these algorithms on noise reliability and speed for 2D cardiac models. The four methods were as follows: (I) an interior point method for solving Ll-regularized least squares problems (Ll-LS); (2) total variation using a Lagrangian multiplier (TV AL3); (3) a two step iterative shrinkage/thresholding method (TWIST) for solving the Lo-regularized least squares problem; (4) The Least Absolute Shrinkage and Selection Operator (LASSO). In our investigation, using 1600 elements, we found all four algorithms provided an improvement over the best conventional EIT reconstruction method, Total Variation, in three important areas: robustness to noise, increased computational speed of at least 40 x and a visually apparent improvement in spatial resolution. Out of the four algorithms we found TWIST was the fastest with at least a 1 00 x speed increase. (author)

  15. Three-dimensional electrical impedance tomography

    Science.gov (United States)

    Metherall, P.; Barber, D. C.; Smallwood, R. H.; Brown, B. H.

    1996-04-01

    THE electrical resistivity of mammalian tissues varies widely1-5 and is correlated with physiological function6-8. Electrical impedance tomography (EIT) can be used to probe such variations in vivo, and offers a non-invasive means of imaging the internal conductivity distribution of the human body9-11. But the computational complexity of EIT has severe practical limitations, and previous work has been restricted to considering image reconstruction as an essentially two-dimensional problem10,12. This simplification can limit significantly the imaging capabilities of EIT, as the electric currents used to determine the conductivity variations will not in general be confined to a two-dimensional plane13. A few studies have attempted three-dimensional EIT image reconstruction14,15, but have not yet succeeded in generating images of a quality suitable for clinical applications. Here we report the development of a three-dimensional EIT system with greatly improved imaging capabilities, which combines our 64-electrode data-collection apparatus16 with customized matrix inversion techniques. Our results demonstrate the practical potential of EIT for clinical applications, such as lung or brain imaging and diagnostic screening8.

  16. Journal and Wave Bearing Impedance Calculation Software

    Science.gov (United States)

    Hanford, Amanda; Campbell, Robert

    2012-01-01

    The wave bearing software suite is a MALTA application that computes bearing properties for user-specified wave bearing conditions, as well as plain journal bearings. Wave bearings are fluid film journal bearings with multi-lobed wave patterns around the circumference of the bearing surface. In this software suite, the dynamic coefficients are outputted in a way for easy implementation in a finite element model used in rotor dynamics analysis. The software has a graphical user interface (GUI) for inputting bearing geometry parameters, and uses MATLAB s structure interface for ease of interpreting data. This innovation was developed to provide the stiffness and damping components of wave bearing impedances. The computational method for computing bearing coefficients was originally designed for plain journal bearings and tilting pad bearings. Modifications to include a wave bearing profile consisted of changing the film thickness profile given by an equation, and writing an algorithm to locate the integration limits for each fluid region. Careful consideration was needed to implement the correct integration limits while computing the dynamic coefficients, depending on the form of the input/output variables specified in the algorithm.

  17. [Interaction between humans and intestinal bacteria as a determinant for intestinal health : intestinal microbiome and inflammatory bowel diseases].

    Science.gov (United States)

    Haller, Dirk; Hörmannsperger, G

    2015-02-01

    Recent scientific results underline the importance of the intestinal microbiome, the totality of all intestinal microbes and their genes, for the health of the host organism. The intestinal microbiome can therefore be considered as a kind of "external organ". It has been shown that the intestinal microbiota is a complex and dynamic ecosystem that influences host immunity and metabolism beyond the intestine. The composition and functionality of the intestinal microbiota is of major importance for the development and maintenance of intestinal functions. Inflammatory bowel diseases (IBD) are characterized by dysregulated interactions between the host and its microbiota.The present contribution summarizes current knowledge of the composition and development of the intestinal microbiome and gives an overview of the bidirectional interaction between host and microbiota. The contribution informs about insights regarding the role of the intestinal microbiota in IBD and finally discusses the protective potential of microbial therapies in the context of IBD.

  18. Sound reflection in an acoustic impedance tube terminated with a loudspeaker shunted by a negative impedance converter

    International Nuclear Information System (INIS)

    Černík, M; Mokrý, P

    2012-01-01

    A system for the absorption of sound at the termination of an acoustic tube using an electrodynamic loudspeaker connected to a shunt circuit is presented. A theoretical model of the electrodynamic loudspeaker in the acoustic tube is used for the calculation of the frequency dependence of the ideal shunt circuit impedance, which yields perfect sound absorption in broad frequency range. It is shown that both the real and imaginary parts of the shunt circuit impedance must be negative in the considered system. The required negative values of the shunt circuit impedance are achieved using a negative impedance converter. Frequency dependences of the reflection coefficient were measured in the acoustic impedance tube using the two-microphone transfer function method. Greatly reduced values of sound absorption coefficient were achieved in a narrow frequency range. The stability, applicability of the sound absorption system, and broadening its frequency range are discussed. (paper)

  19. Quiescence Exit of Tert+ Stem Cells by Wnt/β-Catenin Is Indispensable for Intestinal Regeneration

    Directory of Open Access Journals (Sweden)

    Han Na Suh

    2017-11-01

    Full Text Available Fine control of stem cell maintenance and activation is crucial for tissue homeostasis and regeneration. However, the mechanism of quiescence exit of Tert+ intestinal stem cells (ISCs remains unknown. Employing a Tert knockin (TertTCE/+ mouse model, we found that Tert+ cells are long-term label-retaining self-renewing cells, which are partially distinguished from the previously identified +4 ISCs. Tert+ cells become mitotic upon irradiation (IR injury. Conditional ablation of Tert+ cells impairs IR-induced intestinal regeneration but not intestinal homeostasis. Upon IR injury, Wnt signaling is specifically activated in Tert+ cells via the ROS-HIFs-transactivated Wnt2b signaling axis. Importantly, conditional knockout of β-catenin/Ctnnb1 in Tert+ cells undermines IR-induced quiescence exit of Tert+ cells, which subsequently impedes intestinal regeneration. Our results that Wnt-signaling-induced activation of Tert+ ISCs is indispensable for intestinal regeneration unveil the underlying mechanism for how Tert+ stem cells undergo quiescence exit upon tissue injury.

  20. Summary of Human Ankle Mechanical Impedance During Walking.

    Science.gov (United States)

    Lee, Hyunglae; Rouse, Elliott J; Krebs, Hermano Igo

    2016-01-01

    The human ankle joint plays a critical role during walking and understanding the biomechanical factors that govern ankle behavior and provides fundamental insight into normal and pathologically altered gait. Previous researchers have comprehensively studied ankle joint kinetics and kinematics during many biomechanical tasks, including locomotion; however, only recently have researchers been able to quantify how the mechanical impedance of the ankle varies during walking. The mechanical impedance describes the dynamic relationship between the joint position and the joint torque during perturbation, and is often represented in terms of stiffness, damping, and inertia. The purpose of this short communication is to unify the results of the first two studies measuring ankle mechanical impedance in the sagittal plane during walking, where each study investigated differing regions of the gait cycle. Rouse et al. measured ankle impedance from late loading response to terminal stance, where Lee et al. quantified ankle impedance from pre-swing to early loading response. While stiffness component of impedance increases significantly as the stance phase of walking progressed, the change in damping during the gait cycle is much less than the changes observed in stiffness. In addition, both stiffness and damping remained low during the swing phase of walking. Future work will focus on quantifying impedance during the "push off" region of stance phase, as well as measurement of these properties in the coronal plane.

  1. A Batteryless Sensor ASIC for Implantable Bio-Impedance Applications.

    Science.gov (United States)

    Rodriguez, Saul; Ollmar, Stig; Waqar, Muhammad; Rusu, Ana

    2016-06-01

    The measurement of the biological tissue's electrical impedance is an active research field that has attracted a lot of attention during the last decades. Bio-impedances are closely related to a large variety of physiological conditions; therefore, they are useful for diagnosis and monitoring in many medical applications. Measuring living tissues, however, is a challenging task that poses countless technical and practical problems, in particular if the tissues need to be measured under the skin. This paper presents a bio-impedance sensor ASIC targeting a battery-free, miniature size, implantable device, which performs accurate 4-point complex impedance extraction in the frequency range from 2 kHz to 2 MHz. The ASIC is fabricated in 150 nm CMOS, has a size of 1.22 mm × 1.22 mm and consumes 165 μA from a 1.8 V power supply. The ASIC is embedded in a prototype which communicates with, and is powered by an external reader device through inductive coupling. The prototype is validated by measuring the impedances of different combinations of discrete components, measuring the electrochemical impedance of physiological solution, and performing ex vivo measurements on animal organs. The proposed ASIC is able to extract complex impedances with around 1 Ω resolution; therefore enabling accurate wireless tissue measurements.

  2. Geometric Beam Coupling Impedance of LHC Secondary Collimators

    CERN Document Server

    Frasciello, O; Zobov, M; Grudiev, A; Mounet, N; Salvant, B

    2016-01-01

    The High Luminosity LHC project is aimed at increasing the LHC luminosity by an order of magnitude. One of the key ingredients to achieve the luminosity goal is the beam intensity increase. In order to keep under control beam instabilities and to avoid excessive power losses a careful design of new vacuum chamber components and an improvement of the present LHC impedance model are required. Collimators are the main impedance contributors. Measurements with beam have revealed that the betatron coherent tune shifts were by about a factor of 2 higher with respect to the theoretical predictions based on the current model. Up to now the resistive wall impedance has been considered as the major impedance contribution for collimators. By carefully simulating their geometric impedance we show that for the graphite collimators with half-gaps higher than 10 mm the geometric impedance exceeds the resistive wall one. In turn, for the tungsten collimators the geometric impedance dominates for all used gap values. Hence, i...

  3. A comparison study of electrodes for neonate electrical impedance tomography.

    Science.gov (United States)

    Rahal, Mohamad; Khor, Joo Moy; Demosthenous, Andreas; Tizzard, Andrew; Bayford, Richard

    2009-06-01

    Electrical impedance tomography (EIT) is an imaging technique that has the potential to be used for studying neonate lung function. The properties of the electrodes are very important in multi-frequency EIT (MFEIT) systems, particularly for neonates, as the skin cannot be abraded to reduce contact impedance. In this work, the impedance of various clinical electrodes as a function of frequency is investigated to identify the optimum electrode type for this application. Six different types of self-adhesive electrodes commonly used in general and neonatal cardiology have been investigated. These electrodes are Ag/AgCl electrodes from the Ambu Cardiology Blue sensors range (BR, NF and BRS), Kendall (KittyCat and ARBO) and Philips 13953D electrodes. In addition, a textile electrode without gel from Textronics was tested on two subjects to allow comparison with the hydrogel-based electrodes. Two- and four-electrode measurements were made to determine the electrode-interface and tissue impedances, respectively. The measurements were made on the back of the forearm of six healthy adult volunteers without skin preparation with 2.5 cm electrode spacing. Impedance measurements were carried out using a Solartron SI 1260 impedance/gain-phase analyser with a frequency range from 10 Hz to 1 MHz. For the electrode-interface impedance, the average magnitude decreased with frequency, with an average value of 5 kOmega at 10 kHz and 337 Omega at 1 MHz; for the tissue impedance, the respective values were 987 Omega and 29 Omega. Overall, the Ambu BRS, Kendall ARBO and Textronics textile electrodes gave the lowest electrode contact impedance at 1 MHz. Based on the results of the two-electrode measurements, simple RC models for the Ambu BRS and Kendall-ARBO and Textronics textile electrodes have been derived for MFEIT applications.

  4. Microfluidic device for cell capture and impedance measurement.

    Science.gov (United States)

    Jang, Ling-Sheng; Wang, Min-How

    2007-10-01

    This work presents a microfluidic device to capture physically single cells within microstructures inside a channel and to measure the impedance of a single HeLa cell (human cervical epithelioid carcinoma) using impedance spectroscopy. The device includes a glass substrate with electrodes and a PDMS channel with micro pillars. The commercial software CFD-ACE+ is used to study the flow of the microstructures in the channel. According to simulation results, the probability of cell capture by three micro pillars is about 10%. An equivalent circuit model of the device is established and fits closely to the experimental results. The circuit can be modeled electrically as cell impedance in parallel with dielectric capacitance and in series with a pair of electrode resistors. The system is operated at low frequency between 1 and 100 kHz. In this study, experiments show that the HeLa cell is successfully captured by the micro pillars and its impedance is measured by impedance spectroscopy. The magnitude of the HeLa cell impedance declines at all operation voltages with frequency because the HeLa cell is capacitive. Additionally, increasing the operation voltage reduces the magnitude of the HeLa cell because a strong electric field may promote the exchange of ions between the cytoplasm and the isotonic solution. Below an operating voltage of 0.9 V, the system impedance response is characteristic of a parallel circuit at under 30 kHz and of a series circuit at between 30 and 100 kHz. The phase of the HeLa cell impedance is characteristic of a series circuit when the operation voltage exceeds 0.8 V because the cell impedance becomes significant.

  5. A comparison study of electrodes for neonate electrical impedance tomography

    International Nuclear Information System (INIS)

    Rahal, Mohamad; Demosthenous, Andreas; Khor, Joo Moy; Tizzard, Andrew; Bayford, Richard

    2009-01-01

    Electrical impedance tomography (EIT) is an imaging technique that has the potential to be used for studying neonate lung function. The properties of the electrodes are very important in multi-frequency EIT (MFEIT) systems, particularly for neonates, as the skin cannot be abraded to reduce contact impedance. In this work, the impedance of various clinical electrodes as a function of frequency is investigated to identify the optimum electrode type for this application. Six different types of self-adhesive electrodes commonly used in general and neonatal cardiology have been investigated. These electrodes are Ag/AgCl electrodes from the Ambu® Cardiology Blue sensors range (BR, NF and BRS), Kendall (KittyCat(TM) and ARBO®) and Philips 13953D electrodes. In addition, a textile electrode without gel from Textronics was tested on two subjects to allow comparison with the hydrogel-based electrodes. Two- and four-electrode measurements were made to determine the electrode-interface and tissue impedances, respectively. The measurements were made on the back of the forearm of six healthy adult volunteers without skin preparation with 2.5 cm electrode spacing. Impedance measurements were carried out using a Solartron SI 1260 impedance/gain-phase analyser with a frequency range from 10 Hz to 1 MHz. For the electrode-interface impedance, the average magnitude decreased with frequency, with an average value of 5 kΩ at 10 kHz and 337 Ω at 1 MHz; for the tissue impedance, the respective values were 987 Ω and 29 Ω. Overall, the Ambu BRS, Kendall ARBO® and Textronics textile electrodes gave the lowest electrode contact impedance at 1 MHz. Based on the results of the two-electrode measurements, simple RC models for the Ambu BRS and Kendall-ARBO and Textronics textile electrodes have been derived for MFEIT applications

  6. Longitudinal impedance variability in patients with chronically implanted DBS devices.

    Science.gov (United States)

    Cheung, Tyler; Nuño, Miriam; Hoffman, Matilde; Katz, Maya; Kilbane, Camilla; Alterman, Ron; Tagliati, Michele

    2013-09-01

    Deep brain stimulation (DBS) is an effective therapy for advanced movement disorders, but its optimal use is still controversial. One factor that could play a role in the proper delivery of therapeutic stimulation by current DBS devices is the variability of the impedance at the interface between the electrode surface and surrounding tissue. To analyze variability and trends in the impedance of chronically-implanted DBS electrodes in subjects with movement disorders. We reviewed impedance values from medical records of DBS patients at an academic tertiary-care movement disorders center. The standard deviation of data recorded within individual subjects and single contacts were used as measures of longitudinal impedance variability. A generalized linear mixed model (GLMM) determined if a number of effects had significant influences on impedance. We analyzed 2863 impedance measurements from 94 subjects. Median variability, for subjects with follow-up from 6 months to 5 years (n = 77), was 194 Ω for individual subjects and 141 Ω for individual contacts, with a range spanning from 18 to over 600 Ω. The GLMM, incorporating all subjects (n = 94), identified time, electrical activity, implanted target, contact position on the electrode and side of implantation as significant predictors of impedance. Age and disease duration at surgery, gender or ethnicity were not significant predictors. Our analysis suggests that a significant amount of impedance variability can be expected in chronically implanted DBS electrodes and indicates a number of factors with possible predictive value. Further studies are needed to link impedance characteristics to clinical outcomes. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Single cell array impedance analysis in a microfluidic device

    Science.gov (United States)

    Altinagac, Emre; Taskin, Selen; Kizil, Huseyin

    2016-10-01

    Impedance analysis of single cells is presented in this paper. Following the separation of a target cell type by dielectrophoresis in our previous work, this paper focuses on capturing the cells as a single array and performing impedance analysis to point out the signature difference between each cell type. Lab-on-a-chip devices having a titanium interdigitated electrode layer on a glass substrate and a PDMS microchannel are fabricated to capture each cell in a single form and perform impedance analysis. HCT116 (homosapiens colon colorectal carcin) and HEK293 (human embryonic kidney) cells are used in our experiments.

  8. On the longitudinal coupling impedance of a toroidal beam tube

    International Nuclear Information System (INIS)

    Hahn, H.; Tepikian, S.

    1990-01-01

    In this paper, the longitudinal coupling impedance of a smooth toroidal beam tube is derived. By treating the torus as a slow-wave structure, the well-known method of describing the impedance in terms of cavity resonances can be used. A simple analytical expression for the coupling impedance of a toroidal beam tube with square cross section valid in the low-frequency limit is obtained. The results from the present study are compared with previously published solutions and qualitative differences are pointed out. 16 refs., 3 figs., 1 tab

  9. Acoustic impedances of audiometric earphones coupled to different loads

    DEFF Research Database (Denmark)

    Ciric, Dejan; Hammershøi, Dorte

    2005-01-01

    The acoustic impedance of an audiometric earphone is one of the factors that can affect sound transmission through the ear during tests of hearing sensitivity. Similar situation exists during calibration of the earphone where its impedance can affect sound transmission through a coupler......, audiometric earphones are coupled to different loads. Thus, they are placed on different terminations of the tube including metal plate, artificial rubber pinna and upper part of the standardized coupler. The results show that the impedances of earphones are different, but they also differ from radiation...

  10. MEASURED TRANSVERSE COUPLING IMPEDANCE OF RHIC INJECTION AND ABORT KICKERS

    International Nuclear Information System (INIS)

    HAHN, H.; DAVINO, D.

    2001-01-01

    Concerns regarding possible transverse instabilities in RHIC and the SNS pointed to the need for measurements of the transverse coupling impedance of ring components. The impedance of the RHIC injection and abort kicker was measured using the conventional method based on the S 21 forward transmission coefficient. A commercial 450 Ω twin-wire Lecher line were used and the data was interpreted via the log-formula. All measurements, were performed in test stands fully representing operational conditions including pulsed power supplies and connecting cables. The measured values for the transverse coupling impedance in kick direction and perpendicular to it are comparable in magnitude, but differ from Handbook predictions

  11. Impedance-Source Networks for Electric Power Conversion Part I

    DEFF Research Database (Denmark)

    Siwakoti, Yam P.; Peng, Fang Zheng; Blaabjerg, Frede

    2015-01-01

    is the first of its kind with the aim of providing a “one-stop” information source and a selection guide on impedance-source networks for power conversion for researchers, designers, and application engineers. A comprehensive review of various modeling, control, and modulation techniques for the impedance......Impedance networks cover the entire of electric power conversion from dc (converter, rectifier), ac (inverter), to phase and frequency conversion (ac-ac) in a wide range of applications. Various converter topologies have been reported in the literature to overcome the limitations and problems......-source converters/inverters will be presented in Part II....

  12. Electrochemical Characterization of a PEMEC Using Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Elsøe, Katrine; Grahl-Madsen, L.; Hjelm, Johan

    2017-01-01

    In this study, electrochemical impedance spectroscopy (EIS) is applied in combination with cyclic voltammetry (CV) and current density – cell voltage curves (iV-curves) to investigate the processes contributing to the total impedance of a polymer electrolyte membrane electrolysis cell (PEMEC). i......V-curves were linear above 0.35 A cm−2 implying ohmic processes to be performance limiting, however the impedance spectra showed three arcs indicating three electrochemical reactions at these conditions not to be purely ohmic, but also to have capacitive properties. A hypothesis that the composite Ir...

  13. Reliability of impedance cardiography in measuring central haemodynamics

    DEFF Research Database (Denmark)

    Mehlsen, J; Bonde, J; Stadeager, C

    1991-01-01

    The purpose of the study described here was to investigate the reliability of impedance cardiography (IC) in measuring cardiac output (CO) and central blood volume. Absolute values and changes in these variables obtained by impedance cardiography and by isotope- or thermodilution techniques were...... compared. The reproducibility of IC within the same day was compared with that of isotope dilution and the reproducibility in IC from day to day was derived. Finally, the effects of the readings of impedance tracings by different observers were quantified. The results are based on 270 measurements in 37...

  14. Intestinal circulation during inhalation anesthesia

    International Nuclear Information System (INIS)

    Tverskoy, M.; Gelman, S.; Fowler, K.C.; Bradley, E.L.

    1985-01-01

    This study was designed to evaluate the influence of inhalational agents on the intestinal circulation in an isolated loop preparation. Sixty dogs were studied, using three intestinal segments from each dog. Selected intestinal segments were pumped with aortic blood at a constant pressure of 100 mmHg. A mixture of 86 Rb and 9-microns spheres labeled with 141 Ce was injected into the arterial cannula supplying the intestinal loop, while mesenteric venous blood was collected for activity counting. A very strong and significant correlation was found between rubidium clearance and microsphere entrapment (r = 0.97, P less than 0.0001). Nitrous oxide anesthesia was accompanied by a higher vascular resistance (VR), lower flow (F), rubidium clearance (Cl-Rb), and microspheres entrapment (Cl-Sph) than pentobarbital anesthesia, indicating that the vascular bed in the intestinal segment was constricted and flow (total and nutritive) decreased. Halothane, enflurane, and isoflurane anesthesia were accompanied by a much lower arteriovenous oxygen content difference (AVDO 2 ) and oxygen uptake than pentobarbital or nitrous oxide. Compared with pentobarbital, enflurane anesthesia was not accompanied by marked differences in VR, F, Cl-Rb, and Cl-Sph; halothane at 2 MAC decreased VR and increased F and Cl-Rb while isoflurane increased VR and decreased F. alpha-Adrenoceptor blockade with phentolamine (1 mg . kg-1) abolished isoflurane-induced vasoconstriction, suggesting that the increase in VR was mediated via circulating catecholamines

  15. Modeling intestinal disorders using zebrafish.

    Science.gov (United States)

    Zhao, X; Pack, M

    2017-01-01

    Although the zebrafish was initially developed as a model system to study embryonic development, it has gained increasing attention as an advantageous system to investigate human diseases, including intestinal disorders. Zebrafish embryos develop rapidly, and their digestive system is fully functional and visible by 5days post fertilization. There is a large degree of homology between the intestine of zebrafish and higher vertebrate organisms in terms of its cellular composition and function as both a digestive and immune organ. Furthermore, molecular pathways regulating injury and immune responses are highly conserved. In this chapter, we provide an overview of studies addressing developmental and physiological processes relevant to human intestinal disease. These studies include those related to congenital disorders, host-microbiota interactions, inflammatory diseases, motility disorders, and intestinal cancer. We also highlight the utility of zebrafish to functionally validate candidate genes identified through mutational analyses and genome-wide association studies, and discuss methodologies to investigate the intestinal biology that are unique to zebrafish. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Isotopic identification of intestinal strangulation

    International Nuclear Information System (INIS)

    Anderson, M.C.; Selby, J.B.

    1982-01-01

    A small series of eleven dogs prepared with a strangulating segment of jejunum demonstrated that a radionuclide, 99 mTc-labelled albumin, concentrates in the lumen and bowel wall of the affected intestinal segment. Modern scanning equipment accurately localized the strangulating loop. This technique has the potential of identifying patients with intestinal obstruction, in whom strangulation is a factor, prior to the development of impaired arterial inflow and frank gangrene. These findings confirmed earlier obstructions that were reported when nuclear scanning instrumentation was less sophisticated. Identification of patients at risk for intestinal strangulation requires a high index of suspicion. Excruciating cramping abdominal pain out of proportion to physical findings, roentgenogram evidence, and laboratory studies should alert the physician to the possibility of intestinal ischemia and closed loop obstruction. Radionuclide scanning in such cases may be of assistance in defining or excluding the diagnosis of a strangulating mechanism. The test is simple, relatively economical, and represents a low risk procedure to patients. It would have no place when the classic physical and laboratory findings of intestinal infarction are present

  17. Isotopic identification of intestinal strangulation

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, M.C.; Selby, J.B.

    1982-12-01

    A small series of eleven dogs prepared with a strangulating segment of jejunum demonstrated that a radionuclide, /sup 99/mTc-labelled albumin, concentrates in the lumen and bowel wall of the affected intestinal segment. Modern scanning equipment accurately localized the strangulating loop. This technique has the potential of identifying patients with intestinal obstruction, in whom strangulation is a factor, prior to the development of impaired arterial inflow and frank gangrene. These findings confirmed earlier obstructions that were reported when nuclear scanning instrumentation was less sophisticated. Identification of patients at risk for intestinal strangulation requires a high index of suspicion. Excruciating cramping abdominal pain out of proportion to physical findings, roentgenogram evidence, and laboratory studies should alert the physician to the possibility of intestinal ischemia and closed loop obstruction. Radionuclide scanning in such cases may be of assistance in defining or excluding the diagnosis of a strangulating mechanism. The test is simple, relatively economical, and represents a low risk procedure to patients. It would have no place when the classic physical and laboratory findings of intestinal infarction are present.

  18. How the Inductive Voltage Adder (IVA) output impedance affects impedance dynamics of a Self-Magnetic Pinch (SMP) diode

    Science.gov (United States)

    Renk, Timothy; Simpson, Sean; Webb, Timothy; Mazarakis, Michael; Kiefer, Mark

    2016-10-01

    The SMP diode, fielded on the RITS-6 (3.5-8.5 MV) IVA accelerator at Sandia National Laboratories, produces a focused electron beam (transmission line (MITL) center conductors, of 40 and 80 ohms flow impedance. We have operated in-situ heating and discharge-cleaning hardware in the load region, in order to address the tendency of some shots to undergo premature impedance (Z) collapse, defined as a fall in impedance beyond that due to normal movement of electrode plasmas that reduces the effective A-K gap. The goal of heating/cleaning was to reduce the volume of evolving gases near the A-K gap. Despite clear evidence that the cleaning techniques removed the proton portion of beam current, we observed no consistent increase in diode impedance (ZDIODE). This forced an examination of the role that the IVA flow impedance has on ZDIODE. A preliminary conclusion is that ZDIODE should be at least 1.5 times the flow impedance before ZDIODE is a parameter independent of flow impedance. This has implications for SMP as a load for a IVA, since ZDIODE >100 ohms has not been consistently demonstrated. Data analysis is ongoing, and latest results will be reported. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  19. Active electrode IC for EEG and electrical impedance tomography with continuous monitoring of contact impedance.

    Science.gov (United States)

    Guermandi, Marco; Cardu, Roberto; Franchi Scarselli, Eleonora; Guerrieri, Roberto

    2015-02-01

    The IC presented integrates the front-end for EEG and Electrical Impedance Tomography (EIT) acquisition on the electrode, together with electrode-skin contact impedance monitoring and EIT current generation, so as to improve signal quality and integration of the two techniques for brain imaging applications. The electrode size is less than 2 cm(2) and only 4 wires connect the electrode to the back-end. The readout circuit is based on a Differential Difference Amplifier and performs single-ended amplification and frequency division multiplexing of the three signals that are sent to the back-end on a single wire which also provides power supply. Since the system's CMRR is a function of each electrode's gain accuracy, an analysis is performed on how this is influenced by mismatches in passive and active components. The circuit is fabricated in 0.35 μm CMOS process and occupies 4 mm(2), the readout circuit consumes 360 μW, the input referred noise for bipolar EEG signal acquisition is 0.56 μVRMS between 0.5 and 100 Hz and almost halves if only EEG signal is acquired.

  20. Childbearing impeded education more than education impeded childbearing among Norwegian women.

    Science.gov (United States)

    Cohen, Joel E; Kravdal, Øystein; Keilman, Nico

    2011-07-19

    In most societies, women at age 39 with higher levels of education have fewer children. To understand this association, we investigated the effects of childbearing on educational attainment and the effects of education on fertility in the 1964 birth cohort of Norwegian women. Using detailed annual data from ages 17 to 39, we estimated the probabilities of an additional birth, a change in educational level, and enrollment in the coming year, conditional on fertility history, educational level, and enrollment history at the beginning of each year. A simple model reproduced a declining gradient of children ever born with increasing educational level at age 39. When a counterfactual simulation assumed no effects of childbearing on educational progression or enrollment (without changing the estimated effects of education on childbearing), the simulated number of children ever born decreased very little with increasing completed educational level, contrary to data. However, when another counterfactual simulation assumed no effects of current educational level and enrollment on childbearing (without changing the estimated effects of childbearing on education), the simulated number of children ever born decreased with increasing completed educational level nearly as much as the decrease in the data. In summary, in these Norwegian data, childbearing impeded education much more than education impeded childbearing. These results suggest that women with advanced degrees have lower completed fertility on the average principally because women who have one or more children early are more likely to leave or not enter long educational tracks and never attain a high educational level.

  1. Neck electrical impedance for measurement of swallowing; Enge katsudo no keisoku no tame no keibu denki impedance

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Y. [Okayama University, Okayama (Japan)] Nakamura, T. [Okayama University, Okayama (Japan). School of Health Science; Utsunomiya, K.; Akashi, K. [Kawasaki Medical School, Kawasaki (Japan)] Jikuya, K. [Kawasaki College of Allied Health Professions, Kawasaki (Japan)

    1998-03-01

    Recently videofluorography has been used for evaluation of swallowing function in rehabilitation field. But it is not easy to evaluate swallowing disorder simply. And it has problems or exposure for daily use. We have proposed a measurement method of swallowing using bioelectrical impedance method (Impedance Pharyngography, IPG) which has advantages of easy handle and non-invasive measurement. Appropriate electrode positions have been determined. The waveform of IPG can be obtained with some extent reproducibility. The change of neck electrical impedance in pharyngeal phase is mainly caused by the changes of equivalent cross sectional area of near epiglottis. The possibilities of applications for clinical diagnosis have been shown. 7 refs., 10 figs.

  2. Something different - caching applied to calculation of impedance matrix elements

    CSIR Research Space (South Africa)

    Lysko, AA

    2012-09-01

    Full Text Available (N). The method requires only minor modifications of an existing code, and has been realized in Matlab. The tests confirmed validity of the method and showed doubling the speed of filling the impedance matrix in....

  3. Analytical model of impedance in elliptical beam pipes

    CERN Document Server

    Pesah, Arthur Chalom

    2017-01-01

    Beam instabilities are among the main limitations in building higher intensity accelerators. Having a good impedance model for every accelerators is necessary in order to build components that minimize the probability of instabilities caused by the interaction beam-environment and to understand what piece to change in case of intensity increasing. Most of accelerator components have their impedance simulated with finite elements method (using softwares like CST Studio), but simple components such as circular or flat pipes are modeled analytically, with a decreasing computation time and an increasing precision compared to their simulated model. Elliptical beam pipes, while being a simple component present in some accelerators, still misses a good analytical model working for the hole range of velocities and frequencies. In this report, we present a general framework to study the impedance of elliptical pipes analytically. We developed a model for both longitudinal and transverse impedance, first in the case of...

  4. Bioelectrical impedance analysis for bovine milk: Preliminary results

    Science.gov (United States)

    Bertemes-Filho, P.; Valicheski, R.; Pereira, R. M.; Paterno, A. S.

    2010-04-01

    This work reports the investigation and analysis of bovine milk quality by using biological impedance measurements using electrical impedance spectroscopy (EIS). The samples were distinguished by a first chemical analysis using Fourier transform midinfrared spectroscopy (FTIR) and flow citometry. A set of milk samples (100ml each) obtained from 17 different cows in lactation with and without mastitis were analyzed with the proposed technique using EIS. The samples were adulterated by adding distilled water and hydrogen peroxide in a controlled manner. FTIR spectroscopy and flow cytometry were performed, and impedance measurements were made in a frequency range from 500Hz up to 1MHz with an implemented EIS system. The system's phase shift was compensated by measuring saline solutions. It was possible to show that the results obtained with the Bioelectrical Impedance Analysis (BIA) technique may detect changes in the milk caused by mastitis and the presence of water and hydrogen peroxide in the bovine milk.

  5. Robust excitation power spectrum design for broadband impedance spectroscopy

    International Nuclear Information System (INIS)

    Sanchez, B; Rojas, C R

    2014-01-01

    This paper focuses on the robust design of broadband impedance spectroscopy (IS) experiments. This contribution extends the optimal IS experiment design presented in previous work (Sanchez et al 2012 Meas. Sci. Technol. 23 085702) in order to design a robust broadband excitation which gives relatively good estimation performance over a large number of possible impedance models. To this end, we assume as prior knowledge that the parameters of the impedance model lie in a compact set. Then, we pose the experiment design problem as a convex optimization program, which gives the excitation signal of bounded power that minimizes the worst value of a given scalar function of the Fisher information matrix, as the parameters range over the given compact set. Supported by numerical simulations, our results reveal the robust excitation for impedance experiments has a discrete power spectrum, e.g. (periodic) multisine signals. (paper)

  6. Interdigitated electrodes as impedance and capacitance biosensors: A review

    Science.gov (United States)

    Mazlan, N. S.; Ramli, M. M.; Abdullah, M. M. A. B.; Halin, D. S. C.; Isa, S. S. M.; Talip, L. F. A.; Danial, N. S.; Murad, S. A. Z.

    2017-09-01

    Interdigitated electrodes (IDEs) are made of two individually addressable interdigitated comb-like electrode structures. IDEs are one of the most favored transducers, widely utilized in technological applications especially in the field of biological and chemical sensors due to their inexpensive, ease of fabrication process and high sensitivity. In order to detect and analyze a biochemical molecule or analyte, the impedance and capacitance signal need to be obtained. This paper investigates the working principle and influencer of the impedance and capacitance biosensors. The impedance biosensor depends on the resistance and capacitance while the capacitance biosensor influenced by the dielectric permittivity. However, the geometry and structures of the interdigitated electrodes affect both impedance and capacitance biosensor. The details have been discussed in this paper.

  7. Optimization design of power efficiency of exponential impedance transformer

    International Nuclear Information System (INIS)

    Wang Meng; Zou Wenkang; Chen Lin; Guan Yongchao; Fu Jiabin; Xie Weiping

    2011-01-01

    The paper investigates the optimization design of power efficiency of exponential impedance transformer with analytic method and numerical method. In numerical calculation, a sine wave Jantage with hypothesis of rising edge equivalence is regarded as the forward-going Jantage at input of transformer, and its dominant angular frequency is determined by typical rise-time of actual Jantage waveforms. At the same time, dissipative loss in water dielectric is neglected. The numerical results of three typical modes of impedance transformation, viz. linear mode, saturation mode and steep mode,are compared. Pivotal factors which affect the power efficiency of exponential impedance transformer are discussed, and a certain extent quantitative range of intermediate variables and accordance coefficients are obtained. Finally, the paper discusses some important issues in actual design, such as insulation safety factor in structure design, effects of coupling capacitance on impedance calculation, and dissipative loss in water dielectric. (authors)

  8. Propagation of singularities for linearised hybrid data impedance tomography

    DEFF Research Database (Denmark)

    Bal, Guillaume; Hoffmann, Kristoffer; Knudsen, Kim

    2017-01-01

    For a general formulation of linearised hybrid inverse problems in impedance tomography, the qualitative properties of the solutions are analysed. Using an appropriate scalar pseudo-differential formulation, the problems are shown to permit propagating singularities under certain non...

  9. Low profile conformal antenna arrays on high impedance substrate

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan

    2016-01-01

    This book presents electromagnetic (EM) design and analysis of dipole antenna array over high impedance substrate (HIS). HIS is a preferred substrate for low-profile antenna design, owing to its unique boundary conditions. Such substrates permit radiating elements to be printed on them without any disturbance in the radiation characteristics. Moreover HIS provides improved impedance matching, enhanced bandwidth, and increased broadside directivity owing to total reflection from the reactive surface and high input impedance. This book considers different configurations of HIS for array design on planar and non-planar high-impedance surfaces. Results are presented for cylindrical dipole, printed dipole, and folded dipole over single- and double-layered square-patch-based HIS and dogbone-based HIS. The performance of antenna arrays is analyzed in terms of performance parameters such as return loss and radiation pattern. The design presented shows acceptable return loss and mainlobe gain of radiation pattern. Thi...

  10. Validation of Standing Wave Liner Impedance Measurement Method, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Hersh Acoustical Engineering, Inc. proposes to establish the feasibility and practicality of using the Standing Wave Method (SWM) to measure the impedance of...

  11. Retrieving complex surface impedances from statistical absorption coefficients

    DEFF Research Database (Denmark)

    Mondet, Boris Jean-Francois; Brunskog, Jonas; Jeong, Cheol-Ho

    2017-01-01

    coefficients, prior information about the absorber of interest can be used as constraints, which is shown to help determine the correct impedance from absorption coefficient. Further stability and sensitivity investigations indicate that the method presented constitutes an efficient solution to convert sound......In room acoustic simulations the surface materials are commonly represented with energy parameters, such as the absorption and scattering coefficients, which do not carry phase information. This paper presents a method to transform statistical absorption coefficients into complex surface impedances...... that the impedance found has a physical meaning and respects causality in the time domain. Known material models, such as Miki’s and Maa’s models, are taken as references to assess the validity of the suggested model. Due to the non-uniqueness of retrieving complex-valued impedances from real-valued absorption...

  12. A Forward Solution for RF Impedance Tomography in Wood

    Directory of Open Access Journals (Sweden)

    Ian WOODHEAD

    2008-04-01

    Full Text Available Both integral equation and differential equation methods enable modelling current and hence impedance of wood, to provide the forward solution for impedance tomography that in turn provides a measure of its internal moisture distribution. Previously, we have used a series impedance model and successfully demonstrated measurement of internal moisture distribution. Here we describe the adaptation of our integral equation method for this application. This has required an alternative calculation to model the impressed field from the segmented electrodes used in the measurements to date, and we demonstrate distortion of the anomalous field due to the presence of a wood dielectric, and the field magnitude. Further work will be required to translate the resulting field distribution from our model, to complex current and hence impedance readings, to allow completion of tomographic reconstruction using this approach.

  13. A UVC Device for Intra-luminal Disinfection of Catheters: In Vitro Tests on Soft Polymer Tubes Contaminated with Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Candida albicans

    DEFF Research Database (Denmark)

    Bak, Jimmy; Begovic, Tanja; Bjarnsholt, Thomas

    2011-01-01

    light is possible. In this paper we present dose-response results using a newly developed UVC disinfection device, which can be connected to a Luer catheter hub. The device was tested on soft polymer tubes contaminated with a pallet of microorganisms, including Candida albicans, Staphylococcus aureus...... breach. Our results show UVC killing in a dose and time dependent manner, with no viable counts after 2 min of radiation for bacteria. Killing of C. albicans was obtained at >20 min in an UVC absorbing suspension. We believe our results to be transferable directly to the clinic, and we are currently...

  14. Simulation of the LHC injection kicker impedance test bench

    CERN Document Server

    Tsutsui, H

    2003-01-01

    The coupling impedance measurements of the LHC injection kicker test bench are simulated by HFSS code. The simulation gives qualitatively good agreement with the measurement. In order to damp the resonances, some ferrite rings are tested in the simulation. Longitudinal resonances are damped by a ferrite ring of large tan$\\delta_{\\mu}$. The effect of the ferrite ring is small for damping the transverse impedance resonance around 30 MHz.

  15. The bioelectrical impedance vector migration in healthy infants

    OpenAIRE

    L'Abee, Carianne; Poorts-Borger, Petra H.; Gorter, Erna H. G. M.; Piccoli, Antonio; Stolk, Ronald P.; Sauer, Pieter J. J.

    2010-01-01

    Background & aims: Detecting young children with high amount of body fat is important to intervene in the development of obesity. The aim of this study is to gain inside in the bioelectrical impedance vector analysis in healthy infants. Methods: Repeated measurements of whole body reactance and resistance were assessed, using a 50 kHz frequency bioelectrical impedance analysis, in 51 boys and 62 girls during infancy. Bivariate vector analysis, which can be used to determine tissue hydration a...

  16. Application of Electrochemical Impedance Spectroscopy for Fuel Cell Characterization

    OpenAIRE

    Wagner, N.

    2010-01-01

    Theory of impedance spectra measured at fuel cells with electrodes changing their state with time e.g. anode surface changing during CO poisoning of PEFC anodes and water flooding of the cathode during “dead end” operation mode of the PEFC are discussed in the presentation. Also first experimental results of locally resolved EIS measured simultaneously on 5 cells of a SOFC stack will be presented and discussed. For the evaluation of the measured impedance spectra a porous electrode model w...

  17. Development of Longitudinal Coupling Impedance Measurement Platform for BEPCII

    CERN Document Server

    Huang, Gang; Wang Jiu Qing; Zheng, Shuxin; Zhou, Demin

    2005-01-01

    A coaxial line impedance measurement platform is developed for BEPCII. A pair of gradual change impedance matching section is designed and fabricated by numerical control milling machine. The special designed RF connector is applied to strengthen the inner conductor. The algorithm of TRL calibration is applied in the system to avoid the usage of a reference pipe for each device under test. The measurement is accomplished by a VNA under the control of the software written in LabView.

  18. Intramyocardial impedance measurements for diagnosis of acute cardiac allograft rejection.

    Science.gov (United States)

    Pfitzmann, R; Müller, J; Grauhan, O; Hetzer, R

    2000-08-01

    Measurements of intramyocardial impedance at high frequencies can indicate alterations in cell membranes and intracellular spaces during acute cardiac allograft rejection. Fifteen beagle dogs underwent heterotopic heart transplantation and were immunosuppressed with cyclosporine and methyl prednisolone (MP). Impedance was determined twice daily by means of four screw-in electrodes in the right and left ventricle. Transmyocardial biopsies and the intramyocardial electrogram (IMEG) were performed as reference methods. A total of 23 rejection episodes were induced. When acute rejection was recognized histologically and through IMEG readings, the animals were treated with a bolus of 125 mg of methyl prednisolone over 5 consecutive days. Treatment of rejection was controlled by biopsy and IMEG. All hearts showed a uniform decrease in impedance of about 28.3%+/-5.5% immediately after transplantation, which subsequently reached a stable plateau after 7 to 8 days. Impedance values then remained unchanged as long as rejection was absent. Biopsy findings of grades 1A to 1B (ISHLT) were accompanied by a statistically significant increase in impedance of 12.2%+/-2.5%; of grades 2 to 3A of 19.2%+/-3.2% and of grades 3B to 4 of 27.0%+/-2.9%. Sensitivity was 96%, specificity 91%. Successful treatment of rejection led to a decrease of impedance to the initial levels. The amount of increase in impedance of high frequencies is a method to stratify acute cardiac allograft rejection into grades like histologically grading. The effectiveness of rejection treatment can also be monitored through impedance measurement. The method is also applicable for telemetric rejection monitoring by means of an implantable device.

  19. Analysis and design of complex impedance transforming marchand baluns

    OpenAIRE

    Michaelsen, Rasmus Schandorph; Johansen, Tom Keinicke; Tamborg, Kjeld M.

    2014-01-01

    A new type of Marchand balun is presented in this paper, which has the property of complex impedance transformation. To allow the Marchand balun to transform between arbitrary complex impedances, three reactances should be added to the circuit. A detailed analysis of the circuit gives the governing equations. To verify the theory, a design and electromagnetic simulation of a lumped element Marchand balun is made in a SiGe BiCMOS technology. The lumped element impementation is favorable becaus...

  20. MD 349: Impedance Localization with AC-dipole

    CERN Document Server

    Biancacci, Nicolo; Metral, Elias; Salvant, Benoit; Papotti, Giulia; Persson, Tobias Hakan Bjorn; Tomas Garcia, Rogelio; CERN. Geneva. ATS Department

    2016-01-01

    The purpose of this MD is to measure the distribution of the transverse impedance of the LHC by observing the phase advance variation with intensity between the machine BPMs. Four injected bunches with different intensities are excited with an AC dipole and the turn by turn data is acquired from the BPM system. Through post-processing analysis the phase variation along the machine is depicted and, from this information, first conclusions of the impedance distribution can be drawn.

  1. Galanin and vasoactive intestinal polypeptide

    DEFF Research Database (Denmark)

    Harling, H; Messell, T; Poulsen, Steen Seier

    1991-01-01

    By immunohistochemistry and double staining technique, almost complete coexistence of galanin-like immunoreactivity (GAL-LI) and vasoactive intestinal polypeptide-like immunoreactivity (VIP-LI) was demonstrated in submucosal ganglionic cells and mucosal nerve fibers of the porcine ileum. The rele......By immunohistochemistry and double staining technique, almost complete coexistence of galanin-like immunoreactivity (GAL-LI) and vasoactive intestinal polypeptide-like immunoreactivity (VIP-LI) was demonstrated in submucosal ganglionic cells and mucosal nerve fibers of the porcine ileum...

  2. Intestinal Microbiota Influences Non-intestinal Related Autoimmune Diseases

    Directory of Open Access Journals (Sweden)

    Maria C. Opazo

    2018-03-01

    Full Text Available The human body is colonized by millions of microorganisms named microbiota that interact with our tissues in a cooperative and non-pathogenic manner. These microorganisms are present in the skin, gut, nasal, oral cavities, and genital tract. In fact, it has been described that the microbiota contributes to balancing the immune system to maintain host homeostasis. The gut is a vital organ where microbiota can influence and determine the function of cells of the immune system and contributes to preserve the wellbeing of the individual. Several articles have emphasized the connection between intestinal autoimmune diseases, such as Crohn's disease with dysbiosis or an imbalance in the microbiota composition in the gut. However, little is known about the role of the microbiota in autoimmune pathologies affecting other tissues than the intestine. This article focuses on what is known about the role that gut microbiota can play in the pathogenesis of non-intestinal autoimmune diseases, such as Grave's diseases, multiple sclerosis, type-1 diabetes, systemic lupus erythematosus, psoriasis, schizophrenia, and autism spectrum disorders. Furthermore, we discuss as to how metabolites derived from bacteria could be used as potential therapies for non-intestinal autoimmune diseases.

  3. Gintonin absorption in intestinal model systems

    Directory of Open Access Journals (Sweden)

    Byung-Hwan Lee

    2018-01-01

    Conclusion: The present study shows that gintonin could be absorbed in the intestine through transcellular and paracellular diffusion, and active transport. In addition, the lipid component of gintonin might play a key role in its intestinal absorption.

  4. Microbiota, intestinal immunity, and mouse bustle

    OpenAIRE

    Kruglov, A.; Nedospasov, S.

    2014-01-01

    The composition of the intestinal microbiota is regulated by the immune system. This paper discusses the role of cytokines and innate immunity lymphoid cells in the intestinal immune regulation by means of IgA.

  5. Validation of an Acoustic Impedance Prediction Model for Skewed Resonators

    Science.gov (United States)

    Howerton, Brian M.; Parrott, Tony L.

    2009-01-01

    An impedance prediction model was validated experimentally to determine the composite impedance of a series of high-aspect ratio slot resonators incorporating channel skew and sharp bends. Such structures are useful for packaging acoustic liners into constrained spaces for turbofan noise control applications. A formulation of the Zwikker-Kosten Transmission Line (ZKTL) model, incorporating the Richards correction for rectangular channels, is used to calculate the composite normalized impedance of a series of six multi-slot resonator arrays with constant channel length. Experimentally, acoustic data was acquired in the NASA Langley Normal Incidence Tube over the frequency range of 500 to 3500 Hz at 120 and 140 dB OASPL. Normalized impedance was reduced using the Two-Microphone Method for the various combinations of channel skew and sharp 90o and 180o bends. Results show that the presence of skew and/or sharp bends does not significantly alter the impedance of a slot resonator as compared to a straight resonator of the same total channel length. ZKTL predicts the impedance of such resonators very well over the frequency range of interest. The model can be used to design arrays of slot resonators that can be packaged into complex geometries heretofore unsuitable for effective acoustic treatment.

  6. Entrance and Exit CSR Impedance for Non-Ultrarelativistic Beam

    Energy Technology Data Exchange (ETDEWEB)

    Li, Rui; Tsai, Cheng Ying [SLAC National Accelerator Lab., Menlo Park, CA (United States); Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2017-05-01

    For a high-brightness electron beam being transported through beamlines involving bending systems, the coherent synchrotron radiation (CSR) and longitudinal space charge (LSC) interaction could often cause microbunching instability. The semi-analytical Vlasov solver for microbunching gain* depends on the impedances for the relevant collective effects. The existing results for CSR impedances are usually obtained for the ultrarelativistic limit. To extend the microbunching analysis to cases of low energies, such as the case of an ERL merger, or to density modulations at extremely small wavelength, it is necessary to extend the impedance analysis to the non-ultrarelativistic regime. In this study, we present the impedance analysis for the transient CSR interaction in the non-ultrarelativistic regime, for transients including both entrance to and exit from a magnetic dipole. These impedance results will be compared to their ultra-relativistic counterparts**, and the corresponding wakefield obtained from the impedance for low-energy beams will be compared with the existing results of transient CSR wakefield for general beam energies***.

  7. Comparison of the longitudinal coupling impedance from different source terms

    International Nuclear Information System (INIS)

    Al-Khateeb, A.M.; Hasse, R.W.; Boine-Frankenheim, O.

    2008-01-01

    The longitudinal coupling impedance and the transmission coefficient resulting from a thin ring and from a uniform disk are obtained analytically for a resistive cylindrical beam-pipe of finite wall thickness. The impedances are derived and then compared with the well-known corresponding expression for perturbations on a uniform, coasting beam [A. Al-Khateeb, O. Boine-Frankenheim, R.W. Hasse, I. Hofmann, Phys. Rev. E 71 (2005) 026501]. The transmission coefficients from both sources are found to be exactly the same. Differences do appear in the expressions for the electromagnetic fields within the beam region, and therefore leading to different coupling impedances. By applying the results to parameters relevant for the SIS-18 synchrotron at GSI, it is found that the formula from the ring source underestimates the space-charge impedance at all beam energies and it shows a noticeable deviation from the disk formula for all frequencies. Although their mathematical expressions are different, resistive-wall impedances from the two sources are found to be numerically equal. The space-charge impedances become equal asymptotically only in the so-called ultra-relativistic limit

  8. Transverse impedance of a periodic array of cavities

    Directory of Open Access Journals (Sweden)

    A. V. Fedotov

    1999-06-01

    Full Text Available We examine the transverse impedance of a periodic array of cavities in a beam pipe at high frequency. The calculation is an extension of a previous one for the longitudinal impedance of a periodic array of azimuthally symmetric pillboxes, for which only TM modes were needed. In the present case, we must include TE modes as well. In addition, we extend the applicability of the previous calculation by including an extra term in the coupling kernel so that the results are valid for all values of the ratio of the cavity length to the period of the structure (all values of the ratio of iris thickness to structure period. In spite of the presence of TE modes, we find that the high frequency limit of the transverse impedance is simply (2/ka^{2} times the corresponding limit of the longitudinal impedance, just as it is for the resistive wall impedances, a relation which occurs frequently for azimuthally symmetric structures. Finally, we present numerical results as well as approximate expressions for the impedance per period, valid for all ratios of cavity length to structure period.

  9. Feasibility of bioelectrical impedance spectroscopy measurement before and after thoracentesis.

    Science.gov (United States)

    Zink, Matthias Daniel; Weyer, Sören; Pauly, Karolin; Napp, Andreas; Dreher, Michael; Leonhardt, Steffen; Marx, Nikolaus; Schauerte, Patrick; Mischke, Karl

    2015-01-01

    Bioelectrical impedance spectroscopy is applied to measure changes in tissue composition. The aim of this study was to evaluate its feasibility in measuring the fluid shift after thoracentesis in patients with pleural effusion. 45 participants (21 with pleural effusion and 24 healthy subjects) were included. Bioelectrical impedance was analyzed for "Transthoracic," "Foot to Foot," "Foot to Hand," and "Hand to Hand" vectors in low and high frequency domain before and after thoracentesis. Healthy subjects were measured at a single time point. The mean volume of removed pleural effusion was 1169 ± 513 mL. The "Foot to Foot," "Hand to Hand," and "Foot to Hand" vector indicated a trend for increased bioelectrical impedance after thoracentesis. Values for the low frequency domain in the "Transthoracic" vector increased significantly (P impedance change in the low frequency domain using the "Foot to Hand" vector (r = -0.7). Bioelectrical impedance changes in correlation with the thoracic fluid level. It was feasible to monitor significant fluid shifts and loss after thoracentesis in the "Transthoracic" vector by means of bioelectrical impedance spectroscopy. The trial is registered with Registration Numbers IRB EK206/11 and NCT01778270.

  10. Impedance characterization and modeling of electrodes for biomedical applications.

    Science.gov (United States)

    Franks, Wendy; Schenker, Iwan; Schmutz, Patrik; Hierlemann, Andreas

    2005-07-01

    A low electrode-electrolyte impedance interface is critical in the design of electrodes for biomedical applications. To design low-impedance interfaces a complete understanding of the physical processes contributing to the impedance is required. In this work a model describing these physical processes is validated and extended to quantify the effect of organic coatings and incubation time. Electrochemical impedance spectroscopy has been used to electrically characterize the interface for various electrode materials: platinum, platinum black, and titanium nitride; and varying electrode sizes: 1 cm2, and 900 microm2. An equivalent circuit model comprising an interface capacitance, shunted by a charge transfer resistance, in series with the solution resistance has been fitted to the experimental results. Theoretical equations have been used to calculate the interface capacitance impedance and the solution resistance, yielding results that correspond well with the fitted parameter values, thereby confirming the validity of the equations. The effect of incubation time, and two organic cell-adhesion promoting coatings, poly-L-lysine and laminin, on the interface impedance has been quantified using the model. This demonstrates the benefits of using this model in developing better understanding of the physical processes occurring at the interface in more complex, biomedically relevant situations.

  11. Management of Elevated Therapeutic Impedances on Deep Brain Stimulation Leads

    Directory of Open Access Journals (Sweden)

    Wissam Deeb

    2017-09-01

    Full Text Available Clinical Vignette: A 64-year-old male with a history of essential tremor with bilateral thalamic ventralis intermedius deep brain stimulation implants had elevated therapeutic impedance values despite normal lead integrity impedances and good response to stimulation.Clinical Dilemma: Do elevated therapeutic impedance values indicate a sign of hardware malfunction? What are the guidelines to approach deep brain stimulation hardware malfunction?Clinical Solution: Lead integrity impedance values are a better evaluation of hardware integrity. The discrepancy between therapeutic and lead-integrity impedance values can arise when using low voltage settings.Gaps in Knowledge: There are no established guidelines for the management of possible hardware malfunction in deep brain stimulation. The recommended approach is to distinguish between open and short circuit problems followed by an “inching” evaluation, assessing the structures from the implantable and programmable generator to the intracranial leads. Constant-current devices will deliver a more stable stimulation but the effect of their adoption is still not clear.Expert Commentary: This case emphasizes the need for clinicians to understand fundamental differences in lead integrity and therapeutic impedance while utilizing a methodical approach in treating hardware malfunction. It highlights future avenues of investigation regarding the utility of constant current DBS technology.

  12. Management of Elevated Therapeutic Impedances on Deep Brain Stimulation Leads.

    Science.gov (United States)

    Deeb, Wissam; Patel, Amar; Okun, Michael S; Gunduz, Aysegul

    2017-01-01

    A 64-year-old male with a history of essential tremor with bilateral thalamic ventralis intermedius deep brain stimulation implants had elevated therapeutic impedance values despite normal lead integrity impedances and good response to stimulation. Do elevated therapeutic impedance values indicate a sign of hardware malfunction? What are the guidelines to approach deep brain stimulation hardware malfunction? Lead integrity impedance values are a better evaluation of hardware integrity. The discrepancy between therapeutic and lead-integrity impedance values can arise when using low voltage settings. There are no established guidelines for the management of possible hardware malfunction in deep brain stimulation. The recommended approach is to distinguish between open and short circuit problems followed by an "inching" evaluation, assessing the structures from the implantable and programmable generator to the intracranial leads. Constant-current devices will deliver a more stable stimulation but the effect of their adoption is still not clear. This case emphasizes the need for clinicians to understand fundamental differences in lead integrity and therapeutic impedance while utilizing a methodical approach in treating hardware malfunction. It highlights future avenues of investigation regarding the utility of constant current DBS technology.

  13. Positive impedance humidity sensors via single-component materials.

    Science.gov (United States)

    Qian, Jingwen; Peng, Zhijian; Shen, Zhenguang; Zhao, Zengying; Zhang, Guoliang; Fu, Xiuli

    2016-05-06

    Resistivity-type humidity sensors have been investigated with great interest due to the increasing demands in industry, agriculture and daily life. To date, most of the available humidity sensors have been fabricated based on negative humidity impedance, in which the electrical resistance decreases as the humidity increases, and only several carbon composites have been reported to present positive humidity impedance. However, here we fabricate positive impedance humidity sensors only via single-component WO3-x crystals. The resistance of WO3-x crystal sensors in response to relative humidity could be tuned from a negative to positive one by increasing the compositional x. And it was revealed that the positive humidity impedance was driven by the defects of oxygen vacancy. This result will extend the application field of humidity sensors, because the positive humidity impedance sensors would be more energy-efficient, easier to be miniaturized and electrically safer than their negative counterparts for their lower operation voltages. And we believe that constructing vacancies in semiconducting materials is a universal way to fabricate positive impedance humidity sensors.

  14. Treatment Option Overview (Small Intestine Cancer)

    Science.gov (United States)

    ... all of an organ that contains cancer. The resection may include the small intestine and nearby organs (if the cancer has spread). The doctor may remove the section of the small intestine that contains cancer and perform an anastomosis (joining the cut ends of the intestine together). ...

  15. General Information about Small Intestine Cancer

    Science.gov (United States)

    ... all of an organ that contains cancer. The resection may include the small intestine and nearby organs (if the cancer has spread). The doctor may remove the section of the small intestine that contains cancer and perform an anastomosis (joining the cut ends of the intestine together). ...

  16. Abdominal tuberculosis presenting as intestinal obstruction- Case ...

    African Journals Online (AJOL)

    One of the complications of abdominal tuberculosis is intestinal obstruction, which can be acute, chronic or acute on chronic. Other complications include intestinal haemorrhage, perforation of the intestine (rare), faecal fistula, cold abscess formation, mal-absorption syndrome and dissemination of the tuberculosis to other ...

  17. Exercise and the gastro-intestinal tract

    African Journals Online (AJOL)

    on perfonnance and me value of cardiovascular training in improving performance in aerobic sports is well recognised. The role of me gastro-intestinal tracr, bom as a limiting and sustaining facror in aerobic exercises, is less well appreciared. Gastro-intestinal symptoms. The spectrum of gastro-intestinal effecrs of exercise ...

  18. Childhood intestinal obstruction in Northwestern Nigeria

    African Journals Online (AJOL)

    of childhood intestinal obstruction in this study agrees with those reportedis'gi m3 from other parts of the coun- try. Mortality from childhood intestinal obstruction is still high in our environment. References. 1. Otu AA. Tropical surgical abdominal emergencies: acute intestinal obstruction. Postgrad. Doctor (Afr) 1992; 14: 51. 2.

  19. Protein malnutrition and metronidazole induced intestinal bacterial ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-09-17

    Sep 17, 2008 ... The gastrointestinal tract serves as a potent barrier that prevents luminal bacteria from entering the host. This barrier function is maintained by a well-balanced intestinal flora, an unaltered perme- ability of the intestinal mucosa, and a normal functioning immune system. Furthermore, the intestinal mucosa, in.

  20. Childhood intestinal obstruction in Northwestern Nigeria | Uba ...

    African Journals Online (AJOL)

    Background: Intestinal obstruction is a common cause of childhood surgical emergency in the tropics. The aim of this paper was to assess the pattern and the outcome of mangement of intestinal obstruction in Nigerian children. Study design: The clinical reccords of all the cases of childhood intestinal obstructions managed ...

  1. The TNO gastro-intestinal model (TIM)

    NARCIS (Netherlands)

    Minekus, M.

    2015-01-01

    The TNO Gastro–Intestinal Model (TIM) is a multi–compartmental model, designed to realistically simulate conditions in the lumen of the gastro–intestinal tract. TIM is successfully used to study the gastro–intestinal behavior of a wide variety of feed, food and pharmaceutical products. Experiments

  2. Impedance of SOFC electrodes: A review and a comprehensive case study on the impedance of LSM:YSZ cathodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Hjelm, Johan

    2014-01-01

    It was shown through a comprehensive impedance spectroscopy study that the impedance of the classic composite LSM:YSZ (lanthanum strontium manganite and yttria stabilized zirconia) solid oxide fuel cell (SOFC) cathode can be described well with porous electrode theory. Furthermore, it was illustr......It was shown through a comprehensive impedance spectroscopy study that the impedance of the classic composite LSM:YSZ (lanthanum strontium manganite and yttria stabilized zirconia) solid oxide fuel cell (SOFC) cathode can be described well with porous electrode theory. Furthermore......, it was illustrated through a literature review on SOFC electrodes that porous electrode theory not only describes the classic LSM:YSZ SOFC cathode well, but SOFC electrodes in general. The extensive impedance spectroscopy study of LSM:YSZ cathodes consisted of measurements on cathodes with three different sintering...... temperatures and hence different microstructures and varying degrees of LSM/YSZ solid state interactions. LSM based composite cathodes, where YSZ was replaced with CGO was also studied in order to acquire further knowledge on the chemical compatibility between LSM and YSZ. All impedance measurements were...

  3. Entomoftoromicose intestinal: relato de caso

    Directory of Open Access Journals (Sweden)

    Fábia Aparecida Carvalho

    1997-02-01

    Full Text Available Os autores relatam um caso de entomoftoromicose intestinal causada por Entomophthorales, em indivíduo de 19 anos, agricultor e sem doença associada. O paciente foi submetido a ressecção intestinal e o diagnóstico foi feito após análise da peça cirúrgica. Após revisão da literatura, são discutidos a evolução clínica, as características clinicopatológicas, as dificuldades no diagnóstico e o tratamento dessa entidade rara.A case of intestinal entomophthoramycosis caused by Entomophthorales in a man with 19 years-old, farmer and without associated disease. The patient was submitted to a intestinal ressection and diagnosis was carried through after analisys of the surgical specimen. After a review of the literature, the clinical evolution, clinico-pathologic features, difficulties in diagnosis and treatment are discussed.

  4. Diversity of insect intestinal microflora

    Czech Academy of Sciences Publication Activity Database

    Mrázek, Jakub; Štrosová, Lenka; Fliegerová, Kateřina; Kott, T.; Kopečný, Jan

    2008-01-01

    Roč. 53, č. 3 (2008), s. 229-233 ISSN 0015-5632 R&D Projects: GA ČR GA303/06/0974 Institutional research plan: CEZ:AV0Z50450515 Keywords : insect intestinal microflora Subject RIV: EE - Microbiology, Virology Impact factor: 1.172, year: 2008

  5. Circadian disorganization alters intestinal microbiota.

    Science.gov (United States)

    Voigt, Robin M; Forsyth, Christopher B; Green, Stefan J; Mutlu, Ece; Engen, Phillip; Vitaterna, Martha H; Turek, Fred W; Keshavarzian, Ali

    2014-01-01

    Intestinal dysbiosis and circadian rhythm disruption are associated with similar diseases including obesity, metabolic syndrome, and inflammatory bowel disease. Despite the overlap, the potential relationship between circadian disorganization and dysbiosis is unknown; thus, in the present study, a model of chronic circadian disruption was used to determine the impact on the intestinal microbiome. Male C57BL/6J mice underwent once weekly phase reversals of the light:dark cycle (i.e., circadian rhythm disrupted mice) to determine the impact of circadian rhythm disruption on the intestinal microbiome and were fed either standard chow or a high-fat, high-sugar diet to determine how diet influences circadian disruption-induced effects on the microbiome. Weekly phase reversals of the light:dark (LD) cycle did not alter the microbiome in mice fed standard chow; however, mice fed a high-fat, high-sugar diet in conjunction with phase shifts in the light:dark cycle had significantly altered microbiota. While it is yet to be established if some of the adverse effects associated with circadian disorganization in humans (e.g., shift workers, travelers moving across time zones, and in individuals with social jet lag) are mediated by dysbiosis, the current study demonstrates that circadian disorganization can impact the intestinal microbiota which may have implications for inflammatory diseases.

  6. Milk products and intestinal health

    NARCIS (Netherlands)

    Van der Meer, R; Bovee-Oudenhoven, IMJ; Sesink, ALA; Kleibeuker, JH

    Milk products may improve intestinal health by means of the cytoprotective effects of their high calcium phosphate (CaPi) content. We hypothesized that this cytoprotection may increase host defenses against bacterial infections as well as decrease colon cancer risk. This paper summarizes our studies

  7. [Chronic intestinal pseudo-obstruction].

    Science.gov (United States)

    Joly, Francisca; Amiot, Aurélien; Coffin, Benoît; Lavergne-Slove, Anne; Messing, Bernard; Bouhnik, Yoram

    2006-01-01

    Chronic intestinal pseudo-obstruction (CIPO) is a disease characterized by episodes resembling mechanical obstruction in the absence of organic, systemic, or metabolic disorders. Pseudo-obstruction is an uncommon condition and can result from primary (40%) or secondary (60%) causes. The most common symptoms are nausea, vomiting, abdominal distension, abdominal pain and constipation or diarrhea. These symptoms are usually present many years before CIPO diagnosis. They can lead to severe electrolyte disorders and malnutrition. Principles for management of patients with CIPO are: to establish a correct clinical diagnosis in excluding mechanical obstruction; to perform a symptomatic and physiologic assessment of the gastrointestinal tract involved; to look for extra-intestinal manifestations, especially for myopathy and neuropathy; to discuss in some cases a surgery for full-thickness intestinal biopsies, and/or a neuromuscular biopsy in case of mitochondrial cytopathy suspicion. The management is primarily focused on symptom control and nutritional support to prevent weight loss and malnutrition. Treatment of CIPO includes prokinetic agents which may help to reduce gastrointestinal symptoms Courses of antibiotics may be needed in patients with symptoms suggestive of bacterial overgrowth. When necessary, enteral nutrition is preferred. In carefully selected patients, feeding jejunostomy with or without decompression gastrostomy may be tried. Long term parenteral nutrition should be reserved for patients who can not tolerate enteral nutrition. Intestinal transplantation can be discussed in selected patients.

  8. INTESTINAL PERMEABILITY IN PEDIATRIC GASTROENTEROLOGY

    NARCIS (Netherlands)

    VANELBURG, RM; UIL, JJ; DEMONCHY, JGR; HEYMANS, HSA

    1992-01-01

    The role of the physiologic barrier function of the small bowel and its possible role in health and disease has attracted much attention over the past decade. The intestinal mucosal barrier for luminal macromolecules and microorganism is the result of non-immunologic and immunologic defense

  9. Microcontainers for Intestinal Drug Delivery

    DEFF Research Database (Denmark)

    Tentor, Fabio; Mazzoni, Chiara; Keller, Stephan Sylvest

    Among all the drug administration routes, the oral one is the most preferred by the patients being less invasive, faster and easier. Oral drug delivery systems designed to target the intestine are produced by powder technology and capsule formulations. Those systems including micro- and nano...

  10. Stochastic Gabor reflectivity and acoustic impedance inversion

    Science.gov (United States)

    Hariri Naghadeh, Diako; Morley, Christopher Keith; Ferguson, Angus John

    2018-02-01

    To delineate subsurface lithology to estimate petrophysical properties of a reservoir, it is possible to use acoustic impedance (AI) which is the result of seismic inversion. To change amplitude to AI, removal of wavelet effects from the seismic signal in order to get a reflection series, and subsequently transforming those reflections to AI, is vital. To carry out seismic inversion correctly it is important to not assume that the seismic signal is stationary. However, all stationary deconvolution methods are designed following that assumption. To increase temporal resolution and interpretation ability, amplitude compensation and phase correction are inevitable. Those are pitfalls of stationary reflectivity inversion. Although stationary reflectivity inversion methods are trying to estimate reflectivity series, because of incorrect assumptions their estimations will not be correct, but may be useful. Trying to convert those reflection series to AI, also merging with the low frequency initial model, can help us. The aim of this study was to apply non-stationary deconvolution to eliminate time variant wavelet effects from the signal and to convert the estimated reflection series to the absolute AI by getting bias from well logs. To carry out this aim, stochastic Gabor inversion in the time domain was used. The Gabor transform derived the signal’s time–frequency analysis and estimated wavelet properties from different windows. Dealing with different time windows gave an ability to create a time-variant kernel matrix, which was used to remove matrix effects from seismic data. The result was a reflection series that does not follow the stationary assumption. The subsequent step was to convert those reflections to AI using well information. Synthetic and real data sets were used to show the ability of the introduced method. The results highlight that the time cost to get seismic inversion is negligible related to general Gabor inversion in the frequency domain. Also

  11. Intestinal epithelium in inflammatory bowel disease

    DEFF Research Database (Denmark)

    Coskun, Mehmet

    2014-01-01

    homeostasis. Therefore, dysregulation within the epithelial layer can increase intestinal permeability, lead to abnormalities in interactions between IECs and immune cells in underlying lamina propria, and disturb the intestinal immune homeostasis, all of which are linked to the clinical disease course......The intestinal epithelium has a strategic position as a protective physical barrier to luminal microbiota and actively contributes to the mucosal immune system. This barrier is mainly formed by a monolayer of specialized intestinal epithelial cells (IECs) that are crucial in maintaining intestinal...

  12. A etiological factors in mechanical intestinal obstruction

    International Nuclear Information System (INIS)

    Asad, S.; Khan, H.; Khan, I.A.; Ghaffar, S.; Rehman, Z.U.

    2012-01-01

    Background: Intestinal obstruction occurs when the normal flow of intestinal contents is interrupted. The most frequent causes of intestinal obstruction are postoperative adhesions and hernias, which cause extrinsic compression of the intestine. Less frequently, tumours or strictures of the bowel can cause intrinsic blockage. Objective of the study was to find out the various a etiological factors of mechanical intestinal obstruction and to evaluate the morbidity and mortality in adult patients presenting to Surgical 'A' unit of Ayub teaching hospital with mechanical intestinal obstruction. Methods: This cross-sectional study was conducted from March 2009 to September, 2009. All patients presenting with intestinal obstruction and were above the age of 12 years were included in the study. Patients with non-mechanical obstruction were excluded from the study and those who responded to conservative measures were also excluded. Results: A total of 36 patients with age ranging from 12 to 80 years (Mean age 37.72+-19.74 years) and male to female ratio of 1.77:1, were treated for mechanical intestinal obstruction. The most common cause for mechanical intestinal obstruction was adhesions (36.1%). Intestinal tuberculosis was the second most common cause (19.4%), while hernias and sigmoid volvulus affected 13.9% patients each. Malignancies were found in 5.6% cases. Conclusion: Adhesions and Tuberculosis are the leading causes of mechanical intestinal obstruction in Pakistan. Although some patients can be treated conservatively, a substantial portion requires immediate surgical intervention. (author)

  13. Intestinal Epithelial Sirtuin 1 Regulates Intestinal Inflammation During Aging in Mice by Altering the Intestinal Microbiota.

    Science.gov (United States)

    Wellman, Alicia S; Metukuri, Mallikarjuna R; Kazgan, Nevzat; Xu, Xiaojiang; Xu, Qing; Ren, Natalie S X; Czopik, Agnieszka; Shanahan, Michael T; Kang, Ashley; Chen, Willa; Azcarate-Peril, M Andrea; Gulati, Ajay S; Fargo, David C; Guarente, Leonard; Li, Xiaoling

    2017-09-01

    Intestinal epithelial homeostasis is maintained by complex interactions among epithelial cells, commensal gut microorganisms, and immune cells. Disruption of this homeostasis is associated with disorders such as inflammatory bowel disease (IBD), but the mechanisms of this process are not clear. We investigated how Sirtuin 1 (SIRT1), a conserved mammalian NAD + -dependent protein deacetylase, senses environmental stress to alter intestinal integrity. We performed studies of mice with disruption of Sirt1 specifically in the intestinal epithelium (SIRT1 iKO, villin-Cre+, Sirt1 flox/flox mice) and control mice (villin-Cre-, Sirt1 flox/flox ) on a C57BL/6 background. Acute colitis was induced in some mice by addition of 2.5% dextran sodium sulfate to drinking water for 5-9 consecutive days. Some mice were given antibiotics via their drinking water for 4 weeks to deplete their microbiota. Some mice were fed with a cholestyramine-containing diet for 7 days to sequester their bile acids. Feces were collected and proportions of microbiota were analyzed by 16S rRNA amplicon sequencing and quantitative PCR. Intestines were collected from mice and gene expression profiles were compared by microarray and quantitative PCR analyses. We compared levels of specific mRNAs between colon tissues from age-matched patients with ulcerative colitis (n=10) vs without IBD (n=8, controls). Mice with intestinal deletion of SIRT1 (SIRT1 iKO) had abnormal activation of Paneth cells starting at the age of 5-8 months, with increased activation of NF-κB, stress pathways, and spontaneous inflammation at 22-24 months of age, compared with control mice. SIRT1 iKO mice also had altered fecal microbiota starting at 4-6 months of age compared with control mice, in part because of altered bile acid metabolism. Moreover, SIRT1 iKO mice with defective gut microbiota developed more severe colitis than control mice. Intestinal tissues from patients with ulcerative colitis expressed significantly lower

  14. Intestinal perfusion in the study of intestinal absorption

    International Nuclear Information System (INIS)

    Baker, S.J.

    1976-01-01

    Several techniques for studying absorption by means of intestinal perfusion have been developed. While the principle is simple, the practice is complicated by absorption of the solvent and by excretion of fluid into the lumen. To improve reliability a ''marker'' is incorporated into the system; it should behave as nearly as possible like the nutrient of interest, except that it should be unabsorbable. A great many markers, including several labelled with radionuclides, have been developed for use with numerous nutrients, and perfusion methods using double or triple tubes or occlusive balloons have been tested. The perfusion technique is too complicated for routine diagnostic use, but it offers at present the only possibility of studying the function of defined sections of the small intestine in the intact human. (author)

  15. Radiation impedance of collapsed capacitive micromachined ultrasonic transducers.

    Science.gov (United States)

    Ozgurluk, Alper; Atalar, Abdullah; Köymen, Hayrettin; Olçum, Selim

    2012-06-01

    The radiation impedance of a capacitive micromachined ultrasonic transducer (CMUT) array is a critical parameter to achieve high performance. In this paper, we present a calculation of the radiation impedance of collapsed, clamped, circular CMUTs both analytically and using finite element method (FEM) simulations. First, we model the radiation impedance of a single collapsed CMUT cell analytically by expressing its velocity profile as a linear combination of special functions for which the generated pressures are known. For an array of collapsed CMUT cells, the mutual impedance between the cells is also taken into account. The radiation impedances for arrays of 7, 19, 37, and 61 circular collapsed CMUT cells for different contact radii are calculated both analytically and by FEM simulations. The radiation resistance of an array reaches a plateau and maintains this level for a wide frequency range. The variation of radiation reactance with respect to frequency indicates an inductance-like behavior in the same frequency range. We find that the peak radiation resistance value is reached at higher kd values in the collapsed case as compared with the uncollapsed case, where k is the wavenumber and d is the center-to-center distance between two neighboring CMUT cells.

  16. Utilization of bone impedance for age estimation in postmortem cases.

    Science.gov (United States)

    Ishikawa, Noboru; Suganami, Hideki; Nishida, Atsushi; Miyamori, Daisuke; Kakiuchi, Yasuhiro; Yamada, Naotake; Wook-Cheol, Kim; Kubo, Toshikazu; Ikegaya, Hiroshi

    2015-11-01

    In the field of Forensic Medicine the number of unidentified cadavers has increased due to natural disasters and international terrorism. The age estimation is very important for identification of the victims. The degree of sagittal closure is one of such age estimation methods. However it is not widely accepted as a reliable method for age estimation. In this study, we have examined whether measuring impedance value (z-values) of the sagittal suture of the skull is related to the age in men and women and discussed the possibility to use bone impedance for age estimation. Bone impedance values increased with aging and decreased after the age of 64.5. Then we compared age estimation through the conventional visual method and the proposed bone impedance measurement technique. It is suggested that the bone impedance measuring technique may be of value to forensic science as a method of age estimation. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

  17. Diagnostic criteria for mass lesions differentiating in electrical impedance mammography

    International Nuclear Information System (INIS)

    Karpov A; Korotkova M

    2013-01-01

    The purpose of this research was to determine the diagnostic criteria for differentiating volumetric lesions in the mammary gland in electrical impedance mammography. The research was carried out utilizing the electrical impedance computer mammograph ||MEIK v.5.6>>®, which enables to acquire images of 3-D conductivity distribution layers within mamma's tissues up to 5 cm depth. The weighted reciprocal projection method was employed to reconstruct the 3-D electric conductivity distribution of the examined organ. The results of 3,710 electrical impedance examinations were analyzed. The analysis of a volumetric lesion included assessment of its shape, contour, internal electrical structure and changes of the surrounding tissues. Moreover, mammary gland status was evaluated with the help of comparative and age-related electrical conductivity curves. The diagnostic chart is provided. Each criterion is measured in points. Using the numerical score for evaluation of mass and non-volumetric lesions within the mammary gland in electrical impedance mammography allowed comparing this information to BI-RADS categories developed by American College of Radiology experts. The article is illustrated with electrical impedance mammograms and tables.

  18. Diagnostic criteria for mass lesions differentiating in electrical impedance mammography

    Science.gov (United States)

    A, Karpov; M, Korotkova

    2013-04-01

    The purpose of this research was to determine the diagnostic criteria for differentiating volumetric lesions in the mammary gland in electrical impedance mammography. The research was carried out utilizing the electrical impedance computer mammograph llMEIK v.5.6gg®, which enables to acquire images of 3-D conductivity distribution layers within mamma's tissues up to 5 cm depth. The weighted reciprocal projection method was employed to reconstruct the 3-D electric conductivity distribution of the examined organ. The results of 3,710 electrical impedance examinations were analyzed. The analysis of a volumetric lesion included assessment of its shape, contour, internal electrical structure and changes of the surrounding tissues. Moreover, mammary gland status was evaluated with the help of comparative and age-related electrical conductivity curves. The diagnostic chart is provided. Each criterion is measured in points. Using the numerical score for evaluation of mass and non-volumetric lesions within the mammary gland in electrical impedance mammography allowed comparing this information to BI-RADS categories developed by American College of Radiology experts. The article is illustrated with electrical impedance mammograms and tables.

  19. Application of Vertical Electrodes in Microfluidic Channels for Impedance Analysis

    Directory of Open Access Journals (Sweden)

    Qiang Li

    2016-05-01

    Full Text Available This paper presents a microfluidic device with electroplated vertical electrodes in the side walls for impedance measurement. Based on the proposed device, the impedance of NaCl solutions with different concentrations and polystyrene microspheres with different sizes was measured and analyzed. The electroplating and SU-8-PDMS (SU-8-poly(dimethylsiloxane bonding technologies were firstly integrated for the fabrication of the proposed microfluidic device, resulting in a tightly three-dimensional structure for practical application. The magnitude of impedance of the tested solutions in the frequency range of 1 Hz to 100 kHz was analyzed by the Zennium electrochemical workstation. The results show that the newly designed microfluidic device has potential for impedance analysis with the advantages of ease of fabrication and the integration of 3D electrodes in the side walls. The newly designed impedance sensor can distinguish different concentrations of polystyrene microspheres and may have potential for cell counting in biological areas. By integrating with other techniques such as dielectrophoresis (DEP and biological recognition technology, the proposed device may have potential for the assay to identify foodborne pathogen bacteria.

  20. The bioelectrical impedance vector migration in healthy infants.

    Science.gov (United States)

    L'Abée, Carianne; Poorts-Borger, Petra H; Gorter, Erna H G M; Piccoli, Antonio; Stolk, Ronald P; Sauer, Pieter J J

    2010-04-01

    Detecting young children with high amount of body fat is important to intervene in the development of obesity. The aim of this study is to gain inside in the bioelectrical impedance vector analysis in healthy infants. Repeated measurements of whole body reactance and resistance were assessed, using a 50kHz frequency bioelectrical impedance analysis, in 51 boys and 62 girls during infancy. Bivariate vector analysis, which can be used to determine tissue hydration and soft tissue mass, was conducted. The 95% confidence intervals of the mean vectors for different age groups and the 95%, 75% and 50% tolerance intervals were plotted, using resistance and reactance components standardized by the participant's height. During infancy impedance vectors changed significantly: A vector migration of the Xc/H of 8.50ohm/m and the R/H of -95.68ohm/m between the age of two months and eight to twelve months (p=0.0001) was observed. Bivariate, reference tolerance intervals of the impedance vectors for healthy infants at the age of two months are presented. Our results show a significant impedance vector migration during the first year of life. New reference tolerance intervals for the second month of life were constructed. Copyright 2009 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  1. Impedance dispersion analysis of drug-membrane interactions

    Science.gov (United States)

    Tacheva, Bilyana; Paarvanova, Boyana; Ivanov, Ivan T.; Karabaliev, Miroslav

    2017-11-01

    Thin lipid films modified glassy carbon electrodes (GCE) were used in this work as model system for studying the interactions between two antipsychotic phenothiazine drugs, chlorpromazine and thioridazine, and the lipid fraction of the biomembranes. The lipid films on the electrode surface were obtained through the thinning of film-forming lipid solution deposited between an electrolyte phase and the working GC electrode. The effects of the drugs on the lipid film structure were investigated by electrochemical impedance spectroscopy (EIS). To characterize the electric properties of the lipid film the impedance of the working GCE is modeled with an equivalent circuit consisting of parallel capacitance Cp and resistance Rp. These capacitance and resistance are not frequency independent but could be calculated as equivalent Cp and Rp for each measured frequency of the impedance spectrum and presented as functions of the frequency f, Cp = Cp(f) and Rp= Rp(f). For the lipid films used in this work, it is demonstrated that both Cp(f) and Rp(f) are well approximated with power-law functions. This behavior implies that the impedance Z of the films could be analysed in terms of the well-known constant-phase angle element (CPE), which is often used to describe the interfacial impedance of solid working electrodes.

  2. Development of a wearable multi-frequency impedance cardiography device.

    Science.gov (United States)

    Weyer, Sören; Menden, Tobias; Leicht, Lennart; Leonhardt, Steffen; Wartzek, Tobias

    2015-02-01

    Cardiovascular diseases as well as pulmonary oedema can be early diagnosed using vital signs and thoracic bio-impedance. By recording the electrocardiogram (ECG) and the impedance cardiogram (ICG), vital parameters are captured continuously. The aim of this study is the continuous monitoring of ECG and multi-frequency ICG by a mobile system. A mobile measuring system, based on 'low-power' ECG, ICG and an included radio transmission is described. Due to the high component integration, a board size of only 6.5 cm×5 cm could be realized. The measured data can be transmitted via Bluetooth and visualized on a portable monitor. By using energy-efficient hardware, the system can operate for up to 18 hs with a 3 V battery, continuously sending data via Bluetooth. Longer operating times can be realized by decreased transfer rates. The relative error of the impedance measurement was less than 1%. The ECG and ICG measurements allow an approximate calculation of the heart stroke volume. The ECG and the measured impedance showed a high correlation to commercial devices (r=0.83, p<0.05). In addition to commercial devices, the developed system allows a multi-frequency measurement of the thoracic impedance between 5-150 kHz.

  3. Impedance cardiography – optimization and efficacy evaluation of antihypertensive treatment

    Directory of Open Access Journals (Sweden)

    Katarzyna Panasiuk-Kamińska

    2016-09-01

    Full Text Available Background . Hypertension is a civilization disease which currently affects about 10.5 m people in Poland. The number of patients with diagnosed, untreated hypertension amounts to 18%, and as many as 45% of patients are treated ineffectively whereas only 26% are treated effectively. Impedance cardiography (IC is an important tool both in diagnostics and the treatment of hypertensive patients, particularly in the case of antihypertensive treatment resistance. This method allows for the individualized treatment of each patient on the basis of hemodynamic parameters, monitoring of hypertensive patients in the outpatient care setting, and the assessment of cardiovascular risk factors. Objectives . The aim of the study was to evaluate the efficacy of hypotensive medications in patients with hypertension using impedance cardiography. Material and methods. The study involved 60 hypertensive patients, treated with antihypertensives, who failed to achieve the required blood pressure values. The modification of hypertension therapy was based on EBM (evidence-based medicine and on hemodynamic parameters obtained using impedance cardiography. Results . It was found that high blood pressure therapy based on impedance cardiography parameters has a significant influence on blood pressure reduction compared to EM B-based therapy: below 140/90: 66.8 vs. 55.1% and below 130/80: 23.5 vs. 18.9%. Conclusions . On the basis of this study it was confirmed that impedance cardiography allows for a significant reduction of hypertension and the selection of the most effective therapeutic strategy, providing for the optimization and efficacy of hypertension treatment.

  4. The Contributions of Human Mini-Intestines to the Study of Intestinal Physiology and Pathophysiology.

    Science.gov (United States)

    Yu, Huimin; Hasan, Nesrin M; In, Julie G; Estes, Mary K; Kovbasnjuk, Olga; Zachos, Nicholas C; Donowitz, Mark

    2017-02-10

    The lack of accessibility to normal and diseased human intestine and the inability to separate the different functional compartments of the intestine even when tissue could be obtained have held back the understanding of human intestinal physiology. Clevers and his associates identified intestinal stem cells and established conditions to grow "mini-intestines" ex vivo in differentiated and undifferentiated conditions. This pioneering work has made a new model of the human intestine available and has begun making contributions to the understanding of human intestinal transport in normal physiologic conditions and the pathophysiology of intestinal diseases. However, this model is reductionist and lacks many of the complexities of normal intestine. Consequently, it is not yet possible to predict how great the advances using this model will be for understanding human physiology and pathophysiology, nor how the model will be modified to include multiple other intestinal cell types and physical forces necessary to more closely approximate normal intestine. This review describes recent studies using mini-intestines, which have readdressed previously established models of normal intestinal transport physiology and newly examined intestinal pathophysiology. The emphasis is on studies with human enteroids grown either as three-dimensional spheroids or two-dimensional monolayers. In addition, comments are provided on mouse studies in cases when human studies have not yet been described.

  5. Low-frequency quadrupole impedance of undulators and wigglers

    Directory of Open Access Journals (Sweden)

    A. Blednykh

    2016-10-01

    Full Text Available An analytical expression of the low-frequency quadrupole impedance for undulators and wigglers is derived and benchmarked against beam-based impedance measurements done at the 3 GeV NSLS-II storage ring. The adopted theoretical model, valid for an arbitrary number of electromagnetic layers with parallel geometry, allows to calculate the quadrupole impedance for arbitrary values of the magnetic permeability μ_{r}. In the comparison of the analytical results with the measurements for variable magnet gaps, two limit cases of the permeability have been studied: the case of perfect magnets (μ_{r}→∞, and the case in which the magnets are fully saturated (μ_{r}=1.

  6. Characterization of lithium-thionyl chloride cells by impedance techniques

    Science.gov (United States)

    Walsh, F.; Pozin, M.; Cherniy, A.; Tikhonov, K.

    The main contributor to voltage drop observed on initial discharge of lithium-thionyl chloride cells is the resistance of the passive layer on the lithium anode, as can be determined from the Nyquist plot of a lithium-thionyl chloride cell. At extremely low discharge currents, initial voltage drop corresponds to the value found from the impedance measurements; at higher current, an empirical correction based on the experimental results is required. The dispersion in the values of the impedance parameters and thus in initial voltage drop of individual cells was analyzed. The condition of the lithium surface after assembly was shown not to be the only reason for high dispersion in impedance parameter values.

  7. Fiber Materials AC Impedance Characteristics and Principium Analysis

    Science.gov (United States)

    Wang, Jianjun; Li, Xiaofeng

    With an invariable amplitude and variable frequency inspiriting, impedance of fiber materials rapidly decrease at first and then increase speedy followed with increasing of signal frequency. For the impedance curve of frequency is section of bathtub, this phenomenon is defined as alternating current electric conductive bathtub effect of fiber material. With analysis tools,of circuit theory and medium polarization theory, the phenomenon can be deeply detected that in AC electric field there are four different kind of currents in fiber material: absorbing current, conductance current, charging current and superficial current. With more analyzing it's discovered this phenomenon can be explained by medium polarize theory. Make using of fiber AC electric conductivity bathtub effect, fast testing equipment on fiber moisture regain can be invent, and disadvantages of conventional impedance technique, such as greatness test error and electrode polarization easily. This paper affords directions to design novel speediness fiber moisture test equipments in theory.

  8. Impedance-based damage assessment using piezoelectric sensors

    Science.gov (United States)

    Rim, Mi-Sun; Yoo, Seung-Jae; Lee, In; Song, Jae-Hoon; Yang, Jae-Won

    2011-04-01

    Recently structural health monitoring (SHM) systems are being focused because they make it possible to assess the health of structures at real-time in many application fields such as aircraft, aerospace, civil and so on. Piezoelectric materials are widely used for sensors of SHM system to monitor damage of critical parts such as bolted joints. Bolted joints could be loosened by vibration, thermal cycling, shock, corrosion, and they cause serious mechanical failures. In this paper, impedance-based method using piezoelectric sensors was applied for real-time SHM. A steel beam specimen fastened by bolts was tested, and polymer type piezoelectric materials, PVDFs were used for sensors to monitor the condition of bolted joint connections. When structure has some damage, for example loose bolts, the impedance of PVDF sensors showed different tendency with normal structure which has no loose bolts. In the case of loose bolts, impedance values are decreased and admittance values are increased.

  9. Analytic model of Applied-B ion diode impedance behavior

    International Nuclear Information System (INIS)

    Miller, P.A.; Mendel, C.W. Jr.

    1987-01-01

    An empirical analysis of impedance data from Applied-B ion diodes used in seven inertial confinement fusion research experiments was published recently. The diodes all operated with impedance values well below the Child's-law value. The analysis uncovered an unusual unifying relationship among data from the different experiments. The analysis suggested that closure of the anode-cathode gap by electrode plasma was not a dominant factor in the experiments, but was not able to elaborate the underlying physics. Here we present a new analytic model of Applied-B ion diodes coupled to accelerators. A critical feature of the diode model is based on magnetic insulation theory. The model successfully describes impedance behavior of these diodes and supports stimulating new viewpoints of the physics of Applied-B ion diode operation

  10. Diffusion and conversion impedance in solid oxide fuel cells

    DEFF Research Database (Denmark)

    Jacobsen, Torben; Hendriksen, Peter Vang; Koch, Søren

    2008-01-01

    In fuel cell electrodes where the thin, active electrode layer is supported by a porous layer the diffusion processes as well as the change in the gas phase composition due to the conversion of reactants will influence the cell impedance. Two models are developed for the description of these proc......In fuel cell electrodes where the thin, active electrode layer is supported by a porous layer the diffusion processes as well as the change in the gas phase composition due to the conversion of reactants will influence the cell impedance. Two models are developed for the description...... to consumption of reactants and accumulation of products. For simplicity this model is restricted to cases dominated by mass transfer and conversion of the gas supply. Qualitatively the predictions by both models are alike. At high frequencies a Warburg diffusion impedance is seen. Depending on the dimensions...

  11. A Wireless Multi-Sensor Dielectric Impedance Spectroscopy Platform

    Directory of Open Access Journals (Sweden)

    Seyed Alireza Ghaffari

    2015-09-01

    Full Text Available This paper describes the development of a low-cost, miniaturized, multiplexed, and connected platform for dielectric impedance spectroscopy (DIS, designed for in situ measurements and adapted to wireless network architectures. The platform has been tested and used as a DIS sensor node on ZigBee mesh and was able to interface up to three DIS sensors at the same time and relay the information through the network for data analysis and storage. The system is built from low-cost commercial microelectronics components, performs dielectric spectroscopy ranging from 5 kHz to 100 kHz, and benefits from an on-the-fly calibration system that makes sensor calibration easy. The paper describes the microelectronics design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the testing of the platform for in situ dielectric impedance spectroscopy applications pertaining to fertilizer sensing, water quality sensing, and touch sensing.

  12. Road Impedance Model Study under the Control of Intersection Signal

    Directory of Open Access Journals (Sweden)

    Yunlin Luo

    2015-01-01

    Full Text Available Road traffic impedance model is a difficult and critical point in urban traffic assignment and route guidance. The paper takes a signalized intersection as the research object. On the basis of traditional traffic wave theory including the implementation of traffic wave model and the analysis of vehicles’ gathering and dissipating, the road traffic impedance model is researched by determining the basic travel time and waiting delay time. Numerical example results have proved that the proposed model in this paper has received better calculation performance compared to existing model, especially in flat hours. The values of mean absolute percentage error (MAPE and mean absolute deviation (MAD are separately reduced by 3.78% and 2.62 s. It shows that the proposed model has feasibility and availability in road traffic impedance under intersection signal.

  13. Advanced impedance modeling of solid oxide electrochemical cells

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Hjelm, Johan

    2014-01-01

    Impedance spectroscopy is a powerful technique for detailed study of the electrochemical and transport processes that take place in fuel cells and electrolysis cells, including solid oxide cells (SOCs). Meaningful analysis of impedance measurements is nontrivial, however, because a large number...... of modeling parameters are fit to the many processes which often overlap in the same frequency ranges. Also, commonly used equivalent circuit (EC) models only provide zero-dimensional (0-D) approximations of the processes of the two electrodes, electrolyte and gas transport. Employing improved analytical...... electrode and 2-D gas transport models which have fewer unknown parameters for the same number of processes, (ii) use of a new model fitting algorithm, “multi-fitting”, in which multiple impedance spectra are fit simultaneously with parameters linked based on the variation of measurement conditions, (iii...

  14. Effect of the Tem Mode on the kicker Impedance

    CERN Document Server

    Zannini, C; Vaccaro, VG

    2012-01-01

    The kickers are major contributors to the CERN SPS beam coupling impedance. As such, they may represent a limitation to increasing the SPS bunch current in the frame of a luminosity upgrade of the LHC. The C-Magnet supports a transverse electromagnetic (TEM) mode due to the presence of two conductors. Due to the finite length of the structure this TEM mode affects the impedance below a certain frequency (when the penetration depth in the ferrite becomes comparable to the magnetic circuit length). A theoretical model was developed to take into account also the impedance contribution due to the TEM mode. The model is found to be in good agreement with CST 3D electromagnetic (EM) simulations. It allows for generic terminations in the longitudinal direction. An example of kicker is analyzed taking into account also the external cables.

  15. Energy storage cell impedance measuring apparatus, methods and related systems

    Science.gov (United States)

    Morrison, John L.; Morrison, William H.; Christophersen, Jon P.

    2017-12-26

    Energy storage cell impedance testing devices, circuits, and related methods are disclosed. An energy storage cell impedance measuring device includes a sum of sinusoids (SOS) current excitation circuit including differential current sources configured to isolate a ground terminal of the differential current sources from a positive terminal and a negative terminal of an energy storage cell. A method includes applying an SOS signal comprising a sum of sinusoidal current signals to the energy storage cell with the SOS current excitation circuit, each of the sinusoidal current signals oscillating at a different one of a plurality of different frequencies. The method also includes measuring an electrical signal at a positive terminal and a negative terminal of the energy storage cell, and computing an impedance of the energy storage cell at each of the plurality of different frequencies using the measured electrical signal.

  16. Ferromagnetic resonance in gigahertz magneto-impedance of multilayer systems

    International Nuclear Information System (INIS)

    Cos, D. de; Garcia-Arribas, A.; Barandiaran, J.M.

    2006-01-01

    The effect of ferromagnetic resonance (FMR) on magneto-impedance (MI) of multilayer thin films is investigated. We present impedance measurements of an insulated multilayer film as a function of the applied magnetic field both in the plane of the sample and perpendicular to it, for frequencies from 300 kHz to 3 GHz. These measurements have been made using RF techniques, and the data have been treated using high-frequency models in order to minimize the contribution to the impedance of the test fixture. The results confirm that the FMR dominates the MI behavior at high frequency, allowing to reach higher MI ratios than those achieved at the quasistatic regime. However, the broad resonance lines cause a considerable drop of the sensitivity of the curves, and therefore the optimum operation frequency of GMI devices lays in the sub-GHz range

  17. Experimental verification of depolarization effects in bioelectrical impedance measurement.

    Science.gov (United States)

    Chen, Xiaoyan; Lv, Xinqiang; Du, Meng

    2014-01-01

    The electrode polarization effects on bioelectrical impedance measurement at low-frequency cannot be ignored. In this paper, the bioelectrical data of mice livers are measured to specify the polarization effects on the bio-impedance measurement data. We firstly introduce the measurement system and methodology. Using the depolarization method, the corrected results are obtained. Besides, the specific effects of electrode polarization on bio-impedance measurement results are investigated using comparative analysis of the previous and posterior correction results from dielectric spectroscopy, Cole-Cole plot, conductivity and spectroscopy of dissipation tangent. Experimental results show that electrode polarization has a significant influence on the characteristic parameters of mouse liver tissues. To be specific, we see a low-frequency limit resistance R0 increase by 19.29%, a reactance peak XP increase by 8.50%, a low-frequency limit conductivity Kl decrease by 17.65% and a dissipation peak tangent decrease by 160%.

  18. Grid impedance detection via excitation of LCL-filter resonance

    DEFF Research Database (Denmark)

    Liserre, Marco; Blaabjerg, Frede; Teodorescu, Remus

    2005-01-01

    Inverters adopted in distributed power generation, active filter and UPS are often connected to the grid through an LCL-fiIter. The impedance of the LCL-fiIter has a typical frequency spectrum with a resonance peak. Hence the LCL-fiIter has to be damped in order to avoid instability. However...... the resonance of the LCL-fiIter can be also excited in a controlled way in order to individuate the resonance frequency in the spectrum (using for example the FFn. This paper proposes to use a controlled excitation to measure the grid impedance, since this one influences also the resonance frequency. This paper...... will address some possible limits, some solutions and some implementation issues (e.g. how to obtain a controlled resonance in the filter without damaging the system) in order to use the resonant peak for grid impedance detection. The analysis is validated both by simulations and experimental results....

  19. The effect of vocal tract impedance on the vocal folds

    DEFF Research Database (Denmark)

    Agerkvist, Finn T.; Selamtzis, Andreas

    2011-01-01

    The importance of the interaction between the acoustic impedance of the vocal tract with the flow across the vocal cords is well established. In this paper we are investigating the changes in vocal tract impedance when using the different modes of phonation according to Sadolin [1], going from...... the soft levels of the Neutral mode to the high levels of the fully ‘metallic’ Edge mode. The acoustic impedance of vocal tract as seen from the mouth opening is measured via a microphone placed close to the mouth when exciting the system with a volume velocity source [2]. At the same time a Laryngograph...... frontend is used to measure the electroglottograph signal which reflects the opening and closing pattern of the vocal folds. The measurements were carried out for all four modes (Neutral, Curbing, Overdrive and Edge) for the vowel [a] in three different pitches: C3(131 Hz), G3 (196 Hz) and C4 (262Hz...

  20. Electrical impedance tomography of the 1995 OGI gasoline release

    International Nuclear Information System (INIS)

    Daily, W.; Ramirez, A.

    1996-01-01

    Electrical impedance tomography (EIT) was used to image the plume resulting from a release of 378 liters (100 gallons) of gasoline into a sandy acquifer. Images were made in 5 planes before and 5 times during the release, to generate a detailed picture of the spatial as well as the temporal development of the plume as it spread at the water table. Information of the electrical impedance (both in phase and out of phase voltages) was used or several different frequencies to produce images. We observed little dispersion in the images either before or after the gasoline entered the acquifer. Likewise, despite some laboratory measurements of impedances, there was no evidence of a change in the reactance in the soil because of the gasoline

  1. The intestinal microenvironment in sepsis.

    Science.gov (United States)

    Fay, Katherine T; Ford, Mandy L; Coopersmith, Craig M

    2017-10-01

    The gastrointestinal tract has long been hypothesized to function as "the motor" of multiple organ dysfunction syndrome. The gastrointestinal microenvironment is comprised of a single cell layer epithelia, a local immune system, and the microbiome. These three components of the intestine together play a crucial role in maintaining homeostasis during times of health. However, the gastrointestinal microenvironment is perturbed during sepsis, resulting in pathologic changes that drive both local and distant injury. In this review, we seek to characterize the relationship between the epithelium, gastrointestinal lymphocytes, and commensal bacteria during basal and pathologic conditions and how the intestinal microenvironment may be targeted for therapeutic gain in septic patients. Published by Elsevier B.V.

  2. Drug Transporters in the Intestine

    DEFF Research Database (Denmark)

    Steffansen, Bente

    2016-01-01

    that may impact drug absorption. Thus absorptive transporters may facilitate BA of APIs that are substrates/victims for the transporters and have permeability-limited absorption, i.e. those that are classified in the biopharmaceutics classification system (BCS) Class 3 and 4. On the other hand, exsorptive...... transporters may restrict BA of APIs that are victims for these efflux transporters, especially those APIs classified to have solubility-limited absorption, i.e. compounds in BCS Class 2 and 4. The aim of the present Chapter is to review drug transporters (DTs) present within the intestine and to discuss...... and exemplify their roles in drug absorption/exsorption and in drug-drug interactions (DDIs). Although focus in the present Chapter is on DTs that are mentioned in American and European regulatory guidances, the intestinal transporters for nutrients and endogens (endogenous compounds) are also briefly...

  3. Tunable nanogap devices for ultra-sensitive electrochemical impedance biosensing

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yong [Department of Chemistry, Wannan Medical College, Wuhu 241002 (China); Guo, Zheng [Nanomaterials and Environmental Detection Laboratory, Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031 (China); Song, Jing-Jing; Huang, Qin-An; Zhu, Si-Wei [Department of Chemistry, Wannan Medical College, Wuhu 241002 (China); Huang, Xing-Jiu [Nanomaterials and Environmental Detection Laboratory, Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031 (China); Wei, Yan, E-mail: yanwei_wnmc@hotmail.com [Department of Chemistry, Wannan Medical College, Wuhu 241002 (China)

    2016-01-28

    A wealth of research has been available discussing nanogap devices for detecting very small quantities of biomolecules by observing their electrical behavior generally performed in dry conditions. We report that a gold nanogapped electrode with tunable gap length for ultra-sensitive detection of streptavidin based on electrochemical impedance technique. The gold nanogap is fabricated using simple monolayer film deposition and in-situ growth of gold nanoparticles in a traditional interdigitated array (IDA) microelectrode. The electrochemical impedance biosensor with a 25-nm nanogap is found to be ultra-sensitive to the specific binding of streptavidin to biotin. The binding of the streptavidin hinder the electron transfer between two electrodes, resulting in a large increase in electron-transfer resistance (R{sub et}) for operating the impedance. A linear relation between the relative R{sub et} and the logarithmic value of streptavidin concentration is observed in the concentration range from 1 pM (picomolar) to 100 nM (nanomolar). The lowest detectable concentration actually measured reaches 1 pM. We believe that such an electrochemical impedance nanogap biosensor provides a useful approach towards biomolecular detection that could be extended to a number of other systems. - Highlights: • A tunable gold nanogap device was used as to electrochemical impedance biosensor. • Linear range from 1 pM to 100 nM with LOD of 1 pM for streptavidin detection was obtained. • The nanogap devices exhibit a satisfactory precision, stability, and reproducibility. • The combination of electrochemical impedance technique and nanogap devices was achieved.

  4. Signal Processing for the Impedance Measurement on an Electrochemical Generator

    Directory of Open Access Journals (Sweden)

    El-Hassane AGLZIM

    2008-04-01

    Full Text Available Improving the life time of batteries or fuel cells requires the optimization of components such as membranes and electrodes and enhancement of the flow of gases [1], [2]. These goals could be reached by using a real time measurement on loaded generator. The impedance spectroscopy is a new way that was recently investigated. In this paper, we present an electronic measurement instrumentation developed in our laboratory to measure and plot the impedance of a loaded electrochemical generator like batteries and fuel cells. Impedance measures were done according to variations of the frequency in a larger band than what is usually used. The electronic instrumentation is controlled by Hpvee® software which allows us to plot the Nyquist graph of the electrochemical generator impedance. The theoretical results obtained in simulation under Pspice® confirm the choice of the method and its advantage. For safety reasons, the experimental preliminary tests were done on a 12 V vehicle battery, having an input current of 330 A and a capacity of 40 Ah and are now extended to a fuel cell. The results were plotted at various nominal voltages of the battery (12.7 V, 10 V, 8 V and 5 V and with two imposed currents (0.6 A and 4 A. The Nyquist diagram resulting from the experimental data enable us to show an influence of the load of the battery on its internal impedance. The similitude in the graph form and in order of magnitude of the values obtained (both theoretical and practical enables us to validate our electronic measurement instrumentation. Different sensors (temperature, pressure were placed around the device under test (DUT. These influence parameters were permanently recorded. Results presented here concern a classic loaded 12 V vehicle battery. The Nyquist diagram resulting from the experimental data confirms the influence of the load of the DUT on its internal impedance.

  5. Subnanosecond-rise-time, low-impedance pulse generator

    International Nuclear Information System (INIS)

    Druce, R.; Vogtlin, G.

    1983-01-01

    This paper describes a fast rise, low-impedance pulse generator that has been developed at the Lawrence Livermore National Laboratory. The design specifications of this generator are: 50-kV operating voltage, 1-ohm output impedance, subnanosecond rise time, and a 2 to 10 nanosecond pulse length. High repetition rate is not required. The design chosen is a parallel-plate, folded Blumlein generator. A tack switch is utilized for its simple construction and high performance. The primary diagnostic is a capacitive voltage divider with a B probe used to measure the current waveform

  6. Electrochemical Impedance Imaging via the Distribution of Diffusion Times

    Science.gov (United States)

    Song, Juhyun; Bazant, Martin Z.

    2018-03-01

    We develop a mathematical framework to analyze electrochemical impedance spectra in terms of a distribution of diffusion times (DDT) for a parallel array of random finite-length Warburg (diffusion) or Gerischer (reaction-diffusion) circuit elements. A robust DDT inversion method is presented based on complex nonlinear least squares regression with Tikhonov regularization and illustrated for three cases of nanostructured electrodes for energy conversion: (i) a carbon nanotube supercapacitor, (ii) a silicon nanowire Li-ion battery, and (iii) a porous-carbon vanadium flow battery. The results demonstrate the feasibility of nondestructive "impedance imaging" to infer microstructural statistics of random, heterogeneous materials.

  7. Impedance Studies for the Phase 2 LHC Collimators

    CERN Document Server

    Métral, E; Grudiev, A; Kroyer, T; Zotter, B; Roncarolo, F; Salvant, B

    2010-01-01

    The LHC phase 2 collimation project aims at gaining a factor ten in cleaning efficiency, robustness and impedance reduction. From the impedance point of view, several ideas emerged during the last year, such as using dielectric collimators, slots or rods in copper plates, or Litz wires. The purpose of this paper is to discuss the possible choices, showing analytical estimates, electromagnetic simulations performed using Maxwell, HFSS and GdFidL, and preliminary bench measurements. The corresponding complex tune shifts are computed for the different cases and compared on the stability diagram defined by the settings of the Landau octupoles available in the LHC at 7 TeV.

  8. Impedance technique for measuring dielectrophoretic collection of microbiological particles

    CERN Document Server

    Allsopp, D W E; Brown, A P; Betts, W B

    1999-01-01

    Measurement of the impedance change resulting from the collection of microbiological particles at coplanar electrodes is shown to be an effective and potentially quantitative method of detecting dielectrophoresis. Strong correlations between the frequency-dependent dielectrophoretic collection characteristics measured by impedance change and those observed using an established counting method based on image analysis have been obtained for Escherichia coli. In addition it is shown that the new electrical method can be used to sense dielectrophoretic collection of 19 nm diameter latex beads, particles too small to be resolved by conventional optical detection systems. (author)

  9. Electrical impedance along connective tissue planes associated with acupuncture meridians

    Directory of Open Access Journals (Sweden)

    Hammerschlag Richard

    2005-05-01

    Full Text Available Abstract Background Acupuncture points and meridians are commonly believed to possess unique electrical properties. The experimental support for this claim is limited given the technical and methodological shortcomings of prior studies. Recent studies indicate a correspondence between acupuncture meridians and connective tissue planes. We hypothesized that segments of acupuncture meridians that are associated with loose connective tissue planes (between muscles or between muscle and bone visible by ultrasound have greater electrical conductance (less electrical impedance than non-meridian, parallel control segments. Methods We used a four-electrode method to measure the electrical impedance along segments of the Pericardium and Spleen meridians and corresponding parallel control segments in 23 human subjects. Meridian segments were determined by palpation and proportional measurements. Connective tissue planes underlying those segments were imaged with an ultrasound scanner. Along each meridian segment, four gold-plated needles were inserted along a straight line and used as electrodes. A parallel series of four control needles were placed 0.8 cm medial to the meridian needles. For each set of four needles, a 3.3 kHz alternating (AC constant amplitude current was introduced at three different amplitudes (20, 40, and 80 μAmps to the outer two needles, while the voltage was measured between the inner two needles. Tissue impedance between the two inner needles was calculated based on Ohm's law (ratio of voltage to current intensity. Results At the Pericardium location, mean tissue impedance was significantly lower at meridian segments (70.4 ± 5.7 Ω compared with control segments (75.0 ± 5.9 Ω (p = 0.0003. At the Spleen location, mean impedance for meridian (67.8 ± 6.8 Ω and control segments (68.5 ± 7.5 Ω were not significantly different (p = 0.70. Conclusion Tissue impedance was on average lower along the Pericardium meridian, but not

  10. Amplifier input impedance in dry electrode ECG recording.

    Science.gov (United States)

    Assambo, Cedric; Burke, Martin J

    2009-01-01

    This paper presents a novel approach for designing the front-end of instrumentation amplifiers for use in dry electrode recording of the human electrocardiogram (ECG). The method relies on information provided by the characterization of the skin-electrode interface and the analysis of low frequency ECG criteria defined by international standards. Marginal measurements of capacitive elements of the skin-electrode interface as small as 0.01 microF, suggest values of input impedance in the order of 1.3 GOmega. However, results in 99% of the data analyzed indicate that a recording amplifier providing an input impedance of 500 MOmega should ensure clear signal sensing without distortion.

  11. LEIR impedance model and coherent beam instability observations

    CERN Document Server

    Biancacci, N; Migliorati, M; Rijoff, T L

    2017-01-01

    The LEIR machine is the first synchrotron in the ion ac-celeration chain at CERN and it is responsible to deliverhigh intensity ion beams to the LHC. Following the recentprogress in the understanding of the intensity limitations,detailed studies of the machine impedance started. In thiswork we describe the present LEIR impedance model, detail-ing the contribution to the total longitudinal and transverseimpedance of several machine elements. We then comparethe machine tune shift versus intensity predictions againstmeasurements at injection energy and summarize the co-herent instability observations in the absence of transversefeedback.

  12. Acoustic characteristics of the medium with gradient change of impedance

    Science.gov (United States)

    Hu, Bo; Yang, Desen; Sun, Yu; Shi, Jie; Shi, Shengguo; Zhang, Haoyang

    2015-10-01

    The medium with gradient change of acoustic impedance is a new acoustic structure which developed from multiple layer structures. In this paper, the inclusion is introduced and a new set of equations is developed. It can obtain better acoustic properties based on the medium with gradient change of acoustic impedance. Theoretical formulation has been systematically addressed which demonstrates how the idea of utilizing this method. The sound reflection and absorption coefficients were obtained. At last, the validity and the correctness of this method are assessed by simulations. The results show that appropriate design of parameters of the medium can improve underwater acoustic properties.

  13. Anisotropic bioelectrical impedance determination of subcutaneous fat thickness

    Science.gov (United States)

    Hernández-Becerra, P. A. I.; Delgadillo-Holtfort, I.; Balleza-Ordaz, M.; Huerta-Franco, M. R.; Vargas-Luna, M.

    2014-11-01

    Preliminary results have shown that bioelectrical impedance measurements performed on different parts of the human body strongly depend upon the subcutaneous fat of the considered region. In this work, a method for the determination of subcutaneous fat thickness is explored. Within this method the measurement of the bioelectrical impedance response of the fat-muscle system, both along the direction defined by the muscle fibers and along the corresponding perpendicular direction, are performed. Measurements have been carried out on human female and male subjects of ages around 25 years old at the region of the biceps. Correlation has been performed with skinfold caliper measurements.

  14. Line impedance estimation using model based identification technique

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai; Agelidis, Vassilios; Teodorescu, Remus

    2011-01-01

    The estimation of the line impedance can be used by the control of numerous grid-connected systems, such as active filters, islanding detection techniques, non-linear current controllers, detection of the on/off grid operation mode. Therefore, estimating the line impedance can add extra functions......-passive behaviour of the proposed method comes from the combination of the non intrusive behaviour of the passive methods with a better accuracy of the active methods. The simulation results reveal the good accuracy of the proposed method....

  15. Theory of fractional order elements based impedance matching networks

    KAUST Repository

    Radwan, Ahmed G.

    2011-03-01

    Fractional order circuit elements (inductors and capacitors) based impedance matching networks are introduced for the first time. In comparison to the conventional integer based L-type matching networks, fractional matching networks are much simpler and versatile. Any complex load can be matched utilizing a single series fractional element, which generally requires two elements for matching in the conventional approach. It is shown that all the Smith chart circles (resistance and reactance) are actually pairs of completely identical circles. They appear to be single for the conventional integer order case, where the identical circles completely overlap each other. The concept is supported by design equations and impedance matching examples. © 2010 IEEE.

  16. High sound screening in low impedance slit arrays

    International Nuclear Information System (INIS)

    Estrada, Hector; Bravo, Jose Maria; Meseguer, Francisco

    2011-01-01

    We report on the key role of the acoustical impedance ratio between the solid and the host fluid in the transmission properties of slit arrays. Numerical calculations predict huge sound screening effects up to 60 dB for low impedance ratio values. The screening band appears over a broad frequency region and is very robust against dissipative losses of the material as well as against the sound incident angle. This counterintuitive result is discussed in terms of the hydrodynamic short circuit, where the fluid and the solid at the radiating interface vibrate out of phase, resulting in a huge sound blocking effect.

  17. The frequency characteristics of medium voltage distribution system impedances

    Directory of Open Access Journals (Sweden)

    Liviu Emil Petrean

    2009-10-01

    Full Text Available In this paper we present the frequency characteristics of impedances involved in the electrical equivalent circuit of a large medium voltage distribution system. These impedances influence harmonics distortions propagation occurring due to the nonsinusoidal loads. We analyse the case of a 10 kV large urban distribution system which supplies industrial, commercial and residential customers. The influence of various parameters of the distribution network on the frequency characteristics are presented, in order to assess the interaction of harmonic distortion and distribution system network.

  18. Two port network analysis for three impedance based oscillators

    KAUST Repository

    Said, Lobna A.

    2011-12-01

    Two-port network representations are applied to analyze complex networks which can be dissolved into sub-networks connected in series, parallel or cascade. In this paper, the concept of two-port network has been studied for oscillators. Three impedance oscillator based on two port concept has been analyzed using different impedance structures. The effect of each structure on the oscillation condition and the frequency of oscillation have been introduced. Two different implementations using MOS and BJT have been introduced. © 2011 IEEE.

  19. [Chronic gastritis and intestinal metaplasia].

    Science.gov (United States)

    Castillo, T; Navarrete, J; Celestina, A

    1989-01-01

    Much has been written about gastric mucosae behavior and the occurrence of intestinal metaplasia. The aim of this paper is to learn something more about these matters in peruvian population. We selected 100 patients with endoscopically no localized lesions between 30 to 70 years of age. We took 8 samples of gastric mucosae in each patient which were carefully examined for the presence of inflammatory changes, settle the line type between antral and fundic mucosae and the frequency of intestinal metaplasia finding. The results showed disagreement between endoscopic and histological findings, so we conclude it is better to diagnose chronic gastritis on the basis of histological parameters. The line between antral and fundic mucosae was of the close type one found in 87% of all cases and it advanced proximally with increasing age. Intestinal metaplasia was present in 46% of the whole number of patients and the rate of occurrence increased in 50% over 50 years age. These findings will let us compare future investigations of gastric mucosae behavior with localized benign or malign lesions.

  20. Radiological manifestations of intestinal tuberculosis

    International Nuclear Information System (INIS)

    Im, Jae Hoon

    1974-01-01

    Radiological findings of 87 cases of intestinal tuberculosis are analyzed and presented. The diagnosis was based on histopathology in 29 cases, and on clinical ground and radiological findings in 58 cases. The radio of male and female patients was 4:6, and peak incidence is between 10 and 30. Abdominal pain, diarrhea, weight loss, fever and general weakness are frequent symptoms, and tenderness of abdomen, ascites with abdominal distension, malnutrition and emaciation are frequent signs of the patients. Laboratory investigation reveal anemia, raised ESR, hypoalbuminaemia and positive occult blood reaction in the stool in most of the patients. Chest film show activity pulmonary tuberculosis in only 1/3 patients. There is no pathognomonic radiological findings in intestinal tuberculosis and their manifestations are protean, and differentiation from other inflammatory diseases and malignant tumors in gastrointestinal tract is very difficult on radiological ground alone. However, in patients with complaining vague abdominal symptoms and signs, the radiological diagnosis is most certain means in the decision of existence of organic lesion and suggestion of tuberculosis in the gastrointestinal tract and its extent as yet. Multiplicity of the lesion, involvement of adjacent organ such as peritoneum or mesenteric lymph nodes, typical nodularity or irregularity of mesenteric border and existence of active pulmonary tuberculosis are the suggestive findings of intestinal tuberculosis. In the diagnosis of inflammatory disease or malignant tumor of gastrointestinal tract, the possibility of tuberculosis should be borne in mind, and vice versa

  1. [Intestinal parasitic diseases in children].

    Science.gov (United States)

    Mare, Anca; Man, A; Toma, Felicia; Székely, Edit; Lôrinczi, Lilla; Sipoş, Anca

    2007-01-01

    To compare the incidence of intestinal parasitosis between children with residence in urban and rural areas: to compare the efficacy of parasitologic diagnostic methods. In our study we included two lots of children. The first lot consisted in 74 children from rural areas from which we collected 44 samples of feces and 55 samples for the "Scotch tape" test. The second lot consisted in 214 children from urban areas from which we collected 44 samples of feces. We examined each sample of feces by three different methods. The study was performed between April to June 2006. The incidence of intestinal parasitosis increases in children from urban areas towards rural areas, and in children between 5 and 10 years. Ascariasis is the most frequent disease in both urban and rural areas. By examination of each fecal sample by three different methods, the number of positive cases increased. The residence in rural areas and age between 5 to 10 years are risk factors for intestinal parasitosis. The "Scotch tape" test was more efficient in Enterobius vermicularis infection than the methods performed from feces. We recommend using at the same time three diagnostic methods for feces examination to improve the diagnostic sensibility.

  2. Colon in acute intestinal infection.

    Science.gov (United States)

    Guarino, Alfredo; Buccigrossi, Vittoria; Armellino, Carla

    2009-04-01

    The colon is actively implicated in intestinal infections not only as a target of enteric pathogens and their products but also as a target organ for treatment. In the presence of diarrhea, both of osmotic and secretory nature, the colon reacts with homeostatic mechanisms to increase ion absorption. These mechanisms can be effectively exploited to decrease fluid discharge. A model of intestinal infections using rotavirus (RV) in colonic cells was set up and used to define a dual model of secretory and osmotic diarrhea in sequence. Using this model, antidiarrheal drugs were tested, namely zinc and the enkephalinase inhibitor racecadotril. Zinc was able to decrease the enterotoxic activity responsible for secretory diarrhea. It also inhibited the cytotoxic effect of RV. The mechanism of zinc was related at least in part to the activation of MAPK activity, but also a direct antiviral effect was observed. Racecadotril showed a potent and selective inhibition of active secretion, being particularly effective in the first phase of RV diarrhea. The use of drugs active at the colonic level, therefore, offers effective options to treat intestinal infections in childhood. In addition, the colon is the natural site of colonic microflora, a target of probiotic therapy, which is the first line of approach recommended by the European Society for Paediatric Gastroenterology, Hepatology and Nutrition to treat infectious diarrhea.

  3. Immunogenetic control of the intestinal microbiota.

    Science.gov (United States)

    Marietta, Eric; Rishi, Abdul; Taneja, Veena

    2015-07-01

    All vertebrates contain a diverse collection of commensal, symbiotic and pathogenic microorganisms, such as bacteria, viruses and fungi, on their various body surfaces, and the ecological community of these microorganisms is referred to as the microbiota. Mucosal sites, such as the intestine, harbour the majority of microorganisms, and the human intestine contains the largest community of commensal and symbiotic bacteria. This intestinal community of bacteria is diverse, and there is a significant variability among individuals with respect to the composition of the intestinal microbiome. Both genetic and environmental factors can influence the diversity and composition of the intestinal bacteria with the predominant environmental factor being diet. So far, studies have shown that diet-dependent differences in the composition of intestinal bacteria can be classified into three groups, called enterotypes. Other environmental factors that can influence the composition include antibiotics, probiotics, smoking and drugs. Studies of monozygotic and dizygotic twins have proven that genetics plays a role. Recently, MHC II genes have been associated with specific microbial compositions in human infants and transgenic mice that express different HLA alleles. There is a growing list of genes/molecules that are involved with the sensing and monitoring of the intestinal lumen by the intestinal immune system that, when genetically altered, will significantly alter the composition of the intestinal microflora. The focus of this review will be on the genetic factors that influence the composition of the intestinal microflora. © 2015 John Wiley & Sons Ltd.

  4. Immediate postconditioning during reperfusion attenuates intestinal injury.

    Science.gov (United States)

    Liu, Ke-Xuan; Li, Yun-Sheng; Huang, Wen-Qi; Chen, Shu-Qing; Wang, Zhong-Xin; Liu, Jia-Xin; Xia, Zhengyuan

    2009-05-01

    To test the hypothesis that immediate but not delayed ischemic postconditioning (IPo) during reperfusion attenuates intestinal injury, and that ischemic preconditioning (IPC) and IPo may confer synergy in intestinal protection. Prospective laboratory animal study with concurrent control. Adult Sprague-Dawley rats. Intestinal ischemia/reperfusion (II/R) injury in rats was produced by clamping superior mesenteric artery for 60 min followed by 60 min reperfusion; IPC was elicited by 10 min ischemia and 10 min reperfusion before index ischemia; IPo was performed by three cycles of 30 s reperfusion and 30 s ischemia initiated either immediately at the onset of reperfusion (IPo) or after reperfusion for 3 min (delayed-IPo). Combination of IPC and IPo was performed by combining both protocols. Intestinal ischemia/reperfusion resulted in significant intestinal injury evidenced as significant increase in Chiu's scores and wet-to-dry intestine weight ratio accompanied with increases in plasma levels of tumor necrosis factor-alpha and interleukin-6, as well as increases in the intestinal tissue lipid peroxidation product malonediadehyde and myeloperoxidase activity as compared to control animals (all P IPo or their combination (P IPo (P > 0.05). IPC and IPo showed synergistic protection compared with either protocol alone. Ischemic postconditioning reduces intestinal injury, in part, by inhibiting oxidative injury, neutrophils filtration and proinflammatory response. The early period of reperfusion is critical to intestinal protection by IPo, and intestinal protection with IPo can be enhanced by IPC.

  5. Intestinal microcirculatory dysfunction and neonatal necrotizing enterocolitis.

    Science.gov (United States)

    Zhang, Hong-yi; Wang, Fang; Feng, Jie-xiong

    2013-01-01

    Based on the observation that coagulation necrosis occurs in the majority of neonatal necrotizing enterocolitis (NEC) patients, it is clear that intestinal ischemia is a contributing factor to the pathogenesis of NEC. However, the published studies regarding the role of intestinal ischemia in NEC are controversial. The aim of this paper is to review the current studies regarding intestinal microcirculatory dysfunction and NEC, and try to elucidate the exact role of intestinal microcirculatory dysfunction in NEC. The studies cited in this review were mainly obtained from articles listed in Medline and PubMed. The search terms used were "intestinal microcirculatory dysfunction" and "neonatal necrotizing enterocolitis". Mainly original milestone articles and critical reviews written by major pioneer investigators in the field were selected. Immature regulatory control of mesentery circulation makes the neonatal intestinal microvasculature vulnerable. When neonates are subjected to stress, endothelial cell dysfunction occurs and results in vasoconstriction of arterioles, inflammatory cell infiltration and activation in venules, and endothelial barrier disruption in capillaries. The compromised vasculature increases circulation resistance and therefore decreases intestinal perfusion, and may eventually progress to intestinal necrosis. Intestinal ischemia plays an important role through the whole course of NEC. New therapeutic agents targeting intestinal ischemia, like HB-EGF, are promising therapeutic agents for the treatment of NEC.

  6. Ketogenesis contributes to intestinal cell differentiation.

    Science.gov (United States)

    Wang, Qingding; Zhou, Yuning; Rychahou, Piotr; Fan, Teresa W-M; Lane, Andrew N; Weiss, Heidi L; Evers, B Mark

    2017-03-01

    The intestinal epithelium undergoes a continual process of proliferation, differentiation and apoptosis. Previously, we have shown that the PI3K/Akt/mTOR pathway has a critical role in intestinal homeostasis. However, the downstream targets mediating the effects of mTOR in intestinal cells are not known. Here, we show that the ketone body β-hydroxybutyrate (βHB), an endogenous inhibitor of histone deacetylases (HDACs) induces intestinal cell differentiation as noted by the increased expression of differentiation markers (Mucin2 (MUC2), lysozyme, IAP, sucrase-isomaltase, KRT20, villin, Caudal-related homeobox transcription factor 2 (CDX2) and p21 Waf1 ). Conversely, knockdown of the ketogenic mitochondrial enzyme hydroxymethylglutaryl CoA synthase 2 (HMGCS2) attenuated spontaneous differentiation in the human colon cancer cell line Caco-2. Overexpression of HMGCS2, which we found is localized specifically in the more differentiated portions of the intestinal mucosa, increased the expression of CDX2, thus further suggesting the contributory role of HMGCS2 in intestinal differentiation. In addition, mice fed a ketogenic diet demonstrated increased differentiation of intestinal cells as noted by an increase in the enterocyte, goblet and Paneth cell lineages. Moreover, we showed that either knockdown of mTOR or inhibition of mTORC1 with rapamycin increases the expression of HMGCS2 in intestinal cells in vitro and in vivo, suggesting a possible cross-talk between mTOR and HMGCS2/βHB signaling in intestinal cells. In contrast, treatment of intestinal cells with βHB or feeding mice with a ketogenic diet inhibits mTOR signaling in intestinal cells. Together, we provide evidence showing that HMGCS2/βHB contributes to intestinal cell differentiation. Our results suggest that mTOR acts cooperatively with HMGCS2/βHB to maintain intestinal homeostasis.

  7. Assessment of distribution of ventilation by electrical impedance tomography in standing horses

    International Nuclear Information System (INIS)

    Ambrisko, T D; Schramel, J P; Moens, Y P S; Adler, A; Kutasi, O; Makra, Z

    2016-01-01

    The aim was to evaluate the feasibility of using electrical impedance tomography (EIT) in horses. Thoracic EIT was used in nine horses. Thoracic and abdominal circumference changes were also measured with respiratory ultrasound plethysmography (RUP). Data were recorded during baseline, rebreathing of CO 2 and sedation. Three breaths were selected for analysis from each recording. During baseline breathing, horses regularly took single large breaths (sighs), which were also analysed. Functional EIT images were created using standard deviations (SD) of pixel signals and correlation coefficients (R) of each pixel signal with a reference respiratory signal. Left-to-right ratio, centre-of-ventilation and global-inhomogeneity-index were calculated. RM-ANOVA and Bonferroni tests were used (P  <  0.05). Distribution of ventilation shifted towards right during sighs and towards dependent regions during sighs, rebreathing and sedation. Global-inhomogeneity-index did not change for SD but increased for R images during sedation. The sum of SDs for the respiratory EIT signals correlated well with thoracic (r 2   =  0.78) and abdominal (r 2   =  0.82) tidal circumferential changes. Inverse respiratory signals were identified on the images at sternal location and based on reviewing CT images, seemed to correspond to location of gas filled intestines. Application of EIT in standing non-sedated horses is feasible. EIT images may provide physiologically useful information even in situations, such as sighs, that cannot easily be tested by other methods. (paper)

  8. Transverse impedance measurement using response matrix fit method at APS

    International Nuclear Information System (INIS)

    Sajaev, V.

    2007-01-01

    The Advanced Photon Source (APS) is a third-generation synchrotron light source based on a 7-GeV electron storage ring. In third-generation light sources the synchrotron radiation is mainly produced in undulators. In order to achieve high photon flux and tunability, the magnet gap in undulators has to be as small as possible. Therefore, the undulators are installed on dedicated small-gap insertion device (ID) vacuum chambers. APS has thirty-five 5-m-long straight sections available for undulators. At the time of the measurements, there were 31 straight sections occupied with various insertion devices, and 4 straight sections were still empty. Most of the ID vacuum chambers have a 8-mm in-vacuum gap, and two chambers have a 5-mm gap. These narrow-gap vacuum chambers are believed to be the main source of the transverse impedance of the machine. One can measure the combined impedance by measuring the transverse tune slope with single-bunch current. Comparing this slope before and after installation of the narrow-gap vacuum chamber, one can deduce the impedance of the chamber. It is difficult to accurately measure the change in the tune slope after one or a few new ID chambers are installed. If several identical ID vacuum chambers are installed over a period of time, then one can estimate the contribution of one ID chamber. Over the last few years there have been a number of attempts to measure the impedance of separate components of accelerators. Phase-advance measurements from beam position monitor (BPM) turn-by-turn histories were used at LEP to measure the impedance distribution around the ring. Researches at LEP were able to fit average impedance in the long sections of the LEP arc and determine the impedance of the rf sections. The method was tried at APS; however, the accuracy of the measurements was not enough to determine the small impedance of a single ID vacuum chamber. There is also a different approach that uses local orbit bumps to probe different parts

  9. Virtual-Impedance-Based Control for Voltage-Source and Current-Source Converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Li, YunWei; Blaabjerg, Frede

    2015-01-01

    The virtual impedance concept is increasingly used for the control of power electronic systems. Generally, the virtual impedance loop can either be embedded as an additional degree of freedom for active stabilization and disturbance rejection, or be employed as a command reference generator....... Different virtual impedances and their implementation issues are then discussed. A number of practical examples are demonstrated to illustrate the feasibility of virtual impedances. Emerging applications and future trends of virtual impedances in power electronic systems conclude this paper....... for the converters to provide ancillary services. This paper presents an overview of the virtual-impedance-based control strategies for voltage-source and current-source converters. The control output impedance shaping attained by the virtual impedances is generalized first using the impedance-based models...

  10. Epidermal Growth Factor and Intestinal Barrier Function

    Directory of Open Access Journals (Sweden)

    Xiaopeng Tang

    2016-01-01

    Full Text Available Epidermal growth factor (EGF is a 53-amino acid peptide that plays an important role in regulating cell growth, survival, migration, apoptosis, proliferation, and differentiation. In addition, EGF has been established to be an effective intestinal regulator helping to protect intestinal barrier integrity, which was essential for the absorption of nutrients and health in humans and animals. Several researches have demonstrated that EGF via binding to the EGF receptor and subsequent activation of Ras/MAPK, PI3K/AKT, PLC-γ/PKC, and STATS signal pathways regulates intestinal barrier function. In this review, the relationship between epidermal growth factor and intestinal development and intestinal barrier is described, to provide a better understanding of the effects of EGF on intestine development and health.

  11. Intestinal epithelium in inflammatory bowel disease

    Directory of Open Access Journals (Sweden)

    Mehmet eCoskun

    2014-08-01

    Full Text Available The intestinal epithelium has a strategic position as a protective physical barrier to luminal microbiota and actively contributes to the mucosal immune system. This barrier is mainly formed by a monolayer of specialized intestinal epithelial cells (IECs that are crucial in maintaining intestinal homeostasis. Therefore, dysregulation within the epithelial layer can increase intestinal permeability, lead to abnormalities in interactions between IECs and immune cells in underlying lamina propria, and disturb the intestinal immune homeostasis, all of which are linked to the clinical disease course of inflammatory bowel disease (IBD. Understanding the role of the intestinal epithelium in IBD pathogenesis might contribute to an improved knowledge of the inflammatory processes and the identification of potential therapeutic targets.

  12. Cinnamon polyphenols regulate multiple metabolic pathways involved in intestinal lipid metabolism of primary small intestinal enterocytes

    Science.gov (United States)

    Increasing evidence suggests that dietary factors may affect the expression of multiple genes and signaling pathways including those that regulate intestinal lipoprotein metabolism. The small intestine is actively involved in the regulation of dietary lipid absorption, intracellular transport and me...

  13. Generalized Warburg impedance on realistic self-affine fractals ...

    Indian Academy of Sciences (India)

    Administrator

    Generalized Warburg impedance on realistic self-affine fractals: Comparative study of statistically corrugated and isotropic roughness. RAJESH KUMAR and RAMA KANT. Journal of Chemical Sciences, Vol. 121, No. 5, September 2009, pp. 579–588. 1. ( ) c. L. R ω on page 582, column 2, para 2, after eq (8) should read as ...

  14. Generalized Warburg impedance on realistic self-affine fractals ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... We analyse the problem of impedance for a diffusion controlled charge transfer process across an irregular interface. These interfacial irregularities are characterized as two class of random fractals: (i) a statistically isotropic self-affine fractals and (ii) a statistically corrugated self-affine fractals.

  15. High precision impedance spectroscopy: a strategy demonstrated on PZT

    NARCIS (Netherlands)

    Boukamp, Bernard A.; Blank, David H.A.

    2011-01-01

    Electrochemical impedance spectroscopy (EIS) has been recognized as a very powerful tool for studying charge and mass transport and transfer in a wide variety of electrically or electrochemically active systems. Sophisticated modeling programs make it possible to extract parameters from the

  16. Cultural Saga: Does Pakhtun Culture Impede Women Employment ...

    African Journals Online (AJOL)

    Cultural Saga: Does Pakhtun Culture Impede Women Employment? Humera Jamal, Mussawar Shah, Sidra Iqbal, Asad Ullah, Imran Imran. Abstract. Aim of this research article embodies the measurement of attitude of teaching faculty in Peshawar University to assess cultural impediments with reference to women ...

  17. Array of piezoelectric energy harvesting by the equivalent impedance approach

    International Nuclear Information System (INIS)

    Lien, I C; Shu, Y C

    2012-01-01

    This article proposes to use the idea of equivalent impedance to investigate the electrical response of an array of piezoelectric oscillators endowed with distinct energy harvesting circuits. Three interface electronics systems are considered including standard AC/DC and parallel/series-SSHI (synchronized switch harvesting on inductor) circuits. Various forms of equivalent load impedance are analytically obtained for different interfaces. The steady-state response of an array system is then shown to be determined by the matrix formulation of generalized Ohm’s law whose impedance matrix is explicitly expressed in terms of the load impedance. A model problem is proposed for evaluating the ability of power harvesting under various conditions. It is shown first that harvested power is increased dramatically for the case of small deviation in the system parameters. On the other hand, if the deviation in mass is relatively large, the result is changed from the power-boosting mode to wideband mode. In particular, the parallel-SSHI array system exhibits much more significant bandwidth improvement than the other two cases. Surprisingly, the series-SSHI array system shows the worst electrical response. Such an observation is opposed to our previous finding that an SSHI technique avails against the standard technique in the case based on a single piezoelectric energy harvester and the explanation is under investigation. (fast track communication)

  18. A note on the MUSIC algorithm for impedance tomography

    International Nuclear Information System (INIS)

    Hanke, Martin

    2017-01-01

    We investigate the MUSIC algorithm for the reconstruction of small (infinitesimal) inclusions inside a planar homogeneous object from discrete impedance tomography data within the framework of the gap electrode model. We provide a justification of the method whenever the number of electrodes exceeds 2( J   +  1) where J is the number of the inclusions to be found. (paper)

  19. Impedance model for quantum-mechanical barrier problems

    International Nuclear Information System (INIS)

    Nelin, Evgenii A

    2007-01-01

    Application of the impedance model to typical quantum-mechanical barrier problems, including those for structures with resonant electron tunneling, is discussed. The efficiency of the approach is illustrated. The physical transparency and compactness of the model and its potential as a teaching and learning tool are discussed. (methodological notes)

  20. Relationship between bioelectrical impedance-derived estimates of ...

    African Journals Online (AJOL)

    Measurements of basal metabolic rate (BMR) and body composition parameters represent an important tool for preventing obesity. This investigation examined the relationships between bioelectrical impedance-derived estimates of BMR and various body composition parameters, including age, body mass index, ...

  1. Effect of temperature on the AC impedance of protein and ...

    Indian Academy of Sciences (India)

    increased with temperature for all the biopolymers which corresponds to high polarization effect in these biopoly- mers. The AC impedance parameters for papain, gum aca- cia, gum tragacanth and gum guar are given for four different temperatures in table 1 for comparison. The conductivity of papain increases from 1·65× ...

  2. Improved techniques of impedance calculation and localization in particle accelerators

    CERN Document Server

    Biancacci, Nicolò; Migliorati, Mauro; Métral, Elias; Salvant, Benoit

    In this thesis we mainly focus on particle accelerators applied to high energy physics research where a fundamental parameter, the luminosity, is maximized in order to increase the rate of particle collisions useful to particle physicists. One way to increase this parameter is to increase the intensity of the circulating beams which is limited by the onset of collective effects that may drive the beam unstable and eventually provoke beam losses or reduce the beam quality required by the particle physics experiments. One major cause of collective effects is the beam coupling impedance, a quantity that quantifies the effect of the fields scattered by a beam passing through any accelerator device. The development of an impedance budget is required in those machines that are planning substantial upgrades as shown in this thesis for the CERN PS case. The main source of impedance in the CERN LHC are the collimators. Within an impedance reduction perspective, in order to reach the goals of the planned upgrades, it ...

  3. Generalized Warburg impedance on realistic self-affine fractals

    Indian Academy of Sciences (India)

    We analyse the problem of impedance for a diffusion controlled charge transfer process across an irregular interface. These interfacial irregularities are characterized as two class of random fractals: (i) a statistically isotropic self-affine fractals and (ii) a statistically corrugated self-affine fractals. The information about the ...

  4. Impedances of nickel electrodes cycled in various KOH concentrations

    Science.gov (United States)

    Reid, Margaret A.; Loyselle, Patricia L.

    1991-01-01

    Recent tests at Hughes have shown that Ni/H2 cells cycled in 26 percent KOH have much longer lives than those cycled in other concentrations. As part of an ongoing program to try to correlate the impedances of nickel electrodes with their life and performance, impedances were measured of a number of electrodes from these tests that had been cycled in concentrations from 21 to 36 percent KOH. These had ranged from about 1000 to 40,000 cycles. After cycling ten times to reduce possible changes due to storage, impedances were measured at five voltages corresponding to low states of charge. The results were analyzed using a standard circuit model including Warburg impedance term. Lower kinetic resistances and Warburg slopes were found for several electrodes which had been cycled in 26 percent KOH even though they had been cycled for a much longer time than the others. Interpretation of the data is complicated by the fact that the cycle lives, storage times, and failure mechanisms varied. Several other circuit models have also been examined, but the best correlations with life were found with parameters obtained from the simple model.

  5. Design methodology to enhance high impedance surfaces performances

    Directory of Open Access Journals (Sweden)

    M. Grelier

    2014-04-01

    Full Text Available A methodology is introduced for designing wideband, compact and ultra-thin high impedance surfaces (HIS. A parametric study is carried out to examine the effect of the periodicity on the electromagnetic properties of an HIS. This approach allows designers to reach the best trade-off for HIS performances.

  6. Grid impedance estimation via excitation of LCL-filter resonance

    DEFF Research Database (Denmark)

    Liserre, M.; Blaabjerg, Frede; Teodorescu, Remus

    2007-01-01

    Inverters adopted in distributed power generation, active filter, and uninterruptible power supply are often connected to the grid through an inductance-capacitor-inductance (LCL) filter. The impedance of the LCL filter has a typical frequency characteristic with a resonance peak. Hence, the LCL...

  7. Longitudinal impedance of LHC version-1 stripline beam position monitor

    CERN Document Server

    Vos, L

    1997-01-01

    The electrodes in the first version of the LHC beam position monitor are 50 \\W striplines. An enlarged aperture is required to keep the inner face of the electrodes in the shadow of the mechanical aperture of the machine. The longitudinal impedance of this device consists of two distinct components, one from the cavity and the other from the electrodes. The cavity part of the impedance can be reduced by inter-electrode shields as proposed by G. Lambertson. A complementary way of reducing this part of the impedance is to use tapered edges. The cavity wake potential of the beam position monitor is computed both with the 3D code MAFIA and analytically for a very short bunch (20 mm) and for a normal high energy LHC bunch (75 mm). The computation is done separately for the inter-electrode shields and for the tapered ends. The agreement between the two methods is very good, hence it can be concluded that the cavity impedance of the monitor cavity is well known up to the cut-off frequency of the LHC pipe (5.1 GHz). ...

  8. A modified impedance control for physical interaction of UAVs

    NARCIS (Netherlands)

    Fumagalli, Matteo; Carloni, Raffaella

    2013-01-01

    This paper proposes a modified impedance control strategy for a generic robotic system that can interact with an unknown environment or can be moved by a human. The controller makes use of a virtual mass, coupled to the robotic system, which allows for stable interaction. The focus is mainly on

  9. Electrical impedance of layered atherosclerotic plaques on human aortas

    NARCIS (Netherlands)

    C.J. Slager (Cornelis); A.C. Phaff; C.E. Essed; N. Bom (Klaas); J.C.H. Schuurbiers (Johan); P.W.J.C. Serruys (Patrick)

    1992-01-01

    textabstractElectrical impedance measurements were performed on 13 atherosclerotic human aortic segments at 67 measuring spots in order to determine whether or not on the basis of these data a distinction can be made between atherosclerotic lesions and normal tissue. Stenosis localization and

  10. Effect of Zr on dielectric, ferroelectric and impedance properties of ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. A polycrystalline sample of Zr-doped barium titanate (BaTiO3) was prepared by conventional solid state reaction method. The effect of Zr (0⋅15) on the structural and microstructural properties of BaTiO3 was investigated by XRD and SEM. The electrical properties (dielectric, ferroelectric and impedance spectro-.

  11. Does strategic planning enhance or impede innovation and firm performance?

    NARCIS (Netherlands)

    Song, Michael; Im, Subin; van der Bij, Hans; Song, Lisa Z.

    Does strategic planning enhance or impede innovation and firm performance? The current literature provides contradictory views. This study extends the resource-advantage theory to examine the conditions in which strategic planning increases or decreases the number of new product development projects

  12. Impedance spectroscopy studies of surface engineered TiO2 ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Dielectric analysis of nanometre range size ceramic particles like TiO2 is very important in the understanding of the performance and design of their polymer nanocomposites for energy storage and other applications. In recent times, impedance spectroscopy is shown to be a very powerful tool to investigate the.

  13. Wideband impedance measurements of DC motors under dynamic load conditions

    NARCIS (Netherlands)

    Diouf, F.; Buesink, Frederik Johannes Karel; Leferink, Frank Bernardus Johannes; Duval, Fabrice; Bensetti, Mohamed

    2013-01-01

    One of the principal conducted EMI(electromagnetic interferences) sources of low voltage DC (direct current) motors is the commutation occurring during rotation. In this paper the small-signal impedance of low voltage DC motors under different functioning modes, including the dynamic one is studied

  14. Electrochemical Impedance Modeling of a Solid Oxide Fuel Cell Anode

    DEFF Research Database (Denmark)

    Mohammadi, R.; Søgaard, Martin; Ramos, Tania

    2014-01-01

    A simulation package for the impedance response of SOFC anodes is presented here. The model couples the gas transport in gas channels and within a porous electrode with the electrochemical kinetics. The gas phase mass transport is modeled using mass conservation equations. A transmission line mod...

  15. Impedance spectroscopy studies of surface engineered TiO 2 ...

    Indian Academy of Sciences (India)

    Dielectric analysis of nanometre range size ceramic particles like TiO2 is very important in the understanding of the performance and design of their polymer nanocomposites for energy storage and other applications. In recent times, impedance spectroscopy is shown to be a very powerful tool to investigate the dielectric ...

  16. Impedance characterization of PV modules in outdoor conditions

    DEFF Research Database (Denmark)

    Oprea, Matei-lon; Thorsteinsson, Sune; Spataru, Sergiu

    2016-01-01

    Impedance spectroscopy (IS) has been used for laboratory characterizations of photovoltaic (PV) technologies under well controlled conditions. This work applies IS for outdoor characterization of PV panels, in order to observe the effect of irradiance (G) and temperature (T) on the PV module...

  17. Identification of Critical Transmission Limits in Injection Impedance Plane

    DEFF Research Database (Denmark)

    Jóhannsson, Hjörtur; Østergaard, Jacob; Nielsen, Arne Hejde

    2012-01-01

    the partial derivatives of the variables P,Q and V in respect to each other become zero. In addition to the mappingof the critical lines, some characteristic lines are mapped as well. These include the mapping of the lines of constant P,Q,Vand d from the PQV-surface into the impedance plane. All of the mapped...

  18. Effect of Zr on dielectric, ferroelectric and impedance properties of ...

    Indian Academy of Sciences (India)

    A polycrystalline sample of Zr-doped barium titanate (BaTiO3) was prepared by conventional solid state reaction method. The effect of Zr (0.15) on the structural and microstructural properties of BaTiO3 was investigated by XRD and SEM. The electrical properties (dielectric, ferroelectric and impedance spectroscopy) were ...

  19. Different radiation impedance models for finite porous materials

    DEFF Research Database (Denmark)

    Nolan, Melanie; Jeong, Cheol-Ho; Brunskog, Jonas

    2015-01-01

    The Sabine absorption coefficients of finite absorbers are measured in a reverberation chamber according to the international standard ISO 354. They vary with the specimen size essentially due to diffraction at the specimen edges, which can be seen as the radiation impedance differing from the in...

  20. Analysis of the willow root system by electrical impedance spectroscopy.

    Science.gov (United States)

    Cao, Yang; Repo, Tapani; Silvennoinen, Raimo; Lehto, Tarja; Pelkonen, Paavo

    2011-01-01

    Information on plant roots is increasingly needed for understanding and managing plants under various environmental conditions, including climate change. Several methods have been developed to study fine roots but they are either destructive or cumbersome, or may not be suitable for studies of fine root functionality. Electrical impedance, resistance, and capacitance have been proposed as possible non-destructive measures for studying roots. Their use is limited by a lack of knowledge concerning the electrical circuit of the system. Electrical impedance spectroscopy (EIS) was used for hydroponically raised willows (Salix schwerinii) to estimate the root system size. The impedance spectra were investigated in three experimental set-ups and the corresponding appropriate lumped models were formulated. The fit of the proposed lumped models with the measured impedance spectra data was good. The model parameters were correlated with the contact area of the roots and/or stems raised in the hydroponic solution. The EIS method proved a useful non-destructive method for assessing root surface area. This work may be considered to be a new methodological contribution to understanding root systems and their functions in a non-destructive manner.

  1. Pelvic bioelectrical impedance measurements to detect rectal filling.

    Science.gov (United States)

    Ratani, R S; Yazaki, E; Maw, A; Pilot, M A; Rogers, J; Williams, N S

    1998-11-01

    Anorectal sensory deficits are an important cause of defecatory disorders and are also a reason for evacuatory difficulties in patients undergoing total anorectal reconstruction. A method to detect rectal filling would be beneficial in such patients. We have investigated the feasibility of detecting rectal filling in vitro and in vivo by measuring changes in pelvic impedance. In vitro, a model of the pelvis was constructed using a cylindrical plastic tank filled with an electrolyte solution (conductivity 3 mS cm(-1)). Conductive Visking tubing representing the rectum was suspended in the tank and incrementally filled with artificial faeces. An impedance meter detected changes in voltage on rectal filling when an alternating current of 2 mA was passed at eight frequencies (4.8 to 612 kHz). In vivo, changes in pelvic bioelectrical impedance upon retrograde and antegrade rectal filling with artificial faeces were evaluated in three pigs, four electrodes being implanted in the pelvis. Impedance measurements accurately detected 'rectal' volume changes in vitro (n = 10, p < 0.0001; Kruskal Wallis), but not in vivo (n = 68, p = 0.48; Kruskal Wallis). This was probably due to extreme sensitivity of the detecting device to movement, a problem that needs to be resolved before this technique could be used in man.

  2. The bioelectrical impedance vector migration in healthy infants

    NARCIS (Netherlands)

    L'Abee, Carianne; Poorts-Borger, Petra H.; Gorter, Erna H. G. M.; Piccoli, Antonio; Stolk, Ronald P.; Sauer, Pieter J. J.

    Background & aims: Detecting young children with high amount of body fat is important to intervene in the development of obesity. The aim of this study is to gain inside in the bioelectrical impedance vector analysis in healthy infants. Methods: Repeated measurements of whole body reactance and

  3. Assessing human brain impedance using simultaneous surface and intracerebral recordings.

    Science.gov (United States)

    Ranta, Radu; Le Cam, Steven; Tyvaert, Louise; Louis-Dorr, Valérie

    2017-02-20

    Most of the literature on the brain impedance proposes a frequency-independent resistive model. Recently, this conclusion was tackled by a series of papers (Bédard et al., 2006; Bédard and Destexhe, 2009; Gomes et al., 2016), based on microscopic sale modeling and measurements. Our paper aims to investigate the impedance issue using simultaneous in vivo depth and surface signals recorded during intracerebral electrical stimulation of epileptic patients, involving a priori different tissues with different impedances. Our results confirm the conclusions from Logothethis et al. (2007): there is no evidence of frequency dependence of the brain tissue impedance (more precisely, there is no difference, in terms of frequency filtering, between the brain and the skull bone), at least at a macroscopic scale. In order to conciliate findings from both microscopic and macroscopic scales, we recall different neural/synaptic current generators' models from the literature and we propose an original computational model, based on fractional dynamics. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  4. Contactless Impedance Sensors and Their Application to Flow Measurements

    Directory of Open Access Journals (Sweden)

    Karel Štulík

    2013-02-01

    Full Text Available The paper provides a critical discussion of the present state of the theory of high-frequency impedance sensors (now mostly called contactless impedance or conductivity sensors, the principal approaches employed in designing impedance flow-through cells and their operational parameters. In addition to characterization of traditional types of impedance sensors, the article is concerned with the use of less common sensors, such as cells with wire electrodes or planar cells. There is a detailed discussion of the effect of the individual operational parameters (width and shape of the electrodes, detection gap, frequency and amplitude of the input signal on the response of the detector. The most important problems to be resolved in coupling these devices with flow-through measurements in the liquid phase are also discussed. Examples are given of cell designs for continuous flow and flow-injection analyses and of detection systems for miniaturized liquid chromatography and capillary electrophoresis. New directions for the use of these sensors in molecular biology and chemical reactors and some directions for future development are outlined.

  5. Impedance-based monitoring for tissue engineering applications

    DEFF Research Database (Denmark)

    Canali, Chiara; Heiskanen, Arto; Martinsen, Ø.G.

    2015-01-01

    Impedance is a promising technique for sensing the overall process of tissue engineering. Different electrode configurations can be used to characterize the scaffold that supports cell organization in terms of hydrogel polymerization and degree of porosity, monitoring cell loading, cell prolifera...

  6. Effect of Intravenous Infusion Solutions on Bioelectrical Impedance Spectroscopy.

    Science.gov (United States)

    Yap, Jason; Rafii, Mahroukh; Azcue, Maria; Pencharz, Paul

    2017-05-01

    Bioelectrical impedance (BIA) is often used to measure body fluid spaces and thereby body composition. However, in acute animal studies, we found that impedance was driven by the saline content of intravenous (IV) fluids and not by the volume. The aim of the study was to investigate the effect of 3 different fluids acutely administered on the change in impedance, specifically resistance (R). Nine healthy adults participated in 3 treatment (0.9% saline, 5% dextrose, and a mixture of 0.3% saline + 3.3% dextrose) experiments on nonconsecutive days. They all received 1 L of one of the treatments intravenously over a 1-hour period. Repeated BIA measurements were performed prior to IV infusion and then every 5 minutes for the 1-hour infusion period, plus 3 more measurements up to 15 minutes after the completion of the infusion. The change in R in the 0.9% saline infusion experiment was significantly lower than that of the glucose and mixture treatment ( P Bioelectrical impedance spectroscopy and BIA measure salt rather than the volume changes over the infusion period. Hence, in patients receiving IV fluids, BIA of any kind (single frequency or multifrequency) cannot be used to measure body fluid spaces or body composition.

  7. Investigation of the beam impedance of a slowly varying waveguide

    International Nuclear Information System (INIS)

    Jones, R.M.; Heifets, S.A.

    1995-05-01

    A perturbation method is used to obtain analytic expressions for the multipole longitudinal and universe beam impedance for an arbitrary waveguide whose radius is slowly varying and for the specific case of a symmetric small-angle taper. This method is also applicable for a particle in a wiggler undergoing periodic motion

  8. Organic electrochemical transistors for cell-based impedance sensing

    Energy Technology Data Exchange (ETDEWEB)

    Rivnay, Jonathan, E-mail: rivnay@emse.fr, E-mail: owens@emse.fr; Ramuz, Marc; Hama, Adel; Huerta, Miriam; Owens, Roisin M., E-mail: rivnay@emse.fr, E-mail: owens@emse.fr [Department of Bioelectronics, Ecole des Mines de St. Etienne, 13541 Gardanne (France); Leleux, Pierre [Department of Bioelectronics, Ecole des Mines de St. Etienne, 13541 Gardanne (France); Microvitae Technologies, Pole d' Activite Y. Morandat, 13120 Gardanne (France)

    2015-01-26

    Electrical impedance sensing of biological systems, especially cultured epithelial cell layers, is now a common technique to monitor cell motion, morphology, and cell layer/tissue integrity for high throughput toxicology screening. Existing methods to measure electrical impedance most often rely on a two electrode configuration, where low frequency signals are challenging to obtain for small devices and for tissues with high resistance, due to low current. Organic electrochemical transistors (OECTs) are conducting polymer-based devices, which have been shown to efficiently transduce and amplify low-level ionic fluxes in biological systems into electronic output signals. In this work, we combine OECT-based drain current measurements with simultaneous measurement of more traditional impedance sensing using the gate current to produce complex impedance traces, which show low error at both low and high frequencies. We apply this technique in vitro to a model epithelial tissue layer and show that the data can be fit to an equivalent circuit model yielding trans-epithelial resistance and cell layer capacitance values in agreement with literature. Importantly, the combined measurement allows for low biases across the cell layer, while still maintaining good broadband signal.

  9. Modified impedance source inverter for power conditioning system

    Indian Academy of Sciences (India)

    DC link voltage boost, reduced total harmonic distortion of output current and voltage, better voltage gain and wide range of output voltage controlcan be achieved easily with improved power quality. Experimental set-up of the modified impedance source inverter with Field Programmable Gate Array (FPGA) controller has ...

  10. Electrochemical Impedance Study of Reduction Kinetics of the Pesticide Vinclozoline

    Czech Academy of Sciences Publication Activity Database

    Pospíšil, Lubomír; Sokolová, Romana; Colombini, M. P.; Giannarelli, S.; Fuoco, R.

    2000-01-01

    Roč. 67, - (2000), s. 305-312 ISSN 0026-265X R&D Projects: GA MŠk OC D15.10; GA ČR GA203/97/1048 Institutional research plan: CEZ:AV0Z4040901 Keywords : electrochemical impedance * pesticide s * vinclozoline Subject RIV: CG - Electrochemistry Impact factor: 0.884, year: 2000

  11. Measurement of Phase Dependent Impedance for 3-phase Diode Rectifier

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth

    2016-01-01

    This paper presents a new method to measure the phase dependent impedance from an experimental set up. Though most of power electronics based system is gradually migrating to IGBT based voltage source converter due to their controllability, the rectifier composed of diode or thyristor components...

  12. BIOELECTRICAL IMPEDANCE VECTOR ANALYSIS IDENTIFIES SARCOPENIA IN NURSING HOME RESIDENTS

    Science.gov (United States)

    Loss of muscle mass and water shifts between body compartments are contributing factors to frailty in the elderly. The body composition changes are especially pronounced in institutionalized elderly. We investigated the ability of single-frequency bioelectrical impedance analysis (BIA) to identify b...

  13. AC impedance and dielectric spectroscopic studies of Mg ion ...

    Indian Academy of Sciences (India)

    Mater. Sci., Vol. 34, No. 5, August 2011, pp. 1063–1067. c Indian Academy of Sciences. AC impedance and dielectric spectroscopic studies of Mg. 2+ ion conducting PVA–PEG blended polymer electrolytes. ANJI REDDY POLU. ∗ and RANVEER KUMAR. Department of Physics, Dr H S Gour University, Sagar 470 003, India.

  14. Blocky inversion of multichannel elastic impedance for elastic parameters

    Science.gov (United States)

    Mozayan, Davoud Karami; Gholami, Ali; Siahkoohi, Hamid Reza

    2018-04-01

    Petrophysical description of reservoirs requires proper knowledge of elastic parameters like P- and S-wave velocities (Vp and Vs) and density (ρ), which can be retrieved from pre-stack seismic data using the concept of elastic impedance (EI). We propose an inversion algorithm which recovers elastic parameters from pre-stack seismic data in two sequential steps. In the first step, using the multichannel blind seismic inversion method (exploited recently for recovering acoustic impedance from post-stack seismic data), high-resolution blocky EI models are obtained directly from partial angle-stacks. Using an efficient total-variation (TV) regularization, each angle-stack is inverted independently in a multichannel form without prior knowledge of the corresponding wavelet. The second step involves inversion of the resulting EI models for elastic parameters. Mathematically, under some assumptions, the EI's are linearly described by the elastic parameters in the logarithm domain. Thus a linear weighted least squares inversion is employed to perform this step. Accuracy of the concept of elastic impedance in predicting reflection coefficients at low and high angles of incidence is compared with that of exact Zoeppritz elastic impedance and the role of low frequency content in the problem is discussed. The performance of the proposed inversion method is tested using synthetic 2D data sets obtained from the Marmousi model and also 2D field data sets. The results confirm the efficiency and accuracy of the proposed method for inversion of pre-stack seismic data.

  15. Grid impedance detection via excitation of LCL-filter resonance

    DEFF Research Database (Denmark)

    Liserre, Marco; Blaabjerg, Frede; Teodorescu, Remus

    2005-01-01

    the resonance of the LCL-fiIter can be also excited in a controlled way in order to individuate the resonance frequency in the spectrum (using for example the FFn. This paper proposes to use a controlled excitation to measure the grid impedance, since this one influences also the resonance frequency. This paper...

  16. Impedance and instability threshold estimates in the main injector I

    Energy Technology Data Exchange (ETDEWEB)

    Martens, M.A.; Ng, K.Y.

    1994-03-01

    One of the important considerations in the design of the Main Injector is the beam coupling impedances in the vacuum chamber and the stability of the beam. Along with the higher intensities comes the possibility of instabilities which lead to growth in beam emittances and/or the loss of beam. This paper makes estimations of the various impedances and instability thresholds based on impedance estimations and measurements. Notably missing from this paper is any analysis of transition crossing and its potential limitations on beam intensity and beam emittance. Future work should consider this issue. The body of the work contains detailed analysis of the various impedance estimations and instability threshold calculations. The calculations are based on the Main Injector beam intensity of 6 x 10{sup 10} protons per bunch, 95% normalized transverse emittances of 20{pi} mm-mrad, and 95% normalized longitudinal emittance of 0.1 eV-s at 8.9 GeV injection energy and 0.25 eV-s at 150 GeV flattop energy. The conclusions section summarizes the results in the paper and is meant to be readable by itself without referring to the rest of the paper. Also in the conclusion section are recommendations for future investigations.

  17. Multivariable Dynamic Ankle Mechanical Impedance With Active Muscles

    Science.gov (United States)

    Lee, Hyunglae; Krebs, Hermano Igo; Hogan, Neville

    2015-01-01

    Multivariable dynamic ankle mechanical impedance in two coupled degrees-of-freedom (DOFs) was quantified when muscles were active. Measurements were performed at five different target activation levels of tibialis anterior and soleus, from 10% to 30% of maximum voluntary contraction (MVC) with increments of 5% MVC. Interestingly, several ankle behaviors characterized in our previous study of the relaxed ankle were observed with muscles active: ankle mechanical impedance in joint coordinates showed responses largely consistent with a second-order system consisting of inertia, viscosity, and stiffness; stiffness was greater in the sagittal plane than in the frontal plane at all activation conditions for all subjects; and the coupling between dorsiflexion–plantarflexion and inversion–eversion was small—the two DOF measurements were well explained by a strictly diagonal impedance matrix. In general, ankle stiffness increased linearly with muscle activation in all directions in the 2-D space formed by the sagittal and frontal planes, but more in the sagittal than in the frontal plane, resulting in an accentuated “peanut shape.” This characterization of young healthy subjects’ ankle mechanical impedance with active muscles will serve as a baseline to investigate pathophysiological ankle behaviors of biomechanically and/or neurologically impaired patients. PMID:25203497

  18. Monitoring of yeast cell concentration using a micromachined impedance sensor

    NARCIS (Netherlands)

    Krommenhoek, E.E.; Gardeniers, Johannes G.E.; Bomer, Johan G.; van den Berg, Albert; Li, X.; Ottens, M.; van der Wielen, L.A.M.; van Dedem, G.W.K.; van Leeuwen, M.; van Gulik, W.M.; Heijnen, J.J.

    2005-01-01

    The paper describes the design, modelling and experimental characterization of a micromachined impedance sensor for on-line monitoring of the viable yeast cell concentration (biomass) in a miniaturized cell assay. Measurements in a Saccharomyces cerevisiae cell culture show that the permittivity of

  19. Impedance Measurements on the LHC Dump Kicker Prototype

    CERN Document Server

    González, C; Dyachkov, M

    1998-01-01

    In this paper we demonstrate that a thin layer of metallization on the inner surface of the ceramic pipe in an abort kicker will provide an effective way to screen the kicker's magnets from the electr omagnetic fields generated by the LHC bunches. The other objective of this paper was to measure the kicker impedance in a wide frequency range (up to 1 GHz).

  20. Estimation of surface impedance using different types of microphone arrays

    DEFF Research Database (Denmark)

    Richard, Antoine Philippe André; Fernandez Grande, Efren; Brunskog, Jonas

    2017-01-01

    , the performances of a rigid spherical array and a double layer planar array are examined. The use of sparse array processing methods and conventional regulariation approaches are studied. In addition, the influence of the size of the sample on the surface impedance estimation is investigated using both...

  1. Ground Loop Impedance of Long EHV Cable Lines

    DEFF Research Database (Denmark)

    Ohno, Teruo; Bak, Claus Leth; Sørensen, Thomas K.

    2012-01-01

    in literature. Through the calculation of the ground loop impedance for cable lines, it has been found that, for long EHV cable lines, the reliable operation of the ground distance relay is possible with a typical relay setting. Effects of parameters, such as substation grounding, cable layouts...

  2. Impedance Characteristics Modeling of a Two-Terminal Active Capacitor

    DEFF Research Database (Denmark)

    Wang, Haoran; Wang, Huai; Lu, Minghui

    2017-01-01

    to overcome the above issues. In this paper, the modeling of the active capacitor is investigated and a voltage feed-forward compensation scheme is proposed for overshoot reduction. Therefore, the impedance, equivalent capacitance, ESR, and ESL, of the active capacitor can be specified. A case study based...

  3. Does strategic planning enhance or impede innovation and firm performance

    NARCIS (Netherlands)

    Song, Michael; Im, Subin; van der Bijl, H.M.; Song, Lisa Z.

    2011-01-01

    Does strategic planning enhance or impede innovation and firm performance? The current literature provides contradictory views. This study extends the resource-advantage theory to examine the conditions in which strategic planning increases or decreases the number of new product development projects

  4. The effect of gastric inhibitory polypeptide on intestinal glucose absorption and intestinal motility in mice

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Eiichi [Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University (Japan); Hosokawa, Masaya [Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University (Japan); Faculty of Human Sciences, Tezukayama Gakuin University, Osaka (Japan); Harada, Norio; Yamane, Shunsuke; Hamasaki, Akihiro; Toyoda, Kentaro; Fujimoto, Shimpei; Fujita, Yoshihito; Fukuda, Kazuhito [Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University (Japan); Tsukiyama, Katsushi; Yamada, Yuichiro [Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University (Japan); Department of Internal Medicine, Division of Endocrinology, Diabetes and Geriatric Medicine, Akita University School of Medicine, Akita (Japan); Seino, Yutaka [Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University (Japan); Kansai Electric Power Hospital, Osaka (Japan); Inagaki, Nobuya, E-mail: inagaki@metab.kuhp.kyoto-u.ac.jp [Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University (Japan); CREST of Japan Science and Technology Cooperation (JST), Kyoto (Japan)

    2011-01-07

    Research highlights: {yields} Exogenous GIP inhibits intestinal motility through a somatostatin-mediated pathway. {yields} Exogenous GIP inhibits intestinal glucose absorption by reducing intestinal motility. {yields} The GIP-receptor-mediated action in intestine does not involve in GLP-1-mediated pathway. -- Abstract: Gastric inhibitory polypeptide (GIP) is released from the small intestine upon meal ingestion and increases insulin secretion from pancreatic {beta} cells. Although the GIP receptor is known to be expressed in small intestine, the effects of GIP in small intestine are not fully understood. This study was designed to clarify the effect of GIP on intestinal glucose absorption and intestinal motility. Intestinal glucose absorption in vivo was measured by single-pass perfusion method. Incorporation of [{sup 14}C]-glucose into everted jejunal rings in vitro was used to evaluate the effect of GIP on sodium-glucose co-transporter (SGLT). Motility of small intestine was measured by intestinal transit after oral administration of a non-absorbed marker. Intraperitoneal administration of GIP inhibited glucose absorption in wild-type mice in a concentration-dependent manner, showing maximum decrease at the dosage of 50 nmol/kg body weight. In glucagon-like-peptide-1 (GLP-1) receptor-deficient mice, GIP inhibited glucose absorption as in wild-type mice. In vitro examination of [{sup 14}C]-glucose uptake revealed that 100 nM GIP did not change SGLT-dependent glucose uptake in wild-type mice. After intraperitoneal administration of GIP (50 nmol/kg body weight), small intestinal transit was inhibited to 40% in both wild-type and GLP-1 receptor-deficient mice. Furthermore, a somatostatin receptor antagonist, cyclosomatostatin, reduced the inhibitory effect of GIP on both intestinal transit and glucose absorption in wild-type mice. These results demonstrate that exogenous GIP inhibits intestinal glucose absorption by reducing intestinal motility through a somatostatin

  5. The effect of gastric inhibitory polypeptide on intestinal glucose absorption and intestinal motility in mice

    International Nuclear Information System (INIS)

    Ogawa, Eiichi; Hosokawa, Masaya; Harada, Norio; Yamane, Shunsuke; Hamasaki, Akihiro; Toyoda, Kentaro; Fujimoto, Shimpei; Fujita, Yoshihito; Fukuda, Kazuhito; Tsukiyama, Katsushi; Yamada, Yuichiro; Seino, Yutaka; Inagaki, Nobuya

    2011-01-01

    Research highlights: → Exogenous GIP inhibits intestinal motility through a somatostatin-mediated pathway. → Exogenous GIP inhibits intestinal glucose absorption by reducing intestinal motility. → The GIP-receptor-mediated action in intestine does not involve in GLP-1-mediated pathway. -- Abstract: Gastric inhibitory polypeptide (GIP) is released from the small intestine upon meal ingestion and increases insulin secretion from pancreatic β cells. Although the GIP receptor is known to be expressed in small intestine, the effects of GIP in small intestine are not fully understood. This study was designed to clarify the effect of GIP on intestinal glucose absorption and intestinal motility. Intestinal glucose absorption in vivo was measured by single-pass perfusion method. Incorporation of [ 14 C]-glucose into everted jejunal rings in vitro was used to evaluate the effect of GIP on sodium-glucose co-transporter (SGLT). Motility of small intestine was measured by intestinal transit after oral administration of a non-absorbed marker. Intraperitoneal administration of GIP inhibited glucose absorption in wild-type mice in a concentration-dependent manner, showing maximum decrease at the dosage of 50 nmol/kg body weight. In glucagon-like-peptide-1 (GLP-1) receptor-deficient mice, GIP inhibited glucose absorption as in wild-type mice. In vitro examination of [ 14 C]-glucose uptake revealed that 100 nM GIP did not change SGLT-dependent glucose uptake in wild-type mice. After intraperitoneal administration of GIP (50 nmol/kg body weight), small intestinal transit was inhibited to 40% in both wild-type and GLP-1 receptor-deficient mice. Furthermore, a somatostatin receptor antagonist, cyclosomatostatin, reduced the inhibitory effect of GIP on both intestinal transit and glucose absorption in wild-type mice. These results demonstrate that exogenous GIP inhibits intestinal glucose absorption by reducing intestinal motility through a somatostatin-mediated pathway rather

  6. Differentiated thyroid carcinoma and intestinal polyposis syndromes.

    Science.gov (United States)

    Triggiani, Vincenzo; Angelo Giagulli, Vito; Tafaro, Angela; Resta, Francesco; Sabba, Carlo; Licchelli, Brunella; Guastamacchia, Edoardo

    2012-12-01

    Familial Adenomatous Polyposis, Cowden's Syndrome, and Peutz-Jeghers Syndrome are well known as Intestinal Polyposis Syndromes, inherited conditions characterized by the development of polyps of the gastro-intestinal tract in association with extra-intestinal manifestations, in particular malignant tumors at different sites. Thyroid carcinoma is sometimes a part of the clinical picture of these syndromes. The aim of this paper is to review the literature dealing with the association between differentiated thyroid carcinomas and Intestinal Polyposis Syndromes in order to point out peculiar aspects, providing suggestions for the screening and the management of thyroid tumors in these patients.

  7. Sonographic diagnosis of intestinal polyps in children.

    Science.gov (United States)

    Parra, Dimitri A; Navarro, Oscar M

    2008-06-01

    Although colonoscopy is the modality of choice for the diagnosis of intestinal polyps, sonography may be the first diagnostic modality in the evaluation of children with this pathology. Graded compression sonography of the small and large bowel may be useful in diagnosing intestinal polyps. A specific diagnosis is possible in many cases as most polyps have a characteristic appearance. Although sonography is not intended to replace endoscopy in the diagnostic work-up of intestinal polyps, it is important for radiologists to be aware of this appearance as they can be the first in making the diagnosis of intestinal polyps using sonography.

  8. Intestinal absorption of fluorescently labeled nanoparticles.

    Science.gov (United States)

    Simovic, Spomenka; Song, Yunmei; Nann, Thomas; Desai, Tejal A

    2015-07-01

    Characterization of intestinal absorption of nanoparticles is critical in the design of noninvasive anticancer, protein-based, and gene nanoparticle-based therapeutics. Here we demonstrate a general approach for the characterization of the intestinal absorption of nanoparticles and for understanding the mechanisms active in their processing within healthy intestinal cells. It is generally accepted that the cellular processing represents a major drawback of current nanoparticle-based therapeutic systems. In particular, endolysosomal trafficking causes degradation of therapeutic molecules such as proteins, lipids, acid-sensitive anticancer drugs, and genes. To date, investigations into nanoparticle processing within intestinal cells have studied mass transport through Caco-2 cells or everted rat intestinal sac models. We developed an approach to visualize directly the mechanisms of nanoparticle processing within intestinal tissue. These results clearly identify a mechanism by which healthy intestinal cells process nanoparticles and point to the possible use of this approach in the design of noninvasive nanoparticle-based therapies. Advances in nanomedicine have resulted in the development of new therapies for various diseases. Intestinal route of administration remains the easiest and most natural. The authors here designed experiments to explore and characterize the process of nanoparticle transport across the intestinal tissue. In so doing, further insights were gained for future drug design. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Bile acids in regulation of intestinal physiology.

    LENUS (Irish Health Repository)

    Keating, Niamh

    2009-10-01

    In addition to their roles in facilitating lipid digestion and absorption, bile acids are recognized as important regulators of intestinal function. Exposure to bile acids can dramatically influence intestinal transport and barrier properties; in recent years, they have also become appreciated as important factors in regulating cell growth and survival. Indeed, few cells reside within the intestinal mucosa that are not altered to some degree by exposure to bile acids. The past decade saw great advances in the knowledge of how bile acids exert their actions at the cellular and molecular levels. In this review, we summarize the current understanding of the role of bile acids in regulation of intestinal physiology.

  10. Intestinal myiasis caused by Muscina stabulans

    Directory of Open Access Journals (Sweden)

    Shivekar S

    2008-01-01

    Full Text Available Intestinal maggots were isolated from a patient, who had reported to the Department of General Medicine of Sri Manakula Vinayagar Medical College, Puducherry, in southern India with complaints of abdominal distress, bloating of abdomen and intestinal hurry following a meal. He was diagnosed as a case of intestinal myiasis. Maggots obtained from his stool were identified to be Muscina stabulans based on characteristic patterns of posterior spiracles. He was treated with purgatives and albendazole. This intestinal myiasis case caused by M. stabulans is reported here because of its rare occurrence and the need to establish a correct diagnosis.

  11. Ischemia-reperfusion and neonatal intestinal injury.

    Science.gov (United States)

    Young, Christopher M; Kingma, Sandra D K; Neu, Josef

    2011-02-01

    We review research relating ischemia/reperfusion to injury in the neonatal intestine. Epidemiologic evidence suggests that the most common form of necrotizing enterocolitis is not triggered by a primary hypoxic-ischemic event. Its late occurrence, lack of preceding ischemic events, and evidence for microbial and inflammatory processes preclude a major role for primary hypoxic ischemia as the sentinel pathogenic event. However, term infants, especially those with congenital heart disease who have development of intestinal necrosis, and those preterm infants with spontaneous intestinal perforations, are more likely to have intestinal ischemia as a primary component of their disease pathogenesis. Copyright © 2011 Mosby, Inc. All rights reserved.

  12. Impedance Analysis of Silicon Nanowire Lithium Ion Battery Anodes

    KAUST Repository

    Ruffo, Riccardo

    2009-07-02

    The impedance behavior of silicon nanowire electrodes has been investigated to understand the electrochemical process kinetics that influences the performance when used as a high-capacity anode in a lithium ion battery. The ac response was measured by using impedance spectroscopy in equilibrium conditions at different lithium compositions and during several cycles of charge and discharge in a half cell vs. metallic lithium. The impedance analysis shows the contribution of both surface resistance and solid state diffusion through the bulk of the nanowires. The surface process is dominated by a solid electrolyte layer (SEI) consisting of an inner, inorganic insoluble part and several organic compounds at the outer interface, as seen by XPS analysis. The surface resistivity, which seems to be correlated with the Coulombic efficiency of the electrode, grows at very high lithium contents due to an increase in the inorganic SEI thickness. We estimate the diffusion coefficient of about 2 × 10 -10 cm 2/s for lithium diffusion in silicon. A large increase in the electrode impedance was observed at very low lithium compositions, probably due to a different mechanism for lithium diffusion inside the wires. Restricting the discharge voltage to 0.7 V prevents this large impedance and improves the electrode lifetime. Cells cycled between 0.07 and 0.70 V vs. metallic lithium at a current density of 0.84 A/g (C/5) showed good Coulombic efficiency (about 99%) and maintained a capacity of about 2000 mAh/g after 80 cycles. © 2009 American Chemical Society.

  13. Surface impedance of travelling--Wave antenna in magnetized plasma

    International Nuclear Information System (INIS)

    Denisenko, I.B.; Ostrikov, K.N.

    1993-01-01

    Wave properties of metal antennas immersed in a magnetoactive plasma are intensively studied nowadays with the objects of radio communications in ionosphere, plasma heating, gas discharge technique. Many papers are devoted to studies of sheath waves (SW) in magnetoplasma, which are surface by nature and propagate along the metal-low-density sheath-plasma waveguide structure. The results of these papers suggest that the existence of these waves makes significant contribution in antenna impedance. Note that the impedance measurement is one of possible ways of experimental surface waves characterization. In the present report the surface impedance of travelling SW antenna immersed in magnetoactive plasma is calculated and its dependence on the waveguide structure parameters such as plasma density, external magnetic field H 0 and electrons collisional frequency values, sheath region width, conductivity of metal surface is studied. The calculations have been carried out in a quasiplane approximation, when antenna radius greatly exceeds the SW skin depth. Note that the finite conductivity of metal is necessary to be taken into account to provide a finite surface impedance value. The surface impedance is calculated in two cases, namely when SW propagate along (Ζ parallel ) and across (Ζ perpendicular ) the external magnetic field. The relation between the values Ζ parallel and Ζ perpendicular is obtained. This relation shows that the values Ζ parallel and Ζ parallel may satisfy both inequalities Ζ parallel much-gt Ζ perpendicular and Ζ perpendicular approx-gt Ζ perpendicular dependent on the parameters of the structure. The comparison of dispersion properties of the SW propagating along Η 0 with the experimental results is carried out. The results are shown to satisfactorily correspond to the experimental results

  14. Modern Trends in Imaging XI: Impedance Measurements in the Biomedical Sciences

    Directory of Open Access Journals (Sweden)

    Frederick D. Coffman

    2012-01-01

    Full Text Available Biological organisms and their component organs, tissues and cells have unique electrical impedance properties. Impedance properties often change with changes in structure, composition, and metabolism, and can be indicative of the onset and progression of disease states. Over the past 100 years, instruments and analytical methods have been developed to measure the impedance properties of biological specimens and to utilize these measurements in both clinical and basic science settings. This chapter will review the applications of impedance measurements in the biomedical sciences, from whole body analysis to impedance measurements of single cells and cell monolayers, and how cellular impedance measuring instruments can now be used in high throughput screening applications.

  15. Adaptive control of grid-connected inverters based on online grid impedance measurements

    Energy Technology Data Exchange (ETDEWEB)

    Cespedes, Mauricio; Sun, Jian [Rensselaer Polytechnic Institute, Troy, NY (United States). Dept. of Electrical, Computer and Systems Engineering

    2012-07-01

    Stability of a grid-connected inverter depends on the ratio of the grid impedance to the inverter impedance. Since the grid impedance changes during normal power system conditions, this paper uses first an impulse response analysis method built into a grid-connected inverter for online grid impedance identification. Secondly, in order to develop simple adaptation rules for the inverter control system, the grid impedance is assumed inductive, and used to derive, analytically, the stability limits of PLL bandwidth and grid voltage feedforward gains. Experimental measurements demonstrate the online grid impedance identification and the inverter adaptive control implemented together within the DSP of a three-phase grid-connected inverter. (orig.)

  16. Effects of digested onion extracts on intestinal gene expression: an interspecies comparison using different intestine models

    NARCIS (Netherlands)

    Hulst, M.M.; Meulen, van der J.; Hoekman, A.J.W.; Smits, M.A.

    2016-01-01

    Applicability of in vitro (human Caco-2 cells) and ex vivo intestine models (rat precision cut intestine slices and the pig in-situ small intestinal segment perfusion (SISP) technique) to study the effect of food compounds. In vitro digested yellow (YOd) and white onion extracts (WOd) were used as

  17. Intestinal Microbiota Signatures Associated With Histological Liver Steatosis in Pediatric-Onset Intestinal Failure

    NARCIS (Netherlands)

    Korpela, K.; Mutanen, A.; Salonen, A.; Savilahti, E.; Vos, de W.M.; Pakarinen, M.P.

    2017-01-01

    BACKGROUND: Intestinal failure (IF)-associated liver disease (IFALD) is the major cause of mortality in IF. The link between intestinal microbiota and IFALD is unclear. METHODS: We compared intestinal microbiota of patients with IF (n = 23) with healthy controls (n = 58) using culture-independent

  18. The Extracellular Calcium-Sensing Receptor in the Intestine: Evidence for Regulation of Colonic Absorption, Secretion, Motility, and Immunity.

    Science.gov (United States)

    Tang, Lieqi; Cheng, Catherine Y; Sun, Xiangrong; Pedicone, Alexandra J; Mohamadzadeh, Mansour; Cheng, Sam X

    2016-01-01

    Different from other epithelia, the intestinal epithelium has the complex task of providing a barrier impeding the entry of toxins, food antigens, and microbes, while at the same time allowing for the transfer of nutrients, electrolytes, water, and microbial metabolites. These molecules/organisms are transported either transcellularly, crossing the apical and basolateral membranes of enterocytes, or paracellularly, passing through the space between enterocytes. Accordingly, the intestinal epithelium can affect energy metabolism, fluid balance, as well as immune response and tolerance. To help accomplish these complex tasks, the intestinal epithelium has evolved many sensing receptor mechanisms. Yet, their roles and functions are only now beginning to be elucidated. This article explores one such sensing receptor mechanism, carried out by the extracellular calcium-sensing receptor (CaSR). In addition to its established function as a nutrient sensor, coordinating food digestion, nutrient absorption, and regulating energy metabolism, we present evidence for the emerging role of CaSR in the control of intestinal fluid homeostasis and immune balance. An additional role in the modulation of the enteric nerve activity and motility is also discussed. Clearly, CaSR has profound effects on many aspects of intestinal function. Nevertheless, more work is needed to fully understand all functions of CaSR in the intestine, including detailed mechanisms of action and specific pathways involved. Considering the essential roles CaSR plays in gastrointestinal physiology and immunology, research may lead to a translational opportunity for the development of novel therapies that are based on CaSR's unique property of using simple nutrients such as calcium, polyamines, and certain amino acids/oligopeptides as activators. It is possible that, through targeting of intestinal CaSR with a combination of specific nutrients, oral solutions that are both inexpensive and practical may be

  19. Debye potentials, electromagnetic reciprocity and impedance boundary conditions for efficient analytic approximation of coupling impedances in complex heterogeneous accelerator pipes

    Energy Technology Data Exchange (ETDEWEB)

    Petracca, S. [Salerno Univ. (Italy)

    1996-08-01

    Debye potentials, the Lorentz reciprocity theorem, and (extended) Leontovich boundary conditions can be used to obtain simple and accurate analytic estimates of the longitudinal and transverse coupling impedances of (piecewise longitudinally uniform) multi-layered pipes with non simple transverse geometry and/or (spatially inhomogeneous) boundary conditions. (author)

  20. Sound reflection in an acoustic impedance tube terminated with a loudspeaker shunted by a negative impedance converter

    Czech Academy of Sciences Publication Activity Database

    Černík, M.; Mokrý, Pavel

    2012-01-01

    Roč. 21, č. 11 (2012), s. 115016-115016 ISSN 0964-1726 R&D Projects: GA MŠk(CZ) ED2.1.00/03.0079 Institutional research plan: CEZ:AV0Z20430508 Keywords : Sound absorption * electromagnetic shunt damping * electrodynamic loudspeaker * negative impedance converter Subject RIV: BI - Acoustics Impact factor: 2.024, year: 2012

  1. Inflammatory mediators and intestinal injury.

    Science.gov (United States)

    Caplan, M S; MacKendrick, W

    1994-06-01

    Although the causes of necrotizing enterocolitis (NEC) are not well understood, there is compelling evidence to suggest that the inflammatory mediators play an important role in the pathophysiology of the disease. This article examines the role of platelet-activating factor (PAF) and other mediators on the development of NEC, and attempts to explain the association of the putative NEC risk factors with altered mediator production and subsequent intestinal injury. The authors hypothesize that PAF is a key mediator in the final common pathway leading to NEC.

  2. Intestinal Lymphangiectasia Secondary to Neuroblastoma

    Directory of Open Access Journals (Sweden)

    RM Reifen

    1994-01-01

    Full Text Available An eight month-old infant presented with a 10-day history of vomiting and diarrhea, and a one-week history of swelling of the lower extremities. Laboratory evaluations revealed hypoproteinemia and lymphocytopenia due to protein-losing enteropathy. Peroral small bowel biopsy showed intestinal lymphangiectasia. Subsequent onset of unexplained ecchymosis and obstructive jaundice resulted in additional studies which revealed an omental neuroblastoma as the underlying etiology of the infant’s symptoms. This report emphasizes the importance of considering secondary, obstructive causes for lymphangiectasia and protein-losing enteropathy.

  3. PREFACE: XV International Conference on Electrical Bio-Impedance (ICEBI) & XIV Conference on Electrical Impedance Tomography (EIT)

    Science.gov (United States)

    Pliquett, Uwe

    2013-04-01

    Over recent years advanced measurement methods have facilitated outstanding achievements not only in medical instrumentation but also in biotechnology. Impedance measurement is a simple and innocuous way to characterize materials. For more than 40 years biological materials, most of them based on cells, have been characterized by means of electrical impedance for quality control of agricultural products, monitoring of biotechnological or food processes or in health care. Although the list of possible applications is long, very few applications successfully entered the market before the turn of the century. This was, on the one hand, due to the low specificity of electrical impedance with respect to other material properties because it is influenced by multiple factors. On the other hand, equipment and methods for many potential applications were not available. With the appearance of microcontrollers that could be easily integrated in applications at the beginning of the 1980s, impedance measurement advanced as a valuable tool in process optimization and lab automation. However, established methods and data processing were mostly used in a new environment. This has changed significantly during the last 10 years with a dramatic growth of the market for medical instrumentation and also for biotechnological applications. Today, advanced process monitoring and control require fast and highly parallel electrical characterization which in turn yields incredible data volumes that must be handled in real time. Many newer developments require miniaturized but precise sensing methods which is one of the main parts of Lab-on-Chip technology. Moreover, biosensors increasingly use impedometric transducers, which are not compatible with the large expensive measurement devices that are common in the laboratory environment. Following the achievements in the field of bioimpedance measurement, we will now witness a dramatic development of new electrode structures and electronics

  4. Variation in Deep Brain Stimulation Electrode Impedance over Years Following Electrode Implantation

    Science.gov (United States)

    Satzer, David; Lanctin, David; Eberly, Lynn E.; Abosch, Aviva

    2014-01-01

    Background Deep brain stimulation (DBS) electrode impedance is a major determinant of current delivery to target tissues, but long-term variation in impedance has received little attention. Objectives To assess the relationship between electrode impedance and time in a large DBS patient population and characterize the relationship between contact activity and impedance. Methods We collected retrospective impedance and programming data from 128 electrodes in 84 patients with Parkinson's disease, essential tremor, or dystonia. Effects of time, contact activity, stimulation voltage, and other parameters on impedance were assessed. We also examined impedance changes following contact activation and deactivation. Results Impedance decreased by 73 Ω/year (P Impedance was on average 163 Ω lower in active contacts (P impedance, respectively. Higher stimulation voltages were associated with lower impedance values (P impedance. Conclusions Impedance decreases gradually in a stimulation-dependent manner. These trends have implications for long-term programming, the development of a closed-loop DBS device, and current understanding of the electrode-tissue interface. PMID:24503709

  5. Prematurity reduces functional adaptation to intestinal resection in piglets

    DEFF Research Database (Denmark)

    Aunsholt, Lise; Thymann, Thomas; Qvist, Niels

    2015-01-01

    Background: Necrotizing enterocolitis and congenital gastrointestinal malformations in infants often require intestinal resection, with a subsequent risk of short bowel syndrome (SBS). We hypothesized that immediate intestinal adaptation following resection of the distal intestine with placement ...

  6. The Adaptive Response to Intestinal Oxidative Stress in Mammalian Hibernation

    National Research Council Canada - National Science Library

    Carey, Hannah V

    2006-01-01

    .... Specific Aim 2 examines consequences of intestinal oxidative stress during hibernation including seasonal changes in NF-kB activation in intestine, seasonal changes in the intestinal mucosal immune...

  7. Lymphoma Caused by Intestinal Microbiota

    Directory of Open Access Journals (Sweden)

    Mitsuko L. Yamamoto

    2014-09-01

    Full Text Available The intestinal microbiota and gut immune system must constantly communicate to maintain a balance between tolerance and activation: on the one hand, our immune system should protect us from pathogenic microbes and on the other hand, most of the millions of microbes in and on our body are innocuous symbionts and some can even be beneficial. Since there is such a close interaction between the immune system and the intestinal microbiota, it is not surprising that some lymphomas such as mucosal-associated lymphoid tissue (MALT lymphoma have been shown to be caused by the presence of certain bacteria. Animal models played an important role in establishing causation and mechanism of bacteria-induced MALT lymphoma. In this review we discuss different ways that animal models have been applied to establish a link between the gut microbiota and lymphoma and how animal models have helped to elucidate mechanisms of microbiota-induced lymphoma. While there are not a plethora of studies demonstrating a connection between microbiota and lymphoma development, we believe that animal models are a system which can be exploited in the future to enhance our understanding of causation and improve prognosis and treatment of lymphoma.

  8. Intestinal histoplasmosis in immunocompetent adults.

    Science.gov (United States)

    Zhu, Lin-Lin; Wang, Jin; Wang, Zi-Jing; Wang, Yi-Ping; Yang, Jin-Lin

    2016-04-21

    To present a retrospective analysis of clinical and endoscopic features of 4 cases of immunocompetent hosts with intestinal histoplasmosis (IH). Four immunocompetent adults were diagnosed with IH between October 2005 and March 2015 at West China Hospital of Sichuan University. Clinical and endoscopic characteristics were summarized and analyzed retrospectively. GMS (Gomori methenamine silver), PAS (periodic acid-Schiff) and Giemsa staining technique were used to confirm Histoplasma capsulatum(H. capsulatum). The symptoms, signs, endoscopic presentations, radiographic imaging, pathological stain results and follow-up are presented as tables and illustrations. The cases were male patients, ranging from 33 to 61 years old, and primarily presented with non-specific symptoms such as irregular fever, weight loss, abdominal pain and distention. Hepatosplenomegaly and lymphadenopathy were the most common signs. Endoscopic manifestations were localized or diffuse congestion, edema, ulcers, and polypoid nodules with central erosion involving the terminal ileum, ascending colon, transverse colon, descending colon, sigmoid colon and rectum, similar to intestinal tuberculosis, tumor, and inflammatory bowel disease. Numerous yeast-like pathogens testing positive for PAS and GMS stains but negative for Giemsa were detected in the cytoplasm of the histiocytes, which were highly suggestive of H. capsulatum. Immunocompetent individuals suffering from histoplasmosis are rarely reported. It is necessary that gastroenterologists and endoscopists consider histoplasmosis as a differential diagnosis, even in immunocompetent patients.

  9. Current distribution effects in AC impedance spectroscopy of electroceramic point contact and thin film model electrodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Jacobsen, Torben

    2010-01-01

    regarding its significance is provided. The associated characteristic impedance spectrum shape change is simulated and its origin discussed. Furthermore, the characteristic shape of impedance spectra of thin electroceramic film electrodes with lateral ohmic resistance is studied as a function...

  10. Megacystis microcolon intestinal hypoperistalsis syndrome: a report ...

    African Journals Online (AJOL)

    The prognosis is poor and most patients die early because of sepsis or total parental nutrition-related complications. This report describes a new case of megacystis microcolon intestinal hypoperistalsis syndrome associated with meconium ileus, dilated stomach, and megaesophagus. Keywords: intestinal hypoperistalsis ...

  11. Intestinal cholesterol secretion: future clinical implications

    NARCIS (Netherlands)

    Jakulj, L.; Besseling, J.; Stroes, E. S. G.; Groen, A. K.

    2013-01-01

    Together with the liver, the intestine serves as a homeostatic organ in cholesterol metabolism. Recent evidence has substantiated the pivotal role of the intestine in reverse cholesterol transport (RCT). RCT is a fundamental antiatherogenic pathway, mediating the removal of cholesterol from tissues

  12. Intestinal cholesterol secretion : future clinical implications

    NARCIS (Netherlands)

    Jakulj, L.; Besseling, J.; Stroes, E. S. G.; Groen, A. K.

    2013-01-01

    Together with the liver, the intestine serves as a homeostatic organ in cholesterol metabolism. Recent evidence has substantiated the pivotal role of the intestine in reverse cholesterol transport (RCT). RCT is a fundamental antiatherogenic pathway, mediating the removal of cholesterol from tissues

  13. Alkaline Phosphatases From Camel Small Intestine | Fahmy ...

    African Journals Online (AJOL)

    Camel intestinal alkaline phosphatase have been purified and characterized. The purification was carried out by chromatography on DEAE-cellulose. Five intestinal alkaline phosphatase isoenzymes (IAP1 to IAP5) were obtained. IAP2 and IAP5 with the highest activity levels were purified to homogeneity by Sephacryl ...

  14. Megacystis microcolon intestinal hypoperistalsis syndrome: a report ...

    African Journals Online (AJOL)

    intestinal peristalsis. The prognosis is poor and most patients die early because of sepsis or total parental nutrition-related complications. This report describes a new case of megacystis microcolon intestinal hypoperistalsis syndrome associated with meconium ileus, dilated stomach, and megaesophagus. Ann Pediatr Surg.

  15. Is nonoperative management of adhesive intestinal obstruction ...

    African Journals Online (AJOL)

    Background: Nonoperative management of adhesive intestinal obstruction gives good results in adults but there are scant studies on its outcome in children. This study reports outcomes and experiences with nonoperative and operative management of adhesive intestinal obstruction in children in a resource-poor country.

  16. Laparoscopic Treatment of Intestinal Malrotation in Children

    NARCIS (Netherlands)

    Ooms, N.; Matthyssens, L.E.; Draaisma, J.M.T.; Blaauw, I. de; Wijnen, M.H.

    2016-01-01

    Purpose Intestinal malrotation is a congenital intestinal rotation anomaly, which can be treated by either laparotomy or laparoscopy. Our hypothesis is that laparoscopic treatment leads to less small bowel obstruction because of the fewer adhesions in comparison to laparotomy, without increasing the

  17. Species and prevalence determination of Human Intestinal ...

    African Journals Online (AJOL)

    Intestinal parasitic infections constitute a global health burden causing clinical morbidity. Parasitic protozoa and helminthes are responsible for some of the most devastating and prevalent diseases of human. The study was conducted to determine the prevalence of intestinal parasites among patients attending Federal ...

  18. Ectoparasites and intestinal helminths of speckled pigeon ...

    African Journals Online (AJOL)

    Ectoparasites and intestinal helminths of speckled pigeon ( Columba guinea Hartlaub and Finsch 1870) in Zaria, Nigeria. ... Science World Journal ... A total of 30 (20 males and 10 females) Speckled Pigeons trapped from the wild in Zaria and its environs, Nigeria, were examined for ectoparasites and intestinal helminths, ...

  19. Species and prevalence determination of Human Intestinal ...

    African Journals Online (AJOL)

    ADOWIE PERE

    ABSTRACT: Intestinal parasitic infections constitute a global health burden causing clinical morbidity. Parasitic protozoa and helminthes are responsible for some of the most devastating and prevalent diseases of human. The study was conducted to determine the prevalence of intestinal parasites among patients attending ...

  20. Intestinal radiation syndrome: sepsis and endotoxin

    International Nuclear Information System (INIS)

    Geraci, J.P.; Jackson, K.L.; Mariano, M.S.

    1985-01-01

    Rats were whole-body irradiated with 8-MeV cyclotron-produced neutrons and 137 Cs γ rays to study the role of enteric bacteria and endotoxin in the intestinal radiation syndrome. Decrease in intestinal weight was used as an index of radiation-induced breakdown of the mucosa. Neutron and γ-ray doses that were sublethal for intestinal death resulted in a dose-dependent decrease in intestinal weight, reaching minimal values 2 to 3 days after exposure, followed by recovery within 5 days after irradiation. Neutron and photon doses that caused intestinal death resulted in greater mucosal breakdown with little or no evidence of mucosal recovery. The presence of fluid in the intestine and diarrhea, but not bacteremia or endotoxemia, were related to mucosal breakdown and recovery. Neither sepsis nor endotoxin could be detected in liver samples taken at autopsy from animals which died a short time earlier from intestinal injury. These results suggest that overt sepsis and endotoxemia do not play a significant role in the intestinal radiation syndrome