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Sample records for four-dimensional superquadric-based cardiac

  1. Four-dimensional modeling of the heart for image guidance of minimally invasive cardiac surgeries

    Science.gov (United States)

    Wierzbicki, Marcin; Drangova, Maria; Guiraudon, Gerard; Peters, Terry

    2004-05-01

    Minimally invasive surgery of the beating heart can be associated with two major limitations: selecting port locations for optimal target coverage from x-rays and angiograms, and navigating instruments in a dynamic and confined 3D environment using only an endoscope. To supplement the current surgery planning and guidance strategies, we continue developing VCSP - a virtual reality, patient-specific, thoracic cavity model derived from 3D pre-procedural images. In this work, we apply elastic image registration to 4D cardiac images to model the dynamic heart. Our method is validated on two image modalities, and for different parts of the cardiac anatomy. In a helical CT dataset of an excised heart phantom, we found that the artificial motion of the epicardial surface can be extracted to within 0.93 +/- 0.33 mm. For an MR dataset of a human volunteer, the error for different heart structures such as the myocardium, right and left atria, right ventricle, aorta, vena cava, and pulmonary artery, ranged from 1.08 +/- 0.18 mm to 1.14 +/- 0.22 mm. These results indicate that our method of modeling the motion of the heart is not only easily adaptable but also sufficiently accurate to meet the requirements for reliable cardiac surgery training, planning, and guidance.

  2. Four-dimensional cardiac reconstruction from rotational x-ray sequences: first results for 4D coronary angiography

    Science.gov (United States)

    Hansis, Eberhard; Schomberg, Hermann; Erhard, Klaus; Dössel, Olaf; Grass, Michael

    2009-02-01

    The tomographic reconstruction of the beating heart requires dedicated methods. One possibility is gated reconstruction, where only data corresponding to a certain motion state are incorporated. Another one is motioncompensated reconstruction with a pre-computed motion vector field, which requires a preceding estimation of the motion. Here, results of a new approach are presented: simultaneous reconstruction of a three-dimensional object and its motion over time, yielding a fully four-dimensional representation. The object motion is modeled by a time-dependent elastic transformation. The reconstruction is carried out with an iterative gradient-descent algorithm which simultaneously optimizes the three-dimensional image and the motion parameters. The method was tested on a simulated rotational X-ray acquisition of a dynamic coronary artery phantom, acquired on a C-arm system with a slowly rotating C-arm. Accurate reconstruction of both absorption coefficient and motion could be achieved. First results from experiments on clinical rotational X-ray coronary angiography data are shown. The resulting reconstructions enable the analysis of both static properties, such as vessel geometry and cross-sectional areas, and dynamic properties, like magnitude, speed, and synchrony of motion during the cardiac cycle.

  3. Extracting Superquadric-based Geon Description for 3D Object Recognition

    Institute of Scientific and Technical Information of China (English)

    XINGWeiwei; LIUWeibin; YUANBaozong

    2005-01-01

    Geons recognition is one key issue in developing 3D object recognition system based on Recognition by components (RBC) theory. In this paper, we present a novel approach for extracting superquadric-based geon description of 3D volumetric primitives from real shape data, which integrates the advantages of deformable superquadric models reconstruction and SVM-based classification. First, Real-coded genetic algorithm (RCGA) is used for superquadric fitting to 3D data and the quantitative parametric information is obtained; then a new sophisticated feature set is derived from superquadric parameters obtained for the next step; and SVM-based classification is proposed and implemented for geons recognition and the qualitative geometric information is obtained. Furthermore, the knowledge-based feedback of SVM network is introduced for improving the classification performance. Ex-perimental results obtained show that our approach is efficient and precise for extracting superquadric-based geon description from real shape data in 3D object recognition. The results are very encouraging and have significant benefit for developing the general 3D object recognition system.

  4. Superquadric Based Hierarchical Reconstruction for Virtualizing Free Form Objects from 3D Data

    Institute of Scientific and Technical Information of China (English)

    LIU Weibin; YUAN Baozong

    2001-01-01

    The superquadric description is usedin modeling the virtual objects in AVR (from ActualReality to Virtual Reality).However,due to the in-trinsic property,the superquadric and its deforma-tion extensions (DSQ) are not flexible enough to de-scribe precisely the complex objects with asymmetryand free form surface.To solve the problem,a hierar-chical reconstruction approach in AVR for virtualizingthe objects with superquadric based models from 3Ddata is developed.Firstly,an initial approximation isproduced by a superquadric fit to the 3D data.Then,the crude superquadric fit is refined by fitting theresidue (distance map) with global and local DirectManipulation of Free-Form Deformation (DMFFD).The key elements of the hierarchical method,includ-ing superquadric fit to 3D data,mathematical detailsand the recursive-fitting algorithm for DMFFD,com-putation of distance maps,adaptive refinement anddecimation of polygon mesh under DMFFD,are pro-posed.An implementation example of hierarchicalreconstruction is presented.The proposed approachis shown competent and efficient for virtualizing thecomplex objects into virtual environment.

  5. Feasibility Study on Prenatal Cardiac Screening Using Four-Dimensional Ultrasound with Spatiotemporal Image Correlation: A Multicenter Study.

    Directory of Open Access Journals (Sweden)

    Liqing Zhao

    Full Text Available This study aimed at investigating the feasibility of using the spatiotemporal image correlation (STIC technology for prenatal cardiac screening, finding factors that influence the offline evaluation of reconstructed fetal heart, and establishing an optimal acquisition scheme.The study included 452 gravidae presenting for routine screening at 3 maternity centers at 20-38 gestational weeks. The factors influencing the quality of STIC volume data were evaluated using t test, chi-square test, and logistic regression analysis. The predictive power was evaluated using the receiver operating characteristic (ROC curve.Among the 452 fetuses enrolled, 353 (78.1% were identified as successful and 99 (21.9% as failure of evaluation of the reconstructed fetal heart. The total success rate of qualified STIC images was 78.1%. The display rates of reconstructed cardiac views were 86.5% (four-chamber view, 92.5% (left ventricular outflow tract view, 92.7% (right ventricular outflow tract view, 89.9% (three-vessel trachea view, 63.9% (aortic arch view, 81.4% (ductal arch view, 81% (short-axis view of great vessels, 80.1% (long-cava view, and 86.9% (abdominal view. A logistic regression analysis showed that more than 28 gestational weeks [OR = 0.39 (CI 95% 0.16, 0.19, P = 0.035], frequent fetal movements [OR = 0.37 (CI 95% 0.16, 0.87, P = 0.022], shadowing [OR = 0.36 (CI 95% 0.19, 0.72, P = 0.004], spine location at 10-2 o'clock [OR = 0.08 (CI 95% 0.02, 0.27, P = 0.0], and original cardiac view [OR = 0.51 (0.25, 0.89, P = 0.019] had a significant impact on the quality of STIC. The area under the ROC curve was 0.775.Fetal cardiac-STIC seems a feasible tool for prenatal screening of congenital heart diseases. The influence factors on the quality of STIC images included the intensity of training, gestational age, fetal conditions and parameter settings. The optimal acquisition scheme may improve the application and widespread use of cardiac STIC.

  6. Four Dimensional (4-D BioChemInfoPhysics Models of Cardiac Cellular and Sub-Cellular Vibrations (Oscillations

    Directory of Open Access Journals (Sweden)

    Chang-Hua Zou

    2009-01-01

    Full Text Available Problem statement: Cardiovascular Diseases (CVD continued to be the leading cause of death. Failure or abnormal cardiac cellular or sub-cellular vibrations (oscillations could lead failure or abnormal heart beats that could cause CVD. Understanding the mechanisms of the vibrations (oscillations could help to prevent or to treat the diseases. Scientists have studied the mechanisms for more than 100 years. To our knowledge, the mechanisms are still unclear today. In this investigation, based on published data or results, conservation laws of the momentum as well as the energy, in views of biology, biochemistry, informatics and physics (BioChemInfoPhysics, we proposed our models of cardiac cellular and sub-cellular vibrations (oscillations of biological components, such as free ions in Biological Fluids (BF, Biological Membranes (BM, Ca++H+ (Ca++ and Na+K+ ATPases, Na+Ca++ exchangers (NCX, Ca++ carriers and myosin heads. Approach: Our models were described with 4-D (x, y, z, t or r, ?, z, t momentum transfer equations in mathematical physics. Results: The momentum transfer equations were solved with free and forced, damped, un-damped and over-damped, vibrations (oscillations. The biological components could be modeled as resonators or vibrators (oscillators, such as liquid plasmas, membranes, active springs, passive springs and active swings. Conclusion: We systematically provided new insights of automation (ignition and maintain, transportation, propagation and orientation of the cardiac cellular and sub-cellular vibrations (oscillations and resonances, with our BioChemInfoPhysics models of 4-D momentum transfer equations. Our modeling results implied: Auto-rhythmic cells (Sinoatrial Node Cells (SANC, Atrioventricular Node Cells (AVNC, Purkinje fibers, non-Auto-rhythmic ventricular myocytes and their Sarcoplasmic Reticulums (SR work as Biological Liquid Plasma Resonators (BLPR. The resonators were

  7. Four Dimensional Trace Space Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, M.

    2005-02-10

    Future high energy colliders and FELs (Free Electron Lasers) such as the proposed LCLS (Linac Coherent Light Source) at SLAC require high brightness electron beams. In general a high brightness electron beam will contain a large number of electrons that occupy a short longitudinal duration, can be focused to a small transverse area while having small transverse divergences. Therefore the beam must have a high peak current and occupy small areas in transverse phase space and so have small transverse emittances. Additionally the beam should propagate at high energy and have a low energy spread to reduce chromatic effects. The requirements of the LCLS for example are pulses which contain 10{sup 10} electrons in a temporal duration of 10 ps FWHM with projected normalized transverse emittances of 1{pi} mm mrad[1]. Currently the most promising method of producing such a beam is the RF photoinjector. The GTF (Gun Test Facility) at SLAC was constructed to produce and characterize laser and electron beams which fulfill the LCLS requirements. Emittance measurements of the electron beam at the GTF contain evidence of strong coupling between the transverse dimensions of the beam. This thesis explores the effects of this coupling on the determination of the projected emittances of the electron beam. In the presence of such a coupling the projected normalized emittance is no longer a conserved quantity. The conserved quantity is the normalized full four dimensional phase space occupied by the beam. A method to determine the presence and evaluate the strength of the coupling in emittance measurements made in the laboratory is developed. A method to calculate the four dimensional volume the beam occupies in phase space using quantities available in the laboratory environment is also developed. Results of measurements made of the electron beam at the GTF that demonstrate these concepts are presented and discussed.

  8. Four-Dimensional Graded Consciousness.

    Science.gov (United States)

    Jonkisz, Jakub; Wierzchoń, Michał; Binder, Marek

    2017-01-01

    Both the multidimensional phenomenon and the polysemous notion of consciousness continue to prove resistant to consistent measurement and unambiguous definition. This is hardly surprising, given that there is no agreement even as regards the most fundamental issues they involve. One of the basic disagreements present in the continuing debate about consciousness pertains to its gradational nature. The general aim of this article is to show how consciousness might be graded and multidimensional at the same time. We therefore focus on the question of what it is, exactly, that is or could be graded in cases of consciousness, and how we can measure it. Ultimately, four different gradable aspects of consciousness will be described: quality, abstractness, complexity and usefulness, which belong to four different dimensions, these being understood, respectively, as phenomenal, semantic, physiological, and functional. Consequently, consciousness may be said to vary with respect to phenomenal quality, semantic abstraction, physiological complexity, and functional usefulness. It is hoped that such a four-dimensional approach will help to clarify and justify claims about the hierarchical nature of consciousness. The approach also proves explanatorily advantageous, as it enables us not only to draw attention to certain new and important differences in respect of subjective measures of awareness and to justify how a given creature may be ranked higher in one dimension of consciousness and lower in terms of another, but also allows for innovative explanations of a variety of well-known phenomena (amongst these, the interpretations of blindsight and locked-in syndrome will be briefly outlined here). Moreover, a 4D framework makes possible many predictions and hypotheses that may be experimentally tested (We point out a few such possibilities pertaining to interdimensional dependencies).

  9. Fetal cardiac ventricular volume, cardiac output, and ejection fraction determined with four-dimensional ultrasound using Spatio-Temporal Image Correlation (STIC) and Virtual Organ Computed-aided AnaLysis (VOCAL™)

    Science.gov (United States)

    Hamill, Neil; Yeo, Lami; Romero, Roberto; Hassan, Sonia S.; Myers, Stephen A.; Mittal, Pooja; Kusanovic, Juan Pedro; Balasubramaniam, Mamtha; Chaiworapongsa, Tinnakorn; Vaisbuch, Edi; Espinoza, Jimmy; Gotsch, Francesca; Goncalves, Luis F.; Lee, Wesley

    2011-01-01

    Objective To quantify fetal cardiovascular parameters with Spatio-Temporal Image Correlation (STIC) and Virtual Organ Computed-aided AnaLysis (VOCAL™) utilizing the sub-feature: “Contour Finder: Trace”. Study Design A cross-sectional study was designed consisting of patients with normal pregnancies between 19 and 40 weeks of gestation. After STIC datasets were acquired, analysis was performed offline (4DView) and the following cardiovascular parameters were evaluated: ventricular volume in end systole and end diastole, stroke volume, cardiac output, and ejection fraction. To account for fetal size, cardiac output was also expressed as a function of head circumference, abdominal circumference, or femoral diaphysis length. Regression models were fitted for each cardiovascular parameter to assess the effect of gestational age and paired comparisons were made between the left and right ventricles. Results 1) Two hundred and seventeen patients were retrospectively identified, of whom 184 had adequate STIC datasets (85% acceptance); 2) ventricular volume, stroke volume, cardiac output, and adjusted cardiac output increased with gestational age; whereas, the ejection fraction decreased as gestation advanced; 3) the right ventricle was larger than the left in both systole (Right: 0.50 ml, IQR: 0.2 – 0.9; vs. Left: 0.27 ml, IQR: 0.1 – 0.5; p<0.001) and diastole (Right: 1.20 ml, IQR: 0.7 – 2.2; vs. Left: 1.03 ml, IQR: 0.5 – 1.7; p<0.001); 4) there were no differences between the left and right ventricle with respect to stroke volume, cardiac output, or adjusted cardiac output; and 5) the left ventricular ejection fraction was greater than the right (Left: 72.2%, IQR: 64 – 78; vs. Right: 62.4%, IQR: 56 – 69; p<0.001). Conclusion Fetal echocardiography, utilizing STIC and VOCAL™ with the sub-feature: “Contour Finder: Trace”, allows assessment of fetal cardiovascular parameters. Normal fetal cardiovascular physiology is characterized by ventricular

  10. Two dimensional fermions in four dimensional YM

    CERN Document Server

    Narayanan, R

    2009-01-01

    Dirac fermions in the fundamental representation of SU(N) live on a two dimensional torus flatly embedded in $R^4$. They interact with a four dimensional SU(N) Yang Mills vector potential preserving a global chiral symmetry at finite $N$. As the size of the torus in units of $\\frac{1}{\\Lambda_{SU(N)}}$ is varied from small to large, the chiral symmetry gets spontaneously broken in the infinite $N$ limit.

  11. String Breaking in Four Dimensional Lattice QCD

    CERN Document Server

    Duncan, A; Thacker, H

    2001-01-01

    Virtual quark pair screening leads to breaking of the string between fundamental representation quarks in QCD. For unquenched four dimensional lattice QCD, this (so far elusive) phenomenon is studied using the recently developed truncated determinant algorithm (TDA). The dynamical configurations were generated on an Athlon 650 MHz PC. Quark eigenmodes up to 420 MeV are included exactly in these TDA studies performed at low quark mass on large coarse (but O($a^2$) improved) lattices. A study of Wilson line correlators in Coulomb gauge extracted from an ensemble of 1000 two-flavor dynamical configurations reveals evidence for flattening of the string tension at distances R $\\geq$ approximately 1 fm.

  12. Purely Four-dimensional Viable Anomaly Mediation

    CERN Document Server

    Harnik, R; Pierce, A T; Harnik, Roni; Murayama, Hitoshi; Pierce, Aaron

    2002-01-01

    Anomaly mediation of supersymmetry breaking solves the supersymmetric flavor problem thanks to its ultraviolet-insensitivity. However, it suffers from two problems: sleptons have negative masses-squared, and there are likely bulk moduli that spoil the framework. Here, we present the first fully ultraviolet-insensitive model of anomaly mediation with positive slepton masses-squared in a purely four-dimensional framework. Our model is based on the additional D-term contributions to the sparticle masses of Arkani-Hamed, Kaplan, HM, and Nomura, and the conformal sequestering mechanism of Luty and Sundrum.

  13. Four dimensional non-critical strings

    CERN Document Server

    Ferrari, F

    2002-01-01

    This is a set of lectures on the gauge/string duality and non-critical strings, with a particular emphasis on the discretized, or matrix model, approach. After a general discussion of various points of view, I describe the recent generalization to four dimensional non-critical (or five dimensional critical) string theories of the matrix model approach. This yields fully non-perturbative and explicit definition of string theories with eight (or more) supercharges that are related to four dimensional CFTs and their relevant deformations. The space-time as well as world-sheet dimensions of the supersymmetry preserving world-sheet couplings are obtained. Exact formulas for the central charge of the space-time supersymmetry algebra as a function of these couplings are calculated. They include infinite series of string perturbative contributions as well as all the non-perturbative effects. An important insight on the gauge theory side is that instantons yield a non-trivial 1/N expansion at strong coupling, and gene...

  14. N=3 four dimensional field theories

    CERN Document Server

    García-Etxebarria, Iñaki

    2015-01-01

    We introduce a class of four dimensional field theories constructed by quotienting ordinary $\\mathcal{N}=4$ $U(N)$ SYM by particular combinations of R-symmetry and $SL(2,\\mathbb{Z})$ automorphisms. These theories appear naturally on the worldvolume of D3 branes probing terminal singularities in F-theory, where they can be thought of as non-perturbative generalizations of the O3 plane. We focus on cases preserving only 12 supercharges, where the quotient gives rise to theories with coupling fixed at a value of order one. These constructions posses an unconventional large $N$ limit described by a non-trivial F-theory fibration with base $AdS_5\\times (S^5/\\mathbb{Z}_k)$. Upon reduction on a circle the $\\mathcal{N}=3$ theories flow to well-known $\\mathcal{N}=6$ ABJM theories.

  15. Four-dimensional unsubtraction with massive particles

    CERN Document Server

    Sborlini, German F R; Rodrigo, German

    2016-01-01

    We extend the four-dimensional unsubtraction method, which is based on the loop-tree duality (LTD), to deal with processes involving heavy particles. The method allows to perform the summation over degenerate IR configurations directly at integrand level in such a way that NLO corrections can be implemented directly in four space-time dimensions. We define a general momentum mapping between the real and virtual kinematics that accounts properly for the quasi-collinear configurations, and leads to an smooth massless limit. We illustrate the method first with an scalar toy example, and then analyse the case of the decay of a scalar or vector boson into a pair of massive quarks. The results presented in this paper are suitable for the application of the method to any multipartonic process.

  16. Chiral Four-Dimensional Heterotic Covariant Lattices

    CERN Document Server

    Beye, Florian

    2014-01-01

    In the covariant lattice formalism, chiral four-dimensional heterotic string vacua are obtained from certain even self-dual lattices which completely decompose into a left-mover and a right-mover lattice. The main purpose of this work is to classify all right-mover lattices that can appear in such a chiral model, and to study the corresponding left-mover lattices using the theory of lattice genera. In particular, the Smith-Minkowski-Siegel mass formula is employed to calculate a lower bound on the number of left-mover lattices. Also, the known relationship between asymmetric orbifolds and covariant lattices is considered in the context of our classification.

  17. Four-dimensional coherent electronic Raman spectroscopy

    Science.gov (United States)

    Harel, Elad

    2017-04-01

    The correlations between different quantum-mechanical degrees of freedom of molecular species dictate their chemical and physical properties. Generally, these correlations are reflected in the optical response of the system but in low-order or low-dimensionality measurement the signals are highly averaged. Here, we describe a novel four-dimensional coherent spectroscopic method that directly correlates within and between the manifold of electronic and vibrational states. The optical response theory is developed in terms of both resonant and non-resonant field-matter interactions. Using resonance to select coherences on specific electronic states creates opportunities to directly distinguish coherent dynamics on the ground and electronically excited potentials. Critically, this method is free from lower-order signals that have plagued other electronically non-resonant vibrational spectroscopies. The theory presented here compliments recent work on the experimental demonstration of the 4D spectroscopic method described. We highlight specific means by which non-trivial effects such as anharmonicity (diagonal and off-diagonal), mode-specific vibronic coupling, and curvature of the excited states manifest in different projections of the 4D spectrum.

  18. Four-Dimensional Spin Foam Perturbation Theory

    Directory of Open Access Journals (Sweden)

    João Faria Martins

    2011-10-01

    Full Text Available We define a four-dimensional spin-foam perturbation theory for the BF-theory with a B∧B potential term defined for a compact semi-simple Lie group G on a compact orientable 4-manifold M. This is done by using the formal spin foam perturbative series coming from the spin-foam generating functional. We then regularize the terms in the perturbative series by passing to the category of representations of the quantum group U_q(g where g is the Lie algebra of G and q is a root of unity. The Chain-Mail formalism can be used to calculate the perturbative terms when the vector space of intertwiners Λ⊗Λ→A, where A is the adjoint representation of g, is 1-dimensional for each irrep Λ. We calculate the partition function Z in the dilute-gas limit for a special class of triangulations of restricted local complexity, which we conjecture to exist on any 4-manifold M. We prove that the first-order perturbative contribution vanishes for finite triangulations, so that we define a dilute-gas limit by using the second-order contribution. We show that Z is an analytic continuation of the Crane-Yetter partition function. Furthermore, we relate Z to the partition function for the F∧F theory.

  19. General flat four-dimensional world pictures and clock systems

    Science.gov (United States)

    Hsu, J. P.; Underwood, J. A.

    1978-01-01

    We explore the mathematical structure and the physical implications of a general four-dimensional symmetry framework which is consistent with the Poincare-Einstein principle of relativity for physical laws and with experiments. In particular, we discuss a four-dimensional framework in which all observers in different frames use one and the same grid of clocks. The general framework includes special relativity and a recently proposed new four-dimensional symmetry with a nonuniversal light speed as two special simple cases. The connection between the properties of light propagation and the convention concerning clock systems is also discussed, and is seen to be nonunique within the four-dimensional framework.

  20. 四维时空关联成像技术在中晚孕胎儿心脏筛查中的应用%Application of Four-Dimensional Spatio-Temporal Image Correlation in Screening of Fetal Cardiac Structure in Second and Late Trimester Pregnancy

    Institute of Scientific and Technical Information of China (English)

    黎新艳; 田晓先; 林莲恩; 李雪芹; 周旋; 黄欢; 刘萍萍

    2013-01-01

    Objective To explore the application value of four-dimensional spatio-temporal image correlation (STIC) technology in a screening of fetal cardiac structure in the second and late trimester pregnancy .Methods Fetal heart volume datasets were acquired by STIC from 180 normal fetuses at 18 to 38 weeks′gestation .Analysis of the volume datasets using the described technique to display 4 screening echocardiographic planes in the dynamic multi-planar display mode was performed off-line.Results Among 180 pregnant women , the STIC volume data were obtained successfully in 148 cases(82.2%),STIC sweep was obviously more timesaving than that of cardiac screening (P0 .05 ) . Conclusion STIC provides us a timesaving sweep for fulfilling fetal cardiac scanning .The STIC acquisition is of satisfactory qulity,which can be applied to a screening of fetal heart in the second and late trimester pregnancy .The STIC acquisition has relationship with spine acoustic shadow , frequent fetal movement and abnormal amniotic fluid volume.%目的:探讨四维时空关联成像( STIC)技术在中晚孕胎儿心脏筛查中的应用价值。方法运用STIC技术对180例孕18~38周孕妇胎儿进行心脏容积数据采集,采用动态正交三平面模式,显示4个筛查切面。结果180例孕妇中,148例(82.2%)获满意STIC容积数据,采集时间明显少于二维切面采集时间( P<0.05);STIC采集的心脏四腔心、左室流出道、右室流出道、三血管气管切面图像质量满意率与二维超声图像质量比较差异无统计学意义( P>0.05)。结论 STIC技术可缩短胎儿心脏扫描时间;采集的胎儿心脏标准图像质量满意,可应用于中晚孕胎儿心脏筛查,其容积数据采集受到胎儿脊柱声影、胎动频繁、羊水量异常等影响。

  1. Successive superalgebraic truncations from the four-dimensional maximal supergravity

    CERN Document Server

    Kim, C H; Kim, K Y; Kim, Y; Kim, Chang Ho; Park, Young Jai; Kim, Kee Yong; Kim, Yongduk

    1994-01-01

    We study the four-dimensional {\\it N}=8 maximal supergravity in the context of Lie superalgebra SU(8/1). All possible successive superalgebraic truncations from four-dimensional {\\it N}=8 theory to {\\it N}=7, 6, \\cdots, 1 supergravity theories are systematically realized as sub-superalgebra chains of SU(8/1) by using the Kac-Dynkin weight techniques.

  2. Inverse Operation of Four-dimensional Vector Matrix

    Directory of Open Access Journals (Sweden)

    H J Bao

    2011-08-01

    Full Text Available This is a new series of study to define and prove multidimensional vector matrix mathematics, which includes four-dimensional vector matrix determinant, four-dimensional vector matrix inverse and related properties. There are innovative concepts of multi-dimensional vector matrix mathematics created by authors with numerous applications in engineering, math, video conferencing, 3D TV, and other fields.

  3. On the four-dimensional formulation of dimensionally regulated amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Fazio, A.R. [Universidad Nacional de Colombia, Departamento de Fisica, Bogota (Colombia); Mastrolia, P. [Universita di Padova, Dipartimento di Fisica e Astronomia, Padua (Italy); Max-Planck-Institut fuer Physik, Munich (Germany); INFN, Padova (Italy); Mirabella, E. [Max-Planck-Institut fuer Physik, Munich (Germany); Torres Bobadilla, W.J. [Universidad Nacional de Colombia, Departamento de Fisica, Bogota (Colombia); Universita di Padova, Dipartimento di Fisica e Astronomia, Padua (Italy); INFN, Padova (Italy)

    2014-12-01

    Elaborating on the four-dimensional helicity scheme, we propose a pure four-dimensional formulation (FDF) of the d-dimensional regularization of one-loop scattering amplitudes. In our formulation particles propagating inside the loop are represented by massive internal states regulating the divergences. The latter obey Feynman rules containing multiplicative selection rules which automatically account for the effects of the extra-dimensional regulating terms of the amplitude. We present explicit representations of the polarization and helicity states of the four-dimensional particles propagating in the loop. They allow for a complete, four-dimensional, unitarity-based construction of d-dimensional amplitudes. Generalized unitarity within the FDF does not require any higher-dimensional extension of the Clifford and the spinor algebra. Finally we show how the FDF allows for the recursive construction of d-dimensional one-loop integrands, generalizing the four-dimensional open-loop approach. (orig.)

  4. Three- and four-dimensional ultrasound in fetal echocardiography: an up-to-date overview.

    Science.gov (United States)

    Adriaanse, B M E; van Vugt, J M G; Haak, M C

    2016-09-01

    Congenital heart diseases (CHD) are the most commonly overlooked lesions in prenatal screening programs. Real-time two-dimensional ultrasound (2DUS) is the conventionally used tool for fetal echocardiography. Although continuous improvements in the hardware and post-processing software have resulted in a good image quality even in late first trimester, 2DUS still has its limitations. Four-dimensional ultrasound with spatiotemporal image correlation (STIC) is an automated volume acquisition, recording a single three-dimensional (3D) volume throughout a complete cardiac cycle, which results in a four-dimensional (4D) volume. STIC has the potential to increase the detection rate of CHD. The aim of this study is to provide a practical overview of the possibilities and (dis)advantages of STIC. A review of literature and evaluation of the current status and clinical value of 3D/4D ultrasound in prenatal screening and diagnosis of congenital heart disease are presented.

  5. Anisotropic Four-Dimensional NS-NS String Cosmology

    CERN Document Server

    Chen, C M; Mak, M K; Chen, Chiang-Mei

    2001-01-01

    An anisotropic (Bianchi type I) cosmology is considered in the four-dimensional NS-NS sector of low-energy effective string theory coupled to a dilaton and an axion-like $H$-field within a de Sitter-Einstein frame background. The time evolution of this Universe is discussed in both the Einstein and string frames.

  6. Teaching Life Cycles: The Four-Dimensional Organism.

    Science.gov (United States)

    Harper, G. H.

    1987-01-01

    Argues that life cycles and the concept of the four-dimensional organism should be the most important idea in teaching high school biology in the United Kingdom. Presents a set of concepts and terms with a view to improving the perceived confusion in present teaching situations. (TW)

  7. Gravitational and Axionic Backgrounds for Four-dimensional Superstrings

    CERN Document Server

    Lüst, Dieter

    1993-01-01

    We construct new four-dimensional superstring vacua with extended superconformal symmetries. A non-trivial dilaton background implies the existence of Abelian killing symmetries. These are used to construct dual equivalent backgrounds in a way preserving the N=2 superconformal invariance.

  8. A novel four-dimensional autonomous hyperchaotic system

    Institute of Scientific and Technical Information of China (English)

    Liu Chong-Xin; Liu Ling

    2009-01-01

    A novel four-dimensional autonomous hyperchaotic system is reported in this paper. Some basic dynamical properties of the new hyperchaotic system are investigated in detail by means of a continuous spectrum, Lyapunov hyperchaotic system are proved by not only performing numerical simulation and brief theoretical analysis but also by conducting an electronic circuit experiment.

  9. The scalar curvature problem on the four dimensional half sphere

    CERN Document Server

    Ben-Ayed, M; El-Mehdi, K

    2003-01-01

    In this paper, we consider the problem of prescribing the scalar curvature under minimal boundary conditions on the standard four dimensional half sphere. We provide an Euler-Hopf type criterion for a given function to be a scalar curvature for some metric conformal to the standard one. Our proof involves the study of critical points at infinity of the associated variational problem.

  10. Manual control displays for a four-dimensional landing approach

    Science.gov (United States)

    Silverthorn, J. T.; Swaim, R. L.

    1975-01-01

    Six instrument rated pilots flew a STOL fixed base simulator to study the effectiveness of three displays for a four dimensional approach. The three examined displays were a digital readout of forward position error, a digital speed command, and an analog display showing forward position error and error prediction. A flight director was used in all conditions. All test runs were for a typical four dimensional approach in moderate turbulence that included a change in commanded ground speed, a change in flight path angle, and two standard rate sixty degree turns. Use of the digital forward position error display resulted in large overshoot in the forward position error. Some type of lead (rate or prediction information) was shown to be needed. The best overall performance was obtained using the speed command display. It was demonstrated that curved approaches can be flown with relative ease.

  11. IDENTIFICATION OF ARCHITECTURAL FUNCTIONS IN A FOUR-DIMENSIONAL SPACE

    Directory of Open Access Journals (Sweden)

    Firza Utama Sjarifudin

    2012-05-01

    Full Text Available This research has explored the possibilities and concept of architectural space in a virtual environment. The virtual environment exists as a different concept, and challenges the constraints of the physical world. One of the possibilities in a virtual environment is that it is able to extend the spatial dimension higher than the physical three-dimension. To take the advantage of this possibility, this research has applied some geometrical four-dimensional (4D methods to define virtual architectural space. The spatial characteristics of 4D space is established by analyzing the four-dimensional structure that can be comprehended by human participant for its spatial quality, and by developing a system to control the fourth axis of movement. Multiple three-dimensional spaces that fluidly change their volume have been defined as one of the possibilities of virtual architectural space concept in order to enrich our understanding of virtual spatial experience.

  12. Aspects of the Supersymmetry Algebra in Four Dimensional Euclidean Space

    CERN Document Server

    McKeon, D G C

    1998-01-01

    The simplest supersymmetry (SUSY) algebra in four dimensional Euclidean space ($4dE$) has been shown to closely resemble the $N = 2$ SUSY algebra in four dimensional Minkowski space ($4dM$). The structure of the former algebra is examined in greater detail in this paper. We first present its Clifford algebra structure. This algebra shows that the momentum Casimir invariant of physical states has an upper bound which is fixed by the central charges. Secondly, we use reduction of the $N = 1$ SUSY algebra in six dimensional Minkowski space ($6dM$) to $4dE$; this reproduces our SUSY algebra in $4dE$. Moreover, this same reduction of supersymmetric Yang-Mills theory (SSYM) in $6dM$ reproduces Zumino's SSYM in $4dE$. We demonstrate how this dimensional reduction can be used to introduce additional generators into the SUSY algebra in $4dE$.

  13. Finding four dimensional symplectic maps with reduced chaos: Preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Weishi Wan; Cary, J.R.; Shasharina, S.G.

    1998-06-01

    A method for finding integrable four-dimensional symplectic maps is outlined. The method relies on solving for parameter values at which the linear stability factors of the fixed points of the map have the values corresponding to integrability. This method is applied to accelerator lattices in order to increase dynamic aperture. Results show a increase of the dynamic aperture after correction, which implies the validity of the method.

  14. Integrable four-dimensional symplectic maps of standard type

    CERN Document Server

    McLachlan, R I

    1993-01-01

    We search for rational, four-dimensional maps of standard type (x_{n+1} - 2x_n + x_{n-1} = eps f(x,eps)) possessing one or two polynomial integrals. There are no non-trivial maps corresponding to cubic oscillators, but we find a four-parameter family of such maps corresponding to quartic oscillators. This seems to be the only such example.

  15. Temporal Parameter Optimization in Four-Dimensional Flash Trajectory Imaging

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-Wei; ZHOU Yan; FAN Song-Tao; LIU Yu-Liang

    2011-01-01

    In four-dimensional fiash trajectory imaging, temporal parameters include time delay, laser pulse width, gate time, pulse pair repetition frequency and the frame rate of CCD, which directly impact on the acquisition of target trajectories over time. We propose a method of optimizing the temporal parameters of flash trajectory imaging. All the temporal parameters can be estimated by the spatial parameters of the volumes of interest, target scale and velocity, and target sample number. The formulae for optimizing temporal parameters are derived, and the method is demonstrated in an experiment with a ball oscillating as a pendulum.%In four-dimensional flash trajectory imaging,temporal parameters include time delay,laser pulse width,gate time,pulse pair repetition frequency and the frame rate of CCD,which directly impact on the acquisition of target trajectories over time.We propose a method of optimizing the temporal parameters of flash trajectory imaging.All the temporal parameters can be estimated by the spatial parameters of the volumes of interest,target scale and velocity,and target sample number.The formulae for optimizing temporal parameters are derived,and the method is demonstrated in an experiment with a ball oscillating as a pendulum.Four-dimensional flash trajectory imaging (FTI)based on time-delay-modulated range-gated viewing can directly image the trajectories of moving objects with backgrounds filtered and deduce target 3D positions over time,[1] which has potentials in astronomy,remote sensing and biomedical applications.[2 4] Temporal parameters are crucial for FTI.An unreasonable setting of temporal parameters will lead to failure in obtaining target trajectories.However,in the previous work,[1] the optimization of temporal parameters has not been discussed in detail.Therefore,in this Letter we give a method of estimating the temporal parameters of FTI.

  16. Local bifurcation analysis of a four-dimensional hyperchaotic system

    Institute of Scientific and Technical Information of China (English)

    Wu Wen-Juan; Chen Zeng-Qiang; Yuan Zhu-Zhi

    2008-01-01

    Local bifurcation phenomena in a four-dimensional continuous hyperchaotic system, which has rich and complex dynamical behaviours, are analysed. The local bifurcations of the system are investigated by utilizing the bifurcation theory and the centre manifold theorem, and thus the conditions of the existence of pitchfork bifurcation and Hopf bifurcation are derived in detail. Numerical simulations are presented to verify the theoretical analysis, and they show some interesting dynamics, including stable periodic orbits emerging from the new fixed points generated by pitchfork bifurcation, coexistence of a stable limit cycle and a chaotic attractor, as well as chaos within quite a wide parameter region.

  17. Four-dimensional optical manipulation of colloidal particles

    DEFF Research Database (Denmark)

    Rodrigo, P.J.; Daria, V.R.; Glückstad, J.

    2005-01-01

    We transform a TEM00 laser mode into multiple counterpropagating optical traps to achieve four-dimensional simultaneous manipulation of multiple particles. Efficient synthesis and dynamic control of the counterpropagating-beam traps is carried out via the generalized phase contrast method......, and a spatial polarization-encoding scheme. Our experiments genuinely demonstrate real-time, interactive particle-position control for forming arbitrary volumetric constellations and complex three-dimensional trajectories of multiple particles. This opens up doors for cross-disciplinary cutting-edge research...

  18. Four-Dimensional Gallant-Lambert-Vanstone Scalar Multiplication

    CERN Document Server

    Birkner, Peter

    2011-01-01

    The GLV method of Gallant, Lambert and Vanstone (CRYPTO 2001) computes any multiple $kP$ of a point $P$ of prime order $n$ lying on an elliptic curve with a low-degree endomorphism $\\Phi$ (called GLV curve) over $\\mathbb{F}_p$ as \\[kP = k_1P + k_2\\Phi(P), \\quad\\text{with} \\max\\{|k_1|,|k_2|\\}\\leq C\\sqrt n] for some explicit constant $C>0$. Recently, Galbraith, Lin and Scott (EUROCRYPT 2009) extended this method to all curves over $\\mathbb{F}_{p^2}$ which are twists of curves defined over $\\mathbb{F}_p$. These are examples of two-dimensional decompositions (with two new scalars), and the GLS approach shows that for curves with many automorphisms (cubic and quartic twists) one can achieve a four-dimensional decomposition as well. We show in this work how to merge the two approaches in order to get, for twists of any GLV curve over $\\mathbb{F}_{p^2}$, a four-dimensional decomposition together with fast endomorphisms $\\Phi, \\Psi$ over $\\mathbb{F}_{p^2}$ acting on the group generated by a point $P$ of prime order $...

  19. Four-dimensional black holes in Einsteinian cubic gravity

    Science.gov (United States)

    Bueno, Pablo; Cano, Pablo A.

    2016-12-01

    We construct static and spherically symmetric generalizations of the Schwarzschild- and Reissner-Nordström-(anti-)de Sitter [RN-(A)dS] black-hole solutions in four-dimensional Einsteinian cubic gravity (ECG). The solutions are characterized by a single function which satisfies a nonlinear second-order differential equation. Interestingly, we are able to compute independently the Hawking temperature T , the Wald entropy S and the Abbott-Deser mass M of the solutions analytically as functions of the horizon radius and the ECG coupling constant λ . Using these we show that the first law of black-hole mechanics is exactly satisfied. Some of the solutions have positive specific heat, which makes them thermodynamically stable, even in the uncharged and asymptotically flat case. Further, we claim that, up to cubic order in curvature, ECG is the most general four-dimensional theory of gravity which allows for nontrivial generalizations of Schwarzschild- and RN-(A)dS characterized by a single function which reduce to the usual Einstein gravity solutions when the corresponding higher-order couplings are set to zero.

  20. Platonic solids generate their four-dimensional analogues

    CERN Document Server

    Dechant, Pierre-Philippe

    2013-01-01

    In this paper, we show how regular convex 4-polytopes - the analogues of the Platonic solids in four dimensions - can be constructed from three-dimensional considerations concerning the Platonic solids alone. Via the Cartan-Dieudonne theorem, the reflective symmetries of the Platonic solids generate rotations. In a Clifford algebra framework, the space of spinors generating such three-dimensional rotations has a natural four-dimensional Euclidean structure. The spinors arising from the Platonic Solids can thus in turn be interpreted as vertices in four-dimensional space, giving a simple construction of the 4D polytopes 16-cell, 24-cell, the F_4 root system and the 600-cell. In particular, these polytopes have `mysterious' symmetries, that are almost trivial when seen from the three-dimensional spinorial point of view. In fact, all these induced polytopes are also known to be root systems and thus generate rank-4 Coxeter groups, which can be shown to be a general property of the spinor construction. These cons...

  1. Four-dimensional BPS-spectra via M-theory

    CERN Document Server

    Henningson, M

    1998-01-01

    We consider the realization of four-dimensional theories with N = 2 supersymmetry as M-theory configurations including a five-brane. Our emphasis is on the spectrum of massive states, that are realized as two-branes ending on the five-brane. We start with a determination of the supersymmetries that are left unbroken by the background metric and five-brane. We then show how the central charge of the N = 2 algebra arises from the central charge associated with the M-theory two-brane. This determines the condition for a two-brane configuration to be BPS-saturated in the four-dimensional sense. By imposing certain conditions on the moduli, we can give concrete examples of such two-branes. This leads us to conjecture that vectormultiplet and hypermultiplet BPS-saturated states correspond to two-branes with the topology of a cylinder and a disc respectively. We also discuss the phenomenon of marginal stability of BPS-saturated states.

  2. Decomposable medium conditions in four-dimensional representation

    CERN Document Server

    Lindell, Ismo V; Favaro, Alberto

    2011-01-01

    The well-known TE/TM decomposition of time-harmonic electromagnetic fields in uniaxial anisotropic media is generalized in terms of four-dimensional differential-form formalism by requiring that the field two-form satisfies an orthogonality condition with respect to two given bivectors. Conditions for the electromagnetic medium in which such a decomposition is possible are derived and found to define three subclasses of media. It is shown that the previously known classes of generalized Q-media and generalized P-media are particular cases of the proposed decomposable media (DCM) associated to a quadratic equation for the medium dyadic. As a novel solution, another class of special decomposable media (SDCM) is defined by a linear dyadic equation. The paper further discusses the properties of medium dyadics and plane-wave propagation in all the identified cases of DCM and SDCM.

  3. Four-dimensional black holes in Einsteinian cubic gravity

    CERN Document Server

    Bueno, Pablo

    2016-01-01

    We construct static and spherically symmetric generalizations of the Schwarzschild- and Reissner-Nordstr\\"om-(Anti) de Sitter (RN-(A)dS) black-hole solutions in four-dimensional Einsteinian cubic gravity (ECG). The solutions are determined by a single blackening factor which satisfies a non-linear second-order differential equation. Interestingly, we are able to compute independently the Hawking temperature $T$, the Wald entropy $\\mathsf{S}$ and the Abbott-Deser mass $M$ of the solutions analytically as functions of the horizon radius and the ECG coupling constant $\\lambda$. Using these we show that the first law of black-hole mechanics is exactly satisfied. Some of the solutions have positive specific heat, which makes them thermodynamically stable, even in the uncharged and asymptotically flat case.

  4. The effective action in four-dimensional CDT

    CERN Document Server

    Gizbert-Studnicki, Jakub

    2015-01-01

    We present recent results concerning the measurement and analysis of the effective action in four-dimensional Causal Dynamical Triangulations. The action describes quantum fluctuations of the spatial volume of the CDT universe (or alternatively the scale factor) after integrating out other degrees of freedom. We use the covariance of volume fluctuations to measure and parametrize the effective action inside the de Sitter phase, also called the C phase. We show that the action is consistent with a simple discretization of the minisuperspace action (with a reversed overall sign). We discuss possible subleading corrections and show how to construct a more complicated effective action comprising both integer and half-integer discrete proper time layers. We introduce a new method of the effective action measurement based on the transfer matrix. We show that the results of the new method are fully consistent with the covariance matrix method inside the de Sitter phase. We use the new method to measure the effective...

  5. An explicit four-dimensional variational data assimilation method

    Institute of Scientific and Technical Information of China (English)

    QIU ChongJian; ZHANG Lei; SHAO AiMei

    2007-01-01

    A new data assimilation method called the explicit four-dimensional variational (4DVAR) method is proposed. In this method, the singular value decomposition (SVD) is used to construct the orthogonal basis vectors from a forecast ensemble in a 4D space. The basis vectors represent not only the spatial structure of the analysis variables but also the temporal evolution. After the analysis variables are expressed by a truncated expansion of the basis vectors in the 4D space, the control variables in the cost function appear explicitly, so that the adjoint model, which is used to derive the gradient of cost function with respect to the control variables, is no longer needed. The new technique significantly simplifies the data assimilation process. The advantage of the proposed method is demonstrated by several experiments using a shallow water numerical model and the results are compared with those of the conventional 4DVAR. It is shown that when the observation points are very dense, the conventional 4DVAR is better than the proposed method. However, when the observation points are sparse, the proposed method performs better. The sensitivity of the proposed method with respect to errors in the observations and the numerical model is lower than that of the conventional method.

  6. An explicit four-dimensional variational data assimilation method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new data assimilation method called the explicit four-dimensional variational (4DVAR) method is proposed. In this method, the singular value decomposition (SVD) is used to construct the orthogonal basis vectors from a forecast ensemble in a 4D space. The basis vectors represent not only the spatial structure of the analysis variables but also the temporal evolution. After the analysis variables are ex-pressed by a truncated expansion of the basis vectors in the 4D space, the control variables in the cost function appear explicitly, so that the adjoint model, which is used to derive the gradient of cost func-tion with respect to the control variables, is no longer needed. The new technique significantly simpli-fies the data assimilation process. The advantage of the proposed method is demonstrated by several experiments using a shallow water numerical model and the results are compared with those of the conventional 4DVAR. It is shown that when the observation points are very dense, the conventional 4DVAR is better than the proposed method. However, when the observation points are sparse, the proposed method performs better. The sensitivity of the proposed method with respect to errors in the observations and the numerical model is lower than that of the conventional method.

  7. The connection between polarization calculus and four-dimensional rotations

    CERN Document Server

    Karlsson, Magnus

    2013-01-01

    We review the well-known polarization optics matrix methods, i.e., Jones and Stokes-Mueller calculus, and show how they can be formulated in terms of four-dimensional (4d) rotations of the four independent electromagnetic field quadratures. Since 4d rotations is a richer description than the conventional Jones and Stokes-Mueller calculi, having six rather than four degrees of freedom (DOF), we propose an extension of those calculi to handle all six DOF. For the Stokes-Mueller analysis, this leads to a novel and potentially useful extension that accounts for the absolute phase of the optical field, and which can be valuable in the areas where the optical phase is of interest, e.g. interferometry or coherent communications. As examples of the usefulness we use the formalism to explain the Pancharatnam phase by parallel transport, and shows its connection with the Berry phase. In addition we show that the two extra DOF in the 4d description represents unphysical transformations, forbidden for propagating photons...

  8. Four-dimensional unsubtraction from the loop-tree duality

    CERN Document Server

    Sborlini, German F R; Hernandez-Pinto, Roger; Rodrigo, German

    2016-01-01

    We present a new algorithm to construct a purely four dimensional representation of higher-order perturbative corrections to physical cross-sections at next-to-leading order (NLO). The algorithm is based on the loop-tree duality (LTD), and it is implemented by introducing a suitable mapping between the external and loop momenta of the virtual scattering amplitudes with the external momenta of the real emission corrections. In this way, the sum over degenerate infrared states is performed at the integrand level and the cancellation of infrared divergences occurs locally without introducing subtraction counter-terms to deal with soft and final-state collinear singularities. The dual representation of ultraviolet counter-terms is also discussed in detail, in particular for self-energy contributions. The method is first illustrated with the scalar three-point function, before proceeding with the calculation of the physical cross-section for $\\gamma^* \\to q \\bar{q}(g)$, at its generalisation to multi-leg processes...

  9. Constraints on RG Flow for Four Dimensional Quantum Field Theories

    CERN Document Server

    Jack, I

    2013-01-01

    The response of four dimensional quantum field theories to a Weyl rescaling of the metric in the presence of local couplings and which involve $a$, the coefficient of the Euler density in the energy momentum tensor trace on curved space, is reconsidered. Previous consistency conditions for the anomalous terms, which implicitly define a metric $G$ on the space of couplings and give rise to gradient flow like equations for $a$, are derived taking into account the role of lower dimension operators. The results for infinitesimal Weyl rescaling are integrated to finite rescalings $e^{2\\sigma}$ to a form which involves running couplings $g_\\sigma$ and which interpolates between IR and UV fixed points. The results are also restricted to flat space where they give rise to broken conformal Ward identities. Expressions for the three loop Yukawa $\\beta$-functions for a general scalar/fermion theory are obtained and the three loop contribution to the metric $G$ for this theory are also calculated. These results are used ...

  10. Constraints on RG flow for four dimensional quantum field theories

    Science.gov (United States)

    Jack, I.; Osborn, H.

    2014-06-01

    The response of four dimensional quantum field theories to a Weyl rescaling of the metric in the presence of local couplings and which involve a, the coefficient of the Euler density in the energy momentum tensor trace on curved space, is reconsidered. Previous consistency conditions for the anomalous terms, which implicitly define a metric G on the space of couplings and give rise to gradient flow like equations for a, are derived taking into account the role of lower dimension operators. The results for infinitesimal Weyl rescaling are integrated to finite rescalings e2σ to a form which involves running couplings gσ and which interpolates between IR and UV fixed points. The results are also restricted to flat space where they give rise to broken conformal Ward identities. Expressions for the three loop Yukawa β-functions for a general scalar/fermion theory are obtained and the three loop contribution to the metric G for this theory is also calculated. These results are used to check the gradient flow equations to higher order than previously. It is shown that these are only valid when β→B, a modified β-function, and that the equations provide strong constraints on the detailed form of the three loop Yukawa β-function. N=1 supersymmetric Wess-Zumino theories are also considered as a special case. It is shown that the metric for the complex couplings in such theories may be restricted to a hermitian form.

  11. Four-dimensional unsubtraction from the loop-tree duality

    Science.gov (United States)

    Sborlini, Germán F. R.; Driencourt-Mangin, Félix; Hernández-Pinto, Roger J.; Rodrigo, Germán

    2016-08-01

    We present a new algorithm to construct a purely four dimensional representation of higher-order perturbative corrections to physical cross-sections at next-to-leading order (NLO). The algorithm is based on the loop-tree duality (LTD), and it is implemented by introducing a suitable mapping between the external and loop momenta of the virtual scattering amplitudes, and the external momenta of the real emission corrections. In this way, the sum over degenerate infrared states is performed at integrand level and the cancellation of infrared divergences occurs locally without introducing subtraction counter-terms to deal with soft and final-state collinear singularities. The dual representation of ultraviolet counter-terms is also discussed in detail, in particular for self-energy contributions. The method is first illustrated with the scalar three-point function, before proceeding with the calculation of the physical cross-section for {γ}^{ast}to qoverline{q}(g) , and its generalisation to multi-leg processes. The extension to next-to-next-to-leading order (NNLO) is briefly commented.

  12. Spatial heterogeneity of four-dimensional relative pressure fields in the human left ventricle.

    Science.gov (United States)

    Eriksson, Jonatan; Bolger, Ann F; Carlhäll, Carl-Johan; Ebbers, Tino

    2015-12-01

    To assess the spatial heterogeneity of the four-dimensional (4D) relative pressure fields in the healthy human left ventricle (LV) and provide reference data for normal LV relative pressure. Twelve healthy subjects underwent a cardiac MRI examination where 4D flow and morphological data were acquired. The latter data were segmented and used to define the borders of the LV for computation of relative pressure fields using the pressure Poisson equation. The LV lumen was divided into 17 pie-shaped segments. In the normal left ventricle, the relative pressure in the apical segments was significantly higher relative to the basal segments (P pressure than the opposite basal inferolateral segment during both E-wave (P Relative pressure in the left ventricle is heterogeneous. During diastole, the main pressure differences in the LV occur along the basal-apical axis. However, pressure differences were also found in the short axis direction and may reflect important aspects of atrioventricular coupling. Additionally, this study provides reference data on LV pressure dynamics for a group of healthy subjects. © 2014 Wiley Periodicals, Inc.

  13. EXISTENCE OF PERIODIC SOLUTIONS TO A PERTURBED FOUR-DIMENSIONAL SYSTEM

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Consider a k multiple closed orbit on an invariant surface of a four dimensional system, after a suitable perturbation, the closed orbit can generate periodic orbits and double-period orbits. Using bifurcation methods and techniques, sufficient conditions for the existence of periodic solutions to the perturbed four dimensional system are obtained, and the period-doubling bifurcations is discussed.

  14. A Note on Four-Dimensional Symmetry Algebras and Fourth-Order Ordinary Differential Equations

    Directory of Open Access Journals (Sweden)

    A. Fatima

    2013-01-01

    Full Text Available We provide a supplementation of the results on the canonical forms for scalar fourth-order ordinary differential equations (ODEs which admit four-dimensional Lie algebras obtained recently. Together with these new canonical forms, a complete list of scalar fourth-order ODEs that admit four-dimensional Lie algebras is available.

  15. Four-dimensional computed tomography angiographic evaluation of cranial dural arteriovenous fistula before and after embolization

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Bing, E-mail: bing.tian@hotmail.com; Xu, Bing, E-mail: aishanli0102@126.com; Lu, Jianping, E-mail: tianbing2003@163.com; Liu, Qi, E-mail: liuqimd@126.com; Wang, Li, E-mail: wangli_changhai@163.com; Wang, Minjie, E-mail: cjr.wangminjie@vip.163.com

    2015-06-15

    Highlights: • 4D CTA showed excellent agreement with DSA with regard to identification of feeding arteries and drainage veins. • The most important finding was 4D CTA in determining the impact of DAVF treatment with transarterial embolization. • 4D CTA provides images similar to those obtained with DSA both before and after treatment. - Abstract: Purpose: This study aimed to evaluate the usefulness of four-dimensional CTA before and after embolization treatment with ONYX-18 in eleven patients with cranial dural arteriovenous fistulas, and to compare the results with those of the reference standard DSA. Patients and Methods: Eleven patients with cranial dural arteriovenous fistulas detected on DSA underwent transarterial embolization with ONYX-18. Four-dimensional CTA was performed an average of 2 days before and 4 days after DSA. Four-dimensional CTA and DSA images were reviewed by two neuroradiologists for identification of feeding arteries and drainage veins and for determining treatment effects. Interobserver and intermodality agreement between four-dimensional CTA and DSA were assessed. Results: Forty-two feeding arteries were identified for 14 fistulas in the 11 patients. Of these, 36 (85.71%) were detected on four-dimensional CTA. After transarterial embolization, one patient got partly embolized, and the fistulas in the remaining 10 patients were completely occluded. The interobserver agreement for four-dimensional CTA and intermodality agreement between four-dimensional CTA and DSA were excellent (κ = 1) for shunt location, identification of drainage veins, and fistula occlusion after treatment. Conclusion: Four-dimensional CTA images are highly accurate when compared with DSA images both before and after transarterial embolization treatment. Four-dimensional CTA can be used for diagnosis as well as follow-up of cranial dural arteriovenous fistulas in clinical settings.

  16. Construction of a Class of Four-Dimensional Piecewise Affine Systems with Homoclinic Orbits

    Science.gov (United States)

    Wu, Tiantian; Yang, Xiao-Song

    2016-06-01

    Based on mathematical analysis, this paper provides a methodology to ensure the existence of homoclinic orbits in a class of four-dimensional piecewise affine systems. In addition, an example is provided to illustrate the effectiveness of the method.

  17. Improving the Horizontal Transport in the Lower Troposphere with Four Dimensional Data Assimilation

    Science.gov (United States)

    The physical processes involved in air quality modeling are governed by dynamically-generated meteorological model fields. This research focuses on reducing the uncertainty in the horizontal transport in the lower troposphere by improving the four dimensional data assimilation (F...

  18. Chaotic behaviour of nonlinear coupled reaction–diffusion system in four-dimensional space

    Indian Academy of Sciences (India)

    Li Zhang; Shutang Liu; Chenglong Yu

    2014-06-01

    In recent years, nonlinear coupled reaction–diffusion (CRD) system has been widely investigated by coupled map lattice method. Previously, nonlinear behaviour was observed dynamically when one or two of the three variables in the discrete system change. In this paper, we consider the chaotic behaviour when three variables change, which is called as four-dimensional chaos. When two parameters in the discrete system are unknown, we first give the existing condition of the chaos in four-dimensional space by the generalized definitions of spatial periodic orbits and spatial chaos. In addition, the chaotic behaviour will vary with the parameters. Then we propose a generalized Lyapunov exponent in four-dimensional space to characterize the different effects of parameters on the chaotic behaviour, which has not been studied in detail. In order to verify the chaotic behaviour of the system and the different effects clearly, we simulate the dynamical behaviour in two- and three-dimensional spaces.

  19. Covariant Four-Dimensional Scattering Equations for the NN- πNNSystem

    Science.gov (United States)

    Phillips, D. R.; Afnan, I. R.

    1996-04-01

    We derive a set of coupled four-dimensional integral equations for theNN-πNNsystem using our modified version of the Taylor method of classification-of-diagrams. These equations are covariant, obey two- and three-body unitarity and contain subtraction terms which eliminate the double-counting present in some previous four-dimensionalNN-πNNequations. The equations are then recast into a from convenient for computation by grouping the subtraction terms together and obtaining a set of two-fragment scattering equations for the amplitudes of interest.

  20. Covariant four-dimensional scattering equations for the NN - {pi}NN system

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, D.R.; Afnan, I.R. [Flinders Univ. of South Australia, Adelaide (Australia)

    1996-04-10

    The authors derive a set of coupled four-dimensional integral equations for the NN - {pi}NN system using their modified version of the Taylor method of classification-of-diagrams. These equations are covariant, obey two- and three-body unitarity and contain subtraction terms which eliminate the double-counting present in some previous four-dimensional NN - {pi}NN equations. The equations are then recast into a form convenient for computation by grouping the subtraction terms together and obtaining a set of two-fragment scattering equations for the amplitudes of interest. 43 refs., 20 figs.

  1. Randers metrics of Berwald type on four-dimensional hypercomplex Lie groups

    Energy Technology Data Exchange (ETDEWEB)

    Moghaddam, H R Salimi [Department of Mathematics, Shahrood University of Technology, Shahrood (Iran, Islamic Republic of)], E-mail: hrsalimi@shahroodut.ac.ir

    2009-03-06

    In the present paper we study Randers metrics of Berwald type on simply connected four-dimensional real Lie groups admitting invariant hypercomplex structure. On these spaces, the Randers metrics arising from invariant hyper-Hermitian metrics are considered. Then we give explicit formulae for computing the flag curvature of these metrics. By this study we construct two four-dimensional Berwald spaces, one of them with a non-negative flag curvature and the other one with a non-positive flag curvature.

  2. Experimental measurement of the four-dimensional coherence function for an undulator x-ray source.

    Science.gov (United States)

    Tran, C Q; Williams, G J; Roberts, A; Flewett, S; Peele, A G; Paterson, D; de Jonge, M D; Nugent, K A

    2007-06-01

    A full measurement of the four-dimensional coherence function from an undulator beam line is reported. The analysis is based on the observation that the data are consistent with a coherence function that is mathematically separable. The effective source size can be altered by changing the width of the exit slit, and the complete coherence function is presented for two settings. We find, to within experimental error, that the four-dimensional complex degree of coherence can be described as a real Gaussian function that depends only on the difference of the spatial coordinates.

  3. A Calogero formulation for four-dimensional black-hole microstates

    Directory of Open Access Journals (Sweden)

    Olaf Lechtenfeld

    2016-02-01

    Full Text Available We extract the leading-order entropy of a four-dimensional extremal black hole in N=2 ungauged supergravity by formulating the CFT1 that is holographically dual to its near-horizon AdS2 geometry, in terms of a rational Calogero model with a known counting formula for the degeneracy of states in its Hilbert space.

  4. M-theory resolution of four-dimensional cosmological singularities via U-duality

    NARCIS (Netherlands)

    Feinstein, A.; Vazquez-Mozo, M.A.

    2000-01-01

    We consider cosmological solutions of string and M-theory compactified to four dimensions by giving a general prescription to construct four-dimensional modular cosmologies with two commuting Killing vectors from vacuum solutions. By lifting these solutions to higher dimensions we analyze the existe

  5. Some Aspects of Four Dimensional Black Hole Solutions in Gauss-Bonnet Extended String Gravity

    OpenAIRE

    Alexeyev, S. O.; Sazhin, M. V.

    1997-01-01

    An internal singularity of a string four-dimensional black hole with second order curvature corrections is discussed. A restriction to a minimal size of a neutral black hole is obtained in the frame of the model considered. Vacuum polarization of the surrounding space-time caused by this minimal-size black hole is also discussed.

  6. The ambiguity-free four-dimensional Lorentz-breaking Chern-Simons action

    Energy Technology Data Exchange (ETDEWEB)

    Brito, F.A. [Departamento de Fisica, Universidade Federal de Campina Grande, Caixa Postal 10071, 58109-970 Campina Grande, Paraiba (Brazil); Nascimento, J.R.; Passos, E. [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58051-970 Joao Pessoa, Paraiba (Brazil); Petrov, A.Yu. [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58051-970 Joao Pessoa, Paraiba (Brazil)], E-mail: petrov@fisica.ufpb.br

    2008-06-12

    The four-dimensional Lorentz-breaking finite and determined Chern-Simons like action is generated as a one-loop perturbative correction via an appropriate Lorentz-breaking coupling of the gauge field with the spinor field. Unlike the known schemes of calculations, within this scheme this term is found to be regularization independent.

  7. Effect of four-dimensional variational data assimilation in case of nonlinear instability

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of four-dimensional variational data assimilation on the reduction of the forecast errors is investigated for both stable and unstable flows. Numerical results show that the effect is generally positive. Particularly,its effect is much more significant in the presence of nonlinear instability

  8. Achievable Rates for Four-Dimensional Coded Modulation with a Bit-Wise Receiver

    CERN Document Server

    Alvarado, Alex

    2013-01-01

    We study achievable rates for four-dimensional (4D) constellations for spectrally efficient optical systems based on a (suboptimal) bit-wise receiver. We show that PM-QPSK outperforms the best 4D constellation designed for uncoded transmission by approximately 1 dB. Numerical results using LDPC codes validate the analysis.

  9. Integrable and superintegrable Hamiltonian systems with four dimensional real Lie algebras as symmetry of the systems

    Energy Technology Data Exchange (ETDEWEB)

    Abedi-Fardad, J., E-mail: j.abedifardad@bonabu.ac.ir [Department of Mathematics, Bonab University, Tabriz (Iran, Islamic Republic of); Rezaei-Aghdam, A., E-mail: rezaei-a@azaruniv.edu [Department of Physics, Azarbaijan Shahid Madani University, 53714-161 Tabriz (Iran, Islamic Republic of); Haghighatdoost, Gh., E-mail: gorbanali@azaruniv.edu [Department of Mathematics, Bonab University, Tabriz (Iran, Islamic Republic of); Department of Mathematics, Azarbaijan Shahid Madani University, Tabriz (Iran, Islamic Republic of)

    2014-05-15

    We construct integrable and superintegrable Hamiltonian systems using the realizations of four dimensional real Lie algebras as a symmetry of the system with the phase space R{sup 4} and R{sup 6}. Furthermore, we construct some integrable and superintegrable Hamiltonian systems for which the symmetry Lie group is also the phase space of the system.

  10. Four-dimensional optical coherence tomography imaging of total liquid ventilated rats

    Science.gov (United States)

    Kirsten, Lars; Schnabel, Christian; Gaertner, Maria; Koch, Edmund

    2013-06-01

    Optical coherence tomography (OCT) can be utilized for the spatially and temporally resolved visualization of alveolar tissue and its dynamics in rodent models, which allows the investigation of lung dynamics on the microscopic scale of single alveoli. The findings could provide experimental input data for numerical simulations of lung tissue mechanics and could support the development of protective ventilation strategies. Real four-dimensional OCT imaging permits the acquisition of several OCT stacks within one single ventilation cycle. Thus, the entire four-dimensional information is directly obtained. Compared to conventional virtual four-dimensional OCT imaging, where the image acquisition is extended over many ventilation cycles and is triggered on pressure levels, real four-dimensional OCT is less vulnerable against motion artifacts and non-reproducible movement of the lung tissue over subsequent ventilation cycles, which widely reduces image artifacts. However, OCT imaging of alveolar tissue is affected by refraction and total internal reflection at air-tissue interfaces. Thus, only the first alveolar layer beneath the pleura is visible. To circumvent this effect, total liquid ventilation can be carried out to match the refractive indices of lung tissue and the breathing medium, which improves the visibility of the alveolar structure, the image quality and the penetration depth and provides the real structure of the alveolar tissue. In this study, a combination of four-dimensional OCT imaging with total liquid ventilation allowed the visualization of the alveolar structure in rat lung tissue benefiting from the improved depth range beneath the pleura and from the high spatial and temporal resolution.

  11. T2-weighted four dimensional magnetic resonance imaging with result-driven phase sorting

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yilin; Yin, Fang-Fang; Cai, Jing, E-mail: jing.cai@duke.edu [Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710 and Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Czito, Brian G. [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Bashir, Mustafa R. [Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States)

    2015-08-15

    Purpose: T2-weighted MRI provides excellent tumor-to-tissue contrast for target volume delineation in radiation therapy treatment planning. This study aims at developing a novel T2-weighted retrospective four dimensional magnetic resonance imaging (4D-MRI) phase sorting technique for imaging organ/tumor respiratory motion. Methods: A 2D fast T2-weighted half-Fourier acquisition single-shot turbo spin-echo MR sequence was used for image acquisition of 4D-MRI, with a frame rate of 2–3 frames/s. Respiratory motion was measured using an external breathing monitoring device. A phase sorting method was developed to sort the images by their corresponding respiratory phases. Besides, a result-driven strategy was applied to effectively utilize redundant images in the case when multiple images were allocated to a bin. This strategy, selecting the image with minimal amplitude error, will generate the most representative 4D-MRI. Since we are using a different image acquisition mode for 4D imaging (the sequential image acquisition scheme) with the conventionally used cine or helical image acquisition scheme, the 4D dataset sufficient condition was not obviously and directly predictable. An important challenge of the proposed technique was to determine the number of repeated scans (N{sub R}) required to obtain sufficient phase information at each slice position. To tackle this challenge, the authors first conducted computer simulations using real-time position management respiratory signals of the 29 cancer patients under an IRB-approved retrospective study to derive the relationships between N{sub R} and the following factors: number of slices (N{sub S}), number of 4D-MRI respiratory bins (N{sub B}), and starting phase at image acquisition (P{sub 0}). To validate the authors’ technique, 4D-MRI acquisition and reconstruction were simulated on a 4D digital extended cardiac-torso (XCAT) human phantom using simulation derived parameters. Twelve healthy volunteers were involved

  12. Four-dimensional cone beam CT reconstruction and enhancement using a temporal nonlocal means method

    Energy Technology Data Exchange (ETDEWEB)

    Jia Xun; Tian Zhen; Lou Yifei; Sonke, Jan-Jakob; Jiang, Steve B. [Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037 (United States); School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30318 (United States); Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX Amsterdam (Netherlands); Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037 (United States)

    2012-09-15

    Purpose: Four-dimensional cone beam computed tomography (4D-CBCT) has been developed to provide respiratory phase-resolved volumetric imaging in image guided radiation therapy. Conventionally, it is reconstructed by first sorting the x-ray projections into multiple respiratory phase bins according to a breathing signal extracted either from the projection images or some external surrogates, and then reconstructing a 3D CBCT image in each phase bin independently using FDK algorithm. This method requires adequate number of projections for each phase, which can be achieved using a low gantry rotation or multiple gantry rotations. Inadequate number of projections in each phase bin results in low quality 4D-CBCT images with obvious streaking artifacts. 4D-CBCT images at different breathing phases share a lot of redundant information, because they represent the same anatomy captured at slightly different temporal points. Taking this redundancy along the temporal dimension into account can in principle facilitate the reconstruction in the situation of inadequate number of projection images. In this work, the authors propose two novel 4D-CBCT algorithms: an iterative reconstruction algorithm and an enhancement algorithm, utilizing a temporal nonlocal means (TNLM) method. Methods: The authors define a TNLM energy term for a given set of 4D-CBCT images. Minimization of this term favors those 4D-CBCT images such that any anatomical features at one spatial point at one phase can be found in a nearby spatial point at neighboring phases. 4D-CBCT reconstruction is achieved by minimizing a total energy containing a data fidelity term and the TNLM energy term. As for the image enhancement, 4D-CBCT images generated by the FDK algorithm are enhanced by minimizing the TNLM function while keeping the enhanced images close to the FDK results. A forward-backward splitting algorithm and a Gauss-Jacobi iteration method are employed to solve the problems. The algorithms implementation on

  13. Four-dimensional (4D) flow of the whole heart and great vessels using real-time respiratory self-gating

    DEFF Research Database (Denmark)

    Uribe, Sergio; Beerbaum, Philipp; Sørensen, Thomas Sangild

    2009-01-01

    Four-dimensional (4D) flow imaging has been used to study flow patterns and pathophysiology, usually focused on specific thoracic vessels and cardiac chambers. Whole-heart 4D flow at high measurement accuracy covering the entire thoracic cardiovascular system would be desirable to simplify...... and improve hemodynamic assessment. This has been a challenge because compensation of respiratory motion is difficult to achieve, but it is paramount to limit artifacts and improve accuracy. In this work we propose a self-gating technique for respiratory motion-compensation integrated into a whole-heart 4D...... flow acquisition that overcomes these challenges. Flow components are measured in all three directions for each pixel over the complete cardiac cycle, and 1D volume projections are obtained at certain time intervals for respiratory gating in real time during the acquisition. The technique was tested...

  14. A symplectic rearrangement of the four dimensional non-geometric scalar potential

    CERN Document Server

    Shukla, Pramod

    2015-01-01

    We present a symplectic rearrangement of the effective four-dimensional non-geometric scalar potential resulting from the type IIB superstring compactification on Calabi Yau orientifolds. The strategy has two main steps. In the first step, we rewrite the four dimensional scalar potential utilizing some interesting flux combinations which we call {\\it new generalized flux orbits}. After invoking a couple of non-trivial symplectic relations, in the second step, we further rearrange all the pieces of scalar potential into a completely `symplectic-formulation' which involves only the symplectic ingredients (such as period matrix etc.) without the need of knowing Calabi Yau metric. Moreover, the scalar potential under consideration is induced by a generic tree level K\\"{a}hler potential and (non-geometric) flux superpotential for arbitrary numbers of complex structure moduli, K\\"ahler moduli and odd-axions. Finally, we exemplify our symplectic formulation for the two well known toroidal examples based on type IIB ...

  15. Novel four-dimensional autonomous chaotic system generating one-, two-, three- and four-wing attractors

    Institute of Scientific and Technical Information of China (English)

    Yu Fei; Wang Chun-Hua; Yin Jin-Wen; Xu Hao

    2011-01-01

    In this paper,we propose a novel four-dimensional autonomous chaotic system.Of particular interest is that this novel system can generate one-,two,three- and four-wing chaotic attractors with the variation of a single parameter,and the multi-wing type of the chaotic attractors can be displayed in all directions.The system is simple with a large positive Lyapunov exponent and can exhibit some interesting and complicated dynamical behaviours.Basic dynamical properties of the four-dimensional chaotic system,such as equilibrium points,the Poincaré map,the bifurcation diagram and the Lyapunov exponents are investigated by using either theoretical analysis or numerical method.Finally,a circuit is designed for the implementation of the multi-wing chaotic attractors.The electronic workbench observations are in good agreement with the numerical simulation results.

  16. On the blow-up of four dimensional Ricci flow singularities

    CERN Document Server

    Máximo, Davi

    2012-01-01

    In this paper we prove a conjecture by Feldman-Ilmanen-Knopf in \\cite{FIK} that the gradient shrinking soliton metric they constructed on the tautological line bundle over $\\CP^1$ is the uniform limit of blow-ups of a type I Ricci flow singularity on a closed manifold. We use this result to show that limits of blow-ups of Ricci flow singularities on closed four dimensional manifolds do not necessarily have non-negative Ricci curvature.

  17. Exact four-dimensional dyonic black holes and Bertotti-Robinson spacetimes in string theory

    Science.gov (United States)

    Lowe, David A.; Strominger, Andrew

    1994-09-01

    Conformal field theories corresponding to two-dimensional electrically charged black holes and to two-dimensional anti-de Sitter space with a covariantly constant electric field are simply constructed as SL(2,openR)/openZ Wess-Zumino-Witten coset models. Four-dimensional spacetime solutions are obtained by tensoring these two-dimensional theories with SU(2)/Z(m) coset models. These describe a family of dyonic black holes and the Bertotti-Robinson universe.

  18. Poisson structure and Casimir functions for a noncentral dynamical system in four-dimensional phase space

    Institute of Scientific and Technical Information of China (English)

    Lou Zhi-Mei; Chen Zi-Dong; Wang Wen-Long

    2005-01-01

    In this paper, we express the differential equations of a noncentral dynamical system in Ermakov formalism to obtain the Ermakov invariant. In term of Hamiltonian theories and using the Ermakov invariant as the Hamiltonian,the Poisson structure of a noncentral dynamical system in four-dimensional phase space are constructed. The result indicates that the Poisson structure is degenerate and the noncentral dynamical system possesses four invariants: the Hamiltonian, the Ermakov invariant and two Casimir functions.

  19. Four-Dimensional Screening Anti-Counterfeiting Pattern by Inkjet Printed Photonic Crystals.

    Science.gov (United States)

    Hou, Jue; Zhang, Huacheng; Su, Bin; Li, Mingzhu; Yang, Qiang; Jiang, Lei; Song, Yanlin

    2016-10-06

    A four-dimensional screening anti-counterfeiting QR code composed of differently shaped photonic crystal (PC) dots has been fabricated that could display four images depending on different lighting conditions. By controlling the rheology of poly(dimethylsiloxane) (PDMS), three kinds of PC dots could be sequentially integrated into one pattern using the layer-by-layer printing strategy. The information can be encoded and stored in shapes and read out by the difference in optical properties.

  20. Haunted Kaluza universe with four-dimensional Lorentzian flat, Kerr, and Taub-NUT slices

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Rossen I. [Department of Pure and Applied Mathematics, Trinity College, University of Dublin (Ireland) and Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784 (Bulgaria)]. E-mail: ivanovr@tcd.ie; Prodanov, Emil M. [School of Physical Sciences, Dublin City University, Glasnevin (Ireland)]. E-mail: prodanov@physics.dcu.ie

    2005-03-03

    The duality between the original Kaluza's theory and Klein's subsequent modification is duality between slicing and threading decomposition of the five-dimensional spacetime. The field equations of the original Kaluza's theory lead to the interpretation of the four-dimensional Lorentzian Kerr and Taub-NUT solutions as resulting from static electric and magnetic charges and dipoles in the presence of ghost matter and constant dilaton, which models Newton's constant.

  1. Non-diagonal four-dimensional cohomogeneity-one Einstein metrics in various signatures

    CERN Document Server

    Dunajski, Maciej

    2016-01-01

    Most known four-dimensional cohomogeneity-one Einstein metrics are diagonal in the basis defined by the left-invariant one-forms, though some essentially non-diagonal ones are known. We consider the problem of explicitly seeking non-diagonal Einstein metrics, and we find solutions which in some cases exhaust the possibilities. In particular we construct new examples of neutral signature non--diagonal Bianchi type VIII Einstein metrics with self--dual Weyl tensor.

  2. Quantification of left and right atrial kinetic energy using four-dimensional intracardiac magnetic resonance imaging flow measurements.

    Science.gov (United States)

    Arvidsson, Per M; Töger, Johannes; Heiberg, Einar; Carlsson, Marcus; Arheden, Håkan

    2013-05-15

    Kinetic energy (KE) of atrial blood has been postulated as a possible contributor to ventricular filling. Therefore, we aimed to quantify the left (LA) and right (RA) atrial blood KE using cardiac magnetic resonance (CMR). Fifteen healthy volunteers underwent CMR at 3 T, including a four-dimensional phase-contrast flow sequence. Mean LA KE was lower than RA KE (1.1 ± 0.1 vs. 1.7 ± 0.1 mJ, P energy better than nonrotational flow did. The KE increase in early diastole was higher in the LA (P < 0.001). Systolic KE correlated with the combination of atrial volume and systolic velocity of the atrioventricular plane displacement (r(2) = 0.57 for LA and r(2) = 0.64 for RA). Early diastolic KE of the LA correlated with left ventricle (LV) mass (r(2) = 0.28), however, no such correlation was found in the right heart. This suggests that LA KE increases during early ventricular diastole due to LV elastic recoil, indicating that LV filling is dependent on diastolic suction. Right ventricle (RV) relaxation does not seem to contribute to atrial KE. Instead, RA KE generated during ventricular systole may be conserved in a hydraulic "flywheel" and transferred to the RV through helical flow, which may contribute to RV filling.

  3. Four-dimensional computed tomographic imaging in the wrist: proof of feasibility in a cadaveric model

    Energy Technology Data Exchange (ETDEWEB)

    Tay, Shian-Chao; Berger, Richard A. [Mayo Clinic College of Medicine, Orthopedics Biomechanics Laboratory, Rochester, MN (United States); Primak, Andrew N.; Amrami, Kimberly K. [Mayo Clinic College of Medicine, Department of Radiology, Rochester, MN (United States); Fletcher, Joel G.; McCollough, Cynthia H. [Mayo Clinic College of Medicine, Department of Radiology, Rochester, MN (United States); Mayo Clinic College of Medicine, CT Innovation Center, Rochester, MN (United States); Schmidt, Bernhard [Siemens Medical Solutions, Forchheim (Germany)

    2007-12-15

    High-resolution real-time three-dimensional (3D) imaging of the moving wrist may provide novel insights into the pathophysiology of joint instability. The purpose of this work was to assess the feasibility of using retrospectively gated spiral computed tomography (CT) to perform four-dimensional (4D) imaging of the moving wrist joint. A cadaver forearm from below the elbow was mounted on a motion simulator which performed radioulnar deviation of the wrist at 30 cycles per minute. An electronic trigger from the simulator provided the ''electrocardiogram'' (ECG) signal required for gated reconstructions. Four-dimensional and 3D images were compared by a blinded observer for image quality and presence of artifacts. Image quality of 4D images was found to be excellent at the extremes of radial and ulnar deviation (end-motion phases). Some artifacts were seen in mid-motion phases. 4D CT musculoskeletal imaging is feasible. Four-dimensional CT may allow clinicians to assess functional (dynamic) instabilities of the wrist joint. (orig.)

  4. Higher-order gravity in higher dimensions: geometrical origins of four-dimensional cosmology?

    Energy Technology Data Exchange (ETDEWEB)

    Troisi, Antonio [Universita degli Studi di Salerno, Dipartimento di Fisica ' ' E.R. Caianiello' ' , Salerno (Italy)

    2017-03-15

    Determining the cosmological field equations is still very much debated and led to a wide discussion around different theoretical proposals. A suitable conceptual scheme could be represented by gravity models that naturally generalize Einstein theory like higher-order gravity theories and higher-dimensional ones. Both of these two different approaches allow one to define, at the effective level, Einstein field equations equipped with source-like energy-momentum tensors of geometrical origin. In this paper, the possibility is discussed to develop a five-dimensional fourth-order gravity model whose lower-dimensional reduction could provide an interpretation of cosmological four-dimensional matter-energy components. We describe the basic concepts of the model, the complete field equations formalism and the 5-D to 4-D reduction procedure. Five-dimensional f(R) field equations turn out to be equivalent, on the four-dimensional hypersurfaces orthogonal to the extra coordinate, to an Einstein-like cosmological model with three matter-energy tensors related with higher derivative and higher-dimensional counter-terms. By considering the gravity model with f(R) = f{sub 0}R{sup n} the possibility is investigated to obtain five-dimensional power law solutions. The effective four-dimensional picture and the behaviour of the geometrically induced sources are finally outlined in correspondence to simple cases of such higher-dimensional solutions. (orig.)

  5. Non-critical string duals of four-dimensional CFTs with fundamental matter

    Energy Technology Data Exchange (ETDEWEB)

    Bigazzi, F. [LPTHE, Universites Paris VI et VII, 4 Place Jussieu, 75252 Paris cedex 05 (France); INFN, Piazza dei Caprettari, 70, 00186 Roma (Italy); Casero, R.; Paredes, A. [CPHT, Ecole Polytechnique, UMR de CNRS 7644, 91128 Palaiseau (France); Cotrone, A.L. [Departament ECM, Facultat de Fisica, Universitat de Barcelona and Institut de Fisica d' Altes Energies, Diagonal 647, 08028 Barcelona (Spain)

    2006-05-04

    The two-derivative approximation to non-critical strings is used as a qualitative tool to find solutions dual to four dimensional CFTs with matter in the fundamental. Two solutions are discussed: an AdS{sub 5} x S{sup 3}, which is dual to an N=1 SCFT only for a ratio of N{sub f}/N{sub c} and an AdS{sub 5} which is proposed to be dual to N=0 QCD in the conformal window. All solutions have curvatures of the order of the string scale. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  6. A Note On The Semiclassical Formulation Of BPS States In Four-Dimensional N=2 Theories

    CERN Document Server

    Brennan, T Daniel

    2016-01-01

    Vector spaces of (framed) BPS states of Lagrangian four-dimensional N=2 field theories can be defined in semiclassical chambers in terms of the $L^2$-cohomology of Dirac-like operators on monopole moduli spaces. This was spelled out previously for theories with only vectormultiplets, taking into account only a subset of the possible half-supersymmetric 't Hooft-Wilson line defects. This note completes the discussion by describing the modifications needed when including matter hypermultiplets together with arbitrary 't Hooft-Wilson line defects. Two applications of this extended discussion are given.

  7. Gravitational matter-antimatter asymmetry and four-dimensional Yang-Mills gauge symmetry

    Science.gov (United States)

    Hsu, J. P.

    1981-01-01

    A formulation of gravity based on the maximum four-dimensional Yang-Mills gauge symmetry is studied. The theory predicts that the gravitational force inside matter (fermions) is different from that inside antimatter. This difference could lead to the cosmic separation of matter and antimatter in the evolution of the universe. Moreover, a new gravitational long-range spin-force between two fermions is predicted, in addition to the usual Newtonian force. The geometrical foundation of such a gravitational theory is the Riemann-Cartan geometry, in which there is a torsion. The results of the theory for weak fields are consistent with previous experiments.

  8. Four-dimensional dose evaluation using deformable image registration in radiotherapy for liver cancer

    Energy Technology Data Exchange (ETDEWEB)

    Hoon Jung, Sang; Min Yoon, Sang; Ho Park, Sung; Cho, Byungchul; Won Park, Jae; Jung, Jinhong; Park, Jin-hong; Hoon Kim, Jong; Do Ahn, Seung [Departments of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 138-736 (Korea, Republic of)

    2013-01-15

    Purpose: In order to evaluate the dosimetric impact of respiratory motion on the dose delivered to the target volume and critical organs during free-breathing radiotherapy, a four-dimensional dose was evaluated using deformable image registration (DIR). Methods: Four-dimensional computed tomography (4DCT) images were acquired for 11 patients who were treated for liver cancer. Internal target volume-based treatment planning and dose calculation (3D dose) were performed using the end-exhalation phase images. The four-dimensional dose (4D dose) was calculated based on DIR of all phase images from 4DCT to the planned image. Dosimetric parameters from the 4D dose, were calculated and compared with those from the 3D dose. Results: There was no significant change of the dosimetric parameters for gross tumor volume (p > 0.05). The increase D{sub mean} and generalized equivalent uniform dose (gEUD) for liver were by 3.1%{+-} 3.3% (p= 0.003) and 2.8%{+-} 3.3% (p= 0.008), respectively, and for duodenum, they were decreased by 15.7%{+-} 11.2% (p= 0.003) and 15.1%{+-} 11.0% (p= 0.003), respectively. The D{sub max} and gEUD for stomach was decreased by 5.3%{+-} 5.8% (p= 0.003) and 9.7%{+-} 8.7% (p= 0.003), respectively. The D{sub max} and gEUD for right kidney was decreased by 11.2%{+-} 16.2% (p= 0.003) and 14.9%{+-} 16.8% (p= 0.005), respectively. For left kidney, D{sub max} and gEUD were decreased by 11.4%{+-} 11.0% (p= 0.003) and 12.8%{+-} 12.1% (p= 0.005), respectively. The NTCP values for duodenum and stomach were decreased by 8.4%{+-} 5.8% (p= 0.003) and 17.2%{+-} 13.7% (p= 0.003), respectively. Conclusions: The four-dimensional dose with a more realistic dose calculation accounting for respiratory motion revealed no significant difference in target coverage and potentially significant change in the physical and biological dosimetric parameters in normal organs during free-breathing treatment.

  9. A Four-Dimensional Continuum Theory of Space-Time and the Classical Physical Fields

    Directory of Open Access Journals (Sweden)

    Suhendro I.

    2007-10-01

    Full Text Available In this work, we attempt to describe the classical physical fields of gravity, electromagnetism, and the so-called intrinsic spin (chirality in terms of a set of fully geometrized constitutive equations. In our formalism, we treat the four-dimensional space-time continuum as a deformable medium and the classical fields as intrinsic stress and spin fields generated by infinitesimal displacements and rotations in the space-time continuum itself. In itself, the unifying continuum approach employed herein may suggest a possible unified field theory of the known classical physical fields.

  10. The violation of the No-Hair Conjecture in four-dimensional ungauged Supergravity

    CERN Document Server

    Bueno, Pablo

    2013-01-01

    By choosing a particular, String Theory inspired, Special K\\"ahler manifold, we are able to find a N=2 four-dimensional ungauged Supergravity model that contains supersymmetric black hole solutions that violate the folk uniqueness theorems that are expected to hold in ungauged Supergravity. The black hole solutions are regular in the sense that they have a positive mass and a unique physical singularity hidden by an event horizon. In contradistinction to the examples already known in the literature, we find our solutions in a theory without scalar potential, gaugings or higher order curvature terms.

  11. Exact four-dimensional dyonic black holes and Bertotti-Robinson spacetimes in string theory

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, D.A.; Strominger, A. (Department of Physics, University of California, Santa Barbara, California 93106-9530 (United States))

    1994-09-12

    Conformal field theories corresponding to two-dimensional electrically charged black holes and to two-dimensional anti-de Sitter space with a covariantly constant electric field are simply constructed as SL(2,[ital openR])/[ital openZ] Wess-Zumino-Witten coset models. Four-dimensional spacetime solutions are obtained by tensoring these two-dimensional theories with SU(2)/[ital Z]([ital m]) coset models. These describe a family of dyonic black holes and the Bertotti-Robinson universe.

  12. An accessible four-dimensional treatment of Maxwell's equations in terms of differential forms

    Science.gov (United States)

    Sá, Lucas

    2017-03-01

    Maxwell’s equations are derived in terms of differential forms in the four-dimensional Minkowski representation, starting from the three-dimensional vector calculus differential version of these equations. Introducing all the mathematical and physical concepts needed (including the tool of differential forms), using only knowledge of elementary vector calculus and the local vector version of Maxwell’s equations, the equations are reduced to a simple and elegant set of two equations for a unified quantity, the electromagnetic field. The treatment should be accessible for students taking a first course on electromagnetism.

  13. Six-dimensional Methods for Four-dimensional Conformal Field Theories II: Irreducible Fields

    CERN Document Server

    Weinberg, Steven

    2012-01-01

    This note supplements an earlier paper on conformal field theories. There it was shown how to construct tensor, spinor, and spinor-tensor primary fields in four dimensions from their counterparts in six dimensions, where conformal transformations act simply as SO(4,2) Lorentz transformations. Here we show how to constrain fields in six dimensions so that the corresponding primary fields in four dimensions transform according to irreducible representations of the four-dimensional Lorentz group, even when the irreducibility conditions on these representations involve the four-component Levi-Civita tensor $\\epsilon_{\\mu\

  14. Four-dimensional (4D) tracking of high-temperature microparticles

    Science.gov (United States)

    Wang, Zhehui; Liu, Q.; Waganaar, W.; Fontanese, J.; James, D.; Munsat, T.

    2016-11-01

    High-speed tracking of hot and molten microparticles in motion provides rich information about burning plasmas in magnetic fusion. An exploding-wire apparatus is used to produce moving high-temperature metallic microparticles and to develop four-dimensional (4D) or time-resolved 3D particle tracking techniques. The pinhole camera model and algorithms developed for computer vision are used for scene calibration and 4D reconstructions. 3D positions and velocities are then derived for different microparticles. Velocity resolution approaches 0.1 m/s by using the local constant velocity approximation.

  15. A four-dimensional description of five-dimensional N-brane models

    CERN Document Server

    Bloomfield, Jolyon K

    2010-01-01

    We propose a new method for obtaining the four-dimensional effective gravitational theory for five-dimensional braneworld models with arbitrary numbers of branes in a low energy regime, based on a two-lengthscale expansion. The method is straightforward and computationally efficient, and is applicable to both compactified and uncompactified models. Particular emphasis is placed on the behavior of the radion modes of the model, while the massive effective fields are automatically truncated. Generally, the radion modes are found to form a (N-1)-dimensional nonlinear sigma model. We illustrate the method for a N-brane model in an uncompactified extra dimension.

  16. Bifurcation structures and transient chaos in a four-dimensional Chua model

    Energy Technology Data Exchange (ETDEWEB)

    Hoff, Anderson, E-mail: hoffande@gmail.com; Silva, Denilson T. da; Manchein, Cesar, E-mail: cesar.manchein@udesc.br; Albuquerque, Holokx A., E-mail: holokx.albuquerque@udesc.br

    2014-01-10

    A four-dimensional four-parameter Chua model with cubic nonlinearity is studied applying numerical continuation and numerical solutions methods. Regarding numerical solution methods, its dynamics is characterized on Lyapunov and isoperiodic diagrams and regarding numerical continuation method, the bifurcation curves are obtained. Combining both methods the bifurcation structures of the model were obtained with the possibility to describe the shrimp-shaped domains and their endoskeletons. We study the effect of a parameter that controls the dimension of the system leading the model to present transient chaos with its corresponding basin of attraction being riddled.

  17. Quasinormal modes of four-dimensional topological nonlinear charged Lifshitz black holes

    Energy Technology Data Exchange (ETDEWEB)

    Becar, Ramon [Universidad Cato lica de Temuco, Departamento de Ciencias Matematicas y Fisicas, Temuco (Chile); Gonzalez, P.A. [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile); Vasquez, Yerko [Universidad de La Serena, Departamento de Fisica, Facultad de Ciencias, La Serena (Chile)

    2016-02-15

    We study scalar perturbations of four- dimensional topological nonlinear charged Lifshitz black holes with spherical and plane transverse sections, and we find numerically the quasinormal modes for scalar fields. Then we study the stability of these black holes under massive and massless scalar field perturbations. We focus our study on the dependence of the dynamical exponent, the nonlinear exponent, the angular momentum, and the mass of the scalar field in the modes. It is found that the modes are overdamped, depending strongly on the dynamical exponent and the angular momentum of the scalar field for a spherical transverse section. In contrast, for plane transverse sections the modes are always overdamped. (orig.)

  18. Non-critical holography and four-dimensional CFT's with fundamentals

    CERN Document Server

    Bigazzi, F; Cotrone, A L; Kiritsis, E; Paredes, A

    2005-01-01

    We find non-critical string backgrounds in five and eight dimensions, holographically related to four-dimensional conformal field theories with N=0 and N=1 supersymmetries. In the five-dimensional case we find an AdS_5 background metric for a string model related to non-supersymmetric, conformal QCD with large number of colors and flavors and discuss the conjectured existence of a conformal window from the point of view of our solution. In the eight-dimensional string theory, we build a family of solutions of the form AdS_5 x \\tilde{S}^3 with \\tilde{S}^3 a squashed three-sphere. For a special value of the ratio N_f/N_c, the background can be interpreted as the supersymmetric near-horizon limit of a system of color and flavor branes on R^{1,3} times a known four-dimensional generalization of the cigar. The N=1 dual theory with fundamental matter should have an IR fixed point only for a fixed ratio N_f/N_c. General features of the string/gauge theory correspondence for theories with fundamental flavors are also...

  19. Non-critical holography and four-dimensional CFT's with fundamentals

    Energy Technology Data Exchange (ETDEWEB)

    Bigazzi, Francesco [LPTHE, Universites Paris VI et VII, 4 place Jussieu, 75252 Paris cedex 05 (France); INFN, Piazza dei Caprettari 70, I-00186 Rome (Italy); Casero, Roberto [CPHT, Ecole Polytechnique, UMR du CNRS 7644, 91128 Palaiseau (France); Cotrone, Aldo Lorenzo [Departament ECM, Facultat de Fisica, Universitat de Barcelona, and Institut de Fisica d' Altes Energies, Diagonal 647, E-08028 Barcelona (Spain); Kiritsis, Elias [CPHT, Ecole Polytechnique, UMR du CNRS 7644, 91128 Palaiseau (France); Department of Physics, University of Crete, 71003 Heraklion (Greece); Paredes, Angel [CPHT, Ecole Polytechnique, UMR du CNRS 7644, 91128 Palaiseau (France)

    2005-10-15

    We find non-critical string backgrounds in five and eight dimensions, holographically related to four-dimensional conformal field theories with N 0 and N = 1 supersymmetries. In the five-dimensional case we find an AdS{sub 5} background metric for a string model related to non-supersymmetric, conformal QCD with large number of colors and flavors and discuss the conjectured existence of a conformal window from the point of view of our solution. In the eight-dimensional string theory, we build a family of solutions of the form AdS{sub 5} x S-tilde {sup 3} with S-tilde {sup 3} a squashed three-sphere. For a special value of the ratio N{sub f}/N{sub c}, the background can be interpreted as the supersymmetric near-horizon limit of a system of color and flavor branes on R{sup 1,3} times a known four-dimensional generalization of the cigar. The N = 1 dual theory with fundamental matter should have an IR fixed point only for a fixed ratio N{sub f}/N{sub c}. General features of the string/gauge theory correspondence for theories with fundamental flavors are also addressed.

  20. Current status of fetal neurodevelopmental assessment: Four-dimensional ultrasound study.

    Science.gov (United States)

    Hata, Toshiyuki

    2016-10-01

    With the latest advent of four-dimensional (4-D) ultrasound, fetal neurobehavioral or neurodevelopmental assessment can be easily and readily performed. Using this technique, typical fetal movements and behavioral patterns have become apparent in all three trimesters of pregnancy. In twin pregnancy, 4-D ultrasound facilitates the precise evaluation of inter-twin contact and intra-pair stimulation. New fetal neurobehavioral assessment tests, such as Kurjak's Antenatal Neurodevelopmental Test and the Fetal Observable Movement System, may reflect the normal and abnormal neurological development of the fetus, and will facilitate more precise assessments of fetal neurobehavior or neurodevelopment, and fetal brain and central nervous system functions. In this review article, I also discuss interesting topics regarding maternal and fetal stress, fetal pain, and fetal consciousness. Four-dimensional ultrasound has opened the door to new scientific fields, such as 'fetal neurology' and 'fetal psychology,' and fetal neurobehavioral science is at the dawn of a new era. Knowledge on fetal neurobehavior and neurodevelopment will be advanced through fetal behavioral research using this technique.

  1. Three- and four-dimensional visualization of magnetic resonance imaging data sets in pediatric cardiology.

    Science.gov (United States)

    Vick, G W

    2000-01-01

    The purpose of medical imaging technology in pediatric cardiology is to provide clear representations of the underlying anatomy and physiology of the cardiovascular system--representations that are easily understood and that facilitate clinical decision making. However, standard projective and tomographic imaging methods often yield results that are intelligible only to imaging specialists. Three- and four-dimensional reconstructions from projective and tomographic data sets are an alternative form of image display. Often, these reconstructions are more readily comprehensible as representations of the reality apparent in the operating room or the pathology laboratory than are the original data sets. Furthermore, viewing of these reconstructions is much more time efficient than viewing hundreds of separate tomographic images. Magnetic resonance imaging inherently provides three-, four-, and even higher dimensional data, and magnetic resonance data sets are commonly used to generate volumetric reconstructions. This review will focus on the practical application of magnetic resonance imaging to yield three- and four-dimensional reconstructions of pediatric cardiovascular disorders.

  2. A novel four-dimensional analytical approach for analysis of complex samples.

    Science.gov (United States)

    Stephan, Susanne; Jakob, Cornelia; Hippler, Jörg; Schmitz, Oliver J

    2016-05-01

    A two-dimensional LC (2D-LC) method, based on the work of Erni and Frei in 1978, was developed and coupled to an ion mobility-high-resolution mass spectrometer (IM-MS), which enabled the separation of complex samples in four dimensions (2D-LC, ion mobility spectrometry (IMS), and mass spectrometry (MS)). This approach works as a continuous multiheart-cutting LC system, using a long modulation time of 4 min, which allows the complete transfer of most of the first - dimension peaks to the second - dimension column without fractionation, in comparison to comprehensive two-dimensional liquid chromatography. Hence, each compound delivers only one peak in the second dimension, which simplifies the data handling even when ion mobility spectrometry as a third and mass spectrometry as a fourth dimension are introduced. The analysis of a plant extract from Ginkgo biloba shows the separation power of this four-dimensional separation method with a calculated total peak capacity of more than 8700. Furthermore, the advantage of ion mobility for characterizing unknown compounds by their collision cross section (CCS) and accurate mass in a non-target approach is shown for different matrices like plant extracts and coffee. Graphical abstract Principle of the four-dimensional separation.

  3. Four-dimensional conversion for spiritual leadership development: A missiological approach for African churches

    Directory of Open Access Journals (Sweden)

    Kalemba Mwambazambi

    2014-04-01

    Full Text Available The process of a four-dimensional conversion and/or transformation strives in helping the leadership of an organisation, especially such as the church, with practical ways that may lead to the development of an effective leadership by observing the four important aspects of human spirituality as elaborated on in the article. The spiritual, intellectual, moral and socio-political dimensions of the transformation can be catered for so that the complete inner being of humans, as well as their social and political attitudes and behaviours, can equally be transformed to maximum spiritual, personal and socio-political profitability. Mutombo-Mukendi demonstrates that the need for a spiritual leadership that can contribute to an effective transformation of Africa is dire, both for the church and the larger community. The real challenge is how to develop such leadership. This article provides intentional and practical ways that may lead to the development of the needed leadership. Four-dimensional transformation of people can be planned and carried out both in the church arena and in the surrounding communities. Skills development and transfer can also take place when skilled people from the church work with unskilled people from the community.

  4. On the existence of bifocal heteroclinic cycles in a class of four-dimensional piecewise affine systems

    Science.gov (United States)

    Wu, Tiantian; Yang, Xiao-Song

    2016-05-01

    Based on mathematical analysis, this paper provides a methodology to ensure the existence of heteroclinic cycles in a class of four-dimensional piecewise affine systems. In addition, examples are provided to illustrate the effectiveness of the method.

  5. Rotationally acquired four-dimensional optical coherence tomography of embryonic chick hearts using retrospective gating on the common central A-scan

    DEFF Research Database (Denmark)

    Happel, Christoph M.; Thommes, Jan; Thrane, Lars;

    2011-01-01

    We introduce a new method of rotational image acquisition for four-dimensional (4D) optical coherence tomography (OCT) of beating embryonic chick hearts. The rotational axis and the central A-scan of the OCT are identical. An out-of-phase image sequence covering multiple heartbeats is acquired...... at every angle of an incremental rotation of the deflection mirrors of the OCT system. Image acquisition is accomplished after a rotation of 180◦. Comparison of a displayed live M-mode of the central A-scan with a reference M-mode allows instant detection of translational movements of the embryo....... For calculation of 4D data sets, we apply an imagebased retrospective gating algorithm using the phase information of the common central A-scan present in all acquired images. This leads to cylindrical three-dimensional data sets for every time step of the cardiac cycle that can be used for 4D visualization...

  6. Classification of four-dimensional real Lie bialgebras of symplectic type and their Poisson-Lie groups

    Science.gov (United States)

    Abedi-Fardad, J.; Rezaei-Aghdam, A.; Haghighatdoost, Gh.

    2017-01-01

    We classify all four-dimensional real Lie bialgebras of symplectic type and obtain the classical r-matrices for these Lie bialgebras and Poisson structures on all the associated four-dimensional Poisson-Lie groups. We obtain some new integrable models where a Poisson-Lie group plays the role of the phase space and its dual Lie group plays the role of the symmetry group of the system.

  7. Quasinormal modes of a four-dimensional Lifshitz Black Hole in Conformal Gravity

    CERN Document Server

    Catalan, Marcela; Gonzalez, P A; Vasquez, Yerko

    2014-01-01

    We study the quasinormal modes of scalar perturbations for a four-dimensional asymptotically Lifshitz black hole in conformal gravity with dynamical exponent $z=0$ and spherical topology for the transverse section, and we find analytically the quasinormal modes for scalar fields for some special cases that depend of $Q$, where $Q=r_+^2/r_-^2$. One of them are the quasinormal modes for massive scalar fields for the mode with lowest angular momentum $(\\kappa=0)$, where we show that the Klein-Gordon equation can be written as a Riemann differential equation, and the quasinormal frequencies associated guarantees the stability of these black holes under scalar field perturbations for $Q>1$. Other case correspond to $Q=\\pm\\infty$, where the quasinormal frequencies guarantees the unstability of these black holes under scalar field perturbations. Finally, for the extremal case, that is $Q=1$, we show the absence of the quasinormal modes.

  8. Commissioning and quality assurance of Calypso four-dimensional target localization system in linear accelerator facility.

    Science.gov (United States)

    Muralidhar, K R; Komanduri, Krishna; Rout, Birendra Kumar; Ramesh, K K D

    2013-07-01

    Four dimensional (4D) target localization system (Calypso System) was installed at our hospital, which is equipped with Beacon Transponders, Console, Electromagnetic Array, Optical System, Tracking Station, Treatment table overlay, and Calypso kVue Couch top. The objective of this presentation is to describe the results of commissioning measurements carried out on the Calypso System to verify the manufacturer specifications and also to evolve a quality assurance (QA) procedure which can be used to test its performance routinely. The QA program consists of a series of tests (QA for checking the calibration or system accuracy, Camera Calibration with L-frame fixture, Camera Calibration with T-frame fixture, System calibration Fixture targets test, Localization, and Tracking). These tests were found to be useful to assess the performance of the Calypso System.

  9. Automated four-dimensional Monte Carlo workflow using log files and real-time motion monitoring

    Science.gov (United States)

    Sibolt, P.; Cronholm, R. O.; Heath, E.; Andersen, C. E.; Behrens, C. F.

    2017-05-01

    With emerging techniques for tracking and gating methods in radiotherapy of lung cancer patients, there is an increasing need for efficient four-dimensional Monte Carlo (4DMC) based quality assurance (QA). An automated and flexible workflow for 4DMC QA, based on the 4DdefDOSXYZnrc user code, has been developed in python. The workflow has been tested and verified using an in-house developed dosimetry system comprised of a dynamic thorax phantom constructed for plastic scintillator dosimetry. The workflow is directly compatible with any treatment planning system and can also be triggered by the appearance of linac log files. It has minimum user interaction and, with the use of linac log files, it provides a method for verification of the actually delivered dose in the patient geometry.

  10. Modeling lung motion using consistent image registration in four-dimensional computed tomography for radiation therapy

    Science.gov (United States)

    Lu, Wei; Song, Joo Hyun; Christensen, Gary E.; Parikh, Parag J.; Bradley, Jeffrey D.; Low, Daniel A.

    2006-03-01

    Respiratory motion is a significant source of error in conformal radiation therapy for the thorax and upper abdomen. Four-dimensional computed tomography (4D CT) has been proposed to reduce the uncertainty caused by internal respiratory organ motion. A 4D CT dataset is retrospectively reconstructed at various stages of a respiratory cycle. An important tool for 4D treatment planning is deformable image registration. An inverse consistent image registration is used to model lung motion from one respiratory stage to another during a breathing cycle. This diffeomorphic registration jointly estimates the forward and reverse transformations providing more accurate correspondence between two images. Registration results and modeled motions in the lung are shown for three example respiratory stages. The results demonstrate that the consistent image registration satisfactorily models the large motions in the lung, providing a useful tool for 4D planning and delivering.

  11. Berry curvature and four-dimensional monopoles in the relativistic chiral kinetic equation.

    Science.gov (United States)

    Chen, Jiunn-Wei; Pu, Shi; Wang, Qun; Wang, Xin-Nian

    2013-06-28

    We derive a relativistic chiral kinetic equation with manifest Lorentz covariance from Wigner functions of spin-1/2 massless fermions in a constant background electromagnetic field. It contains vorticity terms and a four-dimensional Euclidean Berry monopole which gives an axial anomaly. By integrating out the zeroth component of the 4-momentum p, we reproduce the previous three-dimensional results derived from the Hamiltonian approach, together with the newly derived vorticity terms. The phase space continuity equation has an anomalous source term proportional to the product of electric and magnetic fields (FσρF[over ˜]σρ∼EσBσ). This provides a unified interpretation of the chiral magnetic and vortical effects, chiral anomaly, Berry curvature, and the Berry monopole in the framework of Wigner functions.

  12. Portraying entanglement between molecular qubits with four-dimensional inelastic neutron scattering

    Science.gov (United States)

    Garlatti, E.; Guidi, T.; Ansbro, S.; Santini, P.; Amoretti, G.; Ollivier, J.; Mutka, H.; Timco, G.; Vitorica-Yrezabal, I. J.; Whitehead, G. F. S.; Winpenny, R. E. P.; Carretta, S.

    2017-01-01

    Entanglement is a crucial resource for quantum information processing and its detection and quantification is of paramount importance in many areas of current research. Weakly coupled molecular nanomagnets provide an ideal test bed for investigating entanglement between complex spin systems. However, entanglement in these systems has only been experimentally demonstrated rather indirectly by macroscopic techniques or by fitting trial model Hamiltonians to experimental data. Here we show that four-dimensional inelastic neutron scattering enables us to portray entanglement in weakly coupled molecular qubits and to quantify it. We exploit a prototype (Cr7Ni)2 supramolecular dimer as a benchmark to demonstrate the potential of this approach, which allows one to extract the concurrence in eigenstates of a dimer of molecular qubits without diagonalizing its full Hamiltonian. PMID:28216631

  13. Flame four-dimensional deflection tomography with compressed-sensing-revision reconstruction

    Science.gov (United States)

    Zhang, Bin; Zhao, Minmin; Liu, Zhigang; Wu, Zhaohang

    2016-08-01

    Deflection tomography with limited angle projections was investigated to visualize a premixed flame. A projection sampling system for deflection tomography was used to obtain chronological deflectogram arrays at six view angles with only a pair of gratings. A new iterative reconstruction algorithm with deflection angle compressed-sensing revision was developed to improve reconstruction-distribution quality from incomplete projection data. Numerical simulation and error analysis provided a good indication of algorithm precision and convergence. In the experiment, 150 fringes were processed, and temperature distributions in 20 cross-sections were reconstructed from projection data in four instants. Four-dimensional flame structures and temperature distributions in the flame interior were visualized using the visualization toolkit. The experimental reconstruction was then compared with the result obtained from computational fluid dynamic analysis.

  14. Structures of larger proteins in solution: Three- and four-dimensional heteronuclear NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gronenborn, A.M.; Clore, G.M. [National Institutes of Health, Bethesda, MD (United States)

    1994-12-01

    Complete understanding of a protein`s function and mechanism of action can only be achieved with a knowledge of its three-dimensional structure at atomic resolution. At present, there are two methods available for determining such structures. The first method, which has been established for many years, is x-ray diffraction of protein single crystals. The second method has blossomed only in the last 5 years and is based on the application of nuclear magnetic resonance (NMR) spectroscopy to proteins in solution. This review paper describes three- and four-dimensional NMR methods applied to protein structure determination and was adapted from Clore and Gronenborn. The review focuses on the underlying principals and practice of multidimensional NMR and the structural information obtained.

  15. New classes of bi-axially symmetric solutions to four-dimensional Vasiliev higher spin gravity

    CERN Document Server

    Sundell, Per

    2016-01-01

    We present new infinite-dimensional spaces of bi-axially symmetric asymptotically anti-de Sitter solutions to four-dimensional Vasiliev higher spin gravity, obtained by modifications of the Ansatz used in arXiv:1107.1217, which gave rise to a Type-D solution space. The current Ansatz is based on internal semigroup algebras (without identity) generated by exponentials formed out of the bi-axial symmetry generators. After having switched on the vacuum gauge function, the resulting generalized Weyl tensor is given by the sum of two generalized Petrov type-D tensors, and the twistor space connections are smooth in twistor space over finite regions of spacetime. We provide evidence for that the linearized twistor space connection can be brought to Vasiliev gauge.

  16. Transformation of general astigmatic Gaussian beams in a four-dimensional phase space

    Institute of Scientific and Technical Information of China (English)

    Baoxin Chen

    2006-01-01

    @@ A phase space model of two-dimensional (2D) Gaussian beam propagation is generalized for threedimensional (3D) general astigmatic Gaussian beam passing through first-order optical system. The general astigmatic Gaussian beam is represented by a four-dimensional (4D) phase super-ellipsoid that defined by an associated 4 × 4 real matrix, then the transformation formula of the phase super-ellipsoid of the beam through first-order optical system is derived. In particular, in the phase space framework, the beam propagation factor M2 value is proved to be a ratio of phase area of real beam to ideal beam, and a novel approach for a qualitative examination of the properties of fractional Fourier transform (FRT) for the beam is also provided.

  17. Impact on four dimensional dose accumulation using deformable image registration in liver stereotactic body radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Seong Hee; Kim, Tae Ho; Kim, Dong Su; Seong, Cheon Keum; Cho, Min Seok; Kim, Kyeong Hyeon; Suh, Tae Suk [Dept of. Biomedical Engineering, Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of); Park, So Hyun [Dept. of Radiation Oncology, Uijeongbu ST Mary' s Hospital, the Catholic University of Korea, Uijeongbu (Korea, Republic of); Kim, Si Yong [Dept. of Radiation Oncology, Virginia Commonwealth University, Richmond (United States)

    2014-11-15

    This study aims to evaluate the dosimetric effect of four-dimensional dose accumulation (4D dose) compared to 3D dose in liver stereotactic body radiotherapy (SBRT). Currently, SBRTT has been widely used to deliver highly conformal dose to target while sparing normal tissue. So, SBRT need accurate target delineation, dose calculation and motion management techniques such as breath-hold or abdominal compressor. In spite of the benefits about these techniques, there are still deformation and movement which could lead to reduce the probability for tumor control, imprecise prediction of normal tissue complication. 4D dose accumulation which can consider dosimetric effect of respiratory motion has a possibility to predict the more accurate delivered dose to target and normal organs and improve treatment accuracy.

  18. A pure Dirac's analysis for a four dimensional BF-like theory with a compact dimension

    CERN Document Server

    Escalante, Alberto

    2013-01-01

    In the context of extra dimensions, we perform a detailed Dirac's canonical analysis for a topological four dimensional BF-like theory. By performing the compactification process a la Kaluza-Klein, we find out the relevant symmetries of the theory, namely, the full structure of the constraints and the extended action. We show that the extended Hamiltonian is a linear combination of first class constraints, which means that the general covariance of the theory is not affected by the compactification process. Furthermore, in order to carry out the correct counting of physical degrees of freedom, we show that must be taken into account the reducibility conditions among the first class constraints associated to the excited KK modes. Finally, we perform the Hamiltonian analysis of Maxwell theory written as a $BF$-like theory, we analyze the constraints of the theory and the results obtained are compared with those found in the literature.

  19. Four-dimensional (4D) image reconstruction strategies in dynamic PET: beyond conventional independent frame reconstruction.

    Science.gov (United States)

    Rahmim, Arman; Tang, Jing; Zaidi, Habib

    2009-08-01

    In this article, the authors review novel techniques in the emerging field of spatiotemporal four-dimensional (4D) positron emission tomography (PET) image reconstruction. The conventional approach to dynamic PET imaging, involving independent reconstruction of individual PET frames, can suffer from limited temporal resolution, high noise (especially when higher frame sampling is introduced to better capture fast dynamics), as well as complex reconstructed image noise distributions that can be very difficult and time consuming to model in kinetic parameter estimation tasks. Various approaches that seek to address some or all of these limitations are described, including techniques that utilize (a) iterative temporal smoothing, (b) advanced temporal basis functions, (c) principal components transformation of the dynamic data, (d) wavelet-based techniques, as well as (e) direct kinetic parameter estimation methods. Future opportunities and challenges with regards to the adoption of 4D and higher dimensional image reconstruction techniques are also outlined.

  20. The a-theorem for the four-dimensional gauged vector model

    CERN Document Server

    Schnitzer, Howard J

    2014-01-01

    The discussion of renormalization group flows in four-dimensional conformal field theories has recently focused on the a-anomaly. It has recently been shown that there is a monotonic decreasing function which interpolates between the ultraviolet and infrared fixed points such that \\Delta a = a_UV - a_IR > 0. The analysis has been extended to weakly relevant and marginal deformations, though there are few explicit examples involving interacting theories. In this paper we examine the a-theorem in the context of the gauged vector model which couples the usual vector model to the Banks-Zaks model. We consider the model to leading order in the 1/N expansion, all orders in the coupling constant \\lambda, and to second order in g^2. The model has both an IR and UV fixed point, and satisfies \\Delta a > 0.

  1. Weak constraint four-dimensional variational data assimilation in a model of the California Current System

    Science.gov (United States)

    Crawford, William J.; Smith, Polly J.; Milliff, Ralph F.; Fiechter, Jerome; Wikle, Christopher K.; Edwards, Christopher A.; Moore, Andrew M.

    2016-12-01

    A new approach is explored for computing estimates of the error covariance associated with the intrinsic errors of a numerical forecast model in regions characterized by upwelling and downwelling. The approach used is based on a combination of strong constraint data assimilation, twin model experiments, linear inverse modeling, and Bayesian hierarchical modeling. The resulting model error covariance estimates Q are applied to a model of the California Current System using weak constraint four-dimensional variational (4D-Var) data assimilation to compute estimates of the ocean circulation. The results of this study show that the estimates of Q derived following our approach lead to demonstrable improvements in the model circulation estimates and isolate regions where model errors are likely to be important and that have been independently identified in the same model in previously published work.

  2. Four-dimensional data assimilation with optimized viscosity using High Resolution Doppler Lidar observations

    Science.gov (United States)

    Chai, Tianfeng; Lin, Ching-Long

    2001-11-01

    We present a four-dimensional variational data assimilation (4D-Var) technique with optimized eddy viscosity for the retrieval of the detailed atmospheric boundary-layer structures from High-Resolution Doppler Lidar (HRDL) radial velocity observations. The 4D-Var is based on the calculus of variations and optimal control theory to recover complete and dynamically consistent data set by minimizing the difference between limited observations and corresponding model predictions. To reflect the nature of the atmospheric boundary layer under various stability conditions, eddy viscosity is treated as part of control variables to be optimized in the 4D-Var model. The mathematical formulation for optimizing eddy viscosity is presented. The model is validated by conducting numerical experiments that utilize synthetic observations. We then apply the 4D-Var to the HRDL data measured under convective and stable conditions.

  3. On the existence of rigid spheres in four-dimensional spacetime manifolds

    CERN Document Server

    Gittel, Hans-Peter; Kijowski, Jerzy

    2015-01-01

    This paper deals with the generalization of usual round spheres in the flat Minkowski spacetime to the case of a generic four-dimensional spacetime manifold $M$. We consider geometric properties of sphere-like submanifolds in $M$ and introduce conditions on external curvature and torsion, which lead to a definition of a {\\em rigid sphere}. The main result is a local existence theorem concernig such spheres. For this purpose we apply the surjective implicit function theorem. The proof is based on a detailed analysis of the linearized problem and leads to an eight-parameter family of solutions in case when the metric tensor $g$ of $M$ is from a certain neighbourhood of the flat Minkowski metric. This contribution continues the study of rigid spheres in (Class. Quantum Grav. \\textbf{30} (2013), 175010, doi:10.1088/0264-9381/30/17/175010, 18 pp.).

  4. The transfer matrix method in four-dimensional causal dynamical triangulations

    CERN Document Server

    Ambjorn, J; Goerlich, A T; Jurkiewicz, J; Loll, R

    2013-01-01

    The Causal Dynamical Triangulation model of quantum gravity (CDT) is a proposition to evaluate the path integral over space-time geometries using a lattice regularization with a discrete proper time and geometries realized as simplicial manifolds. The model admits a Wick rotation to imaginary time for each space-time configuration. Using computer simulations we determined the phase structure of the model and discovered that it predicts a de Sitter phase with a four-dimensional spherical semi-classical background geometry. The model has a transfer matrix, relating spatial geometries at adjacent (discrete lattice) times. The transfer matrix uniquely determines the theory. We show that the measurements of the scale factor of the (CDT) universe are well described by an effective transfer matrix where the matrix elements are labelled only by the scale factor. Using computer simulations we determine the effective transfer matrix elements and show how they relate to an effective minisuperspace action at all scales.

  5. Nanomechanics and intermolecular forces of amyloid revealed by four-dimensional electron microscopy.

    Science.gov (United States)

    Fitzpatrick, Anthony W P; Vanacore, Giovanni M; Zewail, Ahmed H

    2015-03-17

    The amyloid state of polypeptides is a stable, highly organized structural form consisting of laterally associated β-sheet protofilaments that may be adopted as an alternative to the functional, native state. Identifying the balance of forces stabilizing amyloid is fundamental to understanding the wide accessibility of this state to peptides and proteins with unrelated primary sequences, various chain lengths, and widely differing native structures. Here, we use four-dimensional electron microscopy to demonstrate that the forces acting to stabilize amyloid at the atomic level are highly anisotropic, that an optimized interbackbone hydrogen-bonding network within β-sheets confers 20 times more rigidity on the structure than sequence-specific sidechain interactions between sheets, and that electrostatic attraction of protofilaments is only slightly stronger than these weak amphiphilic interactions. The potential biological relevance of the deposition of such a highly anisotropic biomaterial in vivo is discussed.

  6. Preventing Data Ambiguity in Infectious Diseases with Four-Dimensional and Personalized Evaluations.

    Directory of Open Access Journals (Sweden)

    Michelle J Iandiorio

    Full Text Available Diagnostic errors can occur, in infectious diseases, when anti-microbial immune responses involve several temporal scales. When responses span from nanosecond to week and larger temporal scales, any pre-selected temporal scale is likely to miss some (faster or slower responses. Hoping to prevent diagnostic errors, a pilot study was conducted to evaluate a four-dimensional (4D method that captures the complexity and dynamics of infectious diseases.Leukocyte-microbial-temporal data were explored in canine and human (bacterial and/or viral infections, with: (i a non-structured approach, which measures leukocytes or microbes in isolation; and (ii a structured method that assesses numerous combinations of interacting variables. Four alternatives of the structured method were tested: (i a noise-reduction oriented version, which generates a single (one data point-wide line of observations; (ii a version that measures complex, three-dimensional (3D data interactions; (iii a non-numerical version that displays temporal data directionality (arrows that connect pairs of consecutive observations; and (iv a full 4D (single line-, complexity-, directionality-based version.In all studies, the non-structured approach revealed non-interpretable (ambiguous data: observations numerically similar expressed different biological conditions, such as recovery and lack of recovery from infections. Ambiguity was also found when the data were structured as single lines. In contrast, two or more data subsets were distinguished and ambiguity was avoided when the data were structured as complex, 3D, single lines and, in addition, temporal data directionality was determined. The 4D method detected, even within one day, changes in immune profiles that occurred after antibiotics were prescribed.Infectious disease data may be ambiguous. Four-dimensional methods may prevent ambiguity, providing earlier, in vivo, dynamic, complex, and personalized information that facilitates both

  7. Toward four-dimensional image-guided adaptive brachytherapy in locally recurrent endometrial cancer.

    Science.gov (United States)

    Fokdal, Lars; Ørtoft, Gitte; Hansen, Estrid S; Røhl, Lisbeth; Pedersen, Erik Morre; Tanderup, Kari; Lindegaard, Jacob Christian

    2014-01-01

    To evaluate clinical outcome and feasibility of a four-dimensional image-guided adaptive brachytherapy concept in patients with locally recurrent endometrial cancer. Forty-three patients with locally recurrent endometrial cancer were included. Treatment consisted of conformal external beam radiotherapy followed by a boost using pulsed-dose-rate brachytherapy (BT). Large tumors were treated with MRI-guided interstitial BT. Small tumors were treated with CT-guided intracavitary BT. The planning aim (total external beam radiotherapy and BT) for high-risk clinical target volume was D90 > 80 Gy, whereas constraints for organs at risk were D2cc ≤ 90 Gy for bladder and D2cc ≤ 70 Gy for rectum, sigmoid, and bowel in terms of equivalent dose in 2 Gy fractions. Median high-risk clinical target volume was 18 cm(3) (range, 0-91). D90 was 82 Gy (range, 77-88). D2cc to bladder, rectum, and sigmoid were 67 Gy (range, 50-81), 67 Gy (range, 51-77), and 55 Gy (range, 44-68), respectively. Median followup was 30 months (6-88). Two-year local control rate was 92% (standard error [SE], 5). Disease-free survival rate and overall survival rate was 59% (SE, 8) and 78% (SE, 7), respectively. Patients with low- to intermediate-risk for recurrence had a 2-year disease-free survival rate of 72% (SE, 9) compared with 42% (SE, 12) in patients with high risk for recurrence (p = 0.04). Late morbidity Grade 3 was recorded in 5 (12%) patients. Four-dimensional image-guided adaptive brachytherapy is feasible in locally recurrent endometrial cancer. Local control rate is good. Systemic control remains a problem in patients with high risk for recurrence. Copyright © 2014 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  8. Four-dimensional address topology for circuits with stacked multilayer crossbar arrays.

    Science.gov (United States)

    Strukov, Dmitri B; Williams, R Stanley

    2009-12-01

    We present a topological framework that provides a simple yet powerful electronic circuit architecture for constructing and using multilayer crossbar arrays, allowing a significantly increased integration density of memristive crosspoint devices beyond the scaling limits of lateral feature sizes. The truly remarkable feature of such circuits, which is an extension of the CMOL (Cmos + MOLecular-scale devices) concept for an area-like interface to a three-dimensional system, is that a large-feature-size complimentary metal-oxide-semiconductor (CMOS) substrate can provide high-density interconnects to multiple crossbar layers through a single set of vertical vias. The physical locations of the memristive devices are mapped to a four-dimensional logical address space such that unique access from the CMOS substrate is provided to every device in a stacked array of crossbars. This hybrid architecture is compatible with digital memories, field-programmable gate arrays, and biologically inspired adaptive networks and with state-of-the-art integrated circuit foundries.

  9. Four-dimensional IMRT treatment planning using a DMLC motion-tracking algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Yelin [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA (United States); Sawant, Amit; Venkat, Raghu; Keall, Paul J [Department of Radiation Oncology, Stanford University, 875 Black Wilbur Drive, Stanford, CA 94305-5847 (United States)], E-mail: ysuh@stanford.edu

    2009-06-21

    The purpose of this study is to develop a four-dimensional (4D) intensity-modulated radiation therapy (IMRT) treatment-planning method by modifying and applying a dynamic multileaf collimator (DMLC) motion-tracking algorithm. The 4D radiotherapy treatment scenario investigated is to obtain a 4D treatment plan based on a 4D computed tomography (CT) planning scan and to have the delivery flexible enough to account for changes in tumor position during treatment delivery. For each of 4D CT planning scans from 12 lung cancer patients, a reference phase plan was created; with its MLC leaf positions and three-dimensional (3D) tumor motion, the DMLC motion-tracking algorithm generated MLC leaf sequences for the plans of other respiratory phases. Then, a deformable dose-summed 4D plan was created by merging the leaf sequences of individual phase plans. Individual phase plans, as well as the deformable dose-summed 4D plan, are similar for each patient, indicating that this method is dosimetrically robust to the variations of fractional time spent in respiratory phases on a given 4D CT planning scan. The 4D IMRT treatment-planning method utilizing the DMLC motion-tracking algorithm explicitly accounts for 3D tumor motion and thus hysteresis and nonlinear motion, and is deliverable on a linear accelerator.

  10. Four-Dimensional Ultrafast Electron Microscopy: Insights into an Emerging Technique

    KAUST Repository

    Adhikari, Aniruddha

    2016-12-15

    Four-dimensional ultrafast electron microscopy (4D-UEM) is a novel analytical technique that aims to fulfill the long-held dream of researchers to investigate materials at extremely short spatial and temporal resolutions by integrating the excellent spatial resolution of electron microscopes with the temporal resolution of ultrafast femtosecond laser-based spectroscopy. The ingenious use of pulsed photoelectrons to probe surfaces and volumes of materials enables time-resolved snapshots of the dynamics to be captured in a way hitherto impossible by other conventional techniques. The flexibility of 4D-UEM lies in the fact that it can be used in both the scanning (S-UEM) and transmission (UEM) modes depending upon the type of electron microscope involved. While UEM can be employed to monitor elementary structural changes and phase transitions in samples using real-space mapping, diffraction, electron energy-loss spectroscopy, and tomography, S-UEM is well suited to map ultrafast dynamical events on materials surfaces in space and time. This review provides an overview of the unique features that distinguish these techniques and also illustrates the applications of both S-UEM and UEM to a multitude of problems relevant to materials science and chemistry.

  11. Four-dimensional reconstruction of cultural heritage sites based on photogrammetry and clustering

    Science.gov (United States)

    Voulodimos, Athanasios; Doulamis, Nikolaos; Fritsch, Dieter; Makantasis, Konstantinos; Doulamis, Anastasios; Klein, Michael

    2017-01-01

    A system designed and developed for the three-dimensional (3-D) reconstruction of cultural heritage (CH) assets is presented. Two basic approaches are presented. The first one, resulting in an "approximate" 3-D model, uses images retrieved in online multimedia collections; it employs a clustering-based technique to perform content-based filtering and eliminate outliers that significantly reduce the performance of 3-D reconstruction frameworks. The second one is based on input image data acquired through terrestrial laser scanning, as well as close range and airborne photogrammetry; it follows a sophisticated multistep strategy, which leads to a "precise" 3-D model. Furthermore, the concept of change history maps is proposed to address the computational limitations involved in four-dimensional (4-D) modeling, i.e., capturing 3-D models of a CH landmark or site at different time instances. The system also comprises a presentation viewer, which manages the display of the multifaceted CH content collected and created. The described methods have been successfully applied and evaluated in challenging real-world scenarios, including the 4-D reconstruction of the historic Market Square of the German city of Calw in the context of the 4-D-CH-World EU project.

  12. Almost conformal transformation in a four dimensional Riemannian manifold with an additional structure

    CERN Document Server

    Dokuzova, Iva

    2011-01-01

    We consider a four dimensional Riemannian manifold M with a metric g and affinor structure q. The local coordinates of these tensors are circulant matrices. Their first orders are (A, B, C, B), A, B, C\\in FM and (0, 1, 0, 0), respectively. We construct another metric \\tilde{g} on M. We find the conditions for \\tilde{g} to be a positively defined metric, and for q to be a parallel structure with respect to the Riemannian connection of g. Further, let x be an arbitrary vector in T_{p}M, where p is a point on M. Let \\phi and \\phi be the angles between x and qx, x and q^{2}x with respect to g. We express the angles between x and qx, x and q^{2}x with respect to $\\tilde{g}$ with the help of the angles $\\phi$ and \\phi. Also,we construct two series {\\phi_{n}}and {\\phi_{n}}. We prove that every of it is an increasing one and it is converge.

  13. Coupling Ensemble Kalman Filter with Four-dimensional Variational Data Assimilation

    Institute of Scientific and Technical Information of China (English)

    Fuqing ZHANG; Meng ZHANG; James A. HANSEN

    2009-01-01

    This study examines the performance of coupling the deterministic four-dimensional variational assimilation system (4DVAR) with an ensemble Kalman filter (EnKF) to produce a superior hybrid approach for data assimilation. The coupled assimilation scheme (E4DVAR) benefits from using the state-dependent uncertainty provided by EnKF while taking advantage of 4DVAR in preventing filter divergence: the 4DVAR analysis produces posterior maximum likelihood solutions through minimization of a cost function about which the ensemble perturbations are transformed, and the resulting ensemble analysis can be propagated forward both for the next assimilation cycle and as a basis for ensemble forecasting. The feasibility and effectiveness of this coupled approach are demonstrated in an idealized model with simulated observations. It is found that the E4DVAR is capable of outperforming both 4DVAR and the EnKF under both perfect-and imperfect-model scenarios. The performance of the coupled scheme is also less sensitive to either the ensemble size or the assimilation window length than those for standard EnKF or 4DVAR implementations.

  14. Combining four dimensional variational data assimilation and particle filtering for estimating volcanic ash emissions

    Science.gov (United States)

    Franke, Philipp; Elbern, Hendrik

    2016-04-01

    Estimating volcanic ash emissions is a very challenging task due to limited monitoring capacities of the ash plume and nonlinear processes in the atmosphere, which renders application of source strength and injection height estimations difficult. Most models, which estimate volcanic ash emissions, make strong simplifications of the dispersion of volcanic ash and corresponding atmospheric processes. The objective of this work is to estimate volcanic ash emissions and simulate the ensuing dispersion applying a full chemistry transport model in a hybrid approach by using its adjoint as well as an ensemble of model runs to quantify forecast uncertainties. Therefore, the four dimensional variational data assimilation version of the EURAD-IM chemistry transport model is extended to include a Sequential Importance Resampling Smoother (SIRS), introducing novel weighting and resampling strategies. In the main SIRS step the ensemble members exchange high rated emission patterns while rejecting emission patterns with low value for the forecast. The emission profiles of the ensemble members are perturbed afterwards to guarantee different emissions for all ensemble members. First identical twin experiments show the ability of the system to estimate the temporal and vertical distribution of volcanic ash emissions. The 4D-var data assimilation algorithm of the new system additionally provides quantitative emission estimation.

  15. Four-Dimensional Ultrafast Electron Microscopy: Insights into an Emerging Technique.

    Science.gov (United States)

    Adhikari, Aniruddha; Eliason, Jeffrey K; Sun, Jingya; Bose, Riya; Flannigan, David J; Mohammed, Omar F

    2017-01-11

    Four-dimensional ultrafast electron microscopy (4D-UEM) is a novel analytical technique that aims to fulfill the long-held dream of researchers to investigate materials at extremely short spatial and temporal resolutions by integrating the excellent spatial resolution of electron microscopes with the temporal resolution of ultrafast femtosecond laser-based spectroscopy. The ingenious use of pulsed photoelectrons to probe surfaces and volumes of materials enables time-resolved snapshots of the dynamics to be captured in a way hitherto impossible by other conventional techniques. The flexibility of 4D-UEM lies in the fact that it can be used in both the scanning (S-UEM) and transmission (UEM) modes depending upon the type of electron microscope involved. While UEM can be employed to monitor elementary structural changes and phase transitions in samples using real-space mapping, diffraction, electron energy-loss spectroscopy, and tomography, S-UEM is well suited to map ultrafast dynamical events on materials surfaces in space and time. This review provides an overview of the unique features that distinguish these techniques and also illustrates the applications of both S-UEM and UEM to a multitude of problems relevant to materials science and chemistry.

  16. A four-dimensional virtual hand brain-machine interface using active dimension selection

    Science.gov (United States)

    Rouse, Adam G.

    2016-06-01

    Objective. Brain-machine interfaces (BMI) traditionally rely on a fixed, linear transformation from neural signals to an output state-space. In this study, the assumption that a BMI must control a fixed, orthogonal basis set was challenged and a novel active dimension selection (ADS) decoder was explored. Approach. ADS utilizes a two stage decoder by using neural signals to both (i) select an active dimension being controlled and (ii) control the velocity along the selected dimension. ADS decoding was tested in a monkey using 16 single units from premotor and primary motor cortex to successfully control a virtual hand avatar to move to eight different postures. Main results. Following training with the ADS decoder to control 2, 3, and then 4 dimensions, each emulating a grasp shape of the hand, performance reached 93% correct with a bit rate of 2.4 bits s-1 for eight targets. Selection of eight targets using ADS control was more efficient, as measured by bit rate, than either full four-dimensional control or computer assisted one-dimensional control. Significance. ADS decoding allows a user to quickly and efficiently select different hand postures. This novel decoding scheme represents a potential method to reduce the complexity of high-dimension BMI control of the hand.

  17. NOTE: Conceptual formulation on four-dimensional inverse planning for intensity modulated radiation therapy

    Science.gov (United States)

    Lee, Louis; Ma, Yunzhi; Ye, Yinyu; Xing, Lei

    2009-07-01

    Four-dimensional computed tomography (4DCT) offers an extra dimension of 'time' on the three-dimensional patient model with which we can incorporate target motion in radiation treatment (RT) planning and delivery in various ways such as in the concept of internal target volume, in gated treatment or in target tracking. However, for all these methodologies, different phases are essentially considered as non-interconnected independent phases for the purpose of optimization, in other words, the 'time' dimension has yet to be incorporated explicitly in the optimization algorithm and fully exploited. In this note, we have formulated a new 4D inverse planning technique that treats all the phases in the 4DCT as one single entity in the optimization. The optimization is formulated as a quadratic problem for disciplined convex programming that enables the problem to be analyzed and solved efficiently. In the proof-of-principle examples illustrated, we show that the temporal information of the spatial relation of the target and organs at risk could be 'exchanged' amongst different phases so that an appropriate weighting of dose deposition could be allocated to each phase, thus enabling a treatment with a tight target margin and a full duty cycle otherwise not achievable by either of the aforementioned methodologies. Yet there are practical issues to be solved in the 4D RT planning and delivery. The 4D concept in the optimization we have formulated here does provide insight on how the 'time' dimension can be exploited in the 4D optimization process.

  18. Four-dimensional measurement by a single-frame structured light method.

    Science.gov (United States)

    Sitnik, Robert

    2009-06-20

    A four-dimensional [4D--three-dimensional (3D) shape varying in time] shape measurement system is described. A single 3D shape of an object is calculated from only one frame. The projected pattern is composed of sinusoidal intensity fringes and one color-encoded stripe, the analysis of which allows us to find the absolute coordinates of the measured object. During measurement, the position of the stripe changes due to the improvement of the quality of spatiotemporal unwrapping. The fringes deformed by the shape of the object are captured by a CCD camera and processed by an adaptive spatial carrier phase-shifting algorithm. The use of an algorithm based on fast Fourier transformation is proposed to approximate the local period of fringes. A new phase-unwrapping routine based on the spatiotemporal information is presented as well. All these features make the 3D shape measurement of an object in motion possible with the additional advantage of using a low-cost system. Experimental results of the developed method together with a preliminary assessment of measurement uncertainty are presented to show the validity of the method.

  19. Quantum Mechanics and Black Holes in Four-Dimensional String Theory

    CERN Document Server

    Ellis, Jonathan Richard; Nanopoulos, Dimitri V

    1992-01-01

    In previous papers we have shown how strings in a two-dimensional target space reconcile quantum mechanics with general relativity, thanks to an infinite set of conserved quantum numbers, ``W-hair'', associated with topological soliton-like states. In this paper we extend these arguments to four dimensions, by considering explicitly the case of string black holes with radial symmetry. The key infinite-dimensional W-symmetry is associated with the $\\frac{SU(1,1)}{U(1)}$ coset structure of the dilaton-graviton sector that is a model-independent feature of spherically symmetric four-dimensional strings. Arguments are also given that the enormous number of string {\\it discrete (topological)} states account for the maintenance of quantum coherence during the (non-thermal) stringy evaporation process, as well as quenching the large Hawking-Bekenstein entropy associated with the black hole. Defining the latter as the measure of the loss of information for an observer at infinity, who - ignoring the higher string qua...

  20. Four-dimensional model of the lower extremity after total hip arthroplasty.

    Science.gov (United States)

    Otake, Yoshito; Suzuki, Naoki; Hattori, Asaki; Hagio, Keisuke; Sugano, Nobuhiko; Yonenobu, Kazuo; Ochi, Takahiro

    2005-12-01

    We have developed a four-dimensional (4D) model of the lower extremities after total hip arthroplasty in patients. The model can aid in preventing complications such as dislocation and wearing of the sliding surface. The skeletal structure and implant alignment were obtained from CT data. We applied registration method using CAD data to estimate accurate implant alignment from scattered CT data. The reconstructed three-dimensional (3D) skeletal model was combined with motion capture data that were acquired by an optical tracking system. We displayed the patient's skeletal movement and analyzed several parameters that relate to complications. The patient's skeletal model was superimposed onto video footage that was taken by a synchronized and calibrated digital video camera. For validation of the measurement error in this system, we used open MRI to evaluate the relative movement between skin markers and bones. This system visually represents not only the 3D anatomical structure, but also 4D dynamic functions that include the time sequential transitions of components and their positions. The open MRI results indicated that the average error in hip angle was within 5 degrees for each static posture. This system enables clinicians to analyze patient's motions on the basis of individual differences. We found that our system was an effective tool in providing precise guidance of daily postoperative motions that was individualized for each patient. This system will be applicable for surgical planning, assessment of postoperative activities, and the development of new surgical techniques, materials, and prosthetic designs.

  1. Four-Dimensional Coded Modulation with Bit-wise Decoders for Future Optical Communications

    CERN Document Server

    Alvarado, Alex

    2014-01-01

    Coded modulation (CM) is the combination of forward error correction (FEC) and multilevel constellations. Coherent optical communication systems result in a four-dimensional (4D) signal space, which naturally leads to 4D-CM transceivers. A practically attractive design paradigm is to use a bit-wise decoder, where the detection process is (suboptimally) separated into two steps: soft-decision demapping followed by binary decoding. In this paper, bit-wise decoders are studied from an information-theoretic viewpoint. 4D constellations with up to 4096 constellation points are considered. Metrics to predict the post-FEC bit-error rate (BER) of bit-wise decoders are analyzed. The mutual information is shown to fail at predicting the post-FEC BER of bit-wise decoders and the so-called generalized mutual information is shown to be a much more robust metric. It is also shown that constellations that transmit and receive information in each polarization and quadrature independently (e.g., PM-QPSK, PM-16QAM, and PM-64QA...

  2. Estimate of the Critical Exponent of the Anderson Transition in the Three and Four-Dimensional Unitary Universality Classes

    Science.gov (United States)

    Slevin, Keith; Ohtsuki, Tomi

    2016-10-01

    Disordered non-interacting systems are classified into ten symmetry classes, with the unitary class being the most fundamental. The three and four-dimensional unitary universality classes are attracting renewed interest because of their relation to three-dimensional Weyl semi-metals and four-dimensional topological insulators. Determining the critical exponent of the correlation/localisation length for the Anderson transition in these classes is important both theoretically and experimentally. Using the transfer matrix technique, we report numerical estimations of the critical exponent in a U(1) model in three and four dimensions.

  3. An automated method for comparing motion artifacts in cine four-dimensional computed tomography images.

    Science.gov (United States)

    Cui, Guoqiang; Jew, Brian; Hong, Julian C; Johnston, Eric W; Loo, Billy W; Maxim, Peter G

    2012-11-08

    The aim of this study is to develop an automated method to objectively compare motion artifacts in two four-dimensional computed tomography (4D CT) image sets, and identify the one that would appear to human observers with fewer or smaller artifacts. Our proposed method is based on the difference of the normalized correlation coefficients between edge slices at couch transitions, which we hypothesize may be a suitable metric to identify motion artifacts. We evaluated our method using ten pairs of 4D CT image sets that showed subtle differences in artifacts between images in a pair, which were identifiable by human observers. One set of 4D CT images was sorted using breathing traces in which our clinically implemented 4D CT sorting software miscalculated the respiratory phase, which expectedly led to artifacts in the images. The other set of images consisted of the same images; however, these were sorted using the same breathing traces but with corrected phases. Next we calculated the normalized correlation coefficients between edge slices at all couch transitions for all respiratory phases in both image sets to evaluate for motion artifacts. For nine image set pairs, our method identified the 4D CT sets sorted using the breathing traces with the corrected respiratory phase to result in images with fewer or smaller artifacts, whereas for one image pair, no difference was noted. Two observers independently assessed the accuracy of our method. Both observers identified 9 image sets that were sorted using the breathing traces with corrected respiratory phase as having fewer or smaller artifacts. In summary, using the 4D CT data of ten pairs of 4D CT image sets, we have demonstrated proof of principle that our method is able to replicate the results of two human observers in identifying the image set with fewer or smaller artifacts.

  4. Novel Assessment of Renal Motion in Children as Measured via Four-Dimensional Computed Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Pai Panandiker, Atmaram S., E-mail: atmaram.pai-panandiker@stjude.org [Department of Radiological Sciences, St. Jude Children' s Research Hospital, Memphis, TN (United States); Sharma, Shelly; Naik, Mihir H. [Department of Radiological Sciences, St. Jude Children' s Research Hospital, Memphis, TN (United States); Wu, Shengjie [Department of Biostatistics, St. Jude Children' s Research Hospital, Memphis, TN (United States); Hua, Chiaho; Beltran, Chris; Krasin, Matthew J.; Merchant, Thomas E. [Department of Radiological Sciences, St. Jude Children' s Research Hospital, Memphis, TN (United States)

    2012-04-01

    Objectives: Abdominal intensity-modulated radiation therapy and proton therapy require quantification of target and organ motion to optimize localization and treatment. Although addressed in adults, there is no available literature on this issue in pediatric patients. We assessed physiologic renal motion in pediatric patients. Methods and Materials: Twenty free-breathing pediatric patients at a median age of 8 years (range, 2-18 years) with intra-abdominal tumors underwent computed tomography simulation and four-dimensional computed tomography acquisition (slice thickness, 3 mm). Kidneys and diaphragms were contoured during eight phases of respiration to estimate center-of-mass motion. We quantified center of kidney mass mobility vectors in three dimensions: anteroposterior (AP), mediolateral (ML), and superoinferior (SI). Results: Kidney motion decreases linearly with decreasing age and height. The 95% confidence interval for the averaged minima and maxima of renal motion in children younger than 9 years was 5-9 mm in the ML direction, 4-11 mm in the AP direction, and 12-25 mm in the SI dimension for both kidneys. In children older than 9 years, the same confidence interval reveals a widening range of motion that was 5-16 mm in the ML direction, 6-17 mm in the AP direction, and 21-52 mm in the SI direction. Although not statistically significant, renal motion correlated with diaphragm motion in older patients. The correlation between diaphragm motion and body mass index was borderline (r = 0.52, p = 0.0816) in younger patients. Conclusions: Renal motion is age and height dependent. Measuring diaphragmatic motion alone does not reliably quantify pediatric renal motion. Renal motion in young children ranges from 5 to 25 mm in orientation-specific directions. The vectors of motion range from 5 to 52 mm in older children. These preliminary data represent novel analyses of pediatric intra-abdominal organ motion.

  5. A New Global Four-Dimensional Variational Ocean Data Assimilation System and Its Application

    Institute of Scientific and Technical Information of China (English)

    LIU Juan; WANG Bin; LIU Hailong; YU Yongqiang

    2008-01-01

    A four-dimensional variational data assimilation (4DVar) system of the LASG/IAP Climate Ocean Model, version 1.0 (LICOM1.0), named LICOM-3DVM, has been developed using the three-dimensional variational data assimilation of mapped observation (3DVM), a 4DVar method newly proposed in the past two years. Two experiments with 12-year model integrations were designed to validate it. One is the as- similation run, called ASSM, which incorporated the analyzed weekly sea surface temperature (SST) fields from Reynolds and Smith (OISST) between 1990 and 2001 once a week by the LICOM-3DVM. The other is the control run without any assimilation, named CTL. ASSM shows that the simulated temperatures of the upper ocean (above 50 meters), especially the SST of equatorial Pacific, coincide with the Tropic Atmo- sphere Ocean (TAO) mooring data, the World Ocean Atlas 2001 (WOA01) data and the Met Office Hadley Centre's sea ice and sea surface temperature (HadISST) data. It decreased the cold bias existing in CTL in the eastern Pacific and produced a Nino index that agrees with observation well. The validation results suggest that the LICOM-3DVM is able to effectively adjust the model results of the ocean temperature, although it's hard to correct the subsurface results and it even makes them worse in some areas due to the incorporation of only surface data. Future development of the LICOM-3DVM is to include subsurface in situ observations and satellite observations to further improve model simulations.

  6. Four-Dimensional Printing Hierarchy Scaffolds with Highly Biocompatible Smart Polymers for Tissue Engineering Applications.

    Science.gov (United States)

    Miao, Shida; Zhu, Wei; Castro, Nathan J; Leng, Jinsong; Zhang, Lijie Grace

    2016-10-01

    The objective of this study was to four-dimensional (4D) print novel biomimetic gradient tissue scaffolds with highly biocompatible naturally derived smart polymers. The term "4D printing" refers to the inherent smart shape transformation of fabricated constructs when implanted minimally invasively for seamless and dynamic integration. For this purpose, a series of novel shape memory polymers with excellent biocompatibility and tunable shape changing effects were synthesized and cured in the presence of three-dimensional printed sacrificial molds, which were subsequently dissolved to create controllable and graded porosity within the scaffold. Surface morphology, thermal, mechanical, and biocompatible properties as well as shape memory effects of the synthesized smart polymers and resultant porous scaffolds were characterized. Fourier transform infrared spectroscopy and gel content analysis confirmed the formation of chemical crosslinking by reacting polycaprolactone triol and castor oil with multi-isocyanate groups. Differential scanning calorimetry revealed an adjustable glass transition temperature in a range from -8°C to 35°C. Uniaxial compression testing indicated that the obtained polymers, possessing a highly crosslinked interpenetrating polymeric networks, have similar compressive modulus to polycaprolactone. Shape memory tests revealed that the smart polymers display finely tunable recovery speed and exhibit greater than 92% shape fixing at -18°C or 0°C and full shape recovery at physiological temperature. Scanning electron microscopy analysis of fabricated scaffolds revealed a graded microporous structure, which mimics the nonuniform distribution of porosity found within natural tissues. With polycaprolactone serving as a control, human bone marrow-derived mesenchymal stem cell adhesion, proliferation, and differentiation greatly increased on our novel smart polymers. The current work will significantly advance the future design and development of

  7. A novel system of four-dimensional motion analysis after total hip arthroplasty.

    Science.gov (United States)

    Hagio, Keisuke; Sugano, Nobuhiko; Nishii, Takashi; Miki, Hidenobu; Otake, Yoshito; Hattori, Asaki; Suzuki, Naoki; Yonenobu, Kazuo; Yoshikawa, Hideki; Ochi, Takahiro

    2004-05-01

    We have developed a novel system of four-dimensional motion analysis after total hip arthroplasty (THA) that can aid in preventing dislocation by assessing safe range of motion for patients in several daily activities. This system uses skeletal structure data from CT and motion capture data from an infrared position sensor. A 3-D model reconstructed from CT data is combined with the motion capture data. Using this system, we analyzed hip motion when getting up from and sitting down in a chair or picking up an object while sitting in a chair in 17 patients (26 hips) who underwent THA. To assess the accuracy of this system's measurements, open MRI was used to evaluate positions of skin markers against bones in five healthy volunteers in various postures. No impingement between bones and/or implants was found in any subjects during any activities. However, mean angle at the point of maximum hip flexion was different for each patient. The open MRI results indicated that average error in hip angle of the present system was within 5 degrees for each static posture. The functional position of the pelvis during daily activities must be taken into account when assessing the real risk of dislocation. The present system enables dynamic analysis involving not only alignment of components and bones of each patient, but also individual differences in characteristics of daily motions. Further investigation using this system can help determine safe ranges of motion for preventing hip dislocation, improving the accuracy of individualized guidance for patients regarding postoperative activities.

  8. Impact of four-dimensional data assimilation (FDDA) on urban climate analysis

    Science.gov (United States)

    Pan, Linlin; Liu, Yubao; Liu, Yuewei; Li, Lei; Jiang, Yin; Cheng, Will; Roux, Gregory

    2015-12-01

    This study investigates the impact of four-dimensional data assimilation (FDDA) on urban climate analysis, which employs the NCAR (National Center for Atmospheric Research) WRF (the weather research and forecasting model) based on climate FDDA (CFDDA) technology to develop an urban-scale microclimatology database for the Shenzhen area, a rapidly developing metropolitan located along the southern coast of China, where uniquely high-density observations, including ultrahigh-resolution surface AWS (automatic weather station) network, radio sounding, wind profilers, radiometers, and other weather observation platforms, have been installed. CFDDA is an innovative dynamical downscaling regional climate analysis system that assimilates diverse regional observations; and has been employed to produce a 5 year multiscale high-resolution microclimate analysis by assimilating high-density observations at Shenzhen area. The CFDDA system was configured with four nested-grid domains at grid sizes of 27, 9, 3, and 1 km, respectively. This research evaluates the impact of assimilating high-resolution observation data on reproducing the refining features of urban-scale circulations. Two experiments were conducted with a 5 year run using CFSR (climate forecast system reanalysis) as boundary and initial conditions: one with CFDDA and the other without. The comparisons of these two experiments with observations indicate that CFDDA greatly reduces the model analysis error and is able to realistically analyze the microscale features such as urban-rural-coastal circulation, land/sea breezes, and local-hilly terrain thermal circulations. It is demonstrated that the urbanization can produce 2.5 k differences in 2 m temperatures, delays/speeds up the land/sea breeze development, and interacts with local mountain-valley circulations.

  9. Do Human Fetuses Anticipate Self-Oriented Actions? A Study by Four-Dimensional (4D) Ultrasonography

    Science.gov (United States)

    Myowa-Yamakoshi, Masako; Takeshita, Hideko

    2006-01-01

    Using four-dimensional (4D) ultrasonography, arm and hand movements toward the face were examined in 27 human fetuses at 19 to 35 weeks of gestation, thereby enabling the continuous monitoring of their faces and other surface features such as the extremities. More than half of the observed arm movements resulted in the hand touching the mouth…

  10. Applying Computerized Adaptive Testing to the Four-Dimensional Symptom Questionnaire (4DSQ): A Simulation Study

    Science.gov (United States)

    de Beurs, Derek P; Terluin, Berend; Verhaak, Peter F

    2017-01-01

    Background Efficient screening questionnaires are useful in general practice. Computerized adaptive testing (CAT) is a method to improve the efficiency of questionnaires, as only the items that are particularly informative for a certain responder are dynamically selected. Objective The objective of this study was to test whether CAT could improve the efficiency of the Four-Dimensional Symptom Questionnaire (4DSQ), a frequently used self-report questionnaire designed to assess common psychosocial problems in general practice. Methods A simulation study was conducted using a sample of Dutch patients visiting a general practitioner (GP) with psychological problems (n=379). Responders completed a paper-and-pencil version of the 50-item 4DSQ and a psychometric evaluation was performed to check if the data agreed with item response theory (IRT) assumptions. Next, a CAT simulation was performed for each of the four 4DSQ scales (distress, depression, anxiety, and somatization), based on the given responses as if they had been collected through CAT. The following two stopping rules were applied for the administration of items: (1) stop if measurement precision is below a predefined level, or (2) stop if more than half of the items of the subscale are administered. Results In general, the items of each of the four scales agreed with IRT assumptions. Application of the first stopping rule reduced the length of the questionnaire by 38% (from 50 to 31 items on average). When the second stopping rule was also applied, the total number of items could be reduced by 56% (from 50 to 22 items on average). Conclusions CAT seems useful for improving the efficiency of the 4DSQ by 56% without losing a considerable amount of measurement precision. The CAT version of the 4DSQ may be useful as part of an online assessment to investigate the severity of mental health problems of patients visiting a GP. This simulation study is the first step needed for the development a CAT version of the 4

  11. Four dimensional variational data assimilation of species-resolved satellite-retrieved aerosol optical thickness

    Science.gov (United States)

    Nieradzik, Lars Peter; Elbern, Hendrik

    2010-05-01

    Aerosols play an increasingly important role in atmospheric modelling. They have a strong influence on the radiative transfer balance and a significant impact on human health. Their origin is various and so are its effects. Most of the measurement sites in Europe only account for an integrated aerosol load PMx (Particulate Matter of less than x μm in diameter) which does not give any qualitative information on the composition of the aerosol. Since very different constituents like mineral dust derived from desert storms and sea salt contribute to PMx it is necessary to make aerosol forcasts not only of load, but also type resolved. The source of information chosen for this study is the aerosol retrieval system SYNAER (SYNergetic AErosol Retrieval) from DLR-DFD that retrieves BLAOT (Boundary Layer Aerosol Optical Thickness) making use of both AATSR/SCIAMACHY and AVHRR/GOME-2 data respectively. Its strengths are a large spatial coverage, near real-time availability, and the classification of five intrinsic aerosol species, namely water-solubles, water-insolubles, soot, sea salt, and mineral dust which are furthermore size resolved in terms of modes. A widely known technique to enhance forecast skills of CTMs (Chemistry-Transport-Models) by ingesting in-situ and, especially, remote-sensing measurements is the method of four dimensional variational data assimilation (4Dvar). The EURAD-IM (EURopean Air pollution Dispersion - Inverse Model), containing a full adjoint gas-phase model, has been expanded with an adjoint of the MADE (Modal Aerosol Dynamics model for Europe) to optimise initial and boundary values for aerosols using 4Dvar. A forward and an adjoint radiative transfer model is driven by the EURAD-IM as mapping between BLAOT and internal aerosol species. Furthermore, its condensation scheme has been bypassed by an HDMR (High-Dimensional-Model-Representation) to ensure differentiability, and a time saving online NMC-module for the generation of the background

  12. Four dimensional variational assimilation of in-situ and remote-sensing aerosol data

    Science.gov (United States)

    Nieradzik, L. P.; Elbern, H.

    2012-04-01

    Aerosols play an increasingly important role in atmospheric modelling. They have a strong influence on the radiative transfer balance and a significant impact on human health. Their origin is various and so are its effects. Most of the measurement sites in Europe account for an integrated aerosol load PMx (Particulate Matter of less than x μm in diameter) which does not give any qualitative information on the composition of the aerosol. Since very different constituents contribute to PMx, like e.g. mineral dust derived from desert storms or sea salt, it is necessary to make aerosol forecasts not only of load, but also type resolved. The method of four dimensional variational data assimilation (4Dvar) is a widely known technique to enhance forecast skills of CTMs (Chemistry-Transport-Models) by ingesting in-situ and, especially, remote-sensing measurements. The EURAD-IM (EURopean Air pollution Dispersion - Inverse Model), containing a full adjoint gas-phase model, has been expanded with an adjoint of the MADE (Modal Aerosol Dynamics model for Europe) to optimise initial and boundary values for aerosols using 4Dvar. A forward and an adjoint radiative transfer model is driven by the EURAD-IM as mapping between BLAOT (Boundary Layer Aerosol Optical Thickness) and internal aerosol species. Furthermore, its condensation scheme has been bypassed by an HDMR (High-Dimensional-Model-Representation) to ensure differentiability. In this study both in-situ measured PMx as well as satellite retrieved aerosol optical thicknesses have been assimilated and the effect on forecast performance has been investigated. The source of BLAOT is the aerosol retrieval system SYNAER (SYNergetic AErosol Retrieval) from DLR-DFD that retrieves AOT by making use of both AATSR/SCIAMACHY and AVHRR/GOME-2 data respectively. Its strengths are a large spatial coverage, near real-time availability, and the classification of five intrinsic aerosol species, namely water-solubles, water-insolubles, soot

  13. A novel four-dimensional radiotherapy planning strategy from a tumor-tracking beam's eye view.

    Science.gov (United States)

    Li, Guang; Cohen, Patrice; Xie, Huchen; Low, Daniel; Li, Diana; Rimner, Andreas

    2012-11-21

    To investigate the feasibility of four-dimensional radiotherapy (4DRT) planning from a tumor-tracking beam's eye view (ttBEV) with reliable gross tumor volume (GTV) delineation, realistic normal tissue representation, high planning accuracy and low clinical workload, we propose and validate a novel 4D conformal planning strategy based on a synthesized 3.5D computed tomographic (3.5DCT) image with a motion-compensated tumor. To recreate patient anatomy from a ttBEV in the moving tumor coordinate system for 4DRT planning (or 4D planning), the centers of delineated GTVs in all phase CT images of 4DCT were aligned, and then the aligned CTs were averaged to produce a new 3.5DCT image. This GTV-motion-compensated CT contains a motionless target (with motion artifacts minimized) and motion-blurred normal tissues (with a realistic temporal density average). Semi-automatic threshold-based segmentation of the tumor, lung and body was applied, while manual delineation was used for other organs at risk (OARs). To validate this 3.5DCT-based 4D planning strategy, five patients with peripheral lung lesions of small size (form deformable image registration (DIR). The DVH(3.5D) (for the 3.5DCT plan) was compared with both iDVH(4D) and DVH(4D). To quantify the DVH difference between the 3.5DCT plan and the 4DCT plan, two methods were used: relative difference (%) of the areas underneath the DVH curves and the volumes receiving more than 20% (V20) and 50% (V50) of prescribed dose of these 4D plans. The volume of the delineated GTV from different phase CTs varied dramatically from 24% to 112% among the five patients, whereas the GTV from 3.5DCT deviated from the averaged GTV in 4DCT by only -6%±6%. For planning tumor volume (PTV) coverage, the difference between the DVH(3.5D) and iDVH(4D) was negligible (equivalent to the 4DCT plan with <1% dose difference to the PTV and negligible dose difference in OARs. The 3.5DCT approach simplifies 4D planning and provides accurate dose

  14. Finite-size scaling relations for a four-dimensional Ising model on Creutz cellular automatons

    Science.gov (United States)

    Merdan, Z.; Güzelsoy, E.

    2011-06-01

    The four-dimensional Ising model is simulated on Creutz cellular automatons using finite lattices with linear dimensions 4 ≤ L ≤ 8. The temperature variations and finite-size scaling plots of the specific heat and the Binder parameter verify the theoretically predicted expression near the infinite lattice critical temperature for 7, 14, and 21 independent simulations. Approximate values for the critical temperature of the infinite lattice of Tc(∞) = 6.6965(35), 6.6961(30), 6.6960(12), 6.6800(3), 6.6801(2), 6.6802(1) and 6.6925(22) (without the logarithmic factor), 6.6921(22) (without the logarithmic factor), 6.6909(2) (without the logarithmic factor), 6.6822(13) (with the logarithmic factor), 6.6819(11) (with the logarithmic factor), and 6.6808(8) (with the logarithmic factor) are obtained from the intersection points of the specific heat curves, the Binder parameter curves, and straight line fits of specific heat maxima for 7, 14, and 21 independent simulations, respectively. As the number of independent simulations increases, the results, 6.6802(1) and 6.6808(8), are in very good agreement with the results of a series expansion of Tc(∞), 6.6817(15) and 6.6802(2), the dynamic Monte Carlo value Tc(∞) = 6.6803(1), the cluster Monte Carlo value Tc(∞) = 6.680(1), and the Monte Carlo value using the Metropolis-Wolff cluster algorithm Tc(∞) = 6.6802632 ± 5 . 10-5. The average values calculated for the critical exponent of the specific heat are α =- 0.0402(15), - 0.0393(12), - 0.0391(11) with 7, 14, and 21 independent simulations, respectively. As the number of independent simulations increases, the result, α =- 0.0391(11), agrees with the series expansions result, α =- 0.12 ± 0.03 and the Monte Carlo result using the Metropolis-Wolff cluster algorithm, α ≥ 0 ± 0.04. However, α =- 0.0391(11) is inconsistent with the renormalization group prediction of α = 0.

  15. GPU-based four-dimensional general-relativistic ray tracing

    Science.gov (United States)

    Kuchelmeister, Daniel; Müller, Thomas; Ament, Marco; Wunner, Günter; Weiskopf, Daniel

    2012-10-01

    This paper presents a new general-relativistic ray tracer that enables image synthesis on an interactive basis by exploiting the performance of graphics processing units (GPUs). The application is capable of visualizing the distortion of the stellar background as well as trajectories of moving astronomical objects orbiting a compact mass. Its source code includes metric definitions for the Schwarzschild and Kerr spacetimes that can be easily extended to other metric definitions, relying on its object-oriented design. The basic functionality features a scene description interface based on the scripting language Lua, real-time image output, and the ability to edit almost every parameter at runtime. The ray tracing code itself is implemented for parallel execution on the GPU using NVidia's Compute Unified Device Architecture (CUDA), which leads to performance improvement of an order of magnitude compared to a single CPU and makes the application competitive with small CPU cluster architectures. Program summary Program title: GpuRay4D Catalog identifier: AEMV_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEMV_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 73649 No. of bytes in distributed program, including test data, etc.: 1334251 Distribution format: tar.gz Programming language: C++, CUDA. Computer: Linux platforms with a NVidia CUDA enabled GPU (Compute Capability 1.3 or higher), C++ compiler, NVCC (The CUDA Compiler Driver). Operating system: Linux. RAM: 2 GB Classification: 1.5. External routines: OpenGL Utility Toolkit development files, NVidia CUDA Toolkit 3.2, Lua5.2 Nature of problem: Ray tracing in four-dimensional Lorentzian spacetimes. Solution method: Numerical integration of light rays, GPU-based parallel programming using CUDA, 3D

  16. Dose and Position Measurements using a Novel Four-Dimensional In Vivo Dosimetry System

    Science.gov (United States)

    Cherpak, Amanda

    This work presents a comprehensive characterization of the dosimetric and position measurement characteristics as well as clinical implementation of a novel four-dimensional in vivo dosimetry system, RADPOS. Preliminary dose and position measurements were first conducted to evaluate any deviation from known characteristics of metal-oxide semiconductor field-effect transistors, MOSFETs, and electromagnetic positioning systems when they are used alone. The system was then combined with a deformable tissue equivalent lung phantom to simulate respiratory-induced tumour motion and lung deformation and to evaluate the potential use of the system as an effective quality assurance tool for 4D conformal radiotherapy. The final phase of testing involved using the RADPOS 4D in vivo dosimetry system in two different clinical trials. The first involved characterizing the breathing patterns of lung cancer patients throughout the course of treatment and measuring inter-fraction variations in skin dose. Within this framework, the feasibility of general use of the RADPOS system on patients during daily treatment fractions was also assessed. The second trial involved a modified RADPOS detector that contained a MOSFET array, allowing for dose measurements at five different points. This detector was used to measure dose and position in the prostatic urethra throughout seed implantation for transperineal interstitial permanent prostate brachytherapy. It has been found that the dosimetric response is similar to that of a microMOSFET, when used alone, aside from a slightly higher variation in angular response. Position measurements can be obtained with an uncertainty of +/- 2 mm when the detector remains within a specific optimal volume with respect to the magnetic field transmitter and when interfering metal objects are kept at least 200 mm away. Combining the RADPOS system with a deformable lung equivalent phantom allowed for efficient quality assurance of 4D radiation therapy, as

  17. Physical performance evaluation of a 256-slice CT-scanner for four-dimensional imaging.

    Science.gov (United States)

    Mori, Shinichiro; Endo, Masahiro; Tsunoo, Takanori; Kandatsu, Susumu; Tanada, Shuji; Aradate, Hiroshi; Saito, Yasuo; Miyazaki, Hiroaki; Satoh, Kazumasa; Matsushita, Satoshi; Kusakabe, Masahiro

    2004-06-01

    We have developed a prototype 256-slice CT-scanner for four-dimensional (4D) imaging that employs continuous rotations of a cone-beam. Since a cone-beam scan along a circular orbit does not collect a complete set of data to make an exact reconstruction of a volume [three-dimensional (3D) image], it might cause disadvantages or artifacts. To examine effects of the cone-beam data collection on image quality, we have evaluated physical performance of the prototype 256-slice CT-scanner with 0.5 mm slices and compared it to that of a 16-slice CT-scanner with 0.75 mm slices. As a result, we found that image noise, uniformity, and high contrast detectability were independent of z coordinate. A Feldkamp artifact was observed in distortion measurements. Full width at half maximum (FWHM) of slice sensitivity profiles (SSP) increased with z coordinate though it seemed to be caused by other reasons than incompleteness of data. With regard to low contrast detectability, smaller objects were detected more clearly at the midplane (z = 0 mm) than at z = 40 mm, though circular-band like artifacts affected detection. The comparison between the 16-slice and the 256-slice scanners showed better performance for the 16-slice scanner regarding the SSP, low contrast detectability, and distortion. The inferiorities of the 256-slice scanner in other than distortion measurement (Feldkamp artifact) seemed to be partly caused by the prototype nature of the scanner and should be improved in the future scanner. The image noise, uniformity, and high contrast detectability were almost identical for both CTs. The 256-slice scanner was superior to the 16-slice scanner regarding the PSF, though it was caused by the smaller transverse beam width of the 256-slice scanner. In order to compare both scanners comprehensively in terms of exposure dose, noise, slice thickness, and transverse spatial resolution, K=Dsigma2ha3 was calculated, where D was exposure dose (CT dose index), sigma was magnitude of

  18. Four-dimensional optical multiband-OFDM for beyond 1.4 Tb/s serial optical transmission.

    Science.gov (United States)

    Djordjevic, Ivan; Batshon, Hussam G; Xu, Lei; Wang, Ting

    2011-01-17

    We propose a four-dimensional (4D) coded multiband-OFDM scheme suitable for beyond 1.4 Tb/s serial optical transport. The proposed scheme organizes the N-dimensional (ND) signal constellation points in the form of signal matrix; employs 2D-inverse FFT and 2D-FFT to perform modulation and demodulation, respectively; and exploits both orthogonal polarizations. This scheme can fully exploit advantages of OFDM to deal with chromatic dispersion, PMD and PDL effects; and multidimensional signal constellations to improve OSNR sensitivity of conventional optical OFDM. The improvement of 4D-OFDM over corresponding polarization-multiplexed QAM (with the same number of constellation points) ranges from 1.79 dB for 16 signal constellation point-four-dimensional-OFDM (16-4D-OFDM) up to 4.53 dB for 128-4D-OFDM.

  19. A novel four-dimensional radiotherapy planning strategy from a tumor-tracking beam's eye view

    Science.gov (United States)

    Li, Guang; Cohen, Patrice; Xie, Huchen; Low, Daniel; Li, Diana; Rimner, Andreas

    2012-11-01

    To investigate the feasibility of four-dimensional radiotherapy (4DRT) planning from a tumor-tracking beam's eye view (ttBEV) with reliable gross tumor volume (GTV) delineation, realistic normal tissue representation, high planning accuracy and low clinical workload, we propose and validate a novel 4D conformal planning strategy based on a synthesized 3.5D computed tomographic (3.5DCT) image with a motion-compensated tumor. To recreate patient anatomy from a ttBEV in the moving tumor coordinate system for 4DRT planning (or 4D planning), the centers of delineated GTVs in all phase CT images of 4DCT were aligned, and then the aligned CTs were averaged to produce a new 3.5DCT image. This GTV-motion-compensated CT contains a motionless target (with motion artifacts minimized) and motion-blurred normal tissues (with a realistic temporal density average). Semi-automatic threshold-based segmentation of the tumor, lung and body was applied, while manual delineation was used for other organs at risk (OARs). To validate this 3.5DCT-based 4D planning strategy, five patients with peripheral lung lesions of small size (<5 cm3) and large motion range (1.2-3.5 cm) were retrospectively studied for stereotactic body radiotherapy (SBRT) using 3D conformal radiotherapy planning tools. The 3.5DCT-based 4D plan (3.5DCT plan) with 9-10 conformal beams was compared with the 4DCT-based 4D plan (4DCT plan). The 4DCT plan was derived from multiple 3D plans based on all phase CT images, each of which used the same conformal beam configuration but with an isocenter shift to aim at the moving tumor and a minor beam aperture and weighting adjustment to maintain plan conformality. The dose-volume histogram (DVH) of the 4DCT plan was created with two methods: one is an integrated DVH (iDVH4D), which is defined as the temporal average of all 3D-phase-plan DVHs, and the other (DVH4D) is based on the dose distribution in a reference phase CT image by dose warping from all phase plans using the

  20. Why is the World four-dimensional? Hermann Weyl’s 1955 argument and the topology of causation

    Science.gov (United States)

    De Bianchi, Silvia

    2017-08-01

    This paper approaches the question of space dimensionality by discussing a neglected argument proposed by Hermann Weyl in 1955. In Why is the World Four-Dimensional? (1955), Weyl offered a different argument from the one generally attributed to him and presented in Raum-Zeit-Materie. In the first sections of the paper, this new argument and its features are spelled-out, and in the last section, I shall develop some useful remarks on the concept of topology of causation that can still inform our reflection on the dimensionality of the world.

  1. Hemodynamic Measurement Using Four-Dimensional Phase-Contrast MRI: Quantification of Hemodynamic Parameters and Clinical Applications

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Hojin [POSTECH Biotech Center, Pohang University of Science and Technology, Pohang 37673 (Korea, Republic of); Kim, Guk Bae [Asan Institute of Life Science, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505 (Korea, Republic of); Kweon, Jihoon [Department of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505 (Korea, Republic of); Lee, Sang Joon [POSTECH Biotech Center, Pohang University of Science and Technology, Pohang 37673 (Korea, Republic of); Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang 37673 (Korea, Republic of); Kim, Young-Hak [Department of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505 (Korea, Republic of); Lee, Deok Hee; Yang, Dong Hyun [Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505 (Korea, Republic of); Kim, Namkug [Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505 (Korea, Republic of); Department of Convergence Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505 (Korea, Republic of)

    2016-11-01

    Recent improvements have been made to the use of time-resolved, three-dimensional phase-contrast (PC) magnetic resonance imaging (MRI), which is also named four-dimensional (4D) PC-MRI or 4D flow MRI, in the investigation of spatial and temporal variations in hemodynamic features in cardiovascular blood flow. The present article reviews the principle and analytical procedures of 4D PC-MRI. Various fluid dynamic biomarkers for possible clinical usage are also described, including wall shear stress, turbulent kinetic energy, and relative pressure. Lastly, this article provides an overview of the clinical applications of 4D PC-MRI in various cardiovascular regions.

  2. Hemodynamic measurement using four-dimensional phase-contrast MRI: Quantification of hemodynamic parameters and clinical applications

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Ho Jin; Lee, Sang Joon [POSTECH Biotech Center, Pohang University of Science and Technology, Pohang (Korea, Republic of); Kim, Guk Bae; Kweon, Ji Hoon; Kim, Young Hak; Lee, Deok Hee; Yang, Dong Hyun; KIm, Nam Kug [Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of)

    2016-07-15

    Recent improvements have been made to the use of time-resolved, three-dimensional phase-contrast (PC) magnetic resonance imaging (MRI), which is also named four-dimensional (4D) PC-MRI or 4D flow MRI, in the investigation of spatial and temporal variations in hemodynamic features in cardiovascular blood flow. The present article reviews the principle and analytical procedures of 4D PC-MRI. Various fluid dynamic biomarkers for possible clinical usage are also described, including wall shear stress, turbulent kinetic energy, and relative pressure. Lastly, this article provides an overview of the clinical applications of 4D PC-MRI in various cardiovascular regions.

  3. Four-dimensional anti-de Sitter black holes from a three-dimensional perspective Full complexity

    CERN Document Server

    Zanchin, V T; Lemos, J P S

    2002-01-01

    The dimensional reduction of black hole solutions in four-dimensional (4D) general relativity is performed and new 3D black hole solutions are obtained. Considering a 4D spacetime with one spacelike Killing vector, it is possible to split the Einstein-Hilbert-Maxwell action with a cosmological term in terms of 3D quantities. Definitions of quasilocal mass and charges in 3D spacetimes are reviewed. The analysis is then particularized to the toroidal charged rotating anti-de Sitter black hole. The reinterpretation of the fields and charges in terms of a three-dimensional point of view is given in each case, and the causal structure analyzed.

  4. Phantom-based evaluations of two binning algorithms for four-dimensional CT reconstruction in lung cancer radiation therapy

    Institute of Scientific and Technical Information of China (English)

    Fuli Zhang; Huayong Jiang; Weidong Xu; Yadi Wang ; Qingzhi Liu; Na Lu; Diandian Chen; Bo Yao

    2014-01-01

    Objective: The purpose of this study was to evaluate the performance of the phase-binning algorithm and am-plitude-binning algorithm for four-dimensional computed tomography (4DCT) reconstruction in lung cancer radiation therapy. Methods: Quasar phantom data were used for evaluation.Aphantom of known geometry was mounted on a four-dimensional (4D) motion platform programmed with twelve respiratory waves (twelve lung patients trajectories) and scanned with a Philips Bril iance Big bore 16-slice CT simulator. The 4DCT images were reconstructed using both phase- and amplitude-binning algorithms. Internal target volumes (ITVs) of the phase- and amplitude-binned image sets were compared by evaluation of shape and volume distortions. Results: The phantom experiments il ustrated that, as expected, maximum inhalation occurred at the 0% amplitude and maximum exhalation occurred at the 50% amplitude of the amplitude-binned 4DCT image sets. The amplitude-binned algorithm rendered smal er ITV than the phase-binning algorithm. Conclusion: The amplitude-binning algorithm for 4DCT reconstruction may have a potential advantage in reducing the margin and protecting normal lung tissue from unnecessary irradiation.

  5. Motion of particles on a Four-Dimensional Asymptotically AdS Black Hole with Scalar Hair

    CERN Document Server

    Gonzalez, P A; Vasquez, Yerko

    2015-01-01

    Motivated by black hole solutions with matter fields outside their horizon, we study the effect of these matter fields in the motion of massless and massive particles. We consider as background a four-dimensional asymptotically AdS black hole with scalar hair. The geodesics are studied numerically and we discuss about the differences in the motion of particles between the four-dimensional asymptotically AdS black holes with scalar hair and their no-hair limit, that is, Schwarzschild AdS black holes. Mainly, we found that there are bounded orbits like planetary orbits in this background. However, the periods associated to circular orbits are modified by the presence of the scalar hair. Besides, we found that some classical tests such as perihelion precession, deflection of light and gravitational time delay have the standard value of general relativity plus a correction term coming from the cosmological constant and the scalar hair. Finally, we found a specific value of the parameter associated to the scalar h...

  6. Motion of particles on a four-dimensional asymptotically AdS black hole with scalar hair

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, P.A.; Olivares, Marco [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile); Vasquez, Yerko [Universidad de La Serena, Departamento de Fisica, Facultad de Ciencias, La Serena (Chile)

    2015-10-15

    Motivated by black hole solutions with matter fields outside their horizon, we study the effect of these matter fields on the motion of massless and massive particles. We consider as background a four-dimensional asymptotically AdS black hole with scalar hair. The geodesics are studied numerically and we discuss the differences in the motion of particles between the four-dimensional asymptotically AdS black holes with scalar hair and their no-hair limit, that is, Schwarzschild AdS black holes. Mainly, we found that there are bounded orbits like planetary orbits in this background. However, the periods associated to circular orbits are modified by the presence of the scalar hair. Besides, we found that some classical tests such as perihelion precession, deflection of light, and gravitational time delay have the standard value of general relativity plus a correction term coming from the cosmological constant and the scalar hair. Finally, we found a specific value of the parameter associated to the scalar hair, in order to explain the discrepancy between the theory and the observations, for the perihelion precession of Mercury and light deflection. (orig.)

  7. An explicit four-dimensional variational data assimilation method based on the proper orthogonal decomposition: Theoretics and evaluation

    Institute of Scientific and Technical Information of China (English)

    TIAN XiangJun; XIE ZhengHui

    2009-01-01

    The proper orthogonal decomposition (POD) method is used to construct a set of basis functions for spanning the ensemble of data in a certain least squares optimal sense. Compared with the singular value decomposition (SVD), the POD basis functions can capture more energy in the forecast ensemble space and can represent its spatial structure and temporal evolution more effectively. After the analysis variables are expressed by a truncated expansion of the POD basis vectors in the ensemble space, the control variables appear explicitly in the cost function, so that the adjoint model, which is used to de-rive the gradient of the cost function with respect to the control variables, is no longer needed. The application of this new technique significantly simplifies the data assimilation process. Several as-similation experiments show that this POD-based explicit four-dimensional variational data assimila-tion method performs much better than the usual ensemble Kalman filter method on both enhancing the assimilation precision and reducing the computation cost. It is also better than the SVD-based ex-plicit four-dimensional assimilation method, especially when the forecast model is not perfect and the forecast error comes from both the noise of the initial filed and the uncertainty of the forecast model.

  8. Four-dimensional noise reduction using the time series of medical computed tomography datasets with short interval times: a static-phantom study

    Directory of Open Access Journals (Sweden)

    Tatsuya Nishii

    2016-02-01

    Full Text Available Backgrounds. This study examines the hypothesis that four-dimensional noise reduction (4DNR with short interval times reduces noise in cardiac computed tomography (CCT using “padding” phases. Furthermore, the capability of reducing the reduction dose in CCT using this post-processing technique was assessed. Methods. Using base and quarter radiation doses for CCT (456 and 114 mAs/rot with 120 kVp, a static phantom was scanned ten times with retrospective electrocardiogram gating, and 4DNR with short interval times (50 ms was performed using a post-processing technique. Differences in the computed tomography (CT attenuation, contrast-to-noise ratio (CNR and spatial resolution with modulation transfer function in each dose image obtained with and without 4DNR were assessed by conducting a Tukey–Kramer’s test and non-inferiority test. Results. For the base dose, by using 4DNR, the CNR was improved from 1.18 ± 0.15 to 2.08 ± 0.20 (P = 0.001, while the CT attenuation and spatial resolution of the image of 4DNR did not were significantly inferior to those of reference image (P < 0.001. CNRs of the quarter-dose image in 4DNR also improved to 1.28 ± 0.11, and were not inferior to those of the non-4DNR images of the base dose (P < 0.001. Conclusions. 4DNR with short interval times significantly reduced noise. Furthermore, applying this method to CCT would have the potential of reducing the radiation dose by 75%, while maintaining a similar image noise level.

  9. Investigating the Impact on Modeled Ozone Concentrations Using Meteorological Fields From WRF With and Updated Four-Dimensional Data Assimilation Approach”

    Science.gov (United States)

    The four-dimensional data assimilation (FDDA) technique in the Weather Research and Forecasting (WRF) meteorological model has recently undergone an important update from the original version. Previous evaluation results have demonstrated that the updated FDDA approach in WRF pr...

  10. Four-dimensional symmetry from a broad viewpoint. II Invariant distribution of quantized field oscillators and questions on infinities

    Science.gov (United States)

    Hsu, J. P.

    1983-01-01

    The foundation of the quantum field theory is changed by introducing a new universal probability principle into field operators: one single inherent and invariant probability distribution P(/k/) is postulated for boson and fermion field oscillators. This can be accomplished only when one treats the four-dimensional symmetry from a broad viewpoint. Special relativity is too restrictive to allow such a universal probability principle. A radical length, R, appears in physics through the probability distribution P(/k/). The force between two point particles vanishes when their relative distance tends to zero. This appears to be a general property for all forces and resembles the property of asymptotic freedom. The usual infinities in vacuum fluctuations and in local interactions, however complicated they may be, are all removed from quantum field theories. In appendix A a simple finite and unitary theory of unified electroweak interactions is discussed without assuming Higgs scalar bosons.

  11. Energy analysis of four dimensional extended hyperbolic Scarf I plus three dimensional separable trigonometric noncentral potentials using SUSY QM approach

    Science.gov (United States)

    Suparmi, A.; Cari, C.; Deta, U. A.; Handhika, J.

    2016-11-01

    The non-relativistic energies and wave functions of extended hyperbolic Scarf I plus separable non-central shape invariant potential in four dimensions are investigated using Supersymmetric Quantum Mechanics (SUSY QM) Approach. The three dimensional separable non-central shape invariant angular potential consists of trigonometric Scarf II, Manning Rosen and Poschl-Teller potentials. The four dimensional Schrodinger equation with separable shape invariant non-central potential is reduced into four one dimensional Schrodinger equations through variable separation method. By using SUSY QM, the non-relativistic energies and radial wave functions are obtained from radial Schrodinger equation, the orbital quantum numbers and angular wave functions are obtained from angular Schrodinger equations. The extended potential means there is perturbation terms in potential and cause the decrease in energy spectra of Scarf I potential.

  12. Prostate displacement during transabdominal ultrasound image-guided radiotherapy assessed by real-time four-dimensional transperineal monitoring

    DEFF Research Database (Denmark)

    Baker, Mariwan; Behrens, Claus F.

    2015-01-01

    Background. Transabdominal ultrasound (TAUS) imaging is currently available for localizing the prostate in daily image-guided radiotherapy (IGRT). The aim of this study was to determine the induced prostate displacement during such TAUS imaging. The prostate displacement was monitored using a novel...... transperineal four-dimensional (4D) US (TPUS) system. Material and methods. Ten prostate cancer patients, with a mean age of 68 years (58/76), were US scanned in the computed tomography (CT) room utilizing the Clarity 4D TPUS monitoring system. The patients were asked to comply with a moderate bladder fi lling...... a TAUS scan. The time dependent prostate displacements induced by the 2D probe pressure were recorded for the three orthogonal directions. In total 42 monitoring curves with applied 2D probe were recorded. Results. Data analysis of 42 US scans resulted in pressure induced prostate displacements with mean...

  13. Solving the four-dimensional {ital NN}-{pi}{ital NN} equations for scalars below the meson-production threshold

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, D.R.; Afnan, I.R. [Department of Physics, The Flinders University of South Australia, GPO Box 2100, Adelaide 5001 (Australia)

    1996-10-01

    The four-dimensional {ital NN}-{pi}{ital NN} equations are adapted to the case of scalar particles with a {phi}{sup 2}{sigma} interaction Lagrangian and solved for energies below the {sigma}-production threshold. This is achieved in the approximation where {phi}{sigma} scattering is dominated by the {ital s}-channel {phi}-pole term. The importance of the removal of double counting is investigated and a detailed comparison of the results of a covariant coupled-channel formulation and the Bethe-Salpeter equation in the ladder and ladder plus crossed-box approximations is presented. A brief discussion of the extension of the method to energies above the {sigma}-production threshold is given. {copyright} {ital 1996 The American Physical Society.}

  14. Solving the four-dimensional NN-πNN equations for scalars below the meson-production threshold

    Science.gov (United States)

    Phillips, D. R.; Afnan, I. R.

    1996-10-01

    The four-dimensional NN-πNN equations are adapted to the case of scalar particles with a φ2σ interaction Lagrangian and solved for energies below the σ-production threshold. This is achieved in the approximation where φσ scattering is dominated by the s-channel φ-pole term. The importance of the removal of double counting is investigated and a detailed comparison of the results of a covariant coupled-channel formulation and the Bethe-Salpeter equation in the ladder and ladder plus crossed-box approximations is presented. A brief discussion of the extension of the method to energies above the σ-production threshold is given.

  15. Measuring working memory is all fun and games: a four-dimensional spatial game predicts cognitive task performance.

    Science.gov (United States)

    Atkins, Sharona M; Sprenger, Amber M; Colflesh, Gregory J H; Briner, Timothy L; Buchanan, Jacob B; Chavis, Sydnee E; Chen, Sy-Yu; Iannuzzi, Gregory L; Kashtelyan, Vadim; Dowling, Eamon; Harbison, J Isaiah; Bolger, Donald J; Bunting, Michael F; Dougherty, Michael R

    2014-01-01

    We developed a novel four-dimensional spatial task called Shapebuilder and used it to predict performance on a wide variety of cognitive tasks. In six experiments, we illustrate that Shapebuilder: (1) Loads on a common factor with complex working memory (WM) span tasks and that it predicts performance on quantitative reasoning tasks and Ravens Progressive Matrices (Experiment 1), (2) Correlates well with traditional complex WM span tasks (Experiment 2), predicts performance on the conditional go/no go task (Experiment 3) and N-back (Experiment 4), and showed weak or nonsignificant correlations with the Attention Networks Task (Experiment 5), and task switching (Experiment 6). Shapebuilder shows that it exhibits minimal skew and kurtosis, and shows good reliability. We argue that Shapebuilder has many advantages over existing measures of WM, including the fact that it is largely language independent, is not prone to ceiling effects, and take less than 6 min to complete on average.

  16. Sensitivity of the model error parameter specification in weak-constraint four-dimensional variational data assimilation

    Science.gov (United States)

    Shaw, Jeremy A.; Daescu, Dacian N.

    2017-08-01

    This article presents the mathematical framework to evaluate the sensitivity of a forecast error aspect to the input parameters of a weak-constraint four-dimensional variational data assimilation system (w4D-Var DAS), extending the established theory from strong-constraint 4D-Var. Emphasis is placed on the derivation of the equations for evaluating the forecast sensitivity to parameters in the DAS representation of the model error statistics, including bias, standard deviation, and correlation structure. A novel adjoint-based procedure for adaptive tuning of the specified model error covariance matrix is introduced. Results from numerical convergence tests establish the validity of the model error sensitivity equations. Preliminary experiments providing a proof-of-concept are performed using the Lorenz multi-scale model to illustrate the theoretical concepts and potential benefits for practical applications.

  17. Non-critical, near extremal AdS6 background as a holographic laboratory of four dimensional YM theory

    Science.gov (United States)

    Kuperstein, S.; Sonnenschein, J.

    2004-11-01

    We study certain properties of the low energy regime of a theory which resembles four dimensional YM theory in the framework of a non-critical holographic gravity dual. We use for the latter the near extremal AdS6 non-critical SUGRA. We extract the glueball spectra that associates with the fluctuations of the dilaton, one form and the graviton and compare the results to those of the critical near extremal D4 model and lattice simulations. We show an area law behavior for the Wilson loop and screening for the 't Hooft loop. The Luscher term is found to be -(3π/24L). We derive the Regge trajectories of glueballs associated with the spinning folded string configurations.

  18. Testing a four-dimensional variational data assimilation method using an improved intermediate coupled model for ENSO analysis and prediction

    Science.gov (United States)

    Gao, Chuan; Wu, Xinrong; Zhang, Rong-Hua

    2016-07-01

    A four-dimensional variational (4D-Var) data assimilation method is implemented in an improved intermediate coupled model (ICM) of the tropical Pacific. A twin experiment is designed to evaluate the impact of the 4D-Var data assimilation algorithm on ENSO analysis and prediction based on the ICM. The model error is assumed to arise only from the parameter uncertainty. The "observation" of the SST anomaly, which is sampled from a "truth" model simulation that takes default parameter values and has Gaussian noise added, is directly assimilated into the assimilation model with its parameters set erroneously. Results show that 4D-Var effectively reduces the error of ENSO analysis and therefore improves the prediction skill of ENSO events compared with the non-assimilation case. These results provide a promising way for the ICM to achieve better real-time ENSO prediction.

  19. Four Dimensional Graphene

    CERN Document Server

    Drissi, L B; Bousmina, M

    2011-01-01

    Mimicking pristine 2D graphene, we revisit the BBTW model for 4D lattice QCD given in ref.[5] by using the hidden SU(5) symmetry of the 4D hyperdiamond lattice H_4. We first study the link between the H_4 and SU(5); then we refine the BBTW 4D lattice action by using the weight vectors \\lambda_1, \\lambda_2, \\lambda_3, \\lambda_4, \\lambda_5 of the 5-dimensional representation of SU(5) satisfying {\\Sigma}_i\\lambda_i=0. After that we study explicitly the solutions of the zeros of the Dirac operator D in terms of the SU(5) simple roots \\alpha_1, \\alpha_2, \\alpha_3, \\alpha_4 generating H_4; and its fundamental weights \\omega_1, \\omega_2, \\omega_3, \\omega_4 which generate the reciprocal lattice H_4^\\ast. It is shown, amongst others, that these zeros live at the sites of H_4^\\ast; and the continuous limit D is given by ((id\\surd5)/2) \\gamma^\\muk_\\mu with d, \\gamma^\\mu and k_\\mu standing respectively for the lattice parameter of H_4, the usual 4 Dirac matrices and the 4D wave vector. Other features such as differences ...

  20. Four-dimensional graphene

    Science.gov (United States)

    Drissi, L. B.; Saidi, E. H.; Bousmina, M.

    2011-07-01

    Mimicking pristine 2D graphene, we revisit the BBTW model for 4D lattice QCD given in [P. F. Bedaque , Phys. Rev. DPRVDAQ1550-7998 78, 017502 (2008)10.1103/PhysRevD.78.017502] by using the hidden SU(5) symmetry of the 4D hyperdiamond lattice H4. We first study the link between the H4 and SU(5); then we refine the BBTW 4D lattice action by using the weight vectors λ1, λ2, λ3, λ4, and λ5 of the five-dimensional representation of SU(5) satisfying ∑iλi=0. After that, we study explicitly the solutions of the zeros of the Dirac operator D in terms of the SU(5) simple roots α1, α2, α3, and α4 generating H4; and its fundamental weights ω1, ω2, ω3 ω4 which generate the reciprocal lattice H4*. It is shown, among others, that these zeros live at the sites of H4*; and the continuous limit D is given by (id5)/(2) γμkμ with d, γμ, and kμ standing, respectively, for the lattice parameter of H4, the usual 4 Dirac matrices and the 4D wave vector. Other features, such as differences with BBTW model as well as the link between the Dirac operator following from our construction and the one suggested by Creutz using quaternions, are also given.

  1. Investigation of four-dimensional computed tomography-based pulmonary ventilation imaging in patients with emphysematous lung regions.

    Science.gov (United States)

    Yamamoto, Tokihiro; Kabus, Sven; Klinder, Tobias; Lorenz, Cristian; von Berg, Jens; Blaffert, Thomas; Loo, Billy W; Keall, Paul J

    2011-04-07

    A pulmonary ventilation imaging technique based on four-dimensional (4D) computed tomography (CT) has advantages over existing techniques. However, physiologically accurate 4D-CT ventilation imaging has not been achieved in patients. The purpose of this study was to evaluate 4D-CT ventilation imaging by correlating ventilation with emphysema. Emphysematous lung regions are less ventilated and can be used as surrogates for low ventilation. We tested the hypothesis: 4D-CT ventilation in emphysematous lung regions is significantly lower than in non-emphysematous regions. Four-dimensional CT ventilation images were created for 12 patients with emphysematous lung regions as observed on CT, using a total of four combinations of two deformable image registration (DIR) algorithms: surface-based (DIR(sur)) and volumetric (DIR(vol)), and two metrics: Hounsfield unit (HU) change (V(HU)) and Jacobian determinant of deformation (V(Jac)), yielding four ventilation image sets per patient. Emphysematous lung regions were detected by density masking. We tested our hypothesis using the one-tailed t-test. Visually, different DIR algorithms and metrics yielded spatially variant 4D-CT ventilation images. The mean ventilation values in emphysematous lung regions were consistently lower than in non-emphysematous regions for all the combinations of DIR algorithms and metrics. V(HU) resulted in statistically significant differences for both DIR(sur) (0.14 ± 0.14 versus 0.29 ± 0.16, p = 0.01) and DIR(vol) (0.13 ± 0.13 versus 0.27 ± 0.15, p Jac) resulted in non-significant differences for both DIR(sur) (0.15 ± 0.07 versus 0.17 ± 0.08, p = 0.20) and DIR(vol) (0.17 ± 0.08 versus 0.19 ± 0.09, p = 0.30). This study demonstrated the strong correlation between the HU-based 4D-CT ventilation and emphysema, which indicates the potential for HU-based 4D-CT ventilation imaging to achieve high physiologic accuracy. A further study is needed to confirm these results.

  2. Theoretical study of different features of the fission process of excited nuclei in the framework of the modified statistical model and four-dimensional dynamical model

    Science.gov (United States)

    Eslamizadeh, H.

    2017-02-01

    Evaporation residue cross section, fission probability, anisotropy of fission fragment angular distribution, mass and energy distributions of fission fragments and the pre-scission neutron multiplicity for the excited compound nuclei {}168{{Y}}{{b}}, {}172{{Y}}{{b}}, {}178{{W}} and {}227{{P}}{{a}} produced in fusion reactions have been calculated in the framework of the modified statistical model and multidimensional dynamical model. In the dynamical calculations, the dynamics of fission of excited nuclei has been studied by solving three- and four-dimensional Langevin equations with dissipation generated through the chaos-weighted wall and window friction formula. Three collective shape coordinates plus the projection of total spin of the compound nucleus to the symmetry axis, K, were considered in the four-dimensional dynamical model. A non-constant dissipation coefficient of K, {γ }k, was applied in the four-dimensional dynamical calculations. A comparison of the results of the three- and four-dimensional dynamical models with the experimental data showed that the results of the four-dimensional dynamical model for the evaporation residue cross section, fission probability, anisotropy of fission fragment angular distribution, mass and energy distributions of fission fragments and the pre-scission neutron multiplicity are in better agreement with the experimental data. It was also shown that the modified statistical model can reproduce the above-mentioned experimental data by choosing appropriate values of the temperature coefficient of the effective potential, λ , and the scaling factor of the fission-barrier height, {r}s.

  3. Clocking the anisotropic lattice dynamics of multi-walled carbon nanotubes by four-dimensional ultrafast transmission electron microscopy

    Science.gov (United States)

    Cao, Gaolong; Sun, Shuaishuai; Li, Zhongwen; Tian, Huanfang; Yang, Huaixin; Li, Jianqi

    2015-02-01

    Recent advances in the four-dimensional ultrafast transmission electron microscope (4D-UTEM) with combined spatial and temporal resolutions have made it possible to directly visualize structural dynamics of materials at the atomic level. Herein, we report on our development on a 4D-UTEM which can be operated properly on either the photo-emission or the thermionic mode. We demonstrate its ability to obtain sequences of snapshots with high spatial and temporal resolutions in the study of lattice dynamics of the multi-walled carbon nanotubes (MWCNTs). This investigation provides an atomic level description of remarkable anisotropic lattice dynamics at the picosecond timescales. Moreover, our UTEM measurements clearly reveal that distinguishable lattice relaxations appear in intra-tubular sheets on an ultrafast timescale of a few picoseconds and after then an evident lattice expansion along the radial direction. These anisotropic behaviors in the MWCNTs are considered arising from the variety of chemical bonding, i.e. the weak van der Waals bonding between the tubular planes and the strong covalent sp2-hybridized bonds in the tubular sheets.

  4. String or brane-like solutions in four-dimensional Einstein gravity in the presence of cosmological constant

    CERN Document Server

    Lee, Youngone; Kim, Hyeong-Chan; Lee, Jungjai

    2011-01-01

    We investigate string or brane-like solutions for four-dimensional vacuum Einstein equations in the presence of cosmological constant. For the case of negative cosmological constant, the BTZ black string is the only warped stringlike solution. The general solutions for non-warped branelike configurations are found and they are characterized by the ADM mass density and two tensions. Interestingly, the sum of these tensions is equal to the minus of the mass density. Other than the well known black 2-brane and AdS soliton spacetimes, all the static solutions possess naked singularities. The time-dependent solutions can be regarded as the AdS extension of the well-known Kasner solutions. The speciality of those static regular solutions and the implication of singular solutions are also discussed in the context of cylindrical matter collapse. For the case of positive cosmological constant, the Kasner-de Sitter spacetime appears as time-dependent solutions and all static solutions are found to be naked singular.

  5. Restoration of four-dimensional diffeomorphism covariance in canonical general relativity: An intrinsic Hamilton-Jacobi approach

    Science.gov (United States)

    Salisbury, Donald; Renn, Jürgen; Sundermeyer, Kurt

    2016-02-01

    Classical background independence is reflected in Lagrangian general relativity through covariance under the full diffeomorphism group. We show how this independence can be maintained in a Hamilton-Jacobi approach that does not accord special privilege to any geometric structure. Intrinsic space-time curvature-based coordinates grant equal status to all geometric backgrounds. They play an essential role as a starting point for inequivalent semiclassical quantizations. The scheme calls into question Wheeler’s geometrodynamical approach and the associated Wheeler-DeWitt equation in which 3-metrics are featured geometrical objects. The formalism deals with variables that are manifestly invariant under the full diffeomorphism group. Yet, perhaps paradoxically, the liberty in selecting intrinsic coordinates is precisely as broad as is the original diffeomorphism freedom. We show how various ideas from the past five decades concerning the true degrees of freedom of general relativity can be interpreted in light of this new constrained Hamiltonian description. In particular, we show how the Kuchař multi-fingered time approach can be understood as a means of introducing full four-dimensional diffeomorphism invariants. Every choice of new phase space variables yields new Einstein-Hamilton-Jacobi constraining relations, and corresponding intrinsic Schrödinger equations. We show how to implement this freedom by canonical transformation of the intrinsic Hamiltonian. We also reinterpret and rectify significant work by Dittrich on the construction of “Dirac observables.”

  6. The finite-size scaling study of four-dimensional Ising model in the presence of external magnetic field

    Science.gov (United States)

    Merdan, Ziya; Kürkçü, Cihan; Öztürk, Mustafa K.

    2014-12-01

    The four-dimensional ferromagnetic Ising model in external magnetic field is simulated on the Creutz cellular automaton algorithm using finite-size lattices with linear dimension 4 ≤ L ≤ 8. The critical temperature value of infinite lattice, Tc χ ( ∞ ) = 6 , 680 (1) obtained for h = 0 agrees well with the values T c ( ∞ ) ≈ 6.68 obtained previously using different methods. Moreover, h = 0.00025 in our work also agrees with all the results obtained from h = 0 in the literature. However, there are no works for h ≠ 0 in the literature. The value of the field critical exponent (δ = 3.0136(3)) is in good agreement with δ = 3 which is obtained from scaling law of Widom. In spite of the finite-size scaling relations of | M L ( t ) | and χ L ( t ) for 0 ≤ h ≤ 0.001 are verified; however, in the cases of 0.0025 ≤ h ≤ 0.1 they are not verified.

  7. An Alternative View of the Universe Structure (on the invalidity of the four dimensional space-time concept)

    CERN Document Server

    Hovsepian, Felix

    2007-01-01

    The model of the Universe in this paper uses equations of the unperturbed Keplerian motion. They have been updated, complementied and generalized when the solution of these equations is the characteristic function of a random value from the theory of probabilities. Argument of the differential equation in this case is any more time, an interval of time between sections of a random stationary prosess. In this paper this time interval is referred to as flexible (elastic) time due to its many non-trivial properties. It is proved flexible time does not depend on the space which makes invalid the four dimensional space-time concept. The Universe becomes stationary and Eucledian. It is proved: 1. the advavce of Mercury's perihelion versus the predictions in accordance with the universal gravity law results inequality of the coefficients in the correlation equations of Keplerian moution along axes x, y and z; 2. the velocity of propagation of harmonic oscillation in the Uneverse is not constant; 3. long-range intera...

  8. Four-Dimensional Variational Data Assimilation Experiments for a Heavy Rain Case During the 2002 IOP in China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lin; NI Yunqi

    2005-01-01

    A heavy rainfall event along the mei-yu front during 22-23 June 2002 was chosen for this study. To assess the impact of the routine and additional IOP (intensive observation period) radiosonde observations on the mesoscale heavy rainfall forecast, a series of four-dimensional variational (4DVAR) data assimilation and model simulation experiments was conducted using nonhydrostatic mesoscale model MM5 and the MM5 4DVAR system. The effects of the intensive observations in the different areas on the heavy rainfall forecast were also investigated. The results showed that improvement of the forecast skill for mesoscale heavy rainfall intensity was possible from the assimilation of the IOP radiosonde observations. However,the impact of the IOP observations on the forecast of the rainfall pattern was not significant. Initial conditions obtained through the 4DVAR experiments with a 12-h assimilation window were capable of improving the 24-h forecast. The simulated results after the assimilation showed that it would be best to perform the intensive radiosonde observations in the upstream of the rainfall area and in the moisture passageway area at the same time. Initial conditions created by the 4DVAR led to the low-level moisture convergence over the rainfall area, enhanced frontogenesis and upward motion within the mei-yu front,and intensified middle- and high-level unstable stratification in front of the mei-yu front. Consequently,the heavy rainfall forecast was improved.

  9. Four-dimensional Cone Beam CT Reconstruction and Enhancement using a Temporal Non-Local Means Method

    CERN Document Server

    Jia, Xun; Lou, Yifei; Sonke, Jan-Jakob; Jiang, Steve B

    2012-01-01

    Four-dimensional Cone Beam Computed Tomography (4D-CBCT) has been developed to provide respiratory phase resolved volumetric imaging in image guided radiation therapy (IGRT). Inadequate number of projections in each phase bin results in low quality 4D-CBCT images with obvious streaking artifacts. In this work, we propose two novel 4D-CBCT algorithms: an iterative reconstruction algorithm and an enhancement algorithm, utilizing a temporal nonlocal means (TNLM) method. We define a TNLM energy term for a given set of 4D-CBCT images. Minimization of this term favors those 4D-CBCT images such that any anatomical features at one spatial point at one phase can be found in a nearby spatial point at neighboring phases. 4D-CBCT reconstruction is achieved by minimizing a total energy containing a data fidelity term and the TNLM energy term. As for the image enhancement, 4D-CBCT images generated by the FDK algorithm are enhanced by minimizing the TNLM function while keeping the enhanced images close to the FDK results. A...

  10. Fluctuation in measurements of pulmonary nodule under tidal volume ventilation on four-dimensional computed tomography: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Tateishi, Ukihide [National Cancer Center Hospital, Division of Diagnostic Radiology, Chuo-ku, Tokyo (Japan); Tsukagoshi, Shinsuke; Inokawa, Hiroyasu; Okumura, Miwa [Toshiba Medical Systems Corporation, CT Systems Development, Otawara (Japan); Moriyama, Noriyuki [National Cancer Center, Division of Cancer Screening, Research Center for Cancer Prevention and Screening, Tokyo (Japan)

    2008-10-15

    The present study aimed to assess the feasibility of four-dimensional (4D) chest computed tomography (CT) under tidal volume ventilation and the impact of respiratory motion on quantitative analysis of CT measurements. Forty-four pulmonary nodules in patients with metastatic disease were evaluated. CT examinations were performed using a 256 multidetector-row CT (MDCT) unit. Volume data were obtained from the lower lung fields (128 mm) above the diaphragm during dynamic CT acquisition. The CT parameters used were 120 kV, 100 or 150 mA, 0.5 s{sup -1}, and 0.5 mm collimation. Image data were reconstructed every 0.1 s during one respiratory cycle by a 180 reconstruction algorithm for four independent fractions of the respiratory cycle. Pulmonary nodules were measured along their longest and shortest axes using electronic calipers. Automated volumetry was assessed using commercially available software. The diameters of long and short axes in each frame were 9.0-9.6 mm and 7.1-7.5 mm, respectively. There was fluctuation of the long axis diameters in the third fraction. The mean volume in each fraction ranged from 365 to 394 mm{sup 3}. Statistically significant fluctuation was also found in the third fraction. 4D-CT under tidal volume ventilation is feasible to determine diameter or volume of the pulmonary nodule. (orig.)

  11. Generation and visualization of four-dimensional MR angiography data using an undersampled 3-D projection trajectory.

    Science.gov (United States)

    Liu, Jing; Redmond, Michael J; Brodsky, Ethan K; Alexander, Andrew L; Lu, Aiming; Thornton, Francis J; Schulte, Michael J; Grist, Thomas M; Pipe, James G; Block, Walter F

    2006-02-01

    Time-resolved contrast-enhanced magnetic resonance (MR) angiography (CE-MRA) has gained in popularity relative to X-ray Digital Subtraction Angiography because it provides three-dimensional (3-D) spatial resolution and it is less invasive. We have previously presented methods that improve temporal resolution in CE-MRA while providing high spatial resolution by employing an undersampled 3-D projection (3D PR) trajectory. The increased coverage and isotropic resolution of the 3D PR acquisition simplify visualization of the vasculature from any perspective. We present a new algorithm to develop a set of time-resolved 3-D image volumes by preferentially weighting the 3D PR data according to its acquisition time. An iterative algorithm computes a series of density compensation functions for a regridding reconstruction, one for each time frame, that exploit the variable sampling density in 3D PR. The iterative weighting procedure simplifies the calculation of appropriate density compensation for arbitrary sampling patterns, which improve sampling efficiency and, thus, signal-to-noise ratio and contrast-to-noise ratio, since it is does not require a closed-form calculation based on geometry. Current medical workstations can display these large four-dimensional studies, however, interactive cine animation of the data is only possible at significantly degraded resolution. Therefore, we also present a method for interactive visualization using powerful graphics cards and distributed processing. Results from volunteer and patient studies demonstrate the advantages of dynamic imaging with high spatial resolution.

  12. The effects of discontinuities in the Betts Miller cumulus convection scheme on four-dimensional variational data assimilation

    Science.gov (United States)

    Zupanski, Dušanka

    1993-10-01

    A tangent linear and an adjoint of the large-scale precipitation and the cumulus convection processes in the National Meteorological Center's NMC/ETA regional forecast model are developed. The effects of discontinuities in the Betts Miller cumulus convection scheme are examined and applicability of derivative minimization methods in four-dimensional variational (4D VAR) data assimilation is considered. It is demonstrated that discontinuities present in the control Betts Miller cumulus convection scheme increase linearization errors to a large extent and have adverse effects on 4D VAR data assimilation. In the experiments performed, discontinuities in the cumulus convection scheme have the most serious effect in low layers. These problems can be reduced by modifying the scheme to make it more continuous in low layers. Positive effects of inclusion of cumulus convection in 4D VAR data assimilation are found in upper layers, especially in humidity fields. The "observations" used are optimal interpolation analyses of temperature, surface pressure, wind and specific humidity. By inclusion of other data, more closely related to the convective processes, such as precipitation and clouds, more benefits should be expected. Even with the difficulties caused by discontinuities, derivative minimization techniques appear to work for the data assimilation problems. In order to get more general conclusions, more experiments are needed with different synoptic situations. The inclusion of other important physical processes such as radiation, surface friction and turbulence in the forecast and the corresponding adjoint models could alter the results since they may reinforce the effects of discontinuities.

  13. Validation of the four-dimensional symptom questionnaire (4DSQ) and prevalence of psychological symptoms in orthopedic shoulder patients.

    Science.gov (United States)

    Koorevaar, Rinco C T; Terluin, Berend; van 't Riet, Esther; Madden, Kim; Bulstra, Sjoerd K

    2016-04-01

    Psychological problems are common in shoulder patients. A validated psychological questionnaire measuring clinically relevant psychological symptoms (including distress, depression, anxiety, and somatization) in shoulder patients is lacking. The Four-Dimensional Symptom Questionnaire (4DSQ) is a self-report questionnaire to identify distress, depression, anxiety, and somatization which has been validated in primary care populations. The aim of this study was to validate the 4DSQ in orthopedic shoulder patients. We assessed whether the 4DSQ measures these four constructs the same way in an orthopedic population with shoulder problems compared to a general practice population. We also investigated the prevalence of psychological symptoms in shoulder patients. The shoulder group consisted of 200 consecutive patients and the general practice group comprised 368 patients, matched for gender and age. Differential item functioning analysis showed that the 4DSQ measures the different psychological symptoms in orthopedic shoulder patients the same way as in general practice patients. The shoulder patients tended to score higher on the somatization scale, resulting in a new cut-off point for somatization. The prevalence of distress, somatization, anxiety, and depression in the shoulder group was 23%, 14%, 10%, and 8%, respectively. It can be concluded from this study that the 4DSQ in orthopedic shoulder patients measures the same constructs as in general practice patients and can therefore be used in orthopedic practice to measure psychological symptoms in patients with shoulder complaints.

  14. Fast and exact method for computing a stack of images at various focuses from a four-dimensional light field

    Science.gov (United States)

    Mhabary, Ziv; Levi, Ofer; Small, Eran; Stern, Adrian

    2016-07-01

    This paper presents an efficient method for computing a stack of images digitally focused at various lengths from a four-dimensional light field (LF). The main contribution of this work is a fast and algebraically exact method that does not require interpolation in the frequency or spatial domains as alternative methods do. The proposed imaging operator combines two-dimensional (2-D) fast Fourier transform with 2-D fractional Fourier transform and has computational complexity of O(N log N), where N is the number of pixels in the LF tesseract of dimension N=nx×ny×nu×nv. The whole method consists of unitary vector-based operations; therefore, parallel implementation is easy and can contribute additional speed up. While current state of the art methods suffer from inherent tradeoff between the reconstruction quality and computational complexity, the proposed method benefits of both low-computational complexity and high-reconstruction quality. We also offer a solution for refocusing at distances that are not included in the reconstructed images stack. For such a case, we provide a modified version of our method, which is also algebraically exact and has lower computational complexity than other exact methods.

  15. Inflow hemodynamics evaluated by using four-dimensional flow magnetic resonance imaging and the size ratio of unruptured cerebral aneurysms

    Energy Technology Data Exchange (ETDEWEB)

    Futami, Kazuya [Matto-Ishikawa Central Hospital, Department of Neurosurgery, Hakusan, Ishikawa (Japan); Nambu, Iku; Kitabayashi, Tomohiro; Sano, Hiroki; Misaki, Kouichi; Uchiyama, Naoyuki; Nakada, Mitsutoshi [Kanazawa University School of Medicine, Department of Neurosurgery, Kanazawa, Ishikawa (Japan)

    2017-04-15

    Prediction of the rupture risk is critical for the identification of unruptured cerebral aneurysms (UCAs) eligible for invasive treatments. The size ratio (SR) is a strong morphological predictor for rupture. We investigated the relationship between the inflow hemodynamics evaluated on four-dimensional (4D) flow magnetic resonance (MR) imaging and the SR to identify specific characteristics related to UCA rupture. We evaluated the inflow jet patterns and inflow hemodynamic parameters of 70 UCAs on 4D flow MR imaging and compared them among 23 aneurysms with an SR ≥2.1 and 47 aneurysms with an SR ≤2.0. Based on the shape of inflow streamline bundles with a velocity ≥75% of the maximum flow velocity in the parent artery, the inflow jet patterns were classified as concentrated (C), diffuse (D), neck-limited (N), and unvisualized (U). The incidence of patterns C and N was significantly higher in aneurysms with an SR ≥2.1. The rate of pattern U was significantly higher in aneurysms with an SR ≤2.0. The maximum inflow rate and the inflow rate ratio were significantly higher in aneurysms with an SR ≥2.1. The SR affected the inflow jet pattern, the maximum inflow rate, and the inflow rate ratio of UCAs. In conjunction with the SR, inflow hemodynamic analysis using 4D flow MR imaging may contribute to the risk stratification for aneurysmal rupture. (orig.)

  16. Four-Dimensional (4D) Printing: A New Evolution in Computed Tomography-Guided Stereolithographic Modeling. Principles and Application.

    Science.gov (United States)

    Chae, Michael P; Hunter-Smith, David J; De-Silva, Inoka; Tham, Stephen; Spychal, Robert T; Rozen, Warren Matthew

    2015-07-01

    Over the last decade, image-guided production of three-dimensional (3D) haptic biomodels, or rapid prototyping (RP), has transformed the way surgeons conduct preoperative planning. In contrast to earlier RP techniques such as stereolithography, 3D printing has introduced fast, affordable office-based manufacturing. We introduce the concept of 4D printing for the first time by introducing time as the fourth dimension to 3D printing. The bones of the thumb ray are 3D printed during various movements to demonstrate four-dimensional (4D) printing. Principles and validation studies are presented here. 4D computed tomography was performed using "single volume acquisition" technology to reduce the exposure to radiation. Three representative scans of each thumb movement (i.e., abduction, opposition, and key pinch) were selected and then models were fabricated using a 3D printer. For validation, the angle between the first and the second metacarpals from the 4D imaging data and the 4D-printed model was recorded and compared. We demonstrate how 4D printing accurately depicts the transition in the position of metacarpals during thumb movement. With a fourth dimension of time, 4D printing delivers complex spatiotemporal anatomical details effortlessly and may substantially improve preoperative planning. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  17. Four-dimensional (4D) Motion Detection to Correct Respiratory Effects in Treatment Response Assessment Using Molecular Imaging Biomarkers

    Science.gov (United States)

    Schreibmann, Eduard; Crocker, Ian; Schuster, David M.; Curran, Walter J.; Fox, Tim

    2014-01-01

    Observing early metabolic changes in positron emission tomography (PET) is an essential tool to assess treatment efficiency in radiotherapy. However, for thoracic regions, the use of three-dimensional (3D) PET imaging is unfeasible because the radiotracer activity is smeared by the respiratory motion and averaged during the imaging acquisition process. This motion-induced degradation is similar in magnitude with the treatment-induced changes, and the two occurrences become indiscernible. We present a customized temporal-spatial deformable registration method for quantifying respiratory motion in a four-dimensional (4D) PET dataset. Once the motion is quantified, a motion-corrected (MC) dataset is created by tracking voxels to eliminate breathing-induced changes in the 4D imaging scan. The 4D voxel-tracking data is then summed to yield a 3D MC-PET scan containing only treatment-induced changes. This proof of concept is exemplified on both phantom and clinical data, where the proposed algorithm tracked the trajectories of individual points through the 4D datasets reducing motion to less than 4 mm in all phases. This correction approach using deformable registration can discern motion blurring from treatment-induced changes in treatment response assessment using PET imaging. PMID:24000982

  18. A novel color image encryption algorithm based on genetic recombination and the four-dimensional memristive hyperchaotic system

    Science.gov (United States)

    Chai, Xiu-Li; Gan, Zhi-Hua; Lu, Yang; Zhang, Miao-Hui; Chen, Yi-Ran

    2016-10-01

    Recently, many image encryption algorithms based on chaos have been proposed. Most of the previous algorithms encrypt components R, G, and B of color images independently and neglect the high correlation between them. In the paper, a novel color image encryption algorithm is introduced. The 24 bit planes of components R, G, and B of the color plain image are obtained and recombined into 4 compound bit planes, and this can make the three components affect each other. A four-dimensional (4D) memristive hyperchaotic system generates the pseudorandom key streams and its initial values come from the SHA 256 hash value of the color plain image. The compound bit planes and key streams are confused according to the principles of genetic recombination, then confusion and diffusion as a union are applied to the bit planes, and the color cipher image is obtained. Experimental results and security analyses demonstrate that the proposed algorithm is secure and effective so that it may be adopted for secure communication. Project supported by the National Natural Science Foundation of China (Grant Nos. 61203094 and 61305042), the Natural Science Foundation of the United States (Grant Nos. CNS-1253424 and ECCS-1202225), the Science and Technology Foundation of Henan Province, China (Grant No. 152102210048), the Foundation and Frontier Project of Henan Province, China (Grant No. 162300410196), the Natural Science Foundation of Educational Committee of Henan Province, China (Grant No. 14A413015), and the Research Foundation of Henan University, China (Grant No. xxjc20140006).

  19. Measurement of the transverse four-dimensional beam rms-emittance of an intense uranium beam at 11.4 MeV/u

    Science.gov (United States)

    Xiao, C.; Groening, L.; Gerhard, P.; Maier, M.; Mickat, S.; Vormann, H.

    2016-06-01

    Knowledge of the transverse four-dimensional beam rms-parameters is essential for applications that involve lattice elements that couple the two transverse degrees of freedom (planes). Usually pepper-pots are used for measuring these beam parameters. However, for ions their application is limited to energies below 150 keV/u. This contribution is on measurements of the full transverse four-dimensional second-moments beam matrix of high intensity uranium ions at an energy of 11.4 MeV/u. The combination of skew quadrupoles with a slit/grid emittance measurement device has been successfully applied.

  20. Four Dimensional CO2 Data Assimilation of GOSAT Observation Data Using a Local Ensemble Transform Kalman Filter (LETKF)

    Science.gov (United States)

    Maki, T.; Sekiyama, T. T.; Miyoshi, T.; Nakamura, T.; Iwasaki, T.

    2015-12-01

    Impacts of CO2 concentration data obtained from satellite (GOSAT TIR L2 Ver. 1.0) measurements on the estimation of global surface CO2 fluxes have been investigated using an ensemble-based four-dimensional data assimilation system (LETKF). An online atmospheric transport model (MJ98-CDTM) is employed in the data assimilation system to optimize surface CO2 fluxes from real observations at spatial and temporal resolutions of 6 days and about 2.8° (T42), respectively. The features of GOSAT TIR L2 Ver. 1.0 data are their larger data number than that of SWIR L2 (about 10 times) and smaller standard deviation than their former version (TIR L2 Ver. 0.01). These points are the advantageous features to CO2 data assimilation. One of the most important issues in satellite data assimilation is a bias correction technique. Therefore, we have tested 4 types of satellite bias correction experiments (w/o bias correction, monthly mean bias correction, all data bias correction and globally constant bias correction) using independent CO2 concentration analysis (JMA CO2 distribution) in our data assimilation system. Our results showed that estimated CO2 concentration and fluxes are significantly sensitive to bias correction scheme. The reason may come from that model biases are important issue on data assimilation. In conclusion, suitable satellite data bias correction allows obtaining realistic CO2 concentration field and modifying surface CO2 flux almost entire earth surface. In addition, this satellite bias correction scheme makes it possible to use multiple satellite observation data simultaneously in CO2 data assimilation.

  1. Scapholunate kinematics of asymptomatic wrists in comparison with symptomatic contralateral wrists using four-dimensional CT examinations: initial clinical experience

    Energy Technology Data Exchange (ETDEWEB)

    Demehri, Shadpour; Hafezi-Nejad, Nima; Morelli, John N.; Thakur, Uma; Eng, John [Johns Hopkins University, Musculoskeletal Radiology, Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD (United States); Lifchez, Scott D.; Shores, Jaimie T. [Johns Hopkins University, Department of Plastic and Reconstructive Surgery, Baltimore, MD (United States); Means, Kenneth R. [MedStar Union Memorial Hospital, The Curtis National Hand Center, Baltimore, MD (United States)

    2016-04-15

    Using four-dimensional CT scan (4DCT), we aimed at showing the kinematics of scapholunate (SL) interval in asymptomatic wrists in comparison with symptomatic contralateral wrists with inconclusive radiographic findings. This is an IRB approved, HIPPA compliant, retrospective study. Patients suspected of SL interosseous ligament (SLIL) injuries were referred for further evaluation of chronic wrist pain (>3 months). Twelve wrists (11 subjects) with chronic symptoms and inconclusive plain radiographs and 10 asymptomatic wrists (in 10 different subjects) were scanned using 4DCT. The minimum SL interval was measured during three wrist motions: relaxed-to-clenched fist, flexion-to-extension, and radial-to-ulnar-deviation. Changes were recorded using double-oblique multiplanar reformation technique. We extracted the normal limits of the SL interval as measured by dynamic CT scanning during active motion in asymptomatic wrists. In asymptomatic wrists, the average SL interval was observed to be smaller than 1 mm during all motions. In symptomatic wrists, during exams performed with clenched fist (SL interval (mean ± SD) = 2.53 ± 1.19 mm), extension (2.54 ± 1.48 mm) or ulnar deviation (2.06 ± 1.12 mm), the average SL interval was more than 2 mm. In contrast to symptomatic wrists, no significant change in SL interval measurements was detected during wrist motions in asymptomatic wrists. There was a mild to moderate correlation between SL interval change and presence/absence of symptoms (point-biserial correlation coefficients: 0.29-0.55). In patients with wrist pain suspicious for SLIL injury and inconclusive radiographs, SL interval increase can be detected with 4DCT in the symptomatic wrist compared to the asymptomatic wrist. (orig.)

  2. A four-dimensional motion field atlas of the tongue from tagged and cine magnetic resonance imaging

    Science.gov (United States)

    Xing, Fangxu; Prince, Jerry L.; Stone, Maureen; Wedeen, Van J.; El Fakhri, Georges; Woo, Jonghye

    2017-02-01

    Representation of human tongue motion using three-dimensional vector fields over time can be used to better understand tongue function during speech, swallowing, and other lingual behaviors. To characterize the inter-subject variability of the tongue's shape and motion of a population carrying out one of these functions it is desirable to build a statistical model of the four-dimensional (4D) tongue. In this paper, we propose a method to construct a spatio-temporal atlas of tongue motion using magnetic resonance (MR) images acquired from fourteen healthy human subjects. First, cine MR images revealing the anatomical features of the tongue are used to construct a 4D intensity image atlas. Second, tagged MR images acquired to capture internal motion are used to compute a dense motion field at each time frame using a phase-based motion tracking method. Third, motion fields from each subject are pulled back to the cine atlas space using the deformation fields computed during the cine atlas construction. Finally, a spatio-temporal motion field atlas is created to show a sequence of mean motion fields and their inter-subject variation. The quality of the atlas was evaluated by deforming cine images in the atlas space. Comparison between deformed and original cine images showed high correspondence. The proposed method provides a quantitative representation to observe the commonality and variability of the tongue motion field for the first time, and shows potential in evaluation of common properties such as strains and other tensors based on motion fields.

  3. Dynamic measurement of the optical properties of bovine enamel demineralization models using four-dimensional optical coherence tomography

    Science.gov (United States)

    Aden, Abdirahman; Anthony, Arthi; Brigi, Carel; Merchant, Muhammad Sabih; Siraj, Huda; Tomlins, Peter H.

    2017-07-01

    Dental enamel mineral loss is multifactorial and is consequently explored using a variety of in vitro models. Important factors include the presence of acidic pH and its specific ionic composition, which can both influence lesion characteristics. Optical coherence tomography (OCT) has been demonstrated as a promising tool for studying dental enamel demineralization. However, OCT-based characterization and comparison of demineralization model dynamics are challenging without a consistent experimental environment. Therefore, an automated four-dimensional OCT system was integrated with a multispecimen flow cell to measure and compare the optical properties of subsurface enamel demineralization in different models. This configuration was entirely automated, thus mitigating any need to disturb the specimens and ensuring spatial registration of OCT image volumes at multiple time points. Twelve bovine enamel disks were divided equally among three model groups. The model demineralization solutions were citric acid (pH 3.8), acetic acid (pH 4.0), and acetic acid with added calcium and phosphate (pH 4.4). Bovine specimens were exposed to the solution continuously for 48 h. Three-dimensional OCT data were obtained automatically from each specimen at a minimum of 1-h intervals from the same location within each specimen. Lesion dynamics were measured in terms of the depth below the surface to which the lesion extended and the attenuation coefficient. The net loss of surface enamel was also measured for comparison. Similarities between the dynamics of each model were observed, although there were also distinct characteristic differences. Notably, the attenuation coefficients showed a systematic offset and temporal shift with respect to the different models. Furthermore, the lesion depth curves displayed a discontinuous increase several hours after the initial acid challenge. This work demonstrated the capability of OCT to distinguish between different enamel demineralization

  4. Dissipation of the tilting degree of freedom in heavy-ion-induced fission from four-dimensional Langevin dynamics

    Science.gov (United States)

    Nadtochy, P. N.; Ryabov, E. G.; Cheredov, A. V.; Adeev, G. D.

    2016-10-01

    A stochastic approach based on four-dimensional Langevin fission dynamics is applied to the calculation of a wide set of experimental observables of excited compound nuclei from 199Pb to 248Cf formed in reactions induced by heavy ions. In the model under investigation, the tilting degree of freedom ( K coordinate) representing the projection of the total angular momentum onto the symmetry axis of the nucleus is taken into account in addition to three collective shape coordinates introduced on the basis of {c,h,α} parametrization. The evolution of the K coordinate is described by means of the Langevin equation in the overdamped regime. The friction tensor for the shape collective coordinates is calculated under the assumption of the modified version of the one-body dissipation mechanism, where the reduction coefficient ks of the contribution from the "wall" formula is introduced. The calculations are performed both for the constant values of the coefficient ks and for the coordinate-dependent reduction coefficient ks(q) which is found on the basis of the "chaos-weighted wall formula". Different possibilities of the deformation-dependent dissipation coefficient (γK) for the K coordinate are investigated. The presented results demonstrate that an impact of the ks and γK parameters on the calculated observable fission characteristics can be selectively probed. It was found that it is possible to describe the experimental data consistently with the deformation-dependent γK(q) coefficient for shapes featuring a neck, which predicts quite small values of γK=0.0077 (MeV zs)-1/2 and constant γK=0.1-0.4 (MeV zs)-1/2 for compact shapes featuring no neck.

  5. Detecting cause of dislocation after total hip arthroplasty by patient-specific four-dimensional motion analysis.

    Science.gov (United States)

    Miki, Hidenobu; Sugano, Nobuhiko; Yonenobu, Kazuo; Tsuda, Kosuke; Hattori, Maki; Suzuki, Naoki

    2013-02-01

    Dislocation is a major complication after total hip arthroplasty. Prosthesis impingement is considered to be an important cause of dislocation because impingement marks are more frequently found on retrieved cups or liners in patients who have undergone revision surgery because of dislocation (80%-94%) than in those who have undergone reoperation for other reasons (51%-56%). However, it remains a question whether impingement marks are the cause of dislocation or are instead its result. To clarify the issue, it is necessary to confirm noninvasively whether the point of impingement matches the patient's hip position when dislocation occurs. Using four-dimensional patient-specific analysis, we recorded prosthesis impingement in 10 hips with instability after primary total hip arthroplasty when the patients reproduced the dislocation-causing motion. We found prosthesis impingement to be related to at least instability in 6 of 10 hips with dislocation after primary total hip arthroplasty and in 4 of 4 hips that underwent revision surgery for recurrent dislocation. All impingements occurred between the anterior wall of the liner and the stem neck in posterior dislocation and between the posterior wall of the liner and the stem neck in anterior dislocation. Revision surgery in 1 of those 4 hips revealed 2 impingement marks on the retrieved liner that closely matched the prosthesis impingement point and the dislocation pathway of the metal head on the liner that were detected earlier during motion analysis. Prosthesis impingement is an important factor in dislocation after total hip arthroplasty. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. To what extent does the anxiety scale of the Four-Dimensional Symptom Questionnaire (4DSQ) detect specific types of anxiety disorder in primary care? A psychometric study

    NARCIS (Netherlands)

    Terluin, B.; Oosterbaan, D.B.; Brouwers, E.P.; Straten, A. van; Ven, P.M. van de; Langerak, W.; Marwijk, H.W.J. van

    2014-01-01

    BACKGROUND: Anxiety scales may help primary care physicians to detect specific anxiety disorders among the many emotionally distressed patients presenting in primary care. The anxiety scale of the Four-Dimensional Symptom Questionnaire (4DSQ) consists of an admixture of symptoms of specific anxiety

  7. 四维彩超输卵管造影流程的规范与优化%Standardization and optimization of four-dimensional ultrasound hysterosalpinography process

    Institute of Scientific and Technical Information of China (English)

    杨曦; 张靖; 孟洁; 陈俊雅; 张潇潇; 汪京萍; 李琛; 郑潇潇; 白文佩

    2014-01-01

    In four-dimensional ultrasound hysterosalpinography micro bubble ultrasound contrast agent -sonovueis is injected into the uterine cavity to distend uterine cavity and fallopian for four-dimensional imaging .Four-dimensional ultrasound hysterosalpinography is mainly performed for the evaluation of uterine tubal patency and diagnosis of intrauterine lesions to analyze the causes of female infertility . It is accurate, safe, non-invasive, efficient and therapeutic.A detailed description of standard process of four-dimensional ultrasound hysterosalpinography was described in this paper .%四维彩超输卵管造影检查术是将微气泡超声造影剂———声诺维注入到宫腔,使原本闭合的宫腔和输卵管扩张,然后进行四维成像,主要用于评价输卵管通畅性和诊断子宫宫腔病变,用以诊断女性不孕的原因,具有准确、安全、无创伤、快捷及治疗作用。该文详细叙述了四维彩超输卵管造影的规范流程。

  8. The Hawking temperature in the context of dark energy for four-dimensional asymptotically AdS black holes with scalar hair

    Science.gov (United States)

    Naji, J.

    2016-01-01

    In this paper, we considered new solutions for four-dimensional asymptotically AdS black holes with scalar hair and discuss about Hawking temperature in the context of dark energy by using the tunneling method. We obtain modification of the Hawking temperature due to presence of the dark energy.

  9. Interobserver agreement in detailed prenatal diagnosis of congenital heart disease by telemedicine using four-dimensional ultrasound with spatiotemporal image correlation

    NARCIS (Netherlands)

    Adriaanse, B.M.; Tromp, C.H.; Simpson, J.M.; Mieghem, T. van; Kist, W.J.; Kuik, D.J.; Oepkes, D.; Vugt, J.M. van; Haak, M.C.

    2012-01-01

    OBJECTIVE: To evaluate the clinical accuracy of four-dimensional (4D) echocardiography in the detailed prenatal diagnosis of congenital heart disease (CHD) in a telemedicine setting. METHODS: Ten second-trimester spatiotemporal image correlation (STIC) volumes were sent to three observers in differe

  10. Effect of tumor volume on the enhancement pattern of parathyroid adenoma on parathyroid four-dimensional CT

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun Kyoung [Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Dongguk University Ilsan Hospital, Department of Radiology, Goyang-si (Korea, Republic of); Yun, Tae Jin; Kim, Ji-hoon; Kang, Koung Mi; Choi, Seung Hong; Sohn, Chul-Ho [Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Seoul National University Hospital, Department of Radiology, Jongno-gu, Seoul (Korea, Republic of); Lee, Kyu Eun; Kim, Su-jin [Seoul National University Hospital, Department of Surgery, Seoul (Korea, Republic of); Won, Jae-Kyung [Seoul National University Hospital, Department of Pathology, Seoul (Korea, Republic of)

    2016-05-15

    The purpose of this study is to assess the effect of tumor volume on the enhancement pattern of parathyroid adenoma (PTA) on four-dimensional computed tomography (4D-CT). We analyzed the enhancement patterns of PTA on four-phase 4D-CT in 44 patients. Dependency of the changes of Hounsfield unit values (ΔHU) on the tumor volumes and clinical characteristics was evaluated using linear regression analyses. In addition, an unpaired t test was used to compare ΔHU of PTAs between PTA volume ≥1 cm{sup 3} and <1 cm{sup 3}, thyroid gland, and lymph node. PTA volume based on CT was the strongest factor on the ΔHU{sub Pre} {sub to} {sub Arterial} and ΔHU{sub Arterial} {sub to} {sub Venous} and ΔHU{sub Arterial} {sub to} {sub Delayed} (R {sup 2} = 0.34, 0.25, and 0.32, respectively, P < 0.001 for both). PTA ≥1 cm {sup 3} had statistically significant greater enhancement between the unenhanced phase and the arterial phase than PTA <1 cm {sup 3} (mean values ± standard deviations (SDs) of ΔHU{sub Pre} {sub to} {sub Arterial}, 102.7 ± 33.7 and 57.5 ± 28.8, respectively, P < 0.001). PTA ≥1 cm {sup 3} showed an early washout pattern on the venous phase, whereas PTA <1 cm {sup 3} showed a progressive enhancement pattern on the venous phase (mean values ± SDs of ΔHU{sub Arterial} {sub to} {sub Venous}, -13.2 ± 31.6 and 14.4 ± 32.7, respectively; P = 0.009). The enhancement pattern of PTA on 4D-CT is variable with respect to PTA volume based on CT. Therefore, the enhancement pattern of PTA on 4D-CT requires careful interpretation concerning the tumor volume, especially in cases of PTA <1 cm {sup 3}. (orig.)

  11. SU-C-207-01: Four-Dimensional Inverse Geometry Computed Tomography: Concept and Its Validation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K; Kim, D; Kim, T; Kang, S; Cho, M; Shin, D; Suh, T [The Catholic University of Korea, Seoul (Korea, Republic of)

    2015-06-15

    Purpose: In past few years, the inverse geometry computed tomography (IGCT) system has been developed to overcome shortcomings of a conventional computed tomography (CT) system such as scatter problem induced from large detector size and cone-beam artifact. In this study, we intend to present a concept of a four-dimensional (4D) IGCT system that has positive aspects above all with temporal resolution for dynamic studies and reduction of motion artifact. Methods: Contrary to conventional CT system, projection data at a certain angle in IGCT was a group of fractionated narrow cone-beam projection data, projection group (PG), acquired from multi-source array which have extremely short time gap of sequential operation between each of sources. At this, for 4D IGCT imaging, time-related data acquisition parameters were determined by combining multi-source scanning time for collecting one PG with conventional 4D CBCT data acquisition sequence. Over a gantry rotation, acquired PGs from multi-source array were tagged time and angle for 4D image reconstruction. Acquired PGs were sorted into 10 phase and image reconstructions were independently performed at each phase. Image reconstruction algorithm based upon filtered-backprojection was used in this study. Results: The 4D IGCT had uniform image without cone-beam artifact on the contrary to 4D CBCT image. In addition, the 4D IGCT images of each phase had no significant artifact induced from motion compared with 3D CT. Conclusion: The 4D IGCT image seems to give relatively accurate dynamic information of patient anatomy based on the results were more endurable than 3D CT about motion artifact. From this, it will be useful for dynamic study and respiratory-correlated radiation therapy. This work was supported by the Industrial R&D program of MOTIE/KEIT [10048997, Development of the core technology for integrated therapy devices based on real-time MRI guided tumor tracking] and the Mid-career Researcher Program (2014R1A2A1A

  12. Improving thoracic four-dimensional cone-beam CT reconstruction with anatomical-adaptive image regularization (AAIR).

    Science.gov (United States)

    Shieh, Chun-Chien; Kipritidis, John; O'Brien, Ricky T; Cooper, Benjamin J; Kuncic, Zdenka; Keall, Paul J

    2015-01-21

    Total-variation (TV) minimization reconstructions can significantly reduce noise and streaks in thoracic four-dimensional cone-beam computed tomography (4D CBCT) images compared to the Feldkamp-Davis-Kress (FDK) algorithm currently used in practice. TV minimization reconstructions are, however, prone to over-smoothing anatomical details and are also computationally inefficient. The aim of this study is to demonstrate a proof of concept that these disadvantages can be overcome by incorporating the general knowledge of the thoracic anatomy via anatomy segmentation into the reconstruction. The proposed method, referred as the anatomical-adaptive image regularization (AAIR) method, utilizes the adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS) framework, but introduces an additional anatomy segmentation step in every iteration. The anatomy segmentation information is implemented in the reconstruction using a heuristic approach to adaptively suppress over-smoothing at anatomical structures of interest. The performance of AAIR depends on parameters describing the weighting of the anatomy segmentation prior and segmentation threshold values. A sensitivity study revealed that the reconstruction outcome is not sensitive to these parameters as long as they are chosen within a suitable range. AAIR was validated using a digital phantom and a patient scan and was compared to FDK, ASD-POCS and the prior image constrained compressed sensing (PICCS) method. For the phantom case, AAIR reconstruction was quantitatively shown to be the most accurate as indicated by the mean absolute difference and the structural similarity index. For the patient case, AAIR resulted in the highest signal-to-noise ratio (i.e. the lowest level of noise and streaking) and the highest contrast-to-noise ratios for the tumor and the bony anatomy (i.e. the best visibility of anatomical details). Overall, AAIR was much less prone to over-smoothing anatomical details compared to ASD-POCS and did

  13. Four-dimensional distribution of the 2010 Eyjafjallajökull volcanic cloud over Europe observed by EARLINET

    Directory of Open Access Journals (Sweden)

    G. Pappalardo

    2012-11-01

    Full Text Available The eruption of the Icelandic volcano Eyjafjallajökull in April/May 2010 represents a "natural experiment" to study the impact of volcanic emissions on a continental scale. For the first time, quantitative data about the presence, altitude, and layering of the volcanic cloud, in conjunction with optical information, are available for most parts of Europe derived from the observations by the European Aerosol Research Lidar NETwork (EARLINET. Based on multi-wavelength Raman lidar systems EARLINET is the only instrument worldwide that is able to provide dense time series of high-quality optical data to be used for aerosol typing and for the retrieval of particle microphysical properties as a function of altitude.

    In this work we show the four-dimensional (4-D distribution of the Eyjafjallajökull volcanic cloud over Europe as observed by EARLINET during the entire volcanic event (15 April–26 May 2010. All optical properties directly measured (backscatter, extinction, and particle linear depolarization ratio are stored in the EARLINET database available at http://www.earlinet.org. A specific relational database providing the volcanic mask over Europe, realized ad hoc for this specific event, has been developed and is available on request at http://www.earlinet.org.

    During the first days after the eruption, volcanic particles were detected over Central Europe within a wide range of altitudes, from the lower stratosphere down to the local Planetary Boundary Layer (PBL. After 19 April 2010, volcanic particles were detected over South and South Eastern Europe. During the first half of May (5–15 May, material emitted by the Eyjafjallajökull volcano was detected over Spain and Portugal and then over the Mediterranean and the Balkans. Last observations of the event were recorded until 25 May in Central Europe and in the Eastern

  14. Comparison of planning target volumes based on three-dimensional and four-dimensional CT imaging of thoracic esophageal cancer.

    Science.gov (United States)

    Wang, Wei; Li, Jianbin; Zhang, Yingjie; Shao, Qian; Xu, Min; Fan, Tingyong; Wang, Jinzhi

    2016-01-01

    To investigate the definition of planning target volumes (PTVs) based on four-dimensional computed tomography (4DCT) compared with conventional PTV definition and PTV definition using asymmetrical margins for thoracic primary esophageal cancer. Forty-three patients with esophageal cancer underwent 3DCT and 4DCT simulation scans during free breathing. The motions of primary tumors located in the proximal (group A), middle (group B), and distal (group C) thoracic esophagus were obtained from the 4DCT scans. PTV3D was defined on 3DCT using the tumor motion measured based on 4DCT, PTV conventional (PTVconv) was defined on 3DCT by adding a 1.0 cm margin to the clinical target volume, and PTV4D was defined as the union of the target volumes contoured on the ten phases of the 4DCT images. The centroid positions, volumetric differences, and dice similarity coefficients were evaluated for all PTVs. The median centroid shifts between PTV3D and PTV4D and between PTVconv and PTV4D in all three dimensions were groups. The median size ratios of PTV4D to PTV3D were 0.80, 0.88, and 0.71, and PTV4D to PTVconv were 0.67, 0.73, and 0.76 (χ (2)=-3.18, -2.98, and -3.06; P=0.001, 0.003, and 0.002) for groups A, B, and C, respectively. The dice similarity coefficients were 0.87, 0.90, and 0.81 between PTV4D and PTV3D and 0.80, 0.84, and 0.83 between PTV4D and PTVconv (χ (2) =-3.18, -2.98, and -3.06; P=0.001, 0.003, and 0.002) for groups A, B, and C, respectively. The difference between the degree of inclusion of PTV4D in PTV3D and that of PTV4D in PTVconv was groups. Compared with PTVconv, the amount of irradiated normal tissue for PTV3D was decreased by 11.81% and 11.86% in groups A and B, respectively, but was increased by 2.93% in group C. For proximal and middle esophageal cancer, 3DCT-based PTV using asymmetrical margins provides good coverage of PTV4D; however, for distal esophageal cancer, 3DCT-based PTV using conventional margins provides ideal conformity with PTV4D.

  15. Hyperpolarized (3)He magnetic resonance imaging: comparison with four-dimensional x-ray computed tomography imaging in lung cancer.

    Science.gov (United States)

    Mathew, Lindsay; Wheatley, Andrew; Castillo, Richard; Castillo, Edward; Rodrigues, George; Guerrero, Thomas; Parraga, Grace

    2012-12-01

    Pulmonary functional imaging using four-dimensional x-ray computed tomographic (4DCT) imaging and hyperpolarized (3)He magnetic resonance imaging (MRI) provides regional lung function estimates in patients with lung cancer in whom pulmonary function measurements are typically dominated by tumor burden. The aim of this study was to evaluate the quantitative spatial relationship between 4DCT and hyperpolarized (3)He MRI ventilation maps. Eleven patients with lung cancer provided written informed consent to 4DCT imaging and MRI performed within 11 ± 14 days. Hyperpolarized (3)He MRI was acquired in breath-hold after inhalation from functional residual capacity of 1 L hyperpolarized (3)He, whereas 4DCT imaging was acquired over a single tidal breath of room air. For hyperpolarized (3)He MRI, the percentage ventilated volume was generated using semiautomated segmentation; for 4DCT imaging, pulmonary function maps were generated using the correspondence between identical tissue elements at inspiratory and expiratory phases to generate percentage ventilated volume. After accounting for differences in image acquisition lung volumes ((3)He MRI: 1.9 ± 0.5 L ipsilateral, 2.3 ± 0.7 L contralateral; 4DCT imaging: 1.2 ± 0.3 L ipsilateral, 1.3 ± 0.4 L contralateral), there was no significant difference in percentage ventilated volume between hyperpolarized (3)He MRI (72 ± 11% ipsilateral, 79 ± 12% contralateral) and 4DCT imaging (74 ± 3% ipsilateral, 75 ± 4% contralateral). Spatial correspondence between 4DCT and (3)He MRI ventilation was evaluated using the Dice similarity coefficient index (ipsilateral, 86 ± 12%; contralateral, 88 ± 12%). Despite rather large differences in image acquisition breathing maneuvers, good spatial and significant quantitative agreement was observed for ventilation maps on hyperpolarized (3)He MRI and 4DCT imaging, suggesting that pulmonary regions with good lung function are similar between modalities in this small group of patients with

  16. Four-dimensional variational inversion of black carbon emissions during ARCTAS-CARB with WRFDA-Chem

    Directory of Open Access Journals (Sweden)

    J. J. Guerrette

    2017-06-01

    Full Text Available Biomass burning emissions of atmospheric aerosols, including black carbon, are growing due to increased global drought, and comprise a large source of uncertainty in regional climate and air quality studies. We develop and apply new incremental four-dimensional variational (4D-Var capabilities in WRFDA-Chem to find optimal spatially and temporally distributed biomass burning (BB and anthropogenic black carbon (BC aerosol emissions. The constraints are provided by aircraft BC concentrations from the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites in collaboration with the California Air Resources Board (ARCTAS-CARB field campaign and surface BC concentrations from the Interagency Monitoring of PROtected Visual Environment (IMPROVE network on 22, 23, and 24 June 2008. We consider three BB inventories, including Fire INventory from NCAR (FINN v1.0 and v1.5 and Quick Fire Emissions Database (QFED v2.4r8. On 22 June, aircraft observations are able to reduce the spread between a customized QFED inventory and FINNv1.0 from a factor of 3. 5 ( × 3. 5 to only × 2. 1. On 23 and 24 June, the spread is reduced from × 3. 4 to × 1. 4. The posterior corrections to emissions are heterogeneous in time and space, and exhibit similar spatial patterns of sign for both inventories. The posterior diurnal BB patterns indicate that multiple daily emission peaks might be warranted in specific regions of California. The US EPA's 2005 National Emissions Inventory (NEI05 is used as the anthropogenic prior. On 23 and 24 June, the coastal California posterior is reduced by × 2, where highway sources dominate, while inland sources are increased near Barstow by × 5. Relative BB emission variances are reduced from the prior by up to 35 % in grid cells close to aircraft flight paths and by up to 60 % for fires near surface measurements. Anthropogenic variance reduction is as high as 40 % and is similarly

  17. Four-dimensional variational inversion of black carbon emissions during ARCTAS-CARB with WRFDA-Chem

    Science.gov (United States)

    Guerrette, Jonathan J.; Henze, Daven K.

    2017-06-01

    Biomass burning emissions of atmospheric aerosols, including black carbon, are growing due to increased global drought, and comprise a large source of uncertainty in regional climate and air quality studies. We develop and apply new incremental four-dimensional variational (4D-Var) capabilities in WRFDA-Chem to find optimal spatially and temporally distributed biomass burning (BB) and anthropogenic black carbon (BC) aerosol emissions. The constraints are provided by aircraft BC concentrations from the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites in collaboration with the California Air Resources Board (ARCTAS-CARB) field campaign and surface BC concentrations from the Interagency Monitoring of PROtected Visual Environment (IMPROVE) network on 22, 23, and 24 June 2008. We consider three BB inventories, including Fire INventory from NCAR (FINN) v1.0 and v1.5 and Quick Fire Emissions Database (QFED) v2.4r8. On 22 June, aircraft observations are able to reduce the spread between a customized QFED inventory and FINNv1.0 from a factor of 3. 5 ( × 3. 5) to only × 2. 1. On 23 and 24 June, the spread is reduced from × 3. 4 to × 1. 4. The posterior corrections to emissions are heterogeneous in time and space, and exhibit similar spatial patterns of sign for both inventories. The posterior diurnal BB patterns indicate that multiple daily emission peaks might be warranted in specific regions of California. The US EPA's 2005 National Emissions Inventory (NEI05) is used as the anthropogenic prior. On 23 and 24 June, the coastal California posterior is reduced by × 2, where highway sources dominate, while inland sources are increased near Barstow by × 5. Relative BB emission variances are reduced from the prior by up to 35 % in grid cells close to aircraft flight paths and by up to 60 % for fires near surface measurements. Anthropogenic variance reduction is as high as 40 % and is similarly limited to sources close to observations. We

  18. Four-dimensional dose reconstruction through in vivo phase matching of cine images of electronic portal imaging device.

    Science.gov (United States)

    Yoon, Jihyung; Jung, Jae Won; Kim, Jong Oh; Yi, Byong Yong; Yeo, Inhwan

    2016-07-01

    A method is proposed to reconstruct a four-dimensional (4D) dose distribution using phase matching of measured cine images to precalculated images of electronic portal imaging device (EPID). (1) A phantom, designed to simulate a tumor in lung (a polystyrene block with a 3 cm diameter embedded in cork), was placed on a sinusoidally moving platform with an amplitude of 1 cm and a period of 4 s. Ten-phase 4D computed tomography (CT) images of the phantom were acquired. A planning target volume (PTV) was created by adding a margin of 1 cm around the internal target volume of the tumor. (2) Three beams were designed, which included a static beam, a theoretical dynamic beam, and a planning-optimized dynamic beam (PODB). While the theoretical beam was made by manually programming a simplistic sliding leaf motion, the planning-optimized beam was obtained from treatment planning. From the three beams, three-dimensional (3D) doses on the phantom were calculated; 4D dose was calculated by means of the ten phase images (integrated over phases afterward); serving as "reference" images, phase-specific EPID dose images under the lung phantom were also calculated for each of the ten phases. (3) Cine EPID images were acquired while the beams were irradiated to the moving phantom. (4) Each cine image was phase-matched to a phase-specific CT image at which common irradiation occurred by intercomparing the cine image with the reference images. (5) Each cine image was used to reconstruct dose in the phase-matched CT image, and the reconstructed doses were summed over all phases. (6) The summation was compared with forwardly calculated 4D and 3D dose distributions. Accounting for realistic situations, intratreatment breathing irregularity was simulated by assuming an amplitude of 0.5 cm for the phantom during a portion of breathing trace in which the phase matching could not be performed. Intertreatment breathing irregularity between the time of treatment and the time of planning CT was

  19. Measuring interfraction and intrafraction lung function changes during radiation therapy using four-dimensional cone beam CT ventilation imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kipritidis, John, E-mail: john.kipritidis@sydney.edu.au; Keall, Paul J. [Radiation Physics Laboratory, Sydney Medical School, University of Sydney, Sydney NSW 2006 (Australia); Hugo, Geoffrey; Weiss, Elisabeth; Williamson, Jeffrey [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia 23298 (United States)

    2015-03-15

    Purpose: Adaptive ventilation guided radiation therapy could minimize the irradiation of healthy lung based on repeat lung ventilation imaging (VI) during treatment. However the efficacy of adaptive ventilation guidance requires that interfraction (e.g., week-to-week), ventilation changes are not washed out by intrafraction (e.g., pre- and postfraction) changes, for example, due to patient breathing variability. The authors hypothesize that patients undergoing lung cancer radiation therapy exhibit larger interfraction ventilation changes compared to intrafraction function changes. To test this, the authors perform the first comparison of interfraction and intrafraction lung VI pairs using four-dimensional cone beam CT ventilation imaging (4D-CBCT VI), a novel technique for functional lung imaging. Methods: The authors analyzed a total of 215 4D-CBCT scans acquired for 19 locally advanced non-small cell lung cancer (LA-NSCLC) patients over 4–6 weeks of radiation therapy. This set of 215 scans was sorted into 56 interfraction pairs (including first day scans and each of treatment weeks 2, 4, and 6) and 78 intrafraction pairs (including pre/postfraction scans on the same-day), with some scans appearing in both sets. VIs were obtained from the Jacobian determinant of the transform between the 4D-CBCT end-exhale and end-inhale images after deformable image registration. All VIs were deformably registered to their corresponding planning CT and normalized to account for differences in breathing effort, thus facilitating image comparison in terms of (i) voxelwise Spearman correlations, (ii) mean image differences, and (iii) gamma pass rates for all interfraction and intrafraction VI pairs. For the side of the lung ipsilateral to the tumor, we applied two-sided t-tests to determine whether interfraction VI pairs were more different than intrafraction VI pairs. Results: The (mean ± standard deviation) Spearman correlation for interfraction VI pairs was r{sup -}{sub Inter

  20. Comparison of planning target volumes based on three-dimensional and four-dimensional CT imaging of thoracic esophageal cancer

    Directory of Open Access Journals (Sweden)

    Wang W

    2016-08-01

    Full Text Available Wei Wang, Jianbin Li, Yingjie Zhang, Qian Shao, Min Xu, Tingyong Fan, Jinzhi Wang Department of Radiation Oncology, Shandong Cancer Hospital Affiliated to Shandong University, Shandong Academy of Medical Sciences, Shandong, People’s Republic of China Background and purpose: To investigate the definition of planning target volumes (PTVs based on four-dimensional computed tomography (4DCT compared with conventional PTV definition and PTV definition using asymmetrical margins for thoracic primary esophageal cancer. Materials and methods: Forty-three patients with esophageal cancer underwent 3DCT and 4DCT simulation scans during free breathing. The motions of primary tumors located in the proximal (group A, middle (group B, and distal (group C thoracic esophagus were obtained from the 4DCT scans. PTV3D was defined on 3DCT using the tumor motion measured based on 4DCT, PTV conventional (PTVconv was defined on 3DCT by adding a 1.0 cm margin to the clinical target volume, and PTV4D was defined as the union of the target volumes contoured on the ten phases of the 4DCT images. The centroid positions, volumetric differences, and dice similarity coefficients were evaluated for all PTVs. Results: The median centroid shifts between PTV3D and PTV4D and between PTVconv and PTV4D in all three dimensions were <0.3 cm for the three groups. The median size ratios of PTV4D to PTV3D were 0.80, 0.88, and 0.71, and PTV4D to PTVconv were 0.67, 0.73, and 0.76 (χ2=–3.18, –2.98, and –3.06; P=0.001, 0.003, and 0.002 for groups A, B, and C, respectively. The dice similarity coefficients were 0.87, 0.90, and 0.81 between PTV4D and PTV3D and 0.80, 0.84, and 0.83 between PTV4D and PTVconv (χ2=–3.18, –2.98, and –3.06; P=0.001, 0.003, and 0.002 for groups A, B, and C, respectively. The difference between the degree of inclusion of PTV4D in PTV3D and that of PTV4D in PTVconv was <2% for all groups. Compared with PTVconv, the amount of irradiated normal tissue

  1. Three-dimensional versus four-dimensional dose calculation for volumetric modulated arc therapy of hypofractionated treatments

    Energy Technology Data Exchange (ETDEWEB)

    Ehrbar, Stefanie; Lang, Stephanie; Stieb, Sonja; Riesterer, Oliver; Stark, Luisa Sabrina; Guckenberger, Matthias; Kloeck, Stephan [University Hospital Zuerich (Switzerland). Dept. of Radiation Oncology

    2016-05-01

    Purpose: Respiratory motion is a non-negligible source of uncertainty in radiotherapy. A common approach is to delineate the target volume in all respiratory phases (ITV) and to calculate a treatment plan using the average reconstruction of the four-dimensional computed tomography (4DCT) scans. In this study the extent of the interplay effect caused by interaction between dynamic dose delivery and respiratory tumor motion, as well as other motion effects were investigated. These effects are often ignored when the ITV concept is used. Methods and Materials: Nine previously treated patients with in ten abdominal or thoracic cancer lesions (3 liver, 3 adrenal glands and 4 lung lesions) were selected for this planning study. For all patients, phase-sorted respiration-correlated 4DCT scans were taken, and volumetric modulated arc therapy (VMAT) treatments were planned using the ITV concept. Margins from ITV to planning target volume (PTV) of 3-10 mm were used. Plans were optimized and dose distributions were calculated on the average reconstruction of the 4DCT. 4D dose distributions were calculated to evaluate motion effects, caused by the interference of dynamic treatment delivery with respiratory tumor motion and inhomogeneously planned target dose. These calculations were performed on the phase-sorted CT series with a respiration-correlated assignment of the treatment plan's monitor units (MU) to the respiration phases of the 4DCT. The 4D dose was accumulated with rigid as well as deformable registrations of the CT series and compared to the original 3D dose distribution. Maximum, minimum and mean doses to ITV and PTV, and maximum or mean doses to organs at risk (OAR), were compared after rigid accumulation. The dose variation in the gross tumor volume (GTV) was compared after deformable registration. Results: Using rigid registrations, variations in the investigated dose parameters between 3D and 4D dose calculations were found to be within -2.1% to 1.4% for

  2. Four-dimensional echocardiography area strain combined with exercise stress echocardiography to evaluate left ventricular regional systolic function in patients with mild single vessel coronary artery stenosis.

    Science.gov (United States)

    Deng, Yan; Peng, Long; Liu, Yuan-Yuan; Yin, Li-Xue; Li, Chun-Mei; Wang, Yi; Rao, Li

    2017-07-28

    The aim of this prospective study was to assess the diagnosis value of four-dimensional echocardiography area strain (AS) combined with exercise stress echocardiography to evaluate left ventricular regional systolic function in patients with mild single vessel coronary artery stenosis. Based on treadmill exercise load status, two-dimensional conventional echocardiography and four-dimensional echocardiography area strain were performed on patients suspected coronary artery disease before coronary angiogram. Thirty patients (case group) with mild left anterior descending coronary artery stenosis (stenosis coronary artery stenosis according to the coronary angiogram results were prospectively enrolled. All the patients had no left ventricular regional wall motion abnormality in two-dimensional echocardiography at rest and exercise stress. There was no significant difference in the 16 segmental systolic peak AS at rest between two groups. After exercise stress, the peak systolic ASrest-stress at mid anterior wall (-7.00%±10.90% vs 2.80%±23.69%) and mid anterolateral wall (-4.40%±18.81% vs 8.80%±19.16%) were decreased, while increased at basal inferolateral wall (14.00%±19.27% vs -5.60%±15.94%) in case group compared with control group (Pcoronary artery stenosis, the area strain was decreased at involved segments, while compensatory increased at noninvolved segments after exercise stress. Four-dimensional echocardiography area strain combined with exercise stress echocardiography could sensitively find left ventricular regional systolic function abnormality in patients with mild single vessel coronary artery stenosis, and locate stenosis coronary artery accordingly. © 2017, Wiley Periodicals, Inc.

  3. The relationship between four-dimensional θ = π Yang-Mills theory and the two-dimensional Wess-Zumino-Novikov-Witten model

    Institute of Scientific and Technical Information of China (English)

    寇谡鹏

    2002-01-01

    Used the dimensional reduction in the sense of Parisi and Sourlas, the gauge fixing term of the four-dimensionalYang-Mills field without the theta term is reduced to a two-dimensional principal chiral model. By adding the θ term(θ = π), the two-dimensional principal chiral model changes into the two-dimensional level 1 Wess-Zumino-Novikov-Witten model. The non-trivial fixed point indicates that Yang-Mills theory at θ = π is a critical theory without massgap and confinement.

  4. Application of a Four-dimensional Mathematical Model in the Establishment of an Early Post-burn Cerebral Oedema Model in Severely Burned Dogs

    OpenAIRE

    Haitao, L.; Dajun, Y.; Kaifa, W.; Xiuwu, B.; Jiansen, S.; Zongchen, Y.

    2005-01-01

    The aim of this study was to explore the spatiotemporal development of cerebral oedema in the early stage of severe burn (50% TBSA, third degree), using a four-dimensional (4D) mathematical model. Twenty-six male mongrel dogs were randomly divided into control and 6, 12, 18, and 24 post-burn hour (PBH) groups. The manifestation of magnetic resonance imaging (MRI) and histopathology, changes of brain water content, and intracranial pressure were observed in each group respectively. A 4D mathem...

  5. Vocal cord dysfunction diagnosed by four-dimensional dynamic volume computed tomography in patients with difficult-to-treat asthma: A case series.

    Science.gov (United States)

    Cheng, Wei-Tso; Chen, Huan-Wen; Su, I-Hao; Fang, Ji-Tseng; Kuo, Han-Pin; Huang, Chien-Da

    2015-12-01

    Patients with asthma may also have vocal cord dysfunction (VCD), which leads to poor control of the asthma. Once patients are diagnosed with difficult-to-treat asthma with poor control, VCD should be excluded or treated accordingly. The gold standard for diagnosis of VCD is to perform a laryngoscopy. However, this procedure is invasive and may not be suitable for patients with difficult-to-treat asthma. Four-dimensional (4D) dynamic volume computed tomography (CT) is a noninvasive method for quantification of laryngeal movement, and can serve as an alternative for the diagnosis of VCD. Herein, we present a series of five cases with difficult-to-treat asthma patients who were diagnosed with VCD by 4D dynamic volume CT. Clinicians should be alert to the possibility of VCD when poor control is noted in patients with asthma. Early diagnosis by noninvasive 4D dynamic volume CT can decrease excessive doses of inhaled corticosteroids.

  6. Development of Four Dimensional Human Model that Enables Deformation of Skin, Organs and Blood Vessel System During Body Movement - Visualizing Movements of the Musculoskeletal System.

    Science.gov (United States)

    Suzuki, Naoki; Hattori, Asaki; Hashizume, Makoto

    2016-01-01

    We constructed a four dimensional human model that is able to visualize the structure of a whole human body, including the inner structures, in real-time to allow us to analyze human dynamic changes in the temporal, spatial and quantitative domains. To verify whether our model was generating changes according to real human body dynamics, we measured a participant's skin expansion and compared it to that of the model conducted under the same body movement. We also made a contribution to the field of orthopedics, as we were able to devise a display method that enables the observer to more easily observe the changes made in the complex skeletal muscle system during body movements, which in the past were difficult to visualize.

  7. Establishment of Rural Sports Combined System of "Four-Dimensional Health"%农村体育"四维健康"组合体系的构建

    Institute of Scientific and Technical Information of China (English)

    伊向仁; 李强

    2009-01-01

    根据农村传统习惯和场地特征,结合农民的生活规律、劳动特点,构建具有农村特色、切实可行的农村体育"四维健康"组合体系.包括农村体育身体健康服务体系;农村体育心理健康服务体系;农村体育社会健康服务体系;农村体育环境健康服务体系.通过政府组织、经济杠杆、体育文化、职业教育、法律法规意识引导等,建立农村体育"四维健康"长期引导机制.%Based on rural traditional habits and playground features and combined with peasants' life law and working characteristics, it established a distinctive-rural-feature-having and feasible rural sports combined system of "Four-dimensional Health", which included the service system of rural sport and physical health, the service system of peasants' sport and mental health, the service system of rural sport and social health as well as the service system of rural sport and environment health, and meanwhile proposed to set up a long-term guiding mechanism of "Four-dimensional Health" of rural sport through the guidances from government departments, economic lever, science and technology, sports culture, vocational education, consciousness of law and statutes and so forth.

  8. Four-dimensional electron microscopy.

    Science.gov (United States)

    Zewail, Ahmed H

    2010-04-09

    The discovery of the electron over a century ago and the realization of its dual character have given birth to one of the two most powerful imaging instruments: the electron microscope. The electron microscope's ability to resolve three-dimensional (3D) structures on the atomic scale is continuing to affect different fields, including materials science and biology. In this Review, we highlight recent developments and inventions made by introducing the fourth dimension of time in electron microscopy. Today, ultrafast electron microscopy (4D UEM) enables a resolution that is 10 orders of magnitude better than that of conventional microscopes, which are limited by the video-camera rate of recording. After presenting the central concept involved, that of single-electron stroboscopic imaging, we discuss prototypical applications, which include the visualization of complex structures when unfolding on different length and time scales. The developed UEM variant techniques are several, and here we illucidate convergent-beam and near-field imaging, as well as tomography and scanning-pulse microscopy. We conclude with current explorations in imaging of nanomaterials and biostructures and an outlook on possible future directions in space-time, 4D electron microscopy.

  9. Four dimensional trace space measurement

    CERN Document Server

    Hernández, M E; Winick, Herman; Smith, T

    2003-01-01

    Future high energy colliders and FELs (Free Electron Lasers) such as the proposed LCLS (Linac Coherent Light Source) at SLAC require high brightness electron beams. In general a high brightness electron beam will contain a large number of electrons that occupy a short longitudinal duration, can be focused to a small transverse area while having small transverse divergences. Therefore the beam must have a high peak current and occupy small areas in transverse phase space and so have small transverse emittances. Additionally the beam should propagate at high energy and have a low energy spread to reduce chromatic effects. The requirements of the LCLS for example are pulses which contain 1010 electrons in a temporal duration of 10 ps FWHM with projected normalized transverse emittances of 1π mm mrad. Currently the most promising method of producing such a beam is the RF photoinjector. The GTF (Gun Test Facility) at SLAC was constructed to produce and characterize laser and electron beams which fulfill the...

  10. Four-Dimensional Golden Search

    Energy Technology Data Exchange (ETDEWEB)

    Fenimore, Edward E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-25

    The Golden search technique is a method to search a multiple-dimension space to find the minimum. It basically subdivides the possible ranges of parameters until it brackets, to within an arbitrarily small distance, the minimum. It has the advantages that (1) the function to be minimized can be non-linear, (2) it does not require derivatives of the function, (3) the convergence criterion does not depend on the magnitude of the function. Thus, if the function is a goodness of fit parameter such as chi-square, the convergence does not depend on the noise being correctly estimated or the function correctly following the chi-square statistic. And, (4) the convergence criterion does not depend on the shape of the function. Thus, long shallow surfaces can be searched without the problem of premature convergence. As with many methods, the Golden search technique can be confused by surfaces with multiple minima.

  11. Cardiac arrest

    Science.gov (United States)

    ... Article.jsp. Accessed June 16, 2014. Myerburg RJ, Castellanos A. Approach to cardiac arrest and life-threatening ... PA: Elsevier Saunders; 2011:chap 63. Myerburg RJ, Castellanos A. Cardiac arrest and audden aardiac death. In: ...

  12. The Value of Down Syndrome Screening Combined with Four Dimensional Colour Doppler Ultrasound in Prenatal Diagnosis%唐氏筛查联合四维彩超在产前诊断中的价值

    Institute of Scientific and Technical Information of China (English)

    邓玲; 汤辉; 黎兴盛; 郭平

    2015-01-01

    Objective:To explore the application value of Down syndrome screening combined with four dimensional colour doppler ultrasound in prenatal diagnosis.Method:From January 2011 to December 2014, 2578 cases of pregnant women for 14 to 24 weeks were selected in maternity clinics in our hospital,they were examined by Down syndrome screening and four dimensional colour doppler ultrasound.Result:2578 cases of pregnant women were all examined by Down syndrome screening and four dimensional colour doppler ultrasound. Positive rate of Down syndrome screening was 4.84%,positive rate of was four dimensional colour doppler ultrasound was 0.96%,positive rate of combined examination was 5.81%, positive rate between Down syndrome screening and combined examination had no statistical significance (P>0.05),positive rate between four dimensional colour doppler ultrasound and combined examination had statistical significance(P0.05),与四维彩超筛查比较差异有统计学意义(P<0.05).结论:唐氏筛查联合四维彩超在产前筛查中的意义重大,可提高唐氏儿和其他染色体病儿及各种畸形的诊断率,及时做出判断是否终止妊娠,为家庭和社会减轻了沉重的负担.

  13. Four-dimensional spatio-temporal image correlation technology in detection of fetal heart malformation at early-second trimester%四维超声STIC技术检测中孕早期胎儿心脏畸形

    Institute of Scientific and Technical Information of China (English)

    赵艳春; 吕国荣; 李敏; 谢婧娴; 凌乐文

    2013-01-01

    目的 探讨四维超声时空关联成像(STIC)技术筛查中孕早期胎儿先天性心脏病的临床价值.方法 连续性选取70胎14~17+6周高危妊娠胎儿,先行二维超声筛查,再应用四维超声STIC技术采集胎儿心脏容积数据;由同1名超声医师采用单盲法进行分析,并将二维超声和四维超声STIC技术的诊断结果与随访结果进行比较.结果 58胎高危胎儿获得随访结果,其中心脏异常16胎,心脏正常42胎.STIC技术正确诊断率为86.21%(50/58),3胎诊断不完整,漏诊2胎,误诊3胎;二维超声正确诊断率为91.38%(53/58),1胎诊断不完整,漏诊1胎,误诊3胎;两者正确诊断率差异无统计学意义(x2 =0.78,P>0.05).四维超声STIC联合二维超声后正确诊断率96.55%(56/58),明显高于单独应用STIC技术(x2 =3.94,P<0.0S).结论 四维超声STIC技术可用于诊断中孕早期胎儿先天性心脏病;将其纳入胎儿心脏二维超声产前早期筛查,可提高正确诊断率.%Objective To investigate the clinical value of four-dimensional spatio-temporal image correlation (STIC) technology in detection of fetal congenital heart disease (CHD) at early second trimester. Methods A cross-sectional study was performed on high-risk fetuses (n=70) from 14 to 17+6 gestational age. The data of fetal heart volume were acquired with STIC, and postprocessed after routine two-dimensional ultrasonography (2D US) was performed on all fetuses. The results were analyzed by one independent examiner who was blind to the fetal outcomes. Then the prenatal diagnosis value of STIC and 2D US were evaluated according to postnatal detailed follow-up. Results A total of 58 fetuses who had detailed postnatal following-up data were included, 42 of them had normal cardiac structure, 16 were found with CHD. The accurate diagnostic rate of prenatal STIC was 86. 21% (50/58). Prenatal STIC incompletedly diagnosed 3 fetuses, missed 2 fetuses, misdiagnosed 3 fetuses. The accurate

  14. Technical Note: Four-dimensional variational data assimilation for inverse modelling of atmospheric methane emissions: method and comparison with synthesis inversion

    Directory of Open Access Journals (Sweden)

    J. F. Meirink

    2008-06-01

    Full Text Available A four-dimensional variational (4D-var data assimilation system for inverse modelling of atmospheric methane emissions is presented. The system is based on the TM5 atmospheric transport model. It can be used for assimilating large volumes of measurements, in particular satellite observations and quasi-continuous in-situ observations, and at the same time it enables the optimization of a large number of model parameters, specifically grid-scale emission rates. Furthermore, the variational method allows to estimate uncertainties in posterior emissions. Here, the system is applied to optimize monthly methane emissions over a 1-year time window on the basis of surface observations from the NOAA-ESRL network. The results are rigorously compared with an analogous inversion by Bergamaschi et al. (2007, which was based on the traditional synthesis approach. The posterior emissions as well as their uncertainties obtained in both inversions show a high degree of consistency. At the same time we illustrate the advantage of 4D-Var in reducing aggregation errors by optimizing emissions at the grid scale of the transport model. The full potential of the assimilation system is exploited in Meirink et al. (2008, who use satellite observations of column-averaged methane mixing ratios to optimize emissions at high spatial resolution, taking advantage of the zooming capability of the TM5 model.

  15. Assimilating surface observations in a four-dimensional variational Doppler radar data assimilation system to improve the analysis and forecast of a squall line case

    Science.gov (United States)

    Chen, Xingchao; Zhao, Kun; Sun, Juanzhen; Zhou, Bowen; Lee, Wen-Chau

    2016-10-01

    This paper examines how assimilating surface observations can improve the analysis and forecast ability of a fourdimensional Variational Doppler Radar Analysis System (VDRAS). Observed surface temperature and winds are assimilated together with radar radial velocity and reflectivity into a convection-permitting model using the VDRAS four-dimensional variational (4DVAR) data assimilation system. A squall-line case observed during a field campaign is selected to investigate the performance of the technique. A single observation experiment shows that assimilating surface observations can influence the analyzed fields in both the horizontal and vertical directions. The surface-based cold pool, divergence and gust front of the squall line are all strengthened through the assimilation of the single surface observation. Three experiments—assimilating radar data only, assimilating radar data with surface data blended in a mesoscale background, and assimilating both radar and surface observations with a 4DVAR cost function—are conducted to examine the impact of the surface data assimilation. Independent surface and wind profiler observations are used for verification. The result shows that the analysis and forecast are improved when surface observations are assimilated in addition to radar observations. It is also shown that the additional surface data can help improve the analysis and forecast at low levels. Surface and low-level features of the squall line—including the surface warm inflow, cold pool, gust front, and low-level wind—are much closer to the observations after assimilating the surface data in VDRAS.

  16. Real-Space Imaging of Carrier Dynamics of Materials Surfaces by Second-Generation Four-Dimensional Scanning Ultrafast Electron Microscopy

    KAUST Repository

    Sun, Jingya

    2015-09-14

    In the fields of photocatalysis and photovoltaics, ultrafast dynamical processes, including carrier trapping and recombination on material surfaces, are among the key factors that determine the overall energy conversion efficiency. A precise knowledge of these dynamical events on the nanometer (nm) and femtosecond (fs) scales was not accessible until recently. The only way to access such fundamental processes fully is to map the surface dynamics selectively in real space and time. In this study, we establish a second generation of four-dimensional scanning ultrafast electron microscopy (4D S-UEM) and demonstrate the ability to record time-resolved images (snapshots) of material surfaces with 650 fs and ∼5 nm temporal and spatial resolutions, respectively. In this method, the surface of a specimen is excited by a clocking optical pulse and imaged using a pulsed primary electron beam as a probe pulse, generating secondary electrons (SEs), which are emitted from the surface of the specimen in a manner that is sensitive to the local electron/hole density. This method provides direct and controllable information regarding surface dynamics. We clearly demonstrate how the surface morphology, grains, defects, and nanostructured features can significantly impact the overall dynamical processes on the surface of photoactive-materials. In addition, the ability to access two regimes of dynamical probing in a single experiment and the energy loss of SEs in semiconductor-nanoscale materials will also be discussed.

  17. Dimensional Reduction of N=1, E_8 SYM over SU(3)/U(1) x U(1) x Z_3 and its four-dimensional effective action

    CERN Document Server

    Irges, Nikos; Zoupanos, George

    2011-01-01

    We present an extension of the Standard Model inspired by the E_8 x E_8 Heterotic String. In order that a reasonable effective Lagrangian is presented we neglect everything else other than the ten-dimensional N=1 supersymmetric Yang-Mills sector associated with one of the gauge factors and certain couplings necessary for anomaly cancellation. We consider a compactified space-time M_4 x B_0 / Z_3, where B_0 is the nearly-Kaehler manifold SU(3)/U(1) x U(1) and Z_3 is a freely acting discrete group on B_0. Then we reduce dimensionally the E_8 on this manifold and we employ the Wilson flux mechanism leading in four dimensions to an SU(3)^3 gauge theory with the spectrum of a N=1 supersymmetric theory. We compute the effective four-dimensional Lagrangian and demonstrate that an extension of the Standard Model is obtained with interesting features including a conserved baryon number and fixed tree level Yukawa couplings and scalar potential. The spectrum contains new states such as right handed neutrinos and heavy ...

  18. Four-dimensional magnetic resonance imaging for the determination of tumour movement and its evaluation using a dynamic porcine lung phantom

    Energy Technology Data Exchange (ETDEWEB)

    Remmert, G [Department of Medical Physics in Radiation Oncology, German Cancer Research Centre (DKFZ), 69120 Heidelberg (Germany); Biederer, J [Department of Radiology, German Cancer Research Centre (DKFZ), 69120 Heidelberg (Germany); Lohberger, F [Department of Medical Physics in Radiology, German Cancer Research Centre (DKFZ), 69120 Heidelberg (Germany); Fabel, M [Department of Radiology, German Cancer Research Centre (DKFZ), 69120 Heidelberg (Germany); Hartmann, G H [Department of Medical Physics in Radiation Oncology, German Cancer Research Centre (DKFZ), 69120 Heidelberg (Germany)

    2007-09-21

    A method of four-dimensional (4D) magnetic resonance imaging (MRI) has been implemented and evaluated. It consists of retrospective sorting and slice stacking of two-dimensional (2D) images using an external signal for motion monitoring of the object to be imaged. The presented method aims to determine the tumour trajectories based on a signal that is appropriate for monitoring the movement of the target volume during radiotherapy such that the radiation delivery can be adapted to the movement. For evaluation of the 4D-MRI method, it has been applied to a dynamic lung phantom, which exhibits periodic respiratory movement of a porcine heart-lung explant with artificial pulmonary nodules. Anatomic changes of the lung phantom caused by respiratory motion have been quantified, revealing hysteresis. The results demonstrate the feasibility of the presented method of 4D-MRI. In particular, it enables the determination of trajectories of periodically moving objects with an uncertainty in the order of 1 mm. (note)

  19. Four-dimensional magnetic resonance imaging for the determination of tumour movement and its evaluation using a dynamic porcine lung phantom.

    Science.gov (United States)

    Remmert, G; Biederer, J; Lohberger, F; Fabel, M; Hartmann, G H

    2007-09-21

    A method of four-dimensional (4D) magnetic resonance imaging (MRI) has been implemented and evaluated. It consists of retrospective sorting and slice stacking of two-dimensional (2D) images using an external signal for motion monitoring of the object to be imaged. The presented method aims to determine the tumour trajectories based on a signal that is appropriate for monitoring the movement of the target volume during radiotherapy such that the radiation delivery can be adapted to the movement. For evaluation of the 4D-MRI method, it has been applied to a dynamic lung phantom, which exhibits periodic respiratory movement of a porcine heart-lung explant with artificial pulmonary nodules. Anatomic changes of the lung phantom caused by respiratory motion have been quantified, revealing hysteresis. The results demonstrate the feasibility of the presented method of 4D-MRI. In particular, it enables the determination of trajectories of periodically moving objects with an uncertainty in the order of 1 mm.

  20. Three-dimensional electrode displacement elastography using the Siemens C7F2 fourSight four-dimensional ultrasound transducer.

    Science.gov (United States)

    Bharat, Shyam; Fisher, Ted G; Varghese, Tomy; Hall, Timothy J; Jiang, Jingfeng; Madsen, Ernest L; Zagzebski, James A; Lee, Fred T

    2008-08-01

    Because ablation therapy alters the elastic modulus of tissues, emerging strain imaging methods may enable clinicians for the first time to have readily available, cost-effective, real-time guidance to identify the location and boundaries of thermal lesions. Electrode displacement elastography is a method of strain imaging tailored specifically to ultrasound-guided electrode-based ablative therapies (e.g., radio-frequency ablation). Here tissue deformation is achieved by applying minute perturbations to the unconstrained end of the treatment electrode, resulting in localized motion around the end of the electrode embedded in tissue. In this article, we present a method for three-dimensional (3D) elastographic reconstruction from volumetric data acquired using the C7F2 fourSight four-dimensional ultrasound transducer, provided by Siemens Medical Solutions USA, Inc. (Issaquah, WA, USA). Lesion reconstruction is demonstrated for a spherical inclusion centered in a tissue-mimicking phantom, which simulates a thermal lesion embedded in a normal tissue background. Elastographic reconstruction is also performed for a thermal lesion created in vitro in canine liver using radio-frequency ablation. Postprocessing is done on the acquired raw radio-frequency data to form surface-rendered 3D elastograms of the inclusion. Elastographic volume estimates of the inclusion compare reasonably well with the actual known inclusion volume, with 3D electrode displacement elastography slightly underestimating the true inclusion volume.

  1. Application of a Four-dimensional Mathematical Model in the Establishment of an Early Post-burn Cerebral Oedema Model in Severely Burned Dogs.

    Science.gov (United States)

    Haitao, L; Dajun, Y; Kaifa, W; Xiuwu, B; Jiansen, S; Zongchen, Y

    2005-06-30

    The aim of this study was to explore the spatiotemporal development of cerebral oedema in the early stage of severe burn (50% TBSA, third degree), using a four-dimensional (4D) mathematical model. Twenty-six male mongrel dogs were randomly divided into control and 6, 12, 18, and 24 post-burn hour (PBH) groups. The manifestation of magnetic resonance imaging (MRI) and histopathology, changes of brain water content, and intracranial pressure were observed in each group respectively. A 4D mathematical model was established on the basis of the results of MRI scanning. Two turning points (6 and 18 PBH) and three phases of pathological change were displayed by the 4D mathematical model of cerebral oedema in the early stage of severe burn. The first phase was in the subclinical period, and effective treatment should therefore be performed as quickly as possible in order to prevent deterioration of post-burn cerebral oedema. The second phase (6-18 PBH), with pathological characteristics of cytotoxic cerebral oedema, was in the apoptosis period. The third stage (18-24 PBH) was the danger period of cerebral oedema. Intracranial pressure increased rapidly owing to the limitation of the cranial cavity. As a result, cerebral hernia could easily occur. An S-shape curve in the pathological process of cerebral oedema occurred in the early post-burn stage following severe burn.

  2. Optimization of acquisition parameters and accuracy of target motion trajectory for four-dimensional cone-beam computed tomography with a dynamic thorax phantom.

    Science.gov (United States)

    Shimohigashi, Yoshinobu; Araki, Fujio; Maruyama, Masato; Nakaguchi, Yuji; Nakato, Kengo; Nagasue, Nozomu; Kai, Yudai

    2015-01-01

    Our purpose in this study was to evaluate the performance of four-dimensional computed tomography (4D-CBCT) and to optimize the acquisition parameters. We evaluated the relationship between the acquisition parameters of 4D-CBCT and the accuracy of the target motion trajectory using a dynamic thorax phantom. The target motion was created three dimensionally using target sizes of 2 and 3 cm, respiratory cycles of 4 and 8 s, and amplitudes of 1 and 2 cm. The 4D-CBCT data were acquired under two detector configurations: "small mode" and "medium mode". The projection data acquired with scan times ranging from 1 to 4 min were sorted into 2, 5, 10, and 15 phase bins. The accuracy of the measured target motion trajectories was evaluated by means of the root mean square error (RMSE) from the setup values. For the respiratory cycle of 4 s, the measured trajectories were within 2 mm of the setup values for all acquisition times and target sizes. Similarly, the errors for the respiratory cycle of 8 s were <4 mm. When we used 10 or more phase bins, the measured trajectory errors were within 2 mm of the setup values. The trajectory errors for the two detector configurations showed similar trends. The acquisition times for achieving an RMSE of 1 mm for target sizes of 2 and 3 cm were 2 and 1 min, respectively, for respiratory cycles of 4 s. The results obtained in this study enable optimization of the acquisition parameters for target size, respiratory cycle, and desired measurement accuracy.

  3. Cerebral blood flow in a healthy Circle of Willis and two intracranial aneurysms: computational fluid dynamics versus four-dimensional phase-contrast magnetic resonance imaging.

    Science.gov (United States)

    Berg, Philipp; Stucht, Daniel; Janiga, Gábor; Beuing, Oliver; Speck, Oliver; Thévenin, Dominique

    2014-04-01

    Computational fluid dynamics (CFD) opens up multiple opportunities to investigate the hemodynamics of the human vascular system. However, due to numerous assumptions the acceptance of CFD among physicians is still limited in practice and validation through comparison is mandatory. Time-dependent quantitative phase-contrast magnetic resonance imaging PC-MRI measurements in a healthy volunteer and two intracranial aneurysms were carried out at 3 and 7 Tesla. Based on the acquired images, three-dimensional (3D) models of the aneurysms were reconstructed and used for the numerical simulations. Flow information from the MR measurements were applied as boundary conditions. The four-dimensional (4D) velocity fields obtained by CFD and MRI were qualitatively as well as quantitatively compared including cut planes and vector analyses. For all cases a high similarity of the velocity patterns was observed. Additionally, the quantitative analysis revealed a good agreement between CFD and MRI. Deviations were caused by minor differences between the reconstructed vessel models and the actual lumen. The comparisons between diastole and systole indicate that relative differences between MRI and CFD are intensified with increasing velocity. The findings of this study lead to the conclusion that CFD and MRI agree well in predicting intracranial velocities when realistic geometries and boundary conditions are provided. Due to the considerably higher temporal and spatial resolution of CFD compared to MRI, complex flow patterns can be further investigated in order to evaluate their role with respect to aneurysm formation or rupture. Nevertheless, special care is required regarding the vessel reconstruction since the geometry has a major impact on the subsequent numerical results.

  4. Detection of residual brain arteriovenous malformations after radiosurgery: diagnostic accuracy of contrast-enhanced four-dimensional MR angiography at 3.0 T

    Science.gov (United States)

    Lim, H K; Choi, C G; Kim, S M; Kim, J L; Lee, D H; Kim, S J; Suh, D C

    2012-01-01

    Objective To evaluate the diagnostic accuracy of four-dimensional MR angiography (4D-MRA) at 3.0 T for detecting residual arteriovenous malformations (AVMs) after Gamma Knife® (Elekta Instrument AB, Stockholm, Sweden) radiosurgery (GKRS). Methods We assessed 36 angiographically confirmed AVMs in 36 patients who had been treated with GKRS. 4D-MRA was performed after GKRS and the time intervals were 39.4±26.0 months [mean±standard deviation (SD)]. 4D-MRA was obtained at 3.0 T after contrast injection, with a measured voxel size of 1×1×1 mm and a temporal resolution of 1.1 s (13 patients) or a voxel size of 1×1×2 mm and a temporal resolution of 0.98 s (23 patients). X-ray angiography was performed as the standard reference within 53±47 days (mean±SD) after MRA. To determine a residual AVM, the 4D-MRA results were independently reviewed by two readers blinded to the X-ray angiography results. We evaluated diagnostic sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 4D-MRA for detection of a residual AVM. Results A residual AVM was identified in 13 patients (13/36, 36%) on X-ray angiography. According to Readers 1 and 2, 4D-MRA had a sensitivity of 79.6% and 64.3%, a specificity of 90.9% and 100%, a PPV of 84.6% and 100% and an NPV of 90% and 81.5%, respectively, and a diagnostic accuracy of 86.1% for Readers 1 and 2, for detecting residual AVMs after GKRS. Conclusion The diagnostic accuracy of 4D-MRA at 3.0 T seems high, but there is still the possibility of further improving the spatiotemporal resolution of this technique. PMID:22294705

  5. To what extent does the anxiety scale of the Four-Dimensional Symptom Questionnaire (4DSQ) detect specific types of anxiety disorder in primary care? A psychometric study

    Science.gov (United States)

    2014-01-01

    Background Anxiety scales may help primary care physicians to detect specific anxiety disorders among the many emotionally distressed patients presenting in primary care. The anxiety scale of the Four-Dimensional Symptom Questionnaire (4DSQ) consists of an admixture of symptoms of specific anxiety disorders. The research questions were: (1) Is the anxiety scale unidimensional or multidimensional? (2) To what extent does the anxiety scale detect specific DSM-IV anxiety disorders? (3) Which cut-off points are suitable to rule out or to rule in (which) anxiety disorders? Methods We analyzed 5 primary care datasets with standardized psychiatric diagnoses and 4DSQ scores. Unidimensionality was assessed through confirmatory factor analysis (CFA). We examined mean scores and anxiety score distributions per disorder. Receiver operating characteristic (ROC) analysis was used to determine optimal cut-off points. Results Total n was 969. CFA supported unidimensionality. The anxiety scale performed slightly better in detecting patients with panic disorder, agoraphobia, social phobia, obsessive compulsive disorder (OCD) and post traumatic stress disorder (PTSD) than patients with generalized anxiety disorder (GAD) and specific phobia. ROC-analysis suggested that ≥4 was the optimal cut-off point to rule out and ≥10 the cut-off point to rule in anxiety disorders. Conclusions The 4DSQ anxiety scale measures a common trait of pathological anxiety that is characteristic of anxiety disorders, in particular panic disorder, agoraphobia, social phobia, OCD and PTSD. The anxiety score detects the latter anxiety disorders to a slightly greater extent than GAD and specific phobia, without being able to distinguish between the different anxiety disorder types. The cut-off points ≥4 and ≥10 can be used to separate distressed patients in three groups with a relatively low, moderate and high probability of having one or more anxiety disorders. PMID:24761829

  6. Temporal averaging for analysis of four-dimensional whole-heart computed tomography perfusion of the myocardium: proof-of-concept study.

    Science.gov (United States)

    Feger, S; Shaban, A; Lukas, S; Kendziorra, C; Rief, M; Zimmermann, E; Dewey, M

    2017-03-01

    To assess the feasibility of four-dimensional (4D) whole-heart computed tomography perfusion (CTP) of the myocardium and the added value of temporal averaging of consecutive 3D datasets from different heartbeats for analysis. We included 30 patients with suspected or known coronary artery disease (CAD) who underwent 320-row coronary CT angiography (CTA) and myocardial CTP. Out of these, 15 patients underwent magnetic resonance myocardial perfusion imaging (MR MPI). All CTP examinations were initiated after 3 min of intravenous infusion of adenosine (140 µg/kg/min) and were performed dynamically covering the entire heart every heart beat over a period of 20 ± 3 heart beats. Temporal averaging for dynamic CTP visualisation was analysed for the combination of two, three, four, six, and eight consecutive 3D datasets. Input time attenuation curves (TAC) were delivered from measurement points in the centre of the left ventricle. In all 30 patients, myocardial 4D CTP was feasible and temporal averaging was successfully implemented for all planned combinations of 3D datasets. Temporal averaging of three consecutive 3D datasets showed best performance in the analysis of all CTP image quality parameters: noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), subjective image quality, and diagnostic accuracy with an improvement of SNR and CNR by a factor of 2.2 ± 1.3 and 1.3 ± 0.9. With increasing level of temporal averaging, the input TACs became smoother, but also shorter. Out of the 11 perfusion defects detected with MR MPI, 9 defects were also visible on the 4D CTP images. Whole-heart CTP of the myocardium is feasible and temporal averaging of dynamic datasets improves quantitative image quality parameters and visualization of perfusion defects while further studies are needed to assess its added value for quantification of perfusion parameters.

  7. MR selective flow-tracking cartography: a postprocessing procedure applied to four-dimensional flow MR imaging for complete characterization of cranial dural arteriovenous fistulas.

    Science.gov (United States)

    Edjlali, Myriam; Roca, Pauline; Rabrait, Cécile; Trystram, Denis; Rodriguez-Régent, Christine; Johnson, Kevin M; Wieben, Oliver; Turski, Patrick; Meder, Jean-François; Naggara, Olivier; Oppenheim, Catherine

    2014-01-01

    To assess the feasibility of a selective flow-tracking cartographic procedure applied to four-dimensional (4D) flow imaging and to demonstrate its usefulness in the characterization of dural arteriovenous fistulas (DAVFs). Institutional review board approval was obtained, and all patients provided written informed consent. Eight patients (nine DAVFs) underwent 3.0-T magnetic resonance (MR) imaging and digital subtraction angiography (DSA). Imaging examinations were performed within 24 hours of each other. 4D flow MR imaging was performed by using a 4D radial phase-contrast vastly undersampled isotropic projection reconstruction pulse sequence with an isotropic spatial resolution of 0.86 mm (5 minutes 35 seconds). Two radiologists independently reviewed images from MR flow-tracking cartography and reported the location of arterial feeder vessels and the venous drainage type and classified DAVFs according to the risk of rupture (Cognard classification). These results were compared with those at DSA. Quadratic weighted κ statistics with their 95% confidence intervals (CIs) were used to test intermodality agreement in the identification of arterial feeder vessels, draining veins, and Cognard classification. Interreader agreement for shunt location on MR images was perfect (κ = 1), with good-to-excellent interreader agreement for arterial feeder vessel identification (κ = 0.97; 95% CI = 0.92, 1.0), and matched in all cases with shunt location defined at DSA. There was good-to-excellent agreement between MR cartography and DSA in the definition of the main feeding arteries (κ = 0.92; 95% CI = 0.83, 1.0), presence of retrograde flow in dural sinuses (κ = 1), presence of retrograde cortical venous drainage (κ = 1), presence of venous ectasia (κ = 1), and final Cognard classification of DAVFs (κ = 1, standard error = 0.35). MR selective flow-tracking cartography enabled the noninvasive characterization of cranial DAVFs. © RSNA, 2013.

  8. Cardiac Sarcoidosis.

    Science.gov (United States)

    Birnie, David; Ha, Andrew C T; Gula, Lorne J; Chakrabarti, Santabhanu; Beanlands, Rob S B; Nery, Pablo

    2015-12-01

    Studies suggest clinically manifest cardiac involvement occurs in 5% of patients with pulmonary/systemic sarcoidosis. The principal manifestations of cardiac sarcoidosis (CS) are conduction abnormalities, ventricular arrhythmias, and heart failure. Data indicate that an 20% to 25% of patients with pulmonary/systemic sarcoidosis have asymptomatic (clinically silent) cardiac involvement. An international guideline for the diagnosis and management of CS recommends that patients be screened for cardiac involvement. Most studies suggest a benign prognosis for patients with clinically silent CS. Immunosuppression therapy is advocated for clinically manifest CS. Device therapy, with implantable cardioverter defibrillators, is recommended for some patients.

  9. The fetal cardiovascular response to increased placental vascular impedance to flow determined with four-dimensional ultrasound using spatiotemporal image correlation and virtual organ computer-aided analysis

    Science.gov (United States)

    Hamill, Neil; Romero, Roberto; Hassan, Sonia; Lee, Wesley; Myers, Stephen A.; Mittal, Pooja; Kusanovic, Juan Pedro; Balasubramaniam, Mamtha; Chaiworapongsa, Tinnakorn; Vaisbuch, Edi; Espinoza, Jimmy; Gotsch, Francesca; Goncalves, Luis F.; Mazaki-Tovi, Shali; Erez, Offer; Hernandez-Andrade, Edgar; Yeo, Lami

    2014-01-01

    Objective To determine if increased placental vascular impedance to flow is associated with changes in fetal cardiac function using spatiotemporal image correlation (STIC) and Virtual Organ Computer-aided AnaLysis (VOCAL). Study Design A cross-sectional study was performed in fetuses with an umbilical artery pulsatility index > 95th percentile (ABN). Ventricular volume (end-systole, end-diastole), stroke volume (SV), cardiac output (CO), adjusted CO, and ejection fraction (EF) were compared to those of 184 normal fetuses (NL). Results 1) 34 fetuses were evaluated at a median gestational age of 28.3 (range 20.6 – 36.9) weeks; 2) mean ventricular volumes were lower for ABN than NL (end-systole, end-diastole) with a proportionally greater decrease for left ventricular volume (vs. right); 3) mean left and right SV, CO, and adjusted CO were lower for ABN (vs. NL); 4) right ventricular volume, SV, CO, and adjusted CO exceeded the left in ABN fetuses; 5) mean EF was greater for ABN than NL; and 6) median left EF was greater (vs. right) in ABN fetuses. Conclusion Increased placental vascular impedance to flow is associated with changes in fetal cardiac function. PMID:23220270

  10. Cardiac Malpositions

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Shi Joon; Im, Chung Gie; Yeon, Kyung Mo; Hasn, Man Chung [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1979-06-15

    Cardiac Malposition refers to any position of the heart other than a left-sided heart in a situs solitus individual. Associated cardiac malformations are so complex that even angiocardiographic and autopsy studies may not afford an accurate information. Although the terms and classifications used to describe the internal cardiac anatomy and their arterial connections in cardiac malpositions differ and tend to be confusing, common agreement exists on the need for a segmental approach to diagnosis. Authors present 18 cases of cardiac malpositions in which cardiac catheterization and angiocardiography were done at the Department of Radiology, Seoul National University Hospital between 1971 and 1979. Authors analyzed the clinical, radiographic, operative and autopsy findings with the emphasis on the angiocardiographic findings. The results are as follows: 1. Among 18 cases with cardiac malpositions, 6 cases had dextrocardia with situs inversus, 9 cases had dextrocardia with situs solitus and 3 cases had levocardia with situs inversus. 2. There was no genuine exception to visceroatrial concordance rule. 3. Associated cardiac malpositions were variable and complex with a tendency of high association of transposition and double outlet varieties with dextrocardia in situs solitus and levocardia in situs inversus. Only one in 6 cases of dextrocardia with situs inversus had pure transposition. 4. In two cases associated pulmonary atresia was found at surgery which was not predicted by angiocardiography. 5. Because many of the associated complex lesions can be corrected surgically provided the diagnosis is accurate, the selective biplane angiocardiography with or without cineradiography is essential.

  11. SU-E-J-110: Dosimetric Analysis of Respiratory Motion Based On Four-Dimensional Dose Accumulation in Liver Stereotactic Body Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Kang, S; Kim, D; Kim, T; Kim, K; Cho, M; Shin, D; Suh, T [The Catholic University of Korea College of Medicine, Seoul (Korea, Republic of); Kim, S [Virginia Commonwealth University, Richmond, VA (United States); Park, S [Uijeongbu St.Mary’s Hospital, GyeongGi-Do (Korea, Republic of)

    2015-06-15

    Purpose: Respiratory motion in thoracic and abdominal region could lead to significant underdosing of target and increased dose to healthy tissues. The aim of this study is to evaluate the dosimetric effect of respiratory motion in conventional 3D dose by comparing 4D deformable dose in liver stereotactic body radiotherapy (SBRT). Methods: Five patients who had previously treated liver SBRT were included in this study. Four-dimensional computed tomography (4DCT) images with 10 phases for all patients were acquired on multi-slice CT scanner (Siemens, Somatom definition). Conventional 3D planning was performed using the average intensity projection (AIP) images. 4D dose accumulation was calculated by summation of dose distribution for all phase images of 4DCT using deformable image registration (DIR) . The target volume and normal organs dose were evaluated with the 4D dose and compared with those from 3D dose. And also, Index of achievement (IOA) which assesses the consistency between planned dose and prescription dose was used to compare target dose distribution between 3D and 4D dose. Results: Although the 3D dose calculation considered the moving target coverage, significant differences of various dosimetric parameters between 4D and 3D dose were observed in normal organs and PTV. The conventional 3D dose overestimated dose to PTV, however, there was no significant difference for GTV. The average difference of IOA which become ‘1’ in an ideal case was 3.2% in PTV. The average difference of liver and duodenum was 5% and 16% respectively. Conclusion: 4D dose accumulation which can provide dosimetric effect of respiratory motion has a possibility to predict the more accurate delivered dose to target and normal organs and improve treatment accuracy. This work was supported by the Radiation Technology R&D program (No. 2013M2A2A7043498) and the Mid-career Researcher Program (2014R1A2A1A10050270) through the National Research Foundation of Korea funded by the

  12. Real-time respiration monitoring using the radiotherapy treatment beam and four-dimensional computed tomography (4DCT)--a conceptual study.

    Science.gov (United States)

    Lu, Weiguo; Ruchala, Kenneth J; Chen, Ming-Li; Chen, Quan; Olivera, Gustavo H

    2006-09-21

    Real-time knowledge of intra-fraction motion, such as respiration, is essential for four-dimensional (4D) radiotherapy. Surrogate-based and internal-fiducial-based methods may suffer from one or many drawbacks such as false correlation, being invasive, delivering extra patient radiation, and requiring complicated hardware and software development and implementation. In this paper we develop a simple non-surrogate, non-invasive method to monitor respiratory motion during radiotherapy treatments in real time. This method directly utilizes the treatment beam and thus imposes no additional radiation to the patient. The method requires a pre-treatment 4DCT and a real-time detector system. The method combines off-line processes with on-line processes. The off-line processes include 4DCT imaging and pre-calculating detector signals at each phase of the 4DCT based on the planned fluence map and the detector response function. The on-line processes include measuring detector signal from the treatment beam, and correlating the measured detector signal with the pre-calculated signals. The respiration phase is determined as the position of peak correlation. We tested our method with extensive simulations based on a TomoTherapy machine and a 4DCT of a lung cancer patient. Three types of simulations were implemented to mimic the clinical situations. Each type of simulation used three different TomoTherapy delivery sinograms, each with 800 to 1000 projections, as input fluences. Three arbitrary breathing patterns were simulated and two dose levels, 2 Gy/fraction and 2 cGy/fraction, were used for simulations to study the robustness of this method against detector quantum noise. The algorithm was used to determine the breathing phases and this result was compared with the simulated breathing patterns. For the 2 Gy/fraction simulations, the respiration phases were accurately determined within one phase error in real time for most projections of the treatment, except for a few

  13. Development of an ultrasmall C-band linear accelerator guide for a four-dimensional image-guided radiotherapy system with a gimbaled x-ray head.

    Science.gov (United States)

    Kamino, Yuichiro; Miura, Sadao; Kokubo, Masaki; Yamashita, Ichiro; Hirai, Etsuro; Hiraoka, Masahiro; Ishikawa, Junzo

    2007-05-01

    We are developing a four-dimensional image-guided radiotherapy system with a gimbaled x-ray head. It is capable of pursuing irradiation and delivering irradiation precisely with the help of an agile moving x-ray head on the gimbals. Requirements for the accelerator guide were established, system design was developed, and detailed design was conducted. An accelerator guide was manufactured and basic beam performance and leakage radiation from the accelerator guide were evaluated at a low pulse repetition rate. The accelerator guide including the electron gun is 38 cm long and weighs about 10 kg. The length of the accelerating structure is 24.4 cm. The accelerating structure is a standing wave type and is composed of the axial-coupled injector section and the side-coupled acceleration cavity section. The injector section is composed of one prebuncher cavity, one buncher cavity, one side-coupled half cavity, and two axial coupling cavities. The acceleration cavity section is composed of eight side-coupled nose reentrant cavities and eight coupling cavities. The electron gun is a diode-type gun with a cerium hexaboride (CeB6) direct heating cathode. The accelerator guide can be operated without any magnetic focusing device. Output beam current was 75 mA with a transmission efficiency of 58%, and the average energy was 5.24 MeV. Beam energy was distributed from 4.95 to 5.6 MeV. The beam profile, measured 88 mm from the beam output hole on the axis of the accelerator guide, was 0.7 mm X 0.9 mm full width at half maximum (FWHM) width. The beam loading line was 5.925 (MeV)-Ib (mA) X 0.00808 (MeV/mA), where Ib is output beam current. The maximum radiation leakage of the accelerator guide at 100 cm from the axis of the accelerator guide was calculated as 0.33 cGy/min at the rated x-ray output of 500 cGy/min from the measured value. This leakage requires no radiation shielding for the accelerator guide itself per IEC 60601-2-1.

  14. The Four-Dimensional Symptom Questionnaire (4DSQ: a validation study of a multidimensional self-report questionnaire to assess distress, depression, anxiety and somatization

    Directory of Open Access Journals (Sweden)

    van Balkom Anton JLM

    2006-08-01

    Full Text Available Abstract Background The Four-Dimensional Symptom Questionnaire (4DSQ is a self-report questionnaire that has been developed in primary care to distinguish non-specific general distress from depression, anxiety and somatization. The purpose of this paper is to evaluate its criterion and construct validity. Methods Data from 10 different primary care studies have been used. Criterion validity was assessed by comparing the 4DSQ scores with clinical diagnoses, the GPs' diagnosis of any psychosocial problem for Distress, standardised psychiatric diagnoses for Depression and Anxiety, and GPs' suspicion of somatization for Somatization. ROC analyses and logistic regression analyses were used to examine the associations. Construct validity was evaluated by investigating the inter-correlations between the scales, the factorial structure, the associations with other symptom questionnaires, and the associations with stress, personality and social functioning. The factorial structure of the 4DSQ was assessed through confirmatory factor analysis (CFA. The associations with other questionnaires were assessed with Pearson correlations and regression analyses. Results Regarding criterion validity, the Distress scale was associated with any psychosocial diagnosis (area under the ROC curve [AUC] 0.79, the Depression scale was associated with major depression (AUC = 0.83, the Anxiety scale was associated with anxiety disorder (AUC = 0.66, and the Somatization scale was associated with the GPs' suspicion of somatization (AUC = 0.65. Regarding the construct validity, the 4DSQ scales appeared to have considerable inter-correlations (r = 0.35-0.71. However, 30–40% of the variance of each scale was unique for that scale. CFA confirmed the 4-factor structure with a comparative fit index (CFI of 0.92. The 4DSQ scales correlated with most other questionnaires measuring corresponding constructs. However, the 4DSQ Distress scale appeared to correlate with some other

  15. WE-D-BRA-03: Four-Dimensional Dose Reconstruction Through Retrospective Phase Determination Using Cine Images of Electronic Portal Imaging Device

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, J; Jung, J [East Carolina University, Greenville, NC (United States); Yi, B [Univ. of Maryland School Of Medicine, Baltimore, MD (United States); Kim, J [University of Pittsburgh Medical Center, Pittsburgh, PA (United States); Yeo, I [Loma Linda Univ Medical Center, Loma Linda, CA (United States)

    2015-06-15

    Purpose: To test a method to reconstruct a four-dimensional (4D) dose distribution using the correlation of pre-calculated 4D electronic portal imaging device (EPID) images and measured cine-EPID images. Methods: 1. A phantom designed to simulate a tumor in lung (a polystyrene block with 3.0 cm diameter embedded in cork) was placed on a sinusoidally moving platform with 2 cm amplitude and 4 sec/cycle. Ten-phase 4D CT images were acquired for treatment planning and dose reconstruction. A 6MV photon beam was irradiated on the phantom with static (field size=5×8.5 cm{sup 2}) and dynamic fields (sliding windows, 10×10 cm{sup 2}, X1 MLC closing in parallel with the tumor movement). 2. 4D and 3D doses were calculated forwardly on PTV (1 cm margin). 3. Dose images on EPID under the fields were calculated for 10 phases. 4. Cine EPID images were acquired during irradiation. 5. Their acquisition times were correlated to the phases of the phantom at which irradiation occurred by inter-comparing calculated “reference” EPID images with measured images (2D gamma comparison). For the dynamic beam, the tumor was hidden under MLCs during a portion of irradiation time; the correlation performed when the tumor was visible was extrapolated. 6. Dose for each phase was reconstructed on the 4D CT images and summed over all phases. The summation was compared with forwardly calculated 4D and 3D dose distributions. Monte Carlo methods were used for all calculations. Results: For the open and dynamic beams, the 4D reconstructed doses showed the pass rates of 92.7 % and 100 %, respectively, at the isocenter plane given 3% / 3 mm criteria. The better agreement of the dynamic beam was from its dose gradient which blurred the otherwise sharp difference between forward and reconstructed doses. This also contributed slightly better agreement in DVH of PTV. Conclusion: The feasibility of 4D reconstruction was demonstrated.

  16. TU-F-17A-09: Four-Dimensional Cone Beam CT Ventilation Imaging Can Detect Interfraction Lung Function Variations for Locally Advanced Lung Cancer Patients

    Energy Technology Data Exchange (ETDEWEB)

    Kipritidis, J; Keall, P [Radiation Physics Laboratory, University of Sydney, Sydney NSW 2006 Australia (Australia); Hugo, G; Weiss, E; Williamson, J [Department of Radiation Oncology, Virginia Commonwealth University, Richmond VA (United States)

    2014-06-15

    Purpose: Four-dimensional cone beam CT ventilation imaging (4D-CBCT VI) is a novel functional lung imaging modality requiring validation. We hypothesize that 4D-CBCT VI satisfies a necessary condition for validity: that intrafraction variations (e.g. due to poor 4D-CBCT image quality) are substantially different to interfraction variations (e.g. due to changes in underlying function). We perform the first comparison of intrafraction (pre/post fraction) and interfraction (week-to-week) 4D-CBCT VIs for locally advanced non small cell lung cancer (LA NSCLC) patients undergoing radiation therapy. Methods: A total of 215 4D-CBCT scans were acquired for 19 LA NSCLC patients over 4-6 weeks of radiation therapy, including 75 pairs of pre-/post-fraction scans on the same day. 4D-CBCT VIs were obtained by applying state-of-the-art, B-spline deformable image registration to obtain the Jacobian determinant of deformation between the end-exhale and end-inhale phases. All VIs were deformably registered to the corresponding first day scan, normalized between the 10th and 90th percentile values and cropped to the ipsilateral lung only. Intrafraction variations were assessed by computing the mean and standard deviation of voxel-wise differences between all same-day pairs of pre-/post-fraction VIs. Interfraction differences were computed between first-day VIs and treatment weeks 2, 4 and 6 for all 19 patients. We tested the hypothesis by comparing cumulative distribution functions (CDFs) of intrafraction and interfraction ventilation differences using two-sided Kolmogorov-Smirnov goodness-of-fit tests. Results: The (mean ± std. dev.) of intrafraction differences was (−0.007 ± 0.079). Interfraction differences for weeks 2, 4 and 6 were (−0.035 ± 0.103), (−0.006 ± 0.094) and (−0.019 ± 0.127) respectively. For week 2, the changes in CDFs for intrafraction and interfraction differences approached statistical significance (p=0.099). Conclusion: We have shown that 4D-CBCT VI

  17. SU-F-303-13: Initial Evaluation of Four Dimensional Diffusion- Weighted MRI (4D-DWI) and Its Effect On Apparent Diffusion Coefficient (ADC) Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y [Duke University Medical Physics Program (United States); Yin, F; Czito, B; Bashir, M; Palta, M; Cai, J [Duke University Medical Center, Durham, NC (United States); Zhong, X; Dale, B [Siemens Healthcare, Durham, NC (United States)

    2015-06-15

    Purpose: Diffusion-weighted imaging(DWI) has been shown to have superior tumor-to-tissue contrast for cancer detection.This study aims at developing and evaluating a four dimensional DWI(4D-DWI) technique using retrospective sorting method for imaging respiratory motion for radiotherapy planning,and evaluate its effect on Apparent Diffusion Coefficient(ADC) measurement. Materials/Methods: Image acquisition was performed by repeatedly imaging a volume of interest using a multi-slice single-shot 2D-DWI sequence in the axial planes and cine MRI(served as reference) using FIESTA sequence.Each 2D-DWI image were acquired in xyz-diffusion-directions with a high b-value(b=500s/mm2).The respiratory motion was simultaneously recorded using bellows.Retrospective sorting was applied in each direction to reconstruct 4D-DWI.The technique was evaluated using a computer simulated 4D-digital human phantom(XCAT),a motion phantom and a healthy volunteer under an IRB-approved study.Motion trajectories of regions-of-interests(ROI) were extracted from 4D-DWI and compared with reference.The mean motion trajectory amplitude differences(D) between the two was calculated.To quantitatively analyze the motion artifacts,XCAT were controlled to simulate regular motion and the motions of 10 liver cancer patients.4D-DWI,free-breathing DWI(FB- DWI) were reconstructed.Tumor volume difference(VD) of each phase of 4D-DWI and FB-DWI from the input static tumor were calculated.Furthermore, ADC was measured for each phase of 4D-DWI and FB-DWI data,and mean tumor ADC values(M-ADC) were calculated.Mean M-ADC over all 4D-DWI phases was compared with M-ADC calculated from FB-DWI. Results: 4D-DWI of XCAT,the motion phantom and the healthy volunteer demonstrated the respiratory motion clearly.ROI D values were 1.9mm,1.7mm and 2.0mm,respectively.For motion artifacts analysis,XCAT 4D-DWI images show much less motion artifacts compare to FB-DWI.Mean VD for 4D-WDI and FB-DWI were 8.5±1.4% and 108±15

  18. Cardiac cameras.

    Science.gov (United States)

    Travin, Mark I

    2011-05-01

    Cardiac imaging with radiotracers plays an important role in patient evaluation, and the development of suitable imaging instruments has been crucial. While initially performed with the rectilinear scanner that slowly transmitted, in a row-by-row fashion, cardiac count distributions onto various printing media, the Anger scintillation camera allowed electronic determination of tracer energies and of the distribution of radioactive counts in 2D space. Increased sophistication of cardiac cameras and development of powerful computers to analyze, display, and quantify data has been essential to making radionuclide cardiac imaging a key component of the cardiac work-up. Newer processing algorithms and solid state cameras, fundamentally different from the Anger camera, show promise to provide higher counting efficiency and resolution, leading to better image quality, more patient comfort and potentially lower radiation exposure. While the focus has been on myocardial perfusion imaging with single-photon emission computed tomography, increased use of positron emission tomography is broadening the field to include molecular imaging of the myocardium and of the coronary vasculature. Further advances may require integrating cardiac nuclear cameras with other imaging devices, ie, hybrid imaging cameras. The goal is to image the heart and its physiological processes as accurately as possible, to prevent and cure disease processes.

  19. Unified treatment of one-range addition theorems for integer and non-integer n-STO, -GTO and-generalized exponential type orbitals with hyperbolic cosine in position, momentum and four-dimensional spaces

    Institute of Scientific and Technical Information of China (English)

    I. I. Guseinov

    2012-01-01

    Simpler formulas are derived for one-range addition theorems for the integer and noninteger n generalized exponential type orbitals,momentum space orbitals,and hyperspherical harmonics with hyperbolic cosine (GETO HC,GMSO HC,and GHSH HC) in position,momentum and four-dimensional spaces,respectively.The final results are expressed in terms of one-range addition theorems of complete orthonormal sets of ψα-exponential type orbitals,(φ)α-momentum space orbitals and zα-hyperspherical harmonics.We notice that the one-range addition theorems for integer and noninteger n-Slater type orbitals and Gaussian type orbitals in position,momentum and four dimensional spaces are special cases of GETO HC,GMSO HC,and GHSH HC.The theorems presented can be useful in the accurate study of the electronic structure of atomic and molecular systems.

  20. The Clinical Value of Four-dimensional Ultrasound in Pregnancy Diagnosis of Cleft Lip and Palate%分析四维超声在中孕期胎儿唇腭裂诊断中的临床价值

    Institute of Scientific and Technical Information of China (English)

    李妍钰

    2016-01-01

    Objective To assess the prenatal diagnosis of fetal cleft lip and palate in promoting the clinical effectiveness of four-dimensional ultrasound solutions. Methods A total of 17 958 cases of fetus during pregnancy were randomly selected from April 2014 to December 2015, the late confirms 40 cases of fetal cleft lip and palate, all take the four-dimensional ultrasound, observe all the fetal diagnosis. Results In the fetus, the four dimensional ultrasonic testing found that fetal cleft lip and palate, a total of 39 cases, the coincidence rate of 97.50% (P>0.05). Conclusion In the prenatal diagnosis of fetal cleft lip and palate, promote the four-dimensional ultrasound has the feasibility, the operation is convenient, is worth promoting.%目的:评定中孕期胎儿唇腭裂诊断中推行四维超声方案的临床有效性。方法随机选择我院2014年4月~2015年12月接收的中孕期胎儿共17958例,后期证实唇腭裂胎儿40例,均接受四维超声方案,观察所有入选胎儿诊断结果。结果入选的胎儿中,四维超声检测发现唇腭裂胎儿共39例,其符合率97.50%,与后期追踪结果对比差异无统计学意义(P >0.05)。结论在中孕期胎儿唇腭裂诊断中,推行四维超声方案具有可行性,操作便捷。

  1. 四维超声检查对胎儿唇腭裂的诊断价值%Four dimensional ultrasound in diagnosis of fetal cleft lip and cleft palate

    Institute of Scientific and Technical Information of China (English)

    莫慧端; 吴忠明; 蔡碧琼; 曾思惠

    2015-01-01

    Objective To investigate the value of four-dimensional color Doppler in diagnosis of fetal cleft lip and cleft palate.Methods The four-dimensional color Doppler for 24-28weeks of pregnancy in 13 548 pregnant women by prenatal ultrasound.Results Found 21 cases of fetal cleft lip and cleft palate,2 cases were missed,were confirmed.Conclusion Four dimensional color Doppler dynamic continuous observation of the fetal activity,plays an important role in diagnosis of fetal cleft lip and cleft palate and typing,which can increase the detection rate of fetal cleft lip and palate.%目的 探讨四维彩色多普勒诊断胎儿唇腭裂畸形的价值.方法 采用四维彩色多普勒对孕24~28周13 548例孕妇进行产前超声检查.结果 发现唇腭裂畸形胎儿21例,漏诊2例,均得以证实.结论 四维彩色多普勒动态连续观察胎儿的活动,对胎儿唇腭裂畸形的诊断及分型具有重要意义,能提高胎儿唇腭裂的检出率.

  2. 基于四维CT的肺体积及呼吸运动分析%Four-dimensional CT in the study of lung volume and respiratory movement

    Institute of Scientific and Technical Information of China (English)

    孙宗文; 黄晓延; 包勇; 张黎; 黄劭敏; 樊卫; 陈明; 邓小武

    2008-01-01

    Objective To evaluate the respiratory movement of the both lungs with four-dimensional CT(4DCT), and determine the optimal respiratory phase series CT images for radiation dose calculation. Methods From November 2005 to November 2006,thirty patients with lung cancer who received 4DCT scan were enrolled,including 15 left and 15 right lung cancer cases,25 men and 5 women. The media age was 55 (35-78) years old. After 4DCT scanning, the image was treated with Advantage 4D workstation,and then transmitted into Pinnacle station( Adac 7.4). The both lungs were automatically outlined using Pinnacle station with CT recognition value of-900 to-200 Hu. Then-the same physician examined the unreasonable parts and revised them. After the delineation was completed,the volume of 10 respiratory phases of lung was obtained. Results The average respiratory phase in inspiratory and expiratory phases was 78.87%±2.71% and 26.32%±3.17% in the tumor located lung,77.55%±2.81% and 24.73%±2.55% in the healthy lung. The maximum and minimum mean volume was 106.48%±3.00% and 94.23%±2.78% in the tumor located lung,107.47%±2.43% and 93.65%±2.32% in the healthy lung. The volume at the end of inspiratory and expiratory was 106.43%±3.07% and 94.63%±2.71% in the tumor located lung, 107.37%±4.62% and 93.98%±2.34% in the healthy lung. Conclusions The series CT images scan on 20% ,30% and 80% respiratory phases are reasonable for radiation dose calculation. The maximum and minimum average lung volumes are almost equal to those at the end of inspiratory and expiratory.%目的 应用四维CT(4DCT)评价肺癌患者肺的运动,并初步选择适合进行剂量计算的呼吸时相.方法 选择30例在中山大学肿瘤医院接受4DCT扫描的肺癌患者,左、右肺患者均为15例;男25例、女5例;中位年龄55岁(35~78岁).CT扫描完成后所得到的影像资料经4D软件处理后传至Pinnacle工作站,应用该软件自动勾画功能勾画双侧肺轮廓,自动怪勾画

  3. Four-dimensional MAP-RBI-EM image reconstruction method with a 4D motion prior for 4D gated myocardial perfusion SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Taek-Soo; Tsui, Benjamin M.W. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Radiology; Gullberg, Grant T. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

    2011-07-01

    We evaluated and proposed here a 4D maximum a posteriori rescaled-block iterative (MAP-RBI)-EM image reconstruction method with a motion prior to improve the accuracy of 4D gated myocardial perfusion (GMP) SPECT images. We hypothesized that a 4D motion prior which resembles the global motion of the true 4D motion of the heart will improve the accuracy of the reconstructed images with regional myocardial motion defect. Normal heart model in the 4D XCAT (eXtended CArdiac-Torso) phantom is used as the prior in the 4D MAP-RBI-EM algorithm where a Gaussian-shaped distribution is used as the derivative of potential function (DPF) that determines the smoothing strength and range of the prior in the algorithm. The mean and width of the DPF equal to the expected difference between the reconstructed image and the motion prior, and smoothing range, respectively. To evaluate the algorithm, we used simulated projection data from a typical clinical {sup 99m}Tc Sestamibi GMP SPECT study using the 4D XCAT phantom. The noise-free projection data were generated using an analytical projector that included the effects of attenuation, collimator-detector response and scatter (ADS) and Poisson noise was added to generated noisy projection data. The projection datasets were reconstructed using the modified 4D MAP-RBI-EM with various iterations, prior weights, and sigma values as well as with ADS correction. The results showed that the 4D reconstructed image estimates looked more like the motion prior with sharper edges as the weight of prior increased. It also demonstrated that edge preservation of the myocardium in the GMP SPECT images could be controlled by a proper motion prior. The Gaussian-shaped DPF allowed stronger and weaker smoothing force for smaller and larger difference of neighboring voxel values, respectively, depending on its parameter values. We concluded the 4D MAP-RBI-EM algorithm with the general motion prior can be used to provide 4D GMP SPECT images with improved

  4. 四维彩超检查在胎儿先心病诊断中的临床应用%Clinical Application of Four-dimensional Color Doppler Ultrasonography in the Diagnosis of Fetal Congenital Heart Disease

    Institute of Scientific and Technical Information of China (English)

    谢广平; 贾立娟; 杜学谦

    2016-01-01

    ABSTRACT:Objective To analyze the application value of four-dimensional color Doppler ultrasonography in the diagnosis of fetal congenital heart disease, and to provide a reliable reference for clinical practice. Methods The research subjects in this study were 90 cases of fetus,whose gestational age were 25 to 40 weeks. All subjects were examined by four-dimensional color Doppler ultrasound. The results of four-dimensional color Doppler ultrasound examination of these studies subjects were retrospective analyzed,such as fetal heart rate, the four chamber view, the lfow of the chamber, etc..At the same time, the results of follow-up were retrospectively analyzed. The follow-up results and contrast the four-dimensional color Doppler ultrasound examination results were compared.The accuracy of the four-dimensional color Doppler ultrasound examination for diagnosis of fetal congenital heart disease were calculated ,in order to investigate the application value of four-dimensional color Doppler ultrasonography in the diagnosis of fetal congenital heart disease. Results In the study, 6 cases were diagnosed as congenital heart disease by four-dimensional color Doppler ultrasonography. Follow up results showed that 8 cases were eventually diagnosed as congenital heart disease in the study. By comparing the four-dimensional color Doppler ultrasound examination results and follow-up results, the diagnosis rate of four-dimensional color Doppler ultrasound examination was 75%, 1 cases was misdiagnosis, 1 cases was missed diagnosis. Conclusion Prenatal four-dimensional color Doppler ultrasound examination can improve the diagnostic rate of fetal congenital heart disease, and provide a reliable reference for the early intervention of congenital heart disease. Four-dimensional color Doppler ultrasound examination can be widely used in the diagnosis of fetal congenital heart disease, can provide referenc e for the early diagnosis and intervention of congenital heart disease

  5. Cardiac echinococcosis

    Directory of Open Access Journals (Sweden)

    Ivanović-Krstić Branislava A.

    2002-01-01

    Full Text Available Cardiac hydatid disease is rare. We report on an uncommon hydatid cyst localized in the right ventricular wall, right atrial wall tricuspid valve left atrium and pericard. A 33-year-old woman was treated for cough, fever and chest pain. Cardiac echocardiograpic examination revealed a round tumor (5.8 x 4 cm in the right ventricular free wall and two smaller cysts behind that tumor. There were cysts in right atrial wall and tricuspidal valve as well. Serologic tests for hydatidosis were positive. Computed tomography finding was consistent with diagnosis of hydatid cyst in lungs and right hylar part. Surgical treatment was rejected due to great risk of cardiac perforation. Medical treatment with albendazole was unsuccessful and the patient died due to systemic hydatid involvement of the lungs, liver and central nervous system.

  6. Single-Breathhold Four-Dimensional Assessment of Left Ventricular Morphological and Functional Parameters by Magnetic Resonance Imaging Using the VAST Technique.

    Science.gov (United States)

    Rochitte, Carlos Eduardo; Azevedo, Clerio F; Rosário, Miguel A; Siqueira, Maria H R; Monsão, Victor; Saranathan, Manoj; Foo, Thomas K; Kalil Filho, Roberto; Cerri, Giovanni G; Ramires, José A F

    2011-01-01

    The accurate and reproducible assessment of cardiac volumes, function, and mass is of paramount importance in cardiology. In the present study we sought to determine whether the 3D cine-magnetic resonance (MR) technique, using the variable asymmetric sampling in time (VAST) approach, provided an accurate assessment of LV functional parameters when compared with the conventional 2D cine-MR technique. A total of 43 consecutive patients referred for a CMR examination for clinical reasons and 14 healthy volunteers were included in the study. Cine images were acquired using a steady-state free precession pulse sequence. Two different multiphase acquisitions were performed: conventional 2D cine-MR and 3D cine-MR. The short-axis cine images acquired by both cine-MR techniques were used for the quantitative assessment of LV end-diastolic, end-systolic and stroke volumes, LV mass and ejection fraction. All CMR examinations were completed successfully, with both cine-MR imaging techniques yielding interpretable diagnostic results in all patients. Regarding the quantitative assessment, Bland-Altman analyses demonstrated a good agreement between the measurements of both cine-MR techniques for all LV parameters. In addition, the agreement between 2D and 3D cine-MR techniques for the qualitative assessment of LV global function was perfect (kappa = 1.0, Ptechnique provides an accurate and reproducible quantitative assessment of LV volumes, mass and function when compared with the conventional 2D cine-MR method.

  7. Cardiac Rehabilitation

    Science.gov (United States)

    ... your risk of future heart problems, and to improve your health and quality of life. Cardiac rehabilitation programs increase ... exercise routine at home or at a local gym. You may also continue to ... health concerns. Education about nutrition, lifestyle and weight loss ...

  8. Cardiac Calcification

    Directory of Open Access Journals (Sweden)

    Morteza Joorabian

    2011-05-01

    Full Text Available There is a spectrum of different types of cardiac"ncalcifications with the importance and significance"nof each type of cardiac calcification, especially"ncoronary artery calcification. Radiologic detection of"ncalcifications within the heart is quite common. The"namount of coronary artery calcification correlates"nwith the severity of coronary artery disease (CAD."nCalcification of the aortic or mitral valve may indicate"nhemodynamically significant valvular stenosis."nMyocardial calcification is a sign of prior infarction,"nwhile pericardial calcification is strongly associated"nwith constrictive pericarditis. A spectrum of different"ntypes of cardiac calcifications (linear, annular,"ncurvilinear,... could be seen in chest radiography and"nother imaging modalities. So a carful inspection for"ndetection and reorganization of these calcifications"nshould be necessary. Numerous modalities exist for"nidentifying coronary calcification, including plain"nradiography, fluoroscopy, intravascular ultrasound,"nMRI, echocardiography, and conventional, helical and"nelectron-beam CT (EBCT. Coronary calcifications"ndetected on EBCT or helical CT can be quantifie,"nand a total calcification score (Cardiac Calcification"nScoring may be calculated. In an asymptomatic"npopulation and/or patients with concomitant risk"nfactors like diabetes mellitus, determination of the"npresence of coronary calcifications identifies the"npatients at risk for future myocardial infarction and"ncoronary artery disease. In patients without coronary"ncalcifications, future cardiovascular events could"nbe excluded. Therefore, detecting and recognizing"ncalcification related to the heart on chest radiography"nand other imaging modalities such as fluoroscopy, CT"nand echocardiography may have important clinical"nimplications.

  9. CMTO Four-dimensional Analysis Method of Competitive Intelligence and Its Application%竞争情报分析的CMTO四维分析法及其应用

    Institute of Scientific and Technical Information of China (English)

    苗红; 宋昱晓; 黄鲁成; 娄岩; 王晓宇

    2015-01-01

    Competitive intelligence analysis method is the key way to acquire the most accurate competitive intelligence It is also the basis of competitive intelligence application to be realized. This paper proposes a"Capability-Market-Time-Opportunity" four-dimensional a-nalysis method ( hereinafter referred to as CMTO four-dimensional analysis method) , which offsets the deficiency of the CMT three-di-mensional analysis for lack of direction caused by negligence of competitive opportunities analysis . And this method augments the amount of information in competitive intelligence analysis. This paper carries out empirical study on the application of CMTO four-dimensional a-nalysis method by taking wearable technology. For example,this method verifies the feasibility and superiority of CMTO. Research results show that the following fields are more competitive in the future:carrier and material, measurement, battery and circuit, etc. CMTO can help enterprises by providing fairly comprehensive, valuable intelligence information.%竞争情报分析方法是获取竞争情报最精准、最有价值的关键途径,也是竞争情报应用得以实现的基础。提出一种“市场-能力-时间-机会”四维分析方法(简称CMTO四维分析法),弥补了CMT三维分析法未考虑分析竞争机会而缺乏方向性的不足,增加了竞争情报分析的信息量。并用可穿戴技术验证了该方法的可行性及优越性。研究表明未来竞争机会较大的技术领域集中在载体和材料、测量、电池和电路装置等,为辅助企业决策提供了较为全面而有价值的情报信息。

  10. 四维彩超在胎儿先天性畸形中的临床诊断价值%Four-dimensional color Doppler ultrasound in examination in prenatal screening of fetal malformation

    Institute of Scientific and Technical Information of China (English)

    罗妙云

    2014-01-01

    目的 探讨四维彩超在胎儿先天性畸形中的诊断价值.方法 随机观察我院2012年1月至2014年1月孕中晚期孕妇1200例产前常规超声检查结果,所有孕妇均进行了二维超声和四维超声检查,并随访至产后1个月,比较二维超声和四维超声诊断胎儿先天性畸形的准确性.结果 经产后临床证实,共发现先天性胎儿畸形34例,其中神经管畸形10例,心脏畸形8例,唇腭裂7例,泌尿系畸形3例,四肢畸形3例,腹部畸形1例,其他2例.四维超声检出畸形31例,与产后符合率91.17%;漏诊3例,其中多指畸形1例,脊柱裂2例.二维超声检出畸形26例,符合率76.47%;漏诊8例,其中唇腭裂2例,多指畸形2例,脊柱裂3例,足内翻1例.二维和四维超声的诊断符合率比较差异具有统计学意义(P<0.05).结论 四维超声更能多方位、多切面观察胎儿宫内发育情况,对诊断胎儿体表畸形具有更直观和准确的判断,具有较高的临床价值.%Objective To investigate the diagnostic value of four-dimensional (4D) color Doppler ultrasound examination in prenatal screening of fetal malformation.Methods 1200 pregnant women were observed and detected by four-dimensional color Doppler and two dimensional ultrasound.The results were compared with the results confirmed by clinical pathology.Results 34 cases were detected with congenital defects; among which,10 got defects in nervous system,8 heart deformity,7 cheilopalatognathus,3 urinary tract malformation,3 limb deformity,1 abdominal deformity,and the other 2 cases.31 cases were detected with deformity by four-dimensional color Doppler,with a postpartum coincidence rate of 91.17%; and 3 cases were misdiagnosed,of which 1 case had polydactyly deformity and 2 cases spina bifida.26 cases were detected with deformity by two-dimensional ultrasony,with a postpartum coincidence rate of 76.47%; and 8 cases were misdiagnosed,of which 2 cases had cleft lip and palate,2 case polydactyly

  11. 科技社团绩效评价四维框架模型研究%A four-dimensional model for the performance evaluations of science and technology associations

    Institute of Scientific and Technical Information of China (English)

    赵立新

    2011-01-01

    The connotation of science and technology association performance evaluations is analyzed,the main elements of society are explored,and a four-dimensional model for science and technology association performance evaluation is built.Finally,the performance evaluation index system of modern science and technology associations is proposed.%本文剖析了现代科技社团绩效评价的内涵,探讨了科技社团评价的主体要素,构建了科技社团绩效评价四维模型,提出了现代科技社团绩效评价的指标体系。

  12. 从授权研究方法到授权途径的探索--基于高校教师的调查%An Analysis of Working Status of University Teachers Based on the Four Dimensional Psychological Empowerment

    Institute of Scientific and Technical Information of China (English)

    王瑞文; 刘金兰

    2014-01-01

    通过对不同视角下授权研究方法的梳理,建立了以结构授权为环境、领导授权为条件、心理授权为目标的实现有效授权的模型,并通过结构方程对796名高校教师数据样本进行授权途径的模型拟合,结果表明:结构授权对领导授权和心理授权四个维度起重要的正向影响作用;领导授权对心理授权的工作意义维度起正向影响作用,对影响力维度起负向影响作用;心理授权作为授权途径的最终环节,是进行有效授权的目标。%Based on the survey of 796 university teachers' self-evaluations of their jobs and psychological empowerment, this study establishes a structural equation model to investigate the influence of the four dimensional psychological empowerment on teaching, scientific research and social service. The results show that the four dimensional paradigm has positive impacts on the working states of the teachers, among which competence greatly influenced teaching, scientific research and social service, and significance have positive impact only on teaching. This paper analyzes the internal factors that would influence the working stair of teachers in order to provide theoretical support for the performance improvement and extend the organizational context of psychological empowerment as well.

  13. Cardiac MRI in Athletes

    NARCIS (Netherlands)

    Luijkx, T.

    2012-01-01

    Cardiac magnetic resonance imaging (CMR) is often used in athletes to image cardiac anatomy and function and is increasingly requested in the context of screening for pathology that can cause sudden cardiac death (SCD). In this thesis, patterns of cardiac adaptation to sports are investigated with C

  14. Four-dimensional ultrafast electron microscopy.

    Science.gov (United States)

    Lobastov, Vladimir A; Srinivasan, Ramesh; Zewail, Ahmed H

    2005-05-17

    Electron microscopy is arguably the most powerful tool for spatial imaging of structures. As such, 2D and 3D microscopies provide static structures with subnanometer and increasingly with angstrom-scale spatial resolution. Here we report the development of 4D ultrafast electron microscopy, whose capability imparts another dimension to imaging in general and to dynamics in particular. We demonstrate its versatility by recording images and diffraction patterns of crystalline and amorphous materials and images of biological cells. The electron packets, which were generated with femtosecond laser pulses, have a de Broglie wavelength of 0.0335 angstroms at 120 keV and have as low as one electron per pulse. With such few particles, doses of few electrons per square ångstrom, and ultrafast temporal duration, the long sought after but hitherto unrealized quest for ultrafast electron microscopy has been realized. Ultrafast electron microscopy should have an impact on all areas of microscopy, including biological imaging.

  15. Recent developments in four-dimensional supergravity

    Science.gov (United States)

    Sharpe, Eric

    2011-10-01

    I will summarize recent work on gauge theories in supergravity, specifically concerning the `Fayet-Iliopoulos' parameter. In rigidly supersymmetric gauge theories, this parameter also appears and can vary continuously. In supergravity old lore held that it should always vanish. I will discuss recent developments showing that in fact it can be nonzero, but is quantized, and will explore various ramifications of that result.

  16. Four-dimensional CDT with toroidal topology

    Directory of Open Access Journals (Sweden)

    J. Ambjørn

    2017-09-01

    Full Text Available 3+1 dimensional Causal Dynamical Triangulations (CDT describe a quantum theory of fluctuating geometries without the introduction of a background geometry. If the topology of space is constrained to be that of a three-dimensional torus we show that the system will fluctuate around a dynamically formed background geometry which can be understood from a simple minisuperspace action which contains both a classical part and a quantum part. We determine this action by integrating out degrees of freedom in the full model, as well as by transfer matrix methods.

  17. Multidirectional four-dimensional shape measurement system

    Science.gov (United States)

    Lenar, Janusz; Sitnik, Robert; Witkowski, Marcin

    2012-03-01

    Currently, a lot of different scanning techniques are used for 3D imaging of human body. Most of existing systems are based on static registration of internal structures using MRI or CT techniques as well as 3D scanning of outer surface of human body by laser triangulation or structured light methods. On the other hand there is an existing mature 4D method based on tracking in time the position of retro-reflective markers attached to human body. There are two main drawbacks of this solution: markers are attached to skin (no real skeleton movement is registered) and it gives (x, y, z, t) coordinates only in those points (not for the whole surface). In this paper we present a novel multidirectional structured light measurement system that is capable of measuring 3D shape of human body surface with frequency reaching 60Hz. The developed system consists of two spectrally separated and hardware-synchronized 4D measurement heads. The principle of the measurement is based on single frame analysis. Projected frame is composed from sine-modulated intensity pattern and a special stripe allowing absolute phase measurement. Several different geometrical set-ups will be proposed depending on type of movements that are to be registered.

  18. A Four-Dimensional Product Innovativeness Typology

    DEFF Research Database (Denmark)

    Rosenø, Axel

    2005-01-01

    Product innovativeness is a key moderating variable for the study of innovationmanagement (Song & Montoya-Weiss 1998, p. 124). For this reason, some empiricalstudies of innovation management examine new product processes, critical successfactors, and market learning practices for incremental versus......) typology with four newproduct types; Leonard-Barton's (1995) five product types; and Veryzer's (1998a)four types in a two-by-two matrix.Interestingly, these two meta-perspectives on product innovativeness (i.e. 1. new tothe market and/or new to the company and 2. technological and/or marketnewness...... discontinuous newproduct projects (Song & Montoya-Weiss 1998; Atuahene-Gima 1995; Veryzer 1998a;Lynn et al. 1996; O'Connor 1998; Rice et al. 1998). By looking at both these types ofnew product development projects, empirical observations are likely to be morerealistic than those of studies that do...

  19. Reduction of N=1, E{sub 8} SYM over SU(3)/U(1)xU(1)xZ{sub 3} and its four-dimensional effective action

    Energy Technology Data Exchange (ETDEWEB)

    Irges, Nikos, E-mail: irges@mail.ntua.g [Department of Physics, National Technical University of Athens, Zografou Campus, GR-15780 Athens (Greece); Zoupanos, George [Institut fuer Theoretische Physik, Universitaet Heidelberg, Philosophenweg 16, D-69120 Heidelberg (Germany); Department of Physics, National Technical University of Athens, Zografou Campus, GR-15780 Athens (Greece)

    2011-04-04

    We propose an extension of the Standard Model inspired by the E{sub 8}xE{sub 8} Heterotic String. In order that a reasonable effective Lagrangian is presented we neglect everything else other than the ten-dimensional N=1 supersymmetric Yang-Mills sector associated with one of the gauge factors and certain couplings necessary for anomaly cancellation. We consider a compactified space-time M{sub 4}xB{sub 0}/Z{sub 3}, where B{sub 0} is the nearly Kaehler manifold SU(3)/U(1)xU(1) and Z{sub 3} is a freely acting discrete group on B{sub 0}. Then we reduce dimensionally the E{sub 8} on this manifold and we employ the Wilson flux mechanism leading in four dimensions to an SU(3){sup 3} gauge theory with the spectrum of a N=1 supersymmetric theory. We compute the effective four-dimensional Lagrangian and demonstrate that an extension of the Standard Model is obtained with interesting features including a conserved baryon number and fixed tree level Yukawa couplings and scalar potential. The spectrum contains new states such as right-handed neutrinos and heavy vector-like quarks.

  20. What Is Cardiac Rehabilitation?

    Science.gov (United States)

    ANSWERS by heart Treatments + Tests What Is Cardiac Rehabilitation? A cardiac rehabilitation (rehab) program takes place in a hospital or ... special help in making lifestyle changes. During your rehabilitation program you’ll… • Have a medical evaluation to ...

  1. Cardiac tamponade (image)

    Science.gov (United States)

    Cardiac tamponade is a condition involving compression of the heart caused by blood or fluid accumulation in the space ... they cannot adequately fill or pump blood. Cardiac tamponade is an emergency condition that requires hospitalization.

  2. Cardiac Procedures and Surgeries

    Science.gov (United States)

    ... Procedure Learn more about cardiac medications , including dual antiplatelet therapy, that you may need to take after your ... Procedure Learn more about cardiac medications , including dual antiplatelet therapy, that you may need to take after your ...

  3. Cardiac sodium channelopathies

    NARCIS (Netherlands)

    Amin, A.S.; Asghari-Roodsari, A.; Tan, H.L.

    2010-01-01

    Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (I-Na) during phase 0 of the cardiac action potential. The importance of I-Na for normal cardiac electrical activity is reflected by the high incidence of

  4. Cardiac sodium channelopathies

    NARCIS (Netherlands)

    Amin, A.S.; Asghari-Roodsari, A.; Tan, H.L.

    2010-01-01

    Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (I-Na) during phase 0 of the cardiac action potential. The importance of I-Na for normal cardiac electrical activity is reflected by the high incidence of

  5. Four-dimensional Map based Ni-MH battery' s SOC estimation method%基于4维Map图的镍氢电池SOC估计方法

    Institute of Scientific and Technical Information of China (English)

    胡志坤; 王文祥; 林勇; 孙岩

    2012-01-01

    A battery' s state of charge (SOC) estimation method based on the four-dimensional Map was proposed to solve the problems of current SOC estimation methods which accuracy was too low or too sensitive to data or model parameters that can not be used in practice. A Map which reflects the relation a-mong the Nickel-Metal Hydride(Ni-MH) battery's temperature, current, voltage and its SOC was established with a large number of experimental data. The approach was inspired by the finding that the adjacent charge-discharge character curves with different current, and temperature conditions are in parallel with each other within the work-interval (20% ≤Ysoc≤80% ) of the battery. Therefore, the four-dimen sional Map model of SOC, with current, temperature and voltage as its parameters, was established by interpolating in the current and temperature directions through moving the curves which is based on the relation between SOC and terminal voltage. Some experiments were conducted to verify the Map model and the result indicate that the SOC estimation error of the model is less than 3%. The SOC estimation method based on the four-dimensional Map can meet the requirements of industrial production both in accuracy and ensy realization.%针对现有镍氢电池荷电状态(SOC)估计方法因精确度太低或者对数据、模型参数要求太高而难以实用的问题,提出一种基于4维Map图的电池SOC估计方法.通过大量实验数据,建立镍氢电池SOC与温度、电流和端电压之间的基本Map图,发现在其工作区间20%≤YSOC≤80%内,不同电流、温度条件下的相邻充放电特性曲线基本相互平行.以SOC与端电压之间的关系为基础,分别在电流和温度方向上采用曲线平移的方式插值得到SOC与电流、温度、电压之间的4维Map图模型.利用试验数据进行SOC估计试验,试验结果表明,利用4维Map图模型的SOC估计误差在3%以内,基于4维Map图的

  6. Mechanisms of cardiac pain.

    Science.gov (United States)

    Foreman, Robert D; Garrett, Kennon M; Blair, Robert W

    2015-04-01

    Angina pectoris is cardiac pain that typically is manifested as referred pain to the chest and upper left arm. Atypical pain to describe localization of the perception, generally experienced more by women, is referred to the back, neck, and/or jaw. This article summarizes the neurophysiological and pharmacological mechanisms for referred cardiac pain. Spinal cardiac afferent fibers mediate typical anginal pain via pathways from the spinal cord to the thalamus and ultimately cerebral cortex. Spinal neurotransmission involves substance P, glutamate, and transient receptor potential vanilloid-1 (TRPV1) receptors; release of neurokinins such as nuclear factor kappa b (NF-kb) in the spinal cord can modulate neurotransmission. Vagal cardiac afferent fibers likely mediate atypical anginal pain and contribute to cardiac ischemia without accompanying pain via relays through the nucleus of the solitary tract and the C1-C2 spinal segments. The psychological state of an individual can modulate cardiac nociception via pathways involving the amygdala. Descending pathways originating from nucleus raphe magnus and the pons also can modulate cardiac nociception. Sensory input from other visceral organs can mimic cardiac pain due to convergence of this input with cardiac input onto spinothalamic tract neurons. Reduction of converging nociceptive input from the gallbladder and gastrointestinal tract can diminish cardiac pain. Much work remains to be performed to discern the interactions among complex neural pathways that ultimately produce or do not produce the sensations associated with cardiac pain.

  7. 基于四维顾客价值的航空客运市场细分模型研究%Research on Market Segmentation Model of Air Passenger Transport Based on the Four-dimensional Customer Value

    Institute of Scientific and Technical Information of China (English)

    王悦; 曾小舟; 陈桥

    2015-01-01

    旨在根据航空运输行业特点以及以顾客价值为导向的市场销售特征,摒弃传统细分变量以及细分方法的使用,从Kotler四维顾客总价值角度构建航空客运市场细分模型;继而形成施测问卷,获取样本数据;将因子分析与经典的K-Means相结合,最终获得四类差距明显的子市场.研究结果表明,依据构建的市场细分模型能够获得较为满意的市场细分结果,验证了模型的有效性,可作为航空客运主体细分市场的依据之一.%According to the industry features of the civil aviation and its customer-oriented marketing characteris-tics, this paper established an efficient model of market segmentation (MS) based on Kotler's four-dimensional to-tal customer value (TCV), casting away the traditional segmentation variables and methods. On the basis of the es-tablished model, a questionnaire was formed and the correspondent data were collected. Combining the factor anal-ysis and the classic K-Means algorithm, this paper finally obtained four segmented markets with significant differ-ences. Results demonstrated that according to the constructed model, a desirable segmentation result was ac-quired, which might verify the validity of the model and thus could be the reference for MS of the operational sub-jects in civil aviation.

  8. The Effect of the Number of Simulations on the Exponents Obtained by Finite-Size Scaling Relations of the Order Parameter and the Magnetic Susceptibility for the Four-Dimensional Ising Model on the Creutz Cellular Automaton

    Science.gov (United States)

    Merdan, Z.; Güzelsoy, E.

    2012-05-01

    The four-dimensional Ising model is simulated on the Creutz cellular automaton using finite-size lattices with linear dimension 4≤ L≤8. The exponents in the finite-size scaling relations for the order parameter and the magnetic susceptibility at the finite-lattice critical temperature are computed to be β=0.49(7), β=0.49(5), β=0.50(1) and γ=1.04(4), γ=1.03(4), γ=1.02(4) for 7, 14, and 21 independent simulations, respectively. As the number of independent simulations increases, the obtained results are consistent with the renormalization group predictions of β=0.5 and γ=1. The values for the critical temperature of the infinite lattice T c (∞)=6.6788(65), T c (∞)=6.6798(69), T c (∞)=6.6802(70) are obtained from the straight-line fit of the magnetic susceptibility maxima using 4≤ L≤8 for 7, 14, and 21 independent simulations, respectively. As the number of independent simulations increases, the obtained results are in very good agreement with the series expansion results of T c (∞)=6.6817(15), T c (∞)=6.6802(2), the dynamic Monte Carlo result of T c (∞)=6.6803(1), the cluster Monte Carlo result of T c (∞)=6.680(1) and the Monte Carlo using Metropolis and Wolff-cluster algorithm result of T c (∞)=6.6802632±5×10-5.

  9. Cardiac tumours in children

    Directory of Open Access Journals (Sweden)

    Parsons Jonathan M

    2007-03-01

    Full Text Available Abstract Cardiac tumours are benign or malignant neoplasms arising primarily in the inner lining, muscle layer, or the surrounding pericardium of the heart. They can be primary or metastatic. Primary cardiac tumours are rare in paediatric practice with a prevalence of 0.0017 to 0.28 in autopsy series. In contrast, the incidence of cardiac tumours during foetal life has been reported to be approximately 0.14%. The vast majority of primary cardiac tumours in children are benign, whilst approximately 10% are malignant. Secondary malignant tumours are 10–20 times more prevalent than primary malignant tumours. Rhabdomyoma is the most common cardiac tumour during foetal life and childhood. It accounts for more than 60% of all primary cardiac tumours. The frequency and type of cardiac tumours in adults differ from those in children with 75% being benign and 25% being malignant. Myxomas are the most common primary tumours in adults constituting 40% of benign tumours. Sarcomas make up 75% of malignant cardiac masses. Echocardiography, Computing Tomography (CT and Magnetic Resonance Imaging (MRI of the heart are the main non-invasive diagnostic tools. Cardiac catheterisation is seldom necessary. Tumour biopsy with histological assessment remains the gold standard for confirmation of the diagnosis. Surgical resection of primary cardiac tumours should be considered to relieve symptoms and mechanical obstruction to blood flow. The outcome of surgical resection in symptomatic, non-myxomatous benign cardiac tumours is favourable. Patients with primary cardiac malignancies may benefit from palliative surgery but this approach should not be recommended for patients with metastatic cardiac tumours. Surgery, chemotherapy and radiotherapy may prolong survival. The prognosis for malignant primary cardiac tumours is generally extremely poor.

  10. Stimulating endogenous cardiac regeneration

    Directory of Open Access Journals (Sweden)

    Amanda eFinan

    2015-09-01

    Full Text Available The healthy adult heart has a low turnover of cardiac myocytes. The renewal capacity, however, is augmented after cardiac injury. Participants in cardiac regeneration include cardiac myocytes themselves, cardiac progenitor cells, and peripheral stem cells, particularly from the bone marrow compartment. Cardiac progenitor cells and bone marrow stem cells are augmented after cardiac injury, migrate to the myocardium, and support regeneration. Depletion studies of these populations have demonstrated their necessary role in cardiac repair. However, the potential of these cells to completely regenerate the heart is limited. Efforts are now being focused on ways to augment these natural pathways to improve cardiac healing, primarily after ischemic injury but in other cardiac pathologies as well. Cell and gene therapy or pharmacological interventions are proposed mechanisms. Cell therapy has demonstrated modest results and has passed into clinical trials. However, the beneficial effects of cell therapy have primarily been their ability to produce paracrine effects on the cardiac tissue and recruit endogenous stem cell populations as opposed to direct cardiac regeneration. Gene therapy efforts have focused on prolonging or reactivating natural signaling pathways. Positive results have been demonstrated to activate the endogenous stem cell populations and are currently being tested in clinical trials. A potential new avenue may be to refine pharmacological treatments that are currently in place in the clinic. Evidence is mounting that drugs such as statins or beta blockers may alter endogenous stem cell activity. Understanding the effects of these drugs on stem cell repair while keeping in mind their primary function may strike a balance in myocardial healing. To maximize endogenous cardiac regeneration,a combination of these approaches couldameliorate the overall repair process to incorporate the participation ofmultiple cell players.

  11. Detecting depressive and anxiety disorders in distressed patients in primary care; comparative diagnostic accuracy of the Four-Dimensional Symptom Questionnaire (4DSQ and the Hospital Anxiety and Depression Scale (HADS

    Directory of Open Access Journals (Sweden)

    Verhaak Peter FM

    2009-08-01

    Full Text Available Abstract Background Depressive and anxiety disorders often go unrecognized in distressed primary care patients, despite the overtly psychosocial nature of their demand for help. This is especially problematic in more severe disorders needing specific treatment (e.g. antidepressant pharmacotherapy or specialized cognitive behavioural therapy. The use of a screening tool to detect (more severe depressive and anxiety disorders may be useful not to overlook such disorders. We examined the accuracy with which the Four-Dimensional Symptom Questionnaire (4DSQ and the Hospital Anxiety and Depression Scale (HADS are able to detect (more severe depressive and anxiety disorders in distressed patients, and which cut-off points should be used. Methods Seventy general practitioners (GPs included 295 patients on sick leave due to psychological problems. They excluded patients with recognized depressive or anxiety disorders. Patients completed the 4DSQ and HADS. Standardized diagnoses of DSM-IV defined depressive and anxiety disorders were established with the Composite International Diagnostic Interview (CIDI. Receiver Operating Characteristic (ROC analyses were performed to obtain sensitivity and specificity values for a range of scores, and area under the curve (AUC values as a measure of diagnostic accuracy. Results With respect to the detection of any depressive or anxiety disorder (180 patients, 61%, the 4DSQ and HADS scales yielded comparable results with AUC values between 0.745 and 0.815. Also with respect to the detection of moderate or severe depressive disorder, the 4DSQ and HADS depression scales performed comparably (AUC 0.780 and 0.739, p 0.165. With respect to the detection of panic disorder, agoraphobia and social phobia, the 4DSQ anxiety scale performed significantly better than the HADS anxiety scale (AUC 0.852 versus 0.757, p 0.001. The recommended cut-off points of both HADS scales appeared to be too low while those of the 4DSQ anxiety

  12. Cardiac sodium channelopathies.

    Science.gov (United States)

    Amin, Ahmad S; Asghari-Roodsari, Alaleh; Tan, Hanno L

    2010-07-01

    Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (INa) during phase 0 of the cardiac action potential. The importance of INa for normal cardiac electrical activity is reflected by the high incidence of arrhythmias in cardiac sodium channelopathies, i.e., arrhythmogenic diseases in patients with mutations in SCN5A, the gene responsible for the pore-forming ion-conducting alpha-subunit, or in genes that encode the ancillary beta-subunits or regulatory proteins of the cardiac sodium channel. While clinical and genetic studies have laid the foundation for our understanding of cardiac sodium channelopathies by establishing links between arrhythmogenic diseases and mutations in genes that encode various subunits of the cardiac sodium channel, biophysical studies (particularly in heterologous expression systems and transgenic mouse models) have provided insights into the mechanisms by which INa dysfunction causes disease in such channelopathies. It is now recognized that mutations that increase INa delay cardiac repolarization, prolong action potential duration, and cause long QT syndrome, while mutations that reduce INa decrease cardiac excitability, reduce electrical conduction velocity, and induce Brugada syndrome, progressive cardiac conduction disease, sick sinus syndrome, or combinations thereof. Recently, mutation-induced INa dysfunction was also linked to dilated cardiomyopathy, atrial fibrillation, and sudden infant death syndrome. This review describes the structure and function of the cardiac sodium channel and its various subunits, summarizes major cardiac sodium channelopathies and the current knowledge concerning their genetic background and underlying molecular mechanisms, and discusses recent advances in the discovery of mutation-specific therapies in the management of these channelopathies.

  13. Marketing cardiac CT programs.

    Science.gov (United States)

    Scott, Jason

    2010-01-01

    There are two components of cardiac CT discussed in this article: coronary artery calcium scoring (CACS) and coronary computed tomography angiography (CCTA).The distinctive advantages of each CT examination are outlined. In order to ensure a successful cardiac CT program, it is imperative that imaging facilities market their cardiac CT practices effectively in order to gain a competitive advantage in this valuable market share. If patients receive quality care by competent individuals, they are more likely to recommend the facility's cardiac CT program. Satisfied patients will also be more willing to come back for any further testing.

  14. Cardiac event monitors

    Science.gov (United States)

    ... ECG) - ambulatory; Continuous electrocardiograms (EKGs); Holter monitors; Transtelephonic event monitors ... attached. You can carry or wear a cardiac event monitor up to 30 days. You carry the ...

  15. Cardiac stem cell niches

    Directory of Open Access Journals (Sweden)

    Annarosa Leri

    2014-11-01

    Full Text Available The critical role that stem cell niches have in cardiac homeostasis and myocardial repair following injury is the focus of this review. Cardiac niches represent specialized microdomains where the quiescent and activated state of resident stem cells is regulated. Alterations in niche function with aging and cardiac diseases result in abnormal sites of cardiomyogenesis and inadequate myocyte formation. The relevance of Notch1 signaling, gap-junction formation, HIF-1α and metabolic state in the regulation of stem cell growth and differentiation within the cardiac niches are discussed.

  16. Analysis of the Effect of the Application of Four-dimensional Color Doppler Ultrasound in Prenatal Screening of Fetal Malformation%产前胎儿畸形筛查中四维彩超的应用效果分析

    Institute of Scientific and Technical Information of China (English)

    纪亚梅; 王文俊

    2016-01-01

    目的:探讨产前胎儿畸形筛查中四维彩超的应用效果。方法方便选取2013年1月—2016年2月在该院进行产前筛查的2200例中晚期孕妇作为研究对象,分别对其进行二维彩超及四维彩超检查,根据胎儿出生后情况或引产结果对二维彩超及四维彩超的检出率进行比较。结果二维彩超对胎儿畸形的检出率为76.92%(40/52),四维彩超对胎儿畸形的检出率为96.15%(50/52),四维彩超对胎儿畸形的检出率明显高于二维彩超(P﹤0.01)。结论与二维彩超相比,四维彩超在胎儿畸形检出方面具有明显优势,值得临床推广应用。%Objective To investigate the application effect of four dimensional color Doppler ultrasound in prenatal screen-ing of fetal malformation. Methods 2 200 cases of advanced pregnant women from January 2013 to February 2016 in our hospital were selected as research subjects. Two dimensional color Doppler ultrasound and four-dimensional color Doppler ultrasound examination were carried out on them. According to the results of the fetus after birth or induction of labor, the detection rate of two-dimensional color Doppler ultrasound and four-dimensional color Doppler ultrasound were compared. Results The detection rate of two-dimensional color Doppler ultrasound for fetal malformation was 76.92%(40/52), while that of four-dimensional color Doppler ultrasound was 96.15%(50/52). Thus the detection rate of four-dimensional color Doppler ultrasound was obviously higher than that of two-dimensional color Doppler ultrasound(P﹤0.01). Conclusion Com-pared with two-dimensional ultrasound, four-dimensional color Doppler ultrasound in the detection of fetal abnormalities has obvious advantages, which is worth clinical application.

  17. [Advances in cardiac pacing].

    Science.gov (United States)

    de Carranza, María-José Sancho-Tello; Fidalgo-Andrés, María Luisa; Ferrer, José Martínez; Mateas, Francisco Ruiz

    2012-01-01

    This article contains a review of the current status of remote monitoring and follow-up involving cardiac pacing devices and of the latest developments in cardiac resynchronization therapy. In addition, the most important articles published in the last year are discussed.

  18. Mathematical cardiac electrophysiology

    CERN Document Server

    Colli Franzone, Piero; Scacchi, Simone

    2014-01-01

    This book covers the main mathematical and numerical models in computational electrocardiology, ranging from microscopic membrane models of cardiac ionic channels to macroscopic bidomain, monodomain, eikonal models and cardiac source representations. These advanced multiscale and nonlinear models describe the cardiac bioelectrical activity from the cell level to the body surface and are employed in both the direct and inverse problems of electrocardiology. The book also covers advanced numerical techniques needed to efficiently carry out large-scale cardiac simulations, including time and space discretizations, decoupling and operator splitting techniques, parallel finite element solvers. These techniques are employed in 3D cardiac simulations illustrating the excitation mechanisms, the anisotropic effects on excitation and repolarization wavefronts, the morphology of electrograms in normal and pathological tissue and some reentry phenomena. The overall aim of the book is to present rigorously the mathematica...

  19. Biomaterials for cardiac regeneration

    CERN Document Server

    Ruel, Marc

    2015-01-01

    This book offers readers a comprehensive biomaterials-based approach to achieving clinically successful, functionally integrated vasculogenesis and myogenesis in the heart. Coverage is multidisciplinary, including the role of extracellular matrices in cardiac development, whole-heart tissue engineering, imaging the mechanisms and effects of biomaterial-based cardiac regeneration, and autologous bioengineered heart valves. Bringing current knowledge together into a single volume, this book provides a compendium to students and new researchers in the field and constitutes a platform to allow for future developments and collaborative approaches in biomaterials-based regenerative medicine, even beyond cardiac applications. This book also: Provides a valuable overview of the engineering of biomaterials for cardiac regeneration, including coverage of combined biomaterials and stem cells, as well as extracellular matrices Presents readers with multidisciplinary coverage of biomaterials for cardiac repair, including ...

  20. Sudden cardiac death

    Directory of Open Access Journals (Sweden)

    Neeraj Parakh

    2015-01-01

    Full Text Available Sudden cardiac death is one of the most common cause of mortality worldwide. Despite significant advances in the medical science, there is little improvement in the sudden cardiac death related mortality. Coronary artery disease is the most common etiology behind sudden cardiac death, in the above 40 years population. Even in the apparently healthy population, there is a small percentage of patients dying from sudden cardiac death. Given the large denominator, this small percentage contributes to the largest burden of sudden cardiac death. Identification of this at risk group among the apparently healthy individual is a great challenge for the medical fraternity. This article looks into the causes and methods of preventing SCD and at some of the Indian data. Details of Brugada syndrome, Long QT syndrome, Genetics of SCD are discussed. Recent guidelines on many of these causes are summarised.

  1. Four-dimensional computed tomography based assessment and analysis of lung tumor motion during free-breathing respiration%基于四维CT影像肺内肿瘤运动度的测量与分析

    Institute of Scientific and Technical Information of China (English)

    王彦; 包勇; 张黎; 樊卫; 邓小武; 陈明

    2010-01-01

    目的 以四维CT(4DCT)影像量化肺内肿瘤因呼吸导致的运动,分析其影响因素,寻找运动度大的肿瘤特征.方法 在平静呼吸状态下接受4DCT扫描的肺内肿瘤患者43例,肺内可测量病灶44个.由同一位医生在4DCT各时相数据集卜勾画肿瘤GTV,分别测量GTV中心点在上下、左右、前后三维方向上的运动幅度.对与运动度可能相关的临床变量和解剖学因素进行统计学分析.以任意方向运动幅度>5 mm作为分界点,分析此类肿瘤特征.结果 肺内肿瘤运动度与T分期、GTV体积、肺内所处上下位置、与固定组织(如胸壁、纵隔、脊柱)粘连程度相关.10例患者肺内肿瘤的运动幅度>5 mm,均位于胸腔下部及后部,上下方向运动度最大,最大值为14.4 mm.95%肺内肿瘤的运动幅度在上下方向<11.8 mm,前后方向<4.6 mm,左右方向<2.7 mm.结论 呼吸导致的肺内肿瘤运动度受肿瘤位置、体积、T分期及粘连程度等因素影响.下叶肺内孤立肿瘤的运动度最大,主要发生在上下方向,上叶后段肿瘤的运动度次之.%Objective To quantify the amplitudes of lung tumor motion during free-breathing using four dimensional computed tomography (4DCT), and seek the characteristics of tumors with large motion. Methods Respiratory-induced tumor motion was analyzed for 44 tumors from 43 patients. All patients un-derwent 4DCT during free-breathing before treatment. Gross tumor volumes (GTV) on ten respiratory phases were contoured by the same doctor. The eentroids of GTVs were autoplaeed with treatment software (ADAC Pinnacle 7.4f), then the amplitudes of tumor motion were assessed. The various clinical and anatomic fac-tors associated with GTV motion were analyzed. The characteristics of tumors with motion greater than 5 mm in any direction were explored. Results The tumor motion was found to be associated with T stage, GTV size, the superior-inferior (SI) tumor location in the lung, and the attachment

  2. Cardiac tumors: echo assessment.

    Science.gov (United States)

    Mankad, Rekha; Herrmann, Joerg

    2016-12-01

    Cardiac tumors are exceedingly rare (0.001-0.03% in most autopsy series). They can be present anywhere within the heart and can be attached to any surface or be embedded in the myocardium or pericardial space. Signs and symptoms are nonspecific and highly variable related to the localization, size and composition of the cardiac mass. Echocardiography, typically performed for another indication, may be the first imaging modality alerting the clinician to the presence of a cardiac mass. Although echocardiography cannot give the histopathology, certain imaging features and adjunctive tools such as contrast imaging may aid in the differential diagnosis as do the adjunctive clinical data and the following principles: (1) thrombus or vegetations are the most likely etiology, (2) cardiac tumors are mostly secondary and (3) primary cardiac tumors are mostly benign. Although the finding of a cardiac mass on echocardiography may generate confusion, a stepwise approach may serve well practically. Herein, we will review such an approach and the role of echocardiography in the assessment of cardiac masses.

  3. Cardiac tumors: echo assessment

    Directory of Open Access Journals (Sweden)

    Rekha Mankad MD

    2016-12-01

    Full Text Available Cardiac tumors are exceedingly rare (0.001–0.03% in most autopsy series. They can be present anywhere within the heart and can be attached to any surface or be embedded in the myocardium or pericardial space. Signs and symptoms are nonspecific and highly variable related to the localization, size and composition of the cardiac mass. Echocardiography, typically performed for another indication, may be the first imaging modality alerting the clinician to the presence of a cardiac mass. Although echocardiography cannot give the histopathology, certain imaging features and adjunctive tools such as contrast imaging may aid in the differential diagnosis as do the adjunctive clinical data and the following principles: (1 thrombus or vegetations are the most likely etiology, (2 cardiac tumors are mostly secondary and (3 primary cardiac tumors are mostly benign. Although the finding of a cardiac mass on echocardiography may generate confusion, a stepwise approach may serve well practically. Herein, we will review such an approach and the role of echocardiography in the assessment of cardiac masses.

  4. Cardiac Tamponade Revisited

    Science.gov (United States)

    Ariyarajah, Vignendra; Spodick, David H.

    2007-01-01

    Cardiac tamponade is a life-threatening clinical syndrome that requires timely diagnosis. Herein, we present an instructive case of a patient who had cardiac tamponade. The condition went undiagnosed and resulted in the patient's death because almost all of the pathognomonic clinical findings of tamponade were unrecognized or not manifest. To better prepare health care professionals for similar challenges, we discuss the symptoms and clinical signs typical of cardiac tamponade, review the medical literature, and highlight current investigative methods that enable quick, efficient diagnosis and treatment. PMID:17948086

  5. Molecular Basis of Cardiac Myxomas

    Directory of Open Access Journals (Sweden)

    Pooja Singhal

    2014-01-01

    Full Text Available Cardiac tumors are rare, and of these, primary cardiac tumors are even rarer. Metastatic cardiac tumors are about 100 times more common than the primary tumors. About 90% of primary cardiac tumors are benign, and of these the most common are cardiac myxomas. Approximately 12% of primary cardiac tumors are completely asymptomatic while others present with one or more signs and symptoms of the classical triad of hemodynamic changes due to intracardiac obstruction, embolism and nonspecific constitutional symptoms. Echocardiography is highly sensitive and specific in detecting cardiac tumors. Other helpful investigations are chest X-rays, magnetic resonance imaging and computerized tomography scan. Surgical excision is the treatment of choice for primary cardiac tumors and is usually associated with a good prognosis. This review article will focus on the general features of benign cardiac tumors with an emphasis on cardiac myxomas and their molecular basis.

  6. Cardiac Tumors; Tumeurs cardiaques

    Energy Technology Data Exchange (ETDEWEB)

    Laissy, J.P.; Fernandez, P. [Centre Hospitalier Universitaire Bichat Claude Bernard, Service d' Imagerie, 76 - Rouen (France); Mousseaux, E. [Hopital Europeen Georges Pompidou (HEGP), Service de Radiologie Cardio Vasculaire et Interventionnelle, 75 - Paris (France); Dacher, J.N. [Centre Hospitalier Universitaire Charles Nicolle, 75 - Rouen (France); Crochet, D. [Centre Hospitalier Universitaire, Hopital Laennec, Centre Hemodynamique, Radiologie Thoracique et Vasculaire, 44 - Nantes (France)

    2004-04-01

    Metastases are the most frequent tumors of the heart even though they seldom are recognized. Most primary cardiac tumors are benign. The main role of imaging is to differentiate a cardiac tumor from thrombus and rare pseudo-tumors: tuberculoma, hydatid cyst. Echocardiography is the fist line imaging technique to detect cardiac tumors, but CT and MRl arc useful for further characterization and differential diagnosis. Myxoma of the left atrium is the most frequent benign cardiac tumor. It usually is pedunculated and sometimes calcified. Sarcoma is the most frequent primary malignant tumor and usually presents as a sessile infiltrative tumor. Lymphoma and metastases are usually recognized by the presence of known tumor elsewhere of by characteristic direct contiguous involvement. Diagnosing primary and secondary pericardial tumors often is difficult. Imaging is valuable for diagnosis, characterization, pre-surgical evaluation and follow-up. (author)

  7. Socially differentiated cardiac rehabilitation

    DEFF Research Database (Denmark)

    Meillier, Lucette Kirsten; Nielsen, Kirsten Melgaard; Larsen, Finn Breinholt;

    2012-01-01

    to a standard rehabilitation programme (SRP). If patients were identified as socially vulnerable, they were offered an extended version of the rehabilitation programme (ERP). Excluded patients were offered home visits by a cardiac nurse. Concordance principles were used in the individualised programme elements......%. Patients were equally distributed to the SRP and the ERP. No inequality was found in attendance and adherence among referred patients. Conclusions: It seems possible to overcome unequal referral, attendance, and adherence in cardiac rehabilitation by organisation of systematic screening and social......Aim: The comprehensive cardiac rehabilitation (CR) programme after myocardial infarction (MI) improves quality of life and results in reduced cardiac mortality and recurrence of MI. Hospitals worldwide face problems with low participation rates in rehabilitation programmes. Inequality...

  8. Transvenous Temporary Cardiac Pacing

    National Research Council Canada - National Science Library

    Emmanouil Poulidakis; Antonis S Manolis

    2014-01-01

      Transvenous temporary cardiac pacing is a rather old but still contemporary life-saving technique, with a unique value in the treatment of critically ill patients suffering from rhythm disturbances...

  9. Cardiac arrest - cardiopulmonary resuscitation

    Institute of Scientific and Technical Information of China (English)

    Basri Lenjani; Besnik Elshani; Nehat Baftiu; Kelmend Pallaska; Kadir Hyseni; Njazi Gashi; Nexhbedin Karemani; Ilaz Bunjaku; Taxhidin Zaimi; Arianit Jakupi

    2014-01-01

    Objective:To investigate application of cardiopulmonary resuscitation(CPR) measures within the golden minutes inEurope.Methods:The material was taken from theUniversityClinical Center ofKosovo -EmergencyCentre inPristina, during the two(2) year period(2010-2011).The collected date belong to the patients with cardiac arrest have been recorded in the patients' log book protocol at the emergency clinic.Results:During the2010 to2011 in the emergency center of theCUCK inPristina have been treated a total of269 patients with cardiac arrest, of whom159 or59.1% have been treated in2010, and110 patients or40.9% in2011.Of the269 patients treated in the emergency centre,93 or34.6% have exited lethally in the emergency centre, and176 or 65.4% have been transferred to other clinics.In the total number of patients with cardiac arrest, males have dominated with186 cases, or69.1%.The average age of patients included in the survey was56.7 year oldSD±16.0 years.Of the269 patients with cardiac arrest, defibrillation has been applied for93 or34.6% of patients.In the outpatient settings defibrillation has been applied for3 or3.2% of patients.Patients were defibrillated with application of one to four shocks. Of27 cases with who have survived cardiac arrest, none of them have suffered cardiac arrest at home,3 or11.1% of them have suffered cardiac arrest on the street, and24 or88.9% of them have suffered cardiac arrest in the hospital.5 out of27 patients survived have ended with neurological impairment.Cardiac arrest cases were present during all days of the week, but frequently most reported cases have been onMonday with32.0% of cases, and onFriday with24.5% of cases. Conclusions:All survivors from cardiac arrest have received appropriate medical assistance within10 min from attack, which implies that if cardiac arrest occurs near an institution health care(with an opportunity to provide the emergent health care) the rate of survival is higher.

  10. Cardiac imaging in adults

    Energy Technology Data Exchange (ETDEWEB)

    Jaffe, C.C.

    1987-01-01

    This book approaches adult cardiac disease from the correlative imaging perspective. It includes chest X-rays and angiographs, 2-dimensional echocardiograms with explanatory diagrams for clarity, plus details on digital radiology, nuclear medicine techniques, CT and MRI. It also covers the normal heart, valvular heart disease, myocardial disease, pericardial disease, bacterial endocarditis, aortic aneurysm, cardiac tumors, and congenital heart disease of the adult. It points out those aspects where one imaging technique has significant superiority.

  11. Autonomic cardiac innervation

    OpenAIRE

    Hasan, Wohaib

    2013-01-01

    Autonomic cardiac neurons have a common origin in the neural crest but undergo distinct developmental differentiation as they mature toward their adult phenotype. Progenitor cells respond to repulsive cues during migration, followed by differentiation cues from paracrine sources that promote neurochemistry and differentiation. When autonomic axons start to innervate cardiac tissue, neurotrophic factors from vascular tissue are essential for maintenance of neurons before they reach their targe...

  12. Port Access Cardiac Surgery.

    Science.gov (United States)

    Viganó, Mario; Minzioni, Gaetano; Spreafico, Patrizio; Rinaldi, Mauro; Pasquino, Stefano; Ceriana, Piero; Locatelli, Alessandro

    2000-10-01

    The port-access technique for cardiac surgery was recently developed at Stanford University in California as a less invasive method to perform some cardiac operations. The port-access system has been described in detail elsewhere. It is based on femoral arterial and venous access for cardiopulmonary bypass (CPB) and on the adoption of a specially designed triple-lumen catheter described originally by Peters, and subsequently modified and developed in the definitive configuration called the endoaortic clamp.

  13. Awareness in cardiac anesthesia.

    LENUS (Irish Health Repository)

    Serfontein, Leon

    2010-02-01

    Cardiac surgery represents a sub-group of patients at significantly increased risk of intraoperative awareness. Relatively few recent publications have targeted the topic of awareness in this group. The aim of this review is to identify areas of awareness research that may equally be extrapolated to cardiac anesthesia in the attempt to increase understanding of the nature and significance of this scenario and how to reduce it.

  14. Post cardiac injury syndrome

    DEFF Research Database (Denmark)

    Nielsen, S L; Nielsen, F E

    1991-01-01

    The post-pericardiotomy syndrome is a symptom complex which is similar in many respects to the post-myocardial infarction syndrome and these are summarized under the diagnosis of the Post Cardiac Injury Syndrome (PCIS). This condition, which is observed most frequently after open heart surgery, i...... on the coronary vessels, with cardiac tamponade and chronic pericardial exudate. In the lighter cases, PCIS may be treated with NSAID and, in the more severe cases, with systemic glucocorticoid which has a prompt effect....

  15. Infected cardiac hydatid cyst

    OpenAIRE

    Ceviz, M; Becit, N; Kocak, H.

    2001-01-01

    A 24 year old woman presented with chest pain and palpitation. The presence of a semisolid mass—an echinococcal cyst or tumour—in the left ventricular apex was diagnosed by echocardiography, computed tomography, and magnetic resonance imaging. The infected cyst was seen at surgery. The cyst was removed successfully by using cardiopulmonary bypass with cross clamp.


Keywords: cardiac hydatid cyst; infected cardiac hydatid cyst

  16. Cardiac applications of optogenetics.

    Science.gov (United States)

    Ambrosi, Christina M; Klimas, Aleksandra; Yu, Jinzhu; Entcheva, Emilia

    2014-08-01

    In complex multicellular systems, such as the brain or the heart, the ability to selectively perturb and observe the response of individual components at the cellular level and with millisecond resolution in time, is essential for mechanistic understanding of function. Optogenetics uses genetic encoding of light sensitivity (by the expression of microbial opsins) to provide such capabilities for manipulation, recording, and control by light with cell specificity and high spatiotemporal resolution. As an optical approach, it is inherently scalable for remote and parallel interrogation of biological function at the tissue level; with implantable miniaturized devices, the technique is uniquely suitable for in vivo tracking of function, as illustrated by numerous applications in the brain. Its expansion into the cardiac area has been slow. Here, using examples from published research and original data, we focus on optogenetics applications to cardiac electrophysiology, specifically dealing with the ability to manipulate membrane voltage by light with implications for cardiac pacing, cardioversion, cell communication, and arrhythmia research, in general. We discuss gene and cell delivery methods of inscribing light sensitivity in cardiac tissue, functionality of the light-sensitive ion channels within different types of cardiac cells, utility in probing electrical coupling between different cell types, approaches and design solutions to all-optical electrophysiology by the combination of optogenetic sensors and actuators, and specific challenges in moving towards in vivo cardiac optogenetics.

  17. Live dynamic OCT imaging of cardiac structure and function in mouse embryos with 43 Hz direct volumetric data acquisition

    Science.gov (United States)

    Wang, Shang; Singh, Manmohan; Lopez, Andrew L.; Wu, Chen; Raghunathan, Raksha; Schill, Alexander; Li, Jiasong; Larin, Kirill V.; Larina, Irina V.

    2016-03-01

    Efficient phenotyping of cardiac dynamics in live mouse embryos has significant implications on understanding of early mammalian heart development and congenital cardiac defects. Recent studies established optical coherence tomography (OCT) as a powerful tool for live embryonic heart imaging in various animal models. However, current four-dimensional (4D) OCT imaging of the beating embryonic heart largely relies on gated data acquisition or postacquisition synchronization, which brings errors when cardiac cycles lack perfect periodicity and is time consuming and computationally expensive. Here, we report direct 4D OCT imaging of the structure and function of cardiac dynamics in live mouse embryos achieved by employing a Fourier domain mode-locking swept laser source that enables ~1.5 MHz A-line rate. Through utilizing both forward and backward scans of a resonant mirror, we obtained a ~6.4 kHz frame rate, which allows for a direct volumetric data acquisition speed of ~43 Hz, around 20 times of the early-stage mouse embryonic heart rate. Our experiments were performed on mouse embryos at embryonic day 9.5. Time-resolved 3D cardiodynamics clearly shows the heart structure in motion. We present analysis of cardiac wall movement and its velocity from the primitive atrium and ventricle. Our results suggest that the combination of ultrahigh-speed OCT imaging with live embryo culture could be a useful embryonic heart phenotyping approach for mouse mutants modeling human congenital heart diseases.

  18. A registration based approach for 4D cardiac micro-CT using combined prospective and retrospective gating

    Science.gov (United States)

    Badea, Cristian T.; Schreibmann, Eduard; Fox, Tim

    2008-01-01

    Recent advances in murine cardiac studies with three-dimensional cone beam micro-computed tomography (CT) have used either prospective or retrospective gating technique. While prospective gating ensures the best image quality and the highest resolution, it involves longer sampling times and higher radiation dose. Sampling is faster and the radiation dose can be reduced with retrospective gating but the image quality is affected by the limited number of projections with an irregular angular distribution which complicate the reconstruction process, causing significant streaking artifacts. This work involves both prospective and retrospective gating in sampling. Deformable registration is used between a high quality image set acquired with prospective gating with the multiple data sets during the cardiac cycle obtained using retrospective gating. Tests were conducted on a four-dimensional (4D) cardiac mouse phantom and after optimization, the method was applied to in vivo cardiac micro-CT data. Results indicate that, by using our method, the sampling time can be reduced by a factor of 2.5 and the radiation dose can be reduced 35% compared to the prospective sampling while the image quality can be maintained. In conclusion, we proposed a novel solution to 4D cine cardiac micro-CT based on a combined prospective with retrospective gating in sampling and deformable registration post reconstruction that mixed the advantages of both strategies. PMID:18491508

  19. Dynamic real-time 4D cardiac MDCT image display using GPU-accelerated volume rendering.

    Science.gov (United States)

    Zhang, Qi; Eagleson, Roy; Peters, Terry M

    2009-09-01

    Intraoperative cardiac monitoring, accurate preoperative diagnosis, and surgical planning are important components of minimally-invasive cardiac therapy. Retrospective, electrocardiographically (ECG) gated, multidetector computed tomographical (MDCT), four-dimensional (3D + time), real-time, cardiac image visualization is an important tool for the surgeon in such procedure, particularly if the dynamic volumetric image can be registered to, and fused with the actual patient anatomy. The addition of stereoscopic imaging provides a more intuitive environment by adding binocular vision and depth cues to structures within the beating heart. In this paper, we describe the design and implementation of a comprehensive stereoscopic 4D cardiac image visualization and manipulation platform, based on the opacity density radiation model, which exploits the power of modern graphics processing units (GPUs) in the rendering pipeline. In addition, we present a new algorithm to synchronize the phases of the dynamic heart to clinical ECG signals, and to calculate and compensate for latencies in the visualization pipeline. A dynamic multiresolution display is implemented to enable the interactive selection and emphasis of volume of interest (VOI) within the entire contextual cardiac volume and to enhance performance, and a novel color and opacity adjustment algorithm is designed to increase the uniformity of the rendered multiresolution image of heart. Our system provides a visualization environment superior to noninteractive software-based implementations, but with a rendering speed that is comparable to traditional, but inferior quality, volume rendering approaches based on texture mapping. This retrospective ECG-gated dynamic cardiac display system can provide real-time feedback regarding the suspected pathology, function, and structural defects, as well as anatomical information such as chamber volume and morphology.

  20. [Psychosomatic aspects of cardiac arrhythmias].

    Science.gov (United States)

    Siepmann, Martin; Kirch, Wilhelm

    2010-07-01

    Emotional stress facilitates the occurrence of cardiac arrhythmias including sudden cardiac death. The prevalence of anxiety and depression is increased in cardiac patients as compared to the normal population. The risk of cardiovascular mortality is enhanced in patients suffering from depression. Comorbid anxiety disorders worsen the course of cardiac arrhythmias. Disturbance of neurocardiac regulation with predominance of the sympathetic tone is hypothesized to be causative for this. The emotional reaction to cardiac arrhythmias is differing to a large extent between individuals. Emotional stress may result from coping with treatment of cardiac arrhythmias. Emotional stress and cardiac arrhythmias may influence each other in the sense of a vicious circle. Somatoform cardiac arrhythmias are predominantly of psychogenic origin. Instrumental measures and frequent contacts between physicians and patients may facilitate disease chronification. The present review is dealing with the multifaceted relationships between cardiac arrhythmias and emotional stress. The underlying mechanisms and corresponding treatment modalities are discussed.

  1. Cardiac radiology: centenary review.

    Science.gov (United States)

    de Roos, Albert; Higgins, Charles B

    2014-11-01

    During the past century, cardiac imaging technologies have revolutionized the diagnosis and treatment of acquired and congenital heart disease. Many important contributions to the field of cardiac imaging were initially reported in Radiology. The field developed from the early stages of cardiac imaging, including the use of coronary x-ray angiography and roentgen kymography, to nowadays the widely used echocardiographic, nuclear medicine, cardiac computed tomographic (CT), and magnetic resonance (MR) applications. It is surprising how many of these techniques were not recognized for their potential during their early inception. Some techniques were described in the literature but required many years to enter the clinical arena and presently continue to expand in terms of clinical application. The application of various CT and MR contrast agents for the diagnosis of myocardial ischemia is a case in point, as the utility of contrast agents continues to expand the noninvasive characterization of myocardium. The history of cardiac imaging has included a continuous process of advances in our understanding of the anatomy and physiology of the cardiovascular system, along with advances in imaging technology that continue to the present day.

  2. Comprehensive cardiac rehabilitation

    DEFF Research Database (Denmark)

    Kruse, Marie; Hochstrasser, Stefan; Zwisler, Ann-Dorthe O;

    2006-01-01

    OBJECTIVES: The costs of comprehensive cardiac rehabilitation are established and compared to the corresponding costs of usual care. The effect on health-related quality of life is analyzed. METHODS: An unprecedented and very detailed cost assessment was carried out, as no guidelines existed...... for the situation at hand. Due to challenging circumstances, the cost assessment turned out to be ex-post and top-down. RESULTS: Cost per treatment sequence is estimated to be approximately euro 976, whereas the incremental cost (compared with usual care) is approximately euro 682. The cost estimate is uncertain...... and may be as high as euro 1.877. CONCLUSIONS: Comprehensive cardiac rehabilitation is more costly than usual care, and the higher costs are not outweighed by a quality of life gain. Comprehensive cardiac rehabilitation is, therefore, not cost-effective....

  3. Pediatric cardiac postoperative care

    Directory of Open Access Journals (Sweden)

    Auler Jr. José Otávio Costa

    2002-01-01

    Full Text Available The Heart Institute of the University of São Paulo, Medical School is a referral center for the treatment of congenital heart diseases of neonates and infants. In the recent years, the excellent surgical results obtained in our institution may be in part due to modern anesthetic care and to postoperative care based on well-structured protocols. The purpose of this article is to review unique aspects of neonate cardiovascular physiology, the impact of extracorporeal circulation on postoperative evolution, and the prescription for pharmacological support of acute cardiac dysfunction based on our cardiac unit protocols. The main causes of low cardiac output after surgical correction of heart congenital disease are reviewed, and methods of treatment and support are proposed as derived from the relevant literature and our protocols.

  4. Toothache of cardiac origin.

    Science.gov (United States)

    Kreiner, M; Okeson, J P

    1999-01-01

    Pain referred to the orofacial structures can sometimes be a diagnostic challenge for the clinician. In some instances, a patient may complain of tooth pain that is completely unrelated to any dental source. This poses a diagnostic and therapeutic problem for the dentist. Cardiac pain most commonly radiates to the left arm, shoulder, neck, and face. In rare instances, angina pectoris may present as dental pain. When this occurs, an improper diagnosis frequently leads to unnecessary dental treatment or, more significantly, a delay of proper treatment. This delay may result in the patient experiencing an acute myocardial infarction. It is the dentist's responsibility to establish a proper diagnosis so that the treatment will be directed toward the source of pain and not to the site of pain. This article reviews the literature concerning referred pain of cardiac origin and presents a case report of toothache of cardiac origin.

  5. The cardiac anxiety questionnaire: cross-validation among cardiac inpatients

    NARCIS (Netherlands)

    Beek, M.H. van; Oude Voshaar, R.C.; Deelen, F.M. van; Balkom, A.J. van; Pop, G.A.; Speckens, A.E.

    2012-01-01

    OBJECTIVE: General anxiety symptoms are common in patients with cardiac disease and considered to have an adverse effect on cardiac prognosis. The role of specific cardiac anxiety, however, is still unknown. The aim of this study is to examine the factor structure, reliability, and validity of the D

  6. THE CARDIAC ANXIETY QUESTIONNAIRE : CROSS-VALIDATION AMONG CARDIAC INPATIENTS

    NARCIS (Netherlands)

    van Beek, M. H. C. T.; Voshaar, R. C. Oude; van Deelen, F. M.; van Balkom, A. J. L. M.; Pop, G.; Speckens, A. E. M.

    2012-01-01

    Objective: General anxiety symptoms are common in patients with cardiac disease and considered to have an adverse effect on cardiac prognosis. The role of specific cardiac anxiety, however, is still unknown. The aim of this study is to examine the factor structure, reliability, and validity of the D

  7. Cardiac output measurement

    Directory of Open Access Journals (Sweden)

    Andreja Möller Petrun

    2014-02-01

    Full Text Available In recent years, developments in the measuring of cardiac output and other haemodynamic variables are focused on the so-called minimally invasive methods. The aim of these methods is to simplify the management of high-risk and haemodynamically unstable patients. Due to the need of invasive approach and the possibility of serious complications the use of pulmonary artery catheter has decreased. This article describes the methods for measuring cardiac output, which are based on volume measurement (Fick method, indicator dilution method, pulse wave analysis, Doppler effect, and electrical bioimpedance.

  8. Perioperative management of cardiac disease.

    Science.gov (United States)

    Aresti, N A; Malik, A A; Ihsan, K M; Aftab, S M E; Khan, W S

    2014-01-01

    Pre-existing cardiac disease contributes significantly to morbidity and mortality amongst patients undergoing non cardiac surgery. Patients with pre-existing cardiac disease or with risk factors for it, have as much as a 3.9% risk of suffering a major perioperative cardiac event (Lee et al 1999, Devereaux 2005). Furthermore, the incidence of perioperative myocardial infarction (MI) is increased 10 to 50 fold in patients with previous coronary events (Jassal 2008).

  9. Data analysis in cardiac arrhythmias.

    Science.gov (United States)

    Rodrigo, Miguel; Pedrón-Torecilla, Jorge; Hernández, Ismael; Liberos, Alejandro; Climent, Andreu M; Guillem, María S

    2015-01-01

    Cardiac arrhythmias are an increasingly present in developed countries and represent a major health and economic burden. The occurrence of cardiac arrhythmias is closely linked to the electrical function of the heart. Consequently, the analysis of the electrical signal generated by the heart tissue, either recorded invasively or noninvasively, provides valuable information for the study of cardiac arrhythmias. In this chapter, novel cardiac signal analysis techniques that allow the study and diagnosis of cardiac arrhythmias are described, with emphasis on cardiac mapping which allows for spatiotemporal analysis of cardiac signals.Cardiac mapping can serve as a diagnostic tool by recording cardiac signals either in close contact to the heart tissue or noninvasively from the body surface, and allows the identification of cardiac sites responsible of the development or maintenance of arrhythmias. Cardiac mapping can also be used for research in cardiac arrhythmias in order to understand their mechanisms. For this purpose, both synthetic signals generated by computer simulations and animal experimental models allow for more controlled physiological conditions and complete access to the organ.

  10. Biosynthesis of cardiac natriuretic peptides

    DEFF Research Database (Denmark)

    Goetze, Jens Peter

    2010-01-01

    Cardiac-derived peptide hormones were identified more than 25 years ago. An astonishing amount of clinical studies have established cardiac natriuretic peptides and their molecular precursors as useful markers of heart disease. In contrast to the clinical applications, the biogenesis of cardiac...

  11. Cardiac troponins and high-sensitivity cardiac troponin assays.

    Science.gov (United States)

    Conrad, Michael J; Jarolim, Petr

    2014-03-01

    Measurement of circulating cardiac troponins I and T has become integral to the diagnosis of myocardial infarction. This article discusses the structure and function of the troponin complex and the release of cardiac troponin molecules from the injured cardiomyocyte into the circulation. An overview of current cardiac troponin assays and their classification according to sensitivity is presented. The diagnostic criteria, role, and usefulness of cardiac troponin for myocardial infarction are discussed. In addition, several examples are given of the usefulness of high-sensitivity cardiac troponin assays for short-term and long-term prediction of adverse events.

  12. Hepato-cardiac disorders

    Institute of Scientific and Technical Information of China (English)

    Yasser; Mahrous; Fouad; Reem; Yehia

    2014-01-01

    Understanding the mutual relationship between the liver and the heart is important for both hepatologists and cardiologists. Hepato-cardiac diseases can be classified into heart diseases affecting the liver, liver diseases affecting the heart, and conditions affecting the heart and the liver at the same time. Differential diagnoses of liver injury are extremely important in a cardiologist’s clinical practice calling for collaboration between cardiologists and hepatologists due to the many other diseases that can affect the liver and mimic haemodynamic injury. Acute and chronic heart failure may lead to acute ischemic hepatitis or chronic congestive hepatopathy. Treatment in these cases should be directed to the primary heart disease. In patients with advanced liver disease, cirrhotic cardiomyopathy may develop including hemodynamic changes, diastolic and systolic dysfunctions, reduced cardiac performance and electrophysiological abnormalities. Cardiac evaluation is important for patients with liver diseases especially before and after liver transplantation. Liver transplantation may lead to the improvement of all cardiac changes and the reversal of cirrhotic cardiomyopathy. There are systemic diseases that may affect both the liver and the heart concomitantly including congenital, metabolic and inflammatory diseases as well as alcoholism. This review highlights these hepatocardiac diseases

  13. The cardiac malpositions.

    Science.gov (United States)

    Perloff, Joseph K

    2011-11-01

    Dextrocardia was known in the 17th century and was 1 of the first congenital malformations of the heart to be recognized. Fifty years elapsed before Matthew Baillie published his account of complete transposition in a human of the thoracic and abdominal viscera to the opposite side from what is natural. In 1858, Thomas Peacock stated that "the heart may be congenitally misplaced in various ways, occupying either an unusual position within the thorax, or being situated external to that cavity." In 1915, Maude Abbott described ectopia cordis, and Richard Paltauf's remarkable illustrations distinguished the various types of dextrocardia. In 1928, the first useful classification of the cardiac malpositions was proposed, and in 1966, Elliott et al's radiologic classification set the stage for clinical recognition. The first section of this review deals with the 3 basic cardiac malpositions in the presence of bilateral asymmetry. The second section deals with cardiac malpositions in the presence of bilateral left-sidedness or right-sidedness. Previous publications on cardiac malpositions are replete with an arcane vocabulary that confounds rather than clarifies. Even if the terms themselves are understood, inherent complexity weighs against clarity. This review was designed as a guided tour of an unfamiliar subject.

  14. Sudden cardiac death

    DEFF Research Database (Denmark)

    Hougen, H P; Valenzuela, Antonio Jesus Sanchez; Lachica, E

    1992-01-01

    The study deals with the comparison of morphological, histochemical and biochemical methods applied to the detection of myocardial infarction in 150 medico-legal autopsies performed at the Institute of Forensic Pathology in Copenhagen. The study also included an NBT (formazan) test of cardiac cro...

  15. Cardiac Risk Assessment

    Science.gov (United States)

    ... Risk Assessment Related tests: Lipid Profile , VLDL Cholesterol , hs-CRP , Lp(a) Overview | Common Questions | Related Pages What ... cardiac risk include: High-sensitivity C-reactive protein (hs-CRP) : Studies have shown that measuring CRP with a ...

  16. Cardiac Catheterization (For Teens)

    Science.gov (United States)

    ... once a day. Avoid baths, hot tubs, and swimming for 1 week after the catheterization. Don't use any creams, lotions, or ointments on the site. The doctor will tell you when it's safe to go back to your normal activities after a cardiac catheterization. ...

  17. Cardiac rehabilitation in the Navy.

    Science.gov (United States)

    Bruzek-Kohler, C M; Love, V; Hendrickson, R; Branford, M; Gates, A; Telvick, C

    1994-10-01

    Cardiac rehabilitation has been effective in the management and recovery of the post-myocardial infarction population for almost 40 years. During that time, the fundamental components of rehabilitation have changed to reflect a growing complexity and number of cardiac patients. Great Lakes Naval Hospital has instituted a structured outpatient cardiac rehabilitation program. It is based on the needs of a large cardiac population with modifiable risk factors identified through quality improvement studies. Future implications and research in the area of cardiac rehabilitation include measurements of self-efficacy, long-term risk factor modification, cost effectiveness, gender-related differences, or morbidity and mortality.

  18. Research on Four-Dimensional Attitude Motion Planning of Agile and Autonomous Spacecraft with Time%考虑时间因素的敏捷自主航天器四维姿态运动规划方法研究

    Institute of Scientific and Technical Information of China (English)

    王平; 郭继峰; 陈诚; 崔乃刚

    2011-01-01

    为解决敏捷自主航天器在轨灵巧、精确姿态运动问题,针对复杂空间环境与其自身运动特点,提出了基于改进的快速搜索随机树的四维姿态运动规划方法.仿真算例检验了该规划方法的有效性,结果表明它不仪满足敏捷自主航天器在一定约束条件下指定时间到达指定地点的四维运动要求,而且对四维姿态运动离线与在线规划两种模式也具备较强的适应性.%An improved four-dimensional attitude motion planning algorithm based on improved Rapidly-searching Random Trees for agile and autonomous spacecraft under complicated space environment is studied. Thia planning algorithm satisfies the requirement for agile and autonomous spacecraft attitude maneuvering with complex constraints. The results show that this four-dimensional motion planning algorithm can be used to obtain the feasible attitude motion trajectories and adapt to the two modes of on and off line planning.

  19. Cardiac involvement in myotonic dystrophy

    DEFF Research Database (Denmark)

    Lund, Marie; Diaz, Lars Jorge; Ranthe, Mattis Flyvholm

    2014-01-01

    disorders, arrhythmias, and device implantation). In the DM cohort, SIR for any cardiac disease was 3.42 [95% confidence interval (CI) 3.01-3.86]; for a cardiac disease belonging to the selected subgroups 6.91 (95% CI: 5.93-8.01) and for other cardiac disease 2.59 (95% CI: 2.03-3.25). For a cardiac disease......AIMS: To quantify the association between myotonic dystrophy (DM) and cardiac disease in a nationwide cohort. METHODS AND RESULTS: We identified a nationwide cohort of 1146 DM patients (period 1977-2011) using the National Patient Registry (NPR) and a subcohort of 485 patients who had undergone...... genetic testing for DM1. Information on incident cardiac diseases was obtained from the NPR. We estimated standardized incidence ratios (SIRs) of cardiac disease compared with the background population, overall and according to selected diagnostic subgroups (cardiomyopathy, heart failure, conduction...

  20. Cardiac fusion and complex congenital cardiac defects in thoracopagus twins: diagnostic value of cardiac CT

    Energy Technology Data Exchange (ETDEWEB)

    Goo, Hyun Woo [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology and Research Institute of Radiology, Seoul (Korea, Republic of); Park, Jeong-Jun [University of Ulsan College of Medicine, Asan Medical Center, Department of Pediatric Cardiac Surgery, Seoul (Korea, Republic of); Kim, Ellen Ai-Rhan [University of Ulsan College of Medicine, Asan Medical Center, Division of Neonatology, Department of Pediatrics, Seoul (Korea, Republic of); Won, Hye-Sung [University of Ulsan College of Medicine, Asan Medical Center, Department of Obstetrics and Gynecology, Seoul (Korea, Republic of)

    2014-09-15

    Most thoracopagus twins present with cardiac fusion and associated congenital cardiac defects, and assessment of this anatomy is of critical importance in determining patient care and outcome. Cardiac CT with electrocardiographic triggering provides an accurate and quick morphological assessment of both intracardiac and extracardiac structures in newborns, making it the best imaging modality to assess thoracopagus twins during the neonatal period. In this case report, we highlight the diagnostic value of cardiac CT in thoracopagus twins with an interatrial channel and complex congenital cardiac defects. (orig.)

  1. Sudden Cardiac Death

    Directory of Open Access Journals (Sweden)

    Yipsy María Gutiérrez Báez

    2015-09-01

    Full Text Available Since the second half of the twentieth century, dying suddenly due to heart-related problems has become the main health issue in all countries where infectious diseases are not prevalent. Sudden death from cardiac causes is an important global health problem. Major databases were searched for the leading causes of sudden cardiac death. It has been demonstrated that there is a group of hereditary diseases with structural alterations or without apparent organic cause that explains many cases of sudden death in young people, whether related or not to physical exertion. Certain population groups are at higher risk for this disease. They are relatively easy to identify and can be the target of primary prevention measures.

  2. Cardiac nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    Gerson, M.C.

    1987-01-01

    The book begins with a review of the radionuclide methods available for evaluating cardiac perfusion and function. The authors discuss planar and tomographic thallium myocardial imaging, first-pass and equilibrium radionuclide angiography, and imaging with infarct-avid tracers. Several common but more specialized procedures are then reviewed: nonogemetric measurement of left ventricular volume, phase (Fourier) analysis, stroke volume ratio, right ventricular function, and diastolic function. A separate chapter is devoted to drug interventions and in particular the use of radionuclide ventriculography to monitor doxorubicin toxicity and therapy of congestive heart failure. The subsequent chapters provide a comprehensive guide to test selection, accuracy, and results in acute myocardial infarction, in postmyocardial infarction, in chronic coronary artery disease, before and after medical or surgical revascularization, in valvular heart disease, in cardiomyopathies, and in cardiac trauma.

  3. Cardiac arrest in children

    Directory of Open Access Journals (Sweden)

    Tress Erika

    2010-01-01

    Full Text Available Major advances in the field of pediatric cardiac arrest (CA were made during the last decade, starting with the publication of pediatric Utstein guidelines, the 2005 recommendations by the International Liaison Committee on Resuscitation, and culminating in multicenter collaborations. The epidemiology and pathophysiology of in-hospital and out-of-hospital CA are now well described. Four phases of CA are described and the term "post-cardiac arrest syndrome" has been proposed, along with treatment goals for each of its four phases: immediate post-arrest, early post-arrest, intermediate and recovery phase. Hypothermia is recommended to be considered as a therapy for post-CA syndrome in comatose patients after CA, and large multicenter prospective studies are underway. We reviewed landmark articles related to pediatric CA published during the last decade. We present the current knowledge of epidemiology, pathophysiology and treatment of CA relevant to pre-hospital and acute care health practitioners.

  4. Cardiac arrhythmias in pregnancy.

    Science.gov (United States)

    Knotts, Robert J; Garan, Hasan

    2014-08-01

    As more women with repaired congenital heart disease survive to their reproductive years and many other women are delaying pregnancy until later in life, a rising concern is the risk of cardiac arrhythmias during pregnancy. Naturally occurring cardiovascular changes during pregnancy increase the likelihood that a recurrence of a previously experienced cardiac arrhythmia or a de novo arrhythmia will occur. Arrhythmias should be thoroughly investigated to determine if there is a reversible etiology, and risks/benefits of treatment options should be fully explored. We discuss the approach to working up and treating various arrhythmias during pregnancy with attention to fetal and maternal risks as well as treatment of fetal arrhythmias. Acute management in stable patients includes close monitoring and intravenous pharmacologic therapy, while DC cardioversion should be used to terminate arrhythmias in hemodynamically unstable patients. Long-term management may require continued oral antiarrhythmic therapy, with particular attention to fetal safety, to prevent complications associated with arrhythmias.

  5. The Role of Cardiac Side Population Cells in Cardiac Regeneration

    Science.gov (United States)

    Yellamilli, Amritha; van Berlo, Jop H.

    2016-01-01

    The heart has a limited ability to regenerate. It is important to identify therapeutic strategies that enhance cardiac regeneration in order to replace cardiomyocytes lost during the progression of heart failure. Cardiac progenitor cells are interesting targets for new regenerative therapies because they are self-renewing, multipotent cells located in the heart. Cardiac side population cells (cSPCs), the first cardiac progenitor cells identified in the adult heart, have the ability to differentiate into cardiomyocytes, endothelial cells, smooth muscle cells, and fibroblasts. They become activated in response to cardiac injury and transplantation of cSPCs into the injured heart improves cardiac function. In this review, we will discuss the current literature on the progenitor cell properties and therapeutic potential of cSPCs. This body of work demonstrates the great promise cSPCs hold as targets for new regenerative strategies. PMID:27679798

  6. Cardiac hybrid imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gaemperli, Oliver [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); University Hospital Zurich, Nuclear Cardiology, Cardiovascular Center, Zurich (Switzerland); Kaufmann, Philipp A. [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); Alkadhi, Hatem [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland)

    2014-05-15

    Hybrid cardiac single photon emission computed tomography (SPECT)/CT imaging allows combined assessment of anatomical and functional aspects of cardiac disease. In coronary artery disease (CAD), hybrid SPECT/CT imaging allows detection of coronary artery stenosis and myocardial perfusion abnormalities. The clinical value of hybrid imaging has been documented in several subsets of patients. In selected groups of patients, hybrid imaging improves the diagnostic accuracy to detect CAD compared to the single imaging techniques. Additionally, this approach facilitates functional interrogation of coronary stenoses and guidance with regard to revascularization procedures. Moreover, the anatomical information obtained from CT coronary angiography or coronary artery calcium scores (CACS) adds prognostic information over perfusion data from SPECT. The use of cardiac hybrid imaging has been favoured by the dissemination of dedicated hybrid systems and the release of dedicated image fusion software, which allow simple patient throughput for hybrid SPECT/CT studies. Further technological improvements such as more efficient detector technology to allow for low-radiation protocols, ultra-fast image acquisition and improved low-noise image reconstruction algorithms will be instrumental to further promote hybrid SPECT/CT in research and clinical practice. (orig.)

  7. Cardiac tissue engineering

    Directory of Open Access Journals (Sweden)

    MILICA RADISIC

    2005-03-01

    Full Text Available We hypothesized that clinically sized (1-5 mm thick,compact cardiac constructs containing physiologically high density of viable cells (~108 cells/cm3 can be engineered in vitro by using biomimetic culture systems capable of providing oxygen transport and electrical stimulation, designed to mimic those in native heart. This hypothesis was tested by culturing rat heart cells on polymer scaffolds, either with perfusion of culture medium (physiologic interstitial velocity, supplementation of perfluorocarbons, or with electrical stimulation (continuous application of biphasic pulses, 2 ms, 5 V, 1 Hz. Tissue constructs cultured without perfusion or electrical stimulation served as controls. Medium perfusion and addition of perfluorocarbons resulted in compact, thick constructs containing physiologic density of viable, electromechanically coupled cells, in contrast to control constructs which had only a ~100 mm thick peripheral region with functionally connected cells. Electrical stimulation of cultured constructs resulted in markedly improved contractile properties, increased amounts of cardiac proteins, and remarkably well developed ultrastructure (similar to that of native heart as compared to non-stimulated controls. We discuss here the state of the art of cardiac tissue engineering, in light of the biomimetic approach that reproduces in vitro some of the conditions present during normal tissue development.

  8. Molecular nuclear cardiac imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong Soo; Paeng, Jin Chul [College of Medicine, Seoul National Univ., Seoul (Korea, Republic of)

    2004-04-01

    Molecular nuclear cardiac imaging has included Tc-99m Annexin imaging to visualize myocardial apoptosis, but is now usually associated with gene therapy and cell-based therapy. Cardiac gene therapy was not successful so far but cardiac reporter gene imaging was made possible using HSV-TK (herpes simplex virus thymidine kinase) and F-18 FHBG (fluoro-hydroxymethylbutyl guanine) or I-124 FIAU (fluoro-deoxyiodo-arabino-furanosyluracil). Gene delivery was performed by needle injection with or without catheter guidance. TK expression did not last longer than 2 weeks in myocardium. Cell-based therapy of ischemic heart or failing heart looks promising, but biodistribution and differentiation of transplanted cells are not known. Reporter genes can be transfected to the stem/progenitor cells and cells containing these genes can be transplanted to the recipients using catheter-based purging or injection. Repeated imaging should be available and if promoter are varied to let express reporter transgenes, cellular (trans)differentiation can be studied. NIS (sodium iodide symporter) or D2R receptor genes are promising in this aspect.

  9. Cardiac surgery 2015 reviewed.

    Science.gov (United States)

    Doenst, Torsten; Strüning, Constanze; Moschovas, Alexandros; Gonzalez-Lopez, David; Essa, Yasin; Kirov, Hristo; Diab, Mahmoud; Faerber, Gloria

    2016-10-01

    For the year 2015, almost 19,000 published references can be found in PubMed when entering the search term "cardiac surgery". The last year has been again characterized by lively discussions in the fields where classic cardiac surgery and modern interventional techniques overlap. Lacking evidence in the field of coronary revascularization with either percutaneous coronary intervention or bypass surgery has been added. As in the years before, CABG remains the gold standard for the revascularization of complex stable triple-vessel disease. Plenty of new information has been presented comparing the conventional to transcatheter aortic valve implantation (TAVI) demonstrating similar short- and mid-term outcomes at high and low risk, but even a survival advantage with transfemoral TAVI at intermediate risk. In addition, there were many relevant and interesting other contributions from the purely operative arena. This review article will summarize the most pertinent publications in the fields of coronary revascularization, surgical treatment of valve disease, heart failure (i.e., transplantation and ventricular assist devices), and aortic surgery. While the article does not have the expectation of being complete and cannot be free of individual interpretation, it provides a condensed summary that is intended to give the reader "solid ground" for up-to-date decision-making in cardiac surgery.

  10. Cardiac assessment prior to non-cardiac surgery.

    Science.gov (United States)

    Mooney, J F; Hillis, G S; Lee, V W; Halliwell, R; Vicaretti, M; Moncrieff, C; Chow, C K

    2016-08-01

    Increasingly, patients undergoing non-cardiac surgery are older and have more comorbidities yet preoperative cardiac assessment appears haphazard and unsystematic. We hypothesised that patients at high cardiac risk were not receiving adequate cardiac assessment, and patients with low-cardiac risk were being over-investigated. To compare in a representative sample of patients undergoing non-cardiac surgery the use of cardiac investigations in patients at high and low preoperative cardiac risk. We examined cardiac assessment patterns prior to elective non-cardiac surgery in a representative sample of patients. Cardiac risk was calculated using the Revised Cardiac Risk Index. Of 671 patients, 589 (88%) were low risk and 82 (12%) were high risk. We found that nearly 14% of low-risk and 45% of high-risk patients had investigations for coronary ischaemia prior to surgery. Vascular surgery had the highest rate of investigation (38%) and thoracic patients the lowest rate (14%). Whilst 78% of high-risk patients had coronary disease, only 46% were on beta-blockers, 49% on aspirin and 77% on statins. For current smokers (17.3% of cohort, n = 98), 60% were advised to quit pre-op. Practice patterns varied across surgical sub-types with low-risk patients tending to be over-investigated and high-risk patients under-investigated. A more systemised approach to this large group of patients could improve clinical outcomes, and more judicious use of investigations could lower healthcare costs and increase efficiency in managing this cohort. © 2016 Royal Australasian College of Physicians.

  11. Indeterminacy of Spatiotemporal Cardiac Alternans

    CERN Document Server

    Zhao, Xiaopeng

    2007-01-01

    Cardiac alternans, a beat-to-beat alternation in action potential duration (at the cellular level) or in ECG morphology (at the whole heart level), is a marker of ventricular fibrillation, a fatal heart rhythm that kills hundreds of thousands of people in the US each year. Investigating cardiac alternans may lead to a better understanding of the mechanisms of cardiac arrhythmias and eventually better algorithms for the prediction and prevention of such dreadful diseases. In paced cardiac tissue, alternans develops under increasingly shorter pacing period. Existing experimental and theoretical studies adopt the assumption that alternans in homogeneous cardiac tissue is exclusively determined by the pacing period. In contrast, we find that, when calcium-driven alternans develops in cardiac fibers, it may take different spatiotemporal patterns depending on the pacing history. Because there coexist multiple alternans solutions for a given pacing period, the alternans pattern on a fiber becomes unpredictable. Usin...

  12. Fully automated intrinsic respiratory and cardiac gating for small animal CT

    Energy Technology Data Exchange (ETDEWEB)

    Kuntz, J; Baeuerle, T; Semmler, W; Bartling, S H [Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg (Germany); Dinkel, J [Department of Radiology, German Cancer Research Center, Heidelberg (Germany); Zwick, S [Department of Diagnostic Radiology, Medical Physics, Freiburg University (Germany); Grasruck, M [Siemens Healthcare, Forchheim (Germany); Kiessling, F [Chair of Experimental Molecular Imaging, RWTH-Aachen University, Medical Faculty, Aachen (Germany); Gupta, R [Department of Radiology, Massachusetts General Hospital, Boston, MA (United States)], E-mail: j.kuntz@dkfz.de

    2010-04-07

    A fully automated, intrinsic gating algorithm for small animal cone-beam CT is described and evaluated. A parameter representing the organ motion, derived from the raw projection images, is used for both cardiac and respiratory gating. The proposed algorithm makes it possible to reconstruct motion-corrected still images as well as to generate four-dimensional (4D) datasets representing the cardiac and pulmonary anatomy of free-breathing animals without the use of electrocardiogram (ECG) or respiratory sensors. Variation analysis of projections from several rotations is used to place a region of interest (ROI) on the diaphragm. The ROI is cranially extended to include the heart. The centre of mass (COM) variation within this ROI, the filtered frequency response and the local maxima are used to derive a binary motion-gating parameter for phase-sensitive gated reconstruction. This algorithm was implemented on a flat-panel-based cone-beam CT scanner and evaluated using a moving phantom and animal scans (seven rats and eight mice). Volumes were determined using a semiautomatic segmentation. In all cases robust gating signals could be obtained. The maximum volume error in phantom studies was less than 6%. By utilizing extrinsic gating via externally placed cardiac and respiratory sensors, the functional parameters (e.g. cardiac ejection fraction) and image quality were equivalent to this current gold standard. This algorithm obviates the necessity of both gating hardware and user interaction. The simplicity of the proposed algorithm enables adoption in a wide range of small animal cone-beam CT scanners.

  13. Case Report: Penetrating Cardiac Injury

    Directory of Open Access Journals (Sweden)

    Adem Grbolar

    2013-10-01

    Full Text Available Summary: Penetrating cardiac injurys caused by gunshots and penetrating tools have high mortality rates. The way of injury, how the cardiac area is effected and the presence of cardiac tamponadecauses mortality in different rates. However the better treatment quality of hospitals, increasingoperative techniques, and internel care unit quality has not been change during the years. Searching the literature, we want to present a 42 years old male patient whowas injured by knife and had a 1 cm skin wound on chest with cardiac tamponade. After sternotomy a 7 cm laseration was observed in heart. Cardioraphy was performed.

  14. Cardiac surgery for Kartagener syndrome.

    Science.gov (United States)

    Tkebuchava, T; von Segesser, L K; Niederhäuser, U; Bauersfeld, U; Turina, M

    1997-01-01

    Two patients (one girl, one boy) with Kartagener syndrome (situs inversus, bronchiectasis, sinusitis), despite pulmonary problems and associated congenital cardiac anomalies, were operated on at the ages of 4 years and 7 years, respectively. They had had previous palliative treatment at the age of 3 months and 1.3 years, respectively. Both postoperative periods after total correction were without significant complications. Long-term follow-up was available for 9 and 19 years, respectively, with no manifestations of heart insufficiency. Both patients are physically active, and neither requires cardiac medication. Patients with Kartagener syndrome and associated congenital cardiac anomalies can successfully undergo multiple cardiac operations with good long-term outcome.

  15. Continuous real-time photoacoustic demodulation via field programmable gate array for dynamic imaging of zebrafish cardiac cycle.

    Science.gov (United States)

    Mattison, Scott P; Shelton, Ryan L; Maxson, Ryan T; Applegate, Brian E

    2013-01-01

    A four dimensional data set of the cardiac cycle of a zebrafish embryo was acquired using postacquisition synchronization of real time photoacoustic b-scans. Utilizing an off-axis photoacoustic microscopy (OA-PAM) setup, we have expanded upon our previous work with OA-PAM to develop a system that can sustain 100 kHz line rates while demodulating the bipolar photoacoustic signal in real-time. Real-time processing was accomplished by quadrature demodulation on a Field Programmable Gate Array (FPGA) in line with the signal digitizer. Simulated data acquisition verified the system is capable of real-time processing up to a line rate of 1 MHz. Galvanometer-scanning of the excitation laser inside the focus of the ultrasonic transducer enables real data acquisition of a 200 by 200 by 200 pixel, volumetric data set across a 2 millimeter field of view at a rate of 2.5 Hz.

  16. CSI cardiac prevent 2015

    Directory of Open Access Journals (Sweden)

    S Ramakrishnan

    2015-01-01

    Full Text Available The CSI Cardiac Prevent 2015 was held at Hotel Taj Palace, New Delhi, on September 25-27, 2015. The major challenge was to create interest among cardiologists and physicians on preventive cardiology, a neglected area. The theme of the conference was "Innovations in Heart Disease Prevention.′′ This conference included "CSI at WHF Roadmap Workshop, Inauguration Ceremony, scientific program, plenary sessions, Nursing/Dietician track, Industry Exhibition, Social Events," Great India blood pressure Survey, and CSI Smart Heart App. A total of 848 delegates/faculties attended this conference against a total of 1140 people registered for the meeting.

  17. Proposal of a four-dimensional model of social response.

    Science.gov (United States)

    Nail, P R; MacDonald, G; Levy, D A

    2000-05-01

    Descriptive models of social response attempt to identify the conceptual dimensions necessary to define and distinguish various types of influence. Building on previous approaches, the authors propose a new response model and demonstrate that a minimum of 4 dimensions is necessary to adequately provide for such influence phenomena as conformity, minority influence, compliance, contagion, independence, and anticonformity in a single model. In addition, the proposed model suggests 5 potential types of response that have not been previously identified. These new types suggest directions for future research and theoretical development. Selected empirical evidence is reviewed in support of the validity and integrative power of the proposed model.

  18. Four-dimensional information visualization and analysis system

    Energy Technology Data Exchange (ETDEWEB)

    Rex, B.

    1994-09-01

    4DIVAS was conceived for two purposes. The first purpose was to fill the void between the current generation of GIS and high-end, image-only visualization systems. The gap existing between these two systems can be summarized as the limitation of relational database oriented GIS to deal with time and the poor connection in visualization systems to databases of any kind. The second purpose was to permit spatio-temporal modeling and query, functionalities currently underdeveloped in the commercial arena. At the Hanford Site, there are many potential applications for such a system, especially in the monitoring and modeling of potential constituent plumes in the subsurface hydrology over time, among others. In its current form, 4DIVAS exists as a proof-of-concept functional prototype and is therefore more of a technology than a product at this time.

  19. Four-dimensional imaging of moisture dynamics during landslide reactivation

    Science.gov (United States)

    Uhlemann, Sebastian; Chambers, Jonathan; Wilkinson, Paul; Maurer, Hansruedi; Merritt, Andrew; Meldrum, Philip; Kuras, Oliver; Gunn, David; Smith, Alister; Dijkstra, Tom

    2017-01-01

    Landslides pose significant risks to communities and infrastructure, and mitigating these risks relies on understanding landslide causes and triggering processes. It has been shown that geophysical surveys can significantly contribute to the characterization of unstable slopes. However, hydrological processes can be temporally and spatially heterogeneous, requiring their related properties to be monitored over time. Geoelectrical monitoring can provide temporal and volumetric distributions of electrical resistivity, which are directly related to moisture content. To date, studies demonstrating this capability have been restricted to 2-D sections, which are insufficient to capture the full degree of spatial heterogeneity. This study is the first to employ 4-D (i.e., 3-D time lapse) resistivity imaging on an active landslide, providing long-term data (3 years) highlighting the evolution of moisture content prior to landslide reactivation and showing its decline post reactivation. Crucially, the time-lapse inversion methodology employed here incorporates movements of the electrodes on the unstable surface. Although seasonal characteristics dominate the shallow moisture dynamics during the first 2 years with surficial drying in summer and wetting in winter, in the months preceding reactivation, moisture content increased by more than 45% throughout the slope. This is in agreement with independent data showing a significant rise in piezometric heads and shallow soil moisture contents as a result of prolonged and intense rainfall. Based on these results, remediation measures could be designed and early-warning systems implemented. Thus, resistivity monitoring that can allow for moving electrodes provides a new means for the effective mitigation of landslide risk.

  20. Holographic superconductor in a deformed four-dimensional STU model

    CERN Document Server

    Pourhassan, B

    2016-01-01

    In this paper, we consider deformed STU model in four dimension including both electric and magnetic charges. Using AdS/CFT we study holographic superconductor and obtain transport properties. We find that presence of magnetic charge is necessary to have maximum electrical conductivity. Also we show that thermal conductivity increases with magnetic charge.

  1. Four-dimensional hilbert curves for R-trees

    DEFF Research Database (Denmark)

    Haverkort, Herman; Walderveen, Freek van

    2011-01-01

    Two-dimensional R-trees are a class of spatial index structures in which objects are arranged to enable fast window queries: report all objects that intersect a given query window. One of the most successful methods of arranging the objects in the index structure is based on sorting the objects a...

  2. Four-dimensional space groups for pedestrians: composite structures.

    Science.gov (United States)

    Sun, Junliang; Lee, Stephen; Lin, Jianhua

    2007-10-01

    Higher-dimensional crystals have been studied for the last thirty years. However, most practicing chemists, materials scientists, and crystallographers continue to eschew the use of higher-dimensional crystallography in their work. Yet it has become increasingly clear in recent years that the number of higher-dimensional systems continues to grow from hundreds to as many as a thousand different compounds. Part of the problem has to do with the somewhat opaque language that has developed over the past decades to describe higher-dimensional systems. This language, while well-suited to the specialist, is too sophisticated for the neophyte wishing to enter the field, and as such can be an impediment. This Focus Review hopes to address this issue. The goal of this article is to show the regular chemist or materials scientist that knowledge of regular 3D crystallography is all that is really necessary to understand 4D crystal systems. To this end, we have couched higher-dimensional composite structures in the language of ordinary 3D crystals. In particular, we developed the principle of complementarity, which allows one to identify correctly 4D space groups solely from examination of the two 3D components that make up a typical 4D composite structure.

  3. Regularization independence of finite states in four dimensional quantized gravity

    CERN Document Server

    Ita, Eyo

    2009-01-01

    This is one of a series of works designed to address a major criticism concerning the mathematical rigor of the generalized Kodama states. The present paper analyzes the criterion for finiteness due to cancellation of the ultraviolet divergences stemming from the quantum Hamiltonian constraint, in the full theory. We argue that any reliable state must be independent of the regulating functions and parameters utilized to extract finite results. Using point-splitting regularization, we show that the results, typically regarded either as being purely formal or meaningless, are indeed mathematically rigorous and consistent with the axioms of field theory and regulator independence. Our analysis is carried out at the level of the quantum constraint solutions, and does not consider the algebra of constraints.

  4. Four dimensional supersymmetric theories in presence of a boundary

    Directory of Open Access Journals (Sweden)

    Mir Faizal

    2015-09-01

    Full Text Available In this paper, we study N=1 supersymmetric theories in four dimensions in presence of a boundary. We demonstrate that it is possible to preserve half the supersymmetry of the original theory by suitably modifying it in presence of a boundary. This is done by adding new boundary terms to the original action, such that the supersymmetric variation of the new terms exactly cancels the boundary terms generated by the supersymmetric transformation of the original bulk action. We also analyze the boundary projections of such supercharges used in such a theory. We study super-Yang–Mills theories in presence of a boundary using these results. Finally, we study the Born–Infeld action in presence of a boundary. We analyze the boundary effects for the Born–Infeld action coupled to a background dilaton and an axion field. We also analyze the boundary effects for a non-abelian Born–Infeld action. We explicitly construct the actions for these systems in presence of a boundary. This action preserves half of the original supersymmetry.

  5. Conformal Killing Vectors Of Plane Symmetric Four Dimensional Lorentzian Manifolds

    CERN Document Server

    Khan, Suhail; Bokhari, Ashfaque H; Khan, Gulzar Ali; Mathematics, Department of; Peshawar, University of; Pakhtoonkhwa, Peshawar Khyber; Pakistan.,; Petroleum, King Fahd University of; Minerals,; 31261, Dhahran; Arabia, Saudi

    2015-01-01

    In this paper, we investigate conformal Killing's vectors (CKVs) admitted by some plane symmetric spacetimes. Ten conformal Killing's equations and their general forms of CKVs are derived along with their conformal factor. The existence of conformal Killing's symmetry imposes restrictions on the metric functions. The conditions imposing restrictions on these metric functions are obtained as a set of integrability conditions. Considering the cases of time-like and inheriting CKVs, we obtain spacetimes admitting plane conformal symmetry. Integrability conditions are solved completely for some known non-conformally flat and conformally flat classes of plane symmetric spacetimes. A special vacuum plane symmetric spacetime is obtained, and it is shown that for such a metric CKVs are just the homothetic vectors (HVs). Among all the examples considered, there exists only one case with a six dimensional algebra of special CKVs admitting one proper CKV. In all other examples of non-conformally flat metrics, no proper ...

  6. Four-dimensional heterotic strings and conformal field theory

    Energy Technology Data Exchange (ETDEWEB)

    Luest, D.; Theisen, S.; Zoupanos, G.

    1988-01-25

    The techniques of (super) conformal field theory are applied to 4-dimensional heterotic string theories. We discuss certain aspects of 4-dimensional strings in the framework of the bosonic lattice approach such as the realization of superconformal symmetry, character valued partition functions, construction of vertex operators and ghost picture changing. As an application we compute all possible 3- and 4-point tree amplitudes of the massless fields and derive from them the low energy effective action of the massless modes. Some effects for the massless spectrum due to one-loop string effects are also mentioned.

  7. New four-dimensional integrals by Mellin-Barnes transform

    CERN Document Server

    Allendes, Pedro; Kondrashuk, Igor; Cuello, Eduardo A Notte

    2009-01-01

    This paper is devoted to the calculation by Mellin-Barnes transform of a especial class of integrals. It contains double integrals in the position space in d = 4-2e dimensions, where e is parameter of dimensional regularization. These integrals contribute to the effective action of the N = 4 supersymmetric Yang-Mills theory. The integrand is a fraction in which the numerator is a logarithm of ratio of spacetime intervals, and the denominator is the product of powers of spacetime intervals. According to the method developed in the previous papers, in order to make use of the uniqueness technique for one of two integrations, we shift exponents in powers in the denominator of integrands by some multiples of e. As the next step, the second integration in the position space is done by Mellin-Barnes transform. For normalizing procedure, we reproduce first the known result obtained earlier by Gegenbauer polynomial technique. Then, we make another shift of exponents in powers in the denominator to create the logarith...

  8. From the Hensen net toward four-dimensional biological oceanography

    Science.gov (United States)

    Wiebe, Peter H.; Benfield, Mark C.

    2003-01-01

    The development of quantitative zooplankton collecting systems began with Hensen (1887 Berichte der Kommssion wissenschaftlichen Untersuchung der deutschen Meere in Kiel5, 1-107; 1895 Ergebnisse der Plankton-Expedition der Humbolt-Stiftung. Kiel and Leipzig: Lipsius and Tischer ). Non-opening closing nets, opening closing nets (mostly messenger based), high-speed samplers, and planktobenthos net systems all had their start in his era - the late 1800s and early 1900s. This was also an era in which many of the fundamental questions about the structure and dynamics of the plankton in the worlds oceans were first posed. Fewer new systems were introduced between 1912 and 1950 apparently due in part to the two World Wars. The continuous plankton recorder stands out as a truly innovative device developed during this period ( Hardy 1926b Nature, London118, 630 ). Resurgence in development of mechanically-based instruments occurred during the 1950s and 1960s. A new lineage of high-speed samplers, the Gulf series, began in the 1950s and a number of variants were developed in the 1960s and 1970s. Net systems specifically designed to collect neuston first appeared in the late 1950s. During the 1960s, many focused field and experimental tank experiments were carried out to investigate the hydrodynamics of nets, and much of our knowledge concerning net design and construction criteria was developed. The advent of reliable electrical conducting cables and electrically-based control systems during this same period gave rise first to a variety of cod-end samplers and then to the precursors of the acoustically and electronically-controlled multi-net systems and environmental sensors, which appeared in the 1970s. The decade of the 1970s saw a succession of multi-net systems based both on the Bé multiple plankton sampler and on the Tucker trawl. The advent of the micro-computer stimulated and enabled the development of sophisticated control and data logging electronics for these systems in the 1980s. In the 1990s, acoustic and optical technologies gave rise to sensor systems that either complement multiple net systems or are deployed without nets. Multi-sensor systems with high data telemetry rates through electro-optical cable are now being deployed in towed bodies and on remotely operated vehicles. In the offing are new molecular technologies to identify species in situ, and realtime data analysis, image processing, and 3D/4D display. In the near future, it is likely that the use of multi-sensor systems deployed on autonomous vehicles will yield world wide coverage of the distribution and abundance of zooplankton.

  9. Causal structures in the four dimensional Euclidean space

    CERN Document Server

    Pestov, I B; Pestov, Ivanhoe B.; Saha, Bijan

    2005-01-01

    It is shown that in the 4d Euclidean space there are two causal structures defined by the temporal field. One of them is well-known Minkowski spacetime. In this case the gravitational potential (the positive definite Riemann metric) and temporal field satisfy the Einstein equations with trivial energy-momentum tensor. However, in the case of the second causal structure the gravitational potential and temporal field should be connected with some nontrivial energy-momentum tensor. We consider the simplest case with energy-momentum tensor of the real scalar field and derive exact solution of the field equations. It can be viewed as the ground to consider the second causal structure on the equal footing with the Minkowski spacetime, i.e., as an object interesting from the physical point of view, especially in the framework of the field theory.

  10. Photon gating in four-dimensional ultrafast electron microscopy.

    Science.gov (United States)

    Hassan, Mohammed T; Liu, Haihua; Baskin, John Spencer; Zewail, Ahmed H

    2015-10-20

    Ultrafast electron microscopy (UEM) is a pivotal tool for imaging of nanoscale structural dynamics with subparticle resolution on the time scale of atomic motion. Photon-induced near-field electron microscopy (PINEM), a key UEM technique, involves the detection of electrons that have gained energy from a femtosecond optical pulse via photon-electron coupling on nanostructures. PINEM has been applied in various fields of study, from materials science to biological imaging, exploiting the unique spatial, energy, and temporal characteristics of the PINEM electrons gained by interaction with a "single" light pulse. The further potential of photon-gated PINEM electrons in probing ultrafast dynamics of matter and the optical gating of electrons by invoking a "second" optical pulse has previously been proposed and examined theoretically in our group. Here, we experimentally demonstrate this photon-gating technique, and, through diffraction, visualize the phase transition dynamics in vanadium dioxide nanoparticles. With optical gating of PINEM electrons, imaging temporal resolution was improved by a factor of 3 or better, being limited only by the optical pulse widths. This work enables the combination of the high spatial resolution of electron microscopy and the ultrafast temporal response of the optical pulses, which provides a promising approach to attain the resolution of few femtoseconds and attoseconds in UEM.

  11. Affine group representation formalism for four dimensional, Lorentzian, quantum gravity

    CERN Document Server

    Ching-Yi, Chou; Soo, Chopin

    2012-01-01

    The Hamiltonian constraint of 4-dimensional General Relativity is recast explicitly in terms of the Chern--Simons functional and the local volume operator. In conjunction with the algebraic quantization program, application of the affine quantization concept due to Klauder facilitates the construction of solutions to all of the the quantum constraints in the Ashtekar variables and their associated Hilbert space. A physical Hilbert space is constructed for Lorentzian signature gravity with nonzero cosmological constant in the form of unitary, irreducible representations of the affine group.

  12. Conformal killing vectors of plane symmetric four dimensional lorentzian manifolds

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Suhail; Hussain, Tahir; Khan, Gulzar Ali [University of Peshawar, Department of Mathematics, Peshawar, Khyber Pakhtoonkhwa (Pakistan); Bokhari, Ashfaque H. [King Fahd University of Petroleum and Minerals, Department of Mathematics and Statistics, Dhahran (Saudi Arabia)

    2015-11-15

    In this paper, we investigate conformal Killing vectors (CKVs) admitted by some plane symmetric spacetimes. Ten conformal Killing's equations and their general forms of CKVs are derived along with their conformal factor. The existence of conformal Killing symmetry imposes restrictions on the metric functions. The conditions imposing restrictions on these metric functions are obtained as a set of integrability conditions. Considering the cases of time-like and inheriting CKVs, we obtain spacetimes admitting plane conformal symmetry. Integrability conditions are solved completely for some known non-conformally flat and conformally flat classes of plane symmetric spacetimes. A special vacuum plane symmetric spacetime is obtained, and it is shown that for such a metric CKVs are just the homothetic vectors (HVs). Among all the examples considered, there exists only one case with a six dimensional algebra of special CKVs admitting one proper CKV. In all other examples of non-conformally flat metrics, no proper CKV is found and CKVs are either HVs or Killing's vectors (KVs). In each of the three cases of conformally flat metrics, a fifteen dimensional algebra of CKVs is obtained of which eight are proper CKVs. (orig.)

  13. Four-dimensional optical manipulation of colloidal particles

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Daria, Vincent Ricardo Mancao; Glückstad, Jesper

    2010-01-01

    The technical development of optical tweezers, along with their application in the biological and physical sciences, has progressed significantly since the demonstration of an optical trap for micron-sized particles based on a single, tightly focused laser beam was first reported more than twenty...... of the best in the field, this compendium presents important historical and current developments of optical tweezers in a range of scientific areas, from the manipulation of bacteria to the treatment of DNA.......The technical development of optical tweezers, along with their application in the biological and physical sciences, has progressed significantly since the demonstration of an optical trap for micron-sized particles based on a single, tightly focused laser beam was first reported more than twenty...... explore the pioneering work of Arthur Ashkin and the use of optical tweezers in biological systems. The book then discusses the extensive use of optical tweezers for the measurement of picoNewton forces and examines various approaches for modeling forces within optical tweezers. The next parts explain how...

  14. Four-dimensional Localization and the Iterative Ensemble Kalman Smoother

    Science.gov (United States)

    Bocquet, M.

    2015-12-01

    The iterative ensemble Kalman smoother (IEnKS) is a data assimilation method meant for efficiently tracking the state ofnonlinear geophysical models. It combines an ensemble of model states to estimate the errors similarly to the ensemblesquare root Kalman filter, with a 4D-variational analysis performed within the ensemble space. As such it belongs tothe class of ensemble variational methods. Recently introduced 4DEnVar or the 4D-LETKF can be seen as particular casesof the scheme. The IEnKS was shown to outperform 4D-Var, the ensemble Kalman filter (EnKF) and smoother, with low-ordermodels in all investigated dynamical regimes. Like any ensemble method, it could require the use of localization of theanalysis when the state space dimension is high. However, localization for the IEnKS is not as straightforward as forthe EnKF. Indeed, localization needs to be defined across time, and it needs to be as much as possible consistent withthe dynamical flow within the data assimilation variational window. We show that a Liouville equation governs the timeevolution of the localization operator, which is linked to the evolution of the error correlations. It is argued thatits time integration strongly depends on the forecast dynamics. Using either covariance localization or domainlocalization, we propose and test several localization strategies meant to address the issue: (i) a constant and uniformlocalization, (ii) the propagation through the window of a restricted set of dominant modes of the error covariancematrix, (iii) the approximate propagation of the localization operator using model covariant local domains. Theseschemes are illustrated on the one-dimensional Lorenz 40-variable model.

  15. Topology of four-dimensional lattice gauge fields

    Science.gov (United States)

    Panagiotakopoulos, C.

    1985-08-01

    An extremely careful implementation of Woit's definition of the topological charge for SU(2) lattice gauge fields reveals a scaling violation by the topological susceptibility in the region 2.1Luscher's charge at weak enough coupling.

  16. Four-dimensional optical manipulation of colloidal particles

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Daria, Vincent Ricardo Mancao; Glückstad, Jesper

    2010-01-01

    The technical development of optical tweezers, along with their application in the biological and physical sciences, has progressed significantly since the demonstration of an optical trap for micron-sized particles based on a single, tightly focused laser beam was first reported more than twenty...

  17. Four-dimensional multi-site photolysis of caged neurotransmitters

    Directory of Open Access Journals (Sweden)

    Mary Ann eGo

    2013-12-01

    Full Text Available Neurons receive thousands of synaptic inputs that are distributed in space and time. The systematic study of how neurons process these inputs requires a technique to stimulate multiple yet highly targeted points of interest along the neuron's dendritic tree. Three-dimensional multi-focal patterns produced via holographic projection combined with two-photon photolysis of caged compounds can provide for highly localized release of neurotransmitters within each diffraction-limited focus, and in this way emulate simultaneous synaptic inputs to the neuron. However, this technique so far cannot achieve time-dependent stimulation patterns due to fundamental limitations of the hologram-encoding device and other factors that affect the consistency of controlled synaptic stimulation. Here, we report an advanced technique that enables the design and application of arbitrary spatio-temporal photostimulation patterns that resemble physiological synaptic inputs. By combining holographic projection with a programmable high-speed light-switching array, we have overcome temporal limitations with holographic projection, allowing us to mimic distributed activation of synaptic inputs leading to action potential generation. Our experiments uniquely demonstrate multi-site two-photon glutamate uncaging in three dimensions with submillisecond temporal resolution. Implementing this approach opens up new prospects for studying neuronal synaptic integration in four dimensions.

  18. Determining intrafractional prostate motion using four dimensional ultrasound system

    DEFF Research Database (Denmark)

    Baker, Mariwan; Behrens, Claus F.

    2016-01-01

    ) of the maximal intrafractional displacements were [ mm]; I(+)/ S: (0.2 +/- 0.9); L(+)/ R: (-0.2 +/- 0.8); and A(+)/ P: (-0.2 +/- 1.1), respectively. The largest displacement was 2.8 mm in the posterior direction. The percentage of fractions with displacements larger than 2.0 mm was 4 %, 2 %, and 10 % in the IS......, LR, and AP directions, respectively. The mean of the maximal intrafractional Euclidean distance (3D vector) was 0.9 +/- 0.6 mm. For 12 % of the fractions the maximal 3D vector displacements were larger than 2.0 mm. At only two fractions (4 %) displacements larger than 3. 0 mm were observed...

  19. The transfer matrix in four-dimensional Causal Dynamical Triangulations

    CERN Document Server

    Görlich, Andrzej

    2013-01-01

    Causal Dynamical Triangulations is a background independent approach to quantum gravity. In this paper we introduce a phenomenological transfer matrix model, where at each time step a reduced set of quantum states is used. The states are solely characterized by the discretized spatial volume. Using Monte Carlo simulations we determine the effective transfer matrix elements and extract the effective action for the scale factor. In this framework no degrees of freedom are frozen, however, the obtained action agrees with the minisuperspace model.

  20. The transfer matrix in four-dimensional CDT

    CERN Document Server

    Ambjorn, Jan; Görlich, Andrzej; Jurkiewicz, Jerzy

    2012-01-01

    The Causal Dynamical Triangulation model of quantum gravity (CDT) has a transfer matrix, relating spatial geometries at adjacent (discrete lattice) times. The transfer matrix uniquely determines the theory. We show that the measurements of the scale factor of the (CDT) universe are well described by an effective transfer matrix where the matrix elements are labeled only by the scale factor. Using computer simulations we determine the effective transfer matrix elements and show how they relate to an effective minisuperspace action at all scales.

  1. Four-dimensional conversion for spiritual leadership development: A ...

    African Journals Online (AJOL)

    2014-04-14

    Apr 14, 2014 ... workplace values, it is important to remember that 'spiritual' and 'religious' are not synonymous. .... their special business of making true disciples of Jesus Christ, .... can contribute to the development of an ethical leadership.

  2. Renormalization theory in four dimensional scalar fields. Pt. 1

    Energy Technology Data Exchange (ETDEWEB)

    Gallavotti, G.; Nicolo, F.

    1985-08-01

    We present a renormalization group appraoch to the renormalization thoery of PHI/sub 4//sup 4/ using techniques that have been introduced and used in previous papers and that lead to very simple methods to bound the coefficients of the effective potential and of the Schwinger functions. The main aim of this paper is to show how one can in this way obtain the n-bounds.

  3. Renormalization theory in four dimensional scalar fields. Pt. 2

    Energy Technology Data Exchange (ETDEWEB)

    Gallavotti, G.; Nicolo, F.

    1985-09-01

    We interpret the results of the preceding paper (1985) in terms of partial resummations of the perturbative series for the effective interaction. As an application we sketch how our resummation method leads to a simple summation rule leading to a convergent expansion for the Schwinger functions of the planar PHI/sub 4//sup 4/-theory.

  4. Four-dimensional multi-site two-photon excitation

    CERN Document Server

    Daria, Vincent Ricardo; Bowman, Richard; Redman, Stephen; Bachor, Hans-A

    2009-01-01

    We report the first demonstration of dynamic and arbitrary multi-site two-photon excitation in three-dimensional (3D) space using the holographic projection method. Rapid temporal response (fourth dimension) is achieved through high-speed non-iterative and non-optimized calculation of the hologram using a video graphics accelerator board. We verify that the projected asymmetric spot configurations have sufficient spatiotemporal photon density for localized two-photon excitation. This system is a significant advance and ready for applications such as time-resolved 3D photolysis of complex biological cell and neuronal networks, 3D microscopy, non-linear micro-fabrication and volume holographic optical storage.

  5. Pneumothorax in cardiac pacing

    DEFF Research Database (Denmark)

    Kirkfeldt, Rikke Esberg; Johansen, Jens Brock; Nohr, Ellen Aagaard;

    2012-01-01

    AIM: To identify risk factors for pneumothorax treated with a chest tube after cardiac pacing device implantation in a population-based cohort.METHODS AND RESULTS: A nationwide cohort study was performed based on data on 28 860 patients from the Danish Pacemaker Register, which included all Danish...... patients who received their first pacemaker (PM) or cardiac resynchronization device from 1997 to 2008. Multiple logistic regression was used to estimate adjusted odds ratios (aOR) with 95% confidence intervals for the association between risk factors and pneumothorax treated with a chest tube. The median...... age was 77 years (25th and 75th percentile: 69-84) and 55% were male (n = 15 785). A total of 190 patients (0.66%) were treated for pneumothorax, which was more often in women [aOR 1.9 (1.4-2.6)], and in patients with age >80 years [aOR 1.4 (1.0-1.9)], a prior history of chronic obstructive pulmonary...

  6. Leadership in cardiac surgery.

    Science.gov (United States)

    Rao, Christopher; Patel, Vanash; Ibrahim, Michael; Ahmed, Kamran; Wong, Kathie A; Darzi, Ara; von Segesser, Ludwig K; Athanasiou, Thanos

    2011-06-01

    Despite the efficacy of cardiac surgery, less invasive interventions with more uncertain long-term outcomes are increasingly challenging surgery as first-line treatment for several congenital, degenerative and ischemic cardiac diseases. The specialty must evolve if it is to ensure its future relevance. More importantly, it must evolve to ensure that future patients have access to treatments with proven long-term effectiveness. This cannot be achieved without dynamic leadership; however, our contention is that this is not enough. The demands of a modern surgical career and the importance of the task at hand are such that the serendipitous emergence of traditional charismatic leadership cannot be relied upon to deliver necessary change. We advocate systematic analysis and strategic leadership at a local, national and international level in four key areas: Clinical Care, Research, Education and Training, and Stakeholder Engagement. While we anticipate that exceptional individuals will continue to shape the future of our specialty, the creation of robust structures to deliver collective leadership in these key areas is of paramount importance.

  7. [Cardiac myxoma with cerebral metastases].

    Science.gov (United States)

    Bazin, A; Peruzzi, P; Baudrillard, J C; Pluot, M; Rousseaux, P

    1987-01-01

    A 56 year old woman developed multiple metastases in the cerebrum and cerebellum, four years after cardiac intervention on a left atrial myxoma. The absence of stroke is noteworthy. Multiple high density lesions with contrast enhancement were seen by CT scan, suggesting metastatic neoplasms. Histological examination confirmed the diagnosis of metastases of cardiac myxoma. Only four cases were recorded in the literature.

  8. Cardiac arrest – cardiopulmonary resuscitation

    Directory of Open Access Journals (Sweden)

    Basri Lenjani

    2014-01-01

    Conclusions: All survivors from cardiac arrest have received appropriate medical assistance within 10 min from attack, which implies that if cardiac arrest occurs near an institution health care (with an opportunity to provide the emergent health care the rate of survival is higher.

  9. Health Instruction Packages: Cardiac Anatomy.

    Science.gov (United States)

    Phillips, Gwen; And Others

    Text, illustrations, and exercises are utilized in these five learning modules to instruct nurses, students, and other health care professionals in cardiac anatomy and functions and in fundamental electrocardiographic techniques. The first module, "Cardiac Anatomy and Physiology: A Review" by Gwen Phillips, teaches the learner to draw…

  10. Health Instruction Packages: Cardiac Anatomy.

    Science.gov (United States)

    Phillips, Gwen; And Others

    Text, illustrations, and exercises are utilized in these five learning modules to instruct nurses, students, and other health care professionals in cardiac anatomy and functions and in fundamental electrocardiographic techniques. The first module, "Cardiac Anatomy and Physiology: A Review" by Gwen Phillips, teaches the learner to draw…

  11. The Danish Cardiac Rehabilitation Database

    DEFF Research Database (Denmark)

    Zwisler, Ann-Dorthe; Rossau, Henriette Knold; Nakano, Anne

    2016-01-01

    AIM OF DATABASE: The Danish Cardiac Rehabilitation Database (DHRD) aims to improve the quality of cardiac rehabilitation (CR) to the benefit of patients with coronary heart disease (CHD). STUDY POPULATION: Hospitalized patients with CHD with stenosis on coronary angiography treated with percutane...

  12. Mitochondrial biogenesis in cardiac pathophysiology.

    Science.gov (United States)

    Rimbaud, Stéphanie; Garnier, Anne; Ventura-Clapier, Renée

    2009-01-01

    Cardiac performance depends on a fine balance between the work the heart has to perform to satisfy the needs of the body and the energy that it is able to produce. Thus, energy production by oxidative metabolism, the main energy source of the cardiac muscle, has to be strictly regulated to adapt to cardiac work. Mitochondrial biogenesis is the mechanism responsible for mitochondrial component synthesis and assembly. This process controls mitochondrial content and thus correlates with energy production that, in turn, sustains cardiac contractility. Mitochondrial biogenesis should be finely controlled to match cardiac growth and cardiac work. When the heart is subjected to an increase in work in response to physiological and pathological challenges, it adapts by increasing its mass and expressing a new genetic program. In response to physiological stimuli such as endurance training, mitochondrial biogenesis seems to follow a program involving increased cardiac mass. But in the context of pathological hypertrophy, the modifications of this mechanism remain unclear. What appears clear is that mitochondrial biogenesis is altered in heart failure, and the imbalance between cardiac work demand and energy production represents a major factor in the development of heart failure.

  13. Biosynthesis of cardiac natriuretic peptides

    DEFF Research Database (Denmark)

    Goetze, Jens Peter

    2010-01-01

    . An inefficient post-translational prohormone maturation will also affect the biology of the cardiac natriuretic peptide system. This review aims at summarizing the myocardial synthesis of natriuretic peptides focusing on B-type natriuretic peptide, where new data has disclosed cardiac myocytes as highly...

  14. [Chronic surplus of Japanese cardiac surgeon--ideal nurse practitioner for cardiac surgery, cardiac surgeon's attitude toward the future].

    Science.gov (United States)

    Ikegami, Hirohisa

    2014-03-01

    It is chronically surplus of doctors in the world of cardiac surgery. There are too many cardiac surgeons because cardiac surgery requires a large amount of manpower resources to provide adequate medical services. Many Japanese cardiac surgeons do not have enough opportunity to perform cardiac surgery operations, and many Japanese cardiac surgery residents do not have enough opportunity to learn cardiac surgery operations. There are physician assistants and nurse practitioners in the US. Because they provide a part of medical care to cardiac surgery patients, American cardiac surgeons can focus more energy on operative procedures. Introduction of cardiac surgery specialized nurse practitioner is essential to deliver a high quality medical service as well as to solve chronic problems that Japanese cardiac surgery has had for a long time.

  15. Prospective-gated cardiac micro-CT imaging of free-breathing mice using carbon nanotube field emission x-ray

    Science.gov (United States)

    Cao, Guohua; Burk, Laurel M.; Lee, Yueh Z.; Calderon-Colon, Xiomara; Sultana, Shabana; Lu, Jianping; Zhou, Otto

    2010-01-01

    Purpose: Carbon nanotube (CNT) based field emission x-ray source technology has recently been investigated for diagnostic imaging applications because of its attractive characteristics including electronic programmability, fast switching, distributed source, and multiplexing. The purpose of this article is to demonstrate the potential of this technology for high-resolution prospective-gated cardiac micro-CT imaging. Methods: A dynamic cone-beam micro-CT scanner was constructed using a rotating gantry, a stationary mouse bed, a flat-panel detector, and a sealed CNT based microfocus x-ray source. The compact single-beam CNT x-ray source was operated at 50 KVp and 2 mA anode current with 100 μm×100 μm effective focal spot size. Using an intravenously administered iodinated blood-pool contrast agent, prospective cardiac and respiratory-gated micro-CT images of beating mouse hearts were obtained from ten anesthetized free-breathing mice in their natural position. Four-dimensional cardiac images were also obtained by gating the image acquisition to different phases in the cardiac cycle. Results: High-resolution CT images of beating mouse hearts were obtained at 15 ms temporal resolution and 6.2 lp∕mm spatial resolution at 10% of system MTF. The images were reconstructed at 76 μm isotropic voxel size. The data acquisition time for two cardiac phases was 44±9 min. The CT values observed within the ventricles and the ventricle wall were 455±49 and 120±48 HU, respectively. The entrance dose for the acquisition of a single phase of the cardiac cycle was 0.10 Gy. Conclusions: A high-resolution dynamic micro-CT scanner was developed from a compact CNT microfocus x-ray source and its feasibility for prospective-gated cardiac micro-CT imaging of free-breathing mice under their natural position was demonstrated. PMID:21089765

  16. Prospective-gated cardiac micro-CT imaging of free-breathing mice using carbon nanotube field emission x-ray

    Energy Technology Data Exchange (ETDEWEB)

    Cao Guohua; Burk, Laurel M.; Lee, Yueh Z.; Calderon-Colon, Xiomara; Sultana, Shabana; Lu Jianping; Zhou, Otto [Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599 (United States); Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599 and Department of Radiology, University of North Carolina, Chapel Hill, North Carolina 27599 (United States); Curriculum in Applied Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599 (United States); Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599 (United States) and Curriculum in Applied Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599 (United States); Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599 (United States); Curriculum in Applied Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599 (United States) and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599 (United States)

    2010-10-15

    Purpose: Carbon nanotube (CNT) based field emission x-ray source technology has recently been investigated for diagnostic imaging applications because of its attractive characteristics including electronic programmability, fast switching, distributed source, and multiplexing. The purpose of this article is to demonstrate the potential of this technology for high-resolution prospective-gated cardiac micro-CT imaging. Methods: A dynamic cone-beam micro-CT scanner was constructed using a rotating gantry, a stationary mouse bed, a flat-panel detector, and a sealed CNT based microfocus x-ray source. The compact single-beam CNT x-ray source was operated at 50 KVp and 2 mA anode current with 100 {mu}mx100 {mu}m effective focal spot size. Using an intravenously administered iodinated blood-pool contrast agent, prospective cardiac and respiratory-gated micro-CT images of beating mouse hearts were obtained from ten anesthetized free-breathing mice in their natural position. Four-dimensional cardiac images were also obtained by gating the image acquisition to different phases in the cardiac cycle. Results: High-resolution CT images of beating mouse hearts were obtained at 15 ms temporal resolution and 6.2 lp/mm spatial resolution at 10% of system MTF. The images were reconstructed at 76 {mu}m isotropic voxel size. The data acquisition time for two cardiac phases was 44{+-}9 min. The CT values observed within the ventricles and the ventricle wall were 455{+-}49 and 120{+-}48 HU, respectively. The entrance dose for the acquisition of a single phase of the cardiac cycle was 0.10 Gy. Conclusions: A high-resolution dynamic micro-CT scanner was developed from a compact CNT microfocus x-ray source and its feasibility for prospective-gated cardiac micro-CT imaging of free-breathing mice under their natural position was demonstrated.

  17. Prospective-gated cardiac micro-CT imaging of free-breathing mice using carbon nanotube field emission x-ray.

    Science.gov (United States)

    Cao, Guohua; Burk, Laurel M; Lee, Yueh Z; Calderon-Colon, Xiomara; Sultana, Shabana; Lu, Jianping; Zhou, Otto

    2010-10-01

    Carbon nanotube (CNT) based field emission x-ray source technology has recently been investigated for diagnostic imaging applications because of its attractive characteristics including electronic programmability, fast switching, distributed source, and multiplexing. The purpose of this article is to demonstrate the potential of this technology for high-resolution prospective-gated cardiac micro-CT imaging. A dynamic cone-beam micro-CT scanner was constructed using a rotating gantry, a stationary mouse bed, a flat-panel detector, and a sealed CNT based microfocus x-ray source. The compact single-beam CNT x-ray source was operated at 50 KVp and 2 mA anode current with 100 microm x 100 microm effective focal spot size. Using an intravenously administered iodinated blood-pool contrast agent, prospective cardiac and respiratory-gated micro-CT images of beating mouse hearts were obtained from ten anesthetized free-breathing mice in their natural position. Four-dimensional cardiac images were also obtained by gating the image acquisition to different phases in the cardiac cycle. High-resolution CT images of beating mouse hearts were obtained at 15 ms temporal resolution and 6.2 lp/mm spatial resolution at 10% of system MTF. The images were reconstructed at 76 microm isotropic voxel size. The data acquisition time for two cardiac phases was 44 +/- 9 min. The CT values observed within the ventricles and the ventricle wall were 455 +/- 49 and 120 +/- 48 HU, respectively. The entrance dose for the acquisition of a single phase of the cardiac cycle was 0.10 Gy. A high-resolution dynamic micro-CT scanner was developed from a compact CNT microfocus x-ray source and its feasibility for prospective-gated cardiac micro-CT imaging of free-breathing mice under their natural position was demonstrated.

  18. [Non-cardiac surgery in patients with cardiac disease].

    Science.gov (United States)

    Sellevold, Olav F Münter; Stenseth, Roar

    2010-03-25

    Patients with cardiac disease have a higher incidence of cardiovascular events after non-cardiac surgery than those without such disease. This paper provides an overview of perioperative examinations and treatment. Own experience and systematic literature search through work with European guidelines constitute the basis for recommendations given in this article. Beta-blockers should not be discontinued before surgery. High-risk patients may benefit from beta-blockers administered before major non-cardiac surgery. Slow dose titration is recommended. Echocardiography should be performed before preoperative beta-blockade to exclude latent heart failure. Statins should be considered before elective surgery and coronary intervention (stenting or surgery) before high-risk surgery. Otherwise, interventions should be evaluated irrespective of planned non-cardiac surgery. Patients with unstable coronary syndrome should only undergo non-cardiac surgery on vital indications. Neuraxial techniques are optimal for postoperative pain relief and thus for postoperative mobilization. Thromboprophylaxis is important, but increases the risk of epidural haematoma and requires systematic follow-up with respect to diagnostics and treatment. Little evidence supports the use of different anaesthetic methods in cardiac patients that undergo non-cardiac surgery than in other patients. Stable circulation, sufficient oxygenation, good pain relief, thromboprophylaxis, enteral nutrition and early mobilization are important factors for improving the perioperative course. Close cooperation between anaesthesiologist, surgeon and cardiologist improves logistics and treatment.

  19. Physics of Cardiac Arrhythmogenesis

    Science.gov (United States)

    Karma, Alain

    2013-04-01

    A normal heartbeat is orchestrated by the stable propagation of an excitation wave that produces an orderly contraction. In contrast, wave turbulence in the ventricles, clinically known as ventricular fibrillation (VF), stops the heart from pumping and is lethal without prompt defibrillation. I review experimental, computational, and theoretical studies that have shed light on complex dynamical phenomena linked to the initiation, maintenance, and control of wave turbulence. I first discuss advances made to understand the precursor state to a reentrant arrhythmia where the refractory period of cardiac tissue becomes spatiotemporally disordered; this is known as an arrhythmogenic tissue substrate. I describe observed patterns of transmembrane voltage and intracellular calcium signaling that can contribute to this substrate, and symmetry breaking instabilities to explain their formation. I then survey mechanisms of wave turbulence and discuss novel methods that exploit electrical pacing stimuli to control precursor patterns and low-energy pulsed electric fields to control turbulence.

  20. Cardiac potassium channel subtypes

    DEFF Research Database (Denmark)

    Schmitt, Nicole; Grunnet, Morten; Olesen, Søren-Peter

    2014-01-01

    that they could constitute targets for new pharmacological treatment of atrial fibrillation. The interplay between the different K(+) channel subtypes in both atria and ventricle is dynamic, and a significant up- and downregulation occurs in disease states such as atrial fibrillation or heart failure......About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K(+) channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K(+) channels...... drive the late repolarization of the ventricle with some redundancy, and in atria this repolarization reserve is supplemented by the fairly atrial-specific KV1.5, Kir3, KCa, and K2P channels. The role of the latter two subtypes in atria is currently being clarified, and several findings indicate...

  1. Mediastinitis after cardiac transplantation

    Directory of Open Access Journals (Sweden)

    Noedir A. G. Stolf

    2000-05-01

    Full Text Available OBJECTIVE: Assessment of incidence and behavior of mediastinitis after cardiac transplantation. METHODS: From 1985 to 1999, 214 cardiac transplantations were performed, 12 (5.6% of the transplanted patients developed confirmed mediastinitis. Patient's ages ranged from 42 to 66 years (mean of 52.3±10.0 years and 10 (83.3% patients were males. Seven (58.3% patients showed sternal stability on palpation, 4 (33.3% patients had pleural empyema, and 2 (16.7% patients did not show purulent secretion draining through the wound. RESULTS: Staphylococcus aureus was the infectious agent identified in the wound secretion or in the mediastinum, or both, in 8 (66.7% patients. Staphylococcus epidermidis was identified in 2 (16.7% patients, Enterococcus faecalis in 1 (8.3% patient, and the cause of mediastinitis could not be determined in 1 (8.3% patient. Surgical treatment was performed on an emergency basis, and the extension of the débridement varied with local conditions. In 2 (16.7% patients, we chose to leave the surgical wound open and performed daily dressings with granulated sugar. Total sternal resection was performed in only 1 (8.3% patient. Out of this series, 5 (41.7% patients died, and the causes of death were related to the infection. Autopsy revealed persistence of mediastinitis in 1 (8.3% patient. CONCLUSION: Promptness in diagnosing mediastinitis and precocious surgical drainage have changed the natural evolution of this disease. Nevertheless, observance of the basic precepts of prophylaxis of infection is still the best way to treat mediastinitis.

  2. Platelets and cardiac arrhythmia

    Directory of Open Access Journals (Sweden)

    Jonas S De Jong

    2010-12-01

    Full Text Available Sudden cardiac death remains one of the most prevalent modes of death in industrialized countries, and myocardial ischemia due to thrombotic coronary occlusion is its primary cause. The role of platelets in the occurrence of SCD extends beyond coronary flow impairment by clot formation. Here we review the substances released by platelets during clot formation and their arrhythmic properties. Platelet products are released from three types of platelet granules: dense core granules, alpha-granules, and platelet lysosomes. The physiologic properties of dense granule products are of special interest as a potential source of arrhythmic substances. They are released readily upon activation and contain high concentrations of serotonin, histamine, purines, pyrimidines, and ions such as calcium and magnesium. Potential arrhythmic mechanisms of these substances, e.g. serotonin and high energy phosphates, include induction of coronary constriction, calcium overloading, and induction of delayed after-depolarizations. Alpha-granules produce thromboxanes and other arachidonic acid products with many potential arrhythmic effects mediated by interference with cardiac sodium, calcium and potassium channels. Alpha-granules also contain hundreds of proteins that could potentially serve as ligands to receptors on cardiomyocytes. Lysosomal products probably do not have an important arrhythmic effect. Platelet products and ischemia can induce coronary permeability, thereby enhancing interaction with surrounding cardiomyocytes. Antiplatelet therapy is known to improve survival after myocardial infarction. Although an important part of this effect results from prevention of coronary clot formation, there is evidence to suggest that antiplatelet therapy also induces anti-arrhythmic effects during ischemia by preventing the release of platelet activation products.

  3. Trends in Cardiac Pacemaker Batteries

    Directory of Open Access Journals (Sweden)

    Venkateswara Sarma Mallela

    2004-10-01

    Full Text Available Batteries used in Implantable cardiac pacemakers-present unique challenges to their developers and manufacturers in terms of high levels of safety and reliability. In addition, the batteries must have longevity to avoid frequent replacements. Technological advances in leads/electrodes have reduced energy requirements by two orders of magnitude. Micro-electronics advances sharply reduce internal current drain concurrently decreasing size and increasing functionality, reliability, and longevity. It is reported that about 600,000 pacemakers are implanted each year worldwide and the total number of people with various types of implanted pacemaker has already crossed 3 million. A cardiac pacemaker uses half of its battery power for cardiac stimulation and the other half for housekeeping tasks such as monitoring and data logging. The first implanted cardiac pacemaker used nickel-cadmium rechargeable battery, later on zinc-mercury battery was developed and used which lasted for over 2 years. Lithium iodine battery invented and used by Wilson Greatbatch and his team in 1972 made the real impact to implantable cardiac pacemakers. This battery lasts for about 10 years and even today is the power source for many manufacturers of cardiac pacemakers. This paper briefly reviews various developments of battery technologies since the inception of cardiac pacemaker and presents the alternative to lithium iodine battery for the near future.

  4. Fetal cardiac rhabdomyoma: case report

    Directory of Open Access Journals (Sweden)

    Seyed Mostafa Ghavami

    2016-07-01

    Full Text Available Background: The primary manifestation of cardiac tumors in embryonic period is a very rare condition. Cardiac rhabdomyomas most frequently arise in the ventricular myocardium, they may also occur in the atria and the epicardial surface. In spite of its benign nature, the critical location of the tumor inside the heart can lead to lethal arrhythmias and chamber obstruction. Multiple rhabdomyomas are strongly associated with tuberous sclerosis which is associated with mental retardation and epilepsy of variable severity. Ultrasonography as a part of routine prenatal screening, is the best method for the diagnosis of cardiac rhabdomyomas. In the review of articles published in Iran, fetal cardiac rhabdomyoma was not reported. Case presentation: We report a case of cardiac rhabdomyoma on a 24-year-old gravid 1, referred to Day Medical Imaging Center for routine evaluation of fetal abnormalities at 31 weeks of her gestational age. Ultrasonographic examination displayed a homogenous echogenic mass (13×9mm, originating from the left ventricle of the fetal heart. It was a normal pregnancy without any specific complications. Other organs of the fetus were found normal and no cardiac abnormalities were appeared. No Pericardial fluid effusion was found. The parents did not have consanguineous marriage. They did not also have any specific disease such as tuberous sclerosis. Conclusion: The clinical features of cardiac rhabdomyomas vary widely, depending on the location, size, and number of tumors in the heart. Although cardiac rhabdomyoma is a benign tumor in many affected fetuses, an early prenatal diagnosis of the tumor is of great significance in making efficient planning and providing adequate follow up visits of the patients and the complications such as, heart failure and outlet obstruction of cardiac chambers.

  5. Metoclopramide-induced cardiac arrest

    Directory of Open Access Journals (Sweden)

    Martha M. Rumore

    2011-11-01

    Full Text Available The authors report a case of cardiac arrest in a patient receiving intravenous (IV metoclopramide and review the pertinent literature. A 62-year-old morbidly obese female admitted for a gastric sleeve procedure, developed cardiac arrest within one minute of receiving metoclopramide 10 mg via slow intravenous (IV injection. Bradycardia at 4 beats/min immediately appeared, progressing rapidly to asystole. Chest compressions restored vital function. Electrocardiogram (ECG revealed ST depression indicative of myocardial injury. Following intubation, the patient was transferred to the intensive care unit. Various cardiac dysrrhythmias including supraventricular tachycardia (SVT associated with hypertension and atrial fibrillation occurred. Following IV esmolol and metoprolol, the patient reverted to normal sinus rhythm. Repeat ECGs revealed ST depression resolution without pre-admission changes. Metoclopramide is a non-specific dopamine receptor antagonist. Seven cases of cardiac arrest and one of sinus arrest with metoclopramide were found in the literature. The metoclopramide prescribing information does not list precautions or adverse drug reactions (ADRs related to cardiac arrest. The reaction is not dose related but may relate to the IV administration route. Coronary artery disease was the sole risk factor identified. According to Naranjo, the association was possible. Other reports of cardiac arrest, severe bradycardia, and SVT were reviewed. In one case, five separate IV doses of 10 mg metoclopramide were immediately followed by asystole repeatedly. The mechanism(s underlying metoclopramide’s cardiac arrest-inducing effects is unknown. Structural similarities to procainamide may play a role. In view of eight previous cases of cardiac arrest from metoclopramide having been reported, further elucidation of this ADR and patient monitoring is needed. Our report should alert clinicians to monitor patients and remain diligent in surveillance and

  6. Acupuncture therapy related cardiac injury.

    Science.gov (United States)

    Li, Xue-feng; Wang, Xian

    2013-12-01

    Cardiac injury is the most serious adverse event in acupuncture therapy. The causes include needling chest points near the heart, the cardiac enlargement and pericardial effusion that will enlarge the projected area on the body surface and make the proper depth of needling shorter, and the incorrect needling method of the points. Therefore, acupuncture practitioners must be familiar with the points of the heart projected area on the chest and the correct needling methods in order to reduce the risk of acupuncture therapy related cardiac injury.

  7. Cardiac Involvement in Ankylosing Spondylitis

    Science.gov (United States)

    Ozkan, Yasemin

    2016-01-01

    Ankylosing spondylitis is one of the subgroup of diseases called “seronegative spondyloarthropathy”. Frequently, it affects the vertebral colon and sacroiliac joint primarily and affects the peripheral joints less often. This chronic, inflammatory and rheumatic disease can also affect the extraarticular regions of the body. The extraarticular affections can be ophthalmologic, cardiac, pulmonary or neurologic. The cardiac affection can be 2-10% in all patients. Cardiac complications such as left ventricular dysfunction, aortitis, aortic regurgitation, pericarditis and cardiomegaly are reviewed. PMID:27222669

  8. Epigenetic regulation in cardiac fibrosis

    Institute of Scientific and Technical Information of China (English)

    Li-Ming; Yu; Yong; Xu

    2015-01-01

    Cardiac fibrosis represents an adoptive response in the heart exposed to various stress cues. While resolution of the fibrogenic response heralds normalization of heart function, persistent fibrogenesis is usually associated with progressive loss of heart function and eventually heart failure. Cardiac fibrosis is regulated by a myriad of factors that converge on the transcription of genes encoding extracellular matrix proteins, a process the epigenetic machinery plays a pivotal role. In this minireview, we summarize recent advances regarding the epigenetic regulation of cardiac fibrosis focusing on the role of histone and DNA modifications and non-coding RNAs.

  9. Normal cardiac function in mice with supraphysiological cardiac creatine levels.

    Science.gov (United States)

    Santacruz, Lucia; Hernandez, Alejandro; Nienaber, Jeffrey; Mishra, Rajashree; Pinilla, Miguel; Burchette, James; Mao, Lan; Rockman, Howard A; Jacobs, Danny O

    2014-02-01

    Creatine and phosphocreatine levels are decreased in heart failure, and reductions in myocellular phosphocreatine levels predict the severity of the disease and portend adverse outcomes. Previous studies of transgenic mouse models with increased creatine content higher than two times baseline showed the development of heart failure and shortened lifespan. Given phosphocreatine's role in buffering ATP content, we tested the hypothesis whether elevated cardiac creatine content would alter cardiac function under normal physiological conditions. Here, we report the creation of transgenic mice that overexpress the human creatine transporter (CrT) in cardiac muscle under the control of the α-myosin heavy chain promoter. Cardiac transgene expression was quantified by qRT-PCR, and human CrT protein expression was documented on Western blots and immunohistochemistry using a specific anti-CrT antibody. High-energy phosphate metabolites and cardiac function were measured in transgenic animals and compared with age-matched, wild-type controls. Adult transgenic animals showed increases of 5.7- and 4.7-fold in the content of creatine and free ADP, respectively. Phosphocreatine and ATP levels were two times as high in young transgenic animals but declined to control levels by the time the animals reached 8 wk of age. Transgenic mice appeared to be healthy and had normal life spans. Cardiac morphometry, conscious echocardiography, and pressure-volume loop studies demonstrated mild hypertrophy but normal function. Based on our characterization of the human CrT protein expression, creatine and phosphocreatine content, and cardiac morphometry and function, these transgenic mice provide an in vivo model for examining the therapeutic value of elevated creatine content for cardiac pathologies.

  10. Cardiac catheterization is underutilized after in-hospital cardiac arrest.

    Science.gov (United States)

    Merchant, Raina M; Abella, Benjamin S; Khan, Monica; Huang, Kuang-Ning; Beiser, David G; Neumar, Robert W; Carr, Brendan G; Becker, Lance B; Vanden Hoek, Terry L

    2008-12-01

    Indications for immediate cardiac catheterization in cardiac arrest survivors without ST elevation myocardial infarction (STEMI) are uncertain as electrocardiographic and clinical criteria may be challenging to interpret in this population. We sought to evaluate rates of early catheterization after in-hospital ventricular fibrillation (VF) arrest and the association with survival. Using a billing database we retrospectively identified cases with an ICD-9 code of cardiac arrest (427.5) or VF (427.41). Discharge summaries were reviewed to identify in-hospital VF arrests. Rates of catheterization on the day of arrest were determined by identifying billing charges. Unadjusted analyses were performed using Chi-square, and adjusted analyses were performed using logistic regression. One hundred and ten in-hospital VF arrest survivors were included in the analysis. Cardiac catheterization was performed immediately or within 1 day of arrest in 27% (30/110) of patients and of these patients, 57% (17/30) successfully received percutaneous coronary intervention. Of those who received cardiac catheterization the indication for the procedure was STEMI or new left bundle branch block (LBBB) in 43% (13/30). Therefore, in the absence of standard ECG data suggesting acute myocardial infarction, 57% (17/30) received angiography. Patients receiving cardiac catheterization were more likely to survive than those who did not receive catheterization (80% vs. 54%, psurvival. Future recommendations need to be established to guide clinicians on which arrest survivors might benefit from immediate catheterization.

  11. Use of cardiac biomarkers in neonatology.

    Science.gov (United States)

    Vijlbrief, Daniel C; Benders, Manon J N L; Kemperman, Hans; van Bel, Frank; de Vries, Willem B

    2012-10-01

    Cardiac biomarkers are used to identify cardiac disease in term and preterm infants. This review discusses the roles of natriuretic peptides and cardiac troponins. Natriuretic peptide levels are elevated during atrial strain (atrial natriuretic peptide (ANP)) or ventricular strain (B-type natriuretic peptide (BNP)). These markers correspond well with cardiac function and can be used to identify cardiac disease. Cardiac troponins are used to assess cardiomyocyte compromise. Affected cardiomyocytes release troponin into the bloodstream, resulting in elevated levels of cardiac troponin. Cardiac biomarkers are being increasingly incorporated into clinical trials as indicators of myocardial strain. Furthermore, cardiac biomarkers can possibly be used to guide therapy and improve outcome. Natriuretic peptides and cardiac troponins are potential tools in the diagnosis and treatment of neonatal disease that is complicated by circulatory compromise. However, clear reference ranges need to be set and validation needs to be carried out in a population of interest.

  12. Robotic Applications in Cardiac Surgery

    Directory of Open Access Journals (Sweden)

    Alan P. Kypson

    2008-11-01

    Full Text Available Traditionally, cardiac surgery has been performed through a median sternotomy, which allows the surgeon generous access to the heart and surrounding great vessels. As a paradigm shift in the size and location of incisions occurs in cardiac surgery, new methods have been developed to allow the surgeon the same amount of dexterity and accessibility to the heart in confined spaces and in a less invasive manner. Initially, long instruments without pivot points were used, however, more recent robotic telemanipulation systems have been applied that allow for improved dexterity, enabling the surgeon to perform cardiac surgery from a distance not previously possible. In this rapidly evolving field, we review the recent history and clinical results of using robotics in cardiac surgery.

  13. Recent developments in cardiac pacing.

    Science.gov (United States)

    Rodak, D J

    1995-10-01

    Indications for cardiac pacing continue to expand. Pacing to improve functional capacity, which is now common, relies on careful patient selection and technical improvements, such as complex software algorithms and diagnostic capabilities.

  14. HOSPITAL EXPERIENCE WITH CARDIAC RESUSCITATION.

    Science.gov (United States)

    CASDORPH, H R

    1964-04-01

    In three cases of cardiac arrest in which resuscitation was successful, there were striking similarities. The patients were men with anterior myocardial infarction and the mode of cardiac arrest was ventricular fibrillation. Corrective action was begun promptly after arrest occurred. In each case vasopressor agents were required for three to five days after resuscitation before the cardiovascular system was able to maintain a normal blood pressure without this aid. Convalescence was satisfactory and each patient returned to his usual occupation. The procedure that was used for cardiac resuscitation was based on artifical respiration (by any of several methods) and artificial circulation by external cardiac compression to provide a flow of oxygenated blood to the brain. Once this is established, time is afforded to determine what other steps are needed.

  15. Robotic Applications in Cardiac Surgery

    Directory of Open Access Journals (Sweden)

    Alan P. Kypson MD

    2004-06-01

    Full Text Available Traditionally, cardiac surgery has been performed through a median sternotomy, which allows the surgeon generous access to the heart and surrounding great vessels. As a paradigm shift in the size and location of incisions occurs in cardiac surgery, new methods have been developed to allow the surgeon the same amount of dexterity and accessibility to the heart in confined spaces and in a less invasive manner. Initially, long instruments without pivot points were used, however, more recent robotic telemanipulation systems have been applied that allow for improved dexterity, enabling the surgeon to perform cardiac surgery from a distance not previously possible. In this rapidly evolving field, we review the recent history and clinical results of using robotics in cardiac surgery.

  16. An airline cardiac arrest program

    National Research Council Canada - National Science Library

    O'Rourke, M F; Donaldson, E; Geddes, J S

    1997-01-01

    ...) available for use on airline passengers with cardiac arrest. AEDs were installed on international Qantas aircraft and at major terminals, selected crew were trained in their use, and all crew members were trained in cardiopulmonary resuscitation...

  17. Cardiac manifestations in systemic sclerosis

    Institute of Scientific and Technical Information of China (English)

    Sevdalina; Lambova

    2014-01-01

    Primary cardiac involvement, which develops as a direct consequence of systemic sclerosis(SSc), may manifest as myocardial damage, fibrosis of the conduction system, pericardial and, less frequently, as valvular disease. In addition, cardiac complications in SSc may develop as a secondary phenomenon due to pulmonary arterial hypertension and kidney pathology. The prevalence of primary cardiac involvement in SSc is variable and difficult to determine because of the diversity of cardiac manifestations, the presence of subclinical periods, the type of diagnostic tools applied, and the diversity of patient populations. When clinically manifested, cardiac involvement is thought to be an important prognostic factor. Profound microvascular disease is a pathognomonic feature of SSc, as both vasospasm and structural alterations are present. Such alterations are thought to predict macrovascular atherosclerosis over time. There are contradictory reports regarding the prevalence of atherosclerosis in SSc. According to some authors, the prevalence of atherosclerosis of the large epicardial coronary arteries is similar to that of the general population, in contrast with other rheumatic diseases such as rheumatoid arthritis and systemic lupus erythematosus. However, the level of inflammation in SSc is inferior. Thus, the atherosclerotic process may not be as aggressive and not easily detectable in smaller studies. Echocardiography(especially tissue Doppler imaging), single-photon emission computed tomography, magnetic resonance imaging and cardiac computed tomography are sensitive techniques for earlier detection of both structural and functional scleroderma-related cardiac pathologies. Screening for subclinical cardiac involvement via modern, sensitive tools provides an opportunity for early diagnosis and treatment, which is of crucial importance for a positive outcome.

  18. Cardiac transplantation in Friedreich ataxia.

    Science.gov (United States)

    Yoon, Grace; Soman, Teesta; Wilson, Judith; George, Kristen; Mital, Seema; Dipchand, Anne I; McCabe, Jane; Logan, William; Kantor, Paul

    2012-09-01

    In this article, we describe a 14-year-old boy with a confirmed diagnosis of Friedreich ataxia who underwent cardiac transplantation for left ventricular failure secondary to dilated cardiomyopathy with restrictive physiology. His neurological status prior to transplantation reflected early signs of neurological disease, with evidence of dysarthria, weakness, mild gait impairment, and limb ataxia. We review the ethical issues considered during the process leading to the decision to offer cardiac transplantation.

  19. Cardiac Transplantation in Friedreich Ataxia

    OpenAIRE

    Yoon, Grace; Soman, Teesta; Wilson, Judith; George, Kristen; Mital, Seema; Dipchand, Anne I; McCabe, Jane; Logan, William; Kantor, Paul

    2012-01-01

    In this paper, we describe a 14-year-old boy with a confirmed diagnosis of Friedreich ataxia who underwent cardiac transplantation for left ventricular failure secondary to dilated cardiomyopathy with restrictive physiology. His neurological status prior to transplantation reflected early signs of neurologic disease, with evidence of dysarthria, weakness, mild gait impairment, and limb ataxia. We review the ethical issues considered during the process leading to the decision to offer cardiac ...

  20. Infrequent cardiac manifestations of sarcoidosis.

    Science.gov (United States)

    Ashraf, Said; Briasoulis, Alexandros; Afonso, Luis

    Cardiac sarcoidosis (CS) is found in 2-7% of patients with systemic sarcoidosis (SS). Its diagnosis and treatment is challenging, notwithstanding the poor prognosis and treatment. Hereby, we present a case of systemic sarcoidosis with rare cardiac manifestations of severe mitral incompetence and large coronary aneurysm in a previously healthy woman. She underwent successful mitral valve replacement and coronary artery bypass surgery and was maintained on low dose glucocorticoid therapy. Copyright © 2016. Published by Elsevier Inc.

  1. Teaching of College English Writing Based on "Memes" and "Four Dimensional Space" Theory%“模因论”和“四空间模型理论”指导下的大学英语写作教学

    Institute of Scientific and Technical Information of China (English)

    刘艳; 许丽云

    2012-01-01

    英语写作是大学生英语听、说、读、写四种能力中比较薄弱的一项,针对这种状况,探讨了"模因论"启发下的英语写作教学,并用认知语言学中的"合成空间理论"的典型模型——"四空间模型理论"来分析模因写作教学,重新认识背诵、仿写和联想等一些传统方法对英语写作教学的重要作用,从而为大学英语写作教学提供一条快捷、有效的途径。%Writing ability is the weakest point among listening,speaking,reading and writing skills in College English,so the author made a survey on the influence of the Memes on the English writing,and using the typical representative of "Space Blending Theory" —"Four Dimensional Space " theory,reacquaints ourselves with some traditional teaching methods of writing such as recitation,rewriting and association to provide a quick and convenient way for the teaching of College English Writing.

  2. Cardiac imaging. A multimodality approach

    Energy Technology Data Exchange (ETDEWEB)

    Thelen, Manfred [Johannes Gutenberg University Hospital, Mainz (Germany); Erbel, Raimund [University Hospital Essen (Germany). Dept. of Cardiology; Kreitner, Karl-Friedrich [Johannes Gutenberg University Hospital, Mainz (Germany). Clinic and Polyclinic for Diagnostic and Interventional Radiology; Barkhausen, Joerg (eds.) [University Hospital Schleswig-Holstein, Luebeck (Germany). Dept. of Radiology and Nuclear Medicine

    2009-07-01

    An excellent atlas on modern diagnostic imaging of the heart Written by an interdisciplinary team of experts, Cardiac Imaging: A Multimodality Approach features an in-depth introduction to all current imaging modalities for the diagnostic assessment of the heart as well as a clinical overview of cardiac diseases and main indications for cardiac imaging. With a particular emphasis on CT and MRI, the first part of the atlas also covers conventional radiography, echocardiography, angiography and nuclear medicine imaging. Leading specialists demonstrate the latest advances in the field, and compare the strengths and weaknesses of each modality. The book's second part features clinical chapters on heart defects, endocarditis, coronary heart disease, cardiomyopathies, myocarditis, cardiac tumors, pericardial diseases, pulmonary vascular diseases, and diseases of the thoracic aorta. The authors address anatomy, pathophysiology, and clinical features, and evaluate the various diagnostic options. Key features: - Highly regarded experts in cardiology and radiology off er image-based teaching of the latest techniques - Readers learn how to decide which modality to use for which indication - Visually highlighted tables and essential points allow for easy navigation through the text - More than 600 outstanding images show up-to-date technology and current imaging protocols Cardiac Imaging: A Multimodality Approach is a must-have desk reference for cardiologists and radiologists in practice, as well as a study guide for residents in both fields. It will also appeal to cardiac surgeons, general practitioners, and medical physicists with a special interest in imaging of the heart. (orig.)

  3. Genetic manipulation of cardiac ageing.

    Science.gov (United States)

    Cannon, Leah; Bodmer, Rolf

    2016-04-15

    Ageing in humans is associated with a significant increase in the prevalence of cardiovascular disease. We still do not fully understand the molecular mechanisms underpinning this correlation. However, a number of insights into which genes control cardiac ageing have come from studying hearts of the fruit fly, Drosophila melanogaster. The fly's simple heart tube has similar molecular structure and basic physiology to the human heart. Also, both fly and human hearts experience significant age-related morphological and functional decline. Studies on the fly heart have highlighted the involvement of key nutrient sensing, ion channel and sarcomeric genes in cardiac ageing. Many of these genes have also been implicated in ageing of the mammalian heart. Genes that increase oxidative stress, or are linked to cardiac hypertrophy or neurodegenerative diseases in mammals also affect cardiac ageing in the fruit fly. Moreover, fly studies have demonstrated the potential of exercise and statins to treat age-related cardiac disease. These results show the value of Drosophila as a model to discover the genetic causes of human cardiac ageing. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

  4. [Stem cells and cardiac regeneration].

    Science.gov (United States)

    Perez Millan, Maria Ines; Lorenti, Alicia

    2006-01-01

    Stem cells are defined by virtue of their functional attributes: absence of tissue specific differentitated markers, capable of proliferation, able to self-maintain the population, able to produce a large number of differentiated, functional progeny, able to regenerate the tissue after injury. Cell therapy is an alternative for the treatment of several diseases, like cardiac diseases (cell cardiomyoplasty). A variety of stem cells could be used for cardiac repair: from cardiac and extracardiac sources. Each cell type has its own profile of advantages, limitations, and practicability issues in specific clinical settings. Differentiation of bone marrow stem cells to cardiomyocyte-like cells have been observed under different culture conditions. The presence of resident cardiac stem cell population capable of differentiation into cardiomyocyte or vascular lineage suggests that these cells could be used for cardiac tissue repair, and represent a great promise for clinical application. Stem cells mobilization by cytokines may also offer a strategy for cardiac regeneration. The use of stem cells (embryonic and adult) may hold the key to replacing cells lost in many devastating diseases. This potential benefit is a major focus for stem cell research.

  5. Cardiac Regeneration and Stem Cells.

    Science.gov (United States)

    Zhang, Yiqiang; Mignone, John; MacLellan, W Robb

    2015-10-01

    After decades of believing the heart loses the ability to regenerate soon after birth, numerous studies are now reporting that the adult heart may indeed be capable of regeneration, although the magnitude of new cardiac myocyte formation varies greatly. While this debate has energized the field of cardiac regeneration and led to a dramatic increase in our understanding of cardiac growth and repair, it has left much confusion in the field as to the prospects of regenerating the heart. Studies applying modern techniques of genetic lineage tracing and carbon-14 dating have begun to establish limits on the amount of endogenous regeneration after cardiac injury, but the underlying cellular mechanisms of this regeneration remained unclear. These same studies have also revealed an astonishing capacity for cardiac repair early in life that is largely lost with adult differentiation and maturation. Regardless, this renewed focus on cardiac regeneration as a therapeutic goal holds great promise as a novel strategy to address the leading cause of death in the developed world.

  6. Physiological and pathological cardiac hypertrophy.

    Science.gov (United States)

    Shimizu, Ippei; Minamino, Tohru

    2016-08-01

    The heart must continuously pump blood to supply the body with oxygen and nutrients. To maintain the high energy consumption required by this role, the heart is equipped with multiple complex biological systems that allow adaptation to changes of systemic demand. The processes of growth (hypertrophy), angiogenesis, and metabolic plasticity are critically involved in maintenance of cardiac homeostasis. Cardiac hypertrophy is classified as physiological when it is associated with normal cardiac function or as pathological when associated with cardiac dysfunction. Physiological hypertrophy of the heart occurs in response to normal growth of children or during pregnancy, as well as in athletes. In contrast, pathological hypertrophy is induced by factors such as prolonged and abnormal hemodynamic stress, due to hypertension, myocardial infarction etc. Pathological hypertrophy is associated with fibrosis, capillary rarefaction, increased production of pro-inflammatory cytokines, and cellular dysfunction (impairment of signaling, suppression of autophagy, and abnormal cardiomyocyte/non-cardiomyocyte interactions), as well as undesirable epigenetic changes, with these complex responses leading to maladaptive cardiac remodeling and heart failure. This review describes the key molecules and cellular responses involved in physiological/pathological cardiac hypertrophy. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Recurrent late cardiac tamponade following cardiac surgery : a deceiving and potentially lethal complication

    NARCIS (Netherlands)

    Harskamp, Ralf E.; Meuzelaar, Jacobus J.

    2010-01-01

    Background - Cardiac tamponade, characterized by inflow obstruction of the heart chambers by extracardiac compression, is a potentially lethal complication following cardiac surgery. Case report - We present a case of recurrent cardiac tamponade following valve surgery. At first presentation, diagno

  8. Recurrent late cardiac tamponade following cardiac surgery : a deceiving and potentially lethal complication

    NARCIS (Netherlands)

    Harskamp, Ralf E.; Meuzelaar, Jacobus J.

    2010-01-01

    Background - Cardiac tamponade, characterized by inflow obstruction of the heart chambers by extracardiac compression, is a potentially lethal complication following cardiac surgery. Case report - We present a case of recurrent cardiac tamponade following valve surgery. At first presentation,

  9. Recurrent late cardiac tamponade following cardiac surgery : a deceiving and potentially lethal complication

    NARCIS (Netherlands)

    Harskamp, Ralf E.; Meuzelaar, Jacobus J.

    2010-01-01

    Background - Cardiac tamponade, characterized by inflow obstruction of the heart chambers by extracardiac compression, is a potentially lethal complication following cardiac surgery. Case report - We present a case of recurrent cardiac tamponade following valve surgery. At first presentation, diagno

  10. Risk factors and the effect of cardiac resynchronization therapy on cardiac and non-cardiac mortality in MADIT-CRT

    DEFF Research Database (Denmark)

    Perkiomaki, Juha S; Ruwald, Anne-Christine; Kutyifa, Valentina;

    2015-01-01

    causes, 108 (63.9%) deemed cardiac, and 61 (36.1%) non-cardiac. In multivariate analysis, increased baseline creatinine was significantly associated with both cardiac and non-cardiac deaths [hazard ratio (HR) 2.97, P ...AIMS: To understand modes of death and factors associated with the risk for cardiac and non-cardiac deaths in patients with cardiac resynchronization therapy with implantable cardioverter-defibrillator (CRT-D) vs. implantable cardioverter-defibrillator (ICD) therapy, which may help clarify...... the action and limitations of cardiac resynchronization therapy (CRT) in relieving myocardial dysfunction. METHODS AND RESULTS: In Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT), during 4 years of follow-up, 169 (9.3%) of 1820 patients died of known...

  11. Cardiac output during exercise

    DEFF Research Database (Denmark)

    Siebenmann, C; Rasmussen, P.; Sørensen, H.

    2015-01-01

    Several techniques assessing cardiac output (Q) during exercise are available. The extent to which the measurements obtained from each respective technique compares to one another, however, is unclear. We quantified Q simultaneously using four methods: the Fick method with blood obtained from...... the right atrium (Q(Fick-M)), Innocor (inert gas rebreathing; Q(Inn)), Physioflow (impedance cardiography; Q(Phys)), and Nexfin (pulse contour analysis; Q(Pulse)) in 12 male subjects during incremental cycling exercise to exhaustion in normoxia and hypoxia (FiO2  = 12%). While all four methods reported...... a progressive increase in Q with exercise intensity, the slopes of the Q/oxygen uptake (VO2) relationship differed by up to 50% between methods in both normoxia [4.9 ± 0.3, 3.9 ± 0.2, 6.0 ± 0.4, 4.8 ± 0.2 L/min per L/min (mean ± SE) for Q(Fick-M), Q(Inn), QP hys and Q(Pulse), respectively; P = 0...

  12. Cardiac Imaging System

    Science.gov (United States)

    1990-01-01

    Although not available to all patients with narrowed arteries, balloon angioplasty has expanded dramatically since its introduction with an estimated further growth to 562,000 procedures in the U.S. alone by 1992. Growth has fueled demand for higher quality imaging systems that allow the cardiologist to be more accurate and increase the chances of a successful procedure. A major advance is the Digital Cardiac Imaging (DCI) System designed by Philips Medical Systems International, Best, The Netherlands and marketed in the U.S. by Philips Medical Systems North America Company. The key benefit is significantly improved real-time imaging and the ability to employ image enhancement techniques to bring out added details. Using a cordless control unit, the cardiologist can manipulate images to make immediate assessment, compare live x-ray and roadmap images by placing them side-by-side on monitor screens, or compare pre-procedure and post procedure conditions. The Philips DCI improves the cardiologist's precision by expanding the information available to him.

  13. [Cardiac syncope in children].

    Science.gov (United States)

    Villain, E

    2004-02-01

    Syncope is a frequent problem in childhood; generally, it is an isolated event and the common causes are benign. However, in some circumstances, syncope can herald a potentially lethal problem, especially when occurring during exercise. Routine evaluation includes history, physical examination and a 12-lead standard ECG should be performed in all cases. Worrying features which should be an indication for further investigation include syncope during exercise, collapse in a swimming pool, history of familial sudden death, and abnormalities on clinical exam or ECG. Structural cardiac abnormalities that may cause syncope and sudden death include aortic stenosis, hypertrophic cardiomyopathy and coronary malformations. All children with unrepaired or repaired congenital heart disease who experienced a syncope should be referred to a specialist. Primary arrhythmias that are easily diagnosed on ECG are the long QT syndrome, complete atrio-ventricular block and Wolff-Parkinson-White syndrome; ST elevation in V1-V3 may reveal a Brugada syndrome. Another arrhythmia which is known to be potentially fatal if undiagnosed is the catecholaminergic ventricular tachycardia; the baseline ECG is normal but the arrhythmia is easily reproduced during exercise testing. Finally, vasovagal syncope is the most likely cause of syncope in the young and it usually easily recognized.

  14. [Calpains and cardiac diseases].

    Science.gov (United States)

    Perrin, C; Vergely, C; Rochette, L

    2004-09-01

    Calpains are a large family of cytosolic cysteine proteases composed of at least fourteen distinct isoforms. The family can be divided into two groups on the basis of distribution: ubiquitous and tissue-specific. Our current knowledge about calpains properties apply mainly to the ubiquitous isozymes, micro- and milli-calpain (classic calpains). These forms are activated after autolysis. Translocation and subsequent interactions with phospholipids of these enzymes increase their activity. Calpains are able to cleave a subset of substrates, as enzymes, structural and signalling proteins. Cardiac pathologies, such as heart failure, atrial fibrillation or clinical states particularly ischemia reperfusion, are associated with an increase of cytosolic calcium and in this regards, calpain activation has been evoked as one of the mediators leading to myocardial damage. Calpain activities have been shown to be increased in hearts experimentally subjected to ischemia reperfusion or during hypertrophy, but also in atrial tissue harvested from patients suffering from atrial fibrillations. These activities have been related to an increase of the proteolysis of different myocardial components, particularly, troponins, which are major regulators of the contraction of cardiomyocytes. Moreover, recent works have demonstrated that calpains are involved in the development of myocardial cell death by necrosis or apoptosis.

  15. ECPR for Refractory Out-Of-Hospital Cardiac Arrest

    Science.gov (United States)

    2017-05-17

    Cardiac Arrest; Heart Arrest; Sudden Cardiac Arrest; Cardiopulmonary Arrest; Death, Sudden, Cardiac; Cardiopulmonary Resuscitation; CPR; Extracorporeal Cardiopulmonary Resuscitation; Extracorporeal Membrane Oxygenation

  16. Five-dimensional motion compensation for respiratory and cardiac motion with cone-beam CT of the thorax region

    Science.gov (United States)

    Sauppe, Sebastian; Hahn, Andreas; Brehm, Marcus; Paysan, Pascal; Seghers, Dieter; Kachelrieß, Marc

    2016-03-01

    We propose an adapted method of our previously published five-dimensional (5D) motion compensation (MoCo) algorithm1, developed for micro-CT imaging of small animals, to provide for the first time motion artifact-free 5D cone-beam CT (CBCT) images from a conventional flat detector-based CBCT scan of clinical patients. Image quality of retrospectively respiratory- and cardiac-gated volumes from flat detector CBCT scans is deteriorated by severe sparse projection artifacts. These artifacts further complicate motion estimation, as it is required for MoCo image reconstruction. For high quality 5D CBCT images at the same x-ray dose and the same number of projections as todays 3D CBCT we developed a double MoCo approach based on motion vector fields (MVFs) for respiratory and cardiac motion. In a first step our already published four-dimensional (4D) artifact-specific cyclic motion-compensation (acMoCo) approach is applied to compensate for the respiratory patient motion. With this information a cyclic phase-gated deformable heart registration algorithm is applied to the respiratory motion-compensated 4D CBCT data, thus resulting in cardiac MVFs. We apply these MVFs on double-gated images and thereby respiratory and cardiac motion-compensated 5D CBCT images are obtained. Our 5D MoCo approach processing patient data acquired with the TrueBeam 4D CBCT system (Varian Medical Systems). Our double MoCo approach turned out to be very efficient and removed nearly all streak artifacts due to making use of 100% of the projection data for each reconstructed frame. The 5D MoCo patient data show fine details and no motion blurring, even in regions close to the heart where motion is fastest.

  17. Patch in Cardiac Surgery

    Directory of Open Access Journals (Sweden)

    Alireza Alizadeh Ghavidel

    2014-06-01

    Full Text Available Introduction: Excessive bleeding presents a risk for the patient in cardiovascular surgery. Local haemostatic agents are of great value to reduce bleeding and related complications. TachoSil (Nycomed, Linz, Austria is a sterile, haemostatic agent that consists of an equine collagen patchcoated with human fibrinogen and thrombin. This study evaluated the safety and efficacy of TachoSil compared to conventional technique.Methods: Forty-two patients scheduled for open heart surgeries, were entered to this study from August 2010 to May 2011. After primary haemostatic measures, patients divided in two groups based on surgeon’s judgment. Group A: 20 patients for whom TachoSil was applied and group B: 22 patients that conventional method using Surgicel (13 patients or wait and see method (9 cases, were performed in order to control the bleeding. In group A, 10 patients were male with mean age of 56.95±15.67 years and in group B, 9 cases were male with mean age of 49.95±14.41 years. In case group 70% (14/20 of the surgeries were redo surgeries versus 100% (22/22 in control group.Results: Baseline characteristics were similar in both groups. In TachoSil group 75% of patients required transfusion versus 90.90% in group B (P=0.03.Most transfusions consisted of packed red blood cell; 2±1.13 units in group A versus 3.11±1.44 in group B (P=0.01, however there were no significant differences between two groups regarding the mean total volume of intra and post-operative bleeding. Re-exploration was required in 10% in group A versus 13.63% in group B (P=0.67.Conclusion: TachoSil may act as a superior alternative in different types of cardiac surgery in order to control the bleeding and therefore reducing transfusion requirement.

  18. Dying from cardiac tamponade

    Directory of Open Access Journals (Sweden)

    Powari Manish

    2007-09-01

    Full Text Available Abstract Background To determine the causes of cardiac tamponade (CT, focussing especially on haemopericardium (HP, as a terminal mode of death, within a 430,000 rural English population. Methods Our hospital mortuary register and, all postmortem reports between 1995 and 2004 inclusive, were interrogated for patients dying of CT or HP. The causes of CT/HP and selected morphological characteristics were then determined. Results 14,368 postmortems were performed in this period: of these, 461 patients died of CT. Three cases were due to non-haemorrhagic pericardial effusion. HP accounted for the remaining 458 cases of which, five were post-traumatic, 311 followed rupture of an acute myocardial infarction (RAMI, 138 after intra-pericardial rupture of dissecting ascending aortic aneurysms (RD3A and four were due to miscellaneous causes. HP was more commonly due to RAMI. Men tended to die from RAMI or RD3A earlier than women. RAMI or RD3A were commoner in men Two thirds of RAMI were associated with coronary artery thrombosis. Anterior free wall rupture was commonest overall, and in women, but posterior free wall rupture was commoner in men. The volume of intrapericardial blood in RAMI (mean = 440 ml and RD3A (mean = 498 ml varied between 150 and 1000 ml: intrapericardial blood volume was greater in men than in women dying from either RAMI or RD3A. Conclusion At postmortem, CT is most often related to HP, attributable to either RAMI or intrapericardial RD3A. Post-traumatic and other causes of CT are infrequent.

  19. Cardiac output monitoring

    Directory of Open Access Journals (Sweden)

    Mathews Lailu

    2008-01-01

    Full Text Available Minimally invasive and non-invasive methods of estimation of cardiac output (CO were developed to overcome the limitations of invasive nature of pulmonary artery catheterization (PAC and direct Fick method used for the measurement of stroke volume (SV. The important minimally invasive techniques available are: oesophageal Doppler monitoring (ODM, the derivative Fick method (using partial carbon dioxide (CO 2 breathing, transpulmonary thermodilution, lithium indicator dilution, pulse contour and pulse power analysis. Impedance cardiography is probably the only non-invasive technique in true sense. It provides information about haemodynamic status without the risk, cost and skill associated with the other invasive or minimally invasive techniques. It is important to understand what is really being measured and what assumptions and calculations have been incorporated with respect to a monitoring device. Understanding the basic principles of the above techniques as well as their advantages and limitations may be useful. In addition, the clinical validation of new techniques is necessary to convince that these new tools provide reliable measurements. In this review the physics behind the working of ODM, partial CO 2 breathing, transpulmonary thermodilution and lithium dilution techniques are dealt with. The physical and the physiological aspects underlying the pulse contour and pulse power analyses, various pulse contour techniques, their development, advantages and limitations are also covered. The principle of thoracic bioimpedance along with computation of CO from changes in thoracic impedance is explained. The purpose of the review is to help us minimize the dogmatic nature of practice favouring one technique or the other.

  20. Cardiac pacing and aviation.

    Science.gov (United States)

    Toff, W D; Edhag, O K; Camm, A J

    1992-12-01

    Certain applicants with stable disturbances of rhythm or conduction requiring cardiac pacing, in whom no other disqualifying condition is present, may be considered fit for medical certification restricted to multi-crew operations. The reliability of modern pacing systems appears adequate to permit restricted certification even in pacemaker dependent subjects except for certain models of pacemakers and leads known to be at increased risk of failure. These are to be avoided. There is little evidence to suggest that newer devices are any more reliable than their predecessors. Single and dual chamber systems appear to have similar reliability up to 4 years, after which time significant attrition of dual chamber devices occurs, principally due to battery depletion. All devices require increased scrutiny as they approach their end of life as predicted from longevity data and pacing characteristics. Unipolar and bipolar leads are of similar reliability, apart from a number of specific bipolar polyurethane leads which have been identified. Atrial leads, particularly those without active fixation, are less secure than ventricular leads and applicants who are dependent on atrial sensing or pacing should be denied certification. Bipolar leads are to be preferred due to the lower risk of myopotential and exogenous EMI. Sensor-driven adaptive-rate pacing systems using active sensors may have reduced longevity and require close scrutiny. Activity-sensing devices using piezoelectric crystal sensors may be subject to significant rate rises in rotary wing aircraft. The impracticality of restricted certification in helicopters will, in any event, preclude certification. Such devices would best be avoided in hovercraft (air cushioned vehicle) pilots. Only minor rate rises are likely in fixed-wing aircraft which are unlikely to be of significance. Anti-tachycardia devices and implanted defibrillators are inconsistent with any form of certification to fly.

  1. Cardiac Penetrating Injuries and Pseudoaneurysm

    Institute of Scientific and Technical Information of China (English)

    CHEN Shifeng

    2002-01-01

    Objective To discuss the early diagnosis and treatment of cardiac penetrating injuries and pseudoaneurysm. Methods 18 cases of cardiac penetrating injuries, in which 2 cases were complicated with pseudoaneurysm, were diagnosed by emergency operation and color Doppler echocardiography between May 1973 and Dec. 2001 in our hospital. The basis for emergency operation is the injured path locating in cardiac dangerous zone, severe shock or pericardial tamponade. ResultsAmong 18 cases of this study, 17 cases underwent emergency operation. During the operation, 11 cases were found injured in right ventricle, 2 cases were found injured in right atrium, 1 case was found injured in pulmonary artery,4 cases were found injured in left ventricle, 2 cases were found complicated with pseudoaneurysm. 17cases underwent cardiac repair including 1 case of rupture of aneurysm. 1 case underwent elective aneurysm resection. In whole group, 15 cases survived(83.33% ), 3 cases died( 16.67%). The cause of death is mainly hemorrhagic shock. Conclusion Highly suspicious cardiac penetrating injuries or hemopericaridium should undergo direct operative exploration. Pseudoaneurysm should be resected early,which can prevent severe complications.

  2. Cardiac Manifestation in Dengue Fever.

    Science.gov (United States)

    Arora, Mohit; Patil, Rekha S

    2016-07-01

    To study the cardiac manifestations of the dengue fever. This one year descriptive study was undertaken at KLES Dr. Prabhakar Kore Hospital and Medical Research Centre, Belgaum under the Department of Medicine. A total of 120 patients with either dengue IgM or IgM and IgG were studied. The assessment of cardiac manifestations was done based on electrocardiogram, 2D echocardiography and cardiac enzymes. Of the 120 patients, 85 (70.83%) were males and the male to female ratio was 2.4:1. The mean age of the patients was 33.02 ± 12.71 years. The commonest clinical presentation was myalgia (97.5%) followed by fever (92.5%). On clinical examination 33.33% of the patients had petecheia and only 9 patients having active bleeding manifestation at the time of presentation. A raised CK-MB and Troponin I was observed in 33.3% and 26.7% patients ECG findings revealed normal rhythm among 95% with 15.8% of them having an abnormal heart rate. Rhythm disturbance was noted in 5% of the patients with AV block being the most common (66.67%). Cardiac manifestation in the form of myocarditis was observed in 37.50% of the patients with a positive correlation with the severity of the dengue fever defined as by W.H.O. criteria. Patients with dengue fever are at high risk of developing myocarditis and rhythm disturbance and therefore require a close cardiac monitoring.

  3. Nuclear imaging in cardiac amyloidosis

    Energy Technology Data Exchange (ETDEWEB)

    Glaudemans, A.W.J.M.; Slart, R.H.J.A.; Veltman, N.C.; Dierckx, R.A.J.O. [University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, Hanzeplein 1, P.O. Box 30001, Groningen (Netherlands); Zeebregts, C.J. [University Medical Center Groningen, Department of Surgery (Division of Vascular Surgery), Groningen (Netherlands); Tio, R.A. [University Medical Center Groningen, Department of Cardiology, Groningen (Netherlands); Hazenberg, B.P.C. [University Medical Center Groningen, Department of Rheumatology and Clinical Immunology, Groningen (Netherlands)

    2009-04-15

    Amyloidosis is a disease characterized by depositions of amyloid in organs and tissues. It can be localized (in just one organ) or systemic. Cardiac amyloidosis is a debilitating disease and can lead to arrhythmias, deterioration of heart function and even sudden death. We reviewed PubMed/Medline, without time constraints, on the different nuclear imaging modalities that are used to visualize myocardial amyloid involvement. Several SPECT tracers have been used for this purpose. The results with these tracers in the evaluation of myocardial amyloidosis and their mechanisms of action are described. Most clinical evidence was found for the use of {sup 123}I-MIBG. Myocardial defects in MIBG activity seem to correlate well with impaired cardiac sympathetic nerve endings due to amyloid deposits. {sup 123}I-MIBG is an attractive option for objective evaluation of cardiac sympathetic level and may play an important role in the indirect measurement of the effect of amyloid myocardial infiltration. Other, less sensitive, options are {sup 99m}Tc-aprotinin for imaging amyloid deposits and perhaps {sup 99m}Tc-labelled phosphate derivatives, especially in the differential diagnosis of the aetiology of cardiac amyloidosis. PET tracers, despite the advantage of absolute quantification and higher resolution, are not yet well evaluated for the study of cardiac amyloidosis. Because of these advantages, there is still the need for further research in this field. (orig.)

  4. Application of four Dimensional Color Doppler Ultrasound in Detecting the Size of the Foramen of the Fetus and the Dynamic State of the Blood Flow%四维彩超检测胎儿卵圆孔大小及血流动力学状态的应用

    Institute of Scientific and Technical Information of China (English)

    杜学谦; 贾立娟

    2016-01-01

    本文通过应用四维彩超对胎儿的房间隔与卵圆孔大小与卵圆孔瓣活动与卵圆孔血流动力学状态进行检测的相关研究,并对胎儿的卵圆孔与血流动力学检测方法与标准切面进行分析,对不同的孕周段之间卵圆孔的大小与卵圆孔正常的血流动力学状态有没有差异进行比较,并且对其大小与血流动力学状态与孕周之间的关系进行分析,从而得出结论为:应用四维彩超进行检测能够清晰地显示胎儿房间隔与卵圆孔与卵圆孔瓣运动,卵圆孔的大小与孕周的增加呈正相关关系,对其测量的结果是评价胎儿心脏发育的一项重要的指标。应用彩色多普勒进行检测能够清晰的测出卵圆孔的血流方向、流速、血流频谱图,根据这些可以对两心房之间的压差值进行估计。%This article through to the four dimensional colour to exceed detect fetal round hole size and the interatrial septum and the eggs patent foramen disc activity and patent foramen to study the hemodynamic status, and the patent foramen of fetus and hemodynamic detection method and standard were analyzed, and the cross section of different gestational period between size and patent foramen oval foramen if there is any difference compare normal hemodynamic status, and its size and hemodynamic status and the relationship between gestational age is analyzed, and concluded that application of four dimensional colour to exceed testing can clearly show fetal atrial septum and patent foramen and patent foramen disc movement, the size of the oval foramen was positively correlated with the increase of gestational age, the results of the measurement can be used as ultrasonic evaluation of an important indicator of fetal heart development. Application of color doppler detection can clear direction and velocity of blood flow to the measure patent foramen, the blood flow spectrum, can according to these estimates of the pressure

  5. 二维超声、三维超声TUI以及四维超声三者联合对胎儿唇腭裂畸形的诊断价值%Value of Two-dimensional Ultrasound,Three-dimensional Ultrasound TUI and Four-dimensional Ultrasound Combined Examination in the Diagnosis of Fetal Cleft Lip and Palate Deformities

    Institute of Scientific and Technical Information of China (English)

    罗丽芳; 郑小红; 邓劲瑶; 吴惠双; 朱艳芳

    2016-01-01

    Objective:To investigate the value of two-dimensional ultrasound,three-dimensional ultrasound TUI and four-dimensional ultrasound combine examination in the diagnosis of fetal cleft lip and palate deformities.Method:From March 2014 to February 2016,5400 cases of pregnant women in our hospital were selected.Respectively for two-dimensional ultrasonography,three-dimensional ultrasound,four-dimensional ultrasound and combined examination,antenatal and postnatal number of cleft lip and palate,simple cleft lip and palate number,different gestational weeks of detection rate were compared.Result:Among 5400 cases of pregnant women,203 cases were lost to follow-up,accounted for 3.76%,and the other 5197 cases were produced by normal or induced labor.Postpartum found 23 cases of cleft lip and palate,accounting for 0.44%(23/5197), included 17 cases of children with cleft lip and palate,6 cases of simple lip cleft palate.Maternal gestational age between 24 and 35 weeks,cleft lip and palate and cleft lip and palate see prototype was higher.Conclusion:Two-dimensional ultrasound,three-dimensional ultrasound TUI and four-ultrasound combined examination of cleft lip and palate is much better than that of two-dimensional ultrasound detection rate.It can promote the use in the diagnosis of fetal cleft lip and palate deformities.%目的:探讨二维超声、三维超声TUI以及四维超声三者联合对胎儿唇腭裂畸形的诊断价值。方法:选取本院2014年3月-2016年2月接收的孕妇5400例分别进行单独二维超声检查、单独三维超声、单独四维超声以及二维超声、三维超声TUI以及四维超声联合检查,比较产前、产后唇腭裂数、单纯性唇腭裂数以及不同孕周的检出率情况。结果:5400例产妇中,失访203例,占3.76%,余5197例正常生产或引产生产。产后发现唇腭裂23例,占0.44%(23/5197),其中唇腭裂17例,单纯性唇腭裂6例;此外,若孕周为24~35周,则唇腭裂

  6. Exercise-induced cardiac remodeling.

    Science.gov (United States)

    Weiner, Rory B; Baggish, Aaron L

    2012-01-01

    Early investigations in the late 1890s and early 1900s documented cardiac enlargement in athletes with above-normal exercise capacity and no evidence of cardiovascular disease. Such findings have been reported for more than a century and continue to intrigue scientists and clinicians. It is well recognized that repetitive participation in vigorous physical exercise results in significant changes in myocardial structure and function. This process, termed exercise-induced cardiac remodeling (EICR), is characterized by structural cardiac changes including left ventricular hypertrophy with sport-specific geometry (eccentric vs concentric). Associated alterations in both systolic and diastolic functions are emerging as recognized components of EICR. The increasing popularity of recreational exercise and competitive athletics has led to a growing number of individuals exhibiting these findings in routine clinical practice. This review will provide an overview of EICR in athletes.

  7. [Ectopia cordis and cardiac anomalies].

    Science.gov (United States)

    Cabrera, Alberto; Rodrigo, David; Luis, María Teresa; Pastor, Esteban; Galdeano, José Miguel; Esteban, Susana

    2002-11-01

    Ectopia cordis is a rare disease that occurs in 5.5 to 7.9 per million live births. Only 267 cases had been reported as of 2001, most (95%) associated with other cardiac anomalies. We studied the cardiac malformations associated in 6 patients with ectopia cordis. Depending on where the defect was located, the cases of ectopia were classified into four groups: cervical, thoracic, thoraco-abdominal, and abdominal. All 6 patients died before the third day of life, 4 during delivery. Three of the patients were included in the thoracic group, whereas the other 3 belonged to the thoraco-abdominal group. All the patients had associated ventricular septal defects, 3 double-outlet right ventricle (50%) and the rest (50%) tetralogy of Fallot-pulmonary atresia. Two patients with double-outlet right ventricle presented mitral-valve pathology, a parachute valve and an atresic mitral valve. None of these cardiac anomalies have been reported to date.

  8. Electrophysiological Cardiac Modeling: A Review.

    Science.gov (United States)

    Beheshti, Mohammadali; Umapathy, Karthikeyan; Krishnan, Sridhar

    2016-01-01

    Cardiac electrophysiological modeling in conjunction with experimental and clinical findings has contributed to better understanding of electrophysiological phenomena in various species. As our knowledge on underlying electrical, mechanical, and chemical processes has improved over time, mathematical models of the cardiac electrophysiology have become more realistic and detailed. These models have provided a testbed for various hypotheses and conditions that may not be easy to implement experimentally. In addition to the limitations in experimentally validating various scenarios implemented by the models, one of the major obstacles for these models is computational complexity. However, the ever-increasing computational power of supercomputers facilitates the clinical application of cardiac electrophysiological models. The potential clinical applications include testing and predicting effects of pharmaceutical agents and performing patient-specific ablation and defibrillation. A review of studies involving these models and their major findings are provided.

  9. Cardiac tumours in intrauterine life.

    OpenAIRE

    Groves, A.M.; Fagg, N. L.; Cook, A C; Allan, L. D.

    1992-01-01

    Since 1980, 11 examples of cardiac tumour have been detected in the fetus out of a total of 794 congenital cardiac malformations. Patients were referred because of fetal hydrops in two, a family history of tuberous sclerosis in two, and because of the detection of a tumour mass during a scan at the local hospital in seven. The gestational age range at presentation was from 20-34 weeks. Of eight fetuses where death occurred, the histological type was rhabdomyoma in seven and teratoma in one. I...

  10. Clinical advances on Cardiac Insuffiency

    Directory of Open Access Journals (Sweden)

    Angel Julio Romero Cabrera

    2007-06-01

    Full Text Available Cardiac insuffiency is a complex clinical syndrome which constitutes a common final path to get in by the majority of the cardiac diseases. Studies based on the communitarian surveys shows that from 30 to 40 % of the patients decease within the first year of the diagnosis. The rest of the patients (from 60 to 70 % die within the 5 years after being diagnosed. For this reason it has been called as the ¨cancer of cardiology¨. The objective of this article is to update the advances reached in the clinical and therapeutic aspects of this important syndrome.

  11. Complications after cardiac implantable electronic device implantations

    DEFF Research Database (Denmark)

    Kirkfeldt, Rikke Esberg; Johansen, Jens Brock; Nohr, Ellen Aagaard;

    2014-01-01

    Complications after cardiac implantable electronic device (CIED) treatment, including permanent pacemakers (PMs), cardiac resynchronization therapy devices with defibrillators (CRT-Ds) or without (CRT-Ps), and implantable cardioverter defibrillators (ICDs), are associated with increased patient...

  12. An update on insertable cardiac monitors

    DEFF Research Database (Denmark)

    Olsen, Flemming J; Biering-Sørensen, Tor; Krieger, Derk W

    2015-01-01

    Continuous cardiac rhythm monitoring has undergone compelling progress over the past decades. Cardiac monitoring has emerged from 12-lead electrocardiograms being performed at the discretion of the treating physician to in-hospital telemetry, Holter monitoring, prolonged external event monitoring...

  13. Exercise-related cardiac cardiac rehabilitation arrest In

    African Journals Online (AJOL)

    ... its possible risks. This study attempted to establish the safety of cardiac ... Patients at risk of CA during exercise were essentially not identifiable, since they .... Patient 2 had had a belO\\~-knee amputation as a consequence of a motor vehicle.

  14. Elevated sensitivity to cardiac ischemia in proteinuric rats is independent of adverse cardiac remodeling

    NARCIS (Netherlands)

    Szymanski, Mariusz K.; Hillege, Hans L.; Danser, A. H. Jan; Garrelds, Ingrid M.; Schoemaker, Regien G.

    2013-01-01

    Objectives: Chronic renal dysfunction severely increases cardiovascular risk. Adverse cardiac remodeling is suggested to play a major role as predisposition for increased cardiac ischemic vulnerability. The aim of the present study was to examine the role of adverse cardiac remodeling in cardiac sen

  15. Pregnancy as a cardiac stress model

    OpenAIRE

    2014-01-01

    Cardiac hypertrophy occurs during pregnancy as a consequence of both volume overload and hormonal changes. Both pregnancy- and exercise-induced cardiac hypertrophy are generally thought to be similar and physiological. Despite the fact that there are shared transcriptional responses in both forms of cardiac adaptation, pregnancy results in a distinct signature of gene expression in the heart. In some cases, however, pregnancy can induce adverse cardiac events in previously healthy women witho...

  16. Bifid cardiac apex in a 25-year-old male with sudden cardiac death.

    Science.gov (United States)

    Wu, Annie; Kay, Deborah; Fishbein, Michael C

    2014-01-01

    Although a bifid cardiac apex is common in certain marine animals, it is an uncommon finding in humans. When present, bifid cardiac apex is usually associated with other congenital heart anomalies. We present a case of bifid cardiac apex that was an incidental finding in a 25-year-old male with sudden cardiac death from combined drug toxicity. On gross examination, there was a bifid cardiac apex with a 2-cm long cleft. There were no other significant gross or microscopic abnormalities. This case represents the very rare occurrence of a bifid cardiac apex as an isolated cardiac anomaly.

  17. Cardiac manifestations of myotonic dystrophy type 1

    DEFF Research Database (Denmark)

    Petri, Helle; Vissing, John; Witting, Nanna

    2012-01-01

    To estimate the degree of cardiac involvement regarding left ventricular ejection fraction, conduction abnormalities, arrhythmia, risk of sudden cardiac death (SCD) and the associations between cardiac involvement and cytosine-thymine-guanine (CTG)-repeat, neuromuscular involvement, age and gende...... in patients with myotonic dystrophy type 1 (MD1)....

  18. Optimal Technique in Cardiac Anesthesia Recovery

    NARCIS (Netherlands)

    Svircevic, V.

    2014-01-01

    The aim of this thesis is to evaluate fast-track cardiac anesthesia techniques and investigate their impact on postoperative mortality, morbidity and quality of life. The following topics will be discussed in the thesis. (1.) Is fast track cardiac anesthesia a safe technique for cardiac surgery?

  19. Cardiac anatomy and physiology: a review.

    Science.gov (United States)

    Gavaghan, M

    1998-04-01

    This article reviews the normal anatomy and physiology of the heart. Understanding the normal anatomic and physiologic relationships described in this article will help perioperative nurses care for patients who are undergoing cardiac procedures. Such knowledge also assists nurses in educating patients about cardiac procedures and about activities that can prevent, reverse, or improve cardiac illness.

  20. Multimodality imaging to guide cardiac interventional procedures

    NARCIS (Netherlands)

    Tops, Laurens Franciscus

    2010-01-01

    In recent years, a number of new cardiac interventional procedures have been introduced. Catheter ablation procedures for atrial fibrillation (AF) have been refined and are now considered a good treatment option in patients with drug-refractory AF. In cardiac pacing, cardiac resynchronization therap

  1. Regulation of Cardiac Hypertrophy: the nuclear option

    NARCIS (Netherlands)

    D.W.D. Kuster (Diederik)

    2011-01-01

    textabstractCardiac hypertrophy is the response of the heart to an increased workload. After myocardial infarction (MI) the surviving muscle tissue has to work harder to maintain cardiac output. This sustained increase in workload leads to cardiac hypertrophy. Despite its apparent appropriateness, c

  2. Discovery and progress of direct cardiac reprogramming.

    Science.gov (United States)

    Kojima, Hidenori; Ieda, Masaki

    2017-02-14

    Cardiac disease remains a major cause of death worldwide. Direct cardiac reprogramming has emerged as a promising approach for cardiac regenerative therapy. After the discovery of MyoD, a master regulator for skeletal muscle, other single cardiac reprogramming factors (master regulators) have been sought. Discovery of cardiac reprogramming factors was inspired by the finding that multiple, but not single, transcription factors were needed to generate induced pluripotent stem cells (iPSCs) from fibroblasts. We first reported a combination of cardiac-specific transcription factors, Gata4, Mef2c, and Tbx5 (GMT), that could convert mouse fibroblasts into cardiomyocyte-like cells, which were designated as induced cardiomyocyte-like cells (iCMs). Following our first report of cardiac reprogramming, many researchers, including ourselves, demonstrated an improvement in cardiac reprogramming efficiency, in vivo direct cardiac reprogramming for heart regeneration, and cardiac reprogramming in human cells. However, cardiac reprogramming in human cells and adult fibroblasts remains inefficient, and further efforts are needed. We believe that future research elucidating epigenetic barriers and molecular mechanisms of direct cardiac reprogramming will improve the reprogramming efficiency, and that this new technology has great potential for clinical applications.

  3. Multimodality imaging to guide cardiac interventional procedures

    NARCIS (Netherlands)

    Tops, Laurens Franciscus

    2010-01-01

    In recent years, a number of new cardiac interventional procedures have been introduced. Catheter ablation procedures for atrial fibrillation (AF) have been refined and are now considered a good treatment option in patients with drug-refractory AF. In cardiac pacing, cardiac resynchronization

  4. Regulation of Cardiac Hypertrophy: the nuclear option

    NARCIS (Netherlands)

    D.W.D. Kuster (Diederik)

    2011-01-01

    textabstractCardiac hypertrophy is the response of the heart to an increased workload. After myocardial infarction (MI) the surviving muscle tissue has to work harder to maintain cardiac output. This sustained increase in workload leads to cardiac hypertrophy. Despite its apparent appropriateness, c

  5. Regulation of Cardiac Hypertrophy: the nuclear option

    NARCIS (Netherlands)

    D.W.D. Kuster (Diederik)

    2011-01-01

    textabstractCardiac hypertrophy is the response of the heart to an increased workload. After myocardial infarction (MI) the surviving muscle tissue has to work harder to maintain cardiac output. This sustained increase in workload leads to cardiac hypertrophy. Despite its apparent appropriateness,

  6. Genetic testing for inheritable cardiac channelopathies.

    Science.gov (United States)

    Szepesváry, Eszter; Kaski, Juan Pablo

    2016-05-01

    Cardiac channelopathies are linked to an increased risk of ventricular arrhythmia and sudden death. This article reviews the clinical characteristics and genetic basis of common cardiac ion-channel diseases, highlights some genotype-phenotype correlations, and summarizes genetic testing for inheritable cardiac channelopathies.

  7. Cardiac tumors: optimal cardiac MR sequences and spectrum of imaging appearances.

    LENUS (Irish Health Repository)

    O'Donnell, David H

    2012-02-01

    OBJECTIVE: This article reviews the optimal cardiac MRI sequences for and the spectrum of imaging appearances of cardiac tumors. CONCLUSION: Recent technologic advances in cardiac MRI have resulted in the rapid acquisition of images of the heart with high spatial and temporal resolution and excellent myocardial tissue characterization. Cardiac MRI provides optimal assessment of the location, functional characteristics, and soft-tissue features of cardiac tumors, allowing accurate differentiation of benign and malignant lesions.

  8. Cardiac connexins and impulse propagation

    NARCIS (Netherlands)

    J.A. Jansen; T.A.B. van Veen; J.M.T. de Bakker; H.V.M. van Rijen

    2010-01-01

    Gap junctions form the intercellular pathway for cell-to-cell transmission of the cardiac impulse from its site of origin, the sinoatrial node, along the atria, the atrioventricular conduction system to the ventricular myocardium. The component parts of gap junctions are proteins called connexins (C

  9. Cardiac abnormalities after subarachnoid hemorrhage

    NARCIS (Netherlands)

    Bilt, I.A.C. van der

    2016-01-01

    Aneurysmal subarachnoid hemorrhage(aSAH) is a devastating neurological disease. During the course of the aSAH several neurological and medical complications may occur. Cardiac abnormalities after aSAH are observed often and resemble stress cardiomyopathy or Tako-tsubo cardiomyopathy(Broken Heart Syn

  10. Response to cardiac resynchronization therapy

    DEFF Research Database (Denmark)

    Versteeg, Henneke; Schiffer, Angélique A; Widdershoven, Jos W

    2009-01-01

    Cardiac resynchronization therapy (CRT) is a promising treatment for a subgroup of patients with advanced congestive heart failure and a prolonged QRS interval. Despite the majority of patients benefiting from CRT, 10-40% of patients do not respond to this treatment and are labeled as nonresponders...

  11. Reninoma presenting as cardiac syncope

    Directory of Open Access Journals (Sweden)

    Tak Shahid

    2011-01-01

    Full Text Available Reninoma, a renin-secreting tumor of the juxta-glomerular cells of the kidney, is a rare but surgically treatable cause of secondary hypertension in children. We report a case of reninoma presenting as cardiac syncope with long QTc on electrocardiogram due to hypokalemia.

  12. Takotsubo Cardiomyopathy Following Cardiac Surgery.

    Science.gov (United States)

    Chiariello, Giovanni Alfonso; Bruno, Piergiorgio; Colizzi, Christian; Crea, Filippo; Massetti, Massimo

    2016-02-01

    Takotsubo cardiomyopathy syndrome, commonly occurring in postmenopausal women, is characterized by transient apical systolic dysfunction in absence of coronary lesions. The cardiomyopathy is often observed after intense stressful events such as a major surgical procedure. A 72-year-old woman symptomatic for dyspnea at rest, chest pain, and peripheral edema successfully underwent surgery for noncoronary sinus aneurysm-right atrium fistula repair. Two days after surgery the patient developed takotsubo syndrome, diagnosed according to the Mayo Clinic criteria. We reviewed the literature on takotsubo cardiomyopathy as a complication of major cardiac surgery procedures. Takotsubo cardiomyopathy is confirmed as a possible early complication of cardiac surgery. Exaggerated sympathetic stimulation may cause massive endogenous catecholamine release. Hypoperfusion during cardiopulmonary bypass, inotropic drugs administration, and postoperative anxiety and pain are all factors generating stress, possible coronary artery spasm and transient cardiomyopathy, clinically simulating acute myocardial infarction. Several clinical features have been described such as acute mitral insufficiency, systolic anterior motion of the anterior mitral valve leaflet, left ventricular outflow tract obstruction, acute cardiac failure, and cardiogenic shock. Intraventricular thrombi and adverse cerebrovascular events may also be possible complications. Rare catastrophic events such as left ventricular free wall rupture and ventricular septal perforation have been also encountered. After cardiac surgery takotsubo cardiomyopathy should be suspected if clinical and instrumental criteria are met, and promptly differentiated from the more frequent acute myocardial infarction. Prognosis may be favorable if appropriate conservative medical treatment is promptly started. © 2015 Wiley Periodicals, Inc.

  13. Thoracocentesis in cardiac surgery patients.

    Science.gov (United States)

    Wickbom, Anders; Cha, Soon Ok; Ahlsson, Anders

    2015-01-01

    Pleural effusion following cardiac surgery is a common complication that sometimes requires invasive treatment. Conventional methods for evacuation include needle aspiration and chest tube insertion. We present an effective, easy and potentially time-saving method of thoracocentesis, using a single-lumen central venous catheter.

  14. Cardiac resynchronization therapy in China

    Institute of Scientific and Technical Information of China (English)

    Wei HUA

    2006-01-01

    @@ Congestive heart failure (HF) is a major and growing public health problem. The therapeutic approach includes non-pharmacological measures, pharmacological therapy,mechanical devices, and surgery. Despite the benefits of optimal pharmacologic therapy, the prognosis is still not ideal. At this time, cardiac resynchronization therapy (CRT)has gained wide acceptance as an alternative treatment for HF patients with conduction delay.1

  15. The cardiac patient in Ramadan.

    Science.gov (United States)

    Chamsi-Pasha, Majed; Chamsi-Pasha, Hassan

    2016-01-01

    Ramadan is one of the five fundamental pillars of Islam. During this month, the majority of the 1.6 billion Muslims worldwide observe an absolute fast from dawn to sunset without any drink or food. Our review shows that the impact of fasting during Ramadan on patients with stable cardiac disease is minimal and does not lead to any increase in acute events. Most patients with the stable cardiac disease can fast safely. Most of the drug doses and their regimen are easily manageable during this month and may need not to be changed. Ramadan fasting is a healthy nonpharmacological means for improving cardiovascular risk factors. Most of the Muslims, who suffer from chronic diseases, insist on fasting Ramadan despite being exempted by religion. The Holy Quran specifically exempts the sick from fasting. This is particularly relevant if fasting worsens one's illness or delays recovery. Patients with unstable angina, recent myocardial infarction, uncontrolled hypertension, decompensated heart failure, recent cardiac intervention or cardiac surgery or any debilitating diseases should avoid fasting.

  16. Molecular therapies for cardiac arrhythmias

    NARCIS (Netherlands)

    Boink, G.J.J.

    2013-01-01

    Despite the ongoing advances in pharmacology, devices and surgical approaches to treat heart rhythm disturbances, arrhythmias are still a significant cause of death and morbidity. With the introduction of gene and cell therapy, new avenues have arrived for the local modulation of cardiac disease. Th

  17. [Acute cardiac failure in pheochromocytoma.

    DEFF Research Database (Denmark)

    Jønler, Morten; Munk, Kim

    2008-01-01

    Pheochromocytoma (P) is an endocrine catecholamine-secreting tumor. Classical symptoms like hypertension, attacks of sweating, palpitations, headache and palor are related to catecholamine discharge. We provide a case of P in a 71 year-old man presenting with acute cardiac failure, severe reduction...

  18. Pseudothrombocytopenia in cardiac surgical practice.

    Science.gov (United States)

    Nair, Sukumaran K; Shah, Roma; Petko, Matus; Keogh, Bruce E

    2007-08-01

    Pseudothrombocytopenia is observed occasionally in post-cardiac surgical patients. It is commonly due to EDTA-mediated immunological mechanisms, which lead to agglutination of functionally intact platelets. This condition is harmless and does not warrant platelet transfusion. We describe an instance of pseudothrombocytopenia in our practice and discuss its clinical relevance.

  19. Molecular Modeling of Cardiac Troponin

    Science.gov (United States)

    Manning, Edward P.

    The cardiac thin filament regulates interactions of actin and myosin, the force-generating elements of muscular contraction. Over the past several decades many details have been discovered regarding the structure and function of the cardiac thin filament and its components, including cardiac troponin (cTn). My hypothesis is that signal propagation occurs between distant ends of the cardiac troponin complex through calcium-dependent alterations in the dynamics of cTn and tropomyosin (Tm). I propose a model of the thin filament that encompasses known structures of cTn, Tm and actin to gain insight into cardiac troponin's allosteric regulation of thin filament dynamics. By performing molecular dynamics simulations of cTn in conjunction with overlapping Tm in two conditions, with and without calcium bound to site II of cardiac troponin C (cTnC), I found a combination of calcium-dependent changes in secondary structure and dynamics throughout the cTn-Tm complex. I then applied this model to investigate familial hypertrophic cardiomyopathy (FHC), a disease of the sarcomere that is one of the most commonly occurring genetic causes of heart disease. Approximately 15% of known FHC-related mutations are found in cardiac troponin T (cTnT), most of which are in or flank the alpha-helical N-tail domain TNT1. TNT1 directly interacts with overlapping Tm coiled coils. Using this model I identified effects of TNT1 mutations that propagate to the cTn core where site II of cTnC, the regulatory site of calcium binding in the thin filament, is located. Specifically, I found that mutations in TNT1 alter the flexibility of TNT1 and that the flexibility of TNT1 is inversely proportional to the cooperativity of calcium activation of the thin filament. Further, I identified a pathway of propagation of structural and dynamic changes linking TNT1 to site II of cTnC. Mutation-induced changes at site II cTnC alter calcium coordination which corresponds to biophysical measurements of calcium

  20. Can cardiac surgery cause hypopituitarism?

    Science.gov (United States)

    Francis, Flverly; Burger, Ines; Poll, Eva Maria; Reineke, Andrea; Strasburger, Christian J; Dohmen, Guido; Gilsbach, Joachim M; Kreitschmann-Andermahr, Ilonka

    2012-03-01

    Apoplexy of pituitary adenomas with subsequent hypopituitarism is a rare but well recognized complication following cardiac surgery. The nature of cardiac on-pump surgery provides a risk of damage to the pituitary because the vascular supply of the pituitary is not included in the cerebral autoregulation. Thus, pituitary tissue may exhibit an increased susceptibility to hypoperfusion, ischemia or intraoperative embolism. After on-pump procedures, patients often present with physical and psychosocial impairments which resemble symptoms of hypopituitarism. Therefore, we analyzed whether on-pump cardiac surgery may cause pituitary dysfunction also in the absence of pre-existing pituitary disease. Twenty-five patients were examined 3-12 months after on-pump cardiac surgery. Basal hormone levels for all four anterior pituitary hormone axes were measured and a short synacthen test and a growth hormone releasing hormone plus arginine (GHRH-ARG)-test were performed. Quality of life (QoL), depression, subjective distress for a specific life event, sleep quality and fatigue were assessed by means of self-rating questionnaires. Hormonal alterations were only slight and no signs of anterior hypopituitarism were found except for an insufficient growth hormone rise in two overweight patients in the GHRH-ARG-test. Psychosocial impairment was pronounced, including symptoms of moderate to severe depression in 9, reduced mental QoL in 8, dysfunctional coping in 6 and pronounced sleep disturbances in 16 patients. Hormone levels did not correlate with psychosocial impairment. On-pump cardiac surgery did not cause relevant hypopituitarism in our sample of patients and does not serve to explain the psychosocial symptoms of these patients.

  1. Cardiac energetics: sense and nonsense.

    Science.gov (United States)

    Gibbs, Colin L

    2003-08-01

    1. The background to current ideas in cardiac energetics is outlined and, in the genomic era, the need is stressed for detailed knowledge of mouse heart mechanics and energetics. 2. The mouse heart is clearly different to the rat in terms of its excitation-contraction (EC) coupling and the common assumption that heart rate difference between mice and humans will account for the eightfold difference in myocardial oxygen consumption is wrong, because the energy per beat of the mouse heart is approximately one-third that of the human heart. 3. In vivo evidence suggests that there may well be an eightfold species difference in the non-beating metabolism of mice and human hearts. It is speculated that the magnitude of basal metabolism in the heart is regulatable and that, in the absence of perfusion, it falls to approximately one-quarter of its in vivo rate and that in clinical conditions, such as hibernation, it probably decreases; its magnitude may be controlled by the endothelium. 4. The active energy balance sheet is briefly discussed and it is suggested that the activation heat accounts for 20-25% of the active energy per beat and cross-bridge turnover accounts for the balance. It is argued that force, not shortening, is the major determinant of cardiac energy usage. 5. The outcome of recent cardiac modelling with variants of the Huxley and Hill/Eisenberg models is described. It has been necessary to invoke 'loose coupling' to replicate the low cardiac energy flux measured at low afterloads (medium to high velocities of shortening). 6. Lastly, some of the unexplained or 'nonsense' energetic data are outlined and eight unsolved problems in cardiac energetics are discussed.

  2. Historical-Sample-Projection Four-Dimensional Variational Land Surface Data Assimilation and Its Preliminary Application%基于历史样本投影的四维变分陆面数据同化方法及其初步应用

    Institute of Scientific and Technical Information of China (English)

    赵海贝; 王斌; 戴永久

    2009-01-01

    数据同化方法在大气、海洋和陆面模式中得到了成功的应用.但现有的四维变分同化(4DVar)方法面临着计算量上的挑战.本研究将一种历史样本投影的四维变分同化方法(Historical-Sample-Projection 4DVar,简写为HSP-4DVar)应用于陆面数据同化,建立起CoLM陆面模型的HSP-4DVar系统.相比其他四维变分同化方法,HSP-4DVar的分析值是显式求解,不需要编写和使用伴随模式,从而大大节省了计算量,是一种易于实现的同化方案.通过同化56个月的土壤湿度观测数据表明,新的陆面同化系统不仅省时,而且能够有效吸取观测信息,使得同化后的均方根误差显著降低,各层土壤湿度模拟都有所改善,陆表1000 mm层的改善最为明显.%Data assimilation has been successfully applied in atmospheric, oceanic, and land surface models. However, the four-dimensional variational (4DVar) assimilation system demands great computational costs. The authors introduced a new Historical-Sample-Projection data assimilation scheme (HSP-4DVar) , and accomplished the HSP-4DVar land surface data assimilation system based on the Common Land Model (CoLM). As a scheme which requires no adjoint models, HSP-4DVar can be directly solved and easily realized, therefore avoids high computational costs. The land surface data assimilation system was used to assimilate the soil moisture data for 56 months. After assimilation, the overall root-mean-square error was significantly reduced with improved simulations, especially the simulation for the top 1000 mm layer.

  3. Mitochondria in cardiac hypertrophy and heart failure.

    Science.gov (United States)

    Rosca, Mariana G; Tandler, Bernard; Hoppel, Charles L

    2013-02-01

    Heart failure (HF) frequently is the unfavorable outcome of pathological heart hypertrophy. In contrast to physiological cardiac hypertrophy, which occurs in response to exercise and leads to full adaptation of contractility to the increased wall stress, pathological hypertrophy occurs in response to volume or pressure overload, ultimately leading to contractile dysfunction and HF. Because cardiac hypertrophy impairs the relationship between ATP demand and production, mitochondrial bioenergetics must keep up with the cardiac hypertrophic phenotype. We review data regarding the mitochondrial proteomic and energetic remodeling in cardiac hypertrophy, as well as the temporal and causal relationships between mitochondrial failure to match the increased energy demand and progression to cardiac decompensation. We suggest that the maladaptive effect of sustained neuroendocrine signals on mitochondria leads to bioenergetic fading which contributes to the progression from cardiac hypertrophy to failure. This article is part of a Special Issue entitled "Focus on Cardiac Metabolism". Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Boosters and barriers for direct cardiac reprogramming.

    Science.gov (United States)

    Talkhabi, Mahmood; Zonooz, Elmira Rezaei; Baharvand, Hossein

    2017-06-01

    Heart disease is currently the most significant cause of morbidity and mortality worldwide, which accounts for approximately 33% of all deaths. Recently, a promising and alchemy-like strategy has been developed called direct cardiac reprogramming, which directly converts somatic cells such as fibroblasts to cardiac lineage cells such as cardiomyocytes (CMs), termed induced CMs or iCMs. The first in vitro cardiac reprogramming study, mediated by cardiac transcription factors (TFs)-Gata4, Tbx5 and Mef2C-, was not enough efficient to produce an adequate number of fully reprogrammed, functional iCMs. As a result, numerous combinations of cardiac TFs exist for direct cardiac reprogramming of mouse and human fibroblasts. However, the efficiency of direct cardiac reprogramming remains low. Recently, a number of cellular and molecular mechanisms have been identified to increase the efficiency of direct cardiac reprogramming and the quality of iCMs. For example, microgrooved substrate, cardiogenic growth factors [VEGF, FGF, BMP4 and Activin A], and an appropriate stoichiometry of TFs boost the direct cardiac reprogramming. On the other hand, serum, TGFβ signaling, activators of epithelial to mesenchymal transition, and some epigenetic factors (Bmi1 and Ezh2) are barriers for direct cardiac reprogramming. Manipulating these mechanisms by the application of boosters and removing barriers can increase the efficiency of direct cardiac reprogramming and possibly make iCMs reliable for cell-based therapy or other potential applications. In this review, we summarize the latest trends in cardiac TF- or miRNA-based direct cardiac reprogramming and comprehensively discuses all molecular and cellular boosters and barriers affecting direct cardiac reprogramming. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Cardiac Mapping: Utility or Futility?

    Directory of Open Access Journals (Sweden)

    Gupta Anoop Kumar

    2002-01-01

    Full Text Available Cardiac mapping is a broad term that covers several modes of mapping such as body surface,1 endocardial,2 and epicardial3 mapping. The recording and analysis of extracellular electrograms, reported as early as 1915, forms the basis for cardiac mapping.4 More commonly, cardiac mapping is performed with catheters that are introduced percutaneously into the heart chambers and sequentially record the endocardial electrograms with the purpose of correlating local electrogram to cardiac anatomy. These electrophysiological catheters are navigated and localized with the use of fluoroscopy. Nevertheless, the use of fluoroscopy for these purposes may be problematic for a number of reasons, including: 1 the inability to accurately associate intracardiac electrograms with their precise location within the heart; 2 the endocardial surface is invisible using fluoroscopy and the target sites can only be approximated by their relationship with nearby structures such as ribs, blood vessels, and the position of other catheters; 3 due to the limitations of two-dimensional fluoroscopy, navigation is not exact, time consuming, and requires multiple views to estimate the three-dimensional location of the catheter; 4 inability to accurately return the catheter precisely to a previously mapped site; and 5 exposure of the patient and medical team to radiation. Newer mapping systems have revolutionized the clinical electrophysiology laboratory in recent years and have offered new insights into arrhythmia mechanisms. They are aimed at improving the resolution, three-dimensional spatial localization, and/or rapidity of acquisition of cardiac activation maps. These systems use novel approaches to accurately determine the three-dimensional location of the mapping catheter and local electrograms are acquired using conventional, well-established methods. Recorded data of the catheter location and intracardiac electrogram at that location are used to reconstruct in real-time a

  6. Cardiac troponin: an emerging cardiac biomarker in animal health

    Directory of Open Access Journals (Sweden)

    Vishal V. Undhad

    Full Text Available Analysis of cardiac troponin I (cTn I and T (cTnT are considered the “gold standard” for the non-invasive diagnosis of myocardial injury in human and animals. It has replaced traditionally used cardiac biomarkers such as myoglobin, lactate dehydrogenase (LDH, creatine kinase (CK and CK-MB due to its high sensitivity and specificity for the detection of myocardial injury. Cardiac troponins are proteins that control the calcium-mediated interaction between actin and myosin, allowing contraction at the sarcomere level. Concentration of the cTn can be correlated microscopic lesion and loss of immunolabeling in myocardium damage. Troponin concentration remains elevated in blood for 1-2wks so that wide window is available for diagnosis of myocardial damage. The cTn test has >95% specificity and sensitivity and test is less time consuming (10 to 15 minutes and less costly (INR 200 to INR 500. [Vet. World 2012; 5(8.000: 508-511

  7. Nutritional Status and Cardiac Autophagy

    Directory of Open Access Journals (Sweden)

    Jihyun Ahn

    2013-02-01

    Full Text Available Autophagy is necessary for the degradation of long-lasting proteins and nonfunctional organelles, and is activated to promote cellular survival. However, overactivation of autophagy may deplete essential molecules and organelles responsible for cellular survival. Lifelong calorie restriction by 40% has been shown to increase the cardiac expression of autophagic markers, which suggests that it may have a cardioprotective effect by decreasing oxidative damage brought on by aging and cardiovascular diseases. Although cardiac autophagy is critical to regulating protein quality and maintaining cellular function and survival, increased or excessive autophagy may have deleterious effects on the heart under some circumstances, including pressure overload-induced heart failure. The importance of autophagy has been shown in nutrient supply and preservation of energy in times of limitation, such as ischemia. Some studies have suggested that a transition from obesity to metabolic syndrome may involve progressive changes in myocardial inflammation, mitochondrial dysfunction, fibrosis, apoptosis, and myocardial autophagy.

  8. Biochemical regulators in cardiac hypertrophy.

    Science.gov (United States)

    Kölbel, F; Schreiber, V

    1983-01-01

    In recent years research has shown that muscle is capable of reacting to mechanical stimuli by altering biochemical processes. Myocardium is probably the source of a biochemical factor, or factors which activate myocardial protein synthesis. In experimentally induced cardiac hypertrophy adaptive alterations have been shown to occur not only in the adrenal medulla but also in the adrenal cortex. Finally, detection of cross reactivity between digitalis glycosides and a number of steroid hormones has succeeded. We assume that such cross reactivity indicates the existence of an endogenic factor of steroid character, which is produced in the adrenal gland and functions as an endogenic cardiotonic agent. During experimental cardiac hypertrophy its synthesis is possibly increased. We propose the term "endocardin" or "endocardiotonin" for this agent.

  9. Sudden cardiac death in athletes

    Directory of Open Access Journals (Sweden)

    Fábio Camilo Pellegrino dos Santos

    2012-11-01

    Full Text Available ABSTRACT The most accepted definition of sudden cardiac death nowadays is an unexplained death occurred suddenly within one hour of symptom onset. If it was not witnessed, individuals need to had been observed for at least 24 hours before the event and should be discarded the possibility of non cardiac causes of sudden death, pulmonary embolism or extensive malignancy. The term athlete refers to individuals of any age who participate in collective or individual regular physical activity, as well as physical training program for regular competitions. The sudden death of a young athlete, whether amateur or professional, especially during competitions, is always dramatic, with strong negative social impact and in the media. The fact that sports are recommended as a formula for longevity and quality of life makes these events a cause for concern in sports and society in general.

  10. Heart fields and cardiac morphogenesis.

    Science.gov (United States)

    Kelly, Robert G; Buckingham, Margaret E; Moorman, Antoon F

    2014-10-01

    In this review, we focus on two important steps in the formation of the embryonic heart: (i) the progressive addition of late differentiating progenitor cells from the second heart field that drives heart tube extension during looping morphogenesis, and (ii) the emergence of patterned proliferation within the embryonic myocardium that generates distinct cardiac chambers. During the transition between these steps, the major site of proliferation switches from progenitor cells outside the early heart to proliferation within the embryonic myocardium. The second heart field and ballooning morphogenesis concepts have major repercussions on our understanding of human heart development and disease. In particular, they provide a framework to dissect the origin of congenital heart defects and the regulation of myocardial proliferation and differentiation of relevance for cardiac repair.

  11. Progeria syndrome with cardiac complications.

    Science.gov (United States)

    Ilyas, Saadia; Ilyas, Hajira; Hameed, Abdul; Ilyas, Muhammad

    2013-09-01

    A case report of 6-year-old boy with progeria syndrome, with marked cardiac complications is presented. The boy had cardiorespiratory failure. Discoloured purpuric skin patches, alopecia, prominent forehead, protuberant eyes, flattened nasal cartilage, malformed mandible, hypodentition, and deformed rigid fingers and toes were observed on examination. The boy was unable to speak. A sclerotic systolic murmur was audible over the mitral and aortic areas. Chest x-rays showed cardiac enlargement and the electrocardiogram (ECG) showed giant peaked P waves (right atrial hypertrophy) and right ventricular hypertrophy. Atherosclerotic dilated ascending aorta, thickened sclerotic aortic, mitral, and tricuspid valves with increased echo texture, left and right atrial and right ventricular dilatation, reduced left ventricular cavity, and thickened speckled atrial and ventricular septa were observed on echocardiography.

  12. [Cardiac cephalgia: an underdiagnosed condition? ].

    Science.gov (United States)

    Gutiérrez Morlote, Jesús; Fernández García, José M; Timiraos Fernández, Juan J; Llano Cardenal, Miguel; Llano Catedral, Miguel; Rodríguez Rodríguez, Eloy; Pascual Gómez, Julio

    2005-12-01

    Cardiac cephalgia, or headache occurring as manifestation of myocardial ischemia, has only recently been recognized as a distinct entity. In patients with known ischemic cardiopathy, its diagnosis depends on the presence of severe headache that is accompanied by nausea, worsened by physical exercise, and only ceases with nitrate administration. We report on two patients who met diagnostic criteria for this entity. In both, headache was the only symptom of coronary ischemia, and delayed its diagnosis. Headache occurred both at rest and during exertion, and resolved only after the administration of nitrates. Cardiac cephalgia should be suspected in patients with a history of ischemic cardiopathy who present with de novo headache, even when thoracic pain is absent, especially if the headache improves with nitrates. Differential diagnosis with migraine is crucial to avoid the administration of vasoconstrictors.

  13. [Cardiac toxicity of 5-fluorouracil].

    Science.gov (United States)

    Fournier, C; Benahmed, M; Blondeau, M

    1989-02-01

    A 67 year-old patient receives 5-fluorouracil for vocal chord cancer. During the perfusion, atypical angina pain occurs, accompanied with offset of ST above the baseline in standard leads and in V4 through V6. The pain subsides spontaneously in 45 minutes. These ECG alterations are followed 48 hours later by diffuse inverted T waves with lengthened QT. Cardiac ultrasonography and isotopic angiography do not show any abnormality of the left ventricular function, but myocardial tomoscintigraphy with labelled thallium show a lower hypofixation on exertion. The cardiac toxicity of 5-fluorouracil is in frequent. It is usually believed that it involves a coronary spasm, as suggested by the ECG tracing in the reported cases. The incident, which may be painful or painless, may result in a myocardial infarction or even sudden death during the perfusion. Therefore, it is advisable to discontinue the treatment as soon as an angina-type pain occurs.

  14. Systems biology and cardiac arrhythmias.

    Science.gov (United States)

    Grace, Andrew A; Roden, Dan M

    2012-10-27

    During the past few years, the development of effective, empirical technologies for treatment of cardiac arrhythmias has exceeded the pace at which detailed knowledge of the underlying biology has accumulated. As a result, although some clinical arrhythmias can be cured with techniques such as catheter ablation, drug treatment and prediction of the risk of sudden death remain fairly primitive. The identification of key candidate genes for monogenic arrhythmia syndromes shows that to bring basic biology to the clinic is a powerful approach. Increasingly sophisticated experimental models and methods of measurement, including stem cell-based models of human cardiac arrhythmias, are being deployed to study how perturbations in several biologic pathways can result in an arrhythmia-prone heart. The biology of arrhythmia is largely quantifiable, which allows for systematic analysis that could transform treatment strategies that are often still empirical into management based on molecular evidence.

  15. Approach to cardiac resyncronization therapy

    DEFF Research Database (Denmark)

    Dobreanu, Dan; Dagres, Nikolaos; Svendsen, Jesper Hastrup

    2012-01-01

    AIMS: The purpose of this EP Wire is to compare indications, techniques, implant strategy, and follow-up regarding cardiac resynchronization therapy (CRT) in several countries across Europe. METHODS AND RESULTS: Forty-one centres, members of the EHRA-EP Research Network, responded to this survey...... fibrillation and standard criteria for CRT. In 24% of the centres, biventricular pacemaker (CRT-P) is implanted in all situations, unless there is an indication for secondary prevention of sudden cardiac death, while 10% always choose to implant a biventricular defibrillator (CRT-D). There are no clear...... evidence-based recommendations concerning the implant procedure and follow-up in patients treated with CRT; therefore, the chosen strategies vary widely from one centre to another. CONCLUSION: This EP Wire survey shows a wide variation not only as far as CRT indications are concerned, but especially...

  16. CARDIAC TRANSPLANTATION: AN ANESTHETIC CHALLENGE

    Directory of Open Access Journals (Sweden)

    Premalatha

    2014-05-01

    Full Text Available : Heart transplantation has emerged as the definitive therapy for patients with end-stage cardiomyopathy. The two most common forms of cardiac disease that lead to transplantation are ischemic cardiomyopathy and dilated cardiomyopathy, which together comprise approximately 90% of cases. The other less common forms of heart disease include viral cardiomyopathy, infiltrative cardiomyopathy, postpartum cardiomyopathy, valvular heart disease and congenital heart disease

  17. Cardiac involvement in myotonic dystrophy

    Directory of Open Access Journals (Sweden)

    Koroush Khalighi

    2015-02-01

    Full Text Available Background: Myotonic dystrophy (DM is an inherited progressive muscle disorder caused by defects in muscle proteins. As the incidence of this condition is low, not many are familiar with the multisystem involvement. At times, cardiac disease may even be the predominant manifestation in the form of arrhythmias, conduction defects, and cardiomyopathies. The progression of the disease can lead to sudden, unpredictable death. Thus, it is important to identify this subgroup and treat accordingly. Objective: To identify patients with DM and assess their risk for sudden cardiac death. Methods: Nine patients previously diagnosed with muscular dystrophy were evaluated by cardiologists for various reasons, from a general follow-up to cardiac arrest. All of them had electrocardiograms (EKG and 2-D echocardiograms, and seven of them had further electrophysiological (EP studies. Results: Of the nine patients with DM, eight had EKG evidence of conduction abnormalities ranging from first-degree heart block to complete heart block. Of the seven who had EP studies, five had inducible ventricular tachycardia requiring immediate cardioversion and implantable cardioverter defibrillator (ICD implant. Two of them underwent permanent pacemaker placement due to complete heart block and infra-Hissian block. The remaining two patients opted for a conservative approach with yearly EKG monitoring. Conclusion: Because one-third of the cardiac deaths in patients with DM are sudden, there is a strong need to identify these patients and intervene in those at high risk. Prophylactic pacemaker placement is recommended even in those with minimal conduction system abnormality. However, the common practice is to identify patients at high risk of conduction abnormalities by EP studies and then provide them with prophylactic invasive strategies.

  18. Chaos control of cardiac arrhythmias.

    Science.gov (United States)

    Garfinkel, A; Weiss, J N; Ditto, W L; Spano, M L

    1995-01-01

    Chaos theory has shown that many disordered and erratic phenomena are in fact deterministic, and can be understood causally and controlled. The prospect that cardiac arrhythmias might be instances of deterministic chaos is therefore intriguing. We used a recently developed method of chaos control to stabilize a ouabain-induced arrhythmia in rabbit ventricular tissue in vitro. Extension of these results to clinically significant arrhythmias such as fibrillation will require overcoming the additional obstacles of spatiotemporal complexity.

  19. Pregnancy as a cardiac stress model.

    Science.gov (United States)

    Chung, Eunhee; Leinwand, Leslie A

    2014-03-15

    Cardiac hypertrophy occurs during pregnancy as a consequence of both volume overload and hormonal changes. Both pregnancy- and exercise-induced cardiac hypertrophy are generally thought to be similar and physiological. Despite the fact that there are shared transcriptional responses in both forms of cardiac adaptation, pregnancy results in a distinct signature of gene expression in the heart. In some cases, however, pregnancy can induce adverse cardiac events in previously healthy women without any known cardiovascular disease. Peripartum cardiomyopathy is the leading cause of non-obstetric mortality during pregnancy. To understand how pregnancy can cause heart disease, it is first important to understand cardiac adaptation during normal pregnancy. This review provides an overview of the cardiac consequences of pregnancy, including haemodynamic, functional, structural, and morphological adaptations, as well as molecular phenotypes. In addition, this review describes the signalling pathways responsible for pregnancy-induced cardiac hypertrophy and angiogenesis. We also compare and contrast cardiac adaptation in response to disease, exercise, and pregnancy. The comparisons of these settings of cardiac hypertrophy provide insight into pregnancy-associated cardiac adaptation.

  20. Pregnancy as a cardiac stress model

    Science.gov (United States)

    Chung, Eunhee; Leinwand, Leslie A.

    2014-01-01

    Cardiac hypertrophy occurs during pregnancy as a consequence of both volume overload and hormonal changes. Both pregnancy- and exercise-induced cardiac hypertrophy are generally thought to be similar and physiological. Despite the fact that there are shared transcriptional responses in both forms of cardiac adaptation, pregnancy results in a distinct signature of gene expression in the heart. In some cases, however, pregnancy can induce adverse cardiac events in previously healthy women without any known cardiovascular disease. Peripartum cardiomyopathy is the leading cause of non-obstetric mortality during pregnancy. To understand how pregnancy can cause heart disease, it is first important to understand cardiac adaptation during normal pregnancy. This review provides an overview of the cardiac consequences of pregnancy, including haemodynamic, functional, structural, and morphological adaptations, as well as molecular phenotypes. In addition, this review describes the signalling pathways responsible for pregnancy-induced cardiac hypertrophy and angiogenesis. We also compare and contrast cardiac adaptation in response to disease, exercise, and pregnancy. The comparisons of these settings of cardiac hypertrophy provide insight into pregnancy-associated cardiac adaptation. PMID:24448313