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With its need for high SNR and short acquisition times, Cardiac MRI (CMR) is an intriguing target application for ultrahigh field MRI. Due to the sheer size of the upper torso, however, the known RF issues of 7T MRI are also most prominent in CMR. Recent years brought substantial progress but the full potential of the ultrahigh field for CMR is yet to be exploited. Parallel transmission (pTx) is a promising approach in this context and several groups have already reported B1 shimming for 7T CMR. In such a static pTx application amplitudes and phases of all Tx channels are adjusted individually but otherwise imaging techniques established in current clinical practice 1.5 T and 3 T are applied. More advanced forms of pTx as spatially selective excitation (SSE) using Transmit SENSE promise additional benefits like faster imaging with reduced fields of view or improved SAR control. SSE requires the full dynamic capabilities of pTx, however, and for the majority of today's implemented pTx hardware the internal synchronization of the Tx array does not easily permit external triggering as needed for CMR. Here we report a software solution to this problem and demonstrate the feasibility of CINE CMR at 7 T using a Tx array.
South Africa in recent years is the establishment of a number of research hubs involved in AI activities ranging from mobile robotics and computational intelligence, to knowledge representation and reasoning, and human language technologies. In this survey we take the reader through a quick tour of the research being conducted at these hubs, and touch on an initiative to maintain and extend the current level of interest in AI research in the country.
This paper presents the latest prototype of the integrated emitter turn-off thyristor concept, which potentially ranks among thyristor high-power devices like the gate turn-off thyristor and the integrated gate-commutated thyristor (IGCT). Due to modifications of the external driver stage and mechanical press-pack design optimization, this prototype allows for full device characterization. The turn-off capability was increased to 1600 A with an active silicon area of 823mm2 . This leads to a transient peak power of 672.1kW/cm² . Within this paper, measurements and concept assessment are presented and a comparison to state-of-the-art IGCT devices is provided.
The assessment of the right ventricle (RV) is a challenge in today's cardiology, but of growing clinical impact regarding patient prognosis in different cardiac diseases. The detection and differentiation of small wall motion abnormalities may help to enhance the differentiation of cardiomyopathies including Arrhythmogenic Rightventricular Cardiomyopathy. Cardiovascular magnetic resonance (CMR) at 1.5T is the accepted gold standard for RV quantification. The higher spatial resolution achievable at ultrahigh field strength (UHF) offers the potential to gain new insights into the structure and function of the RV. To approach this goal accurate RV chamber quantification at 7T has to be proven. Consequently this study examines the feasibility of assessment of RV dimensions and function at 7T using improved spatial resolution enabled by the intrinsic sensitivity gain of UHF CMR. For this purpose, a dedicated 16 channel TX/RX RF coil array is used together with 2D CINE fast gradient echo (FGRE) imaging. For comparison RV chamber quantification is conducted at 1.5T using a SSFP based state of the art clinical protocol.
Cardiac MR (CMR) at ultrahigh (≥7.0 T) fields is regarded as one of the most challenging MRI applications. At 7.0 T image quality is not always exclusively defined by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Detrimental effects bear the potential to spoil the signal-to-noise (SNR) and contrast-to-noise (CNR) benefits of cardiac MR (CMR) at 7.0 T. B₁⁺-inhomogeneities and signal voids represent the main challenges. Various pioneering coil concepts have been proposed to tackle these issues, enabling cardiac MRI at 7.0 T. This includes a trend towards an ever larger number of transmit and receive channels. This approach affords multi-dimensional B₁⁺ modulations to improve B₁⁺ shimming performance and to enhance RF efficiency. Also, parallel imaging benefits from a high number of receive channels enabling two-dimensional acceleration. Realizing the limitations of existing coil designs tailored for UHF CMR and recognizing the opportunities of a many element TX/RX channel architecture this work proposes a modular, two dimensional 32-channel transmit and receive array using loop elements and examines its efficacy for enhanced B¹+ homogeneity and improved parallel imaging performance.
Purpose:
To investigate the feasibility of using magnetohydrodynamic (MHD) effects for synchronization of magnetic resonance imaging (MRI) with the cardiac cycle.
Materials and Methods:
The MHD effect was scrutinized using a pulsatile flow phantom at B0 = 7.0 T. MHD effects were examined in vivo in healthy volunteers (n = 10) for B0 ranging from 0.05–7.0 T. Noncontrast-enhanced MR angiography (MRA) of the carotids was performed using a gated steady-state free-precession (SSFP) imaging technique in conjunction with electrocardiogram (ECG) and MHD synchronization.
Results:
The MHD potential correlates with flow velocities derived from phase contrast MRI. MHD voltages depend on the orientation between B0 and the flow of a conductive fluid. An increase in the interelectrode spacing along the flow increases the MHD potential. In vivo measurement of the MHD effect provides peak voltages of 1.5 mV for surface areas close to the common carotid artery at B0 = 7.0 T. Synchronization of MRI with the cardiac cycle using MHD triggering is feasible. MHD triggered MRA of the carotids at 3.0 T showed an overall image quality and richness of anatomic detail, which is comparable to ECG-triggered MRAs.
Conclusion:
This feasibility study demonstrates the use of MHD effects for synchronization of MR acquisitions with the cardiac cycle. J. Magn. Reson. Imaging 2012;36:364–372. © 2012 Wiley Periodicals, Inc.
Wir stellen einen USB-Baustein vor, der eine kostengünstige und universelle Möglichkeit schafft , im Unterricht den Themenkreis Messen-Steuern-Regeln zu behandeln. Die Funktionalität orientiert sich am CVK-Interface der Firma Fischertechnik. Im Gegensatz zu kommerziellen Lösungen erlaubt unser Aufbau auch den preiswerten Einsatz in Gruppen- oder Einzelarbeit. Abschließend berichten wir über ein Beispiel aus dem Unterrichtseinsatz.
Spontaneous language has rarely been subjected to neuroimaging studies. This study therefore introduces a newly developed method for the analysis of linguistic phenomena observed in continuous language production during fMRI.
Most neuroimaging studies investigating language have so far focussed on single word or — to a smaller extent — sentence processing, mostly due to methodological considerations. Natural language production, however, is far more than the mere combination of words to larger units. Therefore, the present study aimed at relating brain activation to linguistic phenomena like word-finding difficulties or syntactic completeness in a continuous language fMRI paradigm. A picture description task with special constraints was used to provoke hesitation phenomena and speech errors. The transcribed speech sample was segmented into events of one second and each event was assigned to one category of a complex schema especially developed for this purpose. The main results were: conceptual planning engages bilateral activation of the precuneus. Successful lexical retrieval is accompanied – particularly in comparison to unsolved word-finding difficulties – by the left middle and superior temporal gyrus. Syntactic completeness is reflected in activation of the left inferior frontal gyrus (IFG) (area 44). In sum, the method has proven to be useful for investigating the neural correlates of lexical and syntactic phenomena in an overt picture description task. This opens up new prospects for the analysis of spontaneous language production during fMRI.
Cardiac MR (CMR) is of proven clinical value but also an area of vigorous ongoing research since image quality is not always exclusively defined by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Recent developments of CMR at 7.0 T have been driven by pioneering explorations into novel multichannel transmit and receive coil array technology to tackle the challenges B1+-field inhomogeneities, to offset specific-absorption rate (SAR) constraints and to reduce banding artifacts in SSFP imaging. For this study, recognition of the benefits and performance of local surface Tx/Rx-array structures recently established at 7.0 T inspired migration to 3.0 T, where RF inhomogeneities and SAR limitations encountered in routine clinical CMR, though somewhat reduced versus the 7.0 T situation, remain significant. For all these reasons, this study was designed to build and examine the feasibility of a local four channel Tx/Rx cardiac coil array for anatomical and functional cardiac imaging at 3.0 T. For comparison, a homebuilt 4 channel Rx cardiac coil array exhibiting the same geometry as the Tx/Rx coil and a Rx surface coil array were used.
A magnetic resonance tomography (MRT) apparatus (1) for the examination of a body (14) comprises parameter acquisition devices (13) for the acquisition of cardiovascular parameters of the body (14) and a control device (15) in communication with the parameter acquisition devices (13) for synchronizing the imaging, wherein the control device (15) is adapted to analyse the data of at least two parameter acquisition devices (13) and to output a control signal based on the analysis.
Höhere Mathematik kompakt
(2013)
Innovation und Kommunikation
(2013)
Digitale Mobilfunksysteme
(2013)
Der Telekommunikationsmarkt erfährt substanzielle Veränderungen. Neue Geschäftsmodelle, innovative Dienstleistungen und Technologien erfordern Reengineering, Transformation und Prozessstandardisierung. Mit der Enhanced Telecom Operation Map (eTOM) bietet das TM Forum ein international anerkanntes de facto Referenz-Prozess-Framework basierend auf spezifischen Anforderungen und Ausprägungen der Telekommunikationsindustrie an. Allerdings enthält dieses Referenz-Framework nur eine hierarchische Sammlung von Prozessen auf unterschiedlichen Abstraktionsebenen. Eine Kontrollsicht verstanden als sequenzielle Anordnung von Aktivitäten und daraus resultierend ein realer Prozessablauf fehlt ebenso wie eine Ende-zu-Ende-Sicht auf den Kunden. In diesem Artikel erweitern wir das eTOM-Referenzmodell durch Referenzprozessabläufe, in welchen wir das Wissen über Prozesse in Telekommunikationsunternehmen abstrahieren und generalisieren. Durch die Referenzprozessabläufe werden Unternehmen bei dem strukturierten und transparenten (Re-)Design ihrer Prozesse unterstützt. Wir demonstrieren die Anwendbarkeit und Nützlichkeit unserer Referenzprozessabläufe in zwei Fallstudien und evaluieren diese anhand von Kriterien für die Bewertung von Referenzmodellen. Die Referenzprozessabläufe wurden vom TM Forum in den Standard aufgenommen und als Teil von eTOM Version 9 veröffentlicht. Darüber hinaus diskutieren wir die Komponenten unseres Ansatzes, die auch außerhalb der Telekommunikationsindustrie angewandt werden können.
Die Telekommunikationsindustrie hat in den letzten Jahrzehnten einen enormen Wandel vollzogen. Für Telekommunikationsunternehmen erfordert dies fundamentale Umstrukturierungen von Strategie, Prozessen, Anwendungssystemen und Netzwerktechnologien. Dabei spielen Unternehmensarchitekturen und Referenzmodelle eine wichtige Rolle. Zwar existieren in der Praxis anerkannte Referenzmodelle, aber wie sind diese für eine systematische Transformation zu gestalten? Wie sieht eine konkrete Lösung für die Telekommunikationsindustrie aus?
Als Antwort stellt Christian Czarnecki in seinem Buch eine referenzmodellbasierte Unternehmensarchitektur vor. Basierend auf einer umfangreichen Untersuchung von Transformationsprojekten werden Probleme und Anforderungen der Praxis identifiziert, für die mit Methoden der Unternehmenstransformation, Referenzmodellierung und Unternehmensarchitektur ein Lösungsvorschlag entwickelt und evaluiert wird. Dieser besteht u. a. aus detaillierten Anwendungsfällen, Referenzprozessabläufen, einer Zuordnung von Prozessen zu Anwendungssystemen sowie Handlungsempfehlungen zur Virtualisierung.
Für Wissenschaftler und Studierende der Wirtschaftsinformatik zeigt das Buch neue Erkenntnisse einer anwendungsorientierten Referenzmodellierung. Für Praktiker liefert es eine methodisch fundierte Lösung für die aktuellen Transformationsbedarfe der Telekommunikationsindustrie. Christian Czarnecki arbeitet seit 2004 als Unternehmensberater und hat viele Telekommunikationsunternehmen bei deren Transformation begleitet. In 2013 erfolgte die Promotion zum Doktoringenieur an der Otto-von-Guericke-Universität Magdeburg.
Many biped robots deploy a form of gait that follows the zero moment point (ZMP) approach, that is, the robot is in a stable position at any point in time. This requires the robot to be fully actuated. While very stable, the draw-backs of this approach are a fairly slow gait and high energy consumption. An alternative approach is the so-called passive-dynamic walking, where the gait makes use of the inertia and dynamic stability of the robot. In this paper we describe our ongoing work of combining the principles of passive-dynamic walking on the fully-actuated biped robot Nao, which is also deployed for robotic soccer applications. We present a simple controller that allows the robot to stably rock sidewards, showing a closed limit-cycle. We discuss first results of superimposing a forward motion on the sidewards motion. Based on this we expect to endow the Nao with a fast, robust, and stable passive-dynamic walk on the fully-actuated Nao in the future.
Erfolgreiches IT-Marketing
(2013)
We have developed a double-tuned ¹H/¹⁹F birdcage resonator dedicated for hand and wrist imaging at 7 T to locally image non-steroidal anti-inflammatory drugs (NSAID) such as 2-{[3-(Trifluoromethyl) phenyl]amino}benzoic acid. The preliminary in vivo images acquired by the double-tuned ¹H/¹⁹F birdcage resonator demonstrate the feasibility for ¹H/¹⁹F hand- and wrist-imaging at 7 T. While the diagnostic quality of the coil needs to be assessed in patients with inflammatory rheumatoid disease, first ¹⁹F images of the NSAID are encouraging, and point towards the prospect of applying ¹⁹F-MRI to visualize and quantify the concentration of therapeutically-active compound at the sites of inflammation.