M-mode photoacoustic particle flow imaging

Recently, there has been growing interest in the development of photoacoustic flow measuring methods aimed to study microvascular blood flow in biological tissue. Here, we describe the M-mode photoacoustic particle flow imaging, using an optical resolution photoacoustic microscope equipped with a high-repetition-rate pulsed dye laser. We studied the flow of a diluted dyed particle suspension in a small tube embedded in a nonscattering medium as well as in a scattering medium simulating biological tissue. Potentially, the method can be applied to detect the flow speed of single red blood cells in a capillary

Unitarily localizable entanglement of Gaussian states

We consider generic $m\times n$-mode bipartitions of continuous variable systems, and study the associated bisymmetric multimode Gaussian states. They are defined as $(m+n)$-mode Gaussian states invariant under local mode permutations on the $m$-mode and $n$-mode subsystems. We prove that such states are equivalent, under local unitary transformations, to the tensor product of a two-mode state and of $m+n-2$ uncorrelated single-mode states. The entanglement between the $m$-mode and the $n$-mode blocks can then be completely concentrated on a single pair of modes by means of local unitary operations alone. This result allows to prove that the PPT (positivity of the partial transpose) condition is necessary and sufficient for the separability of $(m + n)$-mode bisymmetric Gaussian states. We determine exactly their negativity and identify a subset of bisymmetric states whose multimode entanglement of formation can be computed analytically. We consider explicit examples of pure and mixed bisymmetric states and study their entanglement scaling with the number of modes.Comment: 10 pages, 2 figure

Comparison of 2D versus M-mode echocardiography for assessing fetal myocardial wall thickness

OBJECTIVE: M-mode and 2D have been proposed for evaluating fetal myocardial thickness. However, studies comparing the performance of both modalities are lacking. We aimed to compare 2D versus M-mode reproducibility for assessing myocardial wall thicknesses. METHODS: A prospective study including 45 healthy fetuses from low-risk pregnancies evaluated between 18 and 41 weeks of gestation. Left and right ventricular free-wall and septal myocardial thicknesses were measured at end-diastole (ED) and end-systole (ES) in transverse 4-chamber view using 2D and M-mode. Intra- and interobserver reproducibility was evaluated by the concordance correlation coefficient (CCC). Both techniques were compared by t-test of the CCC. RESULTS: 2D and M-mode demonstrated excellent and similar intraobserver repeatability, with the best concordance in ES septal thickness (M-mode CCC 0.956 versus 2D-mode CCC 0.914). Interobserver reproducibility demonstrated also a high concordance, optimal in ES left ventricular free wall (M-mode 0.925 versus 2 D 0.855). Comparison of both techniques demonstrated a high concordance in all measurements, except for ED septal thickness with better reproducibility using M-mode (CCC 0.954 versus 0.847, p = .017). CONCLUSIONS: 2D and M-mode can be used in a reproducible manner for measuring fetal myocardial thickness, with a slightly better performance of M-mode for assessing ED septal wall thickness

The Radio Sky at Meter Wavelengths: m-Mode Analysis Imaging with the Owens Valley Long Wavelength Array

A host of new low-frequency radio telescopes seek to measure the 21-cm transition of neutral hydrogen from the early universe. These telescopes have the potential to directly probe star and galaxy formation at redshifts $20 \gtrsim z \gtrsim 7$, but are limited by the dynamic range they can achieve against foreground sources of low-frequency radio emission. Consequently, there is a growing demand for modern, high-fidelity maps of the sky at frequencies below 200 MHz for use in foreground modeling and removal. We describe a new widefield imaging technique for drift-scanning interferometers, Tikhonov-regularized $m$-mode analysis imaging. This technique constructs images of the entire sky in a single synthesis imaging step with exact treatment of widefield effects. We describe how the CLEAN algorithm can be adapted to deconvolve maps generated by $m$-mode analysis imaging. We demonstrate Tikhonov-regularized $m$-mode analysis imaging using the Owens Valley Long Wavelength Array (OVRO-LWA) by generating 8 new maps of the sky north of $\delta=-30^\circ$ with 15 arcmin angular resolution, at frequencies evenly spaced between 36.528 MHz and 73.152 MHz, and $\sim$800 mJy/beam thermal noise. These maps are a 10-fold improvement in angular resolution over existing full-sky maps at comparable frequencies, which have angular resolutions $\ge 2^\circ$. Each map is constructed exclusively from interferometric observations and does not represent the globally averaged sky brightness. Future improvements will incorporate total power radiometry, improved thermal noise, and improved angular resolution -- due to the planned expansion of the OVRO-LWA to 2.6 km baselines. These maps serve as a first step on the path to the use of more sophisticated foreground filters in 21-cm cosmology incorporating the measured angular and frequency structure of all foreground contaminants.Comment: 27 pages, 18 figure

The applicability of the anatomical M-mode in comparison with conventional methods of equine echocardiography

Deckblatt-Impressum persönlicher Dank Inhaltsverzeichnis Abkürzungsverzeichnis Abbildungsverzeichnis Diagrammverzeichnis Tabellenverzeichnis Einleitung Literaturübersicht Material und Methoden Ergebnisse Diskussion Zusammenfassung Summary Literaturverzeichnis Anhang Danksagung Lebenslauf SelbständigkeitserklärungIn der vorliegenden Studie wurden 34 Warmblutpferde echokardiographisch mittels B-Mode, konventionellem M-Mode, sowie Farb- und Spektraldoppler untersucht. Im Anschluss daran wurden aus digital gespeicherten B-Mode Filmsequenzen das anatomische M-Mode erstellt. Nach dem Ergebnis der klinischen Untersuchung konnten 28 Pferde in drei Gruppen eingeteilt werden. Die Gruppe 1 (n=10) beinhaltete klinisch und kardiologisch unauffällige Probanden. Die Gruppe 2 (n=11) umfasste Patienten mit einem Herzgeräusch von mindestens Grad II/VI ohne messbare Vergrößerung des linken Atriums oder des linken Ventrikels. In der Gruppe 3 (n=7) wurden Patienten zusammengefasst, die sowohl ein Herzgeräusch von mindestens Grad II/VI und Vergrößerungen der genannten Herzkompartimente aufzeigten. Die Einteilung der Patienten in die Gruppen 2 und 3 erfolgte nach dem echokardiographisch ermittelten Durchmesser des linken Vorhofes sowie dem Durchmesser des linken Ventrikels unterhalb der Mitralklappe gemessen aus der rechten kaudalen langen Achse. Die Probanden der Einzelfalldarstellungen (n=6) wiesen ein Vorhofflimmern auf und wurden aus diesem Grund keiner Gruppn zugeteilt. Die myokardiale Verkürzungsfraktion (fractional shortening, FS%) sowie weitere Herzdimensionen wurden aus vier unterschiedlichen Schnittebenen jeweils mittels B-Mode, konventionellem M-Mode und anatomischem M-Mode bestimmt. Dabei wurden folgende Ebenen verwendet: \- rechte kaudale lange Achse unterhalb der Mitralklappe \- rechte kaudale lange Achse im Bereich der Papillarmuskeln \- rechte kaudale kurze Achse unterhalb der Mitralklappe \- rechte kaudale kurze Achse im Bereich der Papillarmuskeln Ziel dieser Arbeit war die Überprüfung der Anwendbarkeit des anatomischen M-Mode als Messverfahren in der Echokardiographie beim Pferd. Darüber hinaus sollten die Schnittebenen des M-Mode zur Ermittlung der myokardialen Verkürzungsfraktion präzisiert werden. Die aus dem B-Mode ermittelten Parameter lagen jenen des anatomischen M-Mode näher als jenen des konventionellen M-Mode. Der im anatomischen M-Mode frei bewegliche artifizielle Cursor ermöglichte in jedem Fall das orthogonale Schneiden der betreffenden Herzstrukturen, so dass die Ebenen jenen des B-Mode entsprachen. Im konventionellen M-Mode war dieser Vorgang nicht beständig durchzuführen. Eine Streuung der Messwerte der myokardialen Verkürzungsfraktion ist aufgrund der anatomischen Gegebenheiten der intrakardialen Orientierungsstrukturen zu erwarten. Zusammenfassend konnte mit Hilfe dieser Studie gezeigt werden, dass das anatomische M-Mode in der Echokardiographie beim Pferd einsetzbar ist und zahlreiche Vorteile aufweist. Die im anatomischen M-Mode ermittelten linksventrikulären Dimensionen sind mit Referenzwerten aus dem B-Mode und konventionellen M-Mode vergleichbar. Das anatomische M-Mode kann somit das konventionelle M-Mode ersetzen. Da es sich um ein Nachbearbeitungsverfahren aus dem B-Mode handelt, verkürzt sich die Untersuchungsdauer für das Pferd erheblich.In this study an ultrasound examination of the heart using two-dimensional B-mode, conventional M-mode and doppler echocardiography was performed in 34 warm-blood horses. Anatomical M-mode images were obtained by digital reconstruction from two-dimensional cineloops. 28 horses were devided into three groups according to the results of the examinations. The controlgroup (n=10) did not show clinical signs of heart disease. The second group (n=11) consisted of horses with heart murmurs grade II/VI but without alteration of cardiac dimensions. In the third group (n=7) horses with heart murmurs and with cardiac dilatation were combined. The classification into group two and three was based on left atrium diameters and left ventricle diameters immediately below the mitral valve measured in right caudal long axis view. The remaining six patients showed signs of atrial fibrillation and are documented as case studies. Fractional shortening (FS%) and other heart dimensions were determinded by using four image planes: \- right caudal long axis view below the mitral valve \- right caudal long axis view in the region of papillary muscles \- right caudal short axis view below the mitral valve \- right caudal short axis view in the region of papillary muscles The aim of this study was to test the feasibility of the anatomical M-mode as a useful tool in equine cardiology. In addition the accurancy of scan-planes in the M-mode to get FS% reference ranges with lower variability should be improved. Results obtained by using the B-mode technique had higher degree of correlation with those of the anatomical M-mode than with these of the conventional M-mode. The artificial cursor of the anatomical M-mode allowed free orientation within the two-dimensional sector. Orthogonal scan-planes of the heart structures could be created with scan-planes equalling these of the B-mode by using this cursor. As a result perfect alignement with the target structure could be achieved by using the M-mode technique. This was not always practicable with conventional M-mode. The variability of FS% could not be reduced because of intraindividual variation of the intracardiac landmarks. This study showed anatomical M-mode to be feasible for cardiology in horses with parameters measured in anatomical M-mode correlating very closely to those measured in B-mode and conventional M-mode. Since the anatomical M-mode is a postprocessing of a two-dimensional B-mode cineloop using only B-Mode could shorten the time of echocardiographic examination

A-dip of the aortic valve by M-mode echocardiography

We present a case with the previously unreported finding of an a-dip in the M-mode tracing of the aortic valve. An a-dip is commonly seen in the M-mode tracing of the pulmonic valve motion, and represents near equalization of pulmonary artery and right ventricular end- -diastolic pressures during atrial contraction. M-mode echocardiography has become an ancillary study to the basic two-dimensional examination, but can often convey important features of cardiac hemodynamics quite elegantly, as the present case demonstrates