The effect of biphasic waveform tilt in transvenous atrial defibrillation

Atrial defibrillation can be accomplished using low energy shocks and transvenous catheters. The biphasic waveform tilt required to achieve optimal atrial defibrillation thresholds (ADFTs) is, however, not known. The effect of single capacitor biphasic waveform tilt modification on ADFT was assessed in 20 patients. Following AF induction the defibrillation pulses were delivered between the catheters positioned in the coronary sinus and the right atrium. The single capacitor biphasic waveform shocks, delivered over the same pathways, consisted of 65% tilt (65/65 biphasic waveform) to produce an overall tilt of 88%, or 50% tilt (50/50 biphasic waveform) to produce an overall tilt of 75%. Although 65/65 biphasic waveform delivers more energy, the shorter duration 50/50 biphasic waveform reduced stored energy ADFT 21%, from 1.34 +/- 0.82 J with 65/65 biphasic to 1.06 +/- 0.81 J. These differences were not statistically significant. Nine patients had lower ADFT with 50/50 biphasic waveform while five patients had lower ADFT with 65/65 biphasic waveform. Equivalent reduction in ADFT was seen in the remaining six patients. The ADFT was 0.83 +/- 0.65 J when both tilts were considered. In conclusion, biphasic waveform tilt modification may affect the ADFT in an individual patient. The optimal biphasic waveform for ADFT is not known.     

Physical Properties Important to Electrostatic and Non electrostatic Powder Transfer Efficiency in a Tumble Drum

ABSTRACT: Popcorn was oiled and coated in a tumble drum nonelectrostatically and electrostatically with sugar, cornstarch, salt, cellulose, maltodextrin, all-purpose flour, whole-wheat flour, or soy flour. Particle size, density, flowability, and chargeability were correlated to transfer efficiency using regression analysis. Of the various methods to measure chargeability, charge-to-mass and adhesion improvement were the most significant. For nonelectrostatic coating, small, dense, free-flowing powders were most efficient. Small, free-flowing highly charging powders were most efficient for electrostatic coating. Percent improvement was the highest for the least efficient powders. The greatest benefit with electrostatic coating was for low density, highly charging powders with no effect of size.     

Six sigma for software

Six Sigma concepts are increasingly penetrating software engineering literature and practice. But exactly what Six Sigma is and how you apply its concepts remains unclear. To make sense of the Six Sigma movement, this paper looks back to the origins and implications of its dominant predecessor, total quality management.     

Variationsprinzipe für allgemeine elektromagnetische Felder in ruhenden Medien

Contents For general electromagnetic fields in nonmoving media variational principles for the approximativ solution of boundary- and eigenvalue problems are developed in consideration of the asymptotic behavior at infinity. To deal with the lossy case adjoint fields are introduced. As regards the practical calculations for the approximativ solution by means of test fields the essential and natural conditions are shown. In addition to general radiation problems waveguide problems are considered.

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Variationsprinzipe für allgemeine elektromagnetische Felder in ruhenden Medien

Übersicht Für allgemeine elektromagnetische Felder in ruhenden Medien werden unter Berücksichtigung des asymptotischen Verhaltens im Unendlichen Variationsprinzipe entwickelt zur näherungsweisen Lösung von Rand- und Eigenwertproblemen. Zur Behandlung des verlustbehafteten Falles wird der Begriff des adjungierten Feldes eingeführt. Im Hinblick auf die praktische Durchführung der Näherungsrechnung mit Hilfe von Vergleichsfeldern wird gezeigt, welche Bedingungen jeweils wesentlich und welche natürlich sind. Neben allgemeinen Ausstrahlungsproblemen wird auf Wellenleiterprobleme eingegangen.

     

Ver?nderungen der subcellul?ren Struktur in Keimbl?ttern von Kakaosamen (Theobroma cacao L.) w?hrend der Fermentation und Troeknung

Zusammenfassung Während die Chemie der Kakaofermentation intensiv untersucht werden ist, fehlen Kenutnisse über die subcelluläre Struktur des Kakaosamens. Die Bedeutung der Fermentation für die Aromabildung beim Rösten wind allgemein mit der Bildung von Aromavorstufen erklärt. Strukturveränderungen im subcellulären Bereich können jedoch ebenfalls Bedeutung haben, weil aufgrund der Kompartimentierung in der lebenden Zelle Reaktionspartner voneinander getrennt sein können, deren Mischung Voraussetzung für ihre Reaktion ist. Die subcelluläre Struktur im Mesophyll der Kotyledonen aus reifen Samen wurde elektronenmikroskopisch untersucht und ihre Veränderungen durch Trocknung und Fermentation beschrieben. Hierzu wurden Gefrierätzpräparate und Ultradünnschnitte fixierter, entwässerter und in Kunstharz eingebetteter Objekte verwendet. Beide Präparationsmethoden bestätigen die Befunde: In unfermentierten Samen bildet das Fett trotz seiner großen Menge die disperse Phase. Es ist in Form zahlreicher, aber stets voneinander isolierter Vacuolen im restlichen Cytoplasma eingebettet. Dieses bildet die geschlossene hydrophile Phase. Es enthält Zellkern, Mitochondrien, Amyloplasten und Aleuronvacuolen. Das Grundplasma umgibt diese und die Lipidvacuolen als dünnes Netz. Sowohl durch bloße Trocknung bei Zimmertemperatur als auch durch Fermentation (ohne Trocknung) fusionieren die Lipidvacuolen und schließen darn als geschlossene lipophile Phase die hydrophilen Plasmaanteile als disperse Phase ein. Nach Fermentation werden Kompartimentierungen in hydrophilen Einschlüssen nicht mehr gefunden, nach bloßer Trocknung konnen sie dagegen erhalten bleiben, so daß der Stoffaustausch verhindert wird. Im Rohkakao des Handels lassen sich besonders hinsichtlich der Polyphenolspeicherzellen in violett-kompakten und braunbrüchigen Bohren Unterschiede nachweisen. Die Ergebnisse werden im Zusammenhang mit dem Fermentationsprozeß und den Voraussetzungen für die Aromabildung diskutiert.

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Changes in subcellular structures in the cotyledons of cocoa seeds (Theobroma cacau L.) during fermentation and drying

Summary In contrast to extensive investigations on chemical changes there is a lack of knowledge about subcellular structure and its changes in cocoa seeds during fermentation. The fact, that no chocolate flavour develops on roasting without foregoing fermentation generally is believed to be due to the formation of flavour precursors during fermentation. However, structural changes on a subcellular level may be important as well. Mixing of compounds located in different compartments of the living cell, may be a premise to aroma forming reactions. — The subcellular structure in the mesophyll of cotyledons from ripe seeds have been investigated by electron microscopy. Structural changes during drying and fermentation are described. Freeze edgings and thin sections of fixed and dehydrated tissues, embedded in synthetic resin have been prepared. Both methods state the following results: In spite of its high amount, fat forms the dispers phase in unfermented seeds. Numerous, individual lipid vacuoles (1–3 m) are tightly packed without fusion. They are enclosed within the remaining cytoplasm. The groundplasm is restricted to a thin coat surrounding nucleus, mitochondria, amyloplasts and aleuron between the lipid vacuoles. Both, during drying of unfermented seeds at 21–27° C and during fermentation, the lipid vacuoles fuse and ultimately form the continuous lipophlic phase surrounding the hydrophilic parts of plasm as the disperse phase. After fermentation no compartmentation can be found within the hydrophilic inclusions. However, after drying of unfermented seeds, compartmentation is frequently found to be preserved. This implies prevention of exchange between different hydrophilic inclusions. In raw cocoa from the market, in addition, differences of the structure of polyphenol storage cells in purple and brown beans have been found. — The results are discussed in view of processing and the formation of flavour.