Performance limitations of subband adaptive filters

In this paper, we evaluate the performance limitations of subband adaptive filters in terms of achievable final error terms. The limiting factors are the aliasing level in the subbands, which poses a distortion and thus presents a lower bound for the minimum mean squared error in each subband, and the distortion function of the overall filter bank, which in a system identification setup restricts the accuracy of the equivalent fullband model. Using a generalized DFT modulated filter bank for the subband decomposition, both errors can be stated in terms of the underlying prototype filter. If a source model for coloured input signals is available, it is also possible to calculate the power spectral densities in both subbands and reconstructed fullband. The predicted limits of error quantities compare favourably with simulations presented

Interaktionen zwischen Anbaubedingungen, Pilzbefall, Backqualität und Mykotoxinbelastung in der ökologischen Weizenproduktion

1. Feldversuche Die Winterweizensorten Arina und Capo wurden im Versuchsjahr 2002/2003 auf insgesamt 12 Standorten im Ökologischen Anbau als Reinbestände und als Sortenmischung angebaut. Das Versuchsjahr war extrem trocken, weshalb kein relevanter Krankheitsbefall zu verzeichnen war. Die Erträge variierten je nach Standort von 26 bis 53 dt/ha wobei Capo deutlich ertragsstärker war als Arina. Die Mischung brachte im Schnitt 3% mehr Ertrag als erwartet und war im Ertrag deutlich stabiler. Dies war auf die stärkere Konkurrenzkraft der Sorte Capo an fast allen Standorten zurückzuführen. Arina übertraf Capo signifikant im Rohprotein (RP) (12.9 versus 12.2%) und Feuchtklebergehalt (FK) (29.8 versus 25.3%), was auch im Backvolumen reflektiert wurde. Während bei Arina RP und FK mit dem Backvolumen mittelmäßig korrelierten (R2=0.45), bestand keinerlei Zusammenhang zwischen diesen Parametern bei Capo. Im Gegensatz dazu war der Zusammenhang in der Mischung so stark wie bei Arina. Die Mischung verhielt sich insgesamt wie erwartet, konnte aber stärker von verbesserten Standortbedingungen profitieren als die beiden Einzelsorten. In einem Exaktversuch wurden 8 Sorten und 12 Mischungen auf Ertrag und Backqualität nach zwei Vorfrüchten getestet. Wie in den Praxisversuchen entsprachen die Mischungen den Erwartungen oder übertrafen sie leicht, aber nicht signifikant. Die Ergebnisse legen nahe, dass Sortenmischungen mindestens so gut, wenn nicht besser zur Erzeugung von Qualitätsweizen geeignet sind. . 2. Serologischer Fusarien- und Mykotoxinnachweis Serologische Testmethoden, die bereits erfolgreich für die Bewertung der Resistenz von Getreidegenotypen nach künstlicher Inokulation mit Fusarium-Isolaten eingesetzt werden konnten, wurden für die Prüfung von insgesamt 164 Weizenproben aus dem Ökoanbau angewandt. Die Untersuchungen ergaben einen insgesamt sehr geringen Fusarium-Befall. Der Gehalt an Fusarium-Exoantigenen (ExoAg) sowie die Kontamination mit den Mykotoxinen DON und ZEA lagen bei den untersuchten Proben in der Regel unterhalb der Nachweisgrenzen der jeweiligen Testsysteme. Eine Analyse der in Weizenkörner nachweisbaren Antigene ergab, dass es sich hierbei hauptsächlich um glykosilierte Proteine handelt, die infolge eines Befalls mit Fusarium-Arten gebildet werden. Für den Nachweis von Mykotoxinen können die Testsysteme „Ridascreen DON“ und "Ridascreen Zearalenon“ empfohlen werden

Reheating in the Presence of Inhomogeneous Noise

Explosive particle production due to parametric resonance is a crucial feature of reheating in an inflationary cosmology. Coherent oscillations of the inflaton field lead to a periodically varying mass in the evolution equation of matter and gravitational fluctuations and often induce a parametric resonance instability. In a previous paper (hep-ph/9709273) it was shown that homogeneous (i.e. space independent) noise leads to an increase of the generalized Floquet exponent for all modes, at least if the noise is temporally uncorrelated. Here we extend the results to the physically more realistic case of spatially inhomogeneous noise. We demonstrate - modulo some mathematical fine points which are addressed in a companion paper - that the Floquet exponent is a non- decreasing function of the amplitude of the noise. We provide numerical evidence for an even stronger statement, namely that in the presence of inhomogeneous noise, the Floquet exponent of each mode is larger than the maximal Floquet exponent of the system in the absence of noise.Comment: 21 pages, 4 figure

Pancreatitis with an unusual fatal complication following endoscopic retrograde cholangiopancreaticography: a case report

<p>Abstract</p> <p>Introduction</p> <p>Endoscopic retrograde cholangiopancreaticography has been the treatment of choice for stones in the common bile duct. Although the procedure is usually safe, procedure-related complications do occur.</p> <p>Case presentation</p> <p>A case of pancreatitis following endoscopic retrograde cholangiopancreaticography is described in a 55-year-old woman. After an uneventful recovery the patient's condition deteriorated rapidly 16 days after the endoscopic retrograde cholangiopancreaticography, and the patient died within 1 hour. Post-mortem examination revealed massive intrapulmonary fat embolism. The complications of endoscopic retrograde cholangiopancreaticography and pancreatitis are described.</p> <p>Conclusion</p> <p>Fat embolism can occur after the remission of pancreatitis and pancreatic necrosis may be overlooked on contrast-enhanced computed tomography scanning.</p

Amphibious Seismic Survey Images Plate Interface at 1960 Chile Earthquake

The southern central Chilean margin at the site of the largest historically recorded earthquake in the Valdivia region, in 1960 (Mw = 9.5), is part of the 5000-km-long active subduction system whose geodynamic evolution is controversially debated and poorly understood. Covering the area between 36° and 40°S, the oceanic crust is segmented by prominent fracture zones. The offshore forearc and its onshore continuation show a complex image with segments of varying geophysical character, and several fault systems active during the past 24 m.y. In autumn 2001, the project SPOC was organized to study the Subduction Processes Off Chile, with a focus on the seismogenic coupling zone and the forearc. The acquired seismic data crossing the Chilean subduction system were gathered in a combined offshore-onshore survey and provide new insights into the lithospheric structure and evolution of active margins with insignificant frontal accretion

In vitro synthesis of heparosan using recombinant Pasteurella multocida heparosan synthase PmHS2

In vertebrates and bacteria, heparosan the precursor of heparin is synthesized by glycosyltransferases via the stepwise addition of UDP-N-acetylglucosamine and UDP-glucuronic acid. As heparin-like molecules represent a great interest in the pharmaceutical area, the cryptic Pasteurella multocida heparosan synthase PmHS2 found to catalyze heparosan synthesis using substrate analogs has been studied. In this paper, we report an efficient way to purify PmHS2 and to maintain its activity stable during 6 months storage at −80 °C using His-tag purification and a desalting step. In the presence of 1 mM of each nucleotide sugar, purified PmHS2 synthesized polymers up to an average molecular weight of 130 kDa. With 5 mM of UDP-GlcUA and 5 mM of UDP-GlcNAc, an optimal specific activity, from 3 to 6 h of incubation, was found to be about 0.145 nmol/μg/min, and polymers up to an average of 102 kDa were synthesized in 24 h. In this study, we show that the chain length distribution of heparosan polymers can be controlled by change of the initial nucleotide sugar concentration. It was observed that low substrate concentration favors the formation of high molecular weight heparosan polymer with a low polydispersity while high substrate concentration did the opposite. Similarities in the polymerization mechanism between PmHS2, PmHS1, and PmHAS are discussed

Slow Dissociation of a Charged Ligand: Analysis of the Primary Quinone QA Site of Photosynthetic Bacterial Reaction Centers

Reaction centers (RCs) are integral membrane proteins that undergo a series of electron transfer reactions during the process of photosynthesis. In the QA site of RCs from Rhodobacter sphaeroides, ubiquinone-10 is reduced, by a single electron transfer, to its semiquinone. The neutral quinone and anionic semiquinone have similar affinities, which is required for correct in situ reaction thermodynamics. A previous study showed that despite similar affinities, anionic quinones associate and dissociate from the QA site at rates ≈104 times slower than neutral quinones indicating that anionic quinones encounter larger binding barriers (Madeo, J.; Gunner, M. R. Modeling binding kinetics at the QA site in bacterial reaction centers. Biochemistry2005, 44, 10994–11004). The present study investigates these barriers computationally, using steered molecular dynamics (SMD) to model the unbinding of neutral ground state ubiquinone (UQ) and its reduced anionic semiquinone (SQ–) from the QA site. In agreement with experiment, the SMD unbinding barrier for SQ– is larger than for UQ. Multi Conformational Continuum Electrostatics (MCCE), used here to calculate the binding energy, shows that SQ– and UQ have comparable affinities. In the QA site, there are stronger binding interactions for SQ– compared to UQ, especially electrostatic attraction to a bound non-heme Fe2+. These interactions compensate for the higher SQ– desolvation penalty, allowing both redox states to have similar affinities. These additional interactions also increase the dissociation barrier for SQ– relative to UQ. Thus, the slower SQ– dissociation rate is a direct physical consequence of the additional binding interactions required to achieve a QA site affinity similar to that of UQ. By a similar mechanism, the slower association rate is caused by stronger interactions between SQ– and the polar solvent. Thus, stronger interactions for both the unbound and bound states of charged and highly polar ligands can slow their binding kinetics without a conformational gate. Implications of this for other systems are discussed

Kissing G Domains of MnmE Monitored by X-Ray Crystallography and Pulse Electron Paramagnetic Resonance Spectroscopy

The authors of this research article demonstrate the nature of the conformational changes MnmE was previously suggested to undergo during its GTPase cycle, and show the nucleotide-dependent dynamic movements of the G domains around two swivel positions relative to the rest of the protein. These movements are of crucial importance for understanding the mechanistic principles of this GAD