bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zeeman‐Doppler imaging of late‐type stars: The surface magnetic field of II Peg
Authors: Carroll T. A. , Kopf M. , Ilyin I. , Strassmeier K. G. 
Published: December 2007

AbstractLate‐type stars in general possess complicated magnetic surface fields which makes their detection and in particular their modeling and reconstruction challenging. In this work we present a new Zeeman‐Doppler imaging code which is especially designed for the application to late‐type stars. This code uses a new multi‐line cross‐correlation technique by means of a principal component analysis to extract and enhance the quality of individual polarized line profiles. It implements the full polarized radiative transfer equation and uses an inversion strategy that can incorporate prior knowledge based on solar analogies. Moreover, our code utilizes a new regularization scheme which is based on local maximum entropy to allow a more appropriate reproduction of complex surface fields as those expected for late‐type stars. In a first application we present Zeeman‐Doppler images of II Pegasi which reveal a surprisingly large scale surface structure with one predominant (unipolar) magnetic longitude which is mainly radially oriented. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Search for relationship between duration of the extended solar cycles and amplitude of sunspot cycle
Authors: Tlatov A.G. 
Published: December 2007

AbstractDuration of the extended solar cycles is taken into the consideration. The beginning of cycles is counted from the moment of polarity reversal of large‐scale magnetic field in high latitudes, occurring in the sunspot cycle n till the minimum of the cycle n + 2. The connection between cycle duration and its amplitude is established. Duration of the “latent” period of evolution of extended cycle between reversals and a minimum of the current sunspot cycle is entered. It is shown, that the latent period of cycles evolution is connected with the next sunspot cycle amplitude and can be used for the prognosis of a level and time of a sunspot maximum. The 24th activity cycle prognosis is made. The found dependences correspond to transport dynamo model of generation of solar cyclicity, it is possible with various speed of meridional circulation. Long‐term behavior of extended cycle's lengths and connection with change of a climate of the Earth is considered. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
3‐D non‐linear evolution of a magnetic flux tube in a spherical shell: The isentropic case
Authors: Jouve L. , Brun A.S. 
Published: December 2007

AbstractWe present recent 3‐D MHD numerical simulations of the non‐linear dynamical evolution of magnetic flux tubes in an adiabatically stratified convection zone in spherical geometry, using the anelastic spherical harmonic (ASH) code.We seek to understand the mechanism of emergence of strong toroidal fields from the base of the solar convection zone to the solar surface as active regions. We confirm the results obtained in cartesian geometry that flux tubes that are not twisted split into two counter vortices before reaching the top of the convection zone. Moreover, we find that twisted tubes undergo the poleward‐slip instability due to an unbalanced magnetic curvature force which gives the tube a poleward motion both in the non‐rotating and in the rotating case. This poleward drift is found to be more pronounced on tubes originally located at high latitudes. Finally, rotation is found to decrease the rise velocity of the flux tubes through the convection zone, especially when the tube is introduced at low latitudes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimentelle und numerische Untersuchungen zum Brandverhalten von Brettsperrholzplatten
Authors: Frangi Andrea , Fontana Mario , Bochicchio Giovanna 
Published: December 2007

AbstractBrettsperrholzplatten stellen ein technisch und wirtschaftlich interessantes Produkt für den “modernen” Massivholzbau dar und finden in den letzten Jahren einen vermehrten Einsatz als großformatige Wand‐ und Deckenelemente im Wohnungsbau. Im Rahmen von zwei am Institut für Baustatik und Konstruktion der ETH Zürich und am Institut CNR‐IVALSA in San Michele all'Adige, Italien, laufenden Forschungsprojekten wurde das Brandverhalten von Brettsperrholzplatten mit mehreren experimentellen und numerischen Untersuchungen analysiert. Der vorliegende Artikel stellt die brandschutztechnisch relevanten Erkenntnisse aus den Untersuchungen dar und analysiert die grundsätzliche Fragestellung, ob sich im Brandfall Brettsperrholzplatten ähnlich wie Vollholzplatten verhalten. Die durchgeführten Untersuchungen haben gezeigt, dass das Brandverhalten von Brettsperrholzplatten durch das Verhalten der einzelnen Bretterlagen charakterisiert ist. Falls sich die einzelnen verkohlten Schichten frühzeitig ablösen, geht die Schutzwirkung der sich bildenden Holzkohleschicht verloren. Nach der Verkohlung und dem Abfallen jeder einzelnen Schicht ist in diesem Fall wegen der steigenden Brandraumtemperatur mit einem erhöhten Abbrand zu rechnen, ähnlich wie für geschützte Holzbauteile nach dem Versagen der Brandschutzbekleidung. Das Brandverhalten von Brettsperrholzplatten kann somit durch die Plattenschichtigkeit und die Dicke der einzelnen Schichten stark beeinflusst werden. Das Ablösen der Holzkohleschicht könnte für horizontale Bauteile (Decken) kritischer sein als für vertikale Bauteile (Wände).
Fluorescence quenching method for the determination of bleomycins A5 and A2 with halofluorescein dyes
Authors: Liu Jiangtao , Liu Zhongfang , Hu Xiaoli , Kong Ling , Liu Shaopu 
Published: December 2007

AbstractIn weak acidic medium, the anticancer antibiotics bleomycin A5 (BLMA5) and bleomycin A2 (BLMA2) bind with halofluorescein dyes, such as erythrosin (Ery), eosin Y (EY) and eosin B (EB), to form ion‐association complexes, which causes fluorescence quenching of halofluorescein dyes. The quenching values (ΔF) are directly in proportional to the concentrations of bleomycins over the range 0.09–2.5 µg/mL. Based on this, a fluorescence quenching method for the determination of BLMA5 and BLMA2 has been developed. The dynamic range is 0.12–2.5 µg/mL for the determination of BLMA5 and 0.09–2.0 µg/mL for BLMA2, with detection limits (3σ) of 0.04 µg/mL for BLMA5, 0.03 µg/mL for BLMA2, respectively. It has been applied to determine the two antibiotics in human serum, urine and rabbit serum samples. The recovery is in the range 90–102%. In this work, the optimum reaction conditions and the spectral characteristics of the fluorescence are investigated. The reasons for fluorescence quenching are discussed, based on the fluorescence theory. Copyright © 2007 John Wiley & Sons, Ltd.
Late morbidity after duodenum-preserving pancreatic head resection with bile duct reinsertion into the resection cavity
Authors: Cataldegirmen G , Bogoevski D , Mann O , Kaifi J T , Izbicki J R , Yekebas E F 
Published: December 2007

Abstract

Background
Reinsertion of the distal common bile duct (CBD) into the pancreatic resection cavity during duodenum-preserving pancreatic head excision (DPPHE) may be an alternative option to Whipple resection or bilioenteric anastomosis when chronic pancreatitis is associated with CBD stenosis.

Methods
Outcome in 82 patients with chronic pancreatitis who underwent DPPHE with CBD reinsertion was compared with that in 432 who had DPPHE without reinsertion and 50 who had a Whipple procedure or pylorus-preserving pancreatoduodenectomy (PPPD).

Results
There were no deaths after DPPHE with CBD reinsertion, compared with four (0·9 per cent) after DPPHE without reinsertion and three (6 per cent) after classical resection. Overall morbidity rates were 30, 28·9 and 36 per cent respectively. Fifteen patients (18 per cent) who had DPPHE with CBD reinsertion developed a stricture at the reinsertion site, compared with a long-term stricture rate of 2·3 per cent (ten patients) after DPPHE without CBD reinsertion and 4 per cent (two patients) after PPPD/Whipple resection.

Conclusion
Although associated with a high incidence of anastomotic stricture, reinsertion of the CBD into the resection cavity as part of DPPHE can be used to preserve duodenal passage and offers an alternative to extended resection for chronic pancreatitis.
Randomized clinical trial evaluating elective laparoscopic appendicectomy for chronic right lower-quadrant pain
Authors: Roumen R M H , Groenendijk R P R , Sloots C E J , Duthoi K E S , Scheltinga M R M , Bruijninckx C M A 
Published: December 2007

Abstract

Background
It is questionable whether elective appendicectomy can effectively reduce persistent or recurrent right lower-quadrant abdominal pain due to chronic or recurrent appendicitis.

Methods
This single-centre double-blind randomized clinical trial studied the effects of elective laparoscopic appendicectomy on pain 6 months after operation in patients with persistent or recurrent lower-quadrant pain. A secondary outcome evaluated was the relationship between clinical response and appendiceal histopathology. The analysis was performed on an intention-to-treat basis.

Results
Forty patients were randomized to laparoscopic appendicectomy (18) or laparoscopic inspection only (22). Postoperative pain scores differed significantly between the groups, favouring appendicectomy (P = 0·005). Relative risk calculations indicated that there was a 2·4 (95 per cent confidence interval (c.i.) 1·3 to 4·0) times greater chance of improvement in pain after laparoscopic appendicectomy. The number needed to treat was 2·2 (95 per cent c.i. 1·5 to 6·5). There was no association between postoperative pain scores and histopathology findings.

Conclusion
Persistent or recurrent lower abdominal pain can be treated by elective appendicectomy with significant pain reduction in properly selected cases. Histopathology may not be abnormal. Registration number: ISRCTN48831122 (http://www.controlled-trials.com).
Exploring the Substrate Specificity of a Mycobacterial Polyprenol Monophosphomannose‐Dependent α‐(1→6)‐Mannosyltransferase
Authors: Tam Pui‐Hang , Besra Gurdyal S. , Lowary Todd L. 
Published: December 2007

AbstractA series of synthetic α‐(1→6)‐linked octyl mannopyranoside oligomers was evaluated as potential acceptors of a polyprenol monophosphomannose‐dependent α‐(1→6)‐mannosyltransferase that is involved in the biosynthesis of the mannan core of mycobacterial lipoarabinomannan. Initial evaluation demonstrated that the enzyme recognizes di‐, tri‐ and tetramannosides (5, 6 and 7) as substrates with different activities. While the highest mannosyltransferase activities were observed when the di‐ and trisaccharide were used as substrates, diminished enzymatic activity was seen with the tetramannoside. As octyl α‐D‐mannopyranosyl‐(1→6)‐α‐D‐mannopyranoside (5) appears to be the minimum structural element required for mannosyltransferase catalysis, a panel of methoxy and deoxy disaccharide analogues (8–21) were used to probe the substrate specificity of the enzyme further. In terms of the steric requirements at the active site, the enzyme does not recognize either C2′‐ and C2‐methoxy analogues as substrates, a result that suggests that the α‐(1→2)‐mannopyranosyl branches, which are present in the mannan core of LAM must be added on a larger α‐(1→6)‐oligomannan intermediate. In contrast, the presence of a methoxy functionality at the C3′, C3, C4′ and C4 positions are somewhat tolerated by the enzyme, although diminished enzyme activities were observed with the C4′‐ and C4‐methoxy analogues. Moreover, the 2′‐ and 4‐hydroxyl groups appear not to be critical for substrate binding at the active site, as both 2′‐ and 4‐deoxy analogues are substrates for the enzyme. In contrast, replacement of the hydroxyl groups at other positions essentially abolished enzymatic activity. Further kinetic characterization of the enzyme by using the effective acceptor substrates gave apparent KM values ranging from 111 to 437 μM, which are within two‐fold higher or lower than that for the parent dimannoside (5). Although the KM values indicate that the enzyme binds those acceptors with comparable affinities, the C4′‐methoxy analogue (12) turns over more slowly than the others, as indicated by the apparent Vmax values.
Towards a Tunable Tautomeric Switch in Azobenzene Biomimetics: Implications for the Binding Affinity of 2‐(4′‐Hydroxyphenylazo)benzoic Acid to Streptavidin
Authors: Farrera Joan‐Antoni , Canal Ivan , Hidalgo‐Fernández Pedro , Pérez‐García M. Lluïsa , Huertas Oscar , Luque F. Javier 
Published: December 2007

AbstractThe tautomeric equilibria of 2‐(4′‐hydroxyphenylazo)benzoic acid (HABA) and 2‐(3′,5′‐dimethyl‐4′‐hydroxyphenylazo)benzoic acid (3′,5′‐dimethyl‐HABA) have been studied by a combination of spectroscopic and computational methods. For neutral HABA in solvents of different polarity (toluene, chloroform, DMSO, DMF, butanol, and ethanol) the azo tautomer (AT) is largely predominant. For monoanionic HABA, the hydrazone tautomer (HT) is the only detected species in apolar solvents such as toluene and chloroform, while the AT is the only detected species in water and a mixture of both tautomers is detected in ethanol. Comparison of the results obtained for HABA and its 3′,5′‐dimethylated derivative shows that dimethylation of the hydroxybenzene ring shifts the tautomeric preferences towards the hydrazone species. These findings have been used to examine the differences in binding affinity to streptavidin, as the lower affinity of HABA can be explained in terms of the larger energetic cost associated with the tautomeric shift to the bioactive hydrazone species. Overall, these results suggest that a balanced choice of chemical substituents, embedding environment, and pH can be valuable for exploitation of the azo–hydrazone tautomerism of HABA biomimetics in biotechnological applications.
Antiproliferative Agents That Interfere with the Cell Cycle at the G1→S Transition: Further Development and Characterization of a Small Library of Stilbene‐Derived Compounds
Authors: Pizzirani Daniela , Roberti Marinella , Cavalli Andrea , Grimaudo Stefania , Di Cristina Antonietta , Pipitone Rosaria Maria , Gebbia Nicola , Tolomeo Manlio , Recanatini Maurizio 
Published: December 2007

AbstractIn this continuation of our research on derivatives containing the stilbene privileged structure or that are derived from it, we report the results of further studies carried out on the previously initiated collection of compounds. We used a parallel synthetic approach to rapidly obtain small sets of compounds and started the annotation of the library in progress by calculating some physicochemical properties to be eventually correlated with biological activities. A pharmacophore for the antiproliferative activity was also built to summarize the features of the library. We evaluated the antiproliferative and pro‐apoptotic activities of all compounds as well as the cell‐cycle effects of some representative compounds. After in‐depth investigations, 3′‐phenyl‐[1,1′;4′,1′′]terphenyl‐4,3′′,5′′‐triol showed the most interesting biological profile, as it interferes with cell‐cycle progression at the G1→S transition, acting on retinoblastoma phosphorylation and inducing cell differentiation.
Second‐order explicit integrator via composition for coupled rotating rigid bodies applied to roller cone drill bits
Authors: Endres L. , Krysl P. 
Published: December 2007

AbstractWe present a derivation of the equations of motion of a roller cone bit as an example of coupled rotating rigid bodies and apply a state‐of‐the‐art numerical integrator to produce an algorithm for use in a bit dynamics software application. The equations are derived using the virtual power method, which naturally handles the constraint between the bit body and the cones. These equations are fully three‐dimensional (three degrees of freedom for the body, plus one degree of freedom for each cone) and nicely parallel to the equations of motion of a single rigid body. We apply the composition of adjoint first‐order integrators (reminiscent of the approach used earlier to derive an explicit midpoint Lie method (Int. J. Numer. Meth. Eng.2005;63:2171–2193) to produce an algorithm that maintains the properties of the original three degree‐of‐freedom integrator: second‐order convergence, symplecticness, remarkable accuracy, and momentum conservation. This algorithm can be applied to other applications where one or more rigid bodies with a single rotational degree of freedom are attached to another rotating rigid body. Copyright © 2007 John Wiley & Sons, Ltd.
Übersicht zum derzeitigen Stand der numerischen Modellierung
Authors: Jäger Wolfram 
Published: December 2007

AbstractDer Baustoff Mauerwerk hat eine Jahrtausend alte Tradition und wurde früher nur auf der Basis von Erfahrung und handwerklichem Können angewendet. Er kam deshalb bis in die zweite Hälfte des vorigen Jahrhunderts fast ohne Berechnung aus. Die jedoch immer höheren Anforderungen, beispielsweise aus der Notwendigkeit der Energieeinsparung, haben zu einer raschen Entwicklung der Mauerwerksprodukte geführt. Die Berechnung und Bemessung versuchte mitzuhalten oder nachzuziehen. Die Mittel der Computertechnik zur realitätsnahen Abbildung des Baustoff‐ und Bauteilverhaltens ermöglichten es, Tragwerke aus Mauerwerk besser beurteilen zu können. Die neuen Erkenntnisse und Verfahren der Mechanik konnten und können immer nutzbringender für die Weiterentwicklung der Berechnungs‐ und Bemessungsmethoden im Mauerwerksbau eingesetzt und zur Klärung von Verhaltens‐ und Versagensphänomenen angewendet werden.Aber auch Schäden an bestehenden Mauerwerksbauten veranlassten die Ingenieure, den mechanischen Ursachen unter Nutzung der modernen Methoden der Baumechanik auf den Grund zu kommen und geeignete Reparatur‐ oder Verstärkungstechnologien behutsam einzusetzen.Heute ist die numerische Analyse integraler Bestandteil der Forschungsstrategie im Mauerwerksbau. Sie wird vorrangig zur Problemlösung und zur Ursachenklärung eingesetzt. Für die täglichen Planungsaufgaben reichen die bisherigen Mittel üblicher Ingenieurlösungen nach wie vor aus. Für Problemlösungen und Schadensabklärungen werden meist Mittel und Möglichkeiten der modernen Baumechanik eingesetzt, die jedoch i. d. R. umfangreiches Spezialwissen und entsprechende Erfahrungen erfordern. Die Überprüfung der Ergebnisse ist oft schwer möglich, muss bei bestehenden Bauwerken an der Realität vorgenommen und zusätzlich durch weitere Plausibilitäts‐ und Ingenieurkontrollen ergänzt werden.Nachfolgend soll eine kurze Einführung zur numerischen Simulation und Modellierung von Mauerwerk gegeben werden. Die anschließenden Beiträge zeigen die Einsatzmöglichkeiten von numerischen Methoden im Mauerwerksbau, wobei nur neuere Ergebnisse und Beispiele gezeigt werden sollen. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ermittlung effektiver elastischer Eigenschaften von Hochlochziegeln mittels numerischer Simulation
Authors: Hannawald Joachim , Brameshuber Wolfgang 
Published: December 2007

AbstractHochlochziegel (HLz) können in einem dreidimensionalen Finite‐Elemente (FE)‐Modell ganzer Wände nicht detailliert mit ihrer meist sehr komplexen Lochstruktur abgebildet werden, weil dann die Zahl der Freiheitsgrade der Berechnung zu groß würde. Sie müssen stattdessen als homogenes Ersatzkontinuum betrachtet werden, dessen effektive mechanische Eigenschaften zunächst nicht bekannt sind.In diesem Beitrag wird ein numerisches Homogenisierungsverfahren vorgestellt, mit dem die effektiven elastischen Eigenschaften von HLz ermittelt werden können. Das Verfahren wird auf drei unterschiedliche, praxisübliche HLz angewendet. Hierbei zeigt sich, dass alle drei HLz effektiv als orthotropes, elastisches Kontinuum zu beschreiben sind und daher jeweils neun elastische Konstanten zur vollständigen Charakterisierung erforderlich sind. Bei den messtechnisch relativ einfach zu bestimmenden E‐Moduln in Steinhoch‐ und Steinlängsrichtung stimmen die mit dem Homogenisierungsverfahren bestimmten Werte gut mit den experimentellen Beobachtungen überein. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Diskrete FE‐Modellierung von Mauerwerk zur Bestimmung der Druckfestigkeit
Authors: Graubner Carl‐Alexander , Richter Lars 
Published: December 2007

AbstractDie Finite‐Element‐Methode (FEM) dient zur Beschreibung des komplexen physikalischen Verhaltens von Festkörpern (ferner auch von Flüssigkeiten, Gasen, Feldern) und stellt ein Grundwerkzeug in den Ingenieurwissenschaften dar. Die Ergebnisse der FEM liefern trotz der Leistungsfähigkeit nur eine Näherungslösung, die häufig mit aus Versuchen gewonnenen Daten verifiziert werden muss und eine anschließende Kalibrierung der Modellparameter notwendig macht.In diesem Beitrag wird die Anwendung der FEM auf das Mauerwerk am Beispiel eines auf Druck belasteten 4‐Stein‐Körpers aus Ziegelmauerwerk beschrieben und insbesondere auf die Problematik der Abbildung der Materialeigenschaften eingegangen. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Moesin helps to restrain synaptic growth at the Drosophila neuromuscular junction
Authors: Seabrooke Sara , Stewart Bryan A. 
Published: December 2007

AbstractThe precise role of actin and actin‐binding proteins in synaptic development is unclear. In Drosophila, overexpression of a dominant‐negative NSF2 construct perturbs filamentous actin, which is associated with overgrowth of the NMJ, while co‐expression of moesin, which encodes an actin binding protein, suppresses this overgrowth phenotype. These data suggest that Moesin may play a role in synaptic development at the Drosophila NMJ. To further investigate this possibility, we examined the influence of loss‐of‐function moesin alleles on the NSF2‐induced overgrowth phenotype. We found that flies carrying P‐element insertions that reduce moesin expression enhanced the NMJ overgrowth phenotype, indicating a role for Moesin in normal NMJ morphology. In addition to the NMJ overgrowth phenotype, expression of dominant‐negative NSF2 is known to reduce the frequency of miniature excitatory junctional potentials and the amplitude of excitatory junctional potentials. We found that moesin coexpression did not restore the physiology of the mutant NSF2 phenotype. Together, our results demonstrate a role for moesin in regulating synaptic growth in the Drosophila NMJ and suggest that the effect of dominant‐negative NSF2 on NMJ morphology and physiology may have different underlying molecular origins. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2008.