bluuebunny/crossref_metadata_2025 huggingface dataset:
Control‐volume method for numerical simulation of two‐phase immiscible flow in two‐ and three‐dimensional discrete‐fractured media
Authors: Monteagudo J. E. P. , Firoozabadi A.
Published: July 2004

We provide a numerical procedure for the simulation of two‐phase immiscible and incompressible flow in two‐ and three‐dimensional discrete‐fractured media. The concept of cross‐flow equilibrium is used to reduce the fracture dimension from n to (n‐1) in the calculation of flow in the fractures. This concept, which is often referred to as the discrete‐fracture model, has a significant effect on the reduction of computational time. The spatial discretization is performed with the control‐volume method. This method is locally conservative and allows the use of unstructured grids to represent complex geometries, such as discrete‐fracture configurations. The relative permeability is upwinded with a criterion based on the evaluation of the flux direction at the boundaries of the control volumes, which is consistent with the physics of fluid flow. The system of partial differential equations is decoupled and solved using the implicit‐pressure, explicit‐saturation (IMPES) approach. The algorithm has been successfully tested in two‐ and three‐dimensional numerical simulations of wetting phase fluid injection (such as water) in discrete‐fractured media saturated by a nonwetting phase (such as nonaqueous phase liquid or oil) with mild to high nonlinearity in relative permeability and capillary pressure. To the best of our knowledge, results for simulations of two‐phase immiscible and incompressible flow in three‐dimensional discrete‐fractured media, including capillary and gravity effects, are the first to appear in the literature.
An observation‐based method for reconstructing ocean surface changes using a 340,000‐year deuterium excess record from the Dome Fuji ice core, Antarctica
Authors: Uemura R. , Yoshida N. , Kurita N. , Nakawo M. , Watanabe O.
Published: July 2004

An extended deuterium excess (d or d‐excess) record covering the last three glacial‐interglacial cycles (ca. 340,000 years) was obtained from the Dome Fuji ice core, Antarctica. In order to interpret the Antarctic d record as a climatic history of vapor source regions, the record should be corrected for the Antarctic site temperature effect. We propose an observation‐based method for correcting the d record. That method uses a regression curve of the observed spatial relationship between δD and d in Antarctica on the assumption that the present slope has not changed. Unlike the previously proposed model‐based method, our correction method results in considerable change in the d profile of the Dome Fuji ice core. The corrected d record anticorrelates with a mean ocean δ18O record (R2 = 0.74) and correlates with a SST record (R2 = 0.58) throughout the observed period. These results emphasize the significance of our empirical correction method.
Diurnal temperature range as an index of global climate change during the twentieth century
Authors: Braganza Karl , Karoly David J. , Arblaster J. M.
Published: July 2004

The usefulness of global‐average diurnal temperature range (DTR) as an index of climate change and variability is evaluated using observations and climate model simulations representing unforced climate variability and anthropogenic climate change. On decadal timescales, modelled and observed intrinsic variability of DTR compare well and are independent of variations in global mean temperature. Observed reductions in DTR over the last century are large and unlikely to be due to natural variability alone. Comparison of observed and anthropogenic‐forced model changes in DTR over the last 50 years show much less reduction in DTR in the model simulations due to greater warming of maximum temperatures in the models than observed. This difference is likely attributed to increases in cloud cover that are observed over the same period and are absent in model simulations.
External validation of the GRACE GGM01C gravity field using GPS and DORIS positioning results
Authors: Willis Pascal , Heflin Michael B.
Published: July 2004

We have used the new gravity field model GGM01C derived from GRACE data to reanalyze DORIS data from 1993.0 to 2003.2 using the Gipsy/Oasis software and a free‐network approach. We have estimated the position and velocity of each DORIS station in ITRF2000. In order to test the accuracy of these results, we have compared them to the positions and velocities of 43 collocated GPS stations using local ties and covariance information. DORIS results computed using the GGM01C gravity field instead of the EGM96 gravity field show a significantly improved external agreement with GPS. Position agreement of 12–26 mm was reduced to 10–13 mm and velocity agreement of 3.3–3.7 mm/yr was reduced to 2.4–3.3 mm/yr. This can be interpreted as an external test of the accuracy of the new GGM01C gravity field.
Trends in Swiss Alpine snow days: The role of local‐ and large‐scale climate variability
Authors: Scherrer Simon C. , Appenzeller Christof , Laternser Martin
Published: July 2004

Swiss Alpine snow cover is varying substantially on interannual to decadal time scales. In the late 20th century decreases in snow days (SD) have been observed for stations below 1300 m asl. A regression model is used in this work to quantify the importance of mean temperature and precipitation as well as large‐scale climate variability in order to explain the observed trends. Both, local‐ and large‐scale models account for a modest fraction of the observed seasonal variability. Results suggest that the recent decrease in low altitude snow cover can mainly be attributed to an increase in temperature. Differences are found for northern and southern Switzerland concerning the influence of large‐scale climate patterns. In contrast to southern Alpine regions, northern Alpine interannual SD variability is almost unaffected by the North Atlantic Oscillation (NAO). Decadal trends, however, can be explained via temperature only by a model that includes the explanatory variable NAO.
Extratropical stratosphere‐troposphere mass exchange
Authors: Schoeberl Mark R.
Published: July 2004

The net mass flux from the stratosphere to the troposphere can be computed from the heating rate along the 380 K isentropic surface and the time rate of change of the mass of the lowermost stratosphere (the region between the tropopause and the 380 K isentrope) following Appenzeller et al. [1996]. Given this net mass flux and the cross‐tropopause diabatic mass flux, the residual adiabatic mass flux across the tropopause can also be estimated. These fluxes have been computed using meteorological fields from a free‐running general circulation model (the finite volume general circulation model) and two assimilated data sets, finite volume data assimilation system (FVDAS), and UK Met Office (UKMO). All of the calculations agree that the annual average net mass flux for the Northern Hemisphere is about 1010 kg/s. There is less agreement on the Southern Hemisphere flux that might be half as large. For all three data sets the adiabatic mass flux is from the upper troposphere into the lowermost stratosphere. This adiabatic flux into the lowermost stratosphere is roughly 5 times larger than the diabatic mass flux into the stratosphere across the tropical tropopause. For the FVDAS the midlatitude tropopause diabatic flux is smaller than UKMO, apparently due to a systematically colder, higher FVDAS tropopause. Both data assimilation systems have a warmer, lower midlatitude tropopause compared to radiosondes, so the mass flux estimates can be considered upper bounds. Finally, we note that the difference in the diabatic mass fluxes between the two assimilated meteorological analyses is much larger than the interannual variability in either.
Pulmonary Vein Isolation for Atrial Fibrillation in Patients with Symptomatic Sinus Bradycardia or Pauses
Authors: KHAYKIN YAARIV , MARROUCHE NASSIR F. , MARTIN DAVID O. , SALIBA WALID , SCHWEIKERT ROBERT , WEXMAN MARK , STRUNK BRIAN , BEHEIRY SALWA , SAAD EDUARDO , BHARGAVA MANDEEP , BURKHARDT J. DAVID , JOSEPH GEORGE , TCHOU PATRICK , NATALE ANDREA
Published: July 2004

Introduction: Sick sinus syndrome is commonly associated with tachyarrhythmias and bradyarrhythmias that often are symptomatic. The aim of this study was to assess the effect of pulmonary vein isolation in patients with sick sinus syndrome and atrial fibrillation (AF).

Methods and Results: Three hundred fourteen consecutive patients who underwent pulmonary vein isolation between December 2000 and January 2002 were included in the study. Thirty‐one patients had sick sinus syndrome, which was defined as a preprocedural history of symptomatic sinus bradycardia or pauses. Endpoints included AF recurrence, change in the frequency of sinus pauses, and symptoms of presyncope or syncope, as well as mean heart rate and percentage of atrial pacing in patients with pacemakers implanted prior to the pulmonary vein isolation. Patients had AF for an average of 6 ± 3 years. Patients were 58 ±8 years old and had ejection fractions of 55 ± 4%. Sixty‐one percent had implanted pacemakers. AF recurred within 6 months in 4 patients. Two had a successful second pulmonary vein isolation procedure. There were no recurrences of presyncopal events (P < 0.05) or documented sinus pauses (P < 0.05) after successful pulmonary vein isolation in the patients without permanent pacemakers. Patients with pacemakers had a 13‐fold reduction in the percentage of atrial pacing (P < 0.05). Both groups showed a significant increase in average heart rates at 6‐month follow‐up.

Conclusion: Cure of AF by pulmonary vein isolation helped resolve the clinical manifestations of sick sinus syndrome, suggesting that the occurrence of AF and/or the associated treatment could be partially responsible for sick sinus syndrome. (J Cardiovasc Electrophysiol, Vol. 15, pp. 784‐789, July 2004)
Restoration of Heart Rate Turbulence by Titrated Beta‐Blocker Therapy in Patients with Advanced Congestive Heart Failure:
Authors: LIN LIAN‐YU , HWANG JUEY‐JEN , LAI LING‐PING , CHAN HSIAO‐LUNG , DU CHAO‐CHENG , TSENG YUNG‐ZU , LIN JIUNN‐LEE
Published: July 2004

Introduction: Heart rate turbulence (HRT) is a powerful novel predictor for cardiovascular mortality. Chronic congestive heart failure is associated with abnormal HRT. Whether antiadrenergic beta‐blocker therapy can restore control of HRT in patients with chronic congestive heart failure is unknown.

Methods and Results: A 24‐hour Holter ECG recording was obtained before and 1 and 3 months after titrated addition of atenolol therapy in 10 consecutive patients with advanced congestive heart failure. Two parameters derived from HRT, turbulence slope (TS) and turbulence onset (TO), and time‐ and frequency‐domain heart rate variability (HRV) parameters (SDNN, RMSSD, VLF, LF, HF) from 24‐hour ECG were compared before and after beta‐blocker therapy, together with the same parameters in age‐matched normal control. Results showed that TS (3.1 ± 2.2 vs 6.2 ± 3.0; P = 0.001) and all HRV parameters were increased after 3 months of atenolol treatment. No changes in TO were evident (0.6 ± 0.5 vs −0.2 ± 1.3; P = 0.13). The improvement of TS and the vagally mediated parameters of mean R‐R interval, RMSSD, and the HF component of HRV were positively correlated.

Conclusion: Abnormal HRT caused by chronic congestive heart failure can be restored by beta‐blocker therapy. The evolution of TS was positively correlated with measures of vagal modulation of heart rate. (J Cardiovasc Electrophysiol, Vol. 15, pp. 752‐756, July 2004)
Histopathologic Background for Resistance to Conventional Catheter Ablation of Common Atrial Flutter
Authors: IGAWA OSAMU , ADACHI MASAMITSU , HISATOME ICHIRO , MATSUI YUMIE
Published: July 2004

Histopathologic examination of the cavotricuspid isthmus in which a large‐tip catheter was necessary to achieve conduction block is presented. No thickened myocardium or prominent trabeculation was observed on the ablation line. A small cardiac vein extending through the isthmus across the ablation scar was detected. The remaining myocardial cells were distributed along the small cardiac vein. It is possible that the luminal blood flow of the small cardiac vein protects the surrounding atrial muscle from effective delivery of radiofrequency energy. (J Cardiovasc Electrophysiol, Vol. 15, pp. 829‐832, July 2004)
Reentry in a Pulmonary Vein as a Possible Mechanism of Focal Atrial Fibrillation
Authors: BELHASSEN BERNARD , GLICK AHARON , VISKIN SAMI
Published: July 2004

The case of an 18‐year‐old woman with recurrent idiopathic catecholamine‐sensitive paroxysmal atrial fibrillation is reported. Recordings of multiple initiations of atrial fibrillation at the proximal part of the right superior pulmonary vein suggested local reentry in the vein as the mechanism of atrial fibrillation. A single radiofrequency pulse delivered at this site resulted in definite cure of the arrhythmia. (J Cardiovasc Electrophysiol, Vol. 15, pp. 824‐828, July 2004)
Electrophysiologic Characteristics of Atrial Tachycardia Originating from the Right Pulmonary Veins or Posterior Right Atrium:
Authors: YAMADA TAKUMI , MURAKAMI YOSHIMASA , MUTO MASAHIRO , OKADA TARO , OKAMOTO MITSUHIRO , TOYAMA JUNJI , YOSHIDA YUKIHIKO , TSUBOI NAOYA , ITO TERUO , KONDO TAKAHISA , INDEN YASUYA , HIRAI MAKOTO , MUROHARA TOYOAKI
Published: July 2004

Introduction: The right pulmonary veins (RPVs) and posterior wall of the right atrium (PRA) are anatomically located adjacent to each other. The aim of this study was to demonstrate the electrophysiologic characteristics of atrial tachycardia (AT) originating from the PRA or RPVs.

Methods and Results: A total of 26 consecutive patients with AT originating from the RPVs or PRA underwent detailed atrial endocardial mapping and successful radiofrequency catheter ablation. Eight foci were found in the PRA and 18 foci in the RPVs. Analysis of P wave configuration showed that lead V1 was the most helpful in distinguishing the AT foci between these two sites. In all cases, double potential (DP) configurations were recorded from several electrodes of a multielectrode catheter placed in the PRA, and the first DP component (FP) was the earliest potential recorded from the right atrium during the tachycardia. The amplitude of the FP was higher than that of the second DP component (SP) for AT foci originating in the PRA, whereas the reverse occurred for those in the RPV. The activation sequence of the FP was from superior to inferior for the AT foci in the superior RPV, whereas the reverse occurred for the AT foci in the inferior RPV.

Conclusion: P wave configuration in lead V1 is helpful in distinguishing AT foci between those originating in the PRA and RPVs. The DPs obtained from the PRA can be useful in predicting whether AT foci originate from the PRA or RPVs. (J Cardiovasc Electrophysiol, Vol. 15, pp. 745‐751, July 2004)
Accuracy of Mode Switch Algorithms for Detection of Atrial Tachyarrhythmias
Authors: PASSMAN ROD S. , WEINBERG KENNETH M. , FREHER MARK , SCHAECHTER ANDI , GOLDBERGER JEFFREY J. , KADISH ALAN H.
Published: July 2004

Introduction: In patients with permanent pacemakers, mode switching events often are interpreted as surrogate markers for atrial tachyarrhythmias. The aim of this study was to determine the accuracy of automatic mode switching algorithms in patients with permanent pacemakers for the diagnosis of atrial tachyarrhythmias.

Methods and Results: Forty patients with tachycardia‐bradycardia syndrome and Medtronic Thera or Kappa 700 permanent pacemakers underwent Holter monitoring. Date, time of onset, and duration of each mode switch episode as recorded by the pacemaker and each atrial tachyarrhythmia episode as recorded by the Holter monitor were compared. Sixteen patients had a total of 54 atrial tachyarrhythmias documented on Holter monitoring (47 atrial fibrillation, 7 atrial flutter). Comparison of Holter data with pacemaker interrogation demonstrated that 53 (98.1%) of 54 atrial tachyarrhythmia episodes resulted in mode switching with one 13‐second episode of mode switching during sinus rhythm. The sensitivity and specificity of mode switching for the duration of atrial tachyarrhythmias were 98.1% and 100%, respectively. The algorithms detected 98.9% of the total duration of atrial fibrillation and 96.4% of the total duration of atrial flutter.

Conclusion: In patients with tachycardia‐bradycardia syndrome and permanent pacemakers having these mode switching algorithms, mode switching events are reliable surrogate markers for atrial tachyarrhythmias. Therefore, mode switching may serve as a valuable tool for clinical decision making and further research into the natural history and burden of atrial tachyarrhythmias. (J Cardiovasc Electrophysiol, Vol. 15, pp. 773‐777, July 2004)
Transmural Action Potential Repolarization Heterogeneity Develops Postnatally in the Rabbit
Authors: IDRISS SALIM F. , WOLF PATRICK D.
Published: July 2004

Introduction: In the hereditary long QT syndrome, arrhythmia risk changes with age despite the presence of an ion channel mutation throughout development. Age‐dependent changes in the transmural dispersion of repolarization may modulate this vulnerability. We recorded cardiac action potentials in infant, periadolescent, and adult rabbit myocardium to determine if transmural heterogeneities in repolarization are developmentally determined.

Methods and Results: Arterially perfused ventricular preparations were studied from 2‐week (n = 7), 7‐week (n = 7), and adult (n = 6) NZW rabbits. Action potentials were recorded with microelectrodes in five regions: epicardium (epi), subepicardium (subepi), midwall (mid), subendocardium (subendo), and endocardium (endo) during endocardial S1 pacing at cycle lengths of 2,000, 1,000, and 500 ms. At 2 weeks, the transmural APD90 profile was flat. With age, APD prolongation from subepi to endo created a transmural repolarization gradient. At 7 weeks, APD90 was significantly longer at subendo [204 ± 2 ms (mean ± SE) 2,000‐ms cycle length, P < 0.05] vs both endo (193 ± 2 ms) and epi (172 ± 2 ms), causing a heterogeneous transmural APD90 gradient. In adults, the transmural gradient was a smooth continuum such that APD was shortest in epicardium and longest in endocardium.

Conclusion: The transmural distribution of APD is developmentally determined. Tissue‐specific age‐dependent changes in APD can result in transmural repolarization heterogeneity. These age‐related effects may modulate arrhythmia vulnerability during development. (J Cardiovasc Electrophysiol, Vol. 15, pp. 795‐801, July 2004)
Electrophysiologic Effects of Nicorandil on the Guinea Pig Long QT1 Syndrome Model
Authors: YANG ZHIFANG , SHI GUOZHONG , LI CIZHENG , WANG HONGWEI , LIU KAI , LIU YUANMOU
Published: July 2004

Introduction: The slow component of the delayed rectifier K+ current IKs modulates repolarization of the cardiac action potential (AP), and the loss of IKs is known to cause long QT1 (LQT1) syndrome by prolonging action potential duration (APD). In this study, we generated a guinea pig LQT1 syndrome model using the IKs blocker chromanol 293B and then assayed the electrophysiologic effects of the ATP‐sensitive potassium channel IK,ATP opener nicorandil on this model.

Methods and Results: Transmembrane action potentials of perfused right ventricular papillary muscle preparations and both in vitro and in vivo ECGs of guinea pigs were recorded. Blockade of IKs by chromanol 293B (30 μM) prolonged the action potential duration at 90% repolarization (APD90) by 8.5% and QT interval by 16.5% of control values. In addition, proarrhythmic early afterdepolarizations (EADs) and ventricular fibrillation were observed. Venoinjection of chromanol 293B (1 mg/kg) revealed 10.9% QT prolongation. Nicorandil (5–30 μM) dose‐dependently shortened APD90 under the control condition, whereas it reversed the AP prolongation effect of chromanol 293B by 7.4% at the 30 μM concentration. Moreover, nicorandil shortened QT intervals both in vitro and in vivo and displayed an inhibitory effect on EADs and ventricular fibrillation.

Conclusion: The ATP‐sensitive potassium channel opener nicorandil may be an effective drug in the therapy of LQT1 syndrome by shortening APD and the QT interval. (J Cardiovasc Electrophysiol, Vol. 15, pp. 815‐820, July 2004)
Prospective Assessment after Pediatric Cardiac Ablation:
Authors: VAN HARE GEORGE F. , JAVITZ HAROLD , CARMELLI DORIT , SAUL J. PHILIP , TANEL RONN E. , FISCHBACH PETER S. , KANTER RONALD J. , SCHAFFER MICHAEL , DUNNIGAN ANN , COLAN STEVEN , SERWER GERALD ,   Participating Members of the Pediatric Electrophysiology Society
Published: July 2004

Introduction: A multicenter prospective study was designed and implemented to assess the short‐ and longer‐term results and risks associated with radiofrequency (RF) ablation in children.

Methods and Results: Patients recruited for the study were aged 0 to 16 years with supraventricular tachycardia due to accessory pathways or AV nodal reentrant tachycardia (AVNRT), excluding patients with nontrivial congenital heart disease. A national registry also was established, and contributing centers were encouraged to enroll all pediatric patients, aged 0 to 21 years, undergoing ablation at their center. This report summarizes acute results of these procedures. For analysis, subjects were divided into three groups: the prospective cohort (n = 481), cohort‐eligible registry participants (n = 504), and not cohort eligible registry participants (n = 1,776). Prospectively enrolled cohort patients were similar to cohort‐eligible patients in terms of demographic and other patient characteristics. Overall success rates for RF ablation were high (95.7%), with higher success rates for left‐sided and particularly left free‐wall pathways (97.8%) than right free‐wall pathways (90.8%). Complications of both electrophysiologic study and RF ablation were infrequent (4.2% and 4.0%, respectively), and there were no deaths. AV block was uncommon overall (1.2%) and was limited to ablation in AVNRT (2.1%) and septal accessory pathways (3.0%).

Conclusion: Despite the multicenter and prospective design, the study demonstrates high success rates and low complication rates, which are comparable to prior single‐center retrospective studies. These results may serve as the current best benchmark for expected results in the pediatric population, aged 0 to 16 years, both in terms of acute success rates and the occurrence of complications. (J Cardiovasc Electrophysiol, Vol. 15, pp. 759‐770, July 2004)
Azygos Vein Lead Implantation:
Authors: CESARIO DAVID , BHARGAVA MANDEEP , VALDERRÁBANO MIGUEL , FONAROW GREGG C. , WILKOFF BRUCE , SHIVKUMAR KALYANAM
Published: July 2004

High defibrillation thresholds (DFTs) occasionally are encountered during placement of implantable cardioverter defibrillators (ICDs). There are multiple strategies to lower DFTs in such patients, including reassessment of right ventricular lead position, alteration of the shock waveform, and implantation of subcutaneous arrays. This article describes a novel technique of implanting a high‐voltage lead in the azygos vein. This procedure may serve as an adjunctive approach to reduce DFTs. The anatomic location of the azygos vein posterior to the heart provides a suitable shocking vector between the right ventricular electrode, a high‐voltage lead placed in the azygos vein, and the ICD can. (J Cardiovasc Electrophysiol, Vol. 15, pp. 780‐783, July 2004)
Left Atrial Isthmus:
Authors: BECKER ANTON E.
Published: July 2004

Introduction: The success rate of catheter maze ablation procedures for atrial fibrillation depends upon adequate electrical isolation by performing linear ablation lesions. However, recurrence of atrial arrhythmias is not uncommon, particularly in the so‐called left atrial isthmus, between the orifice of the left inferior pulmonary vein and the mitral valve annulus. The focus of the present study is the anatomy of this area.

Methods and Results: Twenty human hearts were studied. The distance between the left inferior pulmonary vein and the mitral valve, the thickness of the left atrial myocardium, and the extent of left atrial myocardium toward the mitral valve were measured. The AV groove contained a fat pad harboring the great cardiac vein. The distance between the vein and the valve varied considerably (range 17–51 mm). The great cardiac vein coursed along the inferior left atrial wall, approximately 1 cm above the level of the mitral valve. Myocardial thickness also varied considerably (distal: range 1.4–7.7 mm, midway: range 1.2–4.4 mm, proximal: range 0−3.2 mm). Left atrial myocardium extended onto the mitral valve in two hearts, and the left atrial myocardium ended above the level of the mitral valve (range 1.8−5.1 mm) in six hearts. An important variable because it raises the question of how much energy should be used—and at which point—to achieve an adequate transmural ablation line.

Conclusion: The great cardiac vein is not an adequate marker for the level of the mitral valve, left atrial myocardium may continue onto the mitral valve, the distance between the left inferior pulmonary vein and mitral valve varies considerably, and left atrial myocardial thickness is highly variable and not uniform.(J Cardiovasc Electrophysiol, Vol. 15, pp. 809‐812, July 2004)
Effect of Rapid Biphasic Shock Subpulse Switching on Ventricular Defibrillation Thresholds
Authors: DOSDALL DEREK J. , ROTHE DARRIN E. , BRANDON TEDD A. , SWEENEY JAMES D.
Published: July 2004

Introduction:The aim of this study was to demonstrate that significant reductions in defibrillation threshold (DFT) can be achieved by rapidly switching defibrillation pulses within an overall biphasic envelope between multiple endovascular electrode sets.

Methods and Results:Defibrillation electrodes were implanted in four locations in nine anesthetized swine (41.7 ± 8.7 kg). Electrodes were implanted into the right ventricular apex (RV), the superior vena cava (SVC), over the left pectoral region as a “hot can” (Can), and within the middle cardiac vein on the posterior left ventricular (LV) surface. The 50% DFT (level for which 50% of delivered shocks successfully defibrillated) for control shocks (7‐ms first phase, 0.5‐ms interpulse period, 4‐ms second phase, RV−→ SVC++ Can+) were determined to have energy of 20.5 ± 5.5 J (mean ± SD). Mean 50% DFTs were also determined for waveforms that split each phase of the same overall biphasic waveform between various electrode sets. Each phase was divided into 2, 3, 4, or 6 subpulses, the defibrillation shock was sequentially delivered to multiple electrode sets, and DFTs were determined (11.9 ± 4.8 J, 11.7 ± 2.9 J, 17.9 ± 8.7 J, 16.7 ± 6.1 J, respectively). DFT energy was statistically lower than the control (Wilcoxon sign rank test; P < 0.05) when each phase was divided into 2 or 3 subpulses.

Conclusion:Rapid shock switching within an overall biphasic waveform between electrode sets including an electrode in the middle cardiac vein potentially can lower DFT energy by 40% or more.(J Cardiovasc Electrophysiol, Vol. 15, pp. 802‐808, July 2004)
Seed Development and Differentiation: A Role for Metabolic Regulation
Authors: Borisjuk L. , Rolletschek H. , Radchuk R. , Weschke W. , Wobus U. , Weber H.
Published: July 2004

Abstract: During seed growth, the filial organs, Vicia embryos and barley endosperm, differentiate into highly specialized storage tissues. Differentiation is evident on structural and morphological levels and is reflected by the spatial distribution of metabolites. In Vicia embryos, glucose is spatially correlated to mitotic activity whereas elongating and starch accumulating cells contain high levels of sucrose. Seed development is also regulated by phytohormones. In pea seeds, GA‐deficiency stops seed growth before maturation. In Arabidopsis seeds, ABA regulates differentiation and inhibits cell division activity. The ABA pathway, in turn, is linked to sugar responses. In young Vicia embryos, invertases in maternal tissues control both concentration and composition of sugars. Embryonic and endospermal transfer cell formation represents an early differentiation step. Establishing an epidermis‐localised sucrose uptake system renders the embryo independent from maternal control. cDNA array analysis in barley seeds revealed a massive transcriptional re‐programming of gene expression during the transition stage, when gene clusters related to transport and energy metabolism are highly transcribed. Sucrose represents a signal for differentiation and up‐regulates storage‐associated gene expression. Sucrose signalling involves protein phosphorylation. Sucrose non‐fermenting‐1‐related protein kinases are apparently induced in response to high cellular sucrose, and could act as mediators of sucrose‐specific signals. Energy metabolism changes during seed development. In Vicia embryos metabolic responses upon hypoxia and low energy charge levels are characteristic for young undifferentiated stages when energy demand and respiration are high. During the transition stage, the embryo becomes adapted to low energy availability and metabolism becomes energetically more economic and tightly controlled. These adaptations are embedded in the embryo's differentiation program and coupled with photoheterotrophic metabolism. In Vicia cotyledons, ATP content increases in a development‐dependent pattern and is associated with the greening process. The main role of seed photosynthesis is to increase internal O2 contents and to control biosynthetic fluxes by improving energy supply.
Evolution of Carnivory in Lentibulariaceae and the Lamiales
Authors: Müller K. , Borsch T. , Legendre L. , Porembski S. , Theisen I. , Barthlott W.
Published: July 2004

Abstract: As a basis for analysing the evolution of the carnivorous syndrome in Lentibulariaceae (Lamiales), phylogenetic reconstructions were conducted based on coding and non‐coding chloroplast DNA (matK gene and flanking trnK intron sequences, totalling about 2.4 kb). A dense taxon sampling including all other major lineages of Lamiales was needed since the closest relatives of Lentibulariaceae and the position of “proto‐carnivores” were unknown. Tree inference using maximum parsimony, maximum likelihood, and Bayesian approaches resulted in fully congruent topologies within Lentibulariaceae, whereas relationships among the different lineages of Lamiales were only congruent between likelihood and Bayesian optimizations. Lentibulariaceae and their three genera (Pinguicula, Genlisea, and Utricularia) are monophyletic, with Pinguicula being sister to a Genlisea‐Utricularia clade. Likelihood and Bayesian trees converge on Bignoniaceae as sister to Lentibulariaceae, albeit lacking good support. The “proto‐carnivores” (Byblidaceae, Martyniaceae) are found in different positions among other Lamiales but not as sister to the carnivorous Lentibulariaceae, which is also supported by Khishino‐Hasegawa tests. This implies that carnivory and its preliminary stages (“proto‐carnivores”) independently evolved more than once among Lamiales. Ancestral states of structural characters connected to the carnivorous syndrome are reconstructed using the molecular tree, and a hypothesis on the evolutionary pathway of the carnivorous syndrome in Lentibulariaceae is presented. Extreme DNA mutational rates found in Utricularia and Genlisea are shown to correspond to their unusual nutritional specialization, thereby hinting at a marked degree of carnivory in these two genera.
Phenology, Sex Ratio, and Spatial Distribution Among Dioecious Species of Trichilia (Meliaceae)
Authors: Morellato L. P. C.
Published: July 2004

Abstract: The flowering, sex ratio, and spatial distribution of four dioecious species of Trichilia (Meliaceae) were studied in a semi‐deciduous forest in southeastern Brazil. All reproductive trees (T. clausseni, T. pallida and T. catigua) with dbh 5 cm within a 1‐ha plot were collected, sexed, mapped and, for individuals of each species, the distances to the nearest neighbour of the same and opposite sex were measured. For the shrub species T. elegans (dbh < 5 cm), all reproductive individuals were sampled randomly in 10 samples of 10 × 10 m. The reproductive phenology was observed at weekly to monthly intervals from May 1988 to January 1990. The species are strictly dioecious, did not present any sex‐mixed trees or sex switching during the study, and sex ratio did not differ significantly from 1: 1. The size distributions and the relative size variation were not significantly different between sexes. There was no significant segregation or clumping between individuals of either sex and no fruit production without pollination. Onset of flowering and flowering peak were synchronous between male and female plants for all species studied. Flower synchrony was related to outcrossing and pollinator attraction rather than climatic factors.
QTL Mapping for a Trade‐Off between Leaf and Bud Production in a Recombinant Inbred Population of Microseris douglasii and M. bigelovii (Asteraceae, Lactuceae): A Potential Preadaptation for the Colonization of Serpentine Soils
Authors: Gailing O. , Macnair M. R. , Bachmann K.
Published: July 2004

Abstract: The different response to growth on serpentine soil is a major autecological difference between the annual asteracean species Microseris douglasii and M. bigelovii, with nearly non‐overlapping distribution ranges in California. Early flowering and seed set is regarded as a crucial character contributing to escape drought and thus is strongly correlated with survival and reproductive success on serpentine as naturally toxic soil. M. bigelovii (strain C94) from non‐serpentine soil produces more leaves at the expense of bud production in the first growing phase than M. douglasii (B14) from serpentine soil. A QTL mapping study for this trade‐off and for other growth‐related traits was performed after six generations of inbreeding (F7) from a single interspecific hybrid between B14 and C94 on plants that were grown on serpentine and alternatively on normal potting soil. The trade‐off is mainly correlated with markers on one map region on linkage group 03a (lg03a) with major phenotypic effects (phenotypic variance explained [PVE] = 18.8 ‐ 31.7 %). Plants with the M. douglasii allele in QTL‐B1 (QTL‐NL1) produce more buds but fewer leaves in the first 119 days on both soil types. Three modifier QTL could be mapped for bud and leaf production. In one modifier (QTL‐B2 = QTL‐NL4) the M. douglasii allele is again associated with more buds but fewer leaves. QTL mapped for bud set in the F6 co‐localize with QTL‐B1 (major QTL) and QTL‐B3. Two additional QTL for leaf length and red coloration of leaves could be mapped to one map region on lg03a. Co‐localization of the two QTL loci with major phenotypic effects on bud and leaf production strongly suggests that a major genetic locus controls the trade‐off between the two adaptive traits. The importance of mutational changes in major genes for the adaptation to stressful environments is discussed.
Succession in Inland Sand Ecosystems: Which Factors Determine the Occurrence of the Tall Grass Species Calamagrostis epigejos (L.) Roth and Stipa capillata L.?
Authors: Süβ K. , Storm C. , Zehm A. , Schwabe A.
Published: July 2004

Abstract: In many successional series, grass species play an important role in mid‐successional stages. Using calcareous sand ecosystems in the northern upper Rhine valley (Germany) as a model, we analyzed successional trajectories and the factors that determine their direction. A 5‐ to 7‐year study of 23 permanent plots is presented. Polar ordination revealed that succession starts with pioneer communities (dominated by Corynephorus canescens and cryptogams) and can eventually lead to relatively stable Calamagrostis epigejos or Stipa capillata tall grass stands. At some sites, Cynodon dactylon can play a major role, but we focused on the two previously mentioned species. Gradient analyses of their ecological amplitudes by means of principal components and regression analysis were carried out in order to elucidate the factors determining the successional trajectories. Soil analyses of 71 plots established significantly positive linear relations for C. epigejos with respect to total nitrogen, extractable phosphate and potassium, as well as soil moisture indicator values. C. epigejos is not able to spread if the stress factors nutrient deficiency and dryness are combined. Lower tolerance limits are presented. In contrast, S. capillata shows negative relations to phosphate, declining strongly at P contents > 20 mg kg‐1. At a moisture indicator value of around 3.2 (indicating dry sites), S. capillata reaches its optimum. S. capillata is a model for a tall grass species which, even with low nutrient levels and dry soil conditions, can be successful in mid‐successional phases; but it is displaced by C. epigejos if soil moisture increases or phosphate/potassium supply is higher. Regarding a general framework, the successional phases are characterized by processes such as replacement of species, facilitation, and inhibition.
Coordinated Expression of Sulfate Uptake and Components of the Sulfate Assimilatory Pathway in Maize
Authors: Hopkins L. , Parmar S. , Bouranis D. L. , Howarth J. R. , Hawkesford M. J.
Published: July 2004

Abstract: A high‐affinity‐type sulfate transporter (Group 1: ZmST1;1, Accession No. AF355602) has been cloned from maize seedlings by RT‐PCR. Tissue and cell specific localisation of this sulfate transporter has been determined along the developmental gradient of the root and in leaves of different ages. In S‐sufficient conditions there was uniform low expression of ZmST1;1 in the root and very low expression in the leaves. Increased mRNA abundance and sulfate influx capacity indicated that S‐starvation increased ZmST1;1 expression in roots, especially at the top of the root (just behind the seed, the area possessing most laterals and root hairs) compared to the root tip. Similarly a group 2, probable low affinity‐type sulfate transporter, ZmST2;1, and also ATP‐sulfurylase and APS‐reductase but not OAS(thiol)lyase were induced by S‐starvation and showed highest expression in the upper section of the root. S‐starvation increased root/shoot ratio by 20 % and increased root lateral length and abundance in the region closest to the root tip. As the increase in root proliferation was not as great as the increase in mRNA pools, it was clear that there was a higher cellular abundance of the mRNAs for sulfate transporters, ATP‐sulfurylase, and APS‐reductase in response to sulfur starvation. In the leaves, the sulfate transporters, ATP‐sulfurylase and APS‐reductase were induced by S‐starvation with the most mature leaf showing increased mRNA abundance first. In situ hybridization indicated that ZmST1;1 was expressed in epidermal and endodermal cell layers throughout the root whilst OAS(thiol)lyase was highly expressed in the root cortex.
Indirect Defence of Plants against Herbivores: Using Arabidopsis thaliana as a Model Plant
Authors: van Poecke R. M. P. , Dicke M.
Published: July 2004

Abstract: In their defence against pathogens, herbivorous insects, and mites, plants employ many induced responses. One of these responses is the induced emission of volatiles upon herbivory. These volatiles can guide predators or parasitoids to their herbivorous prey, and thus benefit both plant and carnivore. This use of carnivores by plants is termed indirect defence and has been reported for many plant species, including elm, pine, maize, Lima bean, cotton, cucumber, tobacco, tomato, cabbage, and Arabidopsis thaliana. Herbivory activates an intricate signalling web and finally results in defence responses such as increased production of volatiles. Although several components of this signalling web are known (for example the plant hormones jasmonic acid, salicylic acid, and ethylene), our understanding of how these components interact and how other components are involved is still limited. Here we review the knowledge on elicitation and signal transduction of herbivory‐induced volatile production. Additionally, we discuss how use of the model plant Arabidopsis thaliana can enhance our understanding of signal transduction in indirect defence and how cross‐talk and trade‐offs with signal transduction in direct defence against herbivores and pathogens influences plant responses.
Phylogenetic Position of Endosymbiotic Green Algae in Paramecium bursaria Ehrenberg from Japan
Authors: Hoshina R. , Kamako S.‐i. , Imamura N.
Published: July 2004

Abstract: Endosymbiotic green algae of Japanese Paramecium bursaria were phylogenetically analyzed based on DNA sequences from the ribosomal DNA operon (18S rDNA, ITS1, 5.8S rDNA, and ITS2). Phylogenetic trees constructed using 18S rDNA sequences showed that the symbionts belong to the Chlorella sensu stricto (Trebouxiophyceae) group. They are genetically closer to the C. vulgaris Beijerinck group than to C. kessleri Fott et Nováková as proposed previously. Branching order in C. vulgaris group was unresolved in 18S rDNA trees. Compared heterogeneities of 18S rDNA, ITS1, 5.8S r, and ITS2 among symbionts and two Chlorella species, indicated that the ITS2 region (and probably also ITS1) is better able to resolve phylogenetic problems in such closely related taxa. All six symbiotic sequences obtained here (approximately 4000‐bp sequences of 18S rDNA, ITS1, 5.8S rDNA, and ITS2) were completely identical in each, strongly suggesting a common origin.
Pleiotropic Effects of the Arabidopsis Cryptochrome 2 Allelic Variation Underlie Fruit Trait‐Related QTL
Authors: El‐Assal S. E. D. , Alonso‐Blanco C. , Hanhart C. J. , Koornneef M.
Published: July 2004

Abstract: The previous molecular identification of a flowering time QTL segregating in the Arabidopsis Ler× Cvi cross, demonstrated that natural allelic variation at the blue light photoreceptor CRY2 gene affects flowering time El‐Assal et al., 2001). In addition, previous works on the same cross have mapped several QTL affecting other unrelated life history traits in the CRY2 genomic region. In the present report, we have used a set of Arabidopsis Ler transgenic plants carrying four different functional CRY2 transgenes for phenotypic analyses, with the aim of exploring the extent of pleiotropy of CRY2 allelic variation. It is concluded that previously identified QTL affecting fruit length, ovule number per fruit, and percentage of unfertilized ovules are caused by this same Ler/Cvi CRY2 allelic variation. In addition, dose effects of the CRY2‐Ler allele are detected for fruit length. A seed weight QTL at the map position of CRY2 could not be confirmed and also no effect on seed dormancy was observed. Thus, it is shown that transgenic plants carrying different alleles can be a useful tool to attribute QTL for different complex traits to a specific locus, even when the relationship among the traits has not been previously suggested.
Tyrosine Phosphorylation Inhibits the Interaction of 14‐3‐3 Proteins with the Plant Plasma Membrane H+‐ATPase
Authors: Giacometti S. , Camoni L. , Albumi C. , Visconti S. , De Michelis M. I. , Aducci P.
Published: July 2004

Abstract: Interaction of 14‐3‐3 proteins with their targets depends not only on the phosphorylation status of the target but also on that of 14‐3‐3 Fu et al., 2000). In this work we demonstrated that the maize 14‐3‐3 isoform GF14‐6 is a substrate of the tyrosine kinase insulin growth factor receptor 1. By means of site‐directed mutants of GF14‐6, we identified Tyr‐137 as the specific tyrosine residue phosphorylated by the insulin growth factor receptor 1. Phosphorylation of GF14‐6 on Tyr‐137 lowered its affinity for a peptide mimicking the 14‐3‐3 binding site of the plant plasma membrane H+‐ATPase. Moreover, phosphorylation in planta of 14‐3‐3 tyrosine residues, resulting from incubation with the tyrosine phosphatase inhibitor, phenylarsine oxide, decreased their association to the H+‐ATPase.
Molecular Phylogeny of Anthyllis spp.
Authors: Nanni L. , Ferradini N. , Taffetani F. , Papa R.
Published: July 2004

Abstract: For the genus Anthyllis (Fam. Fabaceae, tribe Loteae), with few exceptions, little information is available on the genetic variation among and within species. This genus contains 20 species distributed throughout Europe, Africa, and the Mediterranean basin. The most widespread species is A. vulneraria, and over 30 intraspecies taxa have been identified based on plant morphology. To study the molecular phylogeny of the genus, the sequences of the internal transcribed spacers ITS1 and ITS2 of the nuclear ribosomal DNA of 10 Anthyllis species, including 11 subspecies of A. vulneraria and three subspecies of A. montana, were obtained and analysed together with sequences of five other species of the genus obtained from GenBank. Our results suggest that the genus Anthyllis is not monophyletic and is divided in two main clades: the Anthyllis sensu strictu and the “tetraphylla clade”. The former includes most of the Anthyllis species, and the latter includes three annual species more closely related to Lotus. All the taxa were also analysed according to seven chloroplast microsatellites, and these data closely confirm the results obtained with the ITS phylogeny.
Non‐Euglossine Bees also Function as Pollinators of Sinningia Species (Gesneriaceae) in Southeastern Brazil
Authors: SanMartin‐Gajardo I. , Sazima M.
Published: July 2004

Abstract: Pollination by male and female Euglossini bees, euglossophily, was suggested for a number of neotropical Gesneriaceae species. Information on bee species other than Euglossini as pollinators of neotropical members of this family is limited, and in the tribe Sinningieae data about bee pollination are still lacking. Here, we report on floral biology and bee pollination of four Sinningia species: S. schiffneri, S. eumorpha, S. villosa, and Sinningia“canastrensis”. The flower features, such as corolla size, shape, and colour, are very different among the four species, but all conform to the melittophilous syndrome. The average nectar volume and sugar amount is low in S. schiffneri, S. eumorpha, and Sinningia“canastrensis”, when compared to that of S. villosa, but low nectar amounts is a general feature of Sinningia species. The main pollinators of the four species are: small Tapinotaspidini (Trigonopedia ferruginea) of S. schiffneri, large Bombini (Bombus morio) and large Centridini (Epicharis morio) of S. eumorpha, large Euglossini (Eulaema cingulata and Eufriesea surinamensis) of S. villosa, and large Euglossini (Eufriesea violascens) and Megachilini (Megachile sp.) of Sinningia“canastrensis”. Out of the four species, only S. villosa is exclusively Euglossini‐pollinated. The marked differences in flower features and nectar production of these Sinningia species may reflect their pollination by distinct groups of bees. These results strengthen the idea of multiple origins for the pollination systems involving bees within this genus, which is highly supported by molecular phylogenetic analyses.