bluuebunny/crossref_metadata_2025 huggingface dataset:
Seed bank dynamics in five Panamanian forests
Authors: Fornara D. A. , Dalling J. W.
Published: February 2005

Many tropical pioneer species depend on the presence of high seed densities in the soil for successful recruitment following canopy disturbance (Cheke et al. 1979, Dalling & Hubbell 2002, Guevara Sada & Gómez Pompa 1972, Whitmore 1983). However determinants of variation in the composition and abundance of soil seed banks remain poorly understood. Seed bank densities can be affected by rates of seed predation and pathogen infection on the surface and in the soil, by intrinsic rates of loss in viability following dispersal, and by variation in the timing and duration of fruit production (Dalling et al. 1997, Garwood 1983, Murray & Garcia 2002). Here we compare seasonal fluctuations in seed bank density in five Panamanian forests varying in elevation and seasonality of precipitation (Table 1). We predict that lowland forests should show stronger intra-annual fluctuation in seed bank densities than montane forests because seed production and loss rates should be higher under conditions of greater resource availability, and where consistent high temperatures support greater abundance or activity of seed predators and pathogens (Brühl et al. 1999). Secondly, among lowland sites, we predict greater fluctuations in seed bank densities at drier, more seasonal sites where seasonally favourable conditions for seedling recruitment may select for interspecific synchrony in fruit production (Daubenmire 1972, Garwood 1983).
Influence of tree species and compass bearing on insect folivory of nine common tree species in the West African savanna
Authors: Unsicker Sybille B. , Mody Karsten
Published: February 2005

Levels of leaf damage due to insect folivory have been investigated in forests of different latitudes all over the world, but most research has concentrated on a few common forest types. Most studies of insect herbivory were conducted in (sub)tropical rain forests (Barone 1998, Basset 1996, Coley 1983, Lowman 1985), or in temperate forests (Landsberg & Ohmart 1989, Lowman & Heatwole 1992). In contrast, little is known about insect folivory of woody plants in tropical savannas (Fowler & Duarte 1991, Marquis et al. 2001, Ribeiro 2003, Stanton 1975), and no such data are available for the West African savanna ecosystem (Andersen & Lonsdale 1990). Savannas cover about 40% of the land surface of Africa and 20% of the world (Scholes & Walker 1993), and savanna trees may host considerable numbers of insects, including many herbivores (Grant & Moran 1986, Mody et al. 2003). Therefore, insect herbivory can be considered a potentially important aspect of plant–animal interactions for vast areas of tropical ecosystems, where it has been studied remarkably rarely so far.
The effects of the wood-boring Oncideres humeralis (Coleoptera, Cerambycidae) on the number and size structure of its host-plants in south-east Brazil
Authors: Romero Gustavo Q. , Vasconcellos-Neto João , Paulino Neto Hipólito F.
Published: February 2005

Beetles of the family Cerambycidae can girdle stems and larvae bore live or dead stems of their host plants (Linsley 1961), and when they use active tissues (e.g. xylem), can affect the development and survivorship of their hosts (Nowak et al. 2001). Moreover, borer attack can rapidly stress host plants (Matter 2001), often killing them (Nowak et al. 2001). Consequently, they can cause changes in size structure of the plant population, depending on the intensity of attack and plant survival rates (Caraglio et al. 2001). Cerambycids of the genus Oncideres (Lamiinae) present the most specialized behaviour in host-plant use, in which the female cuts stems with its mandibles and prepares the oviposition site above the cut portion by perforating the bark and then inserting eggs (Caraglio et al. 2001, Rice 1989, 1995).
Resource allocation to reproductive organs during masting in the tropical emergent tree, Dipterocarpus tempehes
Authors: Ichie Tomoaki , Kenta Tanaka , Nakagawa Michiko , Sato Kaori , Nakashizuka Tohru
Published: February 2005

Some tree species exhibit large year-to-year variation in seed production, a phenomenon known as masting (Kelly 1994, Kelly & Sork 2002). Even in tropical rain forests, in which the climate is suitable for plant growth all year round with little seasonal variation (Whitmore 1998), there are many reports of masting (Appanah 1993, Hart 1995, Newbery et al. 1998, Newstrom et al. 1994, Wheelwright 1986). In particular, Dipterocarpaceae, the dominant family in lowland mixed dipterocarp forests in South-East Asia, undergo mast fruiting following mass-flowering with strong interspecific synchronization in aseasonal western Malesia (Appanah 1985, 1993; Ashton 1989, Ashton et al. 1988, Curran et al. 1999, Janzen 1974, Medway 1972, Sakai et al. 1999, Whitmore 1998, Wood 1956). In mixed-dipterocarp forests, dipterocarp species contribute more than 70% of the canopy biomass (Bruenig 1996, Curran & Leighton 2000). Masting of dipterocarp species is therefore likely to have a major impact on animal populations, and also on the nutrient cycle in such forest ecosystems by causing fluctuations in the availability of resources (Sakai 2002).
Tap-root depth of tropical seedlings in relation to species-specific edaphic preferences
Authors: Yamada Toshihiro , Suzuki Eizi , Yamakura Takuo , Tan Sylvester
Published: February 2005

We compared seedlings of sandy-soil specialist species (Dryobalanops aromatica and Scaphium borneense) and clay-rich-soil specialist congeners (D. lanceolata and S. longipetiolatum) in a tropical rain forest in Lambir Hills National Park, Malaysia, to determine whether variations in belowground seedling architecture and allometry were related to edaphic specialization. A convergent trait that was phylogenetically independent across the two genera was the presence of a deeper tap-root at any height and any root biomass in sandy-soil specialists than in clay-rich-soil specialists. This trait was fixed independently of the edaphic conditions in which the trees actually grew. Finer-textured soils generally have better water-holding capacity; we concluded that seasonal water limitation would be more severe in sandy soils than in clay-rich soils, and that water limitation would provoke convergence in seedling root depth among species with the same edaphic preferences. All significant differences found in interspecific comparison within Dryobalanops were consistent with the water-availability hypothesis; the sandy-soil specialist had larger root biomass at any total biomass and had smaller leaf biomass at any root biomass than the clay-rich-soil specialist. However, for Scaphium this was not the case, suggesting that factors other than water-limitation may also underlie seedling allometric relationships.
Enhanced Oxidative Stress in iNOS-Deficient Mice after Traumatic Brain Injury: Support for a Neuroprotective Role of iNOS
Authors: Bayır Hülya , Kagan Valerian E. , Borisenko Grigory G. , Tyurina Yulia Y. , Janesko Keri L. , Vagni Vincent A. , Billiar Timothy R. , Williams Deborah L. , Kochanek Patrick M.
Published: February 2005

Studies in experimental traumatic brain injury (TBI) suggest both deleterious and protective effects of inducible nitric oxide synthase (iNOS). Early after injury, iNOS may be detrimental via formation of peroxynitrite and iNOS inhibitors are protective. In contrast, we reported impaired long-term functional outcome after TBI in iNOS knockout (ko) versus wild-type (wt) mice. To elucidate potential neuroprotective and neurotoxic mechanisms for iNOS, we studied nitric oxide formation by electron paramagnetic resonance (EPR) spectroscopy using diethyldithiocarbamate—iron (DETC—Fe) as a spin trap and markers of nitrosative ( S-nitrosothiol (RSNO, Fluorescent assay); nitrotyrosine (3NT, ELISA)) and oxidative stress (ascorbate, HPLC) at 72 h after controlled cortical impact (CCI) in iNOS ko and wt and in uninjured iNOS ko and wt mice. 3NT immunostaining with macrophage and myeloperoxidase (MPO) dual labeling was also assessed in brain sections. Brain DETC—Fe—NO low-temperature EPR signal intensity was ∼2-fold greater in wt versus iNOS ko at 72 h after CCI. Ascorbate levels decreased in injured hemisphere in wt and iNOS ko versus uninjured —this decrease was more pronounced in iNOS ko. In wt mice, RSNO and 3NT levels were increased after CCI versus uninjured (50% and 400%, respectively, P<0.05). RSNO levels were not increased in iNOS ko after CCI. Nitrotyrosine levels increased after CCI in wt and ko versus respective uninjured —this increase was more pronounced in wt (2.34±0.95 versus 1.27±0.49 pmol/mg protein, P<0.05). Increased 3NT immunoreactivity was detected in wt versus iNOS ko at 72 h after CCI, and colocalized with macrophage marker and MPO. Our data support a role for iNOS-derived NO as an endogenous antioxidant after CCI. iNOS also contributes protein nitrosylation and nitration. Colocalization of 3NT with macrophages and MPO suggests generation of nitrating agents by macrophages and/or phagocytosis of nitrated proteins.
Protein Kinase C Delta Cleavage Initiates an Aberrant Signal Transduction Pathway after Cardiac Arrest and Oxygen Glucose Deprivation
Authors: Raval Ami P. , Dave Kunjan R. , Prado Ricardo , Katz Laurence M. , Busto Raul , Sick Thomas J. , Ginsberg Myron D. , Mochly-Rosen Daria , Pérez-Pinzón Miguel A.
Published: February 2005

Protein kinase C (PKC) isozymes have been known to mediate a variety of complex and diverse cellular functions. δPKC has been implicated in mediating apoptosis. Using two models of cerebral ischemia, cardiac arrest in rats and oxygen glucose deprivation (OGD) in organotypic hippocampal slices, we tested whether an ischemic insult promoted δPKC cleavage during the reperfusion and whether the upstream pathway involved release of cytochrome c and caspase 3 cleavage. We showed that cardiac arrest/OGD significantly enhanced δPKC translocation and increased its cleavage at 3 h of reperfusion. Since δPKC is one of the substrates for caspase 3, we next determined caspase 3 activation after cardiac arrest and OGD. The maximum decrease in levels of procaspase 3 was observed at 3 h of reperfusion after cardiac arrest and OGD. We also determined cytochrome c release, since it is upstream of caspase 3 activation. Cytochrome c in cytosol increased at 1 h of reperfusion after cardiac arrest/OGD. Inhibition of either δPKC/caspase 3 during OGD and early reperfusion resulted in neuroprotection in CA1 region of hippocampus. Our results support the deleterious role of δPKC in reperfusion injury. We propose that early cytochrome c release and caspase 3 activation promote δPKC translocation/cleavage.
Regional Heterogeneity of 5-HT1A Receptors in Human Cerebellum as Assessed by Positron Emission Tomography
Authors: Parsey Ramin V , Arango Victoria , Olvet Doreen M , Oquendo Maria A , Van Heertum Ronald L , Mann J John
Published: February 2005

Two measures used in brain imaging are binding potential (BP) and the specific to nonspecific equilibrium partition coefficient ( V3“). V3” determined using the 5-HT1A ligand [11C]WAY-100635 is sensitive to changes in the free and nonspecific binding of the ligand in the reference region ( V2). Healthy female volunteers have higher 5-HT1A BP but not V3“ compared with men, because V2 is higher in women. While there could be several explanations for this observation, we hypothesized that women have more 5-HT1A receptors in the cerebellum. We explore the cerebellum to define a subregion that more accurately represents the free and nonspecific binding, potentially allowing the use of V3”. A quantitative autoradiogram in human brain using [3H]WAY-100635 identified a cerebellar subregion devoid of 5-HT1A receptors. In vivo 5-HT1A receptors were evaluated using [11C]WAY-100635 in 12 healthy women and 13 healthy men. Each subject had a metabolite-corrected arterial input function. The autoradiogram demonstrates the lowest concentration of 5-HT1A receptors in the cerebellar white matter (CW) and highest concentration in the cerebellar vermis (CV). The CW volume of distribution ( VT) is lower than CV. Cerebellar white matter is adequately modeled by a one-tissue compartmental model, while a two-tissue model is necessary to model CV or the total cerebellum (CT). Women have a higher CW VT compared with men, suggesting a difference in V2. Use of CW improves identifiability and time stability of BP in cortical regions. Cerebellar white matter might be a better reference region for use in future 5-HT1A studies using [11C]WAY-100635. With CW as a reference region, V3“ cannot be used to detect differences in 5-HT1A receptors between men and women, suggesting the need for arterial input functions to determine BP.
Spontaneous T Wave Alternans in a Patient with Brugada Syndrome—Responses to Intravenous Administration of Class I Antiarrhythmic Drug, Glucose Tolerance Test, and Atrial Pacing
Authors: NISHIZAKI MITSUHIRO , FUJII HIROYUKI , SAKURADA HARUMIZU , KIMURA AKINORI , HIRAOKA MASAYASU
Published: February 2005

A 43‐year‐old man with an episode of syncope showed ECG patterns of coved‐type ST elevation in leads V1–V3 and right bundle branch block pattern. The patient had spontaneous T wave alternans at baseline, and T wave alternans diminished with distinct development of ST elevation after administration of Na+ channel blocker, and during oral glucose load and atrial pacing. Na+ channel mutation may contribute to the genesis of his ECG changes.
Short Atrioventricular Mahaim Fibers: Observations on Their Clinical, Electrocardiographic, and Electrophysiologic Profile
Authors: STERNICK EDUARDO BACK , FAGUNDES MÁRCIO L. , CRUZ FERNANDO E.S. , TIMMERMANS CARL , SOSA EDUARDO A. , RODRIGUEZ LUZ‐MARIA , GERKEN LUIZ M. , SCANAVACCA MAURÍCIO I. , WELLENS HEIN J.J.
Published: February 2005

Introduction: A short atrioventricular decrementally conducting accessory pathway is an uncommon variant of preexcitation. Available data from small series suggest that their decremental properties might not be caused by A‐V nodal‐like tissue.

Methods: We compared clinical, electrocardiographic and electrophysiologic parameters in two groups of patients: 8 patients with a short A‐V Mahaim pathway (Group A), and 33 patients with atriofascicular pathways (Group B). Radiofrequency catheter ablation was carried out guided by activation mapping at the annulus in Group A patients and targeting the “M” potential in Group B patients.

Results: After ablation of all associated rapidly conducting bypass tracts, 7 of the 8 Group A patients showed clear preexcitation. In only 1 of 8 patients the short A‐V Mahaim fiber was actively engaged in a reentrant tachycardia circuit. During radiofrequency catheter ablation an automatic rhythm occurred in 4 of 8 patients. Intravenous adenosine caused conduction a block in the Mahaim fiber in 3 of the 5 patients tested. In group B, no patient showed clear preexcitation (P < 00001) while 72% had a minimal preexcitation pattern. Twenty‐nine of the 33 patients had a circus movement tachycardia with AV conduction over the atriofascicular fiber. During radiofrequency catheter ablation 30 of 33 patients showed accessory pathway automaticity. Adenosine caused transient block at the atriofascicular pathway in 11 (92%) of the 12 patients tested.

Conclusions: While short decrementally conducting right‐sided accessory pathways show a typical ECG pattern different from atriofascicular pathways, their electrophysiologic properties do not seem to be uniform. Those pathways can be successfully interrupted by catheter ablation.
Mechanism of Propensity to Atrial Fibrillation in Patients Undergoing Isthmus Ablation for Typical Atrial Flutter
Authors: RAMANNA HEMANTH , DE BAKKER JACQUES M.T. , HAUER RICHARD N.W.
Published: February 2005

Background: Patients undergoing isthmus ablation for atrial flutter (AFL) may reveal postablation atrial fibrillation (AF). The electrophysiological mechanism is unclear. In patients with idiopathic AF, enhanced spatial dispersion of right atrial refractoriness was the substrate for the initiation of AF. We hypothesize that dispersion of right atrial refractoriness in patients undergoing AFL ablation is the major cause of postablation AF.

Methods: Consecutive patients (n = 42) undergoing isthmus ablation for typical AFL were included. Twelve right atrial unipolar electrograms were recorded. Inducibility of AF was assessed by a pacing protocol, starting with one extrastimulus, followed by more aggressive pacing until AF was induced. Mean fibrillatory intervals were used to assess local refractoriness of each recording site. Spatial dispersion of right atrial refractoriness was calculated as the coefficient of dispersion (CD‐value: standard deviation of the mean of all local mean fibrillatory intervals as a percentage of the overall mean fibrillatory interval). A CD‐value of 3.0 or less was defined as normal, whereas CD‐value greater than 3.0 was considered enhanced dispersion. PES and refractoriness analysis were followed by isthmus ablation.

Results: Of the 42 patients, 29 had CD‐value of 3.0 or less. In these 29 patients, AF was induced with 1 extrastimulus in only 1 patient, with 2 extrastimuli in 4 patients and burst pacing was required to induce AF in 24 of these 29 patients. Prior to the procedure, 5 of 29 patients had AF episodes, after ablation 6 of 29 patients. Of the 42 patients, 13 had CD‐value greater than 3.0, AF was induced with a single extrastimulus in 11 patients, with 2 extrastimuli in the remaining 2 patients. Of the 13 patients, 11 had AF episodes both before and after ablation (P < 0.001).

Conclusion: Enhanced spatial dispersion of right atrial refractoriness may be the substrate for propensity to AF in patients with AFL. The substrate was associated with enhanced inducibility of atrial fibrillation.
Defibrillation Depends on Conductivity Fluctuations and the Degree of Disorganization in Reentry Patterns
Authors: PLANK GERNOT , LEON L. JOSHUA , KIMBER SHANE , VIGMOND EDWARD J.
Published: February 2005

Introduction: Cardiac fibrillation is the deterioration of the heart's normally well‐organized activity into one or more meandering spiral waves, which subsequently break up into many meandering wave fronts. Delivery of an electric shock (defibrillation) is the only effective way of restoring the normal rhythm. This study focuses on examining whether higher degrees of disorganization requires higher shock strengths to defibrillate and whether microscopic conductivity fluctuations favor shock success.

Methods and Results: We developed a three‐dimensional computer bidomain model of a block of cardiac tissue with straight fibers immersed in a conductive bath. The membrane behavior was described by the Courtemanche human atrial action potential model incorporating electroporation and an acetylcholine‐ (ACh) dependent potassium current. Intracellular conductivities were varied stochastically around nominal values with variations of up to 50%. A single rotor reentry was initiated and, by adjusting the spatial ACh variation, the level of organization could be controlled. The single rotor could be stabilized or spiral wave breakup could be provoked leading to fibrillatory‐like activity. For each level of organization, multiple shock timings and strengths were applied to compute the probability of shock success as a function of shock strength.

Conclusions: Our results suggest that the level of the small‐scale conductivity fluctuations is a very important factor in defibrillation. A higher variation significantly lowers the required shock strength. Further, we demonstrated that success also heavily depends on the level of organization of the fibrillatory episode. In general, higher levels of disorganization require higher shock strengths to defibrillate.
Response to Pharmacological Challenge of Dissociated Pulmonary Vein Rhythm
Authors: MARROUCHE NASSIR , WAZNI OUSSAMA M. , MARTIN DAVID O. , ROSSILLO ANTONIO , SALIBA WALID , ERCIYES DEMET , SCHWEIKERT ROBERT , KHAYKIN YAARIV , BURKHARDT DAVID , BHARGAVA MANDEEP , VERMA ATUL , ABDUL‐KARIM AHMAD , NATALE ANDREA
Published: February 2005

Introduction: Characterization of the electrophysiologic behavior of the pulmonary vein (PV) triggers initiating atrial fibrillation (AF) is still lacking. We conducted the current study to evaluate the behavior of the dissociated PV rhythm (PVD) observed after electrical disconnection from the left atrium of the PV responsible for initiation of AF.

Methods and Results: Four hundred and seven consecutive patients (102 women; mean age 55 ± 11 years) presented for ablation of symptomatic AF to our laboratory. After isolation, sustained dissociated rhythm (>10 minutes) was documented in 2.1% (34 of 1568 PVs) of the PVs (initiating AF prior to isolation). Adenosine (18 mg IV bolus), verapamil (10 mg IV bolus), phenylephrine (200 mcg bolus followed by infusion at 100 mcg/hour), and isoproterenol (infusion rate of 15 mcg/hour) were administered in these patients. The cycle length of the PV rhythm before and after the administration of drugs was measured. Adenosine prolonged the sinus node (SN) cycle length (from 750 ± 105 to 1,900 ± 200 ms; P < 0.05) and suppressed the PVD. Isoproterenol shortened both the SN (from 750 ± 105 to 420 ± 150 ms; P < 0.05) and the PVD (from 2,225 ± 300 to 800 ± 190 ms; P < 0.05) cycle length. A similar response to adenosine and isoproterenol of the PV firing was observed prior to isolating the arrhythmogenic PV. Phenylephrine prolonged the cycle length of both the SN (from 740 ± 115 to 960 ± 90 ms; P < 0.05) and the PV rhythm (from 2,200 ± 300 to 2,355 ± 280 ms; P = 0.87). Verapamil did not cause a significant change either in the SN or in the PVD cycle length.

Conclusion: Our data suggest that the PVD within isolated PV responsible for initiating AF exhibits a response to pharmacologic agents similar to the SN cells.
Multiple Pacing Lead‐Induced Superior Vena Cava Syndrome: Successful Treatment by Balloon Angioplasty
Authors: PARK HYUNG‐WOOK , KIM WEON , CHO JEONG‐GWAN , KANG JUNG‐CHAEE
Published: February 2005

The superior vena cava (SVC) syndrome is an uncommon but sometimes serious complication associated with permanently implanted pacemakers. The mechanical stress associated with pacemaker wires may lead to vessel wall inflammation, fibrosis, thrombus formation, and, ultimately, venous stenosis and occlusion. The surgical treatment of pacemaker‐related SVC syndrome requires thoracotomy and may result in significant morbidity. The long‐term effects on the pacemaker electrodes, due to compression between the stent and the wall of the vein, remain unknown. We describe a case in which balloon venoplasty successfully resolved the SVC syndrome. The patient has remained symptom‐free and with normal pacemaker function for 6 months.
Calcium Channel Antagonism Reduces Exercise‐Induced Ventricular Arrhythmias in Catecholaminergic Polymorphic Ventricular Tachycardia Patients with RyR2 Mutations
Authors: SWAN HEIKKI , LAITINEN PÄIVI , KONTULA KIMMO , TOIVONEN LAURI
Published: February 2005

Introduction: Recently, gain‐of‐function mutations of cardiac ryanodine receptor RyR2 gene have been identified as a cause of familial or catecholaminergic polymorphic ventricular tachycardia. We examined the influence of the calcium channel blockers, verapamil and magnesium, on exercise‐induced ventricular arrhythmias in patients with RyR2 mutations.

Methods and Results: Six molecularly defined catecholaminergic polymorphic ventricular tachycardia patients, all carrying a RyR2 mutation and on β‐adrenergic blocker therapy, underwent exercise stress test four times: at baseline, after verapamil and magnesium sulphate infusions, and finally, without interventions. The number of isolated and successive premature ventricular complexes during exercise ranged from 40 to 374 beats (mean 165 beats) at baseline, and was reduced during verapamil by 76 ± 17% (P < 0.05). Premature ventricular complexes appeared later and at higher heart rate during verapamil than at baseline (119 ± 21 vs. 127 ± 27 min−1, P < 0.05). Magnesium did not inhibit the arrhythmias. Results in the fourth exercise stress test without interventions were similar to those in the first baseline study.

Conclusions: This study provides the first in vivo demonstration that a calcium channel antagonist, verapamil, can suppress premature ventricular complexes and nonsustained ventricular salvoes in catecholaminergic polymorphic ventricular tachycardia caused by RyR2 mutations. Modifying the abnormal calcium handling by calcium antagonists might have therapeutic value.
Effects of Temporal Application Parameters on Lesion Dimensions During Transvenous Catheter Cryoablation
Authors: TSE HUNG‐FAT , RIPLEY KENNETH L. , LEE KATHY L.F. , SIU CHUNG‐WAH , VAN VLEET JOHN F. , PELKEY WILLIAM L. , LAU CHU‐PAK
Published: February 2005

Background: Transvenous catheter cryoablation is a novel technique for treating cardiac arrhythmias. However, the relative importance of temporal application parameters on lesion dimension and clinical efficacy has not been studied.

Methods and Results: We investigated the effects of (1) application duration: single 2.5 (2.5 × 1) versus single 5 versus double 2.5 (2.5 × 2) versus double 5 (5 × 2) minutes, (2) number of freeze–thaw cycles: single versus double, and (3) electrode contact area: horizontal versus vertical orientation, on the lesion diameter and depth during catheter cryoablation (10F, 6.5‐mm tip‐electrode, CryoCor™, San Diego) in a thigh muscle preparation. A total of 175 lesions (horizontal = 90, vertical = 85) were created in thigh muscle preparations on 10 swine. The lesion diameter and depth were significantly greater using 2.5 × 2 and 5 × 2 application modes as compared with 2.5 × 1 applications (P < 0.05). Horizontal tip‐electrode orientation produced larger lesion diameter (P < 0.05), but not lesion depth as compared with vertical orientation. Multivariate analysis demonstrated that both tip‐electrode orientation and duration of freeze >2.5 minutes were independent predictors for lesion diameter (P < 0.001). However, only duration of freeze >2.5 minutes was an independent predictor for lesion depth (P < 0.001).

Conclusions: The dimensions of lesions created by catheter cryoablation are affected by mode of cryoablation application and electrode orientation. Increasing the duration of application, employing multiple freeze–thaw cycles at shorter cycle durations, and orienting the catheter to enhance/increase tissue contact can create a larger lesion.
Topographic Variability of the Esophageal Left Atrial Relation Influencing Ablation Lines in Patients with Atrial Fibrillation
Authors: KOTTKAMP HANS , PIORKOWSKI CHRISTOPHER , TANNER HILDEGARD , KOBZA RICHARD , DORSZEWSKI ANJA , SCHIRDEWAHN PETRA , GERDS‐LI JIN‐HONG , HINDRICKS GERHARD
Published: February 2005

Introduction: The close anatomic relationship of the posterior wall of the left atrium (LA) and the thermosensitive esophagus creates a potential hazard in catheter ablation procedures.

Methods and Results: In 30 patients (pts) with atrial fibrillation (AF) undergoing catheter ablation, we prospectively studied the course and contact of the esophagus in relation to LA and the topographic proximity to ablation lines encircling the right‐sided and left‐sided pulmonary veins (PV) as well as to the posterior line connecting the encircling lines using the electromagnetic mapping system for reconstruction of LA and for tagging of the esophagus. This new technique of anatomic tagging of the esophagus was validated against the CT scan as a standard imaging procedure. The esophageal course was highly variable, extending from courses in direct vicinity to the left‐ or right‐sided PV as well as in the midportion of the posterior LA. In order to avoid energy application in direct proximity to the esophagus, adjustments of the left and right PV encircling lines were necessary in 14/30 pts (47%) and 3/30 (10%). In 30 pts (100%), the mid‐ to inferior areas of the posterior LA revealed contact with the esophagus. Therefore, posterior and inferior linear ablation lines were abandoned and shifted to superior in 29 pts (97%).

Conclusions: Anatomic tagging of esophagus revealed a highly variable proximity to different areas of the posterior LA suggesting individual adjustment of encircling and linear ablation lines in AF ablation procedures to avoid the life threatening complication of esophagus perforation.
Right and Left Ventricular Activation Sequence in Patients with Heart Failure and Right Bundle Branch Block: A Detailed Analysis Using Three‐Dimensional Non‐Fluoroscopic Electroanatomic Mapping System
Authors: FANTONI CECILIA , KAWABATA MIHOKO , MASSARO RAIMONDO , REGOLI FRANCOIS , RAFFA SANTI , ARORA VANITA , SALERNO‐URIARTE JORGE A. , KLEIN HELMUT U. , AURICCHIO ANGELO
Published: February 2005

Introduction: Recently, right bundle branch block (RBBB) was proved to be an important predictor of mortality in heart failure (HF) patients as much as left bundle branch block (LBBB). We characterized endocardial right ventricular (RV) and left ventricular (LV) activation sequence in HF patients with RBBB using a three‐dimensional non‐fluoroscopic electroanatomic contact mapping system (3D‐Map) in order to provide the electrophysiological background to understand whether these patients can benefit from cardiac resynchronization therapy (CRT).

Methods and Results: Using 3D‐Map, RV and LV activation sequences were studied in 100 consecutive HF patients. Six of these patients presented with RBBB QRS morphology. The maps of these patients were analyzed and compared post hoc with those of the other 94 HF patients presenting with LBBB. Clinical and hemodynamic profile was significantly worse in RBBB group compared to LBBB. Patients with RBBB showed significantly longer time to RV breakthrough (P < 0.001), longer activation times of RV anterior and lateral regions (P < 0.001), and longer total RV endocardial activation time (P < 0.02) compared to patients with LBBB. Time to LV breakthrough was significantly shorter in patients with RBBB (P < 0.001), while total and regional LV endocardial activation times were not significantly different between the two groups.

Conclusions: Degree of LV activation delay is similar between HF patients with LBBB and RBBB. Moreover, patients with RBBB have larger right‐sided conduction delay compared to patients with LBBB. The assessment of these electrical abnormalities is important to understand the rationale for delivering CRT in HF patients with RBBB.
A density-functional study of the structures, binding energies and total spins of Ni–Fe clusters using nonlocal norm-conserving pseudopotentials and the generalized gradient approximation
Authors: Longo R. C. , Noya E. G. , Gallego L. J.
Published: February 2005

We report ab initio calculations of the structures, binding energies, and total spins of the clusters Ni13, Ni19, Ni23, Ni26, Ni12Fe, Ni11Fe2, Ni18Fe, Ni17Fe2, Ni22Fe, Ni20Fe3, and Ni25Fe using a density-functional method that employs linear combination of atomic orbitals as basis sets, nonlocal norm-conserving pseudopotentials, and the generalized gradient approximation for exchange and correlation. Our results show that the Fe-doped Ni clusters, which have icosahedral or polyicosahedral ground-state structures similar to those of the corresponding pure Ni clusters, are most stable with the Fe atoms occupying internal positions, as has also been inferred from experimental results on the adsorption of molecular nitrogen on the cluster surfaces. We also rule out the possibility that the experimentally observed difference between the (nonpolyicosahedral) configurations of N2-saturated Ni26 and N2-saturated Ni25Fe be due to the influence of the Fe atom on the energy of the underlying metal cluster.
Twisted intramolecular charge transfer states: Rotationally resolved fluorescence excitation spectra of 4,4′-dimethylaminobenzonitrile in a molecular beam
Authors: Nikolaev A. E. , Myszkiewicz G. , Berden G. , Leo Meerts W. , Pfanstiel J. F. , Pratt D. W.
Published: February 2005

We report the observation at high resolution of seven vibronic bands that appear within ∼200cm−1 of the electronic origin in the S1-S0 fluorescence excitation spectrum of 4,4′-dimethylaminobenzonitrile (DMABN) in a molecular beam. Surprisingly, each band is found to be split into two or more components by a (coordinated) methyl group tunneling motion which significantly complicates the analysis. Despite this fact, high quality [(Observed−Calculated)⩽30MHz] fits of each of the bands have been obtained, from which the rotational constants, inertial defects, torsion-rotation interaction constants, methyl group torsional barriers, and transition moment orientations of DMABN in both electronic states have been determined. The data show that DMABN is a slightly pyramidalized (∼1°) but otherwise (heavy-atom) planar molecule in its ground S0 state, and that its electronically excited S1 state has both a more pyramidalized (∼3°) and twisted (∼25°) dimethylamino group. Large reductions in the methyl group torsional barriers also show that the S1←S0 electronic transition is accompanied by significant charge transfer from the nitrogen atom to the π∗ orbitals of the aromatic ring. Thereby established is the participation of all three vibrational coordinates in the dynamics leading to the “anomalous” emissive behavior of DMABN in the condensed phase.
Coupled-cluster theory with simplified linear-r12 corrections: The CCSD(R12) model
Authors: Fliegl Heike , Klopper Wim , Hättig Christof
Published: February 2005

A simplified singles-and-doubles linear-r12 corrected coupled-cluster model, denoted CCSD(R12), is proposed and compared with the complete singles-and-doubles linear-r12 coupled-cluster method CCSD-R12. An orthonormal auxiliary basis set is used for the resolution-of-the-identity approximation to calculate three-electron integrals needed in the linear-r12 Ansatz. Basis-set convergence is investigated for a selected set of atoms and small molecules. In a large basis, the CCSD(R12) model provides an excellent approximation to the full linear-r12 energy contribution, whereas the magnitude of this contribution is significantly overestimated at the level of second-order perturbation theory.
A complete configurational study for the bound states of Ne trimers
Authors: Baccarelli I. , Gianturco F. A. , González-Lezana T. , Delgado-Barrio G. , Miret-Artés S. , Villarreal P.
Published: February 2005

The structural properties and the energetics of the ground and the excited bound states of Ne3 for zero total angular momentum are examined using different modelings for the two-body interactions. We employ a method consisting of a variational approach with a distributed Gaussian functions (DGF) basis set expansion. We discuss at length the advantages and possible limitations of such an approach, comparing it to other methods which have been applied in the literature to the same system. The DGF method turns out to be very accurate in giving us the bound states energetics and also provides in a natural way a convincing pictorial description of all the states, including those with dominant linear configurations. Additional bound states are found for the Ne3 system with respect to those indicated in previous works and we suggest a “stabilization” procedure that can be used to assess the truly bound nature of a state. Some considerations on the relative reliability of the examined two-body interactions are also reported.
Comment on “Radiation damage of biosystems mediated by secondary electrons: Resonant precursors for uracil molecules” [J. Chem. Phys. 120, 7446 (2004)]
Authors: Burrow P. D.
Published: February 2005

Resonances computed by Gianturco and Lucchese are incorrectly correlated with those observed experimentally. A shift of their π* resonances by 2 eV gives satisfactory agreement. Arguments for determining whether a resonance is a suitable precursor for the fragmentation products are too simplistic, and in one example, incorrect.
Reaction pathway for the nonadiabatic reaction of Ca(4s3dD1)+H2→CaH(XΣ+2)+H
Authors: Chang Ya-Lan , Chen Li , Hsiao Ming-Kai , Chen Jye-Jong , Lin King-Chuen
Published: February 2005

The reaction pathway and the nascent CaH product distribution in the reaction Ca(4s3dD1)+H2→CaH(XΣ+2)+H are obtained using a pump-probe technique. The Ca atom is first prepared in the 3D1 state by a two-photon absorption, and then in brief time delay the laser-induced fluorescence of the reaction product CaH is monitored. The CaH(v=0,1) distributions appear to be single peaked, as characterized by Boltzmann rotational temperature of 807±38K(v=0) and 684±77K(v=1). The vibrational population ratio of CaH(v=0)/CaH(v=1) is determined to be 3.3±0.1, while the v=2 population is not detectable. The fractions of the available energy partitioning into rotation, vibration, and translation are estimated to be 0.36±0.05, 0.28±0.04, and 0.36±0.05, respectively. With the aid of the potential energy surfaces calculations, the current reaction should favor a near C2v collision configuration. The temperature dependence measurement yields a positive slope, indicative of the reaction occurrence without any potential barrier. The colliding species are anticipated to follow an attractive 1B2 (or 2A′) surface and then transit nonadiabatically to the reactive ground state surface.
Non-quadratic-intensity dependence of two-photon absorption induced fluorescence of organic chromophores in solution
Authors: Wang C. H. , Tai Oliver Y.-H. , Wang Yuxiao , Tsai Tsung-Hsiu , Chang Nein-Chen
Published: February 2005

We have provided a model to interpret the non-quadratic-intensity dependence behavior commonly observed in the two-photon fluorescence (TPF) experiment excited with high laser intensity. The model also provides one with a different technique to measure the two-photon absorption cross section of an organic chromophore in solution. In contrast to the commonly used low intensity technique that depends on the quadratic-intensity law, the present technique is based on the non-quadratic-intensity dependence of two-photon fluorescence. Auxiliary data such as two-photon quantum efficiency and fluorescence collection efficiency, essential in the low intensity method, are not required in the present technique. TPF measurements of Rhodamine B in methanol are carried out to demonstrate the validity of the present method. The method is used to determine the two-photon absorption cross section of a new chromophore attached with tricyano-derivatized furan as the electron acceptor. The two-photon absorption cross section measured using this method is also compared with that using a conventional transmission technique.
Statistical and nonstatistical nonadiabatic photodissociation from the first excited state of the hydroxymethyl radical
Authors: Yarkony David R.
Published: February 2005

Photodissociation of hydroxymethyl (H2COD) from the first excited state, a Rydberg 3s state, can produce either H+HCOD or H2CO+D. These processes involve a seam of conical intersections. An analysis of the seam is reported based on a pointwise determination of the three gradient vectors that characterize a conical intersection: the energy difference gradient and the coupling gradient, which span the branching space, and the gradient of the average energy. These data are used to understand why H, but not D is produced at energies near threshold, the difference in the recoil anisotropy for H and D dissociation, and whether H or D will be produced impulsively or after formation of an intermediate complex.
Computer simulation study of intermolecular voids in unsaturated phosphatidylcholine lipid bilayers
Authors: Rabinovich A. L. , Balabaev N. K. , Alinchenko M. G. , Voloshin V. P. , Medvedev N. N. , Jedlovszky P.
Published: February 2005

Computer simulation of the liquid crystalline phase of five different hydrated unsaturated phosphadidylcholine (PC) lipid bilayers, i.e., membranes built up by 18:0∕18:1ω9cis PC, 18:0∕18:2ω6cis PC, 18:0∕18:3ω3cis PC, 18:0∕20:4ω6cis PC, and 18:0∕22:6ω3cis PC molecules have been performed on the isothermal-isobaric ensemble at 1atm and 303K. (The notation n:dωpcis specifies the lipid tails: n refers to the total number of carbon atoms in the chain, d is the number of the methylene-interrupted double bonds, p denotes the number of carbons between the chain terminal CH3 group and the nearest double bond, and cis refers to the conformation around the double bonds.) The characteristics of the free volume in these systems have been analyzed by means of a generalized version of the Voronoi–Delaunay method [M. G. Alinchenko et al., J. Phys. Chem. B 108, 19056 (2004)]. As a reference system, the hydrated bilayer of the saturated 14:0∕14:0 PC molecules (dimyristoylphosphatidylcholine) has also been analyzed. It has been found that the profiles of the fraction of the free volume across the membrane exhibit a rather complex pattern. This fine structure of the free volume fraction profiles can be interpreted by dividing the membrane into three separate major zones (i.e., zones of the aqueous, polar, and apolar parts of the membrane) and defining five subzones within these zones according to the average position of various atomic groups in the membrane. The fraction of the free volume in the middle of the membrane is found to increase with increasing unsaturation of the sn-2 chain of the lipid molecule. This is due to the fact that with increasing number of methylene-interrupted double bonds the lipid tails become more flexible, and hence they do not extend to the middle of the membrane. It is found that there are no broad enough preformed channels in the bilayers through which small penetrants, such as water molecules, can readily go through; however, the existing channels can largely facilitate the permeation of these molecules.
Laser control of electronic transitions of wave packet by using quadratically chirped pulses
Authors: Zou Shiyang , Kondorskiy Alexey , Mil’nikov Gennady , Nakamura Hiroki
Published: February 2005

An effective scheme is proposed for the laser control of wave packet dynamics. It is demonstrated that by using specially designed quadratically chirped pulses, fast and nearly complete excitation of wave packet can be achieved without significant distortion of its shape. The parameters of the laser pulse can be estimated analytically from the Zhu–Nakamura theory of nonadiabatic transition. If the wave packet is not too narrow or not too broad, then the scheme is expected to be utilizable for multidimensional systems. The scheme is applicable to various processes such as simple electronic excitation, pump-dump, and selective bond breaking, and it is actually numerically demonstrated to work well by taking diatomic and triatomic molecules (LiH, NaK, H2O) as examples.
Cavity ring-down spectroscopy and theoretical calculations of the S1(B3u1)←S(Ag1) transition of jet-cooled perylene
Authors: Tan Xiaofeng , Salama Farid
Published: February 2005

As part of our long-term program to test the diffuse interstellar band–polycyclic aromatic hydrocarbon hypothesis, we have investigated the S1←S0 electronic transition of neutral perylene (C20H12) in a combined experimental and theoretical study. Jet-cooled perylene was prepared with a pulsed discharge slit nozzle and detected by cavity ring-down spectroscopy. A number of vibronic features were observed in the 24000–24900cm−1 spectral range. Density functional and ab initio calculations were performed to determine the geometries, harmonic vibrational frequencies, and normal coordinates of both the S0 and S1 electronic states. A rotational temperature of 52±5K was derived from a rotational contour analysis of the vibronic band associated with the 0-0 transition. A Franck–Condon treatment was carried out to calculate the vibronic spectrum of the S1←S0 transition. A good agreement was found between the calculated and the experimental spectra. A vibrational assignment is proposed and six normal modes are identified. The contribution of neutral compact polycyclic aromatic hydrocarbons to the diffuse interstellar bands is briefly discussed.
Influence of junction temperature on chromaticity and color-rendering properties of trichromatic white-light sources based on light-emitting diodes
Authors: Chhajed S. , Xi Y. , Li Y.-L. , Gessmann Th. , Schubert E. F.
Published: February 2005

Trichromatic white-light sources based on light-emitting diodes (LEDs) offer a high luminous efficacy of radiation, a broad range of color temperatures and excellent color-rendering properties with color-rendering indices (CRIs) exceeding 85. An analysis of the luminous efficacy and CRI of a trichromatic light source is performed for a very broad range of wavelength combinations. The peak emission wavelength, spectral width, and the output power of LEDs strongly depend on temperature and the dependencies for red, green, and blue LEDs are established. A detailed analysis of the temperature dependence of trichromatic white LED sources reveals that the luminous efficacy decreases, the color temperature increases, the CRI decreases and the chromaticity point shifts towards the blue as the junction temperature increases. A high CRI>80 can be maintained, by adjusting the LED power ratio so that the chromaticity point is conserved.
Ultrafast tabletop laser-pump–x-ray probe measurement of solvated Fe(CN)64−
Authors: Lee Taewoo , Jiang Yan , Rose-Petruck Christoph G. , Benesch Frank
Published: February 2005

We report on the first ultrafast laser-pump–picosecond x-ray probe measurements of solvated transition metal complexes carried out with a tabletop ultrafast laser-driven plasma x-ray source. The x-ray absorption fine structure (XAFS) spectra of Fe(CN)64− solvated in water have been measured before and tens of picoseconds after photoexcitation with ultrashort UV laser pulses. The XAFS spectra after photoexcitation exhibits a K-edge shift indicating the increase of the iron-ligand distances. Reference spectra of Fe(CN)64− and Fe(CN)63− measured at a synchrotron source yield structural data that show static solvation-induced bond length changes of the metal complexes.
Comparison of two genres for linear scaling in density functional theory: Purification and density matrix minimization methods
Authors: Jordan Daniel K. , Mazziotti David A.
Published: February 2005

Two classes of linear-scaling methods to replace diagonalization of the one-particle Hamiltonian matrix in density functional theory are compared to each other. Purification takes a density matrix with the correct eigenfunctions and corrects the occupation numbers; density matrix minimization takes a density matrix with correct occupation numbers and corrects the eigenfunctions by rotating the orbitals. Computational comparisons are performed through modification of the MondoSCF program on water clusters and the protein endothelin. A purification scheme and a density matrix minimization scheme, based on the 1,2-contracted Schrödinger equation [D. A. Mazziotti, J. Chem. Phys. 115, 8305 (2001)] are implemented in large systems.
Improved dissociation energy of the K39Rb85 molecule
Authors: Stwalley William C.
Published: February 2005

The predissociation data for the 1Π1 state of K39Rb85 of Kasahara et al. [J. Chem. Phys. 111, 8857 (1999)] are combined with the recent determination of the long range C6 coefficients of the predissociating 2Σ+3∼2(0−), 2(1) states [Wang et al., Eur. Phys. J. D31, 165 (2004) ] molecule: to infer a more precise dissociation energy of the K39Rb85 molecule D0=4180.06±0.42cm−1 and De=4217.91±0.42cm−1.