bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three Year Outcome of Cardiac Resynchronization Therapy: A Single Center Evaluation
Authors: STÅHLBERG MARCUS , BRAUNSCHWEIG FRIEDER , GADLER FREDRIK , KARLSSON HELENA , LINDE CECILIA 
Published: October 2005

Aims: To evaluate the long‐term clinical outcome and device performance of cardiac resynchronization therapy in a consecutive sample of patients with moderate to severe heart failure.
Methods and Results: Between 1998 and 2000, forty consecutive patients with drug‐refractory heart failure due to ischemic or idiopathic dilated cardiomyopathy were selected for cardiac resynchronization therapy (CRT). After successful implantation of the coronary sinus lead (n = 35, 88%), patients were followed every sixth month by New York Heart Association (NYHA) functional class, the 6‐minute walking test (6´ walk), quality of life (QoL, Minnesota), and pacemaker control. NYHA‐class and 6´ walk were significantly improved after 6 months and continued to improve gradually until 36 months of follow‐up. The QoL improvement at 6 months was sustained over 3 years. After 3 years, the β‐blocker dose could be increased in 10/23 patients as compared to baseline. Nine patients had to be re‐operated. Coronary sinus lead thresholds were stable over time.
Conclusion: The clinical improvements by CRT are sustained over 3 years of follow‐up. In the setting of a University Medical Center, CRT can be applied in clinical routine with excellent clinical outcome, acceptable implantation success, and stable device performance over time.
Recurrence of Atrial Tachyarrhythmias in Implantable Cardioverter‐Defibrillator Recipients
Authors: DARBAR DAWOOD , WARMAN EDUARDO N. , HAMMILL STEPHEN C. , FRIEDMAN PAUL A. ,   for the Worldwide Jewel AF Investigators
Published: October 2005

Background:
Because the natural history of atrial tachyarrhythmia (AT) is not known in patients with implantable cardioverter‐defibrillators (ICDs) but without device‐based atrial therapies, we aimed to describe the characteristics and recurrence of AT in such patients.
Methods:
In this multicenter trial, 269 patients with standard indications for ICD placement and 2 episodes of AT in the preceding year received a dual‐chamber ICD capable of logging AT. Patients were randomly assigned to 3‐month periods of atrial therapies “on” or “off.” This analysis considered only the 118 patients with atrial therapies programmed off at ICD placement.
Results:
Fifty‐eight patients (49%) had at least 1 AT episode longer than 1 minute, and 21 (18%) had at least 1 prolonged episode (>24 hours). The median episode frequency for each patient (episodes per month) was 1.8 episodes longer than 1 minute, 0.8 longer than 1 hour, and 0 longer than 24 hours. The median AT burden was 12.2 hours per month.
Conclusions:
Patients with standard ICD indications and history of AT have infrequent episodes, frequent short episodes, or prolonged episodes of AT‐atrial fibrillation. However, the clinical characteristics examined did not distinguish among the groups. Improved diagnostic tools may help identify patients at risk for development of AT, thereby allowing specific therapies to be targeted to each group of patients.
Magnetic Resonance Angiography of Pulmonary Veins: Implications for Catheter Ablation of Atrial Fibrillation
Authors: MLČOCHOVÁ HANKA , TINTĚRA JAROSLAV , POROD VÁCLAV , PEICHL PETR , ČIHÁK ROBERT , KAUTZNER JOSEF 
Published: October 2005

Introduction:
Catheter ablation of atrial fibrillation (AF) requires exact anatomical information about pulmonary venous (PV) ostia. In this study, anatomy of pulmonary veins (PVs) was assessed using three‐dimensional (3D) reconstructions of magnetic resonance angiography (MRA).
Methods and Results:
Contrast‐enhanced MRA of the PVs was performed in 40 patients (mean age 53 ± 9 years) with paroxysmal (30 patients) or persistent (10 patients) AF, scheduled for circumferential ablation around PV ostia. PV ostial anatomy and diameters were evaluated from multiplanar reconstructions and compared with 3D reconstructions. Thirty (75%) patients presented with a common left‐sided antrum (21 short and 9 long trunk), while additional PVs were found on right side in 23%. PV ostia were oblong in shape (mean diameters 17.0 ± 4.3 vs 10.5 ± 2.5 mm by two‐dimensional (2D) measurements, and 20.8 ± 7.6 mm vs 12.9 ± 3.3 mm by 3D reconstruction, in long and short axis, respectively). There was a correlation between measurements obtained from 2D and 3D images, although 3D imaging provided slightly larger diameters.
Conclusions:
MRA with 3D reconstructions is an important technique for preprocedural assessment of PVs that allows full understanding of their anatomy and size. This information may be important for selection of appropriate tools.
Electrophysiologic Characteristics of Atria in Patients Without Heart Disease
Authors: BREMBILLA‐PERROT BÉATRICE , BEURRIER DANIEL , HOURIEZ PIERRE , SUTY‐SELTON CHRISTINE , NIPPERT MARC , CLAUDON OLIVIER , ANDRONACHE MARIUS , ERNST YVES , KHALDI EMAD , BELHAKEM HADJ , POPOVIC BATRIC , DE LA CHAISE ARNAUD TERRIER , LOUIS PIERRE 
Published: October 2005

Background: The significance of atrial fibrillation or tachycardia (AF) induction remains debatable. Some believe that the presence of heart disease (HD) increases the sensitivity and decreases the specificity of programmed atrial stimulation (PAS). There are few data in patients without HD. The purpose of the study was to evaluate the results of PAS in asymptomatic patients without HD and in those with documented spontaneous AF, but without HD, to know the diagnosis value of the technique.
Methods: A total of 4,900 PAS were consecutively performed. The control group (I, N=67) was defined by the absence of preexcitation syndrome, dizziness/syncope, hypertension, history of tachycardia, or other documented HD together with a normal 2D echocardiogram and 24‐hour Holter monitoring. They were compared to a group (II) of 54 patients with documented paroxysmal AF and without HD. PAS used one and two extrastimuli, delivered during sinus rhythm and two drive rates (600, 400 ms). Atrial‐effective refractory periods (ARP), their adaptation to cycle length, and conduction times were noted. AF induction was defined as the induction of AF lasting more than 1 minute.
Results: Group I patients (1.4% of 4,900) were younger than group II (51 ± 17 vs 65 ± 11 years, P < 0.001). A single extrastimulus never induced sustained AF in group I, but did so in 11 group II patients (20%); sustained AF was induced by two extrastimuli in 15 group I patients (22%) and in 31 group II patients (57%) (P < 0.001). There were no ARP and conduction time differences in group I patients with and without inducible AF, but there was a longer sinus cycle length in patients with inducible AF (977 ± 164 vs 838 ± 141 ms, P < 0.02). There were no electrophysiological differences in group II patients with and without inducible AF. No group I patient developed spontaneous AF (follow‐up 4 ± 2 years). The sensitivity of PAS with one extrastimulus was 20% and the specificity 100%; the sensitivity of PAS with two extrastimuli was 57% and the specificity 78%.
Conclusion: Sustained AF was not induced by one extrastimulus in control patients without symptoms, nor heart disease, but sustained AF was induced by two extrastimuli in 22% of these patients. The induction of a sustained AF by two extrastimuli should be interpreted cautiously, particularly in patients with a relative sinus bradycardia. However, the sensitivity of PAS with one extrastimulus was very low and two extrastimuli were required in patients with spontaneous AF to induce the tachycardia. Other electrophysiological parameters were not useful to differentiate patients with and without inducible AF.
Effects of Δ12‐prostaglandin J2 on bone regeneration and growth factor expression in rats
Authors: Damrongsri Damrong , Geva Sarah , Salvi Giovanni E. , Cooper Lyndon F. , Limwongse Visaka , Offenbacher Steven 
Published: October 2005

AbstractObjectives: Cyclopentenone prostaglandins have been shown to promote osteoblast differentiation in vitro. The aim of this study was to examine in a rat model the effects of local delivery of Δ12‐prostaglandin J2 (Δ12‐PGJ2) on new bone formation and growth factor expression in (i) cortical defects and (ii) around titanium implants.Material and methods: Standardized transcortical defects were prepared bilaterally in the femur of 28 male Wistar rats. Ten microliters of Δ12‐PGJ2 at 4 concentrations (10−9, 10−7, 10−5 and 10−3 mol/l) in a collagen vehicle were delivered inside a half‐cylindrical titanium chamber fixed over the defect. Contralateral defects served as vehicle controls. Ten days after surgery, the amount of new bone formation in the cortical defect area was determined by histomorphometry and expression of platelet‐derived growth factor (PDGF)‐A and ‐B, insulin‐like growth factor (IGF)‐I/II, bone morphogenetic protein (BMP)‐2 and ‐6 was examined by immunohistochemistry. In an additional six rats, 24 titanium implants were inserted into the femur. Five microliters of carboxymethylcellulose alone (control) or with Δ12‐PGJ2 (10−5 and 10−3 mol/l) were delivered into surgically prepared beds prior to implant installation.Results: Δ12‐PGJ2 (10−5 and 10−3 mol/l) significantly enhanced new bone formation (33%, P<0.05) compared with control cortical defects. Delivery of Δ12‐PGJ2 at 10−3 mol/l significantly increased PDGF‐A and ‐B and BMP‐2 and ‐6 protein expression (P<0.05) compared with control defects. No significant difference was found in IGF‐I/II expression compared with controls. Administration of Δ12‐PGJ2 also significantly increased endosteal new bone formation around implants compared with controls.Conclusion: Local delivery of Δ12‐PGJ2 promoted new bone formation in the cortical defect area and around titanium implants. Enhanced expression of BMP‐2 and ‐6 as well as PDGF‐A and ‐B may be involved in Δ12‐PGJ2‐induced new bone formation.
Structures of the O‐polysaccharides and classification of Proteus genomospecies 4, 5 and 6 into respective Proteus serogroups
Authors: Zych Krystyna , Perepelov Andrei V. , Siwiňska Małgorzata , Knirel Yuriy A. , Sidorczyk Zygmunt 
Published: October 2005

An acidic branched O‐polysaccharide was isolated by mild acid degradation of the lipopolysaccharide (LPS) of Proteus genomospecies 4 and studied by sugar and methylation analyses along with 1H and 13C NMR spectroscopy, including 2D COSY, TOCSY, ROESY and H‐detected 1H,13C HSQC experiments. The following structure of the pentasaccharide repeating unit of the O‐polysaccharide was established, which is unique among Proteus polysaccharide structures: where Qui3NAc stands for 3‐acetamido‐3,6‐dideoxyglucose. Based on the O‐polysaccharide structure and serological data, we propose classifying Proteus genomospecies 4 into a new, separate Proteus serogroup, O56. A weak cross‐reactivity of Proteus genomospecies 4 antiserum with LPS of Providencia stuartii O18 and Proteus vulgaris OX2 was observed and is discussed in view of a similarity of the O‐polysaccharide structures. Structural and serological investigations showed that Proteus genomospecies 5 and 6 should be classified into the existing Proteus serogroups O8 and O69, respectively.
The ‘missing’ young stellar objects in the central parsec of the Galaxy: evidence for star formation in a massive accretion disc and a top-heavy initial mass function
Authors: Nayakshin Sergei , Sunyaev Rashid 
Published: October 2005

Abstract
A few dozen young high-mass stars orbit Sgr A* at distances as short as ∼0.1 pc, where star formation should be quenched by the strong tidal shear from Sgr A*. The puzzling young stellar population is believed to come into existence in one of two ways: (i) ‘normal’ star formation at several tens of parsecs in a very massive star cluster that then spiralled in; or (ii) star formation in situ in a massive self-gravitating disc. We propose to constrain these two scenarios via the expected X-ray emission from young low-mass stars that should have formed alongside the massive stars. To this end we compare the recent Chandra observations of X-ray emission from young stars in the Orion nebula, and the Chandra observations of the Sgr A* field. We show that the cluster spiral-in model is ruled out irrespectively of the initial mass function (IMF) of the young stars. In addition, for the in situ model, we find that no more than a few thousand low-mass stars could have formed alongside the massive stars. This is more than a factor of 10 fewer than expected if these stars were formed with the standard IMF as elsewhere in the Galaxy. The young stars in the Galactic Centre are thus the first solid observational evidence for star formation in active galactic nucleus (AGN) discs and also require the IMF of these stars to be top-heavy. We briefly consider the implications of these results for AGN in general.
Late internal-shock model for bright X-ray flares in gamma-ray burst afterglows and GRB 011121
Authors: Fan Y. Z. , Wei D. M. 
Published: October 2005

Abstract
We explore two possible models which might give rise to bright X-ray flares in gamma-ray burst (GRB) afterglows. One is an external forward-reverse shock model, in which the shock parameters of forward-reverse shocks are taken to be quite different. The other is a so-called ‘late internal-shock model’, which requires a refreshed unsteady relativistic outflow generated after the prompt γ-ray emission. In the forward-reverse shock model, after the time t× at which the reverse shock crosses the ejecta, the flux declines more slowly than (t⊕/t×)−(2+β), where t⊕ denotes the observer's time and β is the spectral index of the X-ray emission. In the ‘late internal-shock model’, decaying slopes much steeper than (t⊕/te,⊕)−(2+β) are possible if the central engine shuts down after te,⊕ and the observed variability time-scale of the X-ray flare is much shorter than te,⊕.
The sharp decline of the X-ray flares detected in GRB 011121, XRF 050406, GRB 050502b and GRB 050730 rules out the external forward-reverse shock model directly and favours the ‘late internal-shock model’. These X-ray flares could thus hint that the central engine has begun to operate again and a new unsteady relativistic outflow is generated just a few minutes after the intrinsic hard burst.
Stochastic geometrical theory of diffraction
Authors: Mazar R. , Felsen L. B. 
Published: October 2005

The localization of high-frequency sound-wave propagation around ray trajectories, and the reflection and(or) diffraction of these local plane-wave fields by boundaries, inhomogeneities, and(or) scattering centers has been combined via the geometrical theory of diffraction (GTD) into one of the most effective means of analyzing high-frequency wave phenomena in complex deterministic environments. These constructs are here incorporated into a stochastic propagation and diffraction theory for statistical moments of the high-frequency field when the propagation medium has weak random fluctuations superimposed upon an inhomogeneous background profile, subject to the assumption that the correlation length ln of the fluctuations is small compared with the scale of variation, but large compared with the local wavelength λ=2π/k=2πv/ω, in the fluctuation-free background, with k being the local wavenumber, v the local wave speed, and ω the radian frequency. Canonical problems of deterministic GTD furnish the propagators and, in the presence of interfaces, boundaries, or other types of scatterers, the local reflection, refraction, and diffraction coefficients that relate incoming to outgoing wave fields.
The major analytical building blocks include propagators described in local coordinates centered on the curved GTD ray trajectories in the deterministic inhomogeneous background environment; multiscale expansions in these coordinates to chart and solve for the propagation properties of statistical measures of the parabolically formulated ray fields; Kirchhoff or physical optics (PO) approximations, generated by stochastic GTD incident fields, to establish initial conditions for fields reflected from, or transmitted across, extended smooth surfaces; and ‘‘point scatterer’’ solutions to establish GTD initial conditions for small scatterers and edges. In addition to the conventional second- and higher-order coherence functions, there are introduced as appropriate statistical objects two-point random functions and corresponding higher-order functions which are useful in treating correlation of incident and of backward reflected or diffracted fields that traverse the same propagation volume. By this solution strategy, one gains access to a much larger class of high-frequency problems in a random medium than at present. Expressions for the average field and higher moments have been obtained for forward propagation in a fluctuating medium with inhomogeneous and caustic-forming background, for reflection and refraction due to a plane or smoothly curved interface in such a medium, and for diffraction due to a wedge and a small scatterer.
Pressure derivatives of elastic wave velocities from ultrasonic interferometric measurements on jacketed polycrystals
Authors: Niesler H. , Jackson I. 
Published: October 2005

A buffer-rod technique is described for the measurement by ultrasonic pulse interferometry of elastic wave velocities in jacketed polycrystalline specimens as functions of pressure to 3 GPa. The technique is tested on a suite of synthetic polycrystalline specimens (alumina and forsteritic olivine) for which bounds on the pressure-dependent wave velocities may be calculated from single-crystal elasticity data. Measurements conducted at pressures below ∼1 GPa with an unbonded buffer-rod configuration are compromised by the behavior of the interface between the buffer rod and the specimen. It appears that complex reflection and transmission coefficients associated with the contact between microscopically rough surfaces give rise to significant travel-time perturbations that decrease markedly with increasing pressure. These complications can be minimized but not eliminated by insertion between the buffer rod and the specimen of a disk of gold foil that amounts to a ‘‘bond’’ with more clearly defined acoustic properties. The range of pressures within which the interface effect is negligible may be significantly increased by the use of this bonded configuration. Measured elastic wave velocities are influenced by the presence of both microcracks and pores.
Very large pressure derivatives measured between 0 and 0.5 GPa on one specimen are attributed to the closure of 0.1% porosity associated with cracks with aspect ratios less than 10−3. Otherwise, pressure derivatives are normal with velocities approximately 1%, 3%, and 4%–6% below the Hashin–Shtrikman bounds throughout the 0- to 3-GPa interval for specimens of 0.3%, 2.1%, and 4.8% porosity, respectively. These modest reductions in velocity and their survival to 3 GPa indicate that essentially all of the porosity in these specimens is contributed by relatively equidimensional pores of aspect ratio ∼0.1—consistent with their origin as sintered aggregates. The measured pressure derivatives are compared with those of the Hashin–Shtrikman bounds calculated from the pressure-dependent single-crystal elastic moduli. With the sole exception of the microcracked specimen at pressure below 0.5 GPa, the measured derivatives of wave velocities reproduce within ±10% the slopes of the Hashin–Shtrikman bounds demonstrating the viability of the technique for measurement of pressure derivatives of elastic wave velocities on fine-grained polycrystals.
Effects of flanking band proximity, number, and modulation pattern on comodulation masking release
Authors: Hall Joseph W. , Grose John H. , Haggard Mark P. 
Published: October 2005

Comodulation masking release for a 700-Hz pure-tone signal was investigated as a function of the number and spectral positions of 20-Hz-wide comodulated flanking bands. In the first experiment, all stimuli were presented diotically. CMR was examined as a function of the number of flanking bands present, in conditions where the bands were arranged symmetrically around the signal frequency, were below the signal frequency, or were above the signal frequency. The number of flanking bands ranged from one to eight, and the magnitude of the diotic CMR ranged from approximately 5–16 dB. The results indicated: (1) bands closer to the signal resulted in larger masking release, and (2) more bands gave rise to larger CMR (but with diminishing returns above two flanking bands).
Two additional sets of diotic conditions were examined and compared to the condition where all eight comodulated flanking bands were present: In one set of conditions, two of the eight flanking bands were removed; in the other set of conditions, two of the eight flanking bands were replaced with bands (termed ‘‘deviant’’ bands) that were not comodulated with respect to the other bands.
There was very little effect of reducing eight bands to six, even when the removed bands were relatively near the signal frequency; however, CMR was substantially reduced when deviant bands were introduced, particularly when the deviant bands were placed relatively near the signal frequency. These reductions in CMR were slightly greater when each of the deviant bands had a unique modulation pattern (bideviant bands) than when the two deviant bands themselves shared the same modulation pattern (codeviant bands). In the second experiment, dichotic conditions were examined where the number and spectral positions of the flanking bands in the nonsignal ear were varied (the signal ear received only a 20-Hz-wide noise band centered on the signal frequency).
The magnitude of the dichotic CMR ranged from approximately 2–10 dB, depending on condition. Effects of proximity and the number of flanking bands were similar to the effects obtained in diotic conditions. For both the diotic and the dichotic data, the effects of proximity were more consistent with an interpretation based upon across-channel processing than upon a within-channel interaction. The results obtained using deviant bands indicate that it is difficult for the auditory system to disregard the modulation pattern of flanking bands that differ from the modulation pattern of the on-signal band, particularly if such bands are proximal to the signal frequency.