bluuebunny/crossref_metadata_2025 huggingface dataset:
A systematic review of the epidemiology of status epilepticus
Authors: Chin R. F. M. , Neville B. G. R. , Scott R. C.
Published: December 2004

Population‐based data on the incidence, aetiology, and mortality associated with status epilepticus (SE) are required to develop preventative strategies for SE. Through a systematic review, we aimed to assess the methodological quality as well as similarities, and differences between available population based studies in order to arrive at conclusions on the epidemiology of SE. All population‐based studies where primary outcome was incidence, aetiology or mortality of SE were identified through a systematic search and synthesized. Methodological quality of studies were independently rated by two examiners using a unique scoring system. Seven population‐based projects on SE yielding nine published reports and five abstracts were reviewed. Quality scores were in the range of 19–34 with a possible maximum of 40 (kappa scores 0.67–1.0). The incidence of SE has a bimodal distribution with peaks in children aged less than a year and the elderly. Most SE were acute symptomatic. Short‐term mortality was 7.6–22% and long‐term mortality was 43%. Age and aetiology were the major determinants of mortality. There are few population‐based studies on SE but most are of good quality. Most studies are primarily or exclusively based on adult populations. There is limited information on the association of ethnicity and socio‐economic status and SE.
Single Grid Error Estimation Using Error Transport Equation
Authors: Celik Ismail , Hu Gusheng
Published: December 2004

This paper presents an approach to quantify the discretization error as well as other errors related to mesh size using the error transport equation (ETE) technique on a single grid computation. The goal is to develop a generalized algorithm that can be used in conjunction with computational fluid dynamics (CFD) codes to quantify the discretization error in a selected process variable. The focus is on applications where the conservation equations are solved for primitive variables, such as velocity, temperature and concentration, using finite difference and/or finite volume methods. An error transport equation (ETE) is formulated. A generalized source term for the ETE is proposed based on the Taylor series expansion and accessible influence coefficients in the discretized equation. Representative examples, i.e., one-dimensional convection diffusion equation, two-dimensional Poisson equation, two-dimensional convection diffusion equation, and non-linear one-dimensional Burger’s equation are presented to verify this method and elucidate its properties. Discussions are provided to address the significance and possible potential applications of this method to Navier-Stokes solvers.
Temperature Corrected Turbulence Model for High Temperature Jet Flow
Authors: Abdol-Hamid Khaled S. , Pao S. Paul , Massey Steven J. , Elmiligui Alaa
Published: December 2004

It is well known that the two-equation turbulence models under-predict mixing in the shear layer for high temperature jet flows. These turbulence models were developed and calibrated for room temperature, low Mach number, and plane mixing layer flows. In the present study, four existing modifications to the two-equation turbulence model are implemented in PAB3D and their effect is assessed for high temperature jet flows. In addition, a new temperature gradient correction to the eddy viscosity term is tested and calibrated. The new model was found to be in the best agreement with experimental data for subsonic and supersonic jet flows at both low and high temperatures.
A Simplified Model for Determining Interfacial Position in Convergent Microchannel Flows
Authors: Hitt D. L. , Macken N.
Published: December 2004

Previous experimental and computational studies have indicated that interfaces formed in steady, converging microchannel flows with similar liquids tend to be planar in nature under a variety of conditions relevant to micro-scale flows, including MEMS/microfluidic devices and even microcirculatory blood flows. Assuming a planar interface, we have developed an analytical framework to predict the fully developed interfacial location downstream of a convergence of identical microchannels. Results have been obtained for microchannels having rectangular, elliptical/circular and triangular cross-sections as a function of the inlet flow ratio. Two-dimensional results have also been obtained for fluids having unequal viscosities. Good agreement is found between this model and 3-D numerical simulations and experimental measurements provided that the flow inertia remains sufficiently small (Re≲10, typically). Where valid, application of this analytical, planar interface method represents a significant decrease in computational effort when compared to using CFD to determine interfacial positions.
Wake Flow of Single and Multiple Yawed Cylinders
Authors: Thakur A. , Liu X. , Marshall J. S.
Published: December 2004

An experimental and computational study is performed of the wake flow behind a single yawed cylinder and a pair of parallel yawed cylinders placed in tandem. The experiments are performed for a yawed cylinder and a pair of yawed cylinders towed in a tank. Laser-induced fluorescence is used for flow visualization and particle-image velocimetry is used for quantitative velocity and vorticity measurement. Computations are performed using a second-order accurate block-structured finite-volume method with periodic boundary conditions along the cylinder axis. Results are applied to assess the applicability of a quasi-two-dimensional approximation, which assumes that the flow field is the same for any slice of the flow over the cylinder cross section. For a single cylinder, it is found that the cylinder wake vortices approach a quasi-two-dimensional state away from the cylinder upstream end for all cases examined (in which the cylinder yaw angle covers the range 0⩽ϕ⩽60°). Within the upstream region, the vortex orientation is found to be influenced by the tank side-wall boundary condition relative to the cylinder. For the case of two parallel yawed cylinders, vortices shed from the upstream cylinder are found to remain nearly quasi-two-dimensional as they are advected back and reach within about a cylinder diameter from the face of the downstream cylinder. As the vortices advect closer to the cylinder, the vortex cores become highly deformed and wrap around the downstream cylinder face. Three-dimensional perturbations of the upstream vortices are amplified as the vortices impact upon the downstream cylinder, such that during the final stages of vortex impact the quasi-two-dimensional nature of the flow breaks down and the vorticity field for the impacting vortices acquire significant three-dimensional perturbations. Quasi-two-dimensional and fully three-dimensional computational results are compared to assess the accuracy of the quasi-two-dimensional approximation in prediction of drag and lift coefficients of the cylinders.
Beam collimation with polycapillary x‐ray optics for high contrast high resolution monochromatic imaging
Authors: Sugiro Francisca R. , Li Danhong , MacDonald C. A.
Published: December 2004

Monochromatic imaging can provide better contrast and resolution than conventional broadband radiography. In broadband systems, low energy photons do not contribute to the image, but are merely absorbed, while high energy photons produce scattering that degrades the image. By tuning to the optimal energy, one can eliminate undesirable lower and higher energies. Monochromatization is achieved by diffraction from a single crystal. A crystal oriented to diffract at a particular energy, in this case the characteristic line energy, diffracts only those photons within a narrow range of angles. The resultant beam from a divergent source is nearly parallel, but not very intense. To increase the intensity, collimation was performed with polycapillary x‐ray optics, which can collect radiation from a divergent source and redirect it into a quasi parallel beam. Contrast and resolution measurements were performed with diffracting crystals with both high and low angular acceptance. Testing was first done at 8 keV with an intense copper rotating anode x‐ray source, then 17.5 keV measurements were made with a low power molybdenum source. At 8 keV, subject contrast was a factor of five higher than for the polychromatic case. At 17.5 keV, monochromatic contrast was two times greater than the conventional polychromatic contrast. The subject contrasts measured at both energies were in good agreement with theory. An additional factor of two increase in contrast, for a total gain of four, is expected at 17.5 keV from the removal of scatter. Scatter might be simply removed using an air gap, which does not degrade resolution with a parallel beam.
Micro‐CT with respiratory and cardiac gating
Authors: Badea C. , Hedlund L. W. , Johnson G. A.
Published: December 2004

Cardiopulmonary imaging in rodents using micro‐computed tomography (CT) is a challenging task due to both cardiac and pulmonary motion and the limited fluence rate available from micro‐focus x‐ray tubes of most commercial systems. Successful imaging in the mouse requires recognition of both the spatial and temporal scales and their impact on the required fluence rate. Smaller voxels require an increase in the total number of photons (integrated fluence) used in the reconstructed image for constant signal‐to‐noise ratio. The faster heart rates require shorter exposures to minimize cardiac motion blur imposing even higher demands on the fluence rate. We describe a system with fixed tube/detector and with a rotating specimen. A large focal spot x‐ray tube capable of producing high fluence rates with short exposure times was used. The geometry is optimized to match focal spot blur with detector pitch and the resolution limits imposed by the reproducibility of gating. Thus, it is possible to achieve isotropic spatial resolution of with a fluence rate at the detector 250 times that of a conventional cone beam micro‐CT system with rotating detector and microfocal x‐ray tube. Motion is minimized for any single projection with exposures that are synchronized to both cardiac and breathing motion. System performance was validated in vivo by studies of the cardiopulmonary structures in C57BL/6 mice, demonstrating the value of motion integration with a bright x‐ray source.
Adaptive algebraic reconstruction technique
Authors: Lu Wenkai , Yin Fang‐Fang
Published: December 2004

Algebraic reconstruction techniques (ART) are iterative procedures for reconstructing objects from their projections. It is proven that ART can be computationally efficient by carefully arranging the order in which the collected data are accessed during the reconstruction procedure and adaptively adjusting the relaxation parameters. In this paper, an adaptive algebraic reconstruction technique (AART), which adopts the same projection access scheme in multilevel scheme algebraic reconstruction technique (MLS‐ART), is proposed. By introducing adaptive adjustment of the relaxation parameters during the reconstruction procedure, one‐iteration AART can produce reconstructions with better quality, in comparison with one‐iteration MLS‐ART. Furthermore, AART outperforms MLS‐ART with improved computational efficiency.
On the use of EPID‐based implanted marker tracking for 4D radiotherapy
Authors: Keall P. J. , Todor A. D. , Vedam S. S. , Bartee C. L. , Siebers J. V. , Kini V. R. , Mohan R.
Published: December 2004

Four‐dimensional (4D) radiotherapy delivery to dynamically moving tumors requires a real‐time signal of the tumor position as a function of time so that the radiation beam can continuously track the tumor during the respiration cycle. The aim of this study was to develop and evaluate an electronic portal imaging device (EPID)‐based marker‐tracking system that can be used for real‐time tumor targeting, or 4D radiotherapy. Three gold cylinders, in length and in diameter, were implanted in a dynamic lung phantom. The phantom range of motion was with a “breathing” period. EPID image acquisition parameters were modified, allowing image acquisition in . Images of the stationary and moving phantom were acquired. Software was developed to segment automatically the marker positions from the EPID images. Images acquired in displayed higher noise and a lower signal‐noise ratio than those obtained using regular acquisition settings. However, the markers were still clearly visible on the images. The motion of the phantom blurred the images of the markers and further reduced the signal‐noise ratio, though they could still be successfully segmented from the images in of computation time. The positions of gold markers placed in the lung phantom were detected successfully, even for phantom velocities substantially higher than those observed for typical lung tumors. This study shows that using EPID‐based marker tracking for 4D radiotherapy is feasible, however, changes in linear accelerator technology and EPID‐based image acquisition as well as patient studies are required before this method can be implemented clinically.
The use of modified single pencil beam dose kernels to improve IMRT dose calculation accuracy
Authors: Bergman Alanah M. , Otto Karl , Duzenli Cheryl
Published: December 2004

Intensity modulated radiation therapy (IMRT) is used to deliver highly conformal radiation doses to tumors while sparing nearby sensitive tissues. Discrepancies between calculated and measured dose distributions have been reported for regions of high dose gradients corresponding to complex radiation fluence patterns. For the single pencil beam convolution dose calculation algorithm, the ability to resolve areas of high dose structure is partly related to the shape of the pencil beam dose kernel (similar to how a photon detector's point spread function relates to imaging resolution). Improvements in dose calculation accuracy have been reported when the treatment planning system (TPS) is recommissioned using high‐resolution measurement data as input. This study proposes to improve the dose calculation accuracy for IMRT planning by modifying clinical dose kernel shapes already present in the TPS, thus avoiding the need to reacquire higher resolution commissioning data. The in‐house optimization program minimizes a cost‐function based on a two‐dimensional composite dose subtraction/distance‐to‐agreement (gamma) analysis. The final modified kernel shapes are reintroduced into the treatment planning system and improvements to the dose calculation accuracy for complex IMRT dose distributions evaluated. The central kernel value has the largest effect on the dose calculation resolution and is the focus of this study.
Respiratory gating and 4‐D tomotherapy
Authors: Zhang Tiezhi
Published: December 2004

Helical tomotherapy is a new intensity‐modulated radiotherapy (IMRT) delivery process developed at the University of Wisconsin and TomoTherapy Inc. Tomotherapy may be of advantage in lung cancer treatment due to its rotational delivery mode. As with conventional IMRT delivery, however, intrafraction respiratory motion during a tomotherapy treatment causes unnecessary radiation to the healthy tissue. Possible solutions to these problems associated with intrafraction motion have been studied in this thesis. A spirometer is useful for monitoring breathing because of its direct correlation with lung volume changes. However, its inherent drift prevents its application in long‐term breathing monitoring. With calibration and stabilization algorithms, a spirometer is able to provide accurate, long‐term lung volume change measurements. Such a spirometer system is most suited for deep inspiration breath‐hold (DIBH) treatments. An improved laser‐spirometer combined system has also been developed for target tracking in 4‐D treatment. Spirometer signals are used to calibrate the displacement measurements into lung volume changes, thereby eliminating scaling errors from daily setup variations. The laser displacement signals may also be used to correct spirometer drifts during operation. A new 4‐D treatment technique has been developed to account for intrafraction motion in treatment planning. The patient's breathing and the beam delivery are synchronized, and the target motion/deformation is incorporated into treatment plan optimization. Results show that this new 4D treatment technique significantly reduces motion effects and provides improved patient tolerance.
Transmission and dose perturbations with high‐ materials in clinical electron beams
Authors: Das Indra J. , Cheng Chee‐Wai , Mitra Raj K. , Kassaee Alireza , Tochner Zelig , Solin Lawrence J.
Published: December 2004

High density and atomic number materials used in various prostheses, eye shielding, and beam modifiers produce dose enhancements on the backscatter side in electron beams and is well documented. However, on the transmission side the dose perturbation is given very little clinical importance, which is investigated in this study. A simple and accurate method for dose perturbation at metallic interfaces with soft tissues and transmission through these materials is required for all clinical electron beams. Measurements were taken with thin‐window parallel plate ion chambers for various high‐ materials (, , , and ) on a Varian and a Siemens accelerator in the energy range of . The dose enhancement on both sides of the metallic sheet is due to increased electron fluence that is dependent on the beam energy and . On the transmission side, the magnitude of dose enhancement depends on the thickness of the high‐ material. With increasing thickness, dose perturbation reduces to the electron transmission. The thickness of material to reduce 100% (range of dose perturbation), 50% and 10% transmission is linear with the beam energy. The slope of the transmission curve varies exponentially with . A nonlinear regression expression is derived to calculate the thickness at a given transmission, namely 100%, 50%, and 10% for electron energy, , which is simple, accurate and well suited for a quick estimation in clinical use. Caution should be given to clinicians for the selection of thickness of high‐ materials when used to shield critical structures as small thickness increases dose significantly at interfaces.
SPECT brain imaging of the dopaminergic system in Parkinsonism using and labeled agents
Authors: Du Yong
Published: December 2004

SPECT brain imaging of the dopaminergic system using and labeled agents, especially the simultaneous imaging of both pre‐ and postsynaptic neurons, promises to provide accurate diagnosis and differentiation of Parkinsonism. However, there are many degrading factors that affect the quality and quantitative accuracy of the SPECT images. These degrading factors limit the potential clinical applications of brain SPECT imaging. In this work, we studied these degrading factors by developing and validating a Monte Carlo (MC) method that provides accurate SPECT simulation with detailed modeling of the photon interactions inside the collimator detector system. To compensate for the partial volume effect (PVE) in the SPECT images caused by finite spatial resolution, we developed a new PVE compensation method that takes into account the effects of nonlinearity in iterative reconstruction‐based compensation for image degrading factors, including attenuation, scatter, and collimator detector response. Compensation using the new method greatly improved the quantitative accuracy of brain SPECT images. We have also developed model‐based method that can accurately estimate the downscatter and crosstalk contamination in the imaging and the simultaneous dual‐isotope imaging. Based on the model‐based method, two different approaches to model‐based downscatter and crosstalk contamination compensation were proposed. Both methods are based on iterative reconstruction and include compensation for other imaging degrading factors. The model‐based downscatter and crosstalk compensation method provided greatly improved accuracy of activity estimates with little effect on the precision. Finally, optimization of energy windows for simultaneous acquisition was performed to find the energy windows with the best trade‐off between minimizing the crosstalk and maximizing the detection efficiency for simultaneous acquisitions. In summary, comprehensive methods were developed and evaluated to compensate for image degrading factors in simultaneous dual‐isotope brain SPECT imaging. Application of these methods in the imaging of the dopaminergic system has the potential to provide improved accuracy for diagnosis of Parkinsonism.
Coptidis rhizoma Induces Apoptosis in Human Colorectal Cancer Cells SNU-C4
Authors: Kim Youn Jung , Kang Soon Ah , Hong Mee Suk , Park Hae Jeong , Kim Mi-Ja , Park Hi-Jun , Kim Hye Kyung
Published: December 2004

Coptidis rhizoma has been used as traditional herb medicine in gastrointestinal disorders in the Eastern Asia. We investigated whether the anticancer effects of the C. rhizoma induced apoptosis on human colorectal cancer cells SNU-C4. The cytotoxic effect of C. rhizoma was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. To determine apoptotic cell death, 4,6-diamidino-2-phenylindole (DAPI) staining, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay, reverse transcription-polymerase chain reaction (RT-PCR) and caspase-3 enzyme assay were performed. In this study, C. rhizoma treatment (100 μg/ml) revealed typical morphological apoptotic features. Additionally, C. rhizoma treatment (100 μg/ml) increased levels of BAX and CASPASE-3, and decreased levels of BCL-2. Caspase-3 enzyme activity by treatment of C. rhizoma (100 μg/ml) also significantly increased compared to the control (p<0.05). These data indicate that C. rhizoma caused cell death by apoptosis through caspase pathways on human colorectal cancer cells SNU-C4.
Electroacupuncture on PC6 (Neiguan) Attenuates Ischemia/Reperfusion Injury in Rat Hearts
Authors: Tsou Meng-Ting , Huang Cheng-Hsiung , Chiu Jen-Hwey
Published: December 2004

The use of somato-visceral regulation has been proposed as a treatment for a wide range of diseases. The aim of this study was to test the hypothesis that through somato-visceral regulation, ischemia-reperfusion (I/R) injury to the myocardium can be avoided by electroacupuncture (EA) on PC6 (Neiguan).

Electroacupuncture on PC6 (Neiguan) was brought about by the application of metal needles over the bilateral median nerve at a point 1.5 cm proximal to the palm crease in male Spraque-Dawley rats. The animals were randomized into two groups: (1) prevention group with preconditioning by the application of EA on PC6 (n=13); and (2) treatment group with EA on PC6 during I/R injury (n=10). The protection against myocardial injury was blocked by different mechanisms: (1) severing of the bilateral median nerve (n=10), (2) bilateral vagotomy (n=10), and (3) intravenous naloxone injection (n=10). The hemodynamic parameters (mean artery pressure and heart rate), duration of arrhythmia, mortality rate and cardiac enzymes were evaluated in these groups. The results showed that there were significant reductions in cardiac enzymes, the duration of arrhythmia and mortality rate in rats that were either preconditioned or treated with EA on PC6, compared with those that did not undergo EA on PC6 (P<0.05). The cardioprotective effects were blocked by different procedures (P>0.05).

We conclude that EA on bilateral PC6 (Neiguan) prevents and attenuates I/R injury to the heart, and that this approach may provide an applicable and preventative alternative for patients with ischemic heart disease.
TACHYONS IN DE SITTER SPACE AND ANALYTICAL CONTINUATION FROM dS/CFT TO AdS/CFT
Authors: CADONI M. , CARTA P.
Published: December 2004

We discuss analytic continuation from d-dimensional Lorentzian de Sitter ( dS d) to d-dimensional Lorentzian anti-de Sitter ( AdS d) space–time. We show that AdS d, with opposite signature of the metric, can be obtained as analytic continuation of a portion of dS d. This implies that the dynamics of (positive square-mass) scalar particles in AdS d can be obtained from the dynamics of tachyons in dS d. We discuss this correspondence both at the level of the solution of the field equations and of the Green functions. The AdS / CFT duality is obtained as analytic continuation of the dS / CFT duality.
IGF-I downregulates resistin gene expression and protein secretion
Authors: Chen Yen-Hang , Hung Pei-Fang , Kao Yung-Hsi
Published: December 2004

Resistin (Rstn) is known as an adipocyte-specific secretory factor that can cause insulin resistance and decrease adipocyte differentiation. Conversely, based on various studies, insulin-like growth factors (IGFs) can improve insulin resistance and stimulate adipocyte adipogenesis. Whether IGFs exert their effects through the control of Rstn's production or modulation of Rstn's action is unknown. This study was designed to examine the influence and the signaling of IGF-I on Rstn gene expression and protein secretion by 3T3-L1 adipocytes. We found that IGF-I suppressed Rstn mRNA expression and protein release in dose- and time-dependent manners. The IC50 of IGF-I was ∼1 nM for a range of 6–10 h of treatment. Treatment with cycloheximide, but not with actinomycin D, prevented IGF-I-suppressed Rstn mRNA expression, suggesting that IGF-I destabilizes Rstn mRNA and that IGF-I's effect requires new protein, but not mRNA, synthesis. Pretreatment with IGF-I receptor (IGF-IR) antibody blocked IGF-I-altered IGF-IR activity and Rstn mRNA levels. Neither PD-98059, SB-203580, nor LY-294002 changed the IGF-I-decreased levels of Rstn mRNA, but they inhibited IGF-I-stimulated activities of MEK1, p38 MAPK, and phosphoinositide 3-kinase, respectively. However, SB-203580 antagonized the IGF-I-decreased Rstn protein release. These data demonstrate that IGF-I downregulates Rstn gene expression via IGF-IR-dependent and MEK1-, p38 MAPK-, and phosphoinositide 3-kinase-independent pathways and likely modifies the distribution of Rstn protein between the intracellular and extracellular compartments via a p38 MAPK-dependent pathway. Decreases in Rstn production and secretion induced by IGF-I may be related to the mechanism by which IGF-I modulates body weight and diabetes in animals.
Detrimental Ventricular Remodeling in Patients With Congenital Complete Heart Block and Chronic Right Ventricular Apical Pacing
Authors: Thambo Jean-Benoît , Bordachar Pierre , Garrigue Stephane , Lafitte Stephane , Sanders Prashanthan , Reuter Sylvain , Girardot Romain , Crepin David , Reant Patricia , Roudaut Raymond , Jaïs Pierre , Haïssaguerre Michel , Clementy Jacques , Jimenez Maria
Published: December 2004

Background—

Although dual-chamber pacing improves cardiac function in patients with complete congenital atrioventricular block (CCAVB) by restoring physiological heart rate and atrioventricular synchronization, the long-term detrimental effect of asynchronous electromechanical activation induced by apical right ventricular pacing (RVP) has not been well clarified.

Methods and Results—

Twenty-three CCAVB adults (24±3 years) with a DDD transvenous pacemaker underwent conventional echocardiography before implantation and, after at least 5 years of RVP, an exercise test and echocardiography coupled with tissue Doppler imaging and tissue tracking. They were compared with 30 matched healthy control subjects. After 10±3 years of RVP, CCAVB adults had significantly higher values versus controls in terms of intra-left ventricular (LV) asynchrony (respectively, 59±18 versus 19±9 ms,
P
<0.001), extent of LV myocardium displaying delayed longitudinal contraction (39±15% versus 10±7%,
P
<0.01), and septal-to-posterior wall-motion delay (84±26 versus 18±9 ms,
P
<0.01). The ratio of late-activated posterior to early-activated septal wall thickness was higher after long-term RVP than before (1.3±0.2 vs 1±0.1,
P
=0.05) and was higher than in controls (1±0.1,
P
<0.05). The percentage of patients with increased LV end-diastolic diameter was higher after long-term RVP than before implantation and was higher than in controls (57% versus 13%,
P
<0.05, and 57% versus 0%,
P
<0.01, respectively). CCAVB patients with long-term RVP had a lower cardiac output than controls (3.8±0.6 versus 4.9±0.8 L/min,
P
<0.05) and lower exercise performance (123±24 versus 185±39 W,
P
<0.001).

Conclusions—

Prolonged ventricular dyssynchrony induced by long-term endovenous RVP is associated with deleterious LV remodeling, LV dilatation, LV asymmetrical hypertrophy, and low exercise capacity. These new data highlight the importance of the ventricular activation sequence in all patients with chronic ventricular pacing.
Long-Term Clinical Course of Patients After Termination of Ventricular Tachyarrhythmia by an Implanted Defibrillator
Authors: Moss Arthur J. , Greenberg Henry , Case Robert B. , Zareba Wojciech , Hall W. Jackson , Brown Mary W. , Daubert James P. , McNitt Scott , Andrews Mark L. , Elkin Adam D.
Published: December 2004

Background—

The implanted cardioverter defibrillator (ICD) improves survival in high-risk cardiac patients. This analysis from the MADIT-II trial database examines the long-term clinical course and subsequent mortality risk of patients after termination of life-threatening ventricular tachyarrhythmias by an ICD.

Methods and Results—

Life-table survival analysis was performed, and proportional hazards regression analysis was used to evaluate the contribution of baseline clinical factors and time-dependent defibrillator therapy to mortality during long-term follow-up. Of 720 patients with an ICD (average follow-up 21 months), 169 patients received 701 antiarrhythmic device therapies for ventricular tachyarrhythmias. Few baseline characteristics distinguished patients who received appropriate ICD therapy for their first ventricular tachyarrhythmic episode. The probability of survival for at least 1 year after first therapy for ventricular tachycardia (VT) or ventricular fibrillation (VF) was 80%. The hazard ratios for the risk of death due to any cause in those who survived appropriate therapy for termination of VT and VF were 3.4 (
P
<0.001) and 3.3 (
P
=0.01), respectively, compared with those who survived without receiving ICD therapy, with a high frequency of heart failure and late nonsudden cardiac death after first successful ICD therapy for VF.

Conclusions—

Successful appropriate therapy by an ICD for VT or VF is associated with 80% survival at 1 year after arrhythmia termination. These patients are at increased risk for heart failure and nonsudden cardiac death after device termination of VT or VF and should receive special attention for the prevention and management of progressive left ventricular dysfunction during long-term follow-up.
Calcitonin Gene-Related Peptide Protects Against Hypertension-Induced Heart and Kidney Damage
Authors: Supowit Scott C. , Rao Arundhati , Bowers Mark C. , Zhao Huawei , Fink Gregory , Steficek Barbara , Patel Parag , Katki Khurshed A. , DiPette Donald J.
Published: December 2004

Calcitonin gene-related peptide is a potent vasodilator neuropeptide that is localized in perivascular sensory nerves. To determine whether α-calcitonin gene-related peptide possesses protective activity against hypertension-induced end organ damage, hypertension was induced in α-calcitonin gene-related/calcitonin peptide knockout and wild-type mice by uninephrectomy, deoxycorticosteroid administration, and 0.9% saline drinking water. These mice were instrumented previously for long-term telemetric blood pressure recording. Control groups were sham-operated and given tap water. Mean arterial pressures were determined, and 3 weeks after initiation of each protocol, tissues were taken for histopathologic studies. The deoxycorticosteroid-salt protocol produced a significant 35% mean arterial pressure increase in both mouse strains. No pathological changes were observed in sections of aortas and femoral arteries from any of the groups studied. Likewise, heart and kidney sections from the hypertensive wild-type mice showed no pathological changes compared with their normotensive counterparts. In contrast, marked vasculitis was seen in the heart sections from the deoxycorticosteroid-salt–treated α-calcitonin gene-related peptide knockout mice with thickening and inflammation of the vessel walls. In addition, myocarditis and focal epicarditis with areas of myocardial necrosis were present. Kidneys of these mice exhibited prominent glomerular changes including congestion of the capillary loops, focal mesangial and crescent proliferation, and focal histocytic infiltration. Urinary microalbumin was significantly higher in the hypertensive α-calcitonin gene-related peptide knockout compared with hypertensive wild-type mice. These data suggest that deletion of the α-calcitonin gene-related peptide gene makes the heart and kidneys more vulnerable to hypertension-induced end organ damage.
Written Obligations from the 2nd/8th to the 4th/10th Century
Authors: Thung Michael
Published: December 2004

In this article, based on recent research undertaken in the collection of Arabic papyri of the Austrian National Library in Vienna (Papyrus Erzherzog Rainer), I discuss four unpublished documents discovered in Egypt, all written obligations (adhkār ḥuqūq) dating from the second half of the 2nd/8th century to the first half of the 4th/10th century. These documents provide important documentary evidence for early Islamic legal practice. By comparing the legal content of the documents with the contract formularies used by the ḥanafī jurist al-Ṭaḥāwī (d. 321/933) in his Kitāb adhkār al-ḥuqūq, I investigate the relationship between theory and practice in Islamic Law.
Endowment, Privilege, and Estate in the Central and Eastern Sudan
Authors: O'Fahey
Published: December 2004

In Sudanic Africa, the institution of waqf is rare in the semi-Muslim states stretching from West Africa to the Nile Valley (although some Sudanic rulers did establish awqāf at al-Azhar or in Mecca and Medina). However, these rulers developed a variety of institutions to accommodate incoming Muslim holy men, including the granting of privileged status (jāh or maḥram) — often involving exemption from taxes — ad personam, usually to a holy man and his kin. In Darfur and Sinnār, in particular, this privileged status seems to have evolved into elaborate grants of allodial estates (ḥākūra or iqṬāʿ) that became hereditary. Unlike the earlier grants of privilege, which appear to have been made to kin groups, these allodial states appear to have been granted to individuals, both holy men and non-holy men, although the extant records are largely from holy families.
The Caliphs, the ʿUlamāʾ, and the Law: Defining the Role and Function of the Caliph in the Early ʿAbbāsid Period
Authors: Qasim Zaman Muhammad
Published: December 2004

The early ʿAbbāsid period is usually thought of as a time when a definitive and enduring separation between religion and politics took place. On this view, expressed most notably by Lapidus and Crone and Hinds, the failure of the Miḥna instituted by the caliph al-Maʾmūn, a major showdown with prominent ʿulamāʾ, is taken as the critical moment which marked the end of any involvement of the caliphs in matters of law. Arguing against any such separation between the religious or legal and the political realms, this essay analyses various indications in juristic and historical sources from the early ʿAbbāsid period to show that the caliph continued to be recognized as a participant in the function of commenting on or resolving obscure matters of a legal import. There is, moreover, considerable evidence to show caliphal participation in religious life in general, before as well as after the Miḥna, and no evidence to indicate a separation between religion and politics.
Crisis and Reformation in a Maritime Kingdom of Southeast Asia: Forces of Instability and Political Disintegration in Western Burma (Arakan), 1603-1701
Authors: Charney Michael
Published: December 2004

This study of the initial collapse, revival, and finally a resumption of decline in the seventeenth century of the maritime kingdom of Arakan (in western Burma) attempts to establish a special place for Arakan in the general historiography of the seventeenth-century crisis in Southeast Asia. The unusual experience of Arakan in the seventeenth century was in large part due to both the blockades by autonomous Portuguese freebooters in the first two decades of the seventeenth century and the peculiar nature of a new trading relationship from the 1630s until the 1660s between the Arakanese and the Dutch, based on the Arakanese supply of slaves and rice to Dutch port-cities and plantations. The ebb and flow of Arakanese fortunes throughout the century were thus tied to the fortunes of the Dutch. Expanding Asian empires in Bengal and Burma also influenced the decline of the Arakanese maritime polity after the Dutch withdrew from Arakan in the 1660s. Afterwards, as the material resources of the Arakanese central court declined, the Arakanese littoral became politically fragmented, characterized and sustained by the rise of rival political centers and the rebellions of non-Arakanese ethnic groups who had been captured abroad and resettled in the Arakanese littoral. Arakan thus experienced its “own” crisis in the seventeenth century, a watershed that gives it a peculiar niche in the seventeenth-century history not only of Southeast Asia as a whole, but of the mainland in particular.
The Sun and the Throne.
Authors: Kirkland Russell
Published: December 2004

In this study, I seek to elucidate the process by which the Japanese royal descent myth evolved into the form with which the modern world is familiar. I analyze and compare the forms of the myth found in the Nihongi and the Kojiki, and explicate their evolution through historical and textual analysis. By examining the interplay of the internal dynamics of the myth itself and the external factors that worked to shape it, I reconstruct the mythographical process, and suggest key factors that may have molded the myth. In particular, I argue that it was the introduction of Buddhism at the Yamato court that stimulated the establishment of an imperial cult at Ise and the reconfiguration of key mythic traditions. According to my analysis, the myth itself originated during the reign of king Keitai (early 6th century). In the original myth, the ancestor of the ruling house was not the sun-goddess Amaterasu, but rather the heavenly ruler Takami-musubi. In the mid-sixth century, a sun-goddess named Ō-hirume was introduced in an effort to combat the rising influence of Buddhism. The artificial figure of Amaterasu was introduced only during the reign of Temmu, late in the seventh century.
The Author of De Dea Syria and his Cultural Heritage
Authors: Dirven Lucinda
Published: December 2004

The present contribution deals with the identity of the author of De Dea Syria, a second century work that claims to provide an accurate description of the religion in the Syrian city Hierapolis. Despite this assertion the information of DS has often been discredited. This is due to its presumed author, Lucian of Samosata. Since Lucian is known for his sceptical attitude towards religion, it is often concluded that the DS intents to ridicule the cult of Hierapolis. This assertion diminishes the reliability of the DS, since it implies that it contains fanciful and exaggerated information. It will be argued that the content of the DS provides no firm proof for Lucian's authorship. If the work was written by Lucian, he wrote in a style normally foreign to him. Apart from the wish to attribute this work to Lucian, there are no grounds to interpret the DS in the light of his oeuvre. Instead of starting from a preconceived idea about the author, this article aims to establish his identity by means of the contents of the work itself. Starting point is the allegation of the author that he is a Syrian who personally visited Hierapolis. The information provided by the DS on the Hierapolitan cult tallies with contemporary archaeological material and literary sources. It can therefore be concluded that the account is indeed based upon a personal visit. The author's self-identification as a Syrian is confirmed by the contents and the objective of the DS. On the basis of the contents of the DS its author is best described as a Hellenized Syrian who aimed to assimilate the Hierapolitan cult with Greek culture, while retaining its unique characteristics. As such his account intends to propagate the cult of the Syrian goddess in the Hellenistic world, in all probability especially in Hellenistic Syria.
An Explicit One-Dimensional Time-Dependent Tilting Cloud Model
Authors: Chen Shu-Hua , Sun Wen-Yih
Published: December 2004

An explicit one-dimensional time-dependent tilting cloud model has been developed for use in cumulus parameterizations. The tilting axis is not necessarily orthogonal to the (r, θ) plane, making the horizontal axisymmetric assumption more reasonable. This explicit time-dependent tilting model (ETTM) consists of an updraft and a downdraft, which are governed by the same dynamic and thermodynamic equations. The updraft is initiated by a moist thermal bubble, while the downdraft is consequently induced by evaporative cooling and the drag force of precipitation separating from the tilting updraft instead of being arbitrarily initialized.

The updraft is capable of reproducing the major features of a deep cloud such as overshooting cooling above the cloud top, evaporative cooling near the surface, and drying in the lower atmosphere at dissipating stages. The entrainment–detrainment rate in this model is well defined, and its time variation is quite significant. Moreover, the vertical profile of the air inside the updraft does not follow the moist adiabat after deep convection. For the downdraft, the total precipitation and mass flux at low levels contributed from the downdraft cannot be neglected in this case study. In addition, the downdraft can bring dry air from middle levels to lower levels.

Three sensitivity tests—the environmental sounding, the tilting angle, and the radius of the updraft–downdraft— have also been conducted. The cooling–warming of a downdraft near the surface is sensitive to the environmental sounding, consistent with results from Srivastava. The cloud life span, maximum vertical velocity, precipitation amount, and vertical mass flux are strongly influenced by the tilting angle and the radius of the cloud.

The results from the ETTM simulation are quite reasonable and promising. However, some deficiencies of this model still exist, and more research will be conducted to improve its performance. The final goal is to implement this 1D model in a mesoscale model's cumulus parameterization scheme.
Flow Patterns and Drag in Near-Critical Flow over Isolated Orography
Authors: Johnson E. R. , Vilenski G. G.
Published: December 2004

Since early manned space flight orographically forced cloud patterns have been described in terms of the single isolated shock structure of shallow-water flow or, equivalently, compressible fluid flow. Some of these observations show, behind an initial “bow wave,” a series of almost parallel wave crests. This paper considers the simplest extension of shallow-water theory that retains not only nonlinear steepening of waves but includes departures from hydrostatic balance, and thus wave dispersion, showing that the single shocks of shallow-water theory are transformed into multiple parallel finite-amplitude wave crests. The context of the discussion is the forced Kadomtsev–Petviashvili equation from classical ship wave dynamics, which plays the same role in two-dimensional near-critical fluid flow as the more familiar Korteweg–de Vries equation in one-dimensional flow. The drag and flow regimes in near-critical flow over isolated orography are described in terms of the three governing parameters of the flow: the deviation of the flow speed from critical, the strength of nonhydrostatic effects, and the strength of orographic forcing.
Abrupt Transition to Strong Superrotation in an Axisymmetric Model of the Upper Troposphere
Authors: Shell Karen M. , Held Isaac M.
Published: December 2004

Abrupt transitions to strongly superrotating states have been found in some idealized models of the troposphere. These transitions are thought to be caused by feedbacks between the eddy momentum flux convergence in low latitudes and the strength of the equatorial flow. The behavior of an axisymmetric shallow-water model with an applied tropical torque is studied here to determine if an abrupt transition can be realized without eddy feedbacks. The upper-tropospheric layer is relaxed to a radiative equilibrium thickness, exchanging mass and thus momentum with the nonmoving lower layer. For low values of the applied torque, the circulation is earthlike; however, for larger values, an abrupt transition to a strongly superrotating state can occur. In some cases, the system remains superrotating as the torque is subsequently decreased. A simple analytical model is used to better understand the system. The bifurcation is caused by a feedback between the applied torque and the strength of the Hadley cell. As the torque increases, the strength of the cell decreases, reducing the damping caused by momentum transfer from the lower layer.
Interdecadal Sea Level Fluctuations at Hawaii
Authors: Firing Yvonne L. , Merrifield Mark A. , Schroeder Thomas A. , Qiu Bo
Published: December 2004

Over the past century, tide gauges in Hawaii have recorded interdecadal sea level variations that are coherent along the island chain. The generation of this signal and its relationship to other interdecadal variability are investigated, with a focus on the last decade. Hawaii sea level is correlated with sea surface height (SSH) over a significant portion of the North Pacific Ocean, and with the Pacific–North America (PNA) index, which represents teleconnections between tropical and midlatitude atmospheric variations. Similar variations extend well below the thermocline in World Ocean Atlas temperature. Comparison with NCEP reanalysis wind and pressure shows that high (low) sea level phases around Hawaii are associated with an increase (decrease) in the strength of the Aleutian low. The associated wind stress curl pattern is dynamically consistent with observed sea level anomalies, suggesting that sea level at Hawaii represents large-scale changes that are directly wind-forced in concert with the PNA. Atmospheric modulation, as opposed to Rossby wave propagation, may explain the linkage of Hawaii sea level to North American sea level and ENSO events. A wind-forced, baroclinic Rossby wave model replicates some aspects of the interdecadal SSH variations and their spatial structure but fails to predict them in detail near Hawaii. The accuracy of wind products in this region and over this time period may be a limiting factor. Variations in mixed layer temperature due to surface heat flux anomalies may also contribute to the interdecadal sea level signal at Hawaii.