bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Hospital Volume on Outcomes of Transcatheter Mitral Valve Repair: An Early US Experience
Authors: Patel Nileshkumar J. , Badheka Apurva O. , Jhamnani Sunny , Panaich Sidakpal S. , Singh Vikas , Patel Nilay , Arora Shilpkumar , Grines Cindy L. , Cleman Micheal , Forrest John K. 
Published: October 2015

BackgroundTranscatheter mitral valve repair (TMVR) is a complex procedure for patients with mitral regurgitation who cannot get surgery. However, there is a lack of data on how hospital volumes affect these outcomes.MethodsWe performed a cross sectional study based on Healthcare Cost and Utilization Project's Nationwide Inpatient Sample database of 2012 and identified subjects using the ICD‐9‐CM procedure code of 35.97, which was introduced in October 2010 for percutaneous mitral valve repair if present in the primary or secondary procedure field. Hospital volumes were divided into tertiles. The primary outcome was a composite of in‐hospital mortality and peri‐procedural complications. Length of stay and hospitalization cost were also assessed.ResultsA total of 95 (weighted n = 475) TMVR procedures were identified. The mean age of the overall cohort was 70 years; 43.2% were female and 63.2% had a significant baseline burden of co‐morbidities. The composite of in‐hospital mortality and peri‐procedural complications decreased with increasing TMVR hospital volume: 48.7% in the first tertile, 17.4% in the second tertile, and 9.1% in the third tertile. Additionally, we saw a decrease in the length of stay and a trend in decrease in the hospitalization cost.ConclusionIn hospitals performing TMVR, higher hospital volumes are associated with a reduction in a composite of in‐hospital mortality and post‐procedural complications, in addition to the shorter length of stay. (J Interven Cardiol 2015;28:464–471)
A Multivariate Analysis of Intercompany Loss Triangles
Authors: Shi Peng 
Published: October 2015

AbstractThe prediction of insurance liabilities often requires aggregating experience of loss payment from multiple insurers. The resulting data set of intercompany loss triangles displays a multilevel structure of claim development where a portfolio consists of a group of insurers, each insurer several lines of business, and each line various cohorts of claims. In this article, we propose a Bayesian hierarchical model to analyze intercompany claim triangles. A copula regression is employed to join multiple triangles of each insurer, and a hierarchical structure is specified on major parameters to allow for information pooling across insurers. Numerical analysis is performed for an insurance portfolio of multivariate loss triangles from the National Association of Insurance Commissioners. We show that prediction is improved through borrowing strength within and between insurers based on training and holdout observations.
Meta‐Analysis of Efficacy and Safety of Apixaban in Patients Undergoing Catheter Ablation for Atrial Fibrillation
Authors: LU DASHENG , LIU QIAN , WANG KAI , ZHANG QI , SHAN QI‐JUN 
Published: October 2015

BackgroundThe efficacy and safety of apixaban in patients undergoing catheter ablation (CA) for atrial fibrillation (AF) are little investigated.MethodsThe Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and EMBASE were searched up to September 2015. Four literatures comparing apixaban with vitamin K antagonists (VKAs) were included. Data were pooled in Review Manager Software, using Mantel‐Haenszel methods with a fixed‐effects model. The funnel plots and Egger's test were used to examine publication bias. Heterogeneity was assessed using the I2 test. Risk ratios (RR) and 95% confidence intervals (CI) of each study were calculated and pooled.ResultsNo significant differences were observed in rates of total bleeding (RR = 0.91, 95% CI [0.57, 1.46], I2 = 0.0%), thromboembolic complications (RR = 0.75, 95% CI [0.03, 18.22], I2 = 0.0%), or total events (RR = 0.90, 95% CI [0.56, 1.44], I2 = 0.0%) between apixaban and VKAs group. The frequency of major bleeding was similar between apixaban and VKAs group (RR = 1.34, 95% CI [0.34, 5.30], I2 = 0.0%).ConclusionApixaban was as effective and safe as VKAs in the periprocedural period of CA.
Tacrolimus interaction with dexmedetomidine—a case report
Authors: Stiehl Sarah R. , Squires James E. , Bucuvalas John C. , Hemmelgarn Trina S. 
Published: October 2015

AbstractDrugs and xenobiotics that inhibit the CYP‐450 isoenzyme 3A4 are associated with increased serum tacrolimus levels. We sought to determine whether there was a temporal association between initiation of dexmedetomidine and increased serum tacrolimus levels. An interaction has not been previously documented. We reviewed tacrolimus levels and dosing in a pediatric patient aged 8 months who had undergone deceased‐donor liver transplantation for biliary atresia and later required sedation with dexmedetomidine continuous infusion during the POD (212–216). Serum tacrolimus trough levels increased 4‐fold from 3.4 to 13.1 ng/mL (tacrolimus regimen: 1 mg every 12 h) within 21 h of initiating dexmedetomidine. During dexmedetomidine infusion, serum tacrolimus trough levels were maintained with doses that were 25% of baseline tacrolimus dose. Tacrolimus trough levels decreased to below goal range within 30–40 h of discontinuation of dexmedetomidine. Data submitted to the U.S. Food and Drug Administration demonstrate that dexmedetomidine inhibits CYP 3A4 and may produce adequate liver concentrations that could interfere with tacrolimus metabolism. We suggest that tacrolimus levels should be carefully monitored in children receiving prolonged infusions of dexmedetomidine to avoid adverse events associated with elevated tacrolimus levels.
Hematopoietic stem cell transplantation from non‐sibling matched family donors for patients with thalassemia major in Jordan
Authors: Hussein Ayad Ahmed , Al‐Zaben Abdulhadi , Khattab Eman , Haroun Anas , Frangoul Haydar 
Published: October 2015

AbstractThere are limited data on the outcome of patients with thalassemia receiving HSCT from non‐sibling matched family donors. Of the 341 patients with thalassemia major that underwent donor search at our center from January 2003 to December 2011, 236 (69.2%) had fully matched family donor of which 28 patients (8.2%) had non‐sibling matched family donors identified. We report on seven patients with a median age of eight yr (4–21) who underwent myeloablative (n = 4) or RIC (n = 3) HSCT. The median age of the donors was 33 yr (4–47), three were parents, two first cousins, one paternal uncle, and one paternal aunt. All patients achieved primary neutrophil and platelet engraftment at a median of 18 (13–20) and 16 days (11–20), respectively. One patient developed grade II acute GVHD, and two patients developed limited chronic GVHD. One patient experienced secondary GF requiring a second transplant. At a median follow‐up of 69 months (7–110), all patients are alive and thalassemia free. Our data emphasize the need for extended family HLA typing for patients with thalassemia major in regions where there is high rate of consanguinity. Transplant from non‐sibling matched family donor can result in excellent outcome.
Pilot study of oral metformin in cancer‐bearing cats
Authors: Wypij J. M. 
Published: October 2015

AbstractA prospective dose escalation pilot study was performed in cancer‐bearing cats to assess toxicity and surrogate biomarkers of pharmacologic activity of oral metformin hydrochloride. Nine cats with measurable spontaneous cancer were treated with oral metformin for 14 days. Monitoring included complete blood count (CBC), serum biochemistry, lactate,pH, insulin‐like growth factor‐1, and vascular endothelial growth factor serially until study completion. At the maximum tolerated dose of 10 mg kg−1q12 h side effects were primarily mild to moderate gastrointestinal upset (anorexia, vomiting, and/or weight loss). All cats developed a reduction in haematocrit. Six of nine cats developed new or progressive hyperlactatemia and one cat developed asymptomatic lactic acidosis. There were no clinical responders and two cats had modest measurable reduction in tumour size. In conclusion, we demonstrate potential pharmacologic activity of metformin at a clinically relevant dose and identify parameters for clinical monitoring and supportive care. Further investigation of metformin in cancer‐bearing cats is warranted.
Combined FIV and VIV Effects on a Cantilevered Pipe Discharging Fluid in Deep Waters
Authors: Meng Shuai , Kajiwara Hiroyuki , Srinil Narakorn 
Published: October 2015

To avoid or mitigate global warming, several ocean carbon capture and storage concepts have been proposed. One of the recent approaches is to dispose carbon dioxide via a fixed vertical cantilevered pipe onto the seabed in deep waters. Due to a high aspect ratio and flexibility of such long pipe conveying fluid with fixed-free end conditions and external hydrodynamic loading caused by currents, the pipe may experience large-amplitude 3-D vibrations leading to structural failure. Hence, it is essential to understand and investigate the pipe nonlinear dynamic behaviors subject to combined flow-induced vibration (FIV) and vortex-induced vibration (VIV).
In this study, the 3-D nonlinear equations of a cantilevered pipe discharging fluid in the sea are analyzed using a Galerkin-based multi modal approach combined with a finite difference Houbolt’s integration scheme. Particular attention is paid to the combined effects of FIV and VIV on the dynamic response of the cantilevered pipe in water. To model the fluctuating lift and drag forces associated with VIV, the two dimensional wake oscillators distributed along the pipe are adopted. Numerical simulations in the FIV case of a pipe discharging fluid in the air are first validated with experimental results in the literature to justify the mathematical models and numerical approaches. Modal convergence analysis is also performed. Results in the combined FIV and VIV cases are then highlighted in order to show the effects of cross-flow and in-line VIV when compared with the pure FIV case. The effects of geometric nonlinearities, the coupling/interaction of multi modes and the space-time modifications of pipe responses and trajectories are highlighted. It is hoped that the numerical observations and findings obtained from this study could be verified by experimental studies which are presently lacking in the literature.
Long Term Analysis for Estimation of Wave Slamming Pressures for Spar Design
Authors: Lim Ho-Joon , Lian Gunnar , Haver Sverre , Dalane Oddgeir , Koo Bonjun , Sablok Anil , Lambrakos Kostas 
Published: October 2015

A long term analysis was performed to determine extreme wave slamming loads on the Aasta Hansteen Spar, the first production and storage Spar to be installed in the Norwegian Sea. The Spar will experience high slamming pressures on the hull due to harsh environments in the field. Extensive model tests were performed to measure the wave slamming pressure which is one of challenging design parameters.
The slamming loads were measured with a 3×3 array of force transducer panels attached to the Spar hull. The extreme slamming loads were estimated from 3-hour simulations of the 100-yr and 10000-yr wave environments at the Aasta Hansteen field in the Norwegian Sea. The wave simulations included fourteen sea states, and each sea state was represented by as many as 20 realizations.
Based on model test data, short term analysis of 3-hour extreme pressure at each tested sea state was performed using the Gumbel distribution. Due to high variability of 3-hour maximum pressures, a long term analysis was required to investigate the proper percentile level to be used in the design.
The paper presents a long term statistical methodology for extreme wave slamming loads that is used to calculate long term slamming pressures corresponding to a specified annual exceedance probability of q (e.g., q = 10−2 and q = 10−4). The paper also derives the appropriate non-exceedance probability for a short term wave environment that reproduces the long term pressures of a specified annual exceedance probability, q.
Various sensitivity analyses (e.g., on the two Gumbel parameters, number of realizations, etc.) were performed to validate the short term target percentiles and associated extreme pressures derived from this approach.
Details of the model tests and methodology to define the design pressure profile above mean water level (MWL) are presented in a companion paper of this Conference.
Practical Design Considerations for Managing Marine Growth on VIV Suppression Devices
Authors: Allen Don W. , Lee Li , Henning Dean , Liapis Stergios 
Published: October 2015

Most deepwater tubulars experiencing high currents frequently require vortex-induced vibration (VIV) suppression to maintain an acceptable fatigue life. Helical strakes and fairings are the most popular VIV suppression devices in use today.
Marine growth can significantly affect the VIV of a bare riser, often within just a few weeks or months after riser installation. Marine growth can have a strong influence on the performance of helical strakes and fairings on deepwater tubulars. This influence affects both suppression effectiveness as well as the drag forces on the helical strakes and fairings. Unfortunately, many VIV analyses and suppression designs fail to account for the effects of marine growth at all, even on a bare riser.
This paper utilizes results from both high and low Reynolds number VIV test programs to provide some design considerations for managing marine growth for VIV suppression devices.
Estimation of the Damping Parameter Governing the VIV of Long Flexible Cylinders
Authors: Rao Zhibiao , Vandiver J. Kim 
Published: October 2015

Much effort in the past half century has been made to explain the role of damping in the prediction of VIV. Scruton (1965), Griffin et al. (1975), Klamo, et al. (2005) and Govardhan & Williamson (2006) all made significant contributions. None fully characterized the role of damping in governing the response over the full range reduced velocities, which encompass the wake synchronized region. In 2012 Vandiver devised a way to do that with a new damping parameter c*. His results were verified using 2D spring-mounted cylinders in uniform flow.
The primary objective of the research described in this paper is to find a c* -like quantity for flexible cylinders, which is capable of organizing response data for flexible cylinders, which may have many modes, be exposed to sheared flows and possess spatially varying properties, such as the coverage of strakes and fairings. Data from a recent high mode VIV model test campaign conducted by SHELL Exploration and Production Company are used to illustrate the application of c* to flexible cylinders. It is shown that, if one accounts for Reynolds number, the response of flexible cylinders with varying strake coverage in the SHELL Tests collapse onto a single curve.
A New Quantitative Assessment of Current Profile Clustering Methods for Riser Engineering
Authors: Jeans Gus , Gibson Richard , Jones Oliver 
Published: October 2015

This paper presents a new quantitative approach of defining current profiles for application to riser fatigue assessment using profile clustering methods.
The analysis presented here was undertaken using a one year long deepwater current profile dataset from the Gulf of Mexico. The data included near full water column measurements in 3250m water depth at one hour intervals, providing nearly 9000 individual profiles. Riser fatigue damage for each profile had been previously computed as part of the Worldwide Approximation of Current Profiles (WACUP) joint industry project.
The new assessment described in this paper applies clustering methods not considered in WACUP, including the K-Means Algorithm (KMA) and Maximum Dissimilarity Algorithm (MDA). These both demonstrate superior performance compared to a much simpler direct method of characterisation. Features of the KMA and MDA methods are contrasted, within the context of previously published application to ocean wave data.
Evaluation of Spar In-Field Performances for Topsides Payload Increase and Operational Changes
Authors: Baquet Aldric , Zhou Joe , Xu Lixin , Chen Yong 
Published: October 2015

In the initial design stage of an offshore platform, some conservative assumptions might be used for the platform hull and Topsides weights, wind area and Metocean criteria of environments. After the platform is installed, actual results from weight surveys and real-time snapshots of the as-built operating platform typically provide more accurate information for the purpose of assessing real operational conditions and future changes of these conditions. For example, in field operations, it is particularly useful to quantify how much weight can be added to the as-built operating facility, while assuring that the platform still meets the overall design criteria and regulatory requirements.
This paper presents an effective method for evaluation of an in-field operating Spar platform, to determine the maximum allowable envelops for topsides weight change verse the topsides VCG, based on the Spar global performances and riser operating limits. The case study is performed for a Spar in the Gulf of Mexico (GOM), based on the Spar as-built data and actual in-field configurations of hull/mooring and risers, and using the updated Metocean criteria (after the Hurricane Katrina in the GOM).
The analysis results of the allowable topsides weight change and topsides VCG limits, accounting for the Spar in operating, extreme and survival conditions, are based on three governing factors: (1) the Spar motions meet the original design criteria for global performances, and are within the safety range of riser operations; (2) the maximum loads at critical connections between the Spar hard tank and the topsides structures are within the design loads; and (3) the reserve variable ballast is sufficient to balance the Spar at an even keel position at the design draft for all required operating conditions.
The Pros and Cons of Wall Functions
Authors: Eça Luís , Saraiva Gonçalo , Vaz Guilherme , Abreu Hugo 
Published: October 2015

Simulations of viscous flows based on the Reynolds-Averaged Navier-Stokes (RANS) equations have become an engineering tool used on a daily basis. One of the main goals of such calculations is to determine friction forces, which are a consequence of the shear-stress at solid walls.
In RANS (and other more sophisticated mathematical models), there are two main approaches for the determination of the shear-stress at a wall: direct application of the no-slip condition, i.e. the velocity gradient is determined directly at the surface; wall functions which determine the shear-stress at the wall from semi-empirical equations applicable up to the outer edge of the so-called “wall layer/log layer”. Although the first option is physically preferable, its numerical requirements may lead to iterative convergence problems and/or excessive calculation times. Therefore, especially at high Reynolds numbers, it is not unusual to use the latter approach.
In this paper we discuss the advantages and disadvantages of wall-function boundary conditions. To this end we have calculated the flow around a flat plate, conventional and laminar airfoils and a circular cylinder. The influence of the location where wall functions are applied (distance to the wall) and the effect of the Reynolds number (ranging from model to full scale applications) are discussed. Griding requirements for wall-function boundary conditions are also addressed. The results obtained with wall functions are compared with those obtained from the direct application of the no slip at the wall.
The results obtained in this study show that the use of wall functions in viscous flow calculations may be justifiable or completely unacceptable depending on the flow conditions. Furthermore, it is also shown that wall-function boundary conditions also require clustering of grid nodes close to the wall, but obviously less demanding than the direct application of no slip condition.
Coupled Axial/Lateral VIV of Marine Risers in Sheared Currents
Authors: Zanganeh Hossein , Srinil Narakorn 
Published: October 2015

Modelling and prediction of vortex-induced vibrations (VIV) of marine risers is a challenging task due to the associated multi degrees of freedom in both cross-flow/in-line directions and the multi-mode fluid-structure interactions. In addition, the axial motion and its geometrically nonlinear coupling with lateral responses can be significant, especially at higher-order modes. Nevertheless, several papers in the literature dealing with VIV predictions have often overlooked such aspects. Therefore, this study aims to investigate and understand the effect of axial or longitudinal motion through a theoretical model and numerical approach in time domain.
Attention is paid to VIV of vertical risers subjected to linearly sheared currents. To capture a three-dimensional aspect of the flexible cylinder experiencing VIV, a semi-empirical model is developed consisting of nonlinear equations of cross-flow, in-line and axial structural oscillations which are coupled with the distributed van der Pol-type wake-oscillators modelling the fluctuating fluid lift/drag forces. The mean drag force is also taken into account. These model equations are numerically solved via a space-time finite difference scheme, and the obtained numerical results highlight several aspects of VIV of elastic cylinders along with the axial motion effects.
Apart from the validation of the numerical model with published experimental results, this study reveals how the effect of axial motion and its nonlinear coupling with the two lateral cross-flow/in-line motions can be very important. These depend on the flow velocity, the fluid-structure parameters, the single or multi-mode lock-in condition, and the standing-wave or travelling-wave feature. We recommend that the axial response should be accounted for in VIV analysis and prediction model.
Simulations for Design and Reconstruction of Breaking Waves in a Wavetank
Authors: Kurnia R. , van den Munckhof T. , Poot C. P. , Naaijen P. , Huijsmans R. H. M. , van Groesen E. 
Published: October 2015

To determine forces on fixed and flexible structures such as wind mills and oil platforms, experiments in wave tanks are useful to investigate the impacts in various types of environmental waves. In this paper we show that the use of an efficient simulation code can optimize the experiments by designing the influx such that waves will break at a predefined position of the structure. The consecutive actual measurements agree well with the numerical design of the experiments. Using the measured elevation close by the wave maker as input, the software recovers the experimental data in great detail, even for rather short (up to L/D=1) and very steep breaking waves with steepness parameter (ak) till 0.4.
The experiments were carried out in the TUD-wavetank and the simulation is done by HaWaSSI-AB, a spatial-spectral implementation of a Hamiltonian Boussinesq model with an eddy-viscosity breaking mechanism that is initiated by a kinematic breaking condition.