bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prolonged Ablation on Critical Segments of Pulmonary Vein Ostia in Paroxysmal Atrial Fibrillation: A Prospective Randomized Controlled Study
Authors: KRIATSELIS CHARALAMPOS , KAUFMANN JAN , NEDIOS SOTIRIOS , TANG MIN , GERDS‐LI JIN‐HONG , FLECK ECKART 
Published: November 2013

IntroductionElectrical reconnection of the pulmonary veins (PVs) plays a key role in the recurrence of atrial fibrillation (AF) after ablative treatment. This randomized controlled study tested the hypothesis that prolonged ablations, on areas that may be critical for left atrial (LA)‐PV conduction, can significantly reduce the rate of acute PV reconnection and AF recurrence.MethodsPatients with paroxysmal AF were randomly assigned to either a control or an add‐on group. Ostial PV isolation (PVI) was performed by point‐to‐point RF ablation (irrigated tip, 30 Watts, 30 seconds). An ostial segment was assumed to be critical for LA‐PV connection if any of the following reactions occurred during RF application: (1) sudden delay of LA‐PV conduction, (2) change of activation sequence, and (3) PVI. In this case, RF application was prolonged from 30 seconds to 90 seconds in the add‐on group only.ResultsA total of 131 patients (58 ± 11 years, 47 female) were assigned to a control (n = 64) and an add‐on (n = 67) group. Ablation time was longer in the add‐on (48 ± 16 minutes vs 37 ± 15 minutes, P = 0.03). Acute PV reconnection was observed in 20 of 64 controls and in eight of 66 add‐on patients (31% vs 12%, P < 0.001). During a follow‐up of 26 months, AF recurred in 33 of 64 controls and in 16 of 66 add‐on patients (52% vs 24%, P = 0.001) after a single ablation procedure.ConclusionsProlonged radiofrequency application on critical segments of LA‐PV connection is a safe and effective ablative strategy that significantly reduces acute PV reconnection and AF recurrence rates after a single ablation procedure for paroxysmal AF.
A Case of Phrynoderma in a Patient with Crohn's Disease
Authors: Cobos Gabriela , Cornejo Christine , McMahon Patrick 
Published: November 2013

AbstractPhrynoderma is a type of follicular hyperkeratosis associated with nutritional deficiencies. It is rarely seen in developed countries, although cases have been reported in patients with severe malnutrition or malabsorption secondary to various causes. This report describes a 19‐year‐old patient with poorly controlled Crohn's disease and malnutrition who developed the characteristic hyperkeratotic papules and plaques on his trunk and extremities in the setting of low serum vitamin A levels. To our knowledge, there are no reports of phrynoderma associated with Crohn's disease. It is likely that our patient's low vitamin A level and subsequent phrynoderma was the result of increased Crohn's disease activity and malnutrition.
Factors influencing timing of neonatal discharge in Japan: Retrospective study
Authors: Ishida Yasushi , Nagaoki Yuko , Nakagawa Machiko , Hirata Michio , Shimabukuro Rinshu , Kusakawa Isao , Hosoya Ryota , Fukui Tsuguya 
Published: November 2013

AbstractBackgroundThe aim of this study was to evaluate the birth and discharge dates of neonates and analyze their distribution over days of the week and the old lunar calendar.MethodsA retrospective study of the neonates discharged in the years 1990, 2000, 2005, and 2010 was conducted in a general hospital in Tokyo, Japan. Data are represented as odds ratios (OR) of the total number of discharges per day divided by the expected number of days per year, for each day of the week as well as each 6 day cycle of the lunar calendar.ResultsThe timing of discharge has an uneven distribution across the days of the week, with weekday discharge rates significantly lower than weekend discharge rates. This uneven distribution is particularly significant in the preterm subgroup. In contrast, there is a minor uneven distribution of births across the days of the week and that of discharges across the 6 day cycle of the lunar calendar. Logistic regression analysis for 2005 and 2010 identified admission fee paid by insurance and prematurity as significant factors associated with weekend/holiday discharge (OR, 1.84; 95% confidence interval [CI]: 1.23–2.75; OR, 1.71; 95%CI: 1.15–2.55, respectively). The average length of stay of neonates discharged on the weekend was longer than that for those discharged on a weekday, in both term and preterm infants.ConclusionsJapanese parents prefer the convenience of weekends over old superstitions about using the lunar calendar to determine the discharge date.
Analysis of 66 patients definitive with transfusion‐associated graft‐versus‐host disease and the effect of universal irradiation of blood
Authors: Uchida S. , Tadokoro K. , Takahashi M. , Yahagi H. , Satake M. , Juji T. 
Published: November 2013

SUMMARYBackgroundTransfusion‐associated graft‐versus‐host disease (TA‐GVHD) is a potentially fatal adverse reaction to blood transfusion. Although TA‐GVHD was formerly considered to be rare and to occur only in immunocompromised patients, it was confirmed to occur even in immunocompetent patients in Japan, based on a definitive diagnostic test for TA‐GVHD using highly polymorphic microsatellite repeat sequences. We clarify the clinical picture of TA‐GVHD via definitive diagnosed cases and argue the validity of blood irradiation for TA‐GVHD prevention.Patients and methodsTwo‐hundred and ninety patients who were suspected of having TA‐GVHD and referred to us for diagnostic testing from October 1992 to August 1999 were analysed for the associated clinical characteristics and risk factors. Effects of universal irradiation were followed up until 2010.ResultsSixty‐six of the 290 study patients were diagnosed as having definite TA‐GVHD by microsatellite DNA analysis. Regarding the symptoms of patients with definite TA‐GVHD, a fever of over 38 °C, erythema and leucocytopenia were found in virtually all of these patients. Among patients in whom human leucocyte antigen (HLA) typing was carried out, TA‐GVHD almost always developed in HLA heterozygous patients following the transfusion of HLA homozygous blood. TA‐GVHD was reported significantly more frequently in older patients. In this study, TA‐GVHD was caused by the transfusion of HLA one‐way match blood stored for 14 days.ConclusionNo cases of TA‐GVHD development have been confirmed since 2000, when the supply of irradiated blood products became widespread. No major problems have been encountered since the start of universal irradiation, more than 10 years ago.
Ocean Power Generator Using Flexible Piezoelectric Device
Authors: Mutsuda Hidemi , Watanabe Ryuta , Azuma Shota , Tanaka Yoshikazu , Doi Yasuaki 
Published: November 2013

We have developed a way of harvesting electrical energy from ocean power, e.g. tide, current wave, breaking wave and vortex, using a Flexible PiezoElectric Device (FPED) consisting of polyvinyledene fluoride (PVDF) and elastic material such as rubber, silicon and resin. The proposed FPED has a multi-layered structure with a distance δ between FPEDs located away from centerline of the FPED. When the FPED can be easily deformed by ocean power, the PVDF laminated in the FPED can be expanded and compressed and then the internal strain energy can be stored in the FPED. The electric power is generated when the electric polarization occurs in the PVDF.
In this study, we have proposed an ocean power generator of EFHAS (Elastic Floating unit with HAnging Structures) consisting of floating unit and hanging unit using the FPEDs to obtain electric power from ocean energy. We investigated a structure of the EFHAS and also examined characteristics of motion and electric performance of the EFHAS (1/50–1/75 scale model. We made clear that the EFHAS could be useful as ocean power generator.
Polar Lows and Their Implications on Marine Operations: Survivability Criteria
Authors: Pakkan Meric , Heng David , Gudmestad Ove Tobias 
Published: November 2013

The oil resource potential in the Arctic/sub-Arctic regions is estimated to be as high as that 25% of the world’s yet-to-be-found. Nevertheless, operating in above-mentioned regions is more complicated and expensive than the ones in the North Sea. One of the most important aspects to consider in operating in these Arctic regions is the presence of polar lows and arctic fronts and storms. These extreme events and implications of them on the marine operations were the main focus of this study.
While the maximum polar low-sourced wind speeds for 10-, 20- and 100-year return periods are estimated to be 55.37, 60.93 and 73.52 knots, the maximum polar low-sourced wave heights for 10-, 20- and 100-year return periods are calculated as 5.71, 6.66 and 8.82 meters, respectively.
It is found out that polar lows weather conditions do not normally represent design values (survival conditions); however, they represent operational limitations.
• We conclude that operations lasting longer than 72 hours shall be designed for a rougher weather than the polar lows lead to (survival mode).
• For operations of duration less than 72 hours, the weather forecast is crucial and it must also be possible to abort the operation within a short period if one is close to a polar weather front as a polar low may appear very quickly.
Wave Power Extraction by an Oscillating Wave Surge Converter in Random Seas
Authors: Sarkar Dripta , Renzi Emiliano , Dias Frederic 
Published: November 2013

This paper investigates the behaviour of a bottom hinged flap-type wave energy converter (WEC), namely the Oscillating Wave Surge Converter (OWSC), in random seas. The semi-analytical model of Renzi and Dias (2013b) for an OWSC in the open ocean is considered to analyze the performance of the device in random incident waves. The modelling is performed within the framework of a linear potential flow theory, by means of Green’s integral theorem. The resultant hypersingular integral equation for the velocity potential obtained from the above formulation is solved using a series expansion in terms of Chebyshev polynomials of the second kind.
The behaviour of the device is investigated for six different sea states, generally representative of the wave climate in the North Atlantic Ocean at the European Marine Energy Centre test site. A Bretschneider spectrum is considered in order to reproduce the sea climate. The analysis is made for sea states where the spectral energy contribution from large periods, which cause excitation of body resonance of the flap — not modelled by the linear theory — is almost negligible. The power take-off damping is optimised for each individual sea state to calculate the captured power.
The investigation is undertaken for two flaps of different widths, resembling the Oyster1 and the new Oyster800 version of the Oyster WEC, respectively. Comparison is made between the performances of the two converters. The effect of varying the width and the characteristic parameters of the flap on the capture factor in random seas is then discussed.
The results of the analysis show that the performance of the device is fairly consistent for the sea states considered. Also an enhancement in the overall average capture factor is shown for the latest version of the wave energy conversion device.
Design for Arctic Conditions: Safety and Performance Issues
Authors: Barabadi Abbas , Naseri Masoud , Ratnayake R. M. Chandima 
Published: November 2013

The harsh climate conditions and vulnerability of the Arctic wilderness can both heighten the risk related to HSE (human, safety and environment) and limit the effectiveness of any activities which are carried out to control such risks. To manage and control these risks, it is vital to reduce the probability of failure of critical components in the corresponding industrial setting. In order to accomplish the aforementioned, it is essential to have an accurate prediction of failure characteristics (e.g. failure modes, time to failure and failure mechanisms) and the consequence of failure which can be taken into consideration during the design phase. It is possible to gather such information by means of an effective risk and dependability analysis.
However, in practice, conducting a dependability and risk analysis is a challenging process for an industrial setting, such as that which is functioning in the Norwegian Arctic. This is mainly due to the lack of historical data about possible activities which are unique to the region. Hence, it is paramount to develop a methodology to facilitate the analysis, using the available data experience and technological solutions which can be retrieved from similar or more challenging situations as a reference to improve the robustness of the current design. This paper reviews the main technical and technological challenges of the operations in the Arctic region. Then, it provides a methodology to take risk and dependability analysis for Arctic conditions into consideration in the design phase. This methodology is demonstrated by a case study for design in the Barents Sea based on the available data collected in the North Sea and the Norwegian Sea.
Calculation of Wave Forces on Cylindrical Piles Using a 3D Numerical Wave Tank
Authors: Kamath Arun , Bihs Hans , Arntsen Øivind A. 
Published: November 2013

Offshore constructions generally include a large number of vertical cylinders in the support structure. The calculation of wave forces on a vertical cylinder and hydrodynamic effects on it in the presence of neighbouring cylinders is of practical interest. In this paper, a 3D numerical model is used to calculate wave forces on bottom fixed cylindrical piles. Two cases are considered in this study: a single cylinder and a pair of tandem cylinders. A scenario with multiple cylindrical structures in close proximity introduces complex wave-structure interactions and would be of great interest to observe this in detail in a three-dimensional simulation. The wave force exerted on a cylindrical pile is numerically calculated by integrating the pressure and the wall shear stress around the surface of the cylinder. In the case of the single cylinder, the force calculated by the model is compared to the force predicted by the Morison formula and MacCamy-Fuchs theory. In the second case, the pair of cylinders is aligned in the direction of the incoming waves. The numerically calculated inline wave force on each cylinder is compared to the analytical solution for this setup and a good agreement is seen.
The Reynolds-Averaged Navier-Stokes equations are used as the governing equations for the fluid flow in the numerical model. The convective terms are discretized using a 5th-order conservative finite difference WENO scheme. A 3rd-order accurate TVD Range-Kutta scheme is used for time discretization. Chorin’s projection method is used to discretize the pressure. The Poisson equation for pressure is solved using a preconditioned BiCGStab algorithm. The level set method is used to obtain a sharp representation of the free water surface. Turbulence in the flow is simulated using the k-ω model. The numerical model is adapted to parallel processing using the MPI library to improve the computing performance of the code.
Full Scale CFD Validation on Thruster-Hull Interaction on a Semi-Submersible Crane Vessel in Transit Condition
Authors: Ottens Harald , Bulten Norbert , van Dijk Radboud 
Published: November 2013

Heerema Marine Contractors operates three semi-submersible crane vessels; the Thialf, Balder and Hermod. The first two vessels are equipped with a DP system. The ability of each crane vessel to keep its position depends highly on the performance of the DP system of that crane vessel. The thrust efficiency of the DP system depends on the efficiency of the individual thruster, but also on the interaction of the thruster wake and the hull of the vessel.
Thruster-hull interaction is important during operations, but also during transits from one location to another. During the transits of the Balder and Thialf, the DP thrusters are used as propulsion. Understanding the thruster-hull interaction effects in this transit condition can result in an optimum thrust setting.
In previous validation studies CFD was used to assess the current loads and the thruster-hull interaction on a semi-submersible vessel. In these studies the CFD results were validated with a series of dedicated model tests. The comparison between the CFD and model test data shows that CFD is able to predict the relevant force components within a sufficient accuracy for engineering purposes.
However, Heerema Marine Contractors is mainly interested in full scale data. Unfortunately, not much full scale data is available to validate the extrapolation of model test and CFD results to full scale thruster efficiency. Therefore a first validation study is performed based on acquired full scale data during a transit of the Thialf in Q4 2011. Comparing the full scale test data with the CFD results shows that the CFD can be used to predict which settings is the most efficient.
Optimization of thruster settings on semi-submersible vessels is not trivial due to number and location of the azimuth thrusters. Using CFD simulations the power settings and azimuth angles of the thrusters were changed to obtain the optimal thrust setting during transit. In Q2 2012 the Thialf made her first transit after a dry-dock period in which the hull was cleaned and painted. Repeating similar tests conditions as in Q4 2011 demonstrates the effect of a clean hull. Additional tests demonstrated the effect of a more efficient thrust setting originated by the CFD results. The implications of the optimized azimuth setting in transit on the life time of the thruster is verified using CFD and FEM.
The paper addresses lessons learnt to improve the CFD simulations as well as practical aspects and limitations of thrust efficiency modeling using CFD. It demonstrates that CFD can be used to understand the associated flow physics and that CFD can be used to predict improvements in thrust efficiencies. In addition, some lessons learnt on full scale monitoring will be addressed.
Development on Aegir Reeling Pipeline Analyses by Test Validation
Authors: Karjadi Erwan , Boyd Helen , van Rooijen Reinout , Demmink Harm , Balder Thomas 
Published: November 2013

Heerema Marine Contractors (HMC) is entering a new era of laying pipelines using the reel-lay method in order to be more cost effective for deep and shallow water pipeline installation projects. The new Deep water Construction Vessel (DCV) Aegir is designed to be able to reel/J-lay pipelines for a range of pipe dimension and water depth combinations. The paper describes how the full reeling cycles Finite Element Analysis (FEA) of the Aegir have been developed step by step from the development of the bend rig test, spooling-on to spooling-off FE models which is validated by the bend rig test program. The required material test program is performed to characterize the correct material behavior under plastic cyclic straining.
The know-how from the validation of the FEA of bend rig tests by performing the bend tests program is used to setup the full-reeling cycles simulation of spooling-on pipeline on the yard and spooling-off pipeline on board of the Aegir. A series of bend rig tests have been performed at Heriot-Watt University. Ovality measurements from the tests are compared with the predicted results from the bend rig FEA simulation model. Based on small scale specimen tests which are performed to describe the proper material behavior under plastic cyclic straining, a new material model has been proposed and discussed to provide a correct prediction of ovalization against the number of bend cycles. Comparison between the bend rig test measurements and the Aegir full reeling cycles simulation results is made by comparing the deformation of the pipe (ovalization) against a number of bend cycles. Discussion is given to justify the difference in the outcomes as well as the representation of the bend tests program for the qualification test program for reeling with the Aegir.
An Ensemble Kalman Filter Data Assimilation Scheme for Modeling the Wave Climate in Persian Gulf
Authors: Serpoushan Nima , Zeinoddini Mostafa , Golestani Maziar 
Published: November 2013

In recent years, application and evaluation of the efficiency of different data assimilation methods has been a subject of interest in both wave hindcasting and forecasting systems. The main goal of the current study is to assess the efficiency of an ensemble Kalman filter (EnKF) data assimilation scheme in improving the wave simulation results in Persian Gulf. The so called region plays an important role in the oil and gas industry due to its Geographical and Morphological location and housing a large number of offshore platforms.
A third generation wave model, SWAN, was employed in order to simulate the wave fields in the region. The three hours updated ECMWF wind data were used as the main driving force. The OpenDA toolbox, especially developed for efficient data assimilation purposes, was employed to smooth the chaotic nature of the non-linear wave simulation scheme. The OpenDA utilizes a number of methods that are based on Kalman filter algorithm but do not require the amount of computation efforts that are incurred by the classical filter algorithm. The EnKF is a variant of Kalman filter, where probability density function of a model state is represented by an ensemble of the model state.
Two sets of records for significant wave heights and peak wave periods were used in the analysis process with EnKF to estimate the error covariance matrix. At analysis time, the forecast error covariance was computed by using the model forecasts ensembles. In overall and for the wave climate modeling, the initial conditions of the numerical model were updated using the improved system state, up to the current computing time level. This is achieved by incorporating the previous measurements into the Kalman filter algorithm. The model was then run into the future, driven by the new improved state conditions.
The statistical results and diagrams showed that applying EnKF scheme leads to a noticeable improvement in significant wave heights. However, the accuracy of this technique was subjected to the location and number of observation stations and also ensemble size. With larger ensembles, results of error covariance estimation are more accurate but there is a limitation due to execution time of process and efficiency of the computations.
Analysis of Pusher-Barge System With Different Maneuvering and Propulsion Devices
Authors: Yuba Douglas T. G. , Tannuri Eduardo A. 
Published: November 2013

Pusher-barge system with different maneuvering and propulsion devices were modeled and analyzed. Both azimuth thrusters and conventional propulsion system (which is composed by rudder and propeller) were considered in the pusher. An additional azimuth thruster installed on the bow of the barges was also analyzed, in order to increase the maneuverability of the convoy.
Hydrodynamic derivatives for different pusher-barge configurations used in Tietê-Paraná river (B × L = 2 × 3, 1 × 2 and 1 × 1) were obtained from previously published works and complemented by captive model tests and CFD calculation executed in the context of the present project, presented in a complementary paper in this conference Grassi et al. (2013). Numerical models for each propulsion and maneuvering devices were obtained by standard formulations. A time-domain simulator was then implemented and the standard zig-zag and turning circle tests were simulated to compare performance of the different maneuvering and propulsion devices.
It was verified that pushers equipped with azimuth thrusters can increase the maneuverability of the system for slow speed navigation. For higher speeds, the conventional rudder and propeller pusher presents similar or even better maneuvering properties, since the effectiveness of the rudder increases.
The additional bow azimuth thruster can also improve maneuverability parameters, since the force applied at the bow increases the turning moment. However, its efficiency depends also on the speed and the instantaneous pivot-point of pusher-barge system. A broad discussion about the advantages and physical limitations of this additional bow azimuth thruster is presented.