bluuebunny/crossref_metadata_2025_split huggingface dataset:
Risk factors for postoperative hemorrhage following tonsillectomy
Authors: Tomkinson Alun , Harrison Wendy , Owens David , Harris Susan , McClure Victoria , Temple Mark 
Published: November 2010

AbstractObjectives/Hypothesis:To identify the main risk factors associated with postoperative hemorrhage following tonsillectomy.Study Design:Prospective multicenter observational study.Methods:The Surgical Instrument Surveillance Programme (SISP) was established in 2003 to monitor tonsil and adenoid surgery and the associated complications in all hospitals in Wales. Data were examined between April 1, 2003, and June 30, 2008, by using binary logistic regression, for risk factors that may contribute to primary (R1) or secondary (R2) postoperative hemorrhage of a severity sufficient to require a return to the operating theater.Results:A total of 17,480 procedures were included. Patients aged ≥12 years were 1.5 (1.0–2.1; P < .05) and 3 times (2.2–4.9; P < .0001) more likely to experience R1 and R2 complications, respectively. There were 2.5 times as many females as males aged ≥12 years who underwent tonsillectomy, but males were almost twice as likely to experience R1 (1.4–2.8), P < .0001, or R2 (1.2–2.5), P < .001, postoperative hemorrhage. There was a 1.9‐fold increased likelihood of R1 (1.1–3.3), P < .05, with the most junior surgeon, and no relationship with R2. All techniques that used heat had a significantly greater adjusted odds of R2 as compared with cold dissection, with odds ranging from 2.7 (1.5–4.7), P < .001, for dissection plus bipolar diathermy and ties, to 13.0 (5.8–29.1), P < .0001, with coblation when used with other techniques. No additional risk was associated with specified single‐use instruments.Conclusions:Patient age and sex and operative technique were the most significant factors affecting the risk and timing of serious postoperative hemorrhage, with no additional risk associated with the use of specified single‐use instruments. Laryngoscope, 2010
Improving apparent diffusion coefficient estimates and elucidating tumor heterogeneity using Bayesian adaptive smoothing
Authors: Walker‐Samuel Simon , Orton Matthew , Boult Jessica K. R. , Robinson Simon P. 
Published: November 2010

AbstractThe spatial distribution of apparent diffusion coefficient (ADC) estimates in tumors is typically heterogeneous, although this observed variability is composed of both true regional differences and random measurement uncertainty. In this study, an adaptive Bayesian adaptive smoothing (BAS) model for estimating ADC values is developed and applied to data acquired in two murine tumor models in vivo. BAS models have previously been shown to reduce parameter uncertainty through the use of a Markov random field. Here, diffusion data acquired with four averages was used as an empirical gold standard for evaluating the BAS model. ADC estimates using BAS displayed a significantly closer accordance with the gold standard data and, following analysis of uncertainty estimates, appeared to even outperform the gold standard. These observations were also reflected in simulations. These results have strong implications for clinical studies, as it suggests that the BAS postprocessing technique can be used to improve ADC estimates without the need to compromise on spatial resolution or signal‐to‐noise or for the adaptation of acquisition hardware. A novel measure of tumor ADC heterogeneity was also defined, which identified differences between tumors derived from different cell lines, which were reflected in histological variations within the tissue microenvironment. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.
Regional and global pancreatic T*2 MRI for iron overload assessment in a large cohort of healthy subjects: Normal values and correlation with age and gender
Authors: Restaino Gennaro , Meloni Antonella , Positano Vincenzo , Missere Massimiliano , Rossi Giuseppe , Calandriello Lucio , Keilberg Petra , Mattioni Oreste , Maggio Aurelio , Lombardi Massimo , Sallustio Giuseppina , Pepe Alessia 
Published: November 2010

AbstractMultiecho gradient‐echo T*2 magnetic resonance imaging is a well‐established technique for iron overload assessment but there are few reports concerning the pancreas. The aim of this work was to assess the feasibility and reproducibility of the magnetic resonance imaging for measuring pancreatic regional and global T*2 values, to establish the lower limit of normal in a large cohort of healthy subjects and to correlate the measured values with age and gender. One hundred and twenty healthy subjects (61 males, 51 ± 17 years) underwent magnetic resonance imaging (1.5T) using a multiecho gradient‐echo T*2 sequence. T*2 measurements were performed in pancreatic head, body, and tail. The global value was calculated as the mean. Measurement of pancreatic T*2 values was feasible in all subjects. For the T*2 global value the coefficient of variation for intraoperator and interoperator reproducibility were 7.7% and 13%, respectively. The global T*2 values ranged from 24 to 52 ms with the lower limit of normal of 26 ms. There were no significant differences among the regional pancreatic T*2 values. No significant correlation was found between T*2 and patient age or gender. In conclusion, pancreatic T*2 measurements appear to be feasible, reproducible, nontime‐consuming and reliable. Gender‐ and age‐related differences concerning pancreatic T*2 were not found. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.
Accelerated multidimensional radiofrequency pulse design for parallel transmission using concurrent computation on multiple graphics processing units
Authors: Deng Weiran , Yang Cungeng , Stenger V. Andrew 
Published: November 2010

AbstractMultidimensional radiofrequency (RF) pulses are of current interest because of their promise for improving high‐field imaging and for optimizing parallel transmission methods. One major drawback is that the computation time of numerically designed multidimensional RF pulses increases rapidly with their resolution and number of transmitters. This is critical because the construction of multidimensional RF pulses often needs to be in real time. The use of graphics processing units for computations is a recent approach for accelerating image reconstruction applications. We propose the use of graphics processing units for the design of multidimensional RF pulses including the utilization of parallel transmitters. Using a desktop computer with four NVIDIA Tesla C1060 computing processors, we found acceleration factors on the order of 20 for standard eight‐transmitter two‐dimensional spiral RF pulses with a 64 × 64 excitation resolution and a 10‐μsec dwell time. We also show that even greater acceleration factors can be achieved for more complex RF pulses. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.
Quantitative diffusion imaging of adipose tissue in the human lower leg at 1.5 T
Authors: Steidle G. , Eibofner F. , Schick F. 
Published: November 2010

AbstractDiffusion‐weighted spin‐echo echo‐planar imaging was developed and applied for assessment of diffusion coefficients of adipose tissue in human lower leg on a 1.5‐T whole‐body MR scanner. Because of the higher molecular weight of triglycerides, apparent diffusion coefficients (ADCs) of adipose tissue are approximately two orders of magnitude smaller compared with water, leading to the necessity of using high b‐values up to 50,000 sec/mm2 and an echo time of 240 msec for sufficient diffusion‐related signal attenuation. ADC maps of adipose tissue in the human lower leg were derived for diffusion encoding along orthogonal spatial directions in six healthy volunteers. Mean diffusion coefficients in the tibial bone marrow amounted to (1.81 ± 0.10) × 10−5 mm2/sec (left–right), (1.96 ± 0.10) × 10−5 mm2/sec (anterior–posterior), and (1.96 ± 0.20) × 10−5 mm2/sec (head–feet), respectively. Pixel‐wise calculated ADC values of subcutaneous adipose tissue showed a distinctly higher variation with the smallest ADC values similar to those measured for tibial bone marrow. Some subcutaneous adipose tissue regions showed increased signal attenuation at higher b‐values resulting in ADC coefficients up to 4.2 × 10−5 mm2/sec. It must be noted that diffusion measurements with extremely high b‐values in vivo are extremely sensitive to incoherent motion effects in tissue. Nonetheless, it could be shown that in vivo diffusion imaging of adipose tissue in human lower leg is possible at 1.5 T in acceptable measurement time of a few minutes. Potential future applications of fat diffusion imaging are seen in temperature measurements in adipose tissue, detection of free fatty acids in white or brown adipose tissue in case of high lipolysis, differentiation of macro‐ and microvesicular steatosis, or assessment of the mobility of intramyocellular lipids. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Prostate cancer metabolite quantification relative to water in 1H‐MRSI in vivo at 3 Tesla
Authors: McLean Mary A. , Barrett Tristan , Gnanapragasam Vincent J. , Priest Andrew N. , Joubert Ilse , Lomas David J. , Neal David E. , Griffiths John R. , Sala Evis 
Published: November 2010

Abstract1H magnetic resonance spectroscopic imaging was performed on 16 men with suspected prostate cancer using an 8‐channel external receive coil at 3 T. Choline and citrate (Cit) signals were measured in prostate lesions and normal‐appearing peripheral zone as identified on T2‐weighted images. Metabolites were quantified relative to unsuppressed water from a separately acquired magnetic resonance spectroscopic imaging dataset using LCModel. Validation experiments were also performed in a phantom containing physiological concentrations of choline, Cit, and creatine. In vitro, fair agreement between measured and true concentrations was observed, with the greatest discrepancy being a 35% underestimation of Cit. In vivo, one dataset was rejected for failure to meet the quality criterion of linewidth <15 Hz, and in 6 of 15 subjects, insufficient normal‐appearing peripheral zone tissue was identified for study. Lesions were found to have higher choline and choline/Cit, and lower Cit, than normal‐appearing peripheral zone. The smaller skew of data obtained using water normalization in comparison with metabolite ratios suggests potential usefulness in longitudinal tumor monitoring and in studies of treatment effects. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Can we accurately measure the onset latency to the first dorsal interosseous?
Authors: Takahashi Nobushige , Robinson Lawrence R. 
Published: November 2010

AbstractWe present two cases with and without a latency difference of the compound muscle action potential (CMAP) from the abductor digiti minimi (ADM) and the first dorsal interosseous (FDI). In each case, onset latencies of FDI CMAPs using the contralateral small finger as E2 were shorter than those of belly–tendon CMAPs from the ADM and FDI. We conclude that onset of the belly–tendon FDI CMAP does not necessarily indicate initial activation of the FDI. Muscle Nerve, 2011
Geometrically nonlinear models in crystal plasticity and the limit of rigid elasticity
Authors: Conti Sergio , Dolzmann Georg , Kreisbeck Carolin 
Published: November 2010

AbstractIt is shown that a standard model in crystal plasticity for which only rigid body motions have finite elastic energy can be approximated in the sense of Γ‐convergence by models with more general elastic potentials. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Damage Localization of Carbon‐Fibre‐Reinforced Plastic Plates
Authors: Ungethuem Andy , Lammering Rolf 
Published: November 2010

AbstractDue to increasing application of light weight structures such as carbon‐fibre‐reinforced plastics well‐known procedures for the examination of components are not always applicable because of inadequate efforts or costs. Therefore, the development of a complementary system is suggested which allows for detecting damages of the structure. A new wave migration model enables to determine the damage location for non‐isotropic plates. The method is based on the propagation of waves reflected at the damage. Piezo‐electric sensors capture the strain caused by the propagating wave. The evaluation and processing of the signals of at least four sensors allow for the calculation of the damage location from the runtime of the signals. In the case of non‐isotropic material the shape of the wave front has to be known for the structure under investigation. These shapes can be obtained for example experimentally due to measurement and monitoring of the wave propagation by a laservibrometer or analytically by calculating this shapes using classical laminate and plate theory. Experiments show that the model indicates the damage location reliably. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Buckling of Carbon Nanotubes: a Molecular Static Approach
Authors: Schwarzbart Michael , Steindl Alois , Troger Hans 
Published: November 2010

AbstractAxially loaded cylindrical continuous shells collapse either globally like a rod (Euler buckling), or locally (local shell wall buckling), depending on the ratio of the length of the shell over the diameter [1]. There are many published investigations, which show that this behaviour is also true for Carbon Nanotubes CNTs [2]. In this work a systematic analysis of the problem is given in the framework of molecular statics. This approach has the advantage of taking care of the discrete structure of CNTs. The covalent bonds of the hexagonal carbon network are modelled as nonlinear springs, and the compressive load is applied quasistatically, excluding follower forces. The software package LAMMPS [3] offers the AIREBO potential [4] and is suitable for describing CNTs. To identify the stability boundary in the parameter plane, LAMMPS is extended to compute the definiteness of the Hessian. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Discretization Effects within Particle Representations of Massive Forming Processes
Authors: Fischer Katrin , Ostermeyer Georg‐Peter 
Published: November 2010

AbstractParticle methods can be used for the simulation of large deformations under large deformation rates which are e.g. characteristic for massive forming processes. Particles' dynamics have to be carefully chosen in order to describe heat and heat flows in a correct thermodynamic way. In the following, mesoscopic particle systems are used, which solve this problem by using internal variables and in addition so‐called hidden mechanical degrees of freedom ( [1], [2]).Another problem of particle methods is the influence of a symmetric discretization of the continuum on the shear planes and yielding. An appropriate interpretation of the simulation results requires a differentiation into physical phenomena and those resulting from the discretization. These circumstances and possible correctives are shown using some examples. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Controller Design for a Test Bench for Seat Belt Systems
Authors: Huber Steffen , Eberhard Peter , Seifried Robert 
Published: November 2010

AbstractIn the product development of vehicle seat belt systems there is a strong need for the possibility of an isolated component testing that is comparable to real world car crashes. A test bench concept that is able to fulfill this requirement is presented. This test bench mainly consists of a highly dynamic actuator system for which a control scheme is presented. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Decentralized Control of an Industrial Robot with Elastic Gears
Authors: Riepl Roland , Gattringer Hubert , Bremer Hartmut 
Published: November 2010

AbstractToday's robots, especially for industrial applications, regularly appear on the market in new shapes, various sizes and challenging configurations. In a certain number of interesting cases, the need for a satisfying joint control will arise, even if the system dynamics is not completely known. Furthermore, despite the fact that most robots' dynamics may be modeled very precisely, the use of complex model based control methods is often not applicable because of considerably high time delays to the distributed drives. Consequently, this contribution describes an independent joint control approach based on the method of nonlinearity estimation and compensation. In contrary to centralized control structures, industrial servo drives, powering synchronous motors, control independently their elastic joints with high sampling frequencies. Focusing not only on simulations, but also on laboratory experiments, detailed results for an industrial robot with six degrees of freedom with elastic gears are presented. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling and Parameter Identification of a Formula Student Car
Authors: Schiehlen Werner , Tobias Christoph , Wewel Marc 
Published: November 2010

AbstractA modelling approach is described using the modules vehicle body, front axle and rear axle. All these modules are virtually assembled by CAD software and Simpack, a commercial multibody dynamics tool. The geometrical data are found from the CAD model while the mechanical data for the entire vehicle are evaluated by parameter identification based on mechanical principles. In detail, the static measurement and error analysis of the center of mass is explained as well as the dynamic tests to identify the moments of inertia of the car. Further, spring and damper characteristics are identified. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Handling kinematic loops of mobile machinery in real‐time applications
Authors: Schubert Christian , Beitelschmidt Michael , Kunze Günter 
Published: November 2010

AbstractThis paper compares different mathematical approaches for handling kinematic loops in real‐time applications by looking at the linkage arrangement of a wheel loader. All constraints must be satisfied on position level and no special integration algorithm is assumed. Classical DAE formulations and an ODE formulation based on coordinate partitioning are considered and compared together with four different explicit and linear‐implicit solvers suitable for real‐time applications. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Explicit and Implicit Solver Coupling: Stability Analysis Based on an Eight‐Parameter Test Model
Authors: Busch Martin , Schweizer Bernhard 
Published: November 2010

AbstractCoupling different solvers via co‐simulation is frequently applied in the field of multi‐physical simulation. The numerical stability and accuracy of the coupled problem strongly depends on the coupling technique used for the co‐simulation. In the current work, different co‐simulation approaches are analytically investigated based on a linear eight‐parameter test model. The test model is formulated in state‐space form containing input and output variables so that the results may directly be applied to practical coupling interfaces. For the test model, recurrence formulas are derived for explicit and implicit coupling techniques of Jacobian and Gauss‐Seidel type. The numerical stability of the co‐simulation approach is examined by an eigenvalue analysis of the corresponding recurrence equation. Three‐dimensional stability plots can be analyzed for different coupling methods and for arbitrary order of the extrapolation/interpolation polynomial. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Integrability and nonintegrability in terms of transcendental functions in dynamics of a rigid body
Authors: Shamolin Maxim V. 
Published: November 2010

AbstractThe results of the presented work are due to the study of the applied problem of the rigid body motion in a resisting medium. More earlier the complete lists of transcendental first integrals expressed through a finite combination of elementary functions were obtained. This circumstance allowed the author to perform a complete analysis of all phase trajectories and highlight those properties of them which exhibit the roughness and preserve for systems of a more general form. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal control of an overhead crane within an energy‐momentum conserving method
Authors: Siebert Ralf , Betsch Peter 
Published: November 2010

AbstractThe present work deals with inverse multibody dynamics problems, more precisely with optimal control problems governed by differential‐algebraic equations. In our case, the control effort, which is necessary for moving a body from one position to another, will be minimized.Beside the commonly used generalized coordinates formulation of the equations of motion, the application of redundant coordinates will permit the derivation of conserving integrators. In addition to existing structure preserving integrators [2], the equations of motion, which serve as constraints within the optimal control scheme, may also be discretized with an energy‐momentum conserving integrator. Schemes with this property typically exhibit superior numerical stability properties.Two different possibilities exist, when applying an energy‐momentum method. The system may be reduced by applying the discrete nullspace method, which yields the elimination of the algebraic constraints [3]. This leads to a formulation with a higher degree of nonlinearity, which complicates the calculation of the gradients, that are necessary for the applied optimal control method. Alternatively, the index 3‐DAEs may be used directly. Previously, this has been done in [1] within an energy preserving direct transcription method. In that case, the simple structure of the discrete equations of motion facilitates the calculation of the gradients, which may be used for calculating the discrete necessary conditions of optimality. These equations can be solved by Newton's method.We test the different formulations with the help of an underactuated overhead crane as numerical example. This example is taken from [4], where it was used in the context of trajectory tracking. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sensitivity Analysis of Plaque Components within Arterial Wall Simulations
Authors: Brinkhues Sarah , Tielke Anna‐Katharina , Schröder Jörg 
Published: November 2010

AbstractIn this contribution we focus on a sensitivity analysis of arterial wall simulations with respect to atherosclerotic plaque components. For the simulations we use patient specific arterial wall geometries gained from medical imaging techniques. The technique used here is the Intravascular Ultra Sound Virtual Histology (IVUS‐VH). The resulting discretization is used for the simulation of a diseased artery with plaque components. The material parameters for the arterial layers are based on uniaxial tension tests, whereas the plaque parameters are chosen in a physiologically suitable range. One final goal is to study the sensitivity of the resulting deformation and stress distribution in the arterial wall with respect to the variation of the material parameters of the plaque. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling the interaction between athlete and sports surfaces
Authors: Körner Claudia , Seemann Wolfgang 
Published: November 2010

AbstractSports surfaces are often seen as one possible factor for sports injuries as the vertical ground reaction force (VGRF) depends not only on the athlete's movement but also on the mechanical properties of the ground. Therefore, the athlete‐surface‐interaction has to be analysed in order to minimize the loading on the athlete. The aim of this work is to understand the behaviour during landing and the associated impact forces during ground contact. Thus a simplified mechanical model is presented. Results for feasible surface material parameters are identified. A first assumption of the effect of the VGRF is presented. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)