bluuebunny/crossref_metadata_2025_split huggingface dataset:
Free flap reconstruction in 1999 and 2009: Changing case characteristics and outcomes
Authors: Kakarala Kiran , Emerick Kevin S. , Lin Derrick T. , Rocco James W. , Deschler Daniel G. 
Published: June 2012

AbstractObjectives/Hypothesis:To compare free flap reconstructive cases from 1999 and 2009 with respect to patient characteristics, surgical characteristics, outcomes, and complications; and to discuss the evolution in free flap reconstruction at a single institution during this time period.Study Design:Retrospective cohort comparison.Methods:Free flap reconstruction cases from 1999 and 2009 were collected into two cohorts. Retrospective chart review was performed to extract patient characteristics, surgical characteristics, and outcomes. Cohorts were compared with respect to extracted data with statistical significance set at P < .05.Results:There were 39 free flap reconstructions performed in 1999 and 81 performed in 2009. Patients in the 2009 cohort had higher American Society of Anesthesiologists scores and incidence of cardiovascular disease (P = .009 and .0045, respectively). Median operative time decreased from 12 hours in 1999 to 9 hours in 2009 (P < .0001). Median length of stay decreased from 14 to 9 days (P = .0006). The rate of perioperative return to the operating room to manage complications decreased from 30% to 17% (P = .103). There were five unsalvaged flap failures in 1999 (12.8%) compared to two failures in 2009 (2.5%) (P = .036).Conclusions:Patients undergoing free flap reconstruction are increasingly older and have more medical comorbidities. Despite these challenges, increased efficiency and teamwork stemming from accumulated institutional experience have led to decreased operative times, length of stay, and complication rates and increased overall success rates.
A Record‐Breaking Year for Lasers
Authors: Hausken Tom 
Published: June 2012

AbstractThere is good news and bad news in the laser market this year. The good news is that 2011 was a record‐breaking year, reaching $ 7.7 billion. The bad news is that the market softened in late 2011, and 2012 will likely end up flat with last year. But that will be temporary.
Scanner Welding with Position Correction
Authors: Rombach Heribert 
Published: June 2012

AbstractWhenever complex parts are welded in series, laser‐welding technologies play a significant role. Although already well established in many industrial applications, additional improvements were made and new features integrated. For example, imaging technology has become an option for scanner welding equipment. It allows a visual control loop that guarantees precise welding and at the same time reduces significantly the costs of setup and equipment.
Stress intensity factors computation for bending plates with extended finite element method
Authors: Lasry Jérémie , Renard Yves , Salaün Michel 
Published: June 2012

SUMMARYThe modelization of bending plates with through‐the‐thickness cracks is investigated. We consider the Kirchhoff–Love plate model, which is valid for very thin plates. Reduced Hsieh–Clough–Tocher triangles and reduced Fraejis de Veubeke–Sanders quadrilaterals are used for the numerical discretization. We apply the eXtended Finite Element Method strategy: enrichment of the finite element space with the asymptotic bending singularities and with the discontinuity across the crack. The main point, addressed in this paper, is the numerical computation of stress intensity factors. For this, two strategies, direct estimate and J‐integral, are described and tested. Some practical rules, dealing with the choice of some numerical parameters, are underlined. Copyright © 2012 John Wiley & Sons, Ltd.
A coupled hp‐finite element scheme for the solution of two‐dimensional electrostrictive materials
Authors: Gil A.J. , Ledger P.D. 
Published: June 2012

SUMMARYAs part of the ongoing research within the field of computational analysis for the coupled electro‐magneto‐mechanical response of smart materials, the problem of linearised electrostriction is revisited and analysed for the first time using the framework of hp‐finite elements. The governing equations modelling the physics of the dielectric are suitably modified by introducing a new total Cauchy stress tensor (A. Dorfmann and R.W. Ogden. Nonlinear electroelasticity. Acta Mechanica, 174:167–183, 2005), which includes the electrostrictive effect and a staggered partitioned scheme for the numerical solution of the coupling phenomena. With the purpose of benchmarking numerical results, the problem of an infinite electrostrictive plate with a circular/elliptical dielectric insert is revisited. The presented analytical solution is based on the theoretical framework for two‐dimensional electrostriction proposed by Knops (R.J. Knops. Two‐dimensional electrostriction. Quarterly Journal of Mechanics and Applied Mathematics, 16:377–388, 1963) and uses classical techniques of complex variable analysis. Our presentation, to the best of our knowledge, provides the first correct closed form expression for the solution to the infinite electrostrictive plate with a circular/elliptical dielectric insert, correcting the errors made in previous presentations of this problem. We use this analytical solution to assess the accuracy, efficiency and robustness of the hp‐formulation in the case of nearly incompressible electrostrictive materials. Copyright © 2012 John Wiley & Sons, Ltd.
Mathematical homogenization theory for electroactive continuum
Authors: Kuznetsov Sergey , Fish Jacob 
Published: June 2012

SUMMARYTwo‐scale continuum equations are derived for heterogeneous continua with full nonlinear electromechanical coupling using nonlinear mathematical homogenization theory. The resulting coarse‐scale electromechanical continuum equations are free of coarse‐scale constitutive equations. The unit cell (or representative volume element) is subjected to the overall mechanical and electric field extracted from the solution of the coarse‐scale problem and is solved for arbitrary constitutive equations of fine‐scale constituents. The proposed method can be applied to analyze the behavior of electroactive materials with heterogeneous fine‐scale structure and can pave the way forward for designing advanced electroactive materials and devices. Copyright © 2012 John Wiley & Sons, Ltd.
Simple multidimensional integration of discontinuous functions with application to level set methods
Authors: Müller B. , Kummer F. , Oberlack M. , Wang Y. 
Published: June 2012

SUMMARYWe present a simple, tree‐based approach for the numerical integration over volumes and surfaces defined by the zero iso‐contour of a level set function. The work is motivated by a variant of the discontinuous Galerkin method that is characterized by discontinuous enrichments of the polynomial basis. Although numerical results suggest that the presently achieved accuracy is comparable with methods based on discretized delta functions and on the geometric reconstruction of the interface, the presented approach is conceptually simpler and applicable to almost arbitrary grid types, which we demonstrate by means of numerical experiments on triangular, quadrilateral, tetrahedral and hexahedral meshes. Copyright © 2012 John Wiley & Sons, Ltd.
Spline‐based meshfree method
Authors: Kim Hyun‐Jung , Youn Sung‐Kie 
Published: June 2012

SUMMARYIn the present work, the spline‐based meshfree method (SBMFM) is presented. The SBMFM uses spline basis functions for field variables and boundary representation. Because of the inherent properties of splines, that is, NURBS (nonuniform rational B‐splines), the analysis domain used in the SBMFM has its own parametric domain. Unlike the classical concepts in the Computer‐aided design (CAD) community in which the NURBS patches are used to model the body, the NURBS patch is treated as a background mesh in the present work. The real analysis domain is created by trimming operation so that the domain boundaries are described by spline curves only on a single NURBS patch. Building the geometry in this way enables a convenient boundary representation of the domains because direct manipulation of spline curves becomes possible. From a deformation point of view, the mesh distortion problem is effectively avoided even if the analysis domain undergoes a large deformation. In the SBMFM, boundary spline curves freely move with complete independence from the quadrilateral background NURBS patch. The so‐called element connectivity is unnecessary for geometry description. In this paper, geometrically nonlinear problems are considered. Implementation strategy is presented and the effectiveness of the present SBMFM is shown through various numerical examples. Copyright © 2012 John Wiley & Sons, Ltd.
High use of tramadol in Germany: an analysis of statutory health insurance data
Authors: Tholen Kathrin , Hoffmann Falk 
Published: June 2012

ABSTRACTPurposeTramadol is a weak opioid according to the World Health Organization pain ladder step II. It is one of the most prescribed analgesic substances in Germany, but tramadol and the step II opioids are very controversially discussed.We analysed patients with filled tramadol prescriptions with special emphasis on high use.MethodsWe used data from a German statutory health insurance for the year 2007. Patients older than 17 years with at least one tramadol prescription were analysed concerning demographic data, pain diagnoses, comorbidities, concomitant opioids, physician contacts and number of different prescribed substances. We fitted a logistic regression model to find relevant associations with high use (defined as >180 daily defined doses per year).ResultsFrom 22 946 insurants with filled tramadol prescriptions, 7.9% (n = 1812) are identified as high users; 90.9% of all tramadol patients and 93.1% of the high users have at least one pain diagnosis. The most frequent diagnoses are back pain (78.4% vs 77.1%) and arthritis pain (37.9% vs 41.8%). The results of the logistic regression model show associations between high use of tramadol and rising age, unspecific pain diagnoses, psychiatric co‐morbidities, additional prescribed strong opioids and a high number of physician contacts.ConclusionsDespite some limitations, this study shows the prescriptions of tramadol in Germany in an authentic way. It seems that there are some ‘challenging’ patients that present a treatment dilemma for some prescribers. This might result in a high use of tramadol. Copyright © 2012 John Wiley & Sons, Ltd.
Numerical Simulation of the Formation of Granular Shock Wave Over Cylindrical Obstacle
Authors: Huang Yrjö Jun , Jalali Payman , Hyppänen Timo 
Published: June 2012

AbstractA two dimensional (2‐D) stream of granular flow with zero initial granular temperature passing over a cylindrical obstacle is simulated by means of both molecular dynamics (MD) simulation and finite volume method (FVM). In experiments, a bow‐shaped shock wave with higher area fraction forms in front of the obstacle that was reproduced in our simulations. Due to the different circumstances to which particles are subjected, the granular flow is divided in two zones. One is undisturbed where quantities, such as space fraction (volume fraction for 3‐D and area fraction for 2‐D geometries), velocity and granular temperature are uniformly distributed and the other is called the shock wave zone. In this region, the values of the space fraction increases and the velocity of particles changes. From the MD simulation, it is found that the area fraction of the shock wave depends on surface roughness, coefficient of restitution (COR) of particles, the obstacle diameter as well as velocity of the granular stream, and a triangular region forms with almost zero velocity, and granular temperature forms in front of the cylindrical obstacle. The bigger is the size of the obstacle, the more stable this region is. In FVM simulations solid phase velocity and area fraction distributions similar to the MD simulation results are obtained for proper parameters.
Simulation of Dynamic Light Scattering Signals of Ultrafine Particles
Authors: Wang Ya jing , Shen Jin , Zheng Gang , Liu Wei , Zhu Xin jun 
Published: June 2012

AbstractIn order to conveniently obtain dynamic light scattering (DLS) signal, a simulation method of DLS signal is proposed in this paper. This method regards the light intensity fluctuation of DLS as a stationary random process. According to autocorrelation function (ACF) of DLS signal, the stationary random process of DLS can be generated by auto‐regressive (AR) model. Signal simulations of several kinds of distribution particles and comparison of simulations and experiment prove that AR model can be used for DLS signal simulation. Moreover, by analyzing effect of simulation parameters on simulation precision, we obtained the relationship between simulation parameters and simulation precision. Finally, application of simulation signal verifies the effectiveness and convenience of this simulation method.
A Multi‐Thresholding Algorithm for Sizing out of Focus Particles
Authors: Ju Dehao , Shrimpton John S. , Hearn Alex 
Published: June 2012

AbstractA methodology is presented that enables efficient acquisition of sufficient droplet information (e.g. diameter and aspect ratio) from images of in and out of focus droplets. The newly developed multi‐threshold algorithm is successfully implemented in the automatic particle/droplet image analysis (PDIA) system. Under the same optical hardware set‐up, and compared to the dual threshold methods [1], the multi‐threshold method increases the measurable/acceptable depth of field (DoF) of particles, especially for the small particles of diameters less than 50 μm (1098 pixels in this optical set‐up). When testing the 70 μm~110 μm and 100 μm~200 μm moving glass spheres, the dual threshold method can only detect 11%~29 % of the particles found by the multi‐threshold method. The multi‐threshold method is also capable of generating the aspect ratios of particles more accurately than dual threshold methods.
Physiotherapy Rehabilitation for Individuals with Lower Limb Amputation: A 15‐Year Clinical Series
Authors: Hordacre Brenton , Birks Vicki , Quinn Stephen , Barr Christopher , Patritti Benjamin L. , Crotty Maria 
Published: June 2012

AbstractBackground and PurposeIndividuals with amputations are a core group in Australian rehabilitation units that have a long index length of stay. The Repatriation General Hospital (RGH) offers general rehabilitation services to the population of Southern Adelaide (a population of 350,000) and includes an on‐site prosthetic manufacturing facility. Using a physiotherapy database at the RGH, we sought to answer the following questions: What are the demographic and clinical characteristics of patients admitted for lower limb prosthetic rehabilitation over 15 years? What are the times to rehabilitation outcomes? How have these changed over 15 years with changes in service delivery?MethodsThis paper is a retrospective observational study using a physiotherapy clinical database (1996–2010) of 531 consecutive individuals with lower limb amputation at one South Australian hospital (RGH). There were two changes in service delivery: 1) a multidisciplinary interim prosthetic programme (IPP) introduced in 1998 and 2) removable rigid dressings (RRDs) introduced in 2000. Outcome measures were patient demographics, clinical characteristics and time to rehabilitation outcome markers.ResultsMean age was 68 years (standard deviation [SD]: 15), with 69% male, 80% dysvascular and 68% transtibial. The overall median inpatient rehabilitation length of stay (RLOS) was 39 days (interquartile range [IQR]: 26–57). Individuals with amputation entering rehabilitation each year had a higher number of co‐morbidities (β: 0.08; 95% confidence interval: 0.05–0.11). Introduction of the IPP was associated with a significant reduction in time to initial prosthetic casting, independent walking and inpatient RLOS. Introduction of RRDs was associated with a significant reduction in time to wound healing, initial prosthetic casting and independent walking.ConclusionsIndividuals with amputation were typically elderly dysvascular men with transtibial amputations. Introduction of the IPP and RRDs successfully reduced time to rehabilitation outcomes including independent walking, an outcome that is rarely reported but is of significance to patients and physiotherapists. Copyright © 2012 John Wiley & Sons, Ltd.
Steady‐state non‐equilibrium transport in non‐Hermitian open quantum nanostructures
Authors: Bolech C.J. , Kakashvili P. 
Published: June 2012

AbstractWe present two classic case studies of non‐equilibrium transport from the mesoscopics literature, – a single‐channel tunneling junction and a tunneling junction with an embedded resonant level –, that we generalized to the non‐Hermitian case. We use these problems to illustrate the characteristics of the non‐linear transport due to the asymmetric dynamics inherent of the non‐Hermitian problem. We employ a generalized time‐loop Green's function formalism that was developed explicitly to define and deal with these problems, and that constitutes a powerful and general tool for this type of studies. We point out important differences with the standard Hermitian case.
Equivalence of the effective Hamiltonian approach and the Siegert boundary condition for resonant states
Authors: Hatano N. 
Published: June 2012

AbstractTwo theoretical methods of finding resonant states in open quantum systems, namely the approach of the Siegert boundary condition and the Feshbach formalism, are reviewed and shown to be algebraically equivalent to each other for a simple model of the T‐type quantum dot. It is stressed that the seemingly Hermitian Hamiltonian of an open quantum system is implicitly non‐Hermitian outside the Hilbert space. The two theoretical approaches extract an explicitly non‐Hermitian effective Hamiltonian in a contracted space out of the seemingly Hermitian (but implicitly non‐Hermitian) full Hamiltonian in the infinite‐dimensional state space of an open quantum system.
Non‐Hermitian approach for modeling of noise‐assisted quantum electron transfer in photosynthetic complexes
Authors: Nesterov A.I. , Berman G.P. , Bishop A.R. 
Published: June 2012

AbstractWe model the quantum electron transfer (ET) in the photosynthetic reaction center (RC), using a non‐Hermitian Hamiltonian approach. Our model includes (i) two protein cofactors, donor and acceptor, with discrete energy levels and (ii) a third protein pigment (sink) which has a continuous energy spectrum. Interactions are introduced between the donor and acceptor, and between the acceptor and the sink, with noise acting between the donor and acceptor. The noise is considered classically (as an external random force), and it is described by an ensemble of two‐level systems (random fluctuators). Each fluctuator has two independent parameters, an amplitude and a switching rate. We represent the noise by a set of fluctuators with fitting parameters (boundaries of switching rates), which allows us to build a desired spectral density of noise in a wide range of frequencies. We analyze the quantum dynamics and the efficiency of the ET as a function of (i) the energy gap between the donor and acceptor, (ii) the strength of the interaction with the continuum, and (iii) noise parameters. As an example, numerical results are presented for the ET through the active pathway in a quinone‐type photosystem II RC.
Non‐Markovian electron dynamics in nanostructures coupled to dissipative contacts
Authors: Novakovic B. , Knezevic I. 
Published: June 2012

AbstractIn quasiballistic semiconductor nanostructures, carrier exchange between the active region and dissipative contacts is the mechanism that governs relaxation. In this paper, we present a theoretical treatment of transient quantum transport in quasiballistic semiconductor nanostructures, which is based on the open system theory and valid on timescales much longer than the characteristic relaxation time in the contacts. The approach relies on a model interaction between the current‐limiting active region and the contacts, given in the scattering‐state basis. We derive a non‐Markovian master equation for the irreversible evolution of the active region's many‐body statistical operator by coarse‐graining the exact dynamical map over the contact relaxation time. In order to obtain the response quantities of a nanostructure under bias, such as the potential and the charge and current densities, the non‐Markovian master equation must be solved numerically together with the Schrödinger, Poisson, and continuity equations. We discuss how to numerically solve this coupled system of equations and illustrate the approach on the example of a silicon nin diode.
Current knowledge and systematic review of viruses associated with Crohn's disease
Authors: Wagner Josef , Sim Winnie H. , Lee Katherine J. , Kirkwood Carl D. 
Published: June 2012

SUMMARYThe aetiology of Crohn's disease (CD) is currently unknown. A viral trigger was proposed more than 40 years ago and has been the focus of many investigations. We summarised the current literature surrounding the association between viruses and CD and conducted a systematic review of all studies investigating this association quantitatively. Studies were identified by searching for 13 specific virus names or the general term ‘virus’ and ‘Crohn's disease’ in search engines PubMed and OVID. A total of 1315 studies were identified, of which 78 studies had a laboratory result. Of the 78, 46 case–control studies met all the inclusion criteria for forest plot analysis.The most common viruses studied were EBV, CMV and measles virus (MV). Forest plot analysis for each virus was carried out (fitted using random effects) and identified evidence of an association between CD and CMV (risk ratio [RR] 1.602, 95% confidence interval [CI] 1.069 to 2.400) with some suggestion that EBV may also be associated with CD (RR 1.366, 95% CI 0.996 to 1.873). However, there was evidence of large heterogeneity in the results from the identified studies for EBV. There was little evidence of an association with CD for MV, human herpes virus 6, human herpes virus 8, human simplex virus, varicella‐zoster virus, mumps virus, Rubella virus, rotavirus, norovirus and adenovirus. There is still some question around whether CD is associated with the presence of a currently known virus. Copyright © 2012 John Wiley & Sons, Ltd.
Counting strongly‐connected, moderately sparse directed graphs
Authors: Pittel Boris 
Published: June 2012

AbstractA sharp asymptotic formula for the number of strongly connected digraphs on n labelled vertices with m arcs, under the condition m ‐ n ≫ n2/3, m = O(n), is obtained; this provides a partial solution of a problem posed by Wright back in 1977. This formula is a counterpart of a classic asymptotic formula, due to Bender, Canfield and McKay, for the total number of connected undirected graphs on n vertices with m edges. A key ingredient of their proof was a recurrence equation for the connected graphs count due to Wright. No analogue of Wright's recurrence seems to exist for digraphs. In a previous paper with Nick Wormald we rederived the BCM formula by counting first connected graphs among the graphs of minimum degree 2, at least. In this paper, using a similar embedding for directed graphs, we find an asymptotic formula, which includes an explicit error term, for the fraction of strongly‐connected digraphs with parameters m and n among all such digraphs with positive in/out‐degrees. © 2012 Wiley Periodicals, Inc. Random Struct. Alg., 2013