bluuebunny/crossref_metadata_2025 huggingface dataset:
Postoperative adverse respiratory events in preschool patients with inhaled foreign bodies: an analysis of 505 cases
Authors: Zhang Xu , Li Wenxian , Chen Yinzi
Published: April 2011

Objectives:  To identify the risk factors associated with postoperative adverse respiratory events in preschool‐aged children with inhaled foreign bodies (FBs) undergoing rigid bronchoscopy.

Background:  Foreign bodies aspiration is the most common cause of admission in pediatric emergency in otolaryngology service. Performance of rigid bronchoscopy is the standard treatment for removal of FBs in children. In some cases, severe respiratory events (complete laryngospasm and pneumothorax) may cause anesthesia‐related morbidity and mortality. However, the association between patient‐related factors and postoperative complications in preschool‐aged children with inhaled FBs undergoing rigid bronchoscopy is unclear.

Methods:  We carried out a large prospective, single‐institution review of anesthesia for 505 American Society of Anesthesiologists I–III preschool children aged ≤7 with inhaled FBs undergoing rigid bronchoscopy. Patients with postoperative adverse respiratory events were classified into two groups: the minor events group [hemorrhage, minor desaturation, and partial laryngospasm (wheezing, stridor, and dyspnea)) and the major events group (complete laryngospasm, including major desaturation, and pneumothorax).

Results:  The incidence of postoperative adverse respiratory events was 9.5% in preschool‐aged children with inhaled FBs undergoing rigid bronchoscopy. Preoperative respiratory impairment was associated with an increased risk for the complicate (P < 0.01). Pneumothorax occurred in 4 (0.8%) patients. There was 1 (0.2%) death from severe respiratory‐related complications.

Conclusions:  Preoperative respiratory impairment may develop the patients with FBs into postoperative adverse respiratory events.
Generalized Helicoids for Modeling Hair Geometry
Authors: Piuze Emmanuel , Kry Paul G. , Siddiqi Kaleem
Published: April 2011

In computer graphics, modeling the geometry of hair and hair‐like patterns such as grass and fur remains a significant challenge. Hair strands can exist in an extensive variety of arrangements and the choice of an appropriate representation for tasks such as hair synthesis, fitting, editing, or reconstruction from samples, is non‐trivial. To support such applications we present a novel mathematical representation of hair based on a class of minimal surfaces called generalized helicoids. This representation allows us to characterize the geometry of a single hair strand, as well as of those in its vicinity, by three intuitive curvature parameters and an elevation angle. We introduce algorithms for fitting piecewise generalized helicoids to unparameterized hair strands, and for interpolating hair between these fits. We showcase several applications of this representation including the synthesis of different hair geometries, wisp generation, hair interpolation from samples and hair‐style parametrization and reconstruction from real hair data.
Combinatorial Bidirectional Path‐Tracing for Efficient Hybrid CPU/GPU Rendering
Authors: Pajot Anthony , Barthe Loïc , Paulin Mathias , Poulin Pierre
Published: April 2011

This paper presents a reformulation of bidirectional path‐tracing that adequately divides the algorithm into processes efficiently executed in parallel on both the CPU and the GPU. We thus benefit from high‐level optimization techniques such as double buffering, batch processing, and asyncronous execution, as well as from the exploitation of most of the CPU, GPU, and memory bus capabilities. Our approach, while avoiding pure GPU implementation limitations (such as limited complexity of shaders, light or camera models, and processed scene data sets), is more than ten times faster than standard bidirectional path‐tracing implementations, leading to performance suitable for production‐oriented rendering engines.
Procedural Modeling of Interconnected Structures
Authors: Krecklau Lars , Kobbelt Leif
Published: April 2011

The complexity and detail of geometric scenes that are used in today's computer animated films and interactive games have reached a level where the manual creation by traditional 3D modeling tools has become infeasible. This is why procedural modeling concepts have been developed which generate highly complex 3D models by automatically executing a set of formal construction rules. Well‐known examples are variants of L‐systems which describe the bottom‐up growth process of plants and shape grammars which define architectural buildings by decomposing blocks in a top‐down fashion. However, none of these approaches allows for the easy generation of interconnected structures such as bridges or roller coasters where a functional interaction between rigid and deformable parts of an object is needed. Our approach mainly relies on the top‐down decomposition principle of shape grammars to create an arbitrarily complex but well structured layout. During this process, potential attaching points are collected in containers which represent the set of candidates to establish interconnections. Our grammar then uses either abstract connection patterns or geometric queries to determine elements in those containers that are to be connected. The two different types of connections that our system supports are rigid object chains and deformable beams. The former type is constructed by inverse kinematics, the latter by spline interpolation. We demonstrate the descriptive power of our grammar by example models of bridges, roller coasters, and wall‐mounted catenaries.
Discovery of Intrinsic Primitives on Triangle Meshes
Authors: Solomon Justin , Ben‐Chen Mirela , Butscher Adrian , Guibas Leonidas
Published: April 2011

The discovery of meaningful parts of a shape is required for many geometry processing applications, such as parameterization, shape correspondence, and animation. It is natural to consider primitives such as spheres, cylinders and cones as the building blocks of shapes, and thus to discover parts by fitting such primitives to a given surface. This approach, however, will break down if primitive parts have undergone almost‐isometric deformations, as is the case, for example, for articulated human models. We suggest that parts can be discovered instead by finding intrinsic primitives, which we define as parts that posses an approximate intrinsic symmetry. We employ the recently‐developed method of computing discrete approximate Killing vector fields (AKVFs) to discover intrinsic primitives by investigating the relationship between the AKVFs of a composite object and the AKVFs of its parts. We show how to leverage this relationship with a standard clustering method to extract k intrinsic primitives and remaining asymmetric parts of a shape for a given k. We demonstrate the value of this approach for identifying the prominent symmetry generators of the parts of a given shape. Additionally, we show how our method can be modified slightly to segment an entire surface without marking asymmetric connecting regions and compare this approach to state‐of‐the‐art methods using the Princeton Segmentation Benchmark.
Global Structure Optimization of Quadrilateral Meshes
Authors: Bommes David , Lempfer Timm , Kobbelt Leif
Published: April 2011

We introduce a fully automatic algorithm which optimizes the high‐level structure of a given quadrilateral mesh to achieve a coarser quadrangular base complex. Such a topological optimization is highly desirable, since state‐of‐the‐art quadrangulation techniques lead to meshes which have an appropriate singularity distribution and an anisotropic element alignment, but usually they are still far away from the high‐level structure which is typical for carefully designed meshes manually created by specialists and used e.g. in animation or simulation. In this paper we show that the quality of the high‐level structure is negatively affected by helical configurations within the quadrilateral mesh. Consequently we present an algorithm which detects helices and is able to remove most of them by applying a novel grid preserving simplification operator (GP‐operator) which is guaranteed to maintain an all‐quadrilateral mesh. Additionally it preserves the given singularity distribution and in particular does not introduce new singularities. For each helix we construct a directed graph in which cycles through the start vertex encode operations to remove the corresponding helix. Therefore a simple graph search algorithm can be performed iteratively to remove as many helices as possible and thus improve the high‐level structure in a greedy fashion. We demonstrate the usefulness of our automatic structure optimization technique by showing several examples with varying complexity.
Scalable Remote Rendering with Depth and Motion‐flow Augmented Streaming
Authors: Paja̧k Dawid , Herzog Robert , Eisemann Elmar , Myszkowski Karol , Seidel Hans‐Peter
Published: April 2011

In this paper, we focus on efficient compression and streaming of frames rendered from a dynamic 3D model. Remote rendering and on‐the‐fly streaming become increasingly attractive for interactive applications. Data is kept confidential and only images are sent to the client. Even if the client's hardware resources are modest, the user can interact with state‐of‐the‐art rendering applications executed on the server. Our solution focuses on augmented video information, e.g., by depth, which is key to increase robustness with respect to data loss, image reconstruction, and is an important feature for stereo vision and other client‐side applications. Two major challenges arise in such a setup. First, the server workload has to be controlled to support many clients, second the data transfer needs to be efficient. Consequently, our contributions are twofold. First, we reduce the server‐based computations by making use of sparse sampling and temporal consistency to avoid expensive pixel evaluations. Second, our data‐transfer solution takes limited bandwidths into account, is robust to information loss, and compression and decompression are efficient enough to support real‐time interaction. Our key insight is to tailor our method explicitly for rendered 3D content and shift some computations on client GPUs, to better balance the server/client workload. Our framework is progressive, scalable, and allows us to stream augmented high‐resolution (e.g., HD‐ready) frames with small bandwidth on standard hardware.
Langevin Particle: A Self‐Adaptive Lagrangian Primitive for Flow Simulation Enhancement
Authors: Chen Fan , Zhao Ye , Yuan Zhi
Published: April 2011

We develop a new Lagrangian primitive, named Langevin particle, to incorporate turbulent flow details in fluid simulation. A group of the particles are distributed inside the simulation domain based on a turbulence energy model with turbulence viscosity. A particle in particular moves obeying the generalized Langevin equation, a well known stochastic differential equation that describes the particle's motion as a random Markov process. The resultant particle trajectory shows self‐adapted fluctuation in accordance to the turbulence energy, while following the global flow dynamics. We then feed back Langevin forces to the simulation based on the stochastic trajectory, which drive the flow with necessary turbulence. The new hybrid flow simulation method features nonrestricted particle evolution requiring minimal extra manipulation after initiation. The flow turbulence is easily controlled and the total computational overhead of enhancement is minimal based on typical fluid solvers.
Computer‐Suggested Facial Makeup
Authors: Scherbaum Kristina , Ritschel Tobias , Hullin Matthias , Thormählen Thorsten , Blanz Volker , Seidel Hans‐Peter
Published: April 2011

Finding the best makeup for a given human face is an art in its own right. Experienced makeup artists train for years to be skilled enough to propose a best‐fit makeup for an individual. In this work we propose a system that automates this task. We acquired the appearance of 56 human faces, both without and with professional makeup. To this end, we use a controlled‐light setup, which allows to capture detailed facial appearance information, such as diffuse reflectance, normals, subsurface‐scattering, specularity, or glossiness. A 3D morphable face model is used to obtain 3D positional information and to register all faces into a common parameterization. We then define makeup to be the change of facial appearance and use the acquired database to find a mapping from the space of human facial appearance to makeup. Our main application is to use this mapping to suggest the best‐fit makeup for novel faces that are not in the database. Further applications are makeup transfer, automatic rating of makeup, makeup‐training, or makeup‐exaggeration. As our makeup representation captures a change in reflectance and scattering, it allows us to synthesize faces with makeup in novel 3D views and novel lighting with high realism. The effectiveness of our approach is further validated in a user‐study.
Predicted Virtual Soft Shadow Maps with High Quality Filtering
Authors: Shen Li , Guennebaud Gaël , Yang Baoguang , Feng Jieqing
Published: April 2011

In this paper we present a novel image based algorithm to render visually plausible anti‐aliased soft shadows in a robust and efficient manner. To achieve both high visual quality and high performance, it employs an accurate shadow map filtering method which guarantees smooth penumbrae and high quality anisotropic anti‐aliasing of the sharp transitions. Unlike approaches based on pre‐filtering approximations, our approach does not suffer from light bleeding or losing contact shadows. Discretization artefacts are avoided by creating virtual shadow maps on the fly according to a novel shadow map resolution prediction model. This model takes into account the screen space frequency of the penumbrae via a perceptual metric which has been directly established from an appropriate user study. Consequently, our algorithm always generates shadow maps with minimal resolutions enabling high performance while guarantying high quality. Thanks to this perceptual model, our algorithm can sometimes be faster at rendering soft shadows than hard shadows. It can render game‐like scenes at very high frame rates, and extremely large and complex scenes such as CAD models at interactive rates. In addition, our algorithm is highly scalable, and the quality versus performance trade‐off can be easily tweaked.
Goal‐based Caustics
Authors: Papas Marios , Jarosz Wojciech , Jakob Wenzel , Rusinkiewicz Szymon , Matusik Wojciech , Weyrich Tim
Published: April 2011

We propose a novel system for designing and manufacturing surfaces that produce desired caustic images when illuminated by a light source. Our system is based on a nonnegative image decomposition using a set of possibly overlapping anisotropic Gaussian kernels. We utilize this decomposition to construct an array of continuous surface patches, each of which focuses light onto one of the Gaussian kernels, either through refraction or reflection. We show how to derive the shape of each continuous patch and arrange them by performing a discrete assignment of patches to kernels in the desired caustic. Our decomposition provides for high fidelity reconstruction of natural images using a small collection of patches. We demonstrate our approach on a wide variety of caustic images by manufacturing physical surfaces with a small number of patches.
Estimating Color and Texture Parameters for Vector Graphics
Authors: Jeschke S. , Cline D. , Wonka P.
Published: April 2011

Diffusion curves are a powerful vector graphic representation that stores an image as a set of 2D Bezier curves with colors defined on either side. These colors are diffused over the image plane, resulting in smooth color regions as well as sharp boundaries. In this paper, we introduce a new automatic diffusion curve coloring algorithm. We start by defining a geometric heuristic for the maximum density of color control points along the image curves. Following this, we present a new algorithm to set the colors of these points so that the resulting diffused image is as close as possible to a source image in a least squares sense. We compare our coloring solution to the existing one which fails for textured regions, small features, and inaccurately placed curves. The second contribution of the paper is to extend the diffusion curve representation to include texture details based on Gabor noise. Like the curves themselves, the defined texture is resolution independent, and represented compactly. We define methods to automatically make an initial guess for the noise texure, and we provide intuitive manual controls to edit the parameters of the Gabor noise. Finally, we show that the diffusion curve representation itself extends to storing any number of attributes in an image, and we demonstrate this functionality with image stippling an hatching applications.
Hatching for Motion Picture Production
Authors: Umenhoffer Tamás , Szécsi László , Szirmay‐Kalos László
Published: April 2011

This paper presents a hatching algorithm which – while also allows for an implementation in real‐time – is integrated into the production pipeline of computer generated motion picture. Motion picture production pipelines impose special functional and quality requirements. From the functional point of view, the stages of modeling, 3D rendering, and compositing form a pipeline without feed‐back, and frames are rendered independently, possibly on different computers. Thus, no temporal data can be shared between them while flicker free animation needs to be generated. Quality requirements can be grasped as that of dual consistency: the generated hatching must consistently follow object movement and deformation, and, at the same time, it should have a consistent pattern and density in image‐space to provide the hand‐crafted look. In order to meet both requirements, we apply a particle based method and develop an image‐space density control mechanism using rejection sampling and low‐discrepancy sequences. We also discuss the decomposition of rendering tasks according to the main stages of the production pipeline and demonstrate how the artist can define the illustration style in a convenient way.
Symmetry Hierarchy of Man‐Made Objects
Authors: Wang Y. , Xu K. , Li J. , Zhang H. , Shamir A. , Liu L. , Cheng Z. , Xiong Y.
Published: April 2011

We introduce symmetry hierarchy of man‐made objects, a high‐level structural representation of a 3D model providing a symmetry‐induced, hierarchical organization of the model's constituent parts. Given an input mesh, we segment it into primitive parts and build an initial graph which encodes inter‐part symmetries and connectivity relations, as well as self‐symmetries in individual parts. The symmetry hierarchy is constructed from the initial graph via recursive graph contraction which either groups parts by symmetry or assembles connected sets of parts. The order of graph contraction is dictated by a set of precedence rules designed primarily to respect the law of symmetry in perceptual grouping and the principle of compactness of representation. We show that symmetry hierarchy naturally implies a hierarchical segmentation that is more meaningful than those produced by local geometric considerations. We also develop an application of symmetry hierarchies for structural shape editing.
Wavelet Rasterization
Authors: Manson J. , Schaefer S.
Published: April 2011

We present a method for analytically calculating an anti‐aliased rasterization of arbitrary polygons or fonts bounded by Bézier curves in 2D as well as oriented triangle meshes in 3D. Our algorithm rasterizes multiple resolutions simultaneously using a hierarchical wavelet representation and is robust to degenerate inputs. We show that using the simplest wavelet, the Haar basis, is equivalent to performing a box‐filter to the rasterized image. Because we evaluate wavelet coefficients through line integrals in 2D, we are able to derive analytic solutions for polygons that have Bézier curve boundaries of any order, and we provide solutions for quadratic and cubic curves. In 3D, we compute the wavelet coefficients through analytic surface integrals over triangle meshes and show how to do so in a computationally efficient manner.
Comprehensive Facial Performance Capture
Authors: Fyffe Graham , Hawkins Tim , Watts Chris , Ma Wan‐Chun , Debevec Paul
Published: April 2011

We present a system for recording a live dynamic facial performance, capturing highly detailed geometry and spatially varying diffuse and specular reflectance information for each frame of the performance. The result is a reproduction of the performance that can be rendered from novel viewpoints and novel lighting conditions, achieving photorealistic integration into any virtual environment. Dynamic performances are captured directly, without the need for any template geometry or static geometry scans, and processing is completely automatic, requiring no human input or guidance. Our key contributions are a heuristic for estimating facial reflectance information from gradient illumination photographs, and a geometry optimization framework that maximizes a principled likelihood function combining multi‐view stereo correspondence and photometric stereo, using multi‐resolution belief propagation. The output of our system is a sequence of geometries and reflectance maps, suitable for rendering in off‐the‐shelf software. We show results from our system rendered under novel viewpoints and lighting conditions, and validate our results by demonstrating a close match to ground truth photographs.
Deformable Motion: Squeezing into Cluttered Environments
Authors: Choi Myung Geol , Kim Manmyung , Hyun Kyung Lyul , Lee Jehee
Published: April 2011

We present an interactive method that allows animated characters to navigate through cluttered environments. Our characters are equipped with a variety of motion skills to clear obstacles, narrow passages, and highly constrained environment features. Our control method incorporates a behavior model into well‐known, standard path planning algorithms. Our behavior model, called deformable motion, consists of a graph of motion capture fragments. The key idea of our approach is to add flexibility on motion fragments such that we can situate them into a cluttered environment via constraint‐based formulation. We demonstrate our deformable motion for realtime interactive navigation and global path planning in highly constrained virtual environments.
A Sparse Parametric Mixture Model for BTF Compression, Editing and Rendering
Authors: Wu Hongzhi , Dorsey Julie , Rushmeier Holly
Published: April 2011

Bidirectional texture functions (BTFs) represent the appearance of complex materials. Three major shortcomings with BTFs are the bulky storage, the difficulty in editing and the lack of efficient rendering methods. To reduce storage, many compression techniques have been applied to BTFs, but the results are difficult to edit. To facilitate editing, analytical models have been fit, but at the cost of accuracy of representation for many materials. It becomes even more challenging if efficient rendering is also needed. We introduce a high‐quality general representation that is, at once, compact, easily editable, and can be efficiently rendered. The representation is computed by adopting the stagewise Lasso algorithm to search for a sparse set of analytical functions, whose weighted sum approximates the input appearance data. We achieve compression rates comparable to a state‐of‐the‐art BTF compression method. We also demonstrate results in BTF editing and rendering.
Implicit Brushes for Stylized Line‐based Rendering
Authors: Vergne Romain , Vanderhaeghe David , Chen Jiazhou , Barla Pascal , Granier Xavier , Schlick Christophe
Published: April 2011

We introduce a new technique called Implicit Brushes to render animated 3D scenes with stylized lines in realtime with temporal coherence. An Implicit Brush is defined at a given pixel by the convolution of a brush footprint along a feature skeleton; the skeleton itself is obtained by locating surface features in the pixel neighborhood. Features are identified via image‐space fitting techniques that not only extract their location, but also their profile, which permits to distinguish between sharp and smooth features. Profile parameters are then mapped to stylistic parameters such as brush orientation, size or opacity to give rise to a wide range of line‐based styles.
Prior Knowledge for Part Correspondence
Authors: van Kaick Oliver , Tagliasacchi Andrea , Sidi Oana , Zhang Hao , Cohen‐Or Daniel , Wolf Lior , Hamarneh Ghassan
Published: April 2011

Classical approaches to shape correspondence base their computation purely on the properties, in particular geometric similarity, of the shapes in question. Their performance still falls far short of that of humans in challenging cases where corresponding shape parts may differ significantly in geometry or even topology. We stipulate that in these cases, shape correspondence by humans involves recognition of the shape parts where prior knowledge on the parts would play a more dominant role than geometric similarity. We introduce an approach to part correspondence which incorporates prior knowledge imparted by a training set of pre‐segmented, labeled models and combines the knowledge with content‐driven analysis based on geometric similarity between the matched shapes. First, the prior knowledge is learned from the training set in the form of per‐label classifiers. Next, given two query shapes to be matched, we apply the classifiers to assign a probabilistic label to each shape face. Finally, by means of a joint labeling scheme, the probabilistic labels are used synergistically with pairwise assignments derived from geometric similarity to provide the resulting part correspondence. We show that the incorporation of knowledge is especially effective in dealing with shapes exhibiting large intra‐class variations. We also show that combining knowledge and content analyses outperforms approaches guided by either attribute alone.
Walking On Broken Mesh: Defect‐Tolerant Geodesic Distances and Parameterizations
Authors: Campen Marcel , Kobbelt Leif
Published: April 2011

Efficient methods to compute intrinsic distances and geodesic paths have been presented for various types of surface representations, most importantly polygon meshes. These meshes are usually assumed to be well‐structured and manifold. In practice, however, they often contain defects like holes, gaps, degeneracies, non‐manifold configurations – or they might even be just a soup of polygons. The task of repairing these defects is computationally complex and in many cases exhibits various ambiguities demanding tedious manual efforts. We present a computational framework that enables the computation of meaningful approximate intrinsic distances and geodesic paths on raw meshes in a way which is tolerant to such defects. Holes and gaps are bridged up to a user‐specified tolerance threshold such that distances can be computed plausibly even across multiple connected components of inconsistent meshes. Further, we show ways to locally parameterize a surface based on geodesic distance fields, easily facilitating the application of textures and decals on raw meshes. We do all this without explicitly repairing the input, thereby avoiding the costly additional efforts. In order to enable broad applicability we provide details on two implementation variants, one optimized for performance, the other optimized for memory efficiency. Using the presented framework many applications can readily be extended to deal with imperfect meshes. Since we abstract from the input applicability is not even limited to meshes, other representations can be handled as well.
Information Shocks and the Dynamics of the Housing Market*
Authors: Fiva Jon H. , Kirkebøen Lars J.
Published: April 2011

In this paper, we analyze housing‐market reactions to the release of previously unpublished information on school quality. Using high‐quality housing data, which precisely bracket the timing of the information shock, we investigate housing‐price dynamics within school‐catchment areas. We find a robust short‐term housing‐market reaction to the publication of school‐quality indicators, suggesting that this information was new to the households, and that households are willing to pay for better schools. The publication effect does not seem to be permanent as prices revert to pre‐publication levels after two to three months.
Weighted Means Through the Looking Glass
Authors: Falk Ruma , Lann Avital Lavie
Published: April 2011

Each weighted mean of two values has a counterpart, equidistant from the arithmetic mean, obtained by exchanging roles between the weights or by inversing each weight. These elementary relations are apt for introductory courses.
Using Actuarial Exam Problems to Teach Probability
Authors: Faul David M.
Published: April 2011

This article describes how practice problems for the actuarial examination in probability can be used to encourage active, collaborative learning.
On application of input data partitioning to Bayesian weighted averaging of biomedical signals
Authors: Momot Alina
Published: April 2011

Averaging in the time domain may be used for noise attenuation in case of biomedical signals with a quasi‐cyclical character. Traditional arithmetic averaging technique assumes the constancy of the noise power cycle‐wise, however, most types of noise are not stationary and the variability of noise power is observed. It constitutes a motivation for using methods of weighted averaging, in particular Bayesian weighted averaging. This paper presents the computational study of Bayesian weighted averaging with traditional (sharp) and fuzzy partition of the input data in the presence of non‐stationary noise. There is presented the known empirical Bayesian weighted averaging method (EBWA), with the parameter p describing the probabilistic model, and its modification NBWA which eliminates the parameter. Both methods can be extended by partitioning of the input data. The performance of presented methods is experimentally evaluated for an analytical signal as well as a real ECG signal and compared with traditional arithmetic averaging method. However, the methods can be applied to any signal with a quasi‐cyclical character. The aim of the paper is to show the influence of the type of partition as well as the number of parts on the quality of the averaged signal.
Heterogeneity in the Speed of Adjustment toward Target Leverage*
Authors: ELSAS RALF , FLORYSIAK DAVID
Published: April 2011

Estimating the speed of adjustment toward target leverage using the standard partial adjustment model assumes that all firms within the sample adjust at the same (average) pace. Dynamic capital structure theory predicts heterogeneity in adjustment speed due to firm‐specific adjustment costs. Applying an estimator designed to be unbiased in the context of unbalanced dynamic panel data with a fractional dependent variable (DPF estimator), we conduct an extensive analysis of cross‐sectional heterogeneity in the speed of adjustment of firms. We find evidence for pronounced heterogeneity, where speed of adjustment is the highest for firms with high default risk or expected bankruptcy costs, and if opportunity costs of deviating from a target are high. Our evidence is consistent with the general relevance of the trade‐off theory.
Relationship of chromatic visual‐evoked potentials and the changes of foveal photoreceptor layer in central serous chorioretinopathy patients
Authors: Wu Fang , Yang Yabo , Li Haojun , Vernon Odom J
Published: April 2011

Citation information: Wu F, Yang Y, Li H & Odom JV. Relationship of chromatic visual‐evoked potentials and the changes of foveal photoreceptor layer in central serous chorioretinopathy patients. Ophthalmic Physiol Opt 2011, 31, 381–388. doi: 10.1111/j.1475‐1313.2011.00839.x

Purpose:  To investigate the relative involvement of chromatic and achromatic visual subsystems in central serous chorioretinopathy, and to correlate the function changes with the changes of the foveal photoreceptor layer using Fourier domain optical coherence tomography (FD‐OCT).

Methods:  Central serous chorioretinopathy patients and control subjects were tested and compared. Equiluminant Chromatic sinusoidal gratings were presented in a pattern onset‐offset mode. We measured the distance between the internal limiting membrane (ILM) and the external limiting membrane (ELM) on FD‐OCT images.

Results:  Visual evoked potential mean latency was delayed significantly in central serous chorioretinopathy patients compared to controls. The visual evoked potential delay was greater for chromatic than for achromatic stimuli. Retinal thickness from ILM to ELM was associated significantly and selectively with short‐wavelength‐sensitive (S) cone visual evoked potential latency (r = −0.40, p = 0.032).

Conclusions:  These results are consistent with data that indicate the loss of photoreceptors in central serous chorioretinopathy resulting in a reduced thickness of the outer nuclear layer. Additionally, they are consistent with data which indicate that the photoreceptor loss is relatively greater in cones. The S‐cone pathway was affected the most.
A national survey of diagnostic tests reported by UK community optometrists for the detection of chronic open angle glaucoma
Authors: Myint Joy , Edgar David F , Kotecha Aachal , Murdoch Ian E , Lawrenson John G
Published: April 2011

Citation information: Myint J, Edgar DF, Kotecha A, Murdoch IE & Lawrenson JG. A national survey of diagnostic tests reported by UK community optometrists for the detection of chronic open angle glaucoma. Ophthalmic Physiol Opt 2011, 31, 353–359. doi: 10.1111/j.1475‐1313.2011.00844.x

Purpose:  In the UK, the majority of cases of chronic open angle glaucoma are detected by community optometrists following a routine sight test. However, there is potential for variability in case finding strategies used. The aim of this study was to carry out a national web‐based survey to determine current diagnostic tests used by optometrists in glaucoma case finding.

Methods:  Optometrists on the Association of Optometrists (AOP) electronic database were invited to participate. The survey was open for 16 weeks between April and July 2008.

Results:  A total of 1875 optometrists were eligible to enter the survey, of which 1264 answered the questions relating to diagnostic equipment. Respondents were asked to indicate their usual method of examining the optic nerve head. Direct ophthalmoscopy only was used by 25% with the majority (62%) using a combination of direct and slit‐lamp binocular indirect methods. The vast majority of optometrists (78%) used non‐contact tonometry to measure intraocular pressure, with only 16% routinely using a Goldmann or Perkins applanation tonometer. The perimeter most frequently used was either one of the Henson range of instruments (39%) or the Humphrey Field Analyser (22%). A smaller number of optometrists (<5%) had access to more specialised imaging equipment, such as HRT, GDx or OCT.

Conclusions:  The results of the survey demonstrate that UK optometrists are well equipped to carry out case finding for chronic open angle glaucoma, although there is a lack of standardisation with respect to equipment used.
Accommodative amplitude required for sustained near work
Authors: Wolffsohn James S , Sheppard Amy L , Vakani Sanjay , Davies Leon N
Published: April 2011

Citation information: Wolffsohn JS, Sheppard AL, Vakani S & Davies LN. Accommodative amplitude required for sustained near work. Ophthalmic Physiol Opt 2011, 31, 480–486. doi: 10.1111/j.1475‐1313.2011.00847.x

Purpose:  Many practitioners base the prescription of near vision additions on the assertion that only one half or two‐thirds of an individual’s amplitude of accommodation is sustainable for a prolonged period. To better understand how much eye focus needs to be restored for presbyopic corrections to be adequate, this study investigated the robustness of the pre‐presbyopic human accommodative system during a sustained and intensive near vision task.

Methods:  Twenty‐one pre‐presbyopic volunteers (aged 26.1 ± 4.7 years) participated in the study. Binocular subjective amplitude of accommodation was measured before and after a prolonged reading exercise, using the RAF rule. During the 30 min reading task, the subject’s closest comfortable eye‐to‐text distance and pupil size was monitored. Accommodative accuracy to 0.2, 1.0, 2.0, 3.0 and 4.0 D stimuli was determined objectively using a validated binocular open‐view autorefractor immediately before, and after the reading task.

Results:  Amplitude of accommodation (p = 0.09) and accommodative accuracy (p > 0.05) were statistically unchanged following the intensive near task. The mean proportion of accommodation exerted throughout the near exercise was 80.6% (range 45.3 ± 3.7 to 96.6 ± 4.3%), which increased as the task progressed (F = 2.24, p = 0.02). The mean percentage of accommodation utilised increased with subject age (r = 0.517, p = 0.016).

Conclusion:  The pre‐presbyopic human accommodative system is robust to fatigue during intense and prolonged near work. A greater proportion of one’s amplitude of accommodation may be continuously exerted than previously suggested.
Immediately Loaded Maxillary and Mandibular Dental Implants with Fixed CAD/CAM Prostheses Using a Flapless Surgical Approach: A Clinical Report
Authors: Bedi Abhayjit , Michalakis Konstantinos X. , Mariani Jr. Eugene J. , Zourdos Despina Mato
Published: April 2011

Immediate implant loading is a viable treatment method for selected cases. One of the greatest advantages of this method is the virtual surgery, which precedes the actual clinical treatment and eliminates any need for last minute decisions. The actual surgery time is decreased, since all steps are predetermined. Additionally, no flaps have to be elevated, resulting in preservation of periimplant soft tissues, vascularization of the underlying bone, fewer postoperative complications, and minimal patient discomfort. This article presents a clinical approach made possible due to the evolution of modern scanning techniques and appropriate software.
An Investigation into the Role of Core Porcelain Thickness and Lamination in Determining the Flexural Strength of In‐Ceram Dental Materials
Authors: Alshehri Sharifa Abdullah
Published: April 2011

Purpose: A biaxial flexure test was conducted to evaluate the effect of reducing the thickness of In‐Ceram core material and veneering with Vitadur α dentine porcelain on its flexural strength.

Materials and Methods: Four groups of 10 discs were tested; group I discs were In‐Ceram discs with mean thickness of 1.58 ± 0.08 mm, group II discs were In‐Ceram discs with mean thickness of 1.0 ± 0.11 mm, group III discs were laminated In‐Ceram core porcelain/Vitadur α discs with a mean total thickness of 2.06 ± 0.15 mm and core porcelain thickness of 1.0 ± 0.11 mm; group IV discs were Vitadur α discs with a mean thickness of 2.08 ± 0.16 mm.

Results: Mean flexural strength values decreased between groups: 436 ± 38 MPa for group I, 352 ± 30 MPa for group II, 237 ± 24 MPa for group III, and 77 ± 14 MPa for group IV. The result of ANOVA and Tukey tests indicated that the mean flexural strength of group II was significantly less than group I, indicating that thickness of the In‐Ceram core provides critical flexural strength to the final product. The addition of ≈ 1 mm of Vitadur α veneering porcelain to In‐Ceram core significantly (p= 0.05) reduced the flexural strength as compared to the nonveneered In‐Ceram core specimens (group II). The Vitadur α specimens (group IV) were significantly weaker than all the other groups.

Conclusion: This study indicates that lamination should be avoided in areas where maximum strength is required for In‐Ceram all‐ceramic crowns and bridges.
Transmyocardial Voyage of a Temporary Epicardial Lead: An Unusual Long‐Term Complication
Authors: SHEIKH MUJEEB , BRUHL STEVEN R. , OMER SHUAB , SCHWAAN THOMAS , GRUBB BLAIR , COOPER CHRISTOPHER , KANJWAL YOUSUF
Published: April 2011

Although the majority of temporary epicardial leads used during cardiac surgery are removed in the perioperative period, occasionally, the wires are cut and allowed to retract into the subcutaneous tissue. Complications arising from such retained epicardial wires are rare. We present a case of transmyocardial migration of a retained epicardial wire through the right ventricular myocardium into the pulmonary artery in a patient who had undergone coronary artery bypass graft surgery 13 years ago. We describe the presentation and successful management of this case.(PACE 2011; 1–2)
Improved Activation Time Assignment of Unipolar Electrograms from Ischemic Canine Epicardium
Authors: CAREF EDWARD B. , NDREPEPA GJIN , TURITTO GIOIA , RESTIVO MARK , EL‐SHERIF NABIL
Published: April 2011

Aims: The present study attempts to develop an objective, statistically based set of criteria for activation time determination from unipolar electrograms (U‐EGMs) using a standard of activation related to biophysical theory.

Methods: A high‐resolution assembly of U‐EGMs obtained from the epicardial surface of the canine postinfarction heart were analyzed in order to achieve the best prediction of local versus distant activation. An activation time standard (ATS) consisted of three properties: (1) propagation of activation, evidenced by a linear temporal shift of waveforms from closely spaced U‐EGMs with little or no decay in amplitude; (2) cycle length‐dependent changes of those propagating waveforms; and (3) evidence of electrotonic deflections, seen as nonpropagating potentials having decaying amplitude with distance.

Results: A number of U‐EGM features were calculated and subjected to analysis by comparing their occurrence with the ATS. A discriminant function analysis incorporating multiple features (Voltage, −dV/dt and Ratio) of major U‐EGM deflections improved prediction of activation time of complex fractionated EMGs from ischemic canine epicardium to 90%.

Conclusion: A unique discriminant function based on sound biophysical principles markedly improved prediction of activation time of complex U‐EGMs from ischemic canine epicardium. A computerized version of the algorithm could be developed to provide more accurate activation maps for both basic and clinical use. (PACE 2011; 34:1105–1115)
Systematic Decrements in QTc between the First and Second Day of Contiguous Daily ECG Recordings under Controlled Conditions
Authors: BEASLEY, Jr. CHARLES M. , BENSON CHARLES , XIA JESSIE Q. , YOUNG S. STANLEY , HABER HARRY , MITCHELL MALCOLM I. , LOGHIN CORINA
Published: April 2011

Background: Many thorough QT (TQT) studies use a baseline day and double delta analysis to account for potential diurnal variation in QTc. However, little is known about systematic changes in the QTc across contiguous days when normal volunteers are brought into a controlled inpatient environment.

Methods: Two separate crossover TQT studies included 2 days of no treatment lead‐in days with ECG collection preceding periods of drug treatment
. In the first study, there were two pairs of such contiguous days with 10 replicate electrocardiograms (ECGs) collected at six time points, and in the second study, there were four pairs of contiguous days with nine replicate ECGs collected at five time points. These lead‐in day pairs provided the opportunity to evaluate any systematic changes across contiguous first and second days of an inpatient environment. Within‐patient consistency of change across pairs of days as well as within day, diurnal variation could also be evaluated.

Results: Modest (4.2 ms [range 1.9–6.5 ms]) but consistent decreases (significant [P < 0.05] for all 32 comparisons) were observed (probability: ≤5.4 × 10−16). Although group behavior with respect to QTc was consistent, individual subjects demonstrated substantial variability across pairs of days. Evidence of diurnal variation was weak and inconsistent. Magnitude of any diurnal variation was less than magnitude of change across days.

Conclusions: Subjects show a systematic decrease in QTc from first day to second day of inpatient status and do not demonstrate a significant diurnal pattern. The magnitude of this systematic change is sufficient to influence QTc study interpretation. (PACE 2011; 34:1116–1127)
Impact of Relaxation Training on Patient‐Perceived Measures of Anxiety, Pain, and Outcomes after Interventional Electrophysiology Procedures
Authors: HINDOYAN ANTREAS , CAO MICHAEL , CESARIO DAVID A. , SHINBANE JEROLD S. , SAXON LESLIE A.
Published: April 2011

Background: Electrophysiology procedures vary in invasiveness, duration, and anesthesia utilized. While complications are low and efficacy high, cases are elective and patient experiences related to anxiety, pain, and perceived outcomes are not well studied. We sought to determine if a 30‐minute audio compact disc (CD) that teaches relaxation techniques and wellness perception prior to an elective procedure impacts validated measures of anxiety, pain, and procedural outcomes.

Methods: Sixty‐one patients were randomly assigned to a control group (CG) (NCG= 31) or interventional group (IG) (NIG= 30). Both groups answered a baseline Hospital Anxiety and Depression Scale (HADS‐A) survey consisting only of anxiety assessment questions. The IG listened to the CD the night prior to their procedure. Heart rate and blood pressure were monitored on admission and prior to the procedure. Postprocedure, both groups completed two HADS‐A surveys as well as two Patient Experience Surveys (PES). There was no statistical difference in the demographics and the rate of procedural complications between the groups. The statistical significance of our data was determined using a Student's t‐test and χ2 test.

Results: At baseline, both groups had equal amounts of anxiety prior to their procedures (P = 0.2). The patients in the IG had lower systolic blood pressures during admission and prior the administration of analgesics in comparison to the CG. Postprocedure, results from administering the HADS‐A demonstrated that the IG had 33% lower anxiety (P = 0.02) than CG patients.

Conclusion: The implementation of basic relaxation teaching techniques prior to planned electrophysiology procedures lowers systolic blood pressure and postprocedural anxiety. (PACE 2011: 34:821–826)
Roll Stabilization with Short Wings
Authors: Segal Zelik , Segal Alexander
Published: April 2011

The paper presents the description and results of model experiments carried out, at zero forward speed, for determining the roll‐damping qualities of continuous bilge keels and of short wings, installed in a staggered row along the ship. The damping qualities of the short wings roll stabilizer (SWIRS) were investigated also at forward motion of the ship, using additional experimental data and the more exact calculation method of the SWIRS effectiveness. The presented experimental results and the performed analysis of roll stabilizers can be useful in further investigations and design of new vessels.