bluuebunny/crossref_metadata_2025 huggingface dataset:
Features and outcomes of patients with grade IV renal injury
Authors: Shariat Shahrokh F. , Jenkins Adam , Roehrborn Claus G. , Karam Jose A. , Stage Key H. , Karakiewicz Pierre I.
Published: April 2008

OBJECTIVE

To evaluate the clinical features and outcomes of patients who presented with grade IV renal trauma to our urban level I trauma hospital and to further refine the absolute indications for exploration and determine the outcomes of conservative management.

PATIENTS AND METHODS

In all, 77 patients with grade IV traumatic renal injuries presented to our emergency department between October 1997 and October 2006. A prospective trauma database including these patients was analysed to determine the patterns of injury, operative outcomes and complications.

RESULTS

A quarter of the patients had gunshot injuries, 9% had stab injuries, and 66% had blunt traumas. In all, 36% of patients required surgical exploration to treat associated non‐urological injuries. There was no or microscopic haematuria in 29% of the patients. Of the 32 patients who underwent renal exploration, 63% (20/32) underwent renorrhaphy and 37% (12/32) underwent nephrectomy. In multivariate analyses, only gunshot injury, surgery for non‐urological injury, and volume of blood transfused were significantly associated with the need for renal exploration (P = 0.015, P = 0.041, and P = 0.032, respectively). The renal complication rate was higher in patients managed conservatively vs those who underwent surgical exploration, but this was not statistically significantly different (28% vs 13%, P = 0.2). Hospital stay was longer after renal exploration than after conservative management at a median of 12 days vs 7 days (P = 0.01).

CONCLUSIONS

While almost all patients with penetrating injury require renal exploration, only 20% of those with blunt trauma do. Patients with no renal injuries and/or haemodynamic instability are more likely to require exploration. Finally, the rate of complications was not statistically different according to management type (conservative vs renal exploration).
The effect of local calamities on educational achievement
Authors: Webbink Dinand
Published: April 2008

This study investigates the impact of two local calamities—an explosion at a firework factory in the city of Enschede on 13 May and afire at a discotheque on 1 January 2001 during a New Years Eve party in the town of Volendam—on the educational achievement of children at the end of their primary education. Based on a quasi‐experimental design with both control groups and pre‐tests, we found that in the three years following the two tragedies, the test scores of girls in those areas closest to the events were on average 0.2 standard deviations lower. This corresponds to a downward shift in the distribution of girls' test scores. Boys' test scores, meanwhile, were not significantly affected by the disasters, and nor were the scores of pupils from nearby areas. In the three years following the calamities, girls' test scores in one of the areas (Volendam) have slowly recovered, although they remain well below their pre‐event level.
Social vulnerability and the natural and built environment: a model of flood casualties in Texas
Authors: Zahran Sammy , Brody Samuel D. , Peacock Walter Gillis , Vedlitz Arnold , Grover Himanshu
Published: April 2008

Studies on the impacts of hurricanes, tropical storms, and tornados indicate that poor communities of colour suffer disproportionately in human death and injury.2 Few quantitative studies have been conducted on the degree to which flood events affect socially vulnerable populations. We address this research void by analysing 832 countywide flood events in Texas from 1997–2001. Specifically, we examine whether geographic localities characterised by high percentages of socially vulnerable populations experience significantly more casualties due to flood events, adjusting for characteristics of the natural and built environment. Zero‐inflated negative binomial regression models indicate that the odds of a flood casualty increase with the level of precipitation on the day of a flood event, flood duration, property damage caused by the flood, population density, and the presence of socially vulnerable populations. Odds decrease with the number of dams, the level of precipitation on the day before a recorded flood event, and the extent to which localities have enacted flood mitigation strategies. The study concludes with comments on hazard‐resilient communities and protection of casualty‐prone populations.
Surface Reconstruction From Non‐parallel Curve Networks
Authors: Liu L. , Bajaj C. , Deasy J. O. , Low D. A. , Ju T.
Published: April 2008

Building surfaces from cross‐section curves has wide applications including bio‐medical modeling. Previous work in this area has mostly focused on connecting simple closed curves on parallel cross‐sections. Here we consider the more general problem where input data may lie on non‐parallel cross‐sections and consist of curve networks that represent the segmentation of the underlying object by different material or tissue types (e.g., skin, muscle, bone, etc.) on each cross‐section. The desired output is a surface network that models both the exterior surface and the internal partitioning of the object. We introduce an algorithm that is capable of handling curve networks of arbitrary shape and topology on cross‐section planes with arbitrary orientations. Our algorithm is simple to implement and is guaranteed to produce a closed surface network that interpolates the curve network on each cross‐section. Our method is demonstrated on both synthetic and bio‐medical examples.
Apparent Greyscale: A Simple and Fast Conversion to Perceptually Accurate Images and Video
Authors: Smith Kaleigh , Landes Pierre‐Edouard , Thollot Joëlle , Myszkowski Karol
Published: April 2008

This paper presents a quick and simple method for converting complex images and video to perceptually accurate greyscale versions. We use a two‐step approach first to globally assign grey values and determine colour ordering, then second, to locally enhance the greyscale to reproduce the original contrast. Our global mapping is image independent and incorporates the Helmholtz‐Kohlrausch colour appearance effect for predicting differences between isoluminant colours. Our multiscale local contrast enhancement reintroduces lost discontinuities only in regions that insufficiently represent original chromatic contrast. All operations are restricted so that they preserve the overall image appearance, lightness range and differences, colour ordering, and spatial details, resulting in perceptually accurate achromatic reproductions of the colour original.
Lighting and Occlusion in a Wave‐Based Framework
Authors: Ziegler Remo , Croci Simone , Gross Markus
Published: April 2008

We present novel methods to enhance Computer Generated Holography (CGH) by introducing a complex‐valued wave‐based occlusion handling method. This offers a very intuitive and efficient interface to introduce optical elements featuring physically‐based light interaction exhibiting depth‐of‐field, diffraction, and glare effects. Fur‐thermore, an efficient and flexible evaluation of lit objects on a full‐parallax hologram leads to more convincing images. Previous illumination methods for CGH are not able to change the illumination settings of rendered holo‐grams. In this paper we propose a novel method for real‐time lighting of rendered holograms in order to change the appearance of a previously captured holographic scene. These functionalities are features of a bigger wave‐based rendering framework which can be combined with 2D framebuffer graphics. We present an algorithm which uses graphics hardware to accelerate the rendering.
GPU Accelerated Direct Volume Rendering on an Interactive Light Field Display
Authors: Agus Marco , Gobbetti Enrico , Guitiàn José Antonio Iglesias , Marton Fabio , Pintore Giovanni
Published: April 2008

We present a GPU accelerated volume ray casting system interactively driving a multi‐user light field display. The display, driven by a single programmable GPU, is based on a specially arranged array of projectors and a holographic screen and provides full horizontal parallax. The characteristics of the display are exploited to develop a specialized volume rendering technique able to provide multiple freely moving naked‐eye viewers the illusion of seeing and manipulating virtual volumetric objects floating in the display workspace. In our approach, a GPU ray‐caster follows rays generated by a multiple‐center‐of‐projection technique while sampling pre‐filtered versions of the dataset at resolutions that match the varying spatial accuracy of the display. The method achieves interactive performance and provides rapid visual understanding of complex volumetric data sets even when using depth oblivious compositing techniques.
Fast Force Field Approximation and its Application to Skeletonization of Discrete 3D Objects
Authors: Brunner D. , Brunnett G.
Published: April 2008

In this paper we present a novel method to approximate the force field of a discrete 3d object with a time complexity that is linear in the number of voxels. We define a rule, similar to the distance transform, to propagate forces associated with boundary points into the interior of the object. The result of this propagation depends on the order in which the points of the object are processed. Therefore we analyze how to obtain an order‐invariant approximation formula. With the resulting formula it becomes possible to approximate the force field and to use its features for a fast and topology preserving skeletonization. We use a thinning strategy on the body‐centered cubic lattice to compute the skeleton and ensure that critical points of the force field are not removed. This leads to improved skeletons with respect to the properties of centeredness and rotational invariance.
Stereo Light Probe
Authors: Corsini Massimiliano , Callieri Marco , Cignoni Paolo
Published: April 2008

In this paper we present a practical, simple and robust method to acquire the spatially‐varying illumination of a real‐world scene. The basic idea of the proposed method is to acquire the radiance distribution of the scene using high‐dynamic range images of two reflective balls. The use of two light probes instead of a single one allows to estimate, not only the direction and intensity of the light sources, but also the actual position in space of the light sources. To robustly achieve this goal we first rectify the two input spherical images, then, using a region‐based stereo matching algorithm, we establish correspondences and compute the position of each light. The radiance distribution so obtained can be used for augmented reality applications, photo‐realistic rendering and accurate reflectance properties estimation. The accuracy and the effectiveness of the method have been tested by measuring the computed light position and rendering synthetic version of a real object in the same scene. The comparison with standard method that uses a simple spherical lighting environment is also shown.
Sketching and Composing Widgets for 3D Manipulation
Authors: Schmidt Ryan , Singh Karan , Balakrishnan Ravin
Published: April 2008

We present an interface for 3D object manipulation in which standard transformation tools are replaced with transient 3D widgets invoked by sketching context‐dependent strokes. The widgets are automatically aligned to axes and planes determined by the user's stroke. Sketched pivot‐points further expand the interaction vocabulary. Using gestural commands, these basic elements can be assembled into dynamic, user‐constructed 3D transformation systems. We supplement precise widget interaction with techniques for coarse object positioning and snapping. Our approach, which is implemented within a broader sketch‐based modeling system, also integrates an underlying “widget history” to enable the fluid transfer of widgets between objects. An evaluation indicates that users familiar with 3D manipulation concepts can be taught how to efficiently use our system in under an hour.
Sketch‐Based Procedural Surface Modeling and Compositing Using Surface Trees
Authors: Schmidt Ryan , Singh Karan
Published: April 2008

We present a system for creating and manipulating layered procedural surface editing operations, which is motivated by the limited support for iterative design in free‐form modeling. A combination of sketch‐based and traditional modeling tools are used to design soft displacements, sharp creases, extrusions along 3D paths, and topological holes and handles. Using local parameterizations, these edits are combined in a dynamic hierarchy, enabling procedural operations like linked copy‐and‐paste and drag‐and‐drop layer‐based editing. Such dynamic, layered “surface compositing” is formalized as a Surface Tree, an analog of CSG trees which generalizes previous hierarchical surface modeling techniques. By “anchoring” tree nodes in the parameter space of lower layers, our surface tree implementation can better preserve the semantics of an edit as the underlying surface changes. Details of our implementation are described, including an efficient procedural mesh data structure.
Hardware‐Accelerated, High‐Quality Rendering Based on Trivariate Splines Approximating Volume Data
Authors: Kalbe Thomas , Zeilfelder Frank
Published: April 2008

We develop an approach for hardware‐accelerated, high‐quality rendering of volume data using trivariate splines. The proposed quasi‐interpolating schemes are realtime reconstructions. The low total degrees provide several advantages for our GPU implementation. In particular, intersecting rays with spline isosurfaces for direct Phong illumination is performed by simple root finding algorithms (analytic and iterative), while the necessary normals result from blossoming. Since visualizations are on a fragment base, our renderer for isosurfaces includes an automatic level of detail. While we use well‐known spatial data structures in the CPU part of the algorithm for hierarchical view frustum culling and memory reduction, our GPU implementations have to take the highly complex structure of the splines into account. These include an appropriate organization of the data streams, i.e. we develop an advanced encoding scheme for the spline coefficients, as well as an implicit scheme for bounding geometry retrieval. In addition, we propose an elaborated clipping procedure to be performed in the fragment shader. These features essentially reduce bus traffic, memory consumption, and data access on the GPU leading to interactive frame rates for renderings of high visual quality. Compared with pure CPU implementations and existing GPU implementations for trivariate polynomials frame rates increase by factors between 10 and 100.
GPU‐based Fast Ray Casting for a Large Number of Metaballs
Authors: Kanamori Yoshihiro , Szego Zoltan , Nishita Tomoyuki
Published: April 2008

Metaballs are implicit surfaces widely used to model curved objects, represented by the isosurface of a density field defined by a set of points. Recently, the results of particle‐based simulations have been often visualized using a large number of metaballs, however, such visualizations have high rendering costs. In this paper we propose a fast technique for rendering metaballs on the GPU. Instead of using polygonization, the isosurface is directly evaluated in a per‐pixel manner. For such evaluation, all metaballs contributing to the isosurface need to be extracted along each viewing ray, on the limited memory of GPUs. We handle this by keeping a list of metaballs contributing to the isosurface and efficiently update it. Our method neither requires expensive precomputation nor acceleration data structures often used in existing ray tracing techniques. With several optimizations, we can display a large number of moving metaballs quickly.
Ray Casting Algebraic Surfaces using the Frustum Form
Authors: Reimers Martin , Seland Johan
Published: April 2008

We propose an algorithm for interactive ray‐casting of algebraic surfaces of high degree. A key point of our approach is a polynomial form adapted to the view frustum. This so called frustum form yields simple expressions for the Bernstein form of the ray equations, which can be computed efficiently using matrix products and pre‐computed quantities. Numerical root‐finding is performed using B‐spline and Bézier techniques, and we compare the performances of recent and classical algorithms. Furthermore, we propose a simple and fairly efficient anti‐aliasing scheme, based on a combination of screen space and object space techniques. We show how our algorithms can be implemented on streaming architectures with single precision, and demonstrate interactive frame‐rates for degrees up to 16.
Expressive Facial Gestures From Motion Capture Data
Authors: Ju Eunjung , Lee Jehee
Published: April 2008

Human facial gestures often exhibit such natural stochastic variations as how often the eyes blink, how often the eyebrows and the nose twitch, and how the head moves while speaking. The stochastic movements of facial features are key ingredients for generating convincing facial expressions. Although such small variations have been simulated using noise functions in many graphics applications, modulating noise functions to match natural variations induced from the affective states and the personality of characters is difficult and not intuitive. We present a technique for generating subtle expressive facial gestures (facial expressions and head motion) semi‐automatically from motion capture data. Our approach is based on Markov random fields that are simulated in two levels. In the lower level, the coordinated movements of facial features are captured, parameterized, and transferred to synthetic faces using basis shapes. The upper level represents independent stochastic behavior of facial features. The experimental results show that our system generates expressive facial gestures synchronized with input speech.
Manifold‐valued Thin‐Plate Splines with Applications in Computer Graphics
Authors: Steinke Florian , Hein Matthias , Peters Jan , Schölkopf Bernhard
Published: April 2008

We present a generalization of thin‐plate splines for interpolation and approximation of manifold‐valued data, and demonstrate its usefulness in computer graphics with several applications from different fields. The cornerstone of our theoretical framework is an energy functional for mappings between two Riemannian manifolds which is independent of parametrization and respects the geometry of both manifolds. If the manifolds are Euclidean, the energy functional reduces to the classical thin‐plate spline energy. We show how the resulting optimization problems can be solved efficiently in many cases. Our example applications range from orientation interpolation and motion planning in animation over geometric modelling tasks to color interpolation.
A Semi‐Lagrangian CIP Fluid Solver without Dimensional Splitting
Authors: Kim Doyub , Song Oh‐young , Ko Hyeong‐Seok
Published: April 2008

In this paper, we propose a new constrained interpolation profile (CIP) method that is stable and accurate but requires less amount of computation compared to existing CIP‐based solvers. CIP is a high‐order fluid advection solver that can reproduce rich details of fluids. It has third‐order accuracy but its computation is performed over a compact stencil. These advantageous features of CIP are, however, diluted by the following two shortcomings: (1) CIP contains a defect in the utilization of the grid data, which makes the method suitable only for simulations with a tight CFL restriction; and (2) CIP does not guarantee unconditional stability. There have been several attempts to fix these problems in CIP, but they have been only partially successful. The solutions that fixed both problems ended up introducing other undesirable features, namely increased computation time and/or reduced accuracy. This paper proposes a novel modification of the original CIP method that fixes all of the above problems without increasing the computational load or reducing the accuracy. Both quantitative and visual experiments were performed to test the performance of the new CIP in comparison to existing fluid solvers. The results show that the proposed method brings significant improvements in both accuracy and speed.
Fluid in Video: Augmenting Real Video with Simulated Fluids
Authors: Kwatra Vivek , Mordohai Philippos , Narain Rahul , Penta Sashi Kumar , Carlsonk Mark , Pollefeys Marc , Lin Ming C.
Published: April 2008

We present a technique for coupling simulated fluid phenomena that interact with real dynamic scenes captured as a binocular video sequence. We first process the binocular video sequence to obtain a complete 3D reconstruction of the scene, including velocity information. We use stereo for the visible parts of 3D geometry and surface completion to fill the missing regions. We then perform fluid simulation within a 3D domain that contains the object, enabling one‐way coupling from the video to the fluid. In order to maintain temporal consistency of the reconstructed scene and the animated fluid across frames, we develop a geometry tracking algorithm that combines optic flow and depth information with a novel technique for “velocity completion”. The velocity completion technique uses local rigidity constraints to hypothesize a motion field for the entire 3D shape, which is then used to propagate and filter the reconstructed shape over time. This approach not only generates smoothly varying geometry across time, but also simultaneously provides the necessary boundary conditions for one‐way coupling between the dynamic geometry and the simulated fluid. Finally, we employ a GPU based scheme for rendering the synthetic fluid in the real video, taking refraction and scene texture into account.
Single‐pass Scalable Subsurface Rendering with Lightcuts
Authors: Arbree Adam , Walter Bruce , Bala Kavita
Published: April 2008

This paper presents a new, scalable, single pass algorithm for computing subsurface scattering using the diffusion approximation. Instead of pre‐computing a globally conservative estimate of the surface irradiance like previous two pass methods, the algorithm simultaneously refines hierarchical and adaptive estimates of both the surface irradiance and the subsurface transport. By using an adaptive, top‐down refinement method, the algorithm directs computational effort only to simulating those eye‐surface‐light paths that make significant contributions to the final image. Because the algorithm is driven by image importance, it scales more efficiently than previous methods that have a linear dependence on translucent surface area. We demonstrate that in scenes with many translucent objects and in complex lighting environments, our new algorithm has a significant performance advantage.
Photo‐realistic Rendering of Metallic Car Paint from Image‐Based Measurements
Authors: Rump Martin , Müller Gero , Sarlette Ralf , Koch Dirk , Klein Reinhard
Published: April 2008

State‐of‐the‐art car paint shows not only interesting and subtle angular dependency but also significant spatial variation. Especially in sunlight these variations remain visible even for distances up to a few meters and give the coating a strong impression of depth which cannot be reproduced by a single BRDF model and the kind of procedural noise textures typically used. Instead of explicitly modeling the responsible effect particles we propose to use image‐based reflectance measurements of real paint samples and represent their spatial varying part by Bidirectional Texture Functions (BTF). We use classical BRDF models like Cook‐Torrance to represent the reflection behavior of the base paint and the highly specular finish and demonstrate how the parameters of these models can be derived from the BTF measurements. For rendering, the image‐based spatially varying part is compressed and efficiently synthesized. This paper introduces the first hybrid analytical and image‐based representation for car paint and enables the photo‐realistic rendering of all significant effects of highly complex coatings.
Efficient and Dynamic Simplification of Line Drawings
Authors: Shesh Amit , Chen Baoquan
Published: April 2008

In this paper we present a pipeline for rendering dynamic 2D/3D line drawings efficiently. Our main goal is to create efficient static renditions and coherent animations of line drawings in a setting where lines can be added, deleted and arbitrarily transformed on‐the‐fly. Such a dynamic setting enables us to handle interactively sketched 2D line data, as well as arbitrarily transformed 3D line data in a unified manner. We evaluate the proximity of screen projected strokes to simplify them while preserving their continuity. We achieve this by using a special data structure that facilitates efficient proximity calculations in a dynamic setting. This on‐the‐fly proximity evaluation also facilitates generation of appropriate visibility cues to mitigate depth ambiguities and visual clutter for 3D line data. As we perform all these operations using only line data, we can create line drawings from 3D models without any surface information. We demonstrate the effectiveness and applicability of our approach by showing several examples with initial line representations obtained from a variety of sources: 2D and 3D hand‐drawn sketches and 3D salient geometry lines obtained from 3D surface representations.
The Beam Radiance Estimate for Volumetric Photon Mapping
Authors: Jarosz Wojciech , Zwicker Matthias , Jensen Henrik Wann
Published: April 2008

We present a new method for efficiently simulating the scattering of light within participating media. Using a theoretical reformulation of volumetric photon mapping, we develop a novel photon gathering technique for participating media. Traditional volumetric photon mapping samples the in‐scattered radiance at numerous points along the length of a single ray by performing costly range queries within the photon map. Our technique replaces these multiple point‐queries with a single beam‐query, which explicitly gathers all photons along the length of an entire ray. These photons are used to estimate the accumulated in‐scattered radiance arriving from a particular direction and need to be gathered only once per ray. Our method handles both fixed and adaptive kernels, is faster than regular volumetric photon mapping, and produces images with less noise.
The Shadow Meets the Mask: Pyramid‐Based Shadow Removal
Authors: Shor Yael , Lischinski Dani
Published: April 2008

In this paper we propose a novel method for detecting and removing shadows from a single image thereby obtaining a high‐quality shadow‐free image. With minimal user assistance, we first identify shadowed and lit areas on the same surface in the scene using an illumination‐invariant distance measure. These areas are used to estimate the parameters of an affine shadow formation model. A novel pyramid‐based restoration process is then applied to produce a shadow‐free image, while avoiding loss of texture contrast and introduction of noise. Unlike previous approaches, we account for varying shadow intensity inside the shadowed region by processing it from the interior towards the boundaries. Finally, to ensure a seamless transition between the original and the recovered regions we apply image inpainting along a thin border. We demonstrate that our approach produces results that are in most cases superior in quality to those of previous shadow removal methods. We also show that it is possible to easily composite the extracted shadow onto a new background or modify its size and direction in the original image.
Image‐based Shaving
Authors: Nguyen Minh Hoai , Lalonde Jean‐Francois , Efros Alexei A. , De la Torre Fernando
Published: April 2008

Many categories of objects, such as human faces, can be naturally viewed as a composition of several different layers. For example, a bearded face with glasses can be decomposed into three layers: a layer for glasses, a layer for the beard and a layer for other permanent facial features. While modeling such a face with a linear subspace model could be very difficult, layer separation allows for easy modeling and modification of some certain structures while leaving others unchanged. In this paper, we present a method for automatic layer extraction and its applications to face synthesis and editing. Layers are automatically extracted by utilizing the differences between subspaces and modeled separately. We show that our method can be used for tasks such beard removal (virtual shaving), beard synthesis, and beard transfer, among others.
Sparse points matching by combining 3D mesh saliency with statistical descriptors
Authors: Castellani U. , Cristani M. , Fantoni S. , Murino V.
Published: April 2008

This paper proposes new methodology for the detection and matching of salient points over several views of an object. The process is composed by three main phases. In the first step, detection is carried out by adopting a new perceptually‐inspired 3D saliency measure. Such measure allows the detection of few sparse salient points that characterize distinctive portions of the surface. In the second step, a statistical learning approach is considered to describe salient points across different views. Each salient point is modelled by a Hidden Markov Model (HMM), which is trained in an unsupervised way by using contextual 3D neighborhood information, thus providing a robust and invariant point signature. Finally, in the third step, matching among points of different views is performed by evaluating a pairwise similarity measure among HMMs. An extensive and comparative experimental session has been carried out, considering real objects acquired by a 3D scanner from different points of view, where objects come from standard 3D databases. Results are promising, as the detection of salient points is reliable, and the matching is robust and accurate.
Accurate Shadows by Depth Complexity Sampling
Authors: Forest Vincent , Barthe Loïc , Paulin Mathias
Published: April 2008

The accurate generation of soft shadows is a particularly computationally intensive task. In order to reduce rendering time, most real‐time and offline applications decorrelate the generation of shadows from the computation of lighting. In addition to such approximations, they generate shadows using some restrictive assumptions only correct in very specific cases, leading to penumbra over‐estimation or light‐leaking artifacts. In this paper we present an algorithm that produces soft shadows without exhibiting the previous drawbacks. Using a new efficient evaluation of the number of occluders between two points (i.e. the depth complexity) we either modulate direct lighting or numerically solve the rendering equation for direct illumination. Our approach approximates shadows cast by semi‐opaque occluders and naturally handles area lights with spatially varying luminance. Furthermore, depending on the desired performance and quality, the resulting shadows are either very close to, or as accurate as, a ray‐traced reference. As a result, the presented method is well suited to many domains, ranging from quality‐sensitive to performance‐critical applications.
Deep Opacity Maps
Authors: Yuksel Cem , Keyser John
Published: April 2008

We present a new method for rapidly computing shadows from semi‐transparent objects like hair. Our deep opacity maps method extends the concept of opacity shadow maps by using a depth map to obtain a per pixel distribution of opacity layers. This approach eliminates the layering artifacts of opacity shadow maps and requires far fewer layers to achieve high quality shadow computation. Furthermore, it is faster than the density clustering technique, and produces less noise with comparable shadow quality. We provide qualitative comparisons to these previous methods and give performance results. Our algorithm is easy to implement, faster, and more memory efficient, enabling us to generate high quality hair shadows in real‐time using graphics hardware on a standard PC.
Practical Product Importance Sampling for Direct Illumination
Authors: Clarberg Petrik , Akenine‐Möllery Tomas
Published: April 2008

We present a practical algorithm for sampling the product of environment map lighting and surface reflectance. Our method builds on wavelet‐based importance sampling, but has a number of important advantages over previous methods. Most importantly, we avoid using precomputed reflectance functions by sampling the BRDF on‐the‐fly. Hence, all types of materials can be handled, including anisotropic and spatially varying BRDFs, as well as procedural shaders. This also opens up for using very high resolution, uncompressed, environment maps. Our results show that this gives a significant reduction of variance compared to using lower resolution approximations. In addition, we study the wavelet product, and present a faster algorithm geared for sampling purposes. For our application, the computations are reduced to a simple quadtree‐based multiplication. We build the BRDF approximation and evaluate the product in a single tree traversal, which makes the algorithm both faster and more flexible than previous methods.
Agile Spectrum Imaging: Programmable Wavelength Modulation for Cameras and Projectors
Authors: Mohan Ankit , Raskar Ramesh , Tumblin Jack
Published: April 2008

We advocate the use of quickly‐adjustable, computer‐controlled color spectra in photography, lighting and displays. We present an optical relay system that allows mechanical or electronic color spectrum control and use it to modify a conventional camera and projector. We use a diffraction grating to disperse the rays into different colors, and introduce a mask (or LCD/DMD) in the optical path to modulate the spectrum. We analyze the trade‐offs and limitations of this design, and demonstrate its use in a camera, projector and light source. We propose applications such as adaptive color primaries, metamer detection, scene contrast enhancement, photographing fluorescent objects, and high dynamic range photography using spectrum modulation.
Mobile Democracy: Mobile Phones as Democratic Tools
Authors: Hermanns Heike
Published: April 2008

The growing influence of new information and communication technologies (ICTs), in particular mobile phone technology, on many aspects of life has been noted, but detailed analysis of possible effects on politics has begun only recently. While the possibilities of e-voting are still being explored, the political influence of mobile phones can be noticed in the wider context of democracy, namely the building of networks, the provision of information and the mobilisation of activists. This article explores the evidence of mobile phone technology's effects on democracy and argues for its incorporation in future analyses of new ICTs and democracy and political participation.
The Scope and Robustness of Modern Republicanism: A Reply to Langlois
Authors: Maynor John W.
Published: April 2008

Anthony Langlois has recently charged that a central claim of my book Republicanism in the Modern World about modern republicanism's distinctiveness when compared to the liberalisms of John Rawls and Will Kymlicka cannot be extended to all varieties of liberalism. In particular, he suggests that modern republicanism may be best thought of as a form of perfectionist liberalism. I disagree with this characterisation for two main reasons. The first concerns the difference between the scope and robustness of republican and liberal conceptions of liberty. The second focuses on the difference in the intensity and the object of the virtues and values that accompany republican liberty as non-domination.
The Accuracy of the ‘Ethnic Conflict’ Paradigm: A Reply to Aaron Edwards
Authors: Swan Sean
Published: April 2008

Aaron Edwards questions the ‘ethnic conflict’ model of Northern Irish politics using the Northern Ireland Labour party (NILP) and Progressive Unionist party (PUP) to demonstrate both the existence of cross-community politics in Northern Ireland, and class politics within the unionist community. However, understood in context, this history is actually in accord with what the ‘ethnic conflict’ model would predict. The key lies in the contemporary relative strength and weakness of political unionism and nationalism. The weakness of political nationalism allowed second-order politics safely to emerge within the unionist community and presented nationalists in many constituencies with the choice of voting NILP as the only alternative to the Unionist party.
The Pearson Diffusions: A Class of Statistically Tractable Diffusion Processes
Authors: FORMAN JULIE LYNG , SØRENSEN MICHAEL
Published: April 2008

Abstract. The Pearson diffusions form a flexible class of diffusions defined by having linear drift and quadratic squared diffusion coefficient. It is demonstrated that for this class explicit statistical inference is feasible. A complete model classification is presented for the ergodic Pearson diffusions. The class of stationary distributions equals the full Pearson system of distributions. Well‐known instances are the Ornstein–Uhlenbeck processes and the square root (CIR) processes. Also diffusions with heavy‐tailed and skew marginals are included. Explicit formulae for the conditional moments and the polynomial eigenfunctions are derived. Explicit optimal martingale estimating functions are found. The discussion covers GMM, quasi‐likelihood, non‐linear weighted least squares estimation and likelihood inference too. The analytical tractability is inherited by transformed Pearson diffusions, integrated Pearson diffusions, sums of Pearson diffusions and Pearson stochastic volatility models. For the non‐Markov models, explicit optimal prediction‐based estimating functions are found. The estimators are shown to be consistent and asymptotically normal.
Is Infant Initiation of Joint Attention by Pointing Affected by Type of Interaction?
Authors: Franco Fabia , Perucchini Paola , March Barbara
Published: April 2008

This article reports the results of two experiments studying the effects of type of interaction on infant production of declarative pointing. In Experiment 1, intensity of social presence was manipulated in adult–infant interaction with 12–19‐month‐olds (no social presence; adult responding only; adult also initiating joint attentional bids). Experiment 2 extended the analysis to peer interaction in 12–24‐month‐olds. Pointing was considered in the context of other gestures, vocalizations, and visual checking. The results show that pointing, but not vocalizing, virtually disappeared in the non‐social condition, whereas differential effects between the adult‐responding and initiating conditions were limited. Joint attentional bids were produced in peer interaction even in the younger age group, although overall the frequency of gestures was lower than that in adult–infant interaction. The results are discussed in the context of the relationship between communication and the infant developing social cognition.
Unique and Interactive Effects of Empathy and Social Status on Involvement in Bullying
Authors: Caravita Simona C. S. , Di Blasio Paola , Salmivalli Christina
Published: April 2008

This study investigated the relationships between affective and cognitive empathy, social preference and perceived popularity, and involvement in bullying situations by bullying others or defending the victimized children. The participants were 266 primary and 195 secondary school students. Affective and cognitive empathy, as well as the status variables, had some significant main effects on involvement in bullying. In addition, several interaction effects emerged. For instance, the positive association between affective empathy and defending behavior was stronger among boys who had a high status (i.e., were highly preferred) in the group. The results highlight the importance of studying child‐by‐environment models, which take into account both child characteristics and interpersonal variables in predicting social adjustment.
The Form and Function of Attachment Behavior in the Daily Lives of Young Adults
Authors: Campa Mary I. , Hazan Cindy , Wolfe Jared E.
Published: April 2008

Central to attachment theory is the postulation of an inborn system to regulate attachment behavior. This system has been well studied in infancy and childhood, but much less is known about its functioning at later ages. The goal of this study was to explore the form and function of attachment behavior in the daily lives of young adults. Twenty eight days of online diary data were collected from a sample of 60 undergraduates. In addition to providing descriptive data on routine attachment behavior, the study tests the theorized function of attachment behavior—that is, affect regulation. With the exception of safe haven behaviors, results indicate that age‐appropriate attachment behaviors are readily observable during this phase of development, tend to be preferentially directed toward attachment figures, and regulate affect in a theory consistent manner. Findings are discussed in terms of implications for normative developmental change and normative attachment processes.
Onychomycosis in Inflammatory Bowel Diseases
Authors: Gaburri D , Chebli JMF , Zanine A , Gamonal AC , Gaburri PD
Published: April 2008

Background  As far as we have sought for in Medline and PubMed, not one study until now has evaluated the prevalence of onychomycosis in patients with inflammatory bowel disease (IBD). As there are great evidence of immunological disturbances linked to IBD, a possible relationship of this nail infection in association with those diseases and the possible risk factors might be relevant in IBD patients.

Methods  A case‐control prospective study using combined direct smear and cultures for fungus was performed. Sociodemographics, clinical and laboratorial data were recorded at baseline and samples of suspected nails were collected from 141 IBD (61 men and 80 women) and from a group of 100 non‐IBD subjects (41 men and 59 women). Direct smear and cultures were performed on each suspected case to exclude other onychodystrophies.

Results  The incidence of onychomycosis in IBD patients was highly significant in comparison to non‐IBD patients (14.9% vs. 6%, respectively, P < 0.05). The risk factors predisposing IBD patients to onychomycosis were older age (P = 0.02) and leucopoenia in those using azathioprine therapy (P = 0.04) beyond a trend to lymphopenia (P = 0.06). The dermatophytes predominated (76.2%) over yeasts (19%) and moulds (4.8%).

Conclusion  The prevalence of onychomycosis in IBD patients was expressively high (14.9%) in comparison with non‐IBD patients. Considering the sociodemographic factors, any one but two were related to fungal onychomycosis incidence. Therefore, as far as we are concerned, IBD must be included in the high‐risk underlying conditions for onychomycosis occurrence.
Contact sensitization in patients with chronic wounds: Results of a prospective investigation
Authors: Freise J , Kohaus S , Korber A , Hillen U , Kroger K , Grabbe S , Dissemond J
Published: April 2008

Background  It is well known that patients with chronic wounds frequently acquire clinically relevant contact sensitizations to skin care products.

Objectives  The aim of our study was to find out the actual frequency of contact sensitivities in patients with chronic wounds in Germany with particular attention to components of products used in modern wound therapy.

Methods  We examined the results of a prospective clinical investigation on skin patch tests of patients with chronic wounds.

Results  Altogether, 45 patients with chronic wounds were tested. In 25 (55.5%) of the examined patients, contact sensitization to at least one substance was detected. The most frequent contact sensitizations were to PVP‐iodine (20%), balsam of Peru (15.6%) patients, fragrance mix (11.1%), colophony (8.8%) and potassium dichromate (6.7%). We also found sensitization to the wound dressings Varihesive™ (11.1%), Iruxol™ N (6.7%) and Comfeel™ (2.2%).

Conclusions  We would like to propagate that therapists who are involved in wound treatment should also pay attention on the ingredients of applied modern wound dressings.
Prograde metamorphic sequence of REE minerals in pelitic rocks of the Central Alps: implications for allanite–monazite–xenotime phase relations from 250 to 610 °C
Authors: JANOTS E. , ENGI M. , BERGER A. , ALLAZ J. , SCHWARZ J.‐O. , SPANDLER C.
Published: April 2008

The distribution of REE minerals in metasedimentary rocks was investigated to gain insight into the stability of allanite, monazite and xenotime in metapelites. Samples were collected in the central Swiss Alps, along a well‐established metamorphic field gradient that record conditions from very low grade metamorphism (250 °C) to the lower amphibolite facies (∼600 °C). In the Alpine metapelites investigated, mass balance calculations show that LREE are mainly transferred between monazite and allanite during the course of prograde metamorphism. At very low grade metamorphism, detrital monazite grains (mostly Variscan in age) have two distinct populations in terms of LREE and MREE compositions. Newly formed monazite crystallized during low‐grade metamorphism (<440 °C); these are enriched in La, but depleted in Th and Y, compared with inherited grains. Upon the appearance of chloritoid (∼440–450 °C, thermometry based on chlorite–choritoid and carbonaceous material), monazite is consumed, and MREE and LREE are taken up preferentially in two distinct zones of allanite distinguishable by EMPA and X‐ray mapping. Prior to garnet growth, allanite acquires two growth zones of clinozoisite: a first one rich in HREE + Y and a second one containing low REE contents. Following garnet growth, close to the chloritoid–out zone boundary (∼556–580 °C, based on phase equilibrium calculations), allanite and its rims are partially to totally replaced by monazite and xenotime, both associated with plagioclase (± biotite ± staurolite ± kyanite ± quartz). In these samples, epidote relics are located in the matrix or as inclusions in garnet, and these preserve their characteristic chemical and textural growth zoning, indicating that they did not experience re‐equilibration following their prograde formation. Hence, the partial breakdown of allanite to monazite offers the attractive possibility to obtain in situ ages, representing two distinct crystallization stages. In addition, the complex REE + Y and Th zoning pattern of allanite and monazite are essential monitors of crystallization conditions at relatively low metamorphic grade.
Residual effect of a 7‐amino metabolite of clonazepam on GABAA receptor function in the nucleus reticularis thalami of the rat
Authors: Munakata Mitsutoshi , Tsuchiya Shigeru
Published: April 2008

A considerable amount of 7‐aminoclonazepam (ACZP), a major metabolite of clonazepam (CZP), is present in the brain during CZP treatment, yet the pharmacological properties of ACZP remain unknown. We investigated the effects of ACZP on the GABAA receptor‐mediated currents (IGABA) in neurons from the nucleus reticularis thalami (NRT) of the rat, using a nystatin‐perforated patch technique. Neurons in which CZP (10 nM) exerted prominent augmentation (>100% augmentation) of IGABA, which comprised 32% of the neurons tested, were included for the analysis of ACZP. In these neurons, ACZP augmented IGABA, which was blocked by 10 μM flumazenil, a benzodiazepine receptor (BZR) antagonist. The half‐maximal effective concentration of ACZP was 124 nM, whereas that of CZP was 1.8 nM. The maximal enhancements induced by ACZP and CZP were 38% and 170%, respectively. In neurons from the ventrobasal complex of the thalamus, the effect of ACZP was negligible. Our results suggest that ACZP was a weak partial BZR agonist and that ACZP may competitively modify the effect of CZP, leading to clinical consequences for patients with high levels of ACZP.