bluuebunny/crossref_metadata_2025 huggingface dataset:
Treatment differences between Aboriginal and white infants admitted to Canadian neonatal intensive care units
Authors: Reime Birgit , Tu Andrew W. , Lee Shoo K. ,   the Canadian Neonatal Network
Published: October 2007

Previous studies reported differences in clinical treatments provided to ethnic minority children and white children. We examined whether there were differences in clinical treatments provided to Aboriginal and White infants in Canadian Neonatal Intensive Care Units (NICU) and whether these potential differences could be explained by differences in population characteristics, community size, maternal neighbourhood income and hospital treatment policies. The study population included 10 166 infants (n = 784 Aboriginal and n = 9382 white) admitted to 17 NICUs from all geographical regions of Canada participating in the Canadian Neonatal Network during January 1996–October 1997. We used logistic regression analyses to examine the association between ethnicity and each of seven clinical practices (surfactant treatment, antenatal steroids, blood transfusions, surgery, assisted ventilation, incubator use and transparental nutrition), after adjustment for potential confounders. We repeated theses analyses restricted to infants born <32 weeks gestation.

In crude analyses, in the full sample, Aboriginal infants were less likely than white infants to receive surfactants, antenatal steroids, surgery, assisted ventilation, incubator and transparental nutrition. Among infants born <32 weeks gestation, Aboriginal infants were less likely than white infants to receive antenatal steroids, assisted ventilation, incubator and transparental nutrition. In both groups, adjusting for illness severity, gestational age and multiple births separately (model 2) and in combination with neighbourhood income and community size (model 3) resulted in non‐significant associations between ethnicity and some of the treatments, but the addition of adjustment for the hospital variation in frequency of use of different treatments resulted in non‐significant associations between ethnicity and all seven treatments. Additional studies are needed to explore the significance of hospital frequency of treatment and its relationship to ethnicity.
An oxidative burst of superoxide in embryonic axes of recalcitrant sweet chestnut seeds as induced by excision and desiccation
Authors: Roach Thomas , Ivanova Mariyana , Beckett Richard P. , Minibayeva Farida V. , Green Ian , Pritchard Hugh W. , Kranner Ilse
Published: October 2007

Recalcitrant seeds are intolerant of desiccation and cannot be stored in conventional seed banks. Cryopreservation allows storage of the germplasm of some recalcitrant seeded species, but application to a wide range of plant diversity is still limited. The present work aimed at understanding the stresses that accompany the first steps in cryopreservation protocols, wounding and desiccation, both of which are likely to lead to the formation of reactive oxygen species (ROS). Extracellular ROS production was studied in isolated embryonic axes of sweet chestnut (Castanea sativa). Axis excision was accompanied by a burst of superoxide (O2·−), demonstrated by a colorimetric assay using epinephrine, electron spin resonance and staining with nitroblue tetrazolium. Superoxide was immediately produced on the cut surface after isolation of the axis from the seed, with an initial ‘burst’ in the first 5 min. Isolated axes subjected to variable levels of desiccation stress showed a decrease in viability and vigour and increased electrolyte leakage, indicative of impaired membrane integrity. The pattern of O2·− production showed a typical Gaussian pattern in response to increasing desiccation stress. The results indicate a complex interaction between excision and subsequent drying and are discussed with a view of manipulating ROS production for optimisation of cryopreservation protocols.
Do Blackbirds Signal Motivation to Fight with Their Song?
Authors: Ripmeester Erwin A. P. , De Vries Anne M. , Slabbekoorn Hans
Published: October 2007

Conflicts about resources can be solved with physical fights, but animals will in general try to avoid them due to the costs and risks associated with fighting. Fight outcome depends on the fighting ability as well as the motivation to fight, which means that individuals should try to assess both during a pre‐escalation phase. In the present study, we investigated whether blackbirds (Turdus merula) acoustically signal their motivation to fight with their advertisement song, which consists of a motif part with pure‐toned low frequency elements followed by a twitter part with more complex and higher‐pitched elements. We tested (1) whether the temporal and spectral characteristics of spontaneous songs broadcasted by a territorial male could predict its subsequent aggressive behaviour to a playback and (2) if the song of territorial males changed in case they responded aggressively to the playback. We found no effects in the temporal song structure, which contradicts results from a previous study involving playback experiments with blackbirds. We did however find an interesting pattern in the spectral characteristics of the twitter, since aggressively responding males significantly increased the twitter frequency after the playback. The post‐playback songs of aggressive responders were nevertheless indistinguishable from spontaneous pre‐playback songs of non‐aggressive responders. Therefore, we conclude that changes in twitter frequency, rather than absolute twitter frequencies, are advertising information about motivation to fight.
Seeing What We Want to See: Confirmation Bias in Animal Behavior Research
Authors: Marsh David M. , Hanlon Teresa J.
Published: October 2007

Confirmation bias is the tendency of observers to see what they expect to see while conducting scientific research. Although confirmation bias has been well‐studied by psychologists in the context of qualitative judgments, it has been much less studied with respect to the kinds of quantitative observations made by behavioral biologists. We carried out two experiments that used multiple observers of the aggression and foraging behaviors of red‐backed salamanders (Plethodon cinereus) to determine whether behavioral observations were influenced by the a priori expectations of observers. In both experiments, one group of observers was given a specific set of expectations with respect to sex differences in salamander behavior, while a second group was given the opposite set of expectations. In one experiment, observers collected data on variable sets of live salamanders, while in the other experiment, observers collected data from identical videotaped trials. Across experiments and observed behaviors, the expectations of observers did appear to bias observations, but only to a small or moderate degree. Confirmation bias never accounted for more than 13% of the observed variation in behavior, and was generally equivalent to <20% of the mean value of each variable. The estimated magnitude of confirmation bias was quite similar for men and women, suggesting no relationship between observer gender and susceptibility to confirmation bias. We believe that these results are largely optimistic with respect to confirmation bias in behavioral ecology, in that they suggest the bias may often be small relative to individual variation in behavior, even for relatively inexperienced observers.
Do Larval Damselflies make Adaptive Choices When Exposed to Both Parasites and Predators?
Authors: Rutherford Pamela L. , Baker Robert L. , Forbes Mark R.
Published: October 2007

The importance of multiple enemies from different trophic levels on investment in defence by prey has, with some exceptions, received little attention. Some defences may make the victim more susceptible to other enemies; this latter situation applies to predators and parasites of larval damselflies. Baker and Smith [Oecologia109 (1997) 622) showed that larval damselflies were as active in the presence of both mites and fish as they were when only mites were present, an apparently maladaptive behaviour that results in higher fish predation. In this paper, we further examine this maladaptive behavioural response to multiple enemies (fish predators and mite parasites) and test whether their defence responses are a result of the order in which they experience the parasite or predator, and/or if behavioural ‘personalities’ exist, such that some individuals show anti‐predator behaviours and other show anti‐parasite behaviours. Order of experience did not affect the four main behaviours (groom, crawl, turn and swim) exhibited when larval damselflies were simultaneously exposed to fish and mites. Grooming levels increased in response to mites, decreased in response to fish and when exposed to both mites and fish were similar to when they were exposed to mites alone. Duration of the other three behaviours was lower in the presence of both mites and fish. The crawling ‘personalities’ were evident. The apparently maladaptive response of high grooming levels in the presence of mites and fish is not a result of order of experience or ‘personalities’. It may be a result of relatively high encounter rates with mite parasites, compared with the encounter rates with fish. Lower encounter rates can result in diminishing investment in defence against an enemy.
Persistence of Alarm‐Call Behaviour in the Absence of Predators: A Comparison Between Wild and Captive‐Born Meerkats (Suricata Suricatta)
Authors: Hollén Linda I. , Manser Marta B.
Published: October 2007

Performing correct anti‐predator behaviour is crucial for prey to survive. But, are such abilities lost in species or populations living in predator‐free environments? How individuals respond to the loss of predators has been shown to depend on factors such as the degree to which anti‐predator behaviour relies on experience, the type of cues evoking the behaviour, the cost of expressing the behaviour and the number of generations under which relaxed selection has taken place. Here we investigated whether captive‐born populations of meerkats (Suricata suricatta) used the same repertoire of alarm calls previously documented in wild populations and whether captive animals, as wild ones, could recognize potential predators through olfactory cues. We found that all alarm calls that have been documented in the wild also occurred in captivity and were given in broadly similar contexts. Furthermore, without prior experience of odours from predators, captive meerkats seemed to distinguish between faeces of potential predators (carnivores) and non‐predators (herbivores). Despite slight structural differences, the alarm calls given in response to the faeces largely resembled those recorded in similar contexts in the wild. These results from captive populations suggest that direct, physical interaction with predators is not necessary for meerkats to perform correct anti‐predator behaviour in terms of alarm‐call usage and olfactory predator recognition. Such behaviour may have been retained in captivity because relatively little experience seems necessary for correct performance in the wild and/or because of the recency of relaxed selection on these populations.
Female Gryllus vocalis Field Crickets Gain Diminishing Returns from Increasing Numbers of Matings
Authors: Gershman Susan N.
Published: October 2007

Although female insects generally gain reproductive benefits from mating frequently, females do not mate unlimited numbers of times. This study asks whether the limit on female mating rate is imposed by trade‐offs between reproduction and survival. Female Gryllus vocalis were given the opportunity to mate 5, 10, or 15 times with novel males, and the effects on daily fecundity (egg production), fertility (proportion of eggs that were fertilized), and female post‐experimental longevity were measured. Females that mated 10 times laid more eggs and had a higher proportion of fertile eggs than females that mated 5 times. However, females that mated 15 times did not lay significantly more eggs or have a higher proportion of fertile eggs than females that mated 10 times. Although number of matings did not affect the date that females laid their last egg, mating more times was associated with a prolonged period of laying fertile eggs. Number of matings did not affect female post‐experimental longevity. Thus, there was no trade‐off between female reproductive effort and survival, even when females mated very large numbers of times. When females were allowed to mate ad libitum, the average number of times that females mated was greater than the number of times that confers maximal fitness. The lack of cost to mating explains why females might be willing to mate beyond the point of diminishing reproductive returns.
Do Displays Send Information about Ornament Structure and Male Quality in the Ornate Tree Lizard,Urosaurus ornatus?
Authors: McElroy Eric J. , Marien Chloe , Meyers Jay J. , Irschick Duncan J.
Published: October 2007

Displays can transmit information about ornament or male quality; however, few studies have simultaneously explored the relationship between displays, ornament and male quality within a single species. We quantified ornament morphology (five throat color morphs, throat area, and belly area), male quality (bite force, sprint speed, body condition, and body mass), display behavior [percent time displaying (PTD), number of pushups per display, and display duration], and movement behavior among males in a population of the ornate tree lizard,Urosaurus ornatus. Previous studies have shown that maleU. ornatusare polymorphic in throat coloration and that morphs differ in behavioral aggression. Our study shows that blue throat morphs use 1.5 more pushups per display than other male color morphs, which suggests that throat color and display behavior act as backup signals for aggression. However, other data support the multiple messages hypothesis, and overall our data do not provide conclusive evidence for any one hypothesis. In addition, we show that body mass is positively related to both PTD and percent time moving and this relationship is independent of color morph. We also found that throat area, belly area, bite force, sprint speed, and body condition are unrelated to display behavior. This result highlights at least some discordance between display behavior, ornaments, and performance inU. ornatusand suggests that these traits may be evolving independently.
Direct Familiarity Does Not Alter Mating Preference for Sisters in MalePelvicachromis taeniatus(Cichlidae)
Authors: Thünken Timo , Bakker Theo C. M. , Baldauf Sebastian A. , Kullmann Harald
Published: October 2007

In social species, individuals who grew up together are usually relatives. Therefore, direct familiarity is normally a reliable kin recognition mechanism that is used in many species to discriminate kin from non‐kin. It has been shown in animals and in humans that familiar individuals are rejected as mating partners in order to circumvent potential costs of inbreeding. Here, we tested whether direct familiarity also leads to inbreeding avoidance behaviour in malePelvicachromis taeniatus, a small socially monogamous cichlid with biparental brood care. In mate choice experiments, reproductively active males were given the choice between familiar sisters and unfamiliar, unrelated females. In a previous study, both sexes ofP. taeniatushad preferred unfamiliar full‐sibs over unfamiliar unrelated individuals as mating partners. Here, we show that direct familiarity does not alter the male preference for closely related females. This result is in accordance with theoretical predictions, that inbreeding can be advantageous under certain conditions, and confirms previous findings, that active inbreeding is an adaptive strategy inP. taeniatus.
Secondary structure alignment and direct optimization of 28S rDNA sequences provide limited phylogenetic resolution in bark and ambrosia beetles (Curculionidae: Scolytinae)
Authors: Jordal Bjarte , Gillespie Joseph J. , Cognato Anthony I.
Published: October 2007

Phylogenetic relationships in Scolytinae were reconstructed from 107 DNA sequences that spanned the D2 and D3 expansion segments, and related core regions of the nuclear large ribosomal subunit (28S). Sequences were analysed by parsimony and Bayesian analyses of aligned sequences aided by a new secondary structure model for the D2–D3 domains. Direct optimization was performed on ambiguous alignment regions in combination with fixed states optimization of unambiguous regions, but performed poorly compared to the Bayesian and parsimony analyses. Generally, the phylogenetic signal mainly resolved relationships within tribes, while deeper divergences were either not resolved or received marginal support. In addition to confirming several previously established clades, we found that Micracini formed the sister group to Cactopinus, a group of mainly cactus feeding scolytine beetles. Furthermore, Ipini was monophyletic with Pseudips and Acanthotomicus subtending to the most basal node of that clade. The monophyly of Corthylini, which consists of the bark and cone feeding Pityophtorina and the ambrosia fungus‐feeding Corthylina, was supported in some of the analyses. A close relationship was found between Phloeotribus and the two Phloeosinini genera Chramesus and Pseudochramesus, suggesting an evolutionary trajectory for the origin of a lamellate antennal club in Phloeotribus.
Prevalence of obesity in 6‐ and 9‐year‐old children living in Central‐North Italy. Analysis of determinants and indicators of risk of overweight
Authors: Albertini A. , Tripodi A. , Fabbri A. , Mattioli M. , Cavrini G. , Cecchetti R. , Dalle Donne E. , Cortesi C. , De Giorgi S. , Contarini V. , Andreotti L. , Veronesi B. , Stefanelli I. , Di Martino E.
Published: October 2007

The objective of our article is to survey the prevalence of overweight and obesity among 6‐ and 9‐year‐old children in Emilia‐Romagna, a region of Central‐North Italy, and to study the eating habits and behaviours of these children and their families.

During 2003 and 2005, we analysed a stratified sample of the general population of children attending pre‐school (2681 children aged 6 years) and primary school (2955 children aged 9 years). Their height and weight were measured by healthcare workers. In the 6‐year‐old children, information concerning their eating habits was collected by means of a questionnaire completed by their parents.

The prevalence of overweight was 16.5% in 6‐year‐old children and 20.6% in 9‐year‐old children. The increase of overweight from 6‐ to 9‐year‐old children was observed in males (13.5% in 6‐year‐old/21.3% in 9‐year‐old boys), but not in females. The prevalence of obesity was 8.9% in children aged 6 years and 9.0% in those aged 9 years, and it was higher in comparison with Italian surveys carried out in 1993 and in 2001: 7.5% in 6‐year‐old and 7.8% in 9‐year‐old children in 1993, and 6.6% in 6‐year‐old and 7.2% in 9‐year‐old children in 2001. In pre‐school children, overweight and obesity were closely influenced by the education level, occupation and nutritional status of the parents.
Serious Games: Broadening Games Impact Beyond Entertainment
Authors: Sawyer Ben
Published: October 2007

Computer and videogames for many years has been an island of technology and design innovation largely left to itself as it morphed from a cottage business into a global media and software industry. While there have been pockets of derivative activity related to games and game technology only in the last half‐dozen years has there been a real movement toward exploiting this industry in many new and exciting ways.

Today the general use of games and game technologies for purposes beyond entertainment is collectively referred to as serious games. The Serious Games Initiative was formed in 2002 and since its inception has been among a number of critical efforts that has helped open up the world and many disciplines to the ideas and innovations that may be sourced from the commercial, independent, and academic game fields. This has been a person‐by‐person, project‐by‐project effort that not only has informed us about the potential of games but also in how you merge innovation and innovators from one discipline with those in another.

In this talk we will explore the total gamut of the serious games field identifying past the obvious how games and game technologies are being applied to problems in a wide array of areas including healthcare, productivity, visualization, science, and of course training and education. Once a proper definition of serious games is established the talk will focus on the current state of the field as it relates to research and infrastructure issues that are needed to make the difference between seeing serious games take hold as a major new practice or having it devolve into another trend of the moment lost to history.
Soft Articulated Characters with Fast Contact Handling
Authors: Galoppo Nico , Otaduy Miguel A. , Tekin Serhat , Gross Markus , Lin Ming C.
Published: October 2007

Fast contact handling of soft articulated characters is a computationally challenging problem, in part due to complex interplay between skeletal and surface deformation. We present a fast, novel algorithm based on a layered representation for articulated bodies that enables physically‐plausible simulation of animated characters with a high‐resolution deformable skin in real time. Our algorithm gracefully captures the dynamic skeleton‐skin interplay through a novel formulation of elastic deformation in the pose space of the skinned surface. The algorithm also overcomes the computational challenges by robustly decoupling skeleton and skin computations using careful approximations of Schur complements, and efficiently performing collision queries by exploiting the layered representation. With this approach, we can simultaneously handle large contact areas, produce rich surface deformations, and capture the collision response of a character/s skeleton.
3D Lip‐Synch Generation with Data‐Faithful Machine Learning
Authors: Kim Ig‐Jae , Ko Hyeong‐Seok
Published: October 2007

This paper proposes a new technique for generating three‐dimensional speech animation. The proposed technique takes advantage of both data‐driven and machine learning approaches. It seeks to utilize the most relevant part of the captured utterances for the synthesis of input phoneme sequences. If highly relevant data are missing or lacking, then it utilizes less relevant (but more abundant) data and relies more heavily on machine learning for the lip‐synch generation. This hybrid approach produces results that are more faithful to real data than conventional machine learning approaches, while being better able to handle incompleteness or redundancy in the database than conventional data‐driven approaches. Experimental results, obtained by applying the proposed technique to the utterance of various words and phrases, show that (1) the proposed technique generates lip‐synchs of different qualities depending on the availability of the data, and (2) the new technique produces more realistic results than conventional machine learning approaches.
Adaptive Space Deformations Based on Rigid Cells
Authors: Botsch Mario , Pauly Mark , Wicke Martin , Gross Markus
Published: October 2007

We propose a new adaptive space deformation method for interactive shape modeling. A novel energy formulation based on elastically coupled volumetric cells yields intuitive detail preservation even under large deformations. By enforcing rigidity of the cells, we obtain an extremely robust numerical solver for the resulting nonlinear optimization problem. Scalability is achieved using an adaptive spatial discretization that is decoupled from the resolution of the embedded object. Our approach is versatile and easy to implement, supports thin‐shell and solid deformations of 2D and 3D objects, and is applicable to arbitrary sample‐based representations, such as meshes, triangle soups, or point clouds.
A Finite Element Method on Convex Polyhedra
Authors: Wicke Martin , Botsch Mario , Gross Markus
Published: October 2007

We present a method for animating deformable objects using a novel finite element discretization on convex polyhedra. Our finite element approach draws upon recently introduced 3D mean value coordinates to define smooth interpolants within the elements. The mathematical properties of our basis functions guarantee convergence. Our method is a natural extension to linear interpolants on tetrahedra: for tetrahedral elements, the methods are identical. For fast and robust computations, we use an elasticity model based on Cauchy strain and stiffness warping.

This more flexible discretization is particularly useful for simulations that involve topological changes, such as cutting or fracture. Since splitting convex elements along a plane produces convex elements, remeshing or subdivision schemes used in simulations based on tetrahedra are not necessary, leading to less elements after such operations. We propose various operators for cutting the polyhedral discretization. Our method can handle arbitrary cut trajectories, and there is no limit on how often elements can be split.
Ray‐Casted BlockMaps for Large Urban Models Visualization
Authors: Cignoni P. , Di Benedetto M. , Ganovelli F. , Gobbetti E. , Marton F. , Scopigno R.
Published: October 2007

We introduce a GPU‐friendly technique that efficiently exploits the highly structured nature of urban environments to ensure rendering quality and interactive performance of city exploration tasks. Central to our approach is a novel discrete representation, called BlockMap, for the efficient encoding and rendering of a small set of textured buildings far from the viewer. A BlockMap compactly represents a set of textured vertical prisms with a bounded on‐screen footprint. BlockMaps are stored into small fixed size texture chunks and efficiently rendered through GPU raycasting. Blockmaps can be seamlessly integrated into hierarchical data structures for interactive rendering of large textured urban models. We illustrate an efficient output‐sensitive framework in which a visibility‐aware traversal of the hierarchy renders components close to the viewer with textured polygons and employs BlockMaps for far away geometry. Our approach provides a bounded size far distance representation of cities, naturally scales with the improving shader technology, and outperforms current state of the art approaches. Its efficiency and generality is demonstrated with the interactive exploration of a large textured model of the city of Paris on a commodity graphics platform.
Metropolis Instant Radiosity
Authors: Segovia B. , Iehl J.C. , Péroche B.
Published: October 2007

We present Metropolis Instant Radiosity (MIR), an unbiased algorithm to solve the Light Transport problem. MIR is a hybrid technique which consists in representing the incoming radiance field by a set of Virtual Point Lights (V PLs) and in computing the response of all sensors in the scene (i.e. camera captors) by accumulating their contributions. In contrast to other similar approaches, we propose to sample the VPLs with an innovative Multiple‐try Metropolis‐Hastings (MTMH) Algorithm: the goal is to build an efficient, aggressive, and unconditionally robust variance reduction method that works well regardless of the scene layout. Finally, we present a fast ray tracing implementation using MIR and show how our complete rendering pipeline can produce high‐quality and high‐resolution pictures in a few seconds.
Superresolution Reflectance Fields: Synthesizing images for intermediate light directions
Authors: Fuchs Martin , Lensch Hendrik P. A. , Blanz Volker , Seidel Hans‐Peter
Published: October 2007

Captured reflectance fields tend to provide a relatively coarse sampling of the incident light directions. As a result, sharp illumination features, such as highlights or shadow boundaries, are poorly reconstructed during relighting; highlights are disconnected, and shadows show banding artefacts. In this paper, we propose a novel interpolation technique for 4D reflectance fields that reconstructs plausible images even for non‐observed light directions. Given a sparsely sampled reflectance field, we can effectively synthesize images as they would have been obtained from denser sampling. The processing pipeline consists of three steps: (1) segmentation of regions where intermediate lighting cannot be obtained by blending, (2) appropriate flow algorithms for highlights and shadows, plus (3) a final reconstruction technique that uses image‐based priors to faithfully correct errors that might be introduced by the segmentation or flow step. The algorithm reliably reproduces scenes that contain specular highlights, interreflections, shadows or caustics.
Textured Liquids based on the Marker Level Set
Authors: Mihalef V. , Metaxas D. , Sussman M.
Published: October 2007

In this work we propose a new Eulerian method for handling the dynamics of a liquid and its surface attributes (for example its color). Our approach is based on a new method for interface advection that we term the Marker Level Set (MLS). The MLS method uses surface markers and a level set for tracking the surface of the liquid, yielding more efficient and accurate results than popular methods like the Particle Level Set method (PLS). Another novelty is that the surface markers allow the MLS to handle non‐diffusively surface texture advection, a rare capability in the realm of Eulerian simulation of liquids. We present several simulations of the dynamical evolution of liquids and their surface textures.
Online Motion Capture Marker Labeling for Multiple Interacting Articulated Targets
Authors: Yu Qian , Li Qing , Deng Zhigang
Published: October 2007

In this paper, we propose an online motion capture marker labeling approach for multiple interacting articulated targets. Given hundreds of unlabeled motion capture markers from multiple articulated targets that are interacting each other, our approach automatically labels these markers frame by frame, by fitting rigid bodies and exploiting trained structure and motion models. Advantages of our approach include: 1) our method is an online algorithm, which requires no user interaction once the algorithm starts. 2) Our method is more robust than traditional the closest point‐based approaches by automatically imposing the structure and motion models. 3) Due to the use of the structure model which encodes the rigidity of each articulated body of captured targets, our method can recover missing markers robustly. Our approach is efficient and particularly suited for online computer animation and video game applications.
Precomputed Radiance Transfer Field for Rendering Interreflections in Dynamic Scenes
Authors: Pan Minghao , Wang Xinguo Liu Rui , Peng Qunsheng , Bao Hujun
Published: October 2007

In this paper, we introduce a new representation – radiance transfer fields (RTF) – for rendering interreflections in dynamic scenes under low frequency illumination. The RTF describes the radiance transferred by an individual object to its surrounding space as a function of the incident radiance. An important property of RTF is its independence of the scene configuration, enabling interreflection computation in dynamic scenes. Secondly, RTFs naturally fit in with the rendering framework of precomputed shadow fields, incurring negligible cost to add interreflection effects. In addition, RTFs can be used to compute interreflections for both diffuse and glossy objects. We also show that RTF data can be highly compressed by clustered principal component analysis (CPCA), which not only reduces the memory cost but also accelerates rendering. Finally, we present some experimental results demonstrating our techniques.
Global Illumination using Photon Ray Splatting
Authors: Herzog Robert , Havran Vlastimil , Kinuwaki Shinichi , Myszkowski Karol , Seidel Hans‐Peter
Published: October 2007

We present a novel framework for efficiently computing the indirect illumination in diffuse and moderately glossy scenes using density estimation techniques. Many existing global illumination approaches either quickly compute an overly approximate solution or perform an orders of magnitude slower computation to obtain high‐quality results for the indirect illumination. The proposed method improves photon density estimation and leads to significantly better visual quality in particular for complex geometry, while only slightly increasing the computation time. We perform direct splatting of photon rays, which allows us to use simpler search data structures. Since our density estimation is carried out in ray space rather than on surfaces, as in the commonly used photon mapping algorithm, the results are more robust against geometrically incurred sources of bias. This holds also in combination with final gathering where photon mapping often overestimates the illumination near concave geometric features. In addition, we show that our photon splatting technique can be extended to handle moderately glossy surfaces and can be combined with traditional irradiance caching for sparse sampling and filtering in image space.
Bitmask Soft Shadows
Authors: Schwarz Michael , Stamminger Marc
Published: October 2007

Recently, several real‐time soft shadow algorithms have been introduced which all compute a single shadow map and use its texels to obtain a discrete scene representation. The resulting micropatches are backprojected onto the light source and the light areas occluded by them get accumulated to estimate overall light occlusion. This approach ignores patch overlaps, however, which can lead to objectionable artifacts. In this paper, we propose to determine the visibility of the light source with a bit field where each bit tracks the visibility of a sample point on the light source. This approach not only avoids overlapping‐related artifacts but offers a solution to the important occluder fusion problem. Hence, it also becomes possible to correctly incorporate information from multiple depth maps. In addition, a new interpretation of the shadow map data is suggested which often provides superior visual results. Finally, we show how the search area for potential occluders can be reduced substantially.
Omni‐directional Relief Impostors
Authors: Andújar C. , Boo J. , Brunet P. , Fairén M. , Navazo I. , Vázquez P. , Vinacua À.
Published: October 2007

Relief impostors have been proposed as a compact and high‐quality representation for high‐frequency detail in 3D models. In this paper we propose an algorithm to represent a complex object through the combination of a reduced set of relief maps. These relief maps can be rendered with very few artifacts and no apparent deformation from any view direction. We present an efficient algorithm to optimize the set of viewing planes supporting the relief maps, and an image‐space metric to select a sufficient subset of relief maps for each view direction. Selected maps (typically three) are rendered based on the well‐known ray‐height‐field intersection algorithm implemented on the GPU. We discuss several strategies to merge overlapping relief maps while minimizing sampling artifacts and to reduce extra texture requirements. We show that our representation can maintain the geometry and the silhouette of a large class of complex shapes with no limit in the viewing direction. Since the rendering cost is output sensitive, our representation can be used to build a hierarchical model of a 3D scene.
3D Video Billboard Clouds
Authors: Waschbüsch Michael , Würmlin Stephan , Gross Markus
Published: October 2007

3D video billboard clouds reconstruct and represent a dynamic three‐dimensional scene using displacement‐mapped billboards. They consist of geometric proxy planes augmented with detailed displacement maps and combine the generality of geometry‐based 3D video with the regularization properties of image‐based 3D video. 3D video billboards are an image‐based representation placed in the disparity space of the acquisition cameras and thus provide a regular sampling of the scene with a uniform error model. We propose a general geometry filtering framework which generates time‐coherent models and removes reconstruction and quantization noise as well as calibration errors. This replaces the complex and time‐consuming sub‐pixel matching process in stereo reconstruction with a bilateral filter. Rendering is performed using a GPU‐accelerated algorithm which generates consistent view‐dependent geometry and textures for each individual frame. In addition, we present a semi‐automatic approach for modeling dynamic three‐dimensional scenes with a set of multiple 3D video billboards clouds.
Interactive Simulation of the Human Eye Depth of Field and Its Correction by Spectacle Lenses
Authors: Kakimoto Masanori , Tatsukawa Tomoaki , Mukai Yukiteru , Nishita Tomoyuki
Published: October 2007

This paper describes a fast rendering algorithm for verification of spectacle lens design. Our method simulates refraction corrections of astigmatism as well as myopia or presbyopia. Refraction and defocus are the main issues in the simulation. For refraction, our proposed method uses per‐vertex basis ray tracing which warps the environment map and produces a real‐time refracted image which is subjectively as good as ray tracing. Conventional defocus simulation was previously done by distribution ray tracing and a real‐time solution was impossible. We introduce the concept of a blur field, which we use to displace every vertex according to its position. The blurring information is precomputed as a set of field values distributed to voxels which are formed by evenly subdividing the perspective projected space. The field values can be determined by tracing a wavefront from each voxel through the lens and the eye, and by evaluating the spread of light at the retina considering the best human accommodation effort. The blur field is stored as texture data and referred to by the vertex shader that displaces each vertex. With an interactive frame rate, blending the multiple rendering results produces a blurred image comparable to distribution ray tracing output.
Pedestrian Reactive Navigation for Crowd Simulation: a Predictive Approach
Authors: Paris Sébastien , Pettré Julien , Donikian Stéphane
Published: October 2007

This paper addresses the problem of virtual pedestrian autonomous navigation for crowd simulation. It describes a method for solving interactions between pedestrians and avoiding inter‐collisions. Our approach is agent‐based and predictive: each agent perceives surrounding agents and extrapolates their trajectory in order to react to potential collisions. We aim at obtaining realistic results, thus the proposed model is calibrated from experimental motion capture data. Our method is shown to be valid and solves major drawbacks compared to previous approaches such as oscillations due to a lack of anticipation. We first describe the mathematical representation used in our model, we then detail its implementation, and finally, its calibration and validation from real data.
LIVING WITH THE CONTRADICTIONS OF MODERNIZATION? EMOTIONAL MANAGEMENT IN THE TEACHING PROFESSION
Authors: JENKINS SARAH , CONLEY HAZEL
Published: October 2007

The state education system in the UK has undergone significant transformation such that New Labour’s modernization policy embodies aspects of the marketized system, inspired by New Right thinking, with a concern for placing schools at the centre of the social inclusion agenda. In this paper, we explore the impact of the modernized agenda on teachers’ work and identify the tensions and contradictions which emanate from these policies. The research centred on interviews with teachers and headteachers in four school case studies and explores the changing nature of the profession by focusing on teachers’ emotional management. It is evident that at a time when a large proportion of what teachers do is subject to scrutiny and audit, the emotional and less definable elements of teaching have also increased but remain relatively unrecognized. The findings suggest that issues of emotional management bring into sharp relief the contradictions evident in the modernized agenda.
PERFORMING GOVERNANCE: A PARTNERSHIP BOARD DRAMATURGY
Authors: FREEMAN TIM , PECK EDWARD
Published: October 2007

This paper explores the governance of complex public sector partnerships through a detailed case study of a Joint Commissioning Partnership Board (JCPB) in the South East of England. It argues that a theoretical and empirical focus on the instrumental roles of boards has resulted in an under‐appreciation of their symbolic purposes, especially in the context of the governance of inter‐organizational relationships. The paper considers the performative dimension of partnership governance, highlighting the role of the symbolic in institutional enactment. Following a brief overview of governance in public sector partnerships, the case study site for the empirical research is introduced. The instrumental and symbolic roles of management boards are considered from a new institutionalist perspective and a dramaturgical analysis of institutional enactment undertaken to explore interplays of the symbolic and instrumental in strategy formation. Some implications for our understanding of the symbolic in partnership governance are discussed.
SELF‐REGULATION WITHIN THE REGULATORY STATE: TOWARDS A NEW REGULATORY PARADIGM?
Authors: BARTLE IAN , VASS PETER
Published: October 2007

An emerging feature of the modern regulatory state in Britain and elsewhere is the promotion of self‐regulation. This paper examines the relationship between the state and self‐regulation in the context of the challenge of meeting public interest objectives. It draws on research on the policy and practice of self‐regulation in recent years in Britain. The paper argues that the institutions, processes and mechanisms of the modern regulatory state and the ‘better regulation’ agenda in Britain, notably those that aim to foster transparency and accountability, can assist in the achievement of public interest objectives in self‐regulatory schemes. We conclude that a ‘new regulatory paradigm’ can be put forward which involves a form of regulatory ‘subsidiarity’, whereby the achievement of regulatory outcomes can be delegated downwards to the regulated organizations and self‐regulatory bodies while being offset by increasing public regulatory oversight based on systems of accountability and transparency.
Leon Trotsky in New York City
Authors: Thatcher Ian D.
Published: October 2007

The last three months of Leon Trotsky's emigration from tsarist Russia were spent in New York. However, apart from reference to the views he held on events in his homeland, biographers have thus far ignored other aspects of his literary activities of that time. Basing itself upon the Russian émigré journals produced in New York, this article reports the full range of Trotsky's journalism of January to March 1917. It shows, for example, how Trotsky entered the fray of American socialist politics with categories he had developed during the previous three years in Europe, and how he attempted to encourage others to keep America out of the war.
Neville vs. Percy: a Precedence Dispute circa 1442
Authors: Warner M. W. , Lacey Kay
Published: October 2007

Recent historical research has emphasized the rôle played by local aristocratic feuds in the outbreak of the Wars of the Roses. But it may be argued that the escalation of regional violence to a conflict at national level was instead the result of a profound void at the centre of government which originated from the incapacity of Henry VI to rule effectively. The document reproduced here reinforces this view since it demonstrates that the earls of Salisbury and Northumberland were on extremely bad terms some ten years before their vendetta contributed to the opening of civil war. In 1442 the Crown was able to control their quarrel. In 1453 it was not.
Papal Adventus at Rome in the Twelfth Century
Authors: Twyman Susan
Published: October 2007

The vitae of the 12th-century popes and other literary sources contain references to reception ceremonies performed to honour a pope arriving at Rome. For the papacy these events were a part of its imitatio imperii, a conscious imitation of the antique imperial ceremony of adventus, and an opportunity for the Romans to express their consent to papal rule. But detailed investigation reveals the hitherto unnoticed fact that these ceremonies almost invariably occurred at times of transition and upheaval such as when a papal election had been disrupted or contested, or after popular rebellion against papal rule. Under such circumstances adventus was performed as part of the process of reconciliation between the pope and the Romans.
The Borough Franchise after 1867
Authors: DAVIS JOHN , TANNER DUNCAN
Published: October 2007

This article investigates the practical effects of the extension of the parliamentary franchise in 1867, examining the extent of enfranchisement in different types of borough and the reasons for the differences observed. An uneven pattern emerges, with registration law more open-ended in its application than has previously been claimed, but with the practical obstacles to enfranchisement reinforced by the inadequacy of the registration machinery. The capricious process which resulted ensured that the limited pre-1918 franchise nonetheless displayed an unexpectedly wide social variation. Generalizations based upon the assumption that a limited electorate was also one which had been in some conscious way socially selected are therefore dangerous.
A French View of the Institue in 1921
Authors: Horn Joyce M.
Published: October 2007

In 1921, the young French historian, March Bloch, wrote for the Revue Historique a description of the newly-founded Institute of Historical Research and its philosophy and aims. Besides giving the 1921 text, with explanatory notes, the present article comments on some of the developments in the last seventy-five years.
Accessible Website Content Guidelines for Users with Intellectual Disabilities
Authors: Karreman Joyce , Van Der Geest Thea , Buursink Esmee
Published: October 2007

Background  The W3C Web Accessibility Initiative has issued guidelines for making websites better and easier to access for people with various disabilities (W3C Web Accessibility Initiative guidelines 1999).

Method  The usability of two versions of a website (a non‐adapted site and a site that was adapted on the basis of easy‐to‐read guidelines) was tested with two groups of 20 participants. One group had intellectual disabilities but could read, the other group had no identified intellectual disabilities. In a 2 × 2 experimental design, it was investigated whether the easy‐to‐read website was indeed better accessible and usable for the participants with intellectual disabilities.

Results  The adaptation of the website worked well for participants with intellectual disabilities. Users without identified intellectual disabilities were as effective with the adapted site as they were with the non‐adapted site.

Conclusion  The results form an empirical basis for recommendations about applying guidelines for easy‐to‐read text on websites for people with intellectual disabilities.