bluuebunny/crossref_metadata_2025 huggingface dataset:
Imaging phosphatidylinositol 4‐phosphate dynamics in living plant cells
Authors: Vermeer Joop E.M. , Thole Julie M. , Goedhart Joachim , Nielsen Erik , Munnik Teun , Gadella Jr Theodorus W.J.
Published: September 2008

Polyphosphoinositides represent a minor group of phospholipids, accounting for less than 1% of the total. Despite their low abundance, these molecules have been implicated in various signalling and membrane trafficking events. Phosphatidylinositol 4‐phosphate (PtdIns4P) is the most abundant polyphosphoinositide. 32Pi‐labelling studies have shown that the turnover of PtdIns4P is rapid, but little is known about where in the cell or plant this occurs. Here, we describe the use of a lipid biosensor that monitors PtdIns4P dynamics in living plant cells. The biosensor consists of a fusion between a fluorescent protein and a lipid‐binding domain that specifically binds PtdIns4P, i.e. the pleckstrin homology domain of the human protein phosphatidylinositol‐4‐phosphate adaptor protein‐1 (FAPP1). YFP–PHFAPP1 was expressed in four plant systems: transiently in cowpea protoplasts, and stably in tobacco BY‐2 cells, Medicago truncatula roots and Arabidopsis thaliana seedlings. All systems allowed YFP–PHFAPP1 expression without detrimental effects. Two distinct fluorescence patterns were observed: labelling of motile punctate structures and the plasma membrane. Co‐expression studies with organelle markers revealed strong co‐labelling with the Golgi marker STtmd–CFP, but not with the endocytic/pre‐vacuolar marker GFP–AtRABF2b. Co‐expression with the Ptdins3P biosensor YFP–2 × FYVE revealed totally different localization patterns. During cell division, YFP–PHFAPP1 showed strong labelling of the cell plate, but PtdIns3P was completely absent from the newly formed cell membrane. In root hairs of M. truncatula and A. thaliana, a clear PtdIns4P gradient was apparent in the plasma membrane, with the highest concentration in the tip. This only occurred in growing root hairs, indicating a role for PtdIns4P in tip growth.
Cutaneous mucinosis in shar‐pei dogs is due to hyaluronic acid deposition and is associated with high levels of hyaluronic acid in serum
Authors: Zanna G. , Fondevila D. , Bardagí M. , Docampo M. J. , Bassols A. , Ferrer L.
Published: September 2008

Cutaneous mucinosis affects primarily shar‐pei dogs. Hyaluronic acid (HA) is considered to be the main component of mucin and CD44 is the major cell surface receptor of HA, necessary for its uptake and catabolism. The aims of this study were to identify the composition of the mucin in cutaneous mucinosis of shar‐pei dogs, investigate the correlation between the deposition of HA and the expression of CD44, and determine whether shar‐pei dogs with cutaneous mucinosis presented with elevated levels of serum HA. In skin biopsies, the mucinous material was stained intensely with Alcian blue and bound strongly by the hyaluronan‐binding protein. No correlation was found between the degree of HA deposition in the dermis and the expression of CD44 in the skin of shar‐pei dogs affected or unaffected by cutaneous mucinosis. A clear positive correlation was found between the existence of clinical mucinosis and the serum HA concentration. In control dogs, serum HA ranged from 155.53 to 301.62 µg L−1 in shar‐pei dogs; without mucinosis it ranged from 106.72  to 1251.76 µg L−1 and in shar‐pei dogs with severe mucinosis it ranged between 843.51  to 2330.03 µg L−1. Altogether, the results reported here suggest that mucinosis of shar‐pei dogs is probably the consequence of a genetic defect in the metabolism of HA.
MESENCHYMAL STEM CELLS PROMOTE CARDIOMYOCYTE HYPERTROPHY IN VITRO THROUGH HYPOXIA‐INDUCED PARACRINE MECHANISMS
Authors: Xu Rui‐Xia , Chen Xi , Chen Jing‐Hai , Han Yu , Han Bian‐Mei
Published: September 2008

Mesenchymal stem cell (MSC) therapy for myocardial infarction has received increased attention since transplanted MSC were shown to improve cardiac function by transdifferentiating into cardiomyocytes and endothelial cells. However, recent studies have demonstrated that other mechanisms may contribute to the improvement in cardiac function observed after transplantation of MSC. The paracrine effect of MSC on cardiomyocyte is not clear. Thus, in the present study, we investigated the paracrine effect of MSC on the growth of neonatal rat cardiomyocytes in vitro.

Samples of MSC‐conditioned medium (MSC‐CM) were collected after rat MSC had been cultured under conditions of hypoxia and serum deprivation for 0, 3, 6, 9 or 24 h. Cardiomyocytes were then stimulated with the MSC‐CM for 48 h. Then, the protein content, cell area, [3H]‐leucine incorporation and atrial natriuretic factor‐luciferase (ANF‐Luc) expression of cardiomyocytes were measured.

The data showed that MSC‐CM collected at different time points had different effects and that MSC‐CM collected at 6 h significantly promoted cardiomyocyte hypertrophy by increasing total protein content, cell area, [3H]‐leucine incorporation and ANF gene expression.

In conclusion, MSC‐CM promoted cardiomyocyte hypertrophy in a paracrine manner. The results provide a better understanding of the mechanisms underlying the improvement in heart function after MSC transplantation.
EFFECT OF CHRONIC ASPIRIN ADMINISTRATION ON AN EXPERIMENTAL MODEL OF METABOLIC SYNDROME
Authors: Renna Nicolás F , Vazquez Marcela A , Lama Maria C , González Elsa S , Miatello Roberto M
Published: September 2008

The aim of the present study was to examine the effect of chronic administration of aspirin on metabolic and cardiovascular parameters in fructose‐fed rats (FFR), an experimental model of metabolic syndrome.

Chronic treatment of FFR with aspirin (10 mg/kg per day for 6 weeks) partially reversed the increment in systolic blood pressure. In addition, chronic aspirin treatment normalized relative heart weight and vascular remodelling of renal and carotid arteries, measured as lumen diameter : medial thickness ratio.

Furthermore, chronic aspirin administration completely reversed glucose intolerance and decreased the oxidative status that characterizes the FFR model, as indicated by decreased plasma levels of thiobarbituric acid‐reactive substances and aortic NAD(P)H oxidase activity.

Prevention of oxidative stress and vascular remodelling in FFR may contribute to the protective actions attributed to aspirin in the treatment of metabolic syndrome.
NEUROPROTECTIVE EFFECTS OF A SELECTIVE N‐METHYL‐d‐ASPARTATE NR2B RECEPTOR ANTAGONIST IN THE 6‐HYDROXYDOPAMINE RAT MODEL OF PARKINSON'S DISEASE
Authors: Leaver KR , Allbutt HN , Creber NJ , Kassiou M , Henderson JM
Published: September 2008

Current pharmacotherapies for the treatment of Parkinson's disease (PD) are largely symptomatic and do not attenuate the characteristic nigral (dopamine) cell loss.

Using the 6‐hydroxydopamine (6‐OHDA) rat model of PD, we investigated the novel, potentially neuroprotective compound BZAD‐01, which is an N‐methyl‐D‐aspartate (NMDA) glutamate receptor antagonist selective for the NR2B subunit.

Forty female Sprague‐Dawley rats were pretreated with either 10 mg/kg BZAD‐01 or vehicle (5% sucrose and 0.1% ascorbate) in their drinking water for 11 days prior to and for 3 days following 6‐OHDA surgery. During surgery, rats received an injection of either a toxic dose of 16 µg 6‐OHDA or a non‐toxic dose of 1 µg 6‐OHDA (sham) into the medial forebrain bundle. A series of behavioural tests, including curling (measuring body axis bias), head position bias and narrow beam, was performed fortnightly for 8 weeks after surgery to assess the effects of BZAD‐01 pretreatment on parkinsonism. Drug‐induced rotational asymmetry was also assessed just before rats were killed. Post‐mortem immunohistochemistry was performed to quantify the degree of nigral dopamine cell loss.

Pretreatment of 6‐OHDA‐lesioned rats with BZAD‐01 significantly reduced the amount of dopamine cell loss and significantly improved all behavioural measures. Furthermore, there was no significant difference in any of the behavioural measures between lesioned rats pretreated with BZAD‐01 and rats that underwent sham surgery.
INHIBITORY EFFECT OF EMODIN ON BLEOMYCIN‐INDUCED PULMONARY FIBROSIS IN MICE
Authors: Chen Xiao‐Hong , Sun Ren‐Shan , Hu Jian‐Ming , Mo Zi‐Yao , Yang Zi‐Feng , Jin Guang‐Yao , Guan Wen‐Da , Zhong Nan‐Shan
Published: September 2008

Currently, there is no satisfactory treatment for pulmonary fibrosis. Emodin, a component in Chinese herbs, has been shown to have an antifibrotic effect on pancreatic fibrosis and liver fibrosis. In the present study, we tested the hypothesis that emodin may attenuate the development of pulmonary fibrosis.

Mice were randomly divided into five groups (n = 16 in each). One group was a control group; the remaining four groups were treated with intratracheal instillation of 3 mg/kg bleomycin (BLM). The following day, emodin (5, 10 or 20 mg/kg per day, p.o.) treatment was started for three of the BLM‐treated groups and was continued for 21 days. The fourth BLM‐treated group (and the control group) received daily 0.5% sodium carboxymethyl cellulose (placebo) by gavage over the same period.

Bleomycin challenge provoked severe pulmonary fibrosis, with marked increases in fibrosis fraction, hydroxyproline content and myeloperoxidase activity in lung tissue. Emodin treatment (10 and 20 mg/kg per day, p.o.) attenuated all these biochemical indices, as well as histopathological alterations induced by BLM. Furthermore, in mice injected with BLM, elevated levels of transforming growth factor‐β1, interluekin (IL)‐4 and IL‐13 were found in bronchoalveolar lavage fluid. These increases were significantly inhibited by 10 and 20 mg/kg per day emodin.

In cell culture, exposure of cells to 6.25, 12.5, 25 or 50 µmol/L emodin for 24 h decreased fibroblast proliferation. Treatment of cells with the same concentrations of emodin for 72 h decreased collagen production by fibroblasts. In addition, emodin (6.25, 12.5, 25 or 50 µmol/L) inhibited the steady state expression of α1 (I) procollagen and α2 (I) procollagen mRNA in a dose‐dependent manner.

The results of the present study suggest that emodin may be effective in the treatment of pulmonary fibrosis.
EFFECT OF TEMPERATURE‐INDUCED REACTIVE OXYGEN SPECIES PRODUCTION ON EXCITATION–CONTRACTION COUPLING IN MAMMALIAN SKELETAL MUSCLE
Authors: Van Der Poel Chris , Edwards Joshua N , Macdonald William A , Stephenson D George
Published: September 2008

Here we review evidence obtained recently by us indicating that the poor longevity of isolated mammalian skeletal muscle preparations at temperatures in the normal physiological range is related to the increased production of reactive oxygen species (ROS) in the resting muscle.

Temperature‐induced ROS production increases markedly above 32°C in isolated, resting skeletal muscle and is associated with the gradual and irreversible functional deterioration of the muscle.

The majority of the temperature‐induced muscle ROS originates in the mitochondria and acts on various sites involved in excitation–contraction coupling.
HYPOGLYCAEMIC AND HYPOLIPIDAEMIC EFFECTS OF EMODIN AND ITS EFFECT ON L‐TYPE CALCIUM CHANNELS IN DYSLIPIDAEMIC–DIABETIC RATS
Authors: Zhao Xiao‐Yan , Qiao Guo‐Fen , Li Bao‐Xin , Chai Li‐Min , Li Zhe , Lu Yan‐Jie , Yang Bao‐Feng
Published: September 2008

The aim of the present study was to evaluate the hypoglycaemic and hypolipidaemic effects of 20, 40 and 80 mg/kg per day emodin and its potential effects on L‐type calcium channels in dyslipidaemic–diabetic rats.

Dyslipidaemic‐diabetic rats were induced by a single intraperitoneal injection of streptozotocin (55 mg/kg) after intragastric administration of a high‐fat diet for 2 weeks.

Daily administration of emodin for 2 weeks resulted in a significant dose‐dependent reductions in blood glucose, serum total cholesterol, triglycerides, free fatty acids and malonaldehyde (P < 0.05) in dyslipidaemic–diabetic rats compared with vehicle‐treated dyslipidaemic–diabetic rats. In addition, emodin caused dose‐dependent increases in plasma superoxide dismutase activity in dyslipidaemic–diabetic rats (P < 0.05). Immunofluorescent staining and reverse transcription–polymerase chain reaction showed that the expression of L‐type calcium channels in the pancreas and heart was restored, to different extents, by the three doses of emodin treatment.

The results of the present study suggest that emodin has antidiabetic and lipid‐modulating effects that involve, in part, upregulation of L‐type calcium channel expression in the pancreas and heart in dyslipidaemic–diabetic rats.
Achalasia cardia presenting as stridor
Authors: WECHALEKAR Mihir D. , SOUTHCOTT Anne M.
Published: September 2008

Achalasia cardia is a motility disorder of the oesophagus characterized by aperistalsis of the oesophageal body and incomplete relaxation of the lower oesophageal sphincter. It usually presents with dysphagia, regurgitation and heartburn. It may have various respiratory manifestations. Rarely, it may be complicated by acute airway compromise causing stridor. This case report presents an elderly woman with massive dilatation of the oesophagus secondary to achalasia, who presented with a short history of heartburn and rapid deterioration of her respiratory status due to tracheal compromise and stridor as a result of achalasia. The various hypotheses regarding the pathogenesis of this rare complication are described.
On the relationship between mass and diameter distributions in tree communities
Authors: Stegen James C. , White Ethan P.
Published: September 2008

It has been suggested that frequency distributions of individual tree masses in natural stands are characterized by power‐law distributions with exponents near −3/4, and that therefore tree communities exhibit energetic equivalence among size classes. Because the mass of trees is not measured directly, but estimated from diameter, this supposition is based on the fact that the observed distribution of tree diameters is approximately characterized by a power‐law with an exponent ≈ −2. Here we show that diameter distributions of this form are not equivalent to mass distributions with exponents of −3/4, but actually to mass distributions with exponents of −11/8. We discuss the implications of this result for the metabolic theory of ecology and for understanding energetic equivalence and the processes structuring tree communities.
(R)‐(+)‐limonene, kairomone forDastarcus helophoroides, a natural enemy of longhorned beetles
Authors: Wei Jian‐Rong , Yang Zhong‐Qi , Hao Hui‐Ling , Du Jia‐Wei
Published: September 2008

1 Chemical cues involved in host location byDastarcus helophoroides(Fairmaire) (Coleoptera: Bothrideridae), a parasitoid ofAnoplophora glabripennisMotschulsky,Monochamus alternatusHope,Massicus raddei(Blessig),Apriona germari(Hope),Apriona swainsoni(Hope) andBatocera horsfielde(Hope) in the family Cerambycidae, were investigated in a Y‐tube olfactometer. Responses ofD. helophoroidesadults toward odour sources from their host (M. raddei) and host tree (Quercus mongolicusFisch. ex. Turcz.) were tested in either no‐choice or two‐way choice tests. Wood with larval tunnels and larvae frass were attractive toD. helophoroides. Both sexes showed attraction to wood with larval tunnels.

2 Volatile chemicals emitted from wood with larval tunnels and larval frass were collected on Porapak Q and analyzed by gas chromatography‐mass spectrometry. Several compounds identified from these sources, including α‐pinene, β‐pinene, Δ‐3‐carene, limonene and β‐myrcene, were tested againstD. helophoroidesin the same Y‐tube olfactometer.

3 The result showed thatD. helophoroidesadults were attracted to (R)‐(+)‐limonene, with or without the background odour from uninfested fresh wood. This may suggest that (R)‐(+)‐limonene is an important kairomone for this parasitic beetle.

4 Dose‐dependent response ofD. helophoroidesadults to (R)‐(+)‐limonene indicated thatD. helophoroidesadults showed significant attraction to (R)‐(+)‐limonene when release rates exceeded 2.08 μg/h in Y‐tube olfactometer tests. Moreover, significantly moreA. glabripennislarvae were parasitized byD. helophoroidesin the presence ofR‐(+)‐limonene, relative to the control in cage experiments.
Critical temperatures for xylogenesis in conifers of cold climates
Authors: Rossi Sergio , Deslauriers Annie , Griçar Jozica , Seo Jeong‐Wook , Rathgeber Cyrille BK , Anfodillo Tommaso , Morin Hubert , Levanic Tom , Oven Primoz , Jalkanen Risto
Published: September 2008

Aim  To identify temperatures at which cell division and differentiation are active in order to verify the existence of a common critical temperature determining growth in conifers of cold climates.

Location  Ten European and Canadian sites at different latitudes and altitudes.

Methods  The periods of cambial activity and cell differentiation were assessed on a weekly time‐scale on histological sections of cambium and wood tissue collected over 2 to 5 years per site from 1998 to 2005 from the stems of seven conifer species. All data were compared with daily air temperatures recorded from weather stations located close to the sites. Logistic regressions were used to calculate the probability of xylogenesis and of cambium being active at a given temperature.

Results  Xylogenesis lasted from May to October, with a growing period varying from 3 to 5 months depending on location and elevation. Despite the wide geographical range of the monitored sites, temperatures for onset and ending of xylogenesis converged towards narrow ranges with average values around 4–5, 8–9 and 13–14 °C for daily minimum, mean and maximum temperature, respectively. On the contrary, cell division in the cambium stopped in July−August, when temperatures were still high.

Main conclusions  Wood formation in conifers occurred when specific critical temperatures were reached. Although the timing and duration of xylogenesis varied among species, sites and years, the estimated temperatures were stable for all trees studied. These results provide biologically based evidence that temperature is a critical factor limiting production and differentiation of xylem cells in cold climates. Although daily temperatures below 4−5 °C are still favourable for photosynthesis, thermal conditions below these values could inhibit the allocation of assimilated carbon to structural investment, i.e. xylem growth.
Quantifying the advantage of secondary mathematics study for accounting and finance undergraduates
Authors: Alcock Jamie , Cockcroft Sophie , Finn Frank
Published: September 2008

We examine the role that secondary mathematics plays in the performance of students in introductory business courses. Students who pass more advanced secondary mathematics subjects perform significantly better in introductory business courses. This ‘mathematics effect’ is significantly stronger than the effect of other business‐related secondary subjects, such as economics or accounting. Our findings also confirm previous studies showing that secondary accounting is beneficial for studying first‐year tertiary accounting. Interestingly though, we find that studying secondary economics can detract from a student's introductory tertiary results in some courses. Our findings have implications for educators and administrators as well as current secondary students.
Exposure Fusion: A Simple and Practical Alternative to High Dynamic Range Photography
Authors: Mertens T. , Kautz J. , Van Reeth F.
Published: September 2008

We propose a technique for fusing a bracketed exposure sequence into a high quality image, without converting to High dynamic range (HDR) first. Skipping the physically based HDR assembly step simplifies the acquisition pipeline. This avoids camera response curve calibration and is computationally efficient. It also allows for including flash images in the sequence. Our technique blends multiple exposures, guided by simple quality measures like saturation and contrast. This is done in a multiresolution fashion to account for the brightness variation in the sequence. The resulting image quality is comparable to existing tone mapping operators.
The Visual Computing of Projector‐Camera Systems
Authors: Bimber Oliver , Iwai Daisuke , Wetzstein Gordon , Grundhöfer Anselm
Published: September 2008

This article focuses on real‐time image correction techniques that enable projector‐camera systems to display images onto screens that are not optimized for projections, such as geometrically complex, coloured and textured surfaces. It reviews hardware‐accelerated methods like pixel‐precise geometric warping, radiometric compensation, multi‐focal projection and the correction of general light modulation effects. Online and offline calibration as well as invisible coding methods are explained. Novel attempts in super‐resolution, high‐dynamic range and high‐speed projection are discussed. These techniques open a variety of new applications for projection displays. Some of them will also be presented in this report.
Compression and Importance Sampling of Near‐Field Light Sources
Authors: Mas Albert , Martín Ignacio , Patow Gustavo
Published: September 2008

This paper presents a method for compressing measured datasets of the near‐field emission of physical light sources (represented by raysets). We create a mesh on the bounding surface of the light source that stores illumination information. The mesh is augmented with information about directional distribution and energy density. We have developed a new approach to smoothly generate random samples on the illumination distribution represented by the mesh, and to efficiently handle importance sampling of points and directions. We will show that our representation can compress a 10 million particle rayset into a mesh of a few hundred triangles. We also show that the error of this representation is low, even for very close objects.
High‐speed Marching Cubes using HistoPyramids
Authors: Dyken Christopher , Ziegler Gernot , Theobalt Christian , Seidel Hans‐Peter
Published: September 2008

We present an implementation approach for Marching Cubes (MC) on graphics hardware for OpenGL 2.0 or comparable graphics APIs. It currently outperforms all other known graphics processing units (GPU)‐based iso‐surface extraction algorithms in direct rendering for sparse or large volumes, even those using the recently introduced geometry shader (GS) capabilites. To achieve this, we outfit the Histogram Pyramid (HP) algorithm, previously only used in GPU data compaction, with the capability for arbitrary data expansion. After reformulation of MC as a data compaction and expansion process, the HP algorithm becomes the core of a highly efficient and interactive MC implementation. For graphics hardware lacking GSs, such as mobile GPUs, the concept of HP data expansion is easily generalized, opening new application domains in mobile visual computing. Further, to serve recent developments, we present how the HP can be implemented in the parallel programming language CUDA (compute unified device architecture), by using a novel 1D chunk/layer construction.
Transferring the Rig and Animations from a Character to Different Face Models
Authors: Orvalho Verónica Costa , Zacur Ernesto , Susin Antonio
Published: September 2008

We introduce a facial deformation system that allows artists to define and customize a facial rig and later apply the same rig to different face models. The method uses a set of landmarks that define specific facial features and deforms the rig anthropometrically. We find the correspondence of the main attributes of a source rig, transfer them to different three‐demensional (3D) face models and automatically generate a sophisticated facial rig. The method is general and can be used with any type of rig configuration. We show how the landmarks, combined with other deformation methods, can adapt different influence objects (NURBS surfaces, polygon surfaces, lattice) and skeletons from a source rig to individual face models, allowing high quality geometric or physically‐based animations. We describe how it is possible to deform the source facial rig, apply the same deformation parameters to different face models and obtain unique expressions. We enable reusing of existing animation scripts and show how shapes nicely mix one with the other in different face models. We describe how our method can easily be integrated in an animation pipeline. We end with the results of tests done with major film and game companies to show the strength of our proposal.
Fast Ray Tracing of Arbitrary Implicit Surfaces with Interval and Affine Arithmetic
Authors: Knoll A. , Hijazi Y. , Kensler A. , Schott M. , Hansen C. , Hagen H.
Published: September 2008

Existing techniques for rendering arbitrary‐form implicit surfaces are limited, either in performance, correctness or flexibility. Ray tracing algorithms employing interval arithmetic (IA) or affine arithmetic (AA) for root‐funding are robust and general in the class of surfaces they support, but traditionally slow. Nonetheless, implemented efficiently using a stack‐driven iterative algorithm and SIMD vector instructions, these methods can achieve interactive performance for common algebraic surfaces on the CPU. A similar algorithm can also be implemented stacklessly, allowing for efficient ray tracing on the GPU. This paper presents these algorithms, as well as an inclusion‐preserving reduced affine arithmetic (RAA) for faster ray‐surface intersection. Shader metaprogramming allows for immediate and automatic generation of symbolic expressions and their interval or affine extensions. Moreover, we are able to render even complex forms robustly, in real‐time at high resolution.
GPU‐Based Spherical Light Field Rendering with Per‐Fragment Depth Correction
Authors: Todt S. , Rezk‐Salama C. , Kolb A. , Kuhnert K.‐D.
Published: September 2008

Image‐based rendering techniques are a powerful alternative to traditional polygon‐based computer graphics. This paper presents a novel light field rendering technique which performs per‐pixel depth correction of rays for high‐quality reconstruction. Our technique stores combined RGB and depth values in a parabolic 2D texture for every light field sample acquired at discrete positions on a uniform spherical setup. Image synthesis is implemented on the GPU as a fragment program which extracts the correct image information from adjacent cameras for each fragment by applying per‐pixel depth correction of rays.

We show that the presented image‐based rendering technique provides a significant improvement compared to previous approaches. We explain two different rendering implementations which make use of a uniform parametrisation to minimise disparity problems and ensure full six degrees of freedom for virtual view synthesis. While one rendering algorithm implements an iterative refinement approach for rendering light fields with per pixel depth correction, the other approach employs a raycaster, which provides superior rendering quality at moderate frame rates.

GPU based per‐fragment depth correction of rays, used in both implementations, helps reducing ghosting artifacts to a non‐noticeable amount and provides a rendering technique that performs without exhaustive pre‐processing for 3D object reconstruction and without real‐time ray‐object intersection calculations at rendering time.
Peek‐in‐the‐Pic: Flying Through Architectural Scenes From a Single Image*
Authors: Shesh Amit , Chen Baoquan
Published: September 2008

Many casually taken ‘tourist’ photographs comprise of architectural objects like houses, buildings, etc. Reconstructing such 3D scenes captured in a single photograph is a very challenging problem. We propose a novel approach to reconstruct such architectural scenes with minimal and simple user interaction, with the goal of providing 3D navigational capability to an image rather than acquiring accurate geometric detail. Our system, Peek‐in‐the‐Pic, is based on a sketch‐based geometry reconstruction paradigm. Given an image, the user simply traces out objects from it. Our system regards these as perspective line drawings, automatically completes them and reconstructs geometry from them. We make basic assumptions about the structure of traced objects and provide simple gestures for placing additional constraints. We also provide a simple sketching tool to progressively complete parts of the reconstructed buildings that are not visible in the image and cannot be automatically completed. Finally, we fill holes created in the original image when reconstructed buildings are removed from it, by automatic texture synthesis. Users can spend more time using interactive texture synthesis for further refining the image. Thus, instead of looking at flat images, a user can fly through them after some simple processing. Minimal manual work, ease of use and interactivity are the salient features of our approach.
Precomputed Atmospheric Scattering
Authors: Bruneton Eric , Neyret Fabrice
Published: September 2008

We present a new and accurate method to render the atmosphere in real time from any viewpoint from ground level to outer space, while taking Rayleigh and Mie multiple scattering into account. Our method reproduces many effects of the scattering of light, such as the daylight and twilight sky color and aerial perspective for all view and light directions, or the Earth and mountain shadows (light shafts) inside the atmosphere. Our method is based on a formulation of the light transport equation that is precomputable for all view points, view directions and sun directions. We show how to store this data compactly and propose a GPU compliant algorithm to precompute it in a few seconds. This precomputed data allows us to evaluate at runtime the light transport equation in constant time, without any sampling, while taking into account the ground for shadows and light shafts.
Sequential Monte Carlo Adaptation in Low‐Anisotropy Participating Media
Authors: Pegoraro Vincent , Wald Ingo , Parker Steven G.
Published: September 2008

This paper presents a novel method that effectively combines both control variates and importance sampling in a sequential Monte Carlo context. The radiance estimates computed during the rendering process are cached in a 5D adaptive hierarchical structure that defines dynamic predicate functions for both variance reduction techniques and guarantees well‐behaved PDFs, yielding continually increasing efficiencies thanks to a marginal computational overhead. While remaining unbiased, the technique is effective within a single pass as both estimation and caching are done online, exploiting the coherency in illumination while being independent of the actual scene representation. The method is relatively easy to implement and to tune via a single parameter, and we demonstrate its practical benefits with important gains in convergence rate and competitive results with state of the art techniques.
Table‐driven Adaptive Importance Sampling
Authors: Cline David , Adams Daniel , Egbert Parris
Published: September 2008

Monte Carlo rendering algorithms generally rely on some form of importance sampling to evaluate the measurement equation. Most of these importance sampling methods only take local information into account, however, so the actual importance function used may not closely resemble the light distribution in the scene. In this paper, we present Table‐driven Adaptive Importance Sampling (TAIS), a sampling technique that augments existing importance functions with tabular importance maps that direct sampling towards undersampled regions of path space. The importance maps are constructed lazily, relying on information gathered during the course of sampling. During sampling the importance maps act either in parallel with or as a preprocess to existing importance sampling methods. We show that our adaptive importance maps can be effective at reducing variance in a number of rendering situations.
Exploiting Visibility Correlation in Direct Illumination
Authors: Clarberg Petrik , Akenine‐Möller Tomas
Published: September 2008

The visibility function in direct illumination describes the binary visibility over a light source, e.g., an environment map. Intuitively, the visibility is often strongly correlated between nearby locations in time and space, but exploiting this correlation without introducing noticeable errors is a hard problem. In this paper, we first study the statistical characteristics of the visibility function. Then, we propose a robust and unbiased method for using estimated visibility information to improve the quality of Monte Carlo evaluation of direct illumination. Our method is based on the theory of control variates, and it can be used on top of existing state‐of‐the‐art schemes for importance sampling. The visibility estimation is obtained by sparsely sampling and caching the 4D visibility field in a compact bitwise representation. In addition to Monte Carlo rendering, the stored visibility information can be used in a number of other applications, for example, ambient occlusion and lighting design.
Stylized Vector Art from 3D Models with Region Support
Authors: Eisemann Elmar , Winnemöller Holger , Hart John C. , Salesin David
Published: September 2008

We describe a rendering system that converts a 3D meshed model into the stylized 2D filled‐region vector‐art commonly found in clip‐art libraries. To properly define filled regions, we analyze and combine accurate but jagged face‐normal contours with smooth but inaccurate interpolated vertex normal contours, and construct a new smooth shadow contour that properly surrounds the actual jagged shadow contour. We decompose region definition into geometric and topological components, using machine precision for geometry processing and raster‐precision to accelerate topological queries. We extend programmable stylization to simplify, smooth and stylize filled regions. The result renders 10K‐face meshes into custom clip‐art in seconds.
Shallow Bounding Volume Hierarchies for Fast SIMD Ray Tracing of Incoherent Rays
Authors: Dammertz H. , Hanika J. , Keller A.
Published: September 2008

Photorealistic image synthesis is a computationally demanding task that relies on ray tracing for the evaluation of integrals. Rendering time is dominated by tracing long paths that are very incoherent by construction. We therefore investigate the use of SIMD instructions to accelerate incoherent rays. SIMD is used in the hierarchy construction, the tree traversal and the leaf intersection. This is achieved by increasing the arity of acceleration structures, which also reduces memory requirements. We show that the resulting hierarchies can be built quickly and are smaller than acceleration structures known so far while at the same time outperforming them for incoherent rays. Our new acceleration structure speeds up ray tracing by a factor of 1.6 to 2.0 compared to a highly optimized bounding interval hierarchy implementation, and 1.3 to 1.6 compared to an efficient kd‐tree. At the same time, the memory requirements are reduced by 10–50%. Additionally we show how a caching mechanism in conjunction with this memory efficient hierarchy can be used to speed up shadow rays in a global illumination algorithm without increasing the memory footprint. This optimization decreased the number of traversal steps up to 50%.
ScribbleBoost: Adding Classification to Edge‐Aware Interpolation of Local Image and Video Adjustments
Authors: Li Y. , Adelson E. , Agarwala A.
Published: September 2008

One of the most common tasks in image and video editing is the local adjustment of various properties (e.g., saturation or brightness) of regions within an image or video. Edge‐aware interpolation of user‐drawn scribbles offers a less effort‐intensive approach to this problem than traditional region selection and matting. However, the technique suffers a number of limitations, such as reduced performance in the presence of texture contrast, and the inability to handle fragmented appearances. We significantly improve the performance of edge‐aware interpolation for this problem by adding a boosting‐based classification step that learns to discriminate between the appearance of scribbled pixels. We show that this novel data term in combination with an existing edge‐aware optimization technique achieves substantially better results for the local image and video adjustment problem than edge‐aware interpolation techniques without classification, or related methods such as matting techniques or graph cut segmentation.
Fast Soft Self‐Shadowing on Dynamic Height Fields
Authors: Snydre John , Nowrouzezahrai Derek
Published: September 2008

We present a new, real‐time method for rendering soft shadows from large light sources or lighting environments on dynamic height fields. The method first computes a horizon map for a set of azimuthal directions. To reduce sampling, we compute a multi‐resolution pyramid on the height field. Coarser pyramid levels are indexed as the distance from caster to receiver increases. For every receiver point and every azimuthal direction, a smooth function of blocking angle in terms of log distance is reconstructed from a height difference sample at each pyramid level. This function's maximum approximates the horizon angle. We then sum visibility at each receiver point over wedges determined by successive pairs of horizon angles. Each wedge represents a linear transition in blocking angle over its azimuthal extent. It is precomputed in the order‐4 spherical harmonic (SH) basis, for a canonical azimuthal origin and fixed extent, resulting in a 2D table. The SH triple product of 16D vectors representing lighting, total visibility, and diffuse reflectance then yields the soft‐shadowed result. Two types of light sources are considered; both are distant and low‐frequency. Environmental lights require visibility sampling around the complete 360 ° azimuth, while key lights sample visibility within a partial swath. Restricting the swath concentrates samples where the light comes from (e.g. 3 azimuthal directions vs. 16‐32 for a full swath) and obtains sharper shadows. Our GPU implementation handles height fields up to 1024 × 1024 in real‐time. The computation is simple, local, and parallel, with performance independent of geometric content.
ReduceM: Interactive and Memory Efficient Ray Tracing of Large Models
Authors: Lauterbach Christian , Yoon Sung‐eui , Tang Ming , Manocha Dinesh
Published: September 2008

We present a novel representation and algorithm, ReduceM, for memory efficient ray tracing of large scenes. ReduceM exploits the connectivity between triangles in a mesh and decomposes the model into triangle strips. We also describe a new stripification algorithm, Strip‐RT, that can generate long strips with high spatial coherence. Our approach uses a two‐level traversal algorithm for ray‐primitive intersection. In practice, ReduceM can significantly reduce the storage overhead and ray trace massive models with hundreds of millions of triangles at interactive rates on desktop PCs with 4‐8GB of main memory.
‘He Who Decides’: Swedish Social Democratic Governments from a Presidentialisation Perspective
Authors: Sundström Göran
Published: September 2008

Using a presidentialisation perspective, this article investigates how the work of Swedish Social Democratic Governments has changed in recent decades. It examines whether the work of government has become less collegial and more presidential, and also whether any such changes have taken place gradually or in the form of clear departures during recent years, which is in line with the presidentialisation thesis. This thesis gains only some support in the article. The way the Swedish government is composed and the way it works shows a considerable degree of inertia. However, some changes have occurred. These changes relate foremost to issues connected with the government's forms of working and less to issues connected to the way the government is formed. The study also shows that some changes have occurred gradually while others have taken the form of departures. Thus, changes in the government's working forms have mostly occurred during the last decade. Regarding changes in forming the government, the departures took place earlier. It is concluded that the changes can be explained both by short‐term contingent factors, such as individual prime ministers’ leadership styles, and more structural factors, especially the growing internationalisation and mediatisation of the state.
Social Capital and Political Trust in Finland: An Individual‐level Assessment
Authors: Bäck Maria , Kestilä Elina
Published: September 2008

Political trust has in previous studies mainly been associated, either positively or negatively with a set of political variables, such as subjective knowledge of and interest in political issues, political efficacy, national pride, post‐materialist values and corruption permissiveness. More recently, it has been debated whether or not indicators of social capital also have an impact on political trust. It has been argued that social capital helps to sustain civic virtues and that lack of it will create democratic problems like political dissatisfaction and declining political participation. While trends in social capital seem stable and high at the aggregate level in Finland, the level of political trust has varied to a much larger degree. In this article, indicators of social capital, political variables and social background variables are set against the Finns’ trust in politicians and the parliament as well as their satisfaction with democracy. The analysis shows that social capital, as defined by a set of variables comprised of interpersonal trust and voluntary organisational activism, does not, en bloc, prove to be a powerful predictor of political trust. However, when the social capital items are examined as single factors, interpersonal trust seems to have strong impact on all levels of political trust, while the influence of voluntary organisational activity is less evident.
Hansen's disease in a general hospital: uncommon presentations and delay in diagnosis
Authors: Da Costa Nery JA , Schreuder PAM , Castro Teixeira de Mattos P , Vieira de Mendonça L , Tebaldi Tardi R , De Mello S , Azulay RD , Lehman LF , Naafs B
Published: September 2008

Background  The question was raised as to why ‘obvious’ signs of leprosy, Hansen's disease (HD), are often missed by medical doctors working in a HD endemic area.

Methods  This study describes a small sample of patients who were diagnosed with HD during their hospital admission and not before. The discussion is whether the typical early signs and symptoms of HD are just not recognized, or whether unusual presentations confuse the attending physician.

Results  A total of 23 HD patients were hospitalized during the study period, of which 6 (26%) were only diagnosed with HD during their admission. All were classified as lepromatous leprosy (LL) with a history of signs and symptoms of HD. In nearly all patients, a suspicion of HD might have been raised earlier if a careful history and dermato‐neurological examination had been done.

Conclusions  Multibacillary (MB) HD, especially close to the lepromatous end of the spectrum, may mimic other diseases, and the patient can not be diagnosed without a biopsy or a slit skin smear examination. Clinicians working in a HD endemic area (Rio de Janeiro) do not always include HD in their differential diagnosis, especially when the clinical presentation is unusual. HD should be considered in all patients with skin lesions not responding to treatment, especially when they have neurological deficits, and live or have lived in an HD endemic area. Due to the increase in global travel and immigration, doctors in low endemic areas need to consider HD as a possible diagnosis.

Conflicts of interest

None declared
Patients’ key experiences after coronary artery bypass grafting: a synthesis of qualitative studies
Authors: Leegaard Marit , Fagermoen May Solveig
Published: September 2008

For patients 40 years and over, ischemic coronary heart diseases are the most common reasons for admittance in European and North American hospitals. Coronary artery bypass grafting (CABG) has proved to be the most effective treatment for ischemic coronary heart diseases when other treatments are ineffective. The aim of this article was through a synthesis to integrate and explore qualitative studies regarding patients’ post‐CABG experiences. Electronic searches were carried out in four databases using search terms for CABG combined with key search terms associated with qualitative research. Nineteen of 45 qualitative studies identified met the inclusion criteria. The included studies were appraised by a reading guide. Relevant findings where subsequently thematically analyzed in line with principles in qualitative descriptive research. The following key concepts described patients’ experiences after CABG: The paradox of surviving alone with supportive relations, sense of self‐disrupted, losses, fears and getting on with life. Thus, the synthesis revealed that patients’ postoperative experiences influence their existential aspects of lifelong after surgery. Surprisingly, few studies treated suffering from postoperative pain as a specific topic. This underlines the need for more qualitative research exploring specific postsurgical experiences such as postoperative pain.
Haemodynamic and respiratory effects of an abdominal compression binder
Authors: Toft Mette Helene , Bülow Jens , Simonsen Lene
Published: September 2008

In order to elucidate the circulatory and respiratory effects of a newly developed abdominal compression binder 25 healthy, normal weight subjects were studied. In supine position the central haemodynamics were measured and estimated with a Finapress device. Lower extremity venous haemodynamics were measured in supine position with venous occlusion plethysmography. In an upright‐seated position arterial oxygen saturation was measured by a pulseoxymeter for 1 h before spirometry was performed with a turbine flow measurement device. All the tests were performed in a randomized order with or without the abdominal compression binder. The results show that the compression binder significantly increases the venous volume in the lower extremities as showed by a reduction in the venous capacitance in the lower extremities and a reduction in the stroke volume and cardiac output, while it does not influence the pulmonary volumes.

It is concluded that the applied abdominal binder significantly affects peripheral and central haemodynamics. It should therefore be used with caution when in the supine position for longer periods, as the pooling of blood it induces in the lower extremities may have implications for the risk of deep venous thrombosis formation.
Drug Courts: A Social Capital Perspective*
Authors: May Candace K.
Published: September 2008

Social capital is a variable resource embedded in all social networks. Although the majority of work on social capital describes it as contributing to socially beneficial outcomes, it also contributes to deviant activities. In addition to laying a theoretical basis for understanding the deviant potentials of social capital, this paper argues that a change in social networks results in a change in social capital. Using data collected from adult drug courts in Wyoming, multivariate ordinary least squares (OLS) regression analyses and analyses of personal interviews were used to explore changes in the social capital of drug court participants. However, as a result of deficiencies in available data, questions remain as to the long‐term social circumstances of participants after graduating from the programs and differences in social outcomes among minority groups. The results from this project have implications for future research conducted on drug courts and the theory of social capital.
Foreign Banks in Poor Countries: Theory and Evidence
Authors: DETRAGIACHE ENRICA , TRESSEL THIERRY , GUPTA POONAM
Published: September 2008

We study how foreign bank penetration affects financial sector development in poor countries. A theoretical model shows that when domestic banks are better than foreign banks at monitoring soft information customers, foreign bank entry may hurt these customers and worsen welfare. The model also predicts that credit to the private sector should be lower in countries with more foreign bank penetration, and that foreign banks should have a less risky loan portfolio. In the empirical section, we test these predictions for a sample of lower income countries and find support for the theoretical model.