bluuebunny/crossref_metadata_2025_split huggingface dataset:
Combining spatial and phylogenetic eigenvector filtering in trait analysis
Authors: Kühn Ingolf , Nobis Michael P. , Durka Walter 
Published: August 2009

ABSTRACTAim To analyse the effects of simultaneously using spatial and phylogenetic information in removing spatial autocorrelation of residuals within a multiple regression framework of trait analysis.Location Switzerland, Europe.Methods We used an eigenvector filtering approach to analyse the relationship between spatial distribution of a trait (flowering phenology) and environmental covariates in a multiple regression framework. Eigenvector filters were calculated from ordinations of distance matrices. Distance matrices were either based on pure spatial information, pure phylogenetic information or spatially structured phylogenetic information. In the multiple regression, those filters were selected which best reduced Moran'sIcoefficient of residual autocorrelation. These were added as covariates to a regression model of environmental variables explaining trait distribution.Results The simultaneous provision of spatial and phylogenetic information was effectively able to remove residual autocorrelation in the analysis. Adding phylogenetic information was superior to adding purely spatial information. Applying filters showed altered results, i.e. different environmental predictors were seen to be significant. Nevertheless, mean annual temperature and calcareous substrate remained the most important predictors to explain the onset of flowering in Switzerland; namely, the warmer the temperature and the more calcareous the substrate, the earlier the onset of flowering. A sequential approach, i.e. first removing the phylogenetic signal from traits and then applying a spatial analysis, did not provide more information or yield less autocorrelation than simple or purely spatial models.Main conclusions The combination of spatial and spatio‐phylogenetic information is recommended in the analysis of trait distribution data in a multiple regression framework. This approach is an efficient means for reducing residual autocorrelation and for testing the robustness of results, including the indication of incomplete parameterizations, and can facilitate ecological interpretation.
Locally Adapted Projections to Reduce Panorama Distortions
Authors: Kopf Johannes , Lischinski Dani , Deussen Oliver , Cohen‐Or Daniel , Cohen Michael 
Published: August 2009

AbstractDisplaying panoramic and wide angle views on a flat 2D display surface is necessarily prone to distortions. Perspective projections are limited to fairly narrow view angles. Cylindrical and spherical projections can show full 360° panoramas, but at the cost of curving straight lines, interfering with the perception of salient shapes in the scene.In this paper, we introducelocally‐adapted projections. Such projections are defined by a continuous projection surface consisting of both near‐planar and curved parts. A simple and intuitive user interface allows the specification of regions of interest to be mapped to the near‐planar parts, thereby reducing bending artifacts. We demonstrate the effectiveness of our approach on a variety of panoramic and wide angle images, including both indoor and outdoor scenes.
A Robust Illumination Estimate for Chromatic Adaptation in Rendered Images
Authors: Wilkie Alexander , Weidlich Andrea 
Published: August 2009

AbstractWe propose a method that improves automatic colour correction operations for rendered images. In particular, we propose a robust technique for estimating the visible and pertinent illumination in a given scene. We do this at very low computational cost by mostly re‐using information that is already being computed during the image synthesis process. Conventional illuminant estimations either operate only on 2D image data, or, if they do go beyond pure image analysis, only use information on the luminaires found in the scene. The latter is usually done with little or no regard for how the light sources actually affect the part of the scene that is being viewed. Our technique goes beyond that, and also takes object reflectance into account, as well as the incident light that is actually responsible for the colour of the objects that one sees. It is therefore able to cope with difficult cases, such as scenes with mixed illuminants, complex scenes with many light sources of varying colour, or strongly coloured indirect illumination.
Soft Textured Shadow Volume
Authors: Forest Vincent , Barthe Loïc , Guennebaud Gaël , Paulin Mathias 
Published: August 2009

AbstractEfficiently computing robust soft shadows is a challenging and time consuming task. On the one hand, the quality of image‐based shadows is inherently limited by the discrete property of their framework. On the other hand, object‐based algorithms do not exhibit such discretization issues but they can only efficiently deal with triangles having a constant transmittance factor. This paper addresses this limitation. We propose a general algorithm for the computation of robust and accurate soft shadows for triangles with a spatially varying transmittance. We then show how this technique can be efficiently included into object‐based soft shadow algorithms. This results in unified object‐based frameworks for computing robust direct shadows for both standard and perforated triangles in fully animated scenes.
Estimating Specular Roughness and Anisotropy from Second Order Spherical Gradient Illumination
Authors: Ghosh Abhijeet , Chen Tongbo , Peers Pieter , Wilson Cyrus A. , Debevec Paul 
Published: August 2009

AbstractThis paper presents a novel method for estimating specular roughness and tangent vectors, per surface point, from polarized second order spherical gradient illumination patterns. We demonstrate that for isotropic BRDFs, only three second order spherical gradients are sufficient to robustly estimate spatially varying specular roughness. For anisotropic BRDFs, an additional two measurements yield specular roughness and tangent vectors per surface point. We verify our approach with different illumination configurations which project both discrete and continuous fields of gradient illumination. Our technique provides a direct estimate of the per‐pixel specular roughness and thus does not require off‐line numerical optimization that is typical for the measure‐and‐fit approach to classical BRDF modeling.
Single Photo Estimation of Hair Appearance
Authors: Bonneel Nicolas , Paris Sylvain , Van De Panne Michiel , Durand Frédo , Drettakis George 
Published: August 2009

AbstractSignificant progress has been made in high‐quality hair rendering, but it remains difficult to choose parameter values that reproduce a given real hair appearance. In particular, for applications such as games where naive users want to create their own avatars, tuning complex parameters is not practical. Our approach analyses a single flash photograph and estimates model parameters that reproduce the visual likeness of the observed hair. The estimated parameters include color absorptions, three reflectance lobe parameters of a multiple‐scattering rendering model, and a geometric noise parameter. We use a novel melanin‐based model to capture the natural subspace of hair absorption parameters. At its core, the method assumes that images of hair with similar color distributions are also similar in appearance. This allows us to recast the issue as an image retrieval problem where the photo is matched with a dataset of rendered images; we thus also match the model parameters used to generate these images. An earth‐mover's distance is used between luminance‐weighted color distributions to gauge similarity. We conduct a perceptual experiment to evaluate this metric in the context of hair appearance and demonstrate the method on 64 photographs, showing that it can achieve a visual likeness for a large variety of input photos.
Dart Throwing on Surfaces
Authors: Cline D. , Jeschke S. , White K. , Razdan A. , Wonka P. 
Published: August 2009

AbstractIn this paper we present dart throwing algorithms to generate maximal Poisson disk point sets directly on 3D surfaces. We optimize dart throwing by efficiently excluding areas of the domain that are already covered by existing darts. In the case of triangle meshes, our algorithm shows dramatic speed improvement over comparable sampling methods. The simplicity of our basic algorithm naturally extends to the sampling of other surface types, including spheres, NURBS, subdivision surfaces, and implicits. We further extend the method to handle variable density points, and the placement of arbitrary ellipsoids without overlap. Finally, we demonstrate how to adapt our algorithm to work with geodesic instead of Euclidean distance. Applications for our method include fur modeling, the placement of mosaic tiles and polygon remeshing.
Characteristic Point Maps
Authors: Wu Hongzhi , Dorsey Julie , Rushmeier Holly 
Published: August 2009

AbstractExtremely dense spatial sampling is often needed to prevent aliasing when rendering objects with high frequency variations in geometry and reflectance. To accelerate the rendering process, we introduce characteristic point maps (CPMs), a hierarchy of view‐independent points, which are chosen to preserve the appearance of the original model across different scales. In preprocessing, randomized matrix column sampling is used to reduce an initial dense sampling to a minimum number of characteristic points with associated weights. In rendering, the reflected radiance is computed using a weighted average of reflectances from characteristic points. Unlike existing techniques, our approach requires no restrictions on the original geometry or reflectance functions.
FastV: From‐point Visibility Culling on Complex Models
Authors: Chandak Anish , Antani Lakulish , Taylor Micah , Manocha Dinesh 
Published: August 2009

AbstractWe present an efficient technique to compute the potentially visible set (PVS) of triangles in a complex 3D scene from a viewpoint. The algorithm computes a conservative PVS at object space accuracy. Our approach traces a high number of small, volumetric frusta and computes blockers for each frustum using simple intersection tests. In practice, the algorithm can compute the PVS of CAD and scanned models composed of millions of triangles at interactive rates on a multi‐core PC. We also use the visibility algorithm to accurately compute the reflection paths from a point sound source. The resulting sound propagation algorithm is 10–20X faster than prior accurate geometric acoustic methods.
GPU‐Assisted High Quality Particle Rendering
Authors: Cha Deukhyun , Son Sungjin , Ihm Insung 
Published: August 2009

AbstractVisualizing dynamic participating media in particle form by fully solving equations from the light transport theory is a computationally very expensive process. In this paper, we present a computational pipeline for particle volume rendering that is easily accelerated by the current GPU. To fully harness its massively parallel computing power, we transform input particles into a volumetric density field using a GPU‐assisted, adaptive density estimation technique that iteratively adapts the smoothing length for local grid cells. Then, the volume data is visualized efficiently based on the volume photon mapping method where our GPU techniques further improve the rendering quality offered by previous implementations while performing rendering computation in acceptable time. It is demonstrated that high quality volume renderings can be easily produced from large particle datasets in time frames of a few seconds to less than a minute.
Setting up and running a loss and bereavement support group for adults with learning disabilities
Authors: Boyden Paul , Freeman Adele , Offen Liz 
Published: August 2009

Accessible summary

We held a bereavement and loss group for people with learning disabilities.
The group ran for 8 weeks and there were five adults who came to the group.
The group helped people to share their feelings and experiences to help them cope with their bereavement.

SummaryFollowing evidence based literature, the Birmingham Clinical Psychology Service for People with Learning Disabilities ran a Loss and Bereavement Psychotherapy Group. The group consisted of five adults with mild learning disabilities, who met for 8 consecutive weeks. This paper reports the process of setting up a bereavement group for people with learning disabilities, detailing the development of session plans and structure of the group. The authors encourage allied health professionals to consider setting up similar groups within their learning disabilities services, bearing in mind reflections on practical issues highlighted within this paper.
Geographical Structure of the Y‐chromosomal Genetic Landscape of the Levant: A coastal‐inland contrast
Authors: El‐Sibai Mirvat , Platt Daniel E. , Haber Marc , Xue Yali , Youhanna Sonia C. , Wells R. Spencer , Izaabel Hassan , Sanyoura May F. , Harmanani Haidar , Bonab Maziar Ashrafian , Behbehani Jaafar , Hashwa Fuad , Tyler‐Smith Chris , Zalloua Pierre A. ,   The Genographic Consortium
Published: August 2009

SUMMARYWe have examined the male‐specific phylogeography of the Levant and its surroundings by analyzing Y‐chromosomal haplogroup distributions using 5874 samples (885 new) from 23 countries. The diversity within some of these haplogroups was also examined. The Levantine populations showed clustering in SNP and STR analyses when considered against a broad Middle‐East and North African background. However, we also found a coastal‐inland, east‐west pattern of diversity and frequency distribution in several haplogroups within the small region of the Levant. Since estimates of effective population size are similar in the two regions, this strong pattern is likely to have arisen mainly from differential migrations, with different lineages introduced from the east and west.
Variation in life‐history characteristics among populations of North American wood turtles: a view from the north
Authors: Greaves W. F. , Litzgus J. D. 
Published: August 2009

AbstractLife‐history traits such as age at maturity, body size and clutch size tend to vary across a species' distribution. The purpose of our study was to describe the demography of a newly discovered population of North American wood turtlesGlyptemys insculptaat the species' northern range limit, and to compare our findings to those of other studies to test hypotheses about adaptive life‐history variation. Turtles were hand‐captured from May to October 2005 and 2006 along a 4.5 km stretch of river located in the Sudbury District, ON, Canada (46°N). Fifty‐five captured individuals provided a population density estimate of 1.3 turtles/100 m of river. Juveniles comprised 35% of wood turtles captured, and growth ring counts (i.e. age estimates) indicated recruitment in each of the past 11 years. Among populations, we found a nonlinear pattern in body size variation with the largest turtles in the north, smallest turtles in the centre of the range, and intermediate‐sized turtles in the south. This nonlinear pattern in body size was reflected in clutch size variation. Selective pressures to overcome years of low recruitment may have resulted in larger body sizes and hence large clutch sizes at northern latitudes while conspecifics at southern latitudes can achieve larger body sizes because they live in a more productive environment. Population density decreased with latitude, likely as a result of a gradient in habitat productivity.
Protein phosphatase 5 protects neurons against amyloid‐β toxicity
Authors: Sanchez‐Ortiz Efrain , Hahm Byoung Kwon , Armstrong David L. , Rossie Sandra 
Published: August 2009

AbstractAmyloid‐β (Aβ) is thought to promote neuronal cell loss in Alzheimer’s disease, in part through the generation of reactive oxygen species (ROS) and subsequent activation of mitogen‐activated protein kinase (MAPK) pathways. Protein phosphatase 5 (PP5) is a ubiquitously expressed serine/threonine phosphatase which has been implicated in several cell stress response pathways and shown to inactivate MAPK pathways through key dephosphorylation events. Therefore, we examined whether PP5 protects dissociated embryonic rat cortical neurons in vitro from cell death evoked by Aβ. As predicted, neurons in which PP5 expression was decreased by small‐interfering RNA treatment were more susceptible to Aβ toxicity. In contrast, over‐expression of PP5, but not the inactive mutant, PP5(H304Q), prevented MAPK phosphorylation and neurotoxicity induced by Aβ. PP5 also prevented cell death caused by direct treatment with H2O2, but did not prevent Aβ‐induced production of ROS. Thus, the neuroprotective effect of PP5 requires its phosphatase activity and lies downstream of Aβ‐induced generation of ROS. In summary, our data indicate that PP5 plays a pivotal neuroprotective role against cell death induced by Aβ and oxidative stress. Consequently, PP5 might be an effective therapeutic target in Alzheimer’s disease and other neurodegenerative disorders in which oxidative stress is implicated.
eNOS gene deletion restores blood‐brain barrier integrity and attenuates neurodegeneration in the thiamine‐deficient mouse brain
Authors: Beauchesne Élizabeth , Desjardins Paul , Hazell Alan S. , Butterworth Roger F. 
Published: August 2009

AbstractWernicke’s encephalopathy is a cerebral disorder caused by thiamine (vitamin B1) deficiency (TD). Neuropathologic consequences of TD include region‐selective neuronal cell loss and blood‐brain barrier (BBB) breakdown. Early increased expression of the endothelial isoform of nitric oxide synthase (eNOS) occurs selectively in vulnerable brain regions in TD. We hypothesize that region‐selective eNOS induction in TD leads to altered expression of tight junction proteins and BBB breakdown. In order to address this issue, TD was induced in C57BL/6 wild‐type (WT) and eNOS−/− mice by feeding a thiamine‐deficient diet and treatment with the thiamine antagonist pyrithiamine. Pair‐fed control mice were fed the same diet with additional thiamine. In medial thalamus of TD‐WT mice (vulnerable area), increased heme oxygenase‐1 and S‐nitrosocysteine immunostaining was observed in vessel walls, compared to pair‐fed control‐WT mice. Concomitant increases in IgG extravasation, decreases in expression of the tight junction proteins occludin, zona occludens‐1 and zona occludens‐2, and up‐regulation of matrix metalloproteinase‐9 in endothelial cells were observed in the medial thalamus of TD‐WT mice. eNOS gene deletion restored these BBB alterations, suggesting that eNOS‐derived nitric oxide is a major factor leading to cerebrovascular alterations in TD. However, eNOS gene deletion only partially attenuated TD‐related neuronal cell loss, suggesting the presence of mechanisms additional to BBB disruption in the pathogenesis of these changes.
Decreased transketolase activity contributes to impaired hippocampal neurogenesis induced by thiamine deficiency
Authors: Zhao Yanling , Pan Xiaoli , Zhao Jing , Wang Yang , Peng Yun , Zhong Chunjiu 
Published: August 2009

AbstractThiamine deficiency (TD) impairs hippocampal neurogenesis. However, the mechanisms involved are not identified. In this work, TD mouse model was generated using a thiamine‐depleted diet at two time points, TD9 and TD14 for 9 and 14 days of TD respectively. The activities of pyruvate dehydrogenase (PDH), α‐ketoglutamate dehydrogenase (KGDH), glucose‐6‐phosphate dehydrogenase (G6PD), and transketolase (TK), as well as on the contents of NADP+ and NADPH were determined in whole mouse brain, isolated cortex, and hippocampus of TD mice model. The effects of TK silencing on the growth and migratory ability of cultured hippocampal progenitor cells (HPC), as well as on neuritogenesis of hippocampal neurons were explored. The results showed that TD specifically reduced TK activity in both cortex and hippocampus, without significantly affecting the activities of PDH, KGDH, and G6PD in TD9 and TD14 groups. The level of whole brain and hippocampal NADPH in TD14 group were significantly lower than that of control group. TK silencing significantly inhibited the proliferation, growth, and migratory abilities of cultured HPC, without affecting neuritogenesis of cultured hippocampal neurons. Taken together, these results demonstrate that decreased TK activity leads to pentose‐phosphate pathway dysfunction and contributes to impaired hippocampal neurogenesis induced by TD. TK and pentose‐phosphate pathway may be considered new targets to investigate hippocampal neurogenesis.
Diminished hippocalcin expression in Huntington’s disease brain does not account for increased striatal neuron vulnerability as assessed in primary neurons
Authors: Rudinskiy Nikita , Kaneko Yoshio A. , Beesen Ayshe Ana , Gokce Ozgun , Régulier Etienne , Déglon Nicole , Luthi‐Carter Ruth 
Published: August 2009

AbstractHippocalcin is a neuronal calcium sensor protein previously implicated in regulating neuronal viability and plasticity. Hippocalcin is the most highly expressed neuronal calcium sensor in the medium spiny striatal output neurons that degenerate selectively in Huntington’s disease (HD). We have previously shown that decreased hippocalcin expression occurs in parallel with the onset of disease phenotype in mouse models of HD. Here we show by in situ hybridization histochemistry that hippocalcin RNA is also diminished by 63% in human HD brain. These findings lead us to hypothesize that diminished hippocalcin expression might contribute to striatal neurodegeneration in HD. We tested this hypothesis by assessing whether restoration of hippocalcin expression would decrease striatal neurodegeneration in cellular models of HD comprising primary striatal neurons exposed to mutant huntingtin, the mitochondrial toxin 3‐nitropropionic acid or an excitotoxic concentration of glutamate. Counter to our hypothesis, hippocalcin expression did not improve the survival of striatal neurons under these conditions. Likewise, expression of hippocalcin together with interactor proteins including the neuronal apoptosis inhibitory protein did not increase the survival of striatal cells in cellular models of HD. These results indicate that diminished hippocalcin expression does not contribute to HD‐related neurodegeneration.
Pre‐medication and renal pre‐conditioning: a role for alprazolam, atropine, morphine and promethazine
Authors: Pazoki‐Toroudi Hamid Reza , Ajami Marjan , Habibey Rouhollah 
Published: August 2009

AbstractFour pre‐medication drugs are used to relieve pain, allay anxiety, reduce secretion and enhance hypnosis, were evaluated for their effects on ischemia reperfusion (I/R) injury which is one of the major complications of vascular and transplantation surgery. Right kidney was removed from female rats (210–250 g) 3 weeks before surgical procedure. Different doses of morphine (0.5, 2 and 5 mg/kg), promethazine (1, 2 and 5 mg/kg), atropine (0.1, 0.3 and 0.5 mg/kg) and alprazolam (0.08, 0.32 and 0.64 mg/kg) were administered subcutaneously 30 min before left renal artery occlusion and 6 h reperfusion. Left kidneys were processed for histological evaluations. Creatinine and BUN were measured in serum samples. Morphine, promethazine, atropine and alprazolam at all evaluated doses significantly decreased serum creatinine and BUN levels and histopathological scores. The effects of promethazine (1 mg/kg) and all doses of alprazolam were more potent than other pre‐medication drugs and doses. This study suggested a protective effect of these pre‐medication drugs on I/R injury. Although obvious studies are required, these findings may lead to effective therapies against I/R injury.