bluuebunny/crossref_metadata_2025_split huggingface dataset:
Roles of mGluR5 in synaptic function and plasticity of the mouse thalamocortical pathway
Authors: She Wei‐Chi , Quairiaux Charles , Albright Michael J. , Wang Yu‐Chi , Sanchez Denisse E. , Chang Poh‐Shing , Welker Egbert , Lu Hui‐Chen 
Published: March 2009

AbstractThe group I metabotropic glutamate receptor 5 (mGluR5) has been implicated in the development of cortical sensory maps. However, its precise roles in the synaptic function and plasticity of thalamocortical (TC) connections remain unknown. Here we first show that in mGluR5 knockout (KO) mice bred onto a C57BL6 background cytoarchitectonic differentiation into barrels is missing, but the representations for large whiskers are identifiable as clusters of TC afferents. The altered dendritic morphology of cortical layer IV spiny stellate neurons in mGluR5 KO mice implicates a role for mGluR5 in the dendritic morphogenesis of excitatory neurons. Next, in vivo single‐unit recordings of whisker‐evoked activity in mGluR5 KO adults demonstrated a preserved topographical organization of the whisker representation, but a significantly diminished temporal discrimination of center to surround whiskers in the responses of individual neurons. To evaluate synaptic function at TC synapses in mGluR5 KO mice, whole‐cell voltage‐clamp recording was conducted in acute TC brain slices prepared from postnatal day 4–11 mice. At mGluR5 KO TC synapses, N‐methyl‐d‐aspartate (NMDA) currents decayed faster and synaptic strength was more easily reduced, but more difficult to strengthen by Hebbian‐type pairing protocols, despite a normal developmental increase in α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid receptor (AMPAR)‐mediated currents and presynaptic function. We have therefore demonstrated that mGluR5 is required for synaptic function/plasticity at TC synapses as barrels are forming, and we propose that these functional alterations at the TC synapse are the basis of the abnormal anatomical and functional development of the somatosensory cortex in the mGluR5 KO mouse.
Fenton chemistry and oxidative stress mediate the toxicity of the β‐amyloid peptide in a Drosophila model of Alzheimer’s disease
Authors: Rival Thomas , Page Richard M. , Chandraratna Dhianjali S. , Sendall Timothy J. , Ryder Edward , Liu Beinan , Lewis Huw , Rosahl Thomas , Hider Robert , Camargo L. M. , Shearman Mark S. , Crowther Damian C. , Lomas David A. 
Published: March 2009

AbstractThe mechanism by which aggregates of the β‐amyloid peptide (Aβ) mediate their toxicity is uncertain. We show here that the expression of the 42‐amino‐acid isoform of Aβ (Aβ1–42) changes the expression of genes involved in oxidative stress in a Drosophila model of Alzheimer’s disease. A subsequent genetic screen confirmed the importance of oxidative stress and a molecular dissection of the steps in the cellular metabolism of reactive oxygen species revealed that the iron‐binding protein ferritin and the H2O2 scavenger catalase are the most potent suppressors of the toxicity of wild‐type and Arctic (E22G) Aβ1–42. Likewise, treatment with the iron‐binding compound clioquinol increased the lifespan of flies expressing Arctic Aβ1–42. The effect of iron appears to be mediated by oxidative stress as ferritin heavy chain co‐expression reduced carbonyl levels in Aβ1–42 flies by 65% and restored the survival and locomotion function to normal. This was achieved despite the presence of elevated levels of the Aβ1–42. Taken together, our data show that oxidative stress, probably mediated by the hydroxyl radical and generated by the Fenton reaction, is essential for Aβ1–42 toxicity in vivo and provide strong support for Alzheimer’s disease therapies based on metal chelation.
The induction of HIF‐1 reduces astrocyte activation by amyloid beta peptide
Authors: Schubert David , Soucek Thomas , Blouw Barbara 
Published: March 2009

AbstractReduced glucose metabolism and astrocyte activation in selective areas of the brain are pathological features of Alzheimer’s disease (AD). The underlying mechanisms of low energy metabolism and a molecular basis for preventing astrocyte activation are not, however, known. Here we show that amyloid beta peptide (Aβ)‐dependent astrocyte activation leads to a long‐term decrease in hypoxia‐inducible factor (HIF)‐1α expression and a reduction in the rate of glycolysis. Glial activation and the glycolytic changes are reversed by the maintenance of HIF‐1α levels with conditions that prevent the proteolysis of HIF‐1α. Aβ increases the long‐term production of reactive oxygen species (ROS) through the activation of nicotinamide adenine dinucleotide phosphate oxidase and reduces the amount of HIF‐1α via the activation of the proteasome. ROS are not required for glial activation, but are required for the reduction in glycolysis. These data suggest a significant role for HIF‐1α‐mediated transcription in maintaining the metabolic integrity of the AD brain and identify the probable cause of the observed lower energy metabolism in afflicted areas. They may also explain the therapeutic success of metal chelators in animal models of AD.
Substrate incorporation patterns of bacterioplankton populations in stratified and mixed waters of a humic lake
Authors: Buck Ulrike , Grossart Hans‐Peter , Amann Rudolf , Pernthaler Jakob 
Published: March 2009

SummaryBacterial incorporation of glucose, leucine, acetate and 4‐hydroxybenzoic acid (HBA) was investigated in an artificially divided humic lake (Grosse Fuchskuhle, Germany). Two basins with contrasting influx of allochthonous organic carbon were sampled during late summer stratification (oxic and anoxic layers) and after autumn mixing. High total and cell‐specific incorporation rates were observed for glucose and HBA in stratified and mixed waters respectively, but only a small fraction of bacteria visibly incorporated HBA. The oxic layer of the more humic‐rich basin featured a significantly lower fraction of glucose incorporating cells and substantially higher proportions of acetate assimilating bacteria. Niche differentiation was observed in two betaproteobacterial populations: cells affiliated with the Polynucleobacter C subcluster efficiently incorporated acetate but little glucose, whereas the opposite was found for members of the R‐BT065 clade. By contrast, leucine incorporation was variable in both taxa. Considering the high concentrations and rapid photochemical generation of organic acids in humic waters our results may help to explain the success of the Polynucleobacter C lineage in such habitats. Specific substrate or habitat preferences were also present in three subgroups of the actinobacterial acI lineage: The numerically dominant clade in oxic waters (acI‐840‐1) was absent in the anoxic zone and did not incorporate acetate. A second group (acI‐840‐2) was found both in the epi‐ and hypolimnion, whereas the third one (acI‐840‐3) only occurred in anoxic waters. Altogether our results suggest a constitutive preference for some substrates versus an adaptive utilization of others in the studied microbial groups.
A randomized clinical trial comparing the effect of basal insulin and inhaled mealtime insulin on glucose variability and oxidative stress
Authors: Siegelaar S. E. , Kulik W. , Van Lenthe H. , Mukherjee R. , Hoekstra J. B. L. , DeVries J. H. 
Published: March 2009

Aim:  To assess the effect of three times daily mealtime inhaled insulin therapy compared with once daily basal insulin glargine therapy on 72‐h glucose profiles, glucose variability and oxidative stress in type 2 diabetes patients.Methods:  In an inpatient crossover study, 40 subjects with type 2 diabetes were randomized to receive 9 days of inhaled insulin three times daily before meals or 9 days of glargine administered in the morning before breakfast in a randomized order. During the last 72 h in each phase, glucose was measured with continuous glucose monitoring. Activation of oxidative stress was measured by determining the 15(S)‐8‐iso‐PGF2α‐secretion in 24‐h urine samples.Results:  Inhaled insulin improved overall and postprandial glucose control significantly better than insulin glargine (p < 0.0001). There was a trend towards a greater reduction in glucose variability (8–9%) in the inhaled group [p = 0.1430 and p = 0.3298 for mean amplitude of glycaemic excursions (MAGEs) and mean of daily differences respectively]. Oxidative stress, estimated by determining the urinary isoprostane excretion (15(S)‐8‐iso‐PGF2α), was equally reduced from baseline by both treatments. No correlation was found between glucose variability and oxidative stress in both groups.Conclusions:  This study showed a mealtime insulin approach to improve glycaemic control more than a basal insulin approach. These findings indicate also that lowering glucose using insulin treatment lowers oxidative stress over time, at least for the study period of 9 days, in type 2 diabetes patients. Contrary to earlier data, we found no correlation between glucose variability (MAGE) and oxidative stress (15(S)‐8‐iso‐PGF2α) in this study.
Adaptive training leads to sustained enhancement of poor working memory in children
Authors: Holmes Joni , Gathercole Susan E. , Dunning Darren L. 
Published: March 2009

Abstract Working memory plays a crucial role in supporting learning, with poor progress in reading and mathematics characterizing children with low memory skills. This study investigated whether these problems can be overcome by a training program designed to boost working memory. Children with low working memory skills were assessed on measures of working memory, IQ and academic attainment before and after training on either adaptive or non‐adaptive versions of the program. Adaptive training that taxed working memory to its limits was associated with substantial and sustained gains in working memory, with age‐appropriate levels achieved by the majority of children. Mathematical ability also improved significantly 6 months following adaptive training. These findings indicate that common impairments in working memory and associated learning difficulties may be overcome with this behavioral treatment.
Predicting Display Visibility Under Dynamically Changing Lighting Conditions
Authors: Aydin Tunç Ozan , Myszkowski Karol , Seidel Hans‐Peter 
Published: March 2009

AbstractDisplay devices, more than ever, are finding their ways into electronic consumer goods as a result of recent trends in providing more functionality and user interaction. Combined with the new developments in display technology towards higher reproducible luminance range, the mobility and variation in capability of display devices are constantly increasing. Consequently, in real life usage it is now very likely that the display emission to be distorted by spatially and temporally varying reflections, and the observer's visual system to be not adapted to the particular display that she is viewing at that moment. The actual perception of the display content cannot be fully understood by only considering steady‐state illumination and adaptation conditions. We propose an objective method for display visibility analysis formulating the problem as a full‐reference image quality assessment problem, where the display emission under “ideal” conditions is used as the reference for real‐life conditions. Our work includes a human visual system model that accounts for maladaptation and temporal recovery of sensitivity. As an example application we integrate our method to a global illumination simulator and analyze the visibility of a car interior display under realistic lighting conditions.
Temporal Glare: Real‐Time Dynamic Simulation of the Scattering in the Human Eye
Authors: Ritschel T. , Ihrke M. , Frisvad J. R. , Coppens J. , Myszkowski K. , Seidel H.‐P. 
Published: March 2009

AbstractGlare is a consequence of light scattered within the human eye when looking at bright light sources. This effect can be exploited for tone mapping since adding glare to the depiction of high‐dynamic range (HDR) imagery on a low‐dynamic range (LDR) medium can dramatically increase perceived contrast. Even though most, if not all, subjects report perceiving glare as a bright pattern that fluctuates in time, up to now it has only been modeled as a static phenomenon. We argue that the temporal properties of glare are a strong means to increase perceived brightness and to produce realistic and attractive renderings of bright light sources. Based on the anatomy of the human eye, we propose a model that enables real‐time simulation of dynamic glare on a GPU. This allows an improved depiction of HDR images on LDR media for interactive applications like games, feature films, or even by adding movement to initially static HDR images. By conducting psychophysical studies, we validate that our method improves perceived brightness and that dynamic glare‐renderings are often perceived as more attractive depending on the chosen scene.
Energy Aware Color Sets
Authors: Chuang Johnson , Weiskopf Daniel , Möller Torsten 
Published: March 2009

AbstractWe present a design technique for colors with the purpose of lowering the energy consumption of the display device. Our approach is based on a screen space variant energy model. The result of our design is a set of distinguishable iso‐lightness colors guided by perceptual principles. We present two variations of our approach. One is based on a set of discrete user‐named (categorical) colors, which are analyzed according to their energy consumption. The second is based on the constrained continuous optimization of color energy in the perceptually uniform CIELAB color space. We quantitatively compare our two approaches with a traditional choice of colors, demonstrating that we typically save approximately 40 percent of the energy. The color sets are applied to examples from the 2D visualization of nominal data and volume rendering of 3D scalar fields.
Hydraulic Erosion Using Smoothed Particle Hydrodynamics
Authors: Krištof P. , Beneš B. , Křivánek J. , Št'ava O. 
Published: March 2009

AbstractThis paper presents a new technique for modification of 3D terrains by hydraulic erosion. It efficiently couples fluid simulation using a Lagrangian approach, namely the Smoothed Particle Hydrodynamics (SPH) method, and a physically‐based erosion model adopted from an Eulerian approach. The eroded sediment is associated with the SPH particles and is advected both implicitly, due to the particle motion, and explicitly, through an additional velocity field, which accounts for the sediment transfer between the particles. We propose a new donor‐acceptor scheme for the explicit advection in SPH. Boundary particles associated to the terrain are used to mediate sediment exchange between the SPH particles and the terrain itself. Our results show that this particle‐based method is efficient for the erosion of dense, large, and sparse fluid. Our implementation provides interactive results for scenes with up to 25,000 particles.
Bidirectional Importance Sampling for Unstructured Direct Illumination
Authors: Wang Rui , Åkerlund Oskar 
Published: March 2009

AbstractRecent research in bidirectional importance sampling has focused primarily on structured illumination sources such as distant environment maps, while unstructured illumination has received little attention. In this paper, we present a method for bidirectional importance sampling of unstructured illumination, allowing us to use the same method for sampling both distant as well as local/indirect sources. Building upon recent work in [WFA*05], we model complex illumination as a large set of point lights. The subsequent sampling process draws samples only from this point set. We start by constructing a piecewise constant approximation for the lighting using an illumination cut [CPWAP08]. We show that this cut can be used directly for illumination importance sampling. We then use BRDF importance sampling followed by sample counting to update the cut, resulting in a bidirectional distribution that closely approximates the product of the illumination and BRDF. Drawing visibility samples from this new distribution significantly reduces the sampling variance. As a main advance over previous work, our method allows for unstructured sources, including arbitrary local direct lighting and one‐bounce of indirect lighting.
Modal Locomotion: Animating Virtual Characters with Natural Vibrations
Authors: Kry P.G. , Reveret L. , Faure F. , Cani M.‐P. 
Published: March 2009

AbstractWe present a general method to intuitively create a wide range of locomotion controllers for 3D legged characters. The key of our approach is the assumption that efficient locomotion can exploit the natural vibration modes of the body, where these modes are related to morphological parameters such as the shape, size, mass, and joint stiffness. The vibration modes are computed for a mechanical model of any 3D character with rigid bones, elastic joints, and additional constraints as desired. A small number of vibration modes can be selected with respect to their relevance to locomotion patterns and combined into a compact controller driven by very few parameters. We show that these controllers can be used in dynamic simulations of simple creatures, and for kinematic animations of more complex creatures of a variety of shapes and sizes.
Character Motion Synthesis by Topology Coordinates
Authors: Ho Edmond S.L. , Komura Taku 
Published: March 2009

AbstractIn this paper, we propose a new method to efficiently synthesize character motions that involve close contacts such as wearing a T‐shirt, passing the arms through the strings of a knapsack, or piggy‐back carrying an injured person. We introduce the concept of topology coordinates, in which the topological relationships of the segments are embedded into the attributes. As a result, the computation for collision avoidance can be greatly reduced for complex motions that require tangling the segments of the body. Our method can be combinedly used with other prevalent frame‐based optimization techniques such as inverse kinematics.
An Analytical Solution to Single Scattering in Homogeneous Participating Media
Authors: Pegoraro Vincent , Parker Steven G. 
Published: March 2009

AbstractDespite their numerous applications, efficiently rendering participating media remains a challenging task due to the intricacy of the radiative transport equation. As they provide a generic means of solving a wide variety of problems, numerical methods are most often used to solve the air‐light integral even under simplifying assumptions. In this paper, we present a novel analytical approach to single scattering from isotropic point light sources in homogeneous media. We derive the first closed‐form solution to the air‐light integral in isotropic media and extend this formulation to anisotropic phase functions. The technique relies neither on pre‐computation nor on storage, and we provide a practical implementation allowing for an explicit control on the accuracy of the solutions. Finally, we demonstrate its quantitative and qualitative benefits over both previous numerical and analytical approaches.
A Statistical Model of Human Pose and Body Shape
Authors: Hasler N. , Stoll C. , Sunkel M. , Rosenhahn B. , Seidel H.‐P. 
Published: March 2009

AbstractGeneration and animation of realistic humans is an essential part of many projects in today's media industry. Especially, the games and special effects industry heavily depend on realistic human animation. In this work a unified model that describes both, human pose and body shape is introduced which allows us to accurately model muscle deformations not only as a function of pose but also dependent on the physique of the subject. Coupled with the model's ability to generate arbitrary human body shapes, it severely simplifies the generation of highly realistic character animations. A learning based approach is trained on approximately 550 full body 3D laser scans taken of 114 subjects. Scan registration is performed using a non‐rigid deformation technique. Then, a rotation invariant encoding of the acquired exemplars permits the computation of a statistical model that simultaneously encodes pose and body shape. Finally, morphing or generating meshes according to several constraints simultaneously can be achieved by training semantically meaningful regressors.
Motion Compression using Principal Geodesics Analysis
Authors: Tournier M. , Wu X. , Courty N. , Arnaud E. , Revéret L. 
Published: March 2009

AbstractDue to the growing need for large quantities of human animation data in the entertainment industry, it has become a necessity to compress motion capture sequences in order to ease their storage and transmission. We present a novel, lossy compression method for human motion data that exploits both temporal and spatial coherence. Given one motion, we first approximate the poses manifold using Principal Geodesics Analysis (PGA) in the configuration space of the skeleton. We then search this approximate manifold for poses matching end‐effectors constraints using an iterative minimization algorithm that allows for real‐time, data‐driven inverse kinematics. The compression is achieved by only storing the approximate manifold parametrization along with the end‐effectors and root joint trajectories, also compressed, in the output data. We recover poses using the IK algorithm given the end‐effectors trajectories. Our experimental results show that considerable compression rates can be obtained using our method, with few reconstruction and perceptual errors.
Fast GPU‐based Adaptive Tessellation with CUDA
Authors: Schwarz Michael , Stamminger Marc 
Published: March 2009

AbstractCompact surface descriptions like higher‐order surfaces are popular representations for both modeling and animation. However, for fast graphics‐hardware‐assisted rendering, they usually need to be converted to triangle meshes. In this paper, we introduce a new framework for performing on‐the‐fly crack‐free adaptive tessellation of surface primitives completely on the GPU. Utilizing CUDA and its flexible memory write capabilities, we parallelize the tessellation task at the level of single surface primitives. We are hence able to derive tessellation factors, perform surface evaluation as well as generate the tessellation topology in real‐time even for large collections of primitives. We demonstrate the power of our framework by exemplarily applying it to both bicubic rational Bézier patches and PN triangles.
Out‐of‐core Data Management for Path Tracing on Hybrid Resources
Authors: Budge Brian , Bernardin Tony , Stuart Jeff A. , Sengupta Shubhabrata , Joy Kenneth I. , Owens John D. 
Published: March 2009

AbstractWe present a software system that enables path‐traced rendering of complex scenes. The system consists of two primary components: an application layer that implements the basic rendering algorithm, and an out‐of‐core scheduling and data‐management layer designed to assist the application layer in exploiting hybrid computational resources (e.g., CPUs and GPUs) simultaneously. We describe the basic system architecture, discuss design decisions of the system's data‐management layer, and outline an efficient implementation of a path tracer application, where GPUs perform functions such as ray tracing, shadow tracing, importance‐driven light sampling, and surface shading. The use of GPUs speeds up the runtime of these components by factors ranging from two to twenty, resulting in a substantial overall increase in rendering speed. The path tracer scales well with respect to CPUs, GPUs and memory per node as well as scaling with the number of nodes. The result is a system that can render large complex scenes with strong performance and scalability.