bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetically‐based trade‐offs in response to stoichiometric food quality influence competition in a keystone aquatic herbivore
Authors: Jeyasingh Punidan D. , Weider Lawrence J. , Sterner Robert W. 
Published: August 2009

AbstractThe genetic basis of organism response to stoichiometric mismatches between environmental availability and somatic demand is still poorly understood. This study reports a consistent genotype × environment interaction related to phosphorus : carbon availability to Daphnia. In multiple pairs of Daphnia pulicaria clones, genetic variation at the phosphoglucose isomerase (Pgi) locus indicated that Pgi‐heterozygotes out competed Pgi‐homozygotes under high P : C conditions, whereas the opposite outcome was observed under low P : C conditions. Estimates of phosphorus use efficiency indicated that homozygotes were significantly more efficient. However, homozygotes were comparatively less homeostatic. We hypothesize that lower specific activity of Pgi from homozygotes, which results in lowered energetic efficiency during the second glycolytic step, may underlie the competitive advantage enjoyed by homozygotes under low P : C (i.e. excess C) conditions. Our results show that analysing stoichiometric mismatches between diet and consumer should advance our quest for a fundamental understanding of the mechanisms driving genotype‐environment interactions.
Seed arrival, ecological filters, and plant species richness: a meta‐analysis
Authors: Myers Jonathan A. , Harms Kyle E. 
Published: September 2009

AbstractTheoretical models predict that effects of dispersal on local biodiversity are influenced by the size and composition of the species pool, as well as ecological filters that limit local species membership. We tested these predictions by conducting a meta‐analysis of 28 studies encompassing 62 experiments examining effects of propagule supply (seed arrival) on plant species richness under contrasting intensities of ecological filters (owing to disturbance and resource availability). Seed arrival increased local species richness in a wide range of communities (forest, grassland, montane, savanna, wetland), resulting in a positive mean effect size across experiments. Mean effect size was 70% higher in disturbed relative to undisturbed communities, suggesting that disturbance increases recruitment opportunities for immigrating species. In contrast, effect size was not significantly influenced by nutrient or water availability. Among seed‐addition experiments, effect size was positively correlated with species and functional diversity within the pool of added seeds (species evenness and seed‐size diversity), primarily in disturbed communities. Our analysis provides experimental support for the general hypothesis that species pools and local environmental heterogeneity interactively structure plant communities. We highlight empirical gaps that can be addressed by future experiments and discuss implications for community assembly, species coexistence, and the maintenance of biodiversity.
Dispersal and natural enemies interact to drive spatial synchrony and decrease stability in patchy populations
Authors: Vogwill Tom , Fenton Andy , Brockhurst Michael A. 
Published: August 2009

AbstractSpatial synchrony is widespread in natural populations but the mechanisms that underpin it are not yet fully understood. Two key biotic drivers of spatial synchrony have been identified: dispersal and trophic interactions (e.g. natural enemies). We used spatially structured, patchy bacterial populations to show that although increased dispersal always enhanced spatial synchrony of fluctuations in bacterial abundance, this effect was far stronger in the presence of a bacteriophage parasite. Bacteriophages drove strong within patch fluctuations in bacterial abundance that became phase locked through dispersal. Furthermore, the way in which stability, measured as constancy, responded to increasing dispersal was qualitatively different depending on whether parasites were present or not. Patch‐level constancy decreased with dispersal in the presence of parasites, whereas dispersal increased patch‐level constancy in the absence of parasites. Population‐level constancy also decreased with dispersal in the presence of parasites, but was unaffected by dispersal in the absence of parasites. These contrasting patterns were likely due to the different role played by dispersal in the presence and absence of parasites, synchronizing dynamics in the former case and averaging stochastic fluctuations in the latter. Taken together, our findings suggest that dispersal and natural enemies can interact to drive spatially synchronous population fluctuations that decrease stability at both the patch and population level.
Ultrastructural changes in skeletal muscle of the tail of the lizardHemidactylus mabouiaimmediately following autotomy
Authors: Araújo Tomaz Henrique , Faria Flavio Pavla de , Katchburian Eduardo , Haapalainen Edna Freymüller 
Published: August 2009

AbstractAraújo, T.H., Faria, F.P., Katchburian, E. and Freymüller, E. (2009). Ultrastructural changes in skeletal muscle of the tail of the lizardHemidactylus mabouiaimmediately following autotomy. —Acta Zoologica(Stockholm)91: 440–446.Although autotomy and subsequent regeneration of lizard tails has been extensively studied, there is little information available on ultrastructural changes that occur to the muscle fibers at the site of severance. Thus, in the present study, we examine the ultrastructure of the musculature of the remaining tail stump of the lizardHemidactylus mabouiaimmediately after autotomy. Our results show that exposed portions of the skeletal muscle fibers of the stump that are unprotected by connective tissue bulge to produce large mushroom‐like protrusions. These exposed portions show abnormal structure but suffer no leakage of cytoplasmic contents. Many small and large vesicular structures appeared between myofibrils in the interface at this disarranged region (distal) and the other portion of the fibers that remain unchanged (proximal). These vesicles coalesce, creating a gap that leads to the release of the mushroom‐like protrusion. So, our results showed that after the macroscopic act of autotomy the muscular fibers release part of the sarcoplasm as if a second and microscopic set of autotomic events takes place immediately following the macroscopic act of autotomy. Presumably these changes pave the way for the formation of a blastema and the beginning of regeneration.
Spermatogenesis in Boccardiella hamata (Polychaeta: Spionidae) from the Sea of Japan: sperm formation mechanisms as characteristics for future taxonomic revision
Authors: Reunov Arkadiy A. , Yurchenko Olga V. , Alexandrova Yana N. , Radashevsky Vasily I. 
Published: August 2009

AbstractReunov, A.A., Yurchenko, O.V., Alexandrova, Y.N. and Radashevsky, V.I. 2009. Spermatogenesis in Boccardiella hamata (Polychaeta: Spionidae) from the Sea of Japan: sperm formation mechanisms as characteristics for future taxonomic revision. —Acta Zoologica (Stockholm) 91: 477–456.To characterize novel features that will be useful in the discussion and validation of the spionid polychaete Boccardiella hamata from the Sea of Japan, the successive stages of spermatogenesis were described and illustrated. Spermatogonia, spermatocytes and early spermatids are aflagellar cells that develop synchronously in clusters united by a cytophore. At the middle spermatid stage, the clusters undergo disintegration and spermatids produce flagella and float separately in coelomic fluid as they transform into sperm. Spermatozoa are filiform. The ring‐shaped storage platelets are located along the anterior nuclear area. The nucleus is cupped by a conical acrosome. A nuclear plate is present between the acrosome and nucleus. The nucleus is a cylinder with the implantation fossa throughout its length and with the anterior part of the flagellum inside the fossa. There is only one centriole, serving as a basal body of the flagellum, situated in close vicinity of the acrosomal area. A collar of four mitochondria is located under the nuclear base. The ultrastructure of B. hamata spermatozoa from the Sea of Japan appears to be close to that of B. hamata from Florida described by Rice (Microscopic Anatomy of Invertebrates, Wiley‐Liss, Inc., New York, 1992), suggesting species identity of the samples from the two regions. However, more detailed study of Florida’s B. hamata sperm is required for a reliable conclusion concerning the similarity of these two polychaetes. In addition to sperm structure, features such as the cytophore‐assigned pattern of spermatogenic cell development, the synchronous pattern of cell divisions, the non‐flagellate early spermatogenic stages, and the vesicle amalgamation that drives meiotic cell cytokinesis and spermatid diorthosis will likely be useful in future testing of the validity of B. hamata and sibling species throughout the world.
Clinical experience in a modified Roux‐Y‐ shaped sigmoid neobladder: assessment of complications and voiding patterns in 43 patients
Authors: Liu DingYi , Feng Feng , Shen ZhouJun , Xia WeiMu , Zhou WenLong , Wang MingWei , Zhu Yu , Wang Jian , Tang Qi 
Published: August 2009

Study Type – Therapy (case series)Level of Evidence 4OBJECTIVETo evaluate the complications and urinary voiding patterns in patients with a new Roux‐Y‐shaped continent neobladder, using a modified sigmoid pouch.PATIENTS AND METHODSBetween June 2003 and July 2008, 43 patients (26 men and 17 women, mean age 69.5 years) underwent a modified Roux‐Y‐shaped sigmoid continent neobladder reconstruction after radical cystectomy. The surgical procedures involved the construction of a Roux‐Y‐shaped sigmoid pouch, making an antifeces‐refluxing valve into the sigmoid urine reservoir and ureterosigmoidostomy using the Leadbetter method. This pouch method has not been described before. The patients’ clinical, biochemical, radiological and urodynamic variables were assessed.RESULTSDuring the mean (range) follow‐up of 24 (6–65) months, there were no deaths related to the procedure. In 16% of the patients, early complications occurred, whereas 12% had late complications. There were no cases with local recurrence and metastasis. Routine electrolyte evaluation revealed a slight metabolic acidosis in six patients (14%). Hypovitaminosis B12 did not occur in any patients. All patients were continent in the daytime and night‐time continence was poor in eight patients (19%). The mean (sd, range) neobladder capacity and residual urine volume was 330 (110, 120–410) mL and 48 (26, 25–80) mL, respectively. Moreover, the maximum urinary flow rate was 9.2–25.3 mL/s.CONCLUSIONThe modified Roux‐Y‐shaped sigmoid neobladder replacement provides a new simple surgical procedure with low complication rates. The procedure offers comparatively satisfactory daytime continence with low postvoid residual urine volumes and voiding patterns. This technique is a valid alternative to continent urinary diversion.
Fast, Exact, Linear Booleans
Authors: Bernstein Gilbert , Fussell Don 
Published: August 2009

AbstractWe present a new system for robustly performing Boolean operations on linear, 3D polyhedra. Our system is exact, meaning that all internal numeric predicates are exactly decided in the sense of exact geometric computation. Our BSP‐tree based system is 16‐28× faster at performing iterative computations than CGAL's Nef Polyhedra based system, the current best practice in robust Boolean operations, while being only twice as slow as the non‐robust modeler Maya. Meanwhile, we achieve a much smaller substrate of geometric subroutines than previous work, comprised of only 4 predicates, a convex polygon constructor, and a convex polygon splitting routine. The use of a BSP‐tree based Boolean algorithm atop this substrate allows us to explicitly handle all geometric degeneracies without treating a large number of cases.
Interior Distance Using Barycentric Coordinates
Authors: Rustamov R. M. , Lipman Y. , Funkhouser T. 
Published: August 2009

AbstractThis paper introduces a framework for defining a shape‐aware distance measure between any two points in the interior of a surface mesh. Our framework is based on embedding the surface mesh into a high‐dimensional space in a way that best preserves boundary distances between vertices of the mesh, performing a mapping of the mesh volume into this high‐dimensional space using barycentric coordinates, and defining the interior distance between any two points simply as their Euclidean distance in the embedding space. We investigate the theoretical properties of the interior distance in relation to properties of the chosen boundary distances and barycentric coordinates, and we investigate empirical properties of the interior distance using diffusion distance as the prescribed boundary distance and mean value coordinates. We prove theoretically that the interior distance is a metric, smooth, interpolating the boundary distances, and reproducing Euclidean distances, and we show empirically that it is insensitive to boundary noise and deformation and quick to compute. In case the barycentric coordinates are non‐negative we also show a maximum principle exists. Finally, we use it to define a new geometric property, barycentroid of shape, and show that it captures the notion of semantic center of the shape.
Diamond Hierarchies of Arbitrary Dimension
Authors: Weiss Kenneth , De Floriani Leila 
Published: August 2009

AbstractNested simplicial meshes generated by the simplicial bisection decomposition proposed by Maubach [Mau95] have been widely used in 2D and 3D as multi‐resolution models of terrains and three‐dimensional scalar fields, They are an alternative to octree representation since they allow generating crack‐free representations of the underlying field. On the other hand, this method generates conforming meshes only when all simplices sharing the bisection edge are subdivided concurrently. Thus, efficient representations have been proposed in 2D and 3D based on a clustering of the simplices sharing a common longest edge in what is called a diamond. These representations exploit the regularity of the vertex distribution and the diamond structure to yield an implicit encoding of the hierarchical and geometric relationships among the triangles and tetrahedra, respectively. Here, we analyze properties ofd‐dimensional diamonds to better understand the hierarchical and geometric relationships among the simplices generated by Maubach's bisection scheme and derive closed‐form equations for the number of vertices, simplices, parents and children of each type of diamond. We exploit these properties to yield an implicit pointerless representation ford‐dimensional diamonds and reduce the number of required neighbor‐finding accesses fromO(d!) toO(d).
Progressive Lossless Mesh Compression Via Incremental Parametric Refinement
Authors: Valette Sébastien , Chaine Raphaëlle , Prost Rémy 
Published: August 2009

AbstractIn this paper, we propose a novel progressive lossless mesh compression algorithm based on Incremental Parametric Refinement, where the connectivity is uncontrolled in a first step, yielding visually pleasing meshes at each resolution level while saving connectivity information compared to previous approaches. The algorithm starts with a coarse version of the original mesh, which is further refined by means of a novel refinement scheme. The mesh refinement is driven by a geometric criterion, in spirit with surface reconstruction algorithms, aiming at generating uniform meshes. The vertices coordinates are also quantized and transmitted in a progressive way, following a geometric criterion, efficiently allocating the bit budget. With this assumption, the generated intermediate meshes tend to exhibit a uniform sampling. The potential discrepancy between the resulting connectivity and the original one is corrected at the end of the algorithm. We provide a proof‐of‐concept implementation, yielding very competitive results compared to previous works in terms of rate/distortion trade‐off.
Random Accessible Hierarchical Mesh Compression for Interactive Visualization
Authors: Courbet Clement , Hudelot Celine 
Published: August 2009

AbstractThis paper presents a novel algorithm for hierarchical random accessible mesh decompression. Our approach progressively decompresses the requested parts of a mesh without decoding less interesting parts. Previous approaches divided a mesh into independently compressed charts and a base coarse mesh. We propose a novel hierarchical representation of the mesh. We build this representation by using a boundary‐based approach to recursively split the mesh in two parts, under the constraint that any of the two resulting submeshes should be reconstructible independently.In addition to this decomposition technique, we introduce the concepts of opposite vertex and context dependant numbering. This enables us to achieve seemingly better compression ratios than previous work on quad and higher degree polygonal meshes. Our coder uses about 3 bits per polygon for connectivity and 14 bits per vertex for geometry using 12 bits quantification.
Reconstruction of Multi‐Label Domains from Partial Planar Cross‐Sections
Authors: Barequet Gill , Vaxman Amir 
Published: August 2009

AbstractWe present a novel algorithm for reconstructing a subdivision of the three‐dimensional space (given arbitrarily‐oriented slices of it) into labeled domains. The input to the algorithm is a collection of nonparallel planar cross‐sections of an unknown object, where the sections might cover only portions of the supporting planes. (The information in the rest of these planes is, thus, “unknown.”) Each cross‐section consists of a partition of the plane into closed labeled (“colored”) domains with no restrictions whatsoever on either their geometries or topologies, and without any assumptions about similarities between partitions of different sections. The problem is to reconstruct the original three‐dimensional partition by interpolating simultaneously all the cross‐sections, so that planar domains in the input are connected only to other domains of the same color, no two reconstructed spatial domains intersect, and no unnecessary gaps remain between the reconstructed colored domains.The problem of reconstructing multiple‐labeled domains arises, for example, in medical imaging, where different types of tissues are scanned and reconstructed at the same time. Partial slices are typical, for example, in ultrasound scanning. In this work we use the three‐dimensional straight‐skeleton of the arrangement of the cross‐sections. Since the sections might be partial, cells of the arrangement might be nonconvex. For this we use the unambiguous definition, as well as the implementation of the computation, of the straight skeleton of a three‐dimensional polyhedron that we presented in a recent work [BEGV08]. First, we define these cells and compute their skeleton. Second, we compute overlays of portions of sampled contours in the cross‐sections, using the cell skeletons to guide the reconstruction of the mesh.
Recovering Structure from r‐Sampled Objects
Authors: Aichholzer O. , Aurenhammer F. , Kornberger B. , Plantinga S. , Rote G. , Sturm A. , Vegter G. 
Published: August 2009

AbstractFor a surface in 3‐space that is represented by a set S of sample points, we construct a coarse approximating polytope P that uses a subset of S as its vertices and preserves the topology of . In contrast to surface reconstruction we do not use all the sample points, but we try to use as few points as possible. Such a polytope P is useful as a ‘seed polytope’ for starting an incremental refinement procedure to generate better and better approximations of based on interpolating subdivision surfaces or e.g. Bézier patches.Our algorithm starts from an r‐sample S of . Based on S, a set of surface covering balls with maximal radii is calculated such that the topology is retained. From the weighted α‐shape of a proper subset of these highly overlapping surface balls we get the desired polytope. As there is a rather large range for the possible radii for the surface balls, the method can be used to construct triangular surfaces from point clouds in a scalable manner. We also briefly sketch how to combine parts of our algorithm with existing medial axis algorithms for balls, in order to compute stable medial axis approximations with scalable level of detail.
Manifold Homotopy via the Flow Complex
Authors: Sadri Bardia 
Published: August 2009

AbstractIt is known that the critical points of the distance function induced by a dense sample P of a submanifold Σ of ℝnare distributed into two groups, one lying close to Σ itself, called theshallow, and the other close to medial axis of Σ, called deep critical points. We prove that under (uniform) sampling assumption, the union of stable manifolds of the shallow critical points have the same homotopy type as Σ itself and the union of the stable manifolds of the deep critical points have the homotopy type of the complement of Σ. The separation of critical points under uniform sampling entails a separation in terms of distance of critical points to the sample. This means that if a given sample is dense enough with respect to two or more submanifolds of ℝn, the homotopy types of all such submanifolds together with those of their complements are captured as unions of stable manifolds of shallow versus those of deep critical points, in a filtration of the flow complex based on the distance of critical points to the sample. This results in an algorithm for homotopic manifold reconstruction when the target dimension is unknown.
Isotopic Reconstruction of Surfaces with Boundaries
Authors: Dey Tamal K. , Li Kuiyu , Ramos Edgar A. , Wenger Rephael 
Published: August 2009

AbstractWe present an algorithm for the reconstruction of a surface with boundaries (including a non‐orientable one) in three dimensions from a sufficiently dense sample. It is guaranteed that the output is isotopic to the unknown sampled surface. No previously known algorithm guarantees isotopic or homeomorphic reconstruction of surfaces with boundaries. Our algorithm is surprisingly simple. It ‘peels’ slivers greedily from an α‐complex of a sample of the surface. No other post‐processing is necessary. We provide several experimental results from an implementation of our basic algorithm and also a modified version of it.
Gromov‐Hausdorff Stable Signatures for Shapes using Persistence
Authors: Chazal Frédéric , Cohen‐Steiner David , Guibas Leonidas J. , Mémoli Facundo , Oudot Steve Y. 
Published: August 2009

AbstractWe introduce a family of signatures for finite metric spaces, possibly endowed with real valued functions, based on the persistence diagrams of suitable filtrations built on top of these spaces. We prove the stability of our signatures under Gromov‐Hausdorff perturbations of the spaces. We also extend these results to metric spaces equipped with measures. Our signatures are well‐suited for the study of unstructured point cloud data, which we illustrate through an application in shape classification.