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Selected AbstractsA Local/Global Approach to Mesh ParameterizationCOMPUTER GRAPHICS FORUM, Issue 5 2008Ligang Liu Abstract We present a novel approach to parameterize a mesh with disk topology to the plane in a shape-preserving manner. Our key contribution is a local/global algorithm, which combines a local mapping of each 3D triangle to the plane, using transformations taken from a restricted set, with a global "stitch" operation of all triangles, involving a sparse linear system. The local transformations can be taken from a variety of families, e.g. similarities or rotations, generating different types of parameterizations. In the first case, the parameterization tries to force each 2D triangle to be an as-similar-as-possible version of its 3D counterpart. This is shown to yield results identical to those of the LSCM algorithm. In the second case, the parameterization tries to force each 2D triangle to be an as-rigid-as-possible version of its 3D counterpart. This approach preserves shape as much as possible. It is simple, effective, and fast, due to pre-factoring of the linear system involved in the global phase. Experimental results show that our approach provides almost isometric parameterizations and obtains more shape-preserving results than other state-of-the-art approaches. We present also a more general "hybrid" parameterization model which provides a continuous spectrum of possibilities, controlled by a single parameter. The two cases described above lie at the two ends of the spectrum. We generalize our local/global algorithm to compute these parameterizations. The local phase may also be accelerated by parallelizing the independent computations per triangle. [source] Functional redundancy in heterogeneous environments: implications for conservationECOLOGY LETTERS, Issue 3 2001Todd Wellnitz It has been argued that one of the best ways to conserve biological diversity is to maintain the integrity of functional processes within communities, and this can be accomplished by assessing how much ecological redundancy exists in communities. Evidence suggests, however, that the functional roles species play are subject to the influences of local environmental conditions. Species may appear to perform the same function (i.e. be redundant) under a restricted set of conditions, yet their functional roles may vary in naturally heterogeneous environments. Incorporating the environmental context into ecological experiments would provide a critical perspective for examining functional redundancy among species. [source] Converting Core Compounds into Building Blocks: The Concept of Regiochemically Exhaustive FunctionalizationEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2005Elena Marzi Abstract In a model study, 3-fluorophenol and 3-fluoropyridine were converted into the each time four possible carboxylic acids by passing through the corresponding organometallic intermediates. As an attempt to generalize the findings reveals, a restricted set of principles and methods suffices to cope with all standard scenarios. The most valuable and versatile tools for the regiochemically exhaustive functionalization of a great variety of substrate patterns are the optionally site-selective metalation (either by reagent/substrate matching or by peripheral coordination control), the use of activating or congesting protective groups and the basicity gradient-driven heavy halogen migration (followed by halogen/metal permutation). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Spurious correlations between recent warming and indices of local economic activity,INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 14 2009Gavin A. Schmidt Abstract A series of climate model simulations of the 20th Century are analysed to investigate a number of published correlations between indices of local economic activity and recent global warming. These correlations have been used to support a hypothesis that the observed surface warming record has been contaminated in some way and thus overestimates true global warming. However, the basis of the results are correlations over a very restricted set of locations (predominantly western Europe, Japan and the USA) which project strongly onto naturally occurring patterns of climate variability, or are with fields with significant amounts of spatial auto-correlation. Across model simulations, the correlations vary widely due to the chaotic weather component in any short-term record. The reported correlations do not fall outside the simulated distribution, and are probably spurious (i.e. are likely to have arisen from chance alone). Thus, though this study cannot prove that the global temperature record is unbiased, there is no compelling evidence from these correlations of any large-scale contamination. Copyright © 2009 Royal Meteorological Society [source] Deterring illegal downloading: the effects of threat appeals, past behavior, subjective norms, and attributions of harm,JOURNAL OF CONSUMER BEHAVIOUR, Issue 2-3 2007Aron M. Levin The study employs two experiments to examine the effectiveness of various strategies used to dissuade consumers from downloading music illegally. The research investigates two specific strategies that the recording industry has used: (1) fear or threat appeals (e.g., the threat of punishment, such as fines and/or jail time), and (2) attribution of harm (informing consumers of the harm caused by the illegal downloading of music, such as financial loss to either the artist or the recording company). The study also considers whether past illegal downloading behavior reduces the effectiveness of these disincentive strategies. Finally, the impact of subjective norms (i.e., whether subjects think their friends would approve of downloading music) was also investigated. A 3 (level of threat: low, moderate, or high) X 2 (who is harmed by illegal downloading: artist or recording company) experimental design was employed for study one. Undergraduate students (n,=,388) participated in the study. Study two expanded on the design of the first study by adding a variable of subjective norms and by including previous downloading behavior in the model. Undergraduate students (n,=,211) also participated in the second experiment. Findings indicate a significant effect of threat appeal such that stronger threat appeals were found to be more effective than weaker threat appeals in reducing illegal downloading. The first study also showed that prior illegal downloading behavior does not curtail the effects of threat appeals aimed at reducing illegal downloading. In addition, results reveal no differences in downloading behavior in terms of attribution of harm deterrent strategy (harm to either the recording artist or company). The most interesting finding from the second study is that subjective norms appear to equalize low versus high past downloaders, but only under conditions of weak fear. The current manuscript is the first to examine the impact of four different variables (threat appeals, attribution of harm, subjective norms, and previous downloading behavior) on subjects' likelihood to illegally download music in the future. In particular, this research illuminates the potential importance of social norms in discouraging a type of undesirable consumer behavior but shows that this occurs only under a restricted set of conditions: when threat is low and the consumer is not a habitually high downloader. It should be of interest to those in fields where intellectual property can be pirated on the Internet. Copyright © 2007 John Wiley & Sons, Ltd. [source] Matrix Representation of Polymer Chain Size Distributions, 2,MACROMOLECULAR THEORY AND SIMULATIONS, Issue 2 2007Fundamental Analysis of Linear Polymerization Mechanisms at Transient Conditions Abstract Analysis of the mass balance equations that describe a reaction system may be useful to provide information about its dynamics, such as the restricted set of compositions that can be achieved from a given set of initial compositions and the effect of feeding reactants to the reaction environment along the reaction course. Since these results may be important for the formulation of reaction policies, this work presents the properties of a matrix polymerization model previously developed and extended to describe transient conditions. This model is based on the definitions of two matrices: the consumption matrix (A,,,Kt), which contains information about chemical transformations among the many active polymer species in the system, and the propagation matrix Kp, which contains information about chain growth. It is shown that the set of mass balance equations that describes the dynamics of active chemical species in polymerization reactions has a stable and unique solution, which is bounded if feed rates are also bounded. It is also shown that the set of compositions that may be reached through manipulation of the feed rates is restricted and may not include all possible chemical compositions. Finally, it is shown that the obtained molecular weight distributions are special multiple time convolutions of the initiation rates. [source] A high-throughput protocol for extracting high-purity genomic DNA from plants and animalsMOLECULAR ECOLOGY RESOURCES, Issue 4 2008R. WHITLOCK Abstract DNA extraction techniques that employ the reversible binding of DNA to silica via chaotropic salts can deliver high-quality genomic DNA from plant and animal tissues, while avoiding the use of toxic organic solvents. Existing techniques that use this method are either prohibitively expensive, or are applicable to only a restricted set of taxa. Here we describe a cost-effective DNA extraction technique suitable for a wide range of plant and animal taxa that yields microgram quantities of high-molecular-weight genomic DNA at a throughput of 192 samples per day. Our technique is particularly robust for tissue samples that are insoluble or are rapidly discoloured or oxidized in standard DNA extraction buffers. We demonstrate the quality of DNA extracted using this method by applying the amplified fragment length polymorphism technique to plant species. [source] Calpain 11 is unique to mouse spermatogenic cells,MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 6 2006Irit Ben-Aharon Abstract The calpains are a family of calcium-dependent thiol proteases involved in intracellular processing of proteins. They occur as heterodimers containing one of various large subunits and a common small subunit. Some of the large subunits are expressed ubiquitously and others are expressed in a restricted set of tissues. We have cloned the cDNA for mouse calpain 11 and demonstrated that it is expressed specifically in the mouse testis. The mRNA begins to accumulate in the testis between days 14 and 16 after birth, corresponding to the period of pachytene spermatocyte development. The protein is detected by day 18 after birth, during mid to late pachytene spermatocyte development, and is present in the acrosomal region of spermatozoa from the cauda epididymis. The expression of calpain 11 during spermatogenesis and its localization in spermatozoa suggest that it is involved in regulating calcium-dependent signal transduction events during meiosis and sperm functional processes. Mol. Reprod. Dev. Published 2006 Wiley-Liss, Inc. [source] | ||||||||||