@inproceedings{4055, abstract = {It is shown that a triangulation of a set of n points in the plane that minimizes the maximum edge length can be computed in time O(n2). The algorithm is reasonably easy to implement and is based on the theorem that there is a triangulation with minmax edge length that contains the relative neighborhood graph of the points as a subgraph. With minor modifications the algorithm works for arbitrary normed metrics.}, author = {Edelsbrunner, Herbert and Tan, Tiow}, booktitle = {32nd Annual Symposium of Foundations of Computer Science}, location = {San Juan, PR, United States of America}, pages = {414 -- 423}, publisher = {IEEE}, title = {{A quadratic time algorithm for the minmax length triangulation}}, doi = {10.1109/SFCS.1991.185400}, year = {1991}, } @article{4056, abstract = {This paper proves that for every n ≥ 4 there is a convex n-gon such that the vertices of 2n - 7 vertex pairs are one unit of distance apart. This improves the previously best lower bound of ⌊ (5n - 5) 3⌋ given by Erdo{combining double acute accent}s and Moser if n ≥ 17.}, author = {Edelsbrunner, Herbert and Hajnal, Péter}, issn = {1096-0899}, journal = {Journal of Combinatorial Theory Series A}, number = {2}, pages = {312 -- 316}, publisher = {Elsevier}, title = {{A lower bound on the number of unit distances between the vertices of a convex polygon}}, doi = {10.1016/0097-3165(91)90042-F}, volume = {56}, year = {1991}, } @article{4057, author = {Edelsbrunner, Herbert}, issn = {1090-2724}, journal = {Journal of Computer and System Sciences}, number = {2}, pages = {249 -- 251}, publisher = {Elsevier}, title = {{Corrigendum}}, doi = {10.1016/0022-0000(91)90013-U}, volume = {42}, year = {1991}, } @inproceedings{4058, abstract = {We present a randomized incremental algorithm for computing a single face in an arrangement of n line segments in the plane that is fairly simple to implement. The expected running time of the algorithm is O (nα(n) log n). The analysis of the algorithm uses a novel approach that generalizes and extends the Clarkson-Shor analysis technique.}, author = {Chazelle, Bernard and Edelsbrunner, Herbert and Guibas, Leonidas and Sharir, Micha and Snoeyink, Jack}, booktitle = {Proceedings of the 2nd annual ACM-SIAM symposium on Discrete algorithms}, isbn = {978-0-89791-376-8}, location = {San Francisco, CA, United States of America}, pages = {441 -- 448}, publisher = {SIAM}, title = {{Computing a face in an arrangement of line segments}}, year = {1991}, } @inproceedings{4059, abstract = {Let P be a simple polygon with n vertices. We present a simple decomposition scheme that partitions the interior of P into O(n) so-called geodesic triangles, so that any line segment interior to P crosses at most 2 log n of these triangles. This decomposition can be used to preprocess P in time O(n log n) and storage O(n), so that any ray-shooting query can be answered in time O(log n).The algorithms are fairly simple and easy to implement. We also extend this technique to the case of ray-shooting amidst k polygonal obstacles with a total of n edges, so that a query can be answered in O(radicklog n) time.}, author = {Chazelle, Bernard and Edelsbrunner, Herbert and Grigni, Michelangelo and Guibas, Leonidas and Hershberger, John and Sharir, Micha and Snoeyink, Jack}, booktitle = {18th International Colloquium on Automata, Languages and Programming}, location = {Madrid, Spain}, pages = {661 -- 673}, publisher = {Springer}, title = {{Ray shooting in polygons using geodesic triangulations}}, doi = {10.1007/3-540-54233-7_172}, volume = {510}, year = {1991}, } @article{4061, abstract = {We present an algorithm to compute a Euclidean minimum spanning tree of a given set S of N points in Ed in time O(Fd (N,N) logd N), where Fd (n,m) is the time required to compute a bichromatic closest pair among n red and m green points in Ed . If Fd (N,N)=Ω(N1+ε), for some fixed e{open}>0, then the running time improves to O(Fd (N,N)). Furthermore, we describe a randomized algorithm to compute a bichromatic closest pair in expected time O((nm log n log m)2/3+m log2 n+n log2 m) in E3, which yields an O(N4/3 log4/3 N) expected time, algorithm for computing a Euclidean minimum spanning tree of N points in E3. In d≥4 dimensions we obtain expected time O((nm)1-1/([d/2]+1)+ε+m log n+n log m) for the bichromatic closest pair problem and O(N2-2/([d/2]+1)ε) for the Euclidean minimum spanning tree problem, for any positive e{open}.}, author = {Agarwal, Pankaj and Edelsbrunner, Herbert and Schwarzkopf, Otfried and Welzl, Emo}, issn = {1432-0444}, journal = {Discrete & Computational Geometry}, number = {1}, pages = {407 -- 422}, publisher = {Springer}, title = {{Euclidean minimum spanning trees and bichromatic closest pairs}}, doi = {10.1007/BF02574698}, volume = {6}, year = {1991}, } @article{4062, abstract = {We prove that for any set S of n points in the plane and n3-α triangles spanned by the points in S there exists a point (not necessarily in S) contained in at least n3-3α/(c log5 n) of the triangles. This implies that any set of n points in three-dimensional space defines at most {Mathematical expression} halving planes.}, author = {Aronov, Boris and Chazelle, Bernard and Edelsbrunner, Herbert and Guibas, Leonidas and Sharir, Micha and Wenger, Rephael}, issn = {1432-0444}, journal = {Discrete & Computational Geometry}, number = {1}, pages = {435 -- 442}, publisher = {Springer}, title = {{Points and triangles in the plane and halving planes in space}}, doi = {10.1007/BF02574700}, volume = {6}, year = {1991}, } @inproceedings{4508, abstract = {We extend the specification language of temporal logic, the corresponding verification framework, and the underlying computational model to deal with real-time properties of concurrent and reactive systems. A global, discrete, and asynchronous clock is incorporated into the model by defining the abstract notion of a real-time transition system as a conservative extension of traditional transition systems: qualitative fairness requirements are replaced (and superseded) by quantitative lower-bound and upperbound real-time requirements for transitions. We show how to model real-time systems that communicate either through shared variables or by message passing, and how to represent the important real-time constructs of priorities (interrupts), scheduling, and timeouts in this framework. Two styles for the specification of real-time properties are presented. The first style uses bounded versions of the temporal operators; the real-time requirements expressed in this style are classified ...}, author = {Henzinger, Thomas A and Manna, Zohar and Pnueli, Amir}, booktitle = {Proceedings of the 18th ACM SIGPLAN-SIGACT symposium on Principles of programming languages}, isbn = {978-0-89791-419-2}, location = {Orlando, FL, United States of America}, pages = {353 -- 366}, publisher = {ACM}, title = {{Temporal proof methodologies for real-time systems}}, doi = {10.1145/99583.99629}, year = {1991}, } @phdthesis{4516, abstract = {We extend the specification language of temporal logic, the corresponding verification framework, and the underlying computational model to deal with real-time properties of reactive systems. Semantics We introduce the abstract computational model of timed transition systems as a conservative extension of traditional transition systems qualitative fairness requirements are superseded by quantitative real-time constraints on the transitions. Digital clocks are introduced as observers of continuous real-time behavior. We justify our semantical abstractions by demonstrating that a wide variety of concrete real-time systems can be modeled adequately. Specification We present two conservative extensions of temporal logic that allow for the specification of timing constraints while timed temporal logic provides access to time through a novel kind of time quantifier, metric temporal logic refers to time through time-bounded versions of the temporal operators. We justify our choice of specification languages by developing a general framework for the classification of real-time logics according to their complexity and expressive power. Verification We develop tools for determining if a real-time system that is modeled as a timed transition system meets a specification that is given in timed temporal logic or in metric temporal logic. We present both model-checking algorithms for the automatic verification of finite-state real-time systems and proof methods for the deductive verification of real-time systems.}, author = {Henzinger, Thomas A}, pages = {295}, publisher = {Stanford University}, title = {{The temporal specification and verification of real-time systems }}, year = {1991}, } @article{4592, author = {Alur, Rajeev and Henzinger, Thomas A}, issn = {0163-5700}, journal = {SIGACT News}, number = {3}, pages = {6 -- 12}, publisher = {ACM}, title = {{Time for logic}}, volume = {22}, year = {1991}, } @inproceedings{4621, abstract = {The most natural, compositional, way of modeling real-time systems uses a dense domain for time. The satisfiability of timing constraints that are capable of expressing punctuality in this model, however, is known to be undecidable. We introduce a temporal language that can constrain the time difference between events only with finite, yet arbitrary, precision and show the resulting logic to be EXPSPACE-complete. This result allows us to develop an algorithm for the verification of timing properties of real-time systems with a dense semantics.}, author = {Alur, Rajeev and Feder, Tomás and Henzinger, Thomas A}, booktitle = {Proceedings of the 10th Annual ACM Symposium on Principles of Distributed Computing}, isbn = {978-0-89791-439-0}, location = {Montreal, Canada}, pages = {139 -- 152}, publisher = {ACM}, title = {{The benefits of relaxing punctuality}}, doi = {10.1145/227595.227602}, year = {1991}, } @article{2482, abstract = {The complementary DNA of a metabotropic glutamate receptor coupled to inositol phosphate/Ca2+ signal transduction has been cloned and characterized. This receptor shows no sequence similarity to conventional G protein-coupled receptors and has a unique structure with large hydrophilic sequences at both sides of seven putative membrane-spanning domains. Abundant expression of this messenger RNA is observed in neuronal cells in hippocampal dentate gyrus and CA2-3 and in cerebellar Purkinje cells, suggesting the importance of this receptor in specific hippocampal and cerebellar functions.}, author = {Masu, Masayuki and Tanabe, Yasuto and Tsuchida, Kunihiro and Shigemoto, Ryuichi and Nakanishi, Shigetada}, issn = {1476-4687}, journal = {Nature}, number = {6312}, pages = {760 -- 765}, publisher = {Nature Publishing Group}, title = {{Sequence and expression of a metabotropic glutamate receptor}}, doi = {10.1038/349760a0}, volume = {349}, year = {1991}, } @article{2483, abstract = {A complementary DNA encoding the rat NMDA receptor has been cloned and characterized. The single protein encoded by the cDNA forms a receptor-channel complex that has electrophysiological and pharmacological properties characteristic of the NMDA receptor. This protein has a significant sequence similarity to the AMPA/kainate receptors and contains four putative transmembrane segments following a large extracellular domain. The NMDA receptor messenger RNA is expressed in neuronal cells throughout the brain regions, particularly in the hippocampus, cerebral cortex and cerebellum.}, author = {Moriyoshi, Koki and Masu, Masayuki and Ishii, Takahiro and Shigemoto, Ryuichi and Mizuno, Noboru and Nakanishi, Shigetada}, issn = {1476-4687}, journal = {Nature}, number = {6348}, pages = {31 -- 37}, publisher = {Nature Publishing Group}, title = {{Molecular cloning and characterization of the rat NMDA receptor}}, doi = {10.1038/354031a0}, volume = {353}, year = {1991}, } @article{2529, abstract = {The distribution of cerebral cortical neurons sending projection fibers to the nucleus of the solitary tract (NST), and the topographical distribution of axon terminals of cortico-NST fibers within the NST were examined in the cat by two sets of experiments with horseradish peroxidase (HRP) and HRP conjugated with wheat germ agglutinin (WGA-HRP). First, HRP was injected into the NST. In the cerebral cortex of these cats, neuronal cell bodies were labeled retrogradely in the deep pyramidal cell layer (layer V): After HRP injection centered on the rostral or middle part of the NST, HRP-labeled neuronal cell bodies were distributed mainly in the orbital gyrus and caudal part of the intralimbic cortex, and additionally in the rostral part of the anterior sylvian gyrus. After HRP injection centered on the caudal part of the NST, labeled neuronal cell bodies were seen mainly in the caudoventral part of the intralimbic cortex, and additionally in the orbital gyrus, posterior sigmoid gyrus and rostral part of the anterior sylvian gyrus. The labeling in the intralimbic cortex, orbital gyrus and anterior sylvian gyrus was bilateral with a predominantly ipsilateral distribution, while that in the posterior sigmoid gyrus was bilateral with a clear-cut contralateral dominance. In the second set of experiments, WGA-HRP was injected into the cerebral cortical regions where neuronal cell bodies had been retrogradely labeled with HRP injected into the NST: after WGA-HRP injection into the orbital gyrus, presumed axon terminals in the NST were labeled in the rostral two thirds of the nucleus bilaterally with an ipsilateral predominance. After WGA-HRP injection into the rostral part of the anterior sylvian gyrus, a moderate number of presumed axon terminals were labeled throughout the whole rostrocaudal extent of the NST bilaterally with a slight ipsilateral dominance. After WGA-HRP injection into the middle and caudal parts of the anterior sylvian gyrus, no labeling was found in the NST. After WGA-HRP injection into the caudal part of the intralimbic cortex, presumed terminal labeling in the NST was seen throughout the whole rostrocaudal extent of the nucleus bilaterally with a dominant ipsilateral distribution. After WGA-HRP injection into the posterior sigmoid gyrus, however, no terminal labeling was found in the NST. The results indicate that cortico-NST fibers from the orbital gyrus terminate in the rostral two thirds of the NST, while those from the intralimbic cortex and the rostral part of the anterior sylvian gyrus project to the whole rostrocaudal extent of the NST.}, author = {Yasui, Yukihiko and Itoh, Kazuo and Kaneko, Takeshi and Shigemoto, Ryuichi and Mizuno, Noboru}, issn = {1432-1106}, journal = {Experimental Brain Research}, number = {1}, pages = {75 -- 84}, publisher = {Springer}, title = {{Topographical projections from the cerebral cortex to the nucleus of the solitary tract in the cat}}, doi = {10.1007/BF00229988}, volume = {85}, year = {1991}, } @inbook{2530, author = {Nakanishi, Shigetada and Ohkubo, Hiroaki and Kakizuka, Akira and Yokota, Yoshifumi and Shigemoto, Ryuichi and Sasai, Yoshiki and Takumi, Toru}, booktitle = {Recent Progress in Hormone Research}, isbn = {978-0-12-571148-7}, pages = {59 -- 83}, publisher = {The Endocrine Society}, title = {{Molecular characterization of mammalian tachykinin receptors and a possible epithelial potassium channel}}, doi = {10.1016/b978-0-12-571146-3.50007-9}, volume = {46}, year = {1991}, } @article{3467, abstract = {The effects of mast cell degranulating peptide (MCDP), a toxin from the honey bee, and of dendrotoxin (DTX), a toxin from the green mamba snake, were studied in voltage-clamped experiments with myelinated nerve fibres of Xenopus. MCDP and DTX blocked part of the K+ current. About 20% of the K+ current, however, was resistant to the toxins even in high concentrations. In Ringer solution half-maximal block was reached with concentrations of 33 nM MCDP and 11 nM DTX. In high-K+ solution the potency of both toxins was lower. β-Bungarotoxin (β-BuTX), another snake toxin, also blocked part of the K+ current, but was less potent than MCDP and DTX. Tail currents in high-K+ solution were analysed and three K+ current components were separated according to Dubois (1981b). Both MCDP and DTX selectively blocked a fast deactivating, slowly inactivating K+ current component which steeply activates between E = -60 mV and E = -40 mV (component f1). In concentrations around 100 nM, MCDP and DTX blocked neither the slow K+ current (component s) nor the fast deactivating, rapidly inactivating K+ current which activates between E = -40 mV and E = 20 mV (component f2). Similar results could be derived from K+ outward currents in Ringer solution. In high-K+, IC50 of MCDP for component f1 was 99 nM, whereas it was 7.6 μM for f2. Corresponding values for DTX are 68 nM and 1.8 μM. Binding studies with nerve fibre membranes of Xenopus reveal high-affinity binding sites for 125I-labelled DTX )K(D) = 22 pM in Ringer solution and 81 pM in high-K+ solution). 125I-labelled DTX can be displaced from its sites completely by unlabelled DTX, toxin I (black mamba toxin), MCDP, and partially by β-BuTX. Immunocytochemical staining demonstrates that binding sites for DTX are present in nodal and paranodal regions of the axonal membrane. The axonal membrane of motor and sensory nerve fibres is equipped with three types of well-characterized K+ channels and constitutes so far the best preparation to study MCDP- and DTX-sensitive K+ channels with electrophysiological and biochemical methods.}, author = {Bräu, Michael and Dreyer, Florian and Jonas, Peter M and Repp, Holger and Vogel, Werner}, issn = {1469-7793}, journal = {Journal of Physiology}, pages = {365 -- 385}, publisher = {Wiley-Blackwell}, title = {{A K+ channel in Xenopus nerve fibres selectively blocked by bee and snake toxins: binding and voltage-clamp experiments}}, doi = {10.1113/jphysiol.1990.sp017918}, volume = {420}, year = {1990}, } @inbook{3565, abstract = {We investigate the complexity of determining the shape and presentation (i.e. position with orientation) of convex polytopes in multi-dimensional Euclidean space using a variety of probe models.}, author = {Dobkin, David and Edelsbrunner, Herbert and Yap, Chee}, booktitle = {Autonomous Robot Vehicles}, editor = {Cox, Ingemar and Wilfong, Gordon}, isbn = {978-1-4613-8997-2}, pages = {328 -- 341}, publisher = {Springer}, title = {{Probing convex polytopes}}, doi = {10.1007/978-1-4613-8997-2_25}, year = {1990}, } @article{3649, abstract = {Selection on polygenic characters is generally analyzed by statistical methods that assume a Gaussian (normal) distribution of breeding values. We present an alternative analysis based on multilocus population genetics. We use a general representation of selection, recombination, and drift to analyze an idealized polygenic system in which all genetic effects are additive (i.e., both dominance and epistasis are absent), but no assumptions are made about the distribution of breeding values or the numbers of loci or alleles. Our analysis produces three results. First, our equations reproduce the standard recursions for the mean and additive variance if breeding values are Gaussian; but they also reveal how non-Gaussian distributions of breeding values will alter these dynamics. Second, an approximation valid for weak selection shows that even if genetic variance is attributable to an effectively infinite number of loci with only additive effects, selection will generally drive the distribution of breeding values away from a Gaussian distribution by creating multilocus linkage disequilibria. Long-term dynamics of means can depart substantially from the predictions of the standard selection recursions, but the discrepancy may often be negligible for short-term selection. Third, by including mutation, we show that, for realistic parameter values, linkage disequilibrium has little effect on the amount of additive variance maintained at an equilibrium between stabilizing selection and mutation. Each of these analytical results is supported by numerical calculations.}, author = {Turelli, Michael and Barton, Nicholas H}, issn = {0040-5809}, journal = {Theoretical Population Biology}, number = {1}, pages = {1 -- 57}, publisher = {Academic Press}, title = {{Dynamics of polygenic characters under selection}}, doi = {10.1016/0040-5809(90)90002-D}, volume = {38}, year = {1990}, } @article{3650, abstract = {Hybrid zones can yield estimates of natural selection and gene flow. The width of a cline in gene frequency is approximately proportional to gene flow (σ) divided by the square root of per-locus selection ( &s). Gene flow also causes gametic correlations (linkage disequilibria) between genes that differ across hybrid zones. Correlations are stronger when the hybrid zone is narrow, and rise to a maximum roughly equal to s. Thus cline width and gametic correlations combine to give estimates of gene flow and selection. These indirect measures of σ and s are especially useful because they can be made from collections, and require no field experiments. The method was applied to hybrid zones between color pattern races in a pair of Peruvian Heliconius butterfly species. The species are Mullerian mimics of one another, and both show the same changes in warning color pattern across their respective hybrid zones. The expectations of cline width and gametic correlation were generated using simulations of clines stabilized by strong frequency-dependent selection. In the hybrid zone in Heliconius erato, clines at three major color pattern loci were between 8.5 and 10.2 km wide, and the pairwise gametic correlations peaked at R & 0.35. These measures suggest that s & 0.23 per locus, and that σ & 2.6 km. In erato, the shapes of the clines agreed with that expected on the basis of dominance. Heliconius melpomene has a nearly coincident hybrid zone. In this species, cline widths at four major color pattern loci varied between 11.7 and 13.4 km. Pairwise gametic correlations peaked near R & 1.00 for tightly linked genes, and at R & 0.40 for unlinked genes, giving s & 0.25 per locus and σ & 3.7 km. In melpomene, cline shapes did not perfectly fit theoretical shapes based on dominance; this deviation might be explained by long-distance migration and/or strong epistasis. Compared with erato, sample sizes in melpomene are lower and the genetics of its color patterns are less well understood. In spite of these problems, selection and gene flow are clearly of the same order of magnitude in the two species. The relatively high per locus selection coefficients agree with ``major gene'' theories for the evolution of Mullerian mimicry, but the genetic architecture of the color patterns does not. These results show that the genetics and evolution of mimicry are still only sketchily understood.}, author = {Mallet, James and Barton, Nicholas H and Lamas, Gerado and Santisteban, José and Muedas, Manuel and Eeley, Harriet}, issn = {0016-6731}, journal = {Genetics}, number = {4}, pages = {921 -- 936}, publisher = {Genetics Society of America}, title = {{Estimates of selection and gene flow from measures of cline width and linkage disequilibrium in Heliconius hybrid zones}}, doi = {10.1093/genetics/124.4.921}, volume = {124}, year = {1990}, } @article{3651, abstract = {It is widely held that each gene typically affects many characters, and that each character is affected by many genes. Moreover, strong stabilizing selection cannot act on an indefinitely large number of independent traits. This makes it likely that heritable variation in any one trait is maintained as a side effect of polymorphisms which have nothing to do with selection on that trait. This paper examines the idea that variation is maintained as the pleiotropic side effect of either deleterious mutation, or balancing selection. If mutation is responsible, it must produce alleles which are only mildly deleterious (s & 10(-3)), but nevertheless have significant effects on the trait. Balancing selection can readily maintain high heritabilities; however, selection must be spread over many weakly selected polymorphisms if large responses to artificial selection are to be possible. In both classes of pleiotropic model, extreme phenotypes are less fit, giving the appearance of stabilizing selection on the trait. However, it is shown that this effect is weak (of the same order as the selection on each gene): the strong stabilizing selection which is often observed is likely to be caused by correlations with a limited number of directly selected traits. Possible experiments for distinguishing the alternatives are discussed.}, author = {Barton, Nicholas H}, issn = {0016-6731}, journal = {Genetics}, number = {3}, pages = {773 -- 782}, publisher = {Genetics Society of America}, title = {{Pleiotropic models of quantitative variation}}, doi = {10.1093/genetics/124.3.773 }, volume = {124}, year = {1990}, }