@article{4075, abstract = {A key problem in computational geometry is the identification of subsets of a point set having particular properties. We study this problem for the properties of convexity and emptiness. We show that finding empty triangles is related to the problem of determining pairs of vertices that see each other in a star-shaped polygon. A linear-time algorithm for this problem which is of independent interest yields an optimal algorithm for finding all empty triangles. This result is then extended to an algorithm for finding empty convex r-gons (r> 3) and for determining a largest empty convex subset. Finally, extensions to higher dimensions are mentioned.}, author = {Dobkin, David and Edelsbrunner, Herbert and Overmars, Mark}, issn = {1432-0541}, journal = {Algorithmica}, number = {4}, pages = {561 -- 571}, publisher = {Springer}, title = {{Searching for empty convex polygons}}, doi = {10.1007/BF01840404}, volume = {5}, year = {1990}, } @inproceedings{4076, 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(Td(N, N) logd N), where Td(n, m) is the time required to compute a bichromatic closest pair among n red and m blue points in Ed. If Td(N, N) = Ω(N1+ε), for some fixed ε > 0, then the running time improves to O(Td(N, N)). Furthermore, we describe a randomized algorithm to compute a bichromatic closets pair in expected time O((nm log n log m)2/3+m log2 n + n log2 m) in E3, which yields an O(N4/3log4/3 N) expected time algorithm for computing a Euclidean minimum spanning tree of N points in E3.}, author = {Agarwal, Pankaj and Edelsbrunner, Herbert and Schwarzkopf, Otfried and Welzl, Emo}, booktitle = {Proceedings of the 6th annual symposium on Computational geometry}, isbn = {978-0-89791-362-1}, location = {Berkeley, CA, United States}, pages = {203 -- 210}, publisher = {ACM}, title = {{ Euclidean minimum spanning trees and bichromatic closest pairs}}, doi = {10.1145/98524.98567}, year = {1990}, } @inproceedings{4077, abstract = {We prove that for any set S of n points in the plane and n3-α triangles spanned by the points of S there exists a point (not necessarily of S) contained in at least n3-3α/(512 log25 n) of the triangles. This implies that any set of n points in three - dimensional space defines at most 6.4n8/3 log5/3 n halving planes.}, author = {Aronov, Boris and Chazelle, Bernard and Edelsbrunner, Herbert and Guibas, Leonidas and Sharir, Micha and Wenger, Rephael}, booktitle = {Proceedings of the 6th annual symposium on Computational geometry}, isbn = {978-0-89791-362-1}, location = {Berkley, CA, United States}, pages = {112 -- 115}, publisher = {ACM}, title = {{Points and triangles in the plane and halving planes in space}}, doi = {10.1145/98524.98548}, year = {1990}, } @inproceedings{4078, abstract = {In this paper we derived combinatorial point selection results for geometric objects defined by pairs of points. In a nutshell, the results say that if many pairs of a set of n points in some fixed dimension each define a geometric object of some type, then there is a point covered by many of these objects. Based on such a result for three-dimensional spheres we show that the combinatorial size of the Delaunay triangulation of a point set in space can be reduced by adding new points. We believe that from a practical point of view this is the most important result of this paper.}, author = {Chazelle, Bernard and Edelsbrunner, Herbert and Guibas, Leonidas and Hershberger, John and Seidel, Raimund and Sharir, Micha}, booktitle = {Proceedings of the 6th annual symposium on computational geometry}, isbn = {978-0-89791-362-1}, location = {Berkley, CA, United States}, pages = {116 -- 127}, publisher = {ACM}, title = {{Slimming down by adding; selecting heavily covered points}}, doi = {10.1145/98524.98551}, year = {1990}, } @article{4310, author = {Barton, Nicholas H and Jones, Steve}, issn = {1476-4687}, journal = {Nature}, pages = {415 -- 416}, publisher = {Nature Publishing Group}, title = {{The language of the genes}}, doi = {10.1038/346415a0}, volume = {346}, year = {1990}, } @inbook{4311, author = {Barton, Nicholas H and Clark, A.}, booktitle = {Population biology: Ecological and evolutionary viewpoints}, editor = {Wöhrmann, Klaus and Jain, Subodh}, isbn = { 978-3642744761}, pages = {115 -- 174}, publisher = {Springer}, title = {{Population structure and processes in evolution}}, doi = {10.1007/978-3-642-74474-7_5}, year = {1990}, } @inproceedings{4510, abstract = {The interleaving model is both adequate and sufficiently abstract to allow for the practical specification and verification of many properties of concurrent systems. We incorporate real time into this 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 upper-bound real-time requirements for transitions. We present proof rules to establish lower and upper real-time bounds for response properties of real-time transition systems. This proof system can be used to verify bounded-invariance and bounded-response properties, such as timely termination of shared-variables multi-process systems, whose semantics is defined in terms of real-time transition systems.}, author = {Henzinger, Thomas A and Manna, Zohar and Pnueli, Amir}, booktitle = { Proceedings of the 5th Jerusalem Conference on Information Technology}, isbn = {0-8186-2078-1}, location = {Jerusalem, Israel}, pages = {717 -- 730}, publisher = {IEEE}, title = {{An interleaving model for real time}}, doi = {10.1109/JCIT.1990.128356}, year = {1990}, } @inproceedings{4522, abstract = {We introduce a novel extension of propositional modal logic that is interpreted over Kripke structures in which a value is associated with every possible world. These values are. however, not treated as full first-order objects: they can be accessed only by a very restricted form of quantification: the "freeze" quantifier binds a variable to the value of the current world. We present a complete proof system for this ("half-order") modal logic. As a special case, we obtain the real-time temporal logic TPTL of [AH891: the models are restricted to infinite sequences of states, whose values are monotonically increasing natural numbers. The ordering relation between states is interpreted as temporal precedence. while the value associated with a state is interpreted as its "rear time. We extend our proof system to be complete for TPTL. and demonstrate how it can be used to derive real-time properties. }, author = {Henzinger, Thomas A}, booktitle = {Proceedings of the 9th annual ACM symposium on Principles of distributed computing}, isbn = {978-0-89791-404-8}, location = {Quebec City, Canada}, pages = {281 -- 296}, publisher = {ACM}, title = {{Half-order modal logic: How to prove real-time properties}}, doi = {10.1145/93385.93429}, 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{2479, abstract = {Distribution of putative glutamatergic neurons in the lower brainstem and cerebellum of the rat was examined immunocytochemically by using a monoclonal antibody against phosphate-activated glutaminase, which has been proposed to be a major synthetic enzyme of transmitter glutamate and so may serve as a marker for glutamatergic neurons in the central nervous system. Intensely-immunolabeled neuronal cell bodies were densely distributed in the main precerebellar nuclei sending mossy fibers to the cerebellum; in the pontine nuclei, pontine tegmental reticular nucleus of Bechterew, external cuneate nucleus, and lateral reticular nucleus of the medulla oblongata. Phosphate-activated glutaminase-immunoreactive granular deposits were densely seen in the brachium pontis and restiform body, suggesting the immunolabeling of mossy fibers of passage. In the cerebellum, neuropil within the granule cell layer of the cerebellar cortex displayed intense phosphate-activated glutaminase-immunoreactivity, and that within the deep cerebellar nuclei showed moderate immunoreactivity. These results indicate that many mossy fiber terminals originate from phosphate-activated glutaminase-containing neurons and utilize phosphate-activated glutaminase for the synthesis of transmitter glutamate. Intensely-immunostained neuronal cell bodies were further observed in other regions which have been reported to contain neurons sending mossy fibers to the cerebellum; in the dorsal part of the principal sensory trigeminal nucleus, dorsomedial part of the oral subnucleus of the spinal trigeminal nucleus, interpolar subnucleus of the spinal trigeminal nucleus, paratrigeminal nucleus, supragenual nucleus, regions dorsal to the abducens nucleus and genu of the facial nerve, superior and medial vestibular nuclei, cell groups f, x and y, hypoglossal prepositus nucleus, intercalated nucleus, nucleus of Roller, reticular regions intercalated between the motor trigeminal and principal sensory trigeminal nuclei, linear nucleus, and gigantocellular and paramedian reticular formation. Neuronal cell bodies with intense phosphate-activated glutaminase-immunoreactivity were also found in other brainstem regions, such as the paracochlear glial substance, posterior ventral cochlear nucleus, and cell group e. Although it is still controversial whether all glutamatergic neurons use phosphate-activated glutaminase in a transmitter-related process and whether phosphate-activated glutaminase is involved in other metabolism-related processes, the neurons showing intense phosphate-activated glutaminase-immuno-reactivity in the present study were suggested to be putative glutamatergic neurons.}, author = {Kaneko, Takeshi and Itoh, Kazuo and Shigemoto, Ryuichi and Mizuno, Noboru}, issn = {1873-7544}, journal = {Neuroscience}, number = {1}, pages = {79 -- 98}, publisher = {Elsevier}, title = {{Glutaminase-like immunoreactivity in the lower brainstem and cerebellum of the adult rat}}, doi = {10.1016/0306-4522(89)90109-7}, volume = {32}, year = {1989}, } @article{2525, abstract = {This paper describes the amino acid sequence of the rat substance P receptor and its comparison with that of the rat substance K receptor on the basis of molecular cloning and sequence analysis. From a rat brain cDNA library constructed with an RNA expression vector, we identified a cDNA mixture containing a functional substance P receptor cDNA by examining electrophysiologically a receptor expression following injection of the mRNAs synthesized in vitro into Xenopus oocytes. A receptor cDNA clone was then isolated by cross-hybridization with the bovine substance K receptor DNA. The clone was confirmed by selective binding of substance P to the cloned receptor expressed in mammalian COS cells. The deduced amino acid sequence (407 amino acid residues) possesses seven putative membrane spanning domains and shows a sequence similarity to the members of G-protein-coupled receptors. The rat substance P and substance K receptor are very similar in both size and amino acid sequences, particularly in the putative transmembrane similarity is in marked contrast to the sequence divergence in the amino- and carboxyl-terminal regions and the third cytoplasmic loop. The observed sequence similarytity and divergence would thus contribute to the expression of similar but pharmacological regions and the first and second cytoplasmic loops. This distinguishable activities of the two tachykinin receptors.}, author = {Yokota, Yoshifumi and Sasai, Yoshiki and Tanaka, Kohichi and Fujiwara, Tsutomu and Tsuchida, Kunihiro and Shigemoto, Ryuichi and Kakizuka, Akira and Ohkubo, Hiroaki and Nakanishi, Shigetada}, issn = {1083-351X}, journal = {Journal of Biological Chemistry}, number = {30}, pages = {17649 -- 17652}, publisher = {American Society for Biochemistry and Molecular Biology}, title = {{Molecular characterization of a functional cDNA for rat substance P receptor}}, doi = {10.1016/S0021-9258(19)84619-7}, volume = {264}, year = {1989}, } @article{2526, abstract = {When WGA-HRP (wheat germ agglutinin-horseradish peroxidase conjugate) or HRP was injected into the regions around the superior central and/or the dorsal raphe nuclei in the cat, cell bodies of a number of non-pyramidal neurons were labeled in Ammon's horn. Thus the existence of direct projections from non-pyramidal neurons in Ammon's horn to the rostral raphe regions in the brainstem was suggested in the cat.}, author = {Ino, Tadashi and Itoh, Kazuo and Kamiya, Hiroto and Kaneko, Takeshi and Shigemoto, Ryuichi and Akiguchi, Ichiro and Mizuno, Noboru}, issn = {1872-6240}, journal = {Brain Research}, number = {1}, pages = {157 -- 161}, publisher = {Elsevier}, title = {{Direct projections from Ammon's horn to the rostral raphe regions in the brainstem of the cat}}, doi = {10.1016/0006-8993(89)91346-2}, volume = {479}, year = {1989}, } @article{2527, author = {Akimoto, Masumi and Shigemoto, Ryuichi and Kawamura, Makiko and Yamagata, Hideharu and Kurihara, Takeshi and Takata, S and Miwa, Yoko and Akagami, N and Katsu, Kenichi and Yamauchi, D}, journal = {Japanese Journal of Gastroenterology}, number = {11}, pages = {2627}, publisher = {Japanese Society of Gastroenterology}, title = {{Effect of endothelin on gastric mucosal blood flow in rat}}, doi = {10.11405/nisshoshi1964.86.2627}, volume = {86}, year = {1989}, } @inproceedings{4596, abstract = {A real-time temporal logic for the specification of reactive systems is introduced. The novel feature of the logic, TPTL, is the adoption of temporal operators as quantifiers over time variables; every modality binds a variable to the time(s) it refers to. TPTL is demonstrated to be both a natural specification language and a suitable formalism for verification and synthesis. A tableau-based decision procedure and model-checking algorithm for TPTL are presented. Several generalizations of TPTL are shown to be highly undecidable.}, author = {Alur, Rajeev and Henzinger, Thomas A}, booktitle = {30th Annual Symposium on Foundations of Computer Science}, isbn = {0-8186-1982-1}, issn = {1558-0814}, location = {Research Triangle Park, NC, USA}, pages = {164 -- 169}, publisher = {IEEE}, title = {{A really temporal logic}}, doi = {10.1109/SFCS.1989.63473}, year = {1989}, } @article{3465, abstract = {Asymmetrical displacement currents and Na currents of single myelinated nerve fibers of Xenopus laevis were studied in the temperature range from 5 to 24 degrees C. The time constant of the on-response at E = 4 mV, tau on, was strongly temperature dependent, whereas the amount of displaced charge at E = 39 mV, Qon, was only slightly temperature dependent. The mean Q10 for tau on-1 was 2.54, the mean Q10 for Qon was 1.07. The time constant of charge immobilization, tau i, at E = 4 mV varied significantly (alpha = 0.001) with temperature. The mean Q10 for tau i-1 was 2.71 +/- 0.38. The time constants of immobilization of gating charge and of fast inactivation of Na permeability were similar in the temperature range from 6 to 22 degrees C. The Qoff/Qon ratio for E = 4 mV pulses of 0.5 msec duration decreased with increasing temperature. The temperature dependence of the time constant of the off-response could not be described by a single Q10 value, since the Q10 depended on the duration of the test pulse. Increasing temperature shifted Qon (E) curves to more negative potentials by 0.51 mV K-1, but shifted PNa (E) curves and h infinity (E) curves to more positive potentials by 0.43 and 0.57 mV K-1, respectively. h infinity (E = -70 mV) increased monotonously with increasing temperature. The present data indicate that considerable entropy changes may occur when the Na channel molecule passes from closed through open to inactivated states.}, author = {Jonas, Peter M}, issn = {1432-1424}, journal = {Journal of Membrane Biology}, number = {3}, pages = {277 -- 289}, publisher = {Springer}, title = {{Temperature dependence of gating current in myelinated nerve fibers}}, doi = {10.1007/BF01870958}, volume = {112}, year = {1989}, } @article{3466, abstract = {Amphibian myelinated nerve fibers were treated with collagenase and protease. Axons with retraction of the myelin sheath were patch-clamped in the nodal and paranodal region. One type of Na channel was found. It has a single-channel conductance of 11 pS (15 degrees C) and is blocked by tetrodotoxin. Averaged events show the typical activation and inactivation kinetics of macroscopic Na current. Three potential-dependent K channels were identified (I, F, and S channel). The I channel, being the most frequent type, has a single-channel conductance of 23 pS (inward current, 105 mM K on both sides of the membrane), activates between -60 and -30 mV, deactivates with intermediate kinetics, and is sensitive to dendrotoxin. The F channel has a conductance of 30 pS, activates between -40 and 60 mV, and deactivates with fast kinetics. The former inactivates within tens of seconds; the latter inactivates within seconds. The third type, the S channel, has a conductance of 7 pS and deactivates slowly. All three channels can be blocked by external tetraethylammonium chloride. We suggest that these distinct K channel types form the basis for the different components of macroscopic K current described previously.}, author = {Jonas, Peter M and Bräu, Michael and Hermsteiner, Markus and Vogel, Werner}, issn = {1091-6490}, journal = {PNAS}, number = {18}, pages = {7238 -- 7242}, publisher = {National Academy of Sciences}, title = {{Single-channel recording in myelinated nerve fibers reveals one type of Na channel but different K channels}}, doi = {10.1073/pnas.86.18.7238}, volume = {86}, year = {1989}, } @inproceedings{3549, abstract = {We study three types of spatial triangulations: Delaunay triangulations, triangulations with non-obtuse dihedral angles, and KJ-triangulations. The latter satisfy a certain angle condition useful for finite element approximation. We show that the condition for Delaunay triangulations is incomparable with the other two conditions, and that triangulations with non-obtuse dihedral angles are necessarily also KJ-triangulations. These relationships are in sharp contrast to the ones in the planar case. }, author = {Edelsbrunner, Herbert}, pages = {83 -- 89}, publisher = {Institute of the Electronics, Information and Communication Enginneers}, title = {{Spatial triangulations with dihedral angle conditions}}, year = {1989}, } @article{3652, abstract = {Frequency-dependent selection against rare forms can maintain clines. For weak selection, s, in simple linear models of frequency-dependence, single locus clines are stabilized with a maximum slope of between square root of s/square root of 8 sigma and square root of s/square root of 12 delta, where sigma is the dispersal distance. These clines are similar to those maintained by heterozygote disadvantage. Using computer simulations, the weak-selection analytical results are extended to higher selection pressures with up to three unlinked genes. Graphs are used to display the effect of selection, migration, dominance, and number of loci on cline widths, speeds of cline movements, two-way gametic correlations ("linkage disequilibria"), and heterozygote deficits. The effects of changing the order of reproduction, migration, and selection, are also briefly explored. Epistasis can also maintain tension zones. We show that epistatic selection is similar in its effects to frequency-dependent selection, except that the disequilibria produced in the zone will be higher for a given level of selection. If selection consists of a mixture of frequency-dependence and epistasis, as is likely in nature, the error made in estimating selection is usually less than twofold. From the graphs, selection and migration can be estimated using knowledge of the dominance and number of genes, of gene frequencies and of gametic correlations from a hybrid zone.}, author = {Mallet, James and Barton, Nicholas H}, issn = {0016-6731}, journal = {Genetics}, number = {4}, pages = {967 -- 976}, publisher = {Genetics Society of America}, title = {{Inference from clines stabilized by frequency-dependent selection}}, doi = {10.1093/genetics/122.4.967}, volume = {122}, year = {1989}, } @article{3653, abstract = {Frequency-dependent selection on warning color can maintain narrow hybrid zones between unpalatable prey taxa. To measure such selection, we transferred marked Heliconius erato (Lepidoptera: Nymphalidae) in both directions across a 10-km-wide hybrid zone between Peruvian races differing in color pattern. These experimental H. erato were released at four sites, along with control H. erato of the phenotype native to each site. Survival of experimental butterflies was significantly lower than that of controls at two sites and overall. Most selection, measured as differences in survival, occurred soon after release. Selection against foreign morphs was 52% (confidence limits: 25-71%) and was probably due to bird attacks on unusual warning-color morphs (more than 10% of the recaptures had beak marks). Since only three major loci determine the color-pattern differences, this suggests an average selection coefficient of 0.17 per locus, sufficient to maintain the narrow clines in H. erato.}, author = {Mallet, James and Barton, Nicholas H}, issn = {1558-5646}, journal = {Evolution}, number = {2}, pages = {421 -- 431}, publisher = {Wiley-Blackwell}, title = {{Strong natural selection in a warning color hybrid zone}}, doi = {10.2307/2409217 }, volume = {43}, year = {1989}, } @article{3654, abstract = {Many species are divided into a mosaic of genetically distinct populations, separated by narrow zones of hybridization. Studies of hybrid zones allow us to quantify the genetic differences responsible for speciation, to measure the diffusion of genes between diverging taxa, and to understand the spread of alternative adaptations.}, author = {Barton, Nicholas H and Hewitt, Godfrey}, issn = {1476-4687}, journal = {Nature}, pages = {497 -- 503}, publisher = {Nature Publishing Group}, title = {{Adaptation, speciation and hybrid zones}}, doi = {10.1038/341497a0}, volume = {341}, year = {1989}, }