@article{1946, abstract = {An ultra-low dose (10-14 M) of opioid peptide [D-Ala2]methionine enkephalinamide (DAMEA) is found to exert an inhibitory effect on the production of reactive oxygen species (respiratory burst) in human neutrophils. The validity of this phenomenon has been verified in a series of studies that comprised 30 experiments. The inhibition has proved to be statistically significant (P<0.001). The dose-response dependence of the effect (10-15-10-9 M) followed a characteristic biphasic pattern (with the maximum effect at ultra-low doses). An opioid antagonist, naloxone partially blocks the inhibitory effect, which indicates that the DAMEA action is at least partially mediated by opioid receptors.}, author = {Zaǐtsev, Sergei and Sazanov, Leonid A and Koshkin, Aleksei and Sud'Ina, Galina and Varfolomeev, Sergei}, issn = {0014-2956}, journal = {FEBS Letters}, number = {1}, pages = {84 -- 86}, publisher = {Elsevier}, title = {{Respiratory burst inhibition in human neutrophils by ultra-low doses of [D-Ala2] methionine enkephalinamide}}, doi = {10.1016/0014-5793(91)81109-L}, volume = {291}, year = {1991}, } @article{3468, abstract = {Two types of metabolically regulated K channels have been identified for the first time in enzymatically demyelinated fibres of amphibian sciatic nerve using the patch-clamp technique. A maxi K channel with a single-channel conductance of 132 pS (105 mM K on both sides of the membrane, 15°C) is activated both by micromolar concentrations of internal Ca and by depolarization. A second type of K channel with a conductance of 44 pS is inhibited by intracellular adenosine 5'-triphosphate (ATP) with a half-maximal inhibitory concentration (IC50) of 35 μM. It is blocked by submicromolar concentrations of external glibenclamide. Both channels are sensitive to external tetraethylammonium chloride (IC50 = 0.2 mM for the maxi K channel and 4.2 mM for the ATP-sensitive channel). They may be part of a complex feedback system regulating axonal excitability under various metabolic conditions. }, author = {Jonas, Peter M and Koh, Duk and Kampe, Knut and Hermsteiner, Markus and Vogel, Werner}, issn = {1432-2013}, journal = {Pflügers Archiv : European Journal of Physiology}, number = {1-2}, pages = {68 -- 73}, publisher = {Springer}, title = {{ATP-sensitive and Ca-activated K channels in vertebrate axons: novel links between metabolism and excitability}}, doi = {10.1007/BF00370453}, volume = {418}, year = {1991}, } @inbook{3566, abstract = {This paper proves an O(m2/3n2/3 + m + n) upper bound on the number of incidences between m points and n hyperplanes in four dimensions, assuming all points lie on one side of each hyperplane and the points and hyperplanes satisfy certain natural general position conditions. This result has application to various three-dimensional combinatorial distance problems. For example, it implies the same upper bound for the number of bichromatic minimum distance pairs in a set of m blue and n red points in three-dimensional space. This improves the best previous bound for this problem. © Springer-Verlag Berlin Heidelberg 1990.}, author = {Edelsbrunner, Herbert and Sharir, Micha}, booktitle = {Applied Geometry and Discrete Mathematics: The Victor Klee Festschrift}, isbn = {978-0897913850}, pages = {253 -- 263}, publisher = {American Mathematical Society}, title = {{A hyperplane incidence problem with applications to counting distances}}, volume = {4}, year = {1991}, } @inbook{3567, abstract = {Many computational geometry problems arc exceedingly more difficult if the setting is the (three-dimensional real) space R3 rather than the plane . Most often the reason for this striking increase in complexity is the appearance of new geometric phenomena caused by one-dimensional objects in space. The intention of recent studies on problems for lines in space is to shed light on these new phenomena and their complexities. This paper reviews some of the most important results and shows how they are related to problems in dimensions 2 and 5. }, author = {Edelsbrunner, Herbert}, booktitle = {Discrete & Computational Geometry: Papers from the Dimacs Special Year}, isbn = {9780821865958}, pages = {77 -- 93}, publisher = {Springer}, title = {{Lines in space – A collection of results}}, volume = {6}, year = {1991}, } @article{3646, abstract = {We compare the pattern of morphological and electrophoretic variation in the hybrid zone between Bombina bombina and B. variegata across two transects: one near Cracow and one 200 km away, near Przemysl in southeastern Poland. Morphological variation across the Przemysl transect had been surveyed more than 50 years ago; though we found a significant shift at one site, there is no evidence for gross movement over this period. Morphological and electrophoretic changes coincide, and the average shape of the clines is the same across both transects. At the center, most of the change in frequency of six diagnostic allozymes occurs within w = 6.05 km (2-unit support limits 5.56-6.54 km). These steep gradients are generated not by selection on the allozymes themselves, but by associations with other loci: though these markers are unlinked, they are in strong linkage disequilibrium with each other [R = D/ = 0.22 (0.15-0.29) at the center]. Disequilibria are broken up as alleles diffuse away from the zone and flow into the new genetic background. The net barrier to the flow of genes from bombina into variegata, which is generated by these disequilibria, is B = 51 (22-81) km. The fitness of hybrids must be substantially reduced to produce such a barrier [W̄H/W̄P = 0.58 (0.54-0.68)], and this selection must be spread over many loci [N = 55 (26-88)]. Alleles introgress significantly less far than would be expected from the age of the zone and the estimated dispersal rate [σ = 0.99 (0.82-1.14) km gen.-1/2]: this implies selection of se = 0.37 (0.15-0.58)% on the enzymes themselves. There is weak but significant linkage disequilibrium well away from the center of the zone; this, together with the presence of parental and F1 genotypes, suggests some long-range migration. However, such migration is not likely to cause significant introgression. }, author = {Szymura, Jacek and Barton, Nicholas H}, issn = {1558-5646}, journal = {Evolution}, number = {2}, pages = {237 -- 261}, publisher = {Wiley-Blackwell}, title = {{The genetic structure of the hybrid zone between the fire-bellied toads Bombina bombina and B. variegata: comparisons between transects and between loci}}, doi = {10.1111/j.1558-5646.1991.tb04400.x}, volume = {45}, year = {1991}, } @article{3647, abstract = {A method is developed that describes the effects on an arbitrary number of autosomal loci of selection on haploid and diploid stages, of nonrandom mating between haploid individuals, and of recombination. We provide exact recursions for the dynamics of allele frequencies and linkage disequilibria (nonrandom associations of alleles across loci). When selection is weak relative to recombination, our recursions provide simple approximations for the linkage disequilibria among arbitrary combinations of loci. We show how previous models of sex-independent natural selection on diploids, assortative mating between haploids, and sexual selection on haploids can be analyzed in this framework. Using our weak-selection approximations, we derive new results concerning the coevolution of male traits and female preferences under natural and sexual selection. In particular, we provide general expressions for the intensity of linkage-disequilibrium induced selection experienced by loci that contribute to female preferences for specific male traits. Our general results support the previous observation that these indirect selection forces are so weak that they are unlikely to dominate the evolution of preference-producing loci.}, author = {Barton, Nicholas H and Turelli, Michael}, issn = {0016-6731}, journal = {Genetics}, number = {1}, pages = {229 -- 255}, publisher = {Genetics Society of America}, title = {{Natural and sexual selection on many loci}}, doi = {10.1093/genetics/127.1.229}, volume = {127}, year = {1991}, } @article{3648, abstract = {We investigate the probability of fixation of a chromosome rearrangement in a subdivided population, concentrating on the limit where migration is so large relative to selection (m ≫ s) that the population can be thought of as being continuously distributed. We study two demes, and one- and two-dimensional populations. For two demes, the probability of fixation in the limit of high migration approximates that of a population with twice the size of a single deme: migration therefore greatly reduces the fixation probability. However, this behavior does not extend to a large array of demes. Then, the fixation probability depends primarily on neighborhood size (Nb), and may be appreciable even with strong selection and free gene flow (≈exp(-B·Nb) in one dimension, ≈exp(-B\cdotNb) in two dimensions). Our results are close to those for the more tractable case of a polygenic character under disruptive selection.}, author = {Barton, Nicholas H and Rouhani, Shahin}, issn = {1558-5646}, journal = {Evolution}, number = {3}, pages = {499 -- 517}, publisher = {Wiley-Blackwell}, title = {{The probability of fixation of a new karyotype in a continuous population}}, doi = {10.1111/j.1558-5646.1991.tb04326.x}, volume = {45}, year = {1991}, } @article{4051, abstract = {An algorithm is presented that constructs the convex hull of a set of n points in three dimensions in worst-case time O(n log2h) and storage O(n), where h is the number of extreme points. This is an improvement of the O(nh) time gift-wrapping algorithm and, for certain values of h, of the O(n log n) time divide-and-conquer algorithm.}, author = {Edelsbrunner, Herbert and Shi, Weiping}, issn = {1095-7111}, journal = {SIAM Journal on Computing}, number = {2}, pages = {259 -- 269}, publisher = {SIAM}, title = {{An O(n log^2 h) time algorithm for the three-dimensional convex hull problem}}, doi = {10.1137/0220016 }, volume = {20}, year = {1991}, } @article{4052, abstract = {This paper describes an effective procedure for stratifying a real semi-algebraic set into cells of constant description size. The attractive feature of our method is that the number of cells produced is singly exponential in the number of input variables. This compares favorably with the doubly exponential size of Collins' decomposition. Unlike Collins' construction, however, our scheme does not produce a cell complex but only a smooth stratification. Nevertheless, we are able to apply our results in interesting ways to problems of point location and geometric optimization.}, author = {Chazelle, Bernard and Edelsbrunner, Herbert and Guibas, Leonidas and Sharir, Micha}, issn = {1879-2294}, journal = {Theoretical Computer Science}, number = {1}, pages = {77 -- 105}, publisher = {Elsevier}, title = {{A singly exponential stratification scheme for real semi-algebraic varieties and its applications}}, doi = {10.1016/0304-3975(91)90261-Y}, volume = {84}, year = {1991}, } @inproceedings{4054, abstract = {The zone theorem for an arrangement of n hyperplanes in d-dimensional real space says that the total number of faces bounding the cells intersected by another hyperplane is O(n d–1). This result is the basis of a time-optimal incremental algorithm that constructs a hyperplane arrangement and has a host of other algorithmic and combinatorial applications. Unfortunately, the original proof of the zone theorem, for d ge 3, turned out to contain a serious and irreparable error. This paper presents a new proof of the theorem. Our proof is based on an inductive argument, which also applies in the case of pseudo-hyperplane arrangements. We also briefly discuss the fallacies of the old proof along with some ways of partially saving that approach.}, author = {Edelsbrunner, Herbert and Seidel, Raimund and Sharir, Micha}, pages = {108 -- 123}, publisher = {Springer}, title = {{On the zone theorem for hyperplane arrangements}}, doi = {10.1007/BFb0038185}, volume = {555}, year = {1991}, } @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}, }