TY - JOUR
AB - A version of the one-dimensional Rayleigh gas is considered: a point particle of mass M (molecule), confined to the unit interval [0,1], is surrounded by an infinite ideal gas of point particles of mass 1 (atoms). The molecule interacts with the atoms and with the walls via elastic collision. Central limit theorems are proved for a wide class of additive functionals of this system (e.g. the number of collisions with the walls and the total length of the molecular path).
AU - László Erdös
AU - Tuyen, Dao Quang
ID - 2722
IS - 3
JF - Communications in Mathematical Physics
TI - Central limit theorems for the one-dimensional Rayleigh gas with semipermeable barriers
VL - 143
ER -
TY - JOUR
AB - The effects of ultra-low (10(-18)-10(-14) M) doses (ULD) of biologically active substances have been reviewed in terms of common regularities of ULD effects and peculiarities of action of various groups of compounds. The most common and at the same time paradoxical regularities of ULD action are bi- or polymodal patterns of dose dependence, absence or presence of an inverse effect at higher doses, and instability of ULD effect. Possible mechanisms of ULD action including the mechanism based on the adaptation theory are discussed.
AU - Leonid Sazanov
AU - Zaǐtsev, Sergei V
ID - 1945
IS - 10
JF - Biokhimiya
TI - Effect of superlow doses (10(-18)-10-(-14) M) of biologically active substances: general rules, features, and possible mechanisms
VL - 57
ER -
TY - JOUR
AB - Glutamate-operated ion channels (GluR channels) of the L-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-kainate subtype are found in both neurons and glial cells of the central nervous system. These channels are assembled from the GluR-A, -B, -C, and -D subunits; channels containing a GluR-B subunit show an outwardly rectifying current-voltage relation and low calcium permeability, whereas channels lacking the GluR-B subunit are characterized by a doubly rectifying current-voltage relation and high calcium permeability. Most cell types in the central nervous system coexpress several subunits, including GluR-B. However, Bergmann glia in rat cerebellum do not express GluR-B subunit genes. In a subset of cultured cerebellar glial cells, likely derived from Bergmann glial cells. GluR channels exhibit doubly rectifying current-voltage relations and high calcium permeability, whereas GluR channels of cerebellar neurons have low calcium permeability. Thus, differential expression of the GluR-B subunit gene in neurons and glia is one mechanism by which functional properties of native GluR channels are regulated.
AU - Burnashev, Nail A
AU - Khodorova, Alla
AU - Peter Jonas
AU - Helm, P. J.
AU - Wisden, William
AU - Monyer, Hannah
AU - Seeburg, Peter H
AU - Sakmann, Bert
ID - 3469
IS - 5063
JF - Science
TI - Calcium-permeable AMPA-kainate receptors in fusiform cerebellar glial cells.
VL - 256
ER -
TY - JOUR
AB - Currents activated by glutamate receptor (GluR) agonists were recorded from outside-out patches isolated from the soma of visually identified pyramidal neurones of the (CA3 and CA1 region of rat hippocampal slices. α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). L-glutamate (L-Glu), and kainate (KA) were delivered either by bath application through perfusion of the recording chamber or by rapid application via a piezo-driven two-barrelled fast application system. 2. Bath application of each of the three agonists activated inward currents in all patches (n = 134) at holding potentials of -50 or -60 mV. The current amplitude increased in size between 3 to 30 μM-AMPA and 100 μM to 1 mM-KA. With this slow mode of bath application, the responses showed no apparent desensitization even at saturating concentrations of AMPA (30 μM) and KA (1 mM). 3. The ratio of currents activated by 30 μM-AMPA and 300 μM-KA showed a characteristic difference between CA3 and CA1 neurones. The ratio was 0.242 ± 0.028 (mean ± S.E.M., n = 16) for CA3 cell patches and 0.097 ± 0.012 (n = 8) for CA1 cell patches indicating that GluRs in the two cell populations are different. 4. The steady-state current-voltage relations (I-Vs) for AMPA- and KA-activated currents showed pronounced outward rectification for both cell types (when the main cations are Na+ in the bath and Cs+ in the pipette solution). The current reversed close to 0 mV and the ratio of chord conductances 80 mV on either side of the reversal potential was 2.66 for KA-activated currents in CA3 cell patches and 2.60 in CA1 cell patches. AMPA-activated currents showed a time-dependent increase after steps to positive membrane potentials and a decrease after steps to negative voltages, indicating that a gating process is responsible for outward rectification of the steady-state I-IV. 5. The permeability (P) of GluR channels was high for Na+ as compared to Cs+ for both cell types (P(Na)/P(Cs) = 0.88 and 0.84). The permeability was low for N-methyl-D-glucamine+ (P(NMG)/P(Cs) ≤ 0.03) and Ca2+ (P(Ca)/P(Cs) ≤0.05). 6. The current noise level increased during application of AMPA or KA. Apparent single-channel conductances obtained from fluctuation analysis were higher for AMPA than for KA, but similar for both cell types. In CA3 cell patches, AMPA activated channels with an apparent chord conductance of 7.2 pS, KA of 3.0 pS conductance. 7. Fast agonist application revealed desensitization of GluR channels which was dependent on the type of agonist, currents activated by AMPA and L-Glu rose rapidly to a peak and then desensitized to a steady-state current. In contrast, currents activated by fast application of KA rose to a plateau and did not desensitize. The steady state current expressed as a percentage of the peak current was higher for L-Glu than for AMPA and slightly higher for CA3 than for CA1 cell patches. For CA3 cell patches, this fraction amounted to 6.2 %, with 300 μM-L-Glu and 2.8%, with 300 μM-AMPA. For CA1 cell patches, corresponding values were 3.6 and 1.9 % 8. The dose response relations for the peak current activated by AMPA and L-Glu and the steady-state current activated by KA were similar for CA3 and CA1 cell patches. The order of potency was AMPA > L-Glu ≃ KA for both cell types EC50 values 189, 342 and 344 μM for CA3 cell patches and 183, 424 and 474 μM for CA1 cell patches). In all cases, the Hill coefficients ranged between 12 and 1.7. 8. The rise of AMPA and L-Glu-activated currents became faster with increasing agonist concentration for both cell types. With L-Glu, rise times decreased from about 3 ms at 100 μM to 500 μs at 3 mM. The delay for agonist concentrations ≥ 300 μM was described by the sum of two exponential functions. The time constant of the predominant fast component was slightly concentration dependent and decreased from about 12 ms at 300 μM to 8 ms at 3 mM-L-Glu. 10. The current voltage relations of the peak currents activated by 300 μM-AMPA were linear for both cell types with a reversal potential close to OmV. 11. It is concluded that the GluR channels in pyramidal cells of hippocampal CA3 and CA1 regions are distinet but share many pharmacological and functional properties. Comparison of the properties of native and recombinant GluRs suggests that in both CA3 and CA1 regions GluR channels are hetero-oligomers containing the GluR-B subunit.
AU - Peter Jonas
AU - Sakmann, Bert
ID - 3470
JF - Journal of Physiology
TI - Glutamate receptor channels in isolated patches from CA1 and CA3 pyramidal cells of rat hippocampal slices
VL - 455
ER -
TY - JOUR
AB - 1. Outside-out patches were isolated from granule cells of dentate gyrus and pyramidal cells of CA3 and CA1 regions of rat hippocampal slices. Patches were exposed briefly to L-glutamate using a piezo-driven double-barrelled application pipette. 2. Applications of glutamate (1 mM) of 1 ms duration activated patch currents which rose and decayed rapidly. The 20-80% rise time of these glutamate receptor (GluR)-mediated currents was usually 0.2-0.6 ms. At -50 mV the peak current varied from 10 to 500 pA in different patches. 3. The peak current-voltage relation for brief pulses of 1 mM glutamate was virtually linear in normal extracellular solution for patches from the three cell types (-100 to 60 mV). 4. The permeability of GluR channels activated at the peak to Ca2+, relative to K+, was less than 0.1 for all three cell types (under bi-ionic conditions with Ca2+ on the extracellular side and K+ on the intracellular side of the membrane). 5. The offset decay time constant of the current following 1 ms pulses of 1 mM glutamate was brief, with mean values of 3.0 +/- 0.8, 2.5 +/- 0.7, and 2.3 +/- 0.7 ms for dentate, CA3 and CA1 cell patches, respectively. Offset time constants were independent of membrane potential and independent of glutamate concentration (200 microM and 1 mM) for the three cell types. 6. Applications of 1 mM glutamate of 100 ms duration showed that glutamate responses desensitized rapidly. The time constants for desensitization were 9.4 +/- 2.7, 11.3 +/- 2.8, and 9.3 +/- 2.8 ms for patches from dentate, CA3 and CA1 cells respectively. Desensitization time constants were only weakly dependent on glutamate concentration (200 microM and 1 mM) for the three cell types. Thus offset time constants are about four times faster than desensitization time constants for both glutamate concentrations. 7. Double pulse application of glutamate indicated that even a 1 ms pulse of 1 mM glutamate causes partial (about 60%) desensitization of GluR channels. The time course of recovery from desensitization was slower in dentate gyrus granule cell patches than in CA3 or CA1 pyramidal cell patches. 8. Desensitization was studied at equilibrium by exposing patches to low glutamate concentrations for at least 15 s before a 1 ms test pulse of 1 mM glutamate.
AU - Colquhoun, D.
AU - Peter Jonas
AU - Sakmann, Bert
ID - 3471
JF - Journal of Physiology
TI - Action of brief pulses of glutamate on AMPA/kainate receptors in patches from different neurones of rat hippocampal slices
VL - 458
ER -
TY - JOUR
AB - A novel potassium-selective channel which is active at membrane potentials between -100 mV and +40 mV has been identified in peripheral myelinated axons of Xenopus laevis using the patch-clamp technique. At negative potentials with 105 mM-K on both sides of the membrane, the channel at 1 kHz resolution showed a series of brief openings and closings interrupted by longer closings, resulting in a flickery bursting activity. Measurements with resolution up to 10 kHz revealed a single-channel conductance of 49 pS with 105 mM-K and 17 pS with 2.5 mM-K on the outer side of the membrane. The channel was selective for K ions over Na ions (PNa/PK = 0.033). The probability of being within a burst in outside-out patches varied from patch to patch (> 0.2, but often > 0.9), and was independent of membrane potential. Open-time histograms were satisfactorily described with a single exponential (tau o = 0.09 msec), closed times with the sum of three exponentials (tau c = 0.13, 5.9, and 36.6 msec). Sensitivity to external tetraethylammonium was comparatively low (IC50 = 19.0 mM). External Cs ions reduced the apparent unitary conductance for inward currents at Em = -90 mV (IC50 = 1.1 mM). Ba and, more potently, Zn ions lowered not only the apparent single-channel conductance but also open probability. The local anesthetic bupivacaine with high potency reduced probability of being within a burst (IC50 = 165 nM). The flickering K channel is clearly different from the other five types of K channels identified so far in the same preparation. We suggest that this channel may form the molecular basis of the resting potential in vertebrate myelinated axons.
AU - Koh, Duk S
AU - Peter Jonas
AU - Bräu, Michael E
AU - Vogel, Werner
ID - 3472
JF - Journal of Membrane Biology
TI - A TEA-insensitive flickering potassium channel active around the resting potential in myelinated nerve
VL - 130
ER -
TY - JOUR
AU - Chazelle, Bernard
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas J
AU - Pollack, Richard
AU - Seidel, Raimund
AU - Sharir, Micha
AU - Snoeyink, Jack
ID - 3581
IS - 6
JF - Computational Geometry: Theory and Applications
TI - Counting and cutting cycles of lines and rods in space
VL - 1
ER -
TY - JOUR
AB - Three components of mating call (pulse duration, cycle length, and fundamental frequency) were measured and six diagnostic enzyme loci scored across the hybrid zone between the toads Bombina bombina and B. variegata. All three call components differ significantly, but only cycle length is diagnostic. The clines in call coincide with those for enzymes, and have similar widths. This suggests that there is no strong selection on any of these characters. There are significant correlations between electrophoretic markers and call components, but these are no stronger than would be expected if the electrophoretic loci and the genes causing mating call were neutral. The selection differential on the call is no greater than 6% of the difference in mean cycle length between the two taxa. There is a substantial increase in the variance of cycle length in the center of the zone, suggesting that a small number of loci are involved (≈ three). Recombination between these loci will hinder the evolution of reinforcement and may partly be responsible for the lack of premating isolation between B. bombina and B. variegata.
AU - Sanderson, Neil
AU - Szymura, Jacek M
AU - Nicholas Barton
ID - 3645
IS - 3
JF - Evolution
TI - Variation in mating call across the hybrid zone between the fire-bellied toads Bombina bombina and B. variegata
VL - 46
ER -
TY - JOUR
AB - 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.
AU - Masu, Masayuki
AU - Tanabe, Yasuto
AU - Tsuchida, Kunihiro
AU - Ryuichi Shigemoto
AU - Nakanishi, Shigetada
ID - 2482
IS - 6312
JF - Nature
TI - Sequence and expression of a metabotropic glutamate receptor
VL - 349
ER -
TY - JOUR
AB - 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.
AU - Moriyoshi, Koki
AU - Masu, Masayuki
AU - Ishii, Takahiro
AU - Ryuichi Shigemoto
AU - Mizuno, Noboru
AU - Nakanishi, Shigetada
ID - 2483
IS - 6348
JF - Nature
TI - Molecular cloning and characterization of the rat NMDA receptor
VL - 353
ER -
TY - JOUR
AB - 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.
AU - Yasui, Yukihiko
AU - Itoh, Kazuo
AU - Kaneko, Takeshi
AU - Ryuichi Shigemoto
AU - Mizuno, Noboru
ID - 2529
IS - 1
JF - Experimental Brain Research
TI - Topographical projections from the cerebral cortex to the nucleus of the solitary tract in the cat
VL - 85
ER -
TY - JOUR
AU - Nakanishi, Shigetada
AU - Ohkubo, Hiroaki
AU - Kakizuka, Akira
AU - Yokota, Yoshifumi
AU - Ryuichi Shigemoto
AU - Sasai, Yoshiki
AU - Takumi, Toru
ID - 2530
IS - 1
JF - Recent Progress in Hormone Research
TI - Molecular characterization of mammalian tachykinin receptors and a possible epithelial potassium channel
VL - 46
ER -
TY - JOUR
AB - 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.
AU - Herbert Edelsbrunner
AU - Shi, Weiping
ID - 4051
IS - 2
JF - SIAM Journal on Computing
TI - An O(n log^2 h) time algorithm for the three-dimensional convex hull problem
VL - 20
ER -
TY - JOUR
AB - 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.
AU - Chazelle, Bernard
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas J
AU - Sharir, Micha
ID - 4052
IS - 1
JF - Theoretical Computer Science
TI - A singly exponential stratification scheme for real semi-algebraic varieties and its applications
VL - 84
ER -
TY - CONF
AB - 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.
AU - Herbert Edelsbrunner
AU - Seidel, Raimund
AU - Sharir, Micha
ID - 4054
TI - On the zone theorem for hyperplane arrangements
VL - 555
ER -
TY - CONF
AB - 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.
AU - Herbert Edelsbrunner
AU - Tan, Tiow Seng
ID - 4055
TI - A quadratic time algorithm for the minmax length triangulation
ER -
TY - JOUR
AB - 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.
AU - Herbert Edelsbrunner
AU - Hajnal, Péter
ID - 4056
IS - 2
JF - Journal of Combinatorial Theory Series A
TI - A lower bound on the number of unit distances between the vertices of a convex polygon
VL - 56
ER -
TY - JOUR
AU - Herbert Edelsbrunner
ID - 4057
IS - 2
JF - Journal of Computer and System Sciences
TI - Corrigendum
VL - 42
ER -
TY - CONF
AB - 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.
AU - Chazelle, Bernard
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas
AU - Sharir, Micha
AU - Snoeyink, Jack
ID - 4058
TI - Computing a face in an arrangement of line segments
ER -
TY - CONF
AB - 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.
AU - Chazelle, Bernard
AU - Herbert Edelsbrunner
AU - Grigni, Michelangelo
AU - Guibas, Leonidas
AU - Hershberger, John
AU - Sharir, Micha
AU - Snoeyink, Jack
ID - 4059
TI - Ray shooting in polygons using geodesic triangulations
VL - 510
ER -
TY - JOUR
AB - 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}.
AU - Agarwal, Pankaj K
AU - Herbert Edelsbrunner
AU - Schwarzkopf, Otfried
AU - Welzl, Emo
ID - 4061
IS - 1
JF - Discrete & Computational Geometry
TI - Euclidean minimum spanning trees and bichromatic closest pairs
VL - 6
ER -
TY - JOUR
AB - 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.
AU - Aronov, Boris
AU - Chazelle, Bernard
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas J
AU - Sharir, Micha
AU - Wenger, Rephael
ID - 4062
IS - 1
JF - Discrete & Computational Geometry
TI - Points and triangles in the plane and halving planes in space
VL - 6
ER -
TY - CONF
AB - 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 ...
AU - Thomas Henzinger
AU - Manna, Zohar
AU - Pnueli,Amir
ID - 4508
TI - Temporal proof methodologies for real-time systems
ER -
TY - THES
AU - Thomas Henzinger
ID - 4516
TI - The Temporal Specification and Verification of Real-time Systems
ER -
TY - JOUR
AU - Alur, Rajeev
AU - Thomas Henzinger
ID - 4592
IS - 3
JF - SIGACT News
TI - Time for logic
VL - 22
ER -
TY - CONF
AU - Alur, Rajeev
AU - Feder, Tomás
AU - Thomas Henzinger
ID - 4621
TI - The benefits of relaxing punctuality
ER -
TY - JOUR
AB - 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.
AU - Zaǐtsev, Sergei V
AU - Leonid Sazanov
AU - Koshkin, Aleksei A
AU - Sud'Ina, Galina F
AU - Varfolomeev, Sergei D
ID - 1946
IS - 1
JF - FEBS Letters
TI - Respiratory burst inhibition in human neutrophils by ultra-low doses of [D-Ala2] methionine enkephalinamide
VL - 291
ER -
TY - JOUR
AB - 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.
AU - Peter Jonas
AU - Koh, Duk S
AU - Kampe, Knut
AU - Hermsteiner, Markus
AU - Vogel, Werner
ID - 3468
IS - 1-2
JF - Pflugers Archiv : European Journal of Physiology
TI - ATP-sensitive and Ca-activated K channels in vertebrate axons: novel links between metabolism and excitability
VL - 418
ER -
TY - CHAP
AU - Herbert Edelsbrunner
AU - Sharir, Micha
ID - 3566
T2 - Applied Geometry and Discrete Mathematics: The Victor Klee Festschrift
TI - A hyperplane incidence problem with applications to counting distances
VL - 4
ER -
TY - CHAP
AU - Herbert Edelsbrunner
ID - 3567
T2 - Discrete & Computational Geometry
TI - Lines in space – A collection of results
VL - 6
ER -
TY - JOUR
AB - 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.
AU - Szymura, Jacek M
AU - Nicholas Barton
ID - 3646
IS - 2
JF - Evolution
TI - The genetic structure of the hybrid zone between the fire-bellied toads Bombina bombina and B. variegata: comparisons between transects and between loci
VL - 45
ER -
TY - JOUR
AB - 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.
AU - Nicholas Barton
AU - Turelli, Michael
ID - 3647
IS - 1
JF - Genetics
TI - Natural and sexual selection on many loci
VL - 127
ER -
TY - JOUR
AB - 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.
AU - Nicholas Barton
AU - Rouhani, Shahin
ID - 3648
IS - 3
JF - Evolution
TI - The probability of fixation of a new karyotype in a continuous population
VL - 45
ER -
TY - JOUR
AB - Functional cDNA clones for rat neuromedin K receptor were isolated from a rat brain cDNA library by cross-hybridization with the bovine substance K recepor cDNA. Injection of the mRNA synthesized in vitro from the cloned cDNA into Xenopus oocytes elicited electrophysiological responses to tachykinins, with the most potent sensitivity being to neuromedin K. Ligand-binding displacement in membranes of mammalian COS cells transfected with the cDNA indicated the rank order of affinity of the receptor to tachykinins; neuromedin K > substance K > substance P. The hybridization analysis showed that the neuromedin K receptor mRNA is expressed in both the brain and the peripheral tissues at different levels. The rat neuromedin K receptor consists of 452 amino acid residues and belongs to the family of G protein-coupled receptors, which are thought to have seven transmembrane domains. The sequence comparison of the rat neuromedin K, substance P, and substance K receptors revealed that these receptors are highly conserved in the seven transmembrane domains and the cytoplasmic sides of the receptors. They also show some structural characteristics, including the common presence of histidine residues in transmembrane segments V and VI and the difference in the numbers and distributions of serine and threonine residues as possible phosphorylation sites in the cytoplasmic regions. This paper thus presents the first comprehensive analysis of the molecular nature of the multiple peptide receptors that exhibit similar but pharmacologically distinguishable activities.
AU - Ryuichi Shigemoto
AU - Yokota, Yoshifumi
AU - Tsuchida, Kunihiro
AU - Nakanishi, Shigetada
ID - 2480
IS - 2
JF - Journal of Biological Chemistry
TI - Cloning and expression of a rat neuromedin K receptor cDNA
VL - 265
ER -
TY - JOUR
AB - The family of mammalian tachykinin receptors consists of substance P receptor (SPR), neuromedin K receptor (NKR) and substance K receptor (SKR). In this investigation, tissue and regional distributions of the mRNAs for the three rat tachykinin receptors were investigated by blot-hybridization and RNase-protection analyses using the previously cloned receptor cDNAs. SPR mRNA is widely distributed in both the nervous system and peripheral tissues and is expressed abundantly in the hypothalamus and olfactory buld, as well as in the urinary bladder, salivary glands and small and large intestines. In contrast, NKR mRNA is predominantly expressed in the nervous system, particularly in the cortex, hypothalamus and cerebellum, whereas SKR mRNA expression is restricted to the peripheral tissues, being abundant in the urinary bladder, large intestine, stomach and adenal glands. Thus, the mRNAs for the three tachykinin receptors show distinct patterns of expression between the nervous system and peripheral tissues. Blot-hybridization analysis in combination with S1 nuclease protection and primer-extension analyses revealed that there are two large forms of SKR mRNA expressed commonly in the peripheral tissues, and two additional small forms of the mRNA expressed specifically in the adrenal gland and eye. These analyses also showed that the multiple forms of SKR mRNA differ in the lengths of the 5' mRNA portions, and that the two small forms of the mRNA, if translated, encode a truncated SKR polypeptide lacking the first two transmembrane domains. This investigation thus provides the comprehensive analysis of the distribution and mode of expression of the mRNAs for the multiple peptide receptors and offers a new basis on which to interpret the diverse functions of multiple tachykinin peptides in the CNS and peripheral tissues.
AU - Tsuchida, Kunihiro
AU - Ryuichi Shigemoto
AU - Yokota, Yoshifumi
AU - Nakanishi, Shigetada
ID - 2481
IS - 3
JF - European Journal of Biochemistry
TI - Tissue distribution and quantitation of the mRNAs for three rat tachykinin receptors
VL - 193
ER -
TY - JOUR
AB - We previously reported a novel rat membrane protein that exhibits a voltage-dependent potassium channel activity on the basis of molecular cloning combined with an electrophysiological assay. This protein, termed I(sK) protein, is small and different from the conventional potassium channel proteins but induces selective permeation of potassium ions on its expression in Xenopus oocytes. In this investigation, we examined cellular localization of rat I(sK) protein by preparing three different types of antibody that specifically reacts with a distinct part of rat I(sK) protein. Immunohistochemical analysis using these antibody preparations demonstrated that rat I(sK) protein is confined to the apical membrane portion of epithelial cells in the proximal tubule of the kidney, the submandibular duct and the uterine endometrium. The observed tissue distribution of rat I(sK) protein was consistent with that of the I(sK) protein mRNA determined by blot hybridization analysis. In epithelial cells, the sodium, potassium-ATPase pump in the basolateral membrane generates a sodium gradient across the epithelial cell and allows sodium ions to enter the cell through the apical membrane. Thus, taking into account the cellular localization of the I(sK) protein, together with its electrophysiological properties, we discussed a possible function of the I(sK) protein, namely that this protein is involved in potassium permeation in the apical membrane of epithelial cells through the depolarizing effect of sodium entry.
AU - Sugimoto, Tetsuo
AU - Tanabe, Yasuto
AU - Ryuichi Shigemoto
AU - Iwai, Masazumi
AU - Takumi, Toru
AU - Ohkubo, Hiroaki
AU - Nakanishi, Shigetada
ID - 2528
IS - 1
JF - Journal of Membrane Biology
TI - Immunohistochemical study of a rat membrane protein which induces a selective potassium permeation: Its localization in the apical membrane portion of epithelial cells
VL - 113
ER -
TY - JOUR
AB - This paper offers combinatorial results on extremum problems concerning the number of tetrahedra in a tetrahedrization of n points in general position in three dimensions, i.e. such that no four points are co-planar, It also presents an algorithm that in O(n log n) time constructs a tetrahedrization of a set of n points consisting of at most 3n-11 tetrahedra.
AU - Herbert Edelsbrunner
AU - Preparata, Franco P
AU - West, Douglas B
ID - 4060
IS - 3-4
JF - Journal of Symbolic Computation
TI - Tetrahedrizing point sets in three dimensions
VL - 10
ER -
TY - JOUR
AB - This paper describes a general-purpose programming technique, called Simulation of Simplicity, that can be used to cope with degenerate input data for geometric algorithms. It relieves the programmer from the task of providing a consistent treatment for every single special case that can occur. The programs that use the technique tend to be considerably smaller and more robust than those that do not use it. We believe that this technique will become a standard tool in writing geometric software.
AU - Herbert Edelsbrunner
AU - Mücke, Ernst P
ID - 4063
IS - 1
JF - ACM Transactions on Graphics
TI - Simulation of simplicity: A technique to cope with degenerate cases in geometric algorithms
VL - 9
ER -
TY - JOUR
AB - Given a set of data points pi = (xi, yi ) for 1 ≤ i ≤ n, the least median of squares regression line is a line y = ax + b for which the median of the squared residuals is a minimum over all choices of a and b. An algorithm is described that computes such a line in O(n 2) time and O(n) memory space, thus improving previous upper bounds on the problem. This algorithm is an application of a general method built on top of the topological sweep of line arrangements.
AU - Herbert Edelsbrunner
AU - Souvaine, Diane L
ID - 4064
IS - 409
JF - Journal of the American Statistical Association
TI - Computing least median of squares regression lines and guided topological sweep
VL - 85
ER -
TY - JOUR
AB - We prove that given n⩾3 convex, compact, and pairwise disjoint sets in the plane, they may be covered with n non-overlapping convex polygons with a total of not more than 6n−9 sides, and with not more than 3n−6 distinct slopes. Furthermore, we construct sets that require 6n−9 sides and 3n−6 slopes for n⩾3. The upper bound on the number of slopes implies a new bound on a recently studied transversal problem.
AU - Herbert Edelsbrunner
AU - Robison, Arch D
AU - Shen, Xiao-Jun
ID - 4065
IS - 2
JF - Discrete Mathematics
TI - Covering convex sets with non-overlapping polygons
VL - 81
ER -
TY - JOUR
AB - We consider several problems involving points and planes in three dimensions. Our main results are: (i) The maximum number of faces boundingm distinct cells in an arrangement ofn planes isO(m 2/3 n logn +n 2); we can calculatem such cells specified by a point in each, in worst-case timeO(m 2/3 n log3 n+n 2 logn). (ii) The maximum number of incidences betweenn planes andm vertices of their arrangement isO(m 2/3 n logn+n 2), but this number is onlyO(m 3/5– n 4/5+2 +m+n logm), for any>0, for any collection of points no three of which are collinear. (iii) For an arbitrary collection ofm points, we can calculate the number of incidences between them andn planes by a randomized algorithm whose expected time complexity isO((m 3/4– n 3/4+3 +m) log2 n+n logn logm) for any>0. (iv) Givenm points andn planes, we can find the plane lying immediately below each point in randomized expected timeO([m 3/4– n 3/4+3 +m] log2 n+n logn logm) for any>0. (v) The maximum number of facets (i.e., (d–1)-dimensional faces) boundingm distinct cells in an arrangement ofn hyperplanes ind dimensions,d>3, isO(m 2/3 n d/3 logn+n d–1). This is also an upper bound for the number of incidences betweenn hyperplanes ind dimensions andm vertices of their arrangement. The combinatorial bounds in (i) and (v) and the general bound in (ii) are almost tight.
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas
AU - Sharir, Micha
ID - 4066
IS - 1
JF - Discrete & Computational Geometry
TI - The complexity of many cells in arrangements of planes and related problems
VL - 5
ER -
TY - CONF
AB - This paper proves an O(m 2/3 n 2/3+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.
AU - Herbert Edelsbrunner
AU - Sharir, Micha
ID - 4067
TI - A hyperplane Incidence problem with applications to counting distances
VL - 450
ER -
TY - JOUR
AB - LetS be a collection ofn convex, closed, and pairwise nonintersecting sets in the Euclidean plane labeled from 1 ton. A pair of permutations
(i1i2in−1in)(inin−1i2i1)
is called ageometric permutation of S if there is a line that intersects all sets ofS in this order. We prove thatS can realize at most 2n–2 geometric permutations. This upper bound is tight.
AU - Herbert Edelsbrunner
AU - Sharir, Micha
ID - 4068
IS - 1
JF - Discrete & Computational Geometry
TI - The maximum number of ways to stabn convex nonintersecting sets in the plane is 2n−2
VL - 5
ER -
TY - JOUR
AB - Let C be a cell complex in d-dimensional Euclidean space whose faces are obtained by orthogonal projection of the faces of a convex polytope in d + 1 dimensions. For example, the Delaunay triangulation of a finite point set is such a cell complex. This paper shows that the in front/behind relation defined for the faces of C with respect to any fixed viewpoint x is acyclic. This result has applications to hidden line/surface removal and other problems in computational geometry.
AU - Herbert Edelsbrunner
ID - 4069
IS - 3
JF - Combinatorica
TI - An acyclicity theorem for cell complexes in d dimension
VL - 10
ER -
TY - JOUR
AB - Let S be a set of n closed intervals on the x-axis. A ranking assigns to each interval, s, a distinct rank, p(s) [1, 2,…,n]. We say that s can see t if p(s)<p(t) and there is a point ps∩t so that pu for all u with p(s)<p(u)<p(t). It is shown that a ranking can be found in time O(n log n) such that each interval sees at most three other intervals. It is also shown that a ranking that minimizes the average number of endpoints visible from an interval can be computed in time O(n 5/2). The results have applications to intersection problems for intervals, as well as to channel routing problems which arise in layouts of VLSI circuits.
AU - Herbert Edelsbrunner
AU - Overmars, Mark H
AU - Welzl, Emo
AU - Hartman, Irith Ben-Arroyo
AU - Feldman,Jack A
ID - 4070
IS - 3-4
JF - International Journal of Computer Mathematics
TI - Ranking intervals under visibility constraints
VL - 34
ER -
TY - CONF
AB - We show that a triangulation of a set of n points in the plane that minimizes the maximum angle can be computed in time O(n2 log n) and space O(n). In the same amount of time and space we can also handle the constrained case where edges are prescribed. The algorithm iteratively improves an arbitrary initial triangulation and is fairly easy to implement.
AU - Herbert Edelsbrunner
AU - Tan, Tiow Seng
AU - Waupotitsch, Roman
ID - 4071
TI - An O(n^2log n) time algorithm for the MinMax angle triangulation
ER -
TY - JOUR
AB - We show that the total number of edges ofm faces of an arrangement ofn lines in the plane isO(m 2/3– n 2/3+2 +n) for any>0. The proof takes an algorithmic approach, that is, we describe an algorithm for the calculation of thesem faces and derive the upper bound from the analysis of the algorithm. The algorithm uses randomization and its expected time complexity isO(m 2/3– n 2/3+2 logn+n logn logm). If instead of lines we have an arrangement ofn line segments, then the maximum number of edges ofm faces isO(m 2/3– n 2/3+2 +n (n) logm) for any>0, where(n) is the functional inverse of Ackermann's function. We give a (randomized) algorithm that produces these faces and takes expected timeO(m 2/3– n 2/3+2 log+n(n) log2 n logm).
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas J
AU - Sharir, Micha
ID - 4072
IS - 1
JF - Discrete & Computational Geometry
TI - The complexity and construction of many faces in arrangements of lines and of segments
VL - 5
ER -
TY - CONF
AB - A number of rendering algorithms in computer graphics sort three-dimensional objects by depth and assume that there is no cycle that makes the sorting impossible. One way to resolve the problem caused by cycles is to cut the objects into smaller pieces. The problem of estimating how many such cuts are always sufficient is addressed. A few related algorithmic and combinatorial geometry problems are considered
AU - Chazelle, Bernard
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas J
AU - Pollack, Richard
AU - Seidel, Raimund
AU - Sharir, Micha
AU - Snoeyink, Jack
ID - 4073
TI - Counting and cutting cycles of lines and rods in space
ER -
TY - JOUR
AU - Clarkson, Kenneth L
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas J
AU - Sharir, Micha
AU - Welzl, Emo
ID - 4074
IS - 1
JF - Discrete & Computational Geometry
TI - Combinatorial complexity bounds for arrangements of curves and spheres
VL - 5
ER -
TY - JOUR
AB - 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.
AU - Dobkin, David P
AU - Herbert Edelsbrunner
AU - Overmars, Mark H
ID - 4075
IS - 4
JF - Algorithmica
TI - Searching for empty convex polygons
VL - 5
ER -
TY - CONF
AB - 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.
AU - Agarwal, Pankaj K
AU - Herbert Edelsbrunner
AU - Schwarzkopf, Otfried
AU - Welzl, Emo
ID - 4076
TI - Euclidean minimum spanning trees and bichromatic closest pairs
ER -
TY - CONF
AB - 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.
AU - Aronov, Boris
AU - Chazelle, Bernard
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas J
AU - Sharir, Micha
AU - Wenger, Rephael
ID - 4077
TI - Points and triangles in the plane and halving planes in space
ER -
TY - CONF
AB - 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.
AU - Chazelle, Bernard
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas J
AU - Hershberger, John E
AU - Seidel, Raimund
AU - Sharir, Micha
ID - 4078
TI - Slimming down by adding; selecting heavily covered points
ER -
TY - GEN
AU - Nicholas Barton
AU - Jones, Steve
ID - 4310
T2 - Nature
TI - The language of the genes
VL - 346
ER -
TY - CHAP
AU - Nicholas Barton
AU - Clark,A.
ED - Wöhrmann, Klaus
ED - Jain, Subodh K
ID - 4311
T2 - Population biology: ecological and evolutionary viewpoints
TI - Population structure
ER -
TY - CONF
AB - 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.
AU - Thomas Henzinger
AU - Manna, Zohar
AU - Pnueli,Amir
ID - 4510
TI - An interleaving model for real time
ER -
TY - CONF
AU - Thomas Henzinger
ID - 4522
TI - Half-order modal logic: How to prove real-time properties
ER -
TY - CONF
AB - A unifying framework for the study of real-time logics is developed. In analogy to the untimed case, the underlying classical theory of timed state sequences is identified, it is shown to be nonelementarily decidable, and its complexity and expressiveness are used as a point of reference. Two orthogonal extensions of PTL (timed propositional temporal logic and metric temporal logic) that inherit its appeal are defined: they capture elementary, yet expressively complete, fragments of the theory of timed state sequences, and thus are excellent candidates for practical real-time specification languages
AU - Alur, Rajeev
AU - Thomas Henzinger
ID - 4597
TI - Real-time logics: Complexity and expressiveness
ER -
TY - JOUR
AB - We consider a multidimensional system consisting of a particle of mass M and radius r (molecule), surrounded by an infinite ideal gas of point particles of mass m (atoms). The molecule is confined to the unit ball and interacts with its boundary (barrier) via elastic collision, while the atoms are not affected by the boundary. We obtain convergence to equilibrium for the molecule from almost every initial distribution on its position and velocity. Furthermore, we prove that the infinite composite system of the molecule and the atoms is Bernoulli.
AU - László Erdös
AU - Tuyen, Dao Quang
ID - 2721
IS - 5-6
JF - Journal of Statistical Physics
TI - Ergodic properties of the multidimensional rayleigh gas with a semipermeable barrier
VL - 59
ER -
TY - JOUR
AB - 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.
AU - Bräu, Michael E
AU - Dreyer, Florian W
AU - Peter Jonas
AU - Repp, Holger
AU - Vogel, Werner
ID - 3467
JF - Journal of Physiology
TI - A K+ channel in Xenopus nerve fibres selectively blocked by bee and snake toxins: binding and voltage-clamp experiments
VL - 420
ER -
TY - CHAP
AU - Dobkin, David P
AU - Herbert Edelsbrunner
AU - Yap, Chee K
ED - Cox, Ingemar J
ED - Wilfong, Gordon T
ID - 3565
T2 - Autonomous Robot Vehicles
TI - Probing convex polytopes
ER -
TY - JOUR
AB - 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.
AU - Turelli, Michael
AU - Nicholas Barton
ID - 3649
IS - 1
JF - Theoretical Population Biology
TI - Dynamics of polygenic characters under selection
VL - 38
ER -
TY - JOUR
AB - 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.
AU - Mallet, James L
AU - Nicholas Barton
AU - Lamas,Gerado M
AU - Santisteban, José C
AU - Muedas, Manuel M
AU - Eeley, Harriet
ID - 3650
IS - 4
JF - Genetics
TI - Estimates of selection and gene flow from measures of cline width and linkage disequilibrium in Heliconius hybrid zones
VL - 124
ER -
TY - JOUR
AB - 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.
AU - Nicholas Barton
ID - 3651
IS - 3
JF - Genetics
TI - Pleiotropic models of quantitative variation
VL - 124
ER -
TY - JOUR
AB - 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.
AU - Kaneko, Takeshi
AU - Itoh, Kazuo
AU - Ryuichi Shigemoto
AU - Mizuno, Noboru
ID - 2479
IS - 1
JF - Neuroscience
TI - Glutaminase-like immunoreactivity in the lower brainstem and cerebellum of the adult rat
VL - 32
ER -
TY - JOUR
AB - 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.
AU - Yokota, Yoshifumi
AU - Sasai, Yoshiki
AU - Tanaka, Kohichi
AU - Fujiwara, Tsutomu
AU - Tsuchida, Kunihiro
AU - Ryuichi Shigemoto
AU - Kakizuka, Akira
AU - Ohkubo, Hiroaki
AU - Nakanishi, Shigetada
ID - 2525
IS - 30
JF - Journal of Biological Chemistry
TI - Molecular characterization of a functional cDNA for rat substance P receptor
VL - 264
ER -
TY - JOUR
AB - 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.
AU - Ino, Tadashi
AU - Itoh, Kazuo
AU - Kamiya, Hiroto
AU - Kaneko, Takeshi
AU - Ryuichi Shigemoto
AU - Akiguchi, Ichiro
AU - Mizuno, Noboru
ID - 2526
IS - 1
JF - Brain Research
TI - Direct projections from Ammon's horn to the rostral raphe regions in the brainstem of the cat
VL - 479
ER -
TY - JOUR
AU - Akimoto, Masumi
AU - Ryuichi Shigemoto
AU - Kawamura, Makiko
AU - Yamagata, Hideharu
AU - Kurihara, Takeshi
AU - Takata, S
AU - Miwa, Yoko
AU - Akagami, N
AU - Katsu, Kenichi
AU - Yamauchi, D
ID - 2527
IS - 11
JF - Japanese Journal of Gastroenterology
TI - Effect of endothelin on gastric mucosal blood flow in rat
VL - 86
ER -
TY - JOUR
AU - Herbert Edelsbrunner
AU - Skiena, Steven Sol
ID - 4079
IS - 7
JF - American Mathematical Monthly
TI - On the number of furthest neighbor pairs in a point set
VL - 96
ER -
TY - JOUR
AB - This paper proves that any set of n points in the plane contains two points such that any circle through those two points encloses at least n12−112+O(1)n47 points of the set. The main ingredients used in the proof of this result are edge counting formulas for k-order Voronoi diagrams and a lower bound on the minimum number of semispaces of size at most k.
AU - Herbert Edelsbrunner
AU - Hasan, Nany
AU - Seidel, Raimund
AU - Shen, Xiao-Jun
ID - 4080
IS - 1
JF - Geometriae Dedicata
TI - Circles through two points that always enclose many points
VL - 32
ER -
TY - JOUR
AB - This paper studies applications of envelopes of piecewise linear functions to problems in computational geometry. Among these applications we find problems involving hidden line/surface elimination, motion planning, transversals of polytopes, and a new type of Voronoi diagram for clusters of points. All results are either combinatorial or computational in nature. They are based on the combinatorial analysis in two companion papers [PS] and [E2] and a divide-and-conquer algorithm for computing envelopes described in this paper.
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas J
AU - Sharir, Micha
ID - 4081
IS - 1
JF - Discrete & Computational Geometry
TI - The upper envelope of piecewise linear functions: Algorithms and applications
VL - 4
ER -
TY - JOUR
AB - Sweeping a collection of figures in the Euclidean plane with a straight line is one of the novel algorithmic paradigms that have emerged in the field of computational geometry. In this paper we demonstrate the advantages of sweeping with a topological line that is not necessarily straight. We show how an arrangement of n lines in the plane can be swept over in O(n2) time and O(n) space by a such a line. In the process each element, i.e., vertex, edge, or region, is visited once in a consistent ordering. Our technique makes use of novel data structures which exhibit interesting amortized complexity behavior; the result is an algorithm that improves upon all its predecessors either in the space or the time bounds, as well as being eminently practical. Numerous applications of the technique to problems in computational geometry are given—many through the use of duality transforms. Examples include solving visibility problems, detecting degeneracies in configurations, computing the extremal shadows of convex polytopes, and others. Even though our basic technique solves a planar problem, its applications include several problems in higher dimensions.
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas J
ID - 4082
IS - 1
JF - Journal of Computer and System Sciences
TI - Topologically sweeping an arrangement
VL - 38
ER -
TY - JOUR
AB - It is shown that, given a set S of n points in $R^3 $, one can always find three planes that form an eight-partition of S, that is, a partition where at most ${n / 8}$ points of S lie in each of the eight open regions. This theorem is used to define a data structure, called an octant tree, for representing any point set in $R^3 $. An octant tree for n points occupies $O(n)$ space and can be constructed in polynomial time. With this data structure and its refinements, efficient solutions to various range query problems in two and three dimensions can be obtained, including (1) half-space queries: find all points of S that lie to one side of any given plane; (2) polyhedron queries: find all points that lie inside (outside) any given polyhedron; and (3) circle queries in $R^2 $: for a planar set S, find all points that lie inside (outside) any given circle. The retrieval time for all these queries is $T(n) = O(n^\alpha + m)$, where $\alpha = 0.8988$ (or 0.8471 in case (3)), and m is the size of the output. This performance is the best currently known for linear-space data structures that can be deterministically constructed in polynomial time.
AU - Yao, F. Frances
AU - Dobkin, David P
AU - Herbert Edelsbrunner
AU - Paterson,Michael S
ID - 4083
IS - 2
JF - SIAM Journal on Computing
TI - Partitioning space for range queries
VL - 18
ER -
TY - JOUR
AB - A tour of a finite set P of points is a necklace-tour if there are disks with the points in P as centers such that two disks intersect if and only if their centers are adjacent in . It has been observed by Sanders that a necklace-tour is an optimal traveling salesman tour.
In this paper, we present an algorithm that either reports that no necklace-tour exists or outputs a necklace-tour of a given set of n points in O(n2 log n) time. If a tour is given, then we can test in O(n2) time whether or not this tour is a necklace-tour. Both algorithms can be generalized to ƒ-factors of point sets in the plane. The complexity results rely on a combinatorial analysis of certain intersection graphs of disks defined for finite sets of points in the plane.
AU - Herbert Edelsbrunner
AU - Rote,Günter
AU - Welzl, Emo
ID - 4084
IS - 2
JF - Theoretical Computer Science
TI - Testing the necklace condition for shortest tours and optimal factors in the plane
VL - 66
ER -
TY - CONF
AB - Let C be a cell complex in d-dimensional Euclidean space whose faces are obtained by orthogonal projection of the faces of a convex polytope in d + 1 dimensions. For example, the Delaunay triangulation of a finite point set is such a cell complex. This paper shows that the in_front/behind relation defined for the faces of C with respect to any fixed viewpoint x is acyclic. This result has applications to hidden line/surface removal and other problems in computational geometry.
AU - Herbert Edelsbrunner
ID - 4085
TI - An acyclicity theorem for cell complexes in d dimension
ER -
TY - JOUR
AB - This note proves that the maximum number of faces (of any dimension) of the upper envelope of a set ofn possibly intersectingd-simplices ind+1 dimensions is (n d (n)). This is an extension of a result of Pach and Sharir [PS] who prove the same bound for the number ofd-dimensional faces of the upper envelope.
AU - Herbert Edelsbrunner
ID - 4086
IS - 4
JF - Discrete & Computational Geometry
TI - The upper envelope of piecewise linear functions: Tight bounds on the number of faces
VL - 4
ER -
TY - CONF
AB - This paper offers combinatorial results on extremum problems concerning the number of tetrahedra in a tetrahedrization of n points in general position in three dimensions, i.e. such that no four points are coplanar. It also presents an algorithm that in O(nlog n) time constructs a tetrahedrization of a set of n points consisting of at most 3n–11 tetrahedra.
AU - Herbert Edelsbrunner
AU - Preparata, Franco P
AU - West, Douglas B
ID - 4087
TI - Tetrahedrizing point sets in three dimensions
VL - 358
ER -
TY - JOUR
AB - Anarrangement ofn lines (or line segments) in the plane is the partition of the plane defined by these objects. Such an arrangement consists ofO(n 2) regions, calledfaces. In this paper we study the problem of calculating and storing arrangementsimplicitly, using subquadratic space and preprocessing, so that, given any query pointp, we can calculate efficiently the face containingp. First, we consider the case of lines and show that with (n) space1 and (n 3/2) preprocessing time, we can answer face queries in (n)+O(K) time, whereK is the output size. (The query time is achieved with high probability.) In the process, we solve three interesting subproblems: (1) given a set ofn points, find a straight-edge spanning tree of these points such that any line intersects only a few edges of the tree, (2) given a simple polygonal path , form a data structure from which we can find the convex hull of any subpath of quickly, and (3) given a set of points, organize them so that the convex hull of their subset lying above a query line can be found quickly. Second, using random sampling, we give a tradeoff between increasing space and decreasing query time. Third, we extend our structure to report faces in an arrangement of line segments in (n 1/3)+O(K) time, given(n 4/3) space and (n 5/3) preprocessing time. Lastly, we note that our techniques allow us to computem faces in an arrangement ofn lines in time (m 2/3 n 2/3+n), which is nearly optimal.
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas
AU - Hershberger, John
AU - Seidel, Raimund
AU - Sharir, Micha
AU - Snoeyink, Jack
AU - Welzl, Emo
ID - 4088
IS - 1
JF - Discrete & Computational Geometry
TI - Implicitly representing arrangements of lines or segments
VL - 4
ER -
TY - JOUR
AB - Motivated by a number of motion-planning questions, we investigate in this paper some general topological and combinatorial properties of the boundary of the union ofn regions bounded by Jordan curves in the plane. We show that, under some fairly weak conditions, a simply connected surface can be constructed that exactly covers this union and whose boundary has combinatorial complexity that is nearly linear, even though the covered region can have quadratic complexity. In the case where our regions are delimited by Jordan acrs in the upper halfplane starting and ending on thex-axis such that any pair of arcs intersect in at most three points, we prove that the total number of subarcs that appear on the boundary of the union is only (n(n)), where(n) is the extremely slowly growing functional inverse of Ackermann's function.
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas
AU - Hershberger, John
AU - Pach, János
AU - Pollack, Richard
AU - Seidel, Raimund
AU - Sharir, Micha
AU - Snoeyink, Jack
ID - 4089
IS - 1
JF - Discrete & Computational Geometry
TI - On arrangements of Jordan arcs with three intersections per pair
VL - 4
ER -
TY - CONF
AU - Chazelle, Bernard
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas J
AU - Sharir, Micha
ID - 4092
TI - A singly exponential stratification scheme for real semi-algebraic varieties and its applications
VL - 372
ER -
TY - JOUR
AB - This paper investigates the combinatorial and computational aspects of certain extremal geometric problems in two and three dimensions. Specifically, we examine the problem of intersecting a convex subdivision with a line in order to maximize the number of intersections. A similar problem is to maximize the number of intersected facets in a cross-section of a three-dimensional convex polytope. Related problems concern maximum chains in certain families of posets defined over the regions of a convex subdivision. In most cases we are able to prove sharp bounds on the asymptotic behavior of the corresponding extremal functions. We also describe polynomial algorithms for all the problems discussed.
AU - Chazelle, Bernard
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas J
ID - 4093
IS - 1
JF - Discrete & Computational Geometry
TI - The complexity of cutting complexes
VL - 4
ER -
TY - JOUR
AB - Three methods for estimating the average level of gene flow in natural population are discussed and compared. The three methods are FST, rare alleles, and maximum likelihood. All three methods yield estimates of the combination of parameters (the number of migrants [Nm] in a demic model or the neighborhood size [4πDσ2] in a continuum model) that determines the relative importance of gene flow and genetic drift. We review the theory underlying these methods and derive new analytic results for the expectation of FST in stepping-stone and continuum models when small sets of samples are taken. We also compare the effectiveness of the different methods using a variety of simulated data. We found that the FST and rare-alleles methods yield comparable estimates under a wide variety of conditions when the population being sampled is demographically stable. They are roughly equally sensitive to selection and to variation in population structure, and they approach their equilibrium values at approximately the same rate. We found that two different maximum-likelihood methods tend to yield biased estimates when relatively small numbers of locations are sampled but more accurate estimates when larger numbers are sampled. Our conclusion is that, although FST and rare-alleles methods are expected to be equally effective in analyzing ideal data, practical problems in estimating the frequencies of rare alleles in electrophoretic studies suggest that FST is likely to be more useful under realistic conditions.
AU - Slatkin, Montgomery
AU - Nicholas Barton
ID - 4309
IS - 7
JF - Evolution; International Journal of Organic Evolution
TI - A comparison of three methods for estimating average levels of gene flow
VL - 43
ER -
TY - JOUR
AU - Nicholas Barton
AU - Turelli, Michael
ID - 4312
JF - Annual Review of Genetics
TI - Evolutionary quantitative genetics: how little do we know ?
VL - 23
ER -
TY - CHAP
AU - Nicholas Barton
ED - Otte, Daniel
ED - Endler, John A
ID - 4313
T2 - Speciation and its consequences
TI - Founder effect speciation
ER -
TY - JOUR
AB - Polygenic variation can be maintained by a balance between mutation and stabilizing selection. When the alleles responsible for variation are rare, many classes of equilibria may be stable. The rate at which drift causes shifts between equilibria is investigated by integrating the gene frequency distribution W2N II (pq)4N mu-1. This integral can be found exactly, by numerical integration, or can be approximated by assuming that the full distribution of allele frequencies is approximately Gaussian. These methods are checked against simulations. Over a wide range of population sizes, drift will keep the population near an equilibrium which minimizes the genetic variance and the deviation from the selective optimum. Shifts between equilibria in this class occur at an appreciable rate if the product of population size and selection on each locus is small (Ns alpha 2 less than 10). The Gaussian approximation is accurate even when the underlying distribution is strongly skewed. Reproductive isolation evolves as populations shift to new combinations of alleles: however, this process is slow, approaching the neutral rate (approximately mu) in small populations.
AU - Nicholas Barton
ID - 4314
IS - 1
JF - Genetical Research
TI - The divergence of a polygenic system under stabilising selection, mutation and drift
VL - 54
ER -
TY - CONF
AB - 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.
AU - Alur, Rajeev
AU - Thomas Henzinger
ID - 4596
TI - A really temporal logic
ER -
TY - JOUR
AB - 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.
AU - Peter Jonas
ID - 3465
IS - 3
JF - Journal of Membrane Biology
TI - Temperature dependence of gating current in myelinated nerve fibers
VL - 112
ER -
TY - JOUR
AB - 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.
AU - Peter Jonas
AU - Bräu, Michael E
AU - Hermsteiner, Markus
AU - Vogel, Werner
ID - 3466
IS - 18
JF - PNAS
TI - Single-channel recording in myelinated nerve fibers reveals one type of Na channel but different K channels
VL - 86
ER -
TY - CONF
AU - Herbert Edelsbrunner
ID - 3549
TI - Spatial triangulations with dihedral angle conditions
ER -
TY - JOUR
AB - 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 {complex}s/{complex}8 {sigma} and {complex}s/{complex}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 frequences and of gametic correlations from a hybrid zone.
AU - Mallet, James L
AU - Nicholas Barton
ID - 3652
IS - 4
JF - Genetics
TI - Inference from clines stabilized by frequency-dependent selection
VL - 122
ER -
TY - JOUR
AB - 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.
AU - Mallet, James L
AU - Nicholas Barton
ID - 3653
JF - Evolution
TI - Strong natural selection in a warning color hybrid zone
VL - 43
ER -
TY - JOUR
AB - 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.
AU - Nicholas Barton
AU - Hewitt, Godfrey M
ID - 3654
JF - Nature
TI - Adaptation, speciation and hybrid zones
VL - 341
ER -
TY - JOUR
AB - Non-pyramidal neurons in cat Ammon's horn were shown to send their axons to the supramammillary regions (SMR), i.e. the supramammillary nucleus and its vicinities including the supramammillary nucleus and the lateral, posterior and dorsal hypothalamic areas: wheat germ agglutinin-horseradish peroxidase (WGA-HRP) injection into Ammon's horn resulted in labeling of presumed axon terminals in the SMR; and after injecting HRP into the SMR, retrogradely labeled non-pyramidal neurons were seen in Ammon's horn.
AU - Ino, Tadashi
AU - Itoh, Kazuo
AU - Kamiya, Hiroto
AU - Ryuichi Shigemoto
AU - Akiguchi, Ichiro
AU - Mizuno, Noboru
ID - 2522
IS - 1
JF - Brain Research
TI - Direct projections of non-pyramidal neurons of Ammon's horn to the supramammillary region in the cat
VL - 460
ER -
TY - JOUR
AB - Injection of large amounts of a mixture of horseradish peroxidase and wheat germ agglutinin-horseradish peroxidase conjugate into the upper cervical segments of the spinal cord in the Japanese monkey (Macaca fuscata) led to the retrograde labeling of a small number of neuronal cell bodies within the rostral part of the subthalamic nucleus of Luys. Direct projection from the subthalamic nucleus to the spinal cord appeared to be much less prominent in the Japanese monkey than in the cat and rat.
AU - Mizuno, Noboru
AU - Ueyama, Teizo
AU - Itoh, Kazuo
AU - Satoda, Takahiro
AU - Tashiro, Takashi
AU - Ryuichi Shigemoto
ID - 2523
IS - 1
JF - Neuroscience Letters
TI - Direct projections from the subthalamic nucleus of Luys to the spinal cord in the Japanese monkey
VL - 89
ER -
TY - JOUR
AB - Alpha-ketoglutamate (α-KG) reductive amination activity in rat brain was found to be mostly absorbed with an antibody against liver glutamate dehydrogenase. With this and anti-glutamine synthetase antibodies, α-KG reductive amination activity was immunocytochemically shown to coexist with glutamine synthetase activity in astrocytes. The results suggest that astrocytes de novo synthesize glutamate from α-KG and ammonia, and metabolize it to glutamine.
AU - Kaneko, Takeshi
AU - Ryuichi Shigemoto
AU - Mizuno, Noboru
ID - 2524
IS - 1
JF - Brain Research
TI - Metabolism of glutamate and ammonia in astrocyte an immunocytochemical study
VL - 457
ER -
TY - JOUR
AB - In this paper we study the problem of polygonal separation in the plane, i.e., finding a convex polygon with minimum number k of sides separating two given finite point sets (k-separator), if it exists. We show that for k = Θ(n), is a lower bound to the running time of any algorithm for this problem, and exhibit two algorithms of distinctly different flavors. The first relies on an O(n log n)-time preprocessing task, which constructs the convex hull of the internal set and a nested star-shaped polygon determined by the external set; the k-separator is contained in the annulus between the boundaries of these two polygons and is constructed in additional linear time. The second algorithm adapts the prune-and-search approach, and constructs, in each iteration, one side of the separator; its running time is O(kn), but the separator may have one more side than the minimum.
AU - Herbert Edelsbrunner
AU - Preparata, Franco P
ID - 4090
IS - 3
JF - Information and Computation
TI - Minimum polygonal separation
VL - 77
ER -
TY - JOUR
AB - An X-ray probe through a polygon measures the length of intersection between a line and the polygon. This paper considers the properties of various classes of X-ray probes, and shows how they interact to give finite strategies for completely describing convex n-gons. It is shown that (3n/2)+6 probes are sufficient to verify a specified n-gon, while for determining convex polygons (3n-1)/2 X-ray probes are necesssary and 5n+O(1) sufficient, with 3n+O(1) sufficient given that a lower bound on the size of the smallest edge of P is known.
AU - Herbert Edelsbrunner
AU - Skiena,Steven S
ID - 4091
IS - 5
JF - SIAM Journal on Computing
TI - Probing convex polygons with X-Rays
VL - 17
ER -
TY - CONF
AU - Herbert Edelsbrunner
ID - 4096
TI - Geometric structures in computational geometry
VL - 317
ER -
TY - CONF
AB - Arrangements of curves in the plane are of fundamental significance in many problems of computational and combinatorial geometry (e.g. motion planning, algebraic cell decomposition, etc.). In this paper we study various topological and combinatorial properties of such arrangements under some mild assumptions on the shape of the curves, and develop basic tools for the construction, manipulation, and analysis of these arrangements. Our main results include a generalization of the zone theorem of [EOS], [CGL] to arrangements of curves (in which we show that the combinatorial complexity of the zone of a curve is nearly linear in the number of curves), and an application of (some weaker variant of) that theorem to obtain a nearly quadratic incremental algorithm for the construction of such arrangements.
AU - Herbert Edelsbrunner
AU - Guibas, Leonidas
AU - Pach, János
AU - Pollack, Richard
AU - Seidel, Raimund
AU - Sharir, Micha
ID - 4097
TI - Arrangements of curves in the plane - topology, combinatorics, and algorithms
VL - 317
ER -
TY - GEN
AU - Coyne, Jerry A
AU - Nicholas Barton
ID - 4315
T2 - Nature
TI - What do we know about speciation ?
VL - 331
ER -