@article{4305, abstract = {The common shrew (Sorex araneus) is subdivided into several karyotypic races in Britain. Two of these races meet near Oxford to form the "Oxford-Hermitage" hybrid zone. We present a model which describes this system as a "tension zone," i.e., a set of clines maintained by a balance between dispersal and selection against chromosomal heterozygotes. The Oxford and Hermitage races differ by Robertsonian fusions with monobrachial homology (kq, no versus ko), and so F1 hybrids between them would have low fertility. However, the acrocentric karyotype is found at high frequency within the hybrid zone, so that complex Robertsonian heterozygotes (kq no/q ko n) are replaced by more fertile combinations, such as (kq no/k q n o). This suggests that the hybrid zone has been modified so as to increase hybrid fitness. Mathematical analysis and simulation show that, if selection against complex heterozygotes is sufficiently strong relative to selection against simple heterozygotes, acrocentrics increase, and displace the clines for kq and no from the cline for ko. Superimposed on this separation is a tendency for the hybrid zone to move m favor of the Oxford (kq no) race. We compare the model with estimates of linkage disequilibrium and cline shape made from field data.}, author = {Hatfield, Todd and Barton, Nicholas H and Searle, Jeremy}, issn = {1558-5646}, journal = {Evolution; International Journal of Organic Evolution}, number = {4}, pages = {1129 -- 1145}, publisher = {Wiley-Blackwell}, title = {{A model of a hybrid zone between two chromosomal races of the common shrew (Sorex araneus)}}, doi = {10.1111/j.1558-5646.1992.tb00624.x}, volume = {46}, year = {1992}, } @misc{4306, author = {Barton, Nicholas H and Goldman, Nick}, booktitle = {Nature}, pages = {440 -- 441}, publisher = {Nature Publishing Group}, title = {{Genetics and geography}}, doi = {10.1038/357440a0}, volume = {357}, year = {1992}, } @inbook{4307, author = {Barton, Nicholas H}, booktitle = {Animal dispersal: small mammals as a model}, editor = {Stenseth, Nils and Lidicker, William}, pages = {37 -- 60}, publisher = {Chapman Hall}, title = {{The genetic consequences of dispersal}}, doi = {10.1007/978-94-011-2338-9_3}, year = {1992}, } @article{4308, author = {Barton, Nicholas H}, issn = {1558-5646}, journal = {Evolution; International Journal of Organic Evolution}, number = {2}, pages = {551 -- 557}, publisher = {Wiley-Blackwell}, title = {{On the spread of new gene combinations in the third phase of Wright's shifting balance}}, volume = {46}, year = {1992}, } @inproceedings{4504, abstract = {Real-time systems operate in “real,” continuous time and state changes may occur at any real-numbered time point. Yet many verification methods are based on the assumption that states are observed at integer time points only. What can we conclude if a real-time system has been shown “correct” for integral observations? Integer time verification techniques suffice if the problem of whether all real-numbered behaviors of a system satisfy a property can be reduced to the question of whether the integral observations satisfy a (possibly modified) property. We show that this reduction is possible for a large and important class of systems and properties: the class of systems includes all systems that can be modeled as timed transition systems; the class of properties includes time-bounded invariance and time-bounded response.}, author = {Henzinger, Thomas A and Manna, Zohar and Pnueli, Amir}, booktitle = {19th International Colloquium on Automata, Languages and Programming}, location = {Vienna, Austria}, pages = {545 -- 558}, publisher = {Springer}, title = {{What good are digital clocks?}}, doi = {10.1007/3-540-55719-9_103}, volume = {623}, year = {1992}, } @inproceedings{4505, abstract = {We describe finite-state programs over real-numbered time in a guarded-command language with real-valued clocks or, equivalently, as finite automata with real-valued clocks. Model checking answers the question which states of a real-time program satisfy a branching-time specification (given in an extension of CTL with clock variables). We develop an algorithm that computes this set of states symbolically as a fixpoint of a functional on state predicates, without constructing the state space. For this purpose, we introduce a mu-calculus on computation trees over real-numbered time. Unfortunately, many standard program properties, such as response for all nonzeno execution sequences (during which time diverges), cannot be characterized by fixpoints: we show that the expressiveness of the timed mu-calculus is incomparable to the expressiveness of timed CTL. Fortunately, this result does not impair the symbolic verification of "implementable" real-time programs--those whose safety constraints are machine-closed with respect to diverging time and whose fairness constraints are restricted to finite upper bounds on clock values. All timed CTL properties of such programs are shown to be computable as finitely approximable fixpoints in a simple decidable theory.}, author = {Henzinger, Thomas A and Nicollin, Xavier and Sifakis, Joseph and Yovine, Sergio}, booktitle = {Proceedings of the 7th Annual IEEE Symposium on Logic in Computer Science}, isbn = {0-8186-2735-2}, location = {Santa Cruz, CA, United States of America}, pages = {394 -- 406}, publisher = {IEEE}, title = {{Symbolic model checking for real-time systems}}, doi = {10.1109/LICS.1992.185551}, year = {1992}, } @inbook{4507, abstract = {We incorporate time into an interleaving model of concurrency. In timed transition systems, the qualitative fairness requirements of traditional transition system are replaced (and superseded) by quantitative lower-bound and upperbound timing constraints on transitions. The purpose of this paper is to explore the scope of applicability for the abstract model of timed transition systems. We demonstrate that the model can represent a wide variety of phenomena that routinely occur in conjunction with the timed execution of concurrent processes. Our treatment covers both processes that are executed in parallel on separate processors and communicate either through shared variables or by message passing, and processes that time-share a limited number of processors under a given scheduling policy. Often it is this scheduling policy that determines if a system meets its real-time requirements. Thus we explicitly address such questions as time-outs, interrupts, static and dynamic priorities.}, author = {Henzinger, Thomas A and Manna, Zohar and Pnueli, Amir}, booktitle = {Real Time: Theory in Practice}, pages = {226 -- 251}, publisher = {Springer}, title = {{Timed transition systems}}, doi = {10.1007/BFb0031995}, volume = {600}, year = {1992}, } @article{4517, abstract = {It has been observed repeatedly that the standard safety-liveness classification for properties of reactive systems does not fit for real-time properties. This is because the implicit “liveliness” of time shifts the spectrum towards the safety side. While, for example, response—that “something good” will happen eventually—is a classical liveness property, bounded response—that “something good” will happen soon, within a certain amount of time—has many characteristics of safety. We account for this phenomenon formally by defining safety and liveness relative to a given condition, such as the progress of time.}, author = {Henzinger, Thomas A}, issn = {0020-0190}, journal = {Information Processing Letters}, number = {3}, pages = {135 -- 141}, publisher = {Elsevier}, title = {{Sooner Is Safer Than Later}}, doi = {10.1016/0020-0190(92)90005-G}, volume = {43}, year = {1992}, } @inproceedings{4593, abstract = {We survey logic-based and automata-based languages and techniques for the specification and verification of real-time systems. In particular, we discuss three syntactic extensions of temporal logic: time-bounded operators, freeze quantification, and time variables. We also discuss the extension of finite-state machines with clocks and the extension of transition systems with time bounds on the transitions. All of the resulting notations can be interpreted over a variety of different models of time and computation, including linear and branching time, interleaving and true concurrency, discrete and continuous time. For each choice of syntax and semantics, we summarize the results that are known about expressive power, algorithmic finite-state verification, and deductive verification.}, author = {Alur, Rajeev and Henzinger, Thomas A}, booktitle = {REX Workshop on Real Time: Theory in Practice}, location = {Mook, The Netherlands}, pages = {74 -- 106}, publisher = {Springer}, title = {{Logics and models of real time: A survey}}, doi = {10.1007/BFb0031984}, volume = {600}, year = {1992}, } @inproceedings{4594, abstract = {The authors introduce two-way timed automata-timed automata that can move back and forth while reading a timed word. Two-wayness in its unrestricted form leads, like nondeterminism, to the undecidability of language inclusion. However, if they restrict the number of times an input symbol may be revisited, then two-wayness is both harmless and desirable. The authors show that the resulting class of bounded two-way deterministic timed automata is closed under all boolean operations, has decidable (PSPACE-complete) emptiness and inclusion problems, and subsumes all decidable real-time logics we know. They obtain a strict hierarchy of real-time properties: deterministic timed automata can accept more languages as the bound on the number of times an input symbol may be revisited is increased. This hierarchy is also enforced by the number of alternations between past and future operators in temporal logic. The combination of the results leads to a decision procedure for a real-time logic with past operators }, author = {Alur, Rajeev and Henzinger, Thomas A}, booktitle = {Proceedings of the 33rd Annual Symposium on Foundations of Computer Science}, location = {Pittsburgh, PA, United States of America}, pages = {177 -- 186}, publisher = {IEEE}, title = {{Back to the future: Towards a theory of timed regular languages}}, doi = {10.1109/SFCS.1992.267774}, year = {1992}, } @article{2484, abstract = {Three cDNA clones, mGluR2, mGluR3, and mGluR4, were isolated from a rat brain cDNA library by cross-hybridization with the cDNA for a metabotropic glutamate receptor (mGluR1). The cloned receptors show considerable sequence similarity with mGluR1 and possess a large extracellular domain preceding the seven putative membrane-spanning segments. mGluR2 is expressed in some particular neuronal cells different from those expressing mGluR1 and mediates an efficient inhibition of forskolin-stimulated cAMP formation in cDNA- transfected cells. The mGluRs thus form a novel family of G protein-coupled receptors that differ in their signal transduction and expression patterns.}, author = {Tanabe, Yasuto and Masu, Masayuki and Ishii, Takahiro and Shigemoto, Ryuichi and Nakanishi, Shigetada}, issn = {0896-6273}, journal = {Neuron}, number = {1}, pages = {169 -- 179}, publisher = {Elsevier}, title = {{A family of metabotropic glutamate receptors}}, doi = {10.1016/0896-6273(92)90118-W}, volume = {8}, year = {1992}, } @article{2485, abstract = {Endothelins (ETs) are very potent vasoconstrictive peptides and have diverse functions in both vascular and nonvascular tissues. This investigation concerns the tissue distribution and cellular localization of rat mRNAs encoding two different subtypes of ET receptors (ET(A) and ET(B)). We isolated 46 cDNA clones from a rat lung cDNA library by hybridization with the bovine ET(A) cDNA. The characterization of these cDNA clones indicated that they represent either the ET(A) or ET(B) cDNA. In situ and blot hybridization analyses revealed that the rat ET(A) mRNA is predominantly expressed in vascular smooth muscle cells of a variety of tissues, bronchial smooth muscle cells, myocardium, and the pituitary gland. There is no significant expression of ET(B) mRNA in vascular smooth muscle cells, and ET(A), thus, plays a primary role in ET-induced vascular contraction. ET(B) mRNA is more widely distributed in various cell types of many tissues. Its prominent expression is seen in glial cells throughout the brain regions, epithelial cells of the choroid plexus, ependymal cells lining the ventricle, myocardium, endothelial cells of glomeruli, and epithelial cells of the thin segments of Henle's loops. Our investigation demonstrates that the mRNAs for the two subtypes of rat ET receptors show specialized expression patterns of cell types in both brain and peripheral tissues.}, author = {Hori, Seiji and Komatsu, Yasato and Shigemoto, Ryuichi and Mizuno, Noboru and Nakanishi, Shigetada}, issn = {0013-7227}, journal = {Endocrinology}, number = {4}, pages = {1885 -- 1895}, publisher = {The Endocrine Society}, title = {{Distinct tissue distribution and cellular localization of two messenger ribonucleic acids encoding different subtypes of rat endothelin receptors}}, doi = {10.1210/endo.130.4.1312429}, volume = {130}, year = {1992}, } @article{2486, abstract = {Distribution of the mRNA for a metabotropic glutamate receptor (mGluR1), which is linked to phosphoinositide (PI) hydrolysis, was investigated in adult and developing rat central nervous system (CNS) by in situ hybridization. Transcripts of mGluR1 were specifically localized to neurons and widely distributed throughout the adult rat brain. Most intensely labeled neurons were Purkinje cells of the cerebellum, mitral and tufted cells of the olfactory bulb, and neurons in the hippocampus, lateral septum, thalamus, globus pallidus, entopeduncular nucleus, ventral pallidum, magnocellular preoptic nucleus, substantia nigra, and dorsal cochlear nucleus. Moderately labeled neurons were seen in high density in the dentate gyrus, striatum, islands of Calleja, superficial layers of the retrosplenial, cingulate and entorhinal cortices, mammillary nuclei, red nucleus, and superior colliculus. In the developing rat brain, the level of mGluR1 expression gradually increased during early postnatal days in accordance with the maturation of neuronal elements. These results show prominent expression of mGluR1 in the major targets of putative glutamatergic pathways and unique distribution pattern of mGluR1 distinct from those reported for ionotropic subtypes of glutamate receptors, suggesting specific roles of mGluR1 in the glutamatergic system.}, author = {Shigemoto, Ryuichi and Nakanishi, Shigetada and Mizuno, Noboru}, issn = {0021-9967}, journal = {Journal of Comparative Neurology}, number = {1}, pages = {121 -- 135}, publisher = {Wiley-Blackwell}, title = {{Distribution of the mRNA for a metabotropic glutamate receptor (mGluR1) in the central nervous system: An in situ hybridization study in adult and developing rat}}, doi = {10.1002/cne.903220110}, volume = {322}, year = {1992}, } @article{2531, abstract = {The distribution of NMDA receptor (NMDAR1) on neurons in the peripheral ganglia was examined in the adult rat by in situ hybridization. NMDAR1 mRNA was expressed in all neurons in the sensory and autonomic ganglia examined; in the dorsal root, trigeminal, nodose, superior cervical, and sphenopalatine ganglia. Possible roles of the NMDA receptor on the sensory and autonomic ganglion neurons are discussed.}, author = {Shigemoto, Ryuichi and Ohishi, Hitoshi and Nakanishi, Shigetada and Mizuno, Noboru}, issn = {0304-3940}, journal = {Neuroscience Letters}, number = {1-2}, pages = {229 -- 232}, publisher = {Elsevier}, title = {{Expression of the mRNA for the rat NMDA receptor (NMDAR1) in the sensory and autonomic ganglion neurons}}, doi = {10.1016/0304-3940(92)90756-W}, volume = {144}, year = {1992}, } @article{2532, abstract = {In the present study, we have investigated the expression of both the erythrocyte-type (GLUT1) and the brain-type (GLUT3) glucose transporter isoforms in primary human brain tumors. In situ hybridization made it possible to localize and semiquantify both GLUT1 and GLUT3 mRNAs of individual cells in all 18 samples examined. More signals for GLUT3 mRNA than for GLUT1 mRNA were found over astrocytoma cells, while the reverse was the case in all 6 meningiomas. In astrocytomas, for both mRNAs, the density of silver grains over tumor cells was well correlated with the malignancy of the cells. This correlation was, as was also confirmed by Northern blot analysis, more marked with GLUT3 mRNA than with GLUT1 mRNA. In 2 of 5 anaplastic astrocytomas and in all 3 glioblastomas, numerous tumor cells with large amounts of both mRNAs tended to surround the perivascular regions. 'Tumor vessels' with endothelial proliferation, an almost pathognomonic feature of glioblastomas, expressed much GLUT3 mRNA but no significant GLUT1 mRNA, while a single- or a few-layered capillary endothelium expressed much GLUT1 mRNA. The distribution of both mRNAs was in good accordance with that of both proteins. Our results suggest that the expression of both glucose transporter isoforms may contribute to the maintenance of human brain tumors and that the expression of the GLUT3 isoform may be closely related to the malignant change of astrocytomas and particularly related to the aberrant neovascularization which accompanies glioblastomas.}, author = {Nishioka, Tatsuya and Oda, Yoshifumi and Seino, Yutaka and Yamamoto, Taizo and Inagaki, Nobuya and Yano, Hideki and Imura, Hiroo and Shigemoto, Ryuichi and Kikuchi, Haruhiko}, issn = {0008-5472}, journal = {Cancer Research}, number = {14}, pages = {3972 -- 3979}, publisher = {American Association for Cancer Research}, title = {{Distribution of the glucose transporters in human brain tumors}}, volume = {52}, year = {1992}, } @article{2533, abstract = {A cDNA clone for a new metabotropic glutamate receptor, mGluR5, was isolated through polymerase chain reaction-mediated DNA amplification by using primer sequences conserved among the metabotropic glutamate receptor (mGluR) family and by the subsequent screening of a rat brain cDNA library. The cloned receptor consists of 1171 amino acid residues and exhibits a structural architecture common to the mGluR family, possessing a large extracellular domain preceding the seven putative membrane-spanning segments. mGluR5 shows the highest sequence similarity to mGluR1 among the mGluR members and is coupled to the stimulation of phosphatidylinositol hydrolysis/ Ca2+ signal transduction in Chinese hamster ovary cells transfected with the cloned cDNA. This receptor also resembles mGluR1 in its agonist selectivity and antagonist responses; the potency rank order of agonists for mGluR5 was determined to be quisqualate > L-glutamate ≥ ibotenate > trans-1-aminocyclopentane-1,3-dicarboxylate. Blot and in situ hybridization analyses indicated that mGluR5 mRNA is widely distributed in neuronal cells of the central nervous system and is expressed differently from mGluR1 mRNA in many brain regions. This investigation thus demonstrates that there is an additional mGluR subtype which closely resembles mGluR1 in its signal transduction and pharmacological properties and is expressed in specialized neuronal cells in the central nervous system.}, author = {Abe, Takaaki and Sugihara, Hidemitsu and Nawa, Hiroyuki and Shigemoto, Ryuichi and Mizuno, Noboru and Nakanishi, Shigetada}, issn = {0021-9258}, journal = {Journal of Biological Chemistry}, number = {19}, pages = {13361 -- 13368}, publisher = {American Society for Biochemistry and Molecular Biology}, title = {{Molecular characterization of a novel metabotropic glutamate receptor mGluR5 coupled to inositol phosphate/Ca2+ signal transduction}}, doi = {10.1016/S0021-9258(18)42219-3}, volume = {267}, year = {1992}, } @article{2534, abstract = {Vasoactive intestinal polypeptide (VIP), a 28 amino acid peptide hormone, plays many physiological roles in the peripheral and central nerve systems. A functional cDNA clone of the VIP receptor was isolated from a rat lung cDNA library by cross-hybridization with the secretin receptor cDNA. VIP bound the cloned VIP receptor expressed in mouse COP cells and stimulated adenylate cyclase through the cloned receptor. The rat VIP receptor consists of 459 amino acids with a calculated Mr of 52,054 and contains seven transmembrane segments. It is structurally related to the secretin, calcitonin, and parathyroid hormone receptors, suggesting that they constitute a new subfamily of the G5 protein - coupled receptors. VIP receptor mRNA was detected in various rat tissues including liver, lung, intestines, and brain. In situ hybridization revealed that VIP receptor mRNA is widely distributed in neuronal cells of the adult rat brain, with a relatively high expression in the cerebral cortex and hippocampus.}, author = {Ishihara, Takeshi and Shigemoto, Ryuichi and Mori, Kensaku and Takahashi, Kenji and Nagata, Shigekazu}, issn = {0896-6273}, journal = {Neuron}, number = {4}, pages = {811 -- 819}, publisher = {Elsevier}, title = {{Functional expression and tissue distribution of a novel receptor for vasoactive intestinal polypeptide}}, doi = {10.1016/0896-6273(92)90101-I}, volume = {8}, year = {1992}, } @article{2535, abstract = {We report the molecular characterization of two novel rat helix-loop-helix (HLH) proteins, designated HES-1 and HES-3, that show structural homology to the Drosophila hairy and Enhancer of split [E(spl)] proteins, both of which are required for normal neurogenesis. HES-1 mRNA, expressed in various tissues of both embryos and adults, is present at a high level in the epithelial cells, including the embryonal neuroepithelial cells, as well as in the mesoderm-derived tissues such as the embryonal muscle. In contrast, HES-3 mRNA is produced exclusively in cerebellar Purkinje cells. HES-1 represses transcription by binding to the N box, which is a recognition sequence of E(spl) proteins. Interestingly, neither HES-1 nor HES-3 alone interacts efficiently with the E box, but each protein decreases the transcription induced by E-box-binding HLH activators such as E47. Furthermore, HES-1 also inhibits the functions of MyoD and MASH1 and effectively diminishes the myogenic conversion of C3H10T1/2 cells induced by MyoD. These results suggest that HES-1 may play an important role in mammalian development by negatively acting on the two different sequences while HES-3 acts as a repressor in a specific type of neurons.}, author = {Sasai, Yoshiki and Kageyama, Ryoichiro and Tagawa, Yoshiaki and Shigemoto, Ryuichi and Nakanishi, Shigetada}, issn = {0890-9369}, journal = {Genes and Development}, number = {12 B}, pages = {2620 -- 2634}, publisher = {Cold Spring Harbor Laboratory Press}, title = {{Two mammalian helix-loop-helix factors structurally related to Drosophila hairy and Enhancer of split}}, doi = {10.1101/gad.6.12b.2620}, volume = {6}, year = {1992}, } @article{2714, author = {Erdös, László}, issn = {0001-5954}, journal = {Acta Mathematica Hungarica}, number = {1-2}, pages = {11 -- 24}, publisher = {Springer}, title = {{On some problems of P. Turán concerning power sums of complex numbers}}, doi = {10.1007/BF00052086}, volume = {59}, year = {1992}, } @article{2722, abstract = {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).}, author = {Erdös, László and Tuyen, Dao}, issn = {0010-3616}, journal = {Communications in Mathematical Physics}, number = {3}, pages = {451 -- 466}, publisher = {Springer}, title = {{Central limit theorems for the one-dimensional Rayleigh gas with semipermeable barriers}}, doi = {10.1007/BF02099260}, volume = {143}, year = {1992}, }