@article{4014, abstract = {A new paradigm for designing smooth surfaces is described. A finite set of points with weights specifies a closed surface in space referred to as skin. It consists of one or more components, each tangent continuous and free of self-intersections and intersections with other components. The skin varies continuously with the weights and locations of the points, and the variation includes the possibility of a topology change facilitated by the violation of tangent continuity at a single point in space and time. Applications of the skin to molecular modeling and to geometric deformation are discussed.}, author = {Edelsbrunner, Herbert}, issn = {0179-5376}, journal = {Discrete & Computational Geometry}, number = {1}, pages = {87 -- 115}, publisher = {Springer}, title = {{Deformable smooth surface design}}, doi = {10.1007/PL00009412}, volume = {21}, year = {1999}, } @article{4204, abstract = {During the development of the zebrafish nervous system both noi, a zebrafish pax2 homolog, and ace, a zebrafish fgf8 homolog, are required for development of the midbrain and cerebellum. Here we describe a dominant mutation, aussicht (aus), in which the expression of noi and ace is upregulated, In aus mutant embryos, ace is upregulated at many sites in the embryo, while Itoi expression is only upregulated in regions of the forebrain and midbrain which also express ace. Subsequent to the alterations in noi and ace expression, aus mutants exhibit defects in the differentiation of the forebrain, midbrain and eyes. Within the forebrain, the formation of the anterior and postoptic commissures is delayed and the expression of markers within the pretectal area is reduced. Within the midbrain, En and wnt1 expression is expanded. In heterozygous aus embryos, there is ectopic outgrowth of neural retina in the temporal half of the eyes, whereas in putative homozygous aus embryos, the ventral retina is reduced and the pigmented retinal epithelium is expanded towards the midline, The observation that ans mutant embryos exhibit widespread upregulation of ace raised the possibility that aus might represent an allele of the ace gene itself. However, by crossing carriers for both aus and ace, we were able to generate homozygous ace mutant embryos that also exhibited the aus phenotype, This indicated that aus is not tightly linked to ace and is unlikely to be a mutation directly affecting the ace locus. However, increased Ace activity may underly many aspects of the aus phenotype and we show that the upregulation of noi in the forebrain of aus mutants is partially dependent upon functional Ace activity. Conversely, increased ace expression in the forebrain of arcs mutants is not dependent upon functional Noi activity. We conclude that aus represents a mutation involving a locus normally required for the regulation of ace expression during embryogenesis.}, author = {Heisenberg, Carl-Philipp J and Brennan, Caroline and Wilson, Stephen}, issn = {0950-1991}, journal = {Development}, number = {10}, pages = {2129 -- 2140}, publisher = {Company of Biologists}, title = {{Zebrafish aussicht mutant embryos exhibit widespread overexpression of ace (fgf8) and coincident defects in CNS development}}, doi = {10.1242/dev.126.10.2129}, volume = {126}, year = {1999}, } @article{4277, abstract = {Reproductive isolation between two taxa may be due to endogenous selection, which is generated by incompatibilities between the respective genomes, to exogenous selection, which is generated by differential adaptations to alternative environments, or to both. The continuing debate over the relative importance of either mode of selection has highlighted the need for unambiguous data on the fitness of hybrid genotypes. The hybrid zone between the fire-bellied toad (Bombina bombina) and the yellow-bellied toad (B. variegata) in central Europe involves adaptation to different environments, but evidence of hybrid dysfunction is equivocal. In this study, we followed the development under laboratory conditions of naturally laid eggs collected from a transect across the Bombina hybrid zone in Croatia. Fitness was significantly reduced in hybrid populations: Egg batches from the center of the hybrid zone showed significantly higher embryonic and larval mortality and higher frequencies of morphological abnormalities relative to either parental type. Overall mortality from day of egg collection to three weeks after hatching reached 20% in central hybrid populations, compared to 2% in pure populations. There was no significant difference in fitness between two parental types. Within hybrid populations, there was considerable variation in fitness, with some genotypes showing no evidence of reduced viability. We discuss the implications of these findings for our understanding of barriers to gene flow between species.}, author = {Kruuk, Loeske and Gilchrist, Jason and Barton, Nicholas H}, issn = {0014-3820}, journal = {Evolution; International Journal of Organic Evolution}, number = {5}, pages = {1611 -- 1616}, publisher = {Wiley-Blackwell}, title = {{Hybrid dysfunction in fire-bellied toads (Bombina)}}, doi = {10.2307/2640907}, volume = {53}, year = {1999}, } @article{4279, abstract = {In this article we describe the structure of a hybrid zone in Argyll, Scotland, between native red deer (Cervus elaphus) and introduced Japanese sika deer (Cervus nippon), on the basis of a genetic analysis using 11 microsatellite markers and mitochondrial DNA. In contrast to the findings of a previous study of the same population, we conclude that the deer fall into two distinct genetic classes, corresponding to either a sika-like or red- like phenotype. Introgression is rare at any one locus, but where the taxa overlap up to 40% of deer carry apparently introgressed alleles. While most putative hybrids are heterozygous at only one locus, there are rare multiple heterozygotes, reflecting significant linkage disequilibrium within both sika- and red-like populations. The rate of backcrossing into the sika population is estimated as H = 0.002 per generation and into red, H = 0.001 per generation. On the basis of historical evidence that red deer entered Kintyre only recently, a diffusion model evaluated by maximum likelihood shows that sika have increased at ~9.2% yr-1 from low frequency and disperse at a rate of ~3.7 km yr-1. Introgression into the red-like population is greater in the south, while introgression into sika varies little along the transect. For both sika- and red-like populations, the degree of introgression is 30-40% of that predicted from the rates of current hybridization inferred from linkage disequilibria; however, in neither case is this statistically significant evidence for selection against introgression.}, author = {Goodman, Simon and Barton, Nicholas H and Swanson, Graeme and Abernethy, Kate and Pemberton, Josephine}, issn = {0016-6731}, journal = {Genetics}, number = {1}, pages = {355 -- 371}, publisher = {Genetics Society of America}, title = {{Introgression through rare hybridisation: A genetic study of a hybrid zone between red and sika deer (genus Cervus), in Argyll, Scotland}}, doi = {10.1093/genetics/152.1.355}, volume = {152}, year = {1999}, } @phdthesis{4411, abstract = {Model checking algorithms for the verification of reactive systems proceed by a systematic and exhaustive exploration of the system state space. They do not scale to large designs because of the state explosion problem --the number of states grows exponentially with the number of components in the design. Consequently, the model checking problem is PSPACE-hard in the size of the design description. This dissertation proposes three novel techniques to combat the state explosion problem. One of the most important advances in model checking in recent years has been the discovery of symbolic methods, which use a calculus of expressions, such as binary decision diagrams, to represent the state sets encountered during state space exploration. Symbolic model checking has proved to be effective for verifying hardware designs. Traditionally, symbolic checking of temporal logic specifications is performed by backward fixpoint reasoning with the operator Pre. Backward reasoning can be wasteful since unreachable states are explored. We suggest the use of forward fixpoint reasoning based on the operator Post. We show how all linear temporal logic specifications can be model checked symbolically by forward reasoning. In contrast to backward reasoning, forward reasoning performs computations only on the reachable states. Heuristics that improve algorithms for application domains, such as symbolic methods for hardware designs, are useful but not enough to make model checking feasible on industrial designs. Currently, exhaustive state exploration is possible only on designs with about 50-100 boolean state variables. Assume-guarantee verification attempts to combat the state explosion problem by using the principle of "divide and conquer," where the components of the implementation are analyzed one at a time. Typically, an implementation component refines its specification only when its inputs are suitably constrained by other components in the implementation. The assume-guarantee principle states that instead of constraining the inputs by implementation components, it is sound to constrain them by the corresponding specification components, which can be significantly smaller. We extend the assume-guarantee proof rule to deal with the case where the specification operates at a coarser time scale than the implementation. Using our model checker Mocha, which implements this methodology, we verify VGI, a parallel DSP processor chip with 64 compute processors each containing approximately 800 state variables and 30K gates. Our third contribution is a systematic model checking methodology for verifying the abstract shared-memory interface of sequential consistency on multiprocessor systems with three parameters --number of processors, number of memory locations, and number of data values. Sequential consistency requires that some interleaving of the local temporal orders of read/write events at different processors be a trace of serial memory. Therefore, it suffices to construct a non-interfering serializer that watches and reorders read/write events so that a trace of serial memory is obtained. While in general such a serializer must be unbounded even for fixed values of the parameters --checking sequential consistency is undecidable!-- we show that the paradigmatic class of snoopy cache coherence protocols has finite-state serializers. In order to reduce the arbitrary-parameter problem to the fixed-parameter problem, we develop a novel framework for induction over the number of processors and use the notion of a serializer to reduce the problem of verifying sequential consistency to that of checking language inclusion between finite state machines.}, author = {Qadeer, Shaz}, pages = {1 -- 150}, publisher = {University of California, Berkeley}, title = {{Algorithms and Methodology for Scalable Model Checking}}, year = {1999}, } @article{4442, abstract = {Rectangular hybrid automata model digital control programs of analog plant environments. We study rectangular hybrid automata where the plant state evolves continuously in real-numbered time, and the controller samples the plant state and changes the control state discretely, only at the integer points in time. We prove that rectangular hybrid automata have finite bisimilarity quotients when all control transitions happen at integer times, even if the constraints on the derivatives of the variables vary between control states. This is in contrast with the conventional model where control transitions may happen at any real time, and already the reachability problem is undecidable. Based on the finite bisimilarity quotients, we give an exponential algorithm for the symbolic sampling-controller synthesis of rectangular automata. We show our algorithm to be optimal by proving the problem to be EXPTIME-hard. We also show that rectangular automata form a maximal class of systems for which the sampling-controller synthesis problem can be solved algorithmically.}, author = {Henzinger, Thomas A and Kopke, Peter}, issn = {0304-3975}, journal = {Theoretical Computer Science}, number = {1-2}, pages = {369 -- 392}, publisher = {Elsevier}, title = {{Discrete-time control for rectangular hybrid automata}}, doi = {10.1016/S0304-3975(99)00038-9}, volume = {221}, year = {1999}, } @inproceedings{4480, abstract = {We describe the formal specification and verification of the VGI parallel DSP chip [1], which contains 64 compute processors with ~30K gates in each processor. Our effort coincided in time with the “informal” verification stage of the chip. By interacting with the designers, we produced an abstract but executable specification of the design which embodies the programmer's view of the system. Given the size of the design, an automatic check that even one of the 64 processors satisfies its specification is well beyond the scope of current verification tools. However, the check can be decomposed using assume-guarantee reasoning. For VGI, the implementation and specification operate at different time scales: several steps of the implementation correspond to a single step in the specification. We generalized both the assume-guarantee method and our model checker MOCHA to allow compositional verification for such applications. We used our proof rule to decompose the verification problem of the VGI chip into smaller proof obligations that were discharged automatically by MOCHA. Using our formal approach, we uncovered and fixed subtle bugs that were unknown to the designers.}, author = {Henzinger, Thomas A and Liu, Xiaojun and Qadeer, Shaz and Rajamani, Sriram}, issn = {1092-3152}, location = {San Jose, CA, United States of America}, pages = {494 -- 499}, publisher = {IEEE}, title = {{Formal specification and verification of a dataflow processor array}}, doi = {10.1109/ICCAD.1999.810700}, year = {1999}, } @inproceedings{4484, abstract = {In shared-memory multiprocessors sequential consistency offers a natural tradeoff between the flexibility afforded to the implementor and the complexity of the programmer’s view of the memory. Sequential consistency requires that some interleaving of the local temporal orders of read/write events at different processors be a trace of serial memory. We develop a systematic methodology for proving sequential consistency for memory systems with three parameters —number of processors, number of memory locations, and number of data values. From the definition of sequential consistency it suffices to construct a non-interfering observer that watches and reorders read/write events so that a trace of serial memory is obtained. While in general such an observer must be unbounded even for fixed values of the parameters —checking sequential consistency is undecidable!— we show that for two paradigmatic protocol classes—lazy caching and snoopy cache coherence—there exist finite-state observers. In these cases, sequential consistency for fixed parameter values can thus be checked by language inclusion between finite automata. In order to reduce the arbitrary-parameter problem to the fixed-parameter problem, we develop a novel framework for induction over the number of processors. Classical induction schemas, which are based on process invariants that are inductive with respect to an implementation preorder that preserves the temporal sequence of events, are inadequate for our purposes, because proving sequential consistency requires the reordering of events. Hence we introduce merge invariants, which permit certain reorderings of read/write events. We show that under certain reasonable assumptions about the memory system, it is possible to conclude sequential consistency for any number of processors, memory locations, and data values by model checking two finite-state lemmas about process and merge invariants: they involve two processors each accessing a maximum of three locations, where each location stores at most two data values. For both lazy caching and snoopy cache coherence we are able to discharge the two lemmas using the model checker MOCHA.}, author = {Henzinger, Thomas A and Qadeer, Shaz and Rajamani, Sriram}, booktitle = {Proceedings of the 11th International Conference on Computer Aided Verification}, isbn = {9783540662020}, location = {Trento, Italy}, pages = {301 -- 315}, publisher = {Springer}, title = {{Verifying sequential consistency on shared-memory multiprocessor systems}}, doi = {10.1007/3-540-48683-6_27}, volume = {1633}, year = {1999}, } @inproceedings{4485, abstract = {In order to study control problems for hybrid systems, we generalize hybrid automata to hybrid games —say, controller vs. plant. If we specify the continuous dynamics by constant lower and upper bounds, we obtain rectangular games. We show that for rectangular games with objectives expressed in Ltl (linear temporal logic), the winning states for each player can be computed, and winning strategies can be synthesized. Our result is sharp, as already reachability is undecidable for generalizations of rectangular systems, and optimal —singly exponential in the size of the game structure and doubly exponential in the size of the Ltl objective. Our proof systematically generalizes the theory of hybrid systems from automata (single-player structures) [9] to games (multi-player structures): we show that the successively more general infinite-state classes of timed, 2D rectangular, and rectangular games induce successively weaker, but still finite, quotient structures called game bisimilarity, game similarity, and game trace equivalence. These quotients can be used, in particular, to solve the Ltl control problem.}, author = {Henzinger, Thomas A and Horowitz, Benjamin and Majumdar, Ritankar}, booktitle = {Proceedings of the 10th International Conference on Concurrency Theory}, isbn = {9783540664253}, location = {Eindhoven, The Netherlands}, pages = {320 -- 335}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik}, title = {{Rectangular hybrid games}}, doi = {10.1007/3-540-48320-9_23}, volume = {1664}, year = {1999}, } @inproceedings{4487, abstract = {Refinement checking is used to verify implementations against more abstract specifications. Assume-guarantee reasoning is used to decompose refinement proofs in order to avoid state-space explosion. In previous approaches, specifications are forced to operate on the same time scale as the implementation. This may lead to unnatural specifications and inefficiencies in verification. We introduce a novel methodology for decomposing refinement proofs of temporally abstract specifications, which specify implementation requirements only at certain sampling instances in time. Our new assume-guarantee rule allows separate refinement maps for specifying functionality and timing.We present the theory for the correctness of our methodology, and illustrate it using a simple example. Support for sampling and the generalized assume-guarantee rule have been implemented in the model checker Mocha and successfully applied to verify the VGI multiprocessor dataflow chip with 6 million transistors.}, author = {Henzinger, Thomas A and Qadeer, Shaz and Rajamani, Sriram}, booktitle = {Proceedings of the 11th International Conference on Computer Aided Verification}, isbn = {9783540662020}, location = {Trento, Italy}, pages = {208 -- 221}, publisher = {Springer}, title = {{Assume-guarantee refinement between different time scales}}, doi = {10.1007/3-540-48683-6_20}, volume = {1633}, year = {1999}, } @article{2583, abstract = {Substance P receptor (SPR)-immunoreactive neurons projecting to the periaqueductal gray (PAG) were examined in the rat spinal trigeminal nucleus and spinal cord by a retrograde tracing method combined with immunofluorescence histochemistry. After injection of Fluoro-gold (FG) into the PAG, SPR-immunoreactive neurons labeled with FG were observed mainly in the lateral spinal nucleus and lamina I of the medullary and spinal dorsal horns and additionally in laminae V and X of the spinal cord.}, author = {Li, Jin and Ding, Yu and Xiong, Kang and Li, Ji and Shigemoto, Ryuichi and Mizuno, Noboru}, issn = {0168-0102}, journal = {Neuroscience Research}, number = {3}, pages = {219 -- 225}, publisher = {Elsevier}, title = {{Substance P receptor (NK1)-immunoreactive neurons projecting to the periaqueductal gray: Distribution in the spinal trigeminal nucleus and the spinal cord of the rat}}, doi = {10.1016/S0168-0102(97)00132-6}, volume = {30}, year = {1998}, } @article{2584, abstract = {The distributions of two alternative splicing variants of metabotropic glutamate receptor mGluR7, mGluR7a and mGluR7b, were examined immunohistochemically in the rat and mouse by using variant-specific antibodies raised against C-terminal portions of rat mGluR7a and human mGluR7b. Many regions throughout the central nervous system (CNS) showed mGluR7-like immunoreactivities (LI). The distribution patterns of mGluR7-LI in the rat were substantially the same as those in the mouse, although some species differences were observed in a few regions. Intense mGluR7a-LI was seen in the main and accessory olfactory bulbs, anterior olfactory nucleus, islands of Calleja, superficial layers of the olfactory tubercle, piriform cortex and entorhinal cortex, periamygdaloid cortex, amygdalohippocampal area, hippocampus, layer I of the neocortical regions, globus pallidus, superficial layers of the superior colliculus, locus coeruleus, and superficial layers of the medullary and spinal dorsal horns. The distribution of mGluR7b was more restricted. It was intense in the islands of Calleja, substantia innominata, hippocampus, ventral pallidum, and globus pallidus. The medial habenular nucleus also showed intense mGluR7a-LI in the rat but not in the mouse. For both mGluR7a- and mGluR7b-LI, localization in the active zones of presynaptic axon terminals was confirmed electron microscopically at synapses of both the asymmetrical and symmetrical types. It is noteworthy that mGluR7a-LI is seen preferentially in relay nuclei of the sensory pathways and that both mGluR7a- and mGluR7b-LI are observed not only in presumed glutamatergic axon terminals, but also in non-glutamatergic axon terminals including presumed inhibitory ones. Thus, mGluR7 may play roles not only as an autoreceptor in glutamatergic axon terminals, but also as a presynaptic heteroreceptor in non-glutamatergic axon terminals in various CNS regions.}, author = {Kinoshita, Ayae and Shigemoto, Ryuichi and Ohishi, Hitoshi and Van Der Putten, Herman and Mizuno, Noboru}, issn = {0021-9967}, journal = {Journal of Comparative Neurology}, number = {3}, pages = {332 -- 352}, publisher = {Wiley-Blackwell}, title = {{Immunohistochemical localization of metabotropic glutamate receptors, mGluR7a and mGluR7b, in the central nervous system of the adult rat and mouse: A light and electron microscopic study}}, doi = {10.1002/(SICI)1096-9861(19980413)393:3<332::AID-CNE6>3.0.CO;2-2}, volume = {393}, year = {1998}, } @article{2585, abstract = {Localization of metabetropic glutamate receptor subtypes, mGluR1, mGluRlu, mGluR2/3, mGluR4a, mGluR5, mGluR7a, mGluR7b, and mGluR8, was examined in some of the target areas of projection fibers from the main and accessory olfactory bulbs (MOB and AOB) by using subtype-specific antibodies. The superficial layer of the olfactory tubercle and layer Ia of the pitiform cortex, the target areas of MOB, showed marked mGluR1-, mGluR5-, mGluR7a-, and mGluR8-like immunoreactivities (-LI), and rather weak mGluR2/3-LI. The periamygdaloid cortical region including the target areas of both MOB and AOB showed intense mGluR2/3-LI as well as marked mGluRl-, mGluR5-, mGluR7a-, and mGluRS-LI. No significant mGluR1a-, mGluR4a-, or mGluR7b-LI was seen in these regions. After transection of the lateral olfactory tract, mGluR2/3-, mGluR7a-, and mGluR8-LI were reduced markedly in the target regions on the side ipsilateral to the transection; no significant changes were detected in mGluR1- or mGIuR5-LI. Double labeling experiments indicated light and electron microscopically colocalization of mGluR7a- and mGluRS-LI in axon terminals on dendritic shafts of presumed interneurons in the superficial layer of the olfactory tubercle and layer Ia of the piriform cortex. Electron microscopically mGluR2/3-LI was seen in preterminal and terminal portions of axons, whereas mGluR7a- and mGluRS-LI were associated with presynaptic membrane specialization. Immunolabeled axon terminals were filled with round synaptic vesicles and constituted asymmetric synapses with dendritic profiles. The results suggest that glutamate release from axon terminals of projection fibers from MOB and AOB is regulated presynaptically and differentially through mGluR2/3, mGluR7a, and/or mGluRS.}, author = {Wada, Eiki and Shigemoto, Ryuichi and Kinoshita, Ayae and Ohishi, Hitoshi and Mizuno, Noboru}, issn = {0021-9967}, journal = {Journal of Comparative Neurology}, number = {4}, pages = {493 -- 504}, publisher = {Wiley-Blackwell}, title = {{Metabotropic glutamate receptor subtypes in axon terminals of projection fibers from the main and accessory olfactory bulbs: A light and electron microscopic immunohistochemical study in the rat}}, doi = {10.1002/(SICI)1096-9861(19980420)393:4<493::AID-CNE8>3.0.CO;2-W}, volume = {393}, year = {1998}, } @article{2586, abstract = {The role of inhibitory Golgi cells in cerebellar function was investigated by selectively ablating Golgi cells expressing human interleukin-2 receptor α subunit in transgenic mice, using the immunotoxin- mediated cell targeting technique. Golgi cell disruption caused severe acute motor disorders. These mice showed gradual recovery but retained a continuing inability to perform compound movements. Optical and electrical recordings combined with immunocytological analysis indicated that elimination of Golgi cells not only reduces GABA-mediated inhibition but also attenuates functional NMDA receptors in granule cells. These results demonstrate that synaptic integration involving both GABA inhibition and NMDA receptor activation is essential for compound motor coordination. Furthermore, this integration can adapt after Golgi cell elimination so as not to evoke overexcitation by the reduction of NMDA receptors.}, author = {Watanabe, Dai and Inokawa, Hitoshi and Hashimoto, Kouichi and Suzuki, Noboru and Kano, Masanobu and Shigemoto, Ryuichi and Hirano, Tomoo and Toyama, Keisuke and Kaneko, Satoshi and Yokoi, Mineto and Moriyoshi, Koki and Suzuki, Misao and Kobayashi, Kazuto and Nagatsu, Toshiharu and Kreitman, Robert and Pastan, Ira and Nakanishi, Shigetada}, issn = {0092-8674}, journal = {Cell}, number = {1}, pages = {17 -- 27}, publisher = {Cell Press}, title = {{Ablation of cerebellar Golgi cells disrupts synaptic integration involving GABA inhibition and NMDA receptor activation in motor coordination}}, doi = {10.1016/S0092-8674(00)81779-1}, volume = {95}, year = {1998}, } @article{2588, abstract = {B-type receptors for the neurotransmitter GABA (γ-aminobutyric acid) inhibit neuronal activity through G-protein-coupled second-messenger systems, which regulate the release of neurotransmitters and the activity of ion channels and adenylyl cyclase. Physiological and biochemical studies show that there are differences in drug efficiencies at different GABA(B) receptors, so it is expected that GABA(B)-receptor (GABA(B)R) subtypes exist. Two GABA(B)-receptor splice variants have been cloned (GABA(B)R1a and GABA(B)R1b), but native GABA(B) receptors and recombinant receptors showed unexplained differences in agonist-binding potencies. Moreover, the activation of presumed effector ion channels in heterologous cells expressing the recombinant receptors proved difficult. Here we describe a new GABA(B) receptor subtype, GABA(B)R2, which does not bind available GABA(B) antagonists with measurable potency. GABA(B)R1a, GABA(B)R1b and GABA(B)R2 alone do not activate Kir3-type potassium channels efficiently, but co- expression of these receptors yields a robust coupling to activation of Kir3 channels. We provide evidence for the assembly of heteromeric GABA(B) receptors in vivo and show that GABA(B)R2 and GABA(B)R1a/b proteins immunoprecipitate and localize together at dendritic spines. The heteromeric receptor complexes exhibit a significant increase in agonist- and partial- agonist-binding potencies as compared with individual receptors and probably represent the predominant native GABA(B) receptor. Heteromeric assembly among G-protein-coupled receptors has not, to our knowledge, been described before. }, author = {Kaupmann, Klemens and Malitschek, Barbara and Schuler, Valérie and Heid, Jacob and Froestl, Wolfgang and Beck, Pascal and Mosbacher, Johannes and Bischoff, Serge and Kulik, Ákos and Shigemoto, Ryuichi and Karschin, Andreas and Bettler, Bernhard}, issn = {0028-0836}, journal = {Nature}, number = {6712}, pages = {683 -- 687}, publisher = {Nature Publishing Group}, title = {{ GABA(B)-receptor subtypes assemble into functional heteromeric complexes}}, doi = {10.1038/25360}, volume = {396}, year = {1998}, } @article{2589, abstract = {Immunoreactivity for the substance P receptor (NK1 receptor) has been investigated by light and electron microscopy in the dorsal vagal complexes of adult rats and cats. The general pattern of NK1 immunoreactivity was similar for both rat and cat. Numerous NK1-immunoreactive neurons were present in the area postrema, the nucleus of the solitary tract, and the dorsal motor nucleus of the vagus nerve. The density of labelled neurons differed between the subnuclei of the nucleus of the solitary tract. Overall, the efferent neurons of the dorsal motor nucleus of the vagus nerve highly expressed NK1 when compared to neurons in the nucleus of the solitary tract. The results are discussed with reference to the viscerotopic organisation of the dorsal vagal complex. Ultrastructural analysis demonstrated that NK1 immunoreactivity was present only at the membrane surface of somatic and dendritic profiles of neurons. No labelling was found in axon terminals, axons, or glial processes. NK1 immunoreactivity, as revealed by a preembedding immunogold technique in serial ultrathin sections; was preferentially located at nonsynaptic sites. A semiquantitative study suggested that the density of NK1 receptors is statistically higher at membrane sites free of any contact (synaptic or not) with axon terminals. The subcellular localisation of NK1 immunoreactivity was similar for neurons of both rat and cat. These results suggest that in the dorsal vagal complex, substance P might act on NK1 receptors through a process of volume transmission.}, author = {Baude, Agnès and Shigemoto, Ryuichi}, issn = {0021-9967}, journal = {Journal of Comparative Neurology}, number = {2}, pages = {181 -- 196}, publisher = {Wiley-Blackwell}, title = {{Cellular and subcellular distribution of substance P receptor immunoreactivity in the dorsal vagal complex of the rat and cat: A light and electron microscope study}}, doi = {10.1002/(SICI)1096-9861(19981214)402:2<181::AID-CNE4>3.0.CO;2-B}, volume = {402}, year = {1998}, } @article{2590, abstract = {Unipolar brush cells (UBCs) are a class of small neurons that are densely concentrated in the granular layers of the vestibulocerebellar cortex and dorsal cochlear nucleus. The UBCs form giant synapses with individual mossy fibre rosettes on the dendrioles which make up their brush formations and are provided with numerous, unusual non-synaptic appendages. In accord with the glutamatergic nature of mossy fibres, our previous post-embedding immunocytochemical studies indicated that various ionotropic glutamate receptor subunits are localized at the post-synaptic densities of the giant synapses, whereas the non-synaptic appendages are immunonegative. On the contrary, the metabotropic glutamate receptors mGluR1α and mGluR2/3 are situated at the non-synaptic appendages and are lacking at the post-synaptic densities. Other authors, however, have shown that antibodies to these metabotropic receptors stain both appendages and post-synaptic densities. In the present study, we have re-evaluated the distribution of metabotropic glutamate receptors in the UBCs of the cerebellum and the cochlear nuclear complex by light and electron microscopic pre-embedding immunocytochemistry with subtype-specific antibodies. We confirm that UBCs dendritic brushes are densely immunostained by antibody to mGluR1α particularly in the cerebellum and that antibody to mGluR2/3 labels at least a percentage of the UBC brushes in both the cerebellum and cochlear nuclei. At the ultrastructural level, it appears that mGluR1α and mGluR2/3 immunoreactivities are not associated with the post-synaptic densities of the giant mossy fibre-UBC synapses, but instead are concentrated on the non-synaptic appendages of the cerebellar UBCs. The non-synaptic appendages, therefore, may be an important avenue for regulating the excitability of UBCs and mediating glutamate effects on their still unknown intracellular signal transduction cascades. We also show that the pre-synaptic densities of UBC dendrodendritic junctions are mGluR2/3 positive. As previously demonstrated, antibodies to mGluR1α and mGluR2/3 label subsets of Golgi cells. Antibody to mGluR5 does not stain UBCs in the cerebellum and cochlear nucleus and reveals the somatodendritic compartment of Golgi cells situated in the core of the cerebellar granular layer, whilst cochlear nucleus Golgi cells are mGluR5 negative.}, author = {Jaarsma, Dick and Diño, Maria and Ohishi, Hitoshi and Shigemoto, Ryuichi and Mugnaini, Enrico}, issn = {0300-4864}, journal = {Journal of Neurocytology}, number = {5}, pages = {303 -- 327}, publisher = {Kluwer}, title = {{ Metabotropic glutamate receptors are associated with non-synaptic appendages of unipolar brush cells in rat cerebellar cortex and cochlear nuclear complex}}, doi = {10.1023/A:1006982023657}, volume = {27}, year = {1998}, } @inbook{2695, abstract = {We study a quantum particle in a random potential in two scaling limits: the low density limit (or Boltzman-Grad) and the weak coupling limit. The low density limit is the quantum analogue of the Lorentz gas. In both cases, the phase space density of the quantum evolution defined through the Wigner transform or the Husimi function converges weakly to a linear Boltz-mann equation with collision kernel given by the quantum scattering cross section. }, author = {Erdös, László and Yau, Horng}, booktitle = {Advances in Differential Equations and Mathematical Physics}, issn = {0271-4132}, pages = {137 -- 155}, publisher = {American Mathematical Society}, title = {{Linear Boltzmann equation as scaling limit of quantum Lorentz gas}}, doi = {10.1090/conm/217}, volume = {217}, year = {1998}, } @article{2728, abstract = {We obtain the Lifschitz tail, i.e. the exact low energy asymptotics of the integrated density of states (IDS) of the two-dimensional magnetic Schrödinger operator with a uniform magnetic field and random Poissonian impurities. The single site potential is repulsive and it has a finite but nonzero range. We show that the IDS is a continuous function of the energy at the bottom of the spectrum. This result complements the earlier (nonrigorous) calculations by Brézin, Gross and Itzykson which predict that the IDS is discontinuous at the bottom of the spectrum for zero range (Dirac delta) impurities at low density. We also elucidate the reason behind this apparent controversy. Our methods involve magnetic localization techniques (both in space and energy) in addition to a modified version of the "enlargement of obstacles" method developed by A.-S. Sznitman.}, author = {Erdös, László}, issn = {0044-3719}, journal = {Probability Theory and Related Fields}, number = {3}, pages = {321 -- 371}, publisher = {Springer}, title = {{Lifschitz tail in a magnetic field: The nonclassical regime}}, doi = {10.1007/s004400050193}, volume = {112}, year = {1998}, } @article{11680, abstract = {We present a model for edge updates with restricted randomness in dynamic graph algorithms and a general technique for analyzing the expected running time of an update operation. This model is able to capture the average case in many applications, since (1) it allows restrictions on the set of edges which can be used for insertions and (2) the type (insertion or deletion) of each update operation is arbitrary, i.e., not random. We use our technique to analyze existing and new dynamic algorithms for the following problems: maximum cardinality matching, minimum spanning forest, connectivity, 2-edge connectivity, k -edge connectivity, k -vertex connectivity, and bipartiteness. Given a random graph G with m 0 edges and n vertices and a sequence of l update operations such that the graph contains m i edges after operation i , the expected time for performing the updates for any l is O(llogn+∑li=1n/m−−√i) in the case of minimum spanning forests, connectivity, 2-edge connectivity, and bipartiteness. The expected time per update operation is O(n) in the case of maximum matching. We also give improved bounds for k -edge and k -vertex connectivity. Additionally we give an insertions-only algorithm for maximum cardinality matching with worst-case O(n) amortized time per insertion.}, author = {Alberts, D. and Henzinger, Monika H}, issn = {1432-0541}, journal = {Algorithmica}, keywords = {Dynamic graph algorithm, Average-case analysis, Minimum spanning forest, Connectivity, Bipartiteness, Maximum matching.}, pages = {31--60}, publisher = {Springer Nature}, title = {{Average-case analysis of dynamic graph algorithms}}, doi = {10.1007/pl00009186}, volume = {20}, year = {1998}, }