TY - JOUR AB - We show that the number of nontrivial rational points of height at most B, which lie on the cubic surface x1 x2 x3 = x4 (x1 + x2 + x3)2, has order of magnitude B (log B)6. This agrees with Manin's conjecture. AU - Timothy Browning ID - 217 IS - 2 JF - Journal of Number Theory TI - The density of rational points on a certain singular cubic surface VL - 119 ER - TY - JOUR AB - The human norepinephrine (NE) transporter (hNET) attenuates neuronal signaling by rapid NE clearance from the synaptic cleft, and NET is a target for cocaine and amphetamines as well as therapeutics for depression, obsessive-compulsive disorder, and post-traumatic stress disorder. In spite of its central importance in the nervous system, little is known about how NET substrates, such as NE, 1-methyl-4-tetrahydropyridinium (MPP+), or amphetamine, interact with NET at the molecular level. Nor do we understand the mechanisms behind the transport rate. Previously we introduced a fluorescent substrate similar to MPP+, which allowed separate and simultaneous binding and transport measurement (Schwartz, J. W., Blakely, R. D., and DeFelice, L. J. (2003) J. Biol. Chem. 278, 9768-9777). Here we use this substrate, 4-(4-(dimethylamino)styrl)-N-methyl-pyridinium (ASP+), in combination with green fluorescent protein-tagged hNETs to measure substrate-transporter stoichiometry and substrate binding kinetics. Calibrated confocal microscopy and fluorescence correlation spectroscopy reveal that hNETs, which are homo-multimers, bind one substrate molecule per transporter subunit. Substrate residence at the transporter, obtained from rapid on-off kinetics revealed in fluorescence correlation spectroscopy, is 526 μs. Substrate residence obtained by infinite dilution is 1000 times slower. This novel examination of substrate-transporter kinetics indicates that a single ASP + molecule binds and unbinds thousands of times before being transported or ultimately dissociated from hNET. Calibrated fluorescent images combined with mass spectroscopy give a transport rate of 0.06 ASP +/hNET-protein/s, thus 36,000 on-off binding events (and 36 actual departures) occur for one transport event. Therefore binding has a low probability of resulting in transport. We interpret these data to mean that inefficient binding could contribute to slow transport rates. AU - Schwartz, Joel W AU - Gaia Novarino AU - Piston, David W AU - DeFelice, Louis J ID - 2307 IS - 19 JF - Journal of Biological Chemistry TI - Substrate binding stoichiometry and kinetics of the norepinephrine transporter VL - 280 ER - TY - BOOK AB - This book contains a unique survey of the mathematically rigorous results about the quantum-mechanical many-body problem that have been obtained by the authors in the past seven years. It addresses a topic that is not only rich mathematically, using a large variety of techniques in mathematical analysis, but is also one with strong ties to current experiments on ultra-cold Bose gases and Bose-Einstein condensation. The book provides a pedagogical entry into an active area of ongoing research for both graduate students and researchers. It is an outgrowth of a course given by the authors for graduate students and post-doctoral researchers at the Oberwolfach Research Institute in 2004. The book also provides a coherent summary of the field and a reference for mathematicians and physicists active in research on quantum mechanics. AU - Lieb, Élliott AU - Seiringer, Robert AU - Solovej, Jan AU - Yngvason, Jakob ID - 2335 SN - 978-3-7643-7336-8 TI - The Mathematics of the Bose gas and its Condensation VL - 34 ER - TY - CHAP AB - Now that the low temperature properties of quantum-mechanical many-body systems (bosons) at low density, ρ, can be examined experimentally it is appropriate to revisit some of the formulas deduced by many authors 4–5 decades ago, and to explore new regimes not treated before. For systems with repulsive (i.e. positive) interaction potentials the experimental low temperature state and the ground state are effectively synonymous — and this fact is used in all modeling. In such cases, the leading term in the energy/particle is 2πħ2 aρ/m where a is the scattering length of the two-body potential. Owing to the delicate and peculiar nature of bosonic correlations (such as the strange N 7/5 law for charged bosons), four decades of research failed to establish this plausible formula rigorously. The only previous lower bound for the energy was found by Dyson in 1957, but it was 14 times too small. The correct asymptotic formula has been obtained by us and this work will be presented. The reason behind the mathematical difficulties will be emphasized. A different formula, postulated as late as 1971 by Schick, holds in two dimensions and this, too, will be shown to be correct. With the aid of the methodology developed to prove the lower bound for the homogeneous gas, several other problems have been successfully addressed. One is the proof by us that the Gross-Pitaevskii equation correctly describes the ground state in the ‘traps’ actually used in the experiments. For this system it is also possible to prove complete Bose condensation and superfluidity as we have shown. On the frontier of experimental developments is the possibility that a dilute gas in an elongated trap will behave like a one-dimensional system; we have proved this mathematically. Another topic is a proof that Foldy’s 1961 theory of a high density Bose gas of charged particles correctly describes its ground state energy; using this we can also prove the N 7/5 formula for the ground state energy of the two-component charged Bose gas proposed by Dyson in 1967. All of this is quite recent work and it is hoped that the mathematical methodology might be useful, ultimately, to solve more complex problems connected with these interesting systems. AU - Lieb, Élliott H AU - Robert Seiringer AU - Solovej, Jan P AU - Yngvason, Jakob ED - Benedicks, Michael ED - Jones, Peter W ED - Smirnov, Stanislav ED - Winckler, Björn ID - 2336 T2 - Perspectives in Analysis TI - The quantum-mechanical many-body problem: The Bose gas VL - 27 ER - TY - JOUR AB - The validity of substituting a c-number z for the k = 0 mode operator a0 is established rigorously in full generality, thereby verifying one aspect of Bogoliubov's 1947 theory. This substitution not only yields the correct value of thermodynamic quantities such as the pressure or ground state energy, but also the value of |z|2 that maximizes the partition function equals the true amount of condensation in the presence of a gauge-symmetry-breaking term. This point had previously been elusive. AU - Lieb, Élliott H AU - Robert Seiringer AU - Yngvason, Jakob ID - 2359 IS - 8 JF - Physical Review Letters TI - Justification of c-number substitutions in bosonic hamiltonians VL - 94 ER - TY - JOUR AB - Recent developments in the physics of low-density trapped gases make it worthwhile to verify old, well-known results that, while plausible, were based on perturbation theory and assumptions about pseudopotentials. We use and extend recently developed techniques to give a rigorous derivation of the asymptotic formula for the ground-state energy of a dilute gas of N fermions interacting with a short-range, positive potential of scattering length a. For spin-12 fermions, this is E∼E0+(22m)2πNa, where E0 is the energy of the noninteracting system and is the density. A similar formula holds in two dimensions (2D), with a replaced by ln(a2). Obviously this 2D energy is not the expectation value of a density-independent pseudopotential. AU - Lieb, Élliott H AU - Robert Seiringer AU - Solovej, Jan P ID - 2362 IS - 5 JF - Physical Review A - Atomic, Molecular, and Optical Physics TI - Ground state energy of the low density Fermi gas VL - 71 ER - TY - JOUR AB - The strong subadditivity of entropy plays a key role in several areas of physics and mathematics. It states that the entropy S[±]=- Tr(ϱlnϱ) of a density matrix ϱ123 on the product of three Hilbert spaces satisfies S[ϱ123]- S[ϱ12]≤S[ϱ23]-S[ϱ2]. We strengthen this to S[ϱ123]-S[ϱ12] ≤αnα(S[ϱ23α]-S[ϱ2α]), where the nα are weights and the ϱ23α are partitions of ϱ23. Correspondingly, there is a strengthening of the theorem that the map A|Trexp[L+lnA] is concave. As applications we prove some monotonicity and convexity properties of the Wehrl coherent state entropy and entropy inequalities for quantum gases. AU - Lieb, Élliott H AU - Robert Seiringer ID - 2361 IS - 6 JF - Physical Review A - Atomic, Molecular, and Optical Physics TI - Stronger subadditivity of entropy VL - 71 ER - TY - CONF AB - We consider an online version of the conflict-free coloring of a set of points on the line, where each newly inserted point must be assigned a color upon insertion, and at all times the coloring has to be conflict-free, in the sense that in every interval I there is a color that appears exactly once in I. We present several deterministic and randomized algorithms for achieving this goal, and analyze their performance, that is, the maximum number of colors that they need to use, as a function of the number n of inserted points. We first show that a natural and simple (deterministic) approach may perform rather poorly, requiring Ω(√n) colors in the worst case. We then modify this approach, to obtain an efficient deterministic algorithm that uses a maximum of Θ(log 2 n) colors. Next, we present two randomized solutions. The first algorithm requires an expected number of at most O(log 2 n) colors, and produces a coloring which is valid with high probability, and the second one, which is a variant of our efficient deterministic algorithm, requires an expected number of at most O(log n log log n) colors but always produces a valid coloring. We also analyze the performance of the simplest proposed algorithm when the points are inserted in a random order, and present an incomplete analysis that indicates that, with high probability, it uses only O(log n) colors. Finally, we show that in the extension of this problem to two dimensions, where the relevant ranges are disks, n colors may be required in the worst case. The average-case behavior for disks, and cases involving other planar ranges, are still open. AU - Fiat, Amos AU - Levy, Meital B AU - Matoušek, Jiří AU - Pach, Elchanan M AU - Sharir, Micha AU - Smorodinsky, Shakhar AU - Uli Wagner AU - Welzl, Emo ID - 2428 TI - Online conflict-free coloring for intervals ER - TY - JOUR AB - Intersection graphs of disks and of line segments, respectively, have been well studied, because of both practical applications and theoretically interesting properties of these graphs. Despite partial results, the complexity status of the Clique problem for these two graph classes is still open. Here, we consider the Clique problem for intersection graphs of ellipses, which, in a sense, interpolate between disks and line segments, and show that the problem is APX-hard in that case. Moreover, this holds even if for all ellipses, the ratio of the larger over the smaller radius is some prescribed number. Furthermore, the reduction immediately carries over to intersection graphs of triangles. To our knowledge, this is the first hardness result for the Clique problem in intersection graphs of convex objects with finite description complexity. We also describe a simple approximation algorithm for the case of ellipses for which the ratio of radii is bounded. AU - Ambühl, Christoph AU - Uli Wagner ID - 2427 IS - 3 JF - Theory of Computing Systems TI - The Clique problem in intersection graphs of ellipses and triangles VL - 38 ER - TY - JOUR AB - Local accumulation of the plant growth regulator auxin mediates pattern formation in Arabidopsis roots and influences outgrowth and development of lateral root- and shoot-derived primordia. However, it has remained unclear how auxin can simultaneously regulate patterning and organ outgrowth and how its distribution is stabilized in a primordium-specif ic manner. Here we show that five PIN genes collectively control auxin distribution to regulate cell division and cell expansion in the primary root. Furthermore, the joint action of these genes has an important role in pattern formation by focusing the auxin maximum and restricting the expression domain of PLETHORA (PLT) genes, major determinants for root stem cell specification. In turn, PLT genes are required for PIN gene transcription to stabilize the auxin maximum at the distal root tip. Our data reveal an interaction network of auxin transport facilitators and root fate determinants that control patterning and growth of the root primordium. AU - Billou, Ikram AU - Xu, Jian AU - Wildwater, Marjolein AU - Willemsen, Viola AU - Paponov, Ivan A AU - Jirí Friml AU - Heldstra, Renze AU - Aida, Mitsuhiro AU - Palme, Klaus J AU - Scheres, Ben ID - 2455 IS - 7021 JF - Nature TI - The PIN auxin efflux facilitator network controls growth and patterning in Arabidopsis roots VL - 433 ER - TY - CHAP AU - Jirí Friml AU - Wiśniewska, Justyna ED - Fleming, Andrew J. ID - 2464 T2 - Intercellular Communication in Plants TI - Auxin as an intercellular signal VL - 16 ER - TY - CHAP AU - Dubová, J AU - Hejátko, Jan AU - Jirí Friml ED - Meyers, Robert A ID - 2463 T2 - Encyclopedia of Molecular Cell Biology and Molecular Medicine TI - Reproduction, plants VL - 12 ER - TY - JOUR AB - Hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels are involved in the control of neuronal excitability and plasticity. In this study, we used immunoblotting and immunohistochemical techniques to reveal the developmental expression and subcellular distribution of the HCN1 subunit in the cerebellar cortex. During postnatal development, the spatio-temporal expression of HCN1 correlated well with the morphological events occurring during the ontogenesis of cerebellar interneurons. Using immunoblotting techniques, HCN1 was weakly detected during the first postnatal week and continued to increase throughout postnatal development, peaking at postnatal day (P)15. At the light-microscopic level, HCN1 immunoreactivity was very weak until P7 whereas from P10-12 to adulthood it was strongly detected in the lower third of the molecular layer and in the Purkinje cell layer. HCN1 was present in axons running through the molecular layer and in the pericellular basket around Purkinje cells at P12, but in the periaxonal plexus (the pinceau) surrounding their initial segment only after P15. Using immunofluorescence, HCN1 colocalized with GAD65 and synaptophysin, demonstrating that the subunit was present in inhibitory axons and axon terminals. At the electron-microscopic level, in adulthood, HCN1 immunoparticles were detected at postsynaptic sites in basket and Purkinje cells but most immunoparticles were found at presynaptic sites in basket cell axons and in terminals. In the axon terminals, the distribution of HCN1 was relatively uniform along the extrasynaptic plasma membrane; this was confirmed using quantitative techniques. The present findings suggest that HCN1 channels may provide a significant route for modulating co-ordinated cerebellar synaptic transmission through basket cells. AU - Luján, Rafael AU - Albasanz, José L AU - Ryuichi Shigemoto AU - Juíz, José M ID - 2648 IS - 8 JF - European Journal of Neuroscience TI - Preferential localization of the hyperpolarization-activated cyclic nucleotide-gated cation channel subunit HCN1 in basket cell terminals of the rat cerebellum VL - 21 ER - TY - JOUR AB - Septohippocampal cholinergic neurons play key roles in learning and memory processes, and in the generation of hippocampal theta rhythm. The range of receptors for endogenous modulators expressed on these neurons is unclear. Here we describe GABAB 1a/b receptor (GABABR) and type 1 cannabinoid receptor (CB1R) expression in rat septal cholinergic [i.e. choline acetyltransferase (ChAT)-positive] cells. Using double immunofluorescent staining, we found that almost two-thirds of the cholinergic cells in the rat medial septum were GABABR positive, and that these cells had significantly larger somata than did GABABR-negative cholinergic neurons. We detected CB1R labelling in somata after axonal protein transport was blocked by colchicine. In these animals about one-third of the cholinergic cells were CB1R positive. These cells again had larger somata than CB1R-negative cholinergic neurons. The analyses confirmed that the size of GABABR-positive and CB 1R-positive cholinergic cells were alike, and all CB 1R-positive cholinergic cells were GABABR positive as well. CB1R-positive cells were invariably ChAT positive. All retrogradely labelled septohippocampal cholinergic cells were positive for GABABR and at least half of them also for CB1R. These data shed light on the existence of at least two cholinergic cell types in the medial septum: one expresses GABABR and CB1R, has large somata and projects to the hippocampus, whereas the other is negative for GABABR and CB1R and has smaller somata. The results also suggest that cholinergic transmission in the hippocampus is fine-tuned by endocannabinoid signalling. AU - Nyíri, Gábor AU - Szabadits, Eszter AU - Cserép, Csaba AU - Mackie, Ken P AU - Ryuichi Shigemoto AU - Freund, Tamás F ID - 2650 IS - 11 JF - European Journal of Neuroscience TI - GABAB and CB1 cannabinoid receptor expression identifies two types of septal cholinergic neurons VL - 21 ER - TY - GEN AB - Our understanding of the role played by neurotransmitter receptors in the developing brain has advanced in recent years. The major excitatory and inhibitory neurotransmitters in the brain, glutamate and GABA, activate both ionotropic (ligand-gated ion channels) and metabotropic (G protein-coupled) receptors, and are generally associated with neuronal communication in the mature brain. However, before the emergence of their role in neurotransmission in adulthood, they also act to influence earlier developmental events, some of which occur prior to synapse formation: such as proliferation, migration, differentiation or survival processes during neural development. To fulfill these actions in the constructing of the nervous system, different types of glutamate and GABA receptors need to be expressed both at the right time and at the right place. The identification by molecular cloning of 16 ionotropic glutamate receptor subunits, eight metabotropic glutamate receptor subtypes, 21 ionotropic and two metabotropic GABA receptor subunits, some of which exist in alternatively splice variants, has enriched our appreciation of how molecular diversity leads to functional diversity in the brain. It now appears that many different types of glutamate and GABA receptor subunits have prominent expression in the embryonic and/or postnatal brain, whereas others are mainly present in the adult brain. Although the significance of this differential expression of subunits is not fully understood, it appears that the change in subunit composition is essential for normal development in particular brain regions. This review focuses on emerging information relating to the expression and role of glutamatergic and GABAergic neurotransmitter receptors during prenatal and postnatal development. AU - Luján, Rafael AU - Ryuichi Shigemoto AU - López-Bendito, Guillermina ID - 2647 IS - 3 T2 - Neuroscience TI - Glutamate and GABA receptor signalling in the developing brain VL - 130 ER - TY - JOUR AB - The GABAergic system, a major inhibitory regulator in the central nervous system, may also play important roles in peripheral nonneuronal tissues and cells. Recent studies showed that GABAB receptor is expressed in testis and sperm. To understand the role of the GABAergic system in spermiogenesis, we examined cellular localization of GABA and GABAB receptor subunits in rat spermatids by immunocytochemistry. Immunoreactivity for GABA was detected around acrosomal granules of spermatids during the Golgi and cap phases. GABAB(1) immunoreactivity was observed in the acrosomal vesicle of spermatids in Golgi phase, and during cap phase, this reactivity expanded to the entire region of the acrosome covering the nuclear membrane. The level of reactivity decreased gradually with maturation of spermatids. In contrast, GABAB(2) immunoreactivity was not observed in spermatids during Golgi phase but was detected in the equatorial region during cap phase. Both GABA immunoreactivity and GABAB(2) immunoreactivity were transferred to the residual cytoplasm during the release of spermatozoa. Electron microscopic immunocytochemistry revealed that, during cap phase, GABA and GABAB(1) were distributed within the whole acrosomal vesicle but not in the acrosomal granule. GABAB(2) immunoreactivity was observed in the narrow space between the inner acrosomal and nuclear membrane and was limited to the equatorial region of the spermatid head. These results indicate that the GABAergic system might be involved in regulation of spermiogenesis. AU - Kanbara, Kiyoto AU - Okamoto, Keiko AU - Nomura, Sakashi AU - Kaneko, Takeshi AU - Ryuichi Shigemoto AU - Azuma, Haruhito AU - Katsuoka, Yoji AU - Watanabe, Masahiko ID - 2651 IS - 4 JF - Journal of Andrology TI - Cellular localization of GABA and GABAB receptor subunit proteins during spermiogenesis in rat testis VL - 26 ER - TY - JOUR AB - The number of ionotropic receptors in synapses is an essential factor for determining the efficacy of fast transmission. We estimated the number of functional AMPA receptors at single postsynaptic sites by a combination of two-photon uncaging of glutamate and the nonstationary fluctuation analysis in immature rat Purkinje cells (PCs), which receive a single type of excitatory input from climbing fibers. Areas of postsynaptic membrane specialization at the recorded synapses were measured by reconstruction of serial ultrathin sections. The number of functional AMPA receptors was proportional to the synaptic area with a density of ∼ 1280 receptors/μm 2. Moreover, highly sensitive freeze-fracture replica labeling revealed a homogeneous density of immunogold particles for AMPA receptors in synaptic sites (910 ± 36 particles/μm 2) and much lower density in extrasynaptic sites (19 ± 2 particles/μm 2) in the immature PCs. Our results indicate that in this developing synapse, the efficacy of transmission is determined by the synaptic area. AU - Tanaka, Junichi AU - Matsuzaki, Masanori AU - Tarusawa, Etsuko AU - Momiyama, Akiko AU - Molnár, Elek AU - Kasai, Haruo AU - Ryuichi Shigemoto ID - 2649 IS - 4 JF - Journal of Neuroscience TI - Number and density of AMPA receptors in single synapses in immature cerebellum VL - 25 ER - TY - JOUR AB - Presynaptic metabotropic glutamate receptors (mGluRs) show a highly selective expression and subcellular location in nerve terminals modulating neurotransmitter release. We have demonstrated that alternatively spliced variants of mGluR8, mGluR8a and mGluR8b, have an overlapping distribution in the hippocampus, and besides perforant path terminals, they are expressed in the presynaptic active zone of boutons making synapses selectively with several types of GABAergic interneurons, primarily in the stratum oriens. Boutons labeled for mGluR8 formed either type I or type II synapses, and the latter were GABAergic. Some mGluR8-positive boutons also expressed mGluR7 or vasoactive intestinal polypeptide. Interneurons strongly immunopositive for the muscarinic M2 or the mGlu1 receptors were the primary targets of mGluR8-containing terminals in the stratum oriens, but only neurochemically distinct subsets were innervated by mGluR8-enriched terminals. The majority of M2-positive neurons were mGluR8 innervated, but a minority, which expresses somatostatin, was not. Rare neurons coexpressing calretinin and M2 were consistently targeted by mGluR8-positive boutons. In vivo recording and labeling of an mGluR8-decorated and strongly M2-positive interneuron revealed a trilaminar cell with complex spike bursts during theta oscillations and strong discharge during sharp wave/ripple events. The trilaminar cell had a large projection from the CA1 area to the subiculum and a preferential innervation of interneurons in the CA1 area in addition to pyramidal cell somata and dendrites. The postsynaptic interneuron type-specific expression of the high-efficacy presynaptic mGluR8 in both putative glutamatergic and in identified GABAergic terminals predicts a role in adjusting the activity of interneurons depending on the level of network activity. AU - Ferraguti, Francesco AU - Klausberger,Thomas AU - Cobden, Philip M AU - Baude, Agnès AU - Roberts, John D AU - Szűcs, Péter AU - Kinoshita, Ayae AU - Ryuichi Shigemoto AU - Somogyi, Péter AU - Dalezios, Yannis ID - 2654 IS - 45 JF - Journal of Neuroscience TI - Metabotropic glutamate receptor 8-expressing nerve terminals target subsets of GABAergic neurons in the hippocampus VL - 25 ER - TY - JOUR AB - Enhanced glutamatergic neurotransmission via the subthalamopallidal or subthalamonigral projection seems crucial for developing parkinsonian motor signs. In the present study, the possible changes in the expression of metabotropic glutamate receptors (mGluRs) were examined in the basal ganglia of a primate model for Parkinson's disease. When the patterns of immunohistochemical localization of mGluRs in monkeys administered systemically with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were analysed in comparison with normal controls, we found that expression of mGluR1α, but not of other subtypes, was significantly reduced in the internal and external segments of the globus pallidus and the substantia nigra pars reticulata. To elucidate the functional role of mGluR1 in the control of pallidal neuron activity, extracellular unit recordings combined with intrapallidal microinjections of mGluR1-related agents were then performed in normal and parkinsonian monkeys. In normal awake conditions, the spontaneous firing rates of neurons in the pallidal complex were increased by DHPG, a selective agonist of group I mGluRs, whereas they were decreased by AIDA, a selective antagonist of group I mGluRs, or LY367385, a selective antagonist of mGluR1. These electrophysiological data strongly indicate that the excitatory mechanism of pallidal neurons by glutamate is mediated at least partly through mGluR1. The effects of the mGluR1-related agents on neuronal firing in the internal pallidal segment became rather obscure after MPTP treatment. Our results suggest that the specific down-regulation of pallidal and nigral mGluR1 ot in the parkinsonian state may exert a compensatory action to reverse the overactivity of the subthalamic nucleus-derived glutamatergic input that is generated in the disease. AU - Kaneda, Katsuyuki AU - Tachibana, Yoshihisa AU - Imanishi, Michiko AU - Kita, Hitoshi AU - Ryuichi Shigemoto AU - Nambu, Atsushi AU - Takada, Masahiko ID - 2658 IS - 12 JF - European Journal of Neuroscience TI - Down-regulation of metabotropic glutamate receptor 1α in globus pallidus and substantia nigra of parkinsonian monkeys VL - 22 ER - TY - JOUR AB - We studied neurogliaform neurons in the stratum lacunosum moleculare of the CA1 hippocampal area. These interneurons have short stellate dendrites and an extensive axonal arbor mainly located in the stratum lacunosum moleculare. Single-cell reverse transcription-PCR showed that these neurons were GABAergic and that the majority expressed mRNA for neuropeptide Y. Most neurogliaform neurons tested were immunoreactive for α-actinin-2, and many stratum lacunosum moleculare interneurons coexpressed α-actinin-2 and neuropeptide Y. Neurogliaform neurons received monosynaptic, DNQX-sensitive excitatory input from the perforant path, and 40 Hz stimulation of this input evoked EPSCs displaying either depression or initial facilitation, followed by depression. Paired recordings performed between neurogliaform neurons showed that 85% of pairs were electrically connected and 70% were also connected via GABAergic synapses. Injection of sine waveforms into neurons during paired recordings resulted in transmission of the waveforms through the electrical synapse. Unitary IPSCs recorded from neurogliaform pairs readily fatigued, had a slow decay, and had a strong depression of the synaptic response at a 5 Hz stimulation frequency that was antagonized by the GABA B antagonist (2S)-3-[[(1S)-1-(3,4-dichlorophenyl)ethyl]amino-2-hydroxypropyl](phenylmethyl) phosphinic acid (CGP55845). The amplitude of the first IPSC during the 5 Hz stimulation was also increased by CGP55845, suggesting a tonic inhibition of synaptic transmission. A small unitary GABA B-mediated IPSC could also be detected, providing the first evidence for such a component between GABAergic interneurons. Electron microscopic localization of the GABA B1 subunit at neurogliaform synapses revealed the protein in both presynaptic and postsynaptic membranes. Our data disclose a novel interneuronal network well suited for modulating the flow of information between the entorhinal cortex and CA1 hippocampus. AU - Price, Christopher J AU - Cauli, Bruno AU - Kovács, Endre R AU - Kulik, Ákos AU - Lambolez, Bertrand AU - Ryuichi Shigemoto AU - Capogna,Marco ID - 2652 IS - 29 JF - Journal of Neuroscience TI - Neurogliaform neurons form a novel inhibitory network in the hippocampal CA1 area VL - 25 ER - TY - JOUR AB - Input-dependent left-right asymmetry of NMDA receptor ε2 (NR2B) subunit allocation was discovered in hippocampal Schaffer collateral (Sch) and commissural fiber pyramidal cell synapses (Kawakami et al., 2003). To investigate whether this asymmetrical ε2 allocation is also related to the types of the postsynaptic cells, we compared postembedding immunogold labeling for ε2 in left and right Sch synapses on pyramidal cells and interneurons. To facilitate the detection of ε2 density difference, we used ε1 (NR2A) knock-out (KO) mice, which have a simplified NMDA receptor subunit composition. The labeling density for ε2 but not ζ1 (NR1) and subtype 2/3 glutamate receptor (GluR2/3) in Sch-CA1 pyramidal cell synapses was significantly different between the left and right hippocampus with opposite directions in strata oriens and radiatum; the left to right ratio of ε2 labeling density was 1:1.50 in stratum oriens and 1.44:1 in stratum radiatum. No significant difference, however, was detected in CA1 stratum radiatum between the left and right Sch-GluR4-positive (mostly parvalbumin-positive) and Sch-GluR4-negative interneuron synapses. Consistent with the anatomical asymmetry, the amplitude ratio of NMDA EPSCs to non-NMDA EPSCs in pyramidal cells was approximately two times larger in right than left stratum radiatum and vice versa in stratum oriens of ε1 KO mice. Moreover, the amplitude of long-term potentiation in the Sch-CA1 synapses of left stratum radiatum was significantly larger than that in the right corresponding synapses. These results indicate that the asymmetry of ε2 distribution is target cell specific, resulting in the left-right difference in NMDA receptor content and plasticity in Sch-CA1 pyramidal cell synapses in ε1 KO mice. AU - Wu, Yue AU - Kawakami, Ryosuke AU - Shinohara, Yoshiaki AU - Fukaya, Masahiro AU - Sakimura, Kenji AU - Mishina, Masayoshi AU - Watanabe, Masahiko AU - Ito, Isao AU - Ryuichi Shigemoto ID - 2655 IS - 40 JF - Journal of Neuroscience TI - Target-cell-specific left-right asymmetry of NMDA receptor content in Schaffer collateral synapses in ε1/NR2A knock-out mice VL - 25 ER - TY - JOUR AB - Synaptic vesicle release occurs at a specialized membrane domain known as the presynaptic active zone (AZ). Several membrane proteins are involved in the vesicle release processes such as docking, priming, and exocytotic fusion. Cytomatrix at the active zone (CAZ) proteins are structural components of the AZ and are highly concentrated in it. Localization of other release-related proteins including target soluble N-ethylmaleimide-sensitive-factor attachment protein receptor (t-SNARE) proteins, however, has not been well demonstrated in the AZ. Here, we used sodium dodecyl sulfate-digested freeze-fracture replica labeling (SDS-FRL) to analyze quantitatively the distribution of CAZ and t-SNARE proteins in the hippocampal CA3 area. The AZ in replicated membrane was identified by immunolabeling for CAZ proteins (CAZ-associated structural protein [CAST] and Bassoon). Clusters of immunogold particles for these proteins were found on the P-face of presynaptic terminals of the mossy fiber and associational/commissural (AJC) fiber. Co-labeling with CAST revealed distribution of the t-SNARE proteins syntaxin and synaptosomal-associated protein of 25 kDa (SNAP-25) in the AZ as well as in the extrasynaptic membrane surrounding the AZ (SZ). Quantitative analysis demonstrated that the density of immunoparticles for CAST in the AZ was more than 100 times higher than in the SZ, whereas that for syntaxin and SNAP-25 was not significantly different between the AZ and SZ in both the A/C and mossy fiber terminals. These results support the involvement of the t-SNARE proteins in exocytotic fusion in the AZ and the role of CAST in specialization of the membrane domain for the AZ. AU - Hagiwara, Akari AU - Fukazawa, Yugo AU - Deguchi-Tawarada, Maki AU - Ohtsuka, Toshihisa AU - Ryuichi Shigemoto ID - 2653 IS - 2 JF - Journal of Comparative Neurology TI - Differential distribution of release-related proteins in the hippocampal CA3 area as revealed by freeze-fracture replica labeling VL - 489 ER - TY - JOUR AB - Previous studies have shown that neurons in the sacral dorsal commissural nucleus (SDCN) express neurokinin-1 receptor (NK1R) and can be modulated by the co-release of GABA and glycine (Gly) from single presynaptic terminal. These results raise the possibility that GABA/Gly-cocontaining terminals might make synaptic contacts with NK1R-expressing neurons in the SDCN. In order to provide morphological evidence for this hypothesis, the triple-immunohistochemical studies were performed in the SDCN. Triple-immunofluorescence histochemical study showed that some axon terminals in close association with NK1R-immunopositive (NK1R-ip) neurons in the SDCN were immunopositive for both glutamic acid decarboxylase (GAD) and glycine transporter 2 (GlyT2). In electron microscopic dual- and triple-immunohistochemistry for GAD/GlyT2, GAD/NK1R, GlyT2/NK1R, or GAD/GlyT2/NK1R also revealed dually labeled (GAD/GlyT2-ip) synaptic terminals upon SDCN neurons, as well as GAD- and/or GlyT2-ip axon terminals in synaptic contact with NK1R-ip SDCN neurons. These results suggested that some synaptic terminals upon NK1R-expressing SDCN neurons co-released both GABA and Gly. AU - Feng, Yu-Peng AU - Li, Yun-Qing AU - Wang, Wen AU - Wu, Sheng-Xi AU - Chen, Tao AU - Ryuichi Shigemoto AU - Mizuno, Noboru ID - 2656 IS - 3 JF - Neuroscience Letters TI - Morphological evidence for GABA/glycine-cocontaining terminals in synaptic contact with neurokinin-1 receptor-expressing neurons in the sacral dorsal commissural nucleus of the rat VL - 388 ER - TY - JOUR AB - We study the long time evolution of a quantum particle interacting with a random potential in the Boltzmann-Grad low density limit. We prove that the phase space density of the quantum evolution defined through the Husimi function converges weakly to a linear Boltzmann equation. The Boltzmann collision kernel is given by the full quantum scattering cross-section of the obstacle potential. AU - Eng, David AU - László Erdös ID - 2744 IS - 6 JF - Reviews in Mathematical Physics TI - The linear Boltzmann equation as the low density limit of a random Schrödinger equation VL - 17 ER - TY - JOUR AB - We consider the supersymmetric quantum mechanical system which is obtained by dimensionally reducing d = 6, N = 1 supersymmetric gauge theory with gauge group U(1) and a single charged hypermultiplet. Using the deformation method and ideas introduced by Porrati and Rozenberg [1], we present a detailed proof of the existence of a normalizable ground state for this system. AU - László Erdös AU - Hasler, David G AU - Solovej, Jan P ID - 2743 IS - 2 JF - Annales Henri Poincare TI - Existence of the D0-D4 bound state: A detailed proof VL - 6 ER - TY - JOUR AB - We present the results of an experimental investigation into the nature and structure of turbulent pipe flow at moderate Reynolds numbers. A turbulence regeneration mechanism is identified which sustains a symmetric traveling wave within the flow. The periodicity of the mechanism allows comparison to the wavelength of numerically observed exact traveling wave solutions and close agreement is found. The advection speed of the upstream turbulence laminar interface in the experimental flow is observed to form a lower bound on the phase velocities of the exact traveling wave solutions. Overall our observations suggest that the dynamics of the turbulent flow at moderate Reynolds numbers are governed by unstable nonlinear traveling waves. AU - Björn Hof AU - van Doorne, Casimir W AU - Westerweel, Jerry AU - Nieuwstadt, Frans T ID - 2788 IS - 21 JF - Physical Review Letters TI - Turbulence regeneration in pipe flow at moderate reynolds numbers VL - 95 ER - TY - JOUR AB - We present the results of an experimental investigation of the effect of a magnetic field on the stability of convection in a liquid metal. A rectangular container of gallium is subjected to a horizontal temperature gradient and a uniform magnetic field is applied separately in three directions. The magnetic field suppresses the oscillation most effectively when it is applied in the vertical direction and is least efficient when applied in the direction of the temperature gradient. The critical temperature difference required for the onset of oscillations is found to scale exponentially with the magnitude of the magnetic field for all three orientations. Comparisons are made with available theory and qualitative differences are discussed. AU - Björn Hof AU - Juel, Anne AU - Mullin, Tom P ID - 2790 JF - Journal of Fluid Mechanics TI - Magnetohydrodynamic damping of oscillations in low-Prandtl-number convection VL - 545 ER - TY - JOUR AB - Transitional pipe flow is investigated in two different experimental set-ups. In the first the stability threshold and the initial growth of localized perturbations are studied. Good agreement is found with an earlier investigation of the transition threshold. The measurement technique applied in the last part of this study allows the reconstruction of the streamwise vorticity in a turbulent puff. AU - Björn Hof ID - 2789 JF - Fluid Mechanics and its Applications TI - Transition to turbulence in pipe flow VL - 77 ER - TY - JOUR AB - The plant hormone auxin elicits many specific context-dependent developmental responses. Auxin promotes degradation of Aux/IAA proteins that prevent transcription factors of the auxin response factor (ARF) family from regulating auxin-responsive target genes. Aux/IAAs and ARFs are represented by large gene families in Arabidopsis. Here we show that stabilization of BDL/IAA12 or its sister protein IAA13 prevents MP/ARF5-dependent embryonic root formation whereas stabilized SHY2/IAA3 interferes with seedling growth. Although both bdl and shy2-2 proteins inhibited MP/ARF5-dependent reporter gene activation, shy2-2 was much less efficient than bdl to interfere with embryonic root initiation when expressed from the BDL promoter. Similarly, MP was much more efficient than ARF16 in this process. When expressed from the SHY2 promoter, both shy2-2 and bdl inhibited cell elongation and auxin-induced gene expression in the seedling hypocotyl. By contrast, gravitropism and auxin-induced gene expression in the root, which were promoted by functionally redundant NPH4/ARF7 and ARF19 proteins, were inhibited by shy2-2, but not by bdl protein. Our results suggest that auxin signals are converted into specific responses by matching pairs of coexpressed ARF and Aux/IAA proteins. AU - Weijers, Dolf AU - Eva Benková AU - Jäger, Katja E AU - Schlereth, Alexandra AU - Hamann, Thorsten AU - Kientz, Marika AU - Wilmoth, Jill C AU - Reed, Jason W AU - Jürgens, Gerd ID - 2867 IS - 10 JF - EMBO Journal TI - Developmental specificity of auxin response by pairs of ARF and Aux/IAA transcriptional regulators VL - 24 ER - TY - JOUR AB - One of the fundamental properties of the immune system is its capacity to avoid autoimmune diseases. The mechanism underlying this process, known as self-tolerance, is hitherto unresolved but seems to involve the control of clonal expansion of autoreactive lymphocytes. This article reviews mathematical modeling of self-tolerance, addressing two specific hypotheses. The first hypothesis posits that self-tolerance is mediated by tuning of activation thresholds, which makes autoreactive T lymphocytes reversibly "anergic" and unable to proliferate. The second hypothesis posits that the proliferation of autoreactive T lymphocytes is instead controlled by specific regulatory T lymphocytes. Models representing the population dynamics of autoreactive T lymphocytes according to these two hypotheses were derived. For each model we identified how cell density affects tolerance, and predicted the corresponding phase spaces and bifurcations. We show that the simple induction of proliferative anergy, as modeled here, has a density dependence that is only partially compatible with adoptive transfers of tolerance, and that the models of tolerance mediated by specific regulatory T cells are closer to the observations. AU - Carneiro, Jorge AU - Tiago Paixao AU - Milutinovic, Dejan AU - Sousa, João AU - Leon, Kalet AU - Gardner, Rui AU - Faro, Jose ID - 2895 IS - 1 JF - Journal of Computational and Applied Mathematics TI - Immunological self tolerance: Lessons from mathematical modeling VL - 184 ER - TY - JOUR AB - Molecular mechanisms of pattern formation in the plant embryo are not well understood. Recent molecular and cellular studies, in conjunction with earlier microsurgical, physiological, and genetic work, are now starting to define the outlines of a model where gradients of the signaling molecule auxin play a central role in embryo patterning. It is relatively clear how these gradients are established and interpreted, but how they are maintained is still unresolved. Here, we have studied the contributions of auxin biosynthesis, conjugation, and transport pathways to the maintenance of embryonic auxin gradients. Auxin homeostasis in the embryo was manipulated by region-specific conditional expression of indoleacetic acid-tryptophan monooxygenase or indoleacetic acid-lysine synthetase, bacterial enzymes for auxin biosynthesis or conjugation. Neither manipulation of auxin biosynthesis nor of auxin conjugation interfered with auxin gradients and patterning in the embryo. This result suggests a compensatory mechanism for buffering auxin gradients in the embryo. Chemical and genetic inhibition revealed that auxin transport activity, in particular that of the PIN-FORMED1 (PIN1) and PIN4 proteins, is a major factor in the maintenance of these gradients. AU - Weijers, Dolf AU - Sauer, Michael AU - Meurette, Olivier AU - Jirí Friml AU - Ljung, Karin AU - Sandberg, Göran AU - Hooykaas, Paul AU - Offringa, Remko ID - 3004 IS - 9 JF - Plant Cell TI - Maintenance of embryonic auxin distribution for apical basal patterning by PIN FORMED dependent auxin transport in Arabidopsis VL - 17 ER - TY - JOUR AB - In plants, cell polarity is an issue more recurring than in other systems, because plants, due to their adaptive and flexible development, often change cell polarity postembryonically according to intrinsic cues and demands of the environment. Recent findings on the directional movement of the plant signalling molecule auxin provide a unique connection between individual cell polarity and the establishment of polarity at the tissue, organ, and whole-plant levels. Decisions about the subcellular polar targeting of PIN auxin transport components determine the direction of auxin flow between cells and consequently mediate multiple developmental events. In addition, mutations or chemical interference with PIN-based auxin transport result in abnormal cell divisions. Thus, the complicated links between cell polarity establishment, auxin transport, cytoskeleton, and oriented cell divisions now begin to emerge. Here we review the available literature on the issues of cell polarity in both plants and animals to extend our understanding on the generation, maintenance, and transmission of cell polarity in plants. AU - Dhonukshe, Pankaj AU - Kleine Vehn, Jürgen AU - Friml, Jirí ID - 3000 IS - 1-2 JF - Protoplasma TI - Cell polarity, auxin transport and cytoskeleton mediated division planes: Who comes first? VL - 226 ER - TY - JOUR AB - One of the mechanisms by which signalling molecules regulate cellular behaviour is modulating subcellular protein translocation. This mode of regulation is often based on specialized vesicle trafficking, termed constitutive cycling, which consists of repeated internalization and recycling of proteins to and from the plasma membrane. No such mechanism of hormone action has been shown in plants although several proteins, including the PIN auxin efflux facilitators, exhibit constitutive cycling. Here we show that a major regulator of plant development, auxin, inhibits endocytosis. This effect is specific to biologically active auxins and requires activity of the Calossin-like protein BIG. By inhibiting the internalization step of PIN constitutive cycling, auxin increases levels of PINs at the plasma membrane. Concomitantly, auxin promotes its own efflux from cells by a vesicle-trafficking-dependent mechanism. Furthermore, asymmetric auxin translocation during gravitropism is correlated with decreased PIN internalization. Our data imply a previously undescribed mode of plant hormone action: by modulating PIN protein trafficking, auxin regulates PIN abundance and activity at the cell surface, providing a mechanism for the feedback regulation of auxin transport. AU - Paciorek, Tomasz AU - Zažímalová, Eva AU - Ruthardt, Nadia AU - Petrášek, Jan AU - Stierhof, York-Dieter AU - Kleine-Vehn, Jürgen AU - Morris, David A AU - Emans, Neil AU - Jürgens, Gerd AU - Geldner, Niko AU - Jirí Friml ID - 3001 IS - 7046 JF - Nature TI - Auxin inhibits endocytosis and promotes its own efflux from cells VL - 435 ER - TY - JOUR AB - Plant development displays an exceptional plasticity and adaptability that involves the dynamic, asymmetric distribution of the phytohormone auxin. Polar auxin flow, which requires polarly localized transport facilitators of the PIN family, largely contributes to the establishment and maintenance of the auxin gradients. Functionally overlapping action of PIN proteins mediates multiple developmental processes, including embryo formation, organ development and tropisms. Here we show that PIN proteins exhibit synergistic interactions, which involve cross-regulation of PIN gene expression in pin mutants or plants with inhibited auxin transport. Auxin itself positively feeds back on PIN gene expression in a tissue-specific manner through an AUX/IAA-dependent signalling pathway. This regulatory switch is indicative of a mechanism by which the loss of a specific PIN protein is compensated for by auxin-dependent ectopic: expression of its homologues. The compensatory properties of the PIN-dependent transport network might enable the stabilization of auxin gradients and potentially contribute to the robustness of plant adaptive development. AU - Vieten, Anne AU - Vanneste, Steffen AU - Wiśniewska, Justyna AU - Eva Benková AU - Benjamins, René AU - Beeckman, Tom AU - Luschnig, Christian AU - Jirí Friml ID - 3003 IS - 20 JF - Development TI - Functional redundancy of PIN proteins is accompanied by auxin-dependent cross-regulation of PIN expression VL - 132 ER - TY - CONF AB - The Full-Domain Hash (FDH) signature scheme [3] forms one the most basic usages of random oracles. It works with a family F of trapdoor permutations (TDP), where the signature of m is computed as f−1(h(m)) (here f ∈R F and h is modelled as a random oracle). It is known to be existentially unforgeable for any TDP family F [3], although a much tighter security reduction is known for a restrictive class of TDP’s [10,14] — namely, those induced by a family of claw-free permutations (CFP) pairs. The latter result was shown [11] to match the best possible “black-box” security reduction in the random oracle model, irrespective of the TDP family F (e.g., RSA) one might use. In this work we investigate the question if it is possible to instantiate the random oracle h with a “real” family of hash functions H such that the corresponding schemes can be proven secure in the standard model, under some natural assumption on the family F. Our main result rules out the existence of such instantiations for any assumption on F which (1) is satisfied by a family of random permutations; and (2) does not allow the attacker to invert f ∈R F on an a-priori unbounded number of points. Moreover, this holds even if the choice of H can arbitrarily depend on f. As an immediate corollary, we rule out instantiating FDH based on general claw-free permutations, which shows that in order to prove the security of FDH in the standard model one must utilize significantly more structure on F than what is sufficient for the best proof of security in the random oracle model. AU - Dodis, Yevgeniy AU - Oliveira, Roberto AU - Krzysztof Pietrzak ID - 3212 TI - On the generic insecurity of the full domain hash VL - 3621 ER - TY - CONF AB - We study the question whether the sequential or parallel composition of two functions, each indistinguishable from a random function by non-adaptive distinguishers is secure against adaptive distinguishers. The sequential composition of F and G is the function G(F()), the parallel composition is F G where ⋆ is some group operation. It has been shown that composition indeed gives adaptive security in the information theoretic setting, but unfortunately the proof does not translate into the more interesting computational case. In this work we show that in the computational setting composition does not imply adaptive security: If there is a prime order cyclic group where the decisional Diffie-Hellman assumption holds, then there are functions F and G which are indistinguishable by non-adaptive polynomially time-bounded adversaries, but whose parallel composition can be completely broken (i.e. we recover the key) with only three adaptive queries. We give a similar result for sequential composition. Interestingly, we need a standard assumption from the asymmetric (aka. public-key) world to prove a negative result for symmetric (aka. private-key) systems. AU - Krzysztof Pietrzak ID - 3213 TI - Composition does not imply adaptive security VL - 3621 ER - TY - CONF AB - We present an improved bound on the advantage of any q-query adversary at distinguishing between the CBC MAC over a random n-bit permutation and a random function outputting n bits. The result assumes that no message queried is a prefix of any other, as is the case when all messages to be MACed have the same length. We go on to give an improved analysis of the encrypted CBC MAC, where there is no restriction on queried messages. Letting m be the block length of the longest query, our bounds are about mq2/2n for the basic CBC MAC and mo(1)q2/2n for the encrypted CBC MAC, improving prior bounds of m2q2/2n. The new bounds translate into improved guarantees on the probability of forging these MACs. AU - Bellare, Mihir AU - Krzysztof Pietrzak AU - Rogaway, Phillip ID - 3211 TI - Improved security analyses for CBC MACs VL - 3621 ER - TY - JOUR AB - We discuss the formation of graded morphogen profiles in a cell layer by nonlinear transport phenomena, important for patterning developing organisms. We focus on a process termed transcytosis, where morphogen transport results from the binding of ligands to receptors on the cell surface, incorporation into the cell, and subsequent externalization. Starting from a microscopic model, we derive effective transport equations. We show that, in contrast to morphogen transport by extracellular diffusion, transcytosis leads to robust ligand profiles which are insensitive to the rate of ligand production. AU - Bollenbach, Mark Tobias AU - Kruse, Karsten AU - Pantazis, Periklis AU - González Gaitán, Marcos AU - Jülicher, Frank ID - 3426 IS - 1 JF - Physical Review Letters TI - Robust formation of morphogen gradients VL - 94 ER - TY - JOUR AB - In the hippocampal CA1 area, a relatively homogenous population of pyramidal cells is accompanied by a diversity of GABAergic interneurons. Previously, we found that parvalbumin-expressing basket, axo-axonic, bistratified, and oriens-lacunosum moleculare cells, innervating different domains of pyramidal cells, have distinct firing patterns during network oscillations in vivo. A second family of interneurons, expressing cholecystokinin but not parvalbumin, is known to target the same domains of pyramidal cells as do the parvalbumin cells. To test the temporal activity of these independent and parallel GABAergic inputs, we recorded the precise spike timing of identified cholecystokinin interneurons during hippocampal network oscillations in anesthetized rats and determined their molecular expression profiles and synaptic targets. The cells were cannabinoid receptor type 1 immunopositive. Contrary to the stereotyped firing of parvalbumin interneurons, cholecystokinin-expressing basket and dendrite-innervating cells discharge, on average, with 1.7 ± 2.0 Hz during high-frequency ripple oscillations in an episode-dependent manner. During theta oscillations, cholecystokinin- expressing interneurons fire with 8.8 ± 3.3 Hz at a characteristic time on the ascending phase of theta waves (155 ± 81°), when place cells start firing in freely moving animals. The firing patterns of some interneurons recorded in drug-free behaving rats were similar to cholecystokinin cells in anesthetized animals. Our results demonstrate that cholecystokinin- and parvalbumin-expressing interneurons make different contributions to network oscillations and play distinct roles in different brain states. We suggest that the specific spike timing of cholecystokinin interneurons and their sensitivity to endocannabinoids might contribute to differentiate subgroups of pyramidal cells forming neuronal assemblies, whereas parvalbumin interneurons contribute to synchronizing the entire network. Copyright © 2005 Society for Neuroscience. AU - Klausberger,Thomas AU - Marton,Laszlo F AU - Joseph O'Neill AU - Huck, Jojanneke H AU - Dalezios, Yannis AU - Fuentealba,Pablo AU - Suen, Wai Yee AU - Papp, Edit Cs AU - Kaneko, Takeshi AU - Watanabe, Masahiko AU - Jozsef Csicsvari AU - Somogyi, Péter ID - 3443 IS - 42 JF - Journal of Neuroscience TI - Complementary roles of cholecystokinin- and parvalbumin-expressing GABAergic neurons in hippocampal network oscillations VL - 25 ER - TY - CONF AB - A challenging problem in computer-aided geometric design is the decomposition of a surface into four-sided regions that are then represented by NURBS patches. There are various approaches published in the literature and implemented as commercially available software, but all fall short in either automation or quality of the result. At Raindrop Geomagic, we have recently taken a fresh approach based on concepts from Morse theory. This by itself is not a new idea, but we have some novel ingredients that make this work, one being a rational notion of hierarchy that guides the construction of a simplified decomposition sensitive to only the major critical points. AU - Herbert Edelsbrunner ID - 3557 TI - Surface tiling with differential topology ER - TY - CHAP AB - During zebrafish gastrulation, the interplay between patterning events and morphogenesis creates an embryo out of a seemingly unstructured blastula stage embryo, an embryo with distinct polarities along its anterior–posterior, dorsoventral and left–right axes at the end of gastrulation. AU - Köppen, Mathias AU - Heisenberg, Carl-Philipp J ID - 3589 T2 - Encyclopedia of Life Sciences TI - Cleavage and gastrulation in zebrafish embryos ER - TY - CHAP AU - Castanon Ortega, Irinka AU - Heisenberg, Carl-Philipp J ED - Wedlich, Doris ID - 3588 T2 - Cell Migration in Development and Disease TI - Cell migration during zebrafish gastrulation ER - TY - GEN AU - Castanon Ortega, Irinka AU - Heisenberg, Carl-Philipp J ID - 3590 IS - 1 T2 - Nature Cell Biology TI - A stern view of gastrulation VL - 7 ER - TY - CONF AB - Digital cameras have become almost ubiquitous and their use for fast and casual capturing of natural images is unchallenged. For making images of documents, however, they have not caught up to flatbed scanners yet, mainly because camera images tend to suffer from distortion due to the perspective and are therefore limited in their further use for archival or OCR. For images of non-planar paper surfaces like books, page curl causes additional distortion, which poses an even greater problem due to its nonlinearity. This paper presents a new algorithm for removing both perspective and page curl distortion. It requires only a single camera image as input and relies on a priori layout information instead of additional hardware. Therefore, it is much more user friendly than most previous approaches, and allows for flexible ad hoc document capture. Results are presented showing that the algorithm produces visually pleasing output and increases OCR accuracy, thus having the potential to become a general purpose preprocessing tool for camera based document capture. AU - Ulges, Adrian AU - Christoph Lampert AU - Breuel,Thomas M ID - 3689 TI - Document image dewarping using robust estimation of curled text lines VL - 2 ER - TY - CONF AB - Ever since text processors became popular, users have dreamt of handling documents printed on paper as comfortably as electronic ones, with full text search typically appearing very close to the top of the wish list. This paper presents the design of a prototype system that takes a step into this direction. The user’s desktop is continuously monitored and of each detected document a high resolution snapshot is taken using a digital camera. The resulting image is processed using specially designed dewarping and OCR algorithms, making a digital and fully searchable version of the document available to the user in real-time. These steps are performed without any user interaction. This enables the system to run as a background task without disturbing the user in her work, while at the same time offering electronic access to all paper documents that have been present on the desktop during the uptime of the system. AU - Christoph Lampert AU - Braun,Tim AU - Ulges, Adrian AU - Keysers,Daniel AU - Breuel,Thomas M ID - 3684 TI - Oblivious document capture and real-time retrieval ER - TY - JOUR AU - Guzmán, José AU - Gerevich, Zoltan AU - Hengstler, Jan AU - Illes, Peter AU - Kleemann, Werner ID - 3720 IS - 4 JF - Synapse TI - P2Y1 receptors inhibit both strength and plasticity of glutamatergic synaptic neurotransmission in the rat prefrontal cortex. VL - 57 ER - TY - JOUR AB - Characterizing the dynamics of specific RNA levels requires real-time RNA profiling in a single cell. We show that the combination of a synthetic modular genetic system with fluorescence correlation spectroscopy allows us to directly measure in real time the activity of any specific promoter in prokaryotes. Using a simple inducible gene expression system, we found that induced RNA levels within a single bacterium of Escherichia coli exhibited a pulsating profile in response to a steady input of inducer. The genetic deletion of an efflux pump system, a key determinant of antibiotic resistance, altered the pulsating transcriptional dynamics and caused overexpression of induced RNA. In contrast with population measurements, real-time RNA profiling permits identifying relationships between genotypes and transcriptional dynamics that are accessible only at the level of the single cell. AU - Le,Thuc T. AU - Harlepp, Sébastien AU - Calin Guet AU - Dittmar,Kimberly AU - Emonet,Thierry AU - Pan,Tao AU - Cluzel,Philippe ID - 3753 IS - 26 JF - PNAS TI - Real-time RNA profiling within a single bacterium VL - 102 ER - TY - JOUR AB - The generation of realistic motion satisfying user-defined requirements is one of the most important goals of computer animation. Our aim in this paper is the synthesis of realistic, controllable motion for lightweight natural objects in a gaseous medium. We formulate this problem as a large-scale spacetime optimization with user controls and fluid motion equations as constraints. We have devised novel and effective methods to make this large optimization tractable. Initial trajectories are generated with data-driven synthesis based on stylistic motion planning. Smoothed particle hydrodynamics (SPH) is used during optimization to produce fluid simulations at a reasonable computational cost, while interesting vortex-based fluid motion is generated by recording the presence of vortices in the initial trajectories and maintaining them through optimization. Object rotations are refined as a postprocess to enhance the visual quality of the results. We demonstrate our techniques on a number of animations involving single or multiple objects. AU - Shi, Lin AU - Yu, Yizhou AU - Wojtan, Christopher J AU - Chenney, Stephen ID - 3763 IS - 7 JF - The Visual Computer TI - Controllable motion synthesis in a gaseous medium VL - 21 ER - TY - GEN AB - Hippocampal GABAergic interneurons show diverse molecular and morphological properties. The functional significance of this diversity for information processing is poorly understood. Here we show that cholecystokinin (CCK)-expressing interneurons in rat dentate gyrus release GABA in a highly asynchronous manner, in contrast to parvalbumin (PV) interneurons. With a gamma-frequency burst of ten action potentials, the ratio of asynchronous to synchronous release is 3:1 in CCK interneurons but is 1:5 in parvalbumin interneurons. N-type channels trigger synchronous and asynchronous release in CCK interneuron synapses, whereas P/Q-type Ca(2+) channels mediate release at PV interneuron synapses. Effects of Ca(2+) chelators suggest that both a long-lasting presynaptic Ca(2+) transient and a large distance between Ca(2+) source and sensor of exocytosis contribute to the higher ratio of asynchronous to synchronous release in CCK interneuron synapses. Asynchronous release occurs at physiological temperature and with behaviorally relevant stimulation patterns, thus generating long-lasting inhibition in the brain. AU - Hefft, Stefan AU - Peter Jonas ID - 3812 IS - 10 T2 - Nature Neuroscience TI - Asynchronous GABA release generates long-lasting inhibition at a hippocampal interneuron-principal neuron synapse (Review) VL - 8 ER - TY - CONF AB - Temporal Logic Model Checking is one of the most potent tools for the verification of finite state systems. Computation Tree Logic (CTL) has gained popularity because unlike most other logics, CTL model checking of a single transition system can be achieved in polynomial time. However, in most real-life problems, specially in distributed and parallel systems, the system consist of a set of concurrent processes and the verification problem translates to model check the composition of the component processes. Since explicit composition leads to state explosion, verifying the system without actually composing the components is attractive, even for possibly restrictive class of systems. We show that the problem of compositional CTL model checking is PSPACE complete for the class of systems composed of components that are tree-like transition structure and do not interact among themselves. For the simplest forms of existential and universal CTL formulas model checking turns out to be NP complete and coNP complete, respectively. The results hold for both synchronous and asynchronous composition. AU - Krishnendu Chatterjee AU - Dasgupta, Pallab AU - Chakrabarti, Partha P ID - 3896 TI - Complexity of compositional model checking of computation tree logic on simple structures VL - 3326 ER -