TY - JOUR AB - Cadherins are transmembrane proteins that mediate cell–cell adhesion in animals. By regulating contact formation and stability, cadherins play a crucial role in tissue morphogenesis and homeostasis. Here, we review the three major unctions of cadherins in cell–cell contact formation and stability. Two of those functions lead to a decrease in interfacial ension at the forming cell–cell contact, thereby promoting contact expansion — first, by providing adhesion tension that lowers interfacial tension at the cell–cell contact, and second, by signaling to the actomyosin cytoskeleton in order to reduce cortex tension and thus interfacial tension at the contact. The third function of cadherins in cell–cell contact formation is to stabilize the contact by resisting mechanical forces that pull on the contact. AU - Maître, Jean-Léon AU - Heisenberg, Carl-Philipp J ID - 2469 IS - 14 JF - Current Biology TI - Three functions of cadherins in cell adhesion VL - 23 ER - TY - JOUR AB - An improved estimate is provided for the number of Fq-rational points on a geometrically irreducible, projective, cubic hypersurface that is not equal to a cone. AU - Timothy Browning ID - 247 IS - 3 JF - Canadian Mathematical Bulletin TI - The Lang-Weil estimate for cubic hypersurfaces VL - 56 ER - TY - JOUR AB - When a mutation with selective advantage s spreads through a panmictic population, it may cause two lineages at a linked locus to coalesce; the probability of coalescence is exp(−2rT), where T∼log(2Ns)/s is the time to fixation, N is the number of haploid individuals, and r is the recombination rate. Population structure delays fixation, and so weakens the effect of a selective sweep. However, favourable alleles spread through a spatially continuous population behind a narrow wavefront; ancestral lineages are confined at the tip of this front, and so coalesce rapidly. In extremely dense populations, coalescence is dominated by rare fluctuations ahead of the front. However, we show that for moderate densities, a simple quasi-deterministic approximation applies: the rate of coalescence within the front is λ∼2g(η)/(ρℓ), where ρ is the population density and is the characteristic scale of the wavefront; g(η) depends only on the strength of random drift, . The net effect of a sweep on coalescence also depends crucially on whether two lineages are ever both within the wavefront at the same time: even in the extreme case when coalescence within the front is instantaneous, the net rate of coalescence may be lower than in a single panmictic population. Sweeps can also have a substantial impact on the rate of gene flow. A single lineage will jump to a new location when it is hit by a sweep, with mean square displacement ; this can be substantial if the species’ range, L, is large, even if the species-wide rate of sweeps per map length, Λ/R, is small. This effect is half as strong in two dimensions. In contrast, the rate of coalescence between lineages, at random locations in space and on the genetic map, is proportional to (c/L)(Λ/R), where c is the wavespeed: thus, on average, one-dimensional structure is likely to reduce coalescence due to sweeps, relative to panmixis. In two dimensions, genes must move along the front before they can coalesce; this process is rapid, being dominated by rare fluctuations. This leads to a dramatically higher rate of coalescence within the wavefront than if lineages simply diffused along the front. Nevertheless, the net rate of coalescence due to a sweep through a two-dimensional population is likely to be lower than it would be with panmixis. AU - Barton, Nicholas H AU - Etheridge, Alison AU - Kelleher, Jerome AU - Véber, Amandine ID - 2473 IS - 8 JF - Theoretical Population Biology TI - Genetic hitch-hiking in spatially extended populations VL - 87 ER - TY - JOUR AB - Despite the pivotal functions of the NMDA receptor (NMDAR) for neural circuit development and synaptic plasticity, the molecular mechanisms underlying the dynamics of NMDAR trafficking are poorly understood. The cell adhesion molecule neuroligin-1 (NL1) modifies NMDAR-dependent synaptic transmission and synaptic plasticity, but it is unclear whether NL1 controls synaptic accumulation or function of the receptors. Here, we provide evidence that NL1 regulates the abundance of NMDARs at postsynaptic sites. This function relies on extracellular, NL1 isoform-specific sequences that facilitate biochemical interactions between NL1 and the NMDAR GluN1 subunit. Our work uncovers NL1 isoform-specific cisinteractions with ionotropic glutamate receptors as a key mechanism for controlling synaptic properties. AU - Budreck, Elaine C AU - Kwon, Oh-Bin AU - Jung, Jung-Hoon AU - Baudouin, Stéphane J AU - Thommen, Albert AU - Kim, Hye-Sun AU - Fukazawa, Yugo AU - Harumi Harada AU - Tabuchi, Katsuhiko AU - Ryuichi Shigemoto AU - Scheiffele, Peter AU - Kim, Joung-Hun ID - 2478 IS - 2 JF - PNAS TI - Neuroligin-1 controls synaptic abundance of NMDA-type glutamate receptors through extracellular coupling VL - 110 ER - TY - JOUR AB - Châtelet surfaces provide a rich source of geometrically rational surfaces that do not always satisfy the Hasse principle. Restricting attention to a special class of Châtelet surfaces, we investigate the frequency that such counter-examples arise over the rational numbers. AU - de la Bretèche, Régis AU - Timothy Browning ID - 250 IS - 4 JF - Proceedings of the London Mathematical Society TI - Density of Châtelet surfaces failing the Hasse principle VL - 108 ER - TY - JOUR AB - We study the density of varieties in a certain family which do not satisfy the Hasse principle. This work relies on results recently obtained by Colliot-Thélène [3]. AU - de la Bretèche, Régis AU - Timothy Browning ID - 251 IS - 1 JF - Journal de Theorie des Nombres de Bordeaux TI - Counter examples to the Hasse principle among certain coflasque tori VL - 26 ER - TY - CONF AB - Traditional formal methods are based on a Boolean satisfaction notion: a reactive system satisfies, or not, a given specification. We generalize formal methods to also address the quality of systems. As an adequate specification formalism we introduce the linear temporal logic LTL[F]. The satisfaction value of an LTL[F] formula is a number between 0 and 1, describing the quality of the satisfaction. The logic generalizes traditional LTL by augmenting it with a (parameterized) set F of arbitrary functions over the interval [0,1]. For example, F may contain the maximum or minimum between the satisfaction values of subformulas, their product, and their average. The classical decision problems in formal methods, such as satisfiability, model checking, and synthesis, are generalized to search and optimization problems in the quantitative setting. For example, model checking asks for the quality in which a specification is satisfied, and synthesis returns a system satisfying the specification with the highest quality. Reasoning about quality gives rise to other natural questions, like the distance between specifications. We formalize these basic questions and study them for LTL[F]. By extending the automata-theoretic approach for LTL to a setting that takes quality into an account, we are able to solve the above problems and show that reasoning about LTL[F] has roughly the same complexity as reasoning about traditional LTL. AU - Almagor, Shaull AU - Boker, Udi AU - Kupferman, Orna ID - 2517 IS - Part 2 TI - Formalizing and reasoning about quality VL - 7966 ER - TY - CONF AB - A class of valued constraint satisfaction problems (VCSPs) is characterised by a valued constraint language, a fixed set of cost functions on a finite domain. An instance of the problem is specified by a sum of cost functions from the language with the goal to minimise the sum. We study which classes of finite-valued languages can be solved exactly by the basic linear programming relaxation (BLP). Thapper and Živný showed [20] that if BLP solves the language then the language admits a binary commutative fractional polymorphism. We prove that the converse is also true. This leads to a necessary and a sufficient condition which can be checked in polynomial time for a given language. In contrast, the previous necessary and sufficient condition due to [20] involved infinitely many inequalities. More recently, Thapper and Živný [21] showed (using, in particular, a technique introduced in this paper) that core languages that do not satisfy our condition are NP-hard. Taken together, these results imply that a finite-valued language can either be solved using Linear Programming or is NP-hard. AU - Kolmogorov, Vladimir ID - 2518 IS - 1 TI - The power of linear programming for finite-valued CSPs: A constructive characterization VL - 7965 ER - TY - JOUR AB - We study the problem of object recognition for categories for which we have no training examples, a task also called zero-data or zero-shot learning. This situation has hardly been studied in computer vision research, even though it occurs frequently: the world contains tens of thousands of different object classes and for only few of them image collections have been formed and suitably annotated. To tackle the problem we introduce attribute-based classification: objects are identified based on a high-level description that is phrased in terms of semantic attributes, such as the object's color or shape. Because the identification of each such property transcends the specific learning task at hand, the attribute classifiers can be pre-learned independently, e.g. from existing image datasets unrelated to the current task. Afterwards, new classes can be detected based on their attribute representation, without the need for a new training phase. In this paper we also introduce a new dataset, Animals with Attributes, of over 30,000 images of 50 animal classes, annotated with 85 semantic attributes. Extensive experiments on this and two more datasets show that attribute-based classification indeed is able to categorize images without access to any training images of the target classes. AU - Lampert, Christoph AU - Nickisch, Hannes AU - Harmeling, Stefan ID - 2516 IS - 3 JF - IEEE Transactions on Pattern Analysis and Machine Intelligence TI - Attribute-based classification for zero-shot learning of object categories VL - 36 ER - TY - CONF AB - We propose a probabilistic model to infer supervised latent variables in the Hamming space from observed data. Our model allows simultaneous inference of the number of binary latent variables, and their values. The latent variables preserve neighbourhood structure of the data in a sense that objects in the same semantic concept have similar latent values, and objects in different concepts have dissimilar latent values. We formulate the supervised infinite latent variable problem based on an intuitive principle of pulling objects together if they are of the same type, and pushing them apart if they are not. We then combine this principle with a flexible Indian Buffet Process prior on the latent variables. We show that the inferred supervised latent variables can be directly used to perform a nearest neighbour search for the purpose of retrieval. We introduce a new application of dynamically extending hash codes, and show how to effectively couple the structure of the hash codes with continuously growing structure of the neighbourhood preserving infinite latent feature space. AU - Quadrianto, Novi AU - Sharmanska, Viktoriia AU - Knowles, David AU - Ghahramani, Zoubin ID - 2520 SN - 9780974903996 T2 - Proceedings of the 29th conference uncertainty in Artificial Intelligence TI - The supervised IBP: Neighbourhood preserving infinite latent feature models ER -