TY - JOUR
AB - Social and solitary feeding in natural Caenorhabditis elegans isolates are associated with two alleles of the orphan G-protein-coupled receptor (GPCR) NPR-1: social feeders contain NPR-1 215F, whereas solitary feeders contain NPR-1 215V. Here we identify FMRFamide-related neuropeptides (FaRPs) encoded by the flp-18 and flp-21 genes as NPR-1 ligands and show that these peptides can differentially activate the NPR-1 215F and NPR-1 215V receptors. Multicopy overexpression of flp-21 transformed wild social animals into solitary feeders. Conversely, a flp-21 deletion partially phenocopied the npr-1(null) phenotype, which is consistent with NPR-1 activation by FLP-21 in vivo but also implicates other ligands for NPR-1. Phylogenetic studies indicate that the dominant npr-1 215V allele likely arose from an ancestral npr-1 215F gene in C. elegans. Our data suggest a model in which solitary feeding evolved in an ancestral social strain of C. elegans by a gain-of-function mutation that modified the response of NPR-1 to FLP-18 and FLP-21 ligands.
AU - Rogers, Candida
AU - Reale, Vincenzina
AU - Kim, Kyuhyung
AU - Chatwin, Heather
AU - Li, Chris
AU - Evans, Peter
AU - de Bono, Mario
ID - 6156
IS - 11
JF - Nature Neuroscience
SN - 1097-6256
TI - Inhibition of Caenorhabditis elegans social feeding by FMRFamide-related peptide activation of NPR-1
VL - 6
ER -
TY - JOUR
AB - In many animal species individuals aggregate to live in groups. A range of experimental approaches in different animals, including studies of social feeding in nematodes, maternal behavior in rats and sheep, and pair-bonding in voles, are providing insights into the neural bases for these behaviors. These studies are delineating multiple neural circuits and gene networks in the brain that interact in ways that are as yet poorly understood to coordinate social behavior.
AU - de Bono, Mario
ID - 6157
IS - 1
JF - Journal of Neurobiology
SN - 0022-3034
TI - Molecular approaches to aggregation behavior and social attachment
VL - 54
ER -
TY - JOUR
AB - Among the major mathematical approaches to mirror symmetry are those of Batyrev-Borisov and Stromdnger-Yau-Zaslow (SYZ). The first is explicit and amenable to computation but is not clearly related to the physical motivation; the second is the opposite. Furthermore, it is far from obvious that mirror partners in one sense will also be mirror partners in the other. This paper concerns a class of examples that can be shown to satisfy the requirements of SYZ, but whose Hodge numbers are also equal. This provides significant evidence in support of SYZ. Moreover, the examples are of great interest in their own right: they are spaces of flat SLr-connections on a smooth curve. The mirror is the corresponding space for the Langlands dual group PGLr. These examples therefore throw a bridge from mirror symmetry to the duality theory of Lie groups and, more broadly, to the geometric Langlands program.
AU - Tamas Hausel
AU - Thaddeus, Michael
ID - 1457
IS - 1
JF - Inventiones Mathematicae
TI - Mirror symmetry, langlands duality, and the Hitchin system
VL - 153
ER -
TY - JOUR
AB - The moduli space of stable bundles of rank $2$ and degree $1$ on a Riemann surface has rational cohomology generated by the so-called universal classes. The work of Baranovsky, King-Newstead, Siebert-Tian and Zagier provided a complete set of relations between these classes, expressed in terms of a recursion in the genus. This paper accomplishes the same thing for the noncompact moduli spaces of Higgs bundles, in the sense of Hitchin and Simpson. There are many more independent relations than for stable bundles, but in a sense the answer is simpler, since the formulas are completely explicit, not recursive. The results of Kirwan on equivariant cohomology for holomorphic circle actions are of key importance.
AU - Tamas Hausel
AU - Thaddeus, Michael
ID - 1458
IS - 2
JF - Journal of the American Mathematical Society
TI - Relations in the cohomology ring of the moduli space of rank 2 Higgs bundles
VL - 16
ER -
TY - JOUR
AB - In this paper we explicitly calculate the analogue of the 't Hooft SU (2) Yang-Mills instantons on Gibbons-Hawking multi-centered gravitational instantons, which come in two parallel families: the multi-Eguchi-Hanson, or Ak ALE gravitational instantons and the multi-Taub-NUT spaces, or Ak ALF gravitational instantons. We calculate their energy and find the reducible ones. Following Kronheimer we also exploit the U(1) invariance of our solutions and study the corresponding explicit singular SU (2) magnetic monopole solutions of the Bogomolny equations on flat ℝ3.
AU - Etesi, Gábor
AU - Tamas Hausel
ID - 1459
IS - 2
JF - Communications in Mathematical Physics
TI - On Yang-Mills instantons over multi-centered gravitational instantons
VL - 235
ER -
TY - JOUR
AB - For any number field k, upper bounds are established for the number of k-rational points of bounded height on non-singular del Pezzo surfaces defined over k, which are equipped with suitable conic bundle structures over k.
AU - Browning, Timothy D
AU - Swarbick Jones, M
ID - 166
JF - Proceedings of the Bonn session in analytic number theory and diophantine equations
TI - Counting rational points on del Pezzo surfaces of degree 5
VL - 360
ER -
TY - JOUR
AB - The combination of high-resolution atomic force microscopy (AFM) imaging and single-molecule force-spectroscopy was employed to unfold single bacteriorhodopsins (BR) from native purple membrane patches at various physiologically relevant temperatures. The unfolding spectra reveal detailed insight into the stability of individual structural elements of BR against mechanical unfolding. Intermittent states in the unfolding process are associated with the stepwise unfolding of alpha-helices, whereas other states are associated with the unfolding of polypeptide loops connecting the alpha-helices. It was found that the unfolding forces of the secondary structures considerably decreased upon increasing the temperature from 8 to 52°C. Associated with this effect, the probability of individual unfolding pathways of BR was significantly influenced by the temperature. At lower temperatures, transmembrane alpha-helices and extracellular polypeptide loops exhibited sufficient stability to individually establish potential barriers against unfolding, whereas they predominantly unfolded collectively at elevated temperatures. This suggests that increasing the temperature decreases the mechanical stability of secondary structural elements and changes molecular interactions between secondary structures, thereby forcing them to act as grouped structures.
AU - Harald Janovjak
AU - Kessler, Max
AU - Oesterhelt, Dieter
AU - Gaub, Hermann
AU - Mueller, Daniel J
ID - 3725
IS - 19
JF - EMBO Journal
TI - Unfolding pathways of native bacteriorhodopsin depend on temperature
VL - 22
ER -
TY - JOUR
AB - We use the lac operon in Escherichia coli as a prototype system to illustrate the current state, applicability, and limitations of modeling the dynamics of cellular networks. We integrate three different levels of description (molecular, cellular, and that of cell population) into a single model, which seems to capture many experimental aspects of the system.
AU - Vilar,Jose M
AU - Calin Guet
AU - Leibler, Stanislas
ID - 3752
IS - 3
JF - Journal of Cell Biology
TI - Modeling network dynamics: the lac operon, a case study
VL - 161
ER -
TY - JOUR
AU - Bauer, Wolfgang
AU - Kleine Berkenbusch, Marco
AU - Bollenbach, Mark Tobias
ID - 3797
IS - 4
JF - Revista Mexicana De Fisica
TI - Breaking atomic nuclei into little pieces: evidence for a phase transition
VL - 49
ER -
TY - JOUR
AB - Kv3 channels are thought to be essential for the fast-spiking (FS) phenotype in GABAergic interneurons, but how these channels confer the ability to generate action potentials (APs) at high frequency is unknown. To address this question, we developed a fast dynamic-clamp system (approximately 50 kHz) that allowed us to add a Kv3 model conductance to CA1 oriens alveus (OA) interneurons in hippocampal slices. Selective pharmacological block of Kv3 channels by 0.3 mm 4-aminopyridine or 1 mm tetraethylammonium ions led to a marked broadening of APs during trains of short stimuli and a reduction in AP frequency during 1 sec stimuli. The addition of artificial Kv3 conductance restored the original AP pattern. Subtraction of Kv3 conductance by dynamic clamp mimicked the effects of the blockers. Application of artificial Kv3 conductance also led to FS in OA interneurons after complete K+ channel block and even induced FS in hippocampal pyramidal neurons in the absence of blockers. Adding artificial Kv3 conductance with altered deactivation kinetics revealed a nonmonotonic relationship between mean AP frequency and deactivation rate, with a maximum slightly above the original value. Insertion of artificial Kv3 conductance with either lowered activation threshold or inactivation also led to a reduction in the mean AP frequency. However, the mechanisms were distinct. Shifting the activation threshold induced adaptation, whereas adding inactivation caused frequency-dependent AP broadening. In conclusion, Kv3 channels are necessary for the FS phenotype of OA interneurons, and several of their gating properties appear to be optimized for high-frequency repetitive activity.
AU - Lien, Cheng-Chang
AU - Peter Jonas
ID - 3804
IS - 6
JF - Journal of Neuroscience
TI - Kv3 potassium conductance is necessary and kinetically optimized for high-frequency action potential generation in hippocampal interneurons
VL - 23
ER -
TY - JOUR
AB - To probe exocytosis at a cortical glutamatergic synapse, we made capacitance measurements in whole-cell recorded hippocampal mossy fiber terminals. Evaluation of different methods by using a morphology-based equivalent electrical model revealed that quantitative capacitance measurements are possible in this presynaptic structure. Voltage pulses leading to presynaptic Ca2+ inflow evoked large capacitance signals that showed saturation with increasing pulse duration. The mean peak capacitance increase was 100 fF, corresponding to a pool of approximately 1,400 releasable vesicles. Thus hippocampal mossy fiber synapses have a vesicular "maxipool." Large pool size and rapid vesicle recycling may underlie the uniquely large extent of activity-dependent plasticity in this synapse.
AU - Hallermann, Stefan
AU - Pawlu, Christian
AU - Peter Jonas
AU - Heckmann, Manfred
ID - 3806
IS - 15
JF - PNAS
TI - A large pool of releasable vesicles in a cortical glutamatergic synapse
VL - 100
ER -
TY - CONF
AB - Many verification, planning, and control problems can be modeled as games played on state-transition graphs by one or two players whose conflicting goals are to form a path in the graph. The focus here is on simple stochastic parity games, that is, two-player games with turn-based probabilistic transitions and omega-regular objectives formalized as parity (Rabin chain) winning conditions. An efficient translation from simple stochastic parity games to nonstochastic parity games is given. As many algorithms are known for solving the latter, the translation yields efficient algorithms for computing the states of a simple stochastic parity game from which a player can win with probability 1. An important special case of simple stochastic parity games are the Markov decision processes with Buchi objectives. For this special case a first provably subquadratic algorithm is given for computing the states from which the single player has a strategy to achieve a Buchi objective with probability 1. For game graphs with m edges the algorithm works in time O(mrootm). Interestingly, a similar technique sheds light on the question of the computational complexity of solving simple Buchi games and yields the first provably subquadratic algorithm, with a running time of O(n(2)/log n) for game graphs with n vertices and O(n) edges.
AU - Krishnendu Chatterjee
AU - Jurdziński, Marcin
AU - Thomas Henzinger
ID - 3897
TI - Simple stochastic parity games
VL - 2803
ER -
TY - CONF
AB - We study the problem of determining stack boundedness and the exact maximum stack size for three classes of interrupt-driven programs. Interrupt-driven programs axe used in many real-time applications that require responsive interrupt handling. In order to ensure responsiveness, programmers often enable interrupt processing in the body of lower-priority interrupt handlers. In such programs a programming error can allow interrupt handlers to be interrupted in cyclic fashion to lead to an unbounded stack, causing the system to crash. For a restricted class of interrupt-driven programs, we show that there is a polynomial-time procedure to check stack boundedness, while determining the exact maximum stack size is PSPACE-complete. For a larger class of programs, the two problems are both PSPACE-complete, and for the largest class of programs we consider, the two problems are PSPACE-hard and can be solved in exponential time.
AU - Krishnendu Chatterjee
AU - Ma, Di
AU - Majumdar, Ritankar S
AU - Zhao, Tian
AU - Thomas Henzinger
AU - Palsberg, Jens
ID - 3898
TI - Stack size analysis for interrupt-driven programs
VL - 2694
ER -
TY - JOUR
AB - Male dimorphism is not genetically determined, but is induced by environmental conditions particularly decreasing temperature and density.
AU - Cremer, Sylvia
AU - Heinze, Jürgen
ID - 3917
IS - 15
JF - Blick in die Wissenschaft
TI - Zwischen Hochzeitsflug und Brudermord: reproduktive Taktiken bei Ameisenmännchen
VL - 12
ER -
TY - JOUR
AB - Unlike most social insects, many Cardiocondyla ant species have two male morphs: wingless (ergatoid) males, who remain in the natal nest, and winged males who disperse but, strangely, before leaving may also mate within the nest. Whereas ergatoid males are highly intolerant of each other and fight among themselves, they tend to tolerate their winged counterparts. This is despite the fact that these winged males, like ergatoid males, represent mating competition. Why should ergatoid males tolerate their winged rivals? We developed a mathematical model to address this question. Our model focuses on a number of factors likely toinfluence whether ergatoid males are tolerant of winged males: ergatoid male–winged male relatedness, number of virgin queens, number of winged males, and the number of ejaculates a winged male has (winged males are sperm limited, whereas ergatoid males have lifelong spermatogenesis). Surprisingly, we found that increasing the number of virgin queens favors a kill strategy, whereas an increase in the other factors favors a let-live strategy; these predictions appear true for C. obscurior and for a number of other Cardiocondyla species. Two further aspects, unequal insemination success and multiple mating in queens, were also incorporated into the model and predictions made about their effects on toleration of winged males. The model is applicable more generally in species that have dimorphic males, such as some other ants, bees, and fig wasps.
AU - Anderson, Carl
AU - Cremer, Sylvia
AU - Heinze, Jürgen
ID - 3921
IS - 1
JF - Behavioral Ecology
TI - Live and let die: Why fighter males of the ant Cardiocondyla kill each other but tolerate their winged rivals
VL - 14
ER -
TY - JOUR
AB - Dispersal is advantageous, but, at the same time, it implies high costs and risks. Due to these counteracting selection pressures, many species evolved dispersal polymorphisms, which, in ants, are typically restricted to the female sex (queens). Male polymorphism is presently only known from a few genera, such as Cardiocondyla, in which winged dispersing males coexist with wingless fighter males that mate exclusively inside their maternal nests. We studied the developmental mechanisms underlying these alternative male morphs and found that, first, male dimorphism is not genetically determined, but is induced by environmental conditions (decreasing temperature and density). Second, male morph is not yet fixed at the egg stage, but it differentiates during larval development. This flexible developmental pattern of male morphs allows Cardiocondyla ant colonies to react quickly to changes in their environment. Under good conditions, they invest exclusively in philopatric wingless males. But, when environmental conditions turn bad, colonies start to produce winged dispersal males, even though these males require a many times higher investment by the colony than their much smaller wingless counterparts. Cardiocondyla ants share this potential of optimal resource allocation with other colonial animals and some seed dimorphic plants.
AU - Cremer, Sylvia
AU - Heinze, Jürgen
ID - 3922
IS - 3
JF - Current Biology
TI - Stress grows wings: Environmental induction of winged dispersal males in Cardiocondyla ants
VL - 13
ER -
TY - CHAP
AB - We give analytic inclusion-exclusion formulas for the area and perimeter derivatives of a union of finitely many disks in the plane.
AU - Cheng, Ho-Lun
AU - Herbert Edelsbrunner
ID - 3991
T2 - Computer Science in Perspective: Essays Dedicated to Thomas Ottmann
TI - Area and perimeter derivatives of a union of disks
VL - 2598
ER -
TY - JOUR
AB - Computing the volume occupied by individual atoms in macromolecular structures has been the subject of research for several decades. This interest has grown in the recent years, because weighted volumes are widely used in implicit solvent models. Applications of the latter in molecular mechanics simulations require that the derivatives of these weighted volumes be known. In this article, we give a formula for the volume derivative of a molecule modeled as a space-filling diagram made up of balls in motion. The formula is given in terms of the weights, radii, and distances between the centers as well as the sizes of the facets of the power diagram restricted to the space-filling diagram. Special attention is given to the detection and treatment of singularities as well as discontinuities of the derivative.
AU - Herbert Edelsbrunner
AU - Koehl, Patrice
ID - 3992
IS - 5
JF - PNAS
TI - The weighted-volume derivative of a space-filling diagram
VL - 100
ER -
TY - JOUR
AB - We present algorithms for constructing a hierarchy of increasingly coarse Morse-Smale complexes that decompose a piecewise linear 2-manifold. While these complexes are defined only in the smooth category, we extend the construction to the piecewise linearcategory by ensuring structural integrity and simulating differentiability. We then simplify Morse-Smale complexes by canceling pairs of critical points in order of increasing persistence.
AU - Herbert Edelsbrunner
AU - Harer, John
AU - Zomorodian, Afra
ID - 3993
IS - 1
JF - Discrete & Computational Geometry
TI - Hierarchical Morse-Smale complexes for piecewise linear 2-manifolds
VL - 30
ER -
TY - JOUR
AB - The body defined by a finite collection of disks is a subset of the plane bounded by a tangent continuous curve, which we call the skin. We give analytic formulas for the area, the perimeter, the area derivative, and the perimeter derivative of the body. Given the filtrations of the Delaunay triangulation and the Voronoi diagram of the disks, all formulas can be evaluated in time proportional to the number of disks.
AU - Cheng, Ho-Lun
AU - Herbert Edelsbrunner
ID - 3994
IS - 2
JF - Computational Geometry: Theory and Applications
TI - Area, perimeter and derivatives of a skin curve
VL - 26
ER -