@article{2742,
abstract = {We consider a system of N weakly interacting fermions with a real analytic pair interaction. We prove that for a general class of initial data there exists a fixed time T such that the difference between the one particle density matrix of this system and the solution of the nonlinear Hartree equation is of order N−1 for any time t⩽T.},
author = {Elgart, Alexander and László Erdös and Schlein, Benjamin and Yau, Horng-Tzer},
journal = {Journal de Mathématiques Pures et Appliquées},
number = {10},
pages = {1241 -- 1273},
publisher = {Elsevier},
title = {{Nonlinear Hartree equation as the mean field limit of weakly coupled fermions}},
doi = {10.1016/j.matpur.2004.03.006},
volume = {83},
year = {2004},
}
@article{2425,
abstract = {A finite set N ⊂ Rd is a weak ε-net for an n-point set X ⊂ Rd (with respect to convex sets) if N intersects every convex set K with |K ∩ X| ≥ εn. We give an alternative, and arguably simpler, proof of the fact, first shown by Chazelle et al., that every point set X in Rd admits a weak ε-net of cardinality O(ε-dpolylog(1/ε)). Moreover, for a number of special point sets (e.g., for points on the moment curve), our method gives substantially better bounds. The construction yields an algorithm to construct such weak ε-nets in time O(n ln(1/ε)).},
author = {Matoušek, Jiří and Uli Wagner},
journal = {Discrete & Computational Geometry},
number = {2},
pages = {195 -- 206},
publisher = {Springer},
title = {{New constructions of weak ε-nets}},
doi = {10.1007/s00454-004-1116-4},
volume = {32},
year = {2004},
}
@article{2999,
abstract = {Embryogenesis of flowering plants establishes a basic body plan with apical-basal, radial and bilateral patterns from the single-celled zygote. Arabidopsis embryogenesis exhibits a nearly invariant cell division pattern and therefore is an ideal system for studies of early plant development. However, plant embryos are difficult to access for experimental manipulation, as they develop deeply inside maternal tissues. Here we present a method for the culture of zygotic Arabidopsis embryos in vitro. The technique omits excision of the embryo by culturing the entire ovule, thus greatly facilitating the time and effort involved. It enables external manipulation of embryo development and culture from the earliest developmental stages up to maturity. Administration of various chemical treatments as well as the use of different molecular markers is demonstrated together with standard techniques for visualizing gene expression and protein localization in in vitro cultivated embryos. The presented set of techniques allows for so far unavailable molecular physiology approaches in the study of early plant development.},
author = {Sauer, Michael and Jirí Friml},
journal = {Plant Journal},
number = {5},
pages = {835 -- 843},
publisher = {Wiley-Blackwell},
title = {{In vitro culture of Arabidopsis embryos within their ovules}},
doi = {10.1111/j.1365-313X.2004.02248.x},
volume = {40},
year = {2004},
}
@inbook{3574,
author = {Herbert Edelsbrunner},
booktitle = {Handbook of Discrete and Computational Geometry},
pages = {1395 -- 1412},
publisher = {CRC Press},
title = {{Biological applications of computational topology}},
year = {2004},
}
@article{3810,
abstract = {Voltage-gated potassium (Kv) channels control action potential repolarization, interspike membrane potential, and action potential frequency in excitable cells. It is thought that the combinatorial association between distinct alpha and beta subunits determines whether Kv channels function as non-inactivating delayed rectifiers or as rapidly inactivating A-type channels. We show that membrane lipids can convert A-type channels into delayed rectifiers and vice versa. Phosphoinositides remove N-type inactivation from A-type channels by immobilizing the inactivation domains. Conversely, arachidonic acid and its amide anandamide endow delayed rectifiers with rapid voltage-dependent inactivation. The bidirectional control of Kv channel gating by lipids may provide a mechanism for the dynamic regulation of electrical signaling in the nervous system.},
author = {Oliver, Dominik and Lien, Cheng-Chang and Soom, Malle and Baukrowitz, Thomas and Peter Jonas and Fakler, Bernd},
journal = {Science},
number = {5668},
pages = {265 -- 70},
publisher = {American Association for the Advancement of Science},
title = {{Functional conversion between A-type and delayed rectifier K+ channels by membrane lipids}},
doi = {10.1126/science.1094113},
volume = {304},
year = {2004},
}
@article{3985,
abstract = {Given a Morse function f over a 2-manifold with or without boundary, the Reeb graph is obtained by contracting the connected components of the level sets to points. We prove tight upper and lower bounds on the number of loops in the Reeb graph that depend on the genus, the number of boundary components, and whether or not the 2-manifold is orientable. We also give an algorithm that constructs the Reeb graph in time O(n log n), where n is the number of edges in the triangulation used to represent the 2-manifold and the Morse function.},
author = {Cole-McLaughlin, Kree and Herbert Edelsbrunner and Harer, John and Natarajan, Vijay and Pascucci, Valerio},
journal = {Discrete & Computational Geometry},
number = {2},
pages = {231 -- 244},
publisher = {Springer},
title = {{Loops in Reeb graphs of 2-manifolds}},
doi = {10.1007/s00454-004-1122-6},
volume = {32},
year = {2004},
}
@article{4224,
abstract = {Developing cells acquire positional information by reading the graded distribution of morphogens. In Drosophila, the Dpp morphogen forms a long-range concentration gradient by spreading from a restricted source in the developing wing. It has been assumed that Dpp spreads by extracellular diffusion. Under this assumption, the main role of endocytosis in gradient formation is to downregulate receptors at the cell surface. These surface receptors bind to the ligand and thereby interfere with its long-range movement. Recent experiments indicate that Dpp spreading is mediated by Dynamin-dependent endocytosis in the target tissue, suggesting that extracellular diffusion alone cannot account for Dpp dispersal. Here, we perform a theoretical study of a model for morphogen spreading based on extracellular diffusion, which takes into account receptor binding and trafficking. We compare profiles of ligand and surface receptors obtained in this model with experimental data. To this end, we monitored directly the pool of surface receptors and extracellular Dpp with specific antibodies. We conclude that current models considering pure extracellular diffusion cannot explain the observed role of endocytosis during Dpp long-range movement.},
author = {Kruse, Karsten and Pantazis, Periklis and Bollenbach, Tobias and Julicher, Frank and Gonzalez-Gaitan, Marcos},
journal = {Development},
number = {19},
pages = {4843 -- 4856},
publisher = {Company of Biologists},
title = {{Dpp gradient formation by dynamin-dependent endocytosis: receptor trafficking and the diffusion model}},
doi = {10.1242/dev.01335},
volume = {131},
year = {2004},
}
@phdthesis{4236,
author = {de Vladar,Harold Paul},
publisher = {Centro de estudios avazados, IVIC},
title = {{Métodos no lineales y sus aplicaciones en dinámicas aleatorias de poblaciones celulares}},
doi = {3810},
year = {2004},
}
@inproceedings{4445,
abstract = {We present a type system for E code, which is an assembly language that manages the release, interaction, and termination of real-time tasks. E code specifies a deadline for each task, and the type system ensures that the deadlines are path-insensitive. We show that typed E programs allow, for given worst-case execution times of tasks, a simple schedulability analysis. Moreover, the real-time programming language Giotto can be compiled into typed E~code. This shows that typed E~code identifies an easily schedulable yet expressive class of real-time programs. We have extended the Giotto compiler to generate typed E code, and enabled the run-time system for E code to perform a type and schedulability check before executing the code.},
author = {Thomas Henzinger and Kirsch, Christoph M},
pages = {104 -- 113},
publisher = {ACM},
title = {{A typed assembly language for real-time programs}},
doi = {10.1145/1017753.1017774},
year = {2004},
}
@inproceedings{4558,
abstract = {We study perfect-information stochastic parity games. These are two-player nonterminating games which are played on a graph with turn-based probabilistic transitions. A play results in an infinite path and the conflicting goals of the two players are ω-regular path properties, formalized as parity winning conditions. The qualitative solution of such a game amounts to computing the set of vertices from which a player has a strategy to win with probability 1 (or with positive probability). The quantitative solution amounts to computing the value of the game in every vertex, i.e., the highest probability with which a player can guarantee satisfaction of his own objective in a play that starts from the vertex.For the important special case of one-player stochastic parity games (parity Markov decision processes) we give polynomial-time algorithms both for the qualitative and the quantitative solution. The running time of the qualitative solution is O(d · m3/2) for graphs with m edges and d priorities. The quantitative solution is based on a linear-programming formulation.For the two-player case, we establish the existence of optimal pure memoryless strategies. This has several important ramifications. First, it implies that the values of the games are rational. This is in contrast to the concurrent stochastic parity games of de Alfaro et al.; there, values are in general algebraic numbers, optimal strategies do not exist, and ε-optimal strategies have to be mixed and with infinite memory. Second, the existence of optimal pure memoryless strategies together with the polynomial-time solution forone-player case implies that the quantitative two-player stochastic parity game problem is in NP ∩ co-NP. This generalizes a result of Condon for stochastic games with reachability objectives. It also constitutes an exponential improvement over the best previous algorithm, which is based on a doubly exponential procedure of de Alfaro and Majumdar for concurrent stochastic parity games and provides only ε-approximations of the values.},
author = {Krishnendu Chatterjee and Jurdziński, Marcin and Thomas Henzinger},
pages = {121 -- 130},
publisher = {SIAM},
title = {{Quantitative stochastic parity games}},
year = {2004},
}
@inproceedings{4577,
abstract = {While model checking has been successful in uncovering subtle bugs in code, its adoption in software engineering practice has been hampered by the absence of a simple interface to the programmer in an integrated development environment. We describe an integration of the software model checker BLAST into the Eclipse development environment. We provide a verification interface for practical solutions for some typical program analysis problems - assertion checking, reachability analysis, dead code analysis, and test generation - directly on the source code. The analysis is completely automatic, and assumes no knowledge of model checking or formal notation. Moreover, the interface supports incremental program verification to support incremental design and evolution of code.},
author = {Beyer, Dirk and Thomas Henzinger and Jhala, Ranjit and Majumdar, Ritankar S},
pages = {251 -- 255},
publisher = {IEEE},
title = {{An eclipse plug-in for model checking}},
doi = {10.1109/WPC.2004.1311069 },
year = {2004},
}
@article{6155,
abstract = {The genome of the nematode Caenorhabditis elegans encodes seven soluble guanylate cyclases (sGCs) [1]. In mammals, sGCs function as α/β heterodimers activated by gaseous ligands binding to a haem prosthetic group 2, 3. The principal activator is nitric oxide, which acts through sGCs to regulate diverse cellular events. In C. elegans the function of sGCs is mysterious: the worm genome does not appear to encode nitric oxide synthase, and all C. elegans sGC subunits are more closely related to mammalian β than α subunits [1]. Here, we show that two of the seven C. elegans sGCs, GCY-35 and GCY-36, promote aggregation behavior. gcy-35 and gcy-36 are expressed in a small number of neurons. These include the body cavity neurons AQR, PQR, and URX, which are directly exposed to the blood equivalent of C. elegans and regulate aggregation behavior [4]. We show that GCY-35 and GCY-36 act as α-like and β-like sGC subunits and that their function in the URX sensory neurons is sufficient for strong nematode aggregation. Neither GCY-35 nor GCY-36 is absolutely required for C. elegans to aggregate. Instead, these molecules may transduce one of several pathways that induce C. elegans to aggregate or may modulate aggregation by responding to cues in C. elegans body fluid.},
author = {Cheung, Benny H.H and Arellano-Carbajal, Fausto and Rybicki, Irene and de Bono, Mario},
issn = {0960-9822},
journal = {Current Biology},
number = {12},
pages = {1105--1111},
publisher = {Elsevier},
title = {{Soluble guanylate cyclases act in neurons exposed to the body fluid to promote C. elegans aggregation behavior}},
doi = {10.1016/j.cub.2004.06.027},
volume = {14},
year = {2004},
}
@article{889,
abstract = {The function of protein and RNA molecules depends on complex epistatic interactions between sites. Therefore, the deleterious effect of a mutation can be suppressed by a compensatory second-site substitution. In relating a list of 86 pathogenic mutations in human IRNAs encoded by mitochondrial genes to the sequences of their mammalian orthologs, we noted that 52 pathogenic mutations were present in normal tRNAs of one or several nonhuman mammals. We found at least five mechanisms of compensation for 32 pathogenic mutations that destroyed a Watson-Crick pair in one of the four tRNA stems: restoration of the affected Watson-Crick interaction (25 cases), strengthening of another pair (4 cases), creation of a new pair (8 cases), changes of multiple interactions in the affected stem (11 cases) and changes involving the interaction between the loop and stem structures (3 cases). A pathogenic mutation and its compensating substitution are fixed in a lineage in rapid succession, and often a compensatory interaction evolves convergently in different clades. At least 10%, and perhaps as many as 50%, of all nucleotide substitutions in evolving mammalian (RNAs participate in such interactions, indicating that the evolution of tRNAs proceeds along highly epistatic fitness ridges.},
author = {Kern, Andrew D and Fyodor Kondrashov},
journal = {Nature Genetics},
number = {11},
pages = {1207 -- 1212},
publisher = {Nature Publishing Group},
title = {{Mechanisms and convergence of compensatory evolution in mammalian mitochondrial tRNAs}},
doi = {10.1038/ng1451},
volume = {36},
year = {2004},
}
@article{2356,
abstract = {Recent experimental and theoretical work has shown that there are conditions in which a trapped, low-density Bose gas behaves like the one-dimensional delta-function Bose gas solved years ago by Lieb and Liniger. This is an intrinsically quantum-mechanical phenomenon because it is not necessary to have a trap width that is the size of an atom - as might have been supposed - but it suffices merely to have a trap width such that the energy gap for motion in the transverse direction is large compared to the energy associated with the motion along the trap. Up to now the theoretical arguments have been based on variational - perturbative ideas or numerical investigations. In contrast, this paper gives a rigorous proof of the one-dimensional behavior as far as the ground state energy and particle density are concerned. There are four parameters involved: the particle number, N, transverse and longitudinal dimensions of the trap, r and L, and the scattering length a of the interaction potential. Our main result is that if r/L → 0 and N → ∞ the ground state energy and density can be obtained by minimizing a one-dimensional density functional involving the Lieb-Liniger energy density with coupling constant ∼ a/r 2. This density functional simplifies in various limiting cases and we identify five asymptotic parameter regions altogether. Three of these, corresponding to the weak coupling regime, can also be obtained as limits of a three-dimensional Gross-Pitaevskii theory. We also show that Bose-Einstein condensation in the ground state persists in a part of this regime. In the strong coupling regime the longitudinal motion of the particles is strongly correlated. The Gross-Pitaevskii description is not valid in this regime and new mathematical methods come into play.},
author = {Lieb, Élliott H and Robert Seiringer and Yngvason, Jakob},
journal = {Communications in Mathematical Physics},
number = {2},
pages = {347 -- 393},
publisher = {Springer},
title = {{One-dimensional behavior of dilute, trapped Bose gases}},
doi = {10.1007/s00220-003-0993-3},
volume = {244},
year = {2004},
}
@article{2426,
abstract = {We introduce the adaptive neighborhood graph as a data structure for modeling a smooth manifold M embedded in some Euclidean space ℝ d. We assume that M is known to us only through a finite sample P ⊂ M, as is often the case in applications. The adaptive neighborhood graph is a geometric graph on P. Its complexity is at most min{2O(k)n, n2}, where n = P and k = dim M, as opposed to the n[d/2] complexity of the Delaunay triangulation, which is often used to model manifolds. We prove that we can correctly infer the connected components and the dimension of M from the adaptive neighborhood graph provided a certain standard sampling condition is fulfilled. The running time of the dimension detection algorithm is d20(k7 log k) for each connected component of M. If the dimension is considered constant, this is a constant-time operation, and the adaptive neighborhood graph is of linear size. Moreover, the exponential dependence of the constants is only on the intrinsic dimension k, not on the ambient dimension d. This is of particular interest if the co-dimension is high, i.e., if k is much smaller than d, as is the case in many applications. The adaptive neighborhood graph also allows us to approximate the geodesic distances between the points in P.},
author = {Giesen, Joachim and Uli Wagner},
journal = {Discrete & Computational Geometry},
number = {2},
pages = {245 -- 267},
publisher = {Springer},
title = {{Shape dimension and intrinsic metric from samples of manifolds}},
doi = {10.1007/s00454-004-1120-8},
volume = {32},
year = {2004},
}
@article{2642,
abstract = {In the hippocampal CA1 region, metabotropic glutamate subtype 1 (mGluR1) receptors have been implicated in a variety of physiological responses to glutamate, which include modulation of synaptic transmission and plasticity, as well as neuronal excitability and synchronization. The mGluR1α isoform is characteristically expressed only by nonprincipal cells, and it is particularly enriched in somatostatin (SS -containing interneurons in stratum oriens-alveus. Anatomical and physiological data have indicated the presence of mGluR1α in several distinct classes of interneurons with their somata located also in strata pyramidale, radiatum, and lacunosum moleculare. Each different interneuron subtype, as defined by functionally relevant criteria, including input/output characteristics and expression of selective molecular markers, subserves distinct functions in local hippocampal circuits. We have investigated which of the different CA1 interneuron classes express mGluR1α by immunofluorescent labeling, combining antibodies to mGluR1α, calcium-binding proteins, and neuropeptides, and by intracellular labeling in vitro. Several types of interneuron that are immunopositive for mGluR1α each targeted different domains of pyramidal cells and included (1) O-LM interneurons, found to coexpress both SS and parvalbumin (PV); (2) interneurons with target selectivity for other interneurons, expressing vasoactive intestinal polypeptide (VIP) and/or the calcium-binding protein calretinin; (3) procholecystokinin-immunopositive interneurons probably non-basket and dendrite-targeting; and (4) an as-yet unidentified SS-immunoreactive but PV-immunonegative interneuron class, possibly corresponding to oriensbistratified cells. Estimation of the relative proportion of mGluR1α-positive interneurons showed 43%, 46%, and 30% co-labeling with SS, VIP, or PV, respectively. The identification of the specific subclasses of CA1 interneurons expressing mGluR1α provides the network basis for assessing the contribution of this receptor to the excitability of the hippocampus.},
author = {Ferraguti, Francesco and Cobden, Philip M and Pollard, Marie and Cope, David W and Ryuichi Shigemoto and Watanabe, Masahiko and Somogyi, Péter},
journal = {Hippocampus},
number = {2},
pages = {193 -- 215},
publisher = {Wiley-Blackwell},
title = {{Immunolocalization of metabotropic glutamate receptor 1α (mGluR1α) in distinct classes of interneuron in the CA1 region of the rat hippocampus}},
doi = {10.1002/hipo.10163},
volume = {14},
year = {2004},
}
@article{2786,
abstract = {Transition to turbulence in pipe flow is one of the most fundamental and longest- standing problems in fluid dynamics. Stability theory suggests that the flow remains laminar for all flow rates, but in practice pipe flow becomes turbulent even at moderate speeds. This transition drastically affects the transport efficiency of mass, momentum, and heat. On the basis of the recent discovery of unstable traveling waves in computational studies of the Navier-Stokes equations and ideas from dynamical systems theory, a model for the transition process has been suggested. We report experimental observation of these traveling waves in pipe flow, confirming the proposed transition scenario and suggesting that the dynamics associated with these unstable states may indeed capture the nature of fluid turbulence.},
author = {Björn Hof and van Doorne, Casimir W and Westerweel, Jerry and Nieuwstadt, Frans T and Faisst, Holger and Eckhardt, Bruno and Wedin, Håkan and Kersweli, Richard R and Waleffe, Fabian},
journal = {Science},
number = {5690},
pages = {1594 -- 1598},
publisher = {American Association for the Advancement of Science},
title = {{Experimental observation of nonlinear traveling waves in turbulent pipe flow}},
doi = {10.1126/science.1100393},
volume = {305},
year = {2004},
}
@inproceedings{3208,
abstract = {A new technique for proving the adaptive indistinguishability of two systems, each composed of some component systems, is presented, using only the fact that corresponding component systems are non-adaptively indistinguishable. The main tool is the definition of a special monotone condition for a random system F, relative to another random system G, whose probability of occurring for a given distinguisher D is closely related to the distinguishing advantage ε of D for F and G, namely it is lower and upper bounded by ε and (1+ln1), respectively.
A concrete instantiation of this result shows that the cascade of two random permutations (with the second one inverted) is indistinguishable from a uniform random permutation by adaptive distinguishers which may query the system from both sides, assuming the components’ security only against non-adaptive one-sided distinguishers.
As applications we provide some results in various fields as almost k-wise independent probability spaces, decorrelation theory and computational indistinguishability (i.e., pseudo-randomness).},
author = {Maurer, Ueli M and Krzysztof Pietrzak},
pages = {410 -- 427},
publisher = {Springer},
title = {{Composition of random systems: When two weak make one strong}},
doi = {10.1007/978-3-540-24638-1_23},
volume = {2951},
year = {2004},
}
@article{3614,
abstract = {We analyze the changes in the mean and variance components of a quantitative trait caused by changes in allele frequencies, concentrating on the effects of genetic drift. We use a general representation of epistasis and dominance that allows an arbitrary relation between genotype and phenotype for any number of diallelic loci. We assume initial and final Hardy-Weinberg and linkage equilibrium in our analyses of drift-induced changes. Random drift generates transient linkage disequilibria that cause correlations between allele frequency fluctuations at different loci. However, we show that these have negligible effects, at least for interactions among small numbers of loci. Our analyses are based on diffusion approximations that summarize the effects of drift in terms of F, the inbreeding coefficient, interpreted as the expected proportional decrease in heterozygosity at each locus. For haploids, the variance of the trait mean after a population bottleneck is var(Δz̄) =inline imagewhere n is the number of loci contributing to the trait variance, VA(1)=VA is the additive genetic variance, and VA(k) is the kth-order additive epistatic variance. The expected additive genetic variance after the bottleneck, denoted (V*A), is closely related to var(Δz̄); (V*A) (1 –F)inline imageThus, epistasis inflates the expected additive variance above VA(1 –F), the expectation under additivity. For haploids (and diploids without dominance), the expected value of every variance component is inflated by the existence of higher order interactions (e.g., third-order epistasis inflates (V*AA)). This is not true in general with diploidy, because dominance alone can reduce (V*A) below VA(1 –F) (e.g., when dominant alleles are rare). Without dominance, diploidy produces simple expressions: var(Δz̄)=inline image=1 (2F) kVA(k) and (V*A) = (1 –F)inline imagek(2F)k-1VA(k) With dominance (and even without epistasis), var(Δz̄)and (V*A) no longer depend solely on the variance components in the base population. For small F, the expected additive variance simplifies to (V*A)(1 –F) VA+ 4FVAA+2FVD+2FCAD, where CAD is a sum of two terms describing covariances between additive effects and dominance and additive × dominance interactions. Whether population bottlenecks lead to expected increases in additive variance depends primarily on the ratio of nonadditive to additive genetic variance in the base population, but dominance precludes simple predictions based solely on variance components. We illustrate these results using a model in which genotypic values are drawn at random, allowing extreme and erratic epistatic interactions. Although our analyses clarify the conditions under which drift is expected to increase VA, we question the evolutionary importance of such increases.},
author = {Nicholas Barton and Turelli, Michael},
journal = {Evolution; International Journal of Organic Evolution},
number = {10},
pages = {2111 -- 2132},
publisher = {Wiley-Blackwell},
title = {{Effects of allele frequency changes on variance components under a general model of epistasis}},
doi = {10.1111/j.0014-3820.2004.tb01591.x},
volume = {58},
year = {2004},
}
@inbook{3575,
abstract = {The Jacobi set of two Morse functions defined on a common - manifold is the set of critical points of the restrictions of one func- tion to the level sets of the other function. Equivalently, it is the set of points where the gradients of the functions are parallel. For a generic pair of Morse functions, the Jacobi set is a smoothly embed- ded 1-manifold. We give a polynomial-time algorithm that com- putes the piecewise linear analog of the Jacobi set for functions specified at the vertices of a triangulation, and we generalize all results to more than two but at most Morse functions.},
author = {Herbert Edelsbrunner and Harer, John},
booktitle = {Foundations of Computational Mathematics},
pages = {37 -- 57},
publisher = {Springer},
title = {{Jacobi sets of multiple Morse functions}},
doi = {10.1017/CBO9781139106962.003},
volume = {312},
year = {2004},
}