@article{12925, abstract = {Normal function of organs and cells is tightly linked to the cytoarchitecture. Control of the cell volume is therefore vital for the organism. A widely established strategy of cells to counteract swelling is the activation of chloride and potassium channels, which leads to a net efflux of salt followed by water - a process termed regulatory volume decrease. Since there is evidence for swelling-dependent chloride channels (IClswell) being activated also during pathological processes, the identification of the molecular entity underlying IClswell is of utmost importance. Several proteins are discussed as the channel forming IClswell, i.e. phospholemman, p-glycoprotein, CLC-3 and ICln. In this review we would like to focus on the properties of ICln, a protein cloned from a Madin Darby canine kidney (MDCK) cell library whose expression in Xenopus laevis oocytes resulted in a nucleotide sensitive outwardly rectifying chloride current closely resembling the biophysical properties of IClswell.}, author = {Fürst, Johannes and Jakab, Martin and König, Matthias and Ritter, Markus and Gschwentner, Martin and Rudzki, Jakob and Danzl, Johann G and Mayer, Michael and Burtscher, Carmen M. and Schirmer, Julia and Maier, Brigitte and Nairz, Manfred and Chwatal, Sabine and Paulmichl, Markus}, issn = {1015-8987}, journal = {Cellular Physiology and Biochemistry}, keywords = {Physiology}, number = {5-6}, pages = {329--334}, publisher = {S. Karger AG}, title = {{Structure and Function of the Ion Channel ICln}}, doi = {10.1159/000016374}, volume = {10}, year = {2000}, } @article{842, author = {Wolf, Yuri and Kondrashov, Fyodor and Koonin, Eugene}, issn = {0168-9479}, journal = {Trends in Genetics}, number = {8}, pages = {333 -- 334}, publisher = {Elsevier}, title = {{No footprints of primordial introns in a eukaryotic genome}}, doi = {10.1016/S0168-9525(00)02059-X}, volume = {16}, year = {2000}, } @article{8525, abstract = {Let M be a smooth compact manifold of dimension at least 2 and Diffr(M) be the space of C r smooth diffeomorphisms of M. Associate to each diffeomorphism f;isin; Diffr(M) the sequence P n (f) of the number of isolated periodic points for f of period n. In this paper we exhibit an open set N in the space of diffeomorphisms Diffr(M) such for a Baire generic diffeomorphism f∈N the number of periodic points P n f grows with a period n faster than any following sequence of numbers {a n } n ∈ Z + along a subsequence, i.e. P n (f)>a ni for some n i →∞ with i→∞. In the cases of surface diffeomorphisms, i.e. dim M≡2, an open set N with a supergrowth of the number of periodic points is a Newhouse domain. A proof of the man result is based on the Gontchenko–Shilnikov–Turaev Theorem [GST]. A complete proof of that theorem is also presented.}, author = {Kaloshin, Vadim}, issn = {0010-3616}, journal = {Communications in Mathematical Physics}, keywords = {Mathematical Physics, Statistical and Nonlinear Physics}, pages = {253--271}, publisher = {Springer Nature}, title = {{Generic diffeomorphisms with superexponential growth of number of periodic orbits}}, doi = {10.1007/s002200050811}, volume = {211}, year = {2000}, } @inproceedings{1736, abstract = {A coding scheme called diode is compared with duobinary signalling and with normal binary transmission. It is shown that the diode coding suppresses the FWM products of a three channel DWDM system and this reduction against that achieved with duobinary coding is presented. The results presented show how the average level of the FWM products relative to the average levels of the three optical carriers vary over the channel spacing range. The suppression observed is about / dB more than that achieved with duobinary modulation and is greater for narrow channel spacing.}, author = {Katsaros, Georgios and Lane, Phil and Murphy, Michelle}, booktitle = {Proceedings of the 2000 IEEE Annual Meeting Conference }, isbn = {078035947X}, location = {Rio Grande, PR, USA}, pages = {27 -- 28}, publisher = {IEEE}, title = {{Comparison of the impact of FWM on binary, duobinary and dicode modulation in DWDM systems}}, doi = {10.1109/LEOS.2000.890656}, volume = {1}, year = {2000}, } @article{1957, abstract = {NADH:ubiquinone oxidoreductase (complex I) is the first and largest enzyme of the mitochondrial respiratory chain. The low-resolution structure of the complex is known from electron microscopy studies. The general shape of the complex is in the form of an L, with one arm in the membrane and the other peripheral. We have purified complex I from beef heart mitochondria and reconstituted the enzyme into lipid bilayers. Under different conditions, several two-dimensional crystal forms were obtained. Crystals belonging to space groups p2221 and c12 (unit cell 488 Å x 79 Å) were obtained at 22°C and contained only the membrane fragment of complex I similar to hydrophobic subcomplex Iβ but lacking the ND5 subunit. A crystal form with larger unit cell (534 Å x 81 Å, space group c12) produced at 4°C contained both the peripheral and membrane arms of the enzyme, except that ND5 was missing. Projection maps from frozen hydrated samples were calculated for all crystal forms. By comparing two different c12 crystal forms, extra electron density in the projection map of large crystal form was assigned to the peripheral arm of the enzyme. One of the features of the map is a deep, channel-like, cleft next to peripheral arm. Comparison with available structures of the intact enzyme indicates that large hydrophobic subunit ND5 is situated at the distal end of the membrane domain. Possible locations of sub-unit ND4 and of other subunits in the membrane domain are proposed. Implications of our findings for the mechanism of proton pumping by complex I are discussed. (C) 2000 Academic Press.}, author = {Sazanov, Leonid A and Walker, John}, issn = {0022-2836}, journal = {Journal of Molecular Biology}, number = {2}, pages = {455 -- 464}, publisher = {Elsevier}, title = {{Cryo-electron crystallography of two sub-complexes of bovine complex I reveals the relationship between the membrane and peripheral arms}}, doi = {10.1006/jmbi.2000.4079}, volume = {302}, year = {2000}, } @article{1958, abstract = { Complex I (NADH:ubiquinone oxidoreductase) purified from bovine heart mitochondria was treated with the detergent N,N-dimethyldodecylamine N-oxide (LDAO). The enzyme dissociated into two known subcomplexes, Iα and Iβ, containing mostly hydrophilic and hydrophobic subunits, and a previously undetected fragment referred to as Iγ. Subcomplex Iγ contains the hydrophobic subunits ND1, ND2, ND3, and ND4L which are encoded in the mitochondrial genome, and the nuclear-encoded subunit KFYL. During size- exclusion chromatography in the presence of LDAO, subcomplex Iα lost several subunits and formed another characterized subcomplex known as Iλ. Similarly, subcomplex Iβ dissociated into two smaller subcomplexes, one of which contains the hydrophobic subunits ND4 and ND5; subcomplex Iγ released a fragment containing ND1 and ND2. These results suggest that in the intact complex subunits ND1 and ND2 are likely to be in a different region of the membrane domain than subunits ND4 and ND5. The compositions of the various subcomplexes and fragments of complex I provide an organization of the subunits of the enzyme in the framework of the known low resolution structure of the enzyme.}, author = {Sazanov, Leonid A and Peak Chew, Sew and Fearnley, Ian and Walker, John}, issn = {0006-2960}, journal = {Biochemistry}, number = {24}, pages = {7229 -- 7235}, publisher = {ACS}, title = {{Resolution of the membrane domain of bovine complex I into subcomplexes: implications for the structural organization of the enzyme}}, doi = {10.1021/bi000335t}, volume = {39}, year = {2000}, } @article{13437, abstract = {Liquid/liquid Phase Transfer Catalysis (PTC) reaction of 4-chlorobutyronitrile with nonenolisable aldehydes leads via an addition-cyclisation reaction sequence to derivatives of tetrahydrofuran-3-carbonitrile.}, author = {Macogonkosza, Mieczysław and Przyborowski, Jacek and Klajn, Rafal and Kwast, Andrzej}, issn = {1437-2096}, journal = {Synlett}, keywords = {Organic Chemistry}, number = {12}, pages = {1773--1774}, publisher = {Georg Thieme Verlag}, title = {{Simple synthesis of 2-substituted Tetrahydrofuran-3-carbonitriles}}, doi = {10.1055/s-2000-8670}, volume = {2000}, year = {2000}, } @article{1455, abstract = {First, a special case of Knaster's problem is proved implying that each symmetric convex body in ℝ3 admits an inscribed cube. It is deduced from a theorem in equivariant topology, which says that there is no S4 - equivariant map from SO(3) to S2, where S4 acts on SO(3) on the right as the rotation group of the cube, and on S2 on the right as the symmetry group of the regular tetrahedron. Some generalizations are also given. Second, it is shown how the above non-existence theorem yields Makeev's conjecture in ℝ3 that each set in ℝ3 of diameter 1 can be covered by a rhombic dodecahedron, which has distance 1 between its opposite faces. This reveals an unexpected connection between inscribing cubes into symmetric bodies and covering sets by rhombic dodecahedra. Finally, a possible application of our second theorem to the Borsuk problem in ℝ3 is pointed out.}, author = {Hausel, Tamas and Makai, Endre and Szücs, András}, issn = {0025-5793}, journal = {Mathematika}, number = {1-2}, pages = {371 -- 397}, publisher = {University College London}, title = {{Inscribing cubes and covering by rhombic dodecahedra via equivariant topology}}, doi = {10.1112/S0025579300015965}, volume = {47}, year = {2000}, } @article{11126, abstract = {Nuclear import of the two uracil-rich small nuclear ribonucleoprotein (U snRNP) components U1A and U2B′′ is mediated by unusually long and complex nuclear localization signals (NLSs). Here we investigate nuclear import of U1A and U2B′′ in vitro and demonstrate that it occurs by an active, saturable process. Several lines of evidence suggest that import of the two proteins occurs by an import mechanism different to those characterized previously. No cross competition is seen with a variety of previously studied NLSs. In contrast to import mediated by members of the importin-β family of nucleocytoplasmic transport receptors, U1A/U2B′′ import is not inhibited by either nonhydrolyzable guanosine triphosphate (GTP) analogues or by a mutant of the GTPase Ran that is incapable of GTP hydrolysis. Adenosine triphosphate is capable of supporting U1A and U2B′′ import, whereas neither nonhydrolyzable adenosine triphosphate analogues nor GTP can do so. U1A and U2B′′ import in vitro does not require the addition of soluble cytosolic proteins, but a factor or factors required for U1A and U2B′′ import remains tightly associated with the nuclear fraction of conventionally permeabilized cells. This activity can be solubilized in the presence of elevated MgCl2. These data suggest that U1A and U2B′′ import into the nucleus occurs by a hitherto uncharacterized mechanism.}, author = {HETZER, Martin W and Mattaj, Iain W.}, issn = {1540-8140}, journal = {Journal of Cell Biology}, keywords = {Cell Biology}, number = {2}, pages = {293--304}, publisher = {Rockefeller University Press}, title = {{An Atp-dependent, Ran-independent mechanism for nuclear import of the U1a and U2b′′ spliceosome proteins}}, doi = {10.1083/jcb.148.2.293}, volume = {148}, year = {2000}, } @article{11127, abstract = {Nuclear formation in Xenopus egg extracts requires cytosol and is inhibited by GTPγS, indicating a requirement for GTPase activity. Nuclear envelope (NE) vesicle fusion is extensively inhibited by GTPγS and two mutant forms of the Ran GTPase, Q69L and T24N. Depletion of either Ran or RCC1, the exchange factor for Ran, from the assembly reaction also inhibits this step of NE formation. Ran depletion can be complemented by the addition of Ran loaded with either GTP or GDP but not with GTPγS. RCC1 depletion is only complemented by RCC1 itself or by RanGTP. Thus, generation of RanGTP by RCC1 and GTP hydrolysis by Ran are both required for the extensive membrane fusion events that lead to NE formation.}, author = {HETZER, Martin W and Bilbao-Cortés, Daniel and Walther, Tobias C and Gruss, Oliver J and Mattaj, Iain W}, issn = {1097-2765}, journal = {Molecular Cell}, keywords = {Cell Biology, Molecular Biology}, number = {6}, pages = {1013--1024}, publisher = {Elsevier}, title = {{GTP hydrolysis by Ran is required for nuclear envelope assembly}}, doi = {10.1016/s1097-2765(00)80266-x}, volume = {5}, year = {2000}, } @article{11683, abstract = {The vertex connectivity κ of a graph is the smallest number of vertices whose deletion separates the graph or makes it trivial. We present the fastest known deterministic algorithm for finding the vertex connectivity and a corresponding separator. The time for a digraph having n vertices and m edges is O(min{κ3 + n, κn}m); for an undirected graph the term m can be replaced by κn. A randomized algorithm finds κ with error probability 1/2 in time O(nm). If the vertices have nonnegative weights the weighted vertex connectivity is found in time O(κ1nmlog(n2/m)) where κ1 ≤ m/n is the unweighted vertex connectivity or in expected time O(nmlog(n2/m)) with error probability 1/2. The main algorithm combines two previous vertex connectivity algorithms and a generalization of the preflow-push algorithm of Hao and Orlin (1994, J. Algorithms17, 424–446) that computes edge connectivity.}, author = {Henzinger, Monika H and Rao, Satish and Gabow, Harold N.}, issn = {0196-6774}, journal = {Journal of Algorithms}, keywords = {Computational Theory and Mathematics, Computational Mathematics, Control and Optimization}, number = {2}, pages = {222--250}, publisher = {Elsevier}, title = {{Computing vertex connectivity: New bounds from old techniques}}, doi = {10.1006/jagm.1999.1055}, volume = {34}, year = {2000}, } @article{11685, abstract = {We consider the problem of sampling URLs uniformly at random from the Web. A tool for sampling URLs uniformly can be used to estimate various properties of Web pages, such as the fraction of pages in various Internet domains or written in various languages. Moreover, uniform URL sampling can be used to determine the sizes of various search engines relative to the entire Web. In this paper, we consider sampling approaches based on random walks of the Web graph. In particular, we suggest ways of improving sampling based on random walks to make the samples closer to uniform. We suggest a natural test bed based on random graphs for testing the effectiveness of our procedures. We then use our sampling approach to estimate the distribution of pages over various Internet domains and to estimate the coverage of various search engine indexes.}, author = {Henzinger, Monika H and Heydon, Allan and Mitzenmacher, Michael and Najork, Marc}, issn = {1389-1286}, journal = {Computer Networks}, keywords = {URL sampling, Random walks, Internet domain distribution, Search engine size}, number = {1-6}, pages = {295--308}, publisher = {Elsevier}, title = {{On near-uniform URL sampling}}, doi = {10.1016/s1389-1286(00)00055-4}, volume = {33}, year = {2000}, } @article{11694, abstract = {We consider exploration problems where a robot has to construct a complete map of an unknown environment. We assume that the environment is modeled by a directed, strongly connected graph. The robot's task is to visit all nodes and edges of the graph using the minimum number R of edge traversals. Deng and Papadimitriou [Proceedings of the 31st Symposium on the Foundations of Computer Science, 1990, pp. 356-361] showed an upper bound for R ofd O(d)m and Koutsoupias (reported by Deng and Papadimitriou) gave a lower bound of Ω≠(d2m), where m is the number of edges in the graph and d is the minimum number of edges that have to be added to make the graph Eulerian. We give the 1rst subexponential algorithm for this exploration problem, which achieves an upper bound of dO(logd)m. We also show a matching lower bound of d≠(logd)m for our algorithm. Additionally, we give lower bounds of 2≠(d)m, respectively, d≠(logd)m for various other natural exploration algorithms.}, author = {Albers, Susanne and Henzinger, Monika H}, issn = {1095-7111}, journal = {SIAM Journal on Computing}, keywords = {directed graph, exploration algorithm}, location = {El Paso, TX, United States}, number = {4}, pages = {1164--1188}, publisher = {Society for Industrial and Applied Mathematics}, title = {{Exploring unknown environments}}, doi = {10.1137/s009753979732428x}, volume = {29}, year = {2000}, } @article{11770, abstract = {We compare several algorithms for identifying mirrored hosts on the World Wide Web. The algorithms operate on the basis of URL strings and linkage data: the type of information about Web pages easily available from Web proxies and crawlers. Identification of mirrored hosts can improve Web-based information retrieval in several ways: first, by identifying mirrored hosts, search engines can avoid storing and returning duplicate documents. Second, several new information retrieval techniques for the Web make inferences based on the explicit links among hypertext documents—mirroring perturbs their graph model and degrades performance. Third, mirroring information can be used to redirect users to alternate mirror sites to compensate for various failures, and can thus improve the performance of Web browsers and proxies. We evaluated four classes of “top-down” algorithms for detecting mirrored host pairs (that is, algorithms that are based on page attributes such as URL, IP address, and hyperlinks between pages, and not on the page content) on a collection of 140 million URLs (on 230,000 hosts) and their associated connectivity information. Our best approach is one which combines five algorithms and achieved a precision of 0.57 for a recall of 0.86 considering 100,000 ranked host pairs.}, author = {Bharat, Krishna and Broder, Andrei and Dean, Jeffrey and Henzinger, Monika H}, issn = {0002-8231}, journal = {Journal of the American Society for Information Science}, number = {12}, pages = {1114--1122}, publisher = {Wiley}, title = {{A comparison of techniques to find mirrored hosts on the WWW}}, doi = {10.1002/1097-4571(2000)9999:9999<::aid-asi1025>3.0.co;2-0}, volume = {51}, year = {2000}, } @inproceedings{11802, abstract = {In this paper we survey algorithmic aspects of Web information retrieval. As an example, we discuss ranking of search engine results using connectivity analysis.}, author = {Henzinger, Monika H}, booktitle = {8th Annual European Symposium on Algorithms}, isbn = {9783540410041}, issn = {1611-3349}, location = {Saarbrücken, Germany}, pages = {1–8}, publisher = {Springer Nature}, title = {{Web information retrieval - an algorithmic perspective}}, doi = {10.1007/3-540-45253-2_1}, volume = {1879}, year = {2000}, } @article{11893, abstract = {We present fully dynamic algorithms for maintaining the biconnected components in general and plane graphs. A fully dynamic algorithm maintains a graph during a sequence of insertions and deletions of edges or isolated vertices. Let m be the number of edges and n be the number of vertices in a graph. The time per operation of the best deterministic algorithms is 𝑂(𝑛√) in general graphs and O(log n) in plane graphs for fully dynamic connectivity and O(min m2/3 ,n}) in general graphs and 𝑂(𝑛√) in plane graphs for fully dynamic biconnectivity. We improve the later running times to 𝑂(𝑚log𝑛‾‾‾‾‾‾‾√) in general graphs and O(log 2n ) in plane graphs. Our algorithm for general graphscan also find the biconnected components of all vertices in time O(n).}, author = {Henzinger, Monika H}, issn = {1095-7111}, journal = {SIAM Journal on Computing}, number = {6}, pages = {1761--1815}, publisher = {Society for Industrial & Applied Mathematics}, title = {{Improved data structures for fully dynamic biconnectivity}}, doi = {10.1137/s0097539794263907}, volume = {29}, year = {2000}, } @inproceedings{2325, author = {Robert Seiringer}, pages = {53 -- 72}, publisher = {American Mathematical Society}, title = {{Inequalities for Schrödinger operators and applications to the stability of matter problem }}, doi = {10.1090/conm/529}, volume = {529}, year = {2000}, } @inproceedings{2342, abstract = {In the theoretical description of recent experiments with dilute Bose gases confined in external potentials the Gross-Pitaevskii equation plays an important role. Its status as an approximation for the quantum mechanical many-body ground state problem has recently been rigorously clarified. A summary of this work is presented here.}, author = {Seiringer, Robert and Lieb, Élliott and Yngvason, Jakob}, booktitle = {Proceedings of the International Symposium on Quantum Theory and Symmetries}, isbn = {9789810242374 }, pages = {101 -- 110}, publisher = {World Scientific Publishing}, title = {{The ground state energy and density of interacting bosons in a trap}}, year = {2000}, } @article{2343, abstract = {We study the energy levels of a single particle in a homogeneous magnetic field and in an axially symmetric external potential. For potentials that are superharmonic off the central axis, we find a general 'pseudoconcave' ordering of the ground state energies of the Hamiltonian restricted to the sectors with fixed angular momentum. The physical applications include atoms and ions in strong magnetic fields. There the energies are monotone increasing and concave in angular momentum. In the case of a periodic chain of atoms, the pseudoconcavity extends to the entire lowest band of Bloch functions.}, author = {Baumgartner, Bernhard and Robert Seiringer}, journal = {Letters in Mathematical Physics}, number = {3}, pages = {213 -- 226}, publisher = {Springer}, title = {{On the ordering of energy levels in homogeneous magnetic fields}}, doi = { 10.1023/A:1010978807635}, volume = {54}, year = {2000}, } @article{2344, abstract = {The ground-state properties of interacting Bose gases in external potentials, as considered in recent experiments, are usually described by means of the Gross-Pitaevskii energy functional. We present here a rigorous proof of the asymptotic exactness of this approximation for the ground-state energy and particle density of a dilute Bose gas with a positive interaction.}, author = {Lieb, Élliott and Seiringer, Robert and Yngvason, Jakob}, issn = {0556-2791}, journal = {Physical Review A - Atomic, Molecular, and Optical Physics}, number = {4}, pages = {436021 -- 4360213}, publisher = {American Physical Society}, title = {{Bosons in a trap: A rigorous derivation of the Gross-Pitaevskii energy functional}}, doi = {10.1103/PhysRevA.61.043602}, volume = {61}, year = {2000}, }