TY - JOUR AB - Systems of three interacting particles are notorious for their complex physical behaviour. A landmark theoretical result in few-body quantum physics is Efimov\'s prediction1,2 of a universal set of bound trimer states appearing for three identical bosons with a resonant two-body interaction. Counterintuitively, these states even exist in the absence of a corresponding two-body bound state. Since the formulation of Efimov\'s problem in the context of nuclear physics 35 years ago, it has attracted great interest in many areas of physics3-8. However, the observation of Efimov quantum states has remained an elusive goal3,5. Here we report the observation of an Efimov resonance in an ultracold gas of caesium atoms. The resonance occurs in the range of large negative two-body scattering lengths, arising from the coupling of three free atoms to an Efimov trimer. Experimentally, we observe its signature as a giant three-body recombination loss9,10 when the strength of the two-body interaction is varied. We also detect a minimum 9,11,12 in the recombination loss for positive scattering lengths, indicating destructive interference of decay pathways. Our results confirm central theoretical predictions of Efimov physics and represent a starting point with which to explore the universal properties of resonantly interacting few-body systems7. While Feshbach resonances13,14 have provided the key to control quantum-mechanical interactions on the two-body level, Efimov resonances connect ultracold matter15 to the world of few-body quantum phenomena. AU - Kraemer, Tobias AU - Mark, Michael AU - Waldburger, Philipp AU - Danzl, Johann G AU - Chin, Cheng AU - Engeser, Bastian AU - Lange, Adam AU - Pilch, Karl AU - Jaakkola, Antti AU - Nägerl, Hanns AU - Grimm, Rudolf ID - 1033 IS - 7082 JF - Nature TI - Evidence for Efimov quantum states in an ultracold gas of caesium atoms VL - 440 ER - TY - CONF AB - Three interacting particles form a system which is well known for its complex physical behavior. A landmark theoretical result in few-body quantum physics is Efimov\'s prediction of a universal set of weakly bound trimer states appearing for three identical bosons with a resonant two-body interaction [1, 2]. Surprisingly, these states even exist in the absence of a corresponding two-body bound state and their precise nature is largely independent of the particular type of the two-body interaction potential. Efimov\'s scenario has attracted great interest in many areas of physics; an experimental test however has not been achieved. We report the observation of an Efimov resonance in an ultracold thermal gas of cesium atoms [3]. The resonance occurs in the range of large negative two-body scattering lengths and arises from the coupling of three free atoms to an Efimov trimer. We observe its signature as a giant three-body recombination loss when the strength of the two-body interaction is varied near a Feshbach resonance. This resonance develops into a continuum resonance at non-zero collision energies, and we observe a shift of the resonance position as a function of temperature. We also report on a minimum in the recombination loss for positive scattering lengths, indicating destructive interference of decay pathways. Our results confirm central theoretical predictions of Efimov physics and represent a starting point from which to explore the universal properties of resonantly interacting few-body systems. AU - Nägerl, Hanns AU - Kraemer, Tobias AU - Mark, Michael AU - Waldburger, Philipp AU - Danzl, Johann G AU - Engeser, Bastian AU - Lange, Adam AU - Pilch, Karl AU - Jaakkola, Antti AU - Chin, Cheng AU - Grimm, Rudolf ID - 1034 TI - Experimental evidence for Efimov quantum states VL - 869 ER - TY - CHAP AU - Harris, J. Robin AU - Almouzni, Geneviève AU - Kirschner, Doris AU - Dimitrova, Daniela AU - Nickerson, Jeffrey A. AU - Underwood, Jean AU - Wagner, Stefan AU - Korbei, Barbara AU - Foisner, Roland AU - Walther, Tobias C. AU - HETZER, Martin W AU - Peters, Reiner AU - Walev, Ivan AU - de Kroon, Anton I. P. M. AU - Staffhorst, Rutger W. H. M. AU - de Kruijff, Ben AU - Burger, Koert N. J. AU - Netto, Luis Eduardo Soares AU - Bertrand, Eric AU - Alimonti, Judie B. AU - Greenberg, Arnold H. AU - Xiao, Jinnan AU - Pradhan, Anuradha AU - Liu, Yuechueng AU - Paiement, Jacques AU - Young, Robin AU - Goñi, Félix M. AU - Villar, Ana-Victoria AU - Contreras, F.-Xabier AU - Alonso, Alicia AU - Peter, Brian J. AU - Mills, Ian G. AU - Higgins, Matthew K. AU - Brown, William J. AU - Chambers, K. AU - Doody, A. AU - Cheng, C. Yan AU - Mruk, Dolores D. AU - Yang, Chunhong AU - Kirchhoff, Helmut AU - Haase, Winfried AU - Boggasch, Stephanie AU - Paulsen, Harald AU - Benesova, Julie AU - Liffers, Sven-T. AU - Rögner, Matthias AU - Gao, Ya-sheng AU - Sztul, Elizabeth AU - Thiemann, Meinolf AU - Fahimi, H. Dariush AU - Gniadecki, Robert AU - Gajkowska, Barbara AU - Bane, Susan L. AU - Hess, John F. AU - Voss, John C. AU - Fitzgerald, Paul G. AU - Hisanaga, Shin-ichi AU - Sasaki, Takahiro AU - Uéda, Kenji AU - Town, Terrence AU - Tan, Jun AU - Milton, Nathaniel G. N. AU - Chi, Richard AU - Keller, Thomas C. S. AU - Kriajevska, Marina AU - Bronstein, Igor AU - Lukanidin, Eugene AU - Holmes, David F. AU - Kadler, Karl E. ED - Harris, Robin ED - Graham, John ED - Rickwood, David ID - 11119 SN - 9780470847589 T2 - Cell Biology Protocols TI - In Vitro Techniques ER - TY - JOUR AB - Over the last years it has become evident that the nuclear envelope (NE) is more than a passive membrane barrier that separates the nucleus from the cytoplasm. The NE not only controls the trafficking of macromolecules between the nucleoplasm and the cytosol, but also provides anchoring sites for chromosomes and cytoskeleton to the nuclear periphery. Targeting of chromatin to the NE might actually be part of gene expression regulation in eukaryotes. Mutations in certain NE proteins are associated with a diversity of human diseases, including muscular dystrophy, neuropathy, lipodistrophy, torsion dystonia and the premature aging condition progeria. Despite the importance of the NE for cell division and differentiation, relatively little is known about its biogenesis and its role in human diseases. It is our goal to provide a comprehensive view of the NE and to discuss possible implications of NE-associated changes for gene expression, chromatin organization and signal transduction. AU - D’Angelo, M. A. AU - HETZER, Martin W ID - 11117 IS - 3 JF - Cellular and Molecular Life Sciences KW - Cell Biology KW - Cellular and Molecular Neuroscience KW - Pharmacology KW - Molecular Biology KW - Molecular Medicine SN - 1420-682X TI - The role of the nuclear envelope in cellular organization VL - 63 ER - TY - JOUR AB - Nuclear pore complexes are multiprotein channels that span the double lipid bilayer of the nuclear envelope. How new pores are inserted into the intact nuclear envelope of proliferating and differentiating eukaryotic cells is unknown. We found that the Nup107-160 complex was incorporated into assembly sites in the nuclear envelope from both the nucleoplasmic and the cytoplasmic sides. Nuclear pore insertion required the generation of Ran guanosine triphosphate in the nuclear and cytoplasmic compartments. Newly formed nuclear pore complexes did not contain structural components of preexisting pores, suggesting that they can form de novo. AU - D'Angelo, Maximiliano A. AU - Anderson, Daniel J. AU - Richard, Erin AU - HETZER, Martin W ID - 11118 IS - 5772 JF - Science KW - Multidisciplinary SN - 0036-8075 TI - Nuclear pores form de novo from both sides of the nuclear envelope VL - 312 ER - TY - CONF AB - Broder et al.'s [3] shingling algorithm and Charikar's [4] random projection based approach are considered "state-of-the-art" algorithms for finding near-duplicate web pages. Both algorithms were either developed at or used by popular web search engines. We compare the two algorithms on a very large scale, namely on a set of 1.6B distinct web pages. The results show that neither of the algorithms works well for finding near-duplicate pairs on the same site, while both achieve high precision for near-duplicate pairs on different sites. Since Charikar's algorithm finds more near-duplicate pairs on different sites, it achieves a better precision overall, namely 0.50 versus 0.38 for Broder et al.'s algorithm. We present a combined algorithm which achieves precision 0.79 with 79% of the recall of the other algorithms. AU - Henzinger, Monika H ID - 11929 T2 - 29th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval TI - Finding near-duplicate web pages: A large-scale evaluation of algorithms ER - TY - JOUR AB - A Fourier transform technique is introduced for counting the number of solutions of holomorphic moment map equations over a finite field. This technique in turn gives information on Betti numbers of holomorphic symplectic quotients. As a consequence, simple unified proofs are obtained for formulas of Poincaré polynomials of toric hyperkähler varieties (recovering results of Bielawski-Dancer and Hausel-Sturmfels), Poincaré polynomials of Hubert schemes of points and twisted Atiyah-Drinfeld-Hitchin-Manin (ADHM) spaces of instantons on ℂ2 (recovering results of Nakajima-Yoshioka), and Poincaré polynomials of all Nakajima quiver varieties. As an application, a proof of a conjecture of Kac on the number of absolutely indecomposable representations of a quiver is announced. AU - Tamas Hausel ID - 1462 IS - 16 JF - PNAS TI - Betti numbers of holomorphic symplectic quotients via arithmetic Fourier transform VL - 103 ER - TY - JOUR AB - This note proves combinatorially that the intersection pairing on the middle-dimensional compactly supported cohomology of a toric hyperkähler variety is always definite, providing a large number of non-trivial L 2 harmonic forms for toric hyperkähler metrics on these varieties. This is motivated by a result of Hitchin about the definiteness of the pairing of L 2 harmonic forms on complete hyperkähler manifolds of linear growth. AU - Tamas Hausel AU - Swartz, Edward ID - 1461 IS - 8 JF - Proceedings of the American Mathematical Society TI - Intersection forms of toric hyperkähler varieties VL - 134 ER - TY - JOUR AB - Background: Cell-to-cell communication at the synapse involves synaptic transmission as well as signaling mediated by growth factors, which provide developmental and plasticity cues. There is evidence that a retrograde, presynaptic transforming growth factor-β (TGF-β) signaling event regulates synapse development and function in Drosophila. Results: Here we show that a postsynaptic TGF-β signaling event occurs during larval development. The type I receptor Thick veins (Tkv) and the R-Smad transcription factor Mothers-against-dpp (Mad) are localized postsynaptically in the muscle. Furthermore, Mad phosphorylation occurs in regions facing the presynaptic active zones of neurotransmitter release within the postsynaptic subsynaptic reticulum (SSR). In order to monitor in real time the levels of TGF-β signaling in the synapse during synaptic transmission, we have established a FRAP assay to measure Mad nuclear import/export in the muscle. We show that Mad nuclear trafficking depends on stimulation of the muscle. Conclusions: Our data suggest a mechanism linking synaptic transmission and postsynaptic TGF-β signaling that may coordinate nerve-muscle development and function. AU - Dudu, Veronika AU - Bittig, Thomas AU - Entchev, Eugeni AU - Kicheva, Anna AU - Julicher, Frank AU - González Gaitán, Marcos ID - 1715 IS - 7 JF - Current Biology TI - Postsynaptic mad signaling at the Drosophila neuromuscular junction VL - 16 ER - TY - JOUR AB - SiGe islands grown by deposition of 10 monolayers of Ge on Si(0 0 1) at 740 °C were investigated by using a combination of selective wet chemical etching and atomic force microscopy. The used etchant, a solution consisting of ammonium hydroxide and hydrogen peroxide, shows a high selectivity of Ge over SixGe1-x and is characterized by relatively slow etching rates for Si-rich alloys. By performing successive etching experiments on the same sample area, we are able to gain a deeper insight into the lateral displacement the islands undergo during post growth annealing. AU - Georgios Katsaros AU - Rastelli, Armando AU - Stoffel, Mathieu AU - Isella, Giovanni AU - Von Känel, Hans AU - Bittner, Alexander M AU - Tersoff, Jerry AU - Denker, Ulrich AU - Schmidt, Oliver G AU - Costantini, Giovanni AU - Kern, Klaus ID - 1745 IS - 12 JF - Surface Science TI - Investigating the lateral motion of SiGe islands by selective chemical etching VL - 600 ER - TY - JOUR AB - We report on recent advances in the understanding of surface processes occurring during growth and post-growth annealing of strained islands which may find application as self-assembled quantum dots. We investigate the model system SiGe/Si(0 0 1) by a new approach based on "reading the footprints" which islands leave on the substrate during their growth and evolution. Such footprints consist of trenches carved in the Si substrate. We distinguish between surface footprints and footprints buried below the islands. The former allow us to discriminate islands which are in the process of growing from those which are shrinking. Islands with steep morphologies grow at the expense of smaller and shallower islands, consistent with the kinetics of anomalous coarsening. While shrinking, islands change their shape according to thermodynamic predictions. Buried footprints are investigated by removing the SiGe epilayer by means of selective wet chemical etching. Their reading shows that: (i) during post-growth annealing islands move laterally because of surface-mediated Si-Ge intermixing; (ii) a tree-ring structure of trenches is created by dislocated islands during their "cyclic" growth. This allows us to distinguish coherent from dislocated islands and to establish whether the latter are the result of island coalescence. AU - Rastelli, Armando AU - Stoffel, Mathieu AU - Georgios Katsaros AU - Tersoff, Jerry AU - Denker, Ulrich AU - Merdzhanova, Tsvetelina AU - Kar, Gouranga S AU - Costantini, Giovanni AU - Kern, Klaus AU - Von Känel, Hans AU - Schmidt, Oliver G ID - 1747 IS - 12 JF - Microelectronics Journal TI - Reading the footprints of strained islands VL - 37 ER - TY - JOUR AB - A microscopic picture for the GaAs overgrowth of self-organized InAs/GaAs(001) quantum dots is developed. Scanning tunneling microscopy measurements reveal two capping regimes: the first being characterized by a dot shrinking and a backward pyramid-to-dome shape transition. This regime is governed by fast dynamics resulting in island morphologies close to thermodynamic equilibrium. The second regime is marked by a true overgrowth and is controlled by kinetically limited surface diffusion processes. A simple model is developed to describe the observed structural changes which are rationalized in terms of energetic minimization driven by lattice mismatch and alloying. AU - Costantini, Giovanni AU - Rastelli, Armando AU - Manzano, Carlos AU - Acosta-Diaz, P AU - Songmuang, Rudeeson AU - Georgios Katsaros AU - Schmidt, Oliver G AU - Kern, Klaus ID - 1746 IS - 22 JF - Physical Review Letters TI - Interplay between thermodynamics and kinetics in the capping of InAs/GaAs (001) quantum dots VL - 96 ER - TY - JOUR AB - The authors apply selective wet chemical etching and atomic force microscopy to reveal the three-dimensional shape of SiGeSi (001) islands after capping with Si. Although the "self-assembled quantum dots" remain practically unaffected by capping in the temperature range of 300-450 °C, significant morphological changes take place on the Si surface. At 450 °C, the morphology of the capping layer (Si matrix) evolves toward an intriguing semifacetted structure, which we call a "ziggurat," giving the misleading impression of a stepped SiGe island shape. AU - Georgios Katsaros AU - Rastelli, Armando AU - Stoffel, Mathieu AU - Costantini, Giovanni AU - Schmidt, Oliver G AU - Kern, Klaus AU - Tersoff, Jerry AU - Müller, Elisabeth AU - Von Känel, Hans ID - 1748 IS - 25 JF - Applied Physics Letters TI - Evolution of buried semiconductor nanostructures and origin of stepped surface mounds during capping VL - 89 ER - TY - JOUR AB - Drugs that block the entry of human immunodeficiency virus type 1 (HIV-1) into host cells abrogate the establishment of a productive infection and should ideally diminish the chances of HIV-1 developing resistance. This review will give an overview of the mechanism by which the envelope glycoprotein mediates HIV-1 entry and will summarize current drug developments. AU - Sandra Siegert AU - Schnierle, Peter AU - Schnierle, Barbara S ID - 1796 IS - 5 JF - Mini-Reviews in Medicinal Chemistry TI - Novel anti-viral therapy: Drugs that block HIV entry at different target sites VL - 6 ER - TY - JOUR AB - Respiratory complex I plays a central role in cellular energy production in bacteria and mitochondria. Its dysfunction is implicated in many human neurodegenerative diseases, as well as in aging. The crystal structure of the hydrophilic domain (peripheral arm) of complex I from Thermus thermophilus has been solved at 3.3 angstrom resolution. This subcomplex consists of eight subunits and contains all the redox centers of the enzyme, including nine iron-sulfur clusters. The primary electron acceptor, flavin-mononucleotide, is within electron transfer distance of cluster N3, leading to the main redox pathway, and of the distal cluster Nia, a possible antioxidant. The structure reveals new aspects of the mechanism and evolution of the enzyme. The terminal cluster N2 is coordinated, uniquely, by two consecutive cysteines. The novel subunit Nqo15 has a similar fold to the mitochondrial iron chaperone frataxin, and it may be involved in iron-sulfur cluster regeneration in the complex. AU - Leonid Sazanov AU - Hinchliffe, Philip ID - 1961 IS - 5766 JF - Science TI - Structure of the hydrophilic domain of respiratory complex I from Thermus thermophilus VL - 311 ER - TY - JOUR AB - The hydrophilic domain (peripheral arm) of the proton-translocating NADH:quinone oxidoreductase (complex I) from the thermophilic organism Thermus thermophilus HB8 has been purified and characterized. The subcomplex is stable in sodium dodecyl sulfate up to 80 °C. Of nine iron-sulfur clusters, four to five (one or two binuclear and three tetranuclear) could be detected by EPR in the NADH-reduced enzyme. The preparation consists of eight different polypeptides. Seven of them have been positively identified by peptide mass mapping and N-terminal sequencing as known hydrophilic subunits of T. thermophilus complex I. The eighth polypeptide copurified with the subcomplex at all stages, is strongly associated with the other subunits, and is present in crystals of the subcomplex, used for X-ray data collection. Therefore, it has been identified as a novel complex I subunit and named Nqo15. It is encoded in a locus separate from the nqo operon, containing the 14 other known complex I genes. ORFs encoding Nqo15 homologues are present in the genomes of the closest relatives of T. thermophilus. Our data show that, contrary to previous assumptions, bacterial complex I can contain proteins in addition to a "core" complement of 14 subunits. AU - Hinchliffe, Philip AU - Carroll, Joe D AU - Leonid Sazanov ID - 1966 IS - 14 JF - Biochemistry TI - Identification of a novel subunit of respiratory complex I from Thermus thermophilus VL - 45 ER - TY - JOUR AB - Although the X chromosome is usually similar to the autosomes in size and cytogenetic appearance, theoretical models predict that its hemizygosity in males may cause unusual patterns of evolution. The sequencing of several genomes has indeed revealed differences between the X chromosome and the autosomes in the rates of gene divergence, patterns of gene expression and rates of gene movement between chromosomes. A better understanding of these patterns should provide valuable information on the evolution of genes located on the X chromosome. It could also suggest solutions to more general problems in molecular evolution, such as detecting selection and estimating mutational effects on fitness AU - Beatriz Vicoso AU - Charlesworth, Brian ID - 2066 IS - 8 JF - Nature Reviews Genetics TI - Evolution on the X chromosome: Unusual patterns and processes VL - 7 ER - TY - CONF AB - We present an adaptive animation method for electrical discharges. Electrical discharges can be simulated using the dielectric breakdown model. Regular discretization of the governing Laplace equation leads to huge equation systems, and the computational cost of solving the equations quickly becomes prohibitive at high resolutions, especially for simulations in 3D. In contrast, our method discretizes the Laplace equation on an adaptive octree, reducing the size of the problem significantly, and making simulations of high resolution 3D datasets and even 3D animations feasible. In order to enhance realism for lightning animations, we propose a particle simulation that animates the residual positive charge. Thus, interaction of electrical discharges with their surroundings can be simulated. AU - Bernd Bickel AU - Wicke, Martin AU - Gross, Markus ID - 2077 TI - Adaptive simulation of electrical discharges ER - TY - JOUR AB - We have measured 3D face geometry, skin reflectance, and subsurface scattering using custom-built devices for 149 subjects of varying age, gender, and race. We developed a novel skin reflectance model whose parameters can be estimated from measurements. The model decomposes the large amount of measured skin data into a spatially-varying analytic BRDF, a diffuse albedo map, and diffuse subsurface scattering. Our model is intuitive, physically plausible, and - since we do not use the original measured data - easy to edit as well. High-quality renderings come close to reproducing real photographs. The analysis of the model parameters for our sample population reveals variations according to subject age, gender, skin type, and external factors (e.g., sweat, cold, or makeup). Using our statistics, a user can edit the overall appearance of a face (e.g., changing skin type and age) or change small-scale features using texture synthesis (e.g., adding moles and freckles). We are making the collected statistics publicly available to the research community for applications in face synthesis and analysis. AU - Weyrich, Tim AU - Matusik, Wojciech AU - Pfister, Hanspeter AU - Bernd Bickel AU - Donner, Craig AU - Tu, Chien AU - McAndless, Janet M AU - Lee, Jinho AU - Ngan, Addy AU - Jensen, Henrik W AU - Groß, Markus S ID - 2089 IS - 3 JF - ACM Transactions on Graphics TI - Analysis of human faces using a measurement-based skin reflectance model VL - 25 ER - TY - CONF AB - We have measured 3D face geometry, skin reflectance, and subsurface scattering using custom-built devices for 149 subjects of varying age, gender, and race. We developed a novel skin reflectance model whose parameters can be estimated from measurements. The model decomposes the large amount of measured skin data into a spatially-varying analytic BRDF, a diffuse albedo map, and diffuse subsurface scattering. Our model is intuitive, physically plausible, and - since we do not use the original measured data - easy to edit as well. High-quality renderings come close to reproducing real photographs. The analysis of the model parameters for our sample population reveals variations according to subject age, gender, skin type, and external factors (e.g., sweat, cold, or makeup). Using our statistics, a user can edit the overall appearance of a face (e.g., changing skin type and age) or change small-scale features using texture synthesis (e.g., adding moles and freckles). We are making the collected statistics publicly available to the research community for applications in face synthesis and analysis. AU - Weyrich, Tim AU - Matusik, Wojciech AU - Pfister, Hanspeter AU - Bernd Bickel AU - Donner, Craig AU - Tu, Chien AU - McAndless, Janet M AU - Lee, Jinho AU - Ngan, Addy AU - Jensen, Henrik W AU - Groß, Markus S ID - 2088 TI - Analysis of human faces using a measurement-based skin reflectance model ER -