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    Self-organized stress patterns drive state transitions in actin cortices 

    Tan, Tzer Han; Malik-Garbi, Maya; Abu-Shah, Enas; Li, Junang; Sharma, Abhinav; MacKintosh, Fred C.; Keren, Kinneret; Schmidt, Christoph F.; Fakhri, Nikta
    Science Advances 2018; 4(6): Art. eaar2847
    Biological functions rely on ordered structures and intricately controlled collective dynamics. This order in living systems is typically established and sustained by continuous dissipation of energy. The emergence of collective patterns of motion is unique to nonequilibrium systems and is a manifestation of dynamic steady states. Mechanical resilience of animal cells is largely controlled by the actomyosin cortex. The cortex provides stability but is, at the same time, highly adaptable due to rapid turnover of its components. Dynamic functions involve regulated transitions between different steady states of the cortex. We find that model actomyosin cortices, constructed to maintain turnover, self-organize into distinct nonequilibrium steady states when we vary cross-link density. The feedback between actin network structure and organization of stress-generating myosin motors defines the symmetries of the dynamic steady states. A marginally cross-linked state displays divergence-free long-range flow patterns. Higher cross-link density causes structural symmetry breaking, resulting in a stationary converging flow pattern. We track the flow patterns in the model actomyosin cortices using fluorescent single-walled carbon nanotubes as novel probes. The self-organization of stress patterns we have observed in a model system can have direct implications for biological functions.
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    CAMP@FLASH: an end-station for imaging, electron- and ion-spectroscopy, and pump–probe experiments at the FLASH free-electron laser 

    Erk, Benjamin; Müller, Jan P.; Bomme, Cédric; Boll, Rebecca; Brenner, Günter; Chapman, Henry N.; Correa, Jonathan; Düsterer, Stefan; Dziarzhytski, Siarhei; Eisebitt, Stefan; et al.
    Graafsma, HeinzGrunewald, SörenGumprecht, LarsHartmann, RobertHauser, GünterKeitel, Barbaravon Korff Schmising, ClemensKuhlmann, MarionManschwetus, BastianMercadier, LaurentMüller, ErlandPassow, ChristopherPlönjes, ElkeRamm, DanielRompotis, DimitriosRudenko, ArtemRupp, DanielaSauppe, MarioSiewert, FrankSchlosser, DieterStrüder, LotharSwiderski, AngadTechert, SimoneTiedtke, KaiTilp, ThomasTreusch, RolfSchlichting, IlmeUllrich, JoachimMoshammer, RobertMöller, ThomasRolles, Daniel
    Journal of Synchrotron Radiation 2018; 25(5) p.1529-1540
    The non-monochromatic beamline BL1 at the FLASH free-electron laser facility at DESY was upgraded with new transport and focusing optics, and a new permanent end-station, CAMP, was installed. This multi-purpose instrument is optimized for electron- and ion-spectroscopy, imaging and pump–probe experiments at free-electron lasers. It can be equipped with various electronand ion-spectrometers, along with large-area single-photon-counting pnCCD X-ray detectors, thus enabling a wide range of experiments from atomic, molecular, and cluster physics to material and energy science, chemistry and biology. Here, an overview of the layout, the beam transport and focusing capabilities, and the experimental possibilities of this new end-station are presented, as well as results from its commissioning.
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    Viscoelastic properties of vimentin originate from nonequilibrium conformational changes 

    Block, Johanna; Witt, Hannes; Candelli, Andrea; Danes, Jordi Cabanas; Peterman, Erwin J. G.; Wuite, Gijs J. L.; Janshoff, Andreas; Köster, Sarah
    Science Advances 2018; 4(6): Art. eaat1161
    Structure and dynamics of living matter rely on design principles fundamentally different from concepts of traditional material science. Specialized intracellular filaments in the cytoskeleton permit living systems to divide, migrate, and growwith a high degree of variability and durability. Among the three filament systems,microfilaments,microtubules, and intermediate filaments (IFs), the physical properties of IFs and their role in cellular mechanics are the least well understood. We use optical trapping of individual vimentin filaments to investigate energy dissipation, strain history dependence, and creep behavior of stretched filaments. By stochastic and numerical modeling, we link our experimental observations to the peculiar molecular architecture of IFs. We find that individual vimentin filaments display tensile memory and are able to dissipate more than 70% of the input energy.We attribute these phenomena to distinct nonequilibrium folding and unfolding of a helices in the vimentin monomers constituting the filaments.
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    Correlative microscopy approach for biology using X-ray holography, X-ray scanning diffraction and STED microscopy 

    Bernhardt, M.; Nicolas, J.-D.; Osterhoff, M.; Mittelstädt, H.; Reuss, M.; Harke, B.; Wittmeier, A.; Sprung, M.; Köster, S.; Salditt, T.
    Nature Communications 2018; 9(1): Art. 3641
    We present a correlative microscopy approach for biology based on holographic X-ray imaging, X-ray scanning diffraction, and stimulated emission depletion (STED) microscopy. All modalities are combined into the same synchrotron endstation. In this way, labeled and unlabeled structures in cells are visualized in a complementary manner. We map out the fluorescently labeled actin cytoskeleton in heart tissue cells and superimpose the data with phase maps from X-ray holography. Furthermore, an array of local far-field diffraction patterns is recorded in the regime of small-angle X-ray scattering (scanning SAXS), which can be interpreted in terms of biomolecular shape and spatial correlations of all contributing scattering constituents. We find that principal directions of anisotropic diffraction patterns coincide to a certain degree with the actin fiber directions and that actin stands out in the phase maps from holographic recordings. In situ STED recordings are proposed to formulate models for diffraction data based on co-localization constraints
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    Disentangling Transient Charge Density and Metal-Ligand Covalency in Photoexcited Ferricyanide with Femtosecond Resonant Inelastic Soft X-ray Scattering. 

    Jay, Raphael M.; Norell, Jesper; Eckert, Sebastian; Hantschmann, Markus; Beye, Martin; Kennedy, Brian; Quevedo, Wilson; Schlotter, William F.; Dakovski, Georgi L.; Minitti, Michael P.; et al.
    Hoffmann, Matthias C.Mitra, AnkushMoeller, Stefan P.Nordlund, DennisZhang, WenkaiLiang, Huiyang W.Kunnus, KristjanKubiček, KatharinaTechert, Simone A.Lundberg, MarcusWernet, PhilippeGaffney, KellyOdelius, MichaelFöhlisch, Alexander
    The Journal of Physical Chemistry Letters 2018; 9(12) p.3538-3543
    Soft X-ray spectroscopies are ideal probes of the local valence electronic structure of photocatalytically active metal sites. Here, we apply the selectivity of time-resolved resonant inelastic X-ray scattering at the iron L-edge to the transient charge distribution of an optically excited charge-transfer state in aqueous ferricyanide. Through comparison to steady-state spectra and quantum chemical calculations, the coupled effects of valence-shell closing and ligand-hole creation are experimentally and theoretically disentangled and described in terms of orbital occupancy, metal-ligand covalency, and ligand field splitting, thereby extending established steady-state concepts to the excited-state domain. π-Back-donation is found to be mainly determined by the metal site occupation, whereas the ligand hole instead influences σ-donation. Our results demonstrate how ultrafast resonant inelastic X-ray scattering can help characterize local charge distributions around catalytic metal centers in short-lived charge-transfer excited states, as a step toward future rationalization and tailoring of photocatalytic capabilities of transition-metal complexes.
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    Assigning crystallographic electron densities with free energy calculations-The case of the fluoride channel Fluc. 

    Ariz-Extreme, Igor; Hub, Jochen S.
    PLOS ONE 2018; 13(5): Art. e0196751
    Approximately 90% of the structures in the Protein Data Bank (PDB) were obtained by X-ray crystallography or electron microscopy. Whereas the overall quality of structure is considered high, thanks to a wide range of tools for structure validation, uncertainties may arise from density maps of small molecules, such as organic ligands, ions or water, which are non-covalently bound to the biomolecules. Even with some experience and chemical intuition, the assignment of such disconnected electron densities is often far from obvious. In this study, we suggest the use of molecular dynamics (MD) simulations and free energy calculations, which are well-established computational methods, to aid in the assignment of ambiguous disconnected electron densities. Specifically, estimates of (i) relative binding affinities, for instance between an ion and water, (ii) absolute binding free energies, i.e., free energies for transferring a solute from bulk solvent to a binding site, and (iii) stability assessments during equilibrium simulations may reveal the most plausible assignments. We illustrate this strategy using the crystal structure of the fluoride specific channel (Fluc), which contains five disconnected electron densities previously interpreted as four fluoride and one sodium ion. The simulations support the assignment of the sodium ion. In contrast, calculations of relative and absolute binding free energies as well as stability assessments during free MD simulations suggest that four of the densities represent water molecules instead of fluoride. The assignment of water is compatible with the loss of these densities in the non-conductive F82I/F85I mutant of Fluc. We critically discuss the role of the ion force fields for the calculations presented here. Overall, these findings indicate that MD simulations and free energy calculations are helpful tools for modeling water and ions into crystallographic density maps.
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    Modular Neural Mechanisms for Gait Phase Tracking, Prediction, and Selection in Personalizable Knee-Ankle-Foot-Orthoses 

    Braun, Jan-Matthias; Wörgötter, Florentin; Manoonpong, Poramate
    Frontiers in Neurorobotics 2018; 12: Art. 37
    Orthoses for the lower limbs support patients to perform movements that they could not perform on their own. In traditional devices, generic gait models for a limited set of supportedmovements restrict the patientsmobility and device acceptance. To overcome such limitations, we propose a modular neural control approach with user feedback for personalizable Knee-Ankle-Foot-Orthoses (KAFO). The modular controller consists of two main neural components: neural orthosis control for gait phase tracking and neural internal models for gait prediction and selection. A user interface providing online feedback allows the user to shape the control output that adjusts the knee damping parameter of a KAFO. The accuracy and robustness of the control approach were investigated in different conditions including walking on flat ground and descending stairs as well as stair climbing. We show that the controller accurately tracks and predicts the user’s movements and generates corresponding gaits. Furthermore, based on the modular control architecture, the controller can be extended to support various distinguishable gaits depending on differences in sensory feedback.
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    Time- and frequency-resolved fluorescence with a single TCSPC detector via a Fourier-transform approach 

    Perri, Antonio; Gaida, John H.; Farina, Andrea; Preda, Fabrizio; Viola, Daniele; Ballottari, Matteo; Hauer, Jürgen; De Silvestri, Sandro; D’Andrea, Cosimo; Cerullo, Giulio; et al.
    Polli, Dario
    Optics Express 2018; 26(3): Art. 2270
    We introduce a broadband single-pixel spectro-temporal fluorescence detector, combining time-correlated single photon counting (TCSPC) with Fourier transform (FT) spectroscopy. A birefringent common-path interferometer (CPI) generates two time-delayed replicas of the sample's fluorescence. Via FT of their interference signal at the detector, we obtain a two-dimensional map of the fluorescence as a function of detection wavelength and emission time, with high temporal and spectral resolution. Our instrument is remarkably simple, as it only requires the addition of a CPI to a standard single-pixel TCSPC system, and it shows a readily adjustable spectral resolution with inherently broad bandwidth coverage.
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    Topology determines force distributions in one-dimensional random spring networks 

    Heidemann, Knut M.; Sageman-Furnas, Andrew O.; Sharma, Abhinav; Rehfeldt, Florian; Schmidt, Christoph F.; Wardetzky, Max
    Physical Review E 2018; 97(2): Art. 022306
    etworks of elastic fibers are ubiquitous in biological systems and often provide mechanical stability to cells and tissues. Fiber-reinforced materials are also common in technology. An important characteristic of such materials is their resistance to failure under load. Rupture occurs when fibers break under excessive force and when that failure propagates. Therefore, it is crucial to understand force distributions. Force distributions within such networks are typically highly inhomogeneous and are not well understood. Here we construct a simple one-dimensional model system with periodic boundary conditions by randomly placing linear springs on a circle. We consider ensembles of such networks that consist of N nodes and have an average degree of connectivity z but vary in topology. Using a graph-theoretical approach that accounts for the full topology of each network in the ensemble, we show that, surprisingly, the force distributions can be fully characterized in terms of the parameters (N,z). Despite the universal properties of such (N,z) ensembles, our analysis further reveals that a classical mean-field approach fails to capture force distributions correctly. We demonstrate that network topology is a crucial determinant of force distributions in elastic spring networks.
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    Combined Forward-Backward Asymmetry Measurements in Top-Antitop Quark Production at the Tevatron 

    Aaltonen, T.; Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Agnew, J. P.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; et al.
    Amerio, S.Amidei, D.Anastassov, A.Annovi, A.Antos, J.Apollinari, G.Appel, J. A.Arisawa, T.Artikov, A.Asaadi, J.Ashmanskas, W.Askew, A.Atkins, S.Auerbach, B.Augsten, K.Aurisano, A.Aushev, V.Aushev, Y.Avila, C.Azfar, F.Badaud, F.Badgett, W.Bae, T.Bagby, L.Baldin, B.Bandurin, D. V.Banerjee, S.Barbaro-Galtieri, A.Barberis, E.Baringer, P.Barnes, V. E.Barnett, B. A.Barria, P.Bartlett, J. F.Bartos, P.Bassler, U.Bauce, M.Bazterra, V.Bean, A.Bedeschi, F.Begalli, M.Behari, S.Bellantoni, L.Bellettini, G.Bellinger, J.Benjamin, D.Beretvas, A.Beri, S. B.Bernardi, G.Bernhard, R.Bertram, I.Besançon, M.Beuselinck, R.Bhat, P. C.Bhatia, S.Bhatnagar, V.Bhatti, A.Bland, K. R.Blazey, G.Blessing, S.Bloom, K.Blumenfeld, B.Bocci, A.Bodek, A.Boehnlein, A.Boline, D.Boos, E. E.Borissov, G.Bortoletto, D.Borysova, M.Boudreau, J.Boveia, A.Brandt, A.Brandt, O.Brigliadori, L.Brochmann, M.Brock, R.Bromberg, C.Bross, A.Brown, D.Brucken, E.Bu, X. B.Budagov, J.Budd, H. S.Buehler, M.Buescher, V.Bunichev, V.Burdin, S.Burkett, K.Busetto, G.Bussey, P.Buszello, C. P.Butti, P.Buzatu, A.Calamba, A.Camacho-Pérez, E.Camarda, S.Campanelli, M.Canelli, F.Carls, B.Carlsmith, D.Carosi, R.Carrillo, S.Casal, B.Casarsa, M.Casey, B. C. K.Castilla-Valdez, H.Castro, A.Catastini, P.Caughron, S.Cauz, D.Cavaliere, V.Cerri, A.Cerrito, L.Chakrabarti, S.Chan, K. M.Chandra, A.Chapelain, A.Chapon, E.Chen, G.Chen, Y. C.Chertok, M.Chiarelli, G.Chlachidze, G.Cho, K.Cho, S. W.Choi, S.Chokheli, D.Choudhary, B.Cihangir, S.Claes, D.Clark, A.Clarke, C.Clutter, J.Convery, M. E.Conway, J.Cooke, M.Cooper, W. E.Corbo, M.Corcoran, M.Cordelli, M.Couderc, F.Cousinou, M.-C.Cox, C. A.Cox, D. J.Cremonesi, M.Cruz, D.Cuevas, J.Culbertson, R.Cuth, J.Cutts, D.Das, A.d'Ascenzo, N.Datta, M.Davies, G.de Barbaro, P.de Jong, S. J.De La Cruz-Burelo, E.Déliot, F.Demina, R.Demortier, L.Deninno, M.Denisov, D.Denisov, S. P.D'Errico, M.Desai, S.Deterre, C.DeVaughan, K.Devoto, F.Di Canto, A.Di Ruzza, B.Diehl, H. T.Diesburg, M.Ding, P. F.Dittmann, J. R.Dominguez, A.Donati, S.D'Onofrio, M.Dorigo, M.Driutti, A.Drutskoy, A.Dubey, A.Dudko, L. V.Duperrin, A.Dutt, S.Eads, M.Ebina, K.Edgar, R.Edmunds, D.Elagin, A.Ellison, J.Elvira, V. D.Enari, Y.Erbacher, R.Errede, S.Esham, B.Evans, H.Evdokimov, A.Evdokimov, V. N.Farrington, S.Fauré, A.Feng, L.Ferbel, T.Fernández Ramos, J. P.Fiedler, F.Field, R.Filthaut, F.Fisher, W.Fisk, H. E.Flanagan, G.Forrest, R.Fortner, M.Fox, H.Franc, J.Franklin, M.Freeman, J. C.Frisch, H.Fuess, S.Funakoshi, Y.Galloni, C.Garbincius, P. H.Garcia-Bellido, A.García-González, J. A.Garfinkel, A. F.Garosi, P.Gavrilov, V.Geng, W.Gerber, C. E.Gerberich, H.Gerchtein, E.Gershtein, Y.Giagu, S.Giakoumopoulou, V.Gibson, K.Ginsburg, C. M.Ginther, G.Giokaris, N.Giromini, P.Glagolev, V.Glenzinski, D.Gogota, O.Gold, M.Goldin, D.Golossanov, A.Golovanov, G.Gomez, G.Gomez-Ceballos, G.Goncharov, M.González López, O.Gorelov, I.Goshaw, A. T.Goulianos, K.Gramellini, E.Grannis, P. D.Greder, S.Greenlee, H.Grenier, G.Gris, Ph.Grivaz, J.-F.Grohsjean, A.Grosso-Pilcher, C.Grünendahl, S.Grünewald, M. W.Guillemin, T.Guimaraes da Costa, J.Gutierrez, G.Gutierrez, P.Hahn, S. R.Haley, J.Han, J. Y.Han, L.Happacher, F.Hara, K.Harder, K.Hare, M.Harel, A.Harr, R. F.Harrington-Taber, T.Hatakeyama, K.Hauptman, J. M.Hays, C.Hays, J.Head, T.Hebbeker, T.Hedin, D.Hegab, H.Heinrich, J.Heinson, A. P.Heintz, U.Hensel, C.Heredia-De La Cruz, I.Herndon, M.Herner, K.Hesketh, G.Hildreth, M. D.Hirosky, R.Hoang, T.Hobbs, J. D.Hocker, A.Hoeneisen, B.Hogan, J.Hohlfeld, M.Holzbauer, J. L.Hong, Z.Hopkins, W.Hou, SHowley, I.Hubacek, Z.Hughes, R. E.Husemann, U.Hussein, M.Huston, J.Hynek, V.Iashvili, I.Ilchenko, Y.Illingworth, R.Introzzi, G.Iori, M.Ito, A. S.Ivanov, A.Jabeen, S.Jaffré, M.James, E.Jang, D.Jayasinghe, A.Jayatilaka, B.Jeon, E. J.Jeong, M. S.Jesik, R.Jiang, P.Jindariani, S.Johns, K.Johnson, E.Johnson, M.Jonckheere, A.Jones, M.Jonsson, P.Joo, K. K.Joshi, J.Jun, S. Y.Jung, A. W.Junk, T. R.Juste, A.Kajfasz, E.Kambeitz, M.Kamon, T.Karchin, P. E.Karmanov, D.Kasmi, A.Kato, Y.Katsanos, I.Kaur, M.Kehoe, R.Kermiche, S.Ketchum, W.Keung, J.Khalatyan, N.Khanov, A.Kharchilava, A.Kharzheev, Y. N.Kilminster, B.Kim, D. H.Kim, H. S.Kim, J. E.Kim, M. J.Kim, S. H.Kim, S. B.Kim, Y. J.Kim, Y. K.Kimura, N.Kirby, M.Kiselevich, I.Kohli, J. M.Kondo, K.Kong, D. J.Konigsberg, J.Kotwal, A. V.Kozelov, A. V.Kraus, J.Kreps, M.Kroll, J.Kruse, M.Kuhr, T.Kumar, A.Kupco, A.Kurata, M.Kurča, T.Kuzmin, V. A.Laasanen, A. T.Lammel, S.Lammers, S.Lancaster, M.Lannon, K.Latino, G.Lebrun, P.Lee, H. S.Lee, H. S.Lee, J. S.Lee, S. W.Lee, W. M.Lei, X.Lellouch, J.Leo, S.Leone, S.Lewis, J. D.Li, D.Li, H.Li, L.Li, Q. Z.Lim, J. K.Limosani, A.Lincoln, D.Linnemann, J.Lipaev, V. V.Lipeles, E.Lipton, R.Lister, A.Liu, H.Liu, Q.Liu, T.Liu, Y.Lobodenko, A.Lockwitz, S.Loginov, A.Lokajicek, M.Lopes de Sa, R.Lucchesi, D.Lucà, A.Lueck, J.Lujan, P.Lukens, P.Luna-Garcia, R.Lungu, G.Lyon, A. L.Lys, J.Lysak, R.Maciel, A. K. A.Madar, R.Madrak, R.Maestro, P.Magaña-Villalba, R.Malik, S.Malik, S.Malyshev, V. L.Manca, G.Manousakis-Katsikakis, A.Mansour, J.Marchese, L.Margaroli, F.Marino, P.Martínez-Ortega, J.Matera, K.Mattson, M. E.Mazzacane, A.Mazzanti, P.McCarthy, R.McGivern, C. L.McNulty, R.Mehta, A.Mehtala, P.Meijer, M. M.Melnitchouk, A.Menezes, D.Mercadante, P. G.Merkin, M.Mesropian, C.Meyer, A.Meyer, J.Miao, T.Miconi, F.Mietlicki, D.Mitra, A.Miyake, H.Moed, S.Moggi, N.Mondal, N. K.Moon, C. S.Moore, R.Morello, M. J.Mukherjee, A.Mulhearn, M.Muller, Th.Murat, P.Mussini, M.Nachtman, J.Nagai, Y.Naganoma, J.Nagy, E.Nakano, I.Napier, A.Narain, M.Nayyar, R.Neal, H. A.Negret, J. P.Nett, J.Neustroev, P.Nguyen, H. T.Nigmanov, T.Nodulman, L.Noh, S. Y.Norniella, O.Nunnemann, T.Oakes, L.Oh, S. H.Oh, Y. D.Okusawa, T.Orava, R.Orduna, J.Ortolan, L.Osman, N.Pagliarone, C.Pal, A.Palencia, E.Palni, P.Papadimitriou, V.Parashar, N.Parihar, V.Park, S. K.Parker, W.Partridge, R.Parua, N.Patwa, A.Pauletta, G.Paulini, M.Paus, C.Penning, B.Perfilov, M.Peters, Y.Petridis, K.Petrillo, G.Pétroff, P.Phillips, T. J.Piacentino, G.Pianori, E.Pilot, J.Pitts, K.Plager, C.Pleier, M.-A.Podstavkov, V. M.Pondrom, L.Popov, A. V.Poprocki, S.Potamianos, K.Pranko, A.Prewitt, M.Price, D.Prokopenko, N.Prokoshin, F.Ptohos, F.Punzi, G.Qian, J.Quadt, A.Quinn, B.Ratoff, P. N.Razumov, I.Redondo Fernández, I.Renton, P.Rescigno, M.Rimondi, F.Ripp-Baudot, I.Ristori, L.Rizatdinova, F.Robson, A.Rodriguez, T.Rolli, S.Rominsky, M.Ronzani, M.Roser, R.Rosner, J. L.Ross, A.Royon, C.Rubinov, P.Ruchti, R.Ruffini, F.Ruiz, A.Russ, J.Rusu, V.Sajot, G.Sakumoto, W. K.Sakurai, Y.Sánchez-Hernández, A.Sanders, M. P.Santi, L.Santos, A. S.Sato, K.Savage, G.Saveliev, V.Savitskyi, M.Savoy-Navarro, A.Sawyer, L.Scanlon, T.Schamberger, R. D.Scheglov, Y.Schellman, H.Schlabach, P.Schmidt, E. E.Schott, M.Schwanenberger, C.Schwarz, T.Schwienhorst, R.Scodellaro, L.Scuri, F.Seidel, S.Seiya, Y.Sekaric, J.Semenov, A.Severini, HSforza, F.Shabalina, E.Shalhout, S. Z.Shary, V.Shaw, S.Shchukin, A. A.Shears, T.Shepard, P. F.Shimojima, M.Shkola, O.Shochet, M.Shreyber-Tecker, I.Simak, V.Simonenko, A.Skubic, P.Slattery, P.Sliwa, K.Smith, J. R.Snider, .F D.Snow, G. R.Snow, J.Snyder, S.Söldner-Rembold, S.Song, H.Sonnenschein, L.Sorin, V.Soustruznik, K.St Denis, R.Stancari, M.Stark, J.Stefaniuk, N.Stentz, D.Stoyanova, D. A.Strauss, M.Strologas, J.Sudo, Y.Sukhanov, A.Suslov, I.Suter, L.Svoisky, P.Takemasa, K.Takeuchi, Y.Tang, J.Tecchio, M.Teng, P. K.Thom, J.Thomson, E.Thukral, V.Titov, M.Toback, D.Tokar, S.Tokmenin, V. V.Tollefson, K.Tomura, T.Tonelli, D.Torre, S.Torretta, D.Totaro, P.Trovato, M.Tsai, Y.-T.Tsybychev, D.Tuchming, B.Tully, C.Ukegawa, F.Uozumi, S.Uvarov, L.Uvarov, S.Uzunyan, S.Van Kooten, R.van Leeuwen, W. M.Varelas, N.Varnes, E. W.Vasilyev, I. A.Vázquez, F.Velev, G.Vellidis, C.Verkheev, A. Y.Vernieri, C.Vertogradov, L. S.Verzocchi, M.Vesterinen, M.Vidal, M.Vilanova, D.Vilar, R.Vizán, J.Vogel, M.Vokac, P.Volpi, G.Wagner, P.Wahl, H. D.Wallny, R.Wang, M. H. L. S.Wang, S. M.Warchol, J.Waters, D.Watts, G.Wayne, M.Weichert, J.Welty-Rieger, L.Wester, W. C.Whiteson, D.Wicklund, A. B.Wilbur, S.Williams, H. H.Williams, M. R. J.Wilson, G. W.Wilson, J. S.Wilson, P.Winer, B. L.Wittich, P.Wobisch, M.Wolbers, S.Wolfmeister, H.Wood, D. R.Wright, T.Wu, X.Wu, Z.Wyatt, T. R.Xie, Y.Yamada, R.Yamamoto, K.Yamato, D.Yang, S.Yang, T.Yang, U. K.Yang, Y. C.Yao, W.-M.Yasuda, T.Yatsunenko, Y. A.Ye, W.Ye, Z.Yeh, G. P.Yi, K.Yin, H.Yip, K.Yoh, J.Yorita, K.Yoshida, T.Youn, S. W.Yu, G. B.Yu, I.Yu, J. M.Zanetti, A. M.Zeng, Y.Zennamo, J.Zhao, T. G.Zhou, B.Zhou, C.Zhu, J.Zielinski, M.Zieminska, D.Zivkovic, L.Zucchelli, S.
    Physical Review Retters 2018; 120(4): Art. 042001
    The CDF and D0 experiments at the Fermilab Tevatron have measured the asymmetry between yields of forward- and backward-produced top and antitop quarks based on their rapidity difference and the asymmetry between their decay leptons. These measurements use the full data sets collected in proton-antiproton collisions at a center-of-mass energy of sqrt[s]=1.96  TeV. We report the results of combinations of the inclusive asymmetries and their differential dependencies on relevant kinematic quantities. The combined inclusive asymmetry is A_{FB}^{tt[over ¯]}=0.128±0.025. The combined inclusive and differential asymmetries are consistent with recent standard model predictions.
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    Photodissociation of aligned CH3I and C6H3F2I molecules probed with time-resolved Coulomb explosion imaging by site-selective extreme ultraviolet ionization. 

    Amini, Kasra; Savelyev, Evgeny; Brauße, Felix; Berrah, Nora; Bomme, Cédric; Brouard, Mark; Burt, Michael; Christensen, Lauge; Düsterer, Stefan; Erk, Benjamin; et al.
    Höppner, HaukeKierspel, ThomasKrecinic, FarukLauer, AlexandraLee, Jason W. L.Müller, MariaMüller, ErlandMullins, TerenceRedlin, HaraldSchirmel, NoraThøgersen, JanTechert, SimoneToleikis, SvenTreusch, RolfTrippel, SebastianUlmer, AnatoliVallance, ClaireWiese, JossJohnsson, PerKüpper, JochenRudenko, ArtemRouzée, ArnaudStapelfeldt, HenrikRolles, DanielBoll, Rebecca
    Structural Dynamics 2018; 5(1): Art. 014301
    We explore time-resolved Coulomb explosion induced by intense, extreme ultraviolet (XUV) femtosecond pulses from a free-electron laser as a method to image photo-induced molecular dynamics in two molecules, iodomethane and 2,6-difluoroiodobenzene. At an excitation wavelength of 267 nm, the dominant reaction pathway in both molecules is neutral dissociation via cleavage of the carbon-iodine bond. This allows investigating the influence of the molecular environment on the absorption of an intense, femtosecond XUV pulse and the subsequent Coulomb explosion process. We find that the XUV probe pulse induces local inner-shell ionization of atomic iodine in dissociating iodomethane, in contrast to non-selective ionization of all photofragments in difluoroiodobenzene. The results reveal evidence of electron transfer from methyl and phenyl moieties to a multiply charged iodine ion. In addition, indications for ultrafast charge rearrangement on the phenyl radical are found, suggesting that time-resolved Coulomb explosion imaging is sensitive to the localization of charge in extended molecules.
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    Constraining scalar resonances with top-quark pair production at the LHC 

    Franzosi, Diogo Buarque; Fabbri, Federica; Schumann, Steffen
    Journal of High Energy Physics 2018; 2018(3): Art. 22
    Constraints on models which predict resonant top-quark pair production at the LHC are provided via a reinterpretation of the Standard Model (SM) particle level measurement of the top-anti-top invariant mass distribution, m(t t). We make use of stateof- the-art Monte Carlo event simulation to perform a direct comparison with measurements of m(t t) in the semi-leptonic channels, considering both the boosted and the resolved regime of the hadronic top decays. A simpli ed model to describe various scalar resonances decaying into top-quarks is considered, including CP-even and CP-odd, color-singlet and color-octet states, and the excluded regions in the respective parameter spaces are provided.
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    An ensemble framework for time delay synchronization 

    Pinheiro, Flavia R.; van Leeuwen, Peter Jan; Parlitz, Ulrich
    Quarterly Journal of the Royal Meteorological Society 2018; 144(711) p.305-316
    Synchronization based state estimation tries to synchronize a model with the true evolution of a system via the observations. In practice, an extra term is added to the model equations which hampers growth of instabilities transversal to the synchronization manifold. Therefore, there is a very close connection between synchronization and data assimilation. Recently, synchronization with time-delayed observations has been proposed, in which observations at future times are used to help synchronize a system that does not synchronize using only present observations, with remarkable successes. Unfortunately, these schemes are limited to small-dimensional problems. In this article, we lift that restriction by proposing an ensemble-based synchronization scheme. Tests were performed using the Lorenz’96 model for 20-, 100- and 1000-dimension systems. Results show global synchronization errors stabilizing at values of at least an order of magnitude lower than the observation errors, suggesting that the scheme is a promising tool to steer model states to the truth. While this framework is not a complete data assimilation method, we develop this methodology as a potential choice for a proposal density in a more comprehensive data assimilation method, like a fully nonlinear particle filter.
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    Partially composite Higgs models: phenomenology and RG analysis 

    Alanne, Tommi; Buarque Franzosi, Diogo; Frandsen, Mads T.; Kristensen, Mette L. A.; Meroni, Aurora; Rosenlyst, Martin
    Journal of High Energy Physics 2018; 2018(1): Art. 51
    Abstract: We study the phenomenology of partially composite-Higgs models where electroweak symmetry breaking is dynamically induced, and the Higgs is a mixture of a composite and an elementary state. The models considered have explicit realizations in terms of gauge-Yukawa theories with new strongly interacting fermions coupled to elementary scalars and allow for a very SM-like Higgs state. We study constraints on their parameter spaces from vacuum stability and perturbativity as well as from LHC results and nd that requiring vacuum stability up to the compositeness scale already imposes relevant constraints. A small part of parameter space around the classically conformal limit is stable up to the Planck scale. This is however already strongly disfavored by LHC results. In different limits, the models realize both (partially) composite-Higgs and (bosonic) technicolor models and a dynamical extension of the fundamental Goldstone-Higgs model. Therefore, they provide a general framework for exploring the phenomenology of composite dynamics.
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    Microfluidic device for chemical and mechanical manipulation of suspended cells 

    Rezvani, Samaneh; Shi, Nan; Squires, Todd M.; Schmidt, Christoph F.
    Journal of Physics D: Applied Physics 2018; 51(4)
    Microfluidic devices have proven to be useful and versatile for cell studies. We here report on a method to adapt microfluidic stickers made from UV-curable optical adhesive with inserted permeable hydrogel membrane micro-windows for mechanical studies of suspended cells. The windows were fabricated by optical projection lithography using scanning confocal microscopy. The device allows us to rapidly exchange embedding medium while observing and probing the cells. We characterize the device and demonstrate the function by exposing cultured fibroblasts to varying osmotic conditions. Cells can be shrunk reversibly under osmotic compression.
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    Neon ion beam induced pattern formation on amorphous carbon surfaces 

    Bobes, Omar; Hofsäss, Hans; Zhang, Kun
    AIP Advances 2018; 8(2): Art. 025205
    We investigate the ripple pattern formation on amorphous carbon surfaces at room temperature during low energy Ne ion irradiation as a function of the ion incidence angle. Monte Carlo simulations of the curvature coefficients applied to the Bradley-Harper and Cater-Vishnyakov models, including the recent extensions by Harrison-Bradley and Hofsäss predict that pattern formation on amorphous carbon thin films should be possible for low energy Ne ions from 250 eV up to 1500 eV. Moreover, simulations are able to explain the absence of pattern formation in certain cases. Our experimental results are compared with prediction using current linear theoretical models and applying the crater function formalism, as well as Monte Carlo simulations to calculate curvature coefficients using the SDTrimSP program. Calculations indicate that no patterns should be generated up to 45° incidence angle if the dynamic behavior of the thickness of the ion irradiated layer introduced by Hofsäss is taken into account, while pattern formation most pronounced from 50° for ion energy between 250 eV and 1500 eV, which are in good agreement with our experimental data.
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    Rhombic organization of microvilli domains found in a cell model of the human intestine 

    Franz, Jonas; Grünebaum, Jonas; Schäfer, Marcus; Mulac, Dennis; Rehfeldt, Florian; Langer, Klaus; Kramer, Armin; Riethmüller, Christoph
    PlOS ONE 2018; 13(1): Art. e0189970
    Symmetry is rarely found on cellular surfaces. An exception is the brush border of microvilli, which are essential for the proper function of transport epithelia. In a healthy intestine, they appear densely packed as a 2D-hexagonal lattice. For in vitro testing of intestinal transport the cell line Caco-2 has been established. As reported by electron microscopy, their microvilli arrange primarily in clusters developing secondly into a 2D-hexagonal lattice. Here, atomic force microscopy (AFM) was employed under aqueous buffer conditions on Caco-2 cells, which were cultivated on permeable filter membranes for optimum differentiation. For analysis, the exact position of each microvillus was detected by computer vision; subsequent Fourier transformation yielded the type of 2D-lattice. It was confirmed, that Caco-2 cells can build a hexagonal lattice of microvilli and form clusters. Moreover, a second type of arrangement was discovered, namely a rhombic lattice, which appeared at sub-maximal densities of microvilli with (29 ± 4) microvilli / μm2. Altogether, the findings indicate the existence of a yet undescribed pattern in cellular organization.
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    The MUSE Hubble Ultra Deep Field Survey. IV. Global properties of CIII] emitters 

    Maseda, Michael V.; Brinchmann, Jarle; Franx, Marijn; Bacon, Roland; Bouwens, Rychard J.; Schmidt, Kasper B.; Boogaard, Leindert A.; Contini, Thierry; Feltre, Anna; Inami, Hanae; et al.
    Kollatschny, WolframMarino, Raffaella A.Richard, JohanVerhamme, AnneWisotzki, Lutz
    Astronomy & Astrophysics 2017; 608 p.1-16: Art. A4
    The CIII] 1907, 1909 emission doublet has been proposed as an alternative to Lyman- in redshift confirmations of galaxies at z & 6 since it is not attenuated by the largely neutral intergalactic medium at these redshifts and is believed to be strong in the young, vigorously star-forming galaxies present at these early cosmic times. We present a statistical sample of 17 CIII]-emitting galaxies beyond z 1:5 using 30 h deep VLT/MUSE integral field spectroscopy covering 2 square arcminutes in the Hubble Deep Field South (HDFS) and Ultra Deep Field (UDF), achieving C III] sensitivities of 2 10􀀀17 erg s􀀀1 cm􀀀2 in the HDFS and 7 10􀀀18 erg s􀀀1 cm􀀀2 in the UDF. The rest-frame equivalent widths range from 2 to 19 Å. These 17 galaxies represent 3% of the total sample of galaxies found between 1:5 . z . 4. They also show elevated star formation rates, lower dust attenuation, and younger mass-weighted ages than the general population of galaxies at the same redshifts. Combined with deep slitless grism spectroscopy from the HST/WFC3 in the UDF, we can tie the rest-frame ultraviolet C III] emission to rest-frame optical emission lines, namely [O III] 5007, finding a strong correlation between the two. Down to the flux limits that we observe ( 1 10􀀀18 erg s􀀀1 cm􀀀2 with the grism data in the UDF), all objects with a rest-frame [O III] 4959, 5007 equivalent width in excess of 250 Å, the so-called extreme emission line galaxies, have detections of CIII] in our MUSE data. More detailed studies of the C III]-emitting population at these intermediate redshifts will be crucial to understand the physical conditions in galaxies at early cosmic times and to determine the utility of C III] as a redshift tracer.
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    The MUSE Hubble Ultra Deep Field Survey. II. Spectroscopic redshifts and comparisons to color selections of high-redshift galaxies 

    Inami, H.; Bacon, R.; Brinchmann, J.; Richard, J.; Contini, T.; Conseil, S.; Hamer, S.; Akhlaghi, M.; Bouché, N.; Clément, B.; et al.
    Desprez, G.Drake, A. B.Hashimoto, T.Leclercq, F.Maseda, M.Michel-Dansac, L.Paalvast, M.Tresse, L.Ventou, E.Kollatschny, W.Boogaard, L. A.Finley, H.Marino, R. A.Schaye, J.Wisotzki, L.
    Astronomy & Astrophysics 2017; 608 p.1-26: Art. A2
    We have conducted a two-layered spectroscopic survey (10 10 ultra deep and 30 30 deep regions) in the Hubble Ultra Deep Field (HUDF) with the Multi Unit Spectroscopic Explorer (MUSE). The combination of a large field of view, high sensitivity, and wide wavelength coverage provides an order of magnitude improvement in spectroscopically confirmed redshifts in the HUDF; i.e., 1206 secure spectroscopic redshifts for Hubble Space Telescope (HST) continuum selected objects, which corresponds to 15% of the total (7904). The redshift distribution extends well beyond z > 3 and to HST/F775W magnitudes as faint as 30 mag (AB, 1 ). In addition, 132 secure redshifts were obtained for sources with no HST counterparts that were discovered in the MUSE data cubes by a blind search for emission-line features. In total, we present 1338 high quality redshifts, which is a factor of eight increase compared with the previously known spectroscopic redshifts in the same field.We assessed redshifts mainly with the spectral features [O ii] at z < 1:5 (473 objects) and Ly at 2:9 < z < 6:7 (692 objects). With respect to F775W magnitude, a 50% completeness is reached at 26:5 mag for ultra deep and 25:5 mag for deep fields, and the completeness remains &20% up to 28–29 mag and 27 mag, respectively.We used the determined redshifts to test continuum color selection (dropout) diagrams of high-z galaxies. The selection condition for F336W dropouts successfully captures 80% of the targeted z 2:7 galaxies. However, for higher redshift selections (F435W, F606W, and F775W dropouts), the success rates decrease to 20–40%. We empirically redefine the selection boundaries to make an attempt to improve them to 60%. The revised boundaries allow bluer colors that capture Ly emitters with high Ly equivalent widths falling in the broadbands used for the color-color selection. Along with this paper, we release the redshift and line flux catalog.
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    The MUSE Hubble Ultra Deep Field Survey. III. Testing photometric redshifts to 30th magnitude 

    Brinchmann, J.; Inami, H.; Bacon, R.; Contini, T.; Maseda, M.; Chevallard, J.; Bouché, N.; Boogaard, L.; Carollo, M.; Charlot, S.; et al.
    Kollatschny, W.Marino, R. A.Pello, R.Richard, J.Schaye, J.Verhamme, A.Wisotzki, L.
    Astronomy & Astrophysics 2017; 608 p.1-23: Art. A3
    We tested the performance of photometric redshifts for galaxies in the Hubble Ultra Deep field down to 30th magnitude. We compared photometric redshift estimates from three spectral fitting codes from the literature (EAZY, BPZ and BEAGLE) to high quality redshifts for 1227 galaxies from the MUSE integral field spectrograph. All these codes can return photometric redshifts with bias j(zMUSE 􀀀 pz)=(1 + zMUSE)j < 0:05 down to F775W = 30 and spectroscopic incompleteness is unlikely to strongly modify this statement. We have, however, identified clear systematic biases in the determination of photometric redshifts: in the 0:4 < z < 1:5 range, photometric redshifts are systematically biased low by as much as (zMUSE 􀀀 pz)=(1 + zMUSE) = 􀀀0:04 in the median, and at z > 3 they are systematically biased high by up to (zMUSE 􀀀 pz)=(1 + zMUSE) = 0:05, an o set that can in part be explained by adjusting the amount of intergalactic absorption applied. In agreement with previous studies we find little di erence in the performance of the di erent codes, but in contrast to those we find that adding extensive ground-based and IRAC photometry actually can worsen photo-z performance for faint galaxies.We find an outlier fraction, defined through j(zMUSE 􀀀 pz)=(1 + zMUSE)j > 0:15, of 8% for BPZ and 10% for EAZY and BEAGLE, and show explicitly that this is a strong function of magnitude. While this outlier fraction is high relative to numbers presented in the literature for brighter galaxies, they are very comparable to literature results when the depth of the data is taken into account. Finally, we demonstrate that while a redshift might be of high confidence, the association of a spectrum to the photometric object can be very uncertain and lead to a contamination of a few percent in spectroscopic training samples that do not show up as catastrophic outliers, a problem that must be tackled in order to have su ciently accurate photometric redshifts for future cosmological surveys.
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