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Sample records for fic filamentation induced

  1. Identification of Fic-1 as an enzyme that inhibits bacterial DNA replication by AMPylating GyrB, promoting filament formation.

    Science.gov (United States)

    Lu, Canhua; Nakayasu, Ernesto S; Zhang, Li-Qun; Luo, Zhao-Qing

    2016-01-26

    The morphology of bacterial cells is important for virulence, evasion of the host immune system, and coping with environmental stresses. The widely distributed Fic proteins (filamentation induced by cAMP) are annotated as proteins involved in cell division because of the presence of the HPFx[D/E]GN[G/K]R motif. We showed that the presence of Fic-1 from Pseudomonas fluorescens significantly reduced the yield of plasmid DNA when expressed in Escherichia coli or P. fluorescens. Fic-1 interacted with GyrB, a subunit of DNA gyrase, which is essential for bacterial DNA replication. Fic-1 catalyzed the AMPylation of GyrB at Tyr(109), a residue critical for binding ATP, and exhibited auto-AMPylation activity. Mutation of the Fic-1 auto-AMPylated site greatly reduced AMPylation activity toward itself and toward GyrB. Fic-1-dependent AMPylation of GyrB triggered the SOS response, indicative of DNA replication stress or DNA damage. Fic-1 also promoted the formation of elongated cells when the SOS response was blocked. We identified an α-inhibitor protein that we named anti-Fic-1 (AntF), encoded by a gene immediately upstream of Fic-1. AntF interacted with Fic-1, inhibited the AMPylation activity of Fic-1 for GyrB in vitro, and blocked Fic-1-mediated inhibition of DNA replication in bacteria, suggesting that Fic-1 and AntF comprise a toxin-antitoxin module. Our work establishes Fic-1 as an AMPylating enzyme that targets GyrB to inhibit DNA replication and may target other proteins to regulate bacterial morphology.

  2. Crystal Structure of the Escherichia coli Fic Toxin-Like Protein in Complex with Its Cognate Antitoxin

    Science.gov (United States)

    Stanger, Frédéric V.; Harms, Alexander; Dehio, Christoph; Schirmer, Tilman

    2016-01-01

    FIC domain proteins mediate post-translational modifications of target proteins, which typically results in their inactivation. Depending on the conservation of crucial active site residues, the FIC fold serves as structural scaffold for various enzymatic activities, mostly target adenylylation. The founding member of the vast Fic protein family, EcFicT, was identified in Escherichia coli some time ago. The G55R point mutant of EcFicT displays the “filamentation induced by cAMP” (Fic) phenotype at high 3',5'-cyclic adenosine monophosphate (cAMP) concentrations and elevated temperature, but the underlying molecular mechanism and any putative biochemical activity of EcFicT have remained unknown. EcFicT belongs to class I Fic toxin proteins that are encoded together with a small inhibitory protein (antitoxin), named EcFicA in E. coli. Here, we report the crystal structures of two mutant EcFicT/EcFicA complexes (EcFicTG55RA and EcFicTAE28G) both showing close resemblance with the structure of the AMP-transferase VbhT from Bartonella schoenbuchensis in complex with its cognate antitoxin VbhA. However, crucial differences in the active site of EcFicT compared to VbhT and other AMP-transferases rationalize the lack of evidence for adenylylation activity. Comprehensive bioinformatic analysis suggests that EcFicT has evolved from canonical AMP-transferases and has acquired a conserved binding site for a yet to be discovered novel substrate. The G55R mutation has no effect on structure or thermal stability of EcFicT, such that the molecular basis for its associated Fic phenotype remains elusive. We anticipate that this structure will inspire further bioinformatic and experimental analyses in order to characterize the enzymatic activity of EcFicT and help revealing its physiological role. PMID:27657533

  3. Laser filament-induced aerosol formation

    Directory of Open Access Journals (Sweden)

    H. Saathoff

    2013-05-01

    Full Text Available Using the aerosol and cloud simulation chamber AIDA, we investigated the laser filament induced particle formation in ambient air, humid synthetic air, humid nitrogen, argon–oxygen mixture, and pure argon in order to simulate the particle formation under realistic atmospheric conditions as well as to investigate the influence of typical gas-phase atmospheric constituents on the particle formation. Terawatt laser plasma filaments generated new particles in the size range 3 to 130 nm with particle production rates ranging from 1 × 107 to 5 × 109 cm−3 plasma s−1 for the given experimental conditions. In all cases the particle formation rates increased exponentially with the water content of the gas mixture. Furthermore, the presence of a few ppb of trace gases like SO2 and α-pinene clearly enhanced the particle yield by number, the latter also by mass. Our findings suggest that new particle formation is efficiently supported by oxidized species like acids generated by the photoionization of both major and minor components of the air, including N2, NH3, SO2 and organics.

  4. Laser filament-induced aerosol formation

    Directory of Open Access Journals (Sweden)

    H. Saathoff

    2012-11-01

    Full Text Available Using the aerosol and cloud simulation chamber AIDA we investigated the laser filament induced particle formation in ambient air, humid synthetic air, humid nitrogen, argon-oxygen mixture, and pure argon in order to simulate the particle formation under realistic atmospheric conditions as well as to investigate the influence of typical gas-phase atmospheric constituents on the particle formation. Terawatt laser plasma filaments generated new particles in the size range 3 to 130 nm with particle production rates ranging from 1 × 107 to 5 × 109 cm−3 plasma s−1. In all cases the particle formation rates increased exponentially with the water content of the gas mixture. Furthermore, the presence of a few ppb of trace gases like SO2 and α-pinene clearly enhanced the particle yield by number, the latter also by mass. Our findings suggest that new particle formation is efficiently supported by acids generated by the photo-ionization of both major and minor components of the air, including N2, NH3, SO2 and organics.

  5. Characterization of osmotically induced filaments of Salmonella enterica.

    Science.gov (United States)

    Pratt, Zachary L; Chen, Bingming; Czuprynski, Charles J; Wong, Amy C L; Kaspar, Charles W

    2012-09-01

    Salmonella enterica forms aseptate filaments with multiple nucleoids when cultured in hyperosmotic conditions. These osmotic-induced filaments are viable and form single colonies on agar plates even though they contain multiple genomes and have the potential to divide into multiple daughter cells. Introducing filaments that are formed during osmotic stress into culture conditions without additional humectants results in the formation of septa and their division into individual cells, which could present challenges to retrospective analyses of infectious dose and risk assessments. We sought to characterize the underlying mechanisms of osmotic-induced filament formation. The concentration of proteins and chromosomal DNA in filaments and control cells was similar when standardized by biomass. Furthermore, penicillin-binding proteins in the membrane of salmonellae were active in vitro. The activity of penicillin-binding protein 2 was greater in filaments than in control cells, suggesting that it may have a role in osmotic-induced filament formation. Filaments contained more ATP than did control cells in standardized cell suspensions, though the levels of two F(0)F(1)-ATP synthase subunits were reduced. Furthermore, filaments could septate and divide within 8 h in 0.2 × Luria-Bertani broth at 23°C, while nonfilamentous control cells did not replicate. Based upon the ability of filaments to septate and divide in this diluted broth, a method was developed to enumerate by plate count the number of individual, viable cells within a population of filaments. This method could aid in retrospective analyses of infectious dose of filamented salmonellae.

  6. Plasma temperature clamping in filamentation laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, Sivanandan S.; Yeak, J.; Phillips, Mark C.

    2015-10-19

    Ultrafast laser filament induced breakdown spectroscopy is a very promising method for remote material detection. We present characteristics of plasmas generated in a metal target by laser filaments in air. Our measurements show that the temperature of the ablation plasma is clamped along the filamentation channel due to intensity clamping in a filament. Nevertheless, significant changes in radiation intensity are noticeable, and this is essentially due to variation in the number density of emitting atoms. The present results also partly explains the reason for the occurrence of atomic plume during fs LIBS in air compared to long-pulse ns LIBS.

  7. PDGF induces reorganization of vimentin filaments.

    Science.gov (United States)

    Valgeirsdóttir, S; Claesson-Welsh, L; Bongcam-Rudloff, E; Hellman, U; Westermark, B; Heldin, C H

    1998-07-30

    In this study we demonstrate that stimulation with platelet-derived growth factor (PDGF) leads to a marked reorganization of the vimentin filaments in porcine aortic endothelial (PAE) cells ectopically expressing the PDGF beta-receptor. Within 20 minutes after stimulation, the well-spread fine fibrillar vimentin was reorganized as the filaments aggregated into a dense coil around the nucleus. The solubility of vimentin upon Nonidet-P40-extraction of cells decreased considerably after PDGF stimulation, indicating that PDGF caused a redistribution of vimentin to a less soluble compartment. In addition, an increased tyrosine phosphorylation of vimentin was observed. The redistribution of vimentin was not a direct consequence of its tyrosine phosphorylation, since treatment of cells with an inhibitor for the cytoplasmic tyrosine kinase Src, attenuated phosphorylation but not redistribution of vimentin. These changes in the distribution of vimentin occurred in conjunction with reorganization of actin filaments. In PAE cells expressing a Y740/751F mutant receptor that is unable to bind and activate phosphatidylinositol 3'-kinase (PI3-kinase), the distribution of vimentin was virtually unaffected by PDGF stimulation. Thus, PI3-kinase is important for vimentin reorganization, in addition to its previously demonstrated role in actin reorganization. The small GTPase Rac has previously been shown to be involved downstream of PI3-kinase in the reorganization of actin filaments. In PAE cells overexpressing dominant negative Rac1 (N17Rac1), no change in the fine fibrillar vimentin network was seen after PDGF-BB stimulation, whereas in PAE cells overexpressing constitutively active Rac1 (V12Rac1), there was a dramatic change in vimentin filament organization independent of PDGF stimulation. These data indicate that PDGF causes a reorganization of microfilaments as well as intermediate filaments in its target cells and suggest an important role for Rac downstream of PI3-kinase in

  8. Robust authentication through stochastic femtosecond laser filament induced scattering surfaces

    Science.gov (United States)

    Zhang, Haisu; Tzortzakis, Stelios

    2016-05-01

    We demonstrate a reliable authentication method by femtosecond laser filament induced scattering surfaces. The stochastic nonlinear laser fabrication nature results in unique authentication robust properties. This work provides a simple and viable solution for practical applications in product authentication, while also opens the way for incorporating such elements in transparent media and coupling those in integrated optical circuits.

  9. Force-induced dynamical properties of multiple cytoskeletal filaments are distinct from that of single filaments

    CERN Document Server

    Das, Dipjyoti; Padinhateeri, Ranjith

    2014-01-01

    How cytoskeletal filaments collectively undergo growth and shrinkage is an intriguing question. Collective properties of multiple bio-filaments (actin or microtubules) undergoing hydrolysis, have not been studied extensively earlier, within simple theoretical frameworks. In this paper, we show that collective properties of multiple filaments under force are very distinct from the properties of a single filament under similar conditions -- these distinctions manifest as follows: (i) the collapse time during collective catastrophe for a multifilament system is much larger than that of a single filament with the same average length, (ii) force-dependence of the cap-size distribution of multiple filaments are quantitatively different from that of single filament, (iii) the diffusion constant associated with the system length fluctuations is distinct for multiple filaments, (iv) switching dynamics of multiple filaments between capped and uncapped states and the fluctuations therein are also distinct. We build a un...

  10. Beam deflection induced by E×B near a linear filament cathode

    Science.gov (United States)

    Zhang, Huashun; Jiang, Jiasheng

    2017-02-01

    Beam deflection induced by E×B near a linear filament cathode in a two grid electron gun is presented theoretically and experimentally. The experimental results are consistent with the calculation based on the theoretical equations. The influences upon performance and design of electron gun with linear filament cathode, which is used broadly in electrocurtain accelerators, are discussed in detail.

  11. Survival and virulence of Salmonella enterica serovar enteritidis filaments induced by reduced water activity.

    Science.gov (United States)

    Stackhouse, Robert R; Faith, Nancy G; Kaspar, Charles W; Czuprynski, Charles J; Wong, Amy C Lee

    2012-04-01

    Salmonella enterica serovar Enteritidis strain E40 filaments were developed under conditions of a reduced water activity (a(w)) of 0.95 in tryptic soy broth (TSB) or tryptic soy agar (TSA) supplemented with 8% or 7% NaCl, respectively. Filament formation was accompanied by an increase of biomass without an increase in CFU and was affected by incubation temperature and the physical milieu. The greatest amount of filaments was recovered from TSA with 7% NaCl and incubation at 30°C. Within 2 h of transfer to fresh TSB, filaments started to septate into normal-sized cells, resulting in a rapid increase in CFU. S. Enteritidis E40 filaments were not more tolerant of low- or high-temperature stresses than nonfilamented control cells. However, there was greater survival of filaments in 10% bile salts after 24 to 48 h of incubation, during pH 2.0 acid challenge for 10 min, and under desiccation on stainless steel surfaces at 25°C and 75.5% relative humidity for 7 days. S. Enteritidis E40 filaments invaded and multiplied within Caco-2 human intestinal epithelial cells to a similar degree as control cells when a comparable CFU of filaments and control cells was used. S. Enteritidis E40 filaments established a successful infection in mice via intragastric inoculation. The filaments colonized the gastrointestinal tract and disseminated to the spleen and liver at levels comparable to those attained by control cells, even when animals were inoculated with 10- to 100-fold fewer CFU. To our knowledge this is the first demonstration of virulence of stress-induced Salmonella filaments in vitro and in vivo. Formation of filaments by Salmonella in food products and food processing environments is significant to food safety, because detection and quantitation of the pathogen may be compromised. The finding that these filaments are virulent further enhances their potential public health impact.

  12. Disappearance of a coronal hole induced by a filament activation

    CERN Document Server

    Lin, Ma; Xiao-Li, Yan; Zhi-Ke, Xue

    2014-01-01

    We present a rare observation of direct magnetic interaction between an activating filament and a coronal hole (CH). The filament was a quiescent one located at the northwest of the CH. It underwent a nonradial activation, during which filament material constantly fell and intruded into the CH. As a result, the CH was clearly destroyed by the intrusion. Brightenings appeared at the boundaries and in the interior of the CH, meanwhile, its west boundaries began to retreat and the area gradually shrank. It is noted that the CH went on shrinking after the end of the intrusion and finally disappeared entirely. Following the filament activation, three coronal dimmings (D1-D3) were formed, among which D1 and D2 persisted throughout the complete disappearance of the CH. The derived coronal magnetic configuration shows that the filament was located below an extended loop system which obviously linked D1 to D2. By comparison with this result of extrapolation, our observations imply that the interaction between the fila...

  13. Non-local dynamics governing the self-induced motion of a planar vortex filament

    Science.gov (United States)

    Van Gorder, Robert A.

    2015-06-01

    While the Hasimoto planar vortex filament is one of the few exact solutions to the local induction approximation (LIA) approximating the self-induced motion of a vortex filament, it is natural to wonder whether such a vortex filament solution would exist for the non-local Biot-Savart dynamics exactly governing the filament motion, and if so, whether the non-local effects would drastically modify the solution properties. Both helical vortex filaments and vortex rings are known to exist under both the LIA and non-local Biot-Savart dynamics; however, the planar filament is a bit more complicated. In the present paper, we demonstrate that a planar vortex filament solution does exist for the non-local Biot-Savart formulation, provided that a specific non-linear integral equation (governing the spatial structure of such a filament) has a non-trivial solution. By using the Poincaré-Lindstedt method, we are able to obtain an accurate analytical approximation to the solution of this integral equation under physically reasonable assumptions. To obtain these solutions, we approximate local effects near the singularity of the integral equation using the LIA and non-local effects using the Biot-Savart formulation. Mathematically, the results constitute an analytical solution to an interesting nonlinear singular integro-differential equation in space and time variables. Physically, these results show that planar vortex filaments exist and maintain their forms under the non-local Biot-Savart formulation, as one would hope. Due to the regularization approach utilized, we are able to compare the structure of the planar filaments obtained under both LIA and Biot-Savart formulations in a rather straightforward manner, in order to determine the role of the non-locality on the structure of the planar filament.

  14. Disassembly of actin filaments by botulinum C2 toxin and actin-filament-disrupting agents induces assembly of microtubules in human leukaemia cell lines.

    Science.gov (United States)

    Uematsu, Yosuke; Kogo, Yasusi; Ohishi, Iwao

    2007-03-01

    C(2) toxin produced by Clostridium botulinum types C and D ADP-ribosylates actin monomers and inactivates their polymerization activities. The disassembly of actin filaments by C(2) toxin induces a polarization of cultured human leukaemia cell lines. The polarization induced by C(2) toxin was temperature dependent and was prevented by nocodazole, a microtubule-disrupting agent, whereas it was promoted by paclitaxel, a microtubule-stabilizing agent. The fluorescence staining of polarized cells indicated an increase in microtubule assembly accompanying disassembly of actin filaments. Furthermore, several actin-filament-disrupting agents, other than C(2) toxin, also induced microtubule assembly and cell polarization, irrespective of their different mechanisms of action. The effects induced by some of the agents, which have lower binding affinities for actin, were reversible in response to the re-assembly of actin filaments. Thus the disassembly of actin filaments by C(2) toxin and actin-filament-disrupting agents induces assembly of microtubules followed by polarization of human leukaemia cell lines, indicating that the assembly/disassembly equilibrium of actin filaments influences the dynamics of microtubules, which control cell morphology and, in turn, diverse cellular processes.

  15. Strain-induced internal fibrillation in looped aramid filaments

    DEFF Research Database (Denmark)

    Pauw, Brian Richard; Vigild, Martin Etchells; Mortensen, Kell;

    2010-01-01

    By mapping the small-angle X-ray scattering (SAXS) from a looped poly-(para-phenylene terephtalamide) (aramid, PPTA) filament using a synchrotron X-ray microbeam, we investigate the effects of axially compressive and tensile strain on internal fibrillar structures. Unique observations of oscillat...

  16. ANALYTICAL SOLUTION FOR THE VELOCITY FIELD INDUCED BY A UNIFORMLY MOVING HELICAL VORTEX FILAMENT IN CYLINDRICAL TUBE

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A derivation of an analytical expression for the inviscid velocity field induced by a single right-handed helical vortex filament is presented. The vortex filament moves uniformly and rigidly without change of form in a cylindrical tube, where the vortex filament rotates around its axis with a constant angular velocity and translates along its axis with a constant translational velocity. The key to solve the problem is to set up a moving cylindrical coordinate system fixed on the vortex filament. The result shows that the velocity field is a time-periodic function, and may degenerate into Okulovs's formula when the helical vortex filament slips along the filament itself or stays immobile.

  17. Measuring cohesion between macromolecular filaments, one pair at a time: Depletion-induced microtubule binding

    CERN Document Server

    Hilitski, Feodor; Cajamarca, Luis; Hagan, Michael F; Grason, Gregory M; Dogic, Zvonimir

    2014-01-01

    In presence of non-adsorbing polymers, colloidal particles experience a ubiquitous attractive interactions induced by the depletion mechanism. We measure the depletion interaction between a pair of microtubule filaments by a method that combines optical trapping, single molecule imaging and umbrella sampling. By quantifying the dependence of filament cohesion on both polymer concentration and solution ionic strength, we demonstrate that the minimal model of depletion based, on the Asakura-Oosawa theory, fails to describe the experimental data. By measuring the cohesion strength in two- and three- filament bundles we verify pairwise additivity of the depletion interaction for the specific experimental conditions. The described experimental technique can be used to measure pairwise interactions between various biological or synthetic filaments, thus complementing information extracted from bulk osmotic stress experiments.

  18. Effect of Actin Filament on Deformation-Induced Ca2+ Response in Osteoblast-Like Cells

    Science.gov (United States)

    Adachi, Taiji; Murai, Takayuki; Hoshiai, Sodai; Tomita, Yoshihiro

    Under the influence of mechanical environment, bone structure is formed and maintained by adaptive remodeling that involves osteoclastic resorption and osteoblastic formation. In the mechanotransduction system in osteoblasts, it is believed that intracellular calcium plays a fundamental role and cytoskeletal actin filament is a crucial component for the signal transduction process. To clarify the role of actin filament in deformation-induced Ca2+ signaling, osteoblast-like cells (MC3T3-E1) with different actin filament densities controlled by cytochalasin D were subjected to tensile strain in vitro. The change in intracellular Ca2+ concentration labeled by fluo-3 was observed using a confocal laser-scanning microscope. As a result, the disruption of the actin filament was found to significantly suppress the deformation-induced Ca2+ response that was regulated according to the degree of actin filament organization. This result indicates that the actin filament is indispensable for the quantitative regulation of Ca2+ signaling in response to a mechanical stimulus in osteoblasts.

  19. Structural architecture of the CARMA1/Bcl10/MALT1 signalosome: nucleation-induced filamentous assembly.

    Science.gov (United States)

    Qiao, Qi; Yang, Chenghua; Zheng, Chao; Fontán, Lorena; David, Liron; Yu, Xiong; Bracken, Clay; Rosen, Monica; Melnick, Ari; Egelman, Edward H; Wu, Hao

    2013-09-26

    The CARMA1/Bcl10/MALT1 (CBM) signalosome mediates antigen receptor-induced NF-κB signaling to regulate multiple lymphocyte functions. While CARMA1 and Bcl10 contain caspase recruitment domains (CARDs), MALT1 is a paracaspase with structural similarity to caspases. Here we show that the reconstituted CBM signalosome is a helical filamentous assembly in which substoichiometric CARMA1 nucleates Bcl10 filaments. Bcl10 filament formation is a highly cooperative process whose threshold is sensitized by oligomerized CARMA1 upon receptor activation. In cells, both cotransfected CARMA1/Bcl10 complex and the endogenous CBM signalosome are filamentous morphologically. Combining crystallography, nuclear magnetic resonance, and electron microscopy, we reveal the structure of the Bcl10 CARD filament and the mode of interaction between CARMA1 and Bcl10. Structure-guided mutagenesis confirmed the observed interfaces in Bcl10 filament assembly and MALT1 activation in vitro and NF-κB activation in cells. These data support a paradigm of nucleation-induced signal transduction with threshold response due to cooperativity and signal amplification by polymerization.

  20. Graphical Facility Information Center (GraFIC{trademark})

    Energy Technology Data Exchange (ETDEWEB)

    Dunigan, J.J.; Gaby, J.E.; Hickerson, T.W.; Miller, M.A. [and others

    1997-07-01

    The Graphical Facility Information Center (GraFIC{trademark}) is an information system that provides an inexpensive and flexible method of remotely verifying complete {open_quotes}up-to-the-minute{close_quotes} inventory status of stored items and facility assets. In addition, GraFIC{trademark} provides features needed for day to day management of storage and other facilities. GraFIC{trademark} combines an easy to use graphical user interface with extensive online help so that users need little training. GraFIC{trademark} can be configured to work with most sensor systems used to monitor facility assets.

  1. Helical filaments

    Energy Technology Data Exchange (ETDEWEB)

    Barbieri, Nicholas; Lim, Khan; Durand, Magali; Baudelet, Matthieu; Richardson, Martin [Townes Laser Institute, CREOL—The College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816 (United States); Hosseinimakarem, Zahra; Johnson, Eric [Micro-Photonics Laboratory – Center for Optical Material Science, Clemson, Anderson, South Carolina 29634 (United States)

    2014-06-30

    The shaping of laser-induced filamenting plasma channels into helical structures by guiding the process with a non-diffracting beam is demonstrated. This was achieved using a Bessel beam superposition to control the phase of an ultrafast laser beam possessing intensities sufficient to induce Kerr effect driven non-linear self-focusing. Several experimental methods were used to characterize the resulting beams and confirm the observed structures are laser air filaments.

  2. Self-induced white-light seeding laser in a femtosecond laser filament

    CERN Document Server

    Chu, Wei; Xie, Hongqiang; Ni, Jielei; Yao, Jinping; Zeng, Bin; Zhang, Haisu; Jing, Chenrui; Xu, Huailiang; Cheng, Ya; Xu, Zhizhan

    2013-01-01

    We report, for what we believe to be the first time, on the generation of remote self-seeding laser amplification by using only one 800 nm Ti:Sapphire femtosecond laser pulse. The laser pulse (~ 40 fs) is first used to generate a filament either in pure nitrogen or in ambient air in which population inversion between ground and excited states of nitrogen molecular ions is realized. Self-induced white light inside the filament is then serving as the seed to be amplified. The self-induced narrow-band laser at 428 nm has a pulse duration of ~2.6 ps with perfect linear polarization property. This finding opens new possibilities for remote detection in the atmosphere.

  3. A defect in amino acid transport of filamentous Escherichia coli induced by penicillin.

    OpenAIRE

    内藤, 伸明; 友近, 健一; 口分田,晃; 塩出,純二; 金政, 泰弘

    1983-01-01

    This paper describes a new type of penicillin action on the cytoplasmic membrane of Escherichia coli. The ability of filamentous cells to uptake amino acids induced by low concentrations of penicillin increased with cell elongation. This defect in amino acid transport was mostly observed on the substrate of the osmotic shock resistant transport system. Penicillin treatment, however, did not disturb the other membrane functions such as the uptake of α-D-methyl glucopyranoside and triphenylmeth...

  4. Modelling of helical current filaments induced by LHW on EAST

    Energy Technology Data Exchange (ETDEWEB)

    Rack, Michael; Denner, Peter; Liang, Yunfeng [Institute of Energy and Climate Research - Plasma Physics, Forschungszentrum Juelich GmbH, Association EURATOM-FZJ, Partner in the Trilateral Euregio Cluster, D-52425 Juelich (Germany); Zeng, Long [Institute of Energy and Climate Research - Plasma Physics, Forschungszentrum Juelich GmbH, Association EURATOM-FZJ, Partner in the Trilateral Euregio Cluster, D-52425 Juelich (Germany); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Gong, Xianzu; Gan, Kaifu; Wang, Liang; Liu, Fukun; Qian, Jinping; Shen, Biao; Li, Jiangang [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Gauthier, Eric [Association EURATOM-CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Collaboration: the EAST Team

    2013-07-01

    Helical radiation belts have been observed in the scrape-off layer (SOL) of the plasma during the application of lower hybrid wave (LHW) heating at the superconducting tokamak EAST. Modelled SOL field lines, starting in-front of the LHW antennas, show agreement in position and pitch angle to the experimental observed radiation belts. A splitting of the strike-line can be observed on the outer divertor plates during the application of LHW heating. Agreement in the comparison of the Mirnov coil signals and a modelled electric current flow along these SOL field lines was found. A lower hybrid current drive can induce such an electric current flow near the plasma edge. This electric current flow causes a change of the plasma topology which could result in the splitting of the strike-line as known from the application of resonant magnetic perturbation fields. Comparisons of modelled footprint structures and experimental observed heat load patterns in the divertor region are discussed.

  5. Phototropin-dependent biased relocalization of cp-actin filaments can be induced even when chloroplast movement is inhibited.

    Science.gov (United States)

    Yamada, Noboru; Suetsugu, Noriyuki; Wada, Masamitsu; Kadota, Akeo

    2011-11-01

    In a recent publication using an actin-visualized line of Arabidopsis (Ichikawa et al. 2011, ref. 11), we reported a detailed analysis with higher time resolution on the dynamics of chloroplast actin filaments (cp-actin filaments) during chloroplast avoidance movement and demonstrated a good correlation between the biased configuration of cp-actin filaments and chloroplast movement. However, we could not conclusively determine whether the reorganization of cp-actin filaments into a biased configuration preceded actual chloroplast movement (and, thus, whether it could be a cause of the movement). In this report, we present clear evidence that the reorganization of cp-actin filaments into a biased distribution is induced even in the absence of the actual movement of chloroplasts. When the cells were treated with 2,3-butanedione monoxime (BDM), a potent inhibitor of myosin ATPase, chloroplast motility was completely suppressed. Nevertheless, the disappearance and biased relocalization of cp-actin filaments toward the side of the prospective movement direction were induced by irradiation with a strong blue light microbeam. The results definitively indicate that the reorganization of cp-actin filaments is not an effect of chloroplast movement; however, it is feasible that the biased localization of cp-actin filaments is an event leading to chloroplast movement.

  6. White-light-induced disruption of nanoscale conducting filament in hafnia

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Y.; Yew, K. S.; Ang, D. S., E-mail: edsang@ntu.edu.sg; Bera, M. K.; Zhang, H. Z. [Nanyang Technological University, School of Electrical and Electronic Engineering, Singapore, Singapore 639798 (Singapore); Kawashima, T. [Nanyang Technological University, School of Electrical and Electronic Engineering, Singapore, Singapore 639798 (Singapore); Toshiba Corporation, 33 Shin-Isogo-Cho, Isogo-ku, Yokohama 235-0017 (Japan); Bersuker, G. [The Aerospace Corporation, P.O. Box 92957, M2-244, Los Angeles, California 90009-2957 (United States)

    2015-08-17

    Nanoscale conducting filament, which forms the basis of the HfO{sub 2} resistive memory, is shown to exhibit a “negative photoconductivity” behavior, in that, electrical conduction through it can be disrupted upon white-light illumination. This behavior should be contrasted against the positive photoconductivity behavior commonly exhibited by oxides or perovskites having narrower bandgaps. The negative photoconductivity effect may be explained in terms of a photon-induced excitation of surrounding oxygen ions, which leads to migration and subsequent recombination with vacancies in the conducting filament. The finding suggests possible electrical-cum-optical applications for HfO{sub 2}-based devices, whose functionality is limited to-date by electrical stimulation.

  7. Staurosporine Induces Filamentation in the Human Fungal Pathogen Candida albicans via Signaling through Cyr1 and Protein Kinase A

    Science.gov (United States)

    Xie, Jinglin L.; O’Meara, Teresa R.; Polvi, Elizabeth J.; Robbins, Nicole

    2017-01-01

    ABSTRACT Protein kinases are key regulators of signal transduction pathways that participate in diverse cellular processes. In fungal pathogens, kinases regulate signaling pathways that govern drug resistance, stress adaptation, and pathogenesis. The impact of kinases on the fungal regulatory circuitry has recently garnered considerable attention in the opportunistic fungal pathogen Candida albicans, which is a leading cause of human morbidity and mortality. Complex regulatory circuitry governs the C. albicans morphogenetic transition between yeast and filamentous growth, which is a key virulence trait. Here, we report that staurosporine, a promiscuous kinase inhibitor that abrogates fungal drug resistance, also influences C. albicans morphogenesis by inducing filamentation in the absence of any other inducing cue. We further establish that staurosporine exerts its effect via the adenylyl cyclase Cyr1 and the cyclic AMP (cAMP)-dependent protein kinase A (PKA). Strikingly, filamentation induced by staurosporine does not require the known upstream regulators of Cyr1, Ras1 or Pkc1, or effectors downstream of PKA, including Efg1. We further demonstrate that Cyr1 is capable of activating PKA to enable filamentation in response to staurosporine through a mechanism that does not require degradation of the transcriptional repressor Nrg1. We establish that staurosporine-induced filamentation is accompanied by a defect in septin ring formation, implicating cell cycle kinases as potential staurosporine targets underpinning this cellular response. Thus, we establish staurosporine as a chemical probe to elucidate the architecture of cellular signaling governing fungal morphogenesis and highlight the existence of novel circuitry through which the Cyr1 and PKA govern a key virulence trait. IMPORTANCE The impact of fungal pathogens on human health is devastating. One of the most pervasive fungal pathogens is Candida albicans, which kills ~40% of people suffering from bloodstream

  8. Amplification of 126 nm femtosecond seed pulses in optical-field-induced Ar plasma filamentation

    Science.gov (United States)

    Kubodera, Shoichi; Deshimaru, Naoyuki; Kaku, Masanori; Katto, Masahito

    2014-10-01

    We have observed amplification of femtosecond (fs) VUV coherent seed beam at 126 nm by utilizing an optical-field-induced ionization (OFI) high-pressure Ar plasma filamentation. We have produced a low-temperature and high-density Ar plasma filamentation inside a high-pressure Ar cell by irradiating a high-intensity laser with an intensity of approximately 1014 W cm-2. Argon excimer molecules (Ar2*) as an amplifier medium were produced inside the high-pressure cell and were used to amplify a weak VUV ultrashort seed pulse at 126 nm, which was generated by harmonic generation of another short pulse infrared laser at 882 nm. We have measured the amplification characteristics and the OFI plasma diagnosis by utilizing the fs VUV pulses at 126 and 882 nm, respectively. The maximum optical gain value of 1.1 cm-1 was observed. Temporal behaviors of the plasma temperature and density in the nano-second time scale indicated a high-density and low-temperature plasma produced by using the OFI. These plasma behaviors were utilized to reproduce the optical amplification characteristics with our OFI excimer simulation code.

  9. Nodularin Exposure Induces SOD1 Phosphorylation and Disrupts SOD1 Co-localization with Actin Filaments

    Directory of Open Access Journals (Sweden)

    Kari E. Fladmark

    2012-12-01

    Full Text Available Apoptotic cell death is induced in primary hepatocytes by the Ser/Thr protein phosphatase inhibiting cyanobacterial toxin nodularin after only minutes of exposure. Nodularin-induced apoptosis involves a rapid development of reactive oxygen species (ROS, which can be delayed by the Ca2+/calmodulin protein kinase II inhibitor KN93. This apoptosis model provides us with a unique population of highly synchronized dying cells, making it possible to identify low abundant phosphoproteins participating in apoptosis signaling. Here, we show that nodularin induces phosphorylation and possibly also cysteine oxidation of the antioxidant Cu,Zn superoxide dismutase (SOD1, without altering enzymatic SOD1 activity. The observed post-translational modifications of SOD1 could be regulated by Ca2+/calmodulin protein kinase II. In untreated hepatocytes, a high concentration of SOD1 was found in the sub-membranous area, co-localized with the cortical actin cytoskeleton. In the early phase of nodularin exposure, SOD1 was found in high concentration in evenly distributed apoptotic buds. Nodularin induced a rapid reorganization of the actin cytoskeleton and, at the time of polarized budding, SOD1 and actin filaments no longer co-localized.

  10. Casein kinase II induced polymerization of soluble TDP-43 into filaments is inhibited by heat shock proteins.

    Directory of Open Access Journals (Sweden)

    Yari Carlomagno

    : These findings demonstrate CKII induces polymerization of soluble TDP-43 into filaments and Hsp90 promotes TDP-43 filament depolymerization. These findings provide rational for potential therapeutic intervention at these points in TDP-43 proteinopathies.

  11. Direct visualization of flow-induced conformational transitions of single actin filaments in entangled solutions

    CERN Document Server

    Kirchenbuechler, Inka; Kurniawan, Nicholas A; Koenderink, Gijsje H; Lettinga, M Paul

    2015-01-01

    While semi-flexible polymers and fibers are an important class of material due to their rich mechanical properties, it remains unclear how these properties relate to the microscopic conformation of the polymers. Actin filaments constitute an ideal model polymer system due to their micron-sized length and relatively high stiffness that allow imaging at the single filament level. Here we study the effect of entanglements on the conformational dynamics of actin filaments in shear flow. We directly measure the full three-dimensional conformation of single actin filaments, using confocal microscopy in combination with a counter-rotating cone-plate shear cell. We show that initially entangled filaments form disentangled orientationally ordered hairpins, confined in the flow-vorticity plane. In addition, shear flow causes stretching and shear alignment of the hairpin tails, while the filament length distribution remains unchanged. These observations explain the strain-softening and shear-thinning behavior of entangl...

  12. Concentration-dependency of beta-lactam-induced filament formation in Gram-negative bacteria.

    NARCIS (Netherlands)

    Buijs, J.; Dofferhoff, A.S.M.; Mouton, J.W.; Wagenvoort, J.H.T.; Meer, J.W.M. van der

    2008-01-01

    Ceftazidime and cefotaxime are beta-lactam antibiotics with dose-related affinities for penicillin-binding protein (PBP)-3 and PBP-1. At low concentrations, these antibiotics inhibit PBP-3, leading to filament formation. Filaments are long strands of non-dividing bacteria that contain enhanced quant

  13. Stimulated electromagnetic terahertz emissions (SEE) from laser-induced plasma filaments

    Science.gov (United States)

    Isham, Brett; Kunhardt, Erich

    2016-07-01

    Advances in terawatt laser technology have made it possible to ionize the troposphere in long (centimeters to kilometers), narrow (less than 1 mm), wire-like plasma filaments. These filaments emit high-power stimulated electromagnetic emissions (SEE) at terahertz (submillimeter) frequencies, a frontier in the electromagnetic spectrum lying between the microwave and far infrared bands. Using an accepted model for the plasma oscillations in the filament and a thin-wire approximation, we have calculated the current density and the resulting pattern of terahertz radiation emitted by the filament. The conical shape and opening angle of the calculated radiation pattern match those of recent measurements. Future work could include measurements of both the radiation pattern and of the frequency spectrum, for comparison with detailed calculations of filament plasma processes. Potential applications include high-resolution imaging and remote spectroscopic identification of chemical substances.

  14. Scalability of valence change memory: From devices to tip-induced filaments

    Directory of Open Access Journals (Sweden)

    U. Celano

    2016-08-01

    Full Text Available Since the early days of the investigation on resistive switching (RS, the independence of the ON-state resistance with actual cell area has been a trademark of filamentary-switching. However, with the continuous downscaling of the memory cell down to 10 x 10 nm2 and below, the persistence of this phenomena raises intriguing questions on the conductive filaments (CFs and its dimensions. Particularly, the cell functionality demonstrated at relatively high switching current (> 100 μA implies a high current density (> 106 A/cm2 inside a CF supposedly confined in few hundreds on nm3. We previously demonstrated a methodology for the direct observation of CFs in integrated devices namely scalpel SPM, which overcomes most of the characterization challenges imposed by the device structure and the small CF lateral dimensions. In this letter, we use scalpel SPM to clarify the scaling potential of HfO2-based valence change memory (VCM by characterization of CFs programmed at relatively high switching current and by AFM tip-induced RS experiments. Besides the demonstration of a remarkable scaling potential for the VCM technology, our results are also used to clarify the present understanding on the AFM-based experiments.

  15. Scalability of valence change memory: From devices to tip-induced filaments

    Science.gov (United States)

    Celano, U.; Fantini, A.; Degraeve, R.; Jurczak, M.; Goux, L.; Vandervorst, W.

    2016-08-01

    Since the early days of the investigation on resistive switching (RS), the independence of the ON-state resistance with actual cell area has been a trademark of filamentary-switching. However, with the continuous downscaling of the memory cell down to 10 x 10 nm2 and below, the persistence of this phenomena raises intriguing questions on the conductive filaments (CFs) and its dimensions. Particularly, the cell functionality demonstrated at relatively high switching current (> 100 μA) implies a high current density (> 106 A/cm2) inside a CF supposedly confined in few hundreds on nm3. We previously demonstrated a methodology for the direct observation of CFs in integrated devices namely scalpel SPM, which overcomes most of the characterization challenges imposed by the device structure and the small CF lateral dimensions. In this letter, we use scalpel SPM to clarify the scaling potential of HfO2-based valence change memory (VCM) by characterization of CFs programmed at relatively high switching current and by AFM tip-induced RS experiments. Besides the demonstration of a remarkable scaling potential for the VCM technology, our results are also used to clarify the present understanding on the AFM-based experiments.

  16. Fabricando corpos: ficção e tecnologia

    Directory of Open Access Journals (Sweden)

    Ieda Tucherman

    2008-09-01

    Full Text Available Desdobramento dos extensos estudos da autora sobre a ficção científica no cinema como narrativa representativa do mundo contemporâneo, o artigo enfoca especificamente as questões relacionadas ao corpo humano e à tecnologia que emergem dos filmes desse gênero nascido sob o signo da cultura visual médica. As narrativas fílmicas contemporâneas de ficção científica abrem espaço para reflexões sobre as sociedades atuais em mutação e para questionarmos até que ponto, diante da profunda interação homem-máquina, permanecemos ainda humanos. Palavras-chave: Ficção científica; cinema; tecnociência; corpo; subjetividade. ABSTRACT This article draws on my extensive studies on science fiction cinema as a form of narrative which represents contemporary world. The work focus specifically the questions related with the human body and the technology which emerges from sci fi films generated under the sign of medical visual culture. Contemporary filmic science fiction narratives give way to refletions over present mutating societies and to questioning how far, given the deep human-machine interaction, we are still human. Keywords: Science fiction; cinema; technoscience; body; subjectivity.

  17. Femtosecond laser-induced color change and filamentation in Ag+-doped silicate glass

    Institute of Scientific and Technical Information of China (English)

    Haiyi Sun; Fei He; Jian Xu; Yang Liao; Ya Cheng; Zhizhan Xu; Xiongwei Jiang; Ye Dai

    2009-01-01

    We investigate the influence of multiple filamentation (MF) on the micromachining in Ag+-doped silicate glass irradiated by a 1-kHz femtosecond laser. The thresholds of MF and color change (CC) are measured for both linearly and circularly polarized laser beams. The results demonstrate that the thresholds of MF and CC are very close. The thresholds of CC and MF for circular polarization increase by ~1.4 times compared with linear polarization. Circular polarization can suppress the number of filaments to some extent compared with linear polarization. However, it is difficult to obtain CC without any filamentation if circular polarization technique is used alone.

  18. Competition between multiphoton/tunnel ionization and filamentation induced by powerful femtosecond laser pulses in air

    Institute of Scientific and Technical Information of China (English)

    W. Liu; Q. Luo; S. L. Chin

    2003-01-01

    In this work we present experiments by focusing 42 femtosecond laser pulses in air using three different focal length lenses: f=100, 30 and 5 cm. For the longest focal length, only the filament, which is a weak plasma column, is observed. When the shorter focal length lens is used, a high density plasma is generated near the geometrical focus and coexists with a weak plasma channel of the filament. Under the tightest focusing condition, filamentation is prevented and only a strong plasma volume appears at the geometrical focus.

  19. Multi-octave spanning nonlinear interactions induced by femtosecond filamentation in polycrystalline ZnSe

    Science.gov (United States)

    Šuminas, R.; Tamošauskas, G.; Valiulis, G.; Jukna, V.; Couairon, A.; Dubietis, A.

    2017-06-01

    We report on filamentation and supercontinuum generation in polycrystalline ZnSe by intense femtosecond laser pulses whose center wavelength is tunable in the 1.5-2.4 μm range. By varying the input pulse energy, single and multiple filamentation regimes were accessed, as verified by the measurements of near field intensity distributions. Along with supercontinuum generation, efficient simultaneous generation of broadband second, third, and fourth harmonics is observed. We uncover that extremely efficient harmonics generation stems from randomly quasi phase matched three wave mixing processes, which are facilitated by filamentation of the input beam, as verified by the spectral and energy conversion dynamics, and by polarization measurements.

  20. Self-assembly of a filament by curvature-inducing proteins

    Science.gov (United States)

    Kwiecinski, James; Chapman, S. Jonathan; Goriely, Alain

    2017-04-01

    We explore a simplified macroscopic model of membrane shaping by means of curvature-sensing BAR proteins. Equations describing the interplay between the shape of a freely floating filament in a fluid and the adhesion kinetics of proteins are derived from mechanical principles. The constant curvature solutions that arise from this system are studied using weakly nonlinear analysis. We show that the stability of the filament's shape is completely characterized by the parameters associated with protein recruitment and establish that in the bistable regime, proteins aggregate on the filament forming regions of high and low curvatures. This pattern formation is then followed by phase-coarsening that resolves on a time-scale dependent on protein diffusion and drift across the filament, which contend to smooth and maintain the pattern respectively. The model is generalized for multiple species of BAR proteins and we show that the stability of the assembled shape is determined by a competition between proteins attaching on opposing sides.

  1. Simultaneous transverse oscillations of a prominence and a filament and longitudinal oscillation of another filament induced by a single shock wave

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yuandeng [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Liu, Ying D. [State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100190 (China); Chen, P. F. [Key Laboratory of Modern Astronomy and Astrophysics, School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Ichimoto, Kiyoshi, E-mail: ydshen@ynao.ac.cn [Kwasan and Hida Observatories, Kyoto University, Yamashina-ku, Kyoto 607-8471 (Japan)

    2014-11-10

    We present the first stereoscopic and Doppler observations of simultaneous transverse oscillations of a prominence and a filament and longitudinal oscillation of another filament launched by a single shock wave. Using Hα Doppler observations, we derive the three-dimensional oscillation velocities at different heights along the prominence axis. The results indicate that the prominence has a larger oscillation amplitude and damping time at higher altitude, but the periods at different heights are the same (i.e., 13.5 minutes). This suggests that the prominence oscillates like a linear vertical rigid body with one end anchored on the Sun. One of the filaments shows weak transverse oscillation after the passing of the shock, which is possibly due to the low altitude of the filament and the weakening (due to reflection) of the shock wave before the interaction. Large-amplitude longitudinal oscillation is observed in the other filament after the passing of the shock wave. The velocity amplitude and period are about 26.8 km s{sup –1} and 80.3 minutes, respectively. We propose that the orientation of a filament or prominence relative to the normal vector of the incoming shock should be an important factor for launching transverse or longitudinal filament oscillations. In addition, the restoring forces of the transverse prominence are most likely due to the coupling of gravity and magnetic tension of the supporting magnetic field, while that for the longitudinal filament oscillation is probably the resultant force of gravity and magnetic pressure.

  2. The Contribution of Kawada to the Analytical Solution for the Velocity Induced by a Helical Vortex Filament

    DEFF Research Database (Denmark)

    Fukumoto, Yasuhide; Okulov, Valery L.; Wood, David H.

    2015-01-01

    The basic solution for the velocity induced by helical vortex filament is well known as Hardin's solution, published in 1982. A study of early publications on helical vortices now shows that the Japanese scientist Kawada from Tokyo Imperial University also produced many of these results in 1936......, which predates Hardin by 46 years. Consequently, in order to honor both, we have studied their derivations to establish the originality of both solutions....

  3. Fido, a novel AMPylation domain common to fic, doc, and AvrB.

    Directory of Open Access Journals (Sweden)

    Lisa N Kinch

    Full Text Available BACKGROUND: The Vibrio parahaemolyticus type III secreted effector VopS contains a fic domain that covalently modifies Rho GTPase threonine with AMP to inhibit downstream signaling events in host cells. The VopS fic domain includes a conserved sequence motif (HPFx[D/E]GN[G/K]R that contributes to AMPylation. Fic domains are found in a variety of species, including bacteria, a few archaea, and metazoan eukaryotes. METHODOLOGY/PRINCIPAL FINDINGS: We show that the AMPylation activity extends to a eukaryotic fic domain in Drosophila melanogaster CG9523, and use sequence and structure based computational methods to identify related domains in doc toxins and the type III effector AvrB. The conserved sequence motif that contributes to AMPylation unites fic with doc. Although AvrB lacks this motif, its structure reveals a similar topology to the fic and doc folds. AvrB binds to a peptide fragment of its host virulence target in a similar manner as fic binds peptide substrate. AvrB also orients a phosphate group from a bound ADP ligand near the peptide-binding site and in a similar position as a bound fic phosphate. CONCLUSIONS/SIGNIFICANCE: The demonstrated eukaryotic fic domain AMPylation activity suggests that the VopS effector has exploited a novel host posttranslational modification. Fic domain-related structures give insight to the AMPylation active site and to the VopS fic domain interaction with its host GTPase target. These results suggest that fic, doc, and AvrB stem from a common ancestor that has evolved to AMPylate protein substrates.

  4. A simple application of FIC to model selection

    CERN Document Server

    Wiggins, Paul A

    2015-01-01

    We have recently proposed a new information-based approach to model selection, the Frequentist Information Criterion (FIC), that reconciles information-based and frequentist inference. The purpose of this current paper is to provide a simple example of the application of this criterion and a demonstration of the natural emergence of model complexities with both AIC-like ($N^0$) and BIC-like ($\\log N$) scaling with observation number $N$. The application developed is deliberately simplified to make the analysis analytically tractable.

  5. Conserved inhibitory mechanism and competent ATP binding mode for adenylyltransferases with Fic fold.

    Directory of Open Access Journals (Sweden)

    Arnaud Goepfert

    Full Text Available The ubiquitous FIC domain is evolutionarily conserved from bacteria to human and has been shown to catalyze AMP transfer onto protein side-chain hydroxyl groups. Recently, it was predicted that most catalytically competent Fic proteins are inhibited by the presence of an inhibitory helix αinh that is provided by a cognate anti-toxin (class I, or is part of the N- or C-terminal part of the Fic protein itself (classes II and III. In vitro, inhibition is relieved by mutation of a conserved glutamate of αinh to glycine. For the class III bacterial Fic protein NmFic from Neisseria meningitidis, the inhibitory mechanism has been elucidated. Here, we extend above study by including bacterial class I and II Fic proteins VbhT from Bartonella schoenbuchensis and SoFic from Shewanella oneidensis, respectively, and the respective E->G mutants. Comparative enzymatic and crystallographic analyses show that, in all three classes, the ATP substrate binds to the wild-type FIC domains, but with the α-phosphate in disparate and non-competent orientations. In the E->G mutants, however, the tri-phosphate moiety is found reorganized to the same tightly bound structure through a unique set of hydrogen bonds with Fic signature motif residues. The γ-phosphate adopts the location that is taken by the inhibitory glutamate in wild-type resulting in an α-phosphate orientation that can be attacked in-line by a target side-chain hydroxyl group. The latter is properly registered to the Fic active center by main-chain β-interactions with the β-hairpin flap. These data indicate that the active site motif and the exposed edge of the flap are both required to form an adenylylation-competent Fic protein.

  6. Simultaneous Transverse Oscillations of a Prominence and a Filament and Longitudinal Oscillation of another Filament Induced by a Single Shock Wave

    CERN Document Server

    Shen, Yuandeng; Chen, P F; Ichimoto, Kiyoshi

    2014-01-01

    We present the first stereoscopic and Doppler observations of simultaneous transverse oscillations of a prominence and a filament and longitudinal oscillation of another filament launched by a single shock wave. Using H-alpha Doppler observations, we derive the three-dimensional oscillation velocities at different heights along the prominence axis. The results indicate that the prominence has a larger oscillation amplitude and damping time at higher altitude, but the periods at different heights are the same (i.e., 13.5 minutes). This suggests that the prominence oscillates like a linear vertical rigid body with one end anchored on the Sun. One of the filaments shows weak transverse oscillation after the passing of the shock, which is possibly due to the low altitude of the filament and the weakening (due to reflection) of the shock wave before the interaction. Large amplitude longitudinal oscillation is observed in the other filament after the passing of the shock wave. The velocity amplitude and period are ...

  7. Remote sensing for oil products on water surface via fluorescence induced by UV filaments

    Science.gov (United States)

    Sunchugasheva, E. S.; Ionin, A. A.; Mokrousova, D. V.; Seleznev, L. V.; Sinitsyn, D. V.; Geints, Yu. E.; Zemlyanov, A. A.

    2016-10-01

    Remote monitoring of water pollution, namely thin films of oil or oil products on water surface, can be carried out by laser fluorimetry. The pollutants fluorescence during its interaction with ultrashort UV laser pulses was experimentally studied in this paper. The laser pulses power was considered in a wide range of values including the filamentation regime. We compared fluorescence stimulated by femtosecond UV laser pulses with two central wavelengths (248 and 372 nm) for detection of crude oil and the following oil products: oil VM-5, oil 5W-40 and solvent WhiteSpirit. It was shown that shorter UV wavelengths are more suitable for fluorescence excitation. The spatial resolution of the fluorescence localization was no worse than 30 cm. We discuss techniques of high intensity emission delivery to the remote target as post-filamentation channels and multifilamentation beam propagation regime as well experimentally and numerically.

  8. Consequences of Femtosecond Laser Filament Generation Conditions in Standoff Laser Induced Breakdown Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, Sivanandan S.; Yeak, J.; Brumfield, Brian E.; Phillips, Mark C.

    2016-08-08

    We investigate the role of femtosecond laser focusing conditions on ablation properties and its implications on analytical merits and standoff detection applications. Femtosecond laser pulses can be used for ablation either by tightly focusing or by using filaments generated during its propagation. We evaluated the persistence of atomic, and molecular emission features as well as time evolution of the fundamental properties (temperature and density) of ablation plumes generated using different methods.

  9. Laser-Induced Ionization Efficiency Enhancement On A Filament For Thermal Ionization Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Siegfried, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-14

    The evaluation of trace Uranium and Plutonium isotope ratios for nanogram to femtogram material quantities is a vital tool for nuclear counter-proliferation and safeguard activities. Thermal Ionization Mass Spectrometry (TIMS) is generally accepted as the state of the art technology for highly accurate and ultra-trace measurements of these actinide ratios. However, the very low TIMS ionization yield (typically less than 1%) leaves much room for improvement. Enhanced ionization of Nd and Sm from a TIMS filament was demonstrated using wavelength resonance with a nanosecond (pulse width) laser operating at 10 Hz when light was directed toward the filament.1 For this study, femtosecond and picosecond laser capabilities were to be employed to study the dissociation and ionization mechanisms of actinides/lanthanides and measure the enhanced ionization of the metal of interest. Since the underlying chemistry of the actinide/lanthanide carbides produced and dissociated on a TIMS filament is not well understood, the experimental parameters affecting the photodissociation and photoionization with one and two laser beams were to be investigated.

  10. Gray Level of FIC using Zero-Mean Method

    Directory of Open Access Journals (Sweden)

    Eman A. Al-Hilo

    2014-09-01

    Full Text Available In this work, a fractal image compression (FIC based on zero-mean block matching method is adopted. In this method the mean of the range blocks is used instead of traditional offset parameter. The parameter ( has a smaller dynamic range [0,255] than the (o parameter [-255,511] which using in traditional method. This may cause large errors in some image regions (or points especially those which belong to high contrast area. Replace this factors also reduces and simplifies the computations of the affine parameters during the encoding process. The test results conducted on 24 bits/pixel gray Cat image indicated that the encoding time (7.47 sec, compression ratio (5.63 ,PSNR (35.16

  11. Solid friction between soft filaments

    CERN Document Server

    Ward, Andrew; Schwenger, Walter; Welch, David; Lau, A W C; Vitelli, Vincenzo; Mahadevan, L; Dogic, Zvonimir

    2015-01-01

    Any macroscopic deformation of a filamentous bundle is necessarily accompanied by local sliding and/or stretching of the constituent filaments. Yet the nature of the sliding friction between two aligned filaments interacting through multiple contacts remains largely unexplored. Here, by directly measuring the sliding forces between two bundled F-actin filaments, we show that these frictional forces are unexpectedly large, scale logarithmically with sliding velocity as in solid-like friction, and exhibit complex dependence on the filaments' overlap length. We also show that a reduction of the frictional force by orders of magnitude, associated with a transition from solid-like friction to Stokes' drag, can be induced by coating F-actin with polymeric brushes. Furthermore, we observe similar transitions in filamentous microtubules and bacterial flagella. Our findings demonstrate how altering a filament's elasticity, structure and interactions can be used to engineer interfilament friction and thus tune the prop...

  12. Growth-induced axial buckling of a slender elastic filament embedded in an isotropic elastic matrix

    KAUST Repository

    O'Keeffe, Stephen G.

    2013-11-01

    We investigate the problem of an axially loaded, isotropic, slender cylinder embedded in a soft, isotropic, outer elastic matrix. The cylinder undergoes uniform axial growth, whilst both the cylinder and the surrounding elastic matrix are confined between two rigid plates, so that this growth results in axial compression of the cylinder. We use two different modelling approaches to estimate the critical axial growth (that is, the amount of axial growth the cylinder is able to sustain before it buckles) and buckling wavelength of the cylinder. The first approach treats the filament and surrounding matrix as a single 3-dimensional elastic body undergoing large deformations, whilst the second approach treats the filament as a planar, elastic rod embedded in an infinite elastic foundation. By comparing the results of these two approaches, we obtain an estimate of the foundation modulus parameter, which characterises the strength of the foundation, in terms of the geometric and material properties of the system. © 2013 Elsevier Ltd. All rights reserved.

  13. Phototropin-dependent biased relocalization of cp-actin filaments can be induced even when chloroplast movement is inhibited

    OpenAIRE

    Yamada, Noboru; Suetsugu, Noriyuki; Wada, Masamitsu; Kadota, Akeo

    2011-01-01

    In a recent publication using an actin-visualized line of Arabidopsis (Ichikawa et al. 2011, ref. 11), we reported a detailed analysis with higher time resolution on the dynamics of chloroplast actin filaments (cp-actin filaments) during chloroplast avoidance movement and demonstrated a good correlation between the biased configuration of cp-actin filaments and chloroplast movement. However, we could not conclusively determine whether the reorganization of cp-actin filaments into a biased con...

  14. Femtosecond Laser Filamentation

    CERN Document Server

    Chin, See Leang

    2010-01-01

    Femtosecond Laser Filamentation gives a comprehensive review of the physics of propagation of intense femtosecond laser pulses in optical media (principally air) and the applications and challenges of this new technique. This book presents the modern understanding of the physics of femtosecond laser pulse propagation, including unusual new effects such as the self-transformation of the pulse into a white light laser pulse, intensity clamping, the physics of multiple filamentation and competition, and how filaments’ ability to melt glass leads to wave guide writing. The potential applications of laser filamentation in atmospheric sensing and the generation of other electromagnetic pulses from the UV to the radio frequency are treated, together with possible future challenges in the excitation of super-excited states of molecules. Exciting new phenomena such as filament induced ultrafast birefringence and the excitation of molecular rotational wave packets and their multiple revivals in air (gases) will also ...

  15. Peroxide accumulation and cell death in filamentous fungi induced by contact with a contestant.

    Science.gov (United States)

    Silar, Philippe

    2005-02-01

    Podospora anserina and Coprinopsis cinerea (syn. Coprinus cinereus) are endowed with a defence system able to differentiate self vs. non-self and involving the generation of peroxide. Indeed, they produce peroxide when confronted with a filamentous fungus, only in non-self confrontations. Both species are not able to recognize yeasts and show a differential response to bacteria. The accumulation of peroxides in the ascomycete Podospora anserina requires an NADPH oxidase and a MAP kinase cascade, previously shown to be involved in fruit body formation, cell differentiation and cell degeneration. Confrontation is accompanied by the death of the contestant hyphae only in specific combinations of species. As in animals and plants, data suggest that peroxide is likely involved in signalling rather than playing a direct toxic role. Fungi display more complex behaviours than generally acknowledged, i.e. they are able to recognize potential contestants and built up defence reactions involving evolutionary conserved enzymes.

  16. Zinc-Induced Polymerization of Killer-Cell Ig-like Receptor into Filaments Promotes Its Inhibitory Function at Cytotoxic Immunological Synapses.

    Science.gov (United States)

    Kumar, Santosh; Rajagopalan, Sumati; Sarkar, Pabak; Dorward, David W; Peterson, Mary E; Liao, Hsien-Shun; Guillermier, Christelle; Steinhauser, Matthew L; Vogel, Steven S; Long, Eric O

    2016-04-07

    The inhibitory function of killer cell immunoglobulin-like receptors (KIR) that bind HLA-C and block activation of human natural killer (NK) cells is dependent on zinc. We report that zinc induced the assembly of soluble KIR into filamentous polymers, as detected by electron microscopy, which depolymerized after zinc chelation. Similar KIR filaments were isolated from lysates of cells treated with zinc, and membrane protrusions enriched in zinc were detected on whole cells by scanning electron microscopy and imaging mass spectrometry. Two independent mutations in the extracellular domain of KIR, away from the HLA-C binding site, impaired zinc-driven polymerization and inhibitory function. KIR filaments formed spontaneously, without the addition of zinc, at functional inhibitory immunological synapses of NK cells with HLA-C(+) cells. Adding to the recent paradigm of signal transduction through higher order molecular assemblies, zinc-induced polymerization of inhibitory KIR represents an unusual mode of signaling by a receptor at the cell surface.

  17. Adenylylation of Gyrase and Topo IV by FicT Toxins Disrupts Bacterial DNA Topology

    Directory of Open Access Journals (Sweden)

    Alexander Harms

    2015-09-01

    Full Text Available Toxin-antitoxin (TA modules are ubiquitous molecular switches controlling bacterial growth via the release of toxins that inhibit cell proliferation. Most of these toxins interfere with protein translation, but a growing variety of other mechanisms hints at a diversity that is not yet fully appreciated. Here, we characterize a group of FIC domain proteins as toxins of the conserved and abundant FicTA family of TA modules, and we reveal that they act by suspending control of cellular DNA topology. We show that FicTs are enzymes that adenylylate DNA gyrase and topoisomerase IV, the essential bacterial type IIA topoisomerases, at their ATP-binding site. This modification inactivates both targets by blocking their ATPase activity, and, consequently, causes reversible growth arrest due to the knotting, catenation, and relaxation of cellular DNA. Our results give insight into the regulation of DNA topology and highlight the remarkable plasticity of FIC domain proteins.

  18. Characterization of type-I ELM induced filaments in the far scrape-off layer of ASDEX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, Andreas

    2008-03-18

    This thesis focuses on the characterization of filaments and their propagation in the ASDEX Upgrade tokamak. The aim is to provide experimental measurements for understanding the filament formation process and their temporal evolution, and to provide a comprehensive database for an extrapolation to future fusion devices. For this purpose, a new magnetically driven probe for filament measurements has been developed and installed in ASDEX Upgrade. The probe carries several Langmuir probes and a magnetic coil in between. The Langmuir probes allow for measurements of the radial and poloidal/toroidal propagation of filaments as well as for measurements of filament size, density, and their radial (or temporal) evolution. The magnetic coil on the filament probe allows for measurements of currents in the filaments. A set of 7 coils, measuring 3 field components at different positions along the filament, has been used to measure the magnetic signature during an ELM. The aim was, on the one hand, to study which role filaments play for the magnetic structure, and on the other hand if the parallel currents predicted by the sheath damped model could be verified. Filament temperatures have been derived and the corresponding heat transport mechanisms have been studied. (orig.)

  19. The excluded volume effect induced by poly(ethylene glycol) modulates the motility of actin filaments interacting with myosin.

    Science.gov (United States)

    Munakata, Shinsuke; Hatori, Kuniyuki

    2013-11-01

    To examine the motility of actomyosin complexes in the presence of high concentrations of polymers, we investigated the effect of poly(ethylene glycol) on the sliding velocities of actin filaments and regulated thin filaments on myosin molecules in the presence of ATP. Increased concentrations and relative molecular masses of poly(ethylene glycol) decreased the sliding velocities of actin and regulated thin filaments. The decreased ratio of velocity in regulated thin filaments at - log[Ca(2+) ] of 4 was higher than that of actin filaments. Furthermore, in the absence of Ca(2+) , regulated thin filaments were moderately motile in the presence of poly(ethylene glycol). The excluded volume change (∆V), defined as the change in water volume surrounding actomyosin during the interactions, was estimated by determining the relationship between osmotic pressure exerted by poly(ethylene glycol) and the decreased ratio of the velocities in the presence and absence of poly(ethylene glycol). The ∆V increased up to 3.7 × 10(5) Å(3) as the Mr range of poly(ethylene glycol) was increased up to 20,000. Moreover, the ∆V for regulated thin filaments was approximately two-fold higher than that of actin filaments. This finding suggests that differences in the conformation of filaments according to whether troponin-tropomyosin complexes lie on actin filaments alter the ∆V during interactions of actomyosin complexes and influence motility. © 2013 FEBS.

  20. Characterization of type-I ELM induced filaments in the far scrape-off layer of ASDEX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, Andreas

    2008-03-18

    This thesis focuses on the characterization of filaments and their propagation in the ASDEX Upgrade tokamak. The aim is to provide experimental measurements for understanding the filament formation process and their temporal evolution, and to provide a comprehensive database for an extrapolation to future fusion devices. For this purpose, a new magnetically driven probe for filament measurements has been developed and installed in ASDEX Upgrade. The probe carries several Langmuir probes and a magnetic coil in between. The Langmuir probes allow for measurements of the radial and poloidal/toroidal propagation of filaments as well as for measurements of filament size, density, and their radial (or temporal) evolution. The magnetic coil on the filament probe allows for measurements of currents in the filaments. A set of 7 coils, measuring 3 field components at different positions along the filament, has been used to measure the magnetic signature during an ELM. The aim was, on the one hand, to study which role filaments play for the magnetic structure, and on the other hand if the parallel currents predicted by the sheath damped model could be verified. Filament temperatures have been derived and the corresponding heat transport mechanisms have been studied. (orig.)

  1. Light-Induced Movements of Chloroplasts and Nuclei Are Regulated in Both Cp-Actin-Filament-Dependent and -Independent Manners in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Noriyuki Suetsugu

    Full Text Available Light-induced chloroplast movement and attachment to the plasma membrane are dependent on actin filaments. In Arabidopsis thaliana, the short actin filaments on the chloroplast envelope, cp-actin filaments, are essential for chloroplast movement and positioning. Furthermore, cp-actin-filament-mediated chloroplast movement is necessary for the strong-light-induced nuclear avoidance response. The proteins CHLOROPLAST UNUSUAL POSITIONING 1 (CHUP1, KINESIN-LIKE PROTEIN FOR ACTIN-BASED CHLOROPLAST MOVEMENT 1 (KAC1 and KAC2 are required for the generation and/or maintenance of cp-actin filaments in Arabidopsis. In land plants, CHUP1 and KAC family proteins play pivotal roles in the proper movement of chloroplasts and their attachment to the plasma membrane. Here, we report similar but distinct phenotypes in chloroplast and nuclear photorelocation movements between chup1 and kac1kac2 mutants. Measurement of chloroplast photorelocation movement indicated that kac1kac2, but not chup1, exhibited a clear strong-light-induced increase in leaf transmittance changes. The chloroplast movement in kac1kac2 depended on phototropin 2, CHUP1 and two other regulators for cp-actin filaments, PLASTID MOVEMENT IMPAIRED 1 and THRUMIN 1. Furthermore, kac1kac2 retained a weak but significant nuclear avoidance response although chup1 displayed a severe defect in the nuclear avoidance response. The kac1kac2chup1 triple mutant was completely defective in both chloroplast and nuclear avoidance responses. These results indicate that CHUP1 and the KACs function somewhat independently, but interdependently mediate both chloroplast and nuclear photorelocation movements.

  2. Light-Induced Movements of Chloroplasts and Nuclei Are Regulated in Both Cp-Actin-Filament-Dependent and -Independent Manners in Arabidopsis thaliana.

    Science.gov (United States)

    Suetsugu, Noriyuki; Higa, Takeshi; Gotoh, Eiji; Wada, Masamitsu

    2016-01-01

    Light-induced chloroplast movement and attachment to the plasma membrane are dependent on actin filaments. In Arabidopsis thaliana, the short actin filaments on the chloroplast envelope, cp-actin filaments, are essential for chloroplast movement and positioning. Furthermore, cp-actin-filament-mediated chloroplast movement is necessary for the strong-light-induced nuclear avoidance response. The proteins CHLOROPLAST UNUSUAL POSITIONING 1 (CHUP1), KINESIN-LIKE PROTEIN FOR ACTIN-BASED CHLOROPLAST MOVEMENT 1 (KAC1) and KAC2 are required for the generation and/or maintenance of cp-actin filaments in Arabidopsis. In land plants, CHUP1 and KAC family proteins play pivotal roles in the proper movement of chloroplasts and their attachment to the plasma membrane. Here, we report similar but distinct phenotypes in chloroplast and nuclear photorelocation movements between chup1 and kac1kac2 mutants. Measurement of chloroplast photorelocation movement indicated that kac1kac2, but not chup1, exhibited a clear strong-light-induced increase in leaf transmittance changes. The chloroplast movement in kac1kac2 depended on phototropin 2, CHUP1 and two other regulators for cp-actin filaments, PLASTID MOVEMENT IMPAIRED 1 and THRUMIN 1. Furthermore, kac1kac2 retained a weak but significant nuclear avoidance response although chup1 displayed a severe defect in the nuclear avoidance response. The kac1kac2chup1 triple mutant was completely defective in both chloroplast and nuclear avoidance responses. These results indicate that CHUP1 and the KACs function somewhat independently, but interdependently mediate both chloroplast and nuclear photorelocation movements.

  3. Ultraviolet-B induced damage to photosystem II in intact filaments of Spirulina platensis

    Energy Technology Data Exchange (ETDEWEB)

    Kolli, B.K.; Tiwari, S.; Mohanty, P. [Jawaharlal Nehru Univ., New Delhi (India). Schoof of Life Sciences

    1998-05-01

    When Spirulina platensis filaments were exposed to 0.75 mW x m{sup -2} x s{sup -1} of ultraviolet-B radiation (the ultraviolet-B radiation under clear sky condition is {proportional_to}1.0 mW x m{sup -2} x s{sup -1}), an inhibition in photosystem II activity was observed, the inhibition being 90% after 90 min exposure. Upon exposure to ultraviolet-B, the room temperature emission characteristics of Spirulina cells were altered when excited with light primarily absorbed by chlorophyll a or phycobilisomes. When the cells were exposed for 3 h the emission at 685 nm (F{sub 685}), when excited at 440 nm (primarily chlorophyll a absorption), was enhanced compared to 715 nm (F{sub 715}) band of photosystem I suggesting a decrease in energy transfer from photosystem II to photosystem I. Similarly, when the cells were excited at 580 nm (primarily the phycobilisomes), the ratio of emission intensity at 685 nm (F{sub 685}) to that of 655 nm (F{sub 655}) was decreased in the exposed cells. This change in emission characteristics seems to be linked with the uncoupling of the energy transfer from all phycocyanin to chlorophyll a of photosystem II. A small shift in emission peak positions was also indicated when excited either at 440 nm or 580 nm. (orig./AJ)

  4. Calcium-induced movement of troponin-I relative to actin in skeletal muscle thin filaments.

    Science.gov (United States)

    Tao, T; Gong, B J; Leavis, P C

    1990-03-16

    The role of troponin-I (the inhibitory subunit of troponin) in the regulation by Ca2+ of skeletal muscle contraction was investigated with resonance energy transfer and photo cross-linking techniques. The effect of Ca2+ on the proximity of troponin-I to actin in reconstituted rabbit skeletal thin filaments was determined. The distance between the cysteine residue at position 133 (Cys133) of troponin-I and Cys374 of actin increases by approximately 15 angstroms on binding of Ca2+ to troponin-C. Also, troponin-I labeled at Cys133 with benzophenone-4-maleimide could be photo cross-linked to actin in the absence of Ca2+, but not in its presence. These results suggest that troponin-I is attached to actin in the Ca2(+)-free or relaxed state of muscle, and that it detaches from actin on Ca2+ activation of contraction. Thus, troponin-I may function as a Ca2(+)-dependent molecular switch in regulation of skeletal muscle contraction.

  5. The GraFIC TM Facility Management Software [TM = Trademark Symbol

    Energy Technology Data Exchange (ETDEWEB)

    Younkin, J.R.; Dunigan, J.J.; Gaby, J.E.; Hickerson, T.W.; Pickett, C.A.

    2002-06-01

    The Graphical Facility Information System{trademark} (GraFIC{trademark}) is an intelligent facility and information management system that provides near real time, verifiable status of safeguarded materials in a nuclear storage facility. GraFIC{trademark} is a versatile software package that is designed to operate in a distributed computing environment and to provide item and facility activity information to an unlimited number of authorized clients. Recent extensions to GraFIC{trademark} include the ability to link graphical entities to multimedia documents, interfaces to multiple material control and accountability systems, and alternate data entry and operator interaction mechanisms. Relevant multimedia documents such as still images and iPIX{trademark} immersive images can be summoned on demand from their icons on floor plans. An iPIX{trademark} image server, equipped with the appropriate sensors can signal GraFIC{trademark} that an event that warrants the review of a series of saved iPIX{trademark} images has occurred. GraFIC{trademark} provides mechanisms for presenting information obtained from sensor-based monitoring systems and/or other information systems in a common, easy-to-use graphical format. GraFIC{trademark} was initially integrated with the Continuous Automated Vault Inventory System's (CAVIS{trademark} ) suite of rugged, low-cost sensors that remotely monitor the physical and/or assigned attributes associated with stored nuclear materials. GraFIC{trademark} can now interface with the ReflectoActive Seals{trademark} (RASeals) System. The framework designed for the RASeals interface is suitable for integrating with other systems, such as SmartShelf{trademark} . GraFIC{trademark} can import existing data for stored material from other information systems. By retrieving existing information from other information systems, the expense, effort, and possible inaccuracies associated with manual entry are eliminated. Another data entry method involves

  6. The Frequentist Information Criterion (FIC): The unification of information-based and frequentist inference

    CERN Document Server

    LaMont, Colin H

    2015-01-01

    The failure of the information-based Akaike Information Criterion (AIC) in the context of singular models can be rectified by the definition of a Frequentist Information Criterion (FIC). FIC applies a frequentist approximation to the computation of the model complexity, which can be estimated analytically in many contexts. Like AIC, FIC can be understood as an unbiased estimator of the model predictive performance and is therefore identical to AIC for regular models in the large-observation-number limit ($N\\rightarrow \\infty$) . In the presence of unidentifiable parameters, the complexity exhibits a more general, non-AIC-like scaling ($\\gg N^0$). For instance, both BIC-like ($\\propto\\log N$) and Hannan-Quinn-like ($\\propto \\log \\log N$) scaling with observation number $N$ are observed. Unlike the Bayesian model selection approach, FIC is free from {\\it ad hoc} prior probability distributions and appears to be widely applicable to model selection problems. Finally we demonstrate that FIC (information-based inf...

  7. Engagement of CD81 induces ezrin tyrosine phosphorylation and its cellular redistribution with filamentous actin

    Energy Technology Data Exchange (ETDEWEB)

    Coffey, Greg P.; Rajapaksa, Ranjani; Liu, Raymond; Sharpe, Orr; Kuo, Chiung-Chi; Wald Krauss, Sharon; Sagi, Yael; Davis, R. Eric; Staudt, Louis M.; Sharman, Jeff P.; Robinson, William H.; Levy, Shoshana

    2009-06-09

    CD81 is a tetraspanin family member involved in diverse cellular interactions in the immune and nervous systems and in cell fusion events. However, the mechanism of action of CD81 and of other tetraspanins has not been defined. We reasoned that identifying signaling molecules downstream of CD81 would provide mechanistic clues. We engaged CD81 on the surface of Blymphocytes and identified the induced tyrosine-phosphorylated proteins by mass spectrometry. This analysis showed that the most prominent tyrosine phosphorylated protein was ezrin, an actin binding protein and a member of the ezrin-radixin-moesin family. We also found that CD81 engagement induces spleen tyrosine kinase (Syk) and that Syk was involved in tyrosine phosphorylation of ezrin. Ezrin colocalized with CD81 and F-actin upon stimulation and this association was disrupted when Syk activation was blocked. Taken together, these studies suggest a model in which CD81 interfaces between the plasma membrane and the cytoskeleton by activating Syk, mobilizing ezrin, and recruiting F-actin to facilitate cytoskeletal reorganization and cell signaling. This may be a mechanism explaining the pleiotropic effects induced in response to stimulating cells by anti-CD81 antibodies or by the hepatitis C virus, which uses this molecule as its key receptor.

  8. Morphological changes of the filamentous fungus Mucor mucedo and inhibition of chitin synthase activity induced by anethole.

    Science.gov (United States)

    Yutani, Masahiro; Hashimoto, Yukie; Ogita, Akira; Kubo, Isao; Tanaka, Toshio; Fujita, Ken-ichi

    2011-11-01

    trans-Anethole (anethole), a major component of anise oil, has a broad antimicrobial spectrum with antimicrobial activity relatively weaker than those of well-known antibiotics, and significantly enhances the antifungal activity of polygodial and dodecanol against the baker's yeast Saccharomyces cerevisiae and human pathogenic yeast Candida albicans. However, the antifungal mechanism of anethole is unresolved. Anethole demonstrated antifungal activity against the filamentous fungus, Mucor mucedo IFO 7684, accompanied by hyphal morphological changes such as swollen hyphae at the tips. Its minimum growth inhibitory concentration was 0.625 mM. A hyperosmotic condition (1.2 M sorbitol) restricted the induction of morphological changes, while hypoosmotic treatment (distilled water) induced bursting of hyphal tips and leakage of cytoplasmic constituents. Furthermore, anethole dose-dependently inhibited chitin synthase (CHS) activity in permeabilized hyphae in an uncompetitive manner. These results suggest that the morphological changes of M. mucedo could be explained by the fragility of cell walls caused by CHS inhibition.

  9. High-energy-throughput pulse compression by off-axis group-delay compensation in a laser-induced filament

    Energy Technology Data Exchange (ETDEWEB)

    Voronin, A. A. [Physics Department, International Laser Center, M. V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Alisauskas, S.; Muecke, O. D.; Pugzlys, A.; Baltuska, A. [Photonics Institute, Vienna University of Technology, Gusshausstrasse 27-387, 1040 Vienna (Austria); Zheltikov, A. M. [Physics Department, International Laser Center, M. V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843-3257 (United States)

    2011-08-15

    Off-axial beam dynamics of ultrashort laser pulses in a filament enable a radical energy-throughput improvement for filamentation-assisted pulse compression. We identify regimes where a weakly diverging wave, produced on the trailing edge of the pulse, catches up with a strongly diverging component, arising in the central part of the pulse, allowing sub-100-fs millijoule infrared laser pulses to be compressed to 20-25-fs pulse widths with energy throughputs in excess of 70%. Theoretical predictions have been verified by experimental results on filamentation-assisted compression of 70-fs, 1.5-{mu}m laser pulses in high-pressure argon.

  10. Resonantly enhanced filamentation in gases

    CERN Document Server

    Doussot, J; Billard, F; Béjot, P; Faucher, O

    2016-01-01

    In this Letter, a low-loss Kerr-driven optical filament in Krypton gas is experimentally reported in the ultraviolet. The experimental findings are supported by ab initio quantum calculations describing the atomic optical response. Higher-order Kerr effect induced by three-photon resonant transitions is identified as the underlying physical mechanism responsible for the intensity stabilization during the filamentation process, while ionization plays only a minor role. This result goes beyond the commonly-admitted paradigm of filamentation, in which ionization is a necessary condition of the filament intensity clamping. At resonance, it is also experimentally demonstrated that the filament length is greatly extended because of a strong decrease of the optical losses.

  11. Oral Immunization of Rabbits with S. enterica Typhimurium Expressing Neisseria gonorrhoeae Filamentous Phage Φ6 Induces Bactericidal Antibodies Against N. gonorrhoeae.

    Science.gov (United States)

    Piekarowicz, Andrzej; Kłyż, Aneta; Majchrzak, Michał; Stein, Daniel C

    2016-03-04

    All Neisseria gonorrhoeae strains whose DNA sequences have been determined possess filamentous phage DNA sequences. To ascertain if phage encoded proteins could form the basis of a gonococcal vaccine, rabbits were orally infected with S. enterica Typhimurium strain χ3987 harboring phagemid NgoΦ6 fm. The elicited sera contained large quantities of anti-phage IgG and IgA antibodies that bound to the surface of N. gonorrhoeae cells, as shown by indirect fluorescent analysis and flow cytometry. The elicited sera was able to bind to several phage proteins. The sera also had bactericidal activity. These data demonstrate that N. gonorrhoeae filamentous phage can induce antibodies with anti-gonococcal activity and that phage proteins may be a candidate for vaccine development.

  12. The Contribution of Kawada to the Analytical Solution for the Velocity Induced by a Helical Vortex Filament and Modern Applications of Helical Vortices

    DEFF Research Database (Denmark)

    Fukumoto, Yasuhide; Okulov, Valery; Wood, David H.

    2017-01-01

    Currently, the analytical form of the velocity field induced by a helical vortex filament is well known as Hardin’s solution (1982). But essentially the same result had been obtained by a Japanese scientist Sandi Kawada, which predates Hardin by as long as 46 years. Kawada (1936) provided a compr...... a comprehensive treatment of deriving the induced velocity by helical vortices with a view to applying it to the propeller theory. This paper recollects Kawada’s contribution, together with his life devoted to lead the Japanese aeronautical engineering in the time of its dawning....

  13. IFN-γ-induced increase in the mobility of MHC class II compartments in astrocytes depends on intermediate filaments

    Directory of Open Access Journals (Sweden)

    Vardjan Nina

    2012-06-01

    Full Text Available Abstract Background In immune-mediated diseases of the central nervous system, astrocytes exposed to interferon-γ (IFN-γ can express major histocompatibility complex (MHC class II molecules and antigens on their surface. MHC class II molecules are thought to be delivered to the cell surface by membrane-bound vesicles. However, the characteristics and dynamics of this vesicular traffic are unclear, particularly in reactive astrocytes, which overexpress intermediate filament (IF proteins that may affect trafficking. The aim of this study was to determine the mobility of MHC class II vesicles in wild-type (WT astrocytes and in astrocytes devoid of IFs. Methods The identity of MHC class II compartments in WT and IF-deficient astrocytes 48 h after IFN-γ activation was determined immunocytochemically by using confocal microscopy. Time-lapse confocal imaging and Alexa Fluor546-dextran labeling of late endosomes/lysosomes in IFN-γ treated cells was used to characterize the motion of MHC class II vesicles. The mobility of vesicles was analyzed using ParticleTR software. Results Confocal imaging of primary cultures of WT and IF-deficient astrocytes revealed IFN-γ induced MHC class II expression in late endosomes/lysosomes, which were specifically labeled with Alexa Fluor546-conjugated dextran. Live imaging revealed faster movement of dextran-positive vesicles in IFN-γ-treated than in untreated astrocytes. Vesicle mobility was lower in IFN-γ-treated IF-deficient astrocytes than in WT astrocytes. Thus, the IFN-γ-induced increase in the mobility of MHC class II compartments is IF-dependent. Conclusions Since reactivity of astrocytes is a hallmark of many CNS pathologies, it is likely that the up-regulation of IFs under such conditions allows a faster and therefore a more efficient delivery of MHC class II molecules to the cell surface. In vivo, such regulatory mechanisms may enable antigen-presenting reactive astrocytes to respond rapidly and in a

  14. Triggering filamentation using turbulence

    CERN Document Server

    Eeltink, D; Marchiando, N; Hermelin, S; Gateau, J; Brunetti, M; Wolf, J P; Kasparian, J

    2016-01-01

    We study the triggering of single filaments due to turbulence in the beam path for a laser of power below the filamenting threshold. Turbulence can act as a switch between the beam not filamenting and producing single filaments. This 'positive' effect of turbulence on the filament probability, combined with our observation of off-axis filaments suggests the underlying mechanism is modulation instability caused by transverse perturbations. We hereby experimentally explore the interaction of modulation instability and turbulence, commonly associated with multiple-filaments, in the single-filament regime.

  15. The Caenorhabditis elegans Protein FIC-1 Is an AMPylase That Covalently Modifies Heat-Shock 70 Family Proteins, Translation Elongation Factors and Histones

    Science.gov (United States)

    Truttmann, Matthias C.; Guo, Xuanzong; Engert, Christoph; Schwartz, Thomas U.; Ploegh, Hidde L.

    2016-01-01

    Protein AMPylation by Fic domain-containing proteins (Fic proteins) is an ancient and conserved post-translational modification of mostly unexplored significance. Here we characterize the Caenorhabditis elegans Fic protein FIC-1 in vitro and in vivo. FIC-1 is an AMPylase that localizes to the nuclear surface and modifies core histones H2 and H3 as well as heat shock protein 70 family members and translation elongation factors. The three-dimensional structure of FIC-1 is similar to that of its human ortholog, HYPE, with 38% sequence identity. We identify a link between FIC-1-mediated AMPylation and susceptibility to the pathogen Pseudomonas aeruginosa, establishing a connection between AMPylation and innate immunity in C. elegans. PMID:27138431

  16. The Caenorhabditis elegans Protein FIC-1 Is an AMPylase That Covalently Modifies Heat-Shock 70 Family Proteins, Translation Elongation Factors and Histones.

    Science.gov (United States)

    Truttmann, Matthias C; Cruz, Victor E; Guo, Xuanzong; Engert, Christoph; Schwartz, Thomas U; Ploegh, Hidde L

    2016-05-01

    Protein AMPylation by Fic domain-containing proteins (Fic proteins) is an ancient and conserved post-translational modification of mostly unexplored significance. Here we characterize the Caenorhabditis elegans Fic protein FIC-1 in vitro and in vivo. FIC-1 is an AMPylase that localizes to the nuclear surface and modifies core histones H2 and H3 as well as heat shock protein 70 family members and translation elongation factors. The three-dimensional structure of FIC-1 is similar to that of its human ortholog, HYPE, with 38% sequence identity. We identify a link between FIC-1-mediated AMPylation and susceptibility to the pathogen Pseudomonas aeruginosa, establishing a connection between AMPylation and innate immunity in C. elegans.

  17. Filament-induced visible-to-mid-IR supercontinuum in a ZnSe crystal: Towards multi-octave supercontinuum absorption spectroscopy

    Science.gov (United States)

    Mouawad, O.; Béjot, P.; Billard, F.; Mathey, P.; Kibler, B.; Désévédavy, F.; Gadret, G.; Jules, J.-C.; Faucher, O.; Smektala, F.

    2016-10-01

    We report on the generation of multiple-octave supercontinuum laser source spanning from 0.5 μm to 11 μm induced by multi-filamentation in a ZnSe crystal. The generated supercontinuum is both spatially and spectrally characterized. It is then exploited in a proof-of-principle experiment for methane spectroscopy measurements by means of the supercontinuum absorption spectroscopy technique. The entire absorption spectrum is successfully recorded within the whole spectral bandwidth of the supercontinuum. Experimental results are in fairly good agreement with the HITRAN database, confirming the reliability and stability over several hours of the generated supercontinuum.

  18. Dielectric barrier discharges with steep voltage rise: mapping of atomic nitrogen in single filaments measured by laser-induced fluorescence spectroscopy

    Science.gov (United States)

    Lukas, C.; Spaan, M.; Schulz-von der Gathen, V.; Thomson, M.; Wegst, R.; Döbele, H. F.; Neiger, M.

    2001-08-01

    Space and time resolved relative atomic density distributions of nitrogen have been measured for the first time at a single filament within a dielectric barrier discharge (DBD) reactor with submillimetre radial dimensions. Two-photon-Absorption Laser-Induced Fluorescence (TALIF) spectroscopy of atomic nitrogen using radiation at λ = 206.7 nm is applied to a DBD with fast rising voltage amplitudes. The decay time of the atomic nitrogen density depends strongly on the position within the discharge and the distance from the dielectric where the lifetime is maximum. Admixed oxygen leads to an increase of the N density decay by an order of magnitude even at small fractions.

  19. Da TV ao livro: desdobramentos da ficção televisiva brasileira

    Directory of Open Access Journals (Sweden)

    Sandra Reimão

    2011-08-01

    Full Text Available Esse estudo enfoca a publicação, no Brasil, de livros que se originaram a partir de obras da ficção televisiva nacional. Detemo-nos em publicações posteriores ao ano 2000 vinculadas a produções da Rede Globo de Televisão. Pelo nosso levantamento verificamos que os livros advindos da ficção televisiva publicados atualmente podem ser englobados em três grandes perfis editoriais: 1 adaptações romanceadas; 2 informativos: grupo amplo de publicações atreladas a informações históricas, geográficas ou turísticas de algum fato ou lugar referido em obras teledramatúrgicas; 3 roteiros e registros das gravações. Nosso intuito é discutir os significados culturais e educativos desses livros.

  20. Nuclear Storage Facility Inventory and Information Management using the GraFIC Software.

    Energy Technology Data Exchange (ETDEWEB)

    Hickerson, T.W.

    1999-05-04

    Oak Ridge has developed an intelligent facility and information management system to provide near real time, verifiable status of safeguarded materials in a nuclear storage facility. The Graphical Facility Information System (GraFIC{trademark}) is a versatile software package designed to operate in a distributed computing environment. GraFIC{trademark} is integrated with a suite of rugged, low-cost sensors that remotely monitor the physical and/or assigned attributes associated with stored nuclear materials and reports item and facility activity to an unlimited number of authorized clients. The software also contains facility management tools to assist with space planning, record management, item location, and a variety of other facilities needs.

  1. The effects of pulse cycloheximide treatments on the light-induced recovery of mitotic divisions in antheridial filaments of Chara vulgaris

    Directory of Open Access Journals (Sweden)

    Maria Kwiatkowska

    2014-01-01

    Full Text Available Within the proliferative period of spermatogenesis in Chara vulgaris, the progression throughout successive cell divisions in antheridial filaments is greatly influenced by changes in photoperiodic conditions. The extended (4-day period of total darkness brings about cell cycle arrest in the early G2 phase. The recovery of mitosis requires about 20 hours of exposition to light. In the present study, a series of 8 pulse incubations of plants in cycloheximide (Cx; 2.5 mg/I, 2.5 h each pulse were performed within the period elapsing till the resumption of mitotic divisions. Depending on the time of treatment, the effects induced by Cx vary considerably. Within the first 10 hs of exposition to light, incubations with Cx result in the delays of mitoses; within the period between the 10th and the 17th h, mitotic divisions become blocked, and, following the 17.5 h of light-induced recovery, no influence of Cx is noticed on mitotic activity, as compared with the untreaed control plants. The obtained results provide a starting point for the characteristic of proteins synthesized during the G2 phase and a preliminary study on those mechanisms, which become engaged in the regulation of the G1-deficient cell cycle evidenced in antheridial filaments of Chara.

  2. 由均匀运动双螺旋涡丝诱导的流场的解析解%Analytical Solution of the Flow Field Induced by the Uniformly Moving Double Helical Vortex Filaments

    Institute of Scientific and Technical Information of China (English)

    刘翔; 黄其柏; 廖道训; 温国珍

    2005-01-01

    The analytical expressions was deduced for the inviscid flow field induced by the double vortex filaments that move uniformly and rigidly without change of its form in a cylindrical tube, where the vortex filaments rotate around its axial with a constant angular velocity and translates along its axial with a constant transferal velocity. It is a key of solving problem to set up a moving cylindrical coordinate system together with the vortex filaments motion, in which the relative velocity field is presumed to be time-independent and with helical symmetry. The result shows that the absolute velocity field and pressure field are all time-periodic functions, and may degenerate into a time-independent field when the helical vortex filaments slip along the filaments themselves or is immobile. The calculation results at the location of pressure peaks and valleys on pipe wall are accordant with experimental results. When the cylindrical pipe radius tends to infinitely large quantity, it is also concluded that the double helical vortex filaments induce flow field in an unbound space.

  3. Photoelectron Emission from Metal Surfaces Induced by VUV-emission of Filament Driven Hydrogen Arc Discharge Plasma

    CERN Document Server

    Laulainen, J; Koivisto, H; Komppula, J; Tarvainen, O

    2015-01-01

    Photoelectron emission measurements have been performed using a filament-driven multi-cusp arc discharge volume production H^- ion source (LIISA). It has been found that photoelectron currents obtained with Al, Cu, Mo, Ta and stainless steel (SAE 304) are on the same order of magnitude. The photoelectron currents depend linearly on the discharge power. It is shown experimentally that photoelectron emission is significant only in the short wavelength range of hydrogen spectrum due to the energy dependence of the quantum efficiency. It is estimated from the measured data that the maximum photoelectron flux from plasma chamber walls is on the order of 1 A per kW of discharge power.

  4. Photoelectron emission from metal surfaces induced by VUV-emission of filament driven hydrogen arc discharge plasma

    Science.gov (United States)

    Laulainen, J.; Kalvas, T.; Koivisto, H.; Komppula, J.; Tarvainen, O.

    2015-04-01

    Photoelectron emission measurements have been performed using a filament-driven multi-cusp arc discharge volume production H- ion source (LIISA). It has been found that photoelectron currents obtained with Al, Cu, Mo, Ta and stainless steel (SAE 304) are on the same order of magnitude. The photoelectron currents depend linearly on the discharge power. It is shown experimentally that photoelectron emission is significant only in the short wavelength range of hydrogen spectrum due to the energy dependence of the quantum efficiency. It is estimated from the measured data that the maximum photoelectron flux from plasma chamber walls is on the order of 1 A per kW of discharge power.

  5. Airborne acrolein induces keratin-8 (Ser-73) hyperphosphorylation and intermediate filament ubiquitination in bronchiolar lung cell monolayers.

    Science.gov (United States)

    Burcham, Philip C; Raso, Albert; Henry, Peter J

    2014-05-07

    The combustion product acrolein is a key mediator of pulmonary edema in victims of smoke inhalation injury. Since studying acrolein toxicity in conventional in vitro systems is complicated by reactivity with nucleophilic culture media constituents, we explored an exposure system which delivers airborne acrolein directly to lung cell monolayers at the air-liquid interface. Calu-3 lung adenocarcinoma cells were maintained on membrane inserts such that the basal surface was bathed in nucleophile-free media while the upper surface remained in contact with acrolein-containing air. Cells were exposed to airborne acrolein for 30 min before they were allowed to recover in fresh media, with cell sampling at defined time points to allow evaluation of toxicity and protein damage. After prior exposure to acrolein, cell ATP levels remained close to controls for 4h but decreased in an exposure-dependent manner by 24h. A loss of transepithelial electrical resistance and increased permeability to fluorescein isothiocyanate-labeled dextran preceded ATP loss. Use of antibody arrays to monitor protein expression in exposed monolayers identified strong upregulation of phospho-keratin-8 (Ser(73)) as an early consequence of acrolein exposure. These changes were accompanied by chemical damage to keratin-8 and other intermediate filament family members, while acrolein exposure also resulted in controlled ubiquitination of high mass proteins within the intermediate filament extracts. These findings confirm the usefulness of systems allowing delivery of airborne smoke constituents to lung cell monolayers during studies of the molecular basis for acute smoke intoxication injury.

  6. Photoelectron emission from metal surfaces induced by VUV-emission of filament driven hydrogen arc discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Laulainen, J.; Kalvas, T.; Koivisto, H.; Komppula, J.; Tarvainen, O. [University of Jyväskylä, Department of Physics (Finland)

    2015-04-08

    Photoelectron emission measurements have been performed using a filament-driven multi-cusp arc discharge volume production H{sup −} ion source (LIISA). It has been found that photoelectron currents obtained with Al, Cu, Mo, Ta and stainless steel (SAE 304) are on the same order of magnitude. The photoelectron currents depend linearly on the discharge power. It is shown experimentally that photoelectron emission is significant only in the short wavelength range of hydrogen spectrum due to the energy dependence of the quantum efficiency. It is estimated from the measured data that the maximum photoelectron flux from plasma chamber walls is on the order of 1 A per kW of discharge power.

  7. Filamentation in Laser Wakefields

    Science.gov (United States)

    Los, Eva; Trines, Raoul; Silva, Luis; Bingham, Robert

    2016-10-01

    Laser filamentation instability is observed in plasma wakefields with sub-critical densities, and in high density inertial fusion plasmas. This leads to non-uniform acceleration or compression respectively. Here, we present simulation results on laser filamentation in plasma wakefields. The 2-D simulations are carried out using the particle-in-cell code Osiris. The filament intensity was found to increase exponentially before saturating. The maximum amplitude to which the highest intensity filament grew for a specific set of parameters was also recorded, and plotted against a corresponding parameter value. Clear, positively correlated linear trends were established between plasma density, transverse wavenumber k, laser pulse amplitude and maximum filament amplitude. Plasma density and maximum filament amplitude also showed a positive correlation, which saturated after a certain plasma density. Pulse duration and interaction length did not affect either filament intensity or transverse k value in a predictable manner. There was no discernible trend between pulse amplitude and filament width.

  8. Ultrastructure of cells after reversible dark-induced blocking of mitotic divisions in antheridial filaments of Chara vulgaris L.

    Directory of Open Access Journals (Sweden)

    Maria Kwiatkowska

    2014-01-01

    Full Text Available As compared with the control plants cultured under photoperiodic L : D = =14 : 10 conditions (K w i a t k o w s k a, M a s z e w s k i, 1978, the ultrastructure of nuclei -in cells blocked by a 5 day exposure to continuous darkness is characterized by homogenous arrangement. This homogeneity is maintained in all generations of antheridial filaments irrespective of cell length, which in the controls, being directly correlated with particular type of nuclear structure, may serve as a precise indicator of a given stage of interphase. From similarities in both the spatial distribution and content of condensed chromatin in is concluded that the block of the cell cycle is imposed at the beginning of the G2 phase. On comparing these cells with the early G2 period (stage VII in the control plants, marked changes in the structure of nucleoli were found. They decrease in size by half owing to the complete decline of granular component. The area occupied by endoplasmic reticulum undergoes a 50% reduction. The decrease in the activity of Golgi apparatus expressed by a drop in number of smooth vesicles surrounding a single dictyosome is found to parallel the limited rate of cell growth. The number of coated vesicles and cisterns of dictyosome slightly increases. Mitochondria show typical condensed configuration with dense matrices and swollen cristae, while in the control orthodox forms are prevailing. The mean size of mitochondria is smaller, but their number exceeds that of the control plants. The surface area of mitochondrial profiles is found to remain constant proportion of the cytoplasm section, e.g., about 3%. Dark-cultured antheridial filaments show absolute decline of lipid droplets. No differences were found in structure of plastids and vacuols, as well as in number of ribosomes in cytoplasm surface unit.

  9. Presentació Monogràfic 1: Didàctica del Patrimoni

    OpenAIRE

    Fernàndez, Magda

    2002-01-01

    El concepte de patrimoni, paraula complexa i polisèmica, ha anat variant al llarg del temps gràcies al fet que no és un concepte tancat. Tot el contrari; és un concepte obert que permet noves interpretacions lligades tant als canvis socials com a l"aportació de noves disciplines, les quals han contribuït a la diversificació del concepte de patrimoni en si mateix i al servei de l"educació. Quan se"ns va demanar que coordinéssim un monogràfic sobre didàctica del patrimoni, vam pensar a presenta...

  10. Solar Features - Prominences and Filaments - Filaments

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Filaments are formed in magnetic loops that hold relatively cool, dense gas suspended above the surface of the Sun (David Hathaway/NASA)

  11. Large-Scale Patterns of Filament Channels and Filaments

    Science.gov (United States)

    Mackay, Duncan

    2016-07-01

    In this review the properties and large-scale patterns of filament channels and filaments will be considered. Initially, the global formation locations of filament channels and filaments are discussed, along with their hemispheric pattern. Next, observations of the formation of filament channels and filaments are described where two opposing views are considered. Finally, the wide range of models that have been constructed to consider the formation of filament channels and filaments over long time-scales are described, along with the origin of the hemispheric pattern of filaments.

  12. Actin filament attachments for sustained motility in vitro are maintained by filament bundling.

    Directory of Open Access Journals (Sweden)

    Xiaohua Hu

    Full Text Available We reconstructed cellular motility in vitro from individual proteins to investigate how actin filaments are organized at the leading edge. Using total internal reflection fluorescence microscopy of actin filaments, we tested how profilin, Arp2/3, and capping protein (CP function together to propel thin glass nanofibers or beads coated with N-WASP WCA domains. Thin nanofibers produced wide comet tails that showed more structural variation in actin filament organization than did bead substrates. During sustained motility, physiological concentrations of Mg(2+ generated actin filament bundles that processively attached to the nanofiber. Reduction of total Mg(2+ abolished particle motility and actin attachment to the particle surface without affecting actin polymerization, Arp2/3 nucleation, or filament capping. Analysis of similar motility of microspheres showed that loss of filament bundling did not affect actin shell formation or symmetry breaking but eliminated sustained attachments between the comet tail and the particle surface. Addition of Mg(2+, Lys-Lys(2+, or fascin restored both comet tail attachment and sustained particle motility in low Mg(2+ buffers. TIRF microscopic analysis of filaments captured by WCA-coated beads in the absence of Arp2/3, profilin, and CP showed that filament bundling by polycation or fascin addition increased barbed end capture by WCA domains. We propose a model in which CP directs barbed ends toward the leading edge and polycation-induced filament bundling sustains processive barbed end attachment to the leading edge.

  13. Tunnel ionization, population trapping, filamentation and applications

    Science.gov (United States)

    Leang Chin, See; Xu, Huailiang

    2016-11-01

    The advances in femtosecond Ti-sapphire laser technology have led to the discovery of a profusion of new physics. This review starts with a brief historical account of the experimental realization of tunnel ionization, followed by high harmonic generation and the prediction of attosecond pulses. Then, the unique phenomenon of dynamic population trapping during the ionization of atoms and molecules in intense laser fields is introduced. One of the consequences of population trapping in the highly excited states is the neutral dissociation into simple molecular fragments which fluoresce. Such fluorescence could be amplified in femtosecond laser filamentation in gases. The experimental observations of filament-induced fluorescence and lasing in the atmosphere and combustion flames are given. Excitation of molecular rotational wave packets (molecular alignment) and their relaxation and revival in a gas filament are described. Furthermore, filament-induced condensation and precipitation inside a cloud chamber is explained. Lastly, a summary and future outlook is given.

  14. Histophilus somni IbpA Fic cytotoxin is conserved in disease strains and most carrier strains from cattle, sheep and bison.

    Science.gov (United States)

    Zekarias, B; O'Toole, D; Lehmann, J; Corbeil, L B

    2011-04-21

    Histophilus somni causes bovine pneumonia, septicemia, myocarditis, thrombotic meningoencephalitis and arthritis, as well as a genital or upper respiratory carrier state in normal animals. However, differences in virulence factors among strains are not well studied. The surface and secreted immunoglobulin binding protein A (IbpA) Fic motif of H. somni causes bovine alveolar type 2 (BAT2) cells to retract, allowing virulent bacteria to cross the alveolar monolayer. Because H. somni IbpA is an important virulence factor, its presence was evaluated in different strains from cattle, sheep and bison to define whether there are syndrome specific markers and whether antigenic/molecular/functional conservation occurs. A few preputial carrier strains lacked IbpA by Western blotting but all other tested disease or carrier strains were IbpA positive. These positive strains had either both IbpA DR1/Fic and IbpA DR2/Fic or only IbpA DR2/Fic by PCR. IbpA Fic mediated cytotoxicity for BAT2 cells and sequence analysis of IbpA DR2/Fic from selected strains revealed conservation of sequence and function in disease and IbpA positive carrier strains. Passive protection of mice against H. somni septicemia with antibody to IbpA DR2/Fic, along with previous data, indicates that the IbpA DR1/Fic and/or DR2/Fic domains are candidate vaccine antigens for protection against many strains of H. somni. Since IbpA DR2/Fic is conserved in most carrier strains, they may be virulent if introduced to susceptible animals at susceptible sites. Conservation of the protective IbpA antigen in all disease isolates tested is encouraging for development of protective vaccines and diagnostic assays. Copyright © 2010 Elsevier B.V. All rights reserved.

  15. Pràctica final de l'assignatura "Disseny Gràfic" (Grau de Multimèdia)

    OpenAIRE

    2010-01-01

    Pràctica final de l'assignatura "Disseny Gràfic" (Grau de Multimèdia). Final practice of the "Graphic Design" course (Degree of Multimedia). Práctica final de la asignatura "Diseño Gráfico" (Grado de Multimedia).

  16. O fato e a fantasia: imagens dissimuladamente documentais que se revelam ficção

    Directory of Open Access Journals (Sweden)

    Pinto, Ivonete

    2005-01-01

    Full Text Available O texto procura desvendar a estratégia retórica operacional do cineasta iraniano Abbas Kiarostami e, para tanto, abre a discussão sobre a fronteira existente entre ficção e realidade, trabalhando algumas nuances do gênero documental. O artigo explora a complexidade das obras do cineasta, investigando como ele manipula o artifício que emerge da organização narrativa. The text aims uncovers the operational rhetoric strategic of the cineaste Iranian Abbas Kiarostami and, for in such a way, it opens discussion about the frontier between the fiction and reality, working some shades of the documentary gender. The paper explores the complexity of the work of the cineaste, inquiring into how he manipulates the artifice that emerges out of the narrative organization.

  17. Analysis of the FIC detector data at the n_TOF facility

    CERN Document Server

    Karadimos, D; Papachristodoulou, C; Vlachoudis, V; Assimakopoulos, P; Ioannides, K; Vlastou, R; Karamanis, D; Tsagas, N; Cennini, P; Konovalov, V; Ketlerov, V

    2010-01-01

    Fission cross-section measurements with the Fast Ionization Chamber (FIC) at the CERN n\\_TOF facility were challenged by intense signals due to gamma-rays and ultra-relativistic particles from the impact of the 20 GeV proton pulses on the neutron spallation target. A method for analyzing the data taken with Flash Analog to Digital Converters (FADC) was developed to treat these problems in an automated way to provide a reliable background subtraction and a fit routine for identifying fission events even at high energies. The analysis is illustrated at the example of the fission cross-section of U-238 relative to that of U-235 in the energy range from 40 key to 300 MeV. (C) 2010 Elsevier B.V. All rights reserved.

  18. Dels jeroglífics egipcis a la compartició de secrets

    OpenAIRE

    2009-01-01

    A la secció 1 parlarem d'un jeroglífic inscrit als laterals de la llinda de Sant Andreu de la Barroca, una petita església perduda en un indret recòndit de la Vall del Llémena, a la Garrotxa. A propòsit d'aquest petit enigma ludolingüístic, plantejarem (i finalment resoldrem) un problema de naturalesa combinatòria que el lector interessat pot provar de resoldre com a exercici. A la secció 2 farem un breu repàs de la història del desxiframent d'escriptures de civilitzacions antigues. Aprofitar...

  19. Semiflexible filamentous composites

    NARCIS (Netherlands)

    Huisman, E.M.; Heussinger, C.; Storm, C.; Barkema, G.T.

    2010-01-01

    Inspired by the ubiquity of composite filamentous networks in nature, we investigate models of biopolymer networks that consist of interconnected floppy and stiff filaments. Numerical simulations carried out in three dimensions allow us to explore the microscopic partitioning of stresses and strains

  20. Proteomics of Filamentous Fungi

    NARCIS (Netherlands)

    Passel, van M.W.J.; Schaap, P.J.; Graaff, de L.H.

    2013-01-01

    Filamentous fungi, such as Aspergillus niger and Aspergillus oryzae traditionally have had an important role in providing enzymes and enzyme cocktails that are used in food industry. In recent years the genome sequences of many filamentous fungi have become available. This combined with

  1. Proteomics of Filamentous Fungi

    NARCIS (Netherlands)

    Passel, van M.W.J.; Schaap, P.J.; Graaff, de L.H.

    2013-01-01

    Filamentous fungi, such as Aspergillus niger and Aspergillus oryzae traditionally have had an important role in providing enzymes and enzyme cocktails that are used in food industry. In recent years the genome sequences of many filamentous fungi have become available. This combined with technologica

  2. Tungsten Filament Fire

    Science.gov (United States)

    Ruiz, Michael J.; Perkins, James

    2016-01-01

    We safely remove the outer glass bulb from an incandescent lamp and burn up the tungsten filament after the glass is removed. This demonstration dramatically illustrates the necessity of a vacuum or inert gas for the environment surrounding the tungsten filament inside the bulb. Our approach has added historical importance since the incandescent…

  3. Optical control of filamentation-induced damage to DNA by intense, ultrashort, near-infrared laser pulses

    Science.gov (United States)

    Dharmadhikari, J. A.; Dharmadhikari, A. K.; Kasuba, K. C.; Bharambe, H.; D’Souza, J. S.; Rathod, K. D.; Mathur, D.

    2016-06-01

    We report on damage to DNA in an aqueous medium induced by ultrashort pulses of intense laser light of 800 nm wavelength. Focusing of such pulses, using lenses of various focal lengths, induces plasma formation within the aqueous medium. Such plasma can have a spatial extent that is far in excess of the Rayleigh range. In the case of water, the resulting ionization and dissociation gives rise to in situ generation of low-energy electrons and OH-radicals. Interactions of these with plasmid DNA produce nicks in the DNA backbone: single strand breaks (SSBs) are induced as are, at higher laser intensities, double strand breaks (DSBs). Under physiological conditions, the latter are not readily amenable to repair. Systematic quantification of SSBs and DSBs at different values of incident laser energy and under different external focusing conditions reveals that damage occurs in two distinct regimes. Numerical aperture is the experimental handle that delineates the two regimes, permitting simple optical control over the extent of DNA damage.

  4. Heterogeneous filament network formation by myosin light chain isoforms effects on contractile energy output of single cardiomyocytes derived from human induced pluripotent stem cells

    Directory of Open Access Journals (Sweden)

    Takeomi Mizutani

    2016-03-01

    Full Text Available Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs are expected to play an important role in heart therapies, in which hiPSC-CMs should generate sufficient contractile force to pump blood. However, recent studies have shown that the contractility of myocardial mimics composed of hiPSC-CMs is lower than that of adult human myocardium. To examine the mechanism by which contractile force output of hiPSC-CMs is weakened, we measured the contractile force of single hiPSC-CMs and observed the fibrous distribution of myosin II regulatory light chain (MRLC of cardiac (contributes to beating and non-cardiac (does not contribute to beating isoforms. Single hiPSC-CMs were cultured on an extracellular matrix gel, and the contractile force and strain energy exerted on the gel were measured. Strain energy was not uniform between cells and ranged from 0.2 to 5.8 pJ. The combination of contractile force measurement and immunofluorescent microscopy for MRLC isoforms showed that cells with higher strain energy expressed the weakened non-cardiac myosin II fibers compared to those of cells with lower strain energy. Observation of cardiac and non-cardiac MRLC showed that the MRLC isoforms formed heterogeneous filament networks. These results suggest that strain energy output from single hiPSC-CMs depends both cardiac and non-cardiac myosin fibers, which prevent deformation of the cell body.

  5. Human enhancer of filamentation 1-induced colorectal cancer cell migration: Role of serine phosphorylation and interaction with the breast cancer anti-estrogen resistance 3 protein.

    Science.gov (United States)

    Ibrahim, Rama; Lemoine, Antoinette; Bertoglio, Jacques; Raingeaud, Joël

    2015-07-01

    Human enhancer of filamentation 1 (HEF1) is a member of the p130Cas family of docking proteins involved in integrin-mediated cytoskeleton reorganization associated with cell migration. Elevated expression of HEF1 promotes invasion and metastasis in multiple cancer cell types. To date, little is known on its role in CRC tumor progression. HEF1 is phosphorylated on several Ser/Thr residues but the effects of these post-translational modifications on the functions of HEF1 are poorly understood. In this manuscript, we investigated the role of HEF1 in migration of colorectal adeno-carcinoma cells. First, we showed that overexpression of HEF1 in colo-carcinoma cell line HCT116 increases cell migration. Moreover, in these cells, HEF1 increases Src-mediated phosphorylation of FAK on Tyr-861 and 925. We then showed that HEF1 mutation on Ser-369 enhances HEF1-induced migration and FAK phosphorylation as a result of protein stabilization. We also, for the first time characterized a functional mutation of HEF1 on Arg-367 which mimics the effect of Ser-369 to Ala mutation. Finally through mass spectrometry experiments, we identified BCAR3 as an essential interactor and mediator of HEF1-induced migration. We demonstrated that single amino acid mutations that prevent formation of the HEF1-BCAR3 complex impair HEF1-mediated migration. Therefore, amino-acid substitutions that impede Ser-369 phosphorylation stabilize HEF1 which increases the migration of CRC cells and this latter effect requires the interaction of HEF1 with the NSP family adaptor protein BCAR3. Collectively, these data reveal the importance of HEF1 expression level in cancer cell motility and then support the utilization of HEF1 as a biomarker of tumor progression.

  6. Bovine Insulin Filaments Induced by Reducing Disulfide Bonds Show a Different Morphology, Secondary Structure, and Cell Toxicity from Intact Insulin Amyloid Fibrils

    OpenAIRE

    Zako, Tamotsu; Sakono, Masafumi; Hashimoto, Naomi; Ihara, Masaki; Maeda, Mizuo

    2009-01-01

    Amyloid fibrils are associated with more than 20 diseases, including Alzheimer's disease and type II diabetes. Insulin is a 51-residue polypeptide hormone, with its two polypeptide chains linked by one intrachain and two interchain disulfide bonds, and has long been known to self-assemble in vitro into amyloid fibrils. We demonstrate here that bovine insulin forms flexible filaments in the presence of a reducing agent, Tris (2-carboxyethyl) phosphine. The insulin filaments, possibly formed du...

  7. Effect of paraquat-induced oxidative stress on gene expression and aging of the filamentous ascomycete Podospora anserina

    Directory of Open Access Journals (Sweden)

    Matthias Wiemer

    2014-06-01

    Full Text Available Aging of biological systems is influenced by various factors, conditions and processes. Among others, processes allowing organisms to deal with various types of stress are of key importance. In particular, oxidative stress as the result of the generation of reactive oxygen species (ROS at the mitochondrial respiratory chain and the accumulation of ROS-induced molecular damage has been strongly linked to aging. Here we view the impact of ROS from a different angle: their role in the control of gene expression. We report a genome-wide transcriptome analysis of the fungal aging model Podospora anserina grown on medium containing paraquat (PQ. This treatment leads to an increased cellular generation and release of H2O2, a reduced growth rate, and a decrease in lifespan. The combined challenge by PQ and copper has a synergistic negative effect on growth and lifespan. The data from the transcriptome analysis of the wild type cultivated under PQ-stress and their comparison to those of a longitudinal aging study as well as of a copper-uptake longevity mutant of P. anserina revealed that PQ-stress leads to the up-regulation of transcripts coding for components involved in mitochondrial remodeling. PQ also affects the expression of copper-regulated genes suggesting an increase of cytoplasmic copper levels as it has been demonstrated earlier to occur during aging of P. anserina and during senescence of human fibroblasts. This effect may result from the induction of the mitochondrial permeability transition pore via PQ-induced ROS, leading to programmed cell death as part of an evolutionary conserved mechanism involved in biological aging and lifespan control.

  8. Isotropic-Cholesteric Co-Existence and Magnetic Field-Induced Isotropic-Nematic Transition of Filamentous Bacteriophage FD in Aqueous Suspension.

    Science.gov (United States)

    Tang, Jianxin

    1995-01-01

    Isotropic to liquid crystalline phase transition for a lyotropic suspension of geometrically asymmetric macromolecules occurs to a wild class of synthetic polymers and biopolymers. Although in decades statistical mechanical theories have been developed to predict the thermodynamic conditions and the properties of such transition, quantitative comparison with theory has been compounded with complications such as charge, shape, polydispersity in size, and additional interactions with the solvent and among the macromolecules themselves. We chose the aqueous suspension of the filamentous bacteriophage fd as a model system to study the isotropic to liquid crystalline transition. The co-existence concentrations, as a function of ionic strength, were measured directly by spectrophotometry. Our data confirm quantitatively the predictions of a statistical mechanic treatment first described by Onsager, modified to include the effects of charge and flexibility of rodlike particles. We have also extended a previous study of the pretransitional angular correlations in the isotropic solutions of fd through the measurement of the magnetic-field-induced birefringence, i.e. the measurement of the Cotton-Mouton constant. At several ionic strengths the magnetic-field-induced birefringence, which is proportional to the number of particles in a correlation volume N_{rm corr}, was measured for fd concentrations spanning the entire isotropic region. From this data the limiting concentration of stability (spinodal) of the isotropic phase is obtained. A theoretical expression for the magnetic birefringence of persistent polymers was derived and agreed well with the data with the exception that N_{rm corr} at the isotropic to liquid crystal transition was smaller than predicted. In the proximity of the highest possible isotropic concentration, that is the isotropic in co-existence with anisotropic, we studied the effect of a high magnetic field. A first order field-induced isotropic

  9. Induced alignment and measurement of dipolar couplings of an SH2 domain through direct binding with filamentous phage

    Energy Technology Data Exchange (ETDEWEB)

    Dahlke Ojennus, Deanna; Mitton-Fry, Rachel M.; Wuttke, Deborah S. [University of Colorado, Department of Chemistry and Biochemistry (United States)

    1999-06-15

    Large residual {sup 15}N-{sup 1}H dipolar couplings have been measured in a Src homology II domain aligned at Pf1 bacteriophage concentrations an order of magnitude lower than used for induction of a similar degree of alignment of nucleic acids and highly acidic proteins. An increase in {sup 1} H and {sup 15}N protein linewidths and a decrease in T{sub 2} and T{sub 1}{rho} relaxation time constants implicates a binding interaction between the protein and phage as the mechanism of alignment. However, the associated increased linewidth does not preclude the accurate measurement of large dipolar couplings in the aligned protein. A good correlation is observed between measured dipolar couplings and predicted values based on the high resolution NMR structure of the SH2 domain. The observation of binding-induced protein alignment promises to broaden the scope of alignment techniques by extending their applicability to proteins that are able to interact weakly with the alignment medium.

  10. New opportunities for secure communication networks using shaped femtosecond laser pulses inducing filamentation processes in the atmosphere

    Science.gov (United States)

    Alyami, H. M.; Becerra, V. M.; Hadjiloucas, S.

    2013-11-01

    The current study discusses new opportunities for secure ground to satellite communications using shaped femtosecond pulses that induce spatial hole burning in the atmosphere for efficient communications with data encoded within super-continua generated by femtosecond pulses. Refractive index variation across the different layers in the atmosphere may be modelled using assumptions that the upper strata of the atmosphere and troposphere behaving as layered composite amorphous dielectric networks composed of resistors and capacitors with different time constants across each layer. Input-output expressions of the dynamics of the networks in the frequency domain provide the transmission characteristics of the propagation medium. Femtosecond pulse shaping may be used to optimize the pulse phase-front and spectral composition across the different layers in the atmosphere. A generic procedure based on evolutionary algorithms to perform the pulse shaping is proposed. In contrast to alternative procedures that would require ab initio modelling and calculations of the propagation constant for the pulse through the atmosphere, the proposed approach is adaptive, compensating for refractive index variations along the column of air between the transmitter and receiver.

  11. Analytical Core Mass Function (CMF) from Filaments: Under Which Circumstances Can Filament Fragmentation Reproduce the CMF?

    Science.gov (United States)

    Lee, Yueh-Ning; Hennebelle, Patrick; Chabrier, Gilles

    2017-10-01

    Observations suggest that star formation in filamentary molecular clouds occurs in a two-step process, with the formation of filaments preceding that of prestellar cores and stars. Here, we apply the gravoturbulent fragmentation theory of Hennebelle & Chabrier to a filamentary environment, taking into account magnetic support. We discuss the induced geometrical effect on the cores, with a transition from 3D geometry at small scales to 1D at large ones. The model predicts the fragmentation behavior of a filament for a given mass per unit length (MpL) and level of magnetization. This core mass function (CMF) for individual filaments is then convolved with the distribution of filaments to obtain the final system CMF. The model yields two major results. (i) The filamentary geometry naturally induces a hierarchical fragmentation process, first into groups of cores, separated by a length equal to a few filament Jeans lengths, i.e., a few times the filament width. These groups then fragment into individual cores. (ii) Non-magnetized filaments with high MpL are found to fragment excessively, at odds with observations. This is resolved by taking into account the magnetic field (treated simply as additional pressure support). The present theory suggests two complementary modes of star formation: although small (spherical or filamentary) structures will collapse directly into prestellar cores, according to the standard Hennebelle–Chabrier theory, the large (filamentary) ones, the dominant population according to observations, will follow the aforedescribed two-step process.

  12. Bacterial intermediate filaments

    DEFF Research Database (Denmark)

    Charbon, Godefroid; Cabeen, M.; Jacobs-Wagner, C.

    2009-01-01

    Crescentin, which is the founding member of a rapidly growing family of bacterial cytoskeletal proteins, was previously proposed to resemble eukaryotic intermediate filament (IF) proteins based on structural prediction and in vitro polymerization properties. Here, we demonstrate that crescentin...

  13. Blistering of viscoelastic filaments

    CERN Document Server

    Sattler, R; Wagner, C

    2007-01-01

    When a dilute polymer solution experiences capillary thinning, it forms an almost uniformly cylindrical thread, which we study experimentally. In the last stages of thinning, when polymers have become fully stretched, the filament becomes prone to instabilities, of which we describe two: A novel "breathing" instability, originating from the edge of the filament, and a sinusoidal instability in the interior, which ultimately gives rise to a "blistering" pattern of beads on the filament. We describe the linear instability with a spatial resolution of 80 nm in the disturbance amplitude. For sufficiently high polymer concentrations, the filament eventually separates out into a "solid" phase of entangled polymers, connected by fluid beads. A solid polymer fiber of about 100 nanometer thickness remains, which is essentially permanent.

  14. Changes in the number and size of nucleoli of Chara vulgaris L. antheridial filament cells during the period preceding light-induced re-initiation of cell divisions following a mitodepressive effect of darkness

    Directory of Open Access Journals (Sweden)

    Maria Kwiatkowska

    2014-02-01

    Full Text Available The changes in number and size of nucleoli of Chara vulgaris antheridial filament cells were monitored with the use of Howell and Black's silver staining method. After a 3-day mitodepressive treatment with darkness the cells were exposed to light which reactivated mitotic activity after 18-20 hours. Eight-celled antheridial filaments were observed. In the period preceding light-induced re-initiation of mitoses a gradual reconstruction of the number and size of nucleoli characteristic of control, as well as their total area per nucleus appeared. The obtained results indicate that one of the important conditions for a cell to be able to divide is accumulation of nucleolus components characteristic of a given developmental stage and this controls nucleologenesis of the subsequent cell cycle.

  15. Os mortos de línguas cortadas – ficção e realidade em Nove noites, de Bernardo Carvalho

    Directory of Open Access Journals (Sweden)

    Cid Ottoni Bylaardt

    2008-12-01

    Full Text Available O romance Nove noites, de Bernardo Carvalho, entrelaça morte e escrita numa narrativa intrigante, evidenciando os tênues limites entre realidade e ficção. A realidade dos fatos é buscada tenazmente pelo narrador jornalista, que a partir de certo momento, paradoxalmente, revela a preocupação de que o real arruine a ficção, por mais que esta pareça estar entre as expectativas do leitor. A escritura, entretanto, avança sem se deixar determinar, conduzida por locutores não-confiáveis, indecisos entre a verdade e a mentira, o real e a ficção, desembocando na questão da morte como impossibilidade de dizer e também de calar.Palavras-chave: Ficção e Realidade; Escrita e Morte; Impossibilidade de dizer e de calar.

  16. A política na TV de ficção

    Directory of Open Access Journals (Sweden)

    Juremir Machado

    2008-09-01

    Full Text Available A escola de Frankfurt, durante décadas, pautou o paradigma para o estudo dos meios de comunicação. Superefeitos sociais. Receptores alienados. Vítimas. Numa perspectiva crítica a esta, o texto que segue aponta, em tempos de pós-modernidade, para uma negocia ção complexa de sentido entre emissores e receptores. Telejornalismo e telenovela, mensagens emitidas e recebidas enquanto realidades nada estanques, ensejam matrizes de atribuição de sentido e valor com numerosos e sutis vasos comunicantes. Palavras-chave: Pós-modernidade; ficção; telejornal; eleição. ABSTRACT During decades, the school of Frankfurt set the paradigm for the mass media study. Social super-effects. Alienated receptors. Victims. In a perspective critical to this one, the following text points to, in post-modern times, a complex negotiation of meaning between those who emit and those who receive the information. TV newscast and soap opera, messages emitted and received as realities not in the least unconnected, generate matrixes of attribution of meaning and value with numerous and subtle communicating vases. Keywords: Post-modernity; fiction; TV newscast; election.

  17. Kinetic and Structural Insights into the Mechanism of AMPylation by VopS Fic Domain

    Energy Technology Data Exchange (ETDEWEB)

    Luong, Phi; Kinch, Lisa N.; Brautigam, Chad A.; Grishin, Nick V.; Tomchick, Diana R.; Orth, Kim (UTSMC)

    2010-07-19

    The bacterial pathogen Vibrio parahemeolyticus manipulates host signaling pathways during infections by injecting type III effectors into the cytoplasm of the target cell. One of these effectors, VopS, blocks actin assembly by AMPylation of a conserved threonine residue in the switch 1 region of Rho GTPases. The modified GTPases are no longer able to interact with downstream effectors due to steric hindrance by the covalently linked AMP moiety. Herein we analyze the structure of VopS and its evolutionarily conserved catalytic residues. Steady-state analysis of VopS mutants provides kinetic understanding on the functional role of each residue for AMPylation activity by the Fic domain. Further mechanistic analysis of VopS with its two substrates, ATP and Cdc42, demonstrates that VopS utilizes a sequential mechanism to AMPylate Rho GTPases. Discovery of a ternary reaction mechanism along with structural insight provides critical groundwork for future studies for the family of AMPylators that modify hydroxyl-containing residues with AMP.

  18. Characterization of HI Filaments

    Science.gov (United States)

    Lubar, Emily; Verschuur, Gerrit L.

    2017-01-01

    We characterized the properties of dramatic interstellar HI filaments to learn more about the dynamics and structure of such features. Using Gauss fitting software, we searched the Effelsburg-Bonn HI Survey data for indications of a simple twisting (toroidal) motion across these filaments. Instead, we found that the structure was more complicated than expected. Apparent angular widths of several filaments were measured using the Galactic Arecibo L-band Feed Array HI (GALFA-HI), Bonn, and Leident/Argentine/Bonn (LAB) surveys. Based on filament widths and other parameters, we conclude that magnetism is the dominant force opposing internal motion and maintaining the structure of these filaments. The apparent width as a function of beam width closely follows a relationship reported in 1993 for HI features in general. They tend to subtend an angle two times the beam width, suggesting that the features remain unresolved.The Arecibo Observatory is operated by SRI International under a cooperative agreement with the National Science Foundation (AST-1100968), and in alliance with Ana G. Méndez-Universidad Metropolitana, and the Universities Space Research Association. The Arecibo Observatory REU is funded under grant AST-1559849 to Universidad Metropolitana.

  19. Filaments in Lupus I

    Science.gov (United States)

    Takahashi, Satoko; Rodon, J.; De Gregorio-Monsalvo, I.; Plunkett, A.

    2017-06-01

    The mechanisms behind the formation of sub-stellar mass sources are key to determine the populations at the low-mass end of the stellar distribution. Here, we present mapping observations toward the Lupus I cloud in C18O(2-1) and 13CO(2-1) obtained with APEX. We have identified a few velocity-coherent filaments. Each contains several substellar mass sources that are also identified in the 1.1mm continuum data (see also SOLA catalogue presentation). We will discuss the velocity structure, fragmentation properties of the identified filaments, and the nature of the detected sources.

  20. Aerogel-supported filament

    Science.gov (United States)

    Wuest, Craig R.; Tillotson, Thomas M.; Johnson, III, Coleman V.

    1995-01-01

    The present invention is a thin filament embedded in a low density aerogel for use in radiation detection instruments and incandescent lamps. The aerogel provides a supportive matrix that is thermally and electrically nonconductive, mechanically strong, highly porous, gas-permeable, and transparent to ionizing radiation over short distances. A low density, open-cell aerogel is cast around a fine filament or wire, which allows the wire to be positioned with little or no tension and keeps the wire in place in the event of breakage. The aerogel support reduces the stresses on the wire caused by vibrational, gravitational, electrical, and mechanical forces.

  1. Branching of keratin intermediate filaments.

    Science.gov (United States)

    Nafeey, Soufi; Martin, Ines; Felder, Tatiana; Walther, Paul; Felder, Edward

    2016-06-01

    Keratin intermediate filaments (IFs) are crucial to maintain mechanical stability in epithelial cells. Since little is known about the network architecture that provides this stiffness and especially about branching properties of filaments, we addressed this question with different electron microscopic (EM) methods. Using EM tomography of high pressure frozen keratinocytes, we investigated the course of several filaments in a branching of a filament bundle. Moreover we found several putative bifurcations in individual filaments. To verify our observation we also visualized the keratin network in detergent extracted keratinocytes with scanning EM. Here bifurcations of individual filaments could unambiguously be identified additionally to bundle branchings. Interestingly, identical filament bifurcations were also found in purified keratin 8/18 filaments expressed in Escherichia coli which were reassembled in vitro. This excludes that an accessory protein contributes to the branch formation. Measurements of the filament cross sectional areas showed various ratios between the three bifurcation arms. This demonstrates that intermediate filament furcation is very different from actin furcation where an entire new filament is attached to an existing filament. Instead, the architecture of intermediate filament bifurcations is less predetermined and hence consistent with the general concept of IF formation.

  2. Un vocabulari pornogràfic francès-català inèdit

    Directory of Open Access Journals (Sweden)

    Joan Puigmalet

    2014-06-01

    Full Text Available Antoni Bulbena Tosell és autor d’un manuscrit, i inèdit, vocabulari pornogràfic francèscatalà català-francès, la Flora pornogràfica francesa: suplement al argot francès / Flore pornographique catalane: supplément à l’argot catalan. És una obra d’aproximadament l’any 1921 que, per la seva temàtica, ell mateix reservava per a no publicar-se. Bulbena és autor d’una discutida obra lingüística, entre la qual trobem diferents diccionaris, alguns d’ells entre el català i el francès. El darrer que publicà és el Diccionari de les lléngues francesa & catalana / Dictionnaire catalan-français (1921 que inclou dos apèndixs, un «Vocabulari d’argot francès» i un «Vocabulari d’argot catalan». La Flora és, així, un suplement al lèxic pornogràfic d’aquest diccionari. Per altra banda, el títol de Flora pornogràfica sembla fer referència a una obra de la lexicografia francesa que recull mots obscens presents a obres d’Emile Zola i altres escriptors naturalistes, La flore pornographique (1883, d’Ambroise Macrobe. Els mots d’argot sexual de la Flora, amb un especial focus temàtic en la prostitució, tenen interès lingüístic i cultural tant per a la llengua catalana com per a la llengua francesa. Antoni Bulbena Tosell is the author of an unpublished, pornographic vocabulary FrenchCatalan Catalan-French, a manuscript called the Flora pornogràfica francesa: suplement al argot francès / Flore pornographique catalane: supplément à l’argot catalan. It was written around 1921 and reserved for not being published. Bulbena is the author of a controversial linguistic work, among which are various dictionaries, some of them between Catalan and French. The latest is the Diccionari de les lléngues francesa & catalana / Dictionnaire catalan-français (1921, that includes two appendixes, a «Vocabulari d’argot francès» and a «Vocabulari d’argot catalan». The Flora is thus a pornographic supplement to the

  3. Kilometer range filamentation

    OpenAIRE

    Durand, Magali; Houard, Aurélien; Prade, Bernard; Mysyrowicz, André; Durécu, Anne; Moreau, Bernard; Fleury, Didier; Vasseur, Olivier; Borchert, Hartmut; Diener, Karsten; Schmitt, Rudiger; Théberge, Francis; Chateauneuf, Marc; Daigle, Jean-François; Dubois, Jacques

    2013-01-01

    International audience; We demonstrate for the first time the possibility to generate long plasma channels up to a distance of 1 km, using the terawatt femtosecond T&T laser facility. The plasma density was optimized by adjusting the chirp, the focusing and beam diameter. The interaction of filaments with transparent and opaque targets was studied.

  4. Solar Features - Prominences and Filaments

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Prominences and filaments are two manifestations of the same phenomenon. Both prominences and filaments are features formed above the chromosphere by cool dense...

  5. Positrusion Filament Recycling System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TUI proposes a novel process to produce 3d printer feedstock filament out of scrap ABS on the ISS. Currently the plastic filament materials that most 3d printers use...

  6. Filamentation of femtosecond laser pulse influenced by the air turbulence at various propagation distances

    Science.gov (United States)

    Hu, Yuze; Nie, Jinsong; Sun, Ke; Wang, Lei

    2017-01-01

    The spatial and temporal features of femtosecond laser filamentation, which are induced by a laser with power several times higher than the critical power, influenced by strong air turbulence at various propagation distances have been studied numerically. First, a strong turbulence occurring right before focal lens induces a few counter-balanced energy spikes which prevent the filament generation. Second, with the turbulence right before the filamentation, side filaments formed in the periphery towards the outside area leads the filament to be slightly short. Third, with the turbulence right after the lens, numerous energy spikes of the wave profile arise, but they will merge into one filament gradually, leading to a delayed filamentation onset and a shorter filamentation length. The deformation of temporal pulse shape become more sensitive and the supercontinuum (SC) can be weakened more significantly when strong turbulence takes place in air more previously.

  7. Properties of twisted ferromagnetic filaments

    Energy Technology Data Exchange (ETDEWEB)

    Belovs, Mihails; Cebers, Andrejs [University of Latvia, Zellu 8, LV-1002 (Latvia)], E-mail: aceb@tesla.sal.lv

    2009-02-01

    The full set of equations for twisted ferromagnetic filaments is derived. The linear stability analysis of twisted ferromagnetic filament is carried out. Two different types of the buckling instability are found - monotonous and oscillatory. The first in the limit of large twist leads to the shape of filament reminding pearls on the string, the second to spontaneous rotation of the filament, which may constitute the working of chiral microengine.

  8. Interferon Status and Choice of Interferons Inducers in Frequently Ill Children

    Directory of Open Access Journals (Sweden)

    M. S. Savenkovа

    2016-01-01

    Full Text Available Literature data on the study of interferon status in children. Own results of the survey group of frequently ill children (FIC have shown insufficient production of IFN alpha and gamma-IFN, humoral immunity. It was revealed that 66% of the group FIC has only failure of interferon system, and 34% of FIC has violations of humoral immunity in combination with interferon system failure. At the same time, all children suffering occasionally was detected only insufficiency of interferon system and humoral immunity was within normal limits. Based on the study of individual sensitivity of white blood cells justifies the choice of interferons inducers.

  9. Filamentous Fungi Fermentation

    DEFF Research Database (Denmark)

    Nørregaard, Anders; Stocks, Stuart; Woodley, John

    2014-01-01

    Filamentous fungi (including microorganisms such as Aspergillus niger and Rhizopus oryzae) represent an enormously important platform for industrial fermentation. Two particularly valuable features are the high yield coefficients and the ability to secrete products. However, the filamentous...... morphology, together with non-Newtonian rheological properties (shear thinning), result in poor oxygen transfer unless sufficient energy is provided to the fermentation. While genomic research may improve the organisms, there is no doubt that to enable further application in future it will be necessary...... to match such research with studies of oxygen transfer and energy supply to high viscosity fluids. Hence, the implementation of innovative solutions (some of which in principle are already possible) will be essential to ensure the further development of such fermentations....

  10. Fundamentals of Filament Interaction

    Science.gov (United States)

    2017-05-19

    provide a 1:1 image of the filament profile onto a CCD camera (The Imaging Source DMK72BUC02). Neutral density filters were used to prevent the...thermal velocity, until their momentum was arrested by collisions with neutral air molecules. This results in a short distance, transient current which...Martin Richardson, 3rd ELI-ALPS User Workshop, Szeged, Hungary November 2015 126 “Photonics and the Changing Energy Scene ”, Martin Richardson

  11. Heterologous gene expression in filamentous fungi.

    Science.gov (United States)

    Su, Xiaoyun; Schmitz, George; Zhang, Meiling; Mackie, Roderick I; Cann, Isaac K O

    2012-01-01

    Filamentous fungi are critical to production of many commercial enzymes and organic compounds. Fungal-based systems have several advantages over bacterial-based systems for protein production because high-level secretion of enzymes is a common trait of their decomposer lifestyle. Furthermore, in the large-scale production of recombinant proteins of eukaryotic origin, the filamentous fungi become the vehicle of choice due to critical processes shared in gene expression with other eukaryotic organisms. The complexity and relative dearth of understanding of the physiology of filamentous fungi, compared to bacteria, have hindered rapid development of these organisms as highly efficient factories for the production of heterologous proteins. In this review, we highlight several of the known benefits and challenges in using filamentous fungi (particularly Aspergillus spp., Trichoderma reesei, and Neurospora crassa) for the production of proteins, especially heterologous, nonfungal enzymes. We review various techniques commonly employed in recombinant protein production in the filamentous fungi, including transformation methods, selection of gene regulatory elements such as promoters, protein secretion factors such as the signal peptide, and optimization of coding sequence. We provide insights into current models of host genomic defenses such as repeat-induced point mutation and quelling. Furthermore, we examine the regulatory effects of transcript sequences, including introns and untranslated regions, pre-mRNA (messenger RNA) processing, transcript transport, and mRNA stability. We anticipate that this review will become a resource for researchers who aim at advancing the use of these fascinating organisms as protein production factories, for both academic and industrial purposes, and also for scientists with general interest in the biology of the filamentous fungi. Copyright © 2012 Elsevier Inc. All rights reserved.

  12. Oral Immunization of Rabbits with S. enterica Typhimurium Expressing Neisseria gonorrhoeae Filamentous Phage Φ6 Induces Bactericidal Antibodies Against N. gonorrhoeae

    OpenAIRE

    Andrzej Piekarowicz; Aneta Kłyż; Michał Majchrzak; Stein, Daniel C.

    2016-01-01

    All Neisseria gonorrhoeae strains whose DNA sequences have been determined possess filamentous phage DNA sequences. To ascertain if phage encoded proteins could form the basis of a gonococcal vaccine, rabbits were orally infected with S. enterica Typhimurium strain χ3987 harboring phagemid NgoΦ6 fm. The elicited sera contained large quantities of anti-phage IgG and IgA antibodies that bound to the surface of N. gonorrhoeae cells, as shown by indirect fluorescent analysis and flow cytometry. T...

  13. Increase of calcium levels in epithelial cells induces translocation of calcium-binding proteins migration inhibitory factor-related protein 8 (MRP8) and MRP14 to keratin intermediate filaments.

    Science.gov (United States)

    Goebeler, M; Roth, J; van den Bos, C; Ader, G; Sorg, C

    1995-07-15

    Migration inhibitory factor-related protein 8 (MRP8) and MRP14, two S-100-like Ca(2+)-binding proteins, have been described in cells of the epithelial lineage where they are either expressed constitutively (e.g. by mucosal squamous epithelium) or induced during disease (e.g. in keratinocytes during the course of psoriasis). Their biological function, however, is not yet clear. Recent studies have provided evidence that S-100-like proteins may interact with cytoskeletal components; we have therefore studied the biochemical properties and subcellular distribution of MRP8 and MRP14 in epithelial cells. TR146 human squamous carcinoma cells, which were found to express MRP8 and MRP14 in Northern and Western blot studies, were chosen for analysis. Cross-linking experiments using bis(sulphosuccinimidyl)suberate followed by SDS/PAGE and Western blot analysis revealed formation of heteromeric MRP8-MRP14 complexes. On subjecting TR146 cell lysates to two-dimensional gel electrophoresis and Western blotting, four distinct MRP14 isoforms could be identified resembling those described earlier in macrophages. A differential centrifugation technique revealed a Ca(2+)-dependent translocation of MRP8-MRP14 from the cytoplasm to the membrane and the Nonidet P40-insoluble cytoskeletal fraction. Double-label immunofluorescence microscopy of Ca2+ ionophore A23187-stimulated TR146 cells and cytochalasin B and demecolcine cytoskeleton disruption studies identified these structures as keratin intermediate filaments. Ca(2+)-dependent binding of MRP8-MRP14 to keratin filaments was additionally confirmed by an in vitro binding assay. In conclusion, our data suggest that MRP8 and MRP14 may be involved in Ca(2+)-dependent reorganization of cytoskeletal filaments in epithelial cells, which could be of importance for events associated with differentiation and inflammatory activation.

  14. El dibuix analític com a mètode d'interpretació del disseny gràfic.

    Directory of Open Access Journals (Sweden)

    Anna Pujadas Matarín

    2014-07-01

    Full Text Available Un mètode clàssic per a l'anàlisi dels elements gràfics d'una imatge és el Dibuix Analític de Kandinsky. En aquest treball es desenvolupa una teoria d'aquest mètode basada en els resultats personals d'ensenyament amb classes de grup. La declaració teòrica principal és que aquest mètode clàssic hauria d'ampliar amb vista a intentar la prospecció del significat dels elements gràfics. El treball acaba descrivint el nou mètode i la forma en què és capaç de proporcionar una interpretació crítica d'un producte gràfic.

  15. Flow-induced crystallization in isotactic polypropylene

    Science.gov (United States)

    Hamad, Fawzi Ghassan

    Brief intervals of strong flow stretch chains in a semicrystalline polymer melt, which results in an increase in the nuclei number density and a transformation of the crystal structure. This flow-induced crystallization (FIC) phenomenon is explored in this study using highly isotactic polypropylene (iPP) samples. Using one synthesized and five commercial linear isotactic polypropylene samples, we investigate the FIC behavior by imposing shear onto these samples in a rotational rheometer. Equipped with a good temperature control and flexible shear protocol, we apply different temperature and flow conditions. The magnitude of the FIC effect varies with basic processing parameters (shear rate, specific work, crystallization temperature, and shearing temperature) and material properties (totalistic, molecular weight distribution, and particle concentration in the polymer). The scope of this study is to systematically investigate the influences of these parameters on FIC. The FIC effects that are investigated in this dissertation are: crystallization kinetics, persistence time of flow-induced nuclei, and crystal morphology. The crystallization time was measured in the rheometer by monitoring the onset of crystallization after quenching samples sheared above Tm. These samples were subsequently used to study their flow-induced nuclei persistence time and crystal morphology. The lifetime of flow-induced nuclei was determined by measuring the time required to return from FIC back to quiescent crystallization using a differential scanning calorimeter. The crystal morphology was imaged using polarized optical microscopy and atomic force microscopy. We investigated the influence of specific work on the three FIC characteristics, and found three regimes that are separated by the critical work ( Wc) and the saturation work (Wsat) thresholds. Below the critical work threshold, the morphology is composed of mostly spherulite crystals, which keep a constant volume, and a small

  16. A perspectiva sociocultural da física nos romances de ficção científica de Arthur Clarke

    OpenAIRE

    Piassi,Luís Paulo

    2012-01-01

    Arthur C. Clarke é considerado um dos maiores escritores de ficção científica. Falecido em 2008, o mesmo ano em que seu filme com Stanley Kubrick, 2001: Uma Odisseia no Espaço completou 40 anos, deixou uma série de romances e contos de ficção científica que se caracterizam pela cuidadosa precisão científica aliada à fantasia especulativa sobre os caminhos futuros da humanidade. Alguns autores têm visto nas obras de Clarke um potencial didático relevante no ensino de ciências, na medida em que...

  17. Filament Identification through Mathematical Morphology

    CERN Document Server

    Koch, Eric W

    2015-01-01

    We present a new algorithm for detecting filamentary structure FilFinder. The algorithm uses the techniques of mathematical morphology for filament identification, presenting a complementary approach to current algorithms which use matched filtering or critical manifolds. Unlike other methods, FilFinder identifies filaments over a wide dynamic range in brightness. We apply the new algorithm to far infrared imaging data of dust emission released by the Herschel Gould Belt Survey team. Our preliminary analysis characterizes both filaments and fainter striations. We find a typical filament width of 0.09 pc across the sample, but the brightness varies from cloud to cloud. Several regions show a bimodal filament brightness distribution, with the bright mode (filaments) being an order of magnitude brighter than the faint mode (striations). Using the Rolling Hough Transform, we characterize the orientations of the striations in the data, finding preferred directions that agree with magnetic field direction where dat...

  18. Chaperonin filaments: The archael cytoskeleton

    Energy Technology Data Exchange (ETDEWEB)

    Trent, J.D.; Kagawa, H.K.; Yaoi, Takuro; Olle, E.; Zaluzec, N.J.

    1997-08-01

    Chaperonins are multi-subunit double-ring complexed composed of 60-kDa proteins that are believed to mediate protein folding in vivo. The chaperonins in the hyperthermophilic archaeon Sulfolobus shibatae are composed of the organism`s two most abundant proteins, which represent 4% of its total protein and have an intracellular concentration of {ge} 3.0 mg/ml. At concentrations of 1.0 mg/ml, purified chaperonin proteins aggregate to form ordered filaments. Filament formation, which requires Mg{sup ++} and nucleotide binding (not hydrolysis), occurs at physiological temperatures under conditions suggesting filaments may exist in vivo. If the estimated 4,600 chaperonins per cell, formed filaments in vivo, they could create a matrix of filaments that would span the diameter of an average S. shibatae cell 100 times. Direct observations of unfixed, minimally treated cells by intermediate voltage electron microscopy (300 kV) revealed an intracellular network of filaments that resembles chaperonin filaments produced in vitro. The hypothesis that the intracellular network contains chaperonins is supported by immunogold analyses. The authors propose that chaperonin activity may be regulated in vivo by filament formation and that chaperonin filaments may serve a cytoskeleton-like function in archaea and perhaps in other prokaryotes.

  19. ExB flow-induced shearing-merging of filaments: a Ginzburg-Landau model of Edge-Localized Mode cycles

    CERN Document Server

    Leconte, M; Jeon, Y M

    2016-01-01

    We derive and study a simple 1D nonlinear model for Edge Localized Mode (ELM) cycles. The nonlinear dynamics of a resistive ballooning mode is modeled via a single nonlinear equation of the Ginzburg-Landau type with a radial frequency gradient due to a prescribed ExB shear layer of finite extent. The nonlinearity is due to the feedback of the mode on the profile. We identify a novel mechanism, whereby the ELM only crosses the linear stability boundary once, and subsequently stays in the nonlinear regime for the full duration of the cycles. This is made possible by the shearing and merging of filaments by the ExB flow, which forces the system to oscillate between a radially-uniform solution and a non-uniform solitary - wave like solution. The model predicts a 'phase-jump' correlated with the ELM bursts.

  20. Current filamentation model for the Weibel/Filamentation instabilities

    Science.gov (United States)

    Ryu, Chang-Mo; Huynh, Cong Tuan; Kim, Chul Min

    2016-10-01

    A current filamentaion model for a nonrelativistic plasma with e +/e- beam has been presented together with PIC simulations, which can explain the mangetic field enhancement during the Weibel/ Filamentation instabilities. This filament model assumes the Hammer-Rostoker equilibrium. In addition, this model predicts preferential acceleration/deceleration for electron-ion plasmas depending on the injected beam to be e +/e-.

  1. Narrativa sensacionalista e ficção especulativa sobre o aquecimento global: Catarse, alerta, realidade e ficção em "O Dia Depois de Amanhã"

    Directory of Open Access Journals (Sweden)

    Carolina Maria Zoccoli Carneiro

    2010-06-01

    Full Text Available

    Tomando como objeto de análise o filme O Dia Depois de Amanhã (EUA, 2004, este artigo tem como objetivo discutir como uma abordagem sensacionalista sobre questões ambientais, como o aquecimento global, pode propor uma mistura entre realidade - embasada em fatos científicos – e ficção, atraindo o espectador por meio de suas sensações. Para isto, trabalhamos sobre o conceito de sensacionalismo e suas origens, além do potencial atrativo do ficcional e da fantasia.

  2. Metabolomics protocols for filamentous fungi.

    Science.gov (United States)

    Gummer, Joel P A; Krill, Christian; Du Fall, Lauren; Waters, Ormonde D C; Trengove, Robert D; Oliver, Richard P; Solomon, Peter S

    2012-01-01

    Proteomics and transcriptomics are established functional genomics tools commonly used to study filamentous fungi. Metabolomics has recently emerged as another option to complement existing techniques and provide detailed information on metabolic regulation and secondary metabolism. Here, we describe broad generic protocols that can be used to undertake metabolomics studies in filamentous fungi.

  3. Memória e ficção : o teor testemunhal na obra de Günter Grass

    OpenAIRE

    Bruno Mendes dos Santos

    2014-01-01

    Este trabalho trata dos limites entre memória e ficção em algumas obras de Günter Grass (1927-) - a saber, O tambor (1959), Gato e rato (1961), Anos de cão (1965) e Nas peles da cebola (2006) - tendo em vista o seu teor testemunhal sobre o período entre guerras e pós-guerra, levando em conta a situação do autor como sujeito e objeto social, em um dos ambientes mais representativos da história global no século XX. Com o suporte de teorias da literatura, da cultura e da filosofia, além do apara...

  4. Um bestiário universal: ironia e pessimismo na ficção de Primo Levi

    Directory of Open Access Journals (Sweden)

    Alcebíades Diniz Miguel

    2009-03-01

    Full Text Available A experiência concentracionária marca o tom de parte da literatura de Primo Levi, dedicada à rememoração e testemunho do horror: o processo de desumanização e extermínio pelo qual os judeus passaram durante o Holocausto. Mas há outra literatura cultivada por Levi: fantástica e alegórica, com a apropriação de elementos e motivos da ficção científica. Mas estariam essas duas literaturas – diferentes em tom e temática – distantes de fato, ou haveria elementos que as aproximaria? Essa questão é o motor central de nosso ensaio.

  5. Ontem, hoje e os outros: ficção brasileira contemporânea e tempo presente

    OpenAIRE

    Motta Aguiar, Cristhiano

    2010-01-01

    Esta dissertação estuda de que maneira os romances Mãos de cavalo, de Daniel Galera, O enigma de Qaf, de Alberto Mussa e o livro de contos Rasif, de Marcelino Freire, se articulam com dois elementos chave à compreensão das sociedades contemporâneas: presentificação e memória. A partir destes dois eixos principais, temas como indústria cultural, mídia, mito, mímesis e hiperrealismo ajudarão a delinear as tendências estéticas ideologicas e os contextos de produção da ficção brasileira contempor...

  6. Breve Panorama das Tendências Contemporâneas da Ficção Científica Brasileira

    Directory of Open Access Journals (Sweden)

    Rodolfo Rorato Londero

    2016-07-01

    Full Text Available Atualmente é possível reconhecer na produção brasileira de ficção científica três grandes tendências: 1 a história alternativa, incluindo a recentíssima febre steampunk; 2 a ficção cyberpunk; e 3 a ficção borderline (obras na fronteira entre a ficção científica e a ficção mainstream. As três tendências surgiram durante a Segunda Onda da Ficção Científica Brasileira, período que abrange o início dos anos 1980, sendo cada uma representada pelos autores Gerson Lodi-Ribeiro, Fausto Fawcett e Braulio Tavares, respectivamente. Além de comentar algumas obras recém-publicadas de novos e antigos autores inseridos nas três tendências – as histórias alternativas de Gerson Lodi-Ribeiro (Xochiquetzal, 2009 e de Roberto de Sousa Causo (Selva Brasil, 2010; as ficções cyberpunks de Fábio Fernandes (Os dias da peste, 2009 e de Richard Diegues (Cyber Brasiliana, 2010; e a ficção borderline de Luiz Bras (Paraíso líquido, 2010 –, o objetivo é relacioná-las ao pós-modernismo, demonstrando que este movimento artístico-cultural é o determinante em comum da atual produção: sendo assim, a história alternativa se aproxima da poética do pós-modernismo que Linda Hutcheon denomina “metaficção historiográfica”; a ficção cyberpunk, segundo Fredric Jameson, é a expressão literária máxima não apenas do pós-modernismo, mas também do capitalismo tardio; e a ficção borderline representa o enfraquecimento da distinção entre alta cultura e cultura de massa, também creditada ao pós-modernismo.

  7. Perturbation growth in accreting filaments

    CERN Document Server

    Clarke, Seamus D; Hubber, David A

    2016-01-01

    We use smoothed particle hydrodynamic simulations to investigate the growth of perturbations in infinitely long, initially sub-critical but accreting filaments. The growth of these perturbations leads to filament fragmentation and the formation of cores. Most previous work on this subject has been confined to the growth and fragmentation of equilibrium filaments and has found that there exists a preferential fragmentation length scale which is roughly 4 times the filament's diameter. Our results show a more complicated dispersion relation with a series of peaks linking perturbation wavelength and growth rate. These are due to gravo-acoustic oscillations along the longitudinal axis during the sub-critical phase of growth. The positions of the peaks in growth rate have a strong dependence on both the mass accretion rate onto the filament and the temperature of the gas. When seeded with a multi-wavelength density power spectrum there exists a clear preferred core separation equal to the largest peak in the dispe...

  8. A prova retórica do logos no filme narrativo de ficção

    Directory of Open Access Journals (Sweden)

    Carolina Assunção e ALVES

    2016-08-01

    Full Text Available RESUMO O logos consiste na prova retórica técnica/artística, segundo (Aristóteles, 2000, em que o orador demonstra ou tenta demonstrar a verdade pelo discurso; ou seja, trata-se do uso do raciocínio lógico com o objetivo de fundar uma proposição persuasiva. Para autores como (Amossy, 2006 e (Olbrechts-Tyteca e Perelman, 2008, os gêneros discursivos, uma vez que sempre visam a algum tipo de impacto sobre o público, são providos de argumentatividade em diferentes graus e intenções. Neste artigo, pretendemos discutir possibilidades de emprego da prova retórica do logos no filme narrativo de ficção, sob a perspectiva da análise argumentativa do discurso e da teoria semiolinguística (Charaudeau, 2001. O método utilizado consiste na aplicação de algumas categorias do logos à análise argumentativo-discursiva de algumas sequências do filme O Poderoso Chefão II (The Godfather Part II, 1974, de Francis Ford Coppola, levando em consideração os elementos da linguagem cinematográfica envolvidos. Esta pesquisa permitiu verificar a proficuidade da abordagem do filme de ficção como objeto de estudo nessa área, bem como a relação intrínseca entre as provas retóricas do ethos, do pathos e do logos.

  9. In situ synthesis of porous array films on a filament induced micro-gap electrode pair and their use as resistance-type gas sensors with enhanced performances.

    Science.gov (United States)

    Xu, Zongke; Duan, Guotao; Zhang, Hongwen; Wang, Yingying; Xu, Lei; Cai, Weiping

    2015-09-14

    Resistance-type metal-oxide semiconductor gas sensors with high sensitivity and low detection limit have been explored for practical applications. They require both sensing films with high sensitivity to target gases and an appropriate structure of the electrode-equipped substrate to support the sensing films, which is still challenging. In this paper, a new gas sensor of metal-oxide porous array films on a micro-gap electrode pair is designed and implemented by taking ZnO as a model material. First, a micro-gap electrode pair was constructed by sputtering deposition on a filament template, which was used as the sensor's supporting substrate. Then, the sensing film, made up of ZnO porous periodic arrays, was in situ synthesized onto the supporting substrate by a solution-dipping colloidal lithography strategy. The results demonstrated the validity of the strategy, and the as-designed sensor shows a small device-resistance, an enhanced sensing performance with high resolution and an ultralow detection limit. This work provides an alternative method to promote the practical application of resistance-type gas sensors.

  10. Collective alignment of polar filaments by molecular motors.

    Science.gov (United States)

    Ziebert, F; Vershinin, M; Gross, S P; Aranson, I S

    2009-04-01

    We study the alignment of polar biofilaments, such as microtubules and actin, subject to the action of multiple molecular motors attached simultaneously to more than one filament. Focusing on a paradigm model of only two filaments interacting with multiple motors, we were able to investigate in detail the alignment dynamics. While almost no alignment occurs in the case of a single motor, the filaments become rapidly aligned due to the collective action of the motors. Our analysis shows that the alignment time is governed by the number of bound motors and the magnitude of the motors' stepping fluctuations. We predict that the time scale of alignment is in the order of seconds, much faster than that reported for passive crosslink-induced bundling. In vitro experiments on the alignment of microtubules by multiple-motor covered beads are in qualitative agreement. We also discuss another mode of fast alignment of filaments, namely the cooperation between motors and passive crosslinks.

  11. The comparison study of diagnostics of light filaments in air

    Institute of Scientific and Technical Information of China (English)

    HAO; Zuoqiang; ZHANG; Jie; YU; Jin; ZHENG; Zhiyuan; YUAN; Xiaohui; ZHANG; Zhe; LI; Yutong; WANG; Zhaohua; LING; Weijun; WEI; Zhiyi

    2006-01-01

    Long plasma channels in air induced by femtosecond laser pulses are investigated using three different methods, including the cross-section imaging, resistivity measuring and acoustic diagnostics. These methods are based on different properties of the light filaments. A comparison of the three diagnostics shows that the imaging method is the most precise one in studying the filaments distribution and evolution, that the sonographic method is the most convenient approach to detecting long plasma channels by detecting the acoustic wave generation, and that the resistivity measurement can only be applied for giving a rough estimate. The diagnostics of filaments allow us to choose appropriate detecting methods and provide further insight into the dynamic evolution of the light filaments in air.

  12. Health Risks Associated with Exposure to Filamentous Fungi

    Science.gov (United States)

    Egbuta, Mary Augustina; Mwanza, Mulunda

    2017-01-01

    Filamentous fungi occur widely in the environment, contaminating soil, air, food and other substrates. Due to their wide distribution, they have medical and economic implications. Regardless of their use as a source of antibiotics, vitamins and raw materials for various industrially important chemicals, most fungi and filamentous fungi produce metabolites associated with a range of health risks, both in humans and in animals. The association of filamentous fungi and their metabolites to different negative health conditions in humans and animals, has contributed to the importance of investigating different health risks induced by this family of heterotrophs. This review aims to discuss health risks associated with commonly occurring filamentous fungal species which belong to genera Aspergillus, Penicillium and Fusarium, as well as evaluating their pathogenicity and mycotoxic properties. PMID:28677641

  13. Filament propagation length of femtosecond pulses with different transverse modes

    CERN Document Server

    Kaya, N; Kaya, G; Strohaber, J; Kolomenskii, A A; Schuessler, H A

    2014-01-01

    We experimentally studied intense femtosecond pulse filamentation and propagation in water for Gaussian, Laguerre-Gaussian, and Bessel-Gaussian incident beams. These different transverse modes for incident laser pulses were created from an initial Gaussian beam by using a computer generated hologram technique. We found that the length of the filament induced by the Bessel-Gaussian incident beam was longer than that for the other transverse modes under the conditions of the same peak intensity, pulse duration, and the size of the central part of the beam. To better understand the Bessel-Gaussian beam propagation, we performed a more detailed study of the filament length as a function of the number of radial modal lobes. The length increased with the number of lobes, implying that the radial modal lobes serve as an energy reservoir for the filament formed by the central intensity peak.

  14. Health Risks Associated with Exposure to Filamentous Fungi

    Directory of Open Access Journals (Sweden)

    Mary Augustina Egbuta

    2017-07-01

    Full Text Available Filamentous fungi occur widely in the environment, contaminating soil, air, food and other substrates. Due to their wide distribution, they have medical and economic implications. Regardless of their use as a source of antibiotics, vitamins and raw materials for various industrially important chemicals, most fungi and filamentous fungi produce metabolites associated with a range of health risks, both in humans and in animals. The association of filamentous fungi and their metabolites to different negative health conditions in humans and animals, has contributed to the importance of investigating different health risks induced by this family of heterotrophs. This review aims to discuss health risks associated with commonly occurring filamentous fungal species which belong to genera Aspergillus, Penicillium and Fusarium, as well as evaluating their pathogenicity and mycotoxic properties.

  15. Perturbation growth in accreting filaments

    Science.gov (United States)

    Clarke, S. D.; Whitworth, A. P.; Hubber, D. A.

    2016-05-01

    We use smoothed particle hydrodynamic simulations to investigate the growth of perturbations in infinitely long filaments as they form and grow by accretion. The growth of these perturbations leads to filament fragmentation and the formation of cores. Most previous work on this subject has been confined to the growth and fragmentation of equilibrium filaments and has found that there exists a preferential fragmentation length-scale which is roughly four times the filament's diameter. Our results show a more complicated dispersion relation with a series of peaks linking perturbation wavelength and growth rate. These are due to gravo-acoustic oscillations along the longitudinal axis during the sub-critical phase of growth. The positions of the peaks in growth rate have a strong dependence on both the mass accretion rate onto the filament and the temperature of the gas. When seeded with a multiwavelength density power spectrum, there exists a clear preferred core separation equal to the largest peak in the dispersion relation. Our results allow one to estimate a minimum age for a filament which is breaking up into regularly spaced fragments, as well as an average accretion rate. We apply the model to observations of filaments in Taurus by Tafalla & Hacar and find accretion rates consistent with those estimated by Palmeirim et al.

  16. Activity Cycle of Solar Filaments

    Indian Academy of Sciences (India)

    K. J. Li; Q. X. Li; P. X. Gao; J. Mu; H. D. Chen; T. W. Su

    2007-06-01

    Long-term variation in the distribution of the solar filaments observed at the Observatorie de Paris, Section de Meudon from March 1919 to December 1989 is presented to compare with sunspot cycle and to study the periodicity in the filament activity, namely the periods of the coronal activity with the Morlet wavelet used. It is inferred that the activity cycle of solar filaments should have the same cycle length as sunspot cycle, but the cycle behavior of solar filaments is globally similar in profile with, but different in detail from, that of sunspot cycles. The amplitude of solar magnetic activity should not keep in phase with the complexity of solar magnetic activity. The possible periods in the filament activity are about 10.44 and 19.20 years. The wavelet local power spectrum of the period 10.44 years is statistically significant during the whole consideration time. The wavelet local power spectrum of the period 19.20 years is under the 95% confidence spectrum during the whole consideration time, but over the mean red-noise spectrum of = 0.72 before approximate Carrington rotation number 1500, and after that the filament activity does not statistically show the period. Wavelet reconstruction indicates that the early data of the filament archive (in and before cycle 16) are more noiseful than the later (in and after cycle 17).

  17. Comparative Biomechanics of Thick Filaments and Thin Filaments with Functional Consequences for Muscle Contraction

    Directory of Open Access Journals (Sweden)

    Mark S. Miller

    2010-01-01

    Full Text Available The scaffold of striated muscle is predominantly comprised of myosin and actin polymers known as thick filaments and thin filaments, respectively. The roles these filaments play in muscle contraction are well known, but the extent to which variations in filament mechanical properties influence muscle function is not fully understood. Here we review information on the material properties of thick filaments, thin filaments, and their primary constituents; we also discuss ways in which mechanical properties of filaments impact muscle performance.

  18. Centromeres of filamentous fungi

    Science.gov (United States)

    Smith, Kristina M.; Galazka, Jonathan M.; Phatale, Pallavi A.; Connolly, Lanelle R.; Freitag, Michael

    2012-01-01

    How centromeres are assembled and maintained remains one of the fundamental questions in cell biology. Over the past 20 years the idea of centromeres as precise genetic loci has been replaced by the realization that it is predominantly the protein complement that defines centromere localization and function. Thus, placement and maintenance of centromeres are excellent examples of epigenetic phenomena in the strict sense. In contrast, the highly derived “point centromeres” of the budding yeast Saccharomyces cerevisiae and its close relatives are counterexamples for this general principle of centromere maintenance. While we have learned much in the past decade, it remains unclear if mechanisms for epigenetic centromere placement and maintenance are shared amongst various groups of organisms. For that reason it seems prudent to examine species from many different phylogenetic groups with the aim to extract comparative information that will yield a more complete picture of cell division in all eukaryotes. This review addresses what has been learned by studying the centromeres of filamentous fungi, a large, heterogeneous group of organisms that includes important plant, animal and human pathogens, saprobes and symbionts that fulfill essential roles in the biosphere, as well as a growing number of taxa that have become indispensable for industrial use. PMID:22752455

  19. Collisions of Vortex Filament Pairs

    Science.gov (United States)

    Banica, Valeria; Faou, Erwan; Miot, Evelyne

    2014-12-01

    We consider the problem of collisions of vortex filaments for a model introduced by Klein et al. (J Fluid Mech 288:201-248, 1995) and Zakharov (Sov Phys Usp 31(7):672-674, 1988, Lect. Notes Phys 536:369-385, 1999) to describe the interaction of almost parallel vortex filaments in three-dimensional fluids. Since the results of Crow (AIAA J 8:2172-2179, 1970) examples of collisions are searched as perturbations of antiparallel translating pairs of filaments, with initial perturbations related to the unstable mode of the linearized problem; most results are numerical calculations. In this article, we first consider a related model for the evolution of pairs of filaments, and we display another type of initial perturbation leading to collision in finite time. Moreover, we give numerical evidence that it also leads to collision through the initial model. We finally study the self-similar solutions of the model.

  20. Filament Identification through Mathematical Morphology

    OpenAIRE

    Koch, Eric W.; Rosolowsky, Erik W.

    2015-01-01

    We present a new algorithm for detecting filamentary structure FilFinder. The algorithm uses the techniques of mathematical morphology for filament identification, presenting a complementary approach to current algorithms which use matched filtering or critical manifolds. Unlike other methods, FilFinder identifies filaments over a wide dynamic range in brightness. We apply the new algorithm to far infrared imaging data of dust emission released by the Herschel Gould Belt Survey team. Our prel...

  1. Rate-dependent force, intracellular calcium, and action potential voltage alternans are modulated by sarcomere length and heart failure induced-remodeling of thin filament regulation in human heart failure: A myocyte modeling study.

    Science.gov (United States)

    Zile, Melanie A; Trayanova, Natalia A

    2016-01-01

    Microvolt T-wave alternans (MTWA) testing identifies heart failure patients at risk for lethal ventricular arrhythmias at near-resting heart rates (voltage alternans (APV-ALT), the cellular driver of MTWA. Our goal was to uncover the mechanisms linking APV-ALT and FORCE-ALT in failing human myocytes and to investigate how the link between those alternans was affected by pacing rate and by physiological conditions such as sarcomere length and heart failure induced-remodeling of mechanical parameters. To achieve this, a mechanically-based, strongly coupled human electromechanical myocyte model was constructed. Reducing the sarcoplasmic reticulum calcium uptake current (Iup) to 27% was incorporated to simulate abnormal calcium handling in human heart failure. Mechanical remodeling was incorporated to simulate altered thin filament activation and crossbridge (XB) cycling rates. A dynamical pacing protocol was used to investigate the development of intracellular calcium concentration ([Ca]i), voltage, and active force alternans at different pacing rates. FORCE-ALT only occurred in simulations incorporating reduced Iup, demonstrating that alternans in the intracellular calcium concentration (CA-ALT) induced FORCE-ALT. The magnitude of FORCE-ALT was found to be largest at clinically relevant pacing rates (<110 bpm), where APV-ALT was smallest. We found that the magnitudes of FORCE-ALT, CA-ALT and APV-ALT were altered by heart failure induced-remodeling of mechanical parameters and sarcomere length due to the presence of myofilament feedback. These findings provide important insight into the relationship between heart-failure-induced electrical and mechanical alternans and how they are altered by physiological conditions at near-resting heart rates.

  2. Actin filament-associated protein 1 (AFAP-1) is a key mediator in inflammatory signaling-induced rapid attenuation of intrinsic P-gp function in human brain capillary endothelial cells.

    Science.gov (United States)

    Hoshi, Yutaro; Uchida, Yasuo; Tachikawa, Masanori; Ohtsuki, Sumio; Terasaki, Tetsuya

    2017-01-23

    The purpose of this study was to identify regulatory molecule(s) involved in the inflammatory signaling-induced decrease in P-glycoprotein (P-gp) efflux function at the blood-brain barrier (BBB) that may occur in brain diseases. We confirmed that in vivo P-gp efflux activity at the BBB was decreased without any change in P-gp protein expression level in a mouse model of acute inflammation induced by 3 mg/kg lipopolysaccharide. In a human BBB model cell line (human brain capillary endothelial cells; hCMEC/D3), 1-h treatment with 10 ng/mL tumor necrosis factor-α (TNF-α; an inflammatory mediator) rapidly reduced P-gp efflux activity, but had no effect on P-gp protein expression level. To clarify the non-transcriptional mechanism that causes the decrease in intrinsic efflux activity of P-gp in acute inflammation, we applied comprehensive quantitative phosphoproteomics to compare hCMEC/D3 cells treated with TNF-α and vehicle (control). Actin filament-associated protein-1 (AFAP-1), MAPK1, and transcription factor AP-1 (AP-1) were significantly phosphorylated in TNF-α-treated cells, and were selected as candidate proteins. In validation experiments, knockdown of AFAP-1 expression blocked the reduction in P-gp efflux activity by TNF-α treatment, whereas inhibition of MAPK function or knockdown of AP-1 expression did not. Quantitative targeted absolute proteomics revealed that the reduction in P-gp activity by TNF-α did not require any change in P-gp protein expression levels in the plasma membrane. Our results demonstrate that AFAP-1 is a key mediator in the inflammatory signaling-induced, translocation-independent rapid attenuation of P-gp efflux activity in human brain capillary endothelial cells.

  3. Mundo Real e Mundo Ideal em Rousseau: da Necessidade da Ficção para Pensar o Político

    Directory of Open Access Journals (Sweden)

    Maria Leone

    2015-01-01

    Full Text Available RESUMO:A hipótese desenvolvida nos leva a confrontar três textos do corpusrousseauísta: o Segundo Discurso, Júlia ou A Nova Heloísa e o extrato do Primeiro Diálogo, em que há a ficção do mundo ideal, textos que, apesar do seu estatuto genérico diferente, estão em coerência e convergência teórica. Desejamos evidenciar um aspecto da unidade problemática do pensamento de Rousseau concernente à abordagem crítica da sociedade de seus contemporâneos e sua concepção do papel das Letras e dos Espetáculos. A preocupação do filósofo é de refundar a natureza humana, a fim de lançar as bases de uma nova organização social. Nessa empreitada, a ficção desempenha um papel crucial, o prefácio do Segundo Discurso o comprova: para bem conhecer o homem atual, deve-se supor o que ele não é mais. O homem do estado de natureza, ser de ficção, cujas paixões são retas e naturais, é o modelo teórico que reativa a sociedade dos seres ideais de Júlia. Dessa forma, a ficção é chamada a desempenhar um papel referencial fundamental para o pensamento social e político de Rousseau, aparecendo como um poderoso meio de ação sobre o público. O romance pode reeducar os povos corrompidos, pois, assim como o teatro, como denuncia a Carta a d’Alembert, possui os meios para perverter uma sociedade tida como virtuosa.

  4. Evolutionarily divergent, unstable filamentous actin is essential for gliding motility in apicomplexan parasites.

    Science.gov (United States)

    Skillman, Kristen M; Diraviyam, Karthikeyan; Khan, Asis; Tang, Keliang; Sept, David; Sibley, L David

    2011-10-01

    Apicomplexan parasites rely on a novel form of actin-based motility called gliding, which depends on parasite actin polymerization, to migrate through their hosts and invade cells. However, parasite actins are divergent both in sequence and function and only form short, unstable filaments in contrast to the stability of conventional actin filaments. The molecular basis for parasite actin filament instability and its relationship to gliding motility remain unresolved. We demonstrate that recombinant Toxoplasma (TgACTI) and Plasmodium (PfACTI and PfACTII) actins polymerized into very short filaments in vitro but were induced to form long, stable filaments by addition of equimolar levels of phalloidin. Parasite actins contain a conserved phalloidin-binding site as determined by molecular modeling and computational docking, yet vary in several residues that are predicted to impact filament stability. In particular, two residues were identified that form intermolecular contacts between different protomers in conventional actin filaments and these residues showed non-conservative differences in apicomplexan parasites. Substitution of divergent residues found in TgACTI with those from mammalian actin resulted in formation of longer, more stable filaments in vitro. Expression of these stabilized actins in T. gondii increased sensitivity to the actin-stabilizing compound jasplakinolide and disrupted normal gliding motility in the absence of treatment. These results identify the molecular basis for short, dynamic filaments in apicomplexan parasites and demonstrate that inherent instability of parasite actin filaments is a critical adaptation for gliding motility.

  5. Evolutionarily divergent, unstable filamentous actin is essential for gliding motility in apicomplexan parasites.

    Directory of Open Access Journals (Sweden)

    Kristen M Skillman

    2011-10-01

    Full Text Available Apicomplexan parasites rely on a novel form of actin-based motility called gliding, which depends on parasite actin polymerization, to migrate through their hosts and invade cells. However, parasite actins are divergent both in sequence and function and only form short, unstable filaments in contrast to the stability of conventional actin filaments. The molecular basis for parasite actin filament instability and its relationship to gliding motility remain unresolved. We demonstrate that recombinant Toxoplasma (TgACTI and Plasmodium (PfACTI and PfACTII actins polymerized into very short filaments in vitro but were induced to form long, stable filaments by addition of equimolar levels of phalloidin. Parasite actins contain a conserved phalloidin-binding site as determined by molecular modeling and computational docking, yet vary in several residues that are predicted to impact filament stability. In particular, two residues were identified that form intermolecular contacts between different protomers in conventional actin filaments and these residues showed non-conservative differences in apicomplexan parasites. Substitution of divergent residues found in TgACTI with those from mammalian actin resulted in formation of longer, more stable filaments in vitro. Expression of these stabilized actins in T. gondii increased sensitivity to the actin-stabilizing compound jasplakinolide and disrupted normal gliding motility in the absence of treatment. These results identify the molecular basis for short, dynamic filaments in apicomplexan parasites and demonstrate that inherent instability of parasite actin filaments is a critical adaptation for gliding motility.

  6. O retorno à natureza na ficção brasileira do começo do século XXI

    Directory of Open Access Journals (Sweden)

    Luciano Brito

    2014-07-01

    Full Text Available Este artigo procura entender a tentativa de retorno a representações da natureza na ficção brasileira do começo do século XXI, a partir dos romances Nove noites (2002 de Bernardo Carvalho, Órfãos do Eldorado (2008 de Milton Hatoum e Barba ensopada de sangue (2012 de Daniel Galera. Não sendo mais o sinal de uma necessidade de reivindicação de um patrimônio cultural nacional, como foi o seu papel durante séculos de historiografia literária e cultural, a natureza ressurge na ficção brasileira, de modo inédito, por outros sentidos – de revelação, destruição ou utopia –, excedendo e renovando sua imagem inicial, propagandística, de representação de uma nação. A consequência dessa passagem simbólica, e que mimetizaria o movimento da ficção brasileira atual, é a sua desapropriação como um bem orgulhosamente nacional e a sua integração no que poderíamos chamar de literatura mundial.

  7. L’estat de la qüestió del patrimoni bibliogràfic en les biblioteques públiques de Catalunya

    Directory of Open Access Journals (Sweden)

    Rodrigo Fuentes, Victoria

    2015-12-01

    Full Text Available La presència del patrimoni bibliogràfic en les biblioteques públiques catalanes és un fet real, identitari i que singularitza la biblioteca que el posseeix. D’altra banda, l’observació de la realitat que ens porta a creure que la difusió del patrimoni no és una pràctica habitual en aquestes biblioteques i a plantjar-nos una hipòtesi: el patrimoni bibliogràfic de les biblioteques públiques –espai privilegiat de memòria– és un bé desconegut per la seva comunitat. Aquesta hipòtesi és el punt de partida del nostre treball. Una investigació en la que ens proposem assolir un objectiu principal: presentar l’estat de la qüestió del patrimoni bibliogràfic a les biblioteques públiques. I ho farem amb el testimoni d’onze biblioteques: BP de Girona, BP Gual i Pujadas, B Jordi Rubió i Balaguer, B Comarcal Josep Finestres, B Lambert Mata, BP de Lleida, B Margarida de Montferrat, B Marià Vayreda, BP de Tarragona, B Central de Terrassa, B Central Xavier Amorós.

  8. The blistering of a viscoelastic filament of a droplet of saliva

    CERN Document Server

    Wagner, Christian; Eggers, Jens

    2009-01-01

    A fluid dynamics video of the break up of a droplet of saliva is shown. First a viscoelastic filament is formed and than the blistering of this filament is shown. Finally, a flow induced phase separation takes place nanometer sized solid fiber remains that consist out of the biopolymers.

  9. Manipulation of flow around bluff bodies by flexible slender filaments

    Science.gov (United States)

    Omidyeganeh, Mohammad; Pinelli, Alfredo

    2016-11-01

    Manipulation of bluff bodies wakes to control the intensity of fluid forces and the induced solid vibrations is of paramount importance. A biomimetic passive control based on the use of flexible slender appendages protruding from the body into the separated region has shown promising achievements in drag reduction and moderating force fluctuations. The present research aimed at understating and optimizing the physical properties and the arrangement of elongated flexible filaments to delay the 3D transition of the wake in terms of Reynolds number, mean drag reduction, and mitigation of the force fluctuations. The numerical campaign unveiled the role of flexural stiffness of the filaments: matching the natural frequency with the vortex shedding frequency enhances the mixing at the lee side. However, softer filaments (i.e. larger time scales) lock-in on either side of mid plane breaking the symmetry of the flow field (inducing a net lift force). In addition to 2D effects, the presence of filaments can interfere with the 3D bifurcation process resulting in a delay of the spanwise destabilization of the wake. The most effective parameter for this transitional interference is the spacing between filaments that should be smaller than the wavelength of the dominant 3D unstable mode.

  10. Chloroplast actin filaments organize meshwork on the photorelocated chloroplasts in the moss Physcomitrella patens.

    Science.gov (United States)

    Yamashita, Hiroko; Sato, Yoshikatsu; Kanegae, Takeshi; Kagawa, Takatoshi; Wada, Masamitsu; Kadota, Akeo

    2011-02-01

    Cytoskeleton dynamics during phototropin-dependent chloroplast photorelocation movement was analyzed in protonemal cells of actin- and microtubule-visualized lines of Physcomitrella patens expressing GFP- or tdTomato-talin and GFP-tubulin. Using newly developed epi- and trans-microbeam irradiation systems that permit fluorescence observation of the cell under blue microbeam irradiation inducing chloroplast relocation, it was revealed that meshwork of actin filaments formed at the chloroplast-accumulating area both in the avoidance and accumulation movements. The structure disappeared soon when blue microbeam was turned off, and it was not induced under red microbeam irradiation that did not evoke chloroplast relocation movement. In contrast, no apparent change in microtubule organization was detected during the movements. The actin meshwork was composed of short actin filaments distinct from the cytoplasmic long actin cables and was present between the chloroplasts and plasma membrane. The short actin filaments emerged from around the chloroplast periphery towards the center of chloroplast. Showing highly dynamic behavior, the chloroplast actin filaments (cp-actin filaments) were rapidly organized into meshwork on the chloroplast surface facing plasma membrane. The actin filament configuration on a chloroplast led to the formation of actin meshwork area in the cell as the chloroplasts arrived at and occupied the area. After establishment of the meshwork, cp-actin filaments were still highly dynamic, showing appearance, disappearance, severing and bundling of filaments. These results indicate that the cp-actin filaments have significant roles in the chloroplast movement and positioning in the cell.

  11. Boolean gates on actin filaments

    Science.gov (United States)

    Siccardi, Stefano; Tuszynski, Jack A.; Adamatzky, Andrew

    2016-01-01

    Actin is a globular protein which forms long polar filaments in the eukaryotic cytoskeleton. Actin networks play a key role in cell mechanics and cell motility. They have also been implicated in information transmission and processing, memory and learning in neuronal cells. The actin filaments have been shown to support propagation of voltage pulses. Here we apply a coupled nonlinear transmission line model of actin filaments to study interactions between voltage pulses. To represent digital information we assign a logical TRUTH value to the presence of a voltage pulse in a given location of the actin filament, and FALSE to the pulse's absence, so that information flows along the filament with pulse transmission. When two pulses, representing Boolean values of input variables, interact, then they can facilitate or inhibit further propagation of each other. We explore this phenomenon to construct Boolean logical gates and a one-bit half-adder with interacting voltage pulses. We discuss implications of these findings on cellular process and technological applications.

  12. Galaxy pairs align with galactic filaments

    CERN Document Server

    Tempel, Elmo

    2015-01-01

    Context. Gravitational collapse theory and numerical simulations suggest that the velocity field within large-scale galaxy filaments is dominated by motions along the filaments. Aims. Our aim is to check whether observational data reveal any preferred orientation of galaxy pairs with respect to the underlying filaments as a result of the expectedly anisotropic velocity field. Methods. We use galaxy pairs and galaxy filaments identified from the Sloan Digital Sky Survey data. For filament extraction, we use the Bisous model that is based the marked point process technique. During the filament detection, we use the centre point of each pair instead of the positions of galaxies to avoid a built-in influence of pair orientation on the filament construction. For pairs lying within filaments (3012 cases), we calculate the angle between the line connecting galaxies of each pair and their host filament. To avoid redshift-space distortions, the angle is measured in the plain of the sky. Results. The alignment analysis...

  13. Effect of superconductor filament magnetization on the field errors

    CERN Document Server

    Wolf, R

    1999-01-01

    One of the main source of field errors in a superconducting magnet is the magnetization M of the superconducting filaments. Screening currents, of persistent nature, are induced by any. field change during operation of the magnet. This chapter describes the models for the calculation of these effects and the parameters to be defined in ROXIE. (3 refs).

  14. Temperature Controlled Filamentation in Argon Gas

    Institute of Scientific and Technical Information of China (English)

    CAO Shi-Ying; KONG Wei-Peng; SONG Zhen-Ming; QIN Yu; LI Ru-Xin; WANG Qing-Yue; ZHANG Zhi-Gang

    2008-01-01

    Temperature controlled filamentation is experimentally demonstrated in a temperature gradient gas-filled tube.The proper position of the tube is heated by a furnace and two ends of the tube are cooled by air. The experimental results show that multiple filaments are shrunken into a single fila.ment or no filament only by increasing the temperature at the beginning of the filament. This technique offers another degree of freedom of controlling the filamentation and opens a new way for intense monocycle pulse generation through gradient temperature in a noble gas.

  15. Intermediate Filaments in Caenorhabditis elegans.

    Science.gov (United States)

    Zuela, Noam; Gruenbaum, Yosef

    2016-01-01

    More than 70 different genes in humans and 12 different genes in Caenorhabditis elegans encode the superfamily of intermediate filament (IF) proteins. In C. elegans, similar to humans, these proteins are expressed in a cell- and tissue-specific manner, can assemble into heteropolymers and into 5-10nm wide filaments that account for the principal structural elements at the nuclear periphery, nucleoplasm, and cytoplasm. At least 5 of the 11 cytoplasmic IFs, as well as the nuclear IF, lamin, are essential. In this chapter, we will include a short review of our current knowledge of both cytoplasmic and nuclear IFs in C. elegans and will describe techniques used for their analyses.

  16. Angle-resolved multioctave supercontinua from mid-infrared laser filaments.

    Science.gov (United States)

    Mitrofanov, A V; Voronin, A A; Sidorov-Biryukov, D A; Mitryukovsky, S I; Rozhko, M V; Pugžlys, A; Fedotov, A B; Panchenko, V Ya; Baltuška, A; Zheltikov, A M

    2016-08-01

    Angle-resolved spectral analysis of a multioctave high-energy supercontinuum output of mid-infrared laser filaments is shown to provide a powerful tool for understanding intricate physical scenarios behind laser-induced filamentation in the mid-infrared. The ellipticity of the mid-infrared driver beam breaks the axial symmetry of filamentation dynamics, offering a probe for a truly (3+1)-dimensional spatiotemporal evolution of mid-IR pulses in the filamentation regime. With optical harmonics up to the 15th order contributing to supercontinuum generation in such filaments alongside Kerr-type and ionization-induced nonlinearities, the output supercontinuum spectra span over five octaves from the mid-ultraviolet deep into the mid-infrared. Full (3+1)-dimensional field evolution analysis is needed for an adequate understanding of this regime of laser filamentation. Supercomputer simulations implementing such analysis articulate the critical importance of angle-resolved measurements for both descriptive and predictive power of filamentation modeling. Strong enhancement of ionization-induced blueshift is shown to offer new approaches in filamentation-assisted pulse compression, enabling the generation of high-power few- and single-cycle pulses in the mid-infrared.

  17. Edgar Allan Poe e o surgimento do conto enquanto gênero de ficção

    Directory of Open Access Journals (Sweden)

    Greicy Bellin

    2011-10-01

    Full Text Available http://dx.doi.org/10.5007/2175-7917.2011v16n2p41 O objetivo do presente trabalho é descrever, discutir e analisar o surgimento do conto enquanto gênero de ficção, tendo como ponto de partida uma reflexão a respeito de Review of Twice-Told Tales, resenhas críticas de Edgar Allan Poe sobre os contos de um de seus contemporâneos, o escritor Nathaniel Hawthorne. Em tais textos, Poe apresenta a teoria da unidade de efeito, juntamente com a tese de que o conto poderia ser o veículo apropriado para a expressão máxima dos talentos de um artista. Além disso, será analisado o contexto literário norte-americano de princípios do século XIX, período no qual Poe produziu sua obra e que assistiu à consolidação do conto enquanto gênero ficcional. Neste sentido, serão abordados alguns aspectos do referencial teórico existente sobre narrativas curtas, a fim de problematizar alguns aspectos suscitados pela análise de Poe. Por último, serão feitas algumas considerações a respeito das ressonâncias de Poe na crítica literária, considerando que Mário de Andrade, Machado de Assis e Julio Cortázar retomam, rediscutem e reelaboram algumas noções propostas por Poe a respeito do conto.

  18. Ficções urbanas: estratégias para a ocupação das cidades

    Directory of Open Access Journals (Sweden)

    Andréa Tavares

    2010-01-01

    Full Text Available As intervenções do grafite e da pichação na cidade criam fissuras no real que, por vezes, geram reações violentas, já que a maioria de nós tem dificuldade em lidar com fenômenos atuantes fora da dita ordem natural das coisas. Seres fantásticos e uma tipografia hermética desafiam não só o senso comum, mas também as leis. "Ficções urbanas" pretende analisar as diferenças entre as estratégias da pichação e do grafite na cidade de São Paulo. Esses procedimentos são considerados em suas dinâmicas de apropriação do espaço cotidiano e em relação ao quadro teórico do debate artístico contemporâneo.Interventions on urban space such as graffiti and "pichação" create cracks in the real that sometimes may generate violent reactions, since most of us find difficulties in dealing with phenomena that stretch out our sense of security. Fantastic creatures and a typography that is hard to read defy not only common sense, but also the laws. The text "Urban fiction" analyzes the differences between the strategies of graffiti and "pichação" in São Paulo. These procedures are considered in their dynamics to take over urban landscape and examined in relation to the theoretical framework of contemporary art debate.

  19. Ficção a trois: erotismo, mercado e valor em trilogias eróticas de autoria feminina

    Directory of Open Access Journals (Sweden)

    Luciana Borges

    2013-09-01

    Full Text Available O presente trabalho aborda duas trilogias de ficção erótica de autoria feminina considerando a relação entre literatura, valor de mercado e circulação de capital erótico. Fifty Shades Trilogy (Cinquenta tons de cinza, da inglesa E L James, lançada em 2012 no Brasil e a Trilogia Obscena, da brasileira Hilda Hilst, lançada na década de 1990, compõem-se de modo que pode ser considerado diametralmente oposto quanto a suas estratégias de composição formal, construção temática do erotismo e limites transgressivos da pornografia. Se na primeira encontra-se o tom folhetinesco das obras comerciais, na segunda, o sentido da densidade própria do texto literário transita pelos limites da não fabulação, posto que a narratividade é decomposta por mecanismos reflexivos que remetem a uma crítica do campo literário. A reflexão proposta parte da relação com a conformidade ou desconformidade em termos do instituído ao gênero ficcional literatura erótica e ao campo do pornô em geral, às investiduras de gênero que constroem o masculino como ativo e o feminino como passivo e à lógica do mercado editorial em torno do que constitui um best seller e sua circulação no meio leitor.

  20. Towards filament free semiconductor lasers

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter; Skovgaard, Peter M. W.

    2000-01-01

    We outline physical models and simulations for suppression of self-focusing and filamentation in large aperture semiconductor lasers. The principal technical objective is to generate multi-watt CW or quasi-CW outputs with nearly diffraction limited beams, suitable for long distance free space...... propagation structures in lasers and amplifiers which suppress lateral reflections....

  1. Capillary thinning of polymeric filaments

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Szabo, Peter

    1999-01-01

    The capillary thinning of filaments of a Newtonian polybutene fluid and a viscoelastic polyisobutylene solution are analyzed experimentally and by means of numerical simulation. The experimental procedure is as follows. Initially, a liquid sample is placed between two cylindrical plates. Then, th...... and quantified. (C) 1999 The Society of Rheology. [S0148-6055(99)00103-0]....

  2. Merger of Long Vortex Filaments

    CERN Document Server

    Khandekar, Akshay

    2012-01-01

    This fluid dynamics video demonstrates the merger of long vortex filaments is shown experimentally. Two counter-rotating vortices are generated using in a tank with very high aspect ratio. PIV demonstrates the merger of the vortices within a single orbit.

  3. Picosecond laser filamentation in air

    Science.gov (United States)

    2016-09-02

    LeibnizUniversityHannover,Welfengarten 1, D-30167Hannover, Germany 3 CEA-DAM,DIF, F-91297Arpajon, France 4 Univ.Bordeaux—CNRS—CEA,Centre Lasers ...optics.arizona.edu Keywords: laser filamentation, picosecond laser pulses, nonlinear propagation, optical ionization Abstract The propagation of intense

  4. Transient filament stretching rheometer II

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

    1997-01-01

    The Lagrangian sspecification is used to simulate the transient stretching filament rheometer. Simulations are performed for dilute PIB-solutions modeled as a four mode Oldroyd-B fluid and a semidilute PIB-solution modeled as a non-linear single integral equation. The simulations are compared...

  5. Filament Winding. A Unified Approach

    NARCIS (Netherlands)

    Koussios, S.

    2004-01-01

    In this dissertation we have presented an overview and comprehensive treatment of several facets of the filament winding process. With the concepts of differential geometry and the theory of thin anisotropic shells of revolution, a parametric shape generator has been formulated for the design proced

  6. Role of Intermediate Filaments in Vesicular Traffic

    Directory of Open Access Journals (Sweden)

    Azzurra Margiotta

    2016-04-01

    Full Text Available Intermediate filaments are an important component of the cellular cytoskeleton. The first established role attributed to intermediate filaments was the mechanical support to cells. However, it is now clear that intermediate filaments have many different roles affecting a variety of other biological functions, such as the organization of microtubules and microfilaments, the regulation of nuclear structure and activity, the control of cell cycle and the regulation of signal transduction pathways. Furthermore, a number of intermediate filament proteins have been involved in the acquisition of tumorigenic properties. Over the last years, a strong involvement of intermediate filament proteins in the regulation of several aspects of intracellular trafficking has strongly emerged. Here, we review the functions of intermediate filaments proteins focusing mainly on the recent knowledge gained from the discovery that intermediate filaments associate with key proteins of the vesicular membrane transport machinery. In particular, we analyze the current understanding of the contribution of intermediate filaments to the endocytic pathway.

  7. Fossil evidence for spin alignment of Sloan Digital Sky Survey galaxies in filaments

    Science.gov (United States)

    Jones, Bernard J. T.; van de Weygaert, Rien; Aragón-Calvo, Miguel A.

    2010-10-01

    We search for and find fossil evidence that the spin axes of galaxies in cosmic web filaments relative to their host filaments are not randomly distributed. This indicates the fact that the action of large-scale tidal torques affected the alignments of galaxies located in cosmic filaments. To this end, we constructed a catalogue of clean filaments containing edge-on galaxies. We started by applying the multiscale morphology filter technique to the galaxies in a redshift-distortion-corrected version of the Sloan Digital Sky Survey Data Release 5. From this sample, we extracted 426 filaments that contained edge-on galaxies (b/a spine of the parent filament (cosθ < 0.2). The candidate objects are found in relatively less dense filaments. This happens because galaxies in such locations suffer less interaction with surrounding galaxies and consequently better preserve their tidally induced orientations relative to the parent filament. These objects are also less intrinsically bright and smaller than their counterparts elsewhere in the filaments. The technique of searching for fossil evidence of alignment yields relatively few candidate objects, but it does not suffer from the dilution effects inherent in correlation analysis of large samples. The candidate objects could be the subjects of a programme of observations aimed at understanding in what way they might differ from their non-aligned counterparts.

  8. Large-scale Motion of Solar Filaments

    Indian Academy of Sciences (India)

    Pavel Ambrož; Alfred Schroll

    2000-09-01

    Precise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.

  9. Preparation and Characterization of Carbon Filaments

    Science.gov (United States)

    1991-04-01

    catalysts gave straight filaments, while the use of nickel and other catalysts resulted in a variety of vermicular forms of filaments. Ferrocene, (C5H5)2Fe...vapor deposition of carbon filaments is presented along with a theory for the vermicular growth of filaments on quartz substrates. I U I I I I I I...one hour. The experimental details of the matrix and results are discussed, also theories for the role of hydrogen and the vermicular growth of

  10. Analysis of a filament stretching rheometer

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

    1996-01-01

    A finite element analysis of the stretching filament rheometer of Tirtaadmadja and Sridhar (1993) is presenetd. Simulations of the stretching of a filament of the polymet test solution, fluid A, between two plates are shown.......A finite element analysis of the stretching filament rheometer of Tirtaadmadja and Sridhar (1993) is presenetd. Simulations of the stretching of a filament of the polymet test solution, fluid A, between two plates are shown....

  11. Elastic filament velocimetry (EFV)

    Science.gov (United States)

    Fu, M. K.; Fan, Y.; Byers, C. P.; Chen, T.-H.; Arnold, C. B.; Hultmark, M.

    2017-02-01

    A novel method for velocity measurements in both gaseous and liquid flows is presented. The sensing element is comprised of a free-standing electrically conductive nanoscale ribbon suspended between silicon supports. Due to its minuscule size, the nanoribbon deflects in flow due to viscously dominated fluid forcing inducing an axial strain of the sensing element. The strain leads to a resistance change, which is measurable through a simple Wheatstone bridge circuit and can be related to the flow velocity through semi-analytic analysis. Two methods of characterization are employed to validate the sensor functionality. First, confocal microscopy was used to validate physical models and assumptions through imaging of the nanoribbon deformation under different fluid loads. Second, the resistance measurements of various nanoribbons under different flow conditions exhibited sensitivity to fluid flow consistent with lower order model predictions.

  12. Remote electrical arc suppression by laser filamentation

    CERN Document Server

    Schubert, Elise; Kasparian, Jérôme; Wolf, Jean-Pierre

    2015-01-01

    We investigate the interaction of narrow plasma channels formed in the filamentation of ultrashort laser pulses, with a DC high voltage. The laser filaments prevent electrical arcs by triggering corona that neutralize the high-voltage electrodes. This phenomenon, due to the electric field modulation and free electron release around the filament, opens new prospects to lightning and over-voltage mitigation.

  13. Semiflexible biopolymers: Microrheology and single filament condensation

    Science.gov (United States)

    Schnurr, Bernhard

    Polymers and their elementary subunits, called monomers, come in an immense variety of structures and sizes, and are of great importance for their material properties as well as a multitude of biological functions. The emphasis here is on semiflexible polymers, which are identified by their intermediate degree of stiffness. Their individual as well as their collective properties when assembled into entangled networks is a topic of great interest to polymer physics, materials science, and biology. Some of the most important semiflexible polymers are biopolymers, with such prominent examples as DNA, F-actin, and microtubules. Their functions range from their use as structural elements in the cytoskeleton of most plant and animal cells, to their role as transport tracks for molecular motors, and the storage of genetic information in their linear sequence. The two parts of this experimental and theoretical thesis address single filament aspects as well as network properties of solutions of semiflexible polymers. In the first part, we describe an optical technique for measuring the bulk properties of soft materials at the local scale. We apply it to a solution of entangled, filamentous actin, a particularly difficult material to characterize with conventional techniques. Beyond a description of measurements and apparatus, we also discuss, from a theoretical point of view, the interpretation and fundamental limitations of this and other microrheological techniques. In the second part, we describe the condensation dynamics of a single, semiflexible filament, induced by changing solvent conditions. A biologically important example of this phenomenon is the condensation of DNA into toroidal structures, which occurs, for instance, in viral capsids. Our observations of a molecular simulation motivate an unexpected pathway of collapse via a series of metastable intermediates we call ``racquet'' states. The analysis of the conformational energies of these structures in the

  14. Ubiquitylation by Trim32 causes coupled loss of desmin, Z-bands, and thin filaments in muscle atrophy

    Science.gov (United States)

    Cohen, Shenhav; Zhai, Bo; Gygi, Steven P.

    2012-01-01

    During muscle atrophy, myofibrillar proteins are degraded in an ordered process in which MuRF1 catalyzes ubiquitylation of thick filament components (Cohen et al. 2009. J. Cell Biol. http://dx.doi.org/10.1083/jcb.200901052). Here, we show that another ubiquitin ligase, Trim32, ubiquitylates thin filament (actin, tropomyosin, troponins) and Z-band (α-actinin) components and promotes their degradation. Down-regulation of Trim32 during fasting reduced fiber atrophy and the rapid loss of thin filaments. Desmin filaments were proposed to maintain the integrity of thin filaments. Accordingly, we find that the rapid destruction of thin filament proteins upon fasting was accompanied by increased phosphorylation of desmin filaments, which promoted desmin ubiquitylation by Trim32 and degradation. Reducing Trim32 levels prevented the loss of both desmin and thin filament proteins. Furthermore, overexpression of an inhibitor of desmin polymerization induced disassembly of desmin filaments and destruction of thin filament components. Thus, during fasting, desmin phosphorylation increases and enhances Trim32-mediated degradation of the desmin cytoskeleton, which appears to facilitate the breakdown of Z-bands and thin filaments. PMID:22908310

  15. Cinema e ficção literária em dois escritores hispano-americanos: em torno a Horacio Quiroga e Carlos Noriega Hope

    Directory of Open Access Journals (Sweden)

    Miriam Viviana Garate

    2015-10-01

    Full Text Available O ensaio propõe uma leitura comparada de dois relatos de tema cinematográfico: Miss Dorothy Phillips, mi esposa (1919, do uruguaio Horacio Quiroga e Che Ferrrati, inventor (1923, do mexicano Carlos Noriega Hope. Examinam-se, entre outros aspectos, a presença do registro crítico-ensaístico na ficção, a evidenciação de estereótipos e clichês, o jogo ilusão/ desvelamento instaurado pela trama em relação à “máquina de sonhos”.

  16. Entre a História e a Ficção em Memorial do Convento e Eurico, o Presbítero

    Directory of Open Access Journals (Sweden)

    Aline do Nascimento Duarte

    2004-01-01

    Full Text Available In this paper, we intend to study the thematic of the poetic work of Alexandre Herculano and José Saramago. This analyzes aims to show how the poets rebuild, through different ways, the History by fiction. / Neste trabalho, pretendemos abordar a temática histórica na obra de Alexandre Herculano e José Saramago, explicitando como os escritores reconstroem, através de diferentes estratégias discursivas, a História pela ficção.

  17. Picosecond laser filamentation in air

    Science.gov (United States)

    Schmitt-Sody, Andreas; Kurz, Heiko G.; Bergé, Luc; Skupin, Stefan; Polynkin, Pavel

    2016-09-01

    The propagation of intense picosecond laser pulses in air in the presence of strong nonlinear self-action effects and air ionization is investigated experimentally and numerically. The model used for numerical analysis is based on the nonlinear propagator for the optical field coupled to the rate equations for the production of various ionic species and plasma temperature. Our results show that the phenomenon of plasma-driven intensity clamping, which has been paramount in femtosecond laser filamentation, holds for picosecond pulses. Furthermore, the temporal pulse distortions in the picosecond regime are limited and the pulse fluence is also clamped. In focused propagation geometry, a unique feature of picosecond filamentation is the production of a broad, fully ionized air channel, continuous both longitudinally and transversely, which may be instrumental for many applications including laser-guided electrical breakdown of air, channeling microwave beams and air lasing.

  18. Picosecond laser filamentation in air

    CERN Document Server

    Schmitt-Sody, Andreas; Bergé, L; Skupin, S; Polynkin, Pavel

    2016-01-01

    The propagation of intense picosecond laser pulses in air in the presence of strong nonlinear self-action effects and air ionization is investigated experimentally and numerically. The model used for numerical analysis is based on the nonlinear propagator for the optical field coupled with the rate equations for the production of various ionic species and plasma temperature. Our results show that the phenomenon of plasma-driven intensity clamping, which is paramount in femtosecond laser filamentation, holds for picosecond pulses. Furthermore, the temporal pulse distortions are limited and the pulse fluence is also clamped. The resulting unique feature of the picosecond filamentation regime is the production of a broad, fully ionized air channel, continuous both longitudinally and transversely, which may be instrumental for numerous applications.

  19. Microwave processing of ceramic oxide filaments

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, G.J.; Katz, J.D. [Los Alamos National Laboratory, NM (United States)

    1995-05-01

    The objective of the microwave filament processing project is to develop microwave techniques at 2.45 GHZ to manufacture continuous ceramic oxide filaments. Microwave processing uses the volumetric absorption of microwave power in oxide filament tows to drive off process solvents, to burn out organic binders, and to sinter the dried fibers to produce flexible, high-strength ceramic filaments. The technical goal is to advance filament processing technology by microwave heating more rapidly with less energy and at a lower cost than conventional processing, but with the same quality as conventional processing. The manufacturing goal is to collaborate with the 3M Company, a US manufacturer of ceramic oxide filaments, to evaluate the technology using a prototype filament system and to transfer the microwave technology to the 3M Company.

  20. Dynamics of 3D isolated thermal filaments

    CERN Document Server

    Walkden, N R; Militello, F; Omotani, J T

    2016-01-01

    Simulations have been carried out to establish how electron thermal physics, introduced in the form of a dynamic electron temperature, affects isolated filament motion and dynamics in 3D. It is found that thermal effects impact filament motion in two major ways when the filament has a significant temperature perturbation compared to its density perturbation: They lead to a strong increase in filament propagation in the bi-normal direction and a significant decrease in net radial propagation. Both effects arise from the temperature dependence of the sheath current which leads to a non-uniform floating potential, with the latter effect supplemented by faster pressure loss. The reduction in radial velocity can only occur when the filament cross-section loses angular symmetry. The behaviour is observed across different filament sizes and suggests that filaments with much larger temperature perturbations than density perturbations are more strongly confined to the near SOL region.

  1. Dynamics of 3D isolated thermal filaments

    Science.gov (United States)

    Walkden, N. R.; Easy, L.; Militello, F.; Omotani, J. T.

    2016-11-01

    Simulations have been carried out to establish how electron thermal physics, introduced in the form of a dynamic electron temperature, affects isolated filament motion and dynamics in 3D. It is found that thermal effects impact filament motion in two major ways when the pressure perturbation within the filament is supported primarily through a temperature increase as opposed to density: they lead to a strong increase in filament propagation in the bi-normal direction and a significant decrease in net radial propagation. Both effects arise from the temperature dependence of the sheath current which leads to a non-uniform floating potential, with the latter effect supplemented by faster pressure loss. The reduction in radial velocity can only occur when the filament cross-section loses angular symmetry. The behaviour is observed across different filament sizes and suggests that filaments with much larger temperature perturbations than density perturbations are more strongly confined to the near SOL region.

  2. Spectroscopic analysis of high electric field enhanced ionization in laser filaments in air for corona guiding

    Institute of Scientific and Technical Information of China (English)

    Yingxia Wei; Yaoxiang Liu; Tie-Jun Wang; Na Chen; Jingjing Ju; Yonghong Liu; Haiyi Sun; Cheng Wang; Jiansheng Liu; Haihe Lu; See Leang Chin; Ruxin Li

    2016-01-01

    We report on a systematic experimental study on the fluorescence spectra produced from a femtosecond laser filament in air under a high electric field. The electric field alone was strong enough to create corona discharge(CD). Fluorescence spectra from neutral and ionic air molecules were measured and compared with pure high-voltage CD and pure laser filamentation(FIL). Among them, high electric field assisted laser FIL produced nitrogen fluorescence more efficiently than either pure CD or pure FIL processes. The nonlinear enhancement of fluorescence from the interaction of the laser filament and corona discharging electric field resulted in a more efficient ionization along the laser filament zone, which was confirmed by the spectroscopic measurement of both ionization-induced fluorescence and plasma-scattered 800 nm laser pulses. This is believed to be the key precursor process for filament-guided discharge.

  3. Characteristics of filamentation in ZK7 glass by negatively chirped femtosecond laser pulses

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The filamentation characteristics of femtosecond laser pulses in ZK7 glass are in- vestigated experimentally as a function of initial negative chirps. It is found that the filament threshold power grows rapidly and the filament length extends over a long distance with increasing initial temporal chirps. The measurement of supercon- tinuum reveals that the plasma generation process within filamentation becomes weaker as the initial negative chirp increases, leading to a self-guiding long light channel dominated by Kerr nonlinearity. The interference of transverse rings in multifilamentation of the chirped laser pulses is observed as well. Analyses and discussions give an interpretation of this chirp-induced ionization-free filamenta- tion. These results indicate that initial chirps will play a crucial role in the filament formation of ultrashort laser pulses in transparent media.

  4. Carl Sagan: a exploração e colonização de planetas - ficção científica,cência e divulgação

    OpenAIRE

    Souza, Carlos A. Loiola de

    2006-01-01

    Obras de ficção científica podem, dependendo de como estiverem estruturadas por seus autores, em nosso caso, o astrônomo Carl Sagan, ser usadas como textos de referência em História da Ciência por sua interdisciplinaridade. O caso específico das viagens interplanetárias, pensadas e teorizadas cientificamente e divulgadas sob a linguagem da ficção científica nos livros de Carl Sagan, é o de que se ocupa esta dissertação. Os autores de textos de ficção, como os colegas de Sagan A...

  5. Narrar e descrever: modos de organização do discurso no filme narrativo de ficção

    Directory of Open Access Journals (Sweden)

    Carolina Assunção e Alves

    2014-05-01

    Full Text Available No domínio da Análise do Discurso, mais especificamente na Teoria Semiolinguística, Patrick Charaudeau (1992 apresenta a categoria dos modos de organização do discurso – enunciativo, argumentativo, narrativo e descritivo – como aparelhos utilizados para construir e ordenar os conteúdos dos contratos de comunicação com suas respectivas estratégias. Consideramos o filme narrativo de ficção como gênero discursivo a ser estudado enquanto fenômeno sociallinguageiro, objeto de troca entre instâncias de produção e recepção, com base em um acordo comunicacional preestabelecido. Este artigotem como meta refletir sobre possíveis configurações dos modos narrativo e descritivo de organização do discurso em plataforma audiovisual, durante o processo de construção do filme narrativo de ficção. Para isso, contamos com o auxílio de estudos teóricos acerca da linguagem cinematográfica desenvolvidos por autores como Martin(1990 e Beylot (2005, entre outros.

  6. Liquid Crystal Alignment Control Using Polymer Filament and Polymer Layers Coated on Substrates

    Science.gov (United States)

    Murashige, Takeshi; Fujikake, Hideo; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio

    2005-04-01

    We investigated liquid crystal (LC) alignment in LC cells containing an aligned cellulose filament sandwiched by thin polymer layers coated on substrates. Three types of polymer material, namely polystyrene (PS), polyvinyl alcohol (PVA) and polyimide (PI), were used as polymer layers. LC alignment areas induced on both sides of the filament were large in the order of PS, PVA and PI. In the case of the PS layer, the average LC alignment area reached approximately 100 μm in the direction perpendicular to the polymer filament. The molecular interaction between the LC and the PS layer is thought to be weak and it does not disturb the LC alignment due to the polymer filament. On the other hand, rubbed PS layers were used as polymer layers of the LC cell, where the LC alignment direction induced by the rubbed PS layer was perpendicular to the polymer filament. It was found that the LC alignment near the polymer filament gradually bent in the cell plane. The result suggests that various three-dimensional LC alignments can be realized by the combination of the polymer filament and substrate surface.

  7. Mechanical properties of branched actin filaments

    CERN Document Server

    Razbin, Mohammadhosein; Benetatos, Panayotis; Zippelius, Annette

    2015-01-01

    Cells moving on a two dimensional substrate generate motion by polymerizing actin filament networks inside a flat membrane protrusion. New filaments are generated by branching off existing ones, giving rise to branched network structures. We investigate the force-extension relation of branched filaments, grafted on an elastic structure at one end and pushing with the free ends against the leading edge cell membrane. Single filaments are modeled as worm-like chains, whose thermal bending fluctuations are restricted by the leading edge cell membrane, resulting in an effective force. Branching can increase the stiffness considerably; however the effect depends on branch point position and filament orientation, being most pronounced for intermediate tilt angles and intermediate branch point positions. We describe filament networks without cross-linkers to focus on the effect of branching. We use randomly positioned branch points, as generated in the process of treadmilling, and orientation distributions as measur...

  8. Muscle myosin filaments: cores, crowns and couplings.

    Science.gov (United States)

    Squire, John M

    2009-09-01

    Myosin filaments in muscle, carrying the ATPase myosin heads that interact with actin filaments to produce force and movement, come in multiple varieties depending on species and functional need, but most are based on a common structural theme. The now successful journeys to solve the ultrastructures of many of these myosin filaments, at least at modest resolution, have not been without their false starts and erroneous sidetracks, but the picture now emerging is of both diversity in the rotational symmetries of different filaments and a degree of commonality in the way the myosin heads are organised in resting muscle. Some of the remaining differences may be associated with how the muscle is regulated. Several proteins in cardiac muscle myosin filaments can carry mutations associated with heart disease, so the elucidation of myosin filament structure to understand the effects of these mutations has a clear and topical clinical relevance.

  9. Filamentous Biological Entities Obtained from the Stratosphere

    Science.gov (United States)

    Wainwright, Milton; Rose, Christopher E.; Baker, Alexander J.; Wickramasinghe, N. Chandra

    2013-03-01

    We previously reported the presence of large, non-filamentous, biological entities including a diatom fragment in the stratosphere at heights of between 22-27km. Here we report clear evidence for the presence of filamentous entities associated with a relatively large particle mass collected from the stratosphere. Although viable fungi have previously been isolated from the stratosphere, this is the first report of a filamentous microorganism being observed in situ on a stratospheric particle mass.

  10. Solubilization and fractionation of paired helical filaments.

    Science.gov (United States)

    González, P J; Correas, I; Avila, J

    1992-09-01

    Paired helical filaments isolated from brains of two different patients with Alzheimer's disease were extensively treated with the ionic detergent, sodium dodecyl sulphate. Filaments were solubilized at different extents, depending on the brain examined, thus suggesting the existence of two types of paired helical filaments: sodium dodecyl sulphate-soluble and insoluble filaments. In the first case, the number of structures resembling paired helical filaments greatly decreased after the detergent treatment, as observed by electron microscopy. Simultaneously, a decrease in the amount of sedimentable protein was also observed upon centrifugation of the sodium dodecyl sulfate-treated paired helical filaments. A sodium dodecyl sulphate-soluble fraction was isolated as a supernatant after low-speed centrifugation of the sodium dodecyl sulphate-treated paired helical filaments. The addition of the non-ionic detergent Nonidet-P40 to this fraction resulted in the formation of paired helical filament-like structures. When the sodium dodecyl sulphate-soluble fraction was further fractionated by high-speed centrifugation, three subfractions were observed: a supernatant, a pellet and a thin layer between these two subfractions. No paired helical filaments were observed in any of these subfractions, even after addition of Nonidet P-40. However, when they were mixed back together, the treatment with Nonidet P-40 resulted in the visualization of paired helical filament-like structures. These results suggest that at least two different components are needed for the reconstitution of paired helical filaments as determined by electron microscopy. The method described here may allow the study of the components involved in the formation of paired helical filaments and the identification of possible factors capable of blocking this process.

  11. Equilibrium shapes of twisted magnetic filaments

    Energy Technology Data Exchange (ETDEWEB)

    Belovs, Mihails; Cirulis, Teodors; Cebers, Andrejs [University of Latvia, Zellu 8, LV-1002 (Latvia)], E-mail: aceb@tesla.sal.lv

    2009-06-12

    It is shown that ferromagnetic filaments with free and unclamped ends undergo buckling instabilities under the action of twist. Solutions of nonlinear equations describing the buckled shapes are found, and it is shown that the transition to the buckled shape is subcritical if the magnetization is parallel to the field and supercritical when the magnetization of the straight filament is opposite to the external field. Solutions with the localized curvature distribution are found in the case of long filaments. The class of solutions corresponding to helices is described, and the behavior of coiled ferromagnetic and superparamagnetic filaments is compared.

  12. Hydrodynamic interactions between nearby slender filaments

    CERN Document Server

    Man, Yi; Lauga, Eric

    2016-01-01

    Cellular biology abound with filaments interacting through fluids, from intracellular microtubules, to rotating flagella and beating cilia. While previous work has demonstrated the complexity of capturing nonlocal hydrodynamic interactions between moving filaments, the problem remains difficult theoretically. We show here that when filaments are closer to each other than their relevant length scale, the integration of hydrodynamic interactions can be approximately carried out analytically. This leads to a set of simplified local equations, illustrated on a simple model of two interacting filaments, which can be used to tackle theoretically a range of problems in biology and physics.

  13. Probing the Physical Structures of Dense Filaments

    Science.gov (United States)

    Li, Di

    2015-08-01

    Filament is a common feature in cosmological structures of various scales, ranging from dark matter cosmic web, galaxy clusters, inter-galactic gas flows, to Galactic ISM clouds. Even within cold dense molecular cores, filaments have been detected. Theories and simulations with (or without) different combination of physical principles, including gravity, thermal balance, turbulence, and magnetic field, can reproduce intriguing images of filaments. The ubiquity of filaments and the similarity in simulated ones make physical parameters, beyond dust column density, a necessity for understanding filament evolution. I report three projects attempting to measure physical parameters of filaments. We derive the volume density of a dense Taurus filament based on several cyanoacetylene transitions observed by GBT and ART. We measure the gas temperature of the OMC 2-3 filament based on combined GBT+VLA ammonia images. We also measured the sub-millimeter polarization vectors along OMC3. These filaments were found to be likely a cylinder-type structure, without dynamic heating, and likely accreting mass along the magnetic field lines.

  14. Deep coronal hole associated with quiescent filament

    Science.gov (United States)

    Kesumaningrum, Rasdewita; Herdiwidjaya, Dhani

    2014-03-01

    We present a study of the morphology of quiescent filament observed by H-alpha Solar Telescope at Bosscha Observatory in association with coronal hole observed by Atmospheric Imaging Assembly (AIA) instrument in 193 Å from Solar Dynamics Observatory. H-alpha images were processed by imaging softwares, namely Iris 5.59 and ImageJ, to enhance the signal to noise ratio and to identify the filament features associated with coronal hole. For images observed on October 12, 2011, November 14, 2011 and January 2, 2012, we identified distinct features of coronal holes above the quiescent filaments. This associated coronal holes have filament-like morphology with a thick long thread as it's `spine', defined as Deep Coronal Hole. Because of strong magnetic field of sunspot, these filaments and coronal holes emerged far from active region and lasted for several days. It is interesting as for segmented filament, deep coronal holes above the filaments lasted for a quite long period of time and merged. This association between filament and deep coronal hole can be explained by filament magnetic loop.

  15. Filamentation with nonlinear Bessel vortices.

    Science.gov (United States)

    Jukna, V; Milián, C; Xie, C; Itina, T; Dudley, J; Courvoisier, F; Couairon, A

    2014-10-20

    We present a new type of ring-shaped filaments featured by stationary nonlinear high-order Bessel solutions to the laser beam propagation equation. Two different regimes are identified by direct numerical simulations of the nonlinear propagation of axicon focused Gaussian beams carrying helicity in a Kerr medium with multiphoton absorption: the stable nonlinear propagation regime corresponds to a slow beam reshaping into one of the stationary nonlinear high-order Bessel solutions, called nonlinear Bessel vortices. The region of existence of nonlinear Bessel vortices is found semi-analytically. The influence of the Kerr nonlinearity and nonlinear losses on the beam shape is presented. Direct numerical simulations highlight the role of attractors played by nonlinear Bessel vortices in the stable propagation regime. Large input powers or small cone angles lead to the unstable propagation regime where nonlinear Bessel vortices break up into an helical multiple filament pattern or a more irregular structure. Nonlinear Bessel vortices are shown to be sufficiently intense to generate a ring-shaped filamentary ionized channel in the medium which is foreseen as opening the way to novel applications in laser material processing of transparent dielectrics.

  16. Engineered Laser Filaments in Air for Defense Stand-Off Sensing and Interaction Applications

    Science.gov (United States)

    2013-12-19

    Mark Ramme, Magali Durand , Matthieu Baudelet, Martin Richardson. Stand-off filament-induced ablation of gallium arsenide, Applied Physics Letters...07 2012): 0. doi: 10.1063/1.4734497 Magali Durand , Khan Lim, Vytautas Jukna, Erik McKee, Matthieu Baudelet, Aurélien Houard, Martin Richardson...Bernath and M. Richardson, “RF emissions from filament-matter interaction”, COFIL 2012, Tucson, AZ, USA, 2012. [4] M. Durand , A. Jarnac, S

  17. Evidence that the deep keratin filament systems of the Xenopus embryo act to ensure normal gastrulation.

    OpenAIRE

    Klymkowsky, M. W.; Shook, D R; Maynell, L A

    1992-01-01

    To study the role of keratin filaments in Xenopus development, fertilized eggs were injected with anti-keratin monoclonal antibodies. The anti-keratin monoclonal antibodies AE1 and AE3 induce abnormal gastrulation; in the most severely affected embryos gastrulation fails completely. In contrast, embryos injected with the anti-keratin antibody 1h5 develop normally. Immunocytochemical data indicate that injected 1h5 binds to the dense superficial keratin filament system of the embryo but not to...

  18. Filament poisoning at typical carbon nanotube deposition conditions by hot-filament CVD

    CSIR Research Space (South Africa)

    Oliphant, CJ

    2009-05-01

    Full Text Available This paper reports on the poisoning of tungsten filaments during the hot-filament chemical vapour deposition process at typical carbon nanotube (CNT) deposition conditions and filament temperatures ranging from 1400 to 2000 °C. The morphological...

  19. [Synergy between ajoene and ketoconazole in isolates of Microsporum canis. A preliminary study using fractional inhibitory concentration technique (FIC)].

    Science.gov (United States)

    Ledezma, Eliades; Maniscalchi, Maria Teresa; Espinoza, Druvic Lemus

    2008-09-30

    Fungal infections are probably the most frequent infectious diseases affecting human being. Resistance to different anti-fungal drugs, and their bioavailability in the infection site, represent a problem for treatment. Looking for effective solutions, combination of two or more antifungal drugs to obtain an additive effect or synergic effect that potent antifungal activity has been investigated. In this study, the effect (additive, antagonist or synergistic) of ajoene and ketoconazole combination was evaluated in the growth and proliferation of filamentous fungi. Interactions in vitro were investigated in three isolates of Microsporum canis through a preliminary study using micro dilution, according to recommendations of NCCLS M-38A, with several modifications. Results obtained for CIF of each isolates studied (CIF = 0.18 0.36 microM), demonstrate that exists a very potent synergistic effect, when they are combined, and it represents a hope for future clinic trials to treat resilient fungal infections caused by M. canis.

  20. A Statistical Study of Solar Filament Eruptions

    Science.gov (United States)

    Schanche, Nicole; Aggarwal, Ashna; Reeves, Kathy; Kempton, Dustin James; Angryk, Rafal

    2016-05-01

    Solar filaments are cool, dark channels of partially-ionized plasma that lie above the chromosphere. Their structure follows the neutral line between local regions of opposite magnetic polarity. Previous research (e.g. Schmieder et al. 2013, McCauley et al. 2015) has shown a positive correlation (70-80%) between the occurrence of filament eruptions and coronal mass ejections (CME’s). In this study, we attempt to use properties of the filament in order to predict whether or not a given filament will erupt. This prediction would help to better predict the occurrence of an oncoming CME. To track the evolution of a filament over time, a spatio-temporal algorithm that groups separate filament instances from the Heliophysics Event Knowledgebase (HEK) into filament tracks was developed. Filament features from the HEK metadata, such as length, chirality, and tilt are then combined with other physical features, such as the overlying decay index for two sets of filaments tracks - those that erupt and those that remain bound. Using statistical methods such as the Kolmogrov-Smirnov test and a Random Forest Classifier, we determine the effectiveness of the combined features in prediction. We conclude that there is significant overlap between the properties of filaments that erupt and those that do not, leading to predictions only ~5-10% above chance. However, the changes in features, such as a change in the filament's length over time, were determined to have the highest predictive power. We discuss the possible physical connections with the change in these features."This project has been supported by funding from the Division of Advanced Cyberinfrastructure within the Directorate for Computer and Information Science and Engineering, the Division of Astronomical Sciences within the Directorate for Mathematical and Physical Sciences, and the Division of Atmospheric and Geospace Sciences within the Directorate for Geosciences, under NSF award #1443061.”

  1. Induction of ERK-kinase signalling triggers morphotype-specific killing of Candida albicans filaments by human neutrophils.

    Science.gov (United States)

    Wozniok, Iwona; Hornbach, Anke; Schmitt, Corinna; Frosch, Matthias; Einsele, Hermann; Hube, Bernhard; Löffler, Jürgen; Kurzai, Oliver

    2008-03-01

    Candida albicans is among the most important fungal pathogens in humans. Morphological plasticity has been linked to its pathogenic potential as filamentous forms are associated with tissue invasion and infection. Here we show that human neutrophils discriminate between yeasts and filaments of C. albicans. Whereas filaments induced targeted motility, resulting in the establishment of close contact between neutrophils and fungal cells, yeast forms were largely ignored during coincubation. In transwell assays, C. albicans filaments induced significantly higher migratory activity in neutrophils than yeasts. Neutrophil motility based on actin rearrangement was essential for killing of C. albicans filaments but not involved in killing of yeast forms. Using inhibitors for MAP-kinase cascades, it was shown that recognition of C. albicans filaments by neutrophils is mediated via the MEK/ERK cascade and independent of JNK or p38 activation. Inhibition of the ERK signalling pathway abolished neutrophil migration induced by C. albicans filaments and selectively impaired the ability to kill this morphotype. These data show that invasive filamentous forms of C. albicans trigger a morphotype-specific activation of neutrophils, which is strongly dependent on neutrophil motility. Therefore, human neutrophils are capable of sensing C. albicans invasion and initiating an appropriate early immune response.

  2. Spectral stability of Alfven filament chains

    NARCIS (Netherlands)

    Bergmans, J.; Kuvshinov, B. N.; Lakhin, V. P.; Schep, T. J.

    2000-01-01

    The two-fluid model of nonlinear Alfven perturbations has singular solutions in the form of current-vortex filaments. We investigate analytically and numerically the spectral stability of single and double rows of filaments. Staggered and non-staggered double rows (von Karman streets) are studied. I

  3. Spectral stability of Alfven filament configurations

    NARCIS (Netherlands)

    Bergmans, J.; Kuvshinov, B. N.; Lakhin, V. P.; Schep, T. J.

    2000-01-01

    The two-fluid plasma equations that describe nonlinear Alfven perturbations have singular solutions in the form of current-vortex filaments. These filaments are analogous to point vortices in ideal hydrodynamics and geostrophic fluids. In this work the spectral (linear) stability of current-vortex f

  4. Radial interchange motions of plasma filaments

    DEFF Research Database (Denmark)

    Garcia, O.E.; Bian, N.H.; Fundamenski, W.

    2006-01-01

    reduces the radial velocity of isolated filaments. The results are discussed in the context of convective transport in scrape-off layer plasmas, comprising both blob-like structures in low confinement modes and edge localized mode filaments in unstable high confinement regimes. (c) 2006 American Institute...

  5. Reconstitution of the muscle thin filament from recombinant troponin components and the native thin filaments.

    Science.gov (United States)

    Matsumoto, Fumiko; Deshimaru, Shungo; Oda, Toshiro; Fujiwara, Satoru

    2010-04-15

    We have developed a technique by which muscle thin filaments are reconstituted from the recombinant troponin components and the native thin filaments. By this technique, the reconstituted troponin complex is exchanged into the native thin filaments in the presence of 20% glycerol and 0.3M KCl at pH 6.2. More than 90% of endogenous troponin complex was replaced with the recombinant troponin complex. Structural integrity and Ca(2+) sensitivity of the reconstituted thin filament prepared by this technique was confirmed by X-ray fiber diffraction measurements and the thin filament-activated myosin subfragment 1 ATPase measurements, respectively.

  6. Standoff Detection of Uranium and its Isotopes by Femtosecond Filament Laser Ablation Molecular Isotopic Spectrometry

    Science.gov (United States)

    Hartig, Kyle C.; Ghebregziabher, Isaac; Jovanovic, Igor

    2017-03-01

    The ability to perform not only elementally but also isotopically sensitive detection and analysis at standoff distances is impor-tant for remote sensing applications in diverse ares, such as nuclear nonproliferation, environmental monitoring, geophysics, and planetary science. We demonstrate isotopically sensitive real-time standoff detection of uranium by the use of femtosecond filament-induced laser ablation molecular isotopic spectrometry. A uranium oxide molecular emission isotope shift of 0.05 ± 0.007 nm is reported at 593.6 nm. We implement both spectroscopic and acoustic diagnostics to characterize the properties of uranium plasma generated at different filament-uranium interaction points. The resulting uranium oxide emis-sion exhibits a nearly constant signal-to-background ratio over the length of the filament, unlike the uranium atomic and ionic emission, for which the signal-to-background ratio varies significantly along the filament propagation. This is explained by the different rates of increase of plasma density and uranium oxide density along the filament length resulting from spectral and temporal evolution of the filament along its propagation. The results provide a basis for the optimal use of filaments for standoff detection and analysis of uranium isotopes and indicate the potential of the technique for a wider range of remote sensing applications that require isotopic sensitivity.

  7. Standoff Detection of Uranium and its Isotopes by Femtosecond Filament Laser Ablation Molecular Isotopic Spectrometry.

    Science.gov (United States)

    Hartig, Kyle C; Ghebregziabher, Isaac; Jovanovic, Igor

    2017-03-08

    The ability to perform not only elementally but also isotopically sensitive detection and analysis at standoff distances is impor-tant for remote sensing applications in diverse ares, such as nuclear nonproliferation, environmental monitoring, geophysics, and planetary science. We demonstrate isotopically sensitive real-time standoff detection of uranium by the use of femtosecond filament-induced laser ablation molecular isotopic spectrometry. A uranium oxide molecular emission isotope shift of 0.05 ± 0.007 nm is reported at 593.6 nm. We implement both spectroscopic and acoustic diagnostics to characterize the properties of uranium plasma generated at different filament-uranium interaction points. The resulting uranium oxide emis-sion exhibits a nearly constant signal-to-background ratio over the length of the filament, unlike the uranium atomic and ionic emission, for which the signal-to-background ratio varies significantly along the filament propagation. This is explained by the different rates of increase of plasma density and uranium oxide density along the filament length resulting from spectral and temporal evolution of the filament along its propagation. The results provide a basis for the optimal use of filaments for standoff detection and analysis of uranium isotopes and indicate the potential of the technique for a wider range of remote sensing applications that require isotopic sensitivity.

  8. Solar Filaments as Tracers of Subsurface Processes

    Indian Academy of Sciences (India)

    D. M. Rust

    2000-09-01

    Solar filaments are discussed in terms of two contrasting paradigms. The standard paradigm is that filaments are formed by condensation of coronal plasma into magnetic fields that are twisted or dimpled as a consequence of motions of the fields' sources in the photo-sphere. According to a new paradigm, filaments form in rising, twisted flux ropes and are a necessary intermediate stage in the transfer to interplanetary space of dynamo-generated magnetic flux. It is argued that the accumulation of magnetic helicity in filaments and their coronal surroundings leads to filament eruptions and coronal mass ejections. These ejections relieve the Sun of the flux generated by the dynamo and make way for the flux of the next cycle.

  9. Quantifying protein diffusion and capture on filaments

    CERN Document Server

    Reithmann, Emanuel; Frey, Erwin

    2015-01-01

    The functional relevance of regulating proteins is often limited to specific binding sites such as the ends of microtubules or actin-filaments. A localization of proteins on these functional sites is of great importance. We present a quantitative theory for a diffusion and capture process, where proteins diffuse on a filament and stop diffusing when reaching the filament's end. It is found that end-association after one-dimensional diffusion is the main source for tip-localization of such proteins. As a consequence, diffusion and capture is highly efficient in enhancing the reaction velocity of enzymatic reactions, where proteins and filament ends are to each other as enzyme and substrate. We show that the reaction velocity can effectively be described within a Michaelis-Menten framework. Together one-dimensional diffusion and capture beats the (three-dimensional) Smoluchowski diffusion limit for the rate of protein association to filament ends.

  10. Theory of Semiflexible Filaments and Networks

    Directory of Open Access Journals (Sweden)

    Fanlong Meng

    2017-02-01

    Full Text Available We briefly review the recent developments in the theory of individual semiflexible filaments, and of a crosslinked network of such filaments, both permanent and transient. Starting from the free energy of an individual semiflexible chain, models on its force-extension relation and other mechanical properties such as Euler buckling are discussed. For a permanently crosslinked network of filaments, theories on how the network responds to deformation are provided, with a focus on continuum approaches. Characteristic features of filament networks, such as nonlinear stress-strain relation, negative normal stress, tensegrity, and marginal stability are discussed. In the new area of transient filament network, where the crosslinks can be dynamically broken and re-formed, we show some recent attempts for understanding the dynamics of the crosslinks, and the related rheological properties, such as stress relaxation, yield stress and plasticity.

  11. Parábola do Cágado Velho: entre ficção e história, (dis) utopias

    OpenAIRE

    Góes, Eliane Rosa de

    2011-01-01

    Estudo da estrutura novelesca da Parábola do Cágado Velho (2005), do escritor angolano Pepetela ou Artur Carlos Maurício Pestana dos Santos, que reencena, em sua ficção, a história de Angola no contexto universal. Dentre as disparidades étnicas e lingüísticas, sócio-econômicas, políticas e religiosas levantadas, a negação de projeções esperançosas utópicas deu lugar às inversões das distopias. Na base do reverso do gênero utópico, a distopia atua como um não lugar e modo de pen...

  12. Entre história e ficção: Heródoto um mensageiro trágico

    OpenAIRE

    2010-01-01

    Sem querer negar a Heródoto o estatuto de pioneiro em um gênero novo a História buscamos aproximá-lo, tanto no que é relativo ao estilo, quanto ao que é relativo ao conteúdo, ao mensageiro trágico. Nosso historiador ainda possui uma relação estreita com a produção teatral de seu tempo, partilhando de profundas afinidades com as filosofias de vida veiculadas pelos trágicos do século V. A partir das Histórias, então, e de suas marcas de historicidade e de ficção, esta dissertação visa demonstra...

  13. Estratégias de importação literária: o Brasil traduz ficção Argentina dos anos 70

    OpenAIRE

    Yerro, Jorge Hernán

    2007-01-01

    Esta dissertação tem por objetivo determinar as estratégias que definiram a importação de obras de ficção em prosa, produzidas na década de 1970 por autores argentinos, a serem traduzidas no Brasil, no mesmo período. O trabalho, que propõe uma abordagem historiográfica e se sustenta nos Estudos Descritivos da Tradução, reúne informações sobre a primeira etapa do processo tradutório, o da seleção das obras a serem traduzidas. Ao longo do seu desenvolvimento, o estudo trata das relações existen...

  14. As séries televisivas no contexto da ficção nacional: uma aproximação

    Directory of Open Access Journals (Sweden)

    Sílvia Góis Dantas

    2016-02-01

    Full Text Available Esse texto procura apresentar uma aproximação com o universo de estudo das narrativas teleficcionais, a partir de uma ampla revisão teórica que compreende obras de Balogh, Bruner, Eco, Machado, Mungioli. Para isso, nosso percurso inicia com os estudos sobre narrativa e ficção, transitamos pelo conceito e classificação de serialidade, no qual buscamos distinguir série e seriado. Em seguida, avançamos para as pesquisas sobre a cultura das séries na contemporaneidade e trazemos informações sobre as séries brasileiras inéditas exibidas em 2013 na TV aberta e na TV paga, e focamos na série 3 Teresas, objeto de nossa pesquisa em fase inicial.

  15. Natural colorants from filamentous fungi.

    Science.gov (United States)

    Torres, Fábio Aurélio Esteves; Zaccarim, Bruna Regina; de Lencastre Novaes, Letícia Celia; Jozala, Angela Faustino; Dos Santos, Carolina Alves; Teixeira, Maria Francisca Simas; Santos-Ebinuma, Valéria Carvalho

    2016-03-01

    In the last years, there is a trend towards the replacement of synthetic colorants by natural ones, mainly due to the increase of consumer demand for natural products. The natural colorants are used to enhance the appearance of pharmaceutical products, food, and different materials, making them preferable or attractive. This review intends to provide and describe a comprehensive overview of the history of colorants, from prehistory to modern time, of their market and their applications, as well as of the most important aspects of the fermentation process to obtain natural colorants. Focus is given to colorants produced by filamentous fungal species, aiming to demonstrate the importance of these microorganisms and biocompounds, highlighting the production performance to get high yields and the aspects of conclusion that should be taken into consideration in future studies about natural colorants.

  16. Particles trajectories in magnetic filaments

    CERN Document Server

    Bret, Antoine

    2015-01-01

    The motion of a particle in a spatially harmonic magnetic field is a basic problem involved, for example, in the mechanism of formation of a collisionless shock. In such settings, it is generally reasoned that particles entering a Weibel generated turbulence are trapped inside it, provided their Larmor radius in the peak field is smaller than the field coherence length. The goal of this work is to put this heuristic conclusion on firm ground by studying, both analytically and numerically, such motion. A toy model is analyzed, consisting of a relativistic particle entering a region of space occupied by a spatially harmonic field. The particle penetrates the magnetic structure in a direction aligned with the magnetic filaments. Although the conclusions are not trivial, the main result is confirmed.

  17. Filamentous Growth in Eremothecium Fungi

    DEFF Research Database (Denmark)

    Oskarsson, Therese

    , this thesis deals with some of the aspects of hyphal growth, which is an important virulence factor for pathogenic fungi infecting both humans and plants. Hyphal establishment through continuous polar growth is a complex process, requiring the careful coordination of a large subset of proteins involved......-regulatory activity of AgGts1, the protein could have additional actin organizing properties. In the second and third part, this thesis addresses the use of A. gossypii and its relative E. cymbalariae as model organisms for filamentous growth. A series of assays analyzed the capability of Eremothecium genus fungi...... of molecular tools for E. cymbalariae to enable a faster and more efficient approach for genetic comparisons between Eremothecium genus fungi....

  18. Filamentous Growth in Eremothecium Fungi

    DEFF Research Database (Denmark)

    Oskarsson, Therese

    , this thesis deals with some of the aspects of hyphal growth, which is an important virulence factor for pathogenic fungi infecting both humans and plants. Hyphal establishment through continuous polar growth is a complex process, requiring the careful coordination of a large subset of proteins involved......-regulatory activity of AgGts1, the protein could have additional actin organizing properties. In the second and third part, this thesis addresses the use of A. gossypii and its relative E. cymbalariae as model organisms for filamentous growth. A series of assays analyzed the capability of Eremothecium genus fungi...... of molecular tools for E. cymbalariae to enable a faster and more efficient approach for genetic comparisons between Eremothecium genus fungi....

  19. Particles trajectories in magnetic filaments

    Energy Technology Data Exchange (ETDEWEB)

    Bret, A. [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Instituto de Investigaciones Energéticas y Aplicaciones Industriales, Campus Universitario de Ciudad Real, 13071 Ciudad Real (Spain)

    2015-07-15

    The motion of a particle in a spatially harmonic magnetic field is a basic problem involved, for example, in the mechanism of formation of a collisionless shock. In such settings, it is generally reasoned that particles entering a Weibel generated turbulence are trapped inside it, provided their Larmor radius in the peak field is smaller than the field coherence length. The goal of this work is to put this heuristic conclusion on firm ground by studying, both analytically and numerically, such motion. A toy model is analyzed, consisting of a relativistic particle entering a region of space occupied by a spatially harmonic field. The particle penetrates the magnetic structure in a direction aligned with the magnetic filaments. Although the conclusions are not trivial, the main result is confirmed.

  20. Ensenyament-aprenentatge de les ciènces en Educació Infantil: la construcció de models científics precursors

    Directory of Open Access Journals (Sweden)

    Sabrina Patricia Canedo Ibarra

    2010-03-01

    Full Text Available En aquest article es presenten els resultats sobre la construcció del model científic precursor (MCP de flotació basat en la naturalesa del material dels objectes per part de nens d'educació infantil, a partir de l'ús d'habilitats científiques procedimentals i comunicatives, en un context dialògic d’instrucció. L'estudi exploratori va seguir un enfocament qualitatiu en la presa i anàlisi de les dades i es va dur a terme en tres fases: pre-test, procés d'instrucció, i post-test. Els resultats mostren que, després del període d'instrucció, alguns dels nens van ser capaços de construir el model precursor de flotació, i que, en general, tots van mostrar millorar qualitativament el seu raonament en descriure el fenomen en termes de l'esdeveniment mateix i en canviar la seva forma d'explicar-ho en termes més científics. En base a aquests resultats assumim que les activitats van ser efectives i que, en el context de l'educació infantil, l'enfocament que es proposa pot contribuir a una millor comprensió dels processos d'ensenyament-aprenentatge de les ciències en l'educació infantil amb l'objectiu de promoure una alfabetització científica des d'edats primerenques.

  1. Adiabatic Floquet model for the optical response in femtosecond filaments

    CERN Document Server

    Hofmann, Michael

    2016-01-01

    The standard model of femtosecond filamentation is based on phenomenological assumptions which suggest that the ionization-induced carriers can be treated as free according to the Drude model, while the nonlinear response of the bound carriers follows the all-optical Kerr effect. Here, we demonstrate that the additional plasma generated at a multiphoton resonance dominates the saturation of the nonlinear refractive index. Since resonances are not captured by the standard model, we propose a modification of the latter in which ionization enhancements can be accounted for by an ionization rate obtained from non-Hermitian Floquet theory. In the adiabatic regime of long pulse envelopes, this augmented standard model is in excellent agreement with direct quantum mechanical simulations. Since our proposal maintains the structure of the standard model, it can be easily incorporated into existing codes of filament simulation.

  2. Automatic Detect and Trace of Solar Filaments

    Science.gov (United States)

    Fang, Cheng; Chen, P. F.; Tang, Yu-hua; Hao, Qi; Guo, Yang

    We developed a series of methods to automatically detect and trace solar filaments in solar Hα images. The programs are able to not only recognize filaments and determine their properties, such as the position, the area and other relevant parameters, but also to trace the daily evolution of the filaments. For solar full disk Hα images, the method consists of three parts: first, preprocessing is applied to correct the original images; second, the Canny edge-detection method is used to detect the filaments; third, filament properties are recognized through the morphological operators. For each Hα filament and its barb features, we introduced the unweighted undirected graph concept and adopted Dijkstra shortest-path algorithm to recognize the filament spine; then, using polarity inversion line shift method for measuring the polarities in both sides of the filament to determine the filament axis chirality; finally, employing connected components labeling method to identify the barbs and calculating the angle between each barb and spine to indicate the barb chirality. Our algorithms are applied to the observations from varied observatories, including the Optical & Near Infrared Solar Eruption Tracer (ONSET) in Nanjing University, Mauna Loa Solar Observatory (MLSO) and Big Bear Solar Observatory (BBSO). The programs are demonstrated to be effective and efficient. We used our method to automatically process and analyze 3470 images obtained by MLSO from January 1998 to December 2009, and a butterfly diagram of filaments is obtained. It shows that the latitudinal migration of solar filaments has three trends in the Solar Cycle 23: The drift velocity was fast from 1998 to the solar maximum; after the solar maximum, it became relatively slow and after 2006, the migration became divergent, signifying the solar minimum. About 60% filaments with the latitudes larger than 50 degree migrate towards the Polar Regions with relatively high velocities, and the latitudinal migrating

  3. Unwinding motion of a twisted active region filament

    Energy Technology Data Exchange (ETDEWEB)

    Yan, X. L.; Xue, Z. K.; Kong, D. F. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Liu, J. H. [Department of Physics, Shijiazhuang University, Shijiazhuang 050035 (China); Xu, C. L. [Yunnan Normal University, Kunming 650092 (China)

    2014-12-10

    To better understand the structures of active region filaments and the eruption process, we study an active region filament eruption in active region NOAA 11082 in detail on 2010 June 22. Before the filament eruption, the opposite unidirectional material flows appeared in succession along the spine of the filament. The rising of the filament triggered two B-class flares at the upper part of the filament. As the bright material was injected into the filament from the sites of the flares, the filament exhibited a rapid uplift accompanying the counterclockwise rotation of the filament body. From the expansion of the filament, we can see that the filament consisted of twisted magnetic field lines. The total twist of the filament is at least 5π obtained by using a time slice method. According to the morphology change during the filament eruption, it is found that the active region filament was a twisted flux rope and its unwinding motion was like a solar tornado. We also find that there was a continuous magnetic helicity injection before and during the filament eruption. It is confirmed that magnetic helicity can be transferred from the photosphere to the filament. Using the extrapolated potential fields, the average decay index of the background magnetic fields over the filament is 0.91. Consequently, these findings imply that the mechanism of solar filament eruption could be due to the kink instability and magnetic helicity accumulation.

  4. Unwinding Motion of a Twisted Active Region Filament

    Science.gov (United States)

    Yan, X. L.; Xue, Z. K.; Liu, J. H.; Kong, D. F.; Xu, C. L.

    2014-12-01

    To better understand the structures of active region filaments and the eruption process, we study an active region filament eruption in active region NOAA 11082 in detail on 2010 June 22. Before the filament eruption, the opposite unidirectional material flows appeared in succession along the spine of the filament. The rising of the filament triggered two B-class flares at the upper part of the filament. As the bright material was injected into the filament from the sites of the flares, the filament exhibited a rapid uplift accompanying the counterclockwise rotation of the filament body. From the expansion of the filament, we can see that the filament consisted of twisted magnetic field lines. The total twist of the filament is at least 5π obtained by using a time slice method. According to the morphology change during the filament eruption, it is found that the active region filament was a twisted flux rope and its unwinding motion was like a solar tornado. We also find that there was a continuous magnetic helicity injection before and during the filament eruption. It is confirmed that magnetic helicity can be transferred from the photosphere to the filament. Using the extrapolated potential fields, the average decay index of the background magnetic fields over the filament is 0.91. Consequently, these findings imply that the mechanism of solar filament eruption could be due to the kink instability and magnetic helicity accumulation.

  5. Swirling around filaments: are large-scale structure vortices spinning up dark halos?

    CERN Document Server

    Laigle, Clotilde; Codis, Sandrine; Dubois, Yohan; Borgne, Damien le; Pogosyan, Dmitri; Devriendt, Julien; Peirani, Sebastien; Prunet, Simon; Rouberol, Stephane; Slyz, Adrianne; Sousbie, Thierry

    2013-01-01

    The kinematic analysis of dark matter and hydrodynamical simulations suggests that the vorticity in large-scale structure is mostly confined to, and predominantly aligned with their filaments, with an excess of probability of 20 per cent to have the angle between vorticity and filaments direction lower than 60 degrees relative to random orientations. The cross sections of these filaments are typically partitioned into four quadrants with opposite vorticity sign, arising from multiple flows, originating from neighbouring walls. The spins of halos embedded within these filaments are consistently aligned with this vorticity for any halo mass, with a stronger alignment for the most massive structures up to an excess of probability of 165 per cent. On large scales, adiabatic/cooling hydrodynamical simulations display the same vorticity in the gas as in the dark matter. The global geometry of the flow within the cosmic web is therefore qualitatively consistent with a spin acquisition for smaller halos induced by th...

  6. On the origin of non self-gravitating filaments in the ISM

    CERN Document Server

    Hennebelle, Patrick

    2013-01-01

    {Filaments are ubiquitous in the interstellar medium as recently emphasized by Herschel, yet their physical origin remains elusive} {It is therefore important to understand the physics of molecular clouds to investigate how filaments form and what is the role played by various processes such as turbulence and magnetic field.} {We use ideal MHD simulations to study the formation of clumps in various conditions including different magnetization and Mach numbers as well as two completely different setup. We then perform several analysis to compute the shape of the clumps and their link to velocities and forces using various approaches.} {We find that on average, clumps in MHD simulations are more filamentary that clumps in hydrodynamical simulations. Detailed analyses reveal that the filaments are in general preferentially aligned with the strain which means that these structures simply result from the strech induced by turbulence. Moreover filaments tend to be confined by the Lorentz force which therefore lead ...

  7. Striation and convection in penumbral filaments

    Science.gov (United States)

    Spruit, H. C.; Scharmer, G. B.; Löfdahl, M. G.

    2010-10-01

    Observations with the 1-m Swedish Solar Telescope of the flows seen in penumbral filaments are presented. Time sequences of bright filaments show overturning motions strikingly similar to those seen along the walls of small isolated structures in the active regions. The filaments show outward propagating striations with inclination angles suggesting that they are aligned with the local magnetic field. We interpret it as the equivalent of the striations seen in the walls of small isolated magnetic structures. Their origin is then a corrugation of the boundary between an overturning convective flow inside the filament and the magnetic field wrapping around it. The outward propagation is a combination of a pattern motion due to the downflow observed along the sides of bright filaments, and the Evershed flow. The observed short wavelength of the striation argues against the existence of a dynamically significant horizontal field inside the bright filaments. Its intensity contrast is explained by the same physical effect that causes the dark cores of filaments, light bridges and “canals”. In this way striation represents an important clue to the physics of penumbral structure and its relation with other magnetic structures on the solar surface. We put this in perspective with results from the recent 3-D radiative hydrodynamic simulations. 4 movies are only available in electronic form at http://www.aanda.org

  8. Filamentation of Campylobacter in broth cultures

    Directory of Open Access Journals (Sweden)

    Nacheervan M Ghaffar

    2015-06-01

    Full Text Available The transition from rod to filamentous cell morphology has been identified as a response to stressful conditions in many bacterial species and has been ascribed to confer certain survival advantages. Filamentation of Campylobacter jejuni was demonstrated to occur spontaneously on entry in to stationary phase distinguishing it from many other bacteria where a reduction in size is more common. The aim of this study was to investigate the cues that give rise to filamentation of C. jejuni and C. coli and gain insights into the process. Using minimal medium, augmentation of filamentation occurred and it was observed that this morphological change was wide spread amongst C. jejuni strains tested but was not universal in C. coli strains. Filamentation did not appear to be due to release of diffusible molecules, toxic metabolites, or be in response to oxidative stress in the medium. Separated filaments exhibited greater intracellular ATP contents (2.66 to 17.4 fg than spiral forms (0.99 to 1.7 fg and showed enhanced survival in water at 4oC and 37oC compared to spiral cells. These observations support the conclusion that the filaments are adapted to survive extra-intestinal environments. Differences in cell morphology and physiology need to be considered in the context of the design of experimental studies and the methods adopted for the isolation of campylobacters from food, clinical and environmental sources.

  9. Star forming filaments in warm dark models

    CERN Document Server

    Gao, Liang; Springel, Volker

    2014-01-01

    We performed a hydrodynamical cosmological simulation of the formation of a Milky Way-like galaxy in a warm dark matter (WDM) cosmology. Smooth and dense filaments, several co-moving mega parsec long, form generically above z 2 in this model. Atomic line cooling allows gas in the centres of these filaments to cool to the base of the cooling function, resulting in a very striking pattern of extended Lyman-limit systems (LLSs). Observations of the correlation function of LLSs might hence provide useful limits on the nature of the dark matter. We argue that the self-shielding of filaments may lead to a thermal instability resulting in star formation. We implement a sub-grid model for this, and find that filaments rather than haloes dominate star formation until z 6. Reionisation decreases the gas density in filaments, and the more usual star formation in haloes dominates below z 6, although star formation in filaments continues until z=2. Fifteen per cent of the stars of the z=0 galaxy formed in filaments. At hi...

  10. Filamentous Biopolymers on Surfaces: Atomic Force Microscopy Images Compared with Brownian Dynamics Simulation of Filament Deposition

    Science.gov (United States)

    Mücke, Norbert; Klenin, Konstantin; Kirmse, Robert; Bussiek, Malte; Herrmann, Harald; Hafner, Mathias; Langowski, Jörg

    2009-01-01

    Nanomechanical properties of filamentous biopolymers, such as the persistence length, may be determined from two-dimensional images of molecules immobilized on surfaces. For a single filament in solution, two principal adsorption scenarios are possible. Both scenarios depend primarly on the interaction strength between the filament and the support: i) For interactions in the range of the thermal energy, the filament can freely equilibrate on the surface during adsorption; ii) For interactions much stronger than the thermal energy, the filament will be captured by the surface without having equilibrated. Such a ‘trapping’ mechanism leads to more condensed filament images and hence to a smaller value for the apparent persistence length. To understand the capture mechanism in more detail we have performed Brownian dynamics simulations of relatively short filaments by taking the two extreme scenarios into account. We then compared these ‘ideal’ adsorption scenarios with observed images of immobilized vimentin intermediate filaments on different surfaces. We found a good agreement between the contours of the deposited vimentin filaments on mica (‘ideal’ trapping) and on glass (‘ideal’ equilibrated) with our simulations. Based on these data, we have developed a strategy to reliably extract the persistence length of short worm-like chain fragments or network forming filaments with unknown polymer-surface interactions. PMID:19888472

  11. Filamentous biopolymers on surfaces: atomic force microscopy images compared with Brownian dynamics simulation of filament deposition.

    Directory of Open Access Journals (Sweden)

    Norbert Mücke

    Full Text Available Nanomechanical properties of filamentous biopolymers, such as the persistence length, may be determined from two-dimensional images of molecules immobilized on surfaces. For a single filament in solution, two principal adsorption scenarios are possible. Both scenarios depend primarily on the interaction strength between the filament and the support: i For interactions in the range of the thermal energy, the filament can freely equilibrate on the surface during adsorption; ii For interactions much stronger than the thermal energy, the filament will be captured by the surface without having equilibrated. Such a 'trapping' mechanism leads to more condensed filament images and hence to a smaller value for the apparent persistence length. To understand the capture mechanism in more detail we have performed Brownian dynamics simulations of relatively short filaments by taking the two extreme scenarios into account. We then compared these 'ideal' adsorption scenarios with observed images of immobilized vimentin intermediate filaments on different surfaces. We found a good agreement between the contours of the deposited vimentin filaments on mica ('ideal' trapping and on glass ('ideal' equilibrated with our simulations. Based on these data, we have developed a strategy to reliably extract the persistence length of short worm-like chain fragments or network forming filaments with unknown polymer-surface interactions.

  12. Thermal and Chemical Evolution of Collapsing Filaments

    Energy Technology Data Exchange (ETDEWEB)

    Gray, William J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Scannapieco, Evan [Arizona State Univ., Mesa, AZ (United States). School of Earth and Space Exploration

    2013-01-15

    Intergalactic filaments form the foundation of the cosmic web that connect galaxies together, and provide an important reservoir of gas for galaxy growth and accretion. Here we present very high resolution two-dimensional simulations of the thermal and chemical evolution of such filaments, making use of a 32 species chemistry network that tracks the evolution of key molecules formed from hydrogen, oxygen, and carbon. We study the evolution of filaments over a wide range of parameters including the initial density, initial temperature, strength of the dissociating UV background, and metallicity. In low-redshift, Z ≈ 0.1Z filaments, the evolution is determined completely by the initial cooling time. If this is sufficiently short, the center of the filament always collapses to form dense, cold core containing a substantial fraction of molecules. In high-redshift, Z = 10-3Z filaments, the collapse proceeds much more slowly. This is due mostly to the lower initial temperatures, which leads to a much more modest increase in density before the atomic cooling limit is reached, making subsequent molecular cooling much less efficient. Finally, we study how the gravitational potential from a nearby dwarf galaxy affects the collapse of the filament and compare this to NGC 5253, a nearby starbusting dwarf galaxy thought to be fueled by the accretion of filament gas. In contrast to our fiducial case, a substantial density peak forms at the center of the potential. This peak evolves faster than the rest of the filament due to the increased rate at which chemical species form and cooling occur. We find that we achieve similar accretion rates as NGC 5253, but our two-dimensional simulations do not recover the formation of the giant molecular clouds that are seen in radio observations.

  13. Thermal and Chemical Evolution of Collapsing Filaments

    Energy Technology Data Exchange (ETDEWEB)

    Gray, William J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Scannapieco, Evan [Arizona State Univ., Mesa, AZ (United States). School of Earth and Space Exploration

    2013-01-15

    Intergalactic filaments form the foundation of the cosmic web that connect galaxies together, and provide an important reservoir of gas for galaxy growth and accretion. Here we present very high resolution two-dimensional simulations of the thermal and chemical evolution of such filaments, making use of a 32 species chemistry network that tracks the evolution of key molecules formed from hydrogen, oxygen, and carbon. We study the evolution of filaments over a wide range of parameters including the initial density, initial temperature, strength of the dissociating UV background, and metallicity. In low-redshift, Z ≈ 0.1Z filaments, the evolution is determined completely by the initial cooling time. If this is sufficiently short, the center of the filament always collapses to form dense, cold core containing a substantial fraction of molecules. In high-redshift, Z = 10-3Z filaments, the collapse proceeds much more slowly. This is due mostly to the lower initial temperatures, which leads to a much more modest increase in density before the atomic cooling limit is reached, making subsequent molecular cooling much less efficient. Finally, we study how the gravitational potential from a nearby dwarf galaxy affects the collapse of the filament and compare this to NGC 5253, a nearby starbusting dwarf galaxy thought to be fueled by the accretion of filament gas. In contrast to our fiducial case, a substantial density peak forms at the center of the potential. This peak evolves faster than the rest of the filament due to the increased rate at which chemical species form and cooling occur. We find that we achieve similar accretion rates as NGC 5253 but our two-dimensional simulations do not recover the formation of the giant molecular clouds that are seen in radio observations.

  14. Hydrodynamic interactions of sheets vs filaments: Synchronization, attraction, and alignment

    Science.gov (United States)

    Olson, Sarah D.; Fauci, Lisa J.

    2015-12-01

    The synchronization of nearby sperm flagella as they swim in a viscous fluid was observed nearly a century ago. In the early 1950s, in an effort to shed light on this intriguing phenomenon, Taylor initiated the mathematical analysis of the fluid dynamics of microorganism motility. Since then, models have investigated sperm hydrodynamics where the flagellum is treated as a waving sheet (2D) or as a slender waving filament (3D). Here, we study the interactions of two finite length, flexible filaments confined to a plane in a 3D fluid and compare these to the interactions of the analogous pair of finite, flexible sheets in a 2D fluid. Within our computational framework using regularized Stokeslets, this comparison is easily achieved by choosing either the 2D or 3D regularized kernel to compute fluid velocities induced by the actuated structures. We find, as expected, that two flagella swimming with a symmetric beatform will synchronize (phase-lock) on a fast time scale and attract towards each other on a longer time scale in both 2D and 3D. For a symmetric beatform, synchronization occurs faster in 2D than 3D for sufficiently stiff swimmers. In 3D, a greater enhancement in efficiency and swimming velocity is observed for attracted swimmers relative to the 2D case. We also demonstrate the tendency of two asymmetrically beating filaments in a 3D fluid to align — in tandem — exhibiting an efficiency boost for the duration of their sustained alignment.

  15. Swimming speeds of filaments in viscous fluids with resistance

    Science.gov (United States)

    Ho, Nguyenho; Olson, Sarah D.; Leiderman, Karin

    2016-04-01

    Many microorganisms swim in a highly heterogeneous environment with obstacles such as fibers or polymers. To better understand how this environment affects microorganism swimming, we study propulsion of a cylinder or filament in a fluid with a sparse, stationary network of obstructions modeled by the Brinkman equation. The mathematical analysis of swimming speeds is investigated by studying an infinite-length cylinder propagating lateral or spiral displacement waves. For fixed bending kinematics, we find that swimming speeds are enhanced due to the added resistance from the fibers. In addition, we examine the work and the torque exerted on the cylinder in relation to the resistance. The solutions for the torque, swimming speed, and work of an infinite-length cylinder in a Stokesian fluid are recovered as the resistance is reduced to zero. Finally, we compare the asymptotic solutions with numerical results for the Brinkman flow with regularized forces. The swimming speed of a finite-length filament decreases as its length decreases and planar bending induces an angular velocity that increases linearly with added resistance. The comparisons between the asymptotic analysis and computation give insight on the effect of the length of the filament, the permeability, and the thickness of the cylinder in terms of the overall performance of planar and helical swimmers.

  16. Helicity and internal twist within the vortex filament model

    CERN Document Server

    Hietala, N; Salman, H

    2016-01-01

    For ideal fluids, besides energy, kinetic helicity is the only other known quadratic invariant of the Euler equations besides energy and is understood to be inherently linked to the degree of knotting of vortex lines within the fluid. For vortices arising in superfluid $^4$He, the vorticity is concentrated along vortex filaments. In this setting, helicity would be expected to acquire its simplest form. However, the lack of a core structure for vortex filaments appears to result in a helicity that does not retain its key attribute as a quadratic invariant. By defining the spanwise vector to coincide with the Seifert framing, we are able to introduce twist and henceforth recover the key properties of helicity. Through a detailed analysis of the velocity field induced in the vicinity of the superfluid vortices we are able to express our choice of the spanwise vector in terms of the tangential component of velocity along the filament. Since adding an arbitrary tangential velocity does not alter the configuration ...

  17. Can We Determine the Filament Chirality by the Filament Footpoint Location or the Barb-bearing?

    CERN Document Server

    Hao, Q; Fang, C; Chen, P F; Cao, W

    2015-01-01

    We attempt to propose a method for automatically detecting the solar filament chirality and barb bearing. We first introduce the unweighted undirected graph concept and adopt the Dijkstra shortest-path algorithm to recognize the filament spine. Then, we use the polarity inversion line (PIL) shift method for measuring the polarities on both sides of the filament, and employ the connected components labeling method to identify the barbs and calculate the angle between each barb and the spine to determine the bearing of the barbs, i.e., left or right. We test the automatic detection method with H-alpha filtergrams from the Big Bear Solar Observatory (BBSO) H-alpha archive and magnetograms observed with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Four filaments are automatically detected and illustrated to show the results. The barbs in different parts of a filament may have opposite bearings. The filaments in the southern hemisphere (northern hemisphere) mainly have ...

  18. Interaction and merging of vortex filaments

    Science.gov (United States)

    Liu, C. H.; Weston, R. P.; Ishii, K.; Ting, L.; Visintainer, J. A.

    1988-01-01

    The asymptotic solutions of Navier-Stokes equations for vortex filaments of finite strength with small effective vortical cores are summarized with special emphasis placed on the physical meaning and the practical limit to the applicability of the asymptotic solution. Finite-difference solutions of Navier-Stokes equations for the marging of the filament(s) are described with a focus on the development of the approximate boundary conditions for the computational domain. An efficiency study employing a model problem is used to assess the advantages of the present approximate boundary condition method over previously used techniques. Applications of the present method are presented for the motion and decay of a 3:1 elliptic vortex ring, and for the merging process of a pair of coaxial vortex rings. A numerical procedure for the problem of local merging of vortex filaments, which requires the asymptotic analysis as well as the numerical Navier-Stokes solver, is also presented.

  19. Influence of polarity of set voltage on the properties of conductive filaments in NiO based nonvolatile memory device

    Science.gov (United States)

    Yan, Hui-Yu; Li, Zhi-Qing

    2017-03-01

    In this paper, we realize the coexistence of bipolar and unipolar resistive switching (RS) in one Pt-Ir/NiO/TiB1+δ cell. The types of RS are controlled by polarity of set voltage and are free from the current compliance. Based on this coexistence, the set voltage and characters of filaments formed in RS are studied. The results show that the types of filaments also show polarity dependence on the set voltage. The positive set voltage can induce metallic filaments while the negative set voltage can result in semiconductor filaments. It reveals that the distribution of magnitude of set voltage shows abnormal polarity dependence in our devices. The combination the theory of interaction between oxygen vacancy defects and one-carrier impact ionization theory of breakdown account for these results. The influence of filament properties on RS types is also discussed.

  20. Role of coherent resonant nonlinear processes in the ultrashort KrF laser pulse propagation and filamentation in air

    Energy Technology Data Exchange (ETDEWEB)

    Smetanin, I.V.; Levchenko, A.O.; Shutov, A.V.; Ustinovskii, N.N. [P.N. Lebedev Physical Institute of Russian Academy of Sciences, 53 Leninskii pr., 119991 Moscow (Russian Federation); Zvorykin, V.D. [P.N. Lebedev Physical Institute of Russian Academy of Sciences, 53 Leninskii pr., 119991 Moscow (Russian Federation); National Research Nuclear University “MEPhI”, 31 Kashirskoe sh., 115409 Moscow (Russian Federation)

    2016-02-15

    Recent experiments on multiple filamentation of sub-picosecond terawatt-level KrF laser pulse in air and multi-photon ionization of air revealed an extremely low electron density in filaments, which is out of the conventional filamentation model considering Kerr self-focusing and plasma de-focusing. We propose here the coherent resonant scattering and ionization processes at the pulse durations significantly less than the polarization relaxation time to be possible explanation of the observed filamentation peculiarities. Namely, we argue that the plasma production results from the resonance enhanced (2+1)-photon ionization of the oxygen molecules through the two-photon excitation of the 3s metastable Rydberg state. Coherent Raman self-scattering at rotational transitions of nitrogen molecules provides self-induced focusing of the ultrashort UV laser pulse and filament formation.

  1. Organizing Filament of Small Amplitude Scroll Waves

    Institute of Scientific and Technical Information of China (English)

    ZHOU TianShou; ZHANG SuoChun

    2001-01-01

    We theoretically analyze the organizing filament of small amplitude scroll waves in general excitable media by perturbation method and explicitly give the expressions of coefficients in Keener theory. In particular for the excitable media with equal diffusion, we obtain a close system for the motion of the filament. With an example of the Oregonator model, our results are in good agreement with those simulated by Winfree.``

  2. Flux Cancellation Leading to CME Filament Eruptions

    Science.gov (United States)

    Popescu, Roxana M.; Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.

    2016-01-01

    Solar filaments are strands of relatively cool, dense plasma magnetically suspended in the lower density hotter solar corona. They trace magnetic polarity inversion lines (PILs) in the photosphere below, and are supported against gravity at heights of up to approx.100 Mm above the chromosphere by the magnetic field in and around them. This field erupts when it is rendered unstable, often by magnetic flux cancellation or emergence at or near the PIL. We have studied the evolution of photospheric magnetic flux leading to ten observed filament eruptions. Specifically, we look for gradual magnetic changes in the neighborhood of the PIL prior to and during eruption. We use Extreme Ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA), and magnetograms from the Helioseismic and Magnetic Imager (HMI), both on board the Solar Dynamics Observatory (SDO), to study filament eruptions and their photospheric magnetic fields. We examine whether flux cancellation or/and emergence leads to filament eruptions. We find that continuous flux cancellation was present at the PIL for many hours prior to each eruption. We present two CME-producing eruptions in detail and find the following: (a) the pre-eruption filament-holding core field is highly sheared and appears in the shape of a sigmoid above the PIL; (b) at the start of the eruption the opposite arms of the sigmoid reconnect in the middle above the site of (tether-cutting) flux cancellation at the PIL; (c) the filaments first show a slow-rise, followed by a fast-rise as they erupt. We conclude that these two filament eruptions result from flux cancellation in the middle of the sheared field, and thereafter evolve in agreement with the standard model for a CME/flare filament eruption from a closed bipolar magnetic field [flux cancellation (van Ballegooijen and Martens 1989 and Moore and Roumelrotis 1992) and runaway tether-cutting (Moore et. al 2001)].

  3. Morgellons disease: a filamentous borrelial dermatitis

    OpenAIRE

    Middelveen MJ; Stricker RB

    2016-01-01

    Marianne J Middelveen, Raphael B Stricker International Lyme and Associated Diseases Society, Bethesda, MD, USA Abstract: Morgellons disease (MD) is a dermopathy characterized by multicolored filaments that lie under, are embedded in, or project from skin. Although MD was initially considered to be a delusional disorder, recent studies have demonstrated that the dermopathy is associated with tickborne infection, that the filaments are composed of keratin and collagen, and that they resu...

  4. Can we determine the filament chirality by the filament footpoint location or the barb-bearing?

    Science.gov (United States)

    Hao, Qi; Guo, Yang; Fang, Cheng; Chen, Peng-Fei; Cao, Wen-Da

    2016-01-01

    We attempt to propose a method for automatically detecting the solar filament chirality and barb bearing. We first introduce the concept of an unweighted undirected graph and adopt the Dijkstra shortest path algorithm to recognize the filament spine. Then, we use the polarity inversion line (PIL) shift method for measuring the polarities on both sides of the filament, and employ the connected components labeling method to identify the barbs and calculate the angle between each barb and the spine to determine the bearing of the barbs, i.e., left or right. We test the automatic detection method with Hα filtergrams from the Big Bear Solar Observatory (BBSO) Hα archive and magnetograms observed with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Four filaments are automatically detected and illustrated to show the results. The barbs in different parts of a filament may have opposite bearings. The filaments in the southern hemisphere (northern hemisphere) mainly have left-bearing (right-bearing) barbs and positive (negative) magnetic helicity, respectively. The tested results demonstrate that our method is efficient and effective in detecting the bearing of filament barbs. It is demonstrated that the conventionally believed one-to-one correspondence between filament chirality and barb bearing is not valid. The correct detection of the filament axis chirality should be done by combining both imaging morphology and magnetic field observations.

  5. On the nature of star-forming filaments: II. Sub-filaments and velocities

    CERN Document Server

    Smith, Rowan J; Klessen, Ralf S; Fuller, Gary A

    2015-01-01

    We show that hydrodynamic turbulent cloud simulations naturally produce large filaments made up of a network of smaller and coherent sub-filaments. Such simulations resemble observations of filaments and fibres in nearby molecular clouds. The sub-filaments are dynamical features formed at the stagnation points of the turbulent velocity field where shocks dissipate the turbulent energy. They are a ubiquitous feature of the simulated clouds, which appear from the beginning of the simulation and are not formed by gradual fragmentation of larger filaments. Most of the sub-filaments are gravitationally sub-critical and do not fragment into cores, however, there is also a significant fraction of supercritical sub-filaments which break up into star-forming cores. The sub-filaments are coherent along their length, and the residual velocities along their spine show that they are subsonically contracting without any ordered rotation on scales of ~0.1 pc. Accretion flows along the sub-filaments can feed material into st...

  6. Dual-scale turbulence in filamenting laser beams at high average power

    CERN Document Server

    Schubert, Elise; Mongin, Denis; Kasparian, Jérôme; Wolf, Jean-Pierre; Klingebiel, Sandro; Schultze, Marcel; Metzger, Thomas; Michel, Knut

    2016-01-01

    We investigate the self-induced turbulence of high repetition rate laser filaments over a wide range of average powers (1 mW to 100 W) and its sensitivity to external atmospheric turbulence. Although both externally-imposed and self-generated turbulences can have comparable magnitudes, they act on different temporal and spatial scales. While the former drives the shot-to-shot motion at the millisecond time scale, the latter acts on the 0.5 s scale. As a consequence, their effects are decoupled, preventing beam stabilization by the thermally-induced low-density channel produced by the laser filaments.

  7. Filaments in the Lupus molecular clouds

    CERN Document Server

    Benedettini, M; Pezzuto, S; Elia, D; André, P; Könyves, V; Schneider, N; Tremblin, P; Arzoumanian, D; di Giorgio, A M; Di Francesco, J; Hill, T; Molinari, S; Motte, F; Nguyen-Luong, Q; Palmeirim, P; Rivera-Ingraham, A; Roy, A; Rygl, K L J; Spinoglio, L; Ward-Thompson, D; White, G J

    2015-01-01

    We have studied the filaments extracted from the column density maps of the nearby Lupus 1, 3, and 4 molecular clouds, derived from photometric maps observed with the Herschel satellite. Filaments in the Lupus clouds have quite low column densities, with a median value of $\\sim$1.5$\\times$10$^{21}$ cm$^{-2}$ and most have masses per unit length lower than the maximum critical value for radial gravitational collapse. Indeed, no evidence of filament contraction has been seen in the gas kinematics. We find that some filaments, that on average are thermally subcritical, contain dense cores that may eventually form stars. This is an indication that in the low column density regime, the critical condition for the formation of stars may be reached only locally and this condition is not a global property of the filament. Finally, in Lupus we find multiple observational evidences of the key role that the magnetic field plays in forming filaments, and determining their confinement and dynamical evolution.

  8. Filaments in Simulations of Molecular Cloud Formation

    CERN Document Server

    Gomez, Gilberto C

    2013-01-01

    We report on the filaments that develop self-consistently in a new numerical simulation of cloud formation by colliding flows. As in previous studies, the forming cloud begins to undergo gravitational collapse because it rapidly acquires a mass much larger than the average Jeans mass. Thus, the collapse is hierarchical in nature, proceeding along its shortest dimension first. This naturally produces filaments in cloud, and clumps within the filaments. The filaments are not in equilibrium at any time, but instead are long-lived flow features, through which the gas flows from the cloud to the clumps. The filaments are long-lived because they accrete from their environment while simultaneously accreting onto the clumps within them; they are essentially the locus where the flow changes from accreting in two dimensions to accreting in one dimension. Moreover, the clumps also exhibit a hierarchical nature: the gas in a filament flows onto a main, central clump, but other, smaller-scale clumps form along the infalli...

  9. Filaments in the Lupus molecular clouds

    Science.gov (United States)

    Benedettini, M.; Schisano, E.; Pezzuto, S.; Elia, D.; André, P.; Könyves, V.; Schneider, N.; Tremblin, P.; Arzoumanian, D.; di Giorgio, A. M.; Di Francesco, J.; Hill, T.; Molinari, S.; Motte, F.; Nguyen-Luong, Q.; Palmeirim, P.; Rivera-Ingraham, A.; Roy, A.; Rygl, K. L. J.; Spinoglio, L.; Ward-Thompson, D.; White, G. J.

    2015-10-01

    We have studied the filaments extracted from the column density maps of the nearby Lupus 1, 3, and 4 molecular clouds, derived from photometric maps observed with the Herschel satellite. Filaments in the Lupus clouds have quite low column densities, with a median value of ˜1.5 × 1021 cm-2 and most have masses per unit length lower than the maximum critical value for radial gravitational collapse. Indeed, no evidence of filament contraction has been seen in the gas kinematics. We find that some filaments, that on average are thermally subcritical, contain dense cores that may eventually form stars. This is an indication that in the low column density regime, the critical condition for the formation of stars may be reached only locally and this condition is not a global property of the filament. Finally, in Lupus we find multiple observational evidences of the key role that the magnetic field plays in forming filaments, and determining their confinement and dynamical evolution.

  10. Flexible magnetic filaments under the influence of external magnetic fields in the limit of infinite dilution.

    Science.gov (United States)

    Cerdà, Joan J; Sánchez, Pedro A; Lüsebrink, Daniel; Kantorovich, Sofia; Sintes, Tomàs

    2016-05-14

    In the present work we use Langevin dynamics computer simulations to understand how the presence of a constant external magnetic field modifies the conformational phase diagram of magnetic filaments in the limit of infinite dilution. We have considered the filaments immersed in either a good (non-sticky filaments) or a poor (Stockmayer polymers) solvent. It has been found that in the presence of an applied field, filaments turn out to be much more susceptible to parameters such as temperature and solvent conditions. Filaments owe this increased susceptibility to the fact that the external magnetic field tends to level the free energy landscape as compared to the zero-field case. The field induces equalization in the free energy of competing conformational states that were separated by large energy differences in the zero-field limit. In this new scenario multistability arises, and manifests itself in the existence of broad regions in the phase diagram where two or more equilibrium configurations coexist. The existence of multistability greatly enhances the possibility of tuning the properties of the filament.

  11. Swirling around filaments: are large-scale structure vortices spinning up dark haloes?

    Science.gov (United States)

    Laigle, C.; Pichon, C.; Codis, S.; Dubois, Y.; Le Borgne, D.; Pogosyan, D.; Devriendt, J.; Peirani, S.; Prunet, S.; Rouberol, S.; Slyz, A.; Sousbie, T.

    2015-01-01

    The kinematic analysis of dark matter and hydrodynamical simulations suggests that the vorticity in large-scale structure is mostly confined to, and predominantly aligned with, their filaments, with an excess of probability of 20 per cent to have the angle between vorticity and filaments direction lower than 60° relative to random orientations. The cross-sections of these filaments are typically partitioned into four quadrants with opposite vorticity sign, arising from multiple flows, originating from neighbouring walls. The spins of haloes embedded within these filaments are consistently aligned with this vorticity for any halo mass, with a stronger alignment for the most massive structures up to an excess of probability of 165 per cent. The global geometry of the flow within the cosmic web is therefore qualitatively consistent with a spin acquisition for smaller haloes induced by this large-scale coherence, as argued in Codis et al. In effect, secondary anisotropic infall (originating from the vortex-rich filament within which these lower-mass haloes form) dominates the angular momentum budget of these haloes. The transition mass from alignment to orthogonality is related to the size of a given multi-flow region with a given polarity. This transition may be reconciled with the standard tidal torque theory if the latter is augmented so as to account for the larger scale anisotropic environment of walls and filaments.

  12. Otomycosis due to filamentous fungi.

    Science.gov (United States)

    García-Agudo, Lidia; Aznar-Marín, Pilar; Galán-Sánchez, Fátima; García-Martos, Pedro; Marín-Casanova, Pilar; Rodríguez-Iglesias, Manuel

    2011-10-01

    Otomycosis is common throughout the world but barely studied in Spain. Our objective was to determine the microbiological and epidemiological characteristics of this pathology in Cadiz (Spain) between 2005 and 2010. Samples from patients with suspicion of otomycosis underwent a direct microscopic examination and culture on different media for fungi and bacteria. Mycological cultures were incubated at 30°C for at least seven days. Identification of fungi was based on colonial morphology and microscopic examination of fungal structure. From a total of 2,633 samples, microbial growth was present in 1,375 (52.2%) and fungal isolation in 390 (28.4%). We identified 228 yeasts and 184 filamentous fungi (13.4% of positive cultures and 47.2% of otomycosis), associated with yeasts in 22 cases (5.6%). The most frequent species were Aspergillus flavus (42.4%), A. niger (35.9%), A. fumigatus (12.5%), A. candidus (7.1%), A. terreus (1.6%), and Paecilomyces variotii (0.5%). Infection was predominant in men (54.9%) and patients beyond 55 years old (46.8%). The most common clinical symptoms were itching (98.9%), otalgia (59.3%), and hypoacusis (56.0%). Fall season reported the lowest number of cases (20.1%). Incidence of otomycosis and fungi producing otomycosis vary within the distinct geographical areas. In Cadiz, this infection is endemic due to warm temperatures, high humidity, sea bathing, and wind, which contributes to disseminate the conidia. Despite Aspergillus niger has been reported as the main causative agent, A. flavus is predominant in Cadiz. Although infection is usually detected in warm months, we observed a homogeneous occurrence of otomycosis in almost all the seasons.

  13. Potential fields of merging and splitting filaments in air

    Institute of Scientific and Technical Information of China (English)

    Ma Yuan-Yuan; Lu Xin; Xi Ting-Ting; Hao Zuo-Qiang; Gong Qi-Huang; Zhang Jie

    2007-01-01

    Two interacting light filaments with different initial phases propagating in air are investigated numerically by using a ray tracing method. The evolution of the rays of a filament is governed by a potential field. During propagation, the two potential wells of the two filaments can merge into one or repel each other, depending on the initial phase difference between the two filaments. The study provides a simple description of the interacting filaments.

  14. Alte und neue Problemaspekte der Figur. Zu einem medienübergreifenden Versuch einer Begriffsbestimmung der Figur [Jens Eder / Fotis Jannidis / Ralf Schneider (Hg.: Characters in Fic­tional Worlds. Understanding Imaginary Beings in Literature, Film, and Other Media. Berlin 2010

    Directory of Open Access Journals (Sweden)

    Carmen Lăcan

    2012-12-01

    Full Text Available Rezension zu / Review of:Jens Eder / Fotis Jannidis / Ralf Schneider (Hg.: Characters in Fic­tional Worlds. Understanding Imaginary Beings in Literature, Film, and Other Media. Berlin 2010

  15. Rapid severing and motility of chloroplast-actin filaments are required for the chloroplast avoidance response in Arabidopsis.

    Science.gov (United States)

    Kong, Sam-Geun; Arai, Yoshiyuki; Suetsugu, Noriyuki; Yanagida, Toshio; Wada, Masamitsu

    2013-02-01

    Phototropins (phot1 and phot2 in Arabidopsis thaliana) relay blue light intensity information to the chloroplasts, which move toward weak light (the accumulation response) and away from strong light (the avoidance response). Chloroplast-actin (cp-actin) filaments are vital for mediating these chloroplast photorelocation movements. In this report, we examine in detail the cp-actin filament dynamics by which the chloroplast avoidance response is regulated. Although stochastic dynamics of cortical actin fragments are observed on the chloroplasts, the basic mechanisms underlying the disappearance (including severing and turnover) of the cp-actin filaments are regulated differently from those of cortical actin filaments. phot2 plays a pivotal role in the strong blue light-induced severing and random motility of cp-actin filaments, processes that are therefore essential for asymmetric cp-actin formation for the avoidance response. In addition, phot2 functions in the bundling of cp-actin filaments that is induced by dark incubation. By contrast, the function of phot1 is dispensable for these responses. Our findings suggest that phot2 is the primary photoreceptor involved in the rapid reorganization of cp-actin filaments that allows chloroplasts to change direction rapidly and control the velocity of the avoidance movement according to the light's intensity and position.

  16. Filament Activation in Response to Magnetic Flux Emergence and Cancellation in Filament Channels

    CERN Document Server

    Li, Ting; Ji, Haisheng

    2015-01-01

    We make a comparative analysis for two filaments that showed quite different activation in response to the flux emergence within the filament channels. The observations from the Solar Dynamics Observatory (SDO) and Global Oscillation Network Group (GONG) are carried out to analyze the two filaments on 2013 August 17-20 and September 29. The first event showed that the main body of the filament was separated into two parts when an active region (AR) emerged with a maximum magnetic flux of about 6.4*10^21 Mx underlying the filament. The close neighborhood and common direction of the bright threads in the filament and the open AR fan loops suggest similar magnetic connectivity of these two flux systems. The equilibrium of the filament was not destroyed within 3 days after the start of the emergence of the AR. To our knowledge, similar observations have never been reported before. In the second event, the emerging flux occurred nearby a barb of the filament with a maximum magnetic flux of 4.2*10^20 Mx, about one ...

  17. Monogràfic "Segon Congrés sobre Internet, dret i política: anàlisi i prospectiva"

    Directory of Open Access Journals (Sweden)

    Estudis de Dret i Ciència Política

    2006-10-01

    Full Text Available

    Els dies 8 i 9 de maig de 2006 va tenir lloc el «Segon Congrés d'Internet, Dret i Política: Anàlisi i prospectiva», impulsat i organitzat pels Estudis de Dret i Ciència Política de la Universitat Oberta de Catalunya. Aquest Congrés ha estat una ocasió per a reflexionar sobre la regulació que hi ha respecte de la realitat d'Internet i una manera de fer pública la investigació que es porta a terme a la UOC i de transferir aquest coneixement a la societat civil.

    Aquest monogràfic recull les contribucions d'Amadeu Abril (director executiu de la Fundació punt.CAT, Benjamin R. Barber (professor of Civil Society and distinguised professor de la Universitat de Maryland, Erick Iriarte (vicepresident del comitè assessor At Large de l'ICANN i director executiu d'Alfa-Redi, Stefano Rodotà (expresident de l'Autoritat Italiana per a la Protecció de Dades Personals i expresident del Grup de l'Article 29 i de Clelia Colombo (guanyadora del Premi a la Millor Comunicació.

  18. Autobiografía y ficción en el cine = Autobiografia e ficção no cinema

    Directory of Open Access Journals (Sweden)

    Ermantraut, Sabrina Martino

    2013-01-01

    Full Text Available Este artigo refere-se à construção da narrativa autobiográfica através do cinema, e pretende estabelecer algumas linhas de pensamento sobre as possibilidades que este gênero pode oferecer para a abordagem da última ditadura militar na Argentina e no Brasil. A perspectiva metodológica centra-se na micro-história, destacando as experiências cotidianas e pessoais, oferecendo um olhar singular sobre o passado recente. Assim, foram selecionados dois filmes que recriam as experiências, esperanças e medos vividos por uma criança em um contexto singular de violência política. A partir da análise dos filmes e as histórias de seus diretores, podemos ver que o filme autobiográfico permite olhar para um passado reconstruído desde o presente da narrativa da experiência, a inclusão de elementos de ficção, as lembranças, os esquecimentos e as memórias pessoais e coletivas

  19. Drops moving along and across a filament

    Science.gov (United States)

    Sahu, Rakesh P.; Sinha-Ray, Suman; Yarin, Alexander; Pourdeyhimi, Behnam

    2013-11-01

    The present work is devoted to the experimental study of oil drop motion both along and across a filament due to the air jet blowing. In case of drop moving along the filament, phenomena such as drop stick-slip motion, shape oscillations, shedding of a tail along the filament, the tail capillary instability and drop recoil motion were observed which were rationalized in the framework of simplified models. Experiments with cross-flow of the surrounding gas relative to the filament with an oil drop on it were conducted, with air velocity in the range of 7.23 to 22.7 m s-1. The Weber number varied from 2 to 40 and the Ohnesorge number varied from 0.07 to 0.8. The lower and upper critical Weber numbers were introduced to distinguish between the beginning of the drop blowing off the filament and the onset of the bag-stamen breakup. The range of the Weber number between these two critical values is filled with three types of vibrational breakup: V1 (a balloon-like drop being blown off), V2 (a drop on a single stamen being blown off), and V3 (a drop on a double stamen being blown off). The Weber number/Ohnesorge number plane was delineated into domains of different breakup regimes. The work is supported by the Nonwovens Cooperative Research Center (NCRC).

  20. The hydrodynamic stability of gaseous cosmic filaments

    CERN Document Server

    Birnboim, Yuval; Zinger, Elad

    2016-01-01

    Virial shocks at edges of cosmic-web structures are a clear prediction of standard structure formation theories. We derive a criterion for the stability of the post-shock gas and of the virial shock itself in spherical, filamentary and planar infall geometries. When gas cooling is important, we find that shocks become unstable, and gas flows uninterrupted towards the center of the respective halo, filament or sheet. For filaments, we impose this criterion on self-similar infall solutions. We find that instability is expected for filament masses between $10^{11}-10^{13}M_\\odot Mpc^{-1}.$ Using a simplified toy model, we then show that these filaments will likely feed halos with $10^{10}M_{\\odot}\\lesssim M_{halo}\\lesssim 10^{13}M_{\\odot}$ at redshift $z=3$, as well as $10^{12}M_{\\odot}\\lesssim M_{halo}\\lesssim 10^{15}M_{\\odot}$ at $z=0$. The instability will affect the survivability of the filaments as they penetrate gaseous halos in a non-trivial way. Additionally, smaller halos accreting onto non-stable filam...

  1. Free-Space Nonlinear Beam Combining Towards Filamentation

    CERN Document Server

    Rostami, Shermineh; Kepler, Daniel; Baudelet, Matthieu; Litchinitser, Natalia M; Richardson, Martin

    2016-01-01

    Multi-filamentation opens new degrees of freedom for manipulating electromagnetic waves in air. However, without control, multiple filament interactions, including attraction, repulsion or fusion often result in formation of complex disordered filament distributions. Moreover, high power beams conventionally used in multi-filament formation experiments often cause significant surface damage. The growing number of applications for laser filaments requires fine control of their formation and propagation. We demonstrate, experimentally and theoretically, that the attraction and fusion of ultrashort beams with initial powers below the critical value enable the eventual formation of a filament downstream. Filament formation is delayed to a predetermined distance in space, avoiding optical damage to external beam optics while still enabling robust filaments with controllable properties as if formed from a single high power beam. This paradigm introduces new opportunities for filament engineering eliminating the nee...

  2. Unwinding motion of a twisted active-region filament

    CERN Document Server

    Yan, X L; Liu, J H; Kong, D F; Xu, C L

    2014-01-01

    To better understand the structures of active-region filaments and the eruption process, we study an active-region filament eruption in active region NOAA 11082 in detail on June 22, 2010. Before the filament eruption, the opposite unidirectional material flows appeared in succession along the spine of the filament. The rising of the filament triggered two B-class flares at the upper part of the filament. As the bright material was injected into the filament from the sites of the flares, the filament exhibited a rapid uplift accompanying the counterclockwise rotation of the filament body. From the expansion of the filament, we can see that the filament is consisted of twisted magnetic field lines. The total twist of the filament is at least 5$\\pi$ obtained by using time slice method. According to the morphology change during the filament eruption, it is found that the active-region filament was a twisted flux rope and its unwinding motion was like a solar tornado. We also find that there was a continuous magn...

  3. Nanoscopic structural rearrangements of the Cu-filament in conductive-bridge memories

    Science.gov (United States)

    Celano, U.; Giammaria, G.; Goux, L.; Belmonte, A.; Jurczak, M.; Vandervorst, W.

    2016-07-01

    The electrochemical reactions triggering resistive switching in conductive-bridge resistive random access memory (CBRAM) are spatially confined in few tens of nm3. The formation and dissolution of nanoscopic Cu-filaments rely on the displacement of ions in such confined volume, and it is driven by the electric field induced ion migration and nanoscaled redox reactions. The stochastic nature of these fundamental processes leads to a large variability of the device performance. In this work, a combination of two- and three-dimensional scanning probe microscopy (SPM) techniques are used to study the conductive filament (CF) formation, rupture and its nanoscopic structural rearrangements. The high spatial confinement of our approach enables to locally induce RS in a confined area and image it in 3D. A conical shape of the CF is consistently observed, indicating that the ion migration is the rate limiting step in the filament formation when using high quality dielectrics as switching layers. The sub-10 nm electrical contact size of the AFM tip is used to study the filament's dissolution and detect the hopping conduction of Cu during the CF rupture. We consistently observe a tunnel gap formation associated with the tip-induced filament reset. Finally, aiming to match the fundamental understanding with the integrated device operations, we apply scalpel SPM to failed memory cells and directly observe the appearance of filament multiplicity as a major source of failures and variability in CBRAM.The electrochemical reactions triggering resistive switching in conductive-bridge resistive random access memory (CBRAM) are spatially confined in few tens of nm3. The formation and dissolution of nanoscopic Cu-filaments rely on the displacement of ions in such confined volume, and it is driven by the electric field induced ion migration and nanoscaled redox reactions. The stochastic nature of these fundamental processes leads to a large variability of the device performance. In this

  4. Oscillating Filaments: I - Oscillation and Geometrical Fragmentation

    CERN Document Server

    Gritschneder, Matthias; Burkert, Andreas

    2016-01-01

    We study the stability of filaments in equilibrium between gravity and internal as well as external pressure using the grid based AMR-code RAMSES. A homogeneous, straight cylinder below a critical line mass is marginally stable. However, if the cylinder is bent, e.g. with a slight sinusoidal perturbation, an otherwise stable configuration starts to oscillate, is triggered into fragmentation and collapses. This previously unstudied behavior allows a filament to fragment at any given scale, as long as it has slight bends. We call this process `geometrical fragmentation'. In our realization the spacing between the cores matches the wavelength of the sinusoidal perturbation, whereas up to now, filaments were thought to be only fragmenting on the characteristical scale set by the mass-to-line ratio. Using first principles, we derive the oscillation period as well as the collapse timescale analytically. To enable a direct comparison with observations, we study the line-of-sight velocity for different inclinations. ...

  5. Filament velocity scaling laws for warm ions

    Energy Technology Data Exchange (ETDEWEB)

    Manz, P. [Physik-Department E28, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany); Max-Planck-Institut für Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching (Germany); Carralero, D.; Birkenmeier, G.; Müller, H. W.; Scott, B. D. [Max-Planck-Institut für Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching (Germany); Müller, S. H. [Center for Momentum Transport and Flow Organization, University of California at San Diego, San Diego 92093 (United States); Fuchert, G. [Insitut für Grenzflächenverfahrenstechnik und Plasmatechnologie, Universität Stuttgart, 70569 Stuttgart (Germany); Stroth, U. [Max-Planck-Institut für Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching (Germany); Physik-Department E28, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany)

    2013-10-15

    The dynamics of filaments or blobs in the scrape-off layer of magnetic fusion devices are studied by magnitude estimates of a comprehensive drift-interchange-Alfvén fluid model. The standard blob models are reproduced in the cold ion case. Even though usually neglected, in the scrape-off layer, the ion temperature can exceed the electron temperature by an order of magnitude. The ion pressure affects the dynamics of filaments amongst others by adding up to the interchange drive and the polarisation current. It is shown how both effects modify the scaling laws for filament velocity in dependence of its size. Simplifications for experimentally relevant limit regimes are given. These are the sheath dissipation, collisional, and electromagnetic regime.

  6. Filament velocity scaling laws for warm ions

    Science.gov (United States)

    Manz, P.; Carralero, D.; Birkenmeier, G.; Müller, H. W.; Müller, S. H.; Fuchert, G.; Scott, B. D.; Stroth, U.

    2013-10-01

    The dynamics of filaments or blobs in the scrape-off layer of magnetic fusion devices are studied by magnitude estimates of a comprehensive drift-interchange-Alfvén fluid model. The standard blob models are reproduced in the cold ion case. Even though usually neglected, in the scrape-off layer, the ion temperature can exceed the electron temperature by an order of magnitude. The ion pressure affects the dynamics of filaments amongst others by adding up to the interchange drive and the polarisation current. It is shown how both effects modify the scaling laws for filament velocity in dependence of its size. Simplifications for experimentally relevant limit regimes are given. These are the sheath dissipation, collisional, and electromagnetic regime.

  7. Heterologous expression of cellobiohydrolases in filamentous fungi

    DEFF Research Database (Denmark)

    Zoglowek, Marta; Lübeck, Peter S.; Ahring, Birgitte K.

    2015-01-01

    Cellobiohydrolases are among the most important enzymes functioning in the hydrolysis of crystalline cellulose, significantly contributing to the efficient biorefining of recalcitrant lignocellulosic biomass into biofuels and bio-based products. Filamentous fungi are recognized as both well...... into valuable products. However, due to low cellobiohydrolase activities, certain fungi might be deficient with regard to enzymes of value for cellulose conversion, and improving cellobiohydrolase expression in filamentous fungi has proven to be challenging. In this review, we examine the effects of altering...... promoters, signal peptides, culture conditions and host post-translational modifications. For heterologous cellobiohydrolase production in filamentous fungi to become an industrially feasible process, the construction of site-integrating plasmids, development of protease-deficient strains and glycosylation...

  8. Flexible magnetic filaments in a shear flow

    Energy Technology Data Exchange (ETDEWEB)

    Cebers, Andrejs [Institute of Physics, University of Latvia, Salaspils-1 LV-2169 (Latvia)]. E-mail: aceb@tesla.sal.lv

    2006-05-15

    By flexible magnetic filament model its behavior under the simultaneous action of the shear flow and the magnetic field is investigated. It is found that for magnetoelastic numbers larger as the critical value, which depends on the shear rate, the periodic regime is established. For the values of the magnetoelastic number close to the critical the periodical regime is characterized by a rather slow development of the buckling instability due to the action of magnetic torques with the subsequent stage of the fast straightening of the filament. For the magnetoelastic numbers below the critical slightly bent shape of the filament orientated along the flow is established. The application of the results for the description of the viscoelasticity of the magnetorheological suspensions is discussed.

  9. Production of recombinant proteins by filamentous fungi.

    Science.gov (United States)

    Ward, Owen P

    2012-01-01

    The initial focus of recombinant protein production by filamentous fungi related to exploiting the extraordinary extracellular enzyme synthesis and secretion machinery of industrial strains, including Aspergillus, Trichoderma, Penicillium and Rhizopus species, was to produce single recombinant protein products. An early recognized disadvantage of filamentous fungi as hosts of recombinant proteins was their common ability to produce homologous proteases which could degrade the heterologous protein product and strategies to prevent proteolysis have met with some limited success. It was also recognized that the protein glycosylation patterns in filamentous fungi and in mammals were quite different, such that filamentous fungi are likely not to be the most suitable microbial hosts for production of recombinant human glycoproteins for therapeutic use. By combining the experience gained from production of single recombinant proteins with new scientific information being generated through genomics and proteomics research, biotechnologists are now poised to extend the biomanufacturing capabilities of recombinant filamentous fungi by enabling them to express genes encoding multiple proteins, including, for example, new biosynthetic pathways for production of new primary or secondary metabolites. It is recognized that filamentous fungi, most species of which have not yet been isolated, represent an enormously diverse source of novel biosynthetic pathways, and that the natural fungal host harboring a valuable biosynthesis pathway may often not be the most suitable organism for biomanufacture purposes. Hence it is expected that substantial effort will be directed to transforming other fungal hosts, non-fungal microbial hosts and indeed non microbial hosts to express some of these novel biosynthetic pathways. But future applications of recombinant expression of proteins will not be confined to biomanufacturing. Opportunities to exploit recombinant technology to unravel the

  10. Light-mediated control of gene expression in filamentous fungus Trichoderma reesei.

    Science.gov (United States)

    Wang, Wei; Shi, Xiang-Yu; Wei, Dong-Zhi

    2014-08-01

    We developed a light-mediated system based on synthetic light-switchable transactivators. The transactivators bind promoter upon blue-light exposure and rapidly initiate transcription of target transgenes in filamentous fungus Trichoderma reesei. Light is inexpensive to apply, easily delivered, and instantly removed, and thus has significant advantages over chemical inducers.

  11. MHD Seismology of a loop-like filament tube by observed kink waves

    National Research Council Canada - National Science Library

    Vaibhav Pant Abhishek K Srivastava Dipankar Banerjee Marcel Goossens Peng-Fei Chen Navin Chandra Joshi Yu-Hao Zhou

    2015-01-01

    ...)/Global Oscillation Network Group (GONG). An M1.1-class flare in active region (AR) 11692 occurred on 2013 March 15 and induced a global kink mode in the filament lying towards the southwest of AR 11692...

  12. Reduced filamentation in high power semiconductor lasers

    DEFF Research Database (Denmark)

    Skovgaard, Peter M. W.; McInerney, John; O'Brien, Peter

    1999-01-01

    High brightness semiconductor lasers have applications in fields ranging from material processing to medicine. The main difficulty associated with high brightness is that high optical power densities cause damage to the laser facet and thus require large apertures. This, in turn, results in spatio...... in the optical field causes spatial hole-burning and thus filamentation. To reduce filamentation we propose a new, relatively simple design based on inhomogeneous pumping in which the injected current has a gradual transverse profile. We confirm the improved laser performance theoretically and experimentally...

  13. Generation of stable overlaps between antiparallel filaments

    CERN Document Server

    Johann, D; Kruse, K

    2015-01-01

    During cell division, sister chromatids are segregated by the mitotic spindle, a bipolar assembly of interdigitating antiparallel polar filaments called microtubules. Establishing a stable overlap region is essential for maintenance of bipolarity, but the underlying mechanisms are poorly understood. Using a particle-based stochastic model, we find that the interplay of motors and passive cross linkers can robustly generate partial overlaps between antiparallel filaments. Our analysis shows that motors reduce the overlap in a length-dependent manner, whereas passive cross linkers increase it independently of the length. In addition to maintaining structural integrity, passive cross linkers can thus also have a dynamic role for size regulation.

  14. Filament stretching rheometer: inertia compensation revisited

    DEFF Research Database (Denmark)

    Szabo, Peter; McKinley, Gareth H.

    2003-01-01

    The necessary inertia compensation used in the force balance for the filament stretching rheometer is derived for an arbitrary frame of reference. This enables the force balance to be used to extract correctly the extensional viscosity from measurements of the tensile force at either end of the e......The necessary inertia compensation used in the force balance for the filament stretching rheometer is derived for an arbitrary frame of reference. This enables the force balance to be used to extract correctly the extensional viscosity from measurements of the tensile force at either end...

  15. Nuclear flow in a filamentous fungus

    CERN Document Server

    Hickey, Patrick C; Read, Nick; Glass, N Louise; Roper, Marcus

    2012-01-01

    The syncytial cells of a filamentous fungus consist of a mass of growing, tube-like hyphae. Each extending tip is fed by a continuous flow of nuclei from the colony interior, pushed by a gradient in turgor pressure. The myco-fluidic flows of nuclei are complex and multidirectional, like traffic in a city. We map out the flows in a strain of the model filamentous fungus {\\it N. crassa} that has been transformed so that nuclei express either hH1-dsRed (a red fluorescent nuclear protein) or hH1-GFP (a green-fluorescent protein) and report our results in a fluid dynamics video.

  16. On the nature of star-forming filaments: I. Filament morphologies

    CERN Document Server

    Smith, Rowan J; Klessen, Ralf S

    2014-01-01

    We use a suite of high resolution molecular cloud simulations carried out with the moving mesh code Arepo to explore the nature of star-forming filaments. The simulated filaments are identified and categorised from column density maps in the same manner as for recent Herschel observations. When fit with a Plummer-like profile the filaments are in excellent agreement with observations, and have shallow power-law profiles of p~2.2 without the need for magnetic support. The derived filament widths depend on the data range that is fitted. When data within 1 pc of the filament centre is fitted with a Gaussian function, the average FWHM is ~0.3 pc, in agreement with predictions for accreting filaments. However, if the fit is constructed using only data within 0.35 pc of the centre, in order to better match the procedure used to derive filament widths from Herschel observations, the resulting FWHM is only ~0.2 pc. This value is larger than that measured in IC 5146 and Taurus, but is similar to that found in the Plan...

  17. Modelling the chemistry of star-forming filaments - II. Testing filament characteristics with synthetic observations

    Science.gov (United States)

    Seifried, D.; Sánchez-Monge, Á.; Suri, S.; Walch, S.

    2017-06-01

    We present synthetic continuum and 13CO and C18O line emission observations of dense and cold filaments. The filaments are dynamically evolved using 3D-magnetohydrodynamic simulations that include one of the largest on-the-fly chemical networks used to date, which models the detailed evolution of H2 and CO. We investigate the reliability of observable properties, in particular filament mass and width, under different simulation conditions like magnetic field orientation and cosmic ray ionization rate. We find that filament widths of ˜0.1 pc can be probed with both line and continuum emission observations with a high accuracy (deviations ≤20 per cent). However, the width of more narrow filaments can be significantly overestimated by up to a factor of a few. Masses obtained via the dust emission are accurate within a few per cent whereas the masses inferred from molecular line emission observations deviate from the actual mass by up to a factor of 10 and show large differences for different J transitions. The inaccurate estimate of filament masses and widths of narrow filaments using molecular line observations can be attributed to (i) the non-isothermal state of the filaments, (ii) optical depth effects and (iii) the subthermally excited state of CO, while inclination effects and opacity correction only influence the obtained masses and widths by less than 50 per cent. Both, mass and width estimates, can be improved by using two isotopes to correct for the optical depth. Since gas and dust temperatures generally differ (by up to 25 K), the filaments appear more gravitationally unstable if the (too low) dust temperature is used for the stability analysis.

  18. Impulsive rotational Raman scattering of N2 by a remote "air laser" in femtosecond laser filament

    CERN Document Server

    Ni, Jielei; Zhang, Haisu; Zeng, Bin; Yao, Jinping; Li, Guihua; Jing, Chenrui; Xie, Hongqiang; Xu, Huailiang; Cheng, Ya; Xu, Zhizhan

    2014-01-01

    We report on experimental realization of impulsive rotational Raman scattering from neutral nitrogen molecules in a femtosecond laser filament using an intense self-induced white-light seeding "air laser" generated during the filamentation of an 800 nm Ti: Sapphire laser in nitrogen gas. The impulsive rotational Raman fingerprint signals are observed with a maximum conversion efficiency of ~0.8%. Our observation provides a promising way of remote identification and location of chemical species in atmosphere by rotational Raman scattering of molecules.

  19. High-resolution Observations of Sympathetic Filament Eruptions by NVST

    Science.gov (United States)

    Su, Yingna; Li, Shangwei; Zhou, Tuanhui; Van Ballegooijen, Adriaan A.; Sun, Xudong; Ji, Haisheng

    2017-08-01

    We investigate two sympathetic filament eruptions observed by the New Vacuum Solar Telescope (NVST) on 2015 October 15. The full picture of the eruptions is obtained from the corresponding SDO/AIA observations. The two filaments start from the east border of active region NOAA 12434 in the north and end in one large quiescent filament channel in the south. The left filament erupts firstly, followed by the right filament eruption about 10 minutes later. Clear twist structure and rotating motion are observed in both filaments during the eruption. Both eruptions are failed, since the filaments firstly rise up, then flow towards the south and merge into the southern large quiescent filament. We also observe repeating activations of mini filaments below the right filament after its eruption. Using magnetic field models constructed based on SDO/HMI magnetograms by flux rope insertion method, we find that the left filament eruption is likely to be triggered by kink instability, while weakening of overlying magnetic fields due to magnetic reconnection at an X-point between the two filament systems might play an important role in the onset of the right filament eruption.

  20. Filament formation of Salmonella Paratyphi A accompanied by FtsZ assembly impairment and low level ppGpp.

    Science.gov (United States)

    Yamaguchi, Takayoshi; Iida, Ken-Ichiro; Shiota, Susumu; Nakayama, Hiroaki; Yoshida, Shin-Ichi

    2015-12-01

    Previously, we reported that Salmonella enterica serovar Paratyphi A strain S602 grew into multinuclear, nonseptate, and nonlethal filaments on agar plates containing nitrogenous salts. Strain S602 was more sensitive to osmotic and oxidative stress than the reference strain 3P243 of nonfilamentous Salmonella Paratyphi A. Strain S602 had an amber mutation (C154T) in rpoS. The revertant of this mutant, SR603, was repressed to form filaments under conditions with abundant nitrogenous salts. However, 3PR244, an rpoS mutant of 3P243 (C154T), did not form filaments, which implies that the rpoS mutation is not the sole cause of filamentation in strain S602. Next, we examined whether the level of guanosine 5'-diphosphate 3'-diphosphate (ppGpp) in S602 strain is involved in filament formation. The intracellular ppGpp level in filamentous cells was lower than that in nonfilamentous cells. Furthermore, cells belonging to strain RE606, a derivative of S602 where the intracellular concentration of ppGpp was increased by overexpression of the relA gene, exhibited normal Z-ring formation and cell division. In the S602 strain, the decrease in the ppGpp level induced by the presence of nitrogenous salt and the rpoS mutation led to the inhibition of Z-ring formation and the subsequent filamentation of cells.

  1. Filament networks attached to membranes: cytoskeletal pressure and local bilayer deformation

    Science.gov (United States)

    Auth, Thorsten; Safran, S. A.; Gov, Nir S.

    2007-11-01

    Several cell types, among them red blood cells, have a cortical, two-dimensional (2D) network of filaments sparsely attached to their lipid bilayer. In many mammalian cells, this 2D polymer network is connected to an underlying 3D, more rigid cytoskeleton. In this paper, we consider the pressure exerted by the thermally fluctuating, cortical network of filaments on the bilayer and predict the bilayer deformations that are induced by this pressure. We treat the filaments as flexible polymers and calculate the pressure that a network of such linear chains exerts on the bilayer; we then minimize the bilayer shape in order to predict the resulting local deformations. We compare our predictions with membrane deformations observed in electron micrographs of red blood cells. The polymer pressure along with the resulting membrane deformation can lead to compartmentalization, regulate in-plane diffusion and may influence protein sorting as well as transmit signals to the polymerization of the underlying 3D cytoskeleton.

  2. Filament networks attached to membranes: cytoskeletal pressure and local bilayer deformation

    Energy Technology Data Exchange (ETDEWEB)

    Auth, Thorsten [Department of Materials and Interfaces, Weizmann Institute of Science, PO Box 26, Rehovot 76100 (Israel); Safran, S A [Department of Materials and Interfaces, Weizmann Institute of Science, PO Box 26, Rehovot 76100 (Israel); Gov, Nir S [Department of Chemical Physics, Weizmann Institute of Science, PO Box 26, Rehovot 76100 (Israel)

    2007-11-15

    Several cell types, among them red blood cells, have a cortical, two-dimensional (2D) network of filaments sparsely attached to their lipid bilayer. In many mammalian cells, this 2D polymer network is connected to an underlying 3D, more rigid cytoskeleton. In this paper, we consider the pressure exerted by the thermally fluctuating, cortical network of filaments on the bilayer and predict the bilayer deformations that are induced by this pressure. We treat the filaments as flexible polymers and calculate the pressure that a network of such linear chains exerts on the bilayer; we then minimize the bilayer shape in order to predict the resulting local deformations. We compare our predictions with membrane deformations observed in electron micrographs of red blood cells. The polymer pressure along with the resulting membrane deformation can lead to compartmentalization, regulate in-plane diffusion and may influence protein sorting as well as transmit signals to the polymerization of the underlying 3D cytoskeleton.

  3. Dynamic Wrinkling and Strengthening of an Elastic Filament in a Viscous Fluid

    Science.gov (United States)

    Chopin, Julien; Dasgupta, Moumita; Kudrolli, Arshad

    2017-08-01

    We investigate the wrinkling dynamics of an elastic filament immersed in a viscous fluid submitted to compression at a finite rate with experiments and by combining geometric nonlinearities, elasticity, and slender body theory. The drag induces a dynamic lateral reinforcement of the filament leading to growth of wrinkles that coarsen over time. We discover a new dynamical regime characterized by a time scale with a nontrivial dependence on the loading rate, where the growth of the instability is superexponential and the wave number is an increasing function of the loading rate. We find that this time scale can be interpreted as the characteristic time over which the filament transitions from the extensible to the inextensible regime. In contrast with our analysis with moving boundary conditions, Biot's analysis in the limit of infinitely fast loading leads to rate independent exponential growth and wavelength.

  4. Distribution pattern changes of actin filaments during chloroplast movement in Adiantum capillus-veneris.

    Science.gov (United States)

    Tsuboi, Hidenori; Wada, Masamitsu

    2012-05-01

    Chloroplasts change their positions in a cell in response to light intensities. The photoreceptors involved in chloroplast photo-relocation movements and the behavior of chloroplasts during their migration were identified in our previous studies, but the mechanism of movement has yet to be clarified. In this study, the behavior of actin filaments under various light conditions was observed in Adiantum capillus-veneris gametophytes. In chloroplasts staying in one place under a weak light condition and not moving, circular structures composed of actin filaments were observed around the chloroplast periphery. In contrast, short actin filaments were observed at the leading edge of moving chloroplasts induced by partial cell irradiation. In the dark, the circular structures found under the weak light condition disappeared and then reappeared around the moving chloroplasts. Mutant analyses revealed that the disappearance of the circular actin structure was mediated by the blue light photoreceptor, phototropin2.

  5. Regular "Breathing" of Single-Cycle Light Bullets in Mid-IR Filament

    CERN Document Server

    Chekalin, S V; Kuznetzov, A V; Dormidonov, A E; Shlenov, S A; Kandidov, V P

    2015-01-01

    Experimental and numerical studies of a temporal evolution of a light bullet formed in isotropic LiF by Mid IR femtosecond pulse (2500 to 3250 nm) of power, slightly exceeding the critical power for self-focusing, are presented. For the first time regular oscillations of the light bullet intensity during its propagation in a filament were registered by investigation of induced color centers in LiF. It was revealed that color centers in a single laser pulse filament have a strictly periodic structure with a length of separate sections about 30 mcm, which increases with a laser pulse wavelength decreasing. It was shown that the origin of light bullet modulation is a periodical change of the light field amplitude of an extremely compressed single cycle wave packet in a filament, due to the difference of the wave packet group velocity and the carrier wave phase velocity.

  6. The exo-metabolome in filamentous fungi

    DEFF Research Database (Denmark)

    Thrane, Ulf; Andersen, Birgitte; Frisvad, Jens Christian

    2007-01-01

    Filamentous fungi are a diverse group of eukaryotic microorganisms that have a significant impact on human life as spoilers of food and feed by degradation and toxin production. They are also most useful as a source of bulk and fine chemicals and pharmaceuticals. This chapter focuses on the exo...

  7. The Apis mellifera filamentous virus genome

    Science.gov (United States)

    A complete reference genome of the Apis mellifera Filamentous virus (AmFV) was determined using Illumina Hiseq sequencing. The AmFV genome is a double strand DNA molecule of approximately 498’500 nucleotides with a GC content of 50.8%. It encompasses 251 non overlapping open reading frames (ORFs), e...

  8. Modelling the morphology of filamentous microorganisms

    DEFF Research Database (Denmark)

    Nielsen, Jens Bredal

    1996-01-01

    The rapid development in image analysis techniques has made it possible to study the growth kinetics of filamentous microorganisms in more detail than previously, However, owing to the many different processes that influence the morphology it is important to apply mathematical models to extract...

  9. Conformational phases of membrane bound cytoskeletal filaments

    Science.gov (United States)

    Quint, David A.; Grason, Gregory; Gopinathan, Ajay

    2013-03-01

    Membrane bound cytoskeletal filaments found in living cells are employed to carry out many types of activities including cellular division, rigidity and transport. When these biopolymers are bound to a membrane surface they may take on highly non-trivial conformations as compared to when they are not bound. This leads to the natural question; What are the important interactions which drive these polymers to particular conformations when they are bound to a surface? Assuming that there are binding domains along the polymer which follow a periodic helical structure set by the natural monomeric handedness, these bound conformations must arise from the interplay of the intrinsic monomeric helicity and membrane binding. To probe this question, we study a continuous model of an elastic filament with intrinsic helicity and map out the conformational phases of this filament for various mechanical and structural parameters in our model, such as elastic stiffness and intrinsic twist of the filament. Our model allows us to gain insight into the possible mechanisms which drive real biopolymers such as actin and tubulin in eukaryotes and their prokaryotic cousins MreB and FtsZ to take on their functional conformations within living cells.

  10. Filament eruption with apparent reshuffle of endpoints

    CERN Document Server

    Filippov, Boris

    2014-01-01

    Filament eruption on 30 April - 1 May 2010, which shows the reconnection of one filament leg with a region far away from its initial position, is analyzed. Observations from three viewpoints are used for as precise as possible measurements of endpoint coordinates. The northern leg of the erupting prominence loop 'jumps' laterally to the latitude lower than the latitude of the originally southern endpoint. Thus, the endpoints reshuffled their positions in the limb view. Although this behaviour could be interpreted as the asymmetric zipping-like eruption, it does not look very likely. It seems more likely to be reconnection of the flux-rope field lines in its northern leg with ambient coronal magnetic field lines rooted in a quiet region far from the filament. From calculations of coronal potential magnetic field, we found that the filament before the eruption was stable for vertical displacements, but was liable to violation of the horizontal equilibrium. This is unusual initiation of an eruption with combinat...

  11. Morphology and rheology in filamentous cultivations.

    Science.gov (United States)

    Wucherpfennig, T; Kiep, K A; Driouch, H; Wittmann, C; Krull, R

    2010-01-01

    Because of their metabolic diversity, high production capacity, secretion efficiency, and capability of carrying out posttranslational modifications, filamentous fungi are widely exploited as efficient cell factories in the production of metabolites, bioactive substances, and native or heterologous proteins, respectively. There is, however, a complex relationship between the morphology of these microorganisms, transport phenomena, the viscosity of the cultivation broth, and related productivity. The morphological characteristics vary between freely dispersed mycelia and distinct pellets of aggregated biomass, every growth form having a distinct influence on broth rheology. Hence, the advantages and disadvantages for mycelial or pellet cultivation have to be balanced out carefully. Because of the still inadequate understanding of the morphogenesis of filamentous microorganisms, fungal morphology is often a bottleneck of productivity in industrial production. To obtain an optimized production process, it is of great importance to gain a better understanding of the molecular and cell biology of these microorganisms as well as the relevant approaches in biochemical engineering. In this chapter, morphology and growth of filamentous fungi are described, with special attention given to specific problems as they arise from fungal growth forms; growth and mass transfer in fungal biopellets are discussed as an example. To emphasize the importance of the flow behavior of filamentous cultivation broths, an introduction to rheology is also given, reviewing important rheological models and recent studies concerning rheological parameters. Furthermore, current knowledge on morphology and productivity in relation to the environom is outlined in the last section of this review. Copyright 2010 Elsevier Inc. All rights reserved.

  12. Linear viscoelastic characterization from filament stretching rheometry

    DEFF Research Database (Denmark)

    Wingstrand, Sara Lindeblad; Alvarez, Nicolas J.; Hassager, Ole

    viscoelasticity well into the nonlinear regime. Therefore at present, complete rheological characterization of a material requires two apparatuses: a shear and an extensional rheometer. This work is focused on developing a linear viscoelastic protocol for the filament stretching rheometer (FSR) in order...

  13. Filament stretching rheometry of polymer melts

    DEFF Research Database (Denmark)

    Hassager, Ole; Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz

    2005-01-01

    The Filament Stretching Rheometry (FSR) method developed by Sridhar, McKinley and coworkers for polymer solutions has been extended to be used also for polymer melts. The design of a melt-FSR will be described and differences to conventional melt elongational rheometers will be pointed out. Results...

  14. Using Drosophila for Studies of Intermediate Filaments.

    Science.gov (United States)

    Bohnekamp, Jens; Cryderman, Diane E; Thiemann, Dylan A; Magin, Thomas M; Wallrath, Lori L

    2016-01-01

    Drosophila melanogaster is a useful organism for determining protein function and modeling human disease. Drosophila offers a rapid generation time and an abundance of genomic resources and genetic tools. Conservation in protein structure, signaling pathways, and developmental processes make studies performed in Drosophila relevant to other species, including humans. Drosophila models have been generated for neurodegenerative diseases, muscular dystrophy, cancer, and many other disorders. Recently, intermediate filament protein diseases have been modeled in Drosophila. These models have revealed novel mechanisms of pathology, illuminated potential new routes of therapy, and make whole organism compound screens feasible. The goal of this chapter is to outline steps to study intermediate filament function and model intermediate filament-associated diseases in Drosophila. The steps are general and can be applied to study the function of almost any protein. The protocols outlined here are for both the novice and experienced Drosophila researcher, allowing the rich developmental and cell biology that Drosophila offers to be applied to studies of intermediate filaments.

  15. Self-assembly of Artificial Actin Filaments

    Science.gov (United States)

    Grosenick, Christopher; Cheng, Shengfeng

    Actin Filaments are long, double-helical biopolymers that make up the cytoskeleton along with microtubules and intermediate filaments. In order to further understand the self-assembly process of these biopolymers, a model to recreate actin filament geometry was developed. A monomer in the shape of a bent rod with vertical and lateral binding sites was designed to assemble into single or double helices. With Molecular Dynamics simulations, a variety of phases were observed to form by varying the strength of the binding sites. Ignoring lateral binding sites, we have found a narrow range of binding strengths that lead to long single helices via various growth pathways. When lateral binding strength is introduced, double helices begin to form. These double helices self-assemble into substantially more stable structures than their single helix counterparts. We have found double helices to form long filaments at about half the vertical binding strength of single helices. Surprisingly, we have found that triple helices occasionally form, indicating the importance of structural regulation in the self-assembly of biopolymers.

  16. Filament stretching rheometry of polymer melts

    DEFF Research Database (Denmark)

    Hassager, Ole; Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz

    2005-01-01

    The Filament Stretching Rheometry (FSR) method developed by Sridhar, McKinley and coworkers for polymer solutions has been extended to be used also for polymer melts. The design of a melt-FSR will be described and differences to conventional melt elongational rheometers will be pointed out. Results...

  17. Featured Image: A Filament Forms and Erupts

    Science.gov (United States)

    Kohler, Susanna

    2017-06-01

    This dynamic image of active region NOAA 12241 was captured by the Solar Dynamics Observatorys Atmospheric Imaging Assembly in December 2014. Observations of this region from a number of observatories and instruments recently presented by Jincheng Wang (University of Chinese Academy of Sciences) and collaborators reveal details about the formation and eruption of a long solar filament. Wang and collaborators show that the right part of the filament formed by magnetic reconnection between two bundles of magnetic field lines, while the left part formed as a result of shearing motion. When these two parts interacted, the filament erupted. You can read more about the teams results in the article linked below. Also, check out this awesome video of the filament formation and eruption, again by SDO/AIA:http://cdn.iopscience.com/images/0004-637X/839/2/128/Full/apjaa6bf3f1_video.mp4CitationJincheng Wang et al 2017 ApJ 839 128. doi:10.3847/1538-4357/aa6bf3

  18. Filament Channel Formation, Eruption, and Jet Generation

    Science.gov (United States)

    DeVore, C. Richard; Antiochos, Spiro K.; Karpen, Judith T.

    2017-08-01

    The mechanism behind filament-channel formation is a longstanding mystery, while that underlying the initiation of coronal mass ejections and jets has been studied intensively but is not yet firmly established. In previous work, we and collaborators have investigated separately the consequences of magnetic-helicity condensation (Antiochos 2013) for forming filament channels (Zhao et al. 2015; Knizhnik et al. 2015, 2017a,b) and of the embedded-bipole model (Antiochos 1996) for generating reconnection-driven jets (Pariat et al. 2009, 2010, 2015, 2016; Wyper et al. 2016, 2017). Now we have taken a first step toward synthesizing these two lines of investigation. Our recent study (Karpen et al. 2017) of coronal-hole jets with gravity and wind employed an ad hoc, large-scale shear flow at the surface to introduce magnetic free energy and form the filament channel. In this effort, we replace the shear flow with an ensemble of local rotation cells, to emulate the Sun’s ever-changing granules and supergranules. As in our previous studies, we find that reconnection between twisted flux tubes within the closed-field region concentrates magnetic shear and free energy near the polarity inversion line, forming the filament channel. Onset of reconnection between this field and the external, unsheared, open field releases stored energy to drive the impulsive jet. We discuss the results of our new simulations with implications for understanding solar activity and space weather.

  19. Filamentous bacteria transport electrons over centimetre distances

    DEFF Research Database (Denmark)

    Pfeffer, Christian; Larsen, Steffen; Song, Jie

    2012-01-01

    across centimetre-wide zones. Here we present evidence that the native conductors are long, filamentous bacteria. They abounded in sediment zones with electric currents and along their length they contained strings with distinct properties in accordance with a function as electron transporters. Living...

  20. Nematic Liquid Crystal Alignment Behaviors between Crossed Stretched Miropolymer Filaments with Anchoring Effects

    Science.gov (United States)

    Fujikake, Hideo; Murashige, Takeshi; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio

    2006-04-01

    We observed the molecular alignment of a liquid crystal (LC) induced by crossing two stretched micropolymer filaments between glass substrates and confirmed its light modulation property. The two microfilaments, which were extracted from a cellulose cloth by stretching it in advance, had surface molecular alignment and stabilized nematic LC alignment between the microfilaments crossed with a small angle. In the fabricated LC cell, a spatially-uniform LC planar alignment is achieved in the area of a filament interval of less than 60 μm. By polarizing microscopy observation of the isotropic-to-nematic wetting transition of the LC material between the polymer filaments, it was confirmed that the stable LC alignment area is formed by the surface anchoring of the filaments. When external voltages were applied to the obtained uniformed alignment LC area, a characteristic periodic electrooptic property was confirmed on the basis of electrically-controlled birefringence under the alignment control of the in-plane anchoring of the filaments.

  1. Efficient genome editing in filamentous fungus Trichoderma reesei using the CRISPR/Cas9 system.

    Science.gov (United States)

    Liu, Rui; Chen, Ling; Jiang, Yanping; Zhou, Zhihua; Zou, Gen

    2015-01-01

    Filamentous fungi have wide applications in biotechnology. The CRISPR/Cas9 system is a powerful genome-editing method that facilitates genetic alterations of genomes in a variety of organisms. However, a genome-editing approach has not been reported in filamentous fungi. Here, we demonstrated the establishment of a CRISPR/Cas9 system in the filamentous fungus Trichoderma reesei by specific codon optimization and in vitro RNA transcription. It was shown that the CRISPR/Cas9 system was controllable and conditional through inducible Cas9 expression. This system generated site-specific mutations in target genes through efficient homologous recombination, even using short homology arms. This system also provided an applicable and promising approach to targeting multiple genes simultaneously. Our results illustrate that the CRISPR/Cas9 system is a powerful genome-manipulating tool for T. reesei and most likely for other filamentous fungal species, which may accelerate studies on functional genomics and strain improvement in these filamentous fungi.

  2. Interaction of Two Filament Channels of Different Chiralities

    CERN Document Server

    Joshi, Navin Chandra; Schmieder, Brigitte; Magara, Tetsuya; Moon, Young-Jae; Uddin, Wahab

    2016-01-01

    We present observations of interactions between the two filament channels of different chiralities and associated dynamics that occurred during 2014 April 18 -- 20. While two flux ropes of different helicity with parallel axial magnetic fields can only undergo a bounce interaction when they are brought together, the observations at the first glance show that the heated plasma is moving from one filament channel to the other. The SDO/AIA 171 A observations and the PFSS magnetic field extrapolation reveal the presence of fan-spine magnetic configuration over the filament channels with a null point located above them. Three different events of filament activations, partial eruptions, and associated filament channel interactions have been observed. The activation initiated in one filament channel seems to propagate along the neighbour filament channel. We believe that the activation and partial eruption of the filaments bring the field lines of flux ropes containing them closer to the null point and trigger the m...

  3. Assembly characteristics of plant keratin intermediate filaments in vitro

    Institute of Scientific and Technical Information of China (English)

    闵光伟; 杨澄; 佟向军; 翟中和

    1999-01-01

    After selective extraction and purification, plant keratin intermediate filaments were reassembled in vitro. Scanning tunneling microscope (STM) and transmission electron microscope (TEM) micrographs showed that acidic keratins and basic keratins can assemble into dimers and further into 10 nm filaments in vitro. In higher magnification images, it can be seen that fully assembled plant keratin intermediate filaments consist of several thinner filaments of 3 nm in diameter, which indicates the formation of protofilaments in the assembly processes. One of the explicit features of plant keratin intermediate filaments is a 24—25 nm periodic structural repeat alone the axis of beth the 10 nm filaments and protofilaments. The periodic repeat is one of the fundamental characteristic of all intermediate filaments, and demonstrates the half staggered arrangement of keratin molecules within the filaments.

  4. Filmes de ficção científica como mediadores de conceitos relativos ao meio ambiente Science fiction movies and environmental education: is it possible?

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Machado

    2008-01-01

    Full Text Available Muito se fala sobre o meio ambiente nos meios de comunicação e nas escolas, mas pouco se sabe sobre toda sua gama e envergadura. Confundem-se princípios ecológicos com o ensino generalizado do meio ambiente que cobre uma gama muito maior de conceitos e uma complexidade de relações urgentes e esquece-se que o estudo do meio ambiente deve tratar do todo envolvido pelo homem, do todo ao redor. Visões utópicas e distópicas a respeito desse tema estão presentes em alguns filmes de ficção científica feitos para cinema e televisão. Este texto analisa relações entre esses filmes e conceitos científicos relativos ao meio ambiente e aponta possibilidades de uso dos mesmos no ensino de ciência.The environment is one of the most important scientific subjects in the XXI century. Schools and the media talk about it all the time but they do not have enough knowledge. They forget that environmental studies must embrace the human beings and the whole world around them. Utopian and non-utopian conceptions about this subject are often presented in science fictions movies made for the cinema or for the television. This text discusses the relation between science fiction movies and scientific environmental concepts. In addition, it suggests a way to use the science in these kinds of films at school to develop science teaching.

  5. Mechanical heterogeneity favors fragmentation of strained actin filaments.

    Science.gov (United States)

    De La Cruz, Enrique M; Martiel, Jean-Louis; Blanchoin, Laurent

    2015-05-05

    We present a general model of actin filament deformation and fragmentation in response to compressive forces. The elastic free energy density along filaments is determined by their shape and mechanical properties, which were modeled in terms of bending, twisting, and twist-bend coupling elasticities. The elastic energy stored in filament deformation (i.e., strain) tilts the fragmentation-annealing reaction free-energy profile to favor fragmentation. The energy gradient introduces a local shear force that accelerates filament intersubunit bond rupture. The severing protein, cofilin, renders filaments more compliant in bending and twisting. As a result, filaments that are partially decorated with cofilin are mechanically heterogeneous (i.e., nonuniform) and display asymmetric shape deformations and energy profiles distinct from mechanically homogenous (i.e., uniform), bare actin, or saturated cofilactin filaments. The local buckling strain depends on the relative size of the compliant segment as well as the bending and twisting rigidities of flanking regions. Filaments with a single bare/cofilin-decorated boundary localize energy and force adjacent to the boundary, within the compliant cofilactin segment. Filaments with small cofilin clusters were predicted to fragment within the compliant cofilactin rather than at boundaries. Neglecting contributions from twist-bend coupling elasticity underestimates the energy density and gradients along filaments, and thus the net effects of filament strain to fragmentation. Spatial confinement causes compliant cofilactin segments and filaments to adopt higher deformation modes and store more elastic energy, thereby promoting fragmentation. The theory and simulations presented here establish a quantitative relationship between actin filament fragmentation thermodynamics and elasticity, and reveal how local discontinuities in filament mechanical properties introduced by regulatory proteins can modulate both the severing efficiency

  6. Flexible ferromagnetic filaments and the interface with biology

    Energy Technology Data Exchange (ETDEWEB)

    Erglis, K.; Belovs, M. [University of Latvia, Zellu 8, Riga LV-1002 (Latvia); Cebers, A. [University of Latvia, Zellu 8, Riga LV-1002 (Latvia)], E-mail: aceb@tesla.sal.lv

    2009-04-15

    Flexible ferromagnetic filaments are studied both theoretically and experimentally. Two main deformation modes of the filament at magnetic field inversion are theoretically described and observed experimentally by using DNA-linked chains of ferromagnetic particles. Anomalous orientation of ferromagnetic filaments perpendicular to AC field with a frequency which is high enough is predicted and confirmed experimentally. By experimental studies of magnetotactic bacteria it is demonstrated how these properties of ferromagnetic filaments may be used to measure the flexibility of the chain of magnetosomes.

  7. Architecture and fine structure of gill filaments in the brown mussel, perna perna

    CSIR Research Space (South Africa)

    Gregory, MA

    1996-10-01

    Full Text Available attention was paid to filament architecture, enervation of filaments, number and type of cells populating filament epithelia and variations in epithelial cell morphotogy and cilia ultra structure. Filament shape was maintained by thickened chitin...

  8. Correlative nanoscale imaging of actin filaments and their complexes.

    Science.gov (United States)

    Sharma, Shivani; Zhu, Huanqi; Grintsevich, Elena E; Reisler, Emil; Gimzewski, James K

    2013-07-01

    Actin remodeling is an area of interest in biology in which correlative microscopy can bring a new way to analyze protein complexes at the nanoscale. Advances in EM, X-ray diffraction, fluorescence, and single molecule techniques have provided a wealth of information about the modulation of the F-actin structure and its regulation by actin binding proteins (ABPs). Yet, there are technological limitations of these approaches to achieving quantitative molecular level information on the structural and biophysical changes resulting from ABPs interaction with F-actin. Fundamental questions about the actin structure and dynamics and how these determine the function of ABPs remain unanswered. Specifically, how local and long-range structural and conformational changes result in ABPs induced remodeling of F-actin needs to be addressed at the single filament level. Advanced, sensitive and accurate experimental tools for detailed understanding of ABP-actin interactions are much needed. This article discusses the current understanding of nanoscale structural and mechanical modulation of F-actin by ABPs at the single filament level using several correlative microscopic techniques, focusing mainly on results obtained by Atomic Force Microscopy (AFM) analysis of ABP-actin complexes.

  9. MUSE discovers perpendicular arcs in the inner filament of Centaurus A

    Science.gov (United States)

    Hamer, S.; Salomé, P.; Combes, F.; Salomé, Q.

    2015-03-01

    Context. Evidence of active galactic nuclei (AGN) interaction with the intergalactic medium is observed in some galaxies and many cool core clusters. Radio jets are suspected to dig large cavities into the surrounding gas. In most cases, very large optical filaments (several kpc) are also seen all around the central galaxy. The origin of these filaments is still not understood. Star-forming regions are sometimes observed inside the filaments and are interpreted as evidence of positive feedback (AGN-triggered star formation). Aims: Centaurus A is a very nearby galaxy with huge optical filaments aligned with the AGN radio-jet direction. Here, we searched for line ratio variations along the filaments, kinematic evidence of shock-broadend line widths, and large-scale dynamical structures. Methods: We observed a 1' × 1' region around the so-called inner filament of Cen A with the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT) during the Science Verification period. Results: (i) The brightest lines detected are the Hαλ6562.8, [NII]λ6583, [OIII]λ4959+5007 and [SII]λ6716+6731. MUSE shows that the filaments are made of clumpy structures inside a more diffuse medium aligned with the radio-jet axis. We find evidence of shocked shells surrounding the star-forming clumps from the line profiles, suggesting that the star formation is induced by shocks. The clump line ratios are best explained by a composite of shocks and star formation illuminated by a radiation cone from the AGN. (ii) We also report a previously undetected large arc-like structure: three streams running perpendicular to the main filament; they are kinematically, morphologically, and excitationally distinct. The clear difference in the excitation of the arcs and clumps suggests that the arcs are very likely located outside of the radiation cone and match the position of the filament only in projection. The three arcs are thus most consistent with neutral material swept along by a

  10. Driven transport on open filaments with interfilament switching processes

    Science.gov (United States)

    Ghosh, Subhadip; Pagonabarraga, Ignacio; Muhuri, Sudipto

    2017-02-01

    We study a two-filament driven lattice gas model with oppositely directed species of particles moving on two parallel filaments with filament-switching processes and particle inflow and outflow at filament ends. The filament-switching process is correlated with the occupation number of the adjacent site such that particles switch filaments with finite probability only when oppositely directed particles meet on the same filament. This model mimics some of the coarse-grained features observed in context of microtubule-(MT) based intracellular transport, wherein cellular cargo loaded and off-loaded at filament ends are transported on multiple parallel MT filaments and can switch between the parallel microtubule filaments. We focus on a regime where the filaments are weakly coupled, such that filament-switching rate of particles scale inversely as the length of the filament. We find that the interplay of (off-) loading processes at the boundaries and the filament-switching process of particles leads to some distinctive features of the system. These features includes occurrence of a variety of phases in the system with inhomogeneous density profiles including localized density shocks, density difference across the filaments, and bidirectional current flows in the system. We analyze the system by developing a mean field (MF) theory and comparing the results obtained from the MF theory with the Monte Carlo (MC) simulations of the dynamics of the system. We find that the steady-state density and current profiles of particles and the phase diagram obtained within the MF picture matches quite well with MC simulation results. These findings maybe useful for studying multifilament intracellular transport.

  11. The effects of a low-intensity red laser on bacterial growth, filamentation and plasmid DNA

    Science.gov (United States)

    Roos, C.; Santos, J. N.; Guimarães, O. R.; Geller, M.; Paoli, F.; Fonseca, A. S.

    2013-07-01

    Exposure of nonphotosynthesizing microorganisms to light could increase cell division in cultures, a phenomenon denominated as biostimulation. However, data concerning the importance of the genetic characteristics of cells on this effect are as yet scarce. The aim of this work was to evaluate the effects of a low-intensity red laser on the growth, filamentation and plasmids in Escherichia coli cells proficient and deficient in DNA repair. E. coli cultures were exposed to a laser (658 nm, 10 mW, 1 and 8 J cm-2) to study bacterial growth and filamentation. Also, bacterial cultures hosting pBSK plasmids were exposed to the laser to study DNA topological forms from the electrophoretic profile in agarose gels. Data indicate the low-intensity red laser: (i) had no effect on the growth of E. coli wild type and exonuclease III deficient cells; (ii) induced bacterial filamentation, (iii) led to no alteration in the electrophoretic profile of plasmids from exonuclease III deficient cells, but plasmids from wild type cells were altered. A low-intensity red laser at the low fluences used in phototherapy has no effect on growth, but induces filamentation and alters the topological forms of plasmid DNA in E. coli cultures depending on the DNA repair mechanisms.

  12. L'ús de gràfics interactius en Excel per a facilitar la comprensió de conceptes bàsics d'Estadística

    Directory of Open Access Journals (Sweden)

    Vicente Coll Serrano

    2010-12-01

    Full Text Available En aquest treball es mostra una sèrie d’aplicacions realitzades en la fulla de càlcul Excel que pretenen recolzar la docència de l’assignatura de Estadística. Concretament, es mostren diversos gràfics interactius que persegueixen reforçar el contingut desenvolupat en una classe i facilitar la comprensió conceptual per part de l’estudiant del principals aspectes analitzats. Els estudiants poden relacionar, fàcilment, la teoria amb una representació gràfica dotada d’un cert grau de interactivitat.

  13. L'ús de gràfics interactius en Excel per a facilitar la comprensió de conceptes bàsics d'Estadística

    OpenAIRE

    Vicente Coll Serrano; Olga Blasco Blasco

    2010-01-01

    En aquest treball es mostra una sèrie d’aplicacions realitzades en la fulla de càlcul Excel que pretenen recolzar la docència de l’assignatura de Estadística. Concretament, es mostren diversos gràfics interactius que persegueixen reforçar el contingut desenvolupat en una classe i facilitar la comprensió conceptual per part de l’estudiant del principals aspectes analitzats. Els estudiants poden relacionar, fàcilment, la teoria amb una representació gràfica dotada d’un cert grau de interactivit...

  14. Intergalactic Filaments as Isothermal Gas Cylinders

    CERN Document Server

    Harford, A Gayler

    2010-01-01

    Using a cosmological simulation at redshift 5, we find that the baryon-rich cores of intergalactic filaments radiating from galaxies commonly form isothermal gas cylinders. The central gas density is typically about 500 times the cosmic mean total density, and the temperature is typically 1-2 times 10^4 K, just above the Lyman alpha cooling floor. These findings argue that the hydrodynamic properties of the gas are more important than the dark matter in determining the structure. Filaments form a major pipeline for the transport of gas into the centers of galaxies. Since the temperature and ionization state of the gas completely determine the mass per unit length of an isothermal gas cylinder, our findings suggest a constraint upon gas transport into galaxies by this mechanism.

  15. Morgellons disease: a filamentous borrelial dermatitis

    Science.gov (United States)

    Middelveen, Marianne J; Stricker, Raphael B

    2016-01-01

    Morgellons disease (MD) is a dermopathy characterized by multicolored filaments that lie under, are embedded in, or project from skin. Although MD was initially considered to be a delusional disorder, recent studies have demonstrated that the dermopathy is associated with tickborne infection, that the filaments are composed of keratin and collagen, and that they result from proliferation of keratinocytes and fibroblasts in epithelial tissue. Culture, histopathological and molecular evidence of spirochetal infection associated with MD has been presented in several published studies using a variety of techniques. Spirochetes genetically identified as Borrelia burgdorferi sensu stricto predominate as the infective agent in most of the Morgellons skin specimens studied so far. Other species of Borrelia including Borrelia garinii, Borrelia miyamotoi, and Borrelia hermsii have also been detected in skin specimens taken from MD patients. The optimal treatment for MD remains to be determined. PMID:27789971

  16. Morgellons disease: a filamentous borrelial dermatitis.

    Science.gov (United States)

    Middelveen, Marianne J; Stricker, Raphael B

    2016-01-01

    Morgellons disease (MD) is a dermopathy characterized by multicolored filaments that lie under, are embedded in, or project from skin. Although MD was initially considered to be a delusional disorder, recent studies have demonstrated that the dermopathy is associated with tickborne infection, that the filaments are composed of keratin and collagen, and that they result from proliferation of keratinocytes and fibroblasts in epithelial tissue. Culture, histopathological and molecular evidence of spirochetal infection associated with MD has been presented in several published studies using a variety of techniques. Spirochetes genetically identified as Borrelia burgdorferi sensu stricto predominate as the infective agent in most of the Morgellons skin specimens studied so far. Other species of Borrelia including Borrelia garinii, Borrelia miyamotoi, and Borrelia hermsii have also been detected in skin specimens taken from MD patients. The optimal treatment for MD remains to be determined.

  17. Merging and energy exchange between optical filaments

    Energy Technology Data Exchange (ETDEWEB)

    Georgieva, D. A., E-mail: dgeorgieva@tu-sofia.bg [Faculty of Applied Mathematics and Computer Science, Technical University of Sofia, 8 Kliment Ohridski Blvd., 1000 Sofia (Bulgaria); Kovachev, L. M. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradcko Chaussee Blvd., 1784 Sofia (Bulgaria)

    2015-10-28

    We investigate nonlinear interaction between collinear femtosecond laser pulses with power slightly above the critical for self-focusing P{sub cr} trough the processes of cross-phase modulation (CPM) and degenerate four-photon parametric mixing (FPPM). When there is no initial phase difference between the pulses we observe attraction between pulses due to CPM. The final result is merging between the pulses in a single filament with higher power. By method of moments it is found that the attraction depends on the distance between the pulses and has potential character. In the second case we study energy exchange between filaments. This process is described through FPPM scheme and requests initial phase difference between the waves.

  18. Laser filamentation mathematical methods and models

    CERN Document Server

    Lorin, Emmanuel; Moloney, Jerome

    2016-01-01

    This book is focused on the nonlinear theoretical and mathematical problems associated with ultrafast intense laser pulse propagation in gases and in particular, in air. With the aim of understanding the physics of filamentation in gases, solids, the atmosphere, and even biological tissue, specialists in nonlinear optics and filamentation from both physics and mathematics attempt to rigorously derive and analyze relevant non-perturbative models. Modern laser technology allows the generation of ultrafast (few cycle) laser pulses, with intensities exceeding the internal electric field in atoms and molecules (E=5x109 V/cm or intensity I = 3.5 x 1016 Watts/cm2 ). The interaction of such pulses with atoms and molecules leads to new, highly nonlinear nonperturbative regimes, where new physical phenomena, such as High Harmonic Generation (HHG), occur, and from which the shortest (attosecond - the natural time scale of the electron) pulses have been created. One of the major experimental discoveries in this nonlinear...

  19. In situ ellipsometric study of surface immobilization of flagellar filaments

    Energy Technology Data Exchange (ETDEWEB)

    Kurunczi, S., E-mail: kurunczi@mfa.kfki.hu [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Nemeth, A.; Huelber, T. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Kozma, P. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Department of Nanotechnology, Research Institute of Chemical and Process Engineering, Faculty of Information Technology, University of Pannonia, Egyetem u. 10, Veszprem, H-8200 (Hungary); Petrik, P. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Jankovics, H. [Department of Nanotechnology, Research Institute of Chemical and Process Engineering, Faculty of Information Technology, University of Pannonia, Egyetem u. 10, Veszprem, H-8200 (Hungary); Sebestyen, A. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Department of Nanotechnology, Research Institute of Chemical and Process Engineering, Faculty of Information Technology, University of Pannonia, Egyetem u. 10, Veszprem, H-8200 (Hungary); Vonderviszt, F. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Department of Nanotechnology, Research Institute of Chemical and Process Engineering, Faculty of Information Technology, University of Pannonia, Egyetem u. 10, Veszprem, H-8200 (Hungary); Institute of Enzymology, Karolina ut 29-33, Budapest, H-1113 (Hungary); and others

    2010-10-15

    Protein filaments composed of thousands of subunits are promising candidates as sensing elements in biosensors. In this work in situ spectroscopic ellipsometry is applied to monitor the surface immobilization of flagellar filaments. This study is the first step towards the development of layers of filamentous receptors for sensor applications. Surface activation is performed using silanization and a subsequent glutaraldehyde crosslinking. Structure of the flagellar filament layers immobilized on activated and non-activated Si wafer substrates is determined using a two-layer effective medium model that accounted for the vertical density distribution of flagellar filaments with lengths of 300-1500 nm bound to the surface. The formation of the first interface layer can be explained by the multipoint covalent attachment of the filaments, while the second layer is mainly composed of tail pinned filaments floating upwards with the free parts. As confirmed by atomic force microscopy, covalent immobilization resulted in an increased surface density compared to absorption.

  20. Motion of current filaments in avalanching PIN diodes

    Science.gov (United States)

    Xingrong, Ren; Changchun, Chai; Zhenyang, Ma; Yintang, Yang; Liping, Qiao; Chunlei, Shi; Lihua, Ren

    2013-04-01

    The motion of current filaments in avalanching PIN diodes has been investigated in this paper by 2D transient numerical simulations. The simulation results show that the filament can move along the length of the PIN diode back and forth when the self-heating effect is considered. The voltage waveform varies periodically due to the motion of the filament. The filament motion is driven by the temperature gradient in the filament due to the negative temperature dependence of the impact ionization rates. Contrary to the traditional understanding that current filamentation is a potential cause of thermal destruction, it is shown in this paper that the thermally-driven motion of current filaments leads to the homogenization of temperature in the diode and is expected to have a positive influence on the failure threshold of the PIN diode.

  1. COMPLEX FLARE DYNAMICS INITIATED BY A FILAMENT–FILAMENT INTERACTION

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Chunming; McAteer, R. T. James [Department of Astronomy, New Mexico State University, NM 88003 (United States); Liu, Rui [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei 230026 (China); Alexander, David [Department of Physics and Astronomy, Rice University, TX 77005 (United States); Sun, Xudong, E-mail: czhu@nmsu.edu [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States)

    2015-11-01

    We report on an eruption involving a relatively rare filament–filament interaction on 2013 June 21, observed by SDO and STEREO-B. The two filaments were separated in height with a “double-decker” configuration. The eruption of the lower filament began simultaneously with a descent of the upper filament, resulting in a convergence and direct interaction of the two filaments. The interaction was accompanied by the heating of surrounding plasma and an apparent crossing of a loop-like structure through the upper filament. The subsequent coalescence of the filaments drove a bright front ahead of the erupting structures. The whole process was associated with a C3.0 flare followed immediately by an M2.9 flare. Shrinking loops and descending dark voids were observed during the M2.9 flare at different locations above a C-shaped flare arcade as part of the energy release, giving us unique insight into the flare dynamics.

  2. The Dark Matter filament between Abell 222/223

    Science.gov (United States)

    Dietrich, Jörg P.; Werner, Norbert; Clowe, Douglas; Finoguenov, Alexis; Kitching, Tom; Miller, Lance; Simionescu, Aurora

    2016-10-01

    Weak lensing detections and measurements of filaments have been elusive for a long time. The reason is that the low density contrast of filaments generally pushes the weak lensing signal to unobservably low scales. To nevertheless map the dark matter in filaments exquisite data and unusual systems are necessary. SuprimeCam observations of the supercluster system Abell 222/223 provided the required combination of excellent seeing images and a fortuitous alignment of the filament with the line-of-sight. This boosted the lensing signal to a detectable level and led to the first weak lensing mass measurement of a large-scale structure filament. The filament connecting Abell 222 and Abell 223 is now the only one traced by the galaxy distribution, dark matter, and X-ray emission from the hottest phase of the warm-hot intergalactic medium. The combination of these data allows us to put the first constraints on the hot gas fraction in filaments.

  3. Topological Aspect of Knotted Vortex Filaments in Excitable Media

    Institute of Scientific and Technical Information of China (English)

    REN Ji-Rong; ZHU Tao; DUAN Yi-Shi

    2008-01-01

    Scroll waves exist ubiquitously in three-dimensional excitable media.The rotation centre can be regarded as a topological object called the vortex filament.In three-dimensional space,the vortex filaments usually form closed loops,and can be even linked and knotted.We give a rigorous topological description of knotted vortex filaments.By using the Φ-mapping topological current theory,we rewrite the topological current form of the charge density of vortex filaments,and using this topological current we reveal that the Hopf invariant of vortex filaments is just the sum of the linking and self-linking numbers of the knotted vortex filaments.We think that the precise expression of the Hopf invariant may imply a new topological constraint on knotted vortex filaments.

  4. Formation of magnetic filaments: A kinetic study

    Science.gov (United States)

    Martínez-Pedrero, F.; Tirado-Miranda, M.; Schmitt, A.; Callejas-Fernández, J.

    2007-07-01

    In order to form magnetic filaments or chains, aqueous suspensions of superparamagnetic colloidal particles were aggregated under the action of an external magnetic field in the presence of different amounts of an indifferent 1:1 electrolyte (KBr). This allowed the influence of the anisotropic magnetic and isotropic electrostatic interactions on the aggregation behavior of these electric double-layered magnetic particles to be studied. Dynamic light scattering was used for monitoring the average diffusion coefficient of the magnetic filaments formed. Hydrodynamic equations were employed for obtaining the average chain lengths from the experimental mean diffusion coefficients. The results show that, for the same exposure time to the magnetic field, the average filament size is monotonously related to the amount of electrolyte added. The chain growth behavior was found to follow a power law with a similar exponent for all electrolyte concentrations used in this work. The time evolution of the average filament size can be rescaled such that all the curves collapse on a single master curve. Since the electrolyte added does not have any effect on the scaling behavior, the mechanism of aggregation seems to be completely controlled by the dipolar interaction. However, electrolyte addition not only controls the range of the total interaction between the particles, but also enhances the growth rate of the aggregation process. Taking into account the anisotropic character of these aggregation processes we propose a kernel that depends explicitly on the range of the dipolar interaction. The corresponding solutions of the Smoluchowski equation combined with theoretical models for the diffusion and light scattering by rigid rods reproduce the measured time evolution of the average perpendicular aggregate diffusion coefficient quite satisfactorily.

  5. Cold Milky Way HI Gas in Filaments

    Science.gov (United States)

    Kalberla, P. M. W.; Kerp, J.; Haud, U.; Winkel, B.; Ben Bekhti, N.; Flöer, L.; Lenz, D.

    2016-04-01

    We investigate data from the Galactic Effelsberg-Bonn H i Survey, supplemented with data from the third release of the Galactic All Sky Survey (GASS III) observed at Parkes. We explore the all-sky distribution of the local Galactic H i gas with | {v}{{LSR}}| \\lt 25 km s-1 on angular scales of 11‧-16‧. Unsharp masking is applied to extract small-scale features. We find cold filaments that are aligned with polarized dust emission and conclude that the cold neutral medium (CNM) is mostly organized in sheets that are, because of projection effects, observed as filaments. These filaments are associated with dust ridges, aligned with the magnetic field measured on the structures by Planck at 353 GHz. The CNM above latitudes | b| \\gt 20^\\circ is described by a log-normal distribution, with a median Doppler temperature TD = 223 K, derived from observed line widths that include turbulent contributions. The median neutral hydrogen (H i) column density is NH i ≃ 1019.1 cm-2. These CNM structures are embedded within a warm neutral medium with NH i ≃ 1020 cm-2. Assuming an average distance of 100 pc, we derive for the CNM sheets a thickness of ≲0.3 pc. Adopting a magnetic field strength of Btot = (6.0 ± 1.8) μG, proposed by Heiles & Troland, and assuming that the CNM filaments are confined by magnetic pressure, we estimate a thickness of 0.09 pc. Correspondingly, the median volume density is in the range 14 ≲ n ≲ 47 cm-3. The authors thank the Deutsche Forschungsgemeinschaft (DFG) for support under grant numbers KE757/11-1, KE757/7-3, KE757/7-2, KE757/7-1, and BE4823/1-1.

  6. [Elimination of microscopic filamentous fungi with disinfectants].

    Science.gov (United States)

    Laciaková, A; Laciak, V

    1994-01-01

    The antifungal effectivity of three single-component (Persteril, Septonex, Glutaraldehyd) and of three combined (Persteril+Septonex, Pesteril+Glutaraldehyd, Glutaraldehyd+Septonex) commercially available disinfectants was monitored by the diffuse method on five fen of the microscopic filamentous fungi Aspergillus alternata, Aspergillus niger, Mucor fragillis, Fusarium moniliforme, Penicillium glabrum. The highest antifungal activity was observed in 2% Persteril while 2% Persteril + 1% Septonex were the most effective among the combined disinfectants. M. fragilis was the most resistant strain.

  7. On viscoelastic instability in polymeric filaments

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Hassager, Ole

    1999-01-01

    The 3D Lagrangian Integral Method is used to simulate the effects of surface tension on the viscoelastic end-plate instability, occuring in the rapid extension of some polymeric filaments between parallel plates. It is shovn that the surface tension delays the onset of the instability. Furthermore...... it is demonstrated that surface tension plays a key role in the selection of the most unstable mode...

  8. The tidal filament of NGC 4660

    CERN Document Server

    Kemp, S N; Marquez-Lugo, R A; Zepeda-Garcia, D; Franco-Hernandez, R; Nigoche-Netro, A; Ramos-Larios, G; Navarro, S G; Corral, L J

    2016-01-01

    NGC 4660, in the Virgo cluster, is a well-studied elliptical galaxy which has a strong disk component (D/T about 0.2-0.3). The central regions including the disk component have stellar populations with ages about 12-13 Gyr from SAURON studies. However we report the discovery of a long narrow tidal filament associated with the galaxy in deep co-added Schmidt plate images and deep CCD frames, implying that the galaxy has undergone a tidal interaction and merger within the last few Gyr. The relative narrowness of the filament implies a wet merger with at least one spiral galaxy involved, but the current state of the system has little evidence for this. However a 2-component photometric fit using GALFIT shows much bluer B-V colours for the disk component than for the elliptical component, which may represent a residual trace of enhanced star formation in the disk caused by the interaction 1-2 Gyr ago. There are brighter concentrations within the filament which resemble Tidal Dwarf Galaxies, although they are at l...

  9. Mechanical Properties of Intermediate Filament Proteins.

    Science.gov (United States)

    Charrier, Elisabeth E; Janmey, Paul A

    2016-01-01

    Purified intermediate filament (IF) proteins can be reassembled in vitro to produce polymers closely resembling those found in cells, and these filaments form viscoelastic gels. The cross-links holding IFs together in the network include specific bonds between polypeptides extending from the filament surface and ionic interactions mediated by divalent cations. IF networks exhibit striking nonlinear elasticity with stiffness, as quantified by shear modulus, increasing an order of magnitude as the networks are deformed to large strains resembling those that soft tissues undergo in vivo. Individual IFs can be stretched to more than two or three times their resting length without breaking. At least 10 different rheometric methods have been used to quantify the viscoelasticity of IF networks over a wide range of timescales and strain magnitudes. The mechanical roles of different classes of cytoplasmic IFs on mesenchymal and epithelial cells in culture have also been studied by an even wider range of microrheological methods. These studies have documented the effects on cell mechanics when IFs are genetically or pharmacologically disrupted or when normal or mutant IF proteins are exogenously expressed in cells. Consistent with in vitro rheology, the mechanical role of IFs is more apparent as cells are subjected to larger and more frequent deformations.

  10. Oscillating Filaments. I. Oscillation and Geometrical Fragmentation

    Science.gov (United States)

    Gritschneder, Matthias; Heigl, Stefan; Burkert, Andreas

    2017-01-01

    We study the stability of filaments in equilibrium between gravity and internal as well as external pressure using the grid-based AMR code RAMSES. A homogeneous, straight cylinder below a critical line mass is marginally stable. However, if the cylinder is bent, such as with a slight sinusoidal perturbation, an otherwise stable configuration starts to oscillate, is triggered into fragmentation, and collapses. This previously unstudied behavior allows a filament to fragment at any given scale, as long as it has slight bends. We call this process “geometrical fragmentation.” In our realization, the spacing between the cores matches the wavelength of the sinusoidal perturbation, whereas up to now, filaments were thought to be only fragmenting on the characteristic scale set by the mass-to-line ratio. Using first principles, we derive the oscillation period as well as the collapse timescale analytically. To enable a direct comparison with observations, we study the line-of-sight velocity for different inclinations. We show that the overall oscillation pattern can hide the infall signature of cores.

  11. A first approach to filament dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Silva, P E S; De Abreu, F Vistulo; Dias, R G [Department of Physics, University of Aveiro (Portugal); Simoes, R, E-mail: fva@ua.p [I3N-Institute for Nanostructures, Nanomodelling and Nanofabrication (Portugal)

    2010-11-15

    Modelling elastic filament dynamics is a topic of high interest due to the wide range of applications. However, it has reached a high level of complexity in the literature, making it unaccessible to a beginner. In this paper we explain the main steps involved in the computational modelling of the dynamics of an elastic filament. We first derive equations governing the dynamics of an elastic lament suitable for a computer simulation implementation. The derivation starts from the relation between forces and potential energy in conservative systems in order to derive the equation of motion of any bead in the filament. Only two-dimensional movements are considered, but extensions to three dimensions can follow similar lines. Suggestions for computer implementations are provided in Matlab as well as an example of application related to the generation of musical sounds. This example allows a critical analysis of the numerical results obtained using a cross-disciplinary perspective. Since derivations start from basic physics equations, use simple calculus and computational implementations are straightforward, this paper proposes a different approach to introduce simple molecular dynamics simulations or animations of real systems in undergraduate elasticity or computer modelling courses.

  12. Modelling the chemistry of star forming filaments

    CERN Document Server

    Seifried, D

    2015-01-01

    We present simulations of star forming filaments incorporating - to our knowledge - the largest chemical network used to date on-the-fly in a 3D-MHD simulation. The network contains 37 chemical species and about 300 selected reaction rates. For this we use the newly developed package KROME (Grassi et al. 2014). We combine the KROME package with an algorithm which allows us to calculate the column density and attenuation of the interstellar radiation field necessary to properly model heating and ionisation rates. Our results demonstrate the feasibility of using such a complex chemical network in 3D-MHD simulations on modern supercomputers. We perform simulations with different strengths of the interstellar radiation field and the cosmic ray ionisation rate. We find that towards the centre of the filaments there is gradual conversion of hydrogen from H^+ over H to H_2 as well as of C^+ over C to CO. Moreover, we find a decrease of the dust temperature towards the centre of the filaments in agreement with recent...

  13. Herpesviruses and Intermediate Filaments: Close Encounters with the Third Type

    Directory of Open Access Journals (Sweden)

    Laura Hertel

    2011-07-01

    Full Text Available Intermediate filaments (IF are essential to maintain cellular and nuclear integrity and shape, to manage organelle distribution and motility, to control the trafficking and pH of intracellular vesicles, to prevent stress-induced cell death, and to support the correct distribution of specific proteins. Because of this, IF are likely to be targeted by a variety of pathogens, and may act in favor or against infection progress. As many IF functions remain to be identified, however, little is currently known about these interactions. Herpesviruses can infect a wide variety of cell types, and are thus bound to encounter the different types of IF expressed in each tissue. The analysis of these interrelationships can yield precious insights into how IF proteins work, and into how viruses have evolved to exploit these functions. These interactions, either known or potential, will be the focus of this review.

  14. Increased Filamentous Growth of Candida albicans in Simulated Microgravity

    Institute of Scientific and Technical Information of China (English)

    Sara D. Altenburg; Sheila M. Nielsen-Preiss; Linda E. Hyman

    2008-01-01

    Knowledge of simulated microgravity (SMG)-induced changes in the pathogenicity of microorganisms is important for success of long-term spaceflight. In a previous study using the high aspect ratio vessel bioreactor, we showed that the yeast species Saccharomyces cerevisiae underwent a significant phenotypic response when grown in modeled microgravity, which was reflected in the analysis of gene expression profiles. In this study, we establish that Candida albicans responds to SMG in a similar fashion, demonstrating that there is a conserved response among yeast to this environmental stress. We also report that the growth of C. albicans in SMG results in a morphogenic switch that is consistent with enhanced pathogenicity. Specifically, we observed an increase in filamentous forms of the organism and accompanying changes in the expression of two genes associated with the yeasthyphal transition. The morphological response may have significant implications for astronauts' safety, as the fungal pathogen may become more virulent during spaceflight.

  15. Cartogramas: ficção angolana e o reforço de espaços e paisagens culturais

    Directory of Open Access Journals (Sweden)

    Laura Padilha

    2005-06-01

    Full Text Available O artigo propõe a forma de projeção gráfica do cartograma para por ela pensar a ficção angolana produzida nos anos 1990 e no início do século XXI. Considerando ser o cartograma uma forma de, por imagens ou traços, reforçar um tipo de fenômeno geográfico, a leitura se vale dessa imagem para privilegiar as representações das paisagens e espaços culturais angolanos, vendo-os como um processo de investimento dos ficcionistas em suas histórias locais, para, por tal investimento, reforçar a própria diferença cultural.Enfocando la proyección gráfica de cartogramas postales, este artículo propone reflexionar sobre la producción ficcional de Angola a partir de los años 90 del siglo XX hasta los primeros años del XXI. Por ser el cartograma una forma de reforzar, sea con la imágen, sea con el diseño, un tipo de fenómeno geográfico, su lectura se sostiene sobre esta imagen para privilegiar representaciones de paisajes y espacios culturales angolanos, recurso éste reiterado por ficcionistas para registrar sus historias locales y para reforzar su propia diferencia cultural.This article elaborates on the graphic form of projection of the cartogram in order to think, through it, Angolan fiction of the 90s and the beginnings of the XXI century. Considering the cartogram as a way of highlighting by means of images or sketches a given geographical phenomenon, the reading herein proposed makes use of this image to call attention to the representation of Angolan landscapes and cultural spaces, viewing them as a process of investment on the part of fiction writers in their local histories in order to thereby emphasize their own cultural difference.

  16. Withaferin a alters intermediate filament organization, cell shape and behavior.

    Directory of Open Access Journals (Sweden)

    Boris Grin

    Full Text Available Withaferin A (WFA is a steroidal lactone present in Withania somnifera which has been shown in vitro to bind to the intermediate filament protein, vimentin. Based upon its affinity for vimentin, it has been proposed that WFA can be used as an anti-tumor agent to target metastatic cells which up-regulate vimentin expression. We show that WFA treatment of human fibroblasts rapidly reorganizes vimentin intermediate filaments (VIF into a perinuclear aggregate. This reorganization is dose dependent and is accompanied by a change in cell shape, decreased motility and an increase in vimentin phosphorylation at serine-38. Furthermore, vimentin lacking cysteine-328, the proposed WFA binding site, remains sensitive to WFA demonstrating that this site is not required for its cellular effects. Using analytical ultracentrifugation, viscometry, electron microscopy and sedimentation assays we show that WFA has no effect on VIF assembly in vitro. Furthermore, WFA is not specific for vimentin as it disrupts the cellular organization and induces perinuclear aggregates of several other IF networks comprised of peripherin, neurofilament-triplet protein, and keratin. In cells co-expressing keratin IF and VIF, the former are significantly less sensitive to WFA with respect to inducing perinuclear aggregates. The organization of microtubules and actin/microfilaments is also affected by WFA. Microtubules become wavier and sparser and the number of stress fibers appears to increase. Following 24 hrs of exposure to doses of WFA that alter VIF organization and motility, cells undergo apoptosis. Lower doses of the drug do not kill cells but cause them to senesce. In light of our findings that WFA affects multiple IF systems, which are expressed in many tissues of the body, caution is warranted in its use as an anti-cancer agent, since it may have debilitating organism-wide effects.

  17. TIRF microscopy analysis of human Cof1, Cof2, and ADF effects on actin filament severing and turnover.

    Science.gov (United States)

    Chin, Samantha M; Jansen, Silvia; Goode, Bruce L

    2016-04-24

    Dynamic remodeling and turnover of cellular actin networks requires actin filament severing by actin-depolymerizing factor (ADF)/Cofilin proteins. Mammals express three different ADF/Cofilins (Cof1, Cof2, and ADF), and genetic studies suggest that in vivo they perform both overlapping and unique functions. To gain mechanistic insights into their different roles, we directly compared their G-actin and F-actin binding affinities, and quantified the actin filament severing activities of human Cof1, Cof2, and ADF using in vitro total internal reflection fluorescence microscopy. All three ADF/Cofilins had similar affinities for G-actin and F-actin. However, Cof2 and ADF severed filaments much more efficiently than Cof1 at both lower and higher concentrations and using either muscle or platelet actin. Furthermore, Cof2 and ADF were more effective than Cof1 in promoting "enhanced disassembly" when combined with actin disassembly co-factors Coronin-1B and actin-interacting protein 1 (AIP1), and these differences were observed on both preformed and actively growing filaments. To probe the mechanism underlying these differences, we used multi-wavelength total internal reflection fluorescence microscopy to directly observe Cy3-Cof1 and Cy3-Cof2 interacting with actin filaments in real time during severing. Cof1 and Cof2 each bound to filaments with similar kinetics, yet Cof2 induced severing much more rapidly than Cof1, decreasing the time interval between initial binding on a filament and severing at the same location. These differences in ADF/Cofilin activities and mechanisms may be used in cells to tune filament turnover rates, which can vary widely for different actin structures.

  18. Patterns of molecular motors that guide and sort filaments.

    Science.gov (United States)

    Rupp, Beat; Nédélec, François

    2012-11-21

    Molecular motors can be immobilized to transport filaments and loads that are attached to these filaments inside a nano-device. However, if motors are distributed uniformly over a flat surface, the motility is undirected, and the filaments move equally in all directions. For many applications it is important to control the direction in which the filaments move, and two strategies have been explored to achieve this: applying external forces and confining the filaments inside channels. In this article, we discuss a third strategy in which the topography of the sample remains flat, but the motors are distributed non-uniformly over the surface. Systems of filaments and patterned molecular motors were simulated using a stochastic engine that included Brownian motion and filament bending elasticity. Using an evolutionary algorithm, patterns were optimized for their capacity to precisely control the paths of the filaments. We identified patterns of motors that could either direct the filaments in a particular direction, or separate short and long filaments. These functionalities already exceed what has been achieved with confinement. The patterns are composed of one or two types of motors positioned in lines or along arcs and should be easy to manufacture. Finally, these patterns can be easily combined into larger designs, allowing one to precisely control the motion of microscopic objects inside a device.

  19. Connectin filaments in stretched skinned fibers of frog skeletal muscle

    Science.gov (United States)

    1984-01-01

    Indirect immunofluorescence microscopy of highly stretched skinned frog semi-tendinous muscle fibers revealed that connectin, an elastic protein of muscle, is located in the gap between actin and myosin filaments and also in the region of myosin filaments except in their centers. Electron microscopic observations showed that there were easily recognizable filaments extending from the myosin filaments to the I band region and to Z lines in the myofibrils treated with antiserum against connectin. In thin sections prepared with tannic acid, very thin filaments connected myosin filaments to actin filaments. These filaments were also observed in myofibrils extracted with a modified Hasselbach-Schneider solution (0.6 M KCl, 0.1 M phosphate buffer, pH 6.5, 2 mM ATP, 2 mM MgCl2, and 1 mM EGTA) and with 0.6 M Kl. SDS PAGE revealed that connectin (also called titin) remained in extracted myofibrils. We suggest that connectin filaments play an important role in the generation of tension upon passive stretch. A scheme of the cytoskeletal structure of myofibrils of vertebrate skeletal muscle is presented on the basis of our present information of connectin and intermediate filaments. PMID:6384237

  20. Degradation of thin tungsten filaments at high temperature in HWCVD

    Energy Technology Data Exchange (ETDEWEB)

    Frigeri, P.A., E-mail: pfrigeri@phys.ethz.ch; Nos, O.; Bertomeu, J.

    2015-01-30

    The degradation of the filaments is usually studied by checking the silicidation or carbonization status of the refractory metal used as catalysts, and their effects on the structural stability of the filaments. In this paper, it will be shown that the catalytic stability of a filament heated at high temperature is much shorter than its structural lifetime. The electrical resistance of a thin tungsten filament and the deposition rate of the deposited thin film have been monitored during the filament aging. It has been found that the deposition rate drops drastically once the quantity of dissolved silicon in the tungsten reaches the solubility limit and the silicides start precipitating. This manuscript concludes that the catalytic stability is only guaranteed for a short time and that for sufficiently thick filaments it does not depend on the filament radius. - Highlights: • A model for the electrical resistance of a tungsten filament during aging is presented. • Catalytic activity of the filament drops when W5Si3 precipitation takes place at its surface. • The catalytic stability of the filament does not depend on its radius in most practical situations.

  1. Tropomyosin - master regulator of actin filament function in the cytoskeleton.

    Science.gov (United States)

    Gunning, Peter W; Hardeman, Edna C; Lappalainen, Pekka; Mulvihill, Daniel P

    2015-08-15

    Tropomyosin (Tpm) isoforms are the master regulators of the functions of individual actin filaments in fungi and metazoans. Tpms are coiled-coil parallel dimers that form a head-to-tail polymer along the length of actin filaments. Yeast only has two Tpm isoforms, whereas mammals have over 40. Each cytoskeletal actin filament contains a homopolymer of Tpm homodimers, resulting in a filament of uniform Tpm composition along its length. Evidence for this 'master regulator' role is based on four core sets of observation. First, spatially and functionally distinct actin filaments contain different Tpm isoforms, and recent data suggest that members of the formin family of actin filament nucleators can specify which Tpm isoform is added to the growing actin filament. Second, Tpms regulate whole-organism physiology in terms of morphogenesis, cell proliferation, vesicle trafficking, biomechanics, glucose metabolism and organ size in an isoform-specific manner. Third, Tpms achieve these functional outputs by regulating the interaction of actin filaments with myosin motors and actin-binding proteins in an isoform-specific manner. Last, the assembly of complex structures, such as stress fibers and podosomes involves the collaboration of multiple types of actin filament specified by their Tpm composition. This allows the cell to specify actin filament function in time and space by simply specifying their Tpm isoform composition.

  2. A study of spatial phenomena in semiconductor lasers: Beam filamentation and optical feedback effects

    Science.gov (United States)

    Marciante, John Robert

    1997-10-01

    In an effort to improve the performance of high-power semiconductor lasers to meet the demands of applications, this thesis contains work studying the issues which limit their performance: beam filamentation and spatial feedback effects. Through computer simulations, we investigate the role of three nonlinear mechanisms which can lead to filamentation, and determine the stability boundaries of the material parameters for which the device will not exhibit filamentary tendencies. We use an analytic theory to verify these findings, and to predict the spatio- temporal nature of the filaments through an analytic expression for the gain, in which contributions of the various mechanisms can clearly be seen. We experimentally verify the spatio-temporal characteristics of the filaments, discover effects of the stripe width and transitions to chaos, and discuss how to compare the relative severity of filamentation among different devices. We propose a new method of controlling filamentation using below-bandgap semiconductor nonlinearities. With simulations, we determine under what conditions this imposed nonlinearity can counteract the carrier-induced self-focusing inside the active region. We fabricate a prototype device using new epitaxial layers containing the below-bandgap nonlinearities, and compare the performance of these new devices to a control set. In studying the spatial effects of optical feedback, we use Fresnel diffraction theory to derive an expression for the field that is reflected back into the laser. This result is applied to our computer model and used to explore the effects of feedback on narrow-stripe, broad- area, and tapered-stripe semiconductor lasers. Re- examining feedback in narrow-stripe devices through experiments and analytic theory, we investigate the coupling effects between the narrow waveguide and the feedback field, and the changes in the operating characteristics of the laser due to this coupling. We experimentally examine the beam

  3. The non-equilibrium phase diagrams of flow-induced crystallization and melting of polyethylene.

    Science.gov (United States)

    Wang, Zhen; Ju, Jianzhu; Yang, Junsheng; Ma, Zhe; Liu, Dong; Cui, Kunpeng; Yang, Haoran; Chang, Jiarui; Huang, Ningdong; Li, Liangbin

    2016-09-09

    Combining extensional rheology with in-situ synchrotron ultrafast x-ray scattering, we studied flow-induced phase behaviors of polyethylene (PE) in a wide temperature range up to 240 °C. Non-equilibrium phase diagrams of crystallization and melting under flow conditions are constructed in stress-temperature space, composing of melt, non-crystalline δ, hexagonal and orthorhombic phases. The non-crystalline δ phase is demonstrated to be either a metastable transient pre-order for crystallization or a thermodynamically stable phase. Based on the non-equilibrium phase diagrams, nearly all observations in flow-induced crystallization (FIC) of PE can be well understood. The interplay of thermodynamic stabilities and kinetic competitions of the four phases creates rich kinetic pathways for FIC and diverse final structures. The non-equilibrium flow phase diagrams provide a detailed roadmap for precisely processing of PE with designed structures and properties.

  4. A ficção científica e o estranhamento cognitivo no ensino de ciências: estudos críticos e propostas de sala de aula

    Directory of Open Access Journals (Sweden)

    Luís Paulo Piassi

    2013-01-01

    Full Text Available Este trabalho, partindo da apresentação de propostas de ensino de ciências com o uso da ficção científica e fundamentando-se em referenciais dos estudos literários críticos sobre o gênero, objetiva argumentar que sua maior contribuição para a educação científica não se situa nem na precisão científica, nem na qualidade didática e nem mesmo no potencial lúdico que esse tipo de narrativa desperta. Sem desconsiderar a importância desses aspectos, mostramos que o sentido de levar a ficção científica para as aulas de ciências está nos mecanismos de produção ficcional que, por características que lhe são próprias, envolve um modo especial de raciocinar sobre o mundo natural. Tais mecanismos baseiam-se em conjecturas que promovem o chamado estranhamento cognitivo capaz de promover, nos estudantes, a problematização que pode ser o ponto de partida para uma abordagem crítica, não apenas de conceitos e leis, mas, também, de suas implicações e motivações epistemológicas e socioculturais.

  5. FIC model selection and model averaging for linear model with censored response%响应变量删失情况下线性模型的FIC模型选择和模型平均

    Institute of Scientific and Technical Information of China (English)

    孙志猛; 马景义; 苏治

    2013-01-01

    本文给出了响应变量随机右删失情况下线性模型的FIC (focused information criterion)模型选择方法和光滑FIC模型平均估计方法,证明了兴趣参数的FIC模型选择估计和光滑FIC模型平均估计的渐近正态性,通过随机模拟研究了估计的有限样本性质,模拟结果显示,从均方误差和一定置信水平置信区间的经验覆盖概率看,兴趣参数的光滑FIC模型平均估计均优于FIC,AIC (Akaikeinformation criterion)和BIC (Bayesian information citerion)等模型选择估计;而FIC模型选择估计与AIC和BIC等模型选择估计相比,也表现出了一定的优越性.通过分析原发性胆汁性肝硬化数据集,说明了本文方法在实际问题中的应用.

  6. Olhando o presente a partir do futuro: a pedagogia do cinema de ficção científica = Looking at the present from the future: the pedagogy of science-fiction films

    Directory of Open Access Journals (Sweden)

    Bicca, Angela Dillmann Nunes

    2013-01-01

    Full Text Available Neste artigo, sob a perspectiva dos estudos culturais de inspiração pós-moderna e pós-estruturalista, buscamos indicar como os filmes de ficção científica têm operado na configuração de um mundo futuro, altamente tecnológico, bem como dos sujeitos que nele viverão, a partir de representações que exacerbam e satirizam modos de viver já em curso nas sociedades contemporâneas. O cinema, assim como outras pedagogias culturais, atua na produção e no governo dos indivíduos em um mundo repleto de tecnologias da informação e da comunicação, promovendo deslocamentos nas suas subjetividades. Para promover tal discussão, abordamos seis filmes de ficção científica cujas análises focalizaram a perturbadora semelhança entre seres humanos e máquinas, representadas nestes filmes como criaturas ciborgues, pós-humanas e pós-orgânicas. Indicamos, também, a proliferação de lixo tecnológico e lixo humano nas sociedades “do futuro” e, ainda, a substituição do disciplinamento moderno por ações bastante sutis de controle

  7. Televisão e imaginário: entre os limites da ficção e da realidade = Television and imaginary: in between limits of fiction and reality

    Directory of Open Access Journals (Sweden)

    Pasa, Poliana Dorneles

    2013-01-01

    Full Text Available Este artigo trata das coincidências entre a ficção e a realidade histórica a partir do exemplo da série de televisão 24 Horas. O impacto das imagens televisivas na formação do imaginário social passa pela relação cada vez mais entrelaçada entre a mídia e vida cotidiana. Na medida em que o veículo se firma como onipresente na contemporaneidade, é preciso pensar sobre o seu poder em instituir um espaço social e, portanto, difundir discursos e estéticas. Ainda que a produção simbólica de uma série televisiva encontre a barreira entre “ficção” e “realidade”, cabe pensar na televisão enquanto um meio capaz de dissolver e instaurar mundos a despeito da relação entre “verdade” e “verossímil”. Assim, direcionar a atenção para séries de cunho político ou social permite detectar tendências na criação de imagens, estereótipos e discursos que podem reger a sociedade no futuro

  8. Nano-droplet ejection and nucleation of materials submitted to non-thermal plasma filaments

    Science.gov (United States)

    Borra, J.-P.; Jidenko, N.; Dutouquet, C.; Aguerre, O.; Hou, J.; Weber, A.

    2011-11-01

    Methods to induce non-thermal atmospheric pressure plasma filaments are presented with related properties for micro, streamer and prevented spark discharges, respectively, induced in planar Dielectric Barrier Discharges with one electrode covered by dielectric material (mono-DBD) or point-to-plane Corona. Two mechanisms of nano-particles formation are depicted from aerosol size distributions and TEM analysis. 0.1-10 mJ prevented spark discharges produce 10-100 nm droplets ejected from melted craters as well as nucleated primary particles and subsequent 10-100 nm agglomerates, by nucleation and coagulation in expanding vapor jets. With smaller energy per filament, 0.1-10 μJ micro-discharges and 0.1-100 μJ streamers, the initial local vapor fluxes emitted from spots of interaction between plasma filaments and electrodes are reduced. Subsequent smaller primary particle density limits the local coagulation in the vapor plume since 2-10 nm non-agglomerated crystalline metal nano-particles are produced in mono-DBD with Au, Ag and Cu electrode. Besides, the evolution of the aerosol size from primary nano-particles to agglomerates with transit time suggests slow coagulation of these primary metal particles in mono-DBD. Aerosol properties depend on the energy per filament and on the electrode. The final size is controlled by plasma parameters and transit time in and after the plasma. The aim is to underline emerging applications of atmospheric pressure plasmas for the production of tailored particles with tunable size, composition and structure with non-thermal plasma filaments to control the resulting properties of nano-powders and materials. Production rates and related energetic yields are compared.

  9. Interaction of surfactant protein A with the intermediate filaments desmin and vimentin.

    Science.gov (United States)

    Garcia-Verdugo, Ignacio; Synguelakis, Monique; Degrouard, Jeril; Franco, Claudio-Areias; Valot, Benoit; Zivy, Michel; Chaby, Richard; Tanfin, Zahra

    2008-05-06

    Surfactant protein A (SP-A), a member of the collectin family that modulates innate immunity, has recently been involved in the physiology of reproduction. Consistent with the activation of ERK-1/2 and COX-2 induced by SP-A in myometrial cells, we reported previously the presence of two major proteins recognized by SP-A in these cells. Here we identify by mass spectrometry one of these SP-A targets as the intermediate filament (IF) desmin. In myometrial preparations derived from desmin-deficient mice, the absence of binding of SP-A to any 50 kDa protein confirmed the identity of this SP-A-binding site as desmin. Our data based on partial chymotrypsin digestion of pure desmin suggested that SP-A recognizes especially its rod domain, which is known to play an important role during the assembly of desmin into filaments. In line with that, electron microscopy experiments showed that SP-A inhibits in vitro the polymerization of desmin filaments. SP-A also recognized in vitro polymerized filaments in a calcium-dependent manner at a physiological ionic strength but not the C1q receptor gC1qR. Furthermore, Texas Red-labeled SP-A colocalized with desmin filaments in myometrial cells. Interestingly, vimentin, the IF characteristic of leukocytes, is one of the major proteins recognized by SP-A in protein extracts of U937 cells after PMA-induced differentiation of this monocytic cell line. Interaction of SP-A with vimentin was further confirmed using recombinant vimentin in solid-phase binding assays. The ability of SP-A to interact with desmin and vimentin, and to prevent polymerization of desmin monomers, shed light on unexpected and wider biological roles of this collectin.

  10. Filament Eruptions, Jets, and Space Weather

    Science.gov (United States)

    Moore, Ronald; Sterling, Alphonse; Robe, Nick; Falconer, David; Cirtain, Jonathan

    2013-01-01

    Previously, from chromospheric H alpha and coronal X-ray movies of the Sun's polar coronal holes, it was found that nearly all coronal jets (greater than 90%) are one or the other of two roughly equally common different kinds, different in how they erupt: standard jets and blowout jets (Yamauchi et al 2004, Apl, 605, 5ll: Moore et all 2010, Apj, 720, 757). Here, from inspection of SDO/AIA He II 304 A movies of 54 polar x-ray jets observed in Hinode/XRT movies, we report, as Moore et al (2010) anticipated, that (1) most standard x-ray jets (greater than 80%) show no ejected plasma that is cool enough (T is less than or approximately 10(exp 5K) to be seen in the He II 304 A movies; (2) nearly all blownout X-ray jets (greater than 90%) show obvious ejection of such cool plasma; (3) whereas when cool plasma is ejected in standard X-ray jets, it shows no lateral expansion, the cool plasma ejected in blowout X-ray jets shows strong lateral expansion; and (4) in many blowout X-ray jets, the cool plasma ejection displays the erupting-magnetic-rope form of clasic filament eruptions and is thereby seen to be a miniature filament eruption. The XRT movies also showed most blowout X-ray jets to be larger and brighter, and hence to apparently have more energy, than most standard X-ray jets. These observations (1) confirm the dichotomy of coronal jets, (2) agree with the Shibata model for standard jets, and (3) support the conclusion of Moore et al (2010) that in blowout jets the magnetic-arch base of the jet erupts in the manner of the much larger magnetic arcades in which the core field, the field rooted along the arcade's polarity inversion line, is sheared and twisted (sigmoid), often carries a cool-plasma filament, and erupts to blowout the arcade, producing a CME. From Hinode/SOT Ca II movies of the polar limb, Sterling et al (2010, ApJ, 714, L1) found that chromospheric Type-II spicules show a dichotomy of eruption dynamics similar to that found here for the cool

  11. The extreme nonlinear optics of gases and femtosecond optical/plasma filamentation

    Science.gov (United States)

    Milchberg, Howard

    2013-10-01

    Under certain conditions, powerful ultrashort laser pulses can form greatly extended filaments of concentrated high intensity in gases, leaving behind a very long trail of plasma. Such filaments can be much longer than the longitudinal scale over which a laser beam typically diverges by diffraction. Applications range from laser-guided electrical discharges to remote sensing. Air is a medium of particular interest for applications, and as a mostly molecular gas it is interesting from a physics perspective as well. I will work through the fundamentals of filamentation and give an overview of the field. Understanding in detail the microscopic processes leading to filamentation requires fundamental measurements of the strong field nonlinear response of gas phase atoms and molecules with unprecedented precision in space and time. This includes absolute, ultrafast measurements of nonlinear laser-induced polarization and high field ionization. I will describe how such measurements are done and show how they can be applied to propagation experiments. Work supported by the Air Force Office of Scientific Research, the Office of Naval Research, the National Science Foundation, and the US Dept. of Energy.

  12. Liquid-like bundles of crosslinked actin filaments contract without motors

    Science.gov (United States)

    Weirich, Kimberly

    The actin cytoskeleton is a dynamic, structural material that drives cellular-scale deformations during processes such as cell migration and division. Motor proteins are responsible for actively driving many deformations by buckling and translocating actin filaments. However, there is evidence that deformations, such as the constriction of the actin bundle that drives the separation of cells during division, can occur without motors, mediated instead by crosslinker proteins. How might crosslinkers, independent of motors, drive contraction of a bundle? Using a model system of purified proteins, we show that crosslinkers, analogous to molecular cohesion, create an effective surface tension that induces bundle contraction. Crosslinked short actin filaments form micron-sized spindle-shaped bundles. Similar to tactoid granules found at the isotropic-nematic phase transition in liquid crystals, these bundles coarsen and coalesce like liquid droplets. In contrast, crosslinked long filaments coarsen into a steady state of bundles that are frozen in a solid-like network. Near the liquid-solid boundary, filaments of intermediate length initially form bundles that spontaneously contract into tactoid droplets. Our results, that crosslinked actin bundles are liquid-like with an effective surface tension, provide evidence for a mechanism of motor-independent contractility in biological materials.

  13. Triggered star-formation in the inner filament of Centaurus A

    CERN Document Server

    Crockett, R Mark; Kaviraj, Sugata; Antonuccio-Delogu, Vincenzo; Silk, Joseph; Mutchler, Max; O'Connell, Robert W; Rejkuba, Marina; Whitmore, Bradley C; Windhorst, Rogier A

    2012-01-01

    We present recent Hubble Space Telescope observations of the inner filament of Centaurus A, using the new Wide Field Camera 3 (WFC3) $F225W, F657N$ and $F814W$ filters. We find a young stellar population near the south-west tip of the filament. Combining the WFC3 dataset with archival Advanced Camera for Surveys (ACS) $F606W$ observations, we are able to constrain the ages of these stars to <=10 Myrs, with best-fit ages of 1-4 Myrs. No further recent star-formation is found along the filament. Based on the location and age of this stellar population, and the fact that there is no radio lobe or jet activity near the star-formation, we propose an updated explanation for the origin of the inner filament. Sutherland et al. (1993) suggested that radio jet-induced shocks can drive the observed optical line emission. We argue that such shocks can naturally arise due to a weak cocoon-driven bow shock (rather than from the radio jet directly), propagating through the diffuse interstellar medium from a location near...

  14. Wetting and dewetting processes in the axial retraction of liquid filaments

    Science.gov (United States)

    Ravazzoli, Pablo D.; Cuellar, Ingrith; González, Alejandro G.; Diez, Javier A.

    2017-05-01

    We study the hydrodynamic mechanisms involved in the motion of the contact line formed at the end region of a liquid filament laying on a planar and horizontal substrate. Since the flow develops under partially wetting conditions, the tip of the filament recedes and forms a bulged region (head) that subsequently develops a neck region behind it. Later the neck breaks up leading to a separated drop, while the rest of the filament restarts the sequence. One main feature of this flow is that the whole dynamics and final drop shapes are strongly influenced by the hysteresis of the contact angle typical in most of the liquid-substrate systems. The time evolution till breakup is studied experimentally and pictured in terms of a hybrid wettability theory which involves the Cox-Voinov hydrodynamic approach combined with the molecular kinetic theory developed by Blake. The parameters of this theory are determined for our liquid-substrate system (silicone oil-coated glass). The experimental results of the retracting filament are described in terms of a simple heuristic model and compared with numerical simulations of the full Navier-Stokes equations. This study is of special interest in the context of pulsed laser-induced dewetting.

  15. Heterocyst placement strategies to maximize growth of cyanobacterial filaments

    CERN Document Server

    Brown, Aidan I

    2012-01-01

    Under conditions of limited fixed-nitrogen, some filamentous cyanobacteria develop a regular pattern of heterocyst cells that fix nitrogen for the remaining vegetative cells. We examine three different heterocyst placement strategies by quantitatively modelling filament growth while varying both external fixed-nitrogen and leakage from the filament. We find that there is an optimum heterocyst frequency which maximizes the growth rate of the filament; the optimum frequency decreases as the external fixed-nitrogen concentration increases but increases as the leakage increases. In the presence of leakage, filaments implementing a local heterocyst placement strategy grow significantly faster than filaments implementing random heterocyst placement strategies. With no extracellular fixed-nitrogen, consistent with recent experimental studies of Anabaena sp. PCC 7120, the modelled heterocyst spacing distribution using our local heterocyst placement strategy is qualitatively similar to experimentally observed patterns...

  16. Hamiltonian Dynamics of Protein Filament Formation.

    Science.gov (United States)

    Michaels, Thomas C T; Cohen, Samuel I A; Vendruscolo, Michele; Dobson, Christopher M; Knowles, Tuomas P J

    2016-01-22

    We establish the Hamiltonian structure of the rate equations describing the formation of protein filaments. We then show that this formalism provides a unified view of the behavior of a range of biological self-assembling systems as diverse as actin, prions, and amyloidogenic polypeptides. We further demonstrate that the time-translation symmetry of the resulting Hamiltonian leads to previously unsuggested conservation laws that connect the number and mass concentrations of fibrils and allow linear growth phenomena to be equated with autocatalytic growth processes. We finally show how these results reveal simple rate laws that provide the basis for interpreting experimental data in terms of specific mechanisms controlling the proliferation of fibrils.

  17. Intermediate filaments: from cell architecture to nanomechanics.

    Science.gov (United States)

    Herrmann, Harald; Bär, Harald; Kreplak, Laurent; Strelkov, Sergei V; Aebi, Ueli

    2007-07-01

    Intermediate filaments (IFs) constitute a major structural element of animal cells. They build two distinct systems, one in the nucleus and one in the cytoplasm. In both cases, their major function is assumed to be that of a mechanical stress absorber and an integrating device for the entire cytoskeleton. In line with this, recent disease mutations in human IF proteins indicate that the nanomechanical properties of cell-type-specific IFs are central to the pathogenesis of diseases as diverse as muscular dystrophy and premature ageing. However, the analysis of these various diseases suggests that IFs also have an important role in cell-type-specific physiological functions.

  18. Langmuir wave filamentation in the kinetic regime

    CERN Document Server

    Silantyev, Denis A; Rose, Harvey A

    2016-01-01

    Nonlinear Langmuir wave in the kinetic regime $k\\lambda_D\\gtrsim0.2$ has a transverse instability, where $k$ is the wavenumber and $\\lambda_D$ is the Debye length. The nonlinear stage of that instability development leads to the filamentation of Langmuir waves. Here we study the linear stage of transverse instability of both Bernstein-Greene-Kruskal (BGK) modes and dynamically prepared BGK-like initial conditions to find the same instability growth rate suggesting the universal mechanism for the kinetic saturation of stimulated Raman scatter in laser-plasma interaction experiments. Multidimensional Vlasov simulations results are compared to the theoretical predictions.

  19. Filament winding cylinders. I - Process model

    Science.gov (United States)

    Lee, Soo-Yong; Springer, George S.

    1990-01-01

    A model was developed which describes the filament winding process of composite cylinders. The model relates the significant process variables such as winding speed, fiber tension, and applied temperature to the thermal, chemical and mechanical behavior of the composite cylinder and the mandrel. Based on the model, a user friendly code was written which can be used to calculate (1) the temperature in the cylinder and the mandrel, (2) the degree of cure and viscosity in the cylinder, (3) the fiber tensions and fiber positions, (4) the stresses and strains in the cylinder and in the mandrel, and (5) the void diameters in the cylinder.

  20. Filamentous bacteria transport electrons over centimetre distances

    DEFF Research Database (Denmark)

    Pfeffer, Christian; Larsen, Steffen; Song, Jie

    2012-01-01

    across centimetre-wide zones. Here we present evidence that the native conductors are long, filamentous bacteria. They abounded in sediment zones with electric currents and along their length they contained strings with distinct properties in accordance with a function as electron transporters. Living......Oxygen consumption in marine sediments is often coupled to the oxidation of sulphide generated by degradation of organic matter in deeper, oxygen-free layers. Geochemical observations have shown that this coupling can be mediated by electric currents carried by unidentified electron transporters......, electrical cables add a new dimension to the understanding of interactions in nature and may find use in technology development....

  1. Numerical simulations of a filament in a flowing soap film

    Science.gov (United States)

    Farnell, D. J. J.; David, T.; Barton, D. C.

    2004-01-01

    Experiments concerning the properties of soap films have recently been carried out and these systems have been proposed as experimental versions of theoretical two-dimensional liquids. A silk filament introduced into a flowing soap film, was seen to demonstrate various stable modes, and these were, namely, a mode in which the filament oscillates and one in which the filament is stationary and aligns with the flow of the liquid. The system could be forced from the oscillatory mode into the non- oscillatory mode by varying the length of the filament. In this article we use numerical and computational techniques in order to simulate the strongly coupled behaviour of the filament and the fluid. Preliminary results are presented for the specific case in which the filament is seen to oscillate continuously for the duration of our simulation. We also find that the filament oscillations are strongly suppressed when we reduce the effective length of the filament. We believe that these results are reminiscent of the different oscillatory and non-oscillatory modes observed in experiment. The numerical solutions show that, in contrast to experiment, vortices are created at the leading edge of the filament and are preferentially grown in the curvature of the filament and are eventually released from the trailing edge of the filament. In a similar manner to oscillating hydrofoils, it seems that the oscillating filaments are in a minimal energy state, extracting sufficient energy from the fluid to oscillate. In comparing numerical and experimental results it is possible that the soap film does have an effect on the fluid flow especially in the boundary layer where surface tension forces are large.

  2. Oxygen Control for an Industrial Pilot-Scale Fed-Batch Filamentous Fungal Fermentation

    OpenAIRE

    Bodizs, Levente; Titica, Mariana; Faria, Nuno; Srinivasan, Bala; Dochain, Denis; Bonvin, Dominique

    2007-01-01

    Industrial filamentous fungal fermentations are typically operated in fed- batch mode. Oxygen control represents an important operational challenge due to the varying biomass concentration. In this study, oxygen control is implemented by manipulating the substrate feed rate, i.e. the rate of oxygen consumption. It turns out that the setpoint for dissolved oxygen represents a trade-off since a low dissolved oxygen value favors productivity but can also induce oxygen limitation. This pape...

  3. Crosstalk between non-processive myosin motors mediated by the actin filament elasticity

    OpenAIRE

    2011-01-01

    Many biological processes involve the action of molecular motors that interact with the cell cytoskeleton. Some processes, such as the transport of cargoes is achieved mainly by the action of individual motors. Other, such as cell motility and division, require the cooperative work of many motors. Collective motor dynamics can be quite complex and unexpected. One beautiful example is the bidirectional ("back and forth") motion of filaments which is induced when the motors within a group exert...

  4. Phosphatidylserine liposomes can be tethered by caldesmon to actin filaments.

    Science.gov (United States)

    Makuch, R; Zasada, A; Mabuchi, K; Krauze, K; Wang, C L; Dabrowska, R

    1997-01-01

    Rotary shadowing electron microscopy revealed that attachment of caldesmon to phosphatidylserine (PS) liposomes was mainly through its C-terminal end. To determine the PS-binding sites of caldesmon, we have made use of synthetic peptides covering the two C-terminal calmodulin binding sites and a recombinant fragment corresponding to the N-terminal end of the C-terminal domain that contains an amphipathic helix. Interactions of these peptides with the PS liposomes were studied by nondenaturing gel electrophoresis and fluorescence spectroscopy. The results showed that both calmodulin-binding sites of caldesmon were able to interact with PS. The affinity (Kd) of PS for these sites was in the range of 1.8-14.3 x 10(-5) M, compared to 0.69 x 10(-5) M for the whole caldesmon molecule. Fragments located outside of calmodulin-binding sites bound PS weakly (3.85 x 10(-4) M) and thus may contain a second class of lipid-binding sites. Binding of PS induced conformational changes in regions other than the C-terminal PS-binding sites, as evidenced by the changes in the susceptibility to proteolytic cleavages. Most significantly, the presence of caldesmon greatly increased binding of PS to F-actin, suggesting that caldesmon may tether PS liposomes to actin filaments. These results raise the possibility that caldesmon-lipid interactions could play a functionally important role in the assembly of contractile filaments near the membranes. Images FIGURE 2 FIGURE 4 FIGURE 6 PMID:9284327

  5. Automated image analysis for quantification of filamentous bacteria

    DEFF Research Database (Denmark)

    Fredborg, M.; Rosenvinge, F. S.; Spillum, E.

    2015-01-01

    Background: Antibiotics of the beta-lactam group are able to alter the shape of the bacterial cell wall, e.g. filamentation or a spheroplast formation. Early determination of antimicrobial susceptibility may be complicated by filamentation of bacteria as this can be falsely interpreted as growth...... displaying different resistant profiles and differences in filamentation kinetics were used to study a novel image analysis algorithm to quantify length of bacteria and bacterial filamentation. A total of 12 beta-lactam antibiotics or beta-lactam-beta-lactamase inhibitor combinations were analyzed...

  6. Dynamics of Actin Filament Ends in a Network

    Science.gov (United States)

    Yang, Le; Sept, David; Carlsson, Anders

    2004-03-01

    The formation of filopodia-like bundles in vitro from a dendritic actin network has been observed(D. Vignjevic et al, J. Cell Biol. 160, 951 (2003)) to occur as a result of a nucleation process. We study the dynamics of the actin filament ends in such a network in order to evaluate the dynamics of the bundle nucleation process. Our model treats two semiflexible actin filaments fixed at one end and free at the other, moving according to Brownian dynamics. The initial filament positions are chosen according to a thermal distribution, and we evaluate the time for the filaments to come close enough to each other to interact and bind. The capture criterion is based either on the distance between filaments, or on a combination of distance and relative orientation. We evaluate the dependence of the capture time on the filament length and radius, and the distance between the filament bases. Since treating the movement of the individual monomers in filaments is computationally unwieldy, we treat the filament motion using a normal mode analysis which permits use of a much longer timestep. We find that this method yields rapid convergence even when only the few longest-wavelength modes are included.

  7. Formation and evolution of an active region filament

    CERN Document Server

    Kuckein, C; Pillet, V Martínez

    2013-01-01

    Several scenarios explaining how filaments are formed can be found in literature. In this paper, we analyzed the observations of an active region filament and critically evaluated the observed properties in the context of current filament formation models. This study is based on multi-height spectropolarimetric observations. The inferred vector magnetic field has been extrapolated starting either from the photosphere or from the chromosphere. The line-of-sight motions of the filament, which was located near disk center, have been analyzed inferring the Doppler velocities. We conclude that a part of the magnetic structure emerged from below the photosphere.

  8. Material Supply and Magnetic Configuration of an Active Region Filament

    Science.gov (United States)

    Zou, P.; Fang, C.; Chen, P. F.; Yang, K.; Hao, Q.; Cao, Wenda

    2016-11-01

    It is important to study the fine structures of solar filaments with high-resolution observations, since it can help us understand the magnetic and thermal structures of the filaments and their dynamics. In this paper, we study a newly formed filament located inside the active region NOAA 11762, which was observed by the 1.6 m New Solar Telescope at Big Bear Solar Observatory from 16:40:19 UT to 17:07:58 UT on 2013 June 5. As revealed by the Hα filtergrams, cool material is seen to be injected into the filament spine with a speed of 5-10 km s-1. At the source of the injection, brightenings are identified in the chromosphere, which are accompanied by magnetic cancellation in the photosphere, implying the importance of magnetic reconnection in replenishing the filament with plasmas from the lower atmosphere. Counter-streamings are detected near one endpoint of the filament, with the plane-of-the-sky speed being 7-9 km s-1 in the Hα red-wing filtergrams and 9-25 km s-1 in the blue-wing filtergrams. The observations are indicative that this active region filament is supported by a sheared arcade without magnetic dips, and the counter-streamings are due to unidirectional flows with alternative directions, rather than due to the longitudinal oscillations of filament threads as in many other filaments.

  9. Controlling multiple filaments by relativistic optical vortex beams in plasmas

    Science.gov (United States)

    Ju, L. B.; Huang, T. W.; Xiao, K. D.; Wu, G. Z.; Yang, S. L.; Li, R.; Yang, Y. C.; Long, T. Y.; Zhang, H.; Wu, S. Z.; Qiao, B.; Ruan, S. C.; Zhou, C. T.

    2016-09-01

    Filamentation dynamics of relativistic optical vortex beams (OVBs) propagating in underdense plasma is investigated. It is shown that OVBs with finite orbital angular momentum (OAM) exhibit much more robust propagation behavior than the standard Gaussian beam. In fact, the growth rate of the azimuthal modulational instability decreases rapidly with increase of the OVB topological charge. Thus, relativistic OVBs can maintain their profiles for significantly longer distances in an underdense plasma before filamentation occurs. It is also found that an OVB would then break up into regular filament patterns due to conservation of the OAM, in contrast to a Gaussian laser beam, which in general experiences random filamentation.

  10. Plutonium ion emission from carburized rhenium mass spectrometer filaments

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, J.M.; Robertson, D.M.

    1985-01-01

    Physicochemical processes important to the application of thermal emission mass spectrometry were identified and clarified. Effects of filament carbon concentration and temperature on plutonium ion emissions from a carburized rhenium filament were determined. Filament carbon concentration profoundly affected the appearance and duration of an ion signal. A useful ion signal was produced only when the carbon saturation temperature of the filament was exceeded, at which point first-order kinetics were either achieved or closely approached. This paper explains observed ion emission behavior in terms of pausible carbothermic reduction reactions and carbon diffusion processes that direct the course of those reactions. 31 references, 5 figures.

  11. Frenet algorithm for simulations of fluctuating continuous elastic filaments

    Science.gov (United States)

    Kats, Yevgeny; Kessler, David A.; Rabin, Yitzhak

    2002-02-01

    We present an algorithm for generating the equilibrium configurations of fluctuating continuous elastic filaments, based on a combination of statistical mechanics and differential geometry. We use this to calculate the distribution function of the end-to-end distance of filaments with nonvanishing spontaneous curvature and show that for small twist and large bending rigidities there is an intermediate temperature range in which the filament becomes nearly completely stretched. We show that volume interactions can be incorporated into our algorithm, demonstrating this through the calculation of the effect of excluded volume on the end-to-end distance of the filament.

  12. O paradoxo traumático: documentários, ficções históricas e eventos passados cataclísmicos O paradoxo traumático: documentários, ficções históricas e eventos passados cataclísmicos

    Directory of Open Access Journals (Sweden)

    Janet Walker

    2008-04-01

    Full Text Available Numa aula sobre documentários, no contexto de uma introdução a um curso sobre cinema, pedi a meus alunos que definissem “documentário” a partir da especulação sobre quais seriam os seus limites. Apropriadamente, A Lista de Schindler surgiu, fazendo com que a discussão se deslocasse para questões de ficção histórica e documentários. Nosso entusiasmo foi interrompido por uma ávida aluna sentada à frente que exclamou: “Mas o filme não pode ser um documentário porque nenhum desses eventos realmente aconteceu. Eu não acredito no Holocausto.” Muitas vezes pensei naquela aluna, desde aquela aula. Ponderei que, ou ela representa a guinada pósmoderna no novo historicismo por excelência (sua completa aceitação da ausência de provas históricas, da inacessibilidade do passado, transportando-a para além de uma crença antiquada e teoricamente ingênua em um cosmo material abordável a partir de um ponto de observação objetivo, ou talvez ela seja apenas mal-informada. Ou, talvez exista uma terceira alternativa sobre a qual me referirei adiante. Neste caso, felizmente, minha hesitação pedagógica deu chance para que os outros alunos interviessem. E as intervenções foram indiretas e bastante úteis.

  13. Characterising Radio Emissions in Cosmic Filaments

    Science.gov (United States)

    Miller, R. O.

    2014-02-01

    A growing number of radio studies probe galaxy clusters into the low-power regime in which star formation is the dominant source of radio emission. However, at the time of writing no comparably deep observations have focused exclusively on the radio populations of cosmic filaments. This thesis describes the ATCA 2.1 GHz observations and subsequent analysis of two such regions - labelled Zone 1 (between clusters A3158 and A3125/A3128) and Zone 2 (between A3135 and A3145) - in the Horologium-Reticulum Supercluster (HRS). Source count profiles of both populations are discussed and a radio luminosity function for Zone 1 is generated. While the source counts of Zone 2 appear to be consistent with expected values, Zone 1 exhibits an excess of counts across a wide flux range (1 mJy< S_1.4 < 200 mJy). An excess in radio activity at the lower extent of this range (log P_1.4 < 22.5; within the SF-dominated regime) is also suggested by the radio luminosity function for that region, and brief colour analysis suggests that such an excess is indeed predominantly associated with a starforming population. The differences between the two filamentary zones is attributed to cosmic variation. The regions are both small (~ 1 degree square), and are significantly separated in the HRS. Further radio observations of filaments are required and the results combined into a larger sample size in order to arrive at a generalised model filamentary population.

  14. The Golgi apparatus: insights from filamentous fungi.

    Science.gov (United States)

    Pantazopoulou, Areti

    2016-01-01

    Cargo passage through the Golgi, albeit an undoubtedly essential cellular function, is a mechanistically unresolved and much debated process. Although the main molecular players are conserved, diversification of the Golgi among different eukaryotic lineages is providing us with tools to resolve standing controversies. During the past decade the Golgi apparatus of model filamentous fungi, mainly Aspergillus nidulans, has been intensively studied. Here an overview of the most important findings in the field is provided. Golgi architecture and dynamics, as well as the novel cell biology tools that were developed in filamentous fungi in these studies, are addressed. An emphasis is placed on the central role the Golgi has as a crossroads in the endocytic and secretory-traffic pathways in hyphae. Finally the major advances that the A. nidulans Golgi biology has yielded so far regarding our understanding of key Golgi regulators, such as the Rab GTPases RabC(Rab6) and RabE(Rab11), the oligomeric transport protein particle, TRAPPII, and the Golgi guanine nucleotide exchange factors of Arf1, GeaA(GBF1/Gea1) and HypB(BIG/Sec7), are highlighted.

  15. Morgellons disease: a filamentous borrelial dermatitis

    Directory of Open Access Journals (Sweden)

    Middelveen MJ

    2016-10-01

    Full Text Available Marianne J Middelveen, Raphael B Stricker International Lyme and Associated Diseases Society, Bethesda, MD, USA Abstract: Morgellons disease (MD is a dermopathy characterized by multicolored filaments that lie under, are embedded in, or project from skin. Although MD was initially considered to be a delusional disorder, recent studies have demonstrated that the dermopathy is associated with tickborne infection, that the filaments are composed of keratin and collagen, and that they result from proliferation of keratinocytes and fibroblasts in epithelial tissue. Culture, histopathological and molecular evidence of spirochetal infection associated with MD has been presented in several published studies using a variety of techniques. Spirochetes genetically identified as Borrelia burgdorferi sensu stricto predominate as the infective agent in most of the Morgellons skin specimens studied so far. Other species of Borrelia including Borrelia garinii, Borrelia miyamotoi, and Borrelia hermsii have also been detected in skin specimens taken from MD patients. The optimal treatment for MD remains to be determined. Keywords: Morgellons disease, dermatitis, Lyme disease, Borrelia burgdorferi, spirochetes

  16. Filamentation and supercontinuum generation in lanthanum glass

    Science.gov (United States)

    Yang, Yuxia; Liao, Meisong; Li, Xia; Bi, Wanjun; Ohishi, Yasutake; Cheng, Tonglei; Fang, Yongzheng; Zhao, Guoying; Gao, Weiqing

    2017-01-01

    A broadband supercontinuum (SC) covering 400-2800 nm in a 20 dB dynamic range is reported in a piece of highly nonlinear, low-dispersion bulk lanthanum glass without employing any lens to focus the pump pulse. The spectrum width obtained in this study is broader than the maximum spectrum width obtained in silica photonic crystal fibers. The filaments and bright conical visible emission patterns of the SC are analyzed. Under optimum pump conditions, an SC conversion efficiency of 75% is obtained. The SC conversion efficiency is confirmed to be stable. Additionally, the relationship between the input peak intensity and the output beam radius is elucidated by simulating the propagation of a Gaussian beam in the bulk lanthanum glass. A 0.20 mm stable laser beam radius at the end of the propagation domain is demonstrated in a certain input peak intensity range. This small value of the beam radius indicates that most of the output power is localized over a small region because of the Kerr focusing effect despite the existence of conical emission in the SC generation by filamentation. The findings of this study are of significance for the development of ultra-broadband SC sources based on bulk glasses and high peak power lasers.

  17. Study of filamentation with a high power high repetition rate ps laser at 1.03 µm.

    Science.gov (United States)

    Houard, A; Jukna, V; Point, G; André, Y-B; Klingebiel, S; Schultze, M; Michel, K; Metzger, T; Mysyrowicz, A

    2016-04-01

    We study the propagation of intense, high repetition rate laser pulses of picosecond duration at 1.03 µm central wavelength through air. Evidence of filamentation is obtained from measurements of the beam profile as a function of distance, from photoemission imaging and from spatially resolved sonometric recordings. Good agreement is found with numerical simulations. Simulations reveal an important self shortening of the pulse duration, suggesting that laser pulses with few optical cycles could be obtained via double filamentation. An important lowering of the voltage required to induce guided electric discharges between charged electrodes is measured at high laser pulse repetition rate.

  18. THE APPARATUS FOR ALIGNMENT OF THE PHOTOMETRIC LAMP FILAMENT

    Directory of Open Access Journals (Sweden)

    V. A. Dlugunovich

    2015-01-01

    Full Text Available During photometric measurements involving the use of photometric lamps it is necessary that the filament of lamp takes a strictly predetermined position with respect to the photodetector and the optical axis of the photometric setup. The errors in positioning of alignment filament with respect to the optical axis of the measuring system lead to increase the uncertainty of measurement of the photometric characteristics of the light sources. A typical method for alignment of filament of photometric lamps is based on the use a diopter tubes (telescopes. Using this method, the mounting of filament to the required position is carried out by successive approximations, which requires special concentration and a lot of time. The aim of this work is to develop an apparatus for alignment which allows simultaneous alignment of the filament of lamps in two mutually perpendicular planes. The method and apparatus for alignment of the photometric lamp filament during measurements of the photometric characteristics of light sources based on two digital video cameras is described in this paper. The apparatus allows to simultaneously displaying the image of lamps filament on the computer screen in two mutually perpendicular planes. The apparatus eliminates a large number of functional units requiring elementwise alignment and reduces the time required to carry out the alignment. The apparatus also provides the imaging of lamps filament with opaque coated on the bulb. The apparatus is used at the National standard of light intensity and illuminance units of the Republic of Belarus. 

  19. Motion of a Vortex Filament in the Half Space

    CERN Document Server

    Aiki, Masashi

    2010-01-01

    A model equation for the motion of a vortex filament immersed in three dimensional, incompressible and inviscid fluid is investigated as a humble attempt to model the motion of a tornado. We solve an initial-boundary value problem in the half space where we impose a boundary condition in which the vortex filament is allowed to move on the boundary.

  20. Remote Sub-Diffraction Imaging with Femtosecond Laser Filaments

    Science.gov (United States)

    2012-04-10

    from low-density plasma . Hence the size of the filaments is not limited by the aperture of an optical system [1] which would ordinarily determine the...The diameter of the filament is around 40 μm (estimated by knife -edge transmission measurements; not shown), which together with the scan step

  1. Fossil evidence for spin alignment of SDSS galaxies in filaments

    NARCIS (Netherlands)

    Jones, Bernard J.T.; Weygaert, Rien van de; Arag´on-Calvo, Miguel A.

    2010-01-01

    We search for and find fossil evidence that the distribution of the spin axes of galaxies in cosmic web filaments relative to their host filaments are not randomly distributed. This would indicate that the action of large scale tidal torques effected the alignments of galaxies located in cosmic fila

  2. Physical principles of filamentous protein self-assembly kinetics

    Science.gov (United States)

    Michaels, Thomas C. T.; Liu, Lucie X.; Meisl, Georg; Knowles, Tuomas P. J.

    2017-04-01

    The polymerization of proteins and peptides into filamentous supramolecular structures is an elementary form of self-organization of key importance to the functioning biological systems, as in the case of actin biofilaments that compose the cellular cytoskeleton. Aberrant filamentous protein self-assembly, however, is associated with undesired effects and severe clinical disorders, such as Alzheimer’s and Parkinson’s diseases, which, at the molecular level, are associated with the formation of certain forms of filamentous protein aggregates known as amyloids. Moreover, due to their unique physicochemical properties, protein filaments are finding extensive applications as biomaterials for nanotechnology. With all these different factors at play, the field of filamentous protein self-assembly has experienced tremendous activity in recent years. A key question in this area has been to elucidate the microscopic mechanisms through which filamentous aggregates emerge from dispersed proteins with the goal of uncovering the underlying physical principles. With the latest developments in the mathematical modeling of protein aggregation kinetics as well as the improvement of the available experimental techniques it is now possible to tackle many of these complex systems and carry out detailed analyses of the underlying microscopic steps involved in protein filament formation. In this paper, we review some classical and modern kinetic theories of protein filament formation, highlighting their use as a general strategy for quantifying the molecular-level mechanisms and transition states involved in these processes.

  3. Filament Shape Versus Coronal Potential Magnetic Field Structure

    CERN Document Server

    Filippov, Boris

    2015-01-01

    Solar filament shape in projection on disc depends on the structure of the coronal magnetic field. We calculate the position of polarity inversion lines (PILs) of coronal potential magnetic field at different heights above the photosphere, which compose the magnetic neutral surface, and compare with them the distribution of the filament material in H$\\alpha$ chromospheric images. We found that the most of the filament material is enclosed between two polarity inversion lines (PILs), one at a lower height close to the chromosphere and one at a higher level, which can be considered as a height of the filament spine. Observations of the same filament on the limb by the {\\it STEREO} spacecraft confirm that the height of the spine is really very close to the value obtained from the PIL and filament border matching. Such matching can be used for filament height estimations in on-disk observations. Filament barbs are housed within protruding sections of the low-level PIL. On the base of simple model, we show that th...

  4. A Filament-Associated Halo Coronal Mass Ejection

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    There are only a few observations published so far that show the initiation of a coronal mass ejection (CME) and illustrate the magnetic changes in the surface origin of a CME. Any attempt to connect a CME with its local solar activities is meaningful. In this paper we present a clear instance of a halo CME initiation. A careful analysis of magnetograms shows that the only obvious magnetic changes in the surface region of the CME is a magnetic flux cancellation underneath a quiescent filament. The early disturbance was seen as the slow upward motion in segments of the quiescent filament. Four hours later, the filament was accelerated to about 50 km s-1 and erupted. While a small part of the material in the filament was ejected into the upper corona, most of the mass was transported to a nearby region. About forty minutes later, the transported mass was also ejected partially to the upper corona. The eruption of the filament triggered a two-ribbon flare, with post-flare loops connecting the flare ribbons. A halo CME, which is inferred to be associated with the eruptive filament, was observed from LASCO/C2 and C3. The halo CME contained two CME events, each event corresponded to a partial mass ejection of the filament. We suggest that the magnetic reconnection at the lower atmosphere is responsible for the filament eruption and the halo CME.

  5. Calibration and Temperature Profile of a Tungsten Filament Lamp

    Science.gov (United States)

    de Izarra, Charles; Gitton, Jean-Michel

    2010-01-01

    The goal of this work proposed for undergraduate students and teachers is the calibration of a tungsten filament lamp from electric measurements that are both simple and precise, allowing to determine the temperature of tungsten filament as a function of the current intensity. This calibration procedure was first applied to a conventional filament…

  6. Biophysics of filament length regulation by molecular motors

    CERN Document Server

    Kuan, Hui-Shun

    2013-01-01

    Regulating physical size is an essential problem that biological organisms must solve from the subcellular to the organismal scales, but it is not well understood what physical principles and mechanisms organisms use to sense and regulate their size. Any biophysical size-regulation scheme operates in a noisy environment and must be robust to other cellular dynamics and fluctuations. This work develops theory of filament length regulation inspired by recent experiments on kinesin-8 motor proteins, which move with directional bias on microtubule filaments and alter microtubule dynamics. Purified kinesin-8 motors can depolymerize chemically-stabilized microtubules. In the length-dependent depolymerization model, the rate of depolymerization tends to increase with filament length, because long filaments accumulate more motors at their tips and therefore shorten more quickly. When balanced with a constant filament growth rate, this mechanism can lead to a fixed polymer length. However, the mechanism by which kines...

  7. Persistent nuclear actin filaments inhibit transcription by RNA polymerase II.

    Science.gov (United States)

    Serebryannyy, Leonid A; Parilla, Megan; Annibale, Paolo; Cruz, Christina M; Laster, Kyle; Gratton, Enrico; Kudryashov, Dmitri; Kosak, Steven T; Gottardi, Cara J; de Lanerolle, Primal

    2016-09-15

    Actin is abundant in the nucleus and it is clear that nuclear actin has important functions. However, mystery surrounds the absence of classical actin filaments in the nucleus. To address this question, we investigated how polymerizing nuclear actin into persistent nuclear actin filaments affected transcription by RNA polymerase II. Nuclear filaments impaired nuclear actin dynamics by polymerizing and sequestering nuclear actin. Polymerizing actin into stable nuclear filaments disrupted the interaction of actin with RNA polymerase II and correlated with impaired RNA polymerase II localization, dynamics, gene recruitment, and reduced global transcription and cell proliferation. Polymerizing and crosslinking nuclear actin in vitro similarly disrupted the actin-RNA-polymerase-II interaction and inhibited transcription. These data rationalize the general absence of stable actin filaments in mammalian somatic nuclei. They also suggest a dynamic pool of nuclear actin is required for the proper localization and activity of RNA polymerase II.

  8. Conformations, hydrodynamic interactions, and instabilities of sedimenting semiflexible filaments

    CERN Document Server

    Saggiorato, G; Winkler, R G; Gompper, G

    2015-01-01

    The conformations and dynamics of semiflexible filaments subject to a homogeneous external (gravitational) field, e.g., in a centrifuge, are studied numerically and analytically. The competition between hydrodynamic drag and bending elasticity generates new shapes and dynamical features. We show that the shape of a semiflexible filament undergoes instabilities as the external field increases. We identify two transitions that correspond to the excitation of higher bending modes. In particular, for strong fields the filament stabilizes in a non-planar shape, resulting in a sideways drift or in helical trajectories. For two interacting filaments, we find the same transitions, with the important consequence that the new non-planar shapes have an effective hydrodynamic repulsion, in contrast to the planar shapes which attract themselves even when their osculating planes are rotated with respect to each other. For the case of planar filaments, we show analytically and numerically that the relative velocity is not n...

  9. Sedimentation of slender elastic filaments in a viscous liquid

    Science.gov (United States)

    Raspa, Veronica; Lindner, Anke; Du Roure, Olivia; Duprat, Camille

    2016-11-01

    We explore experimentally the dynamics of slender flexible filaments sedimenting in a viscous fluid at low Reynolds number. The observed deformations and dynamics result from a balance between viscous, elastic and gravitational forces on the slender body and thus are characterized by a dimensionless elasto-gravity number. We present measurements of the filaments stationary shape, velocities and trajectories for different initial conditions and filament characteristics (i.e: density, bending rigidity, size). In particular, we observe bending and reorientation of the filament, and investigate the conditions under which the filament can buckle. The introduction of elasticity broadens the spectrum of accessible sedimentation stationary states, compared to those appearing for their rigid counterparts where nor bending or buckling are allowed.

  10. Energetic protons from a disappearing solar filament

    Energy Technology Data Exchange (ETDEWEB)

    Kahler, S.W.; Cliver, E.W.; Cane, R.E.; McGuire, H.V.; Stone, R.G.

    1985-01-01

    A solar energetic (E> 50MeV) particle (SEP) event observed at 1 AU began about 1500 UT on 1981 December 5. This event was associated with a fast coronal mass ejection observed with the Solwind coronagraph on the P78-1 satellite. No metric type II or type IV burst was observed, but a weak interplanetary type II burst was observed with the low-frequency radio experimentation ISEE-3 satellite. The mass ejection was associated with the eruption of a large solar quiescent filament that lay well away from any active regions. The eruption resulted in a H-alpha double-ribbon structure which straddled the magnetic inversion line. No impulsive phase was obvious in either the H-alpha or the microwave observations. The event indicates that neither a detectable impulsive phase nor a strong or complex magnetic field is necessary for the production of energetic ions.

  11. Filament wound data base development, revision 1

    Science.gov (United States)

    Sharp, R. Scott; Braddock, William F.

    1985-01-01

    The objective was to update the present Space Shuttle Solid Rocket Booster (SRB) baseline reentry aerodynamic data base and to develop a new reentry data base for the filament wound case SRB along with individual protuberance increments. Lockheed's procedures for performing these tasks are discussed. Free fall of the SRBs after separation from the Space Shuttle Launch Vehicle is completely uncontrolled. However, the SRBs must decelerate to a velocity and attitude that is suitable for parachute deployment. To determine the SRB reentry trajectory parameters, including the rate of deceleration and attitude history during free-fall, engineers at Marshall Space Flight Center are using a six-degree-of-freedom computer program to predict dynamic behavior. Static stability aerodynamic coefficients are part of the information required for input into this computer program. Lockheed analyzed the existing reentry aerodynamic data tape (Data Tape 5) for the current steel case SRB. This analysis resulted in the development of Data Tape 7.

  12. Bending artificial muscle from nylon filaments

    Science.gov (United States)

    Mirvakili, Seyed M.; Hunter, Ian W.

    2016-04-01

    Highly oriented nylon and polyethylene fibers shrink in length and expand in diameter when heated. Using this property, in this work, for the first time we are introducing a type of bending artificial muscle from nylon filaments such as fishing line. Reversible radius of curvature of 0.23 mm-1 was achieved with maximum reversible bending amplitude of 115 mm for the nylon bending actuator. Peak force of up to 2040 mN was measured with a catch-state force of up to 40% of the active force. A 3 dB roll-off frequency of around 0.7 Hz was observed in the frequency response of the bending actuator in water.

  13. Radial interchange motions of plasma filaments

    DEFF Research Database (Denmark)

    Garcia, O.E.; Bian, N.H.; Fundamenski, W.

    2006-01-01

    Radial convection of isolated filamentary structures due to interchange motions in magnetized plasmas is investigated. Following a basic discussion of vorticity generation, ballooning, and the role of sheaths, a two-field interchange model is studied by means of numerical simulations...... on a biperiodic domain perpendicular to the magnetic field. It is demonstrated that a blob-like plasma structure develops dipolar vorticity and electrostatic potential fields, resulting in rapid radial acceleration and formation of a steep front and a trailing wake. While the dynamical evolution strongly depends...... as the acoustic speed times the square root of the structure size relative to the length scale of the magnetic field. The plasma filament eventually decelerates due to mixing and collisional dissipation. Finally, the role of sheath dissipation is investigated. When included in the simulations, it significantly...

  14. Validation of the filament winding process model

    Science.gov (United States)

    Calius, Emilo P.; Springer, George S.; Wilson, Brian A.; Hanson, R. Scott

    1987-01-01

    Tests were performed toward validating the WIND model developed previously for simulating the filament winding of composite cylinders. In these tests two 24 in. long, 8 in. diam and 0.285 in. thick cylinders, made of IM-6G fibers and HBRF-55 resin, were wound at + or - 45 deg angle on steel mandrels. The temperatures on the inner and outer surfaces and inside the composite cylinders were recorded during oven cure. The temperatures inside the cylinders were also calculated by the WIND model. The measured and calculated temperatures were then compared. In addition, the degree of cure and resin viscosity distributions inside the cylinders were calculated for the conditions which existed in the tests.

  15. Introduction to vortex filaments in equilibrium

    CERN Document Server

    Andersen, Timothy D

    2014-01-01

    This book presents fundamental concepts and seminal results to the study of vortex filaments in equilibrium. It also presents new discoveries in quasi-2D vortex structures with applications to geophysical fluid dynamics and magnetohydrodynamics in plasmas.  It fills a gap in the vortex statistics literature by simplifying the mathematical introduction to this complex topic, covering numerical methods, and exploring a wide range of applications with numerous examples. The authors have produced an introduction that is clear and easy to read, leading the reader step-by-step into this topical area. Alongside the theoretical concepts and mathematical formulations, interesting applications are discussed. This combination makes the text useful for students and researchers in mathematics and physics.

  16. Natural Fiber Filament Wound Composites: A Review

    Directory of Open Access Journals (Sweden)

    Mohamed Ansari Suriyati

    2017-01-01

    Full Text Available In recent development, natural fibers have attracted the interest of engineers, researchers, professionals and scientists all over the world as an alternative reinforcement for fiber reinforced polymer composites. This is due to its superior properties such as high specific strength, low weight, low cost, fairly good mechanical properties, non-abrasive, eco-friendly and bio-degradable characteristics. In this point of view, natural fiber-polymer composites (NFPCs are becoming increasingly utilized in a wide variety of applications because they represent an ecological and inexpensive alternative to conventional petroleum-derived materials. On the other hand, considerable amounts of organic waste and residue from the industrial and agricultural processes are still underutilized as low-value energy sources. This is a comprehensive review discussing about natural fiber reinforced composite produced by filament winding technique.

  17. Possible association of actin filaments with chloroplasts of spinach mesophyll cells in vivo and in vitro.

    Science.gov (United States)

    Kumatani, T; Sakurai-Ozato, N; Miyawaki, N; Yokota, E; Shimmen, T; Terashima, I; Takagi, S

    2006-11-01

    In palisade mesophyll cells of spinach (Spinacia oleracea L.) kept under low-intensity white light, chloroplasts were apparently immobile and seemed to be surrounded by fine bundles of actin filaments. High-intensity blue light induced actin-dependent chloroplast movement concomitant with the appearance of a couple of long, straight bundles of actin filaments in each cell, whereas high-intensity red light was essentially ineffective in inducing these responses. The actin organization observed under low-intensity white light has been postulated to function in anchoring chloroplasts at proper intracellular positions through direct interaction with the chloroplasts. Intact chloroplasts, which retained their outer envelopes, were isolated after homogenization of leaves and Percoll centrifugation. No endogenous actin was detected by immunoblotting in the final intact-chloroplast fraction prepared from the leaves kept under low-intensity white light or in darkness. In cosedimentation assays with exogenously added skeletal muscle filamentous actin, however, actin was detected in the intact-chloroplast fraction precipitated after low-speed centrifugation. The association of actin with chloroplasts was apparently dependent on incubation time and chloroplast density. After partial disruption of the outer envelope of isolated chloroplasts by treatment with trypsin, actin was no longer coprecipitated. The results suggest that chloroplasts in spinach leaves can directly interact with actin, and that this interaction may be involved in the regulation of intracellular positioning of chloroplasts.

  18. Quantification of filamentation by uropathogenic Escherichia coli during experimental bladder cell infection by using semi-automated image analysis

    DEFF Research Database (Denmark)

    Klein, Kasper; Palarasah, Yaseelan; Kolmos, Hans Jørn

    2015-01-01

    Several rod-shaped pathogens including Escherichia coli, Salmonella spp. and Klebsiella pneumonia are capable of adopting highly filamentous cell shapes under certain circumstances. This phenomenon occurs as a result of continued cell elongation during growth without the usual septation into single...... rod-shaped cells. Evidence has emerged over the past decade suggesting that this morphological transformation is controlled and reversible and provides selective advantages under certain growth conditions, such as during infection in humans. In order to identify the factors which induce filamentation...... of bacterial pathogens and study the advantages of bacterial morphological plasticity, methods are needed to accurately quantify changes in bacterial cell shape. In this study, we present a method for quantification of bacterial filamentation based on automatic detection and measurement of bacterial units...

  19. Regular ‘breathing’ of a near-single-cycle light bullet in mid-IR filament

    Science.gov (United States)

    Chekalin, S. V.; Kompanets, V. O.; Kuznetsov, A. V.; Dormidonov, A. E.; Kandidov, V. P.

    2016-06-01

    Experimental and numerical studies of a temporal evolution of a light bullet formed in isotropic LiF by mid-IR femtosecond pulse (2600-3350 nm) of power, slightly exceeding the critical power for self-focusing, are presented. For the first time regular oscillations of the light bullet field peak amplitude during its propagation in a filament were registered by investigation of induced color centers in LiF. It was revealed that color centers in a single laser pulse filament have the strictly periodic structure with a length of separate sections about 30 μm, which increases with a laser pulse wavelength decreasing. It was shown that the origin of a light bullet modulation is a periodical change of the light field amplitude of a near single-cycle wave packet in a filament, due to a difference of the wave packet group velocity and the carrier wave phase velocity.

  20. A voz de Capitu na crítica-ficção: relações entre Dom Casmurro e Capitu – memórias póstumas

    OpenAIRE

    2013-01-01

    Esta tese perscruta a recepção da personagem Capitu do romance Dom Casmurro (1899), de Machado de Assis, pela crítica-ficção machadiana elaborada em 1998. Trata-se do romance Capitu – memórias póstumas, de Domício Proença Filho. A investigação desenvolvida discute a problemática da noção de autor no âmbito da intertextualidade, enfatizando como, um século depois, as ressignificações da Capitu machadiana se conectam com as tendências estéticas e ideológicas do contexto finissecu...

  1. Ficção científica , cibercultura e pós-modernidade: velocidade e religião no discurso cinematográfico de David Cronenberg videodrome e eXistenZ

    OpenAIRE

    Góes, Maria das Graças Teixeira de Araújo

    2007-01-01

    A pesquisa foi consagrada ao estudo às produções cinematográficas Videodrome e eXistenZ de David Cronenberg. Essas películas estão inseridas no gênero ficção científica, que, na contemporaneidade, adquiriu características peculiares ao representar o presente com conotações futurísticos, como conseqüência de a técnica estar inserida em todos os setores societários. Ao retratar o contexto cultural de época, através de narrativas metafóricas e de imagens bizarras e surreais, os fi...

  2. ¿En qué lenguas se hace ciencia? La gestión del multilingüismo en el Parc Científic de Barcelona

    Directory of Open Access Journals (Sweden)

    F. Xavier Vila

    2015-01-01

    Full Text Available Este estudio investiga los usos lingüísticos en catalán, castellano e inglés de los investigadores del Parc Científic de Barcelona, un entorno con características sociolingüísticas heterogéneas. Los resultados del análisis de conglomerados muestran que el personal investigador (n=179 se estructura alrededor de cuatro grupos según su competencia y usos lingüísticos y proporcionan evidencia de que a en instituciones científicas académicas en entornos multilingües los procesos de cambio lingüístico no se producen de manera compacta y b de que el inglés no se convierte necesariamente en la lengua franca de la institución.

  3. Um olhar sobre a cultura e sociedade em Moçambique: a ficção e a realidade em Niketche: uma história de Poligamia

    OpenAIRE

    Araújo, Erika Tonelli de [UNESP

    2009-01-01

    A presente dissertação “Um olhar sobre a cultura e sociedade em Moçambique: A ficção e a realidade em “Niketche: uma história de Poligamia” pretende realizar uma interpretação de alguns aspectos da realidade da sociedade e cultura contemporânea de Moçambique, especialmente sobre o papel desempenhado pela mulher. Valendo-nos de referências teórico-metodológicas da Sociologia da Literatura e de críticos da literatura africana para realizar o estudo do romance moçambicano Niketche: uma História ...

  4. Relatório de estágio: o processo de produção na série de ficção "Dentro"

    OpenAIRE

    2016-01-01

    O presente relatório tem como principal objetivo descrever o processo de estágio na equipa de produção da série de ficção Dentro, produzida pela HOP! – Henrique Oliveira Produções –, para a RTP. Realizado no âmbito do Mestrado em Comunicação Audiovisual, na vertente de Produção e Realização Audiovisual, ministrado pela Escola Superior de Música, Artes e Espectáculo, o estágio durou sete meses e esteve dividido em três fases distintas: a Pré-produção, a Produção e a Pós-produção. Assim, ...

  5. Fusion of regularized femtosecond filaments in air: far field on-axis emission

    Science.gov (United States)

    Shipilo, D. E.; Panov, N. A.; Sunchugasheva, E. S.; Mokrousova, D. V.; Andreeva, V. A.; Kosareva, O. G.; Seleznev, L. V.; Savel'ev, A. B.; Ionin, A. A.; Chin, S. L.

    2016-11-01

    The fusion of several coherent 800 nm femtosecond filaments is induced experimentally and numerically by transmitting a beam through a mask with circular apertures followed by the focusing lens. The far-field image of the four-filament fusion region reveals bright on-axis maximum and differs drastically from the diffraction pattern of a low energy beam propagating through the mask in the linear regime. In 3D+time numerical simulations with the carrier wave resolved we show a factor-of-5 saturable growth in the peak plasma density with successive increase in the number of mask openings. An overall spectral blueshift of the fundamental and the third harmonics follows the plasma density increase. The simulated far-field on-axis emission agrees with the experiment and serves as the indication of nonlinear interaction in the fusion region.

  6. The Selective Autophagy Receptor p62 Forms a Flexible Filamentous Helical Scaffold

    Directory of Open Access Journals (Sweden)

    Rodolfo Ciuffa

    2015-05-01

    Full Text Available The scaffold protein p62/SQSTM1 is involved in protein turnover and signaling and is commonly found in dense protein bodies in eukaryotic cells. In autophagy, p62 acts as a selective autophagy receptor that recognizes and shuttles ubiquitinated proteins to the autophagosome for degradation. The structural organization of p62 in cellular bodies and the interplay of these assemblies with ubiquitin and the autophagic marker LC3 remain to be elucidated. Here, we present a cryo-EM structural analysis of p62. Together with structures of assemblies from the PB1 domain, we show that p62 is organized in flexible polymers with the PB1 domain constituting a helical scaffold. Filamentous p62 is capable of binding LC3 and addition of long ubiquitin chains induces disassembly and shortening of filaments. These studies explain how p62 assemblies provide a large molecular scaffold for the nascent autophagosome and reveal how they can bind ubiquitinated cargo.

  7. Coincidències i desavinences entre les estratègies de gestió de biblioteques universitàries i les directrius marcades per consorcis i institucions europees vers el patrimoni bibliogràfic patrimonial

    Directory of Open Access Journals (Sweden)

    Rodrigo Fuentes, Victòria

    2013-12-01

    Full Text Available En aquest estudi volem mostrar com algunes biblioteques, contretament les universitàries, estan gestionant una nova realitat virtual, la que suposa la digitalizació dels seus fons bibliogràfics antics i l'accessibilitat que ofereixen a aquests documents a través d'Internet. Les biblioteques seleccionades per aquest treball són: la Biblioteca de la Universidad Complutense de Madrid, la Biblioteca de la Universitat de Barcelona i la Bibliothèque de la Sorbonne Universités de Paris, totes elles referents per la seva col•lecció de patrimoni bibliogràfic. Analitzarem i compararem les diferents estratègies que segueixen aquestes institucions per dur a terme la gestió dels seus fons patrimonials. Així com tractarem el suport que reben aquestes dels organismes que les representen i com l'apliquen en els seus plans de treball. Ens referim als consorcis als que pertanyen, el Consorci de Biblioteques Universitàries de Catalunya, REBIUN, el Consortium universitaire de périodiques numériques (Couperin i l'associació League Bibliothèques Europeennes de Recherche. També volem mostrar la correlació existent entre els diferents models de gestió i d'organització d'aquestes biblioteques. Maneres de fer diferents, tot i estar emparades sota les mateixes directrius europees. En aquests informe no ens oblidarem dels usuaris d'aquestes institucions, especialment aquells que estan abocats a la recerca i la investigació, i veurem quines institucions orienten les seves estratègies a la cerca de l'excel•lència dels serveis que ofereixen.

  8. Campylobacter fetus subspecies contain conserved type IV secretion systems on multiple genomic islands and plasmids

    NARCIS (Netherlands)

    Graaf-Van Bloois, Van Der Linda; Miller, William G.; Yee, Emma; Wagenaar, Jaap A.

    2016-01-01

    The features contributing to differences in pathogenicity of the Campylobacter fetus subspecies are unknown. Putative factors involved in pathogenesis are located in genomic islands that encode a type IV secretion system (T4SS) and fic domain (filamentation induced by cyclic AMP) proteins, which

  9. Fossil evidence for spin alignment of SDSS galaxies in filaments

    CERN Document Server

    Jones, Bernard J T; Aragon-Calvo, Miguel A

    2010-01-01

    We search for and find fossil evidence that the distribution of the spin axes of galaxies in cosmic web filaments relative to their host filaments are not randomly distributed. This would indicate that the action of large scale tidal torques effected the alignments of galaxies located in cosmic filaments. To this end, we constructed a catalogue of clean filaments containing edge-on galaxies. We started by applying the Multiscale Morphology Filter (MMF) technique to the galaxies in a redshift-distortion corrected version of the Sloan Digital Sky Survey DR5. From that sample we extracted those 426 filaments that contained edge-on galaxies (b/a < 0.2). These filaments were then visually classified relative to a variety of quality criteria. Statistical analysis using "feature measures" indicates that the distribution of orientations of these edge-on galaxies relative to their parent filament deviate significantly from what would be expected on the basis of a random distribution of orientations. The interpretat...

  10. An observational detection of the bridge effect of void filaments

    CERN Document Server

    Shim, Junsup; Hoyle, Fiona

    2015-01-01

    The bridge effect of void filaments is a phrase coined by Park & Lee (2009b) to explain the correlations found in a numerical experiment between the luminosity of the void galaxies and the degree of the straightness of their host filaments. Their numerical finding implies that a straight void filament provides a narrow channel for the efficient transportation of gas and matter particles from the surroundings into the void galaxies. To observationally confirm the presence of the bridge effect of void filaments, we identify the filamentary structures from the Sloan void catalog and determine the specific size of each void filament as a measure of its straightness. Using both classical and Bayesian statistics, we indeed detect a strong tendency that the void galaxies located in the more straight filaments are on average more luminous, which is in agreement with the numerical prediction. It is also shown that the strength of correlation increases with the spatial extent of the void filaments, which can be phy...

  11. Structure and assembly of calf hoof keratin filaments.

    Science.gov (United States)

    Sayers, Z; Michon, A M; Sicre, P; Koch, M H

    1990-05-01

    Keratin filament polypeptides were purified from calf hoof stratum corneum with the aim of studying the in vitro assembly process and determining structural parameters of reconstituted filaments. Anion exchange chromatography was used to obtain the most complete fractionation and identification of the acidic and basic components in the purified polypeptide mixture to date. The reassembly products of the fractionated components were investigated by electron microscopy. Fully reconstituted filaments yield homogeneous solutions, and values of 9.8 nm for the filament diameter and 25 kDa/nm for the mass per unit length (M/L) were obtained by X-ray solution scattering. The structures formed in solution at various stages of filament assembly were not sufficiently homogeneous to be studied by this technique. X-ray diffraction patterns from native stratum corneum display strong maxima at 3.6 and 5.4 nm. Contrary to previous reports, these maxima do not appear to be due to lipids since they are also observed with delipidated rehydrated specimens. A series of weak maxima is also detected in the patterns of dry tissue. The absence of these features in the patterns of reconstituted filaments suggests that, in contrast to some electron microscopic observations, there are no prominent regularities in the structure of calf hoof keratin filaments.

  12. MUSE discovers perpendicular arcs in Cen A inner filament

    CERN Document Server

    Hamer, Stephen; Combes, Francoise; Salomé, Quentin

    2014-01-01

    Evidence of AGN interaction with the intergalactic medium is observed in some galaxies and many cool core clusters. Radio-jets are suspected to dig large cavities into the surrounding gas. In most cases, very large optical filaments (several kpc) are also seen all around the central galaxy. The origin of these filaments is still not understood. Star forming regions are sometimes observed inside the filaments and are interpreted as evidence of positive feedback (AGN-triggered star formation). Cen A is a very nearby galaxy with huge optical filaments aligned with AGN radio-jet direction. Here, we search for line ratio variations along the filaments, kinematic evidence of shock-broadend line widths and large scale dynamical structures. We observe a 1'x1' region around the inner filament of Cen A with MUSE on the VLT during the Science Verification period. The brightest lines are the Halpha, [NII], [OIII] and [SII]. MUSE shows that the filaments are made of clumpy structures inside a more diffuse medium aligned w...

  13. Origin of the dense core mass function in contracting filaments

    CERN Document Server

    Myers, Philip C

    2013-01-01

    Mass functions of starless dense cores (CMFs) may arise from contraction and dispersal of core-forming filaments. In an illustrative model, a filament contracts radially by self-gravity, increasing the mass of its cores. During this contraction, FUV photoevaporation and ablation by shocks and winds disperse filament gas and limit core growth. The stopping times of core growth are described by a waiting-time distribution. The initial filament column density profile and the resulting CMF each match recent Herschel observations in detail. Then low-mass cores have short growth ages and arise from the innermost filament gas, while massive cores have long growth ages and draw from more extended filament gas. The model fits the initial density profile and CMF best for mean core density 2 10^4 cm^-3 and filament dispersal time scale 0.5 Myr. Then the typical core mass, radius, mean column density, and contraction speed are respectively 0.8 solar masses, 0.06 pc, 6 10^21 cm^-2, and 0.07 km s^-1, also in accord with ob...

  14. Is Gravitational Lensing by Intercluster Filaments Always Negligible?

    CERN Document Server

    Xu, Dong; Shan, HuanYuan; Famaey, Benoit; Limousin, Marceau; Zhao, HongSheng

    2007-01-01

    Intercluster filaments negligibly contribute to the weak lensing signal in General Relativity (GR), $\\gamma_{N}\\sim 10^{-4}-10^{-3}$. In the context of relativistic Modified Newtonian Dynamics (MOND) (Bekenstein 2004), however, a single filament inclined by $\\approx 45^\\circ$ from the line of sight can cause substantial distortion of background sources pointing towards the filament's axis ($\\kappa=\\gamma=(1-A^{-1})/2\\sim 0.01$); this is rigourous for infinitely long uniform filaments, but also qualitatively true for short filaments ($\\sim 30$Mpc), and even in regions where the projected matter density of the filament equals to zero. Since galaxies and galaxy clusters are generally embedded in filaments or are projected on such structures, this contribution complicates the interpretation of the weak lensing shear map in the context of MOND. While our analysis is of mainly theoretical interest providing order-of-magnitude estimates only, it seems safe to conclude that when modeling systems with anomalous weak l...

  15. The supramolecular organization of the C. elegans nuclear lamin filament.

    Science.gov (United States)

    Ben-Harush, Kfir; Wiesel, Naama; Frenkiel-Krispin, Daphna; Moeller, Dorothee; Soreq, Eyal; Aebi, Ueli; Herrmann, Harald; Gruenbaum, Yosef; Medalia, Ohad

    2009-03-13

    Nuclear lamins are involved in most nuclear activities and are essential for retaining the mechano-elastic properties of the nucleus. They are nuclear intermediate filament (IF) proteins forming a distinct meshwork-like layer adhering to the inner nuclear membrane, called the nuclear lamina. Here, we present for the first time, the three-dimensional supramolecular organization of lamin 10 nm filaments and paracrystalline fibres. We show that Caenorhabditis elegans nuclear lamin forms 10 nm IF-like filaments, which are distinct from their cytoplasmic counterparts. The IF-like lamin filaments are composed of three and four tetrameric protofilaments, each of which contains two partially staggered anti-parallel head-to-tail polymers. The beaded appearance of the lamin filaments stems from paired globular tail domains, which are spaced regularly, alternating between 21 nm and 27 nm. A mutation in an evolutionarily conserved residue that causes Hutchison-Gilford progeria syndrome in humans alters the supramolecular structure of the lamin filaments. On the basis of our structural analysis, we propose an assembly pathway that yields the observed 10 nm IF-like lamin filaments and paracrystalline fibres. These results serve also as a platform for understanding the effect of laminopathic mutations on lamin supramolecular organization.

  16. Investigating the Global Collapse of Filaments Using Smoothed Particle Hydrodynamics

    CERN Document Server

    Clarke, Seamus D

    2015-01-01

    We use Smoothed Particle Hydrodynamic simulations of cold, uniform density, self-gravitating filaments, to investigate their longitudinal collapse timescales; these timescales are important because they determine the time available for a filament to fragment into cores. A filament is initially characterised by its line-mass, $\\mu$, its radius, $R$ (or equivalently its density $\\rho\\!=\\!\\mu/\\pi R^2$), and its aspect ratio, $A\\;\\,(\\equiv Z/R$, where $Z$ is its half-length). The gas is only allowed to contract longitudinally, i.e. parallel to the symmetry axis of the filament (the $z$-axis). Pon et al. (2012) have considered the global dynamics of such filaments analytically. They conclude that short filaments ($A\\! \\!5$) undergo end-dominated collapse, i.e. two dense clumps form at the ends of the filament and converge on the centre sweeping up mass as they go, on a time-scale $t_{_{\\rm END}} \\sim 0.98\\,A^{1/2}\\,(G\\rho)^{-1/2}$. Our simulations do not corroborate these predictions. First, for all $A\\! > \\!2$, ...

  17. Properties of the cosmological filament between two clusters: A possible detection of a large-scale accretion shock by Suzaku

    Science.gov (United States)

    Akamatsu, H.; Fujita, Y.; Akahori, T.; Ishisaki, Y.; Hayashida, K.; Hoshino, A.; Mernier, F.; Yoshikawa, K.; Sato, K.; Kaastra, J. S.

    2017-09-01

    We report on the results of a Suzaku observation of the plasma in the filament located between the two massive clusters of galaxies, Abell 399 and Abell 401. Abell 399 (z = 0.0724) and Abell 401 (z = 0.0737) are expected to be in the initial phase of a cluster merger. In the region between the two clusters, we find a clear enhancement in the temperature of the filament plasma from 4 keV (expected value of a typical cluster temperature profile) to kT 6.5 keV. Our analysis also shows that filament plasma is present out to a radial distance of 15' (1.3 Mpc) from a line connecting the two clusters. The temperature profile is characterized by an almost flat radial shape with kT 6-7 keV within 10' or 0.8 Mpc. Across r = 8' from the axis, the temperature of the filament plasma shows a drop from 6.3 keV to 5.1 keV, indicating the presence of a shock front. The Mach number based on the temperature drop is estimated to be ℳ 1.3. We also successfully determined the abundance profile up to 15' (1.3 Mpc), showing an almost constant value (Z = 0.3 solar) at the cluster outskirts. We estimated the Compton y parameter to be 14.5 ± 1.3 × 10-6, which is in agreement with the Planck results (14-17 × 10-6 on the filament). The line-of-sight depth of the filament is l 1.1 Mpc, which indicates that the geometry of filament is likely a pancake shape rather than cylindrical. The total mass of the filamentary structure is 7.7 × 1013M⊙. We discuss a possible interpretation of the drop of X-ray emission at the rim of the filament, which was pushed out by the merging activity and formed by the accretion flow induced by the gravitational force of the filament.

  18. Formation of interstellar filaments: the role of magnetic fields

    Science.gov (United States)

    Ntormousi, Evangelia; Hennebelle, Patrick

    2014-07-01

    The filamentary structure of interstellar matter and its potential link to star formation has been brought back into focus recently by high resolution observational surveys. The densest of these filaments host pre-stellar and star forming cores, so explaining their properties is tightly correlated to revealing the initial conditions for star formation. To that end, in this work we employ high-resolution, 3D MHD simulations performed with the AMR code RAMSES to investigate two filament formation mechanisms: turbulence and sheet fragmentation. The first series of simulations has as a particular aim to address the origin of the characteristic filament thickness found in observations. Starting from the hypothesis that diffusive processes are responsible, our numerical experiments consist of (driven or decaying) ideal and non-ideal MHD turbulence, at a resolution that greatly exceeds the reported 0.1pc thickness. The comparison points to ion-neutral friction as an excellent candidate for setting a characteristic scale. In this picture dense filaments are the diffusive end of the turbulent cascade, an interpretation with important implications for our understanding of the dynamical behavior of the ISM. A second series of simulations investigates filament formation by the fragmentation of supershells, a scenario inspired by the analytical work of Nagai (1998). We find a striking difference between hydrodynamical and MHD runs as in the first case the sheets fragment into small cores, while in the latter they produce large filaments. In addition though, we see that low-density filaments preferentially form along the dominant component of the magnetic field. In this scenario filaments are prominent features in the ISM, but their fate is still determined by the local magnetic field. A detailed comparison of the filament properties between the two runs is work in progress and will reveal the physical mechanisms responsible for shaping the ISM and setting the initial conditions

  19. Magnetic Structure of a Filament during its Phase of Activity

    Science.gov (United States)

    Sasso, C.; Lagg, A.; Solanki, S. K.

    2008-09-01

    We analyze and interpret spectropolarimetric observations of an active region filament located close to the solar disc center, during its phase of activity. The observations are obtained in the chromospheric He I lines at 1083.0 nm. We provide novel observational results on the magnetic field measurements in solar filaments to give constraints to the theoretical models of their support in the solar corona. Our main goal is to interpret the behavior of the atmospheric parameters retrieved from the spectropolarimetric data to give a picture of the magnetic structure of the observed filament. The analysis of the observed polarization of the He I 1083.0 nm multiplet in the filament, carried out by inverting the Stokes profiles, reveals the presence of different unresolved atmospheric components of the He lines, coexisting within the resolution element (1.2 arcsec). The different components, belonging to different magnetic field lines, show supersonic up- and downflows, sometimes within the same resolution element. The He blueshifted components belong to mostly transversal field lines in the body of the filament. These field lines are found to be curving upwards on both sides. This picture suggests the presence of dipped field lines that are moving upward, carrying with them the filament material. During this movement, we also observe filament material flowing down along field lines having the same polarity as the photospheric field (i.e. they have the opposite inclination with respect to the dipped field lines). These downflows are faster at the filament end points and can reach values close to 10 times the speed of sound. The field lines are found to be almost parallel to the filament axis in the plane perpendicular to the line of sight. We use the two main theoretical models of prominence support (dip or flux rope models) to interpret the results obtained.

  20. Multiscale modeling and mechanics of filamentous actin cytoskeleton.

    Science.gov (United States)

    Yamaoka, Hidetaka; Matsushita, Shinji; Shimada, Yoshitaka; Adachi, Taiji

    2012-03-01

    The adaptive structure and functional changes of the actin cytoskeleton are induced by its mechanical behavior at various temporal and spatial scales. In particular, the mechanical behaviors at different scales play important roles in the mechanical functions of various cells, and these multiscale phenomena require clarification. To establish a milestone toward achieving multiscale modeling and simulation, this paper reviews mathematical analyses and simulation methods applied to the mechanics of the filamentous actin cytoskeleton. The actin cytoskeleton demonstrates characteristic behaviors at every temporal and spatial scale, and mathematical models and simulation methods can be applied to each level of actin cytoskeletal structure ranging from the molecular to the network level. This paper considers studies on mathematical models and simulation methods based on the molecular dynamics, coarse-graining, and continuum dynamics approaches. Every temporal and spatial scale of actin cytoskeletal structure is considered, and it is expected that discrete and continuum dynamics ranging from functional expression at the molecular level to macroscopic functional expression at the whole cell level will be developed and applied to multiscale modeling and simulation.

  1. The Use of Withaferin A to Study Intermediate Filaments.

    Science.gov (United States)

    Mohan, Royce; Bargagna-Mohan, Paola

    2016-01-01

    Withaferin A (WFA), initially identified as a compound that inhibits experimental angiogenesis, has been shown to bind to soluble vimentin (sVim) and other type III intermediate filament (IF) proteins. We review WFA's dose-related activities (Section 1), examining nanomolar concentrations effects on sVim in cell proliferation and submicromolar effects on lamellipodia and focal adhesion formation. WFA effects on polymeric IFs are especially interesting to the study of cell migration and invasion that depend on IF mechanical contractile properties. WFA interferes with NF-κB signaling, though this anti-inflammatory mechanism may occur via perturbation of sVim-protein complexes, and possibly also via targeting IκB kinase β directly. However, micromolar concentrations that induce vimentin cleavage to promote apoptosis may increasingly show off-target effects via targeting other IFs (neurofilaments and keratin) and non-IFs (tubulin, heat-shock proteins, proteasome). Thus, in Section 2, we describe our studies combining cell cultures with animal models of injury to validate relevant type III IF-targeting mechanisms of WFA. In Section 3, we illuminate from investigating myofibroblast differentiation how sVim phosphorylation may govern cell type-selective sensitivity to WFA, offering impetus for exploring vimentin phosphorylation isoforms as targets and biomarkers of fibrosis. These different WFA targets and activities are listed in a summary table.

  2. Ndel1 promotes axon regeneration via intermediate filaments.

    Directory of Open Access Journals (Sweden)

    Cory Toth

    Full Text Available Failure of axons to regenerate following acute or chronic neuronal injury is attributed to both the inhibitory glial environment and deficient intrinsic ability to re-grow. However, the underlying mechanisms of the latter remain unclear. In this study, we have investigated the role of the mammalian homologue of aspergillus nidulans NudE, Ndel1, emergently viewed as an integrator of the cytoskeleton, in axon regeneration. Ndel1 was synthesized de novo and upregulated in crushed and transected sciatic nerve axons, and, upon injury, was strongly associated with neuronal form of the intermediate filament (IF Vimentin while dissociating from the mature neuronal IF (Neurofilament light chain NF-L. Consistent with a role for Ndel1 in the conditioning lesion-induced neurite outgrowth of Dorsal Root Ganglion (DRG neurons, the long lasting in vivo formation of the neuronal Ndel1/Vimentin complex was associated with robust axon regeneration. Furthermore, local silencing of Ndel1 in transected axons by siRNA severely reduced the extent of regeneration in vivo. Thus, Ndel1 promotes axonal regeneration; activating this endogenous repair mechanism may enhance neuroregeneration during acute and chronic axonal degeneration.

  3. HIERARCHICAL FRAGMENTATION OF THE ORION MOLECULAR FILAMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Satoko; Ho, Paul T. P.; Su, Yu-Nung [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Teixeira, Paula S. [Institut fuer Astrophysik, Universitaet Wien, Tuerkenschanzstrasse 17, A-1180, Wien (Austria); Zapata, Luis A., E-mail: satoko_t@asiaa.sinica.edu.tw [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Morelia, Michoacan 58090 (Mexico)

    2013-01-20

    We present a high angular resolution map of the 850 {mu}m continuum emission of the Orion Molecular Cloud-3 (OMC 3) obtained with the Submillimeter Array (SMA); the map is a mosaic of 85 pointings covering an approximate area of 6.'5 Multiplication-Sign 2.'0 (0.88 Multiplication-Sign 0.27 pc). We detect 12 spatially resolved continuum sources, each with an H{sub 2} mass between 0.3-5.7 M {sub Sun} and a projected source size between 1400-8200 AU. All the detected sources are on the filamentary main ridge (n{sub H{sub 2}}{>=}10{sup 6} cm{sup -3}), and analysis based on the Jeans theorem suggests that they are most likely gravitationally unstable. Comparison of multi-wavelength data sets indicates that of the continuum sources, 6/12 (50%) are associated with molecular outflows, 8/12 (67%) are associated with infrared sources, and 3/12 (25%) are associated with ionized jets. The evolutionary status of these sources ranges from prestellar cores to protostar phase, confirming that OMC-3 is an active region with ongoing embedded star formation. We detect quasi-periodical separations between the OMC-3 sources of Almost-Equal-To 17''/0.035 pc. This spatial distribution is part of a large hierarchical structure that also includes fragmentation scales of giant molecular cloud ( Almost-Equal-To 35 pc), large-scale clumps ( Almost-Equal-To 1.3 pc), and small-scale clumps ( Almost-Equal-To 0.3 pc), suggesting that hierarchical fragmentation operates within the Orion A molecular cloud. The fragmentation spacings are roughly consistent with the thermal fragmentation length in large-scale clumps, while for small-scale cores it is smaller than the local fragmentation length. These smaller spacings observed with the SMA can be explained by either a helical magnetic field, cloud rotation, or/and global filament collapse. Finally, possible evidence for sequential fragmentation is suggested in the northern part of the OMC-3 filament.

  4. Organic Acid Production by Filamentous Fungi

    Energy Technology Data Exchange (ETDEWEB)

    Magnuson, Jon K.; Lasure, Linda L.

    2004-05-03

    Many of the commercial production processes for organic acids are excellent examples of fungal biotechnology. However, unlike penicillin, the organic acids have had a less visible impact on human well-being. Indeed, organic acid fermentations are often not even identified as fungal bioprocesses, having been overshadowed by the successful deployment of the β-lactam processes. Yet, in terms of productivity, fungal organic acid processes may be the best examples of all. For example, commercial processes using Aspergillus niger in aerated stirred-tank-reactors can convert glucose to citric acid with greater than 80% efficiency and at final concentrations in hundreds of grams per liter. Surprisingly, this phenomenal productivity has been the object of relatively few research programs. Perhaps a greater understanding of this extraordinary capacity of filamentous fungi to produce organic acids in high concentrations will allow greater exploitation of these organisms via application of new knowledge in this era of genomics-based biotechnology. In this chapter, we will explore the biochemistry and modern genetic aspects of the current and potential commercial processes for making organic acids. The organisms involved, with a few exceptions, are filamentous fungi, and this review is limited to that group. Although yeasts including Saccharomyces cerevisiae, species of Rhodotorula, Pichia, and Hansenula are important organisms in fungal biotechnology, they have not been significant for commercial organic acid production, with one exception. The yeast, Yarrowia lipolytica, and related yeast species, may be in use commercially to produce citric acid (Lopez-Garcia, 2002). Furthermore, in the near future engineered yeasts may provide new commercial processes to make lactic acid (Porro, Bianchi, Ranzi, Frontali, Vai, Winkler, & Alberghina, 2002). This chapter is divided into two parts. The first contains a review of the commercial aspects of current and potential large

  5. Failure and nonfailure of fluid filaments in extension

    DEFF Research Database (Denmark)

    Hassager, Ole; Kolte, Mette Irene; Renardy, Michael

    1998-01-01

    fluid filaments do not exhibit ductile failure without surface tension; (2) some viscoelastic fluids form stable filaments while other fluids exhibit ductile failure as a result of an elastic instability; (3) for large Deborah numbers, the Considere condition may be used to predict the Hencky strain......The phenomenon of ductile failure of Newtonian and viscoelastic fluid filaments without surface tension is studied by a 2D finite element method and by ID non-linear analysis. The viscoelastic fluids are described by single integral constitutive equations. The main conclusions are: (1) Newtonian...

  6. Is the periplasm continuous in filamentous multicellular cyanobacteria?

    Science.gov (United States)

    Flores, Enrique; Herrero, Antonia; Wolk, C Peter; Maldener, Iris

    2006-10-01

    Filamentous, heterocyst-forming cyanobacteria are multicellular organisms in which individual cells exchange nutrients and, presumably, regulatory molecules. Unknown mechanisms underlie this exchange. Classical electron microscopy shows that filamentous cyanobacteria bear a Gram-negative cell wall comprising a peptidoglycan layer and an outer membrane that are external to the cytoplasmic membrane, and that the outer membrane appears to be continuous along the filament of cells. This implies that the periplasmic space between the cytoplasmic and outer membranes might also be continuous. We propose that a continuous periplasm could constitute a communication conduit for the transfer of compounds, which is essential for the performance of these bacteria as multicellular organisms.

  7. Forced motion of an elastic filament through a narrow tube

    Science.gov (United States)

    Freund, L. B.

    2015-12-01

    A polymer filament consisting of many similar molecules linked in a one-dimensional array is very flexible. As a result, shapes with a relatively large curvature can be accommodated elastically. When loosely confined in a thermal environment, such a flexible strand may become tangled owing to its flexibility. When confined within a narrow "tube" over its full length, a flexible molecule may behave quite differently. Here, we consider the qualitative nature of deformation of an individual filament when confined within a tube. Commonly the tube is formed within the cluster by a large number of surrounding filaments of the same type.

  8. Nonlinearly enhanced linear absorption under filamentation in mid-infrared (Conference Presentation)

    Science.gov (United States)

    Shipilo, Daniil; Panov, Nicolay; Andreeva, Vera; Kosareva, Olga G.; Saletski, Alexander M.; Xu, Huai-Liang; Polynkin, Pavel

    2017-05-01

    The mid-infrared OPCPA-based laser facilities have recently reached the critical power for self-focusing in air [1]. This ensures the demonstration of the major difference between the mid- and near-infrared filamentation in air: the odd optical harmonics, harshly suppressed by the material dispersion and phase-mismatch in the near-infrared (800 nm), gain reliable energies in the mid-infrared (3.9 µm) filament [1,2]. Another issue that makes mid-infrared filamentation different from the near-infrared one is a lot of molecular vibrational lines belonging to atmospheric constituents and located in the mid-infrared range [3]. As the result the mid-infrared region of interest becomes subdivided into the bands of normal and anomalous dispersion, the former of which leads to the pulse splitting in temporal domain, while the latter produces the confined light bullet. We simulate the 3.9-µm filamentation using Forward Maxwell equation. We include the tunnel ionization and transient photocurrent as the collapse arresting mechanism, which balances dynamically the instantaneous third-order medium response (similarly to 800-nm filamentation). The key feature that allows us to quantify the losses due to absorption bands is the accurate account of the complex linear absorption index. The absorption index obtained from Mathar model [3] is interpolated to the fine frequency grid (step of about 0.1 THz), and the refractive index is matched according to Kramers-Krönig relations [4]. If the initial Gaussian pulse has a center wavelength of 3.9 µm and a duration of 80 fs FWHM, the energy loss in the carbon dioxide (CO_2) absorption band at 4.3 µm is about 1% in the linear propagation regime. But when we take the 80-mJ pulse (about 3 critical powers for self-focusing), the Kerr-induced spectral broadening develops significantly before the clamping level of intensity is reached. In the collimated beam geometry about 2% of the initial pulse energy is absorbed on the CO_2 band before

  9. A Comparison Study of a Solar Active-Region Eruptive Filament and a Neighboring Non-Eruptive Filament

    CERN Document Server

    Jiang, Chaowei; Feng, Xueshang; Hu, Qiang

    2015-01-01

    Solar active region (AR) 11283 is a very magnetically complex region and it has produced many eruptions. However, there exists a non-eruptive filament in the plage region just next to an eruptive one in the AR, which gives us an opportunity to perform a comparison analysis of these two filaments. The coronal magnetic field extrapolated using a CESE-MHD-NLFFF code (Jiang & Feng 2013) reveals that two magnetic flux ropes (MFRs) exist in the same extrapolation box supporting these two filaments, respectively. Analysis of the magnetic field shows that the eruptive MFR contains a bald-patch separatrix surface (BPSS) co-spatial very well with a pre-eruptive EUV sigmoid, which is consistent with the BPSS model for coronal sigmoids. The magnetic dips of the non-eruptive MFRs match H{\\alpha} observation of the non-eruptive filament strikingly well, which strongly supports the MFR-dip model for filaments. Compared with the non-eruptive MFR/filament (with a length of about 200 Mm), the eruptive MFR/filament is much ...

  10. The Apis mellifera Filamentous Virus Genome

    Directory of Open Access Journals (Sweden)

    Laurent Gauthier

    2015-07-01

    Full Text Available A complete reference genome of the Apis mellifera Filamentous virus (AmFV was determined using Illumina Hiseq sequencing. The AmFV genome is a double stranded DNA molecule of approximately 498,500 nucleotides with a GC content of 50.8%. It encompasses 247 non-overlapping open reading frames (ORFs, equally distributed on both strands, which cover 65% of the genome. While most of the ORFs lacked threshold sequence alignments to reference protein databases, twenty-eight were found to display significant homologies with proteins present in other large double stranded DNA viruses. Remarkably, 13 ORFs had strong similarity with typical baculovirus domains such as PIFs (per os infectivity factor genes: pif-1, pif-2, pif-3 and p74 and BRO (Baculovirus Repeated Open Reading Frame. The putative AmFV DNA polymerase is of type B, but is only distantly related to those of the baculoviruses. The ORFs encoding proteins involved in nucleotide metabolism had the highest percent identity to viral proteins in GenBank. Other notable features include the presence of several collagen-like, chitin-binding, kinesin and pacifastin domains. Due to the large size of the AmFV genome and the inconsistent affiliation with other large double stranded DNA virus families infecting invertebrates, AmFV may belong to a new virus family.

  11. Cold Milky Way Hi gas in filaments

    CERN Document Server

    Kalberla, P M W; Haud, U; Winkel, B; Bekhti, N Ben; Floeer, L; Lenz, D

    2016-01-01

    We investigate data from the Galactic Effelsberg--Bonn HI Survey (EBHIS), supplemented with data from the third release of the Galactic All Sky Survey (GASS III) observed at Parkes. We explore the all sky distribution of the local Galactic HI gas with $|v_{\\rm LSR}| 20^\\circ$ is described by a log-normal distribution, with a median Doppler temperature $T_{\\rm D} = 223$ K, derived from observed line widths that include turbulent contributions. The median neutral hydrogen (HI) column density is $N_{\\rm HI} \\simeq 10^{19.1}\\,{\\rm cm^{-2}}$. These CNM structures are embedded within a warm neutral medium (WNM) with $N_{\\rm HI} \\simeq 10^{20} {\\rm cm^{-2}}$. Assuming an average distance of 100 pc, we derive for the CNM sheets a thickness of $< 0.3$ pc. Adopting a magnetic field strength of $B_{\\rm tot} = (6.0 \\pm 1.8)\\mu$G, proposed by Heiles & Troland 2005, and assuming that the CNM filaments are confined by magnetic pressure, we estimate a thickness of 0.09 pc. Correspondingly the median volume density is ...

  12. Enhancing Nonribosomal Peptide Biosynthesis in Filamentous Fungi.

    Science.gov (United States)

    Soukup, Alexandra A; Keller, Nancy P; Wiemann, Philipp

    2016-01-01

    Filamentous fungi are historically known as rich sources for production of biologically active natural products, so-called secondary metabolites. One particularly pharmaceutically relevant chemical group of secondary metabolites is the nonribosomal peptides synthesized by nonribosomal peptide synthetases (NRPSs). As most of the fungal NRPS gene clusters leading to production of the desired molecules are not expressed under laboratory conditions, efforts to overcome this impediment are crucial to unlock the full chemical potential of each fungal species. One way to activate these silent clusters is by overexpressing and deleting global regulators of secondary metabolism. The conserved fungal-specific regulator of secondary metabolism, LaeA, was shown to be a valuable target for sleuthing of novel gene clusters and metabolites. Additionally, modulation of chromatin structures by either chemical or genetic manipulation has been shown to activate cryptic metabolites. Furthermore, NRPS-derived molecules seem to be affected by cross talk between the specific gene clusters and some of these metabolites have a tissue- or developmental-specific regulation. This chapter summarizes how this knowledge of different tiers of regulation can be combined to increase production of NRPS-derived metabolites in fungal species.

  13. Molecular phylogeny of metazoan intermediate filament proteins.

    Science.gov (United States)

    Erber, A; Riemer, D; Bovenschulte, M; Weber, K

    1998-12-01

    We have cloned cytoplasmic intermediate filament (IF) proteins from a large number of invertebrate phyla using cDNA probes, the monoclonal antibody IFA, peptide sequence information, and various RT-PCR procedures. Novel IF protein sequences reported here include the urochordata and nine protostomic phyla, i.e., Annelida, Brachiopoda, Chaetognatha, Echiura, Nematomorpha, Nemertea, Platyhelminthes, Phoronida, and Sipuncula. Taken together with the wealth of data on IF proteins of vertebrates and the results on IF proteins of Cephalochordata, Mollusca, Annelida, and Nematoda, two IF prototypes emerge. The L-type, which includes 35 sequences from 11 protostomic phyla, shares with the nuclear lamins the long version of the coil 1b subdomain and, in most cases, a homology segment of some 120 residues in the carboxyterminal tail domain. The S-type, which includes all four subfamilies (types I to IV) of vertebrate IF proteins, lacks 42 residues in the coil 1b subdomain and the carboxyterminal lamin homology segment. Since IF proteins from all three phyla of the chordates have the 42-residue deletion, this deletion arose in a progenitor prior to the divergence of the chordates into the urochordate, cephalochordate, and vertebrate lineages, possibly already at the origin of the deuterostomic branch. Four phyla recently placed into the protostomia on grounds of their 18S rDNA sequences (Brachiopoda, Nemertea, Phoronida, and Platyhelminthes) show IF proteins of the L-type and fit by sequence identity criteria into the lophotrochozoic branch of the protostomia.

  14. Enhancing Nonribosomal Peptide Biosynthesis in Filamentous Fungi

    Science.gov (United States)

    Soukup, Alexandra A.; Keller, Nancy P.; Wiemann, Philipp

    2016-01-01

    Filamentous fungi are historically known as rich sources for production of biologically active natural products, so-called secondary metabolites. One particularly pharmaceutically relevant chemical group of secondary metabolites is the nonribosomal peptides synthesized by nonribosomal peptide synthetases (NRPSs). As most of the fungal NRPS gene clusters leading to production of the desired molecules are not expressed under laboratory conditions, efforts to overcome this impediment are crucial to unlock the full chemical potential of each fungal species. One way to activate these silent clusters is by overexpressing and deleting global regulators of secondary metabolism. The conserved fungal-specific regulator of secondary metabolism, LaeA, was shown to be a valuable target for sleuthing of novel gene clusters and metabolites. Additionally, modulation of chromatin structures by either chemical or genetic manipulation has been shown to activate cryptic metabolites. Furthermore, NRPS-derived molecules seem to be affected by cross talk between the specific gene clusters and some of these metabolites have a tissue- or developmental-specific regulation. This chapter summarizes how this knowledge of different tiers of regulation can be combined to increase production of NRPS-derived metabolites in fungal species. PMID:26831707

  15. Equilibrium theory for braided elastic filaments

    Science.gov (United States)

    van der Heijden, Gert

    Motivated by supercoiling of DNA and other filamentous structures, we formulate a theory for equilibria of 2-braids, i.e., structures formed by two elastic rods winding around each other in continuous contact and subject to a local interstrand interaction. Unlike in previous work no assumption is made on the shape of the contact curve. Rather, this shape is found as part of the solution. The theory is developed in terms of a moving frame of directors attached to one of the strands with one of the directors pointing to the position of the other strand. The constant-distance constraint is automatically satisfied by the introduction of what we call braid strains. The price we pay is that the potential energy involves arclength derivatives of these strains, thus giving rise to a second-order variational problem. The Euler-Lagrange equations for this problem give balance equations for the overall braid force and moment referred to the moving frame as well as differential equations that can be interpreted as effective constitutive relations encoding the effect that the second strand has on the first as the braid deforms under the action of end loads. Simple analytical cases are discussed first and used as starting solutions in parameter continuation studies to compute classes of both open and closed (linked or knotted) braid solutions.

  16. The Apis mellifera Filamentous Virus Genome.

    Science.gov (United States)

    Gauthier, Laurent; Cornman, Scott; Hartmann, Ulrike; Cousserans, François; Evans, Jay D; de Miranda, Joachim R; Neumann, Peter

    2015-07-09

    A complete reference genome of the Apis mellifera Filamentous virus (AmFV) was determined using Illumina Hiseq sequencing. The AmFV genome is a double stranded DNA molecule of approximately 498,500 nucleotides with a GC content of 50.8%. It encompasses 247 non-overlapping open reading frames (ORFs), equally distributed on both strands, which cover 65% of the genome. While most of the ORFs lacked threshold sequence alignments to reference protein databases, twenty-eight were found to display significant homologies with proteins present in other large double stranded DNA viruses. Remarkably, 13 ORFs had strong similarity with typical baculovirus domains such as PIFs (per os infectivity factor genes: pif-1, pif-2, pif-3 and p74) and BRO (Baculovirus Repeated Open Reading Frame). The putative AmFV DNA polymerase is of type B, but is only distantly related to those of the baculoviruses. The ORFs encoding proteins involved in nucleotide metabolism had the highest percent identity to viral proteins in GenBank. Other notable features include the presence of several collagen-like, chitin-binding, kinesin and pacifastin domains. Due to the large size of the AmFV genome and the inconsistent affiliation with other large double stranded DNA virus families infecting invertebrates, AmFV may belong to a new virus family.

  17. Effects of airflow on the distribution of filaments in atmospheric AC dielectric barrier discharge

    Science.gov (United States)

    Fan, Zhihui; Qi, Haicheng; Liu, Yidi; Yan, Huijie; Ren, Chunsheng

    2016-12-01

    Atmospheric-pressure dielectric barrier discharge (DBD) accompanied by airflow has attracted a significant attention for its extensive applications. In this paper, the effects of airflow on the characteristics of the atmospheric air DBD plasma are experimentally investigated using the DBD reactor excited by a 15 kHz AC power source. In order to study the discharge filaments distribution at different flow rates, transparent conductive indium tin oxide film is used as the upper electrode, and quartz glasses are used as insulated dielectrics. Experiment results prove that the breakdown voltage is decreased and more current pulses with declined amplitudes are produced when the airflow is introduced into the discharge gap. It is confirmed that although the discharge seems to be diffuse in the presence of airflow to the naked eyes, the discharge mode remains filamentary in the intensified charge-coupled device images within a single AC cycle. By acquiring the images with a different exposure time, it can be recognized that the discharge filaments move along the flow field direction with a velocity less than the corresponding flow rate. The movement of discharge filaments is attributed to the motion of the charge induced by the airflow.

  18. STEM Analysis of Caenorhabditis elegans muscle thick filaments: evidence for microdifferentiated substructures

    Science.gov (United States)

    Muller, S. A.; Haner, M.; Ortiz, I.; Aebi, U.; Epstein, H. F.

    2001-01-01

    In the thick filaments of body muscle in Caenorhabditis elegans, myosin A and myosin B isoforms and a subpopulation of paramyosin, a homologue of myosin heavy chain rods, are organized about a tubular core. As determined by scanning transmission electron microscopy, the thick filaments show a continuous decrease in mass-per-length (MPL) from their central zones to their polar regions. This is consistent with previously reported morphological studies and suggests that both their content and structural organization are microdifferentiated as a function of position. The cores are composed of a second distinct subpopulation of paramyosin in association with the alpha, beta, and gamma-filagenins. MPL measurements suggest that cores are formed from seven subfilaments containing four strands of paramyosin molecules, rather than the two originally proposed. The periodic locations of the filagenins within different regions and the presence of a central zone where myosin A is located, implies that the cores are also microdifferentiated with respect to molecular content and structure. This differentiation may result from a novel "induced strain" assembly mechanism based upon the interaction of the filagenins, paramyosin and myosin A. The cores may then serve as "differentiated templates" for the assembly of myosin B and paramyosin in the tapering, microdifferentiated polar regions of the thick filaments.

  19. Life without Division: Physiology of Escherichia coli FtsZ-Deprived Filaments

    Science.gov (United States)

    Sánchez-Gorostiaga, Alicia; Palacios, Pilar; Martínez-Arteaga, Rocío; Sánchez, Manuel; Casanova, Mercedes

    2016-01-01

    ABSTRACT When deprived of FtsZ, Escherichia coli cells (VIP205) grown in liquid form long nonseptated filaments due to their inability to assemble an FtsZ ring and their failure to recruit subsequent divisome components. These filaments fail to produce colonies on solid medium, in which synthesis of FtsZ is induced, upon being diluted by a factor greater than 4. However, once the initial FtsZ levels are recovered in liquid culture, they resume division, and their plating efficiency returns to normal. The potential septation sites generated in the FtsZ-deprived filaments are not annihilated, and once sufficient FtsZ is accumulated, they all become active and divide to produce cells of normal length. FtsZ-deprived cells accumulate defects in their physiology, including an abnormally high number of unsegregated nucleoids that may result from the misplacement of FtsK. Their membrane integrity becomes compromised and the amount of membrane proteins, such as FtsK and ZipA, increases. FtsZ-deprived cells also show an altered expression pattern, namely, transcription of several genes responding to DNA damage increases, whereas transcription of some ribosomal or global transcriptional regulators decreases. We propose that the changes caused by the depletion of FtsZ, besides stopping division, weaken the cell, diminishing its resiliency to minor challenges, such as dilution stress. PMID:27729511

  20. The GRF10 homeobox gene regulates filamentous growth in the human fungal pathogen Candida albicans.

    Science.gov (United States)

    Ghosh, Anup K; Wangsanut, Tanaporn; Fonzi, William A; Rolfes, Ronda J

    2015-12-01

    Candida albicans is the most common human fungal pathogen and can cause life-threatening infections. Filamentous growth is critical in the pathogenicity of C. albicans, as the transition from yeast to hyphal forms is linked to virulence and is also a pivotal process in fungal biofilm development. Homeodomain-containing transcription factors have been linked to developmental processes in fungi and other eukaryotes. We report here on GRF10, a homeobox transcription factor-encoding gene that plays a role in C. albicans filamentation. Deletion of the GRF10 gene, in both C. albicans SN152 and BWP17 strain backgrounds, results in mutants with strongly decreased hyphal growth. The mutants are defective in chlamydospore and biofilm formation, as well as showing dramatically attenuated virulence in a mouse infection model. Expression of the GRF10 gene is highly induced during stationary phase and filamentation. In summary, our study emphasizes a new role for the homeodomain-containing transcription factor in morphogenesis and pathogenicity of C. albicans.

  1. Fast Radio Bursts as Probes of Magnetic Fields in Filaments of Galaxies

    CERN Document Server

    Akahori, Takuya; Gaensler, B M

    2016-01-01

    We examine the proposal that the dispersion measures (DMs) and Faraday rotation measures (RMs) of extragalactic linearly-polarized fast radio bursts (FRBs) can be used to probe the intergalactic magnetic field (IGMF) in filaments of galaxies. The DM through the cosmic web is dominated by contributions from the warm-hot intergalactic medium (WHIM) in filaments and from the gas in voids. On the other hand, RM is induced mostly by the hot medium in galaxy clusters, and only a fraction of it is produced in the WHIM. We show that if one excludes FRBs whose sightlines pass through galaxy clusters, the line-of-sight strength of the IGMF in filaments, $B_{||}$, is approximately $C(\\langle 1+z \\rangle/f_{DM})(RM/DM)$, where $C$ is a known constant. Here, {the redshift of the FRB is not required to be known;} $f_{DM}$ is the fraction of total DM due the WHIM, while $\\langle 1+z \\rangle$ is the redshift of interevening gas weighted by the WHIM gas density, both of which can be evaluated for a given cosmology model solel...

  2. Persistence of strain in motor-filament assemblies

    CERN Document Server

    Gopinath, Arvind; Mahadevan, L

    2015-01-01

    Crosslinked semi-flexible and flexible filaments that are actively deformed by molecular motors occur in various natural settings, such as the ordered eukaryotic flagellum, and the disordered cytoskeleton. The deformation of these composite systems is driven by active motor forces and resisted by passive filament elasticity, and structural constraints due to permanent cross-links. Using a mean field theory for a one-dimensional ordered system, we show that the combination of motor activity and finite filament extensibility yields a characteristic persistence length scale over which active strain decays. This decay length is set by the ability of motors to respond to combination of the weak extensional elasticity, passive shear resistance and the viscoelastic properties of the motor assembly, and generalizes the notion of persistence in purely thermal filaments to active systems.

  3. Spin alignment of dark matter haloes in filaments and walls

    CERN Document Server

    Arag'on-Calvo, M A; Jones, B J T; Van der Hulst, T; Arag\\'on-Calvo, Miguel A.; Weygaert, Rien van de; Jones, Bernard J. T.

    2006-01-01

    The MMF technique is used to segment the cosmic web as seen in a cosmological N-body simulation into wall-like and filament-like structures. We find that the spins and shapes of dark matter haloes are significantly correlated with each other and with the orientation of their host structures. The shape orientation is such that the halo minor axes tend to lie perpendicular to the host structure, be it a wall or filament. The orientation of the halo spin vector is mass dependent. Low mass haloes in walls and filaments have a tendency to have their spins oriented within the parent structure, while higher mass haloes in filaments have spins that tend to lie perpendicular to the parent structure.

  4. Filamentous Phages As a Model System in Soft Matter Physics.

    Science.gov (United States)

    Dogic, Zvonimir

    2016-01-01

    Filamentous phages have unique physical properties, such as uniform particle lengths, that are not found in other model systems of rod-like colloidal particles. Consequently, suspensions of such phages provided powerful model systems that have advanced our understanding of soft matter physics in general and liquid crystals in particular. We described some of these advances. In particular we briefly summarize how suspensions of filamentous phages have provided valuable insight into the field of colloidal liquid crystals. We also describe recent experiments on filamentous phages that have elucidated a robust pathway for assembly of 2D membrane-like materials. Finally, we outline unique structural properties of filamentous phages that have so far remained largely unexplored yet have the potential to further advance soft matter physics and material science.

  5. Biofilms from a Brazilian water distribution system include filamentous fungi.

    Science.gov (United States)

    Siqueira, V M; Oliveira, H M B; Santos, C; Paterson, R R M; Gusmão, N B; Lima, N

    2013-03-01

    Filamentous fungi in drinking water can block water pipes, can cause organoleptic biodeterioration, and are a source of pathogens. There are increasing reports of the involvement of the organisms in biofilms. This present study describes a sampling device that can be inserted directly into pipes within water distribution systems, allowing biofilm formation in situ. Calcofluor White M2R staining and fluorescent in situ hybridization with morphological analyses using epifluorescent microscopy were used to analyse biofilms for filamentous fungi, permitting direct observation of the fungi. DAPI (4',6-diamidino-2-phenylindole) was applied to detect bacteria. Filamentous fungi were detected in biofilms after 6 months on coupons exposed to raw water, decanted water and at the entrance of the water distribution system. Algae, yeast, and bacteria were also observed. The role of filamentous fungi requires further investigations.

  6. Elastic response of filamentous networks with compliant crosslinks.

    Science.gov (United States)

    Sharma, A; Sheinman, M; Heidemann, K M; MacKintosh, F C

    2013-11-01

    Experiments have shown that elasticity of disordered filamentous networks with compliant crosslinks is very different from networks with rigid crosslinks. Here, we model and analyze filamentous networks as a collection of randomly oriented rigid filaments connected to each other by flexible crosslinks that are modeled as wormlike chains. For relatively large extensions we allow for enthalpic stretching of crosslink backbones. We show that for sufficiently high crosslink density, the network linear elastic response is affine on the scale of the filaments' length. The nonlinear regime can become highly nonaffine and is characterized by a divergence of the elastic modulus at finite strain. In contrast to the prior predictions, we do not find an asymptotic regime in which the differential elastic modulus scales linearly with the stress, although an approximate linear dependence can be seen in a transition from entropic to enthalpic regimes. We discuss our results in light of recent experiments.

  7. Elastic response of filamentous networks with compliant crosslinks

    CERN Document Server

    Sharma, A; Heidemann, K M; MacKintosh, F C

    2013-01-01

    Experiments have shown that elasticity of disordered filamentous networks with compliant crosslinks is very different from networks with rigid crosslinks. Here, we model and analyze filamentous networks as a collection of randomly oriented rigid filaments connected to each other by flexible crosslinks that are modeled as worm-like chains. For relatively large extensions we allow for enthalpic stretching of crosslinks' backbones. We show that for sufficiently high crosslink density, the network linear elastic response is affine on the scale of the filaments' length. The nonlinear regime can become highly nonaffine and is characterized by a divergence of the elastic modulus at finite strain. In contrast to the prior predictions, we do not find an asymptotic regime in which the differential elastic modulus scales linearly with the stress, although an approximate linear dependence can be seen in a transition from entropic to enthalpic regimes. We discuss our results in light of the recent experiments.

  8. Bright Prospect for the Polyester Industrial Filament Sector

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Some large companies from Americaand Europe have constructed plantsin China or established long-termstable cooperation relationship withChinese enterprises. A bright devel-opment prospect has therefore beenbrought to the polyester industrial fila-ment sector in China.

  9. Myosin and Actin Filaments in Muscle: Structures and Interactions.

    Science.gov (United States)

    Squire, John M; Paul, Danielle M; Morris, Edward P

    2017-01-01

    In the last decade, improvements in electron microscopy and image processing have permitted significantly higher resolutions to be achieved (sometimes <1 nm) when studying isolated actin and myosin filaments. In the case of actin filaments the changing structure when troponin binds calcium ions can be followed using electron microscopy and single particle analysis to reveal what happens on each of the seven non-equivalent pseudo-repeats of the tropomyosin α-helical coiled-coil. In the case of the known family of myosin filaments not only are the myosin head arrangements under relaxing conditions being defined, but the latest analysis, also using single particle methods, is starting to reveal the way that the α-helical coiled-coil myosin rods are packed to give the filament backbones.

  10. Tropomyosin diffusion over actin subunits facilitates thin filament assembly

    Directory of Open Access Journals (Sweden)

    Stefan Fischer

    2016-01-01

    Full Text Available Coiled-coil tropomyosin binds to consecutive actin-subunits along actin-containing thin filaments. Tropomyosin molecules then polymerize head-to-tail to form cables that wrap helically around the filaments. Little is known about the assembly process that leads to continuous, gap-free tropomyosin cable formation. We propose that tropomyosin molecules diffuse over the actin-filament surface to connect head-to-tail to partners. This possibility is likely because (1 tropomyosin hovers loosely over the actin-filament, thus binding weakly to F-actin and (2 low energy-barriers provide tropomyosin freedom for 1D axial translation on F-actin. We consider that these unique features of the actin-tropomyosin interaction are the basis of tropomyosin cable formation.

  11. Eruptive filament of May 31, 1997, observed by SOHO.

    Science.gov (United States)

    Schmieder, B.; Heinzel, P.; Vial, J.-C.; Delaboudinière, J.-P.; Delannée, C.

    In the frame of the SUMER/CDS Joint Programme (JOP 17) the authors have detected the four Lyman lines in an erupting filament. The strong self-absorption in these lines, already reported for quiescent filaments, is still present in this highly dynamical event, but the authors observe a significant red asymmetry in the intensities of the two peaks. They ascribe it to an upward bulk motion of the filament, which they can actually see on a series of EIT images taken in the Fe XII line. Both sets of observations can lead to a determination of the velocity vector. The Doppler velocities are also derived from other lines detected by SUMER/CDS and can be correlated with the observations of the Pic-du-Midi MSDP obtained for this event. The filament eruption was also well observed by other GBO instruments in the Hα line (Meudon and Ondřejov).

  12. Successive filament eruptions within one solar breakout event

    CERN Document Server

    Shen, Yuandeng

    2014-01-01

    The magnetic breakout model has been widely used to explain solar eruptive activities. Here, we apply it to explain successive filament eruptions occurred in a quadrupolar magnetic source region. Based on the high temporal and spatial resolution, multi-wavelengths observations taken by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO), we find some signatures that support the occurrence of breakout-like external reconnection just before the start of the successive filament eruptions. Furthermore, the extrapolated three-dimensional coronal field also reveals that the magnetic topology above the quadrupolar source region resembles that of the breakout model. We propose a possible mechanism within the framework of the breakout model to interpret the successive filament eruptions, in which the so-called magnetic implosion mechanism is firstly introduced to be the physical linkage of successive filament eruptions. We conclude that the structural properties of coronal fields are im...

  13. Measurement of Reversed Extension Flow using the Filament Stretch Rheometer

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.; Skov, Anne Ladegaard; Nielsen, Jens Kromann;

    2008-01-01

    The measurement of material functions with reversed extension flow is demonstrated using the Filament Stretching Rheometer (FSR). This includes startup of uniaxial elongational flow (potentially until steady state) followed by biaxial squeezing, and large amplitude oscillatory elongation (LAOE). ...

  14. Actin filaments on myosin beds: The velocity distribution

    Science.gov (United States)

    Bourdieu, L.; Magnasco, M. O.; Winkelmann, D. A.; Libchaber, A.

    1995-12-01

    In vitro studies of actin filaments sliding on a myosin-coated surface are analyzed, filament by filament, at a sampling rate of 30 per second. For each filament, the mean arc length coordinate is computed and histograms of instantaneous velocities, along the arc length, are established. Two types of motion are observed, depending on the experimental conditions. The first one is characterized by a homogeneous flow, with well defined velocities. In this regime, specific defects are a constitutive part of the flow. It is observed at high temperature, at high myosin coverage, and with a particular mode of attachment of myosin to the surface. The second regime shows no clear velocity selection, but a broadband distribution. It is characterized by high friction and is observed at low temperature or low myosin density. (c) 1995 The American Physical Society

  15. Dynamics of wave fronts and filaments in anisotropic cardiac tissue

    CERN Document Server

    Dierckx, Hans J F M

    2015-01-01

    The heartbeat is mediated between cardiac cells by waves of electrical depolarisation. During cardiac arrhythmias, electrical activity was found to be organised in scroll waves which rotate around a dynamical filament curve. In this thesis, a curved-space approach is used to mathematically capture anisotropy of wave propagation. We derive for the first time the covariant laws of motion for traveling wave fronts and scroll wave filaments in anisotropic excitable media such as cardiac tissue. We show that locally varying anisotropy yields non-zero Riemann tensor components, which may alter the stability of scroll wave filaments. The instability of scroll wave filaments has been linked to transition from ventricular tachycardia to fibrillation.

  16. Calibration and temperature profile of a tungsten filament lamp

    Energy Technology Data Exchange (ETDEWEB)

    De Izarra, Charles [Groupe de Recherche sur l' Energetique des Milieux Ionises, UMR6606 Universite d' Orleans, CNRS, Faculte des Sciences, Site de Bourges, rue Gaston Berger, BP 4043, 18028 Bourges Cedex (France); Gitton, Jean-Michel, E-mail: Charles.De_Izarra@univ-orleans.f [College Littre, 10 rue Littre, Bourges (France)

    2010-07-15

    The goal of this work proposed for undergraduate students and teachers is the calibration of a tungsten filament lamp from electric measurements that are both simple and precise, allowing to determine the temperature of tungsten filament as a function of the current intensity. This calibration procedure was first applied to a conventional filament lamp (lamp used in automotive lighting) and then tested on a standard tungsten ribbon lamp. The calibration procedure developed was checked by determining the calibration point of the tungsten ribbon lamp with an accuracy of 2%. In addition, for low current intensity, it was observed that the temperature of the filament was not uniform; an explanation is proposed by considering a simple heat transfer model.

  17. FILAMENTATION INSTABILITY OF LASER BEAMS IN NONLOCAL NONLINEAR MEDIA

    Institute of Scientific and Technical Information of China (English)

    文双春; 范滇元

    2001-01-01

    The filamentation instability of laser beams propagating in nonlocal nonlinear media is investigated. It is shown that the filamentation instability can occur in weakly nonlocal self-focusing media for any degree of nonlocality, and in defocusing media for the input light intensity exceeding a threshold related to the degree of nonlocality. A linear stability analysis is used to predict the initial growth rate of the instability. It is found that the nonlocality tends to suppress filamentation instability in self-focusing media and to stimulate filamentation instability in self-defocusing media. Numerical simulations confirm the results of the linear stability analysis and disclose a recurrence phenomenon in nonlocal self-focusing media analogous to the Fermi-Pasta-Ulam problem.

  18. Tropomyosin diffusion over actin subunits facilitates thin filament assembly

    Science.gov (United States)

    Fischer, Stefan; Rynkiewicz, Michael J.; Moore, Jeffrey R.; Lehman, William

    2016-01-01

    Coiled-coil tropomyosin binds to consecutive actin-subunits along actin-containing thin filaments. Tropomyosin molecules then polymerize head-to-tail to form cables that wrap helically around the filaments. Little is known about the assembly process that leads to continuous, gap-free tropomyosin cable formation. We propose that tropomyosin molecules diffuse over the actin-filament surface to connect head-to-tail to partners. This possibility is likely because (1) tropomyosin hovers loosely over the actin-filament, thus binding weakly to F-actin and (2) low energy-barriers provide tropomyosin freedom for 1D axial translation on F-actin. We consider that these unique features of the actin-tropomyosin interaction are the basis of tropomyosin cable formation. PMID:26798831

  19. The "Le Chatelier's principle"-governed response of actin filaments to osmotic stress.

    Science.gov (United States)

    Ito, Tadanao; Yamazaki, Masahito

    2006-07-13

    Actin filaments inhibit osmotic stress-driven water flow across a semipermeable membrane in proportion to the filament concentration (Ito, T.; Zaner, K. S.; Stossel, T. P. Biophys. J. 1987, 51, 745). When the filaments are cross-linked by F-actin binding protein, filamin A, this flow is stopped completely (Ito, T.; Suzuki, A.; Stossel, T. P. Biophys. J. 1992, 61, 1301). No conventional theory accurately accounts for these results. Here, this response is analyzed by formulating the entropy of the system under osmotic stress. Results demonstrate that the response of the actin filaments to osmotic stress is governed by the Le Chatelier's principle, which states that an external interaction that disturbs the equilibrium brings about processes in the body that tend to reduce the effects of this interaction. In the present case, disrupting equilibrium by osmotic stress brings about a reaction that decreases the chemical potential of water in the F-actin solution, reducing the effect of the applied osmotic disturbance. This decrease in the chemical potential of the water in the F-actin solution is caused by an increase in the chemical potential of F-actin, which is induced by isothermal absorption of heat by F-actin aided by work done by osmotic stress. As a result, F-actin has an inhibitory effect on the osmotic stress-driven water flow, and can even completely stop the flow when it is cross-linked. This is the first report demonstrating that the Le Chatelier's principle applies to the reaction of biopolymers against equilibrium disturbances such as osmotic stress.

  20. Motility patterns of filamentous sulfur bacteria, Beggiatoa spp

    DEFF Research Database (Denmark)

    Dunker, Rita; Røy, Hans; Kamp, Anja;

    2011-01-01

    was constructed based on our observations. The model was applied to virtual filaments in the oxygen- and sulfide-free zone of the sediment, which is a main habitat of Beggiatoa in the natural environment. The model predicts a long residence time of the virtual filament in the suboxic zone and explains why...... Beggiatoa accumulate high nitrate concentrations in internal vacuoles as an alternative electron acceptor to oxygen....

  1. Nucleus-associated intermediate filaments from chicken erythrocytes

    OpenAIRE

    1980-01-01

    Chicken erythrocyte nuclei prepared by isolation in isotonic KCl and Nonidet P-40 detergent were found to contain numerous attached filaments with a mean diameter of 11.0 nm. In polypeptide content and solubility properties, they resembled the vimentin type of intermediate filament found in cells of mesenchymal origin. Examination of their association with the nucleus suggests that more than a simple membrane attachment is involved.

  2. Scrape Off Layer profiles interpreted with filament dynamics

    CERN Document Server

    Militello, F

    2016-01-01

    A theoretical framework is developed to link the density profiles in the Scrape Off Layer (SOL) with the fluctuations (filaments) that generate them. The framework is based on the dynamics of independent filaments and their statistical behaviour and can be used to rigorously understand the mechanisms that lead to flattening and broadening of the SOL profiles as well as the radial increase of the relative fluctuation amplitude.

  3. Riemannian geometrical constraints on magnetic vortex filaments in plasmas

    OpenAIRE

    de Andrade, L. C. Garcia

    2005-01-01

    Two theorems on the Riemannian geometrical constraints on vortex magnetic filaments acting as dynamos in (MHD) flows are presented. The use of Gauss-Mainard-Codazzi equations allows us to investigate in detail the influence of curvature and torsion of vortex filaments in the MHD dynamos. This application follows closely previous applications to Heisenberg spin equation to the investigations in magnetohydrostatics given by Schief (Plasma Physics J. 10, 7, 2677 (2003)). The Lorentz force on vor...

  4. Scrape off layer profiles interpreted with filament dynamics

    Science.gov (United States)

    Militello, F.; Omotani, J. T.

    2016-10-01

    A theoretical framework is developed to link the density profiles in the scrape off layer (SOL) with the fluctuations (filaments) that generate them. The framework is based on the dynamics of independent filaments and their statistical behaviour and can be used to rigorously understand the mechanisms that lead to flattening and broadening of the SOL profiles as well as the radial increase of the relative fluctuation amplitude.

  5. The Hβ Chromospheric Magnetic Field in a Quiescent Filament

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    We observed the line-of-sight magnetic field in the chromosphereandphotosphere of a large quiescent filament on the solar disk on September 6, 2001using the Solar Magnetic Field Telescope in Huairou Solar Observing Station. Thechromospheric and photospheric magnetograms together with Hβ filtergrams of thefilament were examined. The filament was located on the neutral line of the largescale longitudinal magnetic field in the photosphere and the chromosphere. Thelateral feet of the filament .were found to be related to magnetic structures with op-posite polarities. Two small lateral feet are linked to weak parasitic polarity. Thereis a negative magnetic structure in the photosphere under a break of the filament.At the location corresponding to the filament in the chromospheric magnetograms,the magnetic strength is found to be about 40-70 Gauss (measuring error about 39Gauss). The magnetic signal indicates the amplitude and orientation of the internalmagnetic field in the filament. We discuss several possible causes which may pro-duce such a measured signal. A twisted magnetic configuration inside the filamentis suggested .

  6. Force-velocity measurements of a few growing actin filaments.

    Directory of Open Access Journals (Sweden)

    Coraline Brangbour

    2011-04-01

    Full Text Available The polymerization of actin in filaments generates forces that play a pivotal role in many cellular processes. We introduce a novel technique to determine the force-velocity relation when a few independent anchored filaments grow between magnetic colloidal particles. When a magnetic field is applied, the colloidal particles assemble into chains under controlled loading or spacing. As the filaments elongate, the beads separate, allowing the force-velocity curve to be precisely measured. In the widely accepted Brownian ratchet model, the transduced force is associated with the slowing down of the on-rate polymerization. Unexpectedly, in our experiments, filaments are shown to grow at the same rate as when they are free in solution. However, as they elongate, filaments are more confined in the interspace between beads. Higher repulsive forces result from this higher confinement, which is associated with a lower entropy. In this mechanism, the production of force is not controlled by the polymerization rate, but is a consequence of the restriction of filaments' orientational fluctuations at their attachment point.

  7. Force-Velocity Measurements of a Few Growing Actin Filaments

    Science.gov (United States)

    Brangbour, Coraline; du Roure, Olivia; Helfer, Emmanuèle; Démoulin, Damien; Mazurier, Alexis; Fermigier, Marc; Carlier, Marie-France; Bibette, Jérôme; Baudry, Jean

    2011-01-01

    The polymerization of actin in filaments generates forces that play a pivotal role in many cellular processes. We introduce a novel technique to determine the force-velocity relation when a few independent anchored filaments grow between magnetic colloidal particles. When a magnetic field is applied, the colloidal particles assemble into chains under controlled loading or spacing. As the filaments elongate, the beads separate, allowing the force-velocity curve to be precisely measured. In the widely accepted Brownian ratchet model, the transduced force is associated with the slowing down of the on-rate polymerization. Unexpectedly, in our experiments, filaments are shown to grow at the same rate as when they are free in solution. However, as they elongate, filaments are more confined in the interspace between beads. Higher repulsive forces result from this higher confinement, which is associated with a lower entropy. In this mechanism, the production of force is not controlled by the polymerization rate, but is a consequence of the restriction of filaments' orientational fluctuations at their attachment point. PMID:21541364

  8. Filament Fragmentation in High-Mass Star Formation

    CERN Document Server

    Beuther, H; Johnston, K; Henning, Th; Hacar, A; Kainulainen, J T

    2015-01-01

    Aims: We resolve the length-scales for filament formation and fragmentation (res. <=0.1pc), in particular the Jeans length and cylinder fragmentation scale. Methods: We observed the prototypical high-mass star-forming filament IRDC18223 with the Plateau de Bure Interferometer (PdBI) in the 3.2mm continuum and N2H+(1-0) line emission in a ten field mosaic at a spatial resolution of ~4'' (~14000AU). Results: The dust continuum emission resolves the filament into a chain of at least 12 relatively regularly spaced cores. The mean separation between cores is ~0.40(+-0.18)pc. While this is approximately consistent with the fragmentation of an infinite, isothermal, gravitationally bound gas cylinder, a high mass-to-length ratio of M/l~1000M_sun/pc requires additional turbulent and/or magnetic support against radial collapse of the filament. The N2H+(1-0) data reveal a velocity gradient perpendicular to the main filament. Although rotation of the filament cannot be excluded, the data are also consistent with the m...

  9. Mid-infrared laser filaments in the atmosphere

    Science.gov (United States)

    Mitrofanov, A. V.; Voronin, A. A.; Sidorov-Biryukov, D. A.; Pugžlys, A.; Stepanov, E. A.; Andriukaitis, G.; Flöry, T.; Ališauskas, S.; Fedotov, A. B.; Baltuška, A.; Zheltikov, A. M.

    2015-01-01

    Filamentation of ultrashort laser pulses in the atmosphere offers unique opportunities for long-range transmission of high-power laser radiation and standoff detection. With the critical power of self-focusing scaling as the laser wavelength squared, the quest for longer-wavelength drivers, which would radically increase the peak power and, hence, the laser energy in a single filament, has been ongoing over two decades, during which time the available laser sources limited filamentation experiments in the atmosphere to the near-infrared and visible ranges. Here, we demonstrate filamentation of ultrashort mid-infrared pulses in the atmosphere for the first time. We show that, with the spectrum of a femtosecond laser driver centered at 3.9 μm, right at the edge of the atmospheric transmission window, radiation energies above 20 mJ and peak powers in excess of 200 GW can be transmitted through the atmosphere in a single filament. Our studies reveal unique properties of mid-infrared filaments, where the generation of powerful mid-infrared supercontinuum is accompanied by unusual scenarios of optical harmonic generation, giving rise to remarkably broad radiation spectra, stretching from the visible to the mid-infrared. PMID:25687621

  10. The interaction of a magnetohydrodynamical shock with a filament

    CERN Document Server

    Goldsmith, K J A

    2016-01-01

    We present 3D magnetohydrodynamic numerical simulations of the adiabatic interaction of a shock with a dense, filamentary cloud. We investigate the effects of various filament lengths and orientations on the interaction using different orientations of the magnetic field, and vary the Mach number of the shock, the density contrast of the filament, and the plasma beta, in order to determine their effect on the evolution and lifetime of the filament. We find that in a parallel magnetic field filaments have longer lifetimes if they are orientated more 'broadside' to the shock front, and that an increase in the density contrast hastens the destruction of the cloud, in terms of the modified cloud-crushing time-scale, tcs. The combination of a mild shock and a perpendicular or oblique field provides the best condition for extending the life of the filament, with some filaments able to survive almost indefinitely since they are cocooned by the magnetic field. A high value for the density contrast does not initiate la...

  11. Formation of a solar Ha filament from orphan penumbrae

    CERN Document Server

    Buehler, D; van Noort, M; Solanki, S K

    2016-01-01

    The formation of an Ha filament in active region (AR) 10953 is described. Observations from the Solar Optical Telescope (SOT) aboard the Hinode satellite starting on 27th April 2007 until 1st May 2007 were analysed. 20 scans of the 6302A Fe I line pair recorded by SOT/SP were inverted using the SPINOR code. The inversions were analysed together with SOT/BFI G-band and Ca II H and SOT/NFI Ha observations. Following the disappearance of an initial Ha filament aligned along the polarity inversion line (PIL) of the AR, a new Ha filament formed in its place some 20 hours later, which remained stable for at least 1.5 days. The creation of the new Ha filament was driven by the ascent of horizontal magnetic fields from the photosphere into the chromosphere at three separate locations along the PIL. The magnetic fields at two of these locations were situated directly underneath the initial Ha filament and formed orphan penumbrae already aligned along the Ha filament channel. The 700 G orphan penumbrae were stable and ...

  12. Appearance of Dusty Filaments at Different Viewing Angles

    CERN Document Server

    Chira, R -A; Henning, Th; Kainulainen, J

    2016-01-01

    Context: In the last years, there have been many studies on the omnipresence and structures of filaments in star-forming regions, as well as their role in the process of star formation. Those filaments are normally identified as elongated fibres across the plane of the sky. But how would we detect filaments that are inclined? Aims: We aim to learn more about whether, and how, total column density or dust temperature change with respect to the line of sight. Such variations would enable observers to use dust observations to identify and study filaments at any inclination and gain more insight on the distribution and orientations of filaments within the Galactic plane. Methods: As a first step, we perform numerical calculations on simple cylindrical models to evaluate the influence of filament geometry on the average flux density. After that, we apply our three-dimensional Monte Carlo dust radiative transfer code on two models of star-forming regions and derive maps of effective total column density and dust te...

  13. SDC13 infrared dark clouds: Longitudinally collapsing filaments?

    CERN Document Server

    Peretto, N; André, Ph; Arzoumanian, D; Rivilla, V M; Bardeau, S; Puertas, S Duarte; Fernandez, J P Guzman; Lenfestey, C; Li, G -X; Olguin, F A; Röck, B R; de Villiers, H; Williams, J

    2013-01-01

    Formation of stars is now believed to be tightly linked to the dynamical evolution of interstellar filaments in which they form. In this paper we analyze the density structure and kinematics of a small network of infrared dark filaments, SDC13, observed in both dust continuum and molecular line emission with the IRAM 30m telescope. These observations reveal the presence of 18 compact sources amongst which the two most massive, MM1 and MM2, are located at the intersection point of the parsec-long filaments. The dense gas velocity and velocity dispersion observed along these filaments show smooth, strongly correlated, gradients. We discuss the origin of the SDC13 velocity field in the context of filament longitudinal collapse. We show that the collapse timescale of the SDC13 filaments (from 1 Myr to 4 Myr depending on the model parameters) is consistent with the presence of Class I sources in them, and argue that, on top of bringing more material to the centre of the system, collapse could generate additional k...

  14. Photospheric flows around a quiescent filament and CALAS first results .

    Science.gov (United States)

    Rondi, S.; Roudier, Th.; Molodij, G.; Bommier, V.; Malherbe, J. M.; Schmieder, B.; Meunier, N.; Rieutord, M.; Beigbeder., F.

    The horizontal photospheric flows below and around a filament are one of the components in the formation and evolution of filaments. Few studies have been done so far because this requires multiwalength time sequences with high spatial resolution. We present observations obtained in 2004 during the international JOP 178 campaign in which eleven instruments were involved, from space and ground based observatories. Several supergranulation cells are crossing the Polarity Inversion Line (PIL) allowing the transport of magnetic flux through the PIL, in particular the parasitic polarities. Before the filament eruptive phase, parasitic and normal polarities are swept by a continuous diverging horizontal flow located in the filament gap where the disappearance of the filament starts. In the future, observations at high spatial resolution on a large field-of-view would be very useful to study filaments, as they are very large structures. We also present the first images obtained with the use of our new 14 MPixel camera CALAS (CAmera for the LArge Scales of the Solar Surface) (10 arcmin× 6.7 arcmin) . These are the first large-scale and high-resolution images of the solar surface ever made.

  15. Large scale filaments associated with Milky Way spiral arms

    CERN Document Server

    Wang, Ke; Ginsburg, Adam; Walmsley, C Malcolm; Molinari, Sergio; Schisano, Eugenio

    2015-01-01

    The ubiquity of filamentary structure at various scales through out the Galaxy has triggered a renewed interest in their formation, evolution, and role in star formation. The largest filaments can reach up to Galactic scale as part of the spiral arm structure. However, such large scale filaments are hard to identify systematically due to limitations in identifying methodology (i.e., as extinction features). We present a new approach to directly search for the largest, coldest, and densest filaments in the Galaxy, making use of sensitive Herschel Hi-GAL data complemented by spectral line cubes. We present a sample of the 9 most prominent Herschel filaments, including 6 identified from a pilot search field plus 3 from outside the field. These filaments measure 37-99 pc long and 0.6-3.0 pc wide with masses (0.5-8.3)$\\times10^4 \\, M_\\odot$, and beam-averaged ($28"$, or 0.4-0.7 pc) peak H$_2$ column densities of (1.7-9.3)$\\times 10^{22} \\, \\rm{cm^{-2}}$. The bulk of the filaments are relatively cold (17-21 K), whi...

  16. Topology of magnetic helicity of torsioned filaments in Hall plasmas

    CERN Document Server

    de Andrade, L C Garcia

    2007-01-01

    A solution of magnetic Hall equations for plasma filaments in the Coulomb gauge is obtained in the non-holonomic frame. Some physical features of the solution include, the non-conservation of the magnetic helicity and the decay of the magnetic field in the filaments. From the mathematical point of view,the presence of Frenet torsion in the filament is actually shown to be fundamental for the breaking of conservation of magnetic helicity in the case of helicoidal filaments. Since the magnetic helicity is not conserved even in the Coulomb gauge, and the magnetic field decays, one can say that the dynamo action fails. Actually the presence of torsion enhances the breaking of magnetic field helicity conservation. A similar formula of the one obtained here without considering the Hall effect has been obtained by Moffatt and Ricca (PRSA-1992) in the case of holonomic filaments. It is shown that unknotted magnetic filaments may place a lower bound on the magnetic energy. Discussions on the writhe number are also dis...

  17. Properties of Cosmological Filaments extracted from Eulerian Simulations

    CERN Document Server

    Gheller, Claudio; Favre, Jean; Brüggen, Marcus

    2015-01-01

    Using a new parallel algorithm implemented within the VisIt framework, we analysed large cosmological grid simulations to study the properties of baryons in filaments. The procedure allows us to build large catalogues with up to $\\sim 3 \\cdot 10^4$ filaments per simulated volume and to investigate the properties of cosmic filaments for very large volumes at high resolution (up to $300^3 ~\\rm Mpc^3$ simulated with $2048^3$ cells). We determined scaling relations for the mass, volume, length and temperature of filaments and compared them to those of galaxy clusters. The longest filaments have a total length of about $200 ~\\rm Mpc$ with a mass of several $10^{15} M_{\\odot}$. We also investigated the effects of different gas physics. Radiative cooling significantly modifies the thermal properties of the warm-hot-intergalactic medium of filaments, mainly by lowering their mean temperature via line cooling. On the other hand, powerful feedback from active galactic nuclei in surrounding halos can heat up the gas in ...

  18. Sympathetic Solar Filament Eruptions on 2015 March 15

    CERN Document Server

    Wang, Rui; Zimovets, Ivan; Hu, Huidong; Dai, Xinghua; Yang, Zhongwei

    2016-01-01

    The 2015 March 15 coronal mass ejection as one of the two that together drove the largest geomagnetic storm of solar cycle 24 so far was associated with sympathetic filament eruptions. We investigate the relations between the different filaments involved in the eruption. A surge-like small-scale filament motion is confirmed as the trigger that initiated the erupting filament with multi-wavelength observations and using a forced magnetic field extrapolation method. When the erupting filament moved to an open magnetic field region, it experienced an obvious acceleration process and was accompanied by a C-class flare and the rise of another larger filament that eventually failed to erupt. We measure the decay index of the background magnetic field, which presents a critical height of 118 Mm. Combining with a potential field source surface extrapolation method, we analyze the distributions of the large-scale magnetic field, which indicates that the open magnetic field region may provide a favorable condition for ...

  19. Geometrical and mechanical properties control actin filament organization.

    Directory of Open Access Journals (Sweden)

    Gaëlle Letort

    2015-05-01

    Full Text Available The different actin structures governing eukaryotic cell shape and movement are not only determined by the properties of the actin filaments and associated proteins, but also by geometrical constraints. We recently demonstrated that limiting nucleation to specific regions was sufficient to obtain actin networks with different organization. To further investigate how spatially constrained actin nucleation determines the emergent actin organization, we performed detailed simulations of the actin filament system using Cytosim. We first calibrated the steric interaction between filaments, by matching, in simulations and experiments, the bundled actin organization observed with a rectangular bar of nucleating factor. We then studied the overall organization of actin filaments generated by more complex pattern geometries used experimentally. We found that the fraction of parallel versus antiparallel bundles is determined by the mechanical properties of actin filament or bundles and the efficiency of nucleation. Thus nucleation geometry, actin filaments local interactions, bundle rigidity, and nucleation efficiency are the key parameters controlling the emergent actin architecture. We finally simulated more complex nucleation patterns and performed the corresponding experiments to confirm the predictive capabilities of the model.

  20. Alteration of nuclear matrix-intermediate filament system and differential expression of nuclear matrix proteins during human hepatocarcinoma cell differentiation

    Institute of Scientific and Technical Information of China (English)

    Jian Tang; Jing-Wen Niu; Dong-Hui Xu; Zhi-Xing Li; Qi-Fu Li; Jin-An Chen

    2007-01-01

    AIM:To investigate the association between the configurational and compositional changes of nuclear matrix and the differentiation of carcinoma cells.METHODS: Cells cultured with or without 5 × 10-3mmol/L of hexamethylene bisacetamide (HMBA) on Nickel grids were treated by selective extraction and prepared for whole mount observation under electron microscopy. The samples were examined under transmission electron microscope. Nuclear matrix proteins were selectively extracted and subjected to subcellular proteomics study. The protein expression patterns were analyzed by PDQuest software. Spots of differentially expressed nuclear matrix proteins were excised and subjected to in situ digestion with trypsin.The peptides were analyzed by matrix-assisted laserdesorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Data were submitted for database searching using Mascot tool (www. Matrixscience.com).RESULTS: The nuclear matrix (NM) and intermediate filament (IF) in SMMC-7721 hepatocarcinoma cells were found relatively sparse and arranged irregularly.The nuclear lamina was non-uniform, and two kinds of filaments were not tightly connected. After induction for differentiation by HMBA, the NM-IF filaments were concentrated and distributed uniformly. The heterogeneous population of filaments, including highly branched utrathin filaments could also be seen in the regular meshwork. The connection between the two kinds of filaments and the relatively thin, condensed and sharply demarcated lamina composed of intermediatesized filaments was relatively fastened. Meanwhile, 21NM proteins changed remarkably during SMMC-7721cell differentiation. Four proteins, I.e. Mutant Pyst1,hypothetical protein, nucleophosmin1, and LBP were downregulated, whereas four other proteins, eIF6, p44subunit, β-tubulin, and SIN3B were upregulated with the last one, SR2/ASF found only in the differentiated SMMC-7721 cells.CONCLUSION: The induced differentiation of SMMC-7721cells by HMBA is