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Sample records for bacterial flagellar bundling

  1. Mesoscopic modeling of bacterial flagellar microhydrodynamics.

    Science.gov (United States)

    Gebremichael, Yeshitila; Ayton, Gary S; Voth, Gregory A

    2006-11-15

    A particle-based hybrid method of elastic network model and smooth-particle hydrodynamics has been employed to describe the propulsion of bacterial flagella in a viscous hydrodynamic environment. The method explicitly models the two aspects of bacterial propulsion that involve flagellar flexibility and long-range hydrodynamic interaction of low-Reynolds-number flow. The model further incorporates the molecular organization of the flagellar filament at a coarse-grained level in terms of the 11 protofilaments. Each of these protofilaments is represented by a collection of material points that represent the flagellin proteins. A computational model of a single flexible helical segment representing the filament of a bacterial flagellum is presented. The propulsive dynamics and the flow fields generated by the motion of the model filament are examined. The nature of flagellar deformation and the influence of hydrodynamics in determining the shape of deformations are examined based on the helical filament.

  2. Exchange of rotor components in functioning bacterial flagellar motor

    International Nuclear Information System (INIS)

    Fukuoka, Hajime; Inoue, Yuichi; Terasawa, Shun; Takahashi, Hiroto; Ishijima, Akihiko

    2010-01-01

    The bacterial flagellar motor is a rotary motor driven by the electrochemical potential of a coupling ion. The interaction between a rotor and stator units is thought to generate torque. The overall structure of flagellar motor has been thought to be static, however, it was recently proved that stators are exchanged in a rotating motor. Understanding the dynamics of rotor components in functioning motor is important for the clarifying of working mechanism of bacterial flagellar motor. In this study, we focused on the dynamics and the turnover of rotor components in a functioning flagellar motor. Expression systems for GFP-FliN, FliM-GFP, and GFP-FliG were constructed, and each GFP-fusion was functionally incorporated into the flagellar motor. To investigate whether the rotor components are exchanged in a rotating motor, we performed fluorescence recovery after photobleaching experiments using total internal reflection fluorescence microscopy. After photobleaching, in a tethered cell producing GFP-FliN or FliM-GFP, the recovery of fluorescence at the rotational center was observed. However, in a cell producing GFP-FliG, no recovery of fluorescence was observed. The transition phase of fluorescence intensity after full or partially photobleaching allowed the turnover of FliN subunits to be calculated as 0.0007 s -1 , meaning that FliN would be exchanged in tens of minutes. These novel findings indicate that a bacterial flagellar motor is not a static structure even in functioning state. This is the first report for the exchange of rotor components in a functioning bacterial flagellar motor.

  3. Hybrid-fuel bacterial flagellar motors in Escherichia coli

    OpenAIRE

    Sowa, Yoshiyuki; Homma, Michio; Ishijima, Akihiko; Berry, Richard M.

    2014-01-01

    The bacterial flagellar motor is a rotary nano-machine that is driven by an electrochemical ion gradient across the cytoplasmic membrane, either H+ or Na+ ions. Natural Escherichia coli cells have only H+-driven motors. We demonstrate a genetically engineered hybrid-fuel flagellar motor in E. coli that runs on both types of ion gradient, H+ and Na+. The hybrid motors switch between the two types of ion automatically and dynamically in response to external conditions, by swapping the stator co...

  4. Bacterial flagellar capping proteins adopt diverse oligomeric states

    Energy Technology Data Exchange (ETDEWEB)

    Postel, Sandra; Deredge, Daniel; Bonsor, Daniel A.; Yu, Xiong; Diederichs, Kay; Helmsing, Saskia; Vromen, Aviv; Friedler, Assaf; Hust, Michael; Egelman, Edward H.; Beckett, Dorothy; Wintrode, Patrick L.; Sundberg, Eric J. (UV); (Braunschweig); (Maryland-MED); (Konstanz); (Maryland); (Hebrew)

    2016-09-24

    Flagella are crucial for bacterial motility and pathogenesis. The flagellar capping protein (FliD) regulates filament assembly by chaperoning and sorting flagellin (FliC) proteins after they traverse the hollow filament and exit the growing flagellum tip. In the absence of FliD, flagella are not formed, resulting in impaired motility and infectivity. Here, we report the 2.2 Å resolution X-ray crystal structure of FliD fromPseudomonas aeruginosa, the first high-resolution structure of any FliD protein from any bacterium. Using this evidence in combination with a multitude of biophysical and functional analyses, we find thatPseudomonasFliD exhibits unexpected structural similarity to other flagellar proteins at the domain level, adopts a unique hexameric oligomeric state, and depends on flexible determinants for oligomerization. Considering that the flagellin filaments on which FliD oligomers are affixed vary in protofilament number between bacteria, our results suggest that FliD oligomer stoichiometries vary across bacteria to complement their filament assemblies.

  5. Protein export through the bacterial flagellar type III export pathway.

    Science.gov (United States)

    Minamino, Tohru

    2014-08-01

    For construction of the bacterial flagellum, which is responsible for bacterial motility, the flagellar type III export apparatus utilizes both ATP and proton motive force across the cytoplasmic membrane and exports flagellar proteins from the cytoplasm to the distal end of the nascent structure. The export apparatus consists of a membrane-embedded export gate made of FlhA, FlhB, FliO, FliP, FliQ, and FliR and a water-soluble ATPase ring complex consisting of FliH, FliI, and FliJ. FlgN, FliS, and FliT act as substrate-specific chaperones that do not only protect their cognate substrates from degradation and aggregation in the cytoplasm but also efficiently transfer the substrates to the export apparatus. The ATPase ring complex facilitates the initial entry of the substrates into the narrow pore of the export gate. The export gate by itself is a proton-protein antiporter that uses the two components of proton motive force, the electric potential difference and the proton concentration difference, for different steps of the export process. A specific interaction of FlhA with FliJ located in the center of the ATPase ring complex allows the export gate to efficiently use proton motive force to drive protein export. The ATPase ring complex couples ATP binding and hydrolysis to its assembly-disassembly cycle for rapid and efficient protein export cycle. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey. © 2013 Elsevier B.V. All rights reserved.

  6. Hybrid-fuel bacterial flagellar motors in Escherichia coli.

    Science.gov (United States)

    Sowa, Yoshiyuki; Homma, Michio; Ishijima, Akihiko; Berry, Richard M

    2014-03-04

    The bacterial flagellar motor rotates driven by an electrochemical ion gradient across the cytoplasmic membrane, either H(+) or Na(+) ions. The motor consists of a rotor ∼50 nm in diameter surrounded by multiple torque-generating ion-conducting stator units. Stator units exchange spontaneously between the motor and a pool in the cytoplasmic membrane on a timescale of minutes, and their stability in the motor is dependent upon the ion gradient. We report a genetically engineered hybrid-fuel flagellar motor in Escherichia coli that contains both H(+)- and Na(+)-driven stator components and runs on both types of ion gradient. We controlled the number of each type of stator unit in the motor by protein expression levels and Na(+) concentration ([Na(+)]), using speed changes of single motors driving 1-μm polystyrene beads to determine stator unit numbers. De-energized motors changed from locked to freely rotating on a timescale similar to that of spontaneous stator unit exchange. Hybrid motor speed is simply the sum of speeds attributable to individual stator units of each type. With Na(+) and H(+) stator components expressed at high and medium levels, respectively, Na(+) stator units dominate at high [Na(+)] and are replaced by H(+) units when Na(+) is removed. Thus, competition between stator units for spaces in a motor and sensitivity of each type to its own ion gradient combine to allow hybrid motors to adapt to the prevailing ion gradient. We speculate that a similar process may occur in species that naturally express both H(+) and Na(+) stator components sharing a common rotor.

  7. Model Studies of the Dynamics of Bacterial Flagellar Motors

    Science.gov (United States)

    Bai, Fan; Lo, Chien-Jung; Berry, Richard M.; Xing, Jianhua

    2009-01-01

    Abstract The bacterial flagellar motor is a rotary molecular machine that rotates the helical filaments that propel swimming bacteria. Extensive experimental and theoretical studies exist on the structure, assembly, energy input, power generation, and switching mechanism of the motor. In a previous article, we explained the general physics underneath the observed torque-speed curves with a simple two-state Fokker-Planck model. Here, we further analyze that model, showing that 1), the model predicts that the two components of the ion motive force can affect the motor dynamics differently, in agreement with latest experiments; 2), with explicit consideration of the stator spring, the model also explains the lack of dependence of the zero-load speed on stator number in the proton motor, as recently observed; and 3), the model reproduces the stepping behavior of the motor even with the existence of the stator springs and predicts the dwell-time distribution. The predicted stepping behavior of motors with two stators is discussed, and we suggest future experimental procedures for verification. PMID:19383460

  8. Model Studies of the Dynamics of Bacterial Flagellar Motors

    Energy Technology Data Exchange (ETDEWEB)

    Bai, F; Lo, C; Berry, R; Xing, J

    2009-03-19

    The Bacterial Flagellar Motor is a rotary molecular machine that rotates the helical filaments which propel swimming bacteria. Extensive experimental and theoretical studies exist on the structure, assembly, energy input, power generation and switching mechanism of the motor. In our previous paper, we explained the general physics underneath the observed torque-speed curves with a simple two-state Fokker-Planck model. Here we further analyze this model. In this paper we show (1) the model predicts that the two components of the ion motive force can affect the motor dynamics differently, in agreement with the latest experiment by Lo et al.; (2) with explicit consideration of the stator spring, the model also explains the lack of dependence of the zero-load speed on stator number in the proton motor, recently observed by Yuan and Berg; (3) the model reproduces the stepping behavior of the motor even with the existence of the stator springs and predicts the dwelling time distribution. Predicted stepping behavior of motors with two stators is discussed, and we suggest future experimental verification.

  9. Model Studies of the Dynamics of Bacterial Flagellar Motors

    International Nuclear Information System (INIS)

    Bai, F.; Lo, C.; Berry, R.; Xing, J.

    2009-01-01

    The Bacterial Flagellar Motor is a rotary molecular machine that rotates the helical filaments which propel swimming bacteria. Extensive experimental and theoretical studies exist on the structure, assembly, energy input, power generation and switching mechanism of the motor. In our previous paper, we explained the general physics underneath the observed torque-speed curves with a simple two-state Fokker-Planck model. Here we further analyze this model. In this paper we show (1) the model predicts that the two components of the ion motive force can affect the motor dynamics differently, in agreement with the latest experiment by Lo et al.; (2) with explicit consideration of the stator spring, the model also explains the lack of dependence of the zero-load speed on stator number in the proton motor, recently observed by Yuan and Berg; (3) the model reproduces the stepping behavior of the motor even with the existence of the stator springs and predicts the dwelling time distribution. Predicted stepping behavior of motors with two stators is discussed, and we suggest future experimental verification.

  10. Changes in the flagellar bundling time account for variations in swimming behavior of flagellated bacteria in viscous media

    Science.gov (United States)

    Qu, Zijie; Temel, Fatma; Henderikx, Rene; Breuer, Kenneth

    2017-11-01

    The motility of bacteria E.coli in viscous fluids has been widely studied, although conflicting results on the effect of viscosity on swimming speed abound. The swimming mode of wild-type E.coli is idealized as a run-and-tumble sequence in which periods of straight swimming at a constant speed are randomly interrupted by a tumble, defined as a sudden change of direction with a very low speed. Using a tracking microscope, we follow cells for extended time and find that the swimming behavior of a single cell can exhibit a variety of behaviors including run-and-tumble and ``slow-random-walk'' in which the cells move at relatively low speed without the characteristic run. Although the characteristic swimming speed varies between individuals and in different polymer solutions, we find that the skewness of the speed distribution is solely a function of viscosity, and uniquely determines the ratio of the average speed to the characteristic run speed. Using Resistive Force Theory and the cell-specific measured characteristic run speed, we show that differences in the swimming behavior observed in solutions of different viscosity are due to changes in the flagellar bundling time, which increases as the viscosity rises, due to lower rotation rate of the flagellar motor. National Science Foundation.

  11. Signal-dependent turnover of the bacterial flagellar switch protein FliM

    Science.gov (United States)

    Delalez, Nicolas J.; Wadhams, George H.; Rosser, Gabriel; Xue, Quan; Brown, Mostyn T.; Dobbie, Ian M.; Berry, Richard M.; Leake, Mark C.; Armitage, Judith P.

    2010-01-01

    Most biological processes are performed by multiprotein complexes. Traditionally described as static entities, evidence is now emerging that their components can be highly dynamic, exchanging constantly with cellular pools. The bacterial flagellar motor contains ∼13 different proteins and provides an ideal system to study functional molecular complexes. It is powered by transmembrane ion flux through a ring of stator complexes that push on a central rotor. The Escherichia coli motor switches direction stochastically in response to binding of the response regulator CheY to the rotor switch component FliM. Much is known of the static motor structure, but we are just beginning to understand the dynamics of its individual components. Here we measure the stoichiometry and turnover of FliM in functioning flagellar motors, by using high-resolution fluorescence microscopy of E. coli expressing genomically encoded YPet derivatives of FliM at physiological levels. We show that the ∼30 FliM molecules per motor exist in two discrete populations, one tightly associated with the motor and the other undergoing stochastic turnover. This turnover of FliM molecules depends on the presence of active CheY, suggesting a potential role in the process of motor switching. In many ways the bacterial flagellar motor is as an archetype macromolecular assembly, and our results may have further implications for the functional relevance of protein turnover in other large molecular complexes. PMID:20498085

  12. Autonomously responsive pumping by a bacterial flagellar forest: A mean-field approach

    Science.gov (United States)

    Martindale, James D.; Fu, Henry C.

    2017-09-01

    This study is motivated by a microfluidic device that imparts a magnetic torque on an array of bacterial flagella. Bacterial flagella can transform their helical geometry autonomously in response to properties of the background fluid, which provides an intriguing mechanism allowing their use as an engineered element for the regulation or transport of chemicals in microscale applications. The synchronization of flagellar phase has been widely studied in biological contexts, but here we examine the synchronization of flagellar tilt, which is necessary for effective pumping. We first examine the effects of helical geometry and tilt on the pumping flows generated by a single rotating flagellum. Next, we explore a mean-field model for an array of helical flagella to understand how collective tilt arises and influences pumping. The mean-field methodology allows us to take into account possible phase differences through a time-averaging procedure and to model an infinite array of flagella. We find array separation distances, magnetic field strengths, and rotation frequencies that produce nontrivial self-consistent pumping solutions. For individual flagella, pumping is reversed when helicity or rotation is reversed; in contrast, when collective effects are included, self-consistent tilted pumping solutions become untilted nonpumping solutions when helicity or rotation is reversed.

  13. The Bacterial Flagellar Type III Export Gate Complex Is a Dual Fuel Engine That Can Use Both H+ and Na+ for Flagellar Protein Export.

    Science.gov (United States)

    Minamino, Tohru; Morimoto, Yusuke V; Hara, Noritaka; Aldridge, Phillip D; Namba, Keiichi

    2016-03-01

    The bacterial flagellar type III export apparatus utilizes ATP and proton motive force (PMF) to transport flagellar proteins to the distal end of the growing flagellar structure for self-assembly. The transmembrane export gate complex is a H+-protein antiporter, of which activity is greatly augmented by an associated cytoplasmic ATPase complex. Here, we report that the export gate complex can use sodium motive force (SMF) in addition to PMF across the cytoplasmic membrane to drive protein export. Protein export was considerably reduced in the absence of the ATPase complex and a pH gradient across the membrane, but Na+ increased it dramatically. Phenamil, a blocker of Na+ translocation, inhibited protein export. Overexpression of FlhA increased the intracellular Na+ concentration in the presence of 100 mM NaCl but not in its absence, suggesting that FlhA acts as a Na+ channel. In wild-type cells, however, neither Na+ nor phenamil affected protein export, indicating that the Na+ channel activity of FlhA is suppressed by the ATPase complex. We propose that the export gate by itself is a dual fuel engine that uses both PMF and SMF for protein export and that the ATPase complex switches this dual fuel engine into a PMF-driven export machinery to become much more robust against environmental changes in external pH and Na+ concentration.

  14. Assembly and stoichiometry of the core structure of the bacterial flagellar type III export gate complex.

    Science.gov (United States)

    Fukumura, Takuma; Makino, Fumiaki; Dietsche, Tobias; Kinoshita, Miki; Kato, Takayuki; Wagner, Samuel; Namba, Keiichi; Imada, Katsumi; Minamino, Tohru

    2017-08-01

    The bacterial flagellar type III export apparatus, which is required for flagellar assembly beyond the cell membranes, consists of a transmembrane export gate complex and a cytoplasmic ATPase complex. FlhA, FlhB, FliP, FliQ, and FliR form the gate complex inside the basal body MS ring, although FliO is required for efficient export gate formation in Salmonella enterica. However, it remains unknown how they form the gate complex. Here we report that FliP forms a homohexameric ring with a diameter of 10 nm. Alanine substitutions of conserved Phe-137, Phe-150, and Glu-178 residues in the periplasmic domain of FliP (FliPP) inhibited FliP6 ring formation, suppressing flagellar protein export. FliO formed a 5-nm ring structure with 3 clamp-like structures that bind to the FliP6 ring. The crystal structure of FliPP derived from Thermotoga maritia, and structure-based photo-crosslinking experiments revealed that Phe-150 and Ser-156 of FliPP are involved in the FliP-FliP interactions and that Phe-150, Arg-152, Ser-156, and Pro-158 are responsible for the FliP-FliO interactions. Overexpression of FliP restored motility of a ∆fliO mutant to the wild-type level, suggesting that the FliP6 ring is a functional unit in the export gate complex and that FliO is not part of the final gate structure. Copurification assays revealed that FlhA, FlhB, FliQ, and FliR are associated with the FliO/FliP complex. We propose that the assembly of the export gate complex begins with FliP6 ring formation with the help of the FliO scaffold, followed by FliQ, FliR, and FlhB and finally FlhA during MS ring formation.

  15. Maf-dependent bacterial flagellin glycosylation occurs before chaperone binding and flagellar T3SS export.

    Science.gov (United States)

    Parker, Jennifer L; Lowry, Rebecca C; Couto, Narciso A S; Wright, Phillip C; Stafford, Graham P; Shaw, Jonathan G

    2014-04-01

    Bacterial swimming is mediated by rotation of a filament that is assembled via polymerization of flagellin monomers after secretion via a dedicated flagellar Type III secretion system. Several bacteria decorate their flagellin with sialic acid related sugars that is essential for motility. Aeromonas caviae is a model organism for this process as it contains a genetically simple glycosylation system and decorates its flagellin with pseudaminic acid (Pse). The link between flagellin glycosylation and export has yet to be fully determined. We examined the role of glycosylation in the export and assembly process in a strain lacking Maf1, a protein involved in the transfer of Pse onto flagellin at the later stages of the glycosylation pathway. Immunoblotting, established that glycosylation is not required for flagellin export but is essential for filament assembly since non-glycosylated flagellin is still secreted. Maf1 interacts directly with its flagellin substrate in vivo, even in the absence of pseudaminic acid. Flagellin glycosylation in a flagellin chaperone mutant (flaJ) indicated that glycosylation occurs in the cytoplasm before chaperone binding and protein secretion. Preferential chaperone binding to glycosylated flagellin revealed its crucial role, indicating that this system has evolved to favour secretion of the polymerization competent glycosylated form. © 2014 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.

  16. A continuum theoretical model and finite elements simulation of bacterial flagellar filament phase transition.

    Science.gov (United States)

    Wang, Xiaoling; Meng, Shuo; Han, Jingshi

    2017-10-03

    The Bacterial flagellar filament can undergo a polymorphic phase transition in response to both mechanical and chemical variations in vitro and in vivo environments. Under mechanical stimuli, such as viscous flow or forces induced by motor rotation, the filament changes its phase from left-handed normal (N) to right-handed semi-coiled (SC) via phase nucleation and growth. Our detailed mechanical analysis of existing experiments shows that both torque and bending moment contribute to the filament phase transition. In this paper, we establish a non-convex and non-local continuum model based on the Ginzburg-Landau theory to describe main characteristics of the filament phase transition such as new-phase nucleation, growth, propagation and the merging of neighboring interfaces. The finite element method (FEM) is adopted to simulate the phase transition under a displacement-controlled loading condition (rotation angle and bending deflection). We show that new-phase nucleation corresponds to the maximum torque and bending moment at the stuck end of the filament. The hysteresis loop in the loading and unloading curves indicates energy dissipation. When the new phase grows and propagates, torque and bending moment remain static. We also find that there is a drop in load when the two interfaces merge, indicating a concomitant reduction in the interfacial energy. Finally, the interface thickness is governed by the coefficients of the gradient of order parameters in the non-local interface energy. Our continuum theory and the finite element method provide a method to study the mechanical behavior of such biomaterials. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Coevolved Mutations Reveal Distinct Architectures for Two Core Proteins in the Bacterial Flagellar Motor.

    Directory of Open Access Journals (Sweden)

    Alessandro Pandini

    Full Text Available Switching of bacterial flagellar rotation is caused by large domain movements of the FliG protein triggered by binding of the signal protein CheY to FliM. FliG and FliM form adjacent multi-subunit arrays within the basal body C-ring. The movements alter the interaction of the FliG C-terminal (FliGC "torque" helix with the stator complexes. Atomic models based on the Salmonella entrovar C-ring electron microscopy reconstruction have implications for switching, but lack consensus on the relative locations of the FliG armadillo (ARM domains (amino-terminal (FliGN, middle (FliGM and FliGC as well as changes during chemotaxis. The generality of the Salmonella model is challenged by the variation in motor morphology and response between species. We studied coevolved residue mutations to determine the unifying elements of switch architecture. Residue interactions, measured by their coevolution, were formalized as a network, guided by structural data. Our measurements reveal a common design with dedicated switch and motor modules. The FliM middle domain (FliMM has extensive connectivity most simply explained by conserved intra and inter-subunit contacts. In contrast, FliG has patchy, complex architecture. Conserved structural motifs form interacting nodes in the coevolution network that wire FliMM to the FliGC C-terminal, four-helix motor module (C3-6. FliG C3-6 coevolution is organized around the torque helix, differently from other ARM domains. The nodes form separated, surface-proximal patches that are targeted by deleterious mutations as in other allosteric systems. The dominant node is formed by the EHPQ motif at the FliMMFliGM contact interface and adjacent helix residues at a central location within FliGM. The node interacts with nodes in the N-terminal FliGc α-helix triad (ARM-C and FliGN. ARM-C, separated from C3-6 by the MFVF motif, has poor intra-network connectivity consistent with its variable orientation revealed by structural data. ARM

  18. Biotemplated flagellar nanoswimmers

    Directory of Open Access Journals (Sweden)

    Jamel Ali

    2017-11-01

    Full Text Available In this article, a porous hollow biotemplated nanoscale helix that can serve as a low Reynolds number robotic swimmer is reported. The nanorobot utilizes repolymerized bacterial flagella from Salmonella typhimurium as a nanotemplate for biomineralization. We demonstrate the ability to generate templated nanotubes with distinct helical geometries by using specific alkaline pH values to fix the polymorphic form of flagellar templates. Using uniform rotating magnetic fields to mimic the motion of the flagellar motor, we explore the swimming characteristics of these silica templated flagella and demonstrate the ability to wirelessly control their trajectories. The results suggest that the biotemplated nanoswimmer can be a cost-effective alternative to the current top-down methods used to produce helical nanorobots.

  19. Detection of Bundle Branch Block using Adaptive Bacterial Foraging Optimization and Neural Network

    Directory of Open Access Journals (Sweden)

    Padmavthi Kora

    2017-03-01

    Full Text Available The medical practitioners analyze the electrical activity of the human heart so as to predict various ailments by studying the data collected from the Electrocardiogram (ECG. A Bundle Branch Block (BBB is a type of heart disease which occurs when there is an obstruction along the pathway of an electrical impulse. This abnormality makes the heart beat irregular as there is an obstruction in the branches of heart, this results in pulses to travel slower than the usual. Our current study involved is to diagnose this heart problem using Adaptive Bacterial Foraging Optimization (ABFO Algorithm. The Data collected from MIT/BIH arrhythmia BBB database applied to an ABFO Algorithm for obtaining best(important feature from each ECG beat. These features later fed to Levenberg Marquardt Neural Network (LMNN based classifier. The results show the proposed classification using ABFO is better than some recent algorithms reported in the literature.

  20. Architecture of a flagellar apparatus in the fast-swimming magnetotactic bacterium MO-1.

    Science.gov (United States)

    Ruan, Juanfang; Kato, Takayuki; Santini, Claire-Lise; Miyata, Tomoko; Kawamoto, Akihiro; Zhang, Wei-Jia; Bernadac, Alain; Wu, Long-Fei; Namba, Keiichi

    2012-12-11

    The bacterial flagellum is a motility organelle that consists of a rotary motor and a helical propeller. The flagella usually work individually or by forming a loose bundle to produce thrust. However, the flagellar apparatus of marine bacterium MO-1 is a tight bundle of seven flagellar filaments enveloped in a sheath, and it has been a mystery as to how the flagella rotate smoothly in coordination. Here we have used electron cryotomography to visualize the 3D architecture of the sheathed flagella. The seven filaments are enveloped with 24 fibrils in the sheath, and their basal bodies are arranged in an intertwined hexagonal array similar to the thick and thin filaments of vertebrate skeletal muscles. This complex and exquisite architecture strongly suggests that the fibrils counter-rotate between flagella in direct contact to minimize the friction of high-speed rotation of individual flagella in the tight bundle within the sheath to enable MO-1 cells to swim at about 300 µm/s.

  1. The Non-Flagellar Type III Secretion System Evolved from the Bacterial Flagellum and Diversified into Host-Cell Adapted Systems

    Science.gov (United States)

    Abby, Sophie S.; Rocha, Eduardo P. C.

    2012-01-01

    Type 3 secretion systems (T3SSs) are essential components of two complex bacterial machineries: the flagellum, which drives cell motility, and the non-flagellar T3SS (NF-T3SS), which delivers effectors into eukaryotic cells. Yet the origin, specialization, and diversification of these machineries remained unclear. We developed computational tools to identify homologous components of the two systems and to discriminate between them. Our analysis of >1,000 genomes identified 921 T3SSs, including 222 NF-T3SSs. Phylogenomic and comparative analyses of these systems argue that the NF-T3SS arose from an exaptation of the flagellum, i.e. the recruitment of part of the flagellum structure for the evolution of the new protein delivery function. This reconstructed chronology of the exaptation process proceeded in at least two steps. An intermediate ancestral form of NF-T3SS, whose descendants still exist in Myxococcales, lacked elements that are essential for motility and included a subset of NF-T3SS features. We argue that this ancestral version was involved in protein translocation. A second major step in the evolution of NF-T3SSs occurred via recruitment of secretins to the NF-T3SS, an event that occurred at least three times from different systems. In rhizobiales, a partial homologous gene replacement of the secretin resulted in two genes of complementary function. Acquisition of a secretin was followed by the rapid adaptation of the resulting NF-T3SSs to multiple, distinct eukaryotic cell envelopes where they became key in parasitic and mutualistic associations between prokaryotes and eukaryotes. Our work elucidates major steps of the evolutionary scenario leading to extant NF-T3SSs. It demonstrates how molecular evolution can convert one complex molecular machine into a second, equally complex machine by successive deletions, innovations, and recruitment from other molecular systems. PMID:23028376

  2. The non-flagellar type III secretion system evolved from the bacterial flagellum and diversified into host-cell adapted systems.

    Directory of Open Access Journals (Sweden)

    Sophie S Abby

    2012-09-01

    Full Text Available Type 3 secretion systems (T3SSs are essential components of two complex bacterial machineries: the flagellum, which drives cell motility, and the non-flagellar T3SS (NF-T3SS, which delivers effectors into eukaryotic cells. Yet the origin, specialization, and diversification of these machineries remained unclear. We developed computational tools to identify homologous components of the two systems and to discriminate between them. Our analysis of >1,000 genomes identified 921 T3SSs, including 222 NF-T3SSs. Phylogenomic and comparative analyses of these systems argue that the NF-T3SS arose from an exaptation of the flagellum, i.e. the recruitment of part of the flagellum structure for the evolution of the new protein delivery function. This reconstructed chronology of the exaptation process proceeded in at least two steps. An intermediate ancestral form of NF-T3SS, whose descendants still exist in Myxococcales, lacked elements that are essential for motility and included a subset of NF-T3SS features. We argue that this ancestral version was involved in protein translocation. A second major step in the evolution of NF-T3SSs occurred via recruitment of secretins to the NF-T3SS, an event that occurred at least three times from different systems. In rhizobiales, a partial homologous gene replacement of the secretin resulted in two genes of complementary function. Acquisition of a secretin was followed by the rapid adaptation of the resulting NF-T3SSs to multiple, distinct eukaryotic cell envelopes where they became key in parasitic and mutualistic associations between prokaryotes and eukaryotes. Our work elucidates major steps of the evolutionary scenario leading to extant NF-T3SSs. It demonstrates how molecular evolution can convert one complex molecular machine into a second, equally complex machine by successive deletions, innovations, and recruitment from other molecular systems.

  3. Nanobody-Displaying Flagellar Nanotubes.

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    Klein, Ágnes; Kovács, Mátyás; Muskotál, Adél; Jankovics, Hajnalka; Tóth, Balázs; Pósfai, Mihály; Vonderviszt, Ferenc

    2018-02-26

    In this work we addressed the problem how to fabricate self-assembling tubular nanostructures displaying target recognition functionalities. Bacterial flagellar filaments, composed of thousands of flagellin subunits, were used as scaffolds to display single-domain antibodies (nanobodies) on their surface. As a representative example, an anti-GFP nanobody was successfully inserted into the middle part of flagellin replacing the hypervariable surface-exposed D3 domain. A novel procedure was developed to select appropriate linkers required for functional internal insertion. Linkers of various lengths and conformational properties were chosen from a linker database and they were randomly attached to both ends of an anti-GFP nanobody to facilitate insertion. Functional fusion constructs capable of forming filaments on the surface of flagellin-deficient host cells were selected by magnetic microparticles covered by target GFP molecules and appropriate linkers were identified. TEM studies revealed that short filaments of 2-900 nm were formed on the cell surface. ITC and fluorescent measurements demonstrated that the fusion protein exhibited high binding affinity towards GFP. Our approach allows the development of functionalized flagellar nanotubes against a variety of important target molecules offering potential applications in biosensorics and bio-nanotechnology.

  4. Preparation and preliminary X-ray diffraction analysis of crystals of bacterial flagellar sigma factor σ28 in complex with the σ28-binding region of its antisigma factor, FlgM

    International Nuclear Information System (INIS)

    Okada, Kengo; Ichihara, Hisako; Takahashi, Hiroyuki; Fujita, Nobuyuki; Ishihama, Akira; Hakoshima, Toshio

    2007-01-01

    A complex of E. coli flagellar and chemotaxis-specific sigma factor σ 28 bound to the σ 28 -binding region of its antisigma factor FlgM was crystallized. Diffraction data were collected to a resolution of 2.7 Å. The sigma 28 kDa (σ 28 ) factor is a transcription factor specific for the expression of bacterial flagellar and chemotaxis genes. Its antisigma factor, FlgM, binds σ 28 factor and inhibits its activity as a transcription factor. In this study, crystals of the complex between Escherichia coli σ 28 and the C-terminal σ 28 -binding region of FlgM were obtained. The crystals belong to space group P3 1 21 or P3 2 21, with unit-cell parameters a = b = 106.7 (2), c = 51.74 (3) Å, containing one complex in the crystallographic asymmetric unit. An X-ray intensity data set was collected to a resolution of 2.7 Å

  5. Bacterial Tubulins A and B Exhibit Polarized Growth, Mixed-Polarity Bundling, and Destabilization by GTP Hydrolysis.

    Science.gov (United States)

    Díaz-Celis, César; Risca, Viviana I; Hurtado, Felipe; Polka, Jessica K; Hansen, Scott D; Maturana, Daniel; Lagos, Rosalba; Mullins, R Dyche; Monasterio, Octavio

    2017-10-01

    Bacteria of the genus Prosthecobacter express homologs of eukaryotic α- and β-tubulin, called BtubA and BtubB (BtubA/B), that have been observed to assemble into filaments in the presence of GTP. BtubA/B polymers are proposed to be composed in vitro by two to six protofilaments in contrast to that in vivo , where they have been reported to form 5-protofilament tubes named bacterial microtubules (bMTs). The btubAB genes likely entered the Prosthecobacter lineage via horizontal gene transfer and may be derived from an early ancestor of the modern eukaryotic microtubule (MT). Previous biochemical studies revealed that BtubA/B polymerization is reversible and that BtubA/B folding does not require chaperones. To better understand BtubA/B filament behavior and gain insight into the evolution of microtubule dynamics, we characterized in vitro BtubA/B assembly using a combination of polymerization kinetics assays and microscopy. Like eukaryotic microtubules, BtubA/B filaments exhibit polarized growth with different assembly rates at each end. GTP hydrolysis stimulated by BtubA/B polymerization drives a stochastic mechanism of filament disassembly that occurs via polymer breakage and/or fast continuous depolymerization. We also observed treadmilling (continuous addition and loss of subunits at opposite ends) of BtubA/B filament fragments. Unlike MTs, polymerization of BtubA/B requires KCl, which reduces the critical concentration for BtubA/B assembly and induces it to form stable mixed-orientation bundles in the absence of any additional BtubA/B-binding proteins. The complex dynamics that we observe in stabilized and unstabilized BtubA/B filaments may reflect common properties of an ancestral eukaryotic tubulin polymer. IMPORTANCE Microtubules are polymers within all eukaryotic cells that perform critical functions; they segregate chromosomes, organize intracellular transport, and support the flagella. These functions rely on the remarkable range of tunable dynamic

  6. Applying torque to the Escherichia coli flagellar motor using magnetic tweezers

    OpenAIRE

    van Oene, M.M.; Dickinson, L.E.; Cross, B.; Pedaci, F.; Lipfert, J.; Dekker, N.H.

    2017-01-01

    The bacterial flagellar motor of Escherichia coli is a nanoscale rotary engine essential for bacterial propulsion. Studies on the power output of single motors rely on the measurement of motor torque and rotation under external load. Here, we investigate the use of magnetic tweezers, which in principle allow the application and active control of a calibrated load torque, to study single flagellar motors in Escherichia coli. We manipulate the external load on the motor by adjusting the magneti...

  7. H(+) and Na(+) are involved in flagellar rotation of the spirochete Leptospira.

    Science.gov (United States)

    Islam, Md Shafiqul; Morimoto, Yusuke V; Kudo, Seishi; Nakamura, Shuichi

    2015-10-16

    Leptospira is a spirochete possessing intracellular flagella. Each Leptospira flagellar filament is linked with a flagellar motor composed of a rotor and a dozen stators. For many bacterial species, it is known that the stator functions as an ion channel and that the ion flux through the stator is coupled with flagellar rotation. The coupling ion varies depending on the species; for example, H(+) is used in Escherichia coli, and Na(+) is used in Vibrio spp. to drive a polar flagellum. Although genetic and structural studies illustrated that the Leptospira flagellar motor also contains a stator, the coupling ion for flagellar rotation remains unknown. In the present study, we analyzed the motility of Leptospira under various pH values and salt concentrations. Leptospira cells displayed motility in acidic to alkaline pH. In the presence of a protonophore, the cells completely lost motility in acidic to neutral pH but displayed extremely slow movement under alkaline conditions. This result suggests that H(+) is a major coupling ion for flagellar rotation over a wide pH range; however, we also observed that the motility of Leptospira was significantly enhanced by the addition of Na(+), though it vigorously moved even under Na(+)-free conditions. These results suggest that H(+) is preferentially used and that Na(+) is secondarily involved in flagellar rotation in Leptospira. The flexible ion selectivity in the flagellar system could be advantageous for Leptospira to survive in a wide range of environment. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. H{sup +} and Na{sup +} are involved in flagellar rotation of the spirochete Leptospira

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Md. Shafiqul [Department of Applied Physics, Graduate School of Engineering, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Morimoto, Yusuke V. [Quantitative Biology Center, RIKEN, 6-2-3 Furuedai, Suita, Osaka 565-0874 (Japan); Graduate School of Frontier BioSciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871 (Japan); Kudo, Seishi [Department of Applied Physics, Graduate School of Engineering, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Nakamura, Shuichi, E-mail: naka@bp.apph.tohoku.ac.jp [Department of Applied Physics, Graduate School of Engineering, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Graduate School of Frontier BioSciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2015-10-16

    Leptospira is a spirochete possessing intracellular flagella. Each Leptospira flagellar filament is linked with a flagellar motor composed of a rotor and a dozen stators. For many bacterial species, it is known that the stator functions as an ion channel and that the ion flux through the stator is coupled with flagellar rotation. The coupling ion varies depending on the species; for example, H{sup +} is used in Escherichia coli, and Na{sup +} is used in Vibrio spp. to drive a polar flagellum. Although genetic and structural studies illustrated that the Leptospira flagellar motor also contains a stator, the coupling ion for flagellar rotation remains unknown. In the present study, we analyzed the motility of Leptospira under various pH values and salt concentrations. Leptospira cells displayed motility in acidic to alkaline pH. In the presence of a protonophore, the cells completely lost motility in acidic to neutral pH but displayed extremely slow movement under alkaline conditions. This result suggests that H{sup +} is a major coupling ion for flagellar rotation over a wide pH range; however, we also observed that the motility of Leptospira was significantly enhanced by the addition of Na{sup +}, though it vigorously moved even under Na{sup +}-free conditions. These results suggest that H{sup +} is preferentially used and that Na{sup +} is secondarily involved in flagellar rotation in Leptospira. The flexible ion selectivity in the flagellar system could be advantageous for Leptospira to survive in a wide range of environment. - Highlights: • This is a study on input energy for motility in the spirochete Leptospira. • Leptospira biflexa exhibited active motility in acidic to alkaline pH. • Both H{sup +} and Na{sup +} are involved in flagellar rotation in Leptospira. • H{sup +} is a primary energy source, but Na{sup +} can secondarily enhance motility.

  9. H+ and Na+ are involved in flagellar rotation of the spirochete Leptospira

    International Nuclear Information System (INIS)

    Islam, Md. Shafiqul; Morimoto, Yusuke V.; Kudo, Seishi; Nakamura, Shuichi

    2015-01-01

    Leptospira is a spirochete possessing intracellular flagella. Each Leptospira flagellar filament is linked with a flagellar motor composed of a rotor and a dozen stators. For many bacterial species, it is known that the stator functions as an ion channel and that the ion flux through the stator is coupled with flagellar rotation. The coupling ion varies depending on the species; for example, H + is used in Escherichia coli, and Na + is used in Vibrio spp. to drive a polar flagellum. Although genetic and structural studies illustrated that the Leptospira flagellar motor also contains a stator, the coupling ion for flagellar rotation remains unknown. In the present study, we analyzed the motility of Leptospira under various pH values and salt concentrations. Leptospira cells displayed motility in acidic to alkaline pH. In the presence of a protonophore, the cells completely lost motility in acidic to neutral pH but displayed extremely slow movement under alkaline conditions. This result suggests that H + is a major coupling ion for flagellar rotation over a wide pH range; however, we also observed that the motility of Leptospira was significantly enhanced by the addition of Na + , though it vigorously moved even under Na + -free conditions. These results suggest that H + is preferentially used and that Na + is secondarily involved in flagellar rotation in Leptospira. The flexible ion selectivity in the flagellar system could be advantageous for Leptospira to survive in a wide range of environment. - Highlights: • This is a study on input energy for motility in the spirochete Leptospira. • Leptospira biflexa exhibited active motility in acidic to alkaline pH. • Both H + and Na + are involved in flagellar rotation in Leptospira. • H + is a primary energy source, but Na + can secondarily enhance motility.

  10. Applying torque to the Escherichia coli flagellar motor using magnetic tweezers

    NARCIS (Netherlands)

    van Oene, M.M.; Dickinson, L.E.; Cross, B.; Pedaci, F.; Lipfert, J.; Dekker, N.H.

    2017-01-01

    The bacterial flagellar motor of Escherichia coli is a nanoscale rotary engine essential for bacterial propulsion. Studies on the power output of single motors rely on the measurement of motor torque and rotation under external load. Here, we investigate the use of magnetic tweezers, which in

  11. Bundling of elastic filaments induced by hydrodynamic interactions

    Science.gov (United States)

    Man, Yi; Page, William; Poole, Robert J.; Lauga, Eric

    2017-12-01

    Peritrichous bacteria swim in viscous fluids by rotating multiple helical flagellar filaments. As the bacterium swims forward, all its flagella rotate in synchrony behind the cell in a tight helical bundle. When the bacterium changes its direction, the flagellar filaments unbundle and randomly reorient the cell for a short period of time before returning to their bundled state and resuming swimming. This rapid bundling and unbundling is, at its heart, a mechanical process whereby hydrodynamic interactions balance with elasticity to determine the time-varying deformation of the filaments. Inspired by this biophysical problem, we present in this paper what is perhaps the simplest model of bundling whereby two or more straight elastic filaments immersed in a viscous fluid rotate about their centerline, inducing rotational flows which tend to bend the filaments around each other. We derive an integrodifferential equation governing the shape of the filaments resulting from mechanical balance in a viscous fluid at low Reynolds number. We show that such equation may be evaluated asymptotically analytically in the long-wavelength limit, leading to a local partial differential equation governed by a single dimensionless bundling number. A numerical study of the dynamics predicted by the model reveals the presence of two configuration instabilities with increasing bundling numbers: first to a crossing state where filaments touch at one point and then to a bundled state where filaments wrap along each other in a helical fashion. We also consider the case of multiple filaments and the unbundling dynamics. We next provide an intuitive physical model for the crossing instability and show that it may be used to predict analytically its threshold and adapted to address the transition to a bundling state. We then use a macroscale experimental implementation of the two-filament configuration in order to validate our theoretical predictions and obtain excellent agreement. This long

  12. Complex spatial organization and flagellin composition of flagellar propeller from marine magnetotactic ovoid strain MO-1.

    Science.gov (United States)

    Zhang, Wei-Jia; Santini, Claire-Lise; Bernadac, Alain; Ruan, Juanfang; Zhang, Sheng-Da; Kato, Takayuki; Li, Ying; Namba, Keiichi; Wu, Long-Fei

    2012-03-02

    Marine magnetotactic ovoid bacterium MO-1 is capable of swimming along the geomagnetic field lines by means of its two sheathed flagellar bundles at a speed up to 300 μm/s. In this study, by using electron microscopy, we showed that, in each bundle, six individual flagella were organized in hexagon with a seventh in the middle. We identified 12 flagellin paralogs and 2 putative flagellins in the genome of MO-1. Among them, 13 were tandemly located on an ~ 17-kb segment while the 14th was on a separated locus. Using reverse transcription PCR and quantitative PCR, we found that all the 14 flagellin or putative flagellin genes were transcribed and that 2 of them were more abundantly expressed than others. A nLC (nanoliquid chromatography)-ESI (electrospray ionization)-MS/MS (mass spectrometry/mass spectrometry) mass spectrometry analysis identified all the 12 flagellin proteins in three glycosylated polypeptide bands resolved by one-dimensional denaturing polyacrylamide gel electrophoresis and 10 of them in 21 spots obtained by means of two-dimensional electrophoresis of flagellar extracts. Most spots contained more than one flagellin, and eight of the ten identified flagellins existed in multiple isoforms. Taken together, these results show unprecedented complexity in the spatial organization and flagellin composition of the flagellar propeller. Such architecture is observed only for ovoid-coccoid, bilophotrichously flagellated magnetotactic bacteria living in marine sediments, suggesting a species and environmental specificity. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Isolation and characterization of flagellar filaments from Bacillus cereus ATCC 14579.

    Science.gov (United States)

    Tagawa, Yuichi

    2014-12-01

    Isolated flagellar filaments from the type strain of Bacillus cereus, ATCC 14579, were shown to consist of 34, 32 and 31 kDa proteins in similar proportions as judged by band intensities on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The N-terminal amino acid sequences of these three proteins of strain ATCC 14579 were identical with the deduced sequences of three flagellin genes BC1657, BC1658 and BC1659 in the whole genome sequence. Strain ATCC 14579 was classified into serotype T2 by a flagellar serotyping scheme for B. cereus strains that are untypeable into known flagellar serotypes H1 to H23. Flagellar filaments from a reference strain of serotype T2 contained two protein bands at 34 and 32 kDa, but a single protein band at 39 kDa was detected in flagellar filaments of a reference strain of serotype H1. Two murine monoclonal antibodies, 1A5 and 2A5, which recognize both the 34 and 32 kDa flagellins and a single flagellin of 32 kDa, respectively, were specifically reactive with B. cereus strains ATCC 14579 and serotype T2 in whole-cell ELISA and bacterial motility inhibition tests. In immunoelectron microscopy with monoclonal antibodies 1A5 and 2A5, colloidal gold spheres were shown to localize almost evenly over the entire part of flagellar filaments. Since strain ATCC 14579, and presumably strain serotype T2, are unusual among B. cereus strains in possessing multiple genes that encode flagellin subunits, a possible unique mechanism may contribute to assembly of multiple flagellin subunits into the filament over its entire length.

  14. Interactions between flagellar and type III secretion proteins in Chlamydia pneumoniae

    Directory of Open Access Journals (Sweden)

    Mahony James B

    2010-01-01

    Full Text Available Abstract Background Flagellar secretion systems are utilized by a wide variety of bacteria to construct the flagellum, a conserved apparatus that allows for migration towards non-hostile, nutrient rich environments. Chlamydia pneumoniae is an obligate, intracellular pathogen whose genome contains at least three orthologs of flagellar proteins, namely FliI, FlhA and FliF, but the role of these proteins remains unknown. Results Full length FliI, and fragments of FlhA, FliF, and FliI, were cloned and expressed as either GST or His tagged proteins in E. coli. The GST-tagged full length FliI protein was shown to possess ATPase activity, hydrolyzing ATP at a rate of 0.15 ± .02 μmol min-1 mg-1 in a time- and dose-dependant manner. Using bacterial-2-hybrid and GST pull-down assays, the N-terminal domain of FliI was shown to interact with the cytoplasmic domain of FlhA, but not with FliF, and the cytoplasmic domain of FlhA was shown to interact with the C-terminus of FliF. The absence of other flagellar orthologs led us to explore cross-reaction of flagellar proteins with type III secretion proteins, and we found that FliI interacted with CdsL and CopN, while FlhA interacted with CdsL and Cpn0322 (YscU ortholog CdsU. Conclusions The specific interaction of the four orthologous flagellar proteins in C. pneumoniae suggests that they interact in vivo and, taken together with their conservation across members of the chlamydiae sps., and their interaction with T3S components, suggests a role in bacterial replication and/or intracellular survival.

  15. Dual stator dynamics in the Shewanella oneidensis MR-1 flagellar motor.

    Science.gov (United States)

    Paulick, Anja; Delalez, Nicolas J; Brenzinger, Susanne; Steel, Bradley C; Berry, Richard M; Armitage, Judith P; Thormann, Kai M

    2015-06-01

    The bacterial flagellar motor is an intricate nanomachine which converts ion gradients into rotational movement. Torque is created by ion-dependent stator complexes which surround the rotor in a ring. Shewanella oneidensis MR-1 expresses two distinct types of stator units: the Na(+)-dependent PomA4 B2 and the H(+)-dependent MotA4 B2. Here, we have explored the stator unit dynamics in the MR-1 flagellar system by using mCherry-labeled PomAB and MotAB units. We observed a total of between 7 and 11 stator units in each flagellar motor. Both types of stator units exchanged between motors and a pool of stator complexes in the membrane, and the exchange rate of MotAB, but not of PomAB, units was dependent on the environmental Na(+)-levels. In 200 mM Na(+), the numbers of PomAB and MotAB units in wild-type motors was determined to be about 7:2 (PomAB:MotAB), shifting to about 6:5 without Na(+). Significantly, the average swimming speed of MR-1 cells at low Na(+) conditions was increased in the presence of MotAB. These data strongly indicate that the S. oneidensis flagellar motors simultaneously use H(+) and Na(+) driven stators in a configuration governed by MotAB incorporation efficiency in response to environmental Na(+) levels. © 2015 John Wiley & Sons Ltd.

  16. Bacterial signaling and motility: Sure bets

    Energy Technology Data Exchange (ETDEWEB)

    Zhulin, Igor B [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL)

    2008-01-01

    cytoplasmic membrane. The interaction causes the supramembrane and cytoplasmic rings to rotate along with the flagellar filaments. The energy for flagellar rotation comes from proton motive force or other ions, especially sodium in marine bacteria, which generate an electrochemical gradient across the cell membrane. Three proteins, FliM, FliN, and FliG, located at the base of the motor act as switches that control the direction of flagellar rotation. As exemplified by the enteric bacteria Escherichia coli and Salmonella enterica serovar Typhimurium, changes in the direction of flagellar rotation affect the swimming behavior of the bacterial cell. Counterclockwise (CCW) rotation of the flagella causes the flagellar filaments to form a bundle that pushes the cell forward in a 'run.' In contrast, clockwise (CW) rotation causes the flagellar bundle to fly apart, and the cell tumbles to reorient to a new direction for the ensuing run upon the return of CCW rotation. The interchanging pattern of CCW and CW rotations produces a random walk, composed of relatively long runs with occasional direction changes or turns. By modulating the lengths of the runs or the frequency of tumbling, bacteria can regulate their motile behavior to move in a desirable direction. Many bacteria can also move on surfaces. Except for flagellum-driven swarming motility, all the other forms of known bacterial surface movement involve no flagella. The flagellum-independent surface motility, known as gliding, is observed in cyanobacteria, Mycoplasma species, Cytophaga-Flexibacterium species, and Myxococcus species. Without a doubt, the most thoroughly studied model gliding bacterium is Myxococcus xanthus, which also serves as a prokaryotic model for developmental biology due to its ability to develop multicellular fruiting bodies. M. xanthus cells use gliding motility both to hunt for food during vegetative growth and to aggregate during fruiting body formation. When nutrients are present, groups of

  17. Inactivation of ferric uptake regulator (Fur) attenuates Helicobacter pylori J99 motility by disturbing the flagellar motor switch and autoinducer-2 production.

    Science.gov (United States)

    Lee, Ai-Yun; Kao, Cheng-Yen; Wang, Yao-Kuan; Lin, Ssu-Yuan; Lai, Tze-Ying; Sheu, Bor-Shyang; Lo, Chien-Jung; Wu, Jiunn-Jong

    2017-08-01

    Flagellar motility of Helicobacter pylori has been shown to be important for the bacteria to establish initial colonization. The ferric uptake regulator (Fur) is a global regulator that has been identified in H. pylori which is involved in the processes of iron uptake and establishing colonization. However, the role of Fur in H. pylori motility is still unclear. Motility of the wild-type, fur mutant, and fur revertant J99 were determined by a soft-agar motility assay and direct video observation. The bacterial shape and flagellar structure were evaluated by transmission electron microscopy. Single bacterial motility and flagellar switching were observed by phase-contrast microscopy. Autoinducer-2 (AI-2) production in bacterial culture supernatant was analyzed by a bioluminescence assay. The fur mutant showed impaired motility in the soft-agar assay compared with the wild-type J99 and fur revertant. The numbers and lengths of flagellar filaments on the fur mutant cells were similar to those of the wild-type and revertant cells. Phenotypic characterization showed similar swimming speed but reduction in switching rate in the fur mutant. The AI-2 production of the fur mutant was dramatically reduced compared with wild-type J99 in log-phase culture medium. These results indicate that Fur positively modulates H. pylori J99 motility through interfering with bacterial flagellar switching. © 2017 John Wiley & Sons Ltd.

  18. Slipping slender bodies and enhanced flagellar locomotion

    Science.gov (United States)

    Man, Yi; Lauga, Eric

    2017-11-01

    In the biological world, many cells exploit slender appendages to swim, include numerous species of bacteria, algae and spermatozoa. A classical method to describe the flow field around such appendages is slender-body theory (SBT), which is often used to study flagellar motility in Newtonian fluids. However, biology environments are often rheologically complex due to the presence of polymers. These polymers generically phase-separate near rigid boundaries where low-viscosity fluid layers lead to effective slip on the surface. In this talk, we present an analytical derivation of SBT in the case where the no-slip boundary condition on the appendage is replaced by a Navier slip boundary condition. Our results demonstrate in particular a systematic reduction of the resistance coefficient of the slender filaments in their tangential direction, which leads to enhanced flagellar locomotion.

  19. Flagellar Motility of Trypanosoma cruzi Epimastigotes

    Directory of Open Access Journals (Sweden)

    G. Ballesteros-Rodea

    2012-01-01

    Full Text Available The hemoflagellate Trypanosoma cruzi is the causative agent of American trypanosomiasis. Despite the importance of motility in the parasite life cycle, little is known about T. cruzi motility, and there is no quantitative description of its flagellar beating. Using video microscopy and quantitative vectorial analysis of epimastigote trajectories, we find a forward parasite motility defined by tip-to-base symmetrical flagellar beats. This motion is occasionally interrupted by base-to-tip highly asymmetric beats, which represent the ciliary beat of trypanosomatid flagella. The switch between flagellar and ciliary beating facilitates the parasite's reorientation, which produces a large variability of movement and trajectories that results in different distance ranges traveled by the cells. An analysis of the distance, speed, and rotational angle indicates that epimastigote movement is not completely random, and the phenomenon is highly dependent on the parasite behavior and is characterized by directed and tumbling parasite motion as well as their combination, resulting in the alternation of rectilinear and intricate motility paths.

  20. Flagellar motility confers epiphytic fitness advantages upon Pseudomonas syringae

    International Nuclear Information System (INIS)

    Haefele, D.M.; Lindow, S.E.

    1987-01-01

    The role of flagellar motility in determining the epiphytic fitness of an ice-nucleation-active strain of Pseudomonas syringae was examined. The loss of flagellar motility reduced the epiphytic fitness of a normally motile P. syringae strain as measured by its growth, survival, and competitive ability on bean leaf surfaces. Equal population sizes of motile parental or nonmotile mutant P. syringae strains were maintained on bean plants for at least 5 days following the inoculation of fully expanded primary leaves. However, when bean seedlings were inoculated before the primary leaves had expanded and bacterial populations on these leaves were quantified at full expansion, the population size of the nonmotile derivative strain reached only 0.9% that of either the motile parental or revertant strain. When fully expanded bean primary leaves were coinoculated with equal numbers of motile and nonmotile cells, the population size of a nonmotile derivative strain was one-third of that of the motile parental or revertant strain after 8 days. Motile and nonmotile cells were exposed in vitro and on plants to UV radiation and desiccating conditions. The motile and nonmotile strains exhibited equal resistance to both stresses in vitro. However, the population size of a nonmotile strain on leaves was less than 20% that of a motile revertant strain when sampled immediately after UV irradiation. Epiphytic populations of both motile and nonmotile P. syringae declined under desiccating conditions on plants, and after 8 days, the population size of a nonmotile strain was less than one-third that of the motile parental or revertant strain

  1. Shear Stress Transmission Model for the Flagellar Rotary Motor

    Directory of Open Access Journals (Sweden)

    Hiroyuki Ohshima

    2008-09-01

    Full Text Available Most bacteria that swim are propelled by flagellar filaments, which are driven by a rotary motor powered by proton flux. The mechanism of the flagellar motor is discussed by reforming the model proposed by the present authors in 2005. It is shown that the mean strength of Coulomb field produced by a proton passing the channel is very strong in the Mot assembly so that the Mot assembly can be a shear force generator and induce the flagellar rotation. The model gives clear calculation results in agreement with experimental observations, e g., for the charasteristic torque-velocity relationship of the flagellar rotation.

  2. Strategic Aspects of Bundling

    International Nuclear Information System (INIS)

    Podesta, Marion

    2008-01-01

    The increase of bundle supply has become widespread in several sectors (for instance in telecommunications and energy fields). This paper review relates strategic aspects of bundling. The main purpose of this paper is to analyze profitability of bundling strategies according to the degree of competition and the characteristics of goods. Moreover, bundling can be used as price discrimination tool, screening device or entry barriers. In monopoly case bundling strategy is efficient to sort consumers in different categories in order to capture a maximum of surplus. However, when competition increases, the profitability on bundling strategies depends on correlation of consumers' reservations values. (author)

  3. Tetrameric structure of the flagellar cap protein FliD from Serratia marcescens.

    Science.gov (United States)

    Cho, So Yeon; Song, Wan Seok; Hong, Ho Jeong; Lee, Geun-Shik; Kang, Seung Goo; Ko, Hyun-Jeong; Kim, Pyeung-Hyeun; Yoon, Sung-Il

    2017-07-15

    Bacterial motility is provided by the flagellum. FliD is located at the distal end of the flagellum and plays a key role in the insertion of each flagellin protein at the growing tip of the flagellar filament. Because FliD functions as an oligomer, the determination of the oligomeric state of FliD is critical to understanding the molecular mechanism of FliD-mediated flagellar growth. FliD has been shown to adopt a pentameric or a hexameric structure depending on the bacterial species. Here, we report another distinct oligomeric form of FliD based on structural and biochemical studies. The crystal structures of the D2 and D3 domains of Serratia marcescens FliD (smFliD) were determined in two crystal forms and together revealed that smFliD assembles into a tetrameric architecture that resembles a four-pointed star plate. smFliD tetramerization was also confirmed in solution by cross-linking experiments. Although smFliD oligomerizes in a head-to-tail orientation using a common primary binding interface between the D2 and D3' domains (the prime denotes the second subunit in the oligomer) similarly to other FliD orthologs, the smFliD tetramer diverges to present a unique secondary D2-D2' binding interface. Our structure-based comparative analysis of FliD suggests that bacteria have developed diverse species-specific oligomeric forms of FliD that range from tetramers to hexamers for flagellar growth. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Evolution of the microtubular cytoskeleton (flagellar apparatus) in parasitic protists.

    Science.gov (United States)

    Yubuki, Naoji; Čepička, Ivan; Leander, Brian S

    The microtubular cytoskeleton of most single-celled eukaryotes radiates from an organizing center called the flagellar apparatus, which is essential for locomotion, feeding and reproduction. The structure of the flagellar apparatus tends to be conserved within diverse clades of eukaryotes, and modifications of this overall structure distinguish different clades from each other. Understanding the unity and diversity of the flagellar apparatus provides important insights into the evolutionary history of the eukaryotic cell. Diversification of the flagellar apparatus is particularly apparent during the multiple independent transitions to parasitic lifestyles from free-living ancestors. However, our understanding of these evolutionary transitions is hampered by the lack of detailed comparisons of the microtubular root systems in different lineages of parasitic microbial eukaryotes and those of their closest free-living relatives. Here we help to establish this comparative context by examining the unity and diversity of the flagellar apparatus in six major clades containing both free-living lineages and endobiotic (parasitic and symbiotic) microbial eukaryotes: stramenopiles (e.g., Phytophthora), fornicates (e.g., Giardia), parabasalids (e.g., Trichomonas), preaxostylids (e.g., Monocercomonoides), kinetoplastids (e.g., Trypanosoma), and apicomplexans (e.g., Plasmodium). These comparisons enabled us to address some broader patterns associated with the evolution of parasitism, including a general trend toward a more streamlined flagellar apparatus. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Applying torque to the Escherichia coli flagellar motor using magnetic tweezers.

    Science.gov (United States)

    van Oene, Maarten M; Dickinson, Laura E; Cross, Bronwen; Pedaci, Francesco; Lipfert, Jan; Dekker, Nynke H

    2017-03-07

    The bacterial flagellar motor of Escherichia coli is a nanoscale rotary engine essential for bacterial propulsion. Studies on the power output of single motors rely on the measurement of motor torque and rotation under external load. Here, we investigate the use of magnetic tweezers, which in principle allow the application and active control of a calibrated load torque, to study single flagellar motors in Escherichia coli. We manipulate the external load on the motor by adjusting the magnetic field experienced by a magnetic bead linked to the motor, and we probe the motor's response. A simple model describes the average motor speed over the entire range of applied fields. We extract the motor torque at stall and find it to be similar to the motor torque at drag-limited speed. In addition, use of the magnetic tweezers allows us to force motor rotation in both forward and backward directions. We monitor the motor's performance before and after periods of forced rotation and observe no destructive effects on the motor. Our experiments show how magnetic tweezers can provide active and fast control of the external load while also exposing remaining challenges in calibration. Through their non-invasive character and straightforward parallelization, magnetic tweezers provide an attractive platform to study nanoscale rotary motors at the single-motor level.

  6. Applying torque to the Escherichia coli flagellar motor using magnetic tweezers

    Science.gov (United States)

    van Oene, Maarten M.; Dickinson, Laura E.; Cross, Bronwen; Pedaci, Francesco; Lipfert, Jan; Dekker, Nynke H.

    2017-01-01

    The bacterial flagellar motor of Escherichia coli is a nanoscale rotary engine essential for bacterial propulsion. Studies on the power output of single motors rely on the measurement of motor torque and rotation under external load. Here, we investigate the use of magnetic tweezers, which in principle allow the application and active control of a calibrated load torque, to study single flagellar motors in Escherichia coli. We manipulate the external load on the motor by adjusting the magnetic field experienced by a magnetic bead linked to the motor, and we probe the motor’s response. A simple model describes the average motor speed over the entire range of applied fields. We extract the motor torque at stall and find it to be similar to the motor torque at drag-limited speed. In addition, use of the magnetic tweezers allows us to force motor rotation in both forward and backward directions. We monitor the motor’s performance before and after periods of forced rotation and observe no destructive effects on the motor. Our experiments show how magnetic tweezers can provide active and fast control of the external load while also exposing remaining challenges in calibration. Through their non-invasive character and straightforward parallelization, magnetic tweezers provide an attractive platform to study nanoscale rotary motors at the single-motor level. PMID:28266562

  7. The MogR Transcriptional Repressor Regulates Nonhierarchal Expression of Flagellar Motility Genes and Virulence in Listeria monocytogenes.

    Directory of Open Access Journals (Sweden)

    2006-04-01

    Full Text Available Flagella are surface structures critical for motility and virulence of many bacterial species. In Listeria monocytogenes, MogR tightly represses expression of flagellin (FlaA during extracellular growth at 37 degrees C and during intracellular infection. MogR is also required for full virulence in a murine model of infection. Using in vitro and in vivo infection models, we determined that the severe virulence defect of MogR-negative bacteria is due to overexpression of FlaA. Specifically, overproduction of FlaA in MogR-negative bacteria caused pleiotropic defects in bacterial division (chaining phenotype, intracellular spread, and virulence in mice. DNA binding and microarray analyses revealed that MogR represses transcription of all known flagellar motility genes by binding directly to a minimum of two TTTT-N(5-AAAA recognition sites positioned within promoter regions such that RNA polymerase binding is occluded. Analysis of MogR protein levels demonstrated that modulation of MogR repression activity confers the temperature-specificity to flagellar motility gene expression. Epistasis analysis revealed that MogR repression of transcription is antagonized in a temperature-dependent manner by the DegU response regulator and that DegU further regulates FlaA levels through a posttranscriptional mechanism. These studies provide the first known example to our knowledge of a transcriptional repressor functioning as a master regulator controlling nonhierarchal expression of flagellar motility genes.

  8. The ABCDEF Implementation Bundle

    Directory of Open Access Journals (Sweden)

    Annachiara Marra

    2016-08-01

    Full Text Available Long-term morbidity, long-term cognitive impairment and hospitalization-associated disability are common occurrence in the survivors of critical illness, with significant consequences for patients and for the caregivers. The ABCDEF bundle represents an evidence-based guide for clinicians to approach the organizational changes needed for optimizing ICU patient recovery and outcomes. The ABCDEF bundle includes: Assess, Prevent, and Manage Pain, Both Spontaneous Awakening Trials (SAT and Spontaneous Breathing Trials (SBT, Choice of analgesia and sedation, Delirium: Assess, Prevent, and Manage, Early mobility and Exercise, and Family engagement. The purpose of this review is to describe the core features of the ABCDEF bundle.

  9. Design of a Comprehensive Biochemistry and Molecular Biology Experiment: Phase Variation Caused by Recombinational Regulation of Bacterial Gene Expression

    Science.gov (United States)

    Sheng, Xiumei; Xu, Shungao; Lu, Renyun; Isaac, Dadzie; Zhang, Xueyi; Zhang, Haifang; Wang, Huifang; Qiao, Zheng; Huang, Xinxiang

    2014-01-01

    Scientific experiments are indispensable parts of Biochemistry and Molecular Biology. In this study, a comprehensive Biochemistry and Molecular Biology experiment about "Salmonella enterica" serovar Typhi Flagellar phase variation has been designed. It consisted of three parts, namely, inducement of bacterial Flagellar phase variation,…

  10. Bundle Branch Block

    Science.gov (United States)

    ... 2015. Bundle branch block Symptoms & causes Diagnosis & treatment Advertisement Mayo Clinic does not endorse companies or products. ... a Job Site Map About This Site Twitter Facebook Google YouTube Pinterest Mayo Clinic is a not- ...

  11. Dynamics of flagellar force generated by a hyperactivated spermatozoon.

    Science.gov (United States)

    Ishijima, Sumio

    2011-09-01

    The flagellar force generated by a hyperactivated monkey spermatozoon was evaluated using the resistive force theory applied to the activated (nonhyperactivated) and hyperactivated flagellar waves that were obtained using high-speed video microscopy and digital image processing in order to clarify the mechanism of sperm penetration through the zona pellucida. No difference in the maximum propulsive force, which was parallel to the longitudinal sperm head axis, was found between the activated and hyperactivated spermatozoa. The maximum transverse force (45 pN), which was perpendicular to the longitudinal sperm head axis, of the hyperactivated spermatozoon was ∼2.5 times its propulsive force. As the beat frequency of the flagellar beating remarkably decreased during the hyperactivation, the slowly oscillating transverse force (5 Hz) by the hyperactivated spermatozoon seems to be most effective for sperm penetration through the zona pellucida.

  12. The CckA-ChpT-CtrA phosphorelay system is regulated by quorum sensing and controls flagellar motility in the marine sponge symbiont Ruegeria sp. KLH11.

    Directory of Open Access Journals (Sweden)

    Jindong Zan

    Full Text Available Bacteria respond to their environment via signal transduction pathways, often two-component type systems that function through phosphotransfer to control expression of specific genes. Phosphorelays are derived from two-component systems but are comprised of additional components. The essential cckA-chpT-ctrA phosphorelay in Caulobacter crescentus has been well studied and is important in orchestrating the cell cycle, polar development and flagellar biogenesis. Although cckA, chpT and ctrA homologues are widespread among the Alphaproteobacteria, relatively few is known about their function in the large and ecologically significant Roseobacter clade of the Rhodobacterales. In this study the cckA-chpT-ctrA system of the marine sponge symbiont Ruegeria sp. KLH11 was investigated. Our results reveal that the cckA, chpT and ctrA genes positively control flagellar biosynthesis. In contrast to C. crescentus, the cckA, chpT and ctrA genes in Ruegeria sp. KLH11 are non-essential and do not affect bacterial growth. Gene fusion and transcript analyses provide evidence for ctrA autoregulation and the control of motility-related genes. In KLH11, flagellar motility is controlled by the SsaRI system and acylhomoserine lactone (AHL quorum sensing. SsaR and long chain AHLs are required for cckA, chpT and ctrA gene expression, providing a regulatory link between flagellar locomotion and population density in KLH11.

  13. Bacillus subtilis Bactofilins Are Essential for Flagellar Hook- and Filament Assembly and Dynamically Localize into Structures of Less than 100 nm Diameter underneath the Cell Membrane.

    Directory of Open Access Journals (Sweden)

    Jihad El Andari

    Full Text Available Bactofilins are a widely conserved protein family implicated in cell shape maintenance and in bacterial motility. We show that the bactofilins BacE and BacF from Bacillus subtilis are essential for motility. The proteins are required for the establishment of flagellar hook- and filament structures, but apparently not for the formation of basal bodies. Functional YFP fusions to BacE and to BacF localize as discrete assemblies at the B. subtilis cell membrane, and have a diameter of 60 to 70 nm. BacF assemblies are relatively static, and partially colocalize with flagellar basal bodies, while BacE assemblies are fewer per cell than those of BacF and are highly mobile. Tracking of BacE foci showed that the assemblies arrest at a single point for a few hundred milliseconds, showing that a putative interaction with flagellar structures would be transient and fast. When overexpressed or expressed in a heterologous cell system, bactofilins can form filamentous structures, and also form multimers as purified proteins. Our data reveal a propensity for bactofilins to form filaments, however, in B. subtilis cells, bactofilins assemble into defined size assemblies that show a dynamic localization pattern and play a role in flagellar assembly.

  14. Flagellar waveform dynamics of freely swimming algal cells

    NARCIS (Netherlands)

    Kurtuldu, H.; Tam, D.; Hosoi, A.E.; Johnson, K.A.; Gollub, J.P.

    2013-01-01

    We present quantitative measurements of time-dependent flagellar waveforms for freely swimming biflagellated algal cells, for both synchronous and asynchronous beating. We use the waveforms in conjunction with resistive force theory as well as a singularity method to predict a cell's time-dependent

  15. Impaired competence in flagellar mutants of Bacillus subtilis is connected to the regulatory network governed by DegU

    DEFF Research Database (Denmark)

    Hölscher, Theresa; Schiklang, Tina; Dragos, Anna

    2017-01-01

    The competent state is a developmentally distinct phase, in which bacteria are able to take up and integrate exogenous DNA into their genome. Bacillus subtilis is one of the naturally competent bacterial species and the domesticated laboratory strain 168 is easily transformable. In this study, we...... report a reduced transformation frequency of B. subtilis mutants lacking functional and structural flagellar components. This includes hag, the gene encoding the flagellin protein forming the filament of the flagellum. We confirm that the observed decrease of the transformation frequency is due...

  16. Right bundle branch block

    DEFF Research Database (Denmark)

    Bussink, Barbara E; Holst, Anders Gaarsdal; Jespersen, Lasse

    2013-01-01

    AimsTo determine the prevalence, predictors of newly acquired, and the prognostic value of right bundle branch block (RBBB) and incomplete RBBB (IRBBB) on a resting 12-lead electrocardiogram in men and women from the general population.Methods and resultsWe followed 18 441 participants included.......5%/2.3% in women, P Right bundle branch block was associated with significantly...... increased all-cause and cardiovascular mortality in both genders with age-adjusted hazard ratios (HR) of 1.31 [95% confidence interval (CI), 1.11-1.54] and 1.87 (95% CI, 1.48-2.36) in the gender pooled analysis with little attenuation after multiple adjustment. Right bundle branch block was associated...

  17. Flow in rod bundles

    International Nuclear Information System (INIS)

    Hazi, G.; Mayer, G.

    2005-01-01

    For power upgrading VVER-440 reactors we need to know exactly how the temperature measured by the thermocouples is related to the average outlet temperature of the fuel assemblies. Accordingly, detailed knowledge on mixing process in the rod bundles and in the fuel assembly head have great importance. Here we study the hydrodynamics of rod bundles based on the results of direct numerical and large eddy simulation of flows in subchannels. It is shown that secondary flow and flow pulsation phenomena can be observed using both methodologies. Some consequences of these observations are briefly discussed. (author)

  18. Standard-model bundles

    CERN Document Server

    Donagi, Ron; Pantev, Tony; Waldram, Dan; Donagi, Ron; Ovrut, Burt; Pantev, Tony; Waldram, Dan

    2002-01-01

    We describe a family of genus one fibered Calabi-Yau threefolds with fundamental group ${\\mathbb Z}/2$. On each Calabi-Yau $Z$ in the family we exhibit a positive dimensional family of Mumford stable bundles whose symmetry group is the Standard Model group $SU(3)\\times SU(2)\\times U(1)$ and which have $c_{3} = 6$. We also show that for each bundle $V$ in our family, $c_{2}(Z) - c_{2}(V)$ is the class of an effective curve on $Z$. These conditions ensure that $Z$ and $V$ can be used for a phenomenologically relevant compactification of Heterotic M-theory.

  19. ALUMINUM BOX BUNDLING PRESS

    Directory of Open Access Journals (Sweden)

    Iosif DUMITRESCU

    2015-05-01

    Full Text Available In municipal solid waste, aluminum is the main nonferrous metal, approximately 80- 85% of the total nonferrous metals. The income per ton gained from aluminum recuperation is 20 times higher than from glass, steel boxes or paper recuperation. The object of this paper is the design of a 300 kN press for aluminum box bundling.

  20. Irradiated fuel bundle counter

    International Nuclear Information System (INIS)

    Campbell, J.W.; Todd, J.L.

    1975-01-01

    The design of a prototype safeguards instrument for determining the number of irradiated fuel assemblies leaving an on-power refueled reactor is described. Design details include radiation detection techniques, data processing and display, unattended operation capabilities and data security methods. Development and operating history of the bundle counter is reported. (U.S.)

  1. The Logic of Bundles

    Science.gov (United States)

    Harding, John; Yang, Taewon

    2015-12-01

    Since the work of Crown (J. Natur. Sci. Math. 15(1-2), 11-25 1975) in the 1970's, it has been known that the projections of a finite-dimensional vector bundle E form an orthomodular poset ( omp) {P}(E). This result lies in the intersection of a number of current topics, including the categorical quantum mechanics of Abramsky and Coecke (2004), and the approach via decompositions of Harding (Trans. Amer. Math. Soc. 348(5), 1839-1862 1996). Moreover, it provides a source of omps for the quantum logic program close to the Hilbert space setting, and admitting a version of tensor products, yet having important differences from the standard logics of Hilbert spaces. It is our purpose here to initiate a basic investigation of the quantum logic program in the vector bundle setting. This includes observations on the structure of the omps obtained as {P}(E) for a vector bundle E, methods to obtain states on these omps, and automorphisms of these omps. Key theorems of quantum logic in the Hilbert setting, such as Gleason's theorem and Wigner's theorem, provide natural and quite challenging problems in the vector bundle setting.

  2. A novel N-linked flagellar glycan from Methanococcus maripaludis.

    Science.gov (United States)

    Kelly, John; Logan, Susan M; Jarrell, Ken F; VanDyke, David J; Vinogradov, Evgeny

    2009-03-31

    The archaea Methanococcus maripaludis strain Mm900 produces flagella that are glycosylated with an N-linked tetrasaccharide. Mass spectrometric analysis of flagellar tryptic peptides identified a number of tryptic glycopeptides carrying a glycan of mass 1036.4Da, and fragmentation of the glycan oxonium ion indicated that the glycan was a tetrasaccharide. The glycan was purified, following extensive pronase digestion of flagellar filaments, by size-exclusion and anion-exchange chromatography. NMR spectroscopy revealed that the glycan had the following structure: Sug-4-beta-ManNAc3NAmA6Thr-4-beta-GlcNAc3NAcA-3-beta-GalNAc-Asn where Sug is a novel monosaccharide unit, (5S)-2-acetamido-2,4-dideoxy-5-O-methyl-alpha-l-erythro-hexos-5-ulo-1,5-pyranose. This oligosaccharide has significant similarity to the oligosaccharide that was found previously in Methanococcus voltae.

  3. Human sperm steer with second harmonics of the flagellar beat.

    Science.gov (United States)

    Saggiorato, Guglielmo; Alvarez, Luis; Jikeli, Jan F; Kaupp, U Benjamin; Gompper, Gerhard; Elgeti, Jens

    2017-11-10

    Sperm are propelled by bending waves traveling along their flagellum. For steering in gradients of sensory cues, sperm adjust the flagellar waveform. Symmetric and asymmetric waveforms result in straight and curved swimming paths, respectively. Two mechanisms causing spatially asymmetric waveforms have been proposed: an average flagellar curvature and buckling. We image flagella of human sperm tethered with the head to a surface. The waveform is characterized by a fundamental beat frequency and its second harmonic. The superposition of harmonics breaks the beat symmetry temporally rather than spatially. As a result, sperm rotate around the tethering point. The rotation velocity is determined by the second-harmonic amplitude and phase. Stimulation with the female sex hormone progesterone enhances the second-harmonic contribution and, thereby, modulates sperm rotation. Higher beat frequency components exist in other flagellated cells; therefore, this steering mechanism might be widespread and could inspire the design of synthetic microswimmers.

  4. Regulation of flagellar biogenesis by a calcium dependent protein kinase in Chlamydomonas reinhardtii.

    Science.gov (United States)

    Liang, Yinwen; Pan, Junmin

    2013-01-01

    Chlamydomonas reinhardtii, a bi-flagellated green alga, is a model organism for studies of flagella or cilia related activities including cilia-based signaling, flagellar motility and flagellar biogenesis. Calcium has been shown to be a key regulator of these cellular processes whereas the signaling pathways linking calcium to these cellular functions are less understood. Calcium-dependent protein kinases (CDPKs), which are present in plants but not in animals, are also present in ciliated microorganisms which led us to examine their possible functions and mechanisms in flagellar related activities. By in silico analysis of Chlamydomonas genome we have identified 14 CDPKs and studied one of the flagellar localized CDPKs--CrCDPK3. CrCDPK3 was a protein of 485 amino acids and predicted to have a protein kinase domain at the N-terminus and four EF-hand motifs at the C-terminus. In flagella, CrCDPK3 was exclusively localized in the membrane matrix fraction and formed an unknown 20 S protein complex. Knockdown of CrCDPK3 expression by using artificial microRNA did not affect flagellar motility as well as flagellar adhesion and mating. Though flagellar shortening induced by treatment with sucrose or sodium pyrophosphate was not affected in RNAi strains, CrCDPK3 increased in the flagella, and pre-formed protein complex was disrupted. During flagellar regeneration, CrCDPK3 also increased in the flagella. When extracellular calcium was lowered to certain range by the addition of EGTA after deflagellation, flagellar regeneration was severely affected in RNAi cells compared with wild type cells. In addition, during flagellar elongation induced by LiCl, RNAi cells exhibited early onset of bulbed flagella. This work expands new functions of CDPKs in flagellar activities by showing involvement of CrCDPK3 in flagellar biogenesis in Chlamydomonas.

  5. Bundling harvester; Nippukorjausharvesteri

    Energy Technology Data Exchange (ETDEWEB)

    Koponen, K. [Eko-Log Oy, Kuopio (Finland)

    1996-12-31

    The staring point of the project was to design and construct, by taking the silvicultural point of view into account, a harvesting and processing system especially for energy-wood, containing manually driven bundling harvester, automatizing of the harvester, and automatized loading. The equipment forms an ideal method for entrepreneur`s-line harvesting. The target is to apply the system also for owner`s-line harvesting. The profitability of the system promotes the utilization of the system in both cases. The objectives of the project were: to construct a test equipment and prototypes for all the project stages, to carry out terrain and strain tests in order to examine the usability and durability, as well as the capacity of the machine, to test the applicability of the Eko-Log system in simultaneous harvesting of energy and pulp woods, and to start the marketing and manufacturing of the products. The basic problems of the construction of the bundling harvester have been solved using terrain-tests. The prototype machine has been shown to be operable. Loading of the bundles to form sufficiently economically transportable loads has been studied, and simultaneously, the branch-biomass has been tried to be utilized without loosing the profitability of transportation. The results have been promising, and will promote the profitable utilization of wood-energy

  6. Bundled payments in orthopedic surgery.

    Science.gov (United States)

    Bushnell, Brandon D

    2015-02-01

    As a result of reading this article, physicians should be able to: 1. Describe the concept of bundled payments and the potential applications of bundled payments in orthopedic surgery. 2. For specific situations, outline a clinical episode of care, determine the participants in a bundling situation, and define care protocols and pathways. 3. Recognize the importance of resource utilization management, quality outcome measurement, and combined economic-clinical value in determining the value of bundled payment arrangements. 4. Identify the implications of bundled payments for practicing orthopedists, as well as the legal issues and potential future directions of this increasingly popular alternative payment method. Bundled payments, the idea of paying a single price for a bundle of goods and services, is a financial concept familiar to most American consumers because examples appear in many industries. The idea of bundled payments has recently gained significant momentum as a financial model with the potential to decrease the significant current costs of health care. Orthopedic surgery as a field of medicine is uniquely positioned for success in an environment of bundled payments. This article reviews the history, logistics, and implications of the bundled payment model relative to orthopedic surgery. Copyright 2015, SLACK Incorporated.

  7. The Atiyah bundle and connections on a principal bundle

    Indian Academy of Sciences (India)

    be the fiber bundle constructed as in (1.1) for the universal principal G-bundle. In a work in progress, we hope to show that the universal G-connection can be realized as a fiber bundle over C(EG). Turning this around, we hope to get an alternative construction of the universal G-connection. Also, this approach may yield a ...

  8. [Masquerading bundle branch block].

    Science.gov (United States)

    Kukla, Piotr; Baranchuk, Adrian; Jastrzębski, Marek; Bryniarski, Leszek

    2014-01-01

    We here describe a surface 12-lead electrocardiogram (ECG) of a 72-year-old female with a prior history of breast cancer and chemotherapy-induced cardiomyopathy. An echocardiogram revealed left ventricular dysfunction, ejection fraction of 23%, with mild enlarged left ventricle. The 12-lead ECG showed atrial fibrillation with a mean heart rate of about 100 bpm, QRS duration 160 ms, QT interval 400 ms, right bundle branch block (RBBB) and left anterior fascicular block (LAFB). The combination of RBBB features in the precordial leads and LAFB features in the limb leads is known as ''masquerading bundle branch block''. In most cases of RBBB and LAFB, the QRS axis deviation is located between - 80 to -120 degrees. Rarely, when predominant left ventricular forces are present, the QRS axis deviation is near about -90 degrees, turning the pattern into an atypical form. In a situation of RBBB associated with LAFB, the S wave can be absent or very small in lead I. Such a situation is the result of not only purely LAFB but also with left ventricular hypertrophy and/or focal block due to scar (extensive anterior myocardial infarction) or fibrosis (cardiomyopathy). Sometimes, this specific ECG pattern is mistaken for LBBB. RBBB with LAFB may imitate LBBB either in the limb leads (known as 'standard masquerading' - absence of S wave in lead I), or in the precordial leads (called 'precordial masquerading' - absence of S wave in leads V₅ and V₆). Our ECG showed both these types of masquerading bundle branch block - absence of S wave in lead I and in leads V₅ and V₆.

  9. Kernel bundle EPDiff

    DEFF Research Database (Denmark)

    Sommer, Stefan Horst; Lauze, Francois Bernard; Nielsen, Mads

    2011-01-01

    In the LDDMM framework, optimal warps for image registration are found as end-points of critical paths for an energy functional, and the EPDiff equations describe the evolution along such paths. The Large Deformation Diffeomorphic Kernel Bundle Mapping (LDDKBM) extension of LDDMM allows scale space...... information to be automatically incorporated in registrations and promises to improve the standard framework in several aspects. We present the mathematical foundations of LDDKBM and derive the KB-EPDiff evolution equations, which provide optimal warps in this new framework. To illustrate the resulting...

  10. Managing bundled payments.

    Science.gov (United States)

    Draper, Andrew

    2011-04-01

    Results of Medicare's ACE demonstration project and Geisinger Health System's ProvenCare initiative provide insight into the challenges hospitals will face as bundled payment proliferates. An early analysis of these results suggests that hospitals would benefit from bringing full automation using clinical IT tools to bear in their efforts to meet these challenges. Other important factors contributing to success include board and physician leadership, organizational structure, pricing methodology for bidding, evidence-based medical practice guidelines, supply cost management, process efficiency management, proactive and aggressive case management, business development and marketing strategy, and the financial management system.

  11. Handtool assists in bundling cables

    Science.gov (United States)

    Stringer, E. J.

    1980-01-01

    Simple tool makes it possible to bundle electrical cables in channel or "tray" without requiring cables be lifted out. Procedure for bundling is faster and less awkward than lifting method. Used with commercially-available plastic ribbons that tie cables together, tool guides ribbon along tray wall, through bracket at bottom of tray, and up opposite wall. One end of ribbon locks in other end, securing cable bundle.

  12. Infinitesimal bundles and projective relativity

    International Nuclear Information System (INIS)

    Evans, G.T.

    1973-01-01

    An intrinsic and global presentation of five-dimensional relativity theory is developed, in which special coordinate conditions are replaced by conditions of Lie invariance. The notion of an infinitesimal bundle is introduced, and the theory of connexions on principal bundles is extended to infinitesimal bundles. Global aspects of projective relativity are studied: it is shown that projective relativity can describe almost any space-time. In particular, it is not necessary to assume that the electromagnetic field have a global potential. (author)

  13. Muon bundles from the Universe

    Directory of Open Access Journals (Sweden)

    Kankiewicz P.

    2018-01-01

    Full Text Available Recently the CERN ALICE experiment, in its dedicated cosmic ray run, observed muon bundles of very high multiplicities, thereby confirming similar findings from the LEP era at CERN (in the CosmoLEP project. Significant evidence for anisotropy of arrival directions of the observed high multiplicity muonic bundles is found. Estimated directionality suggests their possible extragalactic provenance. We argue that muonic bundles of highest multiplicity are produced by strangelets, hypothetical stable lumps of strange quark matter infiltrating our Universe.

  14. Muon bundles from the Universe

    Science.gov (United States)

    Kankiewicz, P.; Rybczyński, M.; Włodarczyk, Z.; Wilk, G.

    2018-02-01

    Recently the CERN ALICE experiment, in its dedicated cosmic ray run, observed muon bundles of very high multiplicities, thereby confirming similar findings from the LEP era at CERN (in the CosmoLEP project). Significant evidence for anisotropy of arrival directions of the observed high multiplicity muonic bundles is found. Estimated directionality suggests their possible extragalactic provenance. We argue that muonic bundles of highest multiplicity are produced by strangelets, hypothetical stable lumps of strange quark matter infiltrating our Universe.

  15. MAVEN SWIA Calibrated Data Bundle

    Data.gov (United States)

    National Aeronautics and Space Administration — This bundle contains fully calibrated MAVEN SWIA data, including ion velocity distributions, energy spectra, and density, temperature, and velocity moments from...

  16. The Atiyah bundle and connections on a principal bundle

    Indian Academy of Sciences (India)

    correspond to the connections on EG. The pull back of EG to C(EG) has a tautological connection. We investigate the curvature of this tautological connection. Keywords. Principal bundle; connection; Atiyah bundle. 1. Introduction. Fix a Lie group G. Its Lie algebra will be denoted by g. Let M be a connected C. ∞ manifold.

  17. CANFLEX fuel bundle impact test

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Seok Kyu; Chung, C. H.; Park, J. S.; Hong, S. D.; Kim, B. D.

    1997-08-01

    This document outlines the test results for the impact test of the CANFLEX fuel bundle. Impact test is performed to determine and verify the amount of general bundle shape distortion and defect of the pressure tube that may occur during refuelling. The test specification requires that the fuel bundles and the pressure tube retain their integrities after the impact test under the conservative conditions (10 stationary bundles with 31kg/s flow rate) considering the pressure tube creep. The refuelling simulator operating with pneumatic force and simulated shield plug were fabricated and the velocity/displacement transducer and the high speed camera were also used in this test. The characteristics of the moving bundle (velocity, displacement, impacting force) were measured and analyzed with the impact sensor and the high speed camera system. The important test procedures and measurement results were discussed as follows. 1) Test bundle measurements and the pressure tube inspections 2) Simulated shield plug, outlet flange installation and bundle loading 3) refuelling simulator, inlet flange installation and sensors, high speed camera installation 4) Perform the impact test with operating the refuelling simulator and measure the dynamic characteristics 5) Inspections of the fuel bundles and the pressure tube. (author). 8 refs., 23 tabs., 13 figs.

  18. Bundle Security Protocol for ION

    Science.gov (United States)

    Burleigh, Scott C.; Birrane, Edward J.; Krupiarz, Christopher

    2011-01-01

    This software implements bundle authentication, conforming to the Delay-Tolerant Networking (DTN) Internet Draft on Bundle Security Protocol (BSP), for the Interplanetary Overlay Network (ION) implementation of DTN. This is the only implementation of BSP that is integrated with ION.

  19. Sasakian and Parabolic Higgs Bundles

    Science.gov (United States)

    Biswas, Indranil; Mj, Mahan

    2018-03-01

    Let M be a quasi-regular compact connected Sasakian manifold, and let N = M/ S 1 be the base projective variety. We establish an equivalence between the class of Sasakian G-Higgs bundles over M and the class of parabolic (or equivalently, ramified) G-Higgs bundles over the base N.

  20. A Bacillus flagellar motor that can use both Na+ and K+ as a coupling ion is converted by a single mutation to use only Na+.

    Directory of Open Access Journals (Sweden)

    Naoya Terahara

    Full Text Available In bacteria, the sodium ion (Na(+ cycle plays a critical role in negotiating the challenges of an extremely alkaline and sodium-rich environment. Alkaliphilic bacteria that grow optimally at high pH values use Na(+ for solute uptake and flagellar rotation because the proton (H(+ motive force is insufficient for use at extremely alkaline pH. Only three types of electrically driven rotary motors exist in nature: the F-type ATPase, the V-type ATPase, and the bacterial flagellar motor. Until now, only H(+ and Na(+ have been reported as coupling ions for these motors. Here, we report that the alkaliphilic bacterium Bacillus alcalophilus Vedder 1934 can grow not only under a Na(+-rich and potassium ion (K(+-poor condition but also under the opposite condition in an extremely alkaline environment. In this organism, swimming performance depends on concentrations of Na(+, K(+ or Rb(+. In the absence of Na(+, swimming behavior is clearly K(+- dependent. This pattern was confirmed in swimming assays of stator-less Bacillus subtilis and Escherichia coli mutants expressing MotPS from B. alcalophilus (BA-MotPS. Furthermore, a single mutation in BA-MotS was identified that converted the naturally bi-functional BA-MotPS to stators that cannot use K(+ or Rb(+. This is the first report that describes a flagellar motor that can use K(+ and Rb(+ as coupling ions. The finding will affect the understanding of the operating principles of flagellar motors and the molecular mechanisms of ion selectivity, the field of the evolution of environmental changes and stresses, and areas of nanotechnology.

  1. A Bacillus flagellar motor that can use both Na+ and K+ as a coupling ion is converted by a single mutation to use only Na+.

    Science.gov (United States)

    Terahara, Naoya; Sano, Motohiko; Ito, Masahiro

    2012-01-01

    In bacteria, the sodium ion (Na(+)) cycle plays a critical role in negotiating the challenges of an extremely alkaline and sodium-rich environment. Alkaliphilic bacteria that grow optimally at high pH values use Na(+) for solute uptake and flagellar rotation because the proton (H(+)) motive force is insufficient for use at extremely alkaline pH. Only three types of electrically driven rotary motors exist in nature: the F-type ATPase, the V-type ATPase, and the bacterial flagellar motor. Until now, only H(+) and Na(+) have been reported as coupling ions for these motors. Here, we report that the alkaliphilic bacterium Bacillus alcalophilus Vedder 1934 can grow not only under a Na(+)-rich and potassium ion (K(+))-poor condition but also under the opposite condition in an extremely alkaline environment. In this organism, swimming performance depends on concentrations of Na(+), K(+) or Rb(+). In the absence of Na(+), swimming behavior is clearly K(+)- dependent. This pattern was confirmed in swimming assays of stator-less Bacillus subtilis and Escherichia coli mutants expressing MotPS from B. alcalophilus (BA-MotPS). Furthermore, a single mutation in BA-MotS was identified that converted the naturally bi-functional BA-MotPS to stators that cannot use K(+) or Rb(+). This is the first report that describes a flagellar motor that can use K(+) and Rb(+) as coupling ions. The finding will affect the understanding of the operating principles of flagellar motors and the molecular mechanisms of ion selectivity, the field of the evolution of environmental changes and stresses, and areas of nanotechnology.

  2. Twisted vector bundles on pointed nodal curves

    Indian Academy of Sciences (India)

    Abstract. Motivated by the quest for a good compactification of the moduli space of -bundles on a nodal curve we establish a striking relationship between Abramovich's and Vistoli's twisted bundles and Gieseker vector bundles.

  3. Twisted Vector Bundles on Pointed Nodal Curves

    Indian Academy of Sciences (India)

    Abstract. Motivated by the quest for a good compactification of the moduli space of -bundles on a nodal curve we establish a striking relationship between Abramovich's and Vistoli's twisted bundles and Gieseker vector bundles.

  4. Flagellar-phase variation: isolation of the rh1 gene

    International Nuclear Information System (INIS)

    Silverman, M.; Zieg, J.; Simon, M.

    1979-01-01

    In Salmonella, expression of flagellar antigen alternates between two serotypes (phases) encoded by two genes, H1 and H2. The mechanism which controls the alternative expression of the H1 and H2 genes was examined by cloning these genes and the genetic elements which control their activity on hybrid vehicles in Escherichia coli. H2 gene activity was shown to be controlled by a recombinational switch located adjacent to the H2 gene. Activity of the H1 gene is thought to be repressed, when the H2 gene is expressed, by the product of another gene, rhl (repressor of H1), which is controlled coordinately with the H2 gene. In this report, we describe the construction of hybrid lambda vehicles which contain, in addition to the H2 gene, a genetic activity corresponding to rhl. Variation of flagellar antigens analogous to that observed in Salmonella was observed when E. coli strains were transduced with the hybrid lambda. By using the lambda H2rhl hybrid to program protein syntheis in uv-irradiated cells, the synthesis of a polypeptide was correlated with rhl gene product activity. We conclude that the H2 region consists of two cotranscribed genes, H2 and rhl. The expression of both gene products is regulated by the same recombinational event

  5. Aquatic bacteria elongate and wobble their bodies for flagellar performance

    Science.gov (United States)

    Liu, Bin; Valenzuela, Joanna; Chopra, Pooja

    2017-11-01

    Bacteria are endowed with well-regulated sizes and shapes. A bacillus has a rod-like cell body, achieving swimming motility by rotating a single flagellum or multiple flagella. Along with other shapes, this elongated cell is often viewed as a payload, and its movements are regarded as passive responses to its flagellar propulsion. Here, we simultaneously measured the morphology and movement of individual free-swimming bacteria using an automated tracking microscope and 3D reconstruction techniques. These cells were found to consistently precess, based on reconstructions of the apparent wobbling movements viewed from a microscope. Through a hydrodynamic model that incorporates such precessing cell bodies and rod-like geometries, we found that there is a critical cell size below which wobbling movement is beneficial for flagellar performance. This critical cell size is consistent with the cellular morphologies of Caulobacter crescentus and Escherichia coli, as examples of single- and multi-flagellated species that are known for wobbling movements in aquatic environments. We also showed that the moderate cell sizes of these species could be attributed to a compromise between dispersal speed and power consumption. The authors thank the support of NSF-CREST: Center for Cellular and Biomolecular Machines at UC Merced (NSF-HRD-1547848).

  6. Characterization and distinction of two flagellar systems in extraintestinal pathogenic Escherichia coli PCN033.

    Science.gov (United States)

    Liu, Feng; Fu, Jiyang; Liu, Canying; Chen, Jing; Sun, Minhua; Chen, Huanchun; Tan, Chen; Wang, Xiangru

    2017-03-01

    Extraintestinal pathogenic Escherichia coli (ExPEC) can invade and colonize multiple extraintestinal tissues and can cause a wide range of infections; however the mechanisms of its pathogenicity are not well understood. Flagella contribute to the infection of E. coli strains by mediating adhesion and invasion. Our previous bioinformatic analysis revealed two flagella gene clusters in the genome of an ExPEC isolate, PCN033. One encodes the conventional flagellum system (Flag-1) and the other encodes the Flag-2 system, whose function is uncharacterized. Here we aimed to characterize these two flagellum systems and determine their contributions to the flagellum formation and certain pathogenicity-associated phenotypes. Our observations support the involvement of Flag-1 system, but not Flag-2 system, in the synthesis and maturation of the flagellum structure, and in mediating bacterial swimming and swarming. Moreover, flgD, which encodes a flagellar-hook scaffolding protein in the Flag-1 system, is required for flagellum assembly by influencing the production of FliC (flagellin). Deletion of flgD attenuated ExPEC strain PCN033 invasion and colonization in vivo, probably by affecting bacterial adhesion and invasion, and by reducing resistance to phagocytosis by circulating monocytes. In contrast, these phenotypes were not observed in the strain with deletion of lfgD, encoding the FlgD-like protein in the Flag-2 system. Taken together, these findings indicate that Flag-1 flagellum system is the determinative component of bacterial flagella that contributes to the infection. Copyright © 2016 Elsevier GmbH. All rights reserved.

  7. Modified 37-element bundle dryout

    Energy Technology Data Exchange (ETDEWEB)

    Tahir, A., E-mail: ab.tahir@amec.com [AMEC NSS Ltd., Fuel and Fuel Channel Safety Analysis, Ontario (Canada); Parlatan, Y., E-mail: yuksel.parlatan@opg.com [Ontario Power Generation Inc., Nuclear Safety Projects, Ontario (Canada); Kwee, M., E-mail: marc.kwee@brucepower.com [Bruce Power., Nuclear Safety Analysis and Support, Ontario (Canada); Liauw, W., E-mail: wie.kiong.liauw@opg.com [Ontario Power Generation Inc., Nuclear Safety Projects, Ontario (Canada); Hadaller, G.; Fortman, R., E-mail: ghadaller@sternlab.com, E-mail: rfortman@sternlab.com [Stern Labs Inc., Hamilton, Ontario (Canada)

    2011-07-01

    The Heat Transport Systems (HTS) of the Canadian nuclear reactors are ageing. One of the effects of ageing is the non-uniform change in the dimension of the reactor pressure tubes through the mechanism of diametral creep. The mechanism has the global effect of increasing channel flows and decreasing the reactor header-to-header pressure drop. However, the increased flow is not distributed uniformly through the fuel bundle cross-section because the bundle tends to settle at the bottom of the pressure tube leaving a crescent shaped space on the top. This portion experiences the bulk of the increased flow, as it offers the path of least hydraulic resistance. As a result of this flow bypass, the coolant flows through some of the interior-subchannels of the fuel bundle are reduced. For a given flow, inlet temperature and exit pressure, flow bypass in the top of the channel reduces flow from the interior subchannels and consequently reduces the Critical Heat Flux (CHF). To recover some of the reduction in dryout power, OPG started a program in 2004 to examine possible modifications to the reference 37-element bundles that may result in an increase in dryout powers for the uncrept and crept pressure tube. Under accident conditions, where CHF is a concern, the ideal design is one where all fuel elements reach dryout at the same time. The ASSERT subchannel code was used to explore potential modifications to the 37-element bundle that may result in increased dryout powers in an uncrept and crept pressure tube. In addition analysis of post-dryout tests in 37-element bundle were examined to explore the potential of increasing the dryout power of the reference 37-element bundle by slightly modifying the bundle geometry. A small reduction of the centre element in the bundle was selected as an approach to enhance the dryout power of the bundle. CHF tests of the modified bundle were performed. The measurement confirmed that the modified bundle has higher dryout powers than the

  8. Evaluating big deal journal bundles.

    Science.gov (United States)

    Bergstrom, Theodore C; Courant, Paul N; McAfee, R Preston; Williams, Michael A

    2014-07-01

    Large commercial publishers sell bundled online subscriptions to their entire list of academic journals at prices significantly lower than the sum of their á la carte prices. Bundle prices differ drastically between institutions, but they are not publicly posted. The data that we have collected enable us to compare the bundle prices charged by commercial publishers with those of nonprofit societies and to examine the types of price discrimination practiced by commercial and nonprofit journal publishers. This information is of interest to economists who study monopolist pricing, librarians interested in making efficient use of library budgets, and scholars who are interested in the availability of the work that they publish.

  9. A molecular brake, not a clutch, stops the Rhodobacter sphaeroides flagellar motor

    Science.gov (United States)

    Pilizota, Teuta; Brown, Mostyn T.; Leake, Mark C.; Branch, Richard W.; Berry, Richard M.; Armitage, Judith P.

    2009-01-01

    Many bacterial species swim by employing ion-driven molecular motors that power the rotation of helical filaments. Signals are transmitted to the motor from the external environment via the chemotaxis pathway. In bidirectional motors, the binding of phosphorylated CheY (CheY-P) to the motor is presumed to instigate conformational changes that result in a different rotor-stator interface, resulting in rotation in the alternative direction. Controlling when this switch occurs enables bacteria to accumulate in areas favorable for their survival. Unlike most species that swim with bidirectional motors, Rhodobacter sphaeroides employs a single stop-start flagellar motor. Here, we asked, how does the binding of CheY-P stop the motor in R. sphaeroides—using a clutch or a brake? By applying external force with viscous flow or optical tweezers, we show that the R. sphaeroides motor is stopped using a brake. The motor stops at 27–28 discrete angles, locked in place by a relatively high torque, approximately 2–3 times its stall torque. PMID:19571004

  10. A novel glycan modifies the flagellar filament proteins of the oral bacterium Treponema denticola.

    Science.gov (United States)

    Kurniyati, Kurni; Kelly, John F; Vinogradov, Evgeny; Robotham, Anna; Tu, Youbing; Wang, Juyu; Liu, Jun; Logan, Susan M; Li, Chunhao

    2017-01-01

    While protein glycosylation has been reported in several spirochetes including the syphilis bacterium Treponema pallidum and Lyme disease pathogen Borrelia burgdorferi, the pertinent glycan structures and their roles remain uncharacterized. Herein, a novel glycan with an unusual chemical composition and structure in the oral spirochete Treponema denticola, a keystone pathogen of periodontitis was reported. The identified glycan of mass 450.2 Da is composed of a monoacetylated nonulosonic acid (Non) with a novel extended N7 acyl modification, a 2-methoxy-4,5,6-trihydroxy-hexanoyl residue in which the Non has a pseudaminic acid configuration (L-glycero-L-manno) and is β-linked to serine or threonine residues. This novel glycan modifies the flagellin proteins (FlaBs) of T. denticola by O-linkage at multiple sites near the D1 domain, a highly conserved region of bacterial flagellins that interact with Toll-like receptor 5. Furthermore, mutagenesis studies demonstrate that the glycosylation plays an essential role in the flagellar assembly and motility of T. denticola. To our knowledge, this novel glycan and its unique modification sites have not been reported previously in any bacteria. © 2016 John Wiley & Sons Ltd.

  11. MAVEN SWEA Calibrated Data Bundle

    Data.gov (United States)

    National Aeronautics and Space Administration — This bundle contains fully calibrated electron energy/angle (3D) distributions, pitch angle distributions, and omni-directional energy spectra. Tables of sensitivity...

  12. Left bundle-branch block

    DEFF Research Database (Denmark)

    Risum, Niels; Strauss, David; Sogaard, Peter

    2013-01-01

    The relationship between myocardial electrical activation by electrocardiogram (ECG) and mechanical contraction by echocardiography in left bundle-branch block (LBBB) has never been clearly demonstrated. New strict criteria for LBBB based on a fundamental understanding of physiology have recently...

  13. Bundling ecosystem services in Denmark

    DEFF Research Database (Denmark)

    Turner, Katrine Grace; Odgaard, Mette Vestergaard; Bøcher, Peder Klith

    2014-01-01

    We made a spatial analysis of 11 ecosystem services at a 10 km × 10 km grid scale covering most of Denmark. Our objective was to describe their spatial distribution and interactions and also to analyze whether they formed specific bundle types on a regional scale in the Danish cultural landscape....... We found clustered distribution patterns of ecosystem services across the country. There was a significant tendency for trade-offs between on the one hand cultural and regulating services and on the other provisioning services, and we also found the potential of regulating and cultural services...... to form synergies. We identified six distinct ecosystem service bundle types, indicating multiple interactions at a landscape level. The bundle types showed specialized areas of agricultural production, high provision of cultural services at the coasts, multifunctional mixed-use bundle types around urban...

  14. Line bundles and flat connections

    Indian Academy of Sciences (India)

    0344-5. Line bundles and flat connections. INDRANIL BISWAS1,∗ and GEORG SCHUMACHER2. 1School of Mathematics, Tata Institute of Fundamental Research, Homi Bhabha Road,. Mumbai 400 005, India. 2Fachbereich Mathematik und ...

  15. MAVEN LPW Calibrated Data Bundle

    Data.gov (United States)

    National Aeronautics and Space Administration — This bundle contains fully calibrated, science quality data produced by the LPW instrument. The data include spacecraft potential, electric field waveforms and wave...

  16. MAVEN EUV Modelled Data Bundle

    Data.gov (United States)

    National Aeronautics and Space Administration — This bundle contains solar irradiance spectra in 1-nm bins from 0-190 nm. The spectra are generated based upon the Flare Irradiance Spectra Model - Mars (FISM-M)...

  17. MAVEN SEP Calibrated Data Bundle

    Data.gov (United States)

    National Aeronautics and Space Administration — The maven.sep.calibrated Level 2 Science Data Bundle contains fully calibrated SEP data, as well as the raw count data from which they are derived, and ancillary...

  18. Atrio-His bundle tracts.

    Science.gov (United States)

    Brechenmacher, C

    1975-01-01

    The atrio-His bundle tracts are very rare; only two have been found in 687 hearts studied histologically. These tracts have a similar appearance to those of the atrioventricular bundle and form a complete bypass of the atrioventricular node. In their presence the electrocardiogram may show a short or normal PR interval. They may be responsible for some cases of very rapid ventricular response to supraventricular arrhythmias. Images PMID:1191446

  19. Life with eight flagella: flagellar assembly and division in Giardia.

    Science.gov (United States)

    Dawson, Scott C; House, Susan A

    2010-08-01

    Flagellar movement in Giardia, a common intestinal parasitic protist, is crucial to its survival in the host. Each axoneme is unique in possessing a long, cytoplasmic portion as well as a membrane-bound portion. Intraflagellar transport (IFT) is required for the assembly of membrane-bound regions, yet the cytoplasmic regions may be assembled by IFT-independent mechanisms. Steady-state axoneme length is maintained by IFT and by intrinsic and active microtubule dynamics. Following mitosis and before their segregation, giardial flagella undergo a multigenerational division cycle in which the parental eight flagella migrate and reposition to different cellular locations; eight new flagella are assembled de novo. Each daughter cell thus inherits four mature and four newly synthesized flagella. Copyright 2010 Elsevier Ltd. All rights reserved.

  20. Holomorphic bundles over elliptic manifolds

    International Nuclear Information System (INIS)

    Morgan, J.W.

    2000-01-01

    In this lecture we shall examine holomorphic bundles over compact elliptically fibered manifolds. We shall examine constructions of such bundles as well as (duality) relations between such bundles and other geometric objects, namely K3-surfaces and del Pezzo surfaces. We shall be dealing throughout with holomorphic principal bundles with structure group GC where G is a compact, simple (usually simply connected) Lie group and GC is the associated complex simple algebraic group. Of course, in the special case G = SU(n) and hence GC = SLn(C), we are considering holomorphic vector bundles with trivial determinant. In the other cases of classical groups, G SO(n) or G = Sympl(2n) we are considering holomorphic vector bundles with trivial determinant equipped with a non-degenerate symmetric, or skew symmetric pairing. In addition to these classical cases there are the finite number of exceptional groups. Amazingly enough, motivated by questions in physics, much interest centres around the group E8 and its subgroups. For these applications it does not suffice to consider only the classical groups. Thus, while often first doing the case of SU(n) or more generally of the classical groups, we shall extend our discussions to the general semi-simple group. Also, we shall spend a good deal of time considering elliptically fibered manifolds of the simplest type, namely, elliptic curves

  1. Rab23 is a flagellar protein in Trypanosoma brucei

    Directory of Open Access Journals (Sweden)

    Field Mark C

    2011-06-01

    Full Text Available Abstract Background Rab small GTPases are important mediators of membrane transport, and orthologues frequently retain similar locations and functions, even between highly divergent taxa. In metazoan organisms Rab23 is an important negative regulator of Sonic hedgehog signaling and is crucial for correct development and differentiation of cellular lineages by virtue of an involvement in ciliary recycling. Previously, we reported that Trypanosoma brucei Rab23 localized to the nuclear envelope 1, which is clearly inconsistent with the mammalian location and function. As T. brucei is unicellular the potential that Rab23 has no role in cell signaling was possible. Here we sought to further investigate the role(s of Rab23 in T. brucei to determine if Rab23 was an example of a Rab protein with divergent function in distinct taxa. Methods/major findings The taxonomic distribution of Rab23 was examined and compared with the presence of flagella/cilia in representative taxa. Despite evidence for considerable secondary loss, we found a clear correlation between a conventional flagellar structure and the presence of a Rab23 orthologue in the genome. By epitope-tagging, Rab23 was localized and found to be present at the flagellum throughout the cell cycle. However, RNAi knockdown did not result in a flagellar defect, suggesting that Rab23 is not required for construction or maintenance of the flagellum. Conclusions The location of Rab23 at the flagellum is conserved between mammals and trypanosomes and the Rab23 gene is restricted to flagellated organisms. These data may suggest the presence of a Rab23-mediated signaling mechanism in trypanosomes.

  2. Principal bundles the classical case

    CERN Document Server

    Sontz, Stephen Bruce

    2015-01-01

    This introductory graduate level text provides a relatively quick path to a special topic in classical differential geometry: principal bundles.  While the topic of principal bundles in differential geometry has become classic, even standard, material in the modern graduate mathematics curriculum, the unique approach taken in this text presents the material in a way that is intuitive for both students of mathematics and of physics. The goal of this book is to present important, modern geometric ideas in a form readily accessible to students and researchers in both the physics and mathematics communities, providing each with an understanding and appreciation of the language and ideas of the other.

  3. Second messenger-mediated tactile response by a bacterial rotary motor.

    Science.gov (United States)

    Hug, Isabelle; Deshpande, Siddharth; Sprecher, Kathrin S; Pfohl, Thomas; Jenal, Urs

    2017-10-27

    When bacteria encounter surfaces, they respond with surface colonization and virulence induction. The mechanisms of bacterial mechanosensation and downstream signaling remain poorly understood. Here, we describe a tactile sensing cascade in Caulobacter crescentus in which the flagellar motor acts as sensor. Surface-induced motor interference stimulated the production of the second messenger cyclic diguanylate by the motor-associated diguanylate cyclase DgcB. This led to the allosteric activation of the glycosyltransferase HfsJ to promote rapid synthesis of a polysaccharide adhesin and surface anchoring. Although the membrane-embedded motor unit was essential for surface sensing, mutants that lack external flagellar structures were hypersensitive to mechanical stimuli. Thus, the bacterial flagellar motor acts as a tetherless sensor reminiscent of mechanosensitive channels. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  4. Exploring Bundling Theory with Geometry

    Science.gov (United States)

    Eckalbar, John C.

    2006-01-01

    The author shows how instructors might successfully introduce students in principles and intermediate microeconomic theory classes to the topic of bundling (i.e., the selling of two or more goods as a package, rather than separately). It is surprising how much students can learn using only the tools of high school geometry. To be specific, one can…

  5. Line bundles and flat connections

    Indian Academy of Sciences (India)

    The degree of a torsionfree coherent analytic sheaf F on X is defined as degree(F ) = ∫. X ch. 1(det F) ∧ ωδ−1 .... [9] Kobayashi S, Differential geometry of complex vector bundles, Publications of the Math. Society of Japan 15 (1987) (Iwanami Shoten Publishers and Princeton University Press). [10] Lackenby M, Some ...

  6. Line bundles and flat connections

    Indian Academy of Sciences (India)

    We prove that there are cocompact lattices Γ in S L ( 2 , C ) with the property that there are holomorphic line bundles L on S L ( 2 , C ) / Γ with c 1 ( L ) = 0 such that L does not admit any unitary flat connection. Author Affiliations. INDRANIL BISWAS1 GEORG SCHUMACHER2. School of Mathematics, Tata Institute of ...

  7. Tuning bacterial hydrodynamics with magnetic fields

    Science.gov (United States)

    Pierce, C. J.; Mumper, E.; Brown, E. E.; Brangham, J. T.; Lower, B. H.; Lower, S. K.; Yang, F. Y.; Sooryakumar, R.

    2017-06-01

    Magnetotactic bacteria are a group of motile prokaryotes that synthesize chains of lipid-bound, magnetic nanoparticles called magnetosomes. This study exploits their innate magnetism to investigate previously unexplored facets of bacterial hydrodynamics at surfaces. Through use of weak, uniform, external magnetic fields and local, micromagnetic surface patterns, the relative strength of hydrodynamic, magnetic, and flagellar force components is tuned through magnetic control of the bacteria's orientation. The resulting swimming behaviors provide a means to experimentally determine hydrodynamic parameters and offer a high degree of control over large numbers of living microscopic entities. The implications of this controlled motion for studies of bacterial motility near surfaces and for micro- and nanotechnology are discussed.

  8. Strategic and welfare implications of bundling

    DEFF Research Database (Denmark)

    Martin, Stephen

    1999-01-01

    A standard oligopoly model of bundling shows that bundling by a firm with a monopoly over one product has a strategic effect because it changes the substitution relationships between the goods among which consumers choose. Bundling in appropriate proportions is privately profitable, reduces rivals...

  9. Principal G-bundles on nodal curves

    Indian Academy of Sciences (India)

    Springer Verlag Heidelberg #4 2048 1996 Dec 15 10:16:45

    If Y is reducible these notions depend on parameters a = (a1,...,aI ). The study of G-bundles on Y is done by extending the notion of (generalized) parabolic vector bundles [U1] to generalized parabolic principal G-bundles (called GPGs in short) on the curve C and using the correspondence between them and principal ...

  10. Chlamydomonas IFT25 is dispensable for flagellar assembly but required to export the BBSome from flagella

    Directory of Open Access Journals (Sweden)

    Bin Dong

    2017-11-01

    Full Text Available Intraflagellar transport (IFT particles are composed of polyprotein complexes IFT-A and IFT-B as well as cargo adaptors such as the BBSome. Two IFT-B subunits, IFT25 and IFT27 were found to form a heterodimer, which is essential in exporting the BBSome out of the cilium but not involved in flagellar assembly and cytokinesis in vertebrates. Controversial results were, however, recorded to show that defects in IFT, flagellar assembly and even cytokinesis were caused by IFT27 knockdown in Chlamydomonas reinhardtii. Using C. reinhardtii as a model organism, we report that depletion of IFT25 has no effect on flagellar assembly and does not affect the entry of the BBSome into the flagellum, but IFT25 depletion did impair BBSome movement out of the flagellum, clarifying the evolutionally conserved role of IFT25 in regulating the exit of the BBSome from the flagellum cross species. Interestingly, depletion of IFT25 causes dramatic reduction of IFT27 as expected, which does not cause defects in flagellar assembly and cytokinesis in C. reinhardtii. Our data thus support that Chlamydomonas IFT27, like its vertebrate homologues, is not involved in flagellar assembly and cytokinesis.

  11. Involvement of the flagellar assembly pathway in Vibrio alginolyticus adhesion under environmental stresses

    Directory of Open Access Journals (Sweden)

    Lu eWang

    2015-08-01

    Full Text Available Adhesion is an important virulence factor of Vibrio alginolyticus. This factor may be affected by environment conditions; however, its molecular mechanism remains unclear. In our previous research, adhesion tender models were obtained by culturing V. alginolyticus under stresses such as Cu2+, Pb2+, Hg2+, and low pH. With high-throughput sequencing and bioinformatics analysis, we found that all of these stress treatments significantly affected the flagellar assembly pathway, which may play an important role in V. alginolyticus adhesion. Therefore, we hypothesized that the environmental stresses of the flagellar assembly pathway may be one way in which environment conditions affect adhesion. To verify our hypothesis, a bioinformatics analysis, QPCR, RNAi, in vitro adhesion assay and motility assay were performed. Our results indicated that 1 the flagellar assembly pathway was sensitive to environmental stresses, 2 the flagellar assembly pathway played an important role in V. alginolyticus adhesion, and 3 motility is not the only way in which the flagellar assembly pathway affects adhesion.

  12. From ultrastructural flagellar sperm defects to the health of babies conceived by ICSI.

    Science.gov (United States)

    Fauque, Patricia; Albert, Martine; Serres, Catherine; Viallon, Vivian; Davy, Céline; Epelboin, Sylvie; Chalas, Céline; Jouannet, Pierre; Patrat, Catherine

    2009-09-01

    The objective of this retrospective study was to describe a population of patients displaying impaired sperm motility due to ultrastructural flagellar defects and to analyse the intracytoplasmic sperm injection (ICSI) results and neonatal outcomes in this population. The fertilization rate, embryo quality, clinical pregnancy rate, implantation rate, birth rate and perinatal health of babies were determined. Patients (n = 20) were divided into seven categories according to ultrastructural flagellar abnormalities. The type of flagellar abnormality significantly affected the fertilization rate (P <0.025). Two types of flagellar abnormalities showed slower early embryo cleavage kinetics (P <0.001) when axonemal central structures and periaxonemmal columns were abnormal or absent. Of 53 ICSI attempts, 14 resulted in clinical pregnancies (26.4% per cycle) after fresh and frozen embryo transfer. Three (21.4%) of these pregnancies ended in miscarriages and, in the remaining, 12 infants were born (7.2% of transferred embryos). The outcomes differed according to the ultrastructural defect. This study demonstrates that a high proportion of patients could father a child (45.0%). However, flagellar abnormalities appear to influence ICSI results and fetal development.

  13. Higher order jet prolongations type gauge natural bundles over vector bundles

    Directory of Open Access Journals (Sweden)

    Jan Kurek

    2004-05-01

    Full Text Available Let $rgeq 3$ and $mgeq 2$ be natural numbers and $E$ be a vector bundle with $m$-dimensional basis. We find all gauge natural bundles ``similar" to the $r$-jet prolongation bundle $J^rE$ of $E$. We also find all gauge natural bundles ``similar" to the vector $r$-tangent bundle $(J^r_{fl}(E,R_0^*$ of $E$.

  14. Flagellar coordination in Chlamydomonas cells held on micropipettes.

    Science.gov (United States)

    Rüffer, U; Nultsch, W

    1998-01-01

    The two flagella of Chlamydomonas are known to beat synchronously: During breaststroke beating they are generally coordinated in a bilateral way while in shock responses during undulatory beating coordination is mostly parallel [Rüffer and Nultsch, 1995: Botanica Acta 108:169-276]. Analysis of a great number of shock responses revealed that in undulatory beats also periods of bilateral coordination are found and that the coordination type may change several times during a shock response, without concomitant changes of the beat envelope and the beat period. In normal wt cells no coordination changes are found during breaststroke beating, but only short temporary asynchronies: During 2 or 3 normal beats of the cis flagellum, the trans flagellum performs 3 or 4 flat beats with a reduced beat envelope and a smaller beat period, resulting in one additional trans beat. Long periods with flat beats of the same shape and beat period are found in both flagella of the non-phototactic mutant ptx1 and in defective wt 622E cells. During these periods, the coordination is parallel, the two flagella beat alternately. A correlation between normal asynchronous trans beats and the parallel-coordinated beats in the presumably cis defective cells and also the undulatory beats is discussed. In the cis defective cells, a perpetual spontaneous change between parallel beats with small beat periods (higher beat frequency) and bilateral beats with greater beat periods (lower beat frequency) are observed and render questionable the existence of two different intrinsic beat frequencies of the two flagella cis and trans. Asynchronies occur spontaneously but may also be induced by light changes, either step-up or step-down, but not by both stimuli in turn as breaststroke flagellar photoresponses (BFPRs). Asynchronies are not involved in phototaxis. They are independent of the BFPRs, which are supposed to be the basis of phototaxis. Both types of coordination must be assumed to be regulated

  15. Fluid structure interaction in tube bundles

    International Nuclear Information System (INIS)

    Brochard, D.; Jedrzejewski, F.; Gibert, R.J.

    1995-01-01

    A lot of industrial components contain tube bundles immersed in a fluid. The mechanical analysis of such systems requires the study of the fluid structure interaction in the tube bundle. Simplified methods, based on homogenization methods, have been developed to analyse such phenomenon and have been validated through experimental results. Generally, these methods consider only the fluid motion in a plan normal to the bundle axis. This paper will analyse, in a first part, the fluid structure interaction in a tube bundle through a 2D finite element model representing the bundle cross section. The influence of various parameters like the bundle size, and the bundle confinement will be studied. These results will be then compared with results from homogenization methods. Finally, the influence of the 3D fluid motion will be investigated, in using simplified methods. (authors). 11 refs., 12 figs., 2 tabs

  16. Minimum Information Loss Based Multi-kernel Learning for Flagellar Protein Recognition in Trypanosoma Brucei

    KAUST Repository

    Wang, Jim Jing-Yan

    2014-12-01

    Trypanosma brucei (T. Brucei) is an important pathogen agent of African trypanosomiasis. The flagellum is an essential and multifunctional organelle of T. Brucei, thus it is very important to recognize the flagellar proteins from T. Brucei proteins for the purposes of both biological research and drug design. In this paper, we investigate computationally recognizing flagellar proteins in T. Brucei by pattern recognition methods. It is argued that an optimal decision function can be obtained as the difference of probability functions of flagella protein and the non-flagellar protein for the purpose of flagella protein recognition. We propose to learn a multi-kernel classification function to approximate this optimal decision function, by minimizing the information loss of such approximation which is measured by the Kull back-Leibler (KL) divergence. An iterative multi-kernel classifier learning algorithm is developed to minimize the KL divergence for the problem of T. Brucei flagella protein recognition, experiments show its advantage over other T. Brucei flagellar protein recognition and multi-kernel learning methods. © 2014 IEEE.

  17. Identification of flagellar and associated polypeptides of Helicobacter (formerly Campylobacter) pylori.

    Science.gov (United States)

    Luke, C J; Kubiak, E; Cockayne, A; Elliott, T S; Penn, C W

    1990-09-01

    Flagella of Helicobacter pylori were isolated from intact organisms by shearing and differential centrifugation. Treatment of the flagella with the detergent Triton X-100 removed the flagellar sheath, which was confirmed by electron microscopy, and the remaining naked flagella were shown by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) to consist primarily of a single 54 kilodalton (kDa) polypeptide. This was confirmed by immunogold labelling and electron microscopy of detergent treated whole organisms, using a mouse antiserum specific for the 54 kDa polypeptide. Polypeptides solubilised from crude flagellar preparations by detergent treatment were found to have molecular weights of 26, 30, 58, 62, 66 and 80 kDa. These polypeptides are possible components of the flagellar sheath and they may represent outer membrane proteins, based on the assumption that the flagellar sheath is related in composition to the outer membrane of the organism. Analysis and definition of these components of the surface structures of the organism are important in understanding the interaction between the organism and its host in pathogenesis.

  18. Self-Sustained Oscillatory Sliding Movement of Doublet Microtubules and Flagellar Bend Formation.

    Directory of Open Access Journals (Sweden)

    Sumio Ishijima

    Full Text Available It is well established that the basis for flagellar and ciliary movements is ATP-dependent sliding between adjacent doublet microtubules. However, the mechanism for converting microtubule sliding into flagellar and ciliary movements has long remained unresolved. The author has developed new sperm models that use bull spermatozoa divested of their plasma membrane and midpiece mitochondrial sheath by Triton X-100 and dithiothreitol. These models enable the observation of both the oscillatory sliding movement of activated doublet microtubules and flagellar bend formation in the presence of ATP. A long fiber of doublet microtubules extruded by synchronous sliding of the sperm flagella and a short fiber of doublet microtubules extruded by metachronal sliding exhibited spontaneous oscillatory movements and constructed a one beat cycle of flagellar bending by alternately actuating. The small sliding displacement generated by metachronal sliding formed helical bends, whereas the large displacement by synchronous sliding formed planar bends. Therefore, the resultant waveform is a half-funnel shape, which is similar to ciliary movements.

  19. The dynamic instability in the hook/flagellum system that triggers bacterial flicks

    Science.gov (United States)

    Jabbarzadeh, Mehdi; Fu, Henry

    2017-11-01

    Dynamical bending, buckling, and polymorphic transformations of the flagellum are known to affect bacterial motility, but run-reverse-flick motility of monotrichous bacteria also involves the even more flexible hook, which connects the flagellum to the cell body. Here, we identify the dynamic buckling mechanism that produces flicks in Vibrio alginolyticus. Estimates of forces and torques on the hook from experimental observations suggest that flicks are triggered at stresses below the hook's static Euler buckling criterion. Using an accurate linearization of the Kirchoff rod model for the hook in a model of a swimming bacterium with rigid flagellum, we show that as hook stiffness decreases there is a transition from on-axis flagellar rotation with small hook deflections to flagellar precession with large deflections. When flagellum flexibility is incorporated, the precession is disrupted by significant flagellar bending - i.e., incipient flicks. The predicted onset of dynamic instabilities corresponds well with experimentally observed flick events.

  20. Job Management and Task Bundling

    Science.gov (United States)

    Berkowitz, Evan; Jansen, Gustav R.; McElvain, Kenneth; Walker-Loud, André

    2018-03-01

    High Performance Computing is often performed on scarce and shared computing resources. To ensure computers are used to their full capacity, administrators often incentivize large workloads that are not possible on smaller systems. Measurements in Lattice QCD frequently do not scale to machine-size workloads. By bundling tasks together we can create large jobs suitable for gigantic partitions. We discuss METAQ and mpi_jm, software developed to dynamically group computational tasks together, that can intelligently backfill to consume idle time without substantial changes to users' current workflows or executables.

  1. Bundling and mergers in energy markets

    International Nuclear Information System (INIS)

    Granier, Laurent; Podesta, Marion

    2010-01-01

    Does bundling trigger mergers in energy industries? We observe mergers between firms belonging to various energy markets, for instance between gas and electricity providers. These mergers enable firms to bundle. We consider two horizontally differentiated markets. In this framework, we show that bundling strategies in energy markets create incentives to form multi-market firms in order to supply bi-energy packages. Moreover, we find that this type of merger is detrimental to social welfare. (author)

  2. A novel flagellar sheath protein, FcpA, determines filament coiling, translational motility and virulence for the Leptospira spirochete.

    Science.gov (United States)

    Wunder, Elsio A; Figueira, Cláudio P; Benaroudj, Nadia; Hu, Bo; Tong, Brian A; Trajtenberg, Felipe; Liu, Jun; Reis, Mitermayer G; Charon, Nyles W; Buschiazzo, Alejandro; Picardeau, Mathieu; Ko, Albert I

    2016-08-01

    Leptospira are unique among bacteria based on their helical cell morphology with hook-shaped ends and the presence of periplasmic flagella (PF) with pronounced spontaneous supercoiling. The factors that provoke such supercoiling, as well as the role that PF coiling plays in generating the characteristic hook-end cell morphology and motility, have not been elucidated. We have now identified an abundant protein from the pathogen L. interrogans, exposed on the PF surface, and named it Flagellar-coiling protein A (FcpA). The gene encoding FcpA is highly conserved among Leptospira and was not found in other bacteria. fcpA(-) mutants, obtained from clinical isolates or by allelic exchange, had relatively straight, smaller-diameter PF, and were not able to produce translational motility. These mutants lost their ability to cause disease in the standard hamster model of leptospirosis. Complementation of fcpA restored the wild-type morphology, motility and virulence phenotypes. In summary, we identified a novel Leptospira 36-kDa protein, the main component of the spirochete's PF sheath, and a key determinant of the flagella's coiled structure. FcpA is essential for bacterial translational motility and to enable the spirochete to penetrate the host, traverse tissue barriers, disseminate to cause systemic infection and reach target organs. © 2016 John Wiley & Sons Ltd.

  3. Crystal Structure of the Flagellar Rotor Protein FliN from Thermotoga maritima†

    Science.gov (United States)

    Brown, Perry N.; Mathews, Michael A. A.; Joss, Lisa A.; Hill, Christopher P.; Blair, David F.

    2005-01-01

    FliN is a component of the bacterial flagellum that is present at levels of more than 100 copies and forms the bulk of the C ring, a drum-shaped structure at the inner end of the basal body. FliN interacts with FliG and FliM to form the rotor-mounted switch complex that controls clockwise-counterclockwise switching of the motor. In addition to its functions in motor rotation and switching, FliN is thought to have a role in the export of proteins that form the exterior structures of the flagellum (the rod, hook, and filament). Here, we describe the crystal structure of most of the FliN protein of Thermotoga maritima. FliN is a tightly intertwined dimer composed mostly of β sheet. Several well-conserved hydrophobic residues form a nonpolar patch on the surface of the molecule. A mutation in the hydrophobic patch affected both flagellar assembly and switching, showing that this surface feature is important for FliN function. The association state of FliN in solution was studied by analytical ultracentrifugation, which provided clues to the higher-level organization of the protein. T. maritima FliN is primarily a dimer in solution, and T. maritima FliN and FliM together form a stable FliM1-FliN4 complex. Escherichia coli FliN forms a stable tetramer in solution. The arrangement of FliN subunits in the tetramer was modeled by reference to the crystal structure of tetrameric HrcQBC, a related protein that functions in virulence factor secretion in Pseudomonas syringae. The modeled tetramer is elongated, with approximate dimensions of 110 by 40 by 35Å, and it has a large hydrophobic cleft formed from the hydrophobic patches on the dimers. On the basis of the present data and available electron microscopic images, we propose a model for the organization of FliN subunits in the C ring. PMID:15805535

  4. Hydraulic characteristics of HANARO fuel bundles

    Energy Technology Data Exchange (ETDEWEB)

    Cho, S.; Chung, H. J.; Chun, S. Y.; Yang, S. K.; Chung, M. K. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    This paper presents the hydraulic characteristics measured by using LDV (Laser Doppler Velocimetry) in subchannels of HANARO, KAERI research reactor, fuel bundle. The fuel bundle consists of 18 axially finned rods with 3 spacer grids, which are arranged in cylindrical configuration. The effects of the spacer grids on the turbulent flow were investigated by the experimental results. Pressure drops for each component of the fuel bundle were measured, and the friction factors of fuel bundle and loss coefficients for the spacer grids were estimated from the measured pressure drops. Implications regarding the turbulent thermal mixing were discussed. Vibration test results measured by using laser vibrometer were presented. 9 refs., 12 figs. (Author)

  5. Isolation and characterization of flagellar filament from zoospores of Dermatophilus congolensis.

    Science.gov (United States)

    Hiraizumi, Mieko; Tagawa, Yuichi

    2014-09-17

    Highly motile zoospores from Dermatophilus congolensis bovine isolates from clinical dermatophilosis in Japan were obtained by culturing at 27°C in an ambient atmosphere on heart infusion agar supplemented with 5% defibrinated sheep blood for 72h or in heart infusion broth for 48h with gentle shaking. After vigorous mechanical agitation of the zoospore suspension, the flagellar filaments detached from motile zoospores and were isolated in the clear gelatinous part of the final pellet by differential centrifugation. Typical morphology of a flagellar filament, with a width of approximately 15nm, was observed in the isolated flagellar filament by electron microscopy. A single major protein (flagellin) band with an apparent molecular mass of 35kDa was detected in the flagellar filament of D. congolensis strain AM-1 and that of 33kDa was detected in strain IT-2 by SDS-PAGE. In immunoblot analysis of whole-cell proteins from seven isolates of D. congolensis, antiserum to strain AM-1 zoospores reacted with the 35-kDa antigen band of strain AM-1, but not with any antigen band of other strains in a similar molecular mass range. In contrast, antiserum to strain IT-2 zoospores reacted with antigen bands at 33kDa from six strains, except strain AM-1. Similar strain-specific reactions of these anti-zoospore sera with isolated flagellar filaments from strains AM-1 and IT-2 were confirmed by immunoblot, indicating the presence of antigenic variations of flagellins of D. congolensis zoospores. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Reactions of Chicken Sera to Recombinant Campylobacter jejuni Flagellar Proteins

    Science.gov (United States)

    Campylobacter jejuni is a Gram-negative rod bacterium and is the leading but under-reported bacterial food-borne pathogen that causes human campylobacteriosis worldwide. Raw or undercooked poultry products are regarded as a major source for human infection. C. jejuni flagella have been implicated ...

  7. Wall pressure fluctuations in rod bundles

    International Nuclear Information System (INIS)

    Moeller, S.V.

    1990-01-01

    Microphones and hot wires were applied for the measurement of wall pressure fluctuations and velocity fluctuations in rod bundles with several aspect ratios. By means of auto and cross spectral density functions their interdependence was investigated. Results show that the pressure fluctuations in rod bundles are mainly associated with the phenomenon of quasi-periodic flow pulsations between subchannels. (author)

  8. Anatomic Double-bundle ACL Reconstruction

    NARCIS (Netherlands)

    Schreiber, Verena M.; van Eck, Carola F.; Fu, Freddie H.

    2010-01-01

    Rupture of the anterior cruciate ligament (ACL) is one of the most frequent forms of knee trauma. The traditional surgical treatment for ACL rupture is single-bundle reconstruction. However, during the past few years there has been a shift in interest toward double-bundle reconstruction to closely

  9. Intragastric immunization with recombinant Lactobacillus casei expressing flagellar antigen confers antibody-independent protective immunity against Salmonella enterica serovar Enteritidis

    NARCIS (Netherlands)

    Kajikawa, A.; Satoh, E.; Leer, R.J.; Yamamoto, S.; Igimi, S.

    2007-01-01

    A recombinant Lactobacillus casei expressing a flagellar antigen from Salmonella enterica serovar Enteritidis was constructed and evaluated as a mucosal vaccine. Intragastric immunization of the recombinant strain conferred protective immunity against Salmonella infection in mice. This immunization

  10. Higgs bundles and four manifolds

    International Nuclear Information System (INIS)

    Park, Jae-Suk.

    2002-01-01

    It is known that the Seiberg-Witten invariants, derived from supersymmetric Yang-Mill theories in four dimensions, do not distinguish smooth structure of certain non-simply-connected four manifolds. We propose generalizations of Donaldson-Witten and Vafa-Witten theories on a Kaehler manifold based on Higgs bundles. We showed, in particular, that the partition function of our generalized Vafa-Witten theory can be written as the sum of contributions our generalized Donaldson-Witten invariants and generalized Seiberg-Witten invariants. The resulting generalized Seiberg-Witten invariants might have, conjecturally, information on smooth structure beyond the original Seiberg-Witten invariants for non-simply-connected case

  11. Induction of phospholipase- and flagellar synthesis in Serratia liquefaciens is controlled by expression of the flagellar master operon flhD

    DEFF Research Database (Denmark)

    Givskov, M; Eberl, L; Christiansen, Gunna

    1995-01-01

    When a liquid culture of Serratia spp. reaches the last part of the logarithmic phase of growth it induces the synthesis of several extracellular hydrolytic enzymes. In this communication we show that synthesis and secretion of the extracellular phospholipase is coupled to expression of flagella....... Expression of flagella is demonstrated to follow a growth-phase-dependent pattern. Cloning, complementation studies and DNA-sequencing analysis has identified a genetic region in Serratia liquefaciens which exhibits extensive homology to the Escherichia coli flhD flagellar master operon. Interruption...

  12. Design of a comprehensive biochemistry and molecular biology experiment: phase variation caused by recombinational regulation of bacterial gene expression.

    Science.gov (United States)

    Sheng, Xiumei; Xu, Shungao; Lu, Renyun; Isaac, Dadzie; Zhang, Xueyi; Zhang, Haifang; Wang, Huifang; Qiao, Zheng; Huang, Xinxiang

    2014-01-01

    Scientific experiments are indispensable parts of Biochemistry and Molecular Biology. In this study, a comprehensive Biochemistry and Molecular Biology experiment about Salmonella enterica serovar Typhi Flagellar phase variation has been designed. It consisted of three parts, namely, inducement of bacterial Flagellar phase variation, antibody agglutination test, and PCR analysis. Phase variation was observed by baterial motility assay and identified by antibody agglutination test and PCR analysis. This comprehensive experiment can be performed to help students improve their ability to use the knowledge acquired in Biochemistry and Molecular Biology. Copyright © 2014 by The International Union of Biochemistry and Molecular Biology.

  13. Improving BWR fuel critical power without increasing bundle pressure drop

    International Nuclear Information System (INIS)

    Matzner, B.; Shiraishi, L.M.; Danielson, D.W.; Congdon, S.P.

    2004-01-01

    It has been almost axiomatic that BWR fuel bundle critical power performance could not be improved without an accompanying increase in bundle pressure drop. It appeared that in order to increase the bundle dryout resistance it was necessary to perturb the bundle coolant flow paths in some fashion. This resulted in an unacceptable bundle pressure drop increase. However, by adding part length rods to decrease bundle pressure drop and by inserting an extra spacer with rearranged spacer pitch and flow trippers on the channel wall at the top of the bundle to increase critical power it was possible to achieve the goal of increased bundle critical power without pressure drop increase. (author)

  14. Nonlinear instability in flagellar dynamics: a novel modulation mechanism in sperm migration?

    Science.gov (United States)

    Gadelha, H.; Gaffney, E.; Smith, D.; Kirkman-Brown, J.

    2010-11-01

    Throughout biology, cells and organisms use flagella and cilia to propel fluid and achieve motility. While the mechanics of flagellum-fluid interaction has been the subject of extensive mathematical studies, these models have been restricted to being geometrically linear or weakly nonlinear. In this talk, we study the effect of geometrical nonlinearity, focusing on the spermatozoon flagellum. For a wide range of physiologically relevant parameters, the nonlinear model predicts that flagellar compression by the internal forces initiates an effective buckling behaviour, leading to a symmetry-breaking bifurcation that causes profound and complicated changes in the waveform and swimming trajectory, as well as the breakdown of the linear theory. The emergent waveform also induces curved swimming in an otherwise symmetric system, with the swimming trajectory being sensitive to head shape - no signalling or asymmetric forces are required. We conclude that non-linear models are essential in understanding the flagellar waveform in migratory human sperm.

  15. Flagellar apparatus and nuclear chambers of the green dinoflagellate Gymnodinium chlorophorum

    DEFF Research Database (Denmark)

    Hansen, Gert; Moestrup, Øjvind

    2005-01-01

    The green dinoflagellate Gymnodinium chlorophorum (BAH ME 100, the type culture) was reexamined with emphasis on the structure of the flagellar apparatus and nuclear envelope. Like other Gymnodinium species, G. chlorophorum possessed a nuclear fibrous connective linking the flagellar apparatus...... present in G. chlorophorum similar to those reported in Gymnodinium aureolum and Gymnodinium nolleri. In contrast to the type species of Gymnodinium, Gymnodinium fuscum, only one nuclear pore was present per chamber. The presence of a feeding tube (peduncle) suggests that G. chlorophorum is mixotrophic....... Although the fine structure of G. chlorophorum revealed its affiliation to the Gymnodinium group the above discrepancies set it apart, indicating that it might belong in a different genus....

  16. The phylogeny of swimming kinematics: The environment controls flagellar waveforms in sperm motility

    Science.gov (United States)

    Guasto, Jeffrey; Burton, Lisa; Zimmer, Richard; Hosoi, Anette; Stocker, Roman

    2013-11-01

    In recent years, phylogenetic and molecular analyses have dominated the study of ecology and evolution. However, physical interactions between organisms and their environment, a fundamental determinant of organism ecology and evolution, are mediated by organism form and function, highlighting the need to understand the mechanics of basic survival strategies, including locomotion. Focusing on spermatozoa, we combined high-speed video microscopy and singular value decomposition analysis to quantitatively compare the flagellar waveforms of eight species, ranging from marine invertebrates to humans. We found striking similarities in sperm swimming kinematics between genetically dissimilar organisms, which could not be uncovered by phylogenetic analysis. The emergence of dominant waveform patterns across species are suggestive of biological optimization for flagellar locomotion and point toward environmental cues as drivers of this convergence. These results reinforce the power of quantitative kinematic analysis to understand the physical drivers of evolution and as an approach to uncover new solutions for engineering applications, such as micro-robotics.

  17. Why (almost) all bundles are chiral

    Science.gov (United States)

    Kost-Smith, Zachary V.; Blackwell, Robert A.; Glaser, Matthew A.

    2014-03-01

    We examine the self assembly of bundles of achiral hard rods with distributed, short-range attractive interactions. We show that in the majority of cases the equilibrium state of the bundle is chiral, with a double twist structure. We use biased Monte Carlo techniques and cell theory to compute the free energy as a function of an appropriately defined twist order parameter, and show that the formation of spontaneously chiral bundles is driven by maximization of orientational entropy. The finite curvature of the bundle boundary permits orientational escape, in which the circumferential angular range of motion of the rods is maximized for some finite average tilt. We map out the phase diagram of bundles in terms of the density, the ratio of rod length to bundle radius, L / R , and rod aspect ratio, L / D , and find transitions between untwisted, weakly twisted, and strongly twisted states. This work helps explain the common observation of twisted macroscopic bundles, and may provide insight into observations of twist in self-assembled membranes of colloidal rods.[2] This work funded by NSF MRSEC Grant DMR-0820579.

  18. Preliminary report: NIF laser bundle review

    International Nuclear Information System (INIS)

    Tietbohl, G.L.; Larson, D.W.; Erlandson, A.C.

    1995-01-01

    As requested in the guidance memo 1 , this committe determined whether there are compelling reasons to recommend a change from the NIF CDR baseline laser. The baseline bundle design based on a tradeoff between cost and technical risk, which is replicated four times to create the required 192 beams. The baseline amplifier design uses bottom loading 1x4 slab and flashlamp cassettes for amplifier maintenance and large vacuum enclosures (2.5m high x 7m wide in cross-section for each of the two spatial filters in each of the four bundles. The laser beams are arranged in two laser bays configured in a u-shape around the target area. The entire bundle review effort was performed in a very short time (six weeks) and with limited resources (15 personnel part-time). This should be compared to the effort that produced the CDR design (12 months, 50 to 100 personnel). This committee considered three alternate bundle configurations (2x2, 4x2, and 4x4 bundles), and evaluated each bundle against the baseline design using the seven requested issues in the guidance memo: Cost; schedule; performance risk; maintainability/operability; hardware failure cost exposure; activation; and design flexibility. The issues were reviewed to identify differences between each alternate bundle configuration and the baseline

  19. Visualization of bacterial flagella dynamics in a viscous shear flow

    Science.gov (United States)

    Ali, Jamel; Kim, Minjun

    2016-11-01

    We report on the dynamics of tethered bacterial flagella in an applied viscous shear flow and analyze their behavior using image processing. Flagellin proteins were repolymerized into flagellar filaments functionalized with biotin at their proximal end, and allowed to self-assemble within a micro channel coated with streptavidin. It was observed that all attached flagellar filaments aligned with the steady shear flow of various polymeric solutions. Furthermore it was observed that many of the filaments were stretched, and at elevated flow rates began to undergo polymorphic transformations, which were initiated at one end of the flagellum. When undergoing a change to a different helical form the flagellum was observed to transform to an oppositely handed helix, as to counteract the viscous torque imparted by the shear flow. It was also observed that some flagellar filaments did not undergo polymorphic transformations, but rotated about their helical axis. The rate of this rotation appears to be a function of the applied flow rate. These results expand on previous experimental work and aid in the development of a novel platform that harnesses the autonomic response of a 'forest' of bacterial flagella for engineering applications. This work was funded by NSF Grant CMMI-1000255, KEIT MOTIE Grant No. 10052980, and with Government support under and awarded by DoD, Air Force Office of Scientific Research, National Defense Science and Engineering Graduate (NDSEG) Fellowship, 32 CFR 168a.

  20. Discovery of a proteolytic flagellin family in diverse bacterial phyla that assembles enzymatically active flagella.

    Science.gov (United States)

    Eckhard, Ulrich; Bandukwala, Hina; Mansfield, Michael J; Marino, Giada; Cheng, Jiujun; Wallace, Iain; Holyoak, Todd; Charles, Trevor C; Austin, John; Overall, Christopher M; Doxey, Andrew C

    2017-09-12

    Bacterial flagella are cell locomotion and occasional adhesion organelles composed primarily of the polymeric protein flagellin, but to date have not been associated with any enzymatic function. Here, we report the bioinformatics-driven discovery of a class of enzymatic flagellins that assemble to form proteolytically active flagella. Originating by a metallopeptidase insertion into the central flagellin hypervariable region, this flagellin family has expanded to at least 74 bacterial species. In the pathogen, Clostridium haemolyticum, metallopeptidase-containing flagellin (which we termed flagellinolysin) is the second most abundant protein in the flagella and is localized to the extracellular flagellar surface. Purified flagellar filaments and recombinant flagellin exhibit proteolytic activity, cleaving nearly 1000 different peptides. With ~ 20,000 flagellin copies per  ~ 10-μm flagella this assembles the largest proteolytic complex known. Flagellum-mediated extracellular proteolysis expands our understanding of the functional plasticity of bacterial flagella, revealing this family as enzymatic biopolymers that mediate interactions with diverse peptide substrates.So far no enzymatic activity has been attributed to flagellin, the major component of bacterial flagella. Here the authors use bioinformatic analysis and identify a metallopeptidase insertion in flagellins from 74 bacterial species and show that recombinant flagellin and flagellar filaments have proteolytic activity.

  1. Contraction of cross-linked actomyosin bundles

    Science.gov (United States)

    Yoshinaga, Natsuhiko; Marcq, Philippe

    2012-08-01

    Cross-linked actomyosin bundles retract when severed in vivo by laser ablation, or when isolated from the cell and micromanipulated in vitro in the presence of ATP. We identify the timescale for contraction as a viscoelastic time τ, where the viscosity is due to (internal) protein friction. We obtain an estimate of the order of magnitude of the contraction time τ ≈ 10-100 s, consistent with available experimental data for circumferential microfilament bundles and stress fibers. Our results are supported by an exactly solvable, hydrodynamic model of a retracting bundle as a cylinder of isotropic, active matter, from which the order of magnitude of the active stress is estimated.

  2. Fibre bundles. Monopoles and internal symmetries

    International Nuclear Information System (INIS)

    Horvathy, P.A.; Rawnsley, J.H.

    1985-01-01

    Asymptotic monopole configurations are described in fibre-bundle terms. Bundle reduction -the geometric procedure for spontaneous symmetry breaking- is studied in detail: the monopole-bundle is reducible to a given subgroup K of the gauge group if and only if the Higgs charge satisfies a suitable constraint. The Yang-Mills connection reduces if and only if the non-Abelian charge vector belongs to the Lie algebra of K. The problem of ''global color'' can also be formulated in these terms. Our theory allows us to determine which subgroups K are internal symmetries of a given field configuration

  3. On muon bundles from the Universe

    Science.gov (United States)

    Kankiewicz, P.; Rybczyński, M.; Włdarczyk, Z.; Wilk, G.

    2018-01-01

    Recently the CERN ALICE experiment, in its dedicated cosmic ray run, observed muon bundles of very high multiplicities, thereby confirming similar findings from the LEP era at CERN (in the CosmoLEP project). We found significant evidence for anisotropy of arrival directions of the observed high multiplicity muonic bundles. The distribution on celestial sphere and the estimated directionality suggests their possible extragalactic source. We argue that muonic bundles of highest multiplicity are produced by strangelets, hypothetical stable lumps of strange quark matter infiltrating our Universe.

  4. Geometry of Quantum Principal Bundles. Pt. 1

    International Nuclear Information System (INIS)

    Durdevic, M.

    1996-01-01

    A theory of principal bundles possessing quantum structure groups and classical base manifolds is presented. Structural analysis of such quantum principal bundles is performed. A differential calculus is constructed, combining differential forms on the base manifold with an appropriate differential calculus on the structure quantum group. Relations between the calculus on the group and the calculus on the bundle are investigated. A concept of (pseudo)tensoriality is formulated. The formalism of connections is developed. In particular, operators of horizontal projection, covariant derivative and curvature are constructed and analyzed. Generalizations of the first Structure Equation and of the Bianchi identity are found. Illustrative examples are presented. (orig.)

  5. Bundles of C*-categories and duality

    OpenAIRE

    Vasselli, Ezio

    2005-01-01

    We introduce the notions of multiplier C*-category and continuous bundle of C*-categories, as the categorical analogues of the corresponding C*-algebraic notions. Every symmetric tensor C*-category with conjugates is a continuous bundle of C*-categories, with base space the spectrum of the C*-algebra associated with the identity object. We classify tensor C*-categories with fibre the dual of a compact Lie group in terms of suitable principal bundles. This also provides a classification for ce...

  6. Trypanin, a component of the flagellar Dynein regulatory complex, is essential in bloodstream form African trypanosomes.

    Directory of Open Access Journals (Sweden)

    Katherine S Ralston

    2006-09-01

    Full Text Available The Trypanosoma brucei flagellum is a multifunctional organelle with critical roles in motility, cellular morphogenesis, and cell division. Although motility is thought to be important throughout the trypanosome lifecycle, most studies of flagellum structure and function have been restricted to the procyclic lifecycle stage, and our knowledge of the bloodstream form flagellum is limited. We have previously shown that trypanin functions as part of a flagellar dynein regulatory system that transmits regulatory signals from the central pair apparatus and radial spokes to axonemal dyneins. Here we investigate the requirement for this dynein regulatory system in bloodstream form trypanosomes. We demonstrate that trypanin is localized to the flagellum of bloodstream form trypanosomes, in a pattern identical to that seen in procyclic cells. Surprisingly, trypanin RNA interference is lethal in the bloodstream form. These knockdown mutants fail to initiate cytokinesis, but undergo multiple rounds of organelle replication, accumulating multiple flagella, nuclei, kinetoplasts, mitochondria, and flagellum attachment zone structures. These findings suggest that normal flagellar beat is essential in bloodstream form trypanosomes and underscore the emerging concept that there is a dichotomy between trypanosome lifecycle stages with respect to factors that contribute to cell division and cell morphogenesis. This is the first time that a defined dynein regulatory complex has been shown to be essential in any organism and implicates the dynein regulatory complex and other enzymatic regulators of flagellar motility as candidate drug targets for the treatment of African sleeping sickness.

  7. Bimodal rheotactic behavior reflects flagellar beat asymmetry in human sperm cells

    Science.gov (United States)

    Bukatin, Anton; Kukhtevich, Igor; Stoop, Norbert; Dunkel, Jörn; Kantsler, Vasily

    2015-01-01

    Rheotaxis, the directed response to fluid velocity gradients, has been shown to facilitate stable upstream swimming of mammalian sperm cells along solid surfaces, suggesting a robust physical mechanism for long-distance navigation during fertilization. However, the dynamics by which a human sperm orients itself relative to an ambient flow is poorly understood. Here, we combine microfluidic experiments with mathematical modeling and 3D flagellar beat reconstruction to quantify the response of individual sperm cells in time-varying flow fields. Single-cell tracking reveals two kinematically distinct swimming states that entail opposite turning behaviors under flow reversal. We constrain an effective 2D model for the turning dynamics through systematic large-scale parameter scans, and find good quantitative agreement with experiments at different shear rates and viscosities. Using a 3D reconstruction algorithm to identify the flagellar beat patterns causing left or right turning, we present comprehensive 3D data demonstrating the rolling dynamics of freely swimming sperm cells around their longitudinal axis. Contrary to current beliefs, this 3D analysis uncovers ambidextrous flagellar waveforms and shows that the cell’s turning direction is not defined by the rolling direction. Instead, the different rheotactic turning behaviors are linked to a broken mirror symmetry in the midpiece section, likely arising from a buckling instability. These results challenge current theoretical models of sperm locomotion. PMID:26655343

  8. Effective viscosity of a suspension of flagellar-beating microswimmers: Three-dimensional modeling.

    Science.gov (United States)

    Jibuti, Levan; Zimmermann, Walter; Rafaï, Salima; Peyla, Philippe

    2017-11-01

    Micro-organisms usually can swim in their liquid environment by flagellar or ciliary beating. In this numerical work, we analyze the influence of flagellar beating on the orbits of a swimming cell in a shear flow. We also calculate the effect of the flagellar beating on the rheology of a dilute suspension of microswimmers. A three-dimensional model is proposed for Chlamydomonas Reinhardtii swimming with a breaststroke-like beating of two anterior flagella modeled by two counter-rotating fore beads. The active swimmer model reveals unusual angular orbits in a linear shear flow. Namely, the swimmer sustains orientations transiently across the flow. Such behavior is a result of the interplay between shear flow and the swimmer's periodic beating motion of flagella, which exert internal torques on the cell body. This peculiar behavior has some significant consequences on the rheological properties of the suspension. We calculate Einstein's viscosity of the suspension composed of such isolated modeled microswimmers (dilute case) in a shear flow. We use numerical simulations based on a Rotne-Prager-like approximation for hydrodynamic interaction between simplified flagella and the cell body. The results show an increased intrinsic viscosity for active swimmer suspensions in comparison to nonactive ones as well as a shear thinning behavior in accordance with previous experimental measurements [Phys. Rev. Lett. 104, 098102 (2010)10.1103/PhysRevLett.104.098102].

  9. Molecular automata assembly: principles and simulation of bacterial membrane construction.

    Science.gov (United States)

    Lahoz-Beltra, R

    1997-01-01

    The motivation to understand the basic rules and principles governing molecular self-assembly may be relevant to explain in the context of molecular biology the self-organization and biological functions exhibited within cells. This paper presents a molecular automata model to simulate molecular self-assembly introducing the concept of molecular programming to simulate the biological function or operation performed by an assembled molecular state machine. The method is illustrated modelling Escherichia coli membrane construction including the assembly and operation of ATP synthase as well as the assembly of the bacterial flagellar motor. Flagellar motor operation was simulated using a different approach based on state machine definition used in virtual reality systems. The proposed methodology provides a modelling framework for simulation of biological functions performed by cellular components and other biological systems suitable to be modelled as molecular state machines.

  10. Broadcast scheduling with data bundles

    Science.gov (United States)

    Chen, Fangfei; Pizzocaro, Diego; Johnson, Matthew P.; Bar-Noy, Amotz; Preece, Alun; La Porta, Thomas

    2011-06-01

    Broadcast scheduling has been extensively studied in wireless environments, where a base station broadcasts data to multiple users. Due to the sole wireless channel's limited bandwidth, only a subset of the needs may be satisfiable, and so maximizing total (weighted) throughput is a popular objective. In many realistic applications, however, data are dependent or correlated in the sense that the joint utility of a set of items is not simply the sum of their individual utilities. On the one hand, substitute data may provide overlapping information, so one piece of data item may have lower value if a second data item has already been delivered; on the other hand, complementary data are more valuable than the sum of their parts, if, for example, one data item is only useful in the presence of a second data item. In this paper, we define a data bundle to be a set of data items with possibly nonadditive joint utility, and we study a resulting broadcast scheduling optimization problem whose objective is to maximize the utility provided by the data delivered.

  11. Nuclear fuel bundle disassembly and assembly tool

    International Nuclear Information System (INIS)

    Yates, J.; Long, J.W.

    1975-01-01

    A nuclear power reactor fuel bundle is described which has a plurality of tubular fuel rods disposed in parallel array between two transverse tie plates. It is secured against disassembly by one or more locking forks which engage slots in tie rods which position the transverse plates. Springs mounted on the fuel and tie rods are compressed when the bundle is assembled thereby maintaining a continual pressure against the locking forks. Force applied in opposition to the springs permits withdrawal of the locking forks so that one tie plate may be removed, giving access to the fuel rods. An assembly and disassembly tool facilitates removal of the locking forks when the bundle is to be disassembled and the placing of the forks during assembly of the bundle. (U.S.)

  12. MAVEN Insitu Key Parameters Data Bundle

    Data.gov (United States)

    National Aeronautics and Space Administration — The insitu.calibrated level 2 science.data bundle contains selected fully calibrated (L2) data from the Particles and Fields package and NGIMS, together with...

  13. Einstein metrics on tangent bundles of spheres

    Energy Technology Data Exchange (ETDEWEB)

    Dancer, Andrew S [Jesus College, Oxford University, Oxford OX1 3DW (United Kingdom); Strachan, Ian A B [Department of Mathematics, University of Hull, Hull HU6 7RX (United Kingdom)

    2002-09-21

    We give an elementary treatment of the existence of complete Kaehler-Einstein metrics with nonpositive Einstein constant and underlying manifold diffeomorphic to the tangent bundle of the (n+1)-sphere.

  14. In-pool damaged fuel bundle recovery

    International Nuclear Information System (INIS)

    Piascik, T.G.; Patenaude, R.S.

    1988-01-01

    While preparing to rerack the Oyster Creek Nuclear Generating Station, GPU Nuclear had need to move a damaged fuel bundle. This bundle had no upper tie plate and could not be moved in the normal manner. GPU Nuclear formed a small, dedicated project team to disassemble, package, and move this damaged bundle. The team was composed of key personnel from GPU Nuclear Fuels Projects, OCNGS Operations and Proto-Power/Bisco, a specialty contractor who has fuel bundle reconstitution and rod consolidation experience, remote tooling, underwater video systems and experienced technicians. Proven tooling, clear procedures and a simple approach were important, but the key element was the spirit of teamwork and leadership exhibited by the people involved. In spite of several emergent problems which a task of this nature presents, this small, close knit utility/vendor team completed the work on schedule and within the exposure and cost budgets

  15. In-pool damaged fuel bundle recovery

    International Nuclear Information System (INIS)

    Piascik, T.G.; Patenaude, R.S.

    1988-01-01

    While preparing to rerack the Oyster Creek Nuclear Generating Station, GPU Nuclear had need to move a damaged fuel bundle. This bundle had no upper tie plate and could not be moved in the normal manner. GPU Nuclear formed a small, dedicated project team to disassemble, package and move this damaged bundle. The team was composed of key personnel from GPU Nuclear Fuels Projects, OCNGS Operations and Proto-Power / Bisco, a specialty contractor who has fuel bundle reconstitution and rod consolidation experience, remote tooling, underwater video systems and experienced technicians. Proven tooling, clear procedures and a simple approach were important, but the key element was the spirit of teamwork and leadership exhibited by the people involved

  16. Frobenius splitting of projective toric bundles

    Indian Academy of Sciences (India)

    He Xin

    2018-03-19

    Mar 19, 2018 ... Firstly it is easy to see that the image of s under the restriction map (2.5) falls in the χ-isotypical component of (Uσ , E), i.e. for all t ∈ T .... σ falls in the χ-isotypical component of (E,Uσ ). D. As mentioned in Remark 2.3, for a vector v .... The determinant of a toric bundle. LetE be a toric bundle on a toric variety X ...

  17. Principal bundles on the projective line

    Indian Academy of Sciences (India)

    M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22

    E-mail: vikram@math.tifr.res.in; subramnn@math.tifr.res.in. MS received 21 January 2002; revised 19 April 2002. Abstract. We classify principal G-bundles on the projective line over an arbitrary field k of characteristic = 2 or 3, where G is a reductive group. If such a bundle is trivial at a k-rational point, then the structure group ...

  18. Torsional Behavior of Axonal Microtubule Bundles

    Science.gov (United States)

    Lazarus, Carole; Soheilypour, Mohammad; Mofrad, Mohammad R.K.

    2015-01-01

    Axonal microtubule (MT) bundles crosslinked by microtubule-associated protein (MAP) tau are responsible for vital biological functions such as maintaining mechanical integrity and shape of the axon as well as facilitating axonal transport. Breaking and twisting of MTs have been previously observed in damaged undulated axons. Such breaking and twisting of MTs is suggested to cause axonal swellings that lead to axonal degeneration, which is known as “diffuse axonal injury”. In particular, overstretching and torsion of axons can potentially damage the axonal cytoskeleton. Following our previous studies on mechanical response of axonal MT bundles under uniaxial tension and compression, this work seeks to characterize the mechanical behavior of MT bundles under pure torsion as well as a combination of torsional and tensile loads using a coarse-grained computational model. In the case of pure torsion, a competition between MAP tau tensile and MT bending energies is observed. After three turns, a transition occurs in the mechanical behavior of the bundle that is characterized by its diameter shrinkage. Furthermore, crosslink spacing is shown to considerably influence the mechanical response, with larger MAP tau spacing resulting in a higher rate of turns. Therefore, MAP tau crosslinking of MT filaments protects the bundle from excessive deformation. Simultaneous application of torsion and tension on MT bundles is shown to accelerate bundle failure, compared to pure tension experiments. MAP tau proteins fail in clusters of 10–100 elements located at the discontinuities or the ends of MT filaments. This failure occurs in a stepwise fashion, implying gradual accumulation of elastic tensile energy in crosslinks followed by rupture. Failure of large groups of interconnecting MAP tau proteins leads to detachment of MT filaments from the bundle near discontinuities. This study highlights the importance of torsional loading in axonal damage after traumatic brain injury

  19. Frobenius splitting of projective toric bundles

    Indian Academy of Sciences (India)

    11

    Similarly, for each integer m ≥ 1 and n ≤ r, where r is the rank of E, the symmetric product SmE and wedge product ∧nE are also toric bundles. The associated Klyachko data of these toric bundles are the families of filtrations on the vector spaces SmE and ∧nE described as follows. (SmE)α(i) = { ∏. 1≤j≤m ej | ej ∈ E, 1 ...

  20. Flagellar Basal Body Structural Proteins FlhB, FliM, and FliY Are Required for Flagellar-Associated Protein Expression in Listeria monocytogenes

    Directory of Open Access Journals (Sweden)

    Changyong Cheng

    2018-02-01

    Full Text Available Listeria monocytogenes is a food-associated bacterium that is responsible for food-related illnesses worldwide. In the L. monocytogenes EGD-e genome, FlhB, FliM, and FliY (encoded by lmo0679, lmo0699, and lmo0700, respectively are annotated as putative flagella biosynthesis factors, but their functions remain unknown. To explore whether FlhB, FliM, and FliY are involved in Listeria flagella synthesis, we constructed flhB, fliM, fliY, and other flagellar-related gene deletion mutants using a homologous recombination strategy. Then, we analyzed the motility, flagella synthesis, and protein expression of these mutant strains. Motility and flagella synthesis were completely abolished in the absence of flhB, fliM, or fliY. These impaired phenotypes were fully restored in the complemented strains CΔflhB, CΔfliM, and CΔfliY. The transcriptional levels of flagellar-related genes, including flaA, fliM, fliY, lmo0695, lmo0698, fliI, and fliS, were downregulated markedly in the absence of flhB, fliM, or fliY. Deletion of flhB resulted in the complete abolishment of FlaA expression, while it decreased FliM and FliY expression. The expression of FlaA was abolished completely in the absence of fliM or fliY. No significant changes were found in the expression of FlhF and two flagella synthesis regulatory factors, MogR and GmaR. We demonstrate for the first time that FlhB, FliM, and FliY not only mediate Listeria motility, but also are involved in regulating flagella synthesis. This study provides novel insights that increase our understanding of the roles played by FlhB, FliM, and FliY in the flagellar type III secretion system in L. monocytogenes.

  1. Buckling behavior of individual and bundled microtubules.

    Science.gov (United States)

    Soheilypour, Mohammad; Peyro, Mohaddeseh; Peter, Stephen J; Mofrad, Mohammad R K

    2015-04-07

    As the major structural constituent of the cytoskeleton, microtubules (MTs) serve a variety of biological functions that range from facilitating organelle transport to maintaining the mechanical integrity of the cell. Neuronal MTs exhibit a distinct configuration, hexagonally packed bundles of MT filaments, interconnected by MT-associated protein (MAP) tau. Building on our previous work on mechanical response of axonal MT bundles under uniaxial tension, this study is focused on exploring the compression scenarios. Intracellular MTs carry a large fraction of the compressive loads sensed by the cell and therefore, like any other column-like structure, are prone to substantial bending and buckling. Various biological activities, e.g., actomyosin contractility and many pathological conditions are driven or followed by bending, looping, and buckling of MT filaments. The coarse-grained model previously developed in our lab has been used to study the mechanical behavior of individual and bundled in vivo MT filaments under uniaxial compression. Both configurations show tip-localized, decaying, and short-wavelength buckling. This behavior highlights the role of the surrounding cytoplasm and MAP tau on MT buckling behavior, which allows MT filaments to bear much larger compressive forces. It is observed that MAP tau interconnections improve this effect by a factor of two. The enhanced ability of MT bundles to damp buckling waves relative to individual MT filaments, may be interpreted as a self-defense mechanism because it helps axonal MTs to endure harsher environments while maintaining their function. The results indicate that MT filaments in a bundle do not buckle simultaneously implying that the applied stress is not equally shared among the MT filaments, that is a consequence of the nonuniform distribution of MAP tau proteins along the bundle length. Furthermore, from a pathological perspective, it is observed that axonal MT bundles are more vulnerable to failure in

  2. Stability of Picard bundle over moduli space of stable vector bundles ...

    Indian Academy of Sciences (India)

    Springer Verlag Heidelberg #4 2048 1996 Dec 15 10:16:45

    E-mail: indranil@math.tifr.res.in; tomas@math.tifr.res.in. MS received 14 September 2000. Abstract. Answering a question of [BV] it is proved that the Picard bundle on the moduli space of stable vector bundles of rank two, on a Riemann surface of genus at least three, with fixed determinant of odd degree is stable. Keywords ...

  3. Stability of Picard bundle over moduli space of stable vector bundles ...

    Indian Academy of Sciences (India)

    Springer Verlag Heidelberg #4 2048 1996 Dec 15 10:16:45

    Stability of Picard bundle over moduli space of stable vector bundles of rank two over a curve. INDRANIL BISWAS and TOM ´AS L G ´OMEZ. School of Mathematics, Tata Institute of Fundamental Research, Homi Bhabha Road,. Mumbai 400 005, India. E-mail: indranil@math.tifr.res.in; tomas@math.tifr.res.in. MS received 14 ...

  4. Deformations of the generalised Picard bundle

    International Nuclear Information System (INIS)

    Biswas, I.; Brambila-Paz, L.; Newstead, P.E.

    2004-08-01

    Let X be a nonsingular algebraic curve of genus g ≥ 3, and let Mξ denote the moduli space of stable vector bundles of rank n ≥ 2 and degree d with fixed determinant ξ over X such that n and d are coprime. We assume that if g = 3 then n ≥ 4 and if g = 4 then n ≥ 3, and suppose further that n 0 , d 0 are integers such that n 0 ≥ 1 and nd 0 + n 0 d > nn 0 (2g - 2). Let E be a semistable vector bundle over X of rank n 0 and degree d 0 . The generalised Picard bundle W ξ (E) is by definition the vector bundle over M ξ defined by the direct image p M ξ *(U ξ x p X * E) where U ξ is a universal vector bundle over X x M ξ . We obtain an inversion formula allowing us to recover E from W ξ (E) and show that the space of infinitesimal deformations of W ξ (E) is isomorphic to H 1 (X, End(E)). This construction gives a locally complete family of vector bundles over M ξ parametrised by the moduli space M(n 0 ,d 0 ) of stable bundles of rank n 0 and degree d 0 over X. If (n 0 ,d 0 ) = 1 and W ξ (E) is stable for all E is an element of M(n 0 ,d 0 ), the construction determines an isomorphism from M(n 0 ,d 0 ) to a connected component M 0 of a moduli space of stable sheaves over M ξ . This applies in particular when n 0 = 1, in which case M 0 is isomorphic to the Jacobian J of X as a polarised variety. The paper as a whole is a generalisation of results of Kempf and Mukai on Picard bundles over J, and is also related to a paper of Tyurin on the geometry of moduli of vector bundles. (author)

  5. Polymorphism in Bacterial Flagella Suspensions

    Science.gov (United States)

    Schwenger, Walter J.

    Bacterial flagella are a type of biological polymer studied for its role in bacterial motility and the polymorphic transitions undertaken to facilitate the run and tumble behavior. The naturally rigid, helical shape of flagella gives rise to novel colloidal dynamics and material properties. This thesis studies methods in which the shape of bacterial flagella can be controlled using in vitro methods and the changes the shape of the flagella have on both single particle dynamics and bulk material properties. We observe individual flagellum in both the dilute and semidilute regimes to observe the effects of solvent condition on the shape of the filament as well as the effect the filament morphology has on reptation through a network of flagella. In addition, we present rheological measurements showing how the shape of filaments effects the bulk material properties of flagellar suspensions. We find that the individual particle dynamics in suspensions of flagella can vary with geometry from needing to reptate linearly via rotation for helical filaments to the prevention of long range diffusion for block copolymer filaments. Similarly, for bulk material properties of flagella suspensions, helical geometries show a dramatic enhancement in elasticity over straight filaments while block copolymers form an elastic gel without the aid of crosslinking agents.

  6. NIF laser bundle review. Final report

    International Nuclear Information System (INIS)

    Tietbohl, G.L.; Larson, D.W.; Erlandson, A.C.

    1995-01-01

    We performed additional bundle review effort subsequent to the completion of the preliminary report and are revising our original recommendations. We now recommend that the NIF baseline laser bundle size be changed to the 4x2 bundle configuration. There are several 4x2 bundle configurations that could be constructed at a cost similar to that of the baseline 4x12 (from $11M more to about $11M less than the baseline; unescalated, no contingency) and provide significant system improvements. We recommend that the building cost estimates (particularly for the in-line building options) be verified by an architect/engineer (A/E) firm knowledgeable about building design. If our cost estimates of the in-line building are accurate and therefore result in a change from the baseline U-shaped building layout, the acceptability of the in-line configuration must be reviewed from an operations viewpoint. We recommend that installation, operation, and maintenance of all laser components be reviewed to better determine the necessity of aisles, which add to the building cost significantly. The need for beam expansion must also be determined since it affects the type of bundle packing that can be used and increases the minimum laser bay width. The U-turn laser architecture (if proven viable) offers a reduction in building costs since this laser design is shorter than the baseline switched design and requires a shorter laser bay

  7. Adenine nucleotide metabolism and a role for AMP in modulating flagellar waveforms in mouse sperm.

    Science.gov (United States)

    Vadnais, Melissa L; Cao, Wenlei; Aghajanian, Haig K; Haig-Ladewig, Lisa; Lin, Angel M; Al-Alao, Osama; Gerton, George L

    2014-06-01

    While most ATP, the main energy source driving sperm motility, is derived from glycolysis and oxidative phosphorylation, the metabolic demands of the cell require the efficient use of power stored in high-energy phosphate bonds. In times of high energy consumption, adenylate kinase (AK) scavenges one ATP molecule by transphosphorylation of two molecules of ADP, simultaneously yielding one molecule of AMP as a by-product. Either ATP or ADP supported motility of detergent-modeled cauda epididymal mouse sperm, indicating that flagellar AKs are functional. However, the ensuing flagellar waveforms fueled by ATP or ADP were qualitatively different. Motility driven by ATP was rapid but restricted to the distal region of the sperm tail, whereas ADP produced slower and more fluid waves that propagated down the full flagellum. Characterization of wave patterns by tracing and superimposing the images of the flagella, quantifying the differences using digital image analysis, and computer-assisted sperm analysis revealed differences in the amplitude, periodicity, and propagation of the waves between detergent-modeled sperm treated with either ATP or ADP. Surprisingly, addition of AMP to the incubation medium containing ATP recapitulated the pattern of sperm motility seen with ADP alone. In addition to AK1 and AK2, which we previously demonstrated are present in outer dense fibers and mitochondrial sheath of the mouse sperm tail, we show that another AK, AK8, is present in a third flagellar compartment, the axoneme. These results extend the known regulators of sperm motility to include AMP, which may be operating through an AMP-activated protein kinase. © 2014 by the Society for the Study of Reproduction, Inc.

  8. Fibre bundle framework for quantum fault tolerance

    Science.gov (United States)

    Zhang, Lucy Liuxuan; Gottesman, Daniel

    2014-03-01

    We introduce a differential geometric framework for describing families of quantum error-correcting codes and for understanding quantum fault tolerance. In particular, we use fibre bundles and a natural projectively flat connection thereon to study the transformation of codewords under unitary fault-tolerant evolutions. We'll explain how the fault-tolerant logical operations are given by the monodromy group for the bundles with projectively flat connection, which is always discrete. We will discuss the construction of the said bundles for two examples of fault-tolerant families of operations, the string operators in the toric code and the qudit transversal gates. This framework unifies topological fault tolerance and fault tolerance based on transversal gates, and is expected to apply for all unitary quantum fault-tolerant protocols.

  9. Flagellar expression in clinical isolates of non-typeable Haemophilus influenzae.

    Science.gov (United States)

    Carabarin-Lima, Alejandro; Lozano-Zarain, Patricia; Castañeda-Lucio, Miguel; Martínez de la Peña, Claudia Fabiola; Martinez-Garcia, Julieta; Flores, Norarizbeth Lara; Cruz, Elías Campos de la; González-Posos, Sirenia; Rocha-Gracia, Rosa Del Carmen

    2017-05-01

    Haemophilus influenzae is a commensal organism found in the upper respiratory tract of humans. When H. influenzae becomes a pathogen, these bacteria can move out of their commensal niche and cause multiple respiratory tract diseases such as otitis media, sinusitis, conjunctivitis and bronchitis in children, and chronic obstructive pulmonary disease in adults. However, H. influenzae is currently considered a non-flagellate bacterium. In this study, 90 clinical isolates of H. influenzae strains (typeable and non-typeable) showed different degrees of the swarm-motility phenotype in vitro.Keys findings. One of these strains, NTHi BUAP96, showed the highest motility rate and its flagella were revealed using transmission electron microscopy and Ryu staining. Moreover, the flagellar genes fliC and flgH exhibited high homology with those of Actinobacillus pleuropneumoniae, Escherichia coli and Shigella flexneri. Furthermore, Western blot analysis, using anti-flagellin heterologous antibodies from E. coli, demonstrated cross-reaction with a protein present in NTHi BUAP96. This study provides, for the first time, information on flagellar expression in H. influenzae, representing an important finding related to its evolution and pathogenic potential.

  10. Nonlinear instability in flagellar dynamics: a novel modulation mechanism in sperm migration?

    KAUST Repository

    Gadelha, H.

    2010-05-12

    Throughout biology, cells and organisms use flagella and cilia to propel fluid and achieve motility. The beating of these organelles, and the corresponding ability to sense, respond to and modulate this beat is central to many processes in health and disease. While the mechanics of flagellum-fluid interaction has been the subject of extensive mathematical studies, these models have been restricted to being geometrically linear or weakly nonlinear, despite the high curvatures observed physiologically. We study the effect of geometrical nonlinearity, focusing on the spermatozoon flagellum. For a wide range of physiologically relevant parameters, the nonlinear model predicts that flagellar compression by the internal forces initiates an effective buckling behaviour, leading to a symmetry-breaking bifurcation that causes profound and complicated changes in the waveform and swimming trajectory, as well as the breakdown of the linear theory. The emergent waveform also induces curved swimming in an otherwise symmetric system, with the swimming trajectory being sensitive to head shape-no signalling or asymmetric forces are required. We conclude that nonlinear models are essential in understanding the flagellar waveform in migratory human sperm; these models will also be invaluable in understanding motile flagella and cilia in other systems.

  11. Bacterial Keratitis

    Science.gov (United States)

    ... Español Eye Health / Eye Health A-Z Bacterial Keratitis Sections What Is Bacterial Keratitis? Bacterial Keratitis Symptoms ... Lens Care Bacterial Keratitis Treatment What Is Bacterial Keratitis? Leer en Español: ¿Qué Es la Queratitis Bacteriana? ...

  12. A note on the tangent bundle of G/P

    Indian Academy of Sciences (India)

    . 39–50. [3] Donaldson S K, Infinite determinants, stable bundles, and curvature, Duke Math. J. 54. (1987) 231–247. [4] Kobayashi S, Differential geometry of complex vector bundles (NJ: Princeton University. Press, Princeton; Tokyo: Iwanami ...

  13. Vibrations in bundles with cross flows

    International Nuclear Information System (INIS)

    Gibert, R.J.; Villard, B.; Sagner, V.

    1979-01-01

    The studies just presented provide much information on the aero and hydroelastic phenomena encountered in the bundles with cross flows, particularly on the lock-in phenomena and the aeroelastic instability for which a tabulation of the typical constant has been made [fr

  14. Meromorphic connections on vector bundles over curves

    Indian Academy of Sciences (India)

    Descartes,. 67084 Strasbourg Cedex, France. *Correspond author. E-mail: indranil@math.tifr.res.in; heu@math.unistra.fr. MS received 17 July 2013; revised 20 October 2013. Abstract. We give a criterion for filtered vector bundles over curves to admit a ...

  15. Abelian conformal field theory and determinant bundles

    DEFF Research Database (Denmark)

    Andersen, Jørgen Ellegaard; Ueno, K.

    2007-01-01

    are up to a scale the same as the curvature of the connections constructed in [14, 16]. We study the sewing construction for nodal curves and its explicit relation to the constructed connections. Finally we construct preferred holomorphic sections of these line bundles and analyze their behaviour near...

  16. Optimization of a bundle divertor for FED

    International Nuclear Information System (INIS)

    Hively, L.M.; Rothe, K.E.; Minkoff, M.

    1982-01-01

    Optimal double-T bundle divertor configurations have been obtained for the Fusion Engineering Device (FED). On-axis ripple is minimized, while satisfying a series of engineering constraints. The ensuing non-linear optimization problem is solved via a sequence of quadratic programming subproblems, using the VMCON algorithm. The resulting divertor designs are substantially improved over previous configurations

  17. Jacobi bundles and the BFV-complex

    Czech Academy of Sciences Publication Activity Database

    Le, Hong-Van; Tortorella, A. G.; Vitagliano, L.

    2017-01-01

    Roč. 121, November (2017), s. 347-377 ISSN 0393-0440 Institutional support: RVO:67985840 Keywords : Jacobi manifold * Jacobi bundle * coisotropic submanifolds Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 0.819, year: 2016 http://www.sciencedirect.com/science/article/pii/S0393044017301948

  18. Irradiation behavior of Phenix fuel pin bundles

    International Nuclear Information System (INIS)

    Marbach, G.; Millet, P.; Blanchard, P.; Huillery, R.

    1979-01-01

    A complete Phenix assembly was coated and cut into sections after irradiation. The examination of these sections reveals the effects of mechanical interaction in the bundle (ovalizing and inter-cladding contact). From the analysis of the sections through which the sodium passed, the irrigation of the fuel rods as a whole is homogeneous [fr

  19. Graph Bundling by Kernel Density Estimation

    NARCIS (Netherlands)

    Hurter, C.; Ersoy, O.; Telea, A.

    We present a fast and simple method to compute bundled layouts of general graphs. For this, we first transform a given graph drawing into a density map using kernel density estimation. Next, we apply an image sharpening technique which progressively merges local height maxima by moving the convolved

  20. Functional aspects of His bundle physiology and pathophysiology: Clinical implications.

    Science.gov (United States)

    Scherlag, Benjamin J; Lazzara, Ralph

    In this review we present evidence from many experimental studies which challenge the concept of predestination of His bundle fibers. Using both intra- and extracellular His bundle pacing in the context of atrio-ventricular block and the development of bundle branch blocks these experimental studies provide the underlying mechanisms for the recent clinical findings showing the benefits of permanent His bundle pacing. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Fiber bundles in non-relativistic quantum mechanics

    International Nuclear Information System (INIS)

    Moylan, P.

    1979-11-01

    The problem of describing a quantum-mechanical system with symmetry by a fiber bundle is considered. The quantization of a fiber bundle is introduced. Fiber bundles for the Kepler problem and the rotator are constructed. The fiber bundle concept provides a new model for a physical system: it provides a model for an elementary particle with extension having integral values of spin. 5 figures

  2. Interplanetary Overlay Network Bundle Protocol Implementation

    Science.gov (United States)

    Burleigh, Scott C.

    2011-01-01

    The Interplanetary Overlay Network (ION) system's BP package, an implementation of the Delay-Tolerant Networking (DTN) Bundle Protocol (BP) and supporting services, has been specifically designed to be suitable for use on deep-space robotic vehicles. Although the ION BP implementation is unique in its use of zero-copy objects for high performance, and in its use of resource-sensitive rate control, it is fully interoperable with other implementations of the BP specification (Internet RFC 5050). The ION BP implementation is built using the same software infrastructure that underlies the implementation of the CCSDS (Consultative Committee for Space Data Systems) File Delivery Protocol (CFDP) built into the flight software of Deep Impact. It is designed to minimize resource consumption, while maximizing operational robustness. For example, no dynamic allocation of system memory is required. Like all the other ION packages, ION's BP implementation is designed to port readily between Linux and Solaris (for easy development and for ground system operations) and VxWorks (for flight systems operations). The exact same source code is exercised in both environments. Initially included in the ION BP implementations are the following: libraries of functions used in constructing bundle forwarders and convergence-layer (CL) input and output adapters; a simple prototype bundle forwarder and associated CL adapters designed to run over an IPbased local area network; administrative tools for managing a simple DTN infrastructure built from these components; a background daemon process that silently destroys bundles whose time-to-live intervals have expired; a library of functions exposed to applications, enabling them to issue and receive data encapsulated in DTN bundles; and some simple applications that can be used for system checkout and benchmarking.

  3. Ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides (Dinophyceae) with reference to the apical groove and Flagellar apparatus.

    Science.gov (United States)

    Iwataki, Mitsunori; Hansen, Gert; Moestrup, Øjvind; Matsuoka, Kazumi

    2010-01-01

    The external and internal ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides Margalef has been examined with special reference to the apical groove and three-dimensional structure of the flagellar apparatus. The apical groove is U-shaped and connected to the anterior sulcal extension on the dorsal side of the epicone. The eyespot is located dorsally and composed of two layers of globules situated within the chloroplast. A narrow invagination of the plasma membrane is associated with the eyespot. The nuclear envelope has normal nuclear pores similar to other eukaryotes but different from the Gymnodinium group with diagnostic nuclear chambers. The longitudinal and transverse basal bodies are separated by approximately 0.5-1.0 microm and interconnected directly by a striated basal body connective and indirectly by microtubular and fibrous structures. Characteristic features of the flagellar apparatus are as follows: (1) a nuclear extension projects to the R1 (longitudinal microtubular root) and is connected to the root by thin fibrous material; (2) fibrillar structures are associated with the longitudinal and transverse flagellar canal; and (3) a striated ventral connective extends toward the posterior end of the cell along the longitudinal flagellar canal. We conclude, based on both morphological and molecular evidence, that Cochlodinium is only distantly related to Gymnodinium.

  4. Turkish and Native English Academic Writers' Use of Lexical Bundles

    Science.gov (United States)

    Öztürk, Yusuf; Köse, Gül Durmusoglu

    2016-01-01

    Lexical bundles such as "on the other hand" and "as a result of" are extremely common and important in academic discourse. The appropriate use of lexical bundles typical of a specific academic discipline is important for writers and the absence of such bundles may not sound fluent and native-like. Recent studies (e.g. Adel…

  5. Compactifications of reductive groups as moduli stacks of bundles

    DEFF Research Database (Denmark)

    Martens, Johan; Thaddeus, Michael

    Let G be a reductive group. We introduce the moduli problem of "bundle chains" parametrizing framed principal G-bundles on chains of lines. Any fan supported in a Weyl chamber determines a stability condition on bundle chains. Its moduli stack provides an equivariant toroidal compactification of G...

  6. Quillen bundle and geometric prequantization of non-abelian ...

    Indian Academy of Sciences (India)

    prequantum line bundle whose curvature is proportional to this symplectic form. The prequantum ..... The fiber over Ua/G is the equivalence class of this fiber. Like this we can define the line bundle on A/G. 3.2 Quillen metric. Using the Hermitian structure on E (the vector bundle on the Riemann surface ) and therefore the ...

  7. Quillen bundle and geometric prequantization of non-abelian ...

    Indian Academy of Sciences (India)

    In this paper we prequantize the moduli space of non-abelian vortices. We explicitly calculate the symplectic form arising from 2 metric and we construct a prequantum line bundle whose curvature is proportional to this symplectic form. The prequantum line bundle turns out to be Quillen's determinant line bundle with a ...

  8. Bundling of harvesting residues and whole-trees and the treatment of bundles; Hakkuutaehteiden ja kokopuiden niputus ja nippujen kaesittely

    Energy Technology Data Exchange (ETDEWEB)

    Kaipainen, H.; Seppaenen, V.; Rinne, S.

    1996-12-31

    The conditions on which the bundling of the harvesting residues from spruce regeneration fellings would become profitable were studied. The calculations showed that one of the most important features was sufficient compaction of the bundle, so that the portion of the wood in the unit volume of the bundle has to be more than 40 %. The tests showed that the timber grab loader of farm tractor was insufficient for production of dense bundles. The feeding and compression device of the prototype bundler was constructed in the research and with this device the required density was obtained.The rate of compaction of the dry spruce felling residues was about 40 % and that of the fresh residues was more than 50 %. The comparison between the bundles showed that the calorific value of the fresh bundle per unit volume was nearly 30 % higher than that of the dry bundle. This means that the treatment of the bundles should be done of fresh felling residues. Drying of the bundles succeeded well, and the crushing and chipping tests showed that the processing of the bundles at the plant is possible. The treatability of the bundles was also excellent. By using the prototype, developed in the research, it was possible to produce a bundle of the fresh spruce harvesting residues, the diameter of which was about 50 cm and the length about 3 m, and the rate of compaction over 50 %. By these values the reduction target of the costs is obtainable

  9. Triviality and Split of Vector Bundles on Rationally Connected Varieties

    OpenAIRE

    Pan, Xuanyu

    2013-01-01

    In this paper, we give a simple proof of a triviality criterion due to I.Biswas and J.Pedro and P.Dos Santos. We also prove a vector bundle on a homogenous space is trivial if and only if the restrictions of the vector bundle to Schubert lines are trivial. Using this result and Chern classes of vector bundles, we give a general criterion of a uniform vector bundle on a homogenous space to be splitting. As an application, we prove a uniform vector bundle on classical Grassmannians and quadrics...

  10. Multiple large filament bundles observed in Caulobacter crescentus by electron cryotomography

    DEFF Research Database (Denmark)

    Briegel, A; Dias, DP; Li, Z

    2006-01-01

    While the absence of any cytoskeleton was once recognized as a distinguishing feature of prokaryotes, it is now clear that a number of different bacterial proteins do form filaments in vivo. Despite the critical roles these proteins play in cell shape, genome segregation and cell division......, molecular mechanisms have remained obscure in part for lack of electron microscopy-resolution images where these filaments can be seen acting within their cellular context. Here, electron cryotomography was used to image the widely studied model prokaryote Caulobacter crescentus in an intact, near......-native state, producing three-dimensional reconstructions of these cells with unprecedented clarity and fidelity. We observed many instances of large filament bundles in various locations throughout the cell and at different stages of the cell cycle. The bundles appear to fall into four major classes based...

  11. Out of pile testing of the PHWR fuel bundles

    International Nuclear Information System (INIS)

    Mahender Dev; Raghunathan, S.; Agarwal, G.K.; Patel, R.J.; Agarwal, R.G.

    2002-01-01

    In PHWRs fuel bundle resides in the form of a string in the coolant channels. These fuel bundles are required to be replaced periodically with the help of fuelling machine and spent fuel is discharged to the spent-fuel bay through fuel transfer system. During complete refuelling operation, and during residence in channel fuel bundle experiences various kinds of loads like drag force, impact force, force applied by Fuelling Machine ram and force applied by various actuators in fuel transfer system. These fuel bundles are manufactured indigenously and require out of pile testing for qualification of design as well as manufacturing process. In 220 MWe PHWRs, 19-element split spacer fuel bundle is used whereas in 500 MWe PHWRs 37-element fuel bundle will be used. A comprehensive programme was conducted to generate, basic data like estimation of loads coming on fuel bundles, experimental data generation about friction factor and pressure drop and carrying out of pile testing of 19-element fuel bundles in Integral Thermal Facility at Hall-7. The 37-element fuel bundles were tested in fuel locator test facility at simulated reactor conditions for pressure drop test, endurance test and cross flow test. The 37-element bundles have also been tested for flow-induced vibration during residence in the reactor. The paper describes the experimental techniques and setups, for simulating the reactor condition and determining the effect of those conditions on the fuel bundles. (author)

  12. A common assembly module in injectisome and flagellar type III secretion sorting platforms

    Science.gov (United States)

    Notti, Ryan Q.; Bhattacharya, Shibani; Lilic, Mirjana; Stebbins, C. Erec

    2015-05-01

    Translocating proteins across the double membrane of Gram-negative bacteria, type III secretion systems (T3SS) occur in two evolutionarily related forms: injectisomes, delivering virulence factors into host cells, and the flagellar system, secreting the polymeric filament used for motility. While both systems share related elements of a cytoplasmic sorting platform that facilitates the hierarchical secretion of protein substrates, its assembly and regulation remain unclear. Here we describe a module mediating the assembly of the sorting platform in both secretion systems, and elucidate the structural basis for segregation of homologous components among these divergent T3SS subtypes sharing a common cytoplasmic milieu. These results provide a foundation for the subtype-specific assembly of T3SS sorting platforms and will support further mechanistic analysis and anti-virulence drug design.

  13. CUBu: Universal Real-Time Bundling for Large Graphs.

    Science.gov (United States)

    van der Zwan, Matthew; Codreanu, Valeriu; Telea, Alexandru

    2016-12-01

    Visualizing very large graphs by edge bundling is a promising method, yet subject to several challenges: speed, clutter, level-of-detail, and parameter control. We present CUBu, a framework that addresses the above problems in an integrated way. Fully GPU-based, CUBu bundles graphs of up to a million edges at interactive framerates, being over 50 times faster than comparable state-of-the-art methods, and has a simple and intuitive control of bundling parameters. CUBu extends and unifies existing bundling techniques, offering ways to control bundle shapes, separate bundles by edge direction, and shade bundles to create a level-of-detail visualization that shows both the graph core structure and its details. We demonstrate CUBu on several large graphs extracted from real-life application domains.

  14. On stability of Kummer surfaces' tangent bundle

    International Nuclear Information System (INIS)

    Bozhkov, Y.D.

    1988-10-01

    In this paper we propose an explicit approximation of the Kaehler-Einstein-Calabi-Yau metric on the Kummer surfaces, which are manifolds of type K3. It is constructed by gluing 16 pieces of the Eguchi-Hanson metric and 16 pieces of the Euclidean metric. Two estimates on its curvature are proved. Then we prove an estimate on the first eigenvalue of a covariant differential operator of second order. This enables us to apply Taubes' iteration procedure to obtain that there exists an anti-self-dual connection on the considered Kummer surface. In fact, it is a Hermitian-Einstein connection from which we conclude that Kummer surfaces' co-tangent bundle is stable and therefore their tangent bundle is stable too. (author). 40 refs

  15. Reactor application of an improved bundle divertor

    International Nuclear Information System (INIS)

    Yang, T.F.; Ruck, G.W.; Lee, A.Y.; Smeltzer, G.; Prevenslik, T.

    1978-11-01

    A Bundle Divertor was chosen as the impurity control and plasma exhaust system for the beam driven Demonstration Tokamak Hybrid Reactor - DTHR. In the context of a preconceptual design study of the reactor and associated facility a bundle divertor concept was developed and integrated into the reactor system. The overall system was found feasible and scalable for reactors with intermediate torodial field strengths on axis. The important design characteristics are: the overall average current density of the divertor coils is 0.73 kA for each tesla of toroidal field on axis; the divertor windings are made from super-conducting cables supported by steel structures and are designed to be maintainable; the particle collection assembly and auxiliary cryosorption vacuum pump are dual systems designed such that they can be reactivated alterntively to allow for continuous reactor operation; and the power requirement for energizing and operating the divertor is about 5 MW

  16. Tube bundle vibrations in transversal flow

    International Nuclear Information System (INIS)

    Gibert, R.J.; Sagner, M.

    1978-01-01

    This study gives important information concerning characteristic parameters about lock-in and whirling instability phenomena, in the case of tube arrays. The work is mainly an experimental one though models are also developed: 1) an equilateral pitch bundle (p=1,5 D with D=tube diameter) is tested. Tube damping (epsilon) and first eigenfrequency (f), flow velocity are explored in a large domain. Vibratory level of the tubes are measured and critical points are ploted on the fluidelastic parameters diagram. Several bundles with various usual pitches and arrangements (in line or staggered) are tested. Critical velocities are measured and the whirling instability characteristic coefficient is tabulated. A complementary experiment is made on tube rows with various pitches. This gives valuable informations concerning the look-in domain in VR and A'R diagram. Furthermore this puts in evidence the important effect of a frequency difference between two adjacent tubes on the whirling critical velocity

  17. Rod bundle burnout data and correlation comparisons

    International Nuclear Information System (INIS)

    Yoder, G.L.; Morris, D.G.; Mullins, C.B.

    1985-01-01

    Rod bundle burnout data from 30 steady-state and 3 transient tests were obtained from experiments performed in the Thermal Hydraulic Test Facility at the Oak Ridge National Laboratory. The tests covered a parameter range relevant to intact core reactor accidents ranging from large break to small break loss-ofcoolant conditions. Instrumentation within the 64-rod test section indicated that burnout occurred over an axial range within the bundle. The distance from the point where the first dry rod was detected to the point where all rods were dry was up to 60 cm in some of the tests. The burnout data should prove useful in developing new correlations for use in reactor thermalhydraulic codes. Evaluation of several existing critical heat flux correlations using the data show that three correlations, the Barnett, Bowring, and Katto correlations, perform similarly and correlate the data better than the Biasi correlation

  18. Fiber Bundle Model Under Heterogeneous Loading

    Science.gov (United States)

    Roy, Subhadeep; Goswami, Sanchari

    2018-03-01

    The present work deals with the behavior of fiber bundle model under heterogeneous loading condition. The model is explored both in the mean-field limit as well as with local stress concentration. In the mean field limit, the failure abruptness decreases with increasing order k of heterogeneous loading. In this limit, a brittle to quasi-brittle transition is observed at a particular strength of disorder which changes with k. On the other hand, the model is hardly affected by such heterogeneity in the limit where local stress concentration plays a crucial role. The continuous limit of the heterogeneous loading is also studied and discussed in this paper. Some of the important results related to fiber bundle model are reviewed and their responses to our new scheme of heterogeneous loading are studied in details. Our findings are universal with respect to the nature of the threshold distribution adopted to assign strength to an individual fiber.

  19. Type IIB flux compactifications on twistor bundles

    Energy Technology Data Exchange (ETDEWEB)

    Imaanpur, Ali, E-mail: aimaanpu@modares.ac.ir

    2014-02-05

    We construct a U(1) bundle over N(1,1), usually considered as an SO(3) bundle on CP{sup 2}, and show that type IIB supergravity can be consistently compactified over it. With the five form flux turned on, there is a solution for which the metric becomes Einstein. We further turn on 3-form fluxes and show that there is a one parameter family of solutions. In particular, there is a limiting solution of large 3-form fluxes for which two U(1) fiber directions of the metric shrink to zero size. We also discuss compactifications over N(1,1) to AdS{sub 3}. All solutions turn out to be non-supersymmetric.

  20. Thiol changes during epididymal maturation: a link to flagellar angulation in mouse spermatozoa?

    Science.gov (United States)

    Ijiri, T W; Vadnais, M L; Huang, A P; Lin, A M; Levin, L R; Buck, J; Gerton, G L

    2014-01-01

    Caput epididymal wild-type spermatozoa and cauda epididymal spermatozoa from mice null for the adenylyl cyclase Adcy10 gene are immotile unless stimulated by a membrane-permeant cyclic AMP analogue. Both types of spermatozoa exhibit flagellar angulation where the head folds back under these conditions. As sperm proteins undergo oxidation of sulfhydryl groups and the flagellum becomes more stable to external forces during epididymal transit, we hypothesized that ADCY10 is involved in a mechanism regulating flagellar stabilization. Although no differences were observed in global sulfhydryl status between caput and cauda epididymal spermatozoa from wild-type or Adcy10-null mice, two-dimensional fluorescence difference gel electrophoresis was performed to identify specific mouse sperm proteins containing sulfhydryl groups that became oxidized during epididymal maturation. A-kinase anchor protein 4, fatty acid-binding protein 9 (FABP9), glutathione S-transferase mu 5 and voltage-dependent anion channel 2 exhibited changes in thiol status between caput and cauda epididymal spermatozoa. The level and thiol status of each of these proteins were quantified in wild-type and Adcy10-null cauda epididymal spermatozoa. No differences in the abundance of any protein were observed; however, FABP9 in Adcy10-null cauda epididymal spermatozoa contained fewer disulfide bonds than wild-type sperm cells. In caput epididymal spermatozoa, FABP9 was detected in the cytoplasmic droplet, principal piece, midpiece, and non-acrosomal area of the head. However, in cauda epididymal spermatozoa, this protein localized to the perforatorium, post-acrosomal region and principal piece. Together, these results suggest that thiol changes during epididymal maturation have a role in the stabilization of the sperm flagellum. PMID:24254994

  1. Evidence for loss of a partial flagellar glycolytic pathway during trypanosomatid evolution.

    Directory of Open Access Journals (Sweden)

    Robert W B Brown

    Full Text Available Classically viewed as a cytosolic pathway, glycolysis is increasingly recognized as a metabolic pathway exhibiting surprisingly wide-ranging variations in compartmentalization within eukaryotic cells. Trypanosomatid parasites provide an extreme view of glycolytic enzyme compartmentalization as several glycolytic enzymes are found exclusively in peroxisomes. Here, we characterize Trypanosoma brucei flagellar proteins resembling glyceraldehyde-3-phosphate dehydrogenase (GAPDH and phosphoglycerate kinase (PGK: we show the latter associates with the axoneme and the former is a novel paraflagellar rod component. The paraflagellar rod is an essential extra-axonemal structure in trypanosomes and related protists, providing a platform into which metabolic activities can be built. Yet, bioinformatics interrogation and structural modelling indicate neither the trypanosome PGK-like nor the GAPDH-like protein is catalytically active. Orthologs are present in a free-living ancestor of the trypanosomatids, Bodo saltans: the PGK-like protein from B. saltans also lacks key catalytic residues, but its GAPDH-like protein is predicted to be catalytically competent. We discuss the likelihood that the trypanosome GAPDH-like and PGK-like proteins constitute molecular evidence for evolutionary loss of a flagellar glycolytic pathway, either as a consequence of niche adaptation or the re-localization of glycolytic enzymes to peroxisomes and the extensive changes to glycolytic flux regulation that accompanied this re-localization. Evidence indicating loss of localized ATP provision via glycolytic enzymes therefore provides a novel contribution to an emerging theme of hidden diversity with respect to compartmentalization of the ubiquitous glycolytic pathway in eukaryotes. A possibility that trypanosome GAPDH-like protein additionally represents a degenerate example of a moonlighting protein is also discussed.

  2. Thiol changes during epididymal maturation: a link to flagellar angulation in mouse spermatozoa?

    Science.gov (United States)

    Ijiri, T W; Vadnais, M L; Huang, A P; Lin, A M; Levin, L R; Buck, J; Gerton, G L

    2014-01-01

    Caput epididymal wild-type spermatozoa and cauda epididymal spermatozoa from mice null for the adenylyl cyclase Adcy10 gene are immotile unless stimulated by a membrane-permeant cyclic AMP analogue. Both types of spermatozoa exhibit flagellar angulation where the head folds back under these conditions. As sperm proteins undergo oxidation of sulfhydryl groups and the flagellum becomes more stable to external forces during epididymal transit, we hypothesized that ADCY10 is involved in a mechanism regulating flagellar stabilization. Although no differences were observed in global sulfhydryl status between caput and cauda epididymal spermatozoa from wild-type or Adcy10-null mice, two-dimensional fluorescence difference gel electrophoresis was performed to identify specific mouse sperm proteins containing sulfhydryl groups that became oxidized during epididymal maturation. A-kinase anchor protein 4, fatty acid-binding protein 9 (FABP9), glutathione S-transferase mu 5 and voltage-dependent anion channel 2 exhibited changes in thiol status between caput and cauda epididymal spermatozoa. The level and thiol status of each of these proteins were quantified in wild-type and Adcy10-null cauda epididymal spermatozoa. No differences in the abundance of any protein were observed; however, FABP9 in Adcy10-null cauda epididymal spermatozoa contained fewer disulfide bonds than wild-type sperm cells. In caput epididymal spermatozoa, FABP9 was detected in the cytoplasmic droplet, principal piece, midpiece, and non-acrosomal area of the head. However, in cauda epididymal spermatozoa, this protein localized to the perforatorium, post-acrosomal region and principal piece. Together, these results suggest that thiol changes during epididymal maturation have a role in the stabilization of the sperm flagellum. © 2013 American Society of Andrology and European Academy of Andrology.

  3. Uncovering ecosystem service bundles through social preferences.

    Directory of Open Access Journals (Sweden)

    Berta Martín-López

    Full Text Available Ecosystem service assessments have increasingly been used to support environmental management policies, mainly based on biophysical and economic indicators. However, few studies have coped with the social-cultural dimension of ecosystem services, despite being considered a research priority. We examined how ecosystem service bundles and trade-offs emerge from diverging social preferences toward ecosystem services delivered by various types of ecosystems in Spain. We conducted 3,379 direct face-to-face questionnaires in eight different case study sites from 2007 to 2011. Overall, 90.5% of the sampled population recognized the ecosystem's capacity to deliver services. Formal studies, environmental behavior, and gender variables influenced the probability of people recognizing the ecosystem's capacity to provide services. The ecosystem services most frequently perceived by people were regulating services; of those, air purification held the greatest importance. However, statistical analysis showed that socio-cultural factors and the conservation management strategy of ecosystems (i.e., National Park, Natural Park, or a non-protected area have an effect on social preferences toward ecosystem services. Ecosystem service trade-offs and bundles were identified by analyzing social preferences through multivariate analysis (redundancy analysis and hierarchical cluster analysis. We found a clear trade-off among provisioning services (and recreational hunting versus regulating services and almost all cultural services. We identified three ecosystem service bundles associated with the conservation management strategy and the rural-urban gradient. We conclude that socio-cultural preferences toward ecosystem services can serve as a tool to identify relevant services for people, the factors underlying these social preferences, and emerging ecosystem service bundles and trade-offs.

  4. Uncovering ecosystem service bundles through social preferences.

    Science.gov (United States)

    Martín-López, Berta; Iniesta-Arandia, Irene; García-Llorente, Marina; Palomo, Ignacio; Casado-Arzuaga, Izaskun; Amo, David García Del; Gómez-Baggethun, Erik; Oteros-Rozas, Elisa; Palacios-Agundez, Igone; Willaarts, Bárbara; González, José A; Santos-Martín, Fernando; Onaindia, Miren; López-Santiago, Cesar; Montes, Carlos

    2012-01-01

    Ecosystem service assessments have increasingly been used to support environmental management policies, mainly based on biophysical and economic indicators. However, few studies have coped with the social-cultural dimension of ecosystem services, despite being considered a research priority. We examined how ecosystem service bundles and trade-offs emerge from diverging social preferences toward ecosystem services delivered by various types of ecosystems in Spain. We conducted 3,379 direct face-to-face questionnaires in eight different case study sites from 2007 to 2011. Overall, 90.5% of the sampled population recognized the ecosystem's capacity to deliver services. Formal studies, environmental behavior, and gender variables influenced the probability of people recognizing the ecosystem's capacity to provide services. The ecosystem services most frequently perceived by people were regulating services; of those, air purification held the greatest importance. However, statistical analysis showed that socio-cultural factors and the conservation management strategy of ecosystems (i.e., National Park, Natural Park, or a non-protected area) have an effect on social preferences toward ecosystem services. Ecosystem service trade-offs and bundles were identified by analyzing social preferences through multivariate analysis (redundancy analysis and hierarchical cluster analysis). We found a clear trade-off among provisioning services (and recreational hunting) versus regulating services and almost all cultural services. We identified three ecosystem service bundles associated with the conservation management strategy and the rural-urban gradient. We conclude that socio-cultural preferences toward ecosystem services can serve as a tool to identify relevant services for people, the factors underlying these social preferences, and emerging ecosystem service bundles and trade-offs.

  5. Uncovering Ecosystem Service Bundles through Social Preferences

    Science.gov (United States)

    Martín-López, Berta; Iniesta-Arandia, Irene; García-Llorente, Marina; Palomo, Ignacio; Casado-Arzuaga, Izaskun; Amo, David García Del; Gómez-Baggethun, Erik; Oteros-Rozas, Elisa; Palacios-Agundez, Igone; Willaarts, Bárbara; González, José A.; Santos-Martín, Fernando; Onaindia, Miren; López-Santiago, Cesar; Montes, Carlos

    2012-01-01

    Ecosystem service assessments have increasingly been used to support environmental management policies, mainly based on biophysical and economic indicators. However, few studies have coped with the social-cultural dimension of ecosystem services, despite being considered a research priority. We examined how ecosystem service bundles and trade-offs emerge from diverging social preferences toward ecosystem services delivered by various types of ecosystems in Spain. We conducted 3,379 direct face-to-face questionnaires in eight different case study sites from 2007 to 2011. Overall, 90.5% of the sampled population recognized the ecosystem’s capacity to deliver services. Formal studies, environmental behavior, and gender variables influenced the probability of people recognizing the ecosystem’s capacity to provide services. The ecosystem services most frequently perceived by people were regulating services; of those, air purification held the greatest importance. However, statistical analysis showed that socio-cultural factors and the conservation management strategy of ecosystems (i.e., National Park, Natural Park, or a non-protected area) have an effect on social preferences toward ecosystem services. Ecosystem service trade-offs and bundles were identified by analyzing social preferences through multivariate analysis (redundancy analysis and hierarchical cluster analysis). We found a clear trade-off among provisioning services (and recreational hunting) versus regulating services and almost all cultural services. We identified three ecosystem service bundles associated with the conservation management strategy and the rural-urban gradient. We conclude that socio-cultural preferences toward ecosystem services can serve as a tool to identify relevant services for people, the factors underlying these social preferences, and emerging ecosystem service bundles and trade-offs. PMID:22720006

  6. Twisted vector bundles on pointed nodal curves

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    other hand, as shown in [6], the notion of Gieseker vector bundles leads to the construction of the stack of stable maps into ..... residue field R/m = k. Let be a cyclic group of order e prime to the characteristic of k and let γ ∈ be a generator. Assume that acts on R such that the induced action on k is trivial. Let M be a trivial ...

  7. Principal bundles on the projective line

    Indian Academy of Sciences (India)

    M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22

    LetX be a complete nonsingular curve over the algebraic closurek ofk andGa reductive group over k. Let E → X be a principal G-bundle on X. E is said to be semistable if, for every reduction of structure group EP ⊂ E to a maximal parabolic subgroup P of G, we have degree EP (p) ≤ 0, where p is the Lie algebra of P and EP ...

  8. Meromorphic connections on vector bundles over curves

    Indian Academy of Sciences (India)

    satisfying the Leibniz rule which says that D(f ·s) = s ⊗df +f ·D(s) for any holomorphic function f ∈ OX(U) and any holomorphic section s of E|U , where U is any open subset of X. According to Weil's criterion, E admits a holomorphic connection if and only if E is a direct sum of indecomposable vector bundles of degree zero [1, ...

  9. Spanning forests and the vector bundle Laplacian

    OpenAIRE

    Kenyon, Richard

    2011-01-01

    The classical matrix-tree theorem relates the determinant of the combinatorial Laplacian on a graph to the number of spanning trees. We generalize this result to Laplacians on one- and two-dimensional vector bundles, giving a combinatorial interpretation of their determinants in terms of so-called cycle rooted spanning forests (CRSFs). We construct natural measures on CRSFs for which the edges form a determinantal process. ¶ This theory gives a natural generalization of the spanning tre...

  10. Bundling harvester; Harvennuspuun automaattisen nippukorjausharvesterin kehittaeminen

    Energy Technology Data Exchange (ETDEWEB)

    Koponen, K. [Eko-Log Oy, Kuopio (Finland)

    1997-12-01

    The starting point of the project was to design and construct, by taking the silvicultural point of view into account, a harvesting and processing system especially for energy-wood, containing manually driven bundling harvester, automating of the harvester, and automated loading. The equipment forms an ideal method for entrepreneur`s-line harvesting. The target is to apply the system also for owner`s-line harvesting. The profitability of the system promotes the utilisation of the system in both cases. The objectives of the project were: to construct a test equipment and prototypes for all the project stages, to carry out terrain and strain tests in order to examine the usability and durability, as well as the capacity of the machine, to test the applicability of the Eko-Log system in simultaneous harvesting of energy and pulp woods, and to start the marketing and manufacturing of the products. The basic problems of the construction of the bundling harvester have been solved using terrain-tests. The prototype machine has been shown to be operable. Loading of the bundles to form sufficiently economically transportable loads has been studied, and simultaneously, the branch-biomass has been tried to be utilised without loosing the profitability of transportation. The results have been promising, and will promote the profitable utilisation of wood-energy. (orig.)

  11. CRIS-a novel cAMP-binding protein controlling spermiogenesis and the development of flagellar bending.

    Directory of Open Access Journals (Sweden)

    Anke Miriam Krähling

    Full Text Available The second messengers cAMP and cGMP activate their target proteins by binding to a conserved cyclic nucleotide-binding domain (CNBD. Here, we identify and characterize an entirely novel CNBD-containing protein called CRIS (cyclic nucleotide receptor involved in sperm function that is unrelated to any of the other members of this protein family. CRIS is exclusively expressed in sperm precursor cells. Cris-deficient male mice are either infertile due to a lack of sperm resulting from spermatogenic arrest, or subfertile due to impaired sperm motility. The motility defect is caused by altered Ca(2+ regulation of flagellar beat asymmetry, leading to a beating pattern that is reminiscent of sperm hyperactivation. Our results suggest that CRIS interacts during spermiogenesis with Ca(2+-regulated proteins that--in mature sperm--are involved in flagellar bending.

  12. Influence of Bundle Diameter and Attachment Point on Kinematic Behavior in Double Bundle Anterior Cruciate Ligament Reconstruction Using Computational Model

    Directory of Open Access Journals (Sweden)

    Oh Soo Kwon

    2014-01-01

    Full Text Available A protocol to choose the graft diameter attachment point of each bundle has not yet been determined since they are usually dependent on a surgeon’s preference. Therefore, the influence of bundle diameters and attachment points on the kinematics of the knee joint needs to be quantitatively analyzed. A three-dimensional knee model was reconstructed with computed tomography images of a 26-year-old man. Based on the model, models of double bundle anterior cruciate ligament (ACL reconstruction were developed. The anterior tibial translations for the anterior drawer test and the internal tibial rotation for the pivot shift test were investigated according to variation of bundle diameters and attachment points. For the model in this study, the knee kinematics after the double bundle ACL reconstruction were dependent on the attachment point and not much influenced by the bundle diameter although larger sized anterior-medial bundles provided increased stability in the knee joint. Therefore, in the clinical setting, the bundle attachment point needs to be considered prior to the bundle diameter, and the current selection method of graft diameters for both bundles appears justified.

  13. Immunological reactions to Salmonella FlgK and FliD flagellar proteins by broiler sera

    Science.gov (United States)

    Background: Salmonella is the leading foodborne pathogen that causes human acute bacterial gastroenteritis worldwide. Chickens are considered as one of major reservoirs of this bacterium. Because the bacterial flagellum is involved in motility, adhesion, quorum sensing and other virulence activit...

  14. Analytical prediction of turbulent friction factor for a rod bundle

    International Nuclear Information System (INIS)

    Bae, Jun Ho; Park, Joo Hwan

    2011-01-01

    An analytical calculation has been performed to predict the turbulent friction factor in a rod bundle. For each subchannel constituting a rod bundle, the geometry parameters are analytically derived by integrating the law of the wall over each subchannel with the consideration of a local shear stress distribution. The correlation equations for a local shear stress distribution are supplied from a numerical simulation for each subchannel. The explicit effect of a subchannel shape on the geometry parameter and the friction factor is reported. The friction factor of a corner subchannel converges to a constant value, while the friction factor of a central subchannel steadily increases with a rod distance ratio. The analysis for a rod bundle shows that the friction factor of a rod bundle is largely affected by the characteristics of each subchannel constituting a rod bundle. The present analytic calculations well predict the experimental results from the literature with rod bundles in circular, hexagonal, and square channels.

  15. Trivalent Cation Induced Bundle Formation of Filamentous fd Phages.

    Science.gov (United States)

    Korkmaz Zirpel, Nuriye; Park, Eun Jin

    2015-09-01

    Bacteriophages are filamentous polyelectrolyte viral rods infecting only bacteria. In this study, we investigate the bundle formation of fd phages with trivalent cations having different ionic radii (Al(3+) , La(3+) and Y(3+) ) at various phage and counterion concentrations, and at varying bundling times. Aggregated phage bundles were detected at relatively low trivalent counterion concentrations (1 mM). Although 10 mM and 100 mM Y(3+) and La(3+) treatments formed larger and more intertwined phage bundles, Al(3+) and Fe(3+) treatments lead to the formation of networking filaments. Energy dispersive X-ray spectroscopy (EDX) analyses confirmed the presence of C, N and O peaks on densely packed phage bundles. Immunofluorescence labelling and ELISA analyses with anti-p8 antibodies showed the presence of phage filaments after bundling. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. A Tannakian approach to dimensional reduction of principal bundles

    Science.gov (United States)

    Álvarez-Cónsul, Luis; Biswas, Indranil; García-Prada, Oscar

    2017-08-01

    Let P be a parabolic subgroup of a connected simply connected complex semisimple Lie group G. Given a compact Kähler manifold X, the dimensional reduction of G-equivariant holomorphic vector bundles over X × G / P was carried out in Álvarez-Cónsul and García-Prada (2003). This raises the question of dimensional reduction of holomorphic principal bundles over X × G / P. The method of Álvarez-Cónsul and García-Prada (2003) is special to vector bundles; it does not generalize to principal bundles. In this paper, we adapt to equivariant principal bundles the Tannakian approach of Nori, to describe the dimensional reduction of G-equivariant principal bundles over X × G / P, and to establish a Hitchin-Kobayashi type correspondence. In order to be able to apply the Tannakian theory, we need to assume that X is a complex projective manifold.

  17. Inhibition of the Injectisome and Flagellar Type III Secretion Systems by INP1855 Impairs Pseudomonas aeruginosa Pathogenicity and Inflammasome Activation.

    OpenAIRE

    Anantharajah, Ahalieyah; Faure, Emmanuel; Buyck, Julien; Sundin, Charlotta; Lindmark, Tuulikki; Mecsas, Joan; Yahr, Timothy L; Tulkens, Paul M.; Mingeot-Leclercq, Marie-Paule; Guery, Benoît; Van Bambeke, Françoise

    2016-01-01

    With the rise of multidrug resistance, Pseudomonas aeruginosa infections require alternative therapeutics. The injectisome (iT3SS) and flagellar (fT3SS) type III secretion systems are 2 virulence factors associated with poor clinical outcomes. iT3SS translocates toxins, rod, needle, or regulator proteins, and flagellin into the host cell cytoplasm and causes cytotoxicity and NLRC4-dependent inflammasome activation, which induces interleukin 1β (IL-1β) release and reduces interleukin 17 (IL-17...

  18. Extensive flagellar remodeling during the complex life cycle of &ITParatrypanosoma&IT, an early-branching trypanosomatid

    Czech Academy of Sciences Publication Activity Database

    Skalický, Tomáš; Dobáková, Eva; Wheeler, R. J.; Tesařová, Martina; Flegontov, P.; Jirsová, Dagmar; Votýpka, Jan; Yurchenko, V.; Ayala, F. J.; Lukeš, Julius

    2017-01-01

    Roč. 114, č. 44 (2017), s. 11757-11762 ISSN 0027-8424 R&D Projects: GA ČR(CZ) GA14-23986S; GA MŠk LL1601; GA MŠk(CZ) LM2015062 Institutional support: RVO:60077344 Keywords : trypanosomatid * evolution * flagellar remodeling * haptomonads * cytostome Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Biology (theoretical, mathematical, thermal, cryobiology, biological rhythm), Evolutionary biology Impact factor: 9.661, year: 2016

  19. Bacterial meningitis

    NARCIS (Netherlands)

    Roos, Karen L.; van de Beek, Diederik

    2010-01-01

    Bacterial meningitis is a neurological emergency. Empiric antimicrobial and adjunctive therapy should be initiated as soon as a single set of blood cultures has been obtained. Clinical signs suggestive of bacterial meningitis include fever, headache, meningismus, vomiting, photophobia, and an

  20. Global properties of systems quantized via bundles

    International Nuclear Information System (INIS)

    Doebner, H.D.; Werth, J.E.

    1978-03-01

    Take a smooth manifold M and a Lie algebra action (g-ation) theta on M as the geometrical arena of a physical system moving on M with momenta given by theta. It is proposed to quantize the system with a Mackey-like method via the associated vector bundle xisub(rho) of a principal bundle xi=(P,π,M,H) with model dependent structure group H and with g-action phi on P lifted from theta on M. This (quantization) bundle xisub(rho) gives the Hilbert space equal to L 2 (xisub(rho),ω) of the system as the linear space of sections in xisub(rho) being square integrable with respect to a volume form ω on M; the usual position operators are obtained; phi leads to a vector field representation D(phisub(rho),theta) of g in an hence Hilbert space to momentum operators. So Hilbert space carries the quantum kinematics. In this quantuzation the physically important connection between geometrical properties of the system, e.g. quasi-completeness of theta and G-maximality of phisub(rho), and global properties of its quantized kinematics, e.g. skew-adjointness of the momenta and integrability of D(phisub(rho), theta) can easily be studied. The relation to Nelson's construction of a skew-adjoint non-integrable Lie algebra representation and to Palais' local G-action is discussed. Finally the results are applied to actions induced by coverings as examples of non-maximal phisub(rho) on Esub(rho) lifted from maximal theta on M which lead to direct consequences for the corresponding quantum kinematics

  1. Historical dynamics in ecosystem service bundles.

    Science.gov (United States)

    Renard, Delphine; Rhemtulla, Jeanine M; Bennett, Elena M

    2015-10-27

    Managing multiple ecosystem services (ES), including addressing trade-offs between services and preventing ecological surprises, is among the most pressing areas for sustainability research. These challenges require ES research to go beyond the currently common approach of snapshot studies limited to one or two services at a single point in time. We used a spatiotemporal approach to examine changes in nine ES and their relationships from 1971 to 2006 across 131 municipalities in a mixed-use landscape in Quebec, Canada. We show how an approach that incorporates time and space can improve our understanding of ES dynamics. We found an increase in the provision of most services through time; however, provision of ES was not uniformly enhanced at all locations. Instead, each municipality specialized in providing a bundle (set of positively correlated ES) dominated by just a few services. The trajectory of bundle formation was related to changes in agricultural policy and global trends; local biophysical and socioeconomic characteristics explained the bundles' increasing spatial clustering. Relationships between services varied through time, with some provisioning and cultural services shifting from a trade-off or no relationship in 1971 to an apparent synergistic relationship by 2006. By implementing a spatiotemporal perspective on multiple services, we provide clear evidence of the dynamic nature of ES interactions and contribute to identifying processes and drivers behind these changing relationships. Our study raises questions about using snapshots of ES provision at a single point in time to build our understanding of ES relationships in complex and dynamic social-ecological systems.

  2. Hydrodynamic behavior of a bare rod bundle

    International Nuclear Information System (INIS)

    Bartzis, J.G.; Todreas, N.E.

    1977-06-01

    The temperature distribution within the rod bundle of a nuclear reactor is of major importance in nuclear reactor design. However temperature information presupposes knowledge of the hydrodynamic behavior of the coolant which is the most difficult part of the problem due to complexity of the turbulence phenomena. In the present work a 2-equation turbulence model--a strong candidate for analyzing actual three dimensional turbulent flows--has been used to predict fully developed flow of infinite bare rod bundle of various aspect ratios (P/D). The model has been modified to take into account anisotropic effects of eddy viscosity. Secondary flow calculations have been also performed although the model seems to be too rough to predict the secondary flow correctly. Heat transfer calculations have been performed to confirm the importance of anisotropic viscosity in temperature predictions. All numerical calculations for flow and heat have been performed by two computer codes based on the TEACH code. Experimental measurements of the distribution of axial velocity, turbulent axial velocity, turbulent kinetic energy and radial Reynolds stresses were performed in the developing and fully developed regions. A 2-channel Laser Doppler Anemometer working on the Reference mode with forward scattering was used to perform the measurements in a simulated interior subchannel of a triangular rod array with P/D = 1.124. Comparisons between the analytical results and the results of this experiment as well as other experimental data in rod bundle array available in literature are presented. The predictions are in good agreement with the results for the high Reynolds numbers

  3. Assembly mechanism for nuclear fuel bundles

    International Nuclear Information System (INIS)

    Long, J.W.; Flora, B.S.; Ford, K.L.

    1980-01-01

    The invention relates to a nuclear power reactor fuel bundle of the type wherein several rods are mounted in parallel array between two tie plates which secure the fuel rods in place and are maintained in assembled position by means of a number of tie rods secured to both of the end plates. Improved apparatus is provided for attaching the tie rods to the upper tie plate by the use of locking lugs fixed to rotatable sleeves which engage the upper tie plate. (auth)

  4. Thermal hydraulic stability experiments in rod bundle

    International Nuclear Information System (INIS)

    Enomoto, T.; Muto, S.; Ishizuka, T.; Tanabe, A.; Mitsutake, T.; Sakurai, M.

    1985-01-01

    Thermal hydraulic stability tests have been performed on electrically heated bundles to simulate Boiling Water Reactor (BWR) fuels in a parallel channel test-loop. The test facility used is for the study of the steady state and transient characteristics of various thermal hydraulic conditions encountered in BWR operation, such as flow- high power operation, abnormal transient conditions and post boiling transition, including thermal hydraulic stability. Moreover, steady state and transient void behavior can be measured using an additional test section for this facility

  5. Vector bundles on complex projective spaces

    CERN Document Server

    Okonek, Christian; Spindler, Heinz

    1980-01-01

    This expository treatment is based on a survey given by one of the authors at the Séminaire Bourbaki in November 1978 and on a subsequent course held at the University of Göttingen. It is intended to serve as an introduction to the topical question of classification of holomorphic vector bundles on complex projective spaces, and can easily be read by students with a basic knowledge of analytic or algebraic geometry. Short supplementary sections describe more advanced topics, further results, and unsolved problems.

  6. Bundling Products and Services Through Modularization Strategies

    DEFF Research Database (Denmark)

    Bask, Anu; Hsuan, Juliana; Rajahonka, Mervi

    2012-01-01

    Modularity has been recognized as a powerful tool in improving the efficiency and management of product design and manufacturing. However, the integrated view on covering both, product and service modularity for product-service systems (PSS), is under researched. Therefore, in this paper our...... objective is to contribute to the PSS modularity. Thus, we describe configurations of PSSs and the bundling of products and services through modularization strategies. So far there have not been tools to analyze and determine the correct combinations of degrees of product and service modularities....

  7. Real parabolic vector bundles over a real curve

    Indian Academy of Sciences (India)

    by Seshadri [4] and their moduli studied in [2]. Here we consider real vector bundles over a real curve and define parabolic structures on real vector bundles. By a real curve, we mean a pair (X,σX ), where X is a compact Riemann surface and. σX is an anti-holomorphic involution on X. A real vector bundle over a real curve ...

  8. Heat Transfer Analysis in Wire Bundles for Aerospace Vehicles

    Science.gov (United States)

    Rickman, S. L.; Iamello, C. J.

    2016-01-01

    Design of wiring for aerospace vehicles relies on an understanding of "ampacity" which refers to the current carrying capacity of wires, either, individually or in wire bundles. Designers rely on standards to derate allowable current flow to prevent exceedance of wire temperature limits due to resistive heat dissipation within the wires or wire bundles. These standards often add considerable margin and are based on empirical data. Commercial providers are taking an aggressive approach to wire sizing which challenges the conventional wisdom of the established standards. Thermal modelling of wire bundles may offer significant mass reduction in a system if the technique can be generalized to produce reliable temperature predictions for arbitrary bundle configurations. Thermal analysis has been applied to the problem of wire bundles wherein any or all of the wires within the bundle may carry current. Wire bundles present analytical challenges because the heat transfer path from conductors internal to the bundle is tortuous, relying on internal radiation and thermal interface conductance to move the heat from within the bundle to the external jacket where it can be carried away by convective and radiative heat transfer. The problem is further complicated by the dependence of wire electrical resistivity on temperature. Reduced heat transfer out of the bundle leads to higher conductor temperatures and, hence, increased resistive heat dissipation. Development of a generalized wire bundle thermal model is presented and compared with test data. The steady state heat balance for a single wire is derived and extended to the bundle configuration. The generalized model includes the effects of temperature varying resistance, internal radiation and thermal interface conductance, external radiation and temperature varying convective relief from the free surface. The sensitivity of the response to uncertainties in key model parameters is explored using Monte Carlo analysis.

  9. Early Results of Anatomic Double Bundle Anterior Cruciate Ligament Reconstruction

    OpenAIRE

    Demet Pepele

    2014-01-01

    Aim: The goal in anterior cruciate ligament reconstruction (ACLR) is to restore the normal anatomic structure and function of the knee. In the significant proportion of patients after the traditional single-bundle ACLR, complaints of instability still continue. Anatomic double bundle ACLR may provide normal kinematics in knees, much closer to the natural anatomy. The aim of this study is to clinically assess the early outcomes of our anatomical double bundle ACLR. Material and Method: In our ...

  10. Analytic convergence of harmonic metrics for parabolic Higgs bundles

    Science.gov (United States)

    Kim, Semin; Wilkin, Graeme

    2018-04-01

    In this paper we investigate the moduli space of parabolic Higgs bundles over a punctured Riemann surface with varying weights at the punctures. We show that the harmonic metric depends analytically on the weights and the stable Higgs bundle. This gives a Higgs bundle generalisation of a theorem of McOwen on the existence of hyperbolic cone metrics on a punctured surface within a given conformal class, and a generalisation of a theorem of Judge on the analytic parametrisation of these metrics.

  11. Loss of the lac operon contributes to Salmonella invasion of epithelial cells through derepression of flagellar synthesis.

    Science.gov (United States)

    Jiang, Lingyan; Ni, Zhiwei; Wang, Lei; Feng, Lu; Liu, Bin

    2015-03-01

    Salmonella, a genus that is closely related to Escherichia coli, includes many pathogens of humans and other animals. A notable feature that distinguishes Salmonella from E. coli is lactose negativity, because the lac operon is lost in most Salmonella genomes. Here, we expressed the lac operon in Salmonella enterica serovar Typhimurium and compared the virulence of the Lac(+) strain to that of the wild-type strain in a murine model, invasion assays, and macrophage replication assays. We showed that the Lac(+) strain is attenuated in vivo and the attenuation of virulence is caused by its defect in epithelial cell invasion. However, the invasion-defective phenotype is unrelated to lactose utilization. Through sequencing and the comparison of the transcriptome profile between the Lac(+) and wild-type strains during invasion, we found that most flagellar genes were markedly downregulated in the Lac(+) strain, while other genes associated with invasion, such as the majority of genes encoded in Salmonella pathogenicity island 1, were not differentially expressed. Moreover, we discovered that lacA is the major repressor of flagellar gene expression in the lac operon. In conclusion, these data demonstrate that the lac operon decreases Salmonella invasion of epithelial cells through repression of flagellar biosynthesis. As the ability to invade epithelial cells is a critical virulence determinant of Salmonella, our results provide important evidence that the loss of the lac operon contributes to the evolution of Salmonella pathogenicity.

  12. Genetical and functional investigation of fliC genes encoding flagellar serotype H4 in wildtype strains of Escherichia coli and in a laboratory E. coli K-12 strain expressing flagellar antigen type H48

    Directory of Open Access Journals (Sweden)

    Schaudinn Christoph

    2005-01-01

    Full Text Available Abstract Background Serotyping of O-(lipopolysaccharide and H-(flagellar antigens is a wideley used method for identification of pathogenic strains and clones of Escherichia coli. At present, 176 O- and 53 H-antigens are described for E. coli which occur in different combinations in the strains. The flagellar antigen H4 is widely present in E. coli strains of different O-serotypes and pathotypes and we have investigated the genetic relationship between H4 encoding fliC genes by PCR, nucleotide sequencing and expression studies. Results The complete nucleotide sequence of fliC genes present in E. coli reference strains U9-41 (O2:K1:H4 and P12b (O15:H17 was determined and both were found 99.3% (1043 of 1050 nucleotides identical in their coding sequence. A PCR/RFLP protocol was developed for typing of fliC-H4 strains and 88 E. coli strains reacting with H4 antiserum were investigated. Nucleotide sequencing of complete fliC genes of six E. coli strains which were selected based on serum agglutination titers, fliC-PCR genotyping and reference data revealed 96.6 to 100% identity on the amino acid level. The functional expression of flagellin encoded by fliC-H4 from strain U9-41 and from our strain P12b which is an H4 expressing variant type was investigated in the E. coli K-12 strain JM109 which encodes flagellar type H48. The fliC recombinant plasmid carrying JM109 strains reacted with both H4 and H48 specific antisera whereas JM109 reacted only with the H48 antiserum. By immunoelectron microscopy, we could show that the flagella made by the fliC-H4 recombinant plasmid carrying strain are constituted of H48 and H4 flagellins which are co-assembled into functional flagella. Conclusion The flagellar serotype H4 is encoded by closely related fliC genes present in serologically different types of E. coli strainswhich were isolated at different time periods and geographical locations. Our expression studies show for the first time, that flagellins of

  13. Discontinuous conduction in mouse bundle branches is caused by bundle-branch architecture

    NARCIS (Netherlands)

    van Veen, Toon A. B.; van Rijen, Harold V. M.; van Kempen, Marjan J. A.; Miquerol, Lucile; Opthof, Tobias; Gros, Daniel; Vos, Marc A.; Jongsma, Habo J.; de Bakker, Jacques M. T.

    2005-01-01

    Background - Recordings of the electrical activity of mouse bundle branches ( BBs) suggest reduced conduction velocity ( CV) in the midseptal compared with the proximal part of the BB. The present study was performed to elucidate the mechanism responsible for this slowing of conduction. Methods and

  14. Enthalpy and void distributions in subchannels of PHWR fuel bundles

    Energy Technology Data Exchange (ETDEWEB)

    Park, J. W.; Choi, H.; Rhee, B. W. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    Two different types of the CANDU fuel bundles have been modeled for the ASSERT-IV code subchannel analysis. From calculated values of mixture enthalpy and void fraction distribution in the fuel bundles, it is found that net buoyancy effect is pronounced in the central region of the DUPIC fuel bundle when compared with the standard CANDU fuel bundle. It is also found that the central region of the DUPIC fuel bundle can be cooled more efficiently than that of the standard fuel bundle. From the calculated mixture enthalpy distribution at the exit of the fuel channel, it is found that the mixture enthalpy and void fraction can be highest in the peripheral region of the DUPIC fuel bundle. On the other hand, the enthalpy and the void fraction were found to be highest in the central region of the standard CANDU fuel bundle at the exit of the fuel channel. This study shows that the subchannel analysis is very useful in assessing thermal behavior of the fuel bundle that could be used in CANDU reactors. 10 refs., 4 figs., 2 tabs. (Author)

  15. Experimental and numerical investigations of BWR fuel bundle inlet flow

    International Nuclear Information System (INIS)

    Hoashi, E; Morooka, S; Ishitori, T; Komita, H; Endo, T; Honda, H; Yamamoto, T; Kato, T; Kawamura, S

    2009-01-01

    We have been studying the mechanism of the flow pattern near the fuel bundle inlet of BWR using both flow visualization test and computational fluid dynamics (CFD) simulation. In the visualization test, both single- and multi-bundle test sections were used. The former test section includes only a corner orifice facing two support beams and the latter simulates 16 bundles surrounded by four beams. An observation window is set on the side of the walls imitating the support beams upstream of the orifices in both test sections. In the CFD simulation, as well as the visualization test, the single-bundle model is composed of one bundle with a corner orifice and the multi-bundle model is a 1/4 cut of the test section that includes 4 bundles with the following four orifices: a corner orifice facing the corner of the two neighboring support beams, a center orifice at the opposite side from the corner orifice, and two side orifices. Twin-vortices were observed just upstream of the corner orifice in the multi-bundle test as well as the single-bundle test. A single-vortex and a vortex filament were observed at the side orifice inlet and no vortex was observed at the center orifice. These flow patterns were also predicted in the CFD simulation using Reynolds Stress Model as a turbulent model and the results were in good agreement with the test results mentioned above. (author)

  16. Restriction Theorem for Principal bundles in Arbitrary Characteristic

    DEFF Research Database (Denmark)

    Gurjar, Sudarshan

    2015-01-01

    The aim of this paper is to prove two basic restriction theorem for principal bundles on smooth projective varieties in arbitrary characteristic generalizing the analogues theorems of Mehta-Ramanathan for vector bundles. More precisely, let G be a reductive algebraic group over an algebraically...... closed field k and let X be a smooth, projective variety over k together with a very ample line bundle O(1). The main result of the paper is that if E is a semistable (resp. stable) principal G-bundle on X w.r.t O(1), then the restriction of E to a general, high multi-degree, complete-intersection curve...

  17. The differential geometry of higher order jets and tangent bundles

    International Nuclear Information System (INIS)

    De Leon, M.; Rodrigues, P.R.

    1985-01-01

    This chapter is devoted to the study of basic geometrical notions required for the development of the main object of the text. Some facts about Jet theory are reviewed. A particular case of Jet manifolds is considered: the tangent bundle of higher order. It is shown that this jet bundle possesses in a canonical way a certain kind of geometric structure, the so called almost tangent structure of higher order, and which is a generalization of the almost tangent geometry of the tangent bundle. Another important fact examined is the extension of the notion of 'spray' to higher order tangent bundles. (Auth.)

  18. Bundled tungsten oxide nanowires under thermal processing

    International Nuclear Information System (INIS)

    Sun Shibin; Zhao Yimin; Xia Yongde; Zhu Yanqiu; Zou Zengda; Min Guanghui

    2008-01-01

    Ultra-thin W 18 O 49 nanowires were initially obtained by a simple solvothermal method using tungsten chloride and cyclohexanol as precursors. Thermal processing of the resulting bundled nanowires has been carried out in air in a tube furnace. The morphology and phase transformation behavior of the as-synthesized nanowires as a function of annealing temperature have been characterized by x-ray diffraction and electron microscopy. The nanostructured bundles underwent a series of morphological evolution with increased annealing temperature, becoming straighter, larger in diameter, and smaller in aspect ratio, eventually becoming irregular particles with size up to 5 μm. At 500 deg. C, the monoclinic W 18 O 49 was completely transformed to monoclinic WO 3 phase, which remains stable at high processing temperature. After thermal processing at 400 deg. C and 450 deg. C, the specific surface areas of the resulting nanowires dropped to 110 m 2 g -1 and 66 m 2 g -1 respectively, compared with that of 151 m 2 g -1 for the as-prepared sample. This study may shed light on the understanding of the geometrical and structural evolution occurring in nanowires whose working environment may involve severe temperature variations

  19. Development boiling to sprinkled tube bundle

    Science.gov (United States)

    Kracík, Petr; Pospíšil, Jiří

    2016-03-01

    This paper presents results of a studied heat transfer coefficient at the surface of a sprinkled tube bundle where boiling occurs. Research in the area of sprinkled exchangers can be divided into two major parts. The first part is research on heat transfer and determination of the heat transfer coefficient at sprinkled tube bundles for various liquids, whether boiling or not. The second part is testing of sprinkle modes for various tube diameters, tube pitches and tube materials and determination of individual modes' interface. All results published so far for water as the falling film liquid apply to one to three tubes for which the mentioned relations studied are determined in rigid laboratory conditions defined strictly in advance. The sprinkled tubes were not viewed from the operational perspective where there are more tubes and various modes may occur in different parts with various heat transfer values. The article focuses on these processes. The tube is located in a low-pressure chamber where vacuum is generated using an exhauster via ejector. The tube consists of smooth copper tubes of 12 mm diameter placed horizontally one above another.

  20. Development boiling to sprinkled tube bundle

    Directory of Open Access Journals (Sweden)

    Kracík Petr

    2016-01-01

    Full Text Available This paper presents results of a studied heat transfer coefficient at the surface of a sprinkled tube bundle where boiling occurs. Research in the area of sprinkled exchangers can be divided into two major parts. The first part is research on heat transfer and determination of the heat transfer coefficient at sprinkled tube bundles for various liquids, whether boiling or not. The second part is testing of sprinkle modes for various tube diameters, tube pitches and tube materials and determination of individual modes’ interface. All results published so far for water as the falling film liquid apply to one to three tubes for which the mentioned relations studied are determined in rigid laboratory conditions defined strictly in advance. The sprinkled tubes were not viewed from the operational perspective where there are more tubes and various modes may occur in different parts with various heat transfer values. The article focuses on these processes. The tube is located in a low-pressure chamber where vacuum is generated using an exhauster via ejector. The tube consists of smooth copper tubes of 12 mm diameter placed horizontally one above another.

  1. Evaluation of Single-Bundle versus Double-Bundle PCL Reconstructions with More Than 10-Year Follow-Up

    Directory of Open Access Journals (Sweden)

    Masataka Deie

    2015-01-01

    Full Text Available Background. Posterior cruciate ligament (PCL injuries are not rare in acute knee injuries, and several recent anatomical studies of the PCL and reconstructive surgical techniques have generated improved patient results. Now, we have evaluated PCL reconstructions performed by either the single-bundle or double-bundle technique in a patient group followed up retrospectively for more than 10 years. Methods. PCL reconstructions were conducted using the single-bundle (27 cases or double-bundle (13 cases method from 1999 to 2002. The mean age at surgery was 34 years in the single-bundle group and 32 years in the double-bundle group. The mean follow-up period was 12.5 years. Patients were evaluated by Lysholm scoring, the gravity sag view, and knee arthrometry. Results. The Lysholm score after surgery was 89.1±5.6 points for the single-bundle group and 91.9±4.5 points for the double-bundle group. There was no significant difference between the methods in the side-to-side differences by gravity sag view or knee arthrometer evaluation, although several cases in both groups showed a side-to-side difference exceeding 5 mm by the latter evaluation method. Conclusions. We found no significant difference between single- and double-bundle PCL reconstructions during more than 10 years of follow-up.

  2. Real-time wavelet-based inline banknote-in-bundle counting for cut-and-bundle machines

    Science.gov (United States)

    Petker, Denis; Lohweg, Volker; Gillich, Eugen; Türke, Thomas; Willeke, Harald; Lochmüller, Jens; Schaede, Johannes

    2011-03-01

    Automatic banknote sheet cut-and-bundle machines are widely used within the scope of banknote production. Beside the cutting-and-bundling, which is a mature technology, image-processing-based quality inspection for this type of machine is attractive. We present in this work a new real-time Touchless Counting and perspective cutting blade quality insurance system, based on a Color-CCD-Camera and a dual-core Computer, for cut-and-bundle applications in banknote production. The system, which applies Wavelet-based multi-scale filtering is able to count banknotes inside a 100-bundle within 200-300 ms depending on the window size.

  3. A conserved residue, PomB-F22, in the transmembrane segment of the flagellar stator complex, has a critical role in conducting ions and generating torque.

    Science.gov (United States)

    Terauchi, Takashi; Terashima, Hiroyuki; Kojima, Seiji; Homma, Michio

    2011-08-01

    Bacterial flagellar motors exploit the electrochemical potential gradient of a coupling ion (H(+) or Na(+)) as their energy source, and are composed of stator and rotor proteins. Sodium-driven and proton-driven motors have the stator proteins PomA and PomB or MotA and MotB, respectively, which interact with each other in their transmembrane (TM) regions to form an ion channel. The single TM region of PomB or MotB, which forms the ion-conduction pathway together with TM3 and TM4 of PomA or MotA, respectively, has a highly conserved aspartate residue that is the ion binding site and is essential for rotation. To investigate the ion conductivity and selectivity of the Na(+)-driven PomA/PomB stator complex, we replaced conserved residues predicted to be near the conserved aspartate with H(+)-type residues, PomA-N194Y, PomB-F22Y and/or PomB-S27T. Motility analysis revealed that the ion specificity was not changed by either of the PomB mutations. PomB-F22Y required a higher concentration of Na(+) to exhibit swimming, but this effect was suppressed by additional mutations, PomA-N194Y or PomB-S27T. Moreover, the motility of the PomB-F22Y mutant was resistant to phenamil, a specific inhibitor for the Na(+) channel. When PomB-F22 was changed to other amino acids and the effects on swimming ability were investigated, replacement with a hydrophilic residue decreased the maximum swimming speed and conferred strong resistance to phenamil. From these results, we speculate that the Na(+) flux is reduced by the PomB-F22Y mutation, and that PomB-F22 is important for the effective release of Na(+) from PomB-D24.

  4. Mutations alter the sodium versus proton use of a Bacillus clausii flagellar motor and confer dual ion use on Bacillus subtilis motors.

    Science.gov (United States)

    Terahara, Naoya; Krulwich, Terry A; Ito, Masahiro

    2008-09-23

    Bacterial flagella contain membrane-embedded stators, Mot complexes, that harness the energy of either transmembrane proton or sodium ion gradients to power motility. Use of sodium ion gradients is associated with elevated pH and sodium concentrations. The Mot complexes studied to date contain channels that use either protons or sodium ions, with some bacteria having only one type and others having two distinct Mot types with different ion-coupling. Here, alkaliphilic Bacillus clausii KSM-K16 was shown to be motile in a pH range from 7 to 11 although its genome encodes only one Mot (BCl-MotAB). Assays of swimming as a function of pH, sodium concentration, and ion-selective motility inhibitors showed that BCl-MotAB couples motility to sodium at the high end of its pH range but uses protons at lower pH. This pattern was confirmed in swimming assays of a statorless Bacillus subtilis mutant expressing either BCl-MotAB or one of the two B. subtilis stators, sodium-coupled Bs-MotPS or proton-coupled Bs-MotAB. Pairs of mutations in BCl-MotB were identified that converted the naturally bifunctional BCl-MotAB to stators that preferentially use either protons or sodium ions across the full pH range. We then identified trios of mutations that added a capacity for dual-ion coupling on the distinct B. subtilis Bs-MotAB and Bs-MotPS motors. Determinants that alter the specificity of bifunctional and single-coupled flagellar stators add to insights from studies of other ion-translocating transporters that use both protons and sodium ions.

  5. Analyzing the modification of the Shewanella oneidensis MR-1 flagellar filament.

    Directory of Open Access Journals (Sweden)

    Sebastian Bubendorfer

    Full Text Available The unsheathed flagellar filament of Shewanella oneidensis MR-1 is composed of two highly homologous flagellins, FlaA, and the major structural unit, FlaB. We identified a gene cluster, SO_3261-SO_3265 (now sfmABCDE, that is required for the formation of a fully functional filament and for motility. The predicted function of the corresponding gene products strongly indicated a role in flagellin modification. Accordingly, loss of sfmABCDE results in a significant mass shift of both FlaA and FlaB. Mass spectroscopy analysis and single residue substitutions identified five serine residues in both flagellins that are modified via O-linkage. Modeling of the flagellin structures strongly suggests that at least four of the modified residues are exposed to the filament's surface. However, none of the five serine residues solely is crucial for function and assembly. Structural analysis of the flagellin modification revealed that it likely contains a nonulosonic acid (274 Da linked to each glycosylated serine. The putative nonulosonic acid is further substituted with a 236 Da moiety which can carry additional methyl groups (250 Da, 264 Da. In addition, at least 5 lysine residues in FlaB and one in FlaA were found to be methylated. Based on homology comparisons we suggest that smfABCDE is required for species-specific flagellin modification in S. oneidensis MR-1.

  6. Crystallization of FcpA from Leptospira, a novel flagellar protein that is essential for pathogenesis.

    Science.gov (United States)

    San Martin, Fabiana; Mechaly, Ariel E; Larrieux, Nicole; Wunder, Elsio A; Ko, Albert I; Picardeau, Mathieu; Trajtenberg, Felipe; Buschiazzo, Alejandro

    2017-03-01

    The protein FcpA is a unique component of the flagellar filament of spirochete bacteria belonging to the genus Leptospira. Although it plays an essential role in translational motility and pathogenicity, no structures of FcpA homologues are currently available in the PDB. Its three-dimensional structure will unveil the novel motility mechanisms that render pathogenic Leptospira particularly efficient at invading and disseminating within their hosts, causing leptospirosis in humans and animals. FcpA from L. interrogans was purified and crystallized, but despite laborious attempts no useful X ray diffraction data could be obtained. This challenge was solved by expressing a close orthologue from the related saprophytic species L. biflexa. Three different crystal forms were obtained: a primitive and a centred monoclinic form, as well as a hexagonal variant. All forms diffracted X-rays to suitable resolutions for crystallographic analyses, with the hexagonal type typically reaching the highest limits of 2.0 Å and better. A variation of the quick-soaking procedure resulted in an iodide derivative that was instrumental for single-wavelength anomalous diffraction methods.

  7. Hair bundles are specialized for ATP delivery via creatine kinase.

    NARCIS (Netherlands)

    Shin, J.B.; Streijger, F.; Beynon, A.J.; Peters, T.; Gadzala, L.; McMillen, D.; Bystrom, C.; Zee, C.E.E.M. van der; Wallimann, T.; Gillespie, P.G.

    2007-01-01

    When stimulated strongly, a hair cell's mechanically sensitive hair bundle may consume ATP too rapidly for replenishment by diffusion. To provide a broad view of the bundle's protein complement, including those proteins participating in energy metabolism, we used shotgun mass spectrometry methods to

  8. Tokyo Guidelines 2018: management bundles for acute cholangitis and cholecystitis

    NARCIS (Netherlands)

    Mayumi, Toshihiko; Okamoto, Kohji; Takada, Tadahiro; Strasberg, Steven M.; Solomkin, Joseph S.; Schlossberg, David; Pitt, Henry A.; Yoshida, Masahiro; Gomi, Harumi; Miura, Fumihiko; Garden, O. James; Kiriyama, Seiki; Yokoe, Masamichi; Endo, Itaru; Asbun, Horacio J.; Iwashita, Yukio; Hibi, Taizo; Umezawa, Akiko; Suzuki, Kenji; Itoi, Takao; Hata, Jiro; Han, Ho-Seong; Hwang, Tsann-Long; Dervenis, Christos; Asai, Koji; Mori, Yasuhisa; Huang, Wayne Shih-Wei; Belli, Giulio; Mukai, Shuntaro; Jagannath, Palepu; Cherqui, Daniel; Kozaka, Kazuto; Baron, Todd H.; de Santibañes, Eduardo; Higuchi, Ryota; Wada, Keita; Gouma, Dirk J.; Deziel, Daniel J.; Liau, Kui-Hin; Wakabayashi, Go; Padbury, Robert; Jonas, Eduard; Supe, Avinash Nivritti; Singh, Harjit; Gabata, Toshifumi; Chan, Angus C. W.; Lau, Wan Yee; Fan, Sheung Tat; Chen, Miin-Fu; Ker, Chen-Guo; Yoon, Yoo-Seok; Choi, In-Seok; Kim, Myung-Hwan; Yoon, Dong-Sup; Kitano, Seigo; Inomata, Masafumi; Hirata, Koichi; Inui, Kazuo; Sumiyama, Yoshinobu; Yamamoto, Masakazu

    2018-01-01

    Management bundles that define items or procedures strongly recommended in clinical practice have been used in many guidelines in recent years. Application of these bundles facilitates the adaptation of guidelines and helps improve the prognosis of target diseases. In Tokyo Guidelines 2013 (TG13),

  9. Infinite Grassmannian and moduli space of G-bundles

    International Nuclear Information System (INIS)

    Kumar, S.; Ramanathan, A.

    1993-03-01

    Let C be a smooth irreducible projective curve and G a simply connected simple affine algebraic group of C. We study in this paper the relationship between the space of vacua defined in Conformal Field Theory and the space of sections of a line bundle on the moduli space of G-bundles over C. (author). 33 refs

  10. An integral Riemann-Roch theorem for surface bundles

    DEFF Research Database (Denmark)

    Madsen, Ib Henning

    2010-01-01

    This paper is a response to a conjecture by T. Akita about an integral Riemann–Roch theorem for surface bundles.......This paper is a response to a conjecture by T. Akita about an integral Riemann–Roch theorem for surface bundles....

  11. Sensory transduction: the 'swarm intelligence' of auditory hair bundles.

    Science.gov (United States)

    Albert, Jörg

    2011-08-23

    In vertebrate hair cells, the hair bundle is responsible for the conversion of mechanical vibrations into electrical signals. In a combined experimental and computational tour de force, a group of researchers now presents a quantitative model that explains how the bundle's specific microarchitecture gives rise to its exquisite mechanosensory properties. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Stability of Picard Bundle Over Moduli Space of Stable Vector ...

    Indian Academy of Sciences (India)

    Abstract. Answering a question of [BV] it is proved that the Picard bundle on the moduli space of stable vector bundles of rank two, on a Riemann surface of genus at least three, with fixed determinant of odd degree is stable.

  13. Phase Space Reduction of Star Products on Cotangent Bundles.

    NARCIS (Netherlands)

    Kowalzig, N.; Neumaier, N.; Pflaum, M.

    2005-01-01

    In this paper we construct star products on Marsden-Weinstein reduced spaces in case both the original phase space and the reduced phase space are (symplectomorphic to) cotangent bundles. Under the assumption that the original cotangent bundle $T^*Q$ carries a symplectic structure of form

  14. Implementing the care bundle approach in the ICU

    African Journals Online (AJOL)

    2007-11-19

    Nov 19, 2007 ... Intensive care standards can only be maintained by quality control of ICU facilities, activities ... The care bundle approach provides a practical tool to implement evidence-based practice in critical care. Care bundles ... algorithm provides a useful bedside tool in the practical implementation of the guideline.

  15. Computational imaging through a fiber-optic bundle

    Science.gov (United States)

    Lodhi, Muhammad A.; Dumas, John Paul; Pierce, Mark C.; Bajwa, Waheed U.

    2017-05-01

    Compressive sensing (CS) has proven to be a viable method for reconstructing high-resolution signals using low-resolution measurements. Integrating CS principles into an optical system allows for higher-resolution imaging using lower-resolution sensor arrays. In contrast to prior works on CS-based imaging, our focus in this paper is on imaging through fiber-optic bundles, in which manufacturing constraints limit individual fiber spacing to around 2 μm. This limitation essentially renders fiber-optic bundles as low-resolution sensors with relatively few resolvable points per unit area. These fiber bundles are often used in minimally invasive medical instruments for viewing tissue at macro and microscopic levels. While the compact nature and flexibility of fiber bundles allow for excellent tissue access in-vivo, imaging through fiber bundles does not provide the fine details of tissue features that is demanded in some medical situations. Our hypothesis is that adapting existing CS principles to fiber bundle-based optical systems will overcome the resolution limitation inherent in fiber-bundle imaging. In a previous paper we examined the practical challenges involved in implementing a highly parallel version of the single-pixel camera while focusing on synthetic objects. This paper extends the same architecture for fiber-bundle imaging under incoherent illumination and addresses some practical issues associated with imaging physical objects. Additionally, we model the optical non-idealities in the system to get lower modelling errors.

  16. Moduli space of Parabolic vector bundles over hyperelliptic curves

    Indian Academy of Sciences (India)

    27

    MODULI SPACE OF PARABOLIC VECTOR BUNDLES OVER. HYPERELLIPTIC CURVES. SURATNO BASU AND SARBESWAR PAL. Abstract. Let X be a smooth projective hyperelliptic curve of arbitrary genus g. In this short article we will classify the rank 2 stable vector bundles with parabolic structure along a reduced ...

  17. Rigidity of minimal submanifolds with flat normal bundle

    Indian Academy of Sciences (India)

    normal bundle. We prove that if the second fundamental form of M satisfies some decay conditions, then M is an affine plane or a catenoid in some Euclidean subspace. Keywords. Catenoid; minimal submanifolds; flat normal bundle. 1. Introduction. Let Mn be an n-dimensional complete minimal immersed submanifold in R.

  18. Interprofessional Perspectives on ABCDE Bundle Implementation: A Focus Group Study.

    Science.gov (United States)

    Boehm, Leanne M; Vasilevskis, Eduard E; Mion, Lorraine C

    The ABCDE bundle is a multifaceted, interprofessional intervention that is associated with reduced ventilator and delirium days as well as increased likelihood of mobility in intensive care. The aim of this study is to describe organizational domains that contribute to variation in ABCDE bundle implementation as reported by intensive care unit providers and to examine the capability of a conceptual framework for identifying variation in ABCDE bundle implementation. We conducted 2 separate focus groups that included nurses, respiratory therapists, occupational and physical therapists (N = 16) from the surgical and medical intensive care units at 1 academic medical center. All participants had experience performing ABCDE bundle activities. Variation in how the ABCDE bundle was interpreted and executed within and across disciplines was noted. Organizational facets, the physical environment, labor quantity and quality, task burden, provider attitudes, and patient characteristics were noted to influence ABCDE bundle execution. The difficulty coordinating and implementing early mobility was emphasized. The number of disciplines required to perform an activity and individual component complexity was reported to influence ABCDE bundle implementation. Nurses repeatedly described challenges with coordinating care across disciplines. Small tests of change, adequate staffing, interprofessional training and protocol development efforts, and role modeling may be effective methods for successful ABCDE bundle implementation.

  19. Weak point property and sections of Picard bundles on a ...

    Indian Academy of Sciences (India)

    Contemp. Math., 465 (2008) (Providence, RI: Amer. Math. Soc.) pp. 45–50. [7] Ein L and Lazarsfeld R, Stability and restrictions of Picard bundles with an application to the normal bundles of elliptic curves, in: Complex projective geometry (ed) Ellingsrud,. Peskine et al LMS 179 (1992) (Cambridge University Press). [8] Fulton ...

  20. Balanced metrics for vector bundles and polarised manifolds

    DEFF Research Database (Denmark)

    Garcia Fernandez, Mario; Ross, Julius

    2012-01-01

    We consider a notion of balanced metrics for triples (X, L, E) which depend on a parameter α, where X is smooth complex manifold with an ample line bundle L and E is a holomorphic vector bundle over X. For generic choice of α, we prove that the limit of a convergent sequence of balanced metrics...

  1. Implementing a pressure ulcer prevention bundle into practice.

    Science.gov (United States)

    Downie, Fiona; Perrin, Anne-Marie; Kiernan, Martin

    The implementation of a care bundle approach to delivering fundamental care in practice is now a recognised and effective way of translating research into practice, offering consistent care with resulting positive outcomes for the patient. A care bundle consists ofa relatively small number of interventions for every patient to whom the bundle is applied. However, there must be evidence behind each individual intervention to indicate, if delivered, how it will reduce the risk to the patient. This paper reports on a strategy for developing and implementing a pressure ulcer (PU) combined prevention care bundle/ care plan into practice. The effectiveness of the care bundle can be measured when it is in use in the practice setting with an audit tool.

  2. Development of nuclear fuel. Development of CANDU advanced fuel bundle

    International Nuclear Information System (INIS)

    Suk, Ho Chun; Hwang, Woan; Jeong, Young Hwan; Jung, Sung Hoon

    1991-07-01

    In order to develop CANDU advanced fuel, the agreement of the joint research between KAERI and AECL was made on February 19, 1991. AECL conceptual design of CANFLEX bundle for Bruce reactors was analyzed and then the reference design and design drawing of the advanced fuel bundle with natural uranium fuel for CANDU-6 reactor were completed. The CANFLEX fuel cladding was preliminarily investigated. The fabricability of the advanced fuel bundle was investigated. The design and purchase of the machinery tools for the bundle fabrication for hydraulic scoping tests were performed. As a result of CANFLEX tube examination, the tubes were found to be meet the criteria proposed in the technical specification. The dummy bundles for hydraulic scoping tests have been fabricated by using the process and tools, where the process parameters and tools have been newly established. (Author)

  3. CFD modeling of secondary flows in fuel rod bundles

    International Nuclear Information System (INIS)

    Baglietto, Emilio; Ninokata, Hisashi

    2004-01-01

    An optimized non-linear eddy viscosity model is introduced, for calculations of detailed coolant velocity distribution in a tight lattice fuel bundle. The low Reynolds formulation has been optimized based on DNS data for channel flow. The non-linear stress-strain relationship has been modified in the coefficients to model the flow anisotropy, which causes the formation of turbulence driven secondary flows inside the bundle subchannels. Predictions of the model are first compared to experimental measurements of secondary flows in a triangularly arrayed rod bundle with p/d=1.3. Subsequently wall shear stress and velocity predictions are compared with different experimental data for a rod bundle with p/d=1.17. The model shows to be able to correctly reproduce the scale of the secondary motion, and to accurately reproduce both wall shear stress and velocity distributions inside the rod bundle subchannels. (author)

  4. Superconductivity in an Inhomogeneous Bundle of Metallic and Semiconducting Nanotubes

    Directory of Open Access Journals (Sweden)

    Ilya Grigorenko

    2013-01-01

    Full Text Available Using Bogoliubov-de Gennes formalism for inhomogeneous systems, we have studied superconducting properties of a bundle of packed carbon nanotubes, making a triangular lattice in the bundle's transverse cross-section. The bundle consists of a mixture of metallic and doped semiconducting nanotubes, which have different critical transition temperatures. We investigate how a spatially averaged superconducting order parameter and the critical transition temperature depend on the fraction of the doped semiconducting carbon nanotubes in the bundle. Our simulations suggest that the superconductivity in the bundle will be suppressed when the fraction of the doped semiconducting carbon nanotubes will be less than 0.5, which is the percolation threshold for a two-dimensional triangular lattice.

  5. Bundles over Quantum RealWeighted Projective Spaces

    Directory of Open Access Journals (Sweden)

    Tomasz Brzeziński

    2012-09-01

    Full Text Available The algebraic approach to bundles in non-commutative geometry and the definition of quantum real weighted projective spaces are reviewed. Principal U(1-bundles over quantum real weighted projective spaces are constructed. As the spaces in question fall into two separate classes, the negative or odd class that generalises quantum real projective planes and the positive or even class that generalises the quantum disc, so do the constructed principal bundles. In the negative case the principal bundle is proven to be non-trivial and associated projective modules are described. In the positive case the principal bundles turn out to be trivial, and so all the associated modules are free. It is also shown that the circle (coactions on the quantum Seifert manifold that define quantum real weighted projective spaces are almost free.

  6. Vision, healing brush, and fiber bundles

    Science.gov (United States)

    Georgiev, Todor

    2005-03-01

    The Healing Brush is a tool introduced for the first time in Adobe Photoshop (2002) that removes defects in images by seamless cloning (gradient domain fusion). The Healing Brush algorithms are built on a new mathematical approach that uses Fibre Bundles and Connections to model the representation of images in the visual system. Our mathematical results are derived from first principles of human vision, related to adaptation transforms of von Kries type and Retinex theory. In this paper we present the new result of Healing in arbitrary color space. In addition to supporting image repair and seamless cloning, our approach also produces the exact solution to the problem of high dynamic range compression of17 and can be applied to other image processing algorithms.

  7. Cyclic hardening in bundled actin networks.

    Science.gov (United States)

    Schmoller, K M; Fernández, P; Arevalo, R C; Blair, D L; Bausch, A R

    2010-01-01

    Nonlinear deformations can irreversibly alter the mechanical properties of materials. Most soft materials, such as rubber and living tissues, display pronounced softening when cyclically deformed. Here we show that, in contrast, reconstituted networks of crosslinked, bundled actin filaments harden when subject to cyclical shear. As a consequence, they exhibit a mechano-memory where a significant stress barrier is generated at the maximum of the cyclic shear strain. This unique response is crucially determined by the network architecture: at lower crosslinker concentrations networks do not harden, but soften showing the classic Mullins effect known from rubber-like materials. By simultaneously performing macrorheology and confocal microscopy, we show that cyclic shearing results in structural reorganization of the network constituents such that the maximum applied strain is encoded into the network architecture.

  8. Advanced tube-bundle rocket thrust chamber

    Science.gov (United States)

    Kazaroff, John M.; Pavli, Albert J.

    1990-01-01

    An advanced rocket thrust chamber for future space application is described along with an improved method of fabrication. Potential benefits of the concept are improved cyclic life, reusability, and performance. Performance improvements are anticipated because of the enhanced heat transfer into the coolant which will enable higher chamber pressure in expander cycle engines. Cyclic life, reusability and reliability improvements are anticipated because of the enhanced structural compliance inherent in the construction. The method of construction involves the forming of the combustion chamber with a tube-bundle of high conductivity copper or copper alloy tubes, and the bonding of these tubes by an electroforming operation. Further, the method of fabrication reduces chamber complexity by incorporating manifolds, jackets, and structural stiffeners while having the potential for thrust chamber cost and weight reduction.

  9. Color Space Axioms and Fiber Bundles

    Directory of Open Access Journals (Sweden)

    Edoardo Provenzi

    2017-08-01

    Full Text Available In 1974, H. L. Resnkikoff published an inspiring paper about the use of differential geometry to study, among others, the intrinsic shape of the space of perceived colors and the Riemannian metrics on it. The mathematical techniques that he used is shared with modern theories of theoretical physics, which are far from being a common background for scientists in color vision and processing. Due to this, Resnikoff’s paper remained unnoticed for decades. In this brief contribution, some insights about how to update Resnikoff’s ideas will be given and discussed in relationship with a modern theory of color spaces and to the mathematical concept of principal fiber bundle.

  10. Critical Power Performance of Tight Lattice Bundle

    Science.gov (United States)

    Yamamoto, Yasushi; Hiraiwa, Kouji; Morooka, Shinichi; Abe, Nobuaki

    An innovative fuel cycle system concept named BARS (BWR with an Advanced Recycle System) has been proposed as a future fuel cycle option aiming at enhanced utilization of uranium resources and reduction of radioactive wastes. In BARS, the spent fuel from conventional light water reactors (LWRs) is recycled as a mixed oxide (MOX) fuel for a BWR core with the fast neutron spectrum by means of oxide dry-processing and vibro-packing fuel fabrication. The fast neutron spectrum is obtained by means of triangular tight fuel lattice. Further study on BARS, especially on tight lattice MOX fuel, has been initiated as a joint study by Toshiba and Gifu University. The objective of this paper is to show the latest progress of the study on BARS, especially concerning the thermal-hydraulics measurements for tight lattice bundle.

  11. Framework for shape analysis of white matter fiber bundles.

    Science.gov (United States)

    Glozman, Tanya; Bruckert, Lisa; Pestilli, Franco; Yecies, Derek W; Guibas, Leonidas J; Yeom, Kristen W

    2018-02-15

    Diffusion imaging coupled with tractography algorithms allows researchers to image human white matter fiber bundles in-vivo. These bundles are three-dimensional structures with shapes that change over time during the course of development as well as in pathologic states. While most studies on white matter variability focus on analysis of tissue properties estimated from the diffusion data, e.g. fractional anisotropy, the shape variability of white matter fiber bundle is much less explored. In this paper, we present a set of tools for shape analysis of white matter fiber bundles, namely: (1) a concise geometric model of bundle shapes; (2) a method for bundle registration between subjects; (3) a method for deformation estimation. Our framework is useful for analysis of shape variability in white matter fiber bundles. We demonstrate our framework by applying our methods on two datasets: one consisting of data for 6 normal adults and another consisting of data for 38 normal children of age 11 days to 8.5 years. We suggest a robust and reproducible method to measure changes in the shape of white matter fiber bundles. We demonstrate how this method can be used to create a model to assess age-dependent changes in the shape of specific fiber bundles. We derive such models for an ensemble of white matter fiber bundles on our pediatric dataset and show that our results agree with normative human head and brain growth data. Creating these models for a large pediatric longitudinal dataset may improve understanding of both normal development and pathologic states and propose novel parameters for the examination of the pediatric brain. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Bacterial Proteasomes.

    Science.gov (United States)

    Jastrab, Jordan B; Darwin, K Heran

    2015-01-01

    Interest in bacterial proteasomes was sparked by the discovery that proteasomal degradation is required for the pathogenesis of Mycobacterium tuberculosis, one of the world's deadliest pathogens. Although bacterial proteasomes are structurally similar to their eukaryotic and archaeal homologs, there are key differences in their mechanisms of assembly, activation, and substrate targeting for degradation. In this article, we compare and contrast bacterial proteasomes with their archaeal and eukaryotic counterparts, and we discuss recent advances in our understanding of how bacterial proteasomes function to influence microbial physiology.

  13. Restriction of Preferences to the Set of Consumption Bundles, In a Model with Production and Consumption Bundles

    NARCIS (Netherlands)

    Schalk, S.

    1999-01-01

    In contrast to the neo-classical theory of Arrow and Debreu, a model of a private ownership economy is presented, in which production and consumption bundles are treated separately. Each of the two types of bundles is assumed to establish a con- vex cone. Production technologies can convert

  14. Single-Bundle Versus Double-Bundle Reconstruction for Anterior Cruciate Ligament Rupture: A Meta-Analysis-Does Anatomy Matter?

    NARCIS (Netherlands)

    Eck, Carola F. Van; Kopf, Sebastian; Irrgang, James J.; Blankevoort, Leendert; Bhandari, Mohit; Fu, Freddie H.; Poolman, Rudolf W.

    2012-01-01

    Purpose: To determine whether double-bundle anterior cruciate ligament reconstruction leads to better restoration of anterior and rotational laxity and range of motion than single-bundle reconstruction. Methods: A search was performed in the Medline, Embase, CINAHL, and Cochrane databases. All

  15. Are there intracellular Ca2+ oscillations correlated with flagellar beating in human sperm? A three vs. two-dimensional analysis.

    Science.gov (United States)

    Corkidi, G; Montoya, F; Hernández-Herrera, P; Ríos-Herrera, W A; Müller, M F; Treviño, C L; Darszon, A

    2017-09-01

    Are there intracellular Ca2+ ([Ca2+]i) oscillations correlated with flagellar beating in human sperm? The results reveal statistically significant [Ca2+]i oscillations that are correlated with the human sperm flagellar beating frequency, when measured in three-dimensions (3D). Fast [Ca2+]i oscillations that are correlated to the beating flagellar frequency of cells swimming in a restricted volume have been detected in hamster sperm. To date, such findings have not been confirmed in any other mammalian sperm species. An important question that has remained regarding these observations is whether the fast [Ca2+]i oscillations are real or might they be due to remaining defocusing effects of the Z component arising from the 3D beating of the flagella. Healthy donors whose semen samples fulfill the WHO criteria between the age of 18-28 were selected. Cells from at least six different donors were utilized for analysis. Approximately the same number of experimental and control cells were analyzed. Motile cells were obtained by the swim-up technique and were loaded with Fluo-4 (Ca2+ sensitive dye) or with Calcein (Ca2+ insensitive dye). Ni2+ was used as a non-specific plasma membrane Ca2+ channel blocker. Fluorescence data and flagella position were acquired in 3D. Each cell was recorded for up to 5.6 s within a depth of 16 microns with a high speed camera (coupled to an image intensifier) acquiring at a rate of 3000 frames per second, while an oscillating objective vibrated at 90 Hz via a piezoelectric device. From these samples, eight experimental and nine control sperm cells were analyzed in both 2D and 3D. We have implemented a new system that allows [Ca2+]i measurements of the human sperm flagellum beating in 3D. These measurements reveal statistically significant [Ca2+]i oscillations that correlate with the flagellar beating frequency. These oscillations may arise from intracellular sources and/or Ca2+ transporters, as they were insensitive to external Ni2+, a non

  16. Bacterial adhesion

    NARCIS (Netherlands)

    Loosdrecht, van M.C.M.

    1988-01-01

    As mentioned in the introduction of this thesis bacterial adhesion has been studied from a variety of (mostly practice oriented) starting points. This has resulted in a range of widely divergent approaches. In order to elucidate general principles in bacterial adhesion phenomena, we felt it

  17. Independent evolution of neurotoxin and flagellar genetic loci in proteolytic Clostridium botulinum

    Directory of Open Access Journals (Sweden)

    Twine Susan M

    2009-03-01

    Full Text Available Abstract Background Proteolytic Clostridium botulinum is the causative agent of botulism, a severe neuroparalytic illness. Given the severity of botulism, surprisingly little is known of the population structure, biology, phylogeny or evolution of C. botulinum. The recent determination of the genome sequence of C. botulinum has allowed comparative genomic indexing using a DNA microarray. Results Whole genome microarray analysis revealed that 63% of the coding sequences (CDSs present in reference strain ATCC 3502 were common to all 61 widely-representative strains of proteolytic C. botulinum and the closely related C. sporogenes tested. This indicates a relatively stable genome. There was, however, evidence for recombination and genetic exchange, in particular within the neurotoxin gene and cluster (including transfer of neurotoxin genes to C. sporogenes, and the flagellar glycosylation island (FGI. These two loci appear to have evolved independently from each other, and from the remainder of the genetic complement. A number of strains were atypical; for example, while 10 out of 14 strains that formed type A1 toxin gave almost identical profiles in whole genome, neurotoxin cluster and FGI analyses, the other four strains showed divergent properties. Furthermore, a new neurotoxin sub-type (A5 has been discovered in strains from heroin-associated wound botulism cases. For the first time, differences in glycosylation profiles of the flagella could be linked to differences in the gene content of the FGI. Conclusion Proteolytic C. botulinum has a stable genome backbone containing specific regions of genetic heterogeneity. These include the neurotoxin gene cluster and the FGI, each having evolved independently of each other and the remainder of the genetic complement. Analysis of these genetic components provides a high degree of discrimination of strains of proteolytic C. botulinum, and is suitable for clinical and forensic investigations of botulism

  18. Characterization of a subunit of the outer dynein arm docking complex necessary for correct flagellar assembly in Leishmania donovani.

    Directory of Open Access Journals (Sweden)

    Simone Harder

    Full Text Available BACKGROUND: In order to proceed through their life cycle, Leishmania parasites switch between sandflies and mammals. The flagellated promastigote cells transmitted by the insect vector are phagocytized by macrophages within the mammalian host and convert into the amastigote stage, which possesses a rudimentary flagellum only. During an earlier proteomic study of the stage differentiation of the parasite we identified a component of the outer dynein arm docking complex, a structure of the flagellar axoneme. The 70 kDa subunit of the outer dynein arm docking complex consists of three subunits altogether and is essential for the assembly of the outer dynein arm onto the doublet microtubule of the flagella. According to the nomenclature of the well-studied Chlamydomonas reinhardtii complex we named the Leishmania protein LdDC2. METHODOLOGY/PRINCIPAL FINDINGS: This study features a characterization of the protein over the life cycle of the parasite. It is synthesized exclusively in the promastigote stage and localizes to the flagellum. Gene replacement mutants of lddc2 show reduced growth rates and diminished flagellar length. Additionally, the normally spindle-shaped promastigote parasites reveal a more spherical cell shape giving them an amastigote-like appearance. The mutants lose their motility and wiggle in place. Ultrastructural analyses reveal that the outer dynein arm is missing. Furthermore, expression of the amastigote-specific A2 gene family was detected in the deletion mutants in the absence of a stage conversion stimulus. In vitro infectivity is slightly increased in the mutant cell line compared to wild-type Leishmania donovani parasites. CONCLUSIONS/SIGNIFICANCE: Our results indicate that the correct assembly of the flagellum has a great influence on the investigated characteristics of Leishmania parasites. The lack of a single flagellar protein causes an aberrant morphology, impaired growth and altered infectiousness of the parasite.

  19. Reaction-diffusion model of hair-bundle morphogenesis.

    Science.gov (United States)

    Jacobo, Adrian; Hudspeth, A J

    2014-10-28

    The hair bundle, an apical specialization of the hair cell composed of several rows of regularly organized stereocilia and a kinocilium, is essential for mechanotransduction in the ear. Its precise organization allows the hair bundle to convert mechanical stimuli to electrical signals; mutations that alter the bundle's morphology often cause deafness. However, little is known about the proteins involved in the process of morphogenesis and how the structure of the bundle arises through interactions between these molecules. We present a mathematical model based on simple reaction-diffusion mechanisms that can reproduce the shape and organization of the hair bundle. This model suggests that the boundary of the cell and the kinocilium act as signaling centers that establish the bundle's shape. The interaction of two proteins forms a hexagonal Turing pattern--a periodic modulation of the concentrations of the morphogens, sustained by local activation and long-range inhibition of the reactants--that sets a blueprint for the location of the stereocilia. Finally we use this model to predict how different alterations to the system might impact the shape and organization of the hair bundle.

  20. Two-categorical bundles and their classifying spaces

    DEFF Research Database (Denmark)

    Baas, Nils A.; Bökstedt, M.; Kro, T.A.

    2012-01-01

    -category is a classifying space for the associated principal 2-bundles. In the process of proving this we develop a lot of powerful machinery which may be useful in further studies of 2-categorical topology. As a corollary we get a new proof of the classification of principal bundles. A calculation based......For a 2-category 2C we associate a notion of a principal 2C-bundle. In case of the 2-category of 2-vector spaces in the sense of M.M. Kapranov and V.A. Voevodsky this gives the the 2-vector bundles of N.A. Baas, B.I. Dundas and J. Rognes. Our main result says that the geometric nerve of a good 2...... on the main theorem shows that the principal 2-bundles associated to the 2-category of 2-vector spaces in the sense of J.C. Baez and A.S. Crans split, up to concordance, as two copies of ordinary vector bundles. When 2C is a cobordism type 2-category we get a new notion of cobordism-bundles which turns out...

  1. Moduli of Parabolic Higgs Bundles and Atiyah Algebroids

    DEFF Research Database (Denmark)

    Logares, Marina; Martens, Johan

    2010-01-01

    In this paper we study the geometry of the moduli space of (non-strongly) parabolic Higgs bundles over a Riemann surface with marked points. We show that this space possesses a Poisson structure, extending the one on the dual of an Atiyah algebroid over the moduli space of parabolic vector bundles....... By considering the case of full flags, we get a Grothendieck–Springer resolution for all other flag types, in particular for the moduli spaces of twisted Higgs bundles, as studied by Markman and Bottacin and used in the recent work of Laumon–Ngô. We discuss the Hitchin system, and demonstrate that all...

  2. Assembly mechanism for nuclear fuel bundles

    International Nuclear Information System (INIS)

    Long, J.W.; Flora, B.S.

    1977-01-01

    A method of securing a fuel bundle to permit easy remote disassembly is described. Fuel rods are held loosely between end plates, each end of the rods fitting into holes in the end plates. At the upper end of each fuel rod there is a spring pressing against the end plate. Tie rods are used to hold the end plates together securely. The lower end of each tie rod is screwed into the lower end plate; the upper end of each tie rod is attached to the upper end plate by means of a locking assembly described in the patent. In order to remove the upper tie plate during the disassembly process, it is necessary only to depress the tie plate against the pressure of the springs surrounding the fuel rods and then to rotate each locking sleeve on the tie rods from its locked to its unlocked position. It is then possible to remove the tie plate without disassembling the locking assembly. (LL)

  3. Bundled automobile insurance coverage and accidents.

    Science.gov (United States)

    Li, Chu-Shiu; Liu, Chwen-Chi; Peng, Sheng-Chang

    2013-01-01

    This paper investigates the characteristics of automobile accidents by taking into account two types of automobile insurance coverage: comprehensive vehicle physical damage insurance and voluntary third-party liability insurance. By using a unique data set in the Taiwanese automobile insurance market, we explore the bundled automobile insurance coverage and the occurrence of claims. It is shown that vehicle physical damage insurance is the major automobile coverage and affects the decision to purchase voluntary liability insurance coverage as a complement. Moreover, policyholders with high vehicle physical damage insurance coverage have a significantly higher probability of filing vehicle damage claims, and if they additionally purchase low voluntary liability insurance coverage, their accident claims probability is higher than those who purchase high voluntary liability insurance coverage. Our empirical results reveal that additional automobile insurance coverage information can capture more driver characteristics and driving behaviors to provide useful information for insurers' underwriting policies and to help analyze the occurrence of automobile accidents. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Stability of the plasma in a bundle divertor

    International Nuclear Information System (INIS)

    Yang, T.F.; Callen, J.D.

    1979-02-01

    Due to the pressure and magnetic field gradients and curvature of the magnetic field lines in a bundle divertor of a tokamak device, the plasma may be unstable to local interchange modes. Turbulent transport could be quite large and lead to a thick scrape-off layer which is as large as the radius of curvature of the diverted flux bundle. Such turbulence would be beneficial for lowering the energy and particle fluxes on the collector in a bundle divertor. The effect of a bundle divertor on the β limit resulting from the ballooning modes of instability in the central plasma is also estimated. The critical β is reduced by less than one percent

  5. Devices for investigation and intervention on steam generators tubes bundles

    International Nuclear Information System (INIS)

    Launay, J.P.; Sort, M.

    1986-01-01

    After a brief recall on the French regulation concerning pressure vessels, the authors describe the experience and the devices used by Framatome for closing, repairing, sleeving and shot peening for steam generators tubes bundles [fr

  6. Introductory lectures on fibre bundles and topology for physicists

    International Nuclear Information System (INIS)

    Thomas, G.H.

    1978-05-01

    These lectures may provide useful background material for understanding gauge theories, particularly the nonperturbative effects such as instantons and monopoles. The mathematical language of topology and fibre bundles is introduced

  7. Design and synthesis of DNA four-helix bundles

    International Nuclear Information System (INIS)

    Rangnekar, Abhijit; Gothelf, Kurt V; LaBean, Thomas H

    2011-01-01

    The field of DNA nanotechnology has evolved significantly in the past decade. Researchers have succeeded in synthesizing tile-based structures and using them to form periodic lattices in one, two and three dimensions. Origami-based structures have also been used to create nanoscale structures in two and three dimensions. Design and construction of DNA bundles with fixed circumference has added a new dimension to the field. Here we report the design and synthesis of a DNA four-helix bundle. It was found to be extremely rigid and stable. When several such bundles were assembled using appropriate sticky-ends, they formed micrometre-long filaments. However, when creation of two-dimensional sheet-like arrays of the four-helix bundles was attempted, nanoscale rings were observed instead. The exact reason behind the nanoring formation is yet to be ascertained, but it provides an exciting prospect for making programmable circular nanostructures using DNA.

  8. Absorber rod bundle actuator in a pressurized water nuclear reactor

    International Nuclear Information System (INIS)

    Martin, J.; Peletan, R.

    1984-01-01

    The invention concerns an absorber rod bundle actuator in a pressurized water reactor with spectral shift control. The device comprises two coaxial control bars. The inner bar is integral with the absorber rod bundle; it has an enlarged zone which acts as a proton under pressure difference across an annular seal which can be radially expanded, the pressure difference allowing to the absorber rod bundles actuating on the piston. When a pressure difference is applied, the seal expands radially by a sufficient amount to make sealing contact with the zone of larger diameter in the outer bar. The invention applies more particularly to reactors with spectral shift control using bundles of fertile rods [fr

  9. CANFLEX fuel bundle cross-flow endurance test (test report)

    International Nuclear Information System (INIS)

    Hong, Sung Deok; Chung, C. H.; Chang, S. K.; Kim, B. D.

    1997-04-01

    As part of the normal refuelling sequence of CANDU nuclear reactor, both new and irradiated bundles can be parked in the cross-flow region of the liner tubes. This situation occurs normally for a few minutes. The fuel bundle which is subjected to the cross-flow should be capable of withstanding the consequences of cross flow for normal periods, and maintain its mechanical integrity. The cross-flow endurance test was conducted for CANFLEX bundle, latest developed nuclear fuel, at CANDU-Hot Test Loop. The test was carried out during 4 hours at the inlet cross-flow region. After the test, the bundle successfully met all acceptance criteria after the 4 hours cross-flow test. (author). 2 refs., 3 tabs

  10. On induced hermitian metrics for holomorphic vector bundles

    International Nuclear Information System (INIS)

    Hoang Le Minh.

    1989-09-01

    An explicit computation of induced hermitian metrics on holomorphic vector bundles is given. As an example the Fubini-Study metrics for complex projective spaces and Grassmannians are considered. (author). 5 refs

  11. On the classification of complex vector bundles of stable rank

    Indian Academy of Sciences (India)

    , the tuples of cohomology classes on a compact, complex manifold, corresponding to the Chern classes of a complex vector bundle of stable rank. This classification becomes more effective on generalized flag manifolds, where the Lie ...

  12. CANFLEX fuel bundle cross-flow endurance test (test report)

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Deok; Chung, C. H.; Chang, S. K.; Kim, B. D.

    1997-04-01

    As part of the normal refuelling sequence of CANDU nuclear reactor, both new and irradiated bundles can be parked in the cross-flow region of the liner tubes. This situation occurs normally for a few minutes. The fuel bundle which is subjected to the cross-flow should be capable of withstanding the consequences of cross flow for normal periods, and maintain its mechanical integrity. The cross-flow endurance test was conducted for CANFLEX bundle, latest developed nuclear fuel, at CANDU-Hot Test Loop. The test was carried out during 4 hours at the inlet cross-flow region. After the test, the bundle successfully met all acceptance criteria after the 4 hours cross-flow test. (author). 2 refs., 3 tabs.

  13. Simulation of finite size effects of the fiber bundle model

    Science.gov (United States)

    Hao, Da-Peng; Tang, Gang; Xun, Zhi-Peng; Xia, Hui; Han, Kui

    2018-01-01

    In theory, the macroscopic fracture of materials should correspond with the thermodynamic limit of the fiber bundle model. However, the simulation of a fiber bundle model with an infinite size is unrealistic. To study the finite size effects of the fiber bundle model, fiber bundle models of various size are simulated in detail. The effects of system size on the constitutive behavior, critical stress, maximum avalanche size, avalanche size distribution, and increased step number of external load are explored. The simulation results imply that there is no feature size or cut size for macroscopic mechanical and statistical properties of the model. The constitutive curves near the macroscopic failure for various system size can collapse well with a simple scaling relationship. Simultaneously, the introduction of a simple extrapolation method facilitates the acquisition of more accurate simulation results in a large-limit system, which is better for comparison with theoretical results.

  14. Preparations of Nanostructured Silicide Bundles and Oxide Arrays

    Directory of Open Access Journals (Sweden)

    Hirokazu Tatsuoka

    2014-08-01

    Full Text Available A variety of nanostructured silicide bundles and oxide nanowire arrays with abundant, non-toxic materials we are prepared. The CrSi2 nanowire and Mg2Si/MgO composite nanowire bundles were synthesized using a Si substrate and a SiOx nanofiber bundle, respectively. The hexagonal MoSi2 nanosheet bundles were also synthesized using a MoS2 layered material as a template. In addition, ZnO, CuO/Cu2O and α-Fe2O3 nanowire arrays were prepared on semiconductor or metallic substrates. The growth phenomena and the structural properties of the nanostructured materials awere investigated. In addition, the preparations of axial and radial nanowire structures weare examined. 

  15. Bundles of Norms About Teen Sex and Pregnancy.

    Science.gov (United States)

    Mollborn, Stefanie; Sennott, Christie

    2015-09-01

    Teen pregnancy is a cultural battleground in struggles over morality, education, and family. At its heart are norms about teen sex, contraception, pregnancy, and abortion. Analyzing 57 interviews with college students, we found that "bundles" of related norms shaped the messages teens hear. Teens did not think their communities encouraged teen sex or pregnancy, but normative messages differed greatly, with either moral or practical rationalizations. Teens readily identified multiple norms intended to regulate teen sex, contraception, abortion, childbearing, and the sanctioning of teen parents. Beyond influencing teens' behavior, norms shaped teenagers' public portrayals and post hoc justifications of their behavior. Although norm bundles are complex to measure, participants could summarize them succinctly. These bundles and their conflicting behavioral prescriptions create space for human agency in negotiating normative pressures. The norm bundles concept has implications for teen pregnancy prevention policies and can help revitalize social norms for understanding health behaviors. © The Author(s) 2014.

  16. Bundle Pricing Decisions for Fresh Products with Quality Deterioration

    Directory of Open Access Journals (Sweden)

    Yan Fang

    2018-01-01

    Full Text Available How to sell fresh products quickly to decrease the storage cost and to meet customer quality requirement is of vital importance in the food supply chain. Bundling fresh products is an efficient strategy to promote sales and reduce storage pressure of retailers. In this paper, we consider the bundle pricing decisions for homogeneous fresh products with quality deterioration. The value of fresh products with quality deterioration is approximated as an exponential function based on which customer’s reservation prices are calculated. A nonlinear mixed integer programming model is used to formulate the bundle pricing problem for fresh products. By adding auxiliary decision variables, this model is converted into a mixed integer linear program. Numerical experiments and sensitive analysis are conducted to provide managerial insights for bundling fresh products with quality deterioration.

  17. Design and synthesis of DNA four-helix bundles

    Energy Technology Data Exchange (ETDEWEB)

    Rangnekar, Abhijit; Gothelf, Kurt V [Department of Chemistry, Centre for DNA Nanotechnology (CDNA) and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus C (Denmark); LaBean, Thomas H, E-mail: kvg@chem.au.dk, E-mail: thl@cs.duke.edu [Department of Chemistry, Duke University, Durham, NC 27708 (United States)

    2011-06-10

    The field of DNA nanotechnology has evolved significantly in the past decade. Researchers have succeeded in synthesizing tile-based structures and using them to form periodic lattices in one, two and three dimensions. Origami-based structures have also been used to create nanoscale structures in two and three dimensions. Design and construction of DNA bundles with fixed circumference has added a new dimension to the field. Here we report the design and synthesis of a DNA four-helix bundle. It was found to be extremely rigid and stable. When several such bundles were assembled using appropriate sticky-ends, they formed micrometre-long filaments. However, when creation of two-dimensional sheet-like arrays of the four-helix bundles was attempted, nanoscale rings were observed instead. The exact reason behind the nanoring formation is yet to be ascertained, but it provides an exciting prospect for making programmable circular nanostructures using DNA.

  18. Bacterial Vaginosis

    Science.gov (United States)

    ... Archive STDs Home Page Bacterial Vaginosis (BV) Chlamydia Gonorrhea Genital Herpes Hepatitis HIV/AIDS & STDs Human Papillomavirus ( ... of getting other STDs, such as chlamydia and gonorrhea . These bacteria can sometimes cause pelvic inflammatory disease ( ...

  19. A flagellar A-kinase anchoring protein with two amphipathic helices forms a structural scaffold in the radial spoke complex.

    Science.gov (United States)

    Sivadas, Priyanka; Dienes, Jennifer M; St Maurice, Martin; Meek, William D; Yang, Pinfen

    2012-11-12

    A-kinase anchoring proteins (AKAPs) contain an amphipathic helix (AH) that binds the dimerization and docking (D/D) domain, RIIa, in cAMP-dependent protein kinase A (PKA). Many AKAPs were discovered solely based on the AH-RIIa interaction in vitro. An RIIa or a similar Dpy-30 domain is also present in numerous diverged molecules that are implicated in critical processes as diverse as flagellar beating, membrane trafficking, histone methylation, and stem cell differentiation, yet these molecules remain poorly characterized. Here we demonstrate that an AKAP, RSP3, forms a dimeric structural scaffold in the flagellar radial spoke complex, anchoring through two distinct AHs, the RIIa and Dpy-30 domains, in four non-PKA spoke proteins involved in the assembly and modulation of the complex. Interestingly, one AH can bind both RIIa and Dpy-30 domains in vitro. Thus, AHs and D/D domains constitute a versatile yet potentially promiscuous system for localizing various effector mechanisms. These results greatly expand the current concept about anchoring mechanisms and AKAPs.

  20. Proteomics on the rims: insights into the biology of the nuclear envelope and flagellar pocket of trypanosomes.

    Science.gov (United States)

    Field, Mark C; Adung'a, Vincent; Obado, Samson; Chait, Brian T; Rout, Michael P

    2012-08-01

    Trypanosomatids represent the causative agents of major diseases in humans, livestock and plants, with inevitable suffering and economic hardship as a result. They are also evolutionarily highly divergent organisms, and the many unique aspects of trypanosome biology provide opportunities in terms of identification of drug targets, the challenge of exploiting these putative targets and, at the same time, significant scope for exploration of novel and divergent cell biology. We can estimate from genome sequences that the degree of divergence of trypanosomes from animals and fungi is extreme, with perhaps one third to one half of predicted trypanosome proteins having no known function based on homology or recognizable protein domains/architecture. Two highly important aspects of trypanosome biology are the flagellar pocket and the nuclear envelope, where in silico analysis clearly suggests great potential divergence in the proteome. The flagellar pocket is the sole site of endo- and exocytosis in trypanosomes and plays important roles in immune evasion via variant surface glycoprotein (VSG) trafficking and providing a location for sequestration of various invariant receptors. The trypanosome nuclear envelope has been largely unexplored but, by analogy with higher eukaryotes, roles in the regulation of chromatin and most significantly, in controlling VSG gene expression are expected. Here we discuss recent successful proteomics-based approaches towards characterization of the nuclear envelope and the endocytic apparatus, the identification of conserved and novel trypanosomatid-specific features, and the implications of these findings.

  1. Roles of osmolality, calcium - Potassium antagonist and calcium in activation and flagellar beating pattern of sturgeon sperm.

    Science.gov (United States)

    Alavi, S M H; Gela, D; Rodina, M; Linhart, O

    2011-10-01

    The present study shows the roles of osmolality, calcium (Ca(2+))-potassium (K(+)) antagonist and Ca(2+) in sperm activation and flagellar beating of a sturgeon species, sterlet (Acipenser ruthenus). Sperm motility was activated at hypoosmolality relative to seminal plasma and suppressed at 175 mOsmol kg(-1). Sperm activation was totally suppressed by 0.35mM K(+), but Ca(2+) could fully reverse K(+) inhibitory effect at Ca(2+): K(+) ratio of 0.25. Neither EGTA (a chelator of Ca(2+) ions) nor nifedipine (a Ca(2+) channel blocker) prevented sperm activation. But, sperm motility and velocity were significantly decreased by EGTA, nifedipine and an inhibitor for Ca(2+)/calmodulin activated phosphodiesterase (w-7) that suggest role of Ca(2+) signaling after triggering sperm activation through hypoosmolality. Symmetric flagellar beating was also turned to asymmetric after activation in w-7, which is an evidence for modulation of Ca(2+)-binding proteins activity. Sturgeon sperm, similar to salmonids, is immotile in seminal plasma due to high K(+) concentrations, but the mechanism of sperm activation seems to be closer to other fish species where osmolality prohibits sperm activation in seminal plasma. In these species, hypoosmolality is the primary signal for sperm Ca(2+)-dependent signaling of axonemal beating. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. Isotopy Classification of Engel Structures on Circle Bundles

    OpenAIRE

    Klukas, Mirko; Sahamie, Bijan

    2012-01-01

    We call two Engel structures isotopic if they are homotopic through Engel structures by a homotopy that fixes the characteristic line field. In the present paper we define an isotopy invariant of Engel structures on oriented circle bundles over closed oriented three-manifolds and apply it to give an isotopy classification of Engel structures on circle bundles with characteristic line field tangent to the fibers.

  3. Cryopreservation of sperm bundles (spermatozeugmata) from endangered livebearing goodeids.

    Science.gov (United States)

    Liu, Yue; Torres, Leticia; Tiersch, Terrence R

    2018-04-14

    More than half of fishes in the family Goodeidae are considered to be endangered, threatened, or vulnerable. Sperm cryopreservation is an effective tool for conserving genetic resources of imperiled populations, but development of protocols with livebearing fishes faces numerous challenges including the natural packaging of sperm into bundles. In this study the cryopreservation of sperm bundles (spermatozeugmata) of three goodeids species was evaluated. Sperm quality was evaluated by activation with NaCl-NaOH solution (at 300 mOsmol/kg and pH 11.8), and analysis of dissociable bundles and dissociation duration. Using Redtail Splitfin (Xenotoca eiseni) as a model, the effects of cryoprotectants (dimethyl sulfoxide, methanol, and glycerol) with different concentrations (5-15% v/v %), equilibration exposure times (1-60 min), cooling rates (5-40 °C/min), concentrations (4 × 10 4 -4 × 10 6 bundles/ml), buffers (HBSS, PBS and NaCl), and buffer osmolalities (200-400 mOsmol/kg) were investigated. After cooling and thawing, sperm bundles maintained their packed form. A specific protocol was developed (10% dimethyl sulfoxide, 20-min equilibration, 10 °C/min cooling rate, 4 × 10 6 bundles/ml, and 300 mOsmol/kg HBSS). This protocol yielded 89 ± 5% of post-thaw dissociable bundles with 209 ± 10 s of dissociation duration for X. eiseni, 96 ± 9% with 814 ± 14 s for Blackfin Goodea (Goodea atripinni), and 66 ± 2% with 726 ± 25 s for Striped Goodeid (Ataeniobius toweri). This is the first study of cryopreservation of sperm within bundles for livebearing fishes and provides a basis for establishment of germplasm repositories for goodeids and other livebearers. Copyright © 2018. Published by Elsevier Inc.

  4. CHF prediction in rod bundles using round tube data

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Wallen F.; Veloso, Maria A.F.; Pereira, Cláubia; Costa, Antonella L., E-mail: wallenfds@yahoo.com.br, E-mail: mdora@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

    2017-07-01

    The present work concerns the use of 1995 CHF table for uniformly heated round tubes, developed jointly by Canadian and Russian researchers, for the prediction of critical heat fluxes in rod bundles geometries. Comparisons between measured and calculated critical heat fluxes indicate that this table could be applied to rod bundles provided that a suitable correction factor is employed. The tolerance limits associated with the departure from nucleate boiling ratio (DNBR) are evaluated by using statistical analysis. (author)

  5. Page 1 Moduli for bundles over curves - 325 through the ...

    Indian Academy of Sciences (India)

    through the openimmersion (LX &,)(C) s (L x é,)(C). Therefore L x , has a reduction to P and hence seSer. 3.23. Lemma. Let : – S x X be a family of semistable G-bundles. Suppose there exist. (i) a dense open subset T of S. (ii) a reductive subgroup Mo of G of maximal rank and. (iii) a stable Mo-bundle Eo with the following ...

  6. Design and verification of the 'GURI 01' bundle model

    International Nuclear Information System (INIS)

    Benito, G.D.

    1990-01-01

    This work presents a general description of the 'GURI 01' bundle model, designed by INVAP S.E., under international radioactive material transportation regulations, as a B(U) type bundle for international transportation up to a maximum of 350000 Ci of Co60. Moreover, the methodologies used and the results obtained from the structural evaluation of the mechanic essay and from the evaluation of the thermal behaviour under normal or accident conditions are briefly discussed. (Author) [es

  7. Bundle Pricing Decisions for Fresh Products with Quality Deterioration

    OpenAIRE

    Fang, Yan; Jiang, Yiping; Han, Xingxing

    2018-01-01

    How to sell fresh products quickly to decrease the storage cost and to meet customer quality requirement is of vital importance in the food supply chain. Bundling fresh products is an efficient strategy to promote sales and reduce storage pressure of retailers. In this paper, we consider the bundle pricing decisions for homogeneous fresh products with quality deterioration. The value of fresh products with quality deterioration is approximated as an exponential function based on which custome...

  8. On the classification of complex vector bundles of stable rank

    Indian Academy of Sciences (India)

    a classification of all rank r complex vector bundles on X, for stable rank r ≥ n/2. A few partial answers to this question are known. For instance, a classical result of. Wu asserts that any couple of cohomology classes (c1,c2) ∈ H2(X, Z) × H4(X, Z) coincides with c(E) for a vector bundle E, on a basis X of dimension less than ...

  9. Fuel temperature characteristics of the 37-element and CANFLEX fuel bundle

    International Nuclear Information System (INIS)

    Bae, Jun Ho; Rho, Gyu Hong; Park, Joo Hwan

    2009-10-01

    This report describes the fuel temperature characteristics of CANFLEX fuel bundles and 37-element fuel bundles for a different burnup of fuel. The program was consisted for seeking the fuel temperature of fuel bundles of CANFLEX fuel bundles and 37-element fuel bundles by using the method in NUCIRC. Fuel temperature has an increasing pattern with the burnup of fuel for CANFLEX fuel bundles and 37-element fuel bundles. For all the case of burnup, the fuel temperature of CANFLEX fuel bundles has a lower value than that of 37-element fuel bundles. Especially, for the high power channel, the CANFLEX fuel bundles show a lower fuel temperature as much as about 75 degree, and the core averaged fuel temperature has a lower fuel temperature of about 50 degree than that of 37-element fuel bundles. The lower fuel temperature of CANFLEX fuel bundles is expected to enhance the safety by reducing the fuel temperature coefficient. Finally, for each burnup of CANFLEX fuel bundles and 37-element fuel bundles, the equation was present for predicting the fuel temperature of a bundle in terms of a coolant temperature and bundle power

  10. Characterization of Calflagin, a Flagellar Calcium-Binding Protein from Trypanosoma congolense.

    Directory of Open Access Journals (Sweden)

    Brett A Eyford

    2016-04-01

    Full Text Available Identification of species-specific trypanosome molecules is important for laboratory- and field-based research into epidemiology and disease diagnosis. Although Trypanosoma congolense is the most important trypanosome pathogen of cattle in Africa, no species-specific molecules found in infective bloodstream forms (BSF of the parasites have been identified, thus limiting development of diagnostic tests.Immuno-mass spectrometric methods were used to identify a protein that is recognized by a T. congolense-specific monoclonal antibody (mAb Tc6/42.6.4. The identified molecule was expressed as a recombinant protein in E. coli and was tested in several immunoassays for its ability to interact with the mAb. The three dimensional structure of the protein was modeled and compared to crystal- and NMR-structures of the homologous proteins from T. cruzi and T. brucei respectively, in order to examine structural differences leading to the different immunoreactivity of the T. congolense molecule. Enzyme-linked immunosorbent assays (ELISA were used to measure antibodies produced by trypanosome-infected African cattle in order to assess the potential for use of T. congolense calflagin in a serodiagnostic assay.The antigen recognized by the T. congolense-specific mAb Tc6/42.6.4 was identified as a flagellar calcium-binding protein, calflagin. The recombinant molecule showed immunoreactivity with the T. congolense-specific mAb confirming that it is the cognate antigen. Immunofluorescence experiments revealed that Ca2+ modulated the localization of the calflagin molecule in trypanosomes. Structural modelling and comparison with calflagin homologues from other trypanosomatids revealed four non-conserved regions on the surface of the T. congolense molecule that due to differences in surface chemistry and structural topography may form species-specific epitopes. ELISAs using the recombinant calflagin as antigen to detect antibodies in trypanosome-infected cattle

  11. Laser speckle imaging of atherosclerotic plaques through optical fiber bundles

    Science.gov (United States)

    Nadkarni, Seemantini K.; Bouma, Brett E.; Yelin, Dvir; Gulati, Amneet; Tearney, Guillermo J.

    2009-01-01

    Laser speckle imaging (LSI), a new technique that measures an index of plaque viscoelasticity, has been investigated recently to characterize atherosclerotic plaques. These prior studies demonstrated the diagnostic potential of LSI for detecting high-risk plaques and were conducted ex vivo. To conduct intracoronary LSI in vivo, the laser speckle pattern must be transmitted from the coronary wall to the image detector in the presence of cardiac motion. Small-diameter, flexible optical fiber bundles, similar to those used in coronary angioscopy, may be incorporated into an intravascular catheter for this purpose. A key challenge is that laser speckle is influenced by inter-fiber leakage of light, which may be exacerbated during bundle motion. In this study, we tested the capability of optical fiber bundles to transmit laser speckle patterns obtained from atherosclerotic plaques and evaluated the influence of motion on the diagnostic accuracy of fiber bundle-based LSI. Time-varying helium-neon laser speckle images of aortic plaques were obtained while cyclically moving the flexible length of the bundle to mimic coronary motion. Our results show that leached fiber bundles may reliably transmit laser speckle images in the presence of cardiac motion, providing a viable option to conduct intracoronary LSI. PMID:19021396

  12. BiSet: Semantic Edge Bundling with Biclusters for Sensemaking.

    Science.gov (United States)

    Sun, Maoyuan; Mi, Peng; North, Chris; Ramakrishnan, Naren

    2016-01-01

    Identifying coordinated relationships is an important task in data analytics. For example, an intelligence analyst might want to discover three suspicious people who all visited the same four cities. Existing techniques that display individual relationships, such as between lists of entities, require repetitious manual selection and significant mental aggregation in cluttered visualizations to find coordinated relationships. In this paper, we present BiSet, a visual analytics technique to support interactive exploration of coordinated relationships. In BiSet, we model coordinated relationships as biclusters and algorithmically mine them from a dataset. Then, we visualize the biclusters in context as bundled edges between sets of related entities. Thus, bundles enable analysts to infer task-oriented semantic insights about potentially coordinated activities. We make bundles as first class objects and add a new layer, "in-between", to contain these bundle objects. Based on this, bundles serve to organize entities represented in lists and visually reveal their membership. Users can interact with edge bundles to organize related entities, and vice versa, for sensemaking purposes. With a usage scenario, we demonstrate how BiSet supports the exploration of coordinated relationships in text analytics.

  13. Full bundle mechanical cleaning of pressurized water reactor steam generators

    International Nuclear Information System (INIS)

    Reinhardt, M.; Lewis, G.

    1998-01-01

    An improved system for cleaning the upper bundle region of pressurized water reactor steam generators is now available. This system employs high pressure water jets to remove sludge and scale from tube and support plate surfaces and from the broach holes throughout the upper bundle region of steam generators. Benefits of sludge removal can include mitigation of the corrosion process, improvement of plant performance and increased operational stability. The cleaning equipment is installed through existing handholes in the tubesheet region and accesses the upper bundle through flow slots in the tube support plates. The system includes a Bulk Cleaning Head which directs high pressure water jets into the tube bundle, a Vertical Deployment System which delivers and positions the head at the desired locations in the upper bundle region, and a high pressure water pumping and sludge processing system. This paper describes the system, several key components, overall system operation, safety issues, and field use chronology. Specific performance issues that are discussed include the cleaning coverage achieved, the time required to clean a steam generator, and cleaning effectiveness. The Upper Bundle Hydraulic Cleaning System described in this paper is available for use in several types of steam generators

  14. The 3D structure of the apical complex and association with the flagellar apparatus revealed by serial TEM tomography in Psammosa pacifica, a distant relative of the Apicomplexa.

    Science.gov (United States)

    Okamoto, Noriko; Keeling, Patrick J

    2014-01-01

    The apical complex is one of the defining features of apicomplexan parasites, including the malaria parasite Plasmodium, where it mediates host penetration and invasion. The apical complex is also known in a few related lineages, including several non-parasitic heterotrophs, where it mediates feeding behaviour. The origin of the apical complex is unclear, and one reason for this is that in apicomplexans it exists in only part of the life cycle, and never simultaneously with other major cytoskeletal structures like flagella and basal bodies. Here, we used conventional TEM and serial TEM tomography to reconstruct the three dimensional structure of the apical complex in Psammosa pacifica, a predatory relative of apicomplexans and dinoflagellates that retains the archetype apical complex and the flagellar apparatus simultaneously. The P. pacifica apical complex is associated with the gullet and consists of the pseudoconoid, micronemes, and electron dense vesicles. The pseudoconoid is a convex sheet consisting of eight short microtubules, plus a band made up of microtubules that originate from the flagellar apparatus. The flagellar apparatus consists of three microtubular roots. One of the microtubular roots attached to the posterior basal body is connected to bypassing microtubular strands, which are themselves connected to the extension of the pseudoconoid. These complex connections where the apical complex is an extension of the flagellar apparatus, reflect the ancestral state of both, dating back to the common ancestor of apicaomplexans and dinoflagellates.

  15. The flagellar master operon flhDC is a pleiotropic regulator involved in motility and virulence of the fish pathogen Yersinia ruckeri

    Science.gov (United States)

    Aims: To investigate the function of the master flagellar operon flhDC in the fish pathogen Yersinia ruckeri and compare the effect of flhD mutation to a naturally occurring mutation causing loss-of-motility in emergent biotype 2 (BT2) strains. Methods and Results: In this study isogenic Y. ruckeri ...

  16. Helicobacter pylori CheZ(HP) and ChePep form a novel chemotaxis-regulatory complex distinct from the core chemotaxis signaling proteins and the flagellar motor.

    Science.gov (United States)

    Lertsethtakarn, Paphavee; Howitt, Michael R; Castellon, Juan; Amieva, Manuel R; Ottemann, Karen M

    2015-09-01

    Chemotaxis is important for Helicobacter pylori to colonize the stomach. Like other bacteria, H. pylori uses chemoreceptors and conserved chemotaxis proteins to phosphorylate the flagellar rotational response regulator, CheY, and modulate the flagellar rotational direction. Phosphorylated CheY is returned to its non-phosphorylated state by phosphatases such as CheZ. In previously studied cases, chemotaxis phosphatases localize to the cellular poles by interactions with either the CheA chemotaxis kinase or flagellar motor proteins. We report here that the H. pylori CheZ, CheZ(HP), localizes to the poles independently of the flagellar motor, CheA, and all typical chemotaxis proteins. Instead, CheZ(HP) localization depends on the chemotaxis regulatory protein ChePep, and reciprocally, ChePep requires CheZ(HP) for its polar localization. We furthermore show that these proteins interact directly. Functional domain mapping of CheZ(HP) determined the polar localization motif lies within the central domain of the protein and that the protein has regions outside of the active site that participate in chemotaxis. Our results suggest that CheZ(HP) and ChePep form a distinct complex. These results therefore suggest the intriguing idea that some phosphatases localize independently of the other chemotaxis and motility proteins, possibly to confer unique regulation on these proteins' activities. © 2015 John Wiley & Sons Ltd.

  17. Type III secretion systems: the bacterial flagellum and the injectisome

    Science.gov (United States)

    Diepold, Andreas; Armitage, Judith P.

    2015-01-01

    The flagellum and the injectisome are two of the most complex and fascinating bacterial nanomachines. At their core, they share a type III secretion system (T3SS), a transmembrane export complex that forms the extracellular appendages, the flagellar filament and the injectisome needle. Recent advances, combining structural biology, cryo-electron tomography, molecular genetics, in vivo imaging, bioinformatics and biophysics, have greatly increased our understanding of the T3SS, especially the structure of its transmembrane and cytosolic components, the transcriptional, post-transcriptional and functional regulation and the remarkable adaptivity of the system. This review aims to integrate these new findings into our current knowledge of the evolution, function, regulation and dynamics of the T3SS, and to highlight commonalities and differences between the two systems, as well as their potential applications. PMID:26370933

  18. Histones bundle F-actin filaments and affect actin structure.

    Directory of Open Access Journals (Sweden)

    Edna Blotnick

    Full Text Available Histones are small polycationic proteins complexed with DNA located in the cell nucleus. Upon apoptosis they are secreted from the cells and react with extracellular polyanionic compounds. Actin which is a polyanionic protein, is also secreted from necrotic cells and interacts with histones. We showed that both histone mixture (histone type III and the recombinant H2A histone bundles F-actin, increases the viscosity of the F-actin containing solution and polymerizes G-actin. The histone-actin bundles are relatively insensitive to increase of ionic strength, unlike other polycation, histatin, lysozyme, spermine and LL-37 induced F-actin bundles. The histone-actin bundles dissociate completely only in the presence of 300-400 mM NaCl. DNA, which competes with F-actin for histones, disassembles histone induced actin bundles. DNase1, which depolymerizes F- to G-actin, actively unbundles the H2A histone induced but slightly affects the histone mixture induced actin bundles. Cofilin decreases the amount of F-actin sedimented by low speed centrifugation, increases light scattering and viscosity of F-actin-histone mixture containing solutions and forms star like superstructures by copolymerizing G-actin with H2A histone. The results indicate that histones are tightly attached to F-actin by strong electrostatic and hydrophobic forces. Since both histones and F-actin are present in the sputum of patients with cystic fibrosis, therefore, the formation of the stable histone-actin bundles can contribute to the pathology of this disease by increasing the viscosity of the sputum. The actin-histone interaction in the nucleus might affect gene expression.

  19. Histones bundle F-actin filaments and affect actin structure.

    Science.gov (United States)

    Blotnick, Edna; Sol, Asaf; Muhlrad, Andras

    2017-01-01

    Histones are small polycationic proteins complexed with DNA located in the cell nucleus. Upon apoptosis they are secreted from the cells and react with extracellular polyanionic compounds. Actin which is a polyanionic protein, is also secreted from necrotic cells and interacts with histones. We showed that both histone mixture (histone type III) and the recombinant H2A histone bundles F-actin, increases the viscosity of the F-actin containing solution and polymerizes G-actin. The histone-actin bundles are relatively insensitive to increase of ionic strength, unlike other polycation, histatin, lysozyme, spermine and LL-37 induced F-actin bundles. The histone-actin bundles dissociate completely only in the presence of 300-400 mM NaCl. DNA, which competes with F-actin for histones, disassembles histone induced actin bundles. DNase1, which depolymerizes F- to G-actin, actively unbundles the H2A histone induced but slightly affects the histone mixture induced actin bundles. Cofilin decreases the amount of F-actin sedimented by low speed centrifugation, increases light scattering and viscosity of F-actin-histone mixture containing solutions and forms star like superstructures by copolymerizing G-actin with H2A histone. The results indicate that histones are tightly attached to F-actin by strong electrostatic and hydrophobic forces. Since both histones and F-actin are present in the sputum of patients with cystic fibrosis, therefore, the formation of the stable histone-actin bundles can contribute to the pathology of this disease by increasing the viscosity of the sputum. The actin-histone interaction in the nucleus might affect gene expression.

  20. BACTERIAL CONSORTIUM

    Directory of Open Access Journals (Sweden)

    Payel Sarkar

    2013-01-01

    Full Text Available Petroleum aromatic hydrocarbons like benzen e, toluene, ethyl benzene and xylene, together known as BTEX, has almost the same chemical structure. These aromatic hydrocarbons are released as pollutants in th e environment. This work was taken up to develop a solvent tolerant bacterial cons ortium that could degrade BTEX compounds as they all share a common chemical structure. We have isolated almost 60 different types of bacterial strains from different petroleum contaminated sites. Of these 60 bacterial strains almost 20 microorganisms were screene d on the basis of capability to tolerate high concentration of BTEX. Ten differe nt consortia were prepared and the compatibility of the bacterial strains within the consortia was checked by gram staining and BTEX tolerance level. Four successful mi crobial consortia were selected in which all the bacterial strains concomitantly grew in presence of high concentration of BTEX (10% of toluene, 10% of benzene 5% ethyl benzene and 1% xylene. Consortium #2 showed the highest growth rate in pr esence of BTEX. Degradation of BTEX by consortium #2 was monitored for 5 days by gradual decrease in the volume of the solvents. The maximum reduction observed wa s 85% in 5 days. Gas chromatography results also reveal that could completely degrade benzene and ethyl benzene within 48 hours. Almost 90% degradation of toluene and xylene in 48 hours was exhibited by consortium #2. It could also tolerate and degrade many industrial solvents such as chloroform, DMSO, acetonitrile having a wide range of log P values (0.03–3.1. Degradation of aromatic hydrocarbon like BTEX by a solvent tolerant bacterial consortium is greatly significant as it could degrade high concentration of pollutants compared to a bacterium and also reduces the time span of degradation.

  1. Structural Insights into Membrane Targeting by the Flagellar Calcium-binding Protein (FCaBP) a Myristoylated and Palmitoylated Calcium Sensor in Trypanosoma cruzi

    Energy Technology Data Exchange (ETDEWEB)

    J Wingard; J Ladner; M Vanarotti; A Fisher; H Robinson; K Buchanan; D Engman; J Ames

    2011-12-31

    The flagellar calcium-binding protein (FCaBP) of the protozoan Trypanosoma cruzi is targeted to the flagellar membrane where it regulates flagellar function and assembly. As a first step toward understanding the Ca{sup 2+}-induced conformational changes important for membrane-targeting, we report here the x-ray crystal structure of FCaBP in the Ca{sup 2+}-free state determined at 2.2{angstrom} resolution. The first 17 residues from the N terminus appear unstructured and solvent-exposed. Residues implicated in membrane targeting (Lys-19, Lys-22, and Lys-25) are flanked by an exposed N-terminal helix (residues 26-37), forming a patch of positive charge on the protein surface that may interact electrostatically with flagellar membrane targets. The four EF-hands in FCaBP each adopt a 'closed conformation' similar to that seen in Ca{sup 2+}-free calmodulin. The overall fold of FCaBP is closest to that of grancalcin and other members of the penta EF-hand superfamily. Unlike the dimeric penta EF-hand proteins, FCaBP lacks a fifth EF-hand and is monomeric. The unstructured N-terminal region of FCaBP suggests that its covalently attached myristoyl group at the N terminus may be solvent-exposed, in contrast to the highly sequestered myristoyl group seen in recoverin and GCAP1. NMR analysis demonstrates that the myristoyl group attached to FCaBP is indeed solvent-exposed in both the Ca{sup 2+}-free and Ca{sup 2+}-bound states, and myristoylation has no effect on protein structure and folding stability. We propose that exposed acyl groups at the N terminus may anchor FCaBP to the flagellar membrane and that Ca{sup 2+}-induced conformational changes may control its binding to membrane-bound protein targets..

  2. An in vitro biomechanical comparison of anterior cruciate ligament reconstruction: single bundle versus anatomical double bundle techniques

    Directory of Open Access Journals (Sweden)

    Sandra Umeda Sasaki

    2008-01-01

    Full Text Available INTRODUCTION: Anterior cruciate ligament ruptures are frequent, especially in sports. Surgical reconstruction with autologous grafts is widely employed in the international literature. Controversies remain with respect to technique variations as continuous research for improvement takes place. One of these variations is the anatomical double bundle technique, which is performed instead of the conventional single bundle technique. More recently, there has been a tendency towards positioning the two bundles through double bone tunnels in the femur and tibia (anatomical reconstruction. OBJECTIVES: To compare, through biomechanical tests, the practice of anatomical double bundle anterior cruciate ligament reconstruction with a patellar graft to conventional single bundle reconstruction with the same amount of patellar graft in a paired experimental cadaver study. METHODS: Nine pairs of male cadaver knees ranging in age from 44 to 63 years were randomized into two groups: group A (single bundle and group B (anatomical reconstruction. Each knee was biomechanically tested under three conditions: intact anterior cruciate ligament, reconstructed anterior cruciate ligament, and injured anterior cruciate ligament. Maximum anterior dislocation, rigidity, and passive internal tibia rotation were recorded with knees submitted to a 100 N horizontal anterior dislocation force applied to the tibia with the knees at 30, 60 and 90 degrees of flexion. RESULTS: There were no differences between the two techniques for any of the measurements by ANOVA tests. CONCLUSION: The technique of anatomical double bundle reconstruction of the anterior cruciate ligament with bone-patellar tendon-bone graft has a similar biomechanical behavior with regard to anterior tibial dislocation, rigidity, and passive internal tibial rotation.

  3. Pressure Loss across Tube Bundles in Two-phase Flow

    International Nuclear Information System (INIS)

    Sim, Woo Gun; Banzragch, Dagdan

    2016-01-01

    An analytical model was developed by Sim to estimate the two-phase damping ratio for upward two-phase flow perpendicular to horizontal tube bundles. The parameters of two-phase flow, such as void fraction and pressure loss evaluated in the model, were calculated based on existing experimental formulations. However, it is necessary to implement a few improvements in the formulations for the case of tube bundles. For the purpose of the improved formulation, we need more information about the two-phase parameters, which can be found through experimental test. An experiment is performed with a typical normal square array of cylinders subjected to the two-phase flow of air-water in the tube bundles, to calculate the two-phase Euler number and the two-phase friction multiplier. The pitch-to-diameter ratio is 1.35 and the diameter of cylinder is 18mm. Pressure loss along the flow direction in the tube bundles is measured with a pressure transducer and data acquisition system to calculate the two-phase Euler number and the two-phase friction multiplier. The void fraction model by Feenstra et al. is used to estimate the void fraction of the two-phase flow in tube bundles. The experimental results of the two phase friction multiplier and two-phase Euler number for homogeneous and non-homogeneous two-phase flows are compared and evaluated against the analytical results given by Sim's model

  4. Reaction–diffusion model of hair-bundle morphogenesis

    Science.gov (United States)

    Jacobo, Adrian; Hudspeth, A. J.

    2014-01-01

    The hair bundle, an apical specialization of the hair cell composed of several rows of regularly organized stereocilia and a kinocilium, is essential for mechanotransduction in the ear. Its precise organization allows the hair bundle to convert mechanical stimuli to electrical signals; mutations that alter the bundle’s morphology often cause deafness. However, little is known about the proteins involved in the process of morphogenesis and how the structure of the bundle arises through interactions between these molecules. We present a mathematical model based on simple reaction–diffusion mechanisms that can reproduce the shape and organization of the hair bundle. This model suggests that the boundary of the cell and the kinocilium act as signaling centers that establish the bundle’s shape. The interaction of two proteins forms a hexagonal Turing pattern—a periodic modulation of the concentrations of the morphogens, sustained by local activation and long-range inhibition of the reactants—that sets a blueprint for the location of the stereocilia. Finally we use this model to predict how different alterations to the system might impact the shape and organization of the hair bundle. PMID:25313064

  5. Variable recruitment in bundles of miniature pneumatic artificial muscles.

    Science.gov (United States)

    DeLaHunt, Sylvie A; Pillsbury, Thomas E; Wereley, Norman M

    2016-09-13

    The natural compliance and force generation properties of pneumatic artificial muscles (PAMs) allow them to operate like human muscles in anthropomorphic robotic manipulators. Traditionally, manipulators use a single PAM or multiple PAMs actuated in unison in place of a human muscle. However, these standard manipulators can experience significant efficiency losses when operated outside their target performance ranges at low actuation pressures. This study considers the application of a variable recruitment control strategy to a parallel bundle of miniature PAMs as an attempt to mimic the selective recruitment of motor units in a human muscle. Bundles of miniature PAMs are experimentally characterized, their actuation behavior is modeled, and the efficiency gains and losses associated with the application of a variable recruitment control strategy are assessed. This bio-inspired control strategy allows muscle bundles to operate the fewest miniature PAMs necessary to achieve a desired performance objective, improving the muscle bundle's operating efficiency over larger ranges of force generation and displacement. The study also highlights the need for improved PAM fabrication techniques to facilitate the production of identical miniature PAMs for inclusion in muscle bundles.

  6. CANDU fuel bundle deformation modelling with COMSOL multiphysics

    International Nuclear Information System (INIS)

    Bell, J.S.; Lewis, B.J.

    2012-01-01

    Highlights: ► The deformation behaviour of a CANDU fuel bundle was modelled. ► The model has been developed on a commercial finite-element platform. ► Pellet/sheath interaction and end-plate restraint effects were considered. ► The model was benchmarked against the BOW code and a variable-load experiment. - Abstract: A model to describe deformation behaviour of a CANDU 37-element bundle has been developed under the COMSOL Multiphysics finite-element platform. Beam elements were applied to the fuel elements (composed of fuel sheaths and pellets) and endplates in order to calculate the bowing behaviour of the fuel elements. This model is important to help assess bundle-deformation phenomena, which may lead to more restrictive coolant flow through the sub-channels of the horizontally oriented bundle. The bundle model was compared to the BOW code for the occurrence of a dry-out patch, and benchmarked against an out-reactor experiment with a variable load on an outer fuel element.

  7. Enzymatic hydrolysis of biomimetic bacterial cellulose-hemicellulose composites.

    Science.gov (United States)

    Penttilä, Paavo A; Imai, Tomoya; Hemming, Jarl; Willför, Stefan; Sugiyama, Junji

    2018-06-15

    The production of biofuels and other chemicals from lignocellulosic biomass is limited by the inefficiency of enzymatic hydrolysis. Here a biomimetic composite material consisting of bacterial cellulose and wood-based hemicelluloses was used to study the effects of hemicelluloses on the enzymatic hydrolysis with a commercial cellulase mixture. Bacterial cellulose synthesized in the presence of hemicelluloses, especially xylan, was found to be more susceptible to enzymatic hydrolysis than hemicellulose-free bacterial cellulose. The reason for the easier hydrolysis could be related to the nanoscale structure of the substrate, particularly the packing of cellulose microfibrils into ribbons or bundles. In addition, small-angle X-ray scattering was used to show that the average nanoscale morphology of bacterial cellulose remained unchanged during the enzymatic hydrolysis. The reported easier enzymatic hydrolysis of bacterial cellulose produced in the presence of wood-based xylan offers new insights to overcome biomass recalcitrance through genetic engineering. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Bacterial Ecology

    DEFF Research Database (Denmark)

    Fenchel, Tom

    2011-01-01

    Bacterial ecology is concerned with the interactions between bacteria and their biological and nonbiological environments and with the role of bacteria in biogeochemical element cycling. Many fundamental properties of bacteria are consequences of their small size. Thus, they can efficiently exploit...

  9. Bacterial meningitis

    NARCIS (Netherlands)

    Heckenberg, Sebastiaan G. B.; Brouwer, Matthijs C.; van de Beek, Diederik

    2014-01-01

    Bacterial meningitis is a neurologic emergency. Vaccination against common pathogens has decreased the burden of disease. Early diagnosis and rapid initiation of empiric antimicrobial and adjunctive therapy are vital. Therapy should be initiated as soon as blood cultures have been obtained,

  10. Bacterial lipases

    NARCIS (Netherlands)

    Jaeger, Karl-Erich; Ransac, Stéphane; Dijkstra, Bauke W.; Colson, Charles; Heuvel, Margreet van; Misset, Onno

    Many different bacterial species produce lipases which hydrolyze esters of glycerol with preferably long-chain fatty acids. They act at the interface generated by a hydrophobic lipid substrate in a hydrophilic aqueous medium. A characteristic property of lipases is called interfacial activation,

  11. Bacterial Ecology

    DEFF Research Database (Denmark)

    Fenchel, Tom

    2011-01-01

    , the production and oxidation of methane, nitrate reduction and fixation of atmospheric nitrogen are exclusively carried out by different groups of bacteria. Some bacterial species – ‘extremophiles’ – thrive in extreme environments in which no eukaryotic organisms can survive with respect to temperature, salinity...

  12. Bacterial Vaginosis

    Science.gov (United States)

    ... that coats the walls of the vagina Vaginal discharge with an unpleasant or fishlike odor Vaginal pain or itching Burning during urination Doctors are unsure of the incubation period for bacterial vaginosis. How Is the Diagnosis Made? Your child’s pediatrician can make the diagnosis ...

  13. Bacterial stress

    Indian Academy of Sciences (India)

    First page Back Continue Last page Graphics. Bacterial stress. Physicochemical and chemical parameters: temperature, pressure, pH, salt concentration, oxygen, irradiation. Nutritional depravation: nutrient starvation, water shortage. Toxic compounds: Antibiotics, heavy metals, toxins, mutagens. Interactions with other cells: ...

  14. A prospective comparative study of clinical and functional outcomes between anatomic double bundle and single bundle hamstring grafts for arthroscopic anterior cruciate ligament reconstruction.

    Science.gov (United States)

    Morey, Vivek M; Nag, Hira Lal; Chowdhury, Buddhadev; Sankineani, Sukesh Rao; Naranje, Sameer M

    2015-09-01

    Despite a number of studies comparing postoperative stability and function after anatomic single bundle and double bundle anterior cruciate ligament reconstruction, it remains unclear whether double bundle reconstruction has better functional outcome than single bundle anterior cruciate ligament reconstruction. To compare the subjective functional outcome as well as clinical stability in patients treated with either anatomic single bundle or anatomic double bundle anterior cruciate ligament (ACL) reconstruction. We hypothesized that there would be no difference in the postoperative functional outcome and clinical stability between anatomical double bundle anterior cruciate ligament reconstructions when compared to single bundle anterior cruciate ligament reconstructions. We prospectively followed 40 patients out of which, 20 patients were operated for anatomic single bundle ACL reconstruction and other 20 patients underwent anatomic double bundle ACL reconstruction. Patient evaluation using the laxity tests and outcome scales was done preoperatively and at 12, 24 and 48 months after the surgery. Clinical stability was assessed by Lachman test, Pivot shift test and Delhi active test. Functional outcome was assessed by International Knee Documentation Committee (IKDC), Lysholm and Modified Cincinnati scores. Patients in both groups were evaluated at regular intervals for a minimum period of 48 months (mean 51 months, range 48-56 months). For all subjective scores, double bundle group patients reported statistically significant higher scores compared to single bundle group patients. Graded stability results of the Lachman, and Pivot shift tests were significantly higher in the anatomically reconstructed double bundle patient group. We suggest that functional outcome and clinical stability may be better with anatomical double bundle anterior cruciate ligament reconstruction as compared to anatomical single bundle anterior cruciate ligament reconstruction. Copyright

  15. Bacterial Adhesion & Blocking Bacterial Adhesion

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk

    2008-01-01

    reduce or delay bacterial biofilm formation of a range of urinary tract infectious E.coli and Klebsiella isolates. Several other proteinaceous coatings were also found to display anti-adhesive properties, possibly providing a measure for controlling the colonization of implant materials. Several other...... components. These substances may both mediate and stabilize the bacterial biofilm. Finally, several adhesive structures were examined, and a novel physiological biofilm phenotype in E.coli biofilms was characterized, namely cell chain formation. The autotransporter protein, antigen 43, was implicated...

  16. Cationic Amino Acid Uptake Constitutes a Metabolic Regulation Mechanism and Occurs in the Flagellar Pocket of Trypanosoma cruzi

    Science.gov (United States)

    Bouvier, León A.; Cámara, María de los Milagros; Montserrat, Javier; Pereira, Claudio A.

    2012-01-01

    Trypanosomatids' amino acid permeases are key proteins in parasite metabolism since they participate in the adaptation of parasites to different environments. Here, we report that TcAAP3, a member of a Trypanosoma cruzi multigene family of permeases, is a bona fide arginine transporter. Most higher eukaryotic cells incorporate cationic amino acids through a single transporter. In contrast, T. cruzi can recognize and transport cationic amino acids by mono-specific permeases since a 100-fold molar excess of lysine could not affect the arginine transport in parasites that over-express the arginine permease (TcAAP3 epimastigotes). In order to test if the permease activity regulates downstream processes of the arginine metabolism, the expression of the single T. cruzi enzyme that uses arginine as substrate, arginine kinase, was evaluated in TcAAP3 epimastigotes. In this parasite model, intracellular arginine concentration increases 4-folds and ATP level remains constant until cultures reach the stationary phase of growth, with decreases of about 6-folds in respect to the controls. Interestingly, Western Blot analysis demonstrated that arginine kinase is significantly down-regulated during the stationary phase of growth in TcAAP3 epimastigotes. This decrease could represent a compensatory mechanism for the increase in ATP consumption as a consequence of the displacement of the reaction equilibrium of arginine kinase, when the intracellular arginine concentration augments and the glucose from the medium is exhausted. Using immunofluorescence techniques we also determined that TcAAP3 and the specific lysine transporter TcAAP7 co-localize in a specialized region of the plasma membrane named flagellar pocket, staining a single locus close to the flagellar pocket collar. Taken together these data suggest that arginine transport is closely related to arginine metabolism and cell energy balance. The clinical relevance of studying trypanosomatids' permeases relies on the

  17. Interaction between the flagellar pocket collar and the hook complex via a novel microtubule-binding protein in Trypanosoma brucei.

    Directory of Open Access Journals (Sweden)

    Anna Albisetti

    2017-11-01

    Full Text Available Trypanosoma brucei belongs to a group of unicellular, flagellated parasites that are responsible for human African trypanosomiasis. An essential aspect of parasite pathogenicity is cytoskeleton remodelling, which occurs during the life cycle of the parasite and is accompanied by major changes in morphology and organelle positioning. The flagellum originates from the basal bodies and exits the cell body through the flagellar pocket (FP but remains attached to the cell body via the flagellum attachment zone (FAZ. The FP is an invagination of the pellicular membrane and is the sole site for endo- and exocytosis. The FAZ is a large complex of cytoskeletal proteins, plus an intracellular set of four specialised microtubules (MtQ that elongate from the basal bodies to the anterior end of the cell. At the distal end of the FP, an essential, intracellular, cytoskeletal structure called the flagellar pocket collar (FPC circumvents the flagellum. Overlapping the FPC is the hook complex (HC (a sub-structure of the previously named bilobe that is also essential and is thought to be involved in protein FP entry. BILBO1 is the only functionally characterised FPC protein and is necessary for FPC and FP biogenesis. Here, we used a combination of in vitro and in vivo approaches to identify and characterize a new BILBO1 partner protein-FPC4. We demonstrate that FPC4 localises to the FPC, the HC, and possibly to a proximal portion of the MtQ. We found that the C-terminal domain of FPC4 interacts with the BILBO1 N-terminal domain, and we identified the key amino acids required for this interaction. Interestingly, the FPC4 N-terminal domain was found to bind microtubules. Over-expression studies highlight the role of FPC4 in its association with the FPC, HC and FPC segregation. Our data suggest a tripartite association between the FPC, the HC and the MtQ.

  18. Rheology of semiflexible bundle networks with transient linkers.

    Science.gov (United States)

    Müller, Kei W; Bruinsma, Robijn F; Lieleg, Oliver; Bausch, Andreas R; Wall, Wolfgang A; Levine, Alex J

    2014-06-13

    We present a theoretical and computational analysis of the rheology of networks made up of bundles of semiflexible filaments bound by transient cross-linkers. Such systems are ubiquitous in the cytoskeleton and can be formed in vitro using filamentous actin and various cross-linkers. We find that their high-frequency rheology is characterized by a scaling behavior that is quite distinct from that of networks of the well-studied single semiflexible filaments. This regime can be understood theoretically in terms of a length-scale-dependent bending modulus for bundles. Next, we observe new dissipative dynamics associated with the shear-induced disruption of the network at intermediate frequencies. Finally, at low frequencies, we encounter a region of non-Newtonian rheology characterized by power-law scaling. This regime is dominated by bundle dissolution and large-scale rearrangements of the network driven by equilibrium thermal fluctuations.

  19. Single-Phase Bundle Flows Including Macroscopic Turbulence Model

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Jun; Yoon, Han Young [KAERI, Daejeon (Korea, Republic of); Yoon, Seok Jong; Cho, Hyoung Kyu [Seoul National University, Seoul (Korea, Republic of)

    2016-05-15

    To deal with various thermal hydraulic phenomena due to rapid change of fluid properties when an accident happens, securing mechanistic approaches as much as possible may reduce the uncertainty arising from improper applications of the experimental models. In this study, the turbulence mixing model, which is well defined in the subchannel analysis code such as VIPRE, COBRA, and MATRA by experiments, is replaced by a macroscopic k-e turbulence model, which represents the aspect of mathematical derivation. The performance of CUPID with macroscopic turbulence model is validated against several bundle experiments: CNEN 4x4 and PNL 7x7 rod bundle tests. In this study, the macroscopic k-e model has been validated for the application to subchannel analysis. It has been implemented in the CUPID code and validated against CNEN 4x4 and PNL 7x7 rod bundle tests. The results showed that the macroscopic k-e turbulence model can estimate the experiments properly.

  20. Designing cooperatively folded abiotic uni- and multimolecular helix bundles

    Science.gov (United States)

    de, Soumen; Chi, Bo; Granier, Thierry; Qi, Ting; Maurizot, Victor; Huc, Ivan

    2018-01-01

    Abiotic foldamers, that is foldamers that have backbones chemically remote from peptidic and nucleotidic skeletons, may give access to shapes and functions different to those of peptides and nucleotides. However, design methodologies towards abiotic tertiary and quaternary structures are yet to be developed. Here we report rationally designed interactional patterns to guide the folding and assembly of abiotic helix bundles. Computational design facilitated the introduction of hydrogen-bonding functionalities at defined locations on the aromatic amide backbones that promote cooperative folding into helix-turn-helix motifs in organic solvents. The hydrogen-bond-directed aggregation of helices not linked by a turn unit produced several thermodynamically and kinetically stable homochiral dimeric and trimeric bundles with structures that are distinct from the designed helix-turn-helix. Relative helix orientation within the bundles may be changed from parallel to tilted on subtle solvent variations. Altogether, these results prefigure the richness and uniqueness of abiotic tertiary structure behaviour.

  1. Criticality calculation for cluster fuel bundles using grey Dancoff factor

    International Nuclear Information System (INIS)

    Hyeong Heon Kim; Nam Zin Cho

    1999-01-01

    This paper applies the grey Dancoff factor calculated by Monte Carlo method to the criticality calculation for cluster fuel bundles. Dancoff factors for five symmetrically different pin positions of CANDU37 and CANFLEX fuel bundles in full three-dimensional geometry are calculated by Monte Carlo method. The concept of equivalent Dancoff factor is introduced to use the grey Dancoff factor in the resonance calculation based on equivalence theorem. The equivalent Dancoff factor which is based on the realistic model produces an exact fuel collision probability and can be used in the resonance calculation just as the black Dancoff factor. The infinite multiplication factors based on the black Dancoff factors calculated by collision probability or Monte Carlo method are overestimated by about 2 mk for normal condition and 4 mk for void condition of CANDU37 and CANFLEX fuel bundles in comparison with those based on the equivalent Dancoff factors

  2. Symposium on Singularities, Representation of Algebras, and Vector Bundles

    CERN Document Server

    Trautmann, Günther

    1987-01-01

    It is well known that there are close relations between classes of singularities and representation theory via the McKay correspondence and between representation theory and vector bundles on projective spaces via the Bernstein-Gelfand-Gelfand construction. These relations however cannot be considered to be either completely understood or fully exploited. These proceedings document recent developments in the area. The questions and methods of representation theory have applications to singularities and to vector bundles. Representation theory itself, which had primarily developed its methods for Artinian algebras, starts to investigate algebras of higher dimension partly because of these applications. Future research in representation theory may be spurred by the classification of singularities and the highly developed theory of moduli for vector bundles. The volume contains 3 survey articles on the 3 main topics mentioned, stressing their interrelationships, as well as original research papers.

  3. Stress generation by myosin minifilaments in actin bundles.

    Science.gov (United States)

    Dasanayake, Nilushi L; Carlsson, Anders E

    2013-06-01

    Forces and stresses generated by the action of myosin minifilaments are analyzed in idealized computer-generated actin bundles, and compared to results for isotropic actin networks. The bundles are generated as random collections of actin filaments in two dimensions with constrained orientations, crosslinked and attached to two fixed walls. Myosin minifilaments are placed on actin filament pairs and allowed to move and deform the network so that it exerts forces on the walls. The vast majority of simulation runs end with contractile minifilament stress, because minifilaments rotate into energetically stable contractile configurations. This process is aided by the bending and stretching of actin filaments, which accomodate minifilament rotation. Stresses for bundles are greater than those for isotropic networks, and antiparallel filaments generate more tension than parallel filaments. The forces transmitted by the actin network to the walls of the simulation cell often exceed the tension in the minifilament itself.

  4. Betti numbers of graded modules and cohomology of vector bundles

    Science.gov (United States)

    Eisenbud, David; Schreyer, Frank-Olaf

    2009-07-01

    In the remarkable paper Graded Betti numbers of Cohen-Macaulay modules and the multiplicity conjecture, Mats Boij and Jonas Soederberg conjectured that the Betti table of a Cohen-Macaulay module over a polynomial ring is a positive linear combination of Betti tables of modules with pure resolutions. We prove a strengthened form of their conjectures. Applications include a proof of the Multiplicity Conjecture of Huneke and Srinivasan and a proof of the convexity of a fan naturally associated to the Young lattice. With the same tools we show that the cohomology table of any vector bundle on projective space is a positive rational linear combination of the cohomology tables of what we call supernatural vector bundles. Using this result we give new bounds on the slope of a vector bundle in terms of its cohomology.

  5. System for supporting bundled tube segments within a combustor

    Energy Technology Data Exchange (ETDEWEB)

    Melton, Patrick Benedict

    2016-03-01

    A system for supporting bundled tube segments within a combustor includes an annular sleeve that extends circumferentially and axially within the combustor, a support lug that extends radially inward from the annular sleeve and an annular support frame that is disposed within the annular sleeve. The annular support frame includes an inner ring portion, an outer ring portion and a plurality of spokes that extend radially between the inner and outer ring portions. The inner ring portion, the outer ring portion and the plurality of spokes define an annular array of openings for receiving a respective bundled tube segment. The inner ring portion is connected to each bundled tube segment and the outer ring portion is coupled to the support lug.

  6. The Analysis of SBWR Critical Power Bundle Using Cobrag Code

    Directory of Open Access Journals (Sweden)

    Yohannes Sardjono

    2013-03-01

    Full Text Available The coolant mechanism of SBWR is similar with the Dodewaard Nuclear Power Plant (NPP in the Netherlands that first went critical in 1968. The similarity of both NPP is cooled by natural convection system. These coolant concept is very related with same parameters on fuel bundle design especially fuel bundle length, core pressure drop and core flow rate as well as critical power bundle. The analysis was carried out by using COBRAG computer code. COBRAG computer code is GE Company proprietary. Basically COBRAG computer code is a tool to solve compressible three-dimensional, two fluid, three field equations for two phase flow. The three fields are the vapor field, the continuous liquid field, and the liquid drop field. This code has been applied to analyses model flow and heat transfer within the reactor core. This volume describes the finitevolume equations and the numerical solution methods used to solve these equations. This analysis of same parameters has been done i.e.; inlet sub cooling 20 BTU/lbm and 40 BTU/lbm, 1000 psi pressure and R-factor is 1.038, mass flux are 0.5 Mlb/hr.ft2, 0.75 Mlb/hr.ft2, 1.00 Mlb/hr.ft2 and 1.25 Mlb/hr.ft2. Those conditions based on history operation of some type of the cell fuel bundle line at GE Nuclear Energy. According to the results, it can be concluded that SBWR critical power bundle is 10.5 % less than current BWR critical power bundle with length reduction of 12 ft to 9 ft.

  7. Reaction–diffusion model of hair-bundle morphogenesis

    OpenAIRE

    Jacobo, Adrian; Hudspeth, A. J.

    2014-01-01

    Our senses of hearing and balance rest upon the activity of hair cells, the ear’s sensory receptors. Each hair cell detects mechanical stimuli with its hair bundle, an organelle comprising 10–300 cylindrical, actin-filled stereocilia. A bundle’s structure is highly stereotyped: the stereocilia stand erect in a regular, hexagonal array and display a monotonic gradient in length along one axis. This precise organization is key to the operation of the hair bundle: mutations that disturb the morp...

  8. Some Remarks on Group Bundles and C*-dynamical systems

    OpenAIRE

    Vasselli, Ezio

    2003-01-01

    We introduce the notion of fibred action of a group bundle on a C(X)-algebra. By using such a notion, a characterization in terms of induced C*-bundles is given for C*-dynamical systems such that the relative commutant of the fixed-point algebra is minimal (i.e., it is generated by the centre of the given C*-algebra and the centre of the fixed-point algebra). A class of examples in the setting of the Cuntz algebra is given, and connections with superselection structures with nontrivial centre...

  9. Some Remarks on Group Bundles and C* Dynamical Systems

    Science.gov (United States)

    Vasselli, Ezio

    2007-08-01

    We introduce the notion of fibred action of a group bundle on a C(X)-algebra. By using such a notion, a characterization in terms of induced C*-bundles is given for C*-dynamical systems such that the relative commutant of the fixed-point C*-algebra is minimal (i.e., it is generated by the centre of the given C*-algebra and the centre of the fixed-point C*-algebra). A class of examples in the setting of the Cuntz algebra is given, and connections with superselection structures with nontrivial centre are discussed.

  10. Cellulosic Fibers: Effect of Processing on Fiber Bundle Strength

    DEFF Research Database (Denmark)

    Thygesen, Anders; Madsen, Bo; Thomsen, Anne Belinda

    2011-01-01

    A range of differently processed cellulosic fibers from flax and hemp plants were investigated to study the relation between processing of cellulosic fibers and fiber bundle strength. The studied processing methods are applied for yarn production and include retting, scutching, carding, and cotto......A range of differently processed cellulosic fibers from flax and hemp plants were investigated to study the relation between processing of cellulosic fibers and fiber bundle strength. The studied processing methods are applied for yarn production and include retting, scutching, carding...

  11. Bacterial lipases

    OpenAIRE

    Jaeger, Karl-Erich; Ransac, Stéphane; Dijkstra, Bauke W.; Colson, Charles; Heuvel, Margreet van; Misset, Onno

    1994-01-01

    Many different bacterial species produce lipases which hydrolyze esters of glycerol with preferably long-chain fatty acids. They act at the interface generated by a hydrophobic lipid substrate in a hydrophilic aqueous medium. A characteristic property of lipases is called interfacial activation, meaning a sharp increase in lipase activity observed when the substrate starts to form an emulsion, thereby presenting to the enzyme an interfacial area. As a consequence, the kinetics of a lipase rea...

  12. Flexible Hinges in Bacterial Chemoreceptors.

    Science.gov (United States)

    Akkaladevi, Narahari; Bunyak, Filiz; Stalla, David; White, Tommi A; Hazelbauer, Gerald L

    2018-03-01

    Transmembrane bacterial chemoreceptors are extended, rod-shaped homodimers with ligand-binding sites at one end and interaction sites for signaling complex formation and histidine kinase control at the other. There are atomic-resolution structures of chemoreceptor fragments but not of intact, membrane-inserted receptors. Electron tomography of in vivo signaling complex arrays lack distinct densities for chemoreceptor rods away from the well-ordered base plate region, implying structural heterogeneity. We used negative staining, transmission electron microscopy, and image analysis to characterize the molecular shapes of intact homodimers of the Escherichia coli aspartate receptor Tar rendered functional by insertion into nanodisc-provided E. coli lipid bilayers. Single-particle analysis plus tomography of particles in a three-dimensional matrix revealed two bend loci in the chemoreceptor cytoplasmic domain, (i) a short, two-strand gap between the membrane-proximal, four-helix-bundle HAMP (histidine kinases, adenylyl cyclases, methyl-accepting chemoreceptors, and phosphatases) domain and the membrane-distal, four-helix coiled coil and (ii) aligned glycines in the extended, four-helix coiled coil, the position of a bend noted in the previous X-ray structure of a receptor fragment. Our images showed HAMP bends from 0° to ∼13° and glycine bends from 0° to ∼20°, suggesting that the loci are flexible hinges. Variable hinge bending explains indistinct densities for receptor rods outside the base plate region in subvolume averages of chemotaxis arrays. Bending at flexible hinges was not correlated with the chemoreceptor signaling state. However, our analyses showed that chemoreceptor bending avoided what would otherwise be steric clashes between neighboring receptors that would block the formation of core signaling complexes and chemoreceptor arrays. IMPORTANCE This work provides new information about the shape of transmembrane bacterial chemoreceptors, crucial

  13. EXTERNAL VERIFICATION OF THE BUNDLE ADJUSTMENT IN PHOTOGRAMMETRIC SOFTWARE USING THE DAMPED BUNDLE ADJUSTMENT TOOLBOX

    Directory of Open Access Journals (Sweden)

    N. Börlin

    2016-06-01

    Full Text Available The aim of this paper is to investigate whether the Matlab-based Damped Bundle Adjustment Toolbox (DBAT can be used to provide independent verification of the BA computation of two popular software—PhotoModeler (PM and PhotoScan (PS. For frame camera data sets with lens distortion, DBAT is able to reprocess and replicate subsets of PM results with high accuracy. For lens-distortion-free data sets, DBAT can furthermore provide comparative results between PM and PS. Data sets for the discussed projects are available from the authors. The use of an external verification tool such as DBAT will enable users to get an independent verification of the computations of their software. In addition, DBAT can provide computation of quality parameters such as estimated standard deviations, correlation between parameters, etc., something that should be part of best practice for any photogrammetric software. Finally, as the code is free and open-source, users can add computations of their own.

  14. Multicell slug flow heat transfer analysis of finite LMFBR bundles

    Energy Technology Data Exchange (ETDEWEB)

    Yeung, M.K.; Wolf, L.

    1978-12-01

    An analytical two-dimensional, multi-region, multi-cell technique has been developed for the thermal analysis of LMFBR rod bundles. Local temperature fields of various unit cells were obtained for 7, 19, and 37-rod bundles of different geometries and power distributions. The validity of the technique has been verified by its excellent agreement with the THTB calculational result. By comparing the calculated fully-developed circumferential clad temperature distribution with those of the experimental measurements, an axial correction factor has been derived to account for the entrance effect for practical considerations. Moreover, the knowledge of the local temperature field of the rod bundle leads to the determination of the effective mixing lengths L/sub ij/ for adjacent subchannels of various geometries. It was shown that the implementation of the accurately determined L/sub ij/ into COBRA-IIIC calculations has fairly significant effects on intersubchannel mixing. In addition, a scheme has been proposed to couple the 2-D distributed and lumped parameter calculation by COBRA-IIIC such that the entrance effect can be implanted into the distributed parameter analysis. The technique has demonstrated its applicability for a 7-rod bundle and the results of calculation were compared to those of three-dimensional analyses and experimental measurements.

  15. Rigidity of minimal submanifolds with flat normal bundle

    Indian Academy of Sciences (India)

    Let M n ( n ≥ 3 ) be an -dimensional complete immersed n − 2 n -superstable minimal submanifold in an ( n + p ) -dimensional Euclidean space R n + p with flat normal bundle. We prove that if the second fundamental form of satisfies some decay conditions, then is an affine plane or a catenoid in some Euclidean ...

  16. Vranceanu connections and foliations with bundle-like metrics

    Indian Academy of Sciences (India)

    Home; Journals; Proceedings – Mathematical Sciences; Volume 118; Issue 1. Vrănceanu Connections and Foliations with Bundle-Like Metrics. Aurel Bejancu ... Author Affiliations. Aurel Bejancu1 Hani Reda Farran1. Department of Mathematics and Computer Science, Kuwait University, P. O. Box 5969, Safat 13060, Kuwait ...

  17. Quillen bundle and geometric prequantization of non-abelian ...

    Indian Academy of Sciences (India)

    Toepliz operators out of projections to holomorphic sections of the prequatum line bundle. (when the latter makes sense) and Berezin–Toeplitz deformation quantization has been carried out by Andersen in [1, 2]. The non-abelian vortices were first introduced in the literature perhaps by Bradlow [8]. The non-abelian vortex ...

  18. Hydraulic testing of accelerator-production-of-tritium rod bundles

    International Nuclear Information System (INIS)

    Spatz, T.L.; Siebe, D.A.

    1999-01-01

    Hydraulic tests have been performed on small pitch-to-diameter-ratio rod bundles using light water (1.7 Tr < 13,000). Also presented is the comparison of the overall rung pressure drop to a solution based on hydraulic-resistance handbook calculations

  19. Self-adjointness of the Gaffney Laplacian on Vector Bundles

    International Nuclear Information System (INIS)

    Bandara, Lashi; Milatovic, Ognjen

    2015-01-01

    We study the Gaffney Laplacian on a vector bundle equipped with a compatible metric and connection over a Riemannian manifold that is possibly geodesically incomplete. Under the hypothesis that the Cauchy boundary is polar, we demonstrate the self-adjointness of this Laplacian. Furthermore, we show that negligible boundary is a necessary and sufficient condition for the self-adjointness of this operator

  20. Frobenius Pull Backs of Vector Bundles in Higher Dimensions

    Indian Academy of Sciences (India)

    We prove that for a smooth projective variety of arbitrary dimension and for a vector bundle over , the Harder–Narasimhan filtration of a Frobenius pull back of is a refinement of the Frobenius pull back of the Harder–Narasimhan filtration of , provided there is a lower bound on the characteristic (in terms of rank of ...

  1. On the classification of complex vector bundles of stable rank

    Indian Academy of Sciences (India)

    This classification becomes more effective on generalized flag manifolds, where the Lie algebra formalism and concrete integrability conditions describe in constructive terms the Chern classes of a vector bundle. ... Since deceased; Mathematics Department, University of California, Santa Barbara, CA 93106, USA ...

  2. Frobenius pull backs of vector bundles in higher dimensions

    Indian Academy of Sciences (India)

    ... of a Frobenius pull back of is a refinement of the Frobenius pull back of the Harder–Narasimhan filtration of , provided there is a lower bound on the characteristic (in terms of rank of and the slope of the destabilizing sheaf of the cotangent bundle of ). We also recall some examples, due to Raynaud and Monsky, ...

  3. MYOCARDIAL DEFORMATION AND COMPLETE LEFT BUNDLE BRANCH BLOCK

    Directory of Open Access Journals (Sweden)

    E. N. Pavlyukova

    2015-12-01

    Full Text Available Tissue Doppler imaging is evolving as a useful echocardiographic tool for quantitative assessment of left ventricular systolic and diastolic function. Over the last 10 years, myocardial deformation imaging has become possible initially with tissue Doppler , and more recently with myocardial speckle-tracking using 2D echocardiography. Unlike simple tissue velocity measurements, deformation measurements are specific for the region of interest. Strain rate or strain measurements have been used as sensitive indicators for subclinical diseases, and it is the most widely used tool to assess mechanical dyssynchrony. Left bundle branch block is a frequent, etiologically heterogeneous, clinically hostile and diagnostically challenging entity. About 2% of patients underwent cardiac stress testing show stable or intermittent left bundle branch block. Presence of left bundle branch block is associated with a lower and slower diastolic coronary flow velocity especially during hyperemia. Stress echocardiography is the best option for the diagnosis of ischemic heart disease, albeit specificity and sensitivity reduce in patients with left bundle branch block in the territory of left anterior descending artery in presence of initial septum dyskinesia.

  4. Vibrations of turbine blades bundles model with rubber damping elements

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk

    2014-01-01

    Roč. 21, č. 1 (2014), s. 45-52 ISSN 1802-1484 R&D Projects: GA ČR GA101/09/1166 Institutional support: RVO:61388998 Keywords : mathematical model * bundle of five blades * rubber damping elements * eigenmodes Subject RIV: BI - Acoustics http://www.engineeringmechanics.cz/obsahy.html?R=21&C=1

  5. Geometric Description of Fibre Bundle Surface for Birkhoff System

    International Nuclear Information System (INIS)

    Li-Mei, Cao; Hua-Fei, Sun; Zhen-Ning, Zhang

    2009-01-01

    A fibre bundle surface for the Birkhoff system is constructed. The metric and the Riemannian connection of the surface are defined and the representation of the Gaussian curvature of this surface is presented. Finally, three examples for the Birkhoff system are given to illustrate our results. (general)

  6. A novel microbond bundle pullout technique to evaluate the ...

    Indian Academy of Sciences (India)

    In the present investigation, the interfacialproperties of carbon fibre/epoxy composites viz., matrix shrinkage pressure, interfacial frictional stress, interfacial shear stress and coefficient of friction were evaluated through a novel microbond bundle pullout test. This test is different from the single fibre pull out, fibre fragmentation ...

  7. Subanalytic Bundles and Tubular Neighbourhoods of Zero-Loci

    Indian Academy of Sciences (India)

    We introduce the natural and fairly general notion of a subanalytic bundle (with a finite dimensional vector space of sections) on a subanalytic subset of a real analytic manifold , and prove that when is compact, there is a Baire subset of sections in whose zero-loci in have tubular neighbourhoods, ...

  8. Assembly and operation experience of EVA II steam reforming bundle

    International Nuclear Information System (INIS)

    Niessen, H.F.; Harth, R.; Kesel, W.

    1984-01-01

    The main test component of the experimental facility EVA-II/ADAM-II is a helium heated steam reformer bundle with 30 tubes. The tubes are filled with a catalyst of raschig ring type. The main test of the component were related to the power dependence. A series of experiment dealt with the influence of steam/methane ratio on the carbon deposit formation

  9. Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction

    NARCIS (Netherlands)

    Hofbauer, Marcus; Muller, Bart; Wolf, Megan; Forsythe, Brian; Fu, Freddie H.

    2013-01-01

    Over the past decade, intense research of the function of the 2 distinct bundles, the anteromedial and posterolateral, of the anterior cruciate ligament (ACL) has led to pronounced changes in the technical concepts of ACL reconstruction. Recently, the renewed focus of ACL reconstruction has been to

  10. The fibre bundle anatomy of human cruciate ligaments

    NARCIS (Netherlands)

    Mommersteeg, T. J.; Kooloos, J. G.; Blankevoort, L.; Kauer, J. M.; Huiskes, R.; Roeling, F. Q.

    1995-01-01

    The cruciate ligaments of the knee consist of numerous fascicles, groups of which comprise fibre bundles. The stabilising function of these ligaments is established by changes in the lengths and orientations of the fascicles. Understanding the function of knee ligaments thus requires an

  11. Incremental implicit learning of bundles of statistical patterns.

    Science.gov (United States)

    Qian, Ting; Jaeger, T Florian; Aslin, Richard N

    2016-12-01

    Forming an accurate representation of a task environment often takes place incrementally as the information relevant to learning the representation only unfolds over time. This incremental nature of learning poses an important problem: it is usually unclear whether a sequence of stimuli consists of only a single pattern, or multiple patterns that are spliced together. In the former case, the learner can directly use each observed stimulus to continuously revise its representation of the task environment. In the latter case, however, the learner must first parse the sequence of stimuli into different bundles, so as to not conflate the multiple patterns. We created a video-game statistical learning paradigm and investigated (1) whether learners without prior knowledge of the existence of multiple "stimulus bundles" - subsequences of stimuli that define locally coherent statistical patterns - could detect their presence in the input and (2) whether learners are capable of constructing a rich representation that encodes the various statistical patterns associated with bundles. By comparing human learning behavior to the predictions of three computational models, we find evidence that learners can handle both tasks successfully. In addition, we discuss the underlying reasons for why the learning of stimulus bundles occurs even when such behavior may seem irrational. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. The Roach muscle bundle and umbilical cord coiling

    NARCIS (Netherlands)

    de Laat, Monique W. M.; Nikkels, Peter G. J.; Franx, Arie; Visser, Gerard H. A.

    2007-01-01

    To determine if presence of the Roach muscle, a small muscle bundle lying just beside the umbilical artery, contributes to umbilical cord coiling. 251 umbilical cords were examined. The umbilical coiling index (UCI) was calculated as the number of coils divided by the cord length in cm. Cords were

  13. Signal Integrity Analysis in Single and Bundled Carbon Nanotube Interconnects

    International Nuclear Information System (INIS)

    Majumder, M.K.; Pandya, N.D.; Kaushik, B.K.; Manhas, S.K.

    2013-01-01

    Carbon nanotube (CN T) can be considered as an emerging interconnect material in current nano scale regime. They are more promising than other interconnect materials such as Al or Cu because of their robustness to electromigration. This research paper aims to address the crosstalk-related issues (signal integrity) in interconnect lines. Different analytical models of single- (SWCNT), double- (DWCNT), and multiwalled CNTs (MWCNT) are studied to analyze the crosstalk delay at global interconnect lengths. A capacitively coupled three-line bus architecture employing CMOS driver is used for accurate estimation of crosstalk delay. Each line in bus architecture is represented with the equivalent RLC models of single and bundled SWCNT, DWCNT, and MWCNT interconnects. Crosstalk delay is observed at middle line (victim) when it switches in opposite direction with respect to the other two lines (aggressors). Using the data predicted by ITRS 2012, a comparative analysis on the basis of crosstalk delay is performed for bundled SWCNT/DWCNT and single MWCNT interconnects. It is observed that the overall crosstalk delay is improved by 40.92% and 21.37% for single MWCNT in comparison to bundled SWCNT and bundled DWCNT interconnects, respectively.

  14. Metallic/semiconducting ratio of carbon nanotubes in a bundle ...

    Indian Academy of Sciences (India)

    SWCNTs) in a bundle by resonant Raman spectroscopy. The calculation has been done for the three peak positions in radial breathing mode (RBM) spectra obtained by using a laser excitation wavelength () of 633 nm from He–Ne laser on ...

  15. Parabolic bundles on algebraic surfaces I – The Donaldson ...

    Indian Academy of Sciences (India)

    [17] and [18]) that the underlying geometry and topology of the moduli space of parabolic bundles of rank two and trivial determinant have very interesting applications arising out of a generalization of Donaldson polynomials defined from these moduli spaces. These moduli spaces and their compactifications were studied.

  16. Self-organization of myosin II in reconstituted actomyosin bundles.

    Science.gov (United States)

    Stachowiak, Matthew R; McCall, Patrick M; Thoresen, Todd; Balcioglu, Hayri E; Kasiewicz, Lisa; Gardel, Margaret L; O'Shaughnessy, Ben

    2012-09-19

    Cells assemble a variety of bundled actomyosin structures in the cytoskeleton for activities such as cell-shape regulation, force production, and cytokinesis. Although these linear structures exhibit varied architecture, two common organizational themes are a punctate distribution of myosin II and distinct patterns of actin polarity. The mechanisms that cells use to assemble and maintain these organizational features are poorly understood. To study these, we reconstituted actomyosin bundles in vitro that contained only actin filaments and myosin II. Upon addition of ATP, the bundles contracted and the uniformly distributed myosin spontaneously reorganized into discrete clusters. We developed a mathematical model in which the motion of myosin II filaments is governed by the polarities of the actin filaments with which they interact. The model showed that the assembly of myosins into clusters is driven by their tendency to migrate to locations with zero net actin filament polarity. With no fitting parameters, the predicted distribution of myosin cluster separations was in close agreement with our experiments, including a -3/2 power law decay for intermediate length scales. Thus, without an organizing template or accessory proteins, a minimal bundle of actin and myosin has the inherent capacity to self-organize into a heterogeneous banded structure. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  17. Semifinite Bundles and the Chevalley-Weil Formula

    Indian Academy of Sciences (India)

    34

    ) of finite bundles on X and he proved that it is a neutral Tannakian category over k together with a neutral fiber functor ωx : E ↦→ x. ∗. E induced by a rational point x ∈ X(k) [2]. By Tannaka duality, there exists an affine group scheme πN.

  18. Local heat transfer coefficient for turbulent flow in rod bundles

    International Nuclear Information System (INIS)

    Fernandez y Fernandez, E.; Carajilescov, P.

    1983-03-01

    The correlation of the local heat transfer coefficients in heated triangular array of rod bundles, in terms of the flow hydrodynamic parameters is presented. The analysis is made first for fluid with Prandtl numbers varying from moderated to high (Pr>0.2), and then extended to fluids with low Prandtl numbers (0.004 [pt

  19. Bohr--Sommerfeld Lagrangians of moduli spaces of Higgs bundles

    DEFF Research Database (Denmark)

    Biswas, Indranil; Gammelgaard, Niels Leth; Logares, Marina

    Let $X$ be a compact connected Riemann surface of genus at least two. Let $M_H(r,d)$ denote the moduli space of semistable Higgs bundles on $X$ of rank $r$ and degree $d$. We prove that the compact complex Bohr-Sommerfeld Lagrangians of $M_H(r,d)$ are precisely the irreducible components of the n...

  20. Bacterial mitosis

    DEFF Research Database (Denmark)

    Møller-Jensen, Jakob; Borch, Jonas; Dam, Mette

    2003-01-01

    Bacterial DNA segregation takes place in an active and ordered fashion. In the case of Escherichia coli plasmid R1, the partitioning system (par) separates paired plasmid copies and moves them to opposite cell poles. Here we address the mechanism by which the three components of the R1 par system...... movement is powered by insertional polymerization of ParM. Consistently, we find that segregating plasmids are positioned at the ends of extending ParM filaments. Thus, the process of R1 plasmid segregation in E. coli appears to be mechanistically analogous to the actin-based motility operating...

  1. Lower complication rates for cranioplasty with peri-operative bundle.

    Science.gov (United States)

    Le, Catherine; Guppy, Kern H; Axelrod, Yekaterina V; Hawk, Mark W; Silverthorn, James; Inacio, Maria C; Akins, Paul T

    2014-05-01

    The overall benefits of craniectomy must include procedural risks from cranioplasty. Cranioplasty carries a high risk of surgical site infections (SSI) particularly with antibiotic resistant bacteria. The goal of this study was to measure the effect of a cranioplasty bundle on peri-operative complications. The authors queried a prospective, inpatient neurosurgery database at Kaiser Sacramento Medical Center for craniectomy and cranioplasty over a 7 year period. 57 patients who underwent cranioplasties were identified. A retrospective chart review was completed for complications, including surgical complications such as SSI, wound dehiscence, and re-do cranioplasty. We measured cranioplasty complication rates before and after implementation of a peri-operative bundle, which consisted of peri-operative vancomycin (4 doses), a barrier dressing through post-operative day (POD) 3, and de-colonization of the surgical incision using topical chlorhexidine from POD 4 to 7. The rate of MRSA colonization in cranioplasty patients is three times higher than the average seen on ICU admission screening (19% vs. 6%). The cranioplasty surgical complication rate was 22.8% and SSI rate was 10.5%. The concurrent SSI rate for craniectomy was 1.9%. Organisms isolated were methicillin-resistant Staphylococcus aureus (4), methicillin-sensitive S. aureus (1), Propionibacterium acnes (1), and Escherichia coli (1). Factors associated with SSI were peri-operative vancomycin (68.6% vs. 16.7%, p=0.0217). Complication rates without (n=21) and with (n=36) the bundle were: SSI (23.8% vs. 2.8%, p=0.0217) and redo cranioplasty (19% vs. 0%, p=0.0152). Bundle use did not affect rates for superficial wound dehiscence, seizures, or hydrocephalus. The cranioplasty bundle was associated with reduced SSI rates and the need for re-do cranioplasties. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Early Results of Anatomic Double Bundle Anterior Cruciate Ligament Reconstruction

    Directory of Open Access Journals (Sweden)

    Demet Pepele

    2014-03-01

    Full Text Available Aim: The goal in anterior cruciate ligament reconstruction (ACLR is to restore the normal anatomic structure and function of the knee. In the significant proportion of patients after the traditional single-bundle ACLR, complaints of instability still continue. Anatomic double bundle ACLR may provide normal kinematics in knees, much closer to the natural anatomy. The aim of this study is to clinically assess the early outcomes of our anatomical double bundle ACLR. Material and Method: In our clinic between June 2009 and March 2010, performed the anatomic double bundle ACLR with autogenous hamstring grafts 20 patients were evaluated prospectively with Cincinnati, IKDC and Lysholm scores and in clinically for muscle strength and with Cybex II dynamometer. Results: The mean follow-up is 17.8 months (13-21 months. Patients%u2019 scores of Cincinnati, IKDC and Lysholm were respectively, preoperative 18.1, 39.3 and 39.8, while the post-op increased to 27.2, 76.3 and 86.3. In their last check, 17 percent of the patients according to IKDC scores (85% A (excellent and B (good group and 3 patients took place as C (adequate group. The power measurements of quadriceps and hamstring muscle groups of patients who underwent surgery showed no significant difference compared with the intact knees. Discussion: Double-bundle ACL reconstruction is a satisfactory method. There is a need comparative, long-term studies in large numbers in order to determine improving clinical outcome, preventing degeneration and restoring the knee biomechanics better.

  3. Ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides (Dinophyceae) with reference to the apical groove and flagellar apparatus

    DEFF Research Database (Denmark)

    Iwataki, Mitsunori; Hansen, Gert; Moestrup, Øjvind

    2010-01-01

    eukaryotes but different from the Gymnodinium group with diagnostic nuclear chambers. The longitudinal and transverse basal bodies are separated by approximately 0.5-1.0 µm and interconnected directly by a striated basal body connective and indirectly by microtubular and fibrous structures. Characteristic...... connective extends toward the posterior end of the cell along the longitudinal flagellar canal. We conclude, based on both morphological and molecular evidence, that Cochlodinium is only distantly related to Gymnodinium....

  4. Standardization of Type 2 Diabetes Outpatient Expenditure with Bundled Payment Method in China

    Directory of Open Access Journals (Sweden)

    Guo-Chao Xu

    2016-01-01

    Conclusions: We argued that it is feasible to implement bundled payment on type 2 diabetes outpatient services. Bundled payment is effective to control the increase of outpatient expenditure. Further improvements are needed for the implementation of bundled payment reimbursement standards, together with relevant policies and measures.

  5. Solutions of the Strominger System via Stable Bundles on Calabi-Yau Threefolds

    DEFF Research Database (Denmark)

    Andreas, Björn; Garcia Fernandez, Mario

    2012-01-01

    We prove that a given Calabi-Yau threefold with a stable holomorphic vector bundle can be perturbed to a solution of the Strominger system provided that the second Chern class of the vector bundle is equal to the second Chern class of the tangent bundle. If the Calabi-Yau threefold has strict SU(...

  6. The determinant bundle on the moduli space of stable triples over a ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. We construct a holomorphic Hermitian line bundle over the moduli space of stable triples of the form (E1,E2,φ), where E1 and E2 are holomorphic vector bundles over a fixed compact Riemann surface X, and φ : E2 −→ E1 is a holomorphic vector bundle homomorphism. The curvature of the Chern connection of ...

  7. Lexical Bundles in Chinese Undergraduate Academic Writing at an English Medium University

    Science.gov (United States)

    Ruan, Zhoulin

    2017-01-01

    This paper investigates the use of lexical bundles in Chinese students' academic writing across different levels of studies at an English medium university. Frequency-based bundles were retrieved from a corpus of student academic texts written at four points of time between Year 1 and Year 4, and the structures and functions of the bundles were…

  8. The Glycosylphosphatidylinositol-PLC in Trypanosoma brucei Forms a Linear Array on the Exterior of the Flagellar Membrane Before and After Activation

    Science.gov (United States)

    Hanrahan, Orla; Webb, Helena; O'Byrne, Robert; Brabazon, Elaine; Treumann, Achim; Sunter, Jack D.; Carrington, Mark; Voorheis, H. Paul

    2009-01-01

    Bloodstream forms of Trypanosoma brucei contain a glycosylphosphatidylinositol-specific phospholipase C (GPI-PLC) that cleaves the GPI-anchor of the variable surface glycoprotein (VSG). Its location in trypanosomes has been controversial. Here, using confocal microscopy and surface labelling techniques, we show that the GPI-PLC is located exclusively in a linear array on the outside of the flagellar membrane, close to the flagellar attachment zone, but does not co-localize with the flagellar attachment zone protein, FAZ1. Consequently, the GPI-PLC and the VSG occupy the same plasma membrane leaflet, which resolves the topological problem associated with the cleavage reaction if the VSG and the GPI-PLC were on opposite sides of the membrane. The exterior location requires the enzyme to be tightly regulated to prevent VSG release under basal conditions. During stimulated VSG release in intact cells, the GPI-PLC did not change location, suggesting that the release mechanism involves lateral diffusion of the VSG in the plane of the membrane to the fixed position of the GPI-PLC. PMID:19503825

  9. Identification of putative new Escherichia coli flagellar antigens from human origin using serology, PCR-RFlP and DNA sequencing methods

    Directory of Open Access Journals (Sweden)

    Monique Ribeiro Tiba

    Full Text Available Escherichia coli has been isolated frequently, showing flagellar antigens that are not recognized by any of the 53 antisera, provided by the most important reference center of E. coli, The International Escherichia and Klebsiella Center (WHO of the Statens Serum Institute, Copenhagen, Denmark. The objective of this study was to characterize flagellar antigens of E. coli that express non-typeable H antigens. The methods used were serology, PCR-RFLP and DNA sequencing. This characterization was performed by gene amplification of the fliC (flagellin protein by polymerase chain reaction in all 53 standards E.coli strains for the H antigens and 20 E. coli strains for which the H antigen was untypeable. The amplicons were digested by restriction enzymes, and different restriction enzyme profiles were observed. Anti-sera were produced in rabbits, for the non-typeable strains, and agglutination tests were carried out. In conclusion,the results showed that although non-typeable and typable H antigens strains had similar flagellar antigens, the two types of strains were distinct in terms of nucleotide sequence, and did not phenotypically react with the standard antiserum, as expected. Thirteen strains had been characterized as likely putative new H antigen using PCR-RFLP techniques, DNA sequencing and/or serology.

  10. Microtubule assembly and function in Chlamydomonas: inhibition of growth and flagellar regeneration by antitubulins and other drugs and isolation of resistant mutants.

    Science.gov (United States)

    Flavin, M; Slaughter, C

    1974-04-01

    The distribution of microtubules in Chlamydomonas reinhardtii suggests that they are involved in mitosis, cell and nuclear cleavage, and generation of flagella. Vinblastine, colchicine, and podophyllotoxin bind to the protein building block of microtubules (tubulin) and prevent normal assembly. Mutants resistant to these "antitubulin" drugs are candidates to have alterations in tubulin primary structure. We report the ability to inhibit growth, and flagellar regeneration after amputation, of: vinblastine, several colchicine derivatives, two water-soluble derivatives of podophyllotoxin (succinylpodophyllotoxin and epipodophyllotoxin thiuronium bromide), and other substances which may interfere with flagellar assembly or motility (isopropyl N-phenyl carbamate, 2-methoxy-5-nitrotropone, chloral hydrate, caffeine, and nickel acetate). The ability of each drug to inhibit binding of labeled colchicine or podophyllotoxin to mammalian brain tubulin was also determined. The results suggest that only in the cases of colchicine, colcemide, and epipodophyllotoxin thiruonium bromide was the toxicity to Chlamydomonas mediated by inhibition of tubulin assembly. The requirement for high concentrations of colchicine may be due to permeability barriers, since colchicine toxicity was potentiated by deoxycholate. Mutants resistant to antitubulins were isolated after treatment with methyl methanesulfonate. The results with vinblastine were equivocal. Of three mutants resistant to inhibition of growth and flagellar regeneration by colchicine, one was also cross-resistant to epipodophyllotoxin thiuronium bromide.

  11. MotI (DgrA) acts as a molecular clutch on the flagellar stator protein MotA inBacillus subtilis.

    Science.gov (United States)

    Subramanian, Sundharraman; Gao, Xiaohui; Dann, Charles E; Kearns, Daniel B

    2017-12-19

    Stator elements consisting of MotA 4 MotB 2 complexes are anchored to the cell wall, extend through the cell membrane, and interact with FliG in the cytoplasmic C ring rotor of the flagellum. The cytoplasmic loop of MotA undergoes proton-driven conformational changes that drive flagellar rotation. Functional regulators inhibit motility by either disengaging or jamming the stator-rotor interaction. Here we show that the YcgR homolog MotI (formerly DgrA) of Bacillus subtilis inhibits motility like a molecular clutch that disengages MotA. MotI-inhibited flagella rotated freely by Brownian motion, and suppressor mutations in MotA that were immune to MotI inhibition were located two residues downstream of the critical force generation site. The 3D structure of MotI bound to c-di-GMP was solved, and MotI-fluorescent fusions localized as transient MotA-dependent puncta at the membrane when induced at subinhibitory levels. Finally, subinhibitory levels of MotI expression resulted in incomplete inhibition and proportional decreases in swimming speed. We propose a model in which flagellar stators are disengaged and sequestered from the flagellar rotor when bound by MotI.

  12. Biomechanical comparisons of knee stability after anterior cruciate ligament reconstruction between 2 clinically available transtibial procedures: anatomic double bundle versus single bundle.

    Science.gov (United States)

    Kondo, Eiji; Merican, Azhar M; Yasuda, Kazunori; Amis, Andrew A

    2010-07-01

    Several trials have compared the clinical results between anatomic double-bundle and single-bundle anterior cruciate ligament reconstruction procedures. However, it remains controversial whether the anatomic double-bundle procedure is superior to the single-bundle procedure. The anatomic double-bundle procedure will be better than the single-bundle procedure at resisting anterior laxity, internal rotation laxity, and pivot-shift instability. Controlled laboratory study. Eight cadaveric knees were tested in a 6 degrees of freedom rig using the following loading conditions: 90-N anterior tibialforce, 5-N.m internal and external tibial torques, and a simulated pivot-shift test. Tibiofemoral kinematics during the flexion-extension cycle were recorded with an optical tracking system for (1) intact, (2) anterior cruciate ligament-deficient knee, (3) anatomic double-bundle reconstruction, and (4) single-bundle reconstruction placed at 11 o'clock in the intercondylar notch. There were significant reductions of anterior laxity of 3.5 mm at 20 degrees of flexion, internal rotational laxity of 2.5 degrees at 20 degrees of flexion, and anterior translations (2 mm) and internal rotations (5 degrees ) in the simulated pivot-shift test in the double-bundle reconstruction com-pared with the single-bundle reconstruction. There were no significant differences between the 2 procedures for external rotation laxity. The postoperative anterior translation and internal rotation stability after anatomic double-bundle anterior cruciate ligament reconstruction were significantly better than after single-bundle reconstruction, in both static tests and the pivot shift. Unlike previous laboratory studies, this work used clinical arthroscopic methods for anterior cruciate ligament reconstruction, and found that the anatomic reconstruction was superior to a single graft placed at 11 o'clock.

  13. Steady-state stiffness of utricular hair cells depends on macular location and hair bundle structure

    Science.gov (United States)

    Spoon, Corrie; Moravec, W. J.; Rowe, M. H.; Grant, J. W.

    2011-01-01

    Spatial and temporal properties of head movement are encoded by vestibular hair cells in the inner ear. One of the most striking features of these receptors is the orderly structural variation in their mechanoreceptive hair bundles, but the functional significance of this diversity is poorly understood. We tested the hypothesis that hair bundle structure is a significant contributor to hair bundle mechanics by comparing structure and steady-state stiffness of 73 hair bundles at varying locations on the utricular macula. Our first major finding is that stiffness of utricular hair bundles varies systematically with macular locus. Stiffness values are highest in the striola, near the line of hair bundle polarity reversal, and decline exponentially toward the medial extrastriola. Striolar bundles are significantly more stiff than those in medial (median: 8.9 μN/m) and lateral (2.0 μN/m) extrastriolae. Within the striola, bundle stiffness is greatest in zone 2 (106.4 μN/m), a band of type II hair cells, and significantly less in zone 3 (30.6 μN/m), which contains the only type I hair cells in the macula. Bathing bundles in media that break interciliary links produced changes in bundle stiffness with predictable time course and magnitude, suggesting that links were intact in our standard media and contributed normally to bundle stiffness during measurements. Our second major finding is that bundle structure is a significant predictor of steady-state stiffness: the heights of kinocilia and the tallest stereocilia are the most important determinants of bundle stiffness. Our results suggest 1) a functional interpretation of bundle height variability in vertebrate vestibular organs, 2) a role for the striola in detecting onset of head movement, and 3) the hypothesis that differences in bundle stiffness contribute to diversity in afferent response dynamics. PMID:21918003

  14. Perceptions of Workload Burden and Adherence to ABCDE Bundle Among Intensive Care Providers.

    Science.gov (United States)

    Boehm, Leanne M; Dietrich, Mary S; Vasilevskis, Eduard E; Wells, Nancy; Pandharipande, Pratik; Ely, E Wesley; Mion, Lorraine C

    2017-07-01

    Use of the interprofessional Awakening and Breathing Coordination, Delirium Monitoring and Management, and Early Mobility (ABCDE) bundle is recommended practice in intensive care, but its adoption remains limited. To examine the relationship between intensive care unit provider attitudes regarding the ABCDE bundle and ABCDE bundle adherence. A 1-time survey of 268 care providers in 10 intensive care units across the country who had worked at least 4 shifts per month to examine their attitudes toward workload burden, difficulty carrying out the bundle, perceived safety, confidence, and perceived strength of evidence. Logistic regression models were used to examine the relationship of unit-level provider attitudes with ABCDE bundle adherence in 101 patients, adjusted for patients' age, severity of illness, and comorbidity. For every unit increase in workload burden, adherence to the ABCDE bundle decreased 53% (odds ratio [OR], 0.47; 95% CI, 0.28-0.79; P = .004). Bundle difficulty (OR, 0.29; 95% CI, 0.08-1.07), perceived safety (OR, 0.51; 95% CI, 0.10-2.65), confidence (OR, 0.37, 95% CI, 0.10-1.35), and perceived strength of evidence (OR, 0.69; 95% CI, 0.14-3.35) were not associated with ABCDE bundle adherence. For every unit increase in perceived difficulty carrying out the bundle, adherence with early mobility was reduced 59% (OR, 0.41; 95% CI, 0.19-0.90; P = .03). In addition, ABCDE bundle adherence (ie, ventilator bundle) was less than DE bundle adherence (ie, ventilator-free bundle) (97% vs 72%, z = 5.47; P < .001). Focusing interventions on workload burden and factors influencing bundle difficulty may facilitate ABCDE bundle adherence. ©2017 American Association of Critical-Care Nurses.

  15. Curcumin Reduces the Motility of Salmonella enterica Serovar Typhimurium by Binding to the Flagella, Thereby Leading to Flagellar Fragility and Shedding

    Science.gov (United States)

    Balakrishnan, Arjun; Negi, Vidya Devi; Sakorey, Deepika; Chandra, Nagasuma

    2016-01-01

    ABSTRACT One of the important virulence properties of the pathogen is its ability to travel to a favorable environment, cross the viscous mucus barrier (intestinal barrier for enteric pathogens), and reach the epithelia to initiate pathogenesis with the help of an appendage, like flagella. Nonetheless, flagella can act as an “Achilles heel,” revealing the pathogen's presence to the host through the stimulation of innate and adaptive immune responses. We assessed whether curcumin, a dietary polyphenol, could alter the motility of Salmonella, a foodborne pathogen. It reduced the motility of Salmonella enterica serovar Typhimurium by shortening the length of the flagellar filament (from ∼8 μm to ∼5 μm) and decreasing its density (4 or 5 flagella/bacterium instead of 8 or 9 flagella/bacterium). Upon curcumin treatment, the percentage of flagellated bacteria declined from ∼84% to 59%. However, no change was detected in the expression of the flagellin gene and protein. A fluorescence binding assay demonstrated binding of curcumin to the flagellar filament. This might make the filament fragile, breaking it into smaller fragments. Computational analysis predicted the binding of curcumin, its analogues, and its degraded products to a flagellin molecule at an interface between domains D1 and D2. Site-directed mutagenesis and a fluorescence binding assay confirmed the binding of curcumin to flagellin at residues ASN120, ASP123, ASN163, SER164, ASN173, and GLN175. IMPORTANCE This work, to our knowledge the first report of its kind, examines how curcumin targets flagellar density and affects the pathogenesis of bacteria. We found that curcumin does not affect any of the flagellar synthesis genes. Instead, it binds to the flagellum and makes it fragile. It increases the torsional stress on the flagellar filament that then breaks, leaving fewer flagella around the bacteria. Flagella, which are crucial ligands for Toll-like receptor 5, are some of the most important

  16. The C*-algebra of a vector bundle and fields of Cuntz algebras

    OpenAIRE

    Vasselli, Ezio

    2004-01-01

    We study the Pimsner algebra associated with the module of continuous sections of a Hilbert bundle, and prove that it is a continuous bundle of Cuntz algebras. We discuss the role of such Pimsner algebras w.r.t. the notion of inner endomorphism. Furthermore, we study bundles of Cuntz algebras carrying a global circle action, and assign to them a class in the representable KK-group of the zero-grade bundle. We compute such class for the Pimsner algebra of a vector bundle.

  17. Transcriptional analysis of the MrpJ network: modulation of diverse virulence-associated genes and direct regulation of mrp fimbrial and flhDC flagellar operons in Proteus mirabilis.

    Science.gov (United States)

    Bode, Nadine J; Debnath, Irina; Kuan, Lisa; Schulfer, Anjelique; Ty, Maureen; Pearson, Melanie M

    2015-06-01

    The enteric bacterium Proteus mirabilis is associated with a significant number of catheter-associated urinary tract infections (UTIs). Strict regulation of the antagonistic processes of adhesion and motility, mediated by fimbriae and flagella, respectively, is essential for disease progression. Previously, the transcriptional regulator MrpJ, which is encoded by the mrp fimbrial operon, has been shown to repress both swimming and swarming motility. Here we show that MrpJ affects an array of cellular processes beyond adherence and motility. Microarray analysis found that expression of mrpJ mimicking levels observed during UTIs leads to differential expression of 217 genes related to, among other functions, bacterial virulence, type VI secretion, and metabolism. We probed the molecular mechanism of transcriptional regulation by MrpJ using transcriptional reporters and chromatin immunoprecipitation (ChIP). Binding of MrpJ to two virulence-associated target gene promoters, the promoters of the flagellar master regulator flhDC and mrp itself, appears to be affected by the condensation state of the native chromosome, although both targets share a direct MrpJ binding site proximal to the transcriptional start. Furthermore, an mrpJ deletion mutant colonized the bladders of mice at significantly lower levels in a transurethral model of infection. Additionally, we observed that mrpJ is widely conserved in a collection of recent clinical isolates. Altogether, these findings support a role of MrpJ as a global regulator of P. mirabilis virulence. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  18. The Sensor Kinase GacS Negatively Regulates Flagellar Formation and Motility in a Biocontrol Bacterium, Pseudomonas chlororaphis O6

    Directory of Open Access Journals (Sweden)

    Ji Soo Kim

    2014-06-01

    Full Text Available The GacS/GacA two component system regulates various traits related to the biocontrol potential of plant-associated pseudomonads. The role of the sensor kinase, GacS, differs between strains in regulation of motility. In this study, we determined how a gacS mutation changed cell morphology and motility in Pseudomonas chlororaphis O6. The gacS mutant cells were elongated in stationary-phase compared to the wild type and the complemented gacS mutant, but cells did not differ in length in logarithmic phase. The gacS mutant had a two-fold increase in the number of flagella compared with the wild type strain; flagella number was restored to that of the wild type in the complemented gacS mutant. The more highly flagellated gacS mutant cells had greater swimming motilities than that of the wild type strain. Enhanced flagella formation in the gacS mutant correlated with increased expression of three genes, fleQ, fliQ and flhF, involved in flagellar formation. Expression of these genes in the complemented gacS mutant was similar to that of the wild type. These findings show that this root-colonizing pseudomonad adjusts flagella formation and cell morphology in stationary-phase using GacS as a major regulator.

  19. An ALE-based finite element model of flagellar motion driven by beating waves: A parametric study.

    Science.gov (United States)

    Razavi, Seyed Esmail; Seyed Ahmadi, Arman

    2015-11-01

    A computational model of flagellar motility is presented using the finite element method. Two-dimensional traveling waves of finite amplitude are propagated down the flagellum and the swimmer is propelled through a viscous fluid according to Newto's second law of motion. Incompressible Navier-Stokes equations are solved on a triangular moving mesh and arbitrary Lagrangian-Eulerian formulation is employed to accommodate the deforming boundaries. The results from the present study are validated against the data available in the literature and close agreement with previous works is found. The effects of wave parameters as well as head morphology on the swimming characteristics are studied for different swimming conditions. We have found that the swimming velocities are linear functions of finite amplitudes and that the rate of work is independent of the channel height for large amplitudes. Furthermore, we have also demonstrated that for the range of wave parameters that are often encountered in human sperm motility studies, the propulsive velocity versus the wavelength exhibits dissimilar trends for different channel heights. Various head configurations were analyzed and it is also observed that wall proximity amplifies the effects induced by different head shapes. By taking non-Newtonian fluids into account, we present new efficiency analyzes through which we have found that the model microorganism swims much more efficiently in shear-thinning fluids. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Flagellar movement in two bacteria of the family rickettsiaceae: a re-evaluation of motility in an evolutionary perspective.

    Directory of Open Access Journals (Sweden)

    Claudia Vannini

    Full Text Available Bacteria of the family Rickettsiaceae have always been largely studied not only for their importance in the medical field, but also as model systems in evolutionary biology. In fact, they share a recent common ancestor with mitochondria. The most studied species, belonging to genera Rickettsia and Orientia, are hosted by terrestrial arthropods and include many human pathogens. Nevertheless, recent findings show that a large part of Rickettsiaceae biodiversity actually resides outside the group of well-known pathogenic bacteria. Collecting data on these recently described non-conventional members of the family is crucial in order to gain information on ancestral features of the whole group. Although bacteria of the family Rickettsiaceae, and of the whole order Rickettsiales, are formally described as non-flagellated prokaryotes, some recent findings renewed the debate about this feature. In this paper we report the first finding of members of the family displaying numerous flagella and active movement inside their host cells. These two new taxa are hosted in aquatic environments by protist ciliates and are described here by means of ultrastructural and molecular characterization. Data here reported suggest that the ancestor of Rickettsiales displayed flagellar movement and re-evaluate the hypothesis that motility played a key-role in the origin of mitochondria. Moreover, our study highlights that the aquatic environment represents a well exploited habitat for bacteria of the family Rickettsiaceae. Our results encourage a deep re-consideration of ecological and morphological traits of the family and of the whole order.

  1. Serine 26 in the PomB subunit of the flagellar motor is essential for hypermotility of Vibrio cholerae.

    Directory of Open Access Journals (Sweden)

    Petra Halang

    Full Text Available Vibrio cholerae is motile by means of its single polar flagellum which is driven by the sodium-motive force. In the motor driving rotation of the flagellar filament, a stator complex consisting of subunits PomA and PomB converts the electrochemical sodium ion gradient into torque. Charged or polar residues within the membrane part of PomB could act as ligands for Na+, or stabilize a hydrogen bond network by interacting with water within the putative channel between PomA and PomB. By analyzing a large data set of individual tracks of swimming cells, we show that S26 located within the transmembrane helix of PomB is required to promote very fast swimming of V. cholerae. Loss of hypermotility was observed with the S26T variant of PomB at pH 7.0, but fast swimming was restored by decreasing the H+ concentration of the external medium. Our study identifies S26 as a second important residue besides D23 in the PomB channel. It is proposed that S26, together with D23 located in close proximity, is important to perturb the hydration shell of Na+ before its passage through a constriction within the stator channel.

  2. Analysis of Subchannel and Rod Bundle PSBT Experiments with CATHARE 3

    Directory of Open Access Journals (Sweden)

    M. Valette

    2012-01-01

    Full Text Available This paper presents the assessment of CATHARE 3 against PWR subchannel and rod bundle tests of the PSBT benchmark. Noticeable measurements were the following: void fraction in single subchannel and rod bundle, multiple liquid temperatures at subchannel exit in rod bundle, and DNB power and location in rod bundle. All these results were obtained both in steady and transient conditions. Void fraction values are satisfactory predicted by CATHARE 3 in single subchannels with the pipe module. More dispersed predictions of void values are obtained in rod bundles with the CATHARE 3 3D module at subchannel scale. Single-phase liquid mixing tests and DNB tests in rod bundle are also analyzed. After calibrating the mixing in liquid single phase with specific tests, DNB tests using void mixing give mitigated results, perhaps linked to inappropriate use of CHF lookup tables in such rod bundles with many spacers.

  3. Analyses of bundle experiment data using MATRA-h

    Energy Technology Data Exchange (ETDEWEB)

    Lim, In Cheol; Chea, Hee Taek [Korea Atomic Energy Research Institute, Taejon (Korea)

    1998-06-01

    When the construction and operation license for HANARO was renewed in 1995, 25% of CHF penalty was imposed. The reason for this was that the validation work related to the CHF design calculation was not enough for the assurance of CHF margin. As a part of the works to recover this CHF penalty, MATRA-h was developed by implementing the new correlations for the heat transfer, CHF prediction, subcooled void to the MATRA-a, which is the modified version of COBRA-IV-I done by KAERI. Using MATRA-h, the subchannel analyses for the bundle experiment data were performed. The comparison of the code predictions with the experimental results, it was found that the code would give the conservative predictions as far as the CHF in the bundle geometry is concerned. (author). 12 refs., 25 figs., 16 tabs.

  4. Catastrophic Failure and Critical Scaling Laws of Fiber Bundle Material

    Directory of Open Access Journals (Sweden)

    Shengwang Hao

    2017-05-01

    Full Text Available This paper presents a spring-fiber bundle model used to describe the failure process induced by energy release in heterogeneous materials. The conditions that induce catastrophic failure are determined by geometric conditions and energy equilibrium. It is revealed that the relative rates of deformation of, and damage to the fiber bundle with respect to the boundary controlling displacement ε0 exhibit universal power law behavior near the catastrophic point, with a critical exponent of −1/2. The proportion of the rate of response with respect to acceleration exhibits a linear relationship with increasing displacement in the vicinity of the catastrophic point. This allows for the prediction of catastrophic failure immediately prior to failure by extrapolating the trajectory of this relationship as it asymptotes to zero. Monte Carlo simulations are completed and these two critical scaling laws are confirmed.

  5. Synthesis of bundled tungsten oxide nanowires with controllable morphology

    International Nuclear Information System (INIS)

    Sun Shibin; Zou Zengda; Min Guanghui

    2009-01-01

    Bundled tungsten oxide nanowires with controllable morphology were synthesized by a simple solvothermal method with tungsten hexachloride (WCl 6 ) as precursor and cyclohexanol as solvent. The as-synthesized products were systematically characterized by using scanning electron microscopy, X-ray diffraction and transition electron microscopy. Brunauer-Emmett-Teller gas-sorption measurements were also employed. Accompanied by an apparent drop of specific surface area from 151 m 2 g -1 for the longer nanowires synthesized using a lower concentration of WCl 6 to 106 m 2 g -1 for the shorter nanowires synthesized using a higher concentration of WCl 6 , a dramatically morphological evolution was also observed. With increasing concentration of tungsten hexachloride (WCl 6 ) in cyclohexanol, the nanostructured bundles became larger, shorter and straighter, and finally a block-shape product occurred

  6. Medical catheters thermally manipulated by fiber optic bundles

    Science.gov (United States)

    Chastagner, P.

    1992-10-06

    A maneuverable medical catheter comprising a flexible tube having a functional tip is described. The catheter is connected to a control source. The functional tip of the catheter carries a plurality of temperature activated elements arranged in parallel and disposed about the functional tip and held in spaced relation at each end. These elements expand when they are heated. A plurality of fiber optic bundles, each bundle having a proximal end attached to the control source and a distal end attached to one of the elements carry light into the elements where the light is absorbed as heat. By varying the optic fiber that is carrying the light and the intensity of the light, the bending of the elements can be controlled and thus the catheter steered. In an alternate embodiment, the catheter carries a medical instrument for gathering a sample of tissue. The instrument may also be deployed and operated by thermal expansion and contraction of its moving parts. 10 figs.

  7. An improved partial bundle method for linearly constrained minimax problems

    Directory of Open Access Journals (Sweden)

    Chunming Tang

    2016-02-01

    Full Text Available In this paper, we propose an improved partial bundle method for solving linearly constrained minimax problems. In order to reduce the number of component function evaluations, we utilize a partial cutting-planes model to substitute for the traditional one. At each iteration, only one quadratic programming subproblem needs to be solved to obtain a new trial point. An improved descent test criterion is introduced to simplify the algorithm. The method produces a sequence of feasible trial points, and ensures that the objective function is monotonically decreasing on the sequence of stability centers. Global convergence of the algorithm is established. Moreover, we utilize the subgradient aggregation strategy to control the size of the bundle and therefore overcome the difficulty of computation and storage. Finally, some preliminary numerical results show that the proposed method is effective.

  8. CAT reconstruction and potting comparison of a LMFBR fuel bundle

    International Nuclear Information System (INIS)

    Betten, P.R.; Tow, D.M.

    1984-04-01

    A standard Liquid Metal Fast Breeder Reactor (LMFBR) subassembly used in the Experimental Breeder Reactor II (EBR-II) was investigated, by remote techniques, for fuel bundle distortion by both nondestructive and destructive methods, and the results from both methods were compared. The non-destructive method employed neutron tomography to reconstruct the locations of fuel elements through the use of a maximum entropy reconstruction algorithm known as MENT. The destructive method consisted of ''potting'' (a technique that embeds and permanently fixes the fuel elements in a solid matrix) the subassembly, and then cutting and polishing the individual sections. The comparison indicated that the tomography reconstruction provided good results in describing the bundle geometry and spacer-wire locations, with the overall resolution being on the order of a spacer-wire diameter. A dimensional consistency check indicated that the element and spacer-wire dimensions were accurately reproduced in the reconstruction

  9. Element bow profiles from new and irradiated CANDU fuel bundles

    International Nuclear Information System (INIS)

    Dennier, D.; Manzer, A.M.; Ryz, M.A.

    1996-01-01

    Improved methods of measuring element profiles on new CANDU fuel bundles were developed at the Sheridan Park Engineering Laboratory, and have now been applied in the hot cells at Whiteshell Laboratories. For the first time, the outer element profiles have been compared between new, out-reactor tested, and irradiated fuel elements. The comparison shows that irradiated element deformation is similar to that observed on elements in out-reactor tested bundles. In addition to the restraints applied to the element via appendages, the element profile appears to be strongly influenced by gravity and the end loads applied by local deformation of the endplate. Irradiation creep in the direction of gravity also tends to be a dominant factor. (author)

  10. Decomposable subbundles of polystable vector bundles on projective curves

    OpenAIRE

    Ballico, E. (Edoardo)

    1999-01-01

    Let $X$ be a smooth projective curve of genus $g\\geq 4$. Here we show the existence for several numerical invariants $x> 0$, deg($E_i$), rank($E_i$), $1 \\leq i \\leq x$, deg($F$), rank($F$) of semistable vector bundles $E_i, 1\\leq i\\leq x, F$ on $X$ such that $E :=\\oplus_{1\\leq i\\leq x}E_i$ is a saturated subbundle of $F$ and $F/E$ is semistable. If $X$ is either bielliptic or with general moduli we may find stable vector bundles $E_i, 1\\leq i\\leq x$, and $F$ with $F/E$ stable.

  11. Bundled multi-tube nozzle for a turbomachine

    Science.gov (United States)

    Lacy, Benjamin Paul; Ziminsky, Willy Steve; Johnson, Thomas Edward; Zuo, Baifang; York, William David; Uhm, Jong Ho

    2015-09-22

    A turbomachine includes a compressor, a combustor operatively connected to the compressor, an end cover mounted to the combustor, and an injection nozzle assembly operatively connected to the combustor. The injection nozzle assembly includes a cap member having a first surface that extends to a second surface. The cap member further includes a plurality of openings. A plurality of bundled mini-tube assemblies are detachably mounted in the plurality of openings in the cap member. Each of the plurality of bundled mini-tube assemblies includes a main body section having a first end section and a second end section. A fluid plenum is arranged within the main body section. A plurality of tubes extend between the first and second end sections. Each of the plurality of tubes is fluidly connected to the fluid plenum.

  12. Catastrophic Failure and Critical Scaling Laws of Fiber Bundle Material.

    Science.gov (United States)

    Hao, Shengwang; Yang, Hang; Liang, Xiangzhou

    2017-05-09

    This paper presents a spring-fiber bundle model used to describe the failure process induced by energy release in heterogeneous materials. The conditions that induce catastrophic failure are determined by geometric conditions and energy equilibrium. It is revealed that the relative rates of deformation of, and damage to the fiber bundle with respect to the boundary controlling displacement ε ₀ exhibit universal power law behavior near the catastrophic point, with a critical exponent of -1/2. The proportion of the rate of response with respect to acceleration exhibits a linear relationship with increasing displacement in the vicinity of the catastrophic point. This allows for the prediction of catastrophic failure immediately prior to failure by extrapolating the trajectory of this relationship as it asymptotes to zero. Monte Carlo simulations are completed and these two critical scaling laws are confirmed.

  13. Bundle adjustment with raw inertial observations in UAV applications

    Science.gov (United States)

    Cucci, Davide Antonio; Rehak, Martin; Skaloud, Jan

    2017-08-01

    It is well known that accurate aerial position and attitude control is beneficial for image orientation in airborne photogrammetry. The aerial control is traditionally obtained by Kalman filtering/smoothing inertial and GNSS observations prior to the bundle-adjustment. However, in Micro Aerial Vehicles this process may result in poor attitude determination due to the limited quality of the inertial sensors, large alignment uncertainty and residual correlations between sensor biases and initial attitude. We propose to include the raw inertial observations directly into the bundle-adjustment instead of as position and attitude weighted observations from a separate inertial/GNSS fusion step. The necessary observation models are derived in detail within the context of the so called "Dynamic Networks". We examine different real world cases and we show that the proposed approach is superior to the established processing pipeline in challenging scenarios such as mapping in corridors and in areas where the reception of GNSS signals is denied.

  14. Bundled Payments for Elective Primary Total Knee Arthroplasty

    Science.gov (United States)

    Lu, Xin; Li, Yue

    2015-01-01

    Bundled payments have been proposed as a mechanism for restraining health care spending for total knee arthroplasty (TKA), but empirical data are limited. We used Medicare data to examine variation in payments for TKA during a window extending 30 days before to 90 days after TKA for 167 186 patients who underwent elective primary TKA in 2009. Mean Medicare payment was US$23 656. We found that 2.5% of patients incurred payments of >US$50 000 (0.2% >US$100 000). Payments were lower for men and for non-Hispanic whites but higher for patients with greater comorbidity. Episode-of-care payment for primary TKA varies substantially depending upon patient demographics and comorbidity. To the extent that similar patients tend to be clustered within hospitals, bundled payments could inadvertently cause financial harm to certain health systems while rewarding others. PMID:26246946

  15. On Harder–Narasimhan reductions for Higgs principal bundles

    Indian Academy of Sciences (India)

    (2) G stands for a connected reductive algebraic group (i.e. for the linear algebraic group. G, unipotent radical of G, ... bundle E on X. We now recall some facts which we need in our work. (1) Let E be a principal ..... Now we need to check the second condition in the definition of the Higgs H–N reduction. Let B be a Borel ...

  16. Cosmic multi-muon bundles detected by DELPHI

    CERN Document Server

    Ridky, J

    2003-01-01

    The DELPHI detector at LEP, located 100 m underground, has been used to detect multi-muon bundles originated from cosmic ray interactions in the atmosphere. The cosmic events registered during the years 1999 and 2000 correspond roughly to 1.6 106 s of effective run time. The muon multiplicity distribution has been measured over a wide range of multiplicities. This paper provides a preliminary comparison between the data and a prediction of the QGSJET model implemented to the CORSIKA simulation package.

  17. Downflow film boiling in a rod bundle at low pressure

    International Nuclear Information System (INIS)

    Hochreiter, L.E.; Rosal, E.R.; Fayfich, R.R.

    1978-01-01

    A series of low pressure downflow film boiling heat transfer experiments were conducted in a 14-foot (4.27 m) long electrically heater rod bundle containing 336 heater rods. The resulting data was compared with the Dougall-Rohsenow dispersed flow film boiling correlation. The data was found to lie below this correlation as the quality was increased. It is believed that buoyancy effects decreased the heat transfer in downflow film boiling. (author)

  18. On Rationality of Moduli Spaces of Vector Bundles on Real ...

    Indian Academy of Sciences (India)

    Let be a real form of a Hirzebruch surface. Let M H ( r , c 1 , c 2 ) be the moduli space of vector bundles on . Under some numerical conditions on r , c 1 and c 2 , we identify those M H ( r , c 1 , c 2 ) that are rational. Author Affiliations. Indranil Biswas1 Ronnie Sebastian2. School of Mathematics, Tata Institute of ...

  19. Real parabolic vector bundles over a real curve

    Indian Academy of Sciences (India)

    Abstract. We define real parabolic structures on real vector bundles over a real curve. Let (X,σX ) be a real curve, and let S ⊂ X be a non-empty finite subset of X such that σX (S) = S. Let N ≥ 2 be an integer. We construct an N-fold cyclic cover p : Y → X in the category of real curves, ramified precisely over each point of S, ...

  20. Thermal analysis methods for LMFBR wire wrapped bundles

    International Nuclear Information System (INIS)

    Todreas, N.E.

    1976-11-01

    A note is presented which was written to stimulate an awareness and discussion of the fundamental differences in the formulation of certain existing analysis codes for LMFBR wire wrap bundles. The contention of the note is that for those array types where data exists (one wire per pin, equal start angles), the ENERGY method results for coolant temperature under forced convection conditions provide benchmarks of reliability equal to the results of codes COBRA and TH1-3D

  1. On the classification of complex vector bundles of stable rank

    Indian Academy of Sciences (India)

    In the present paper, we study the classification of stable-rank bundles on some compact complex manifolds. First, we extend ... below the results obtained in this case (see Propositions 4.1–4.3 and Theorems 5.1–5.3 for .... In order to prove the converse inclusion, let (c1,...,cp+1) be a (p + 1)-tuple of coho- mology classes ...

  2. Principal bundles whose restrictions to a curve are isomorphic

    Indian Academy of Sciences (India)

    we get rank n vector bundles E and F together with a flag of subbundles. 0 = Eio ⊂ Ei1 ⊂···⊂ Eik = E ... and F/Fi which restricts to the zero homomorphism on the curve C. Assuming the curve C to be of very high degree we get .... Finally he would like to thank his friend Anand Sawant for helping with the latexing. References.

  3. Behavior of a bundle of fast fuel pins under irradiation

    International Nuclear Information System (INIS)

    Marbach, G.; Millet, P.; Robert, J.; Languille, A.

    1979-01-01

    In the French design of fuel elements for fast reactors, great deformation of pins can bring about interaction with the hexagonal tube through the spacer wires. The change in such bundles is described here when the diameter of the cladding increases and the outcome of this reaction (bending and ovalization of pins) is calculated with a simplified model. It is shown that the results achieved agree well with the experimental observations [fr

  4. Crossed products by endomorphisms, vector bundles and group duality, II

    OpenAIRE

    Vasselli, Ezio

    2004-01-01

    We study C*-algebra endomorphims which are special in a weaker sense w.r.t. the notion introduced by Doplicher and Roberts. We assign to such endomorphisms a geometrical invariant, representing a cohomological obstruction for them to be special in the usual sense. Moreover, we construct the crossed product of a C*-algebra by the action of the dual of a (nonabelian, noncompact) group of vector bundle automorphisms. These crossed products supply a class of examples for such generalized special ...

  5. Evaluating pulp stiffness from fibre bundles by ultrasound

    Science.gov (United States)

    Karppinen, Timo; Montonen, Risto; Määttänen, Marjo; Ekman, Axel; Myllys, Markko; Timonen, Jussi; Hæggström, Edward

    2012-06-01

    A non-destructive ultrasonic tester was developed to measure the stiffness of pulp bundles. The mechanical properties of pulp are important when estimating the behaviour of paper under stress. Currently available pulp tests are tedious and alter the fibres structurally and mechanically. The developed tester employs (933 ± 15) kHz tweezer-like ultrasonic transducers and time-of-flight measurement through (9.0 ± 2.5) mm long and (0.8 ± 0.1) mm thick fibre bundles kept at (19.1 ± 0.4) °C and (62 ± 1)% RH. We determined the stiffness of soft wood pulps produced by three kraft pulping modifications: standard kraft pulp, (5.2 ± 0.4) GPa, prehydrolysis kraft pulp, (4.3 ± 0.4) GPa, and alkali extracted prehydrolysis kraft pulp, (3.3 ± 0.4) GPa. Prehydrolysis and alkali extraction processes mainly lowered the hemicellulose content of the pulps, which essentially decreased the fibre-wall stiffness hence impairing the stiffness of the fibre networks. Our results indicate that the method allows ranking of pulps according to their stiffness determined from bundle-like samples taken at an early phase of the papermaking process.

  6. Fabrication of CANFLEX bundle kit for irradiation test in NRU

    International Nuclear Information System (INIS)

    Cho, Moon Sung; Kwon, Hyuk Il; Ji, Chul Goo; Chang, Ho Il; Sim, Ki Seob; Suk, Ho Chun.

    1997-10-01

    CANFLEX bundle kit was prepared at KAERI for the fabrication of complete bundle at AECL. Completed bundle will be used for irradiation test in NRU. Provisions in the 'Quality Assurance Manual for HWR Fuel Projects,' 'Manufacturing Plan' and 'Quality Verification, Inspection and Test Plan' were implemented as appropriately for the preparation of CANFLEX kit. A set of CANFLEX kit consist of 43 fuel sheath of two different sizes with spacers, bearing pads and buttons attached, 2 pieces of end plates and 86 pieces of end caps with two different sizes. All the documents utilized as references for the fabrication such as drawings, specifications, operating instructions, QC instructions and supplier's certificates are specified in this report. Especially, suppliers' certificates and inspection reports for the purchased material as well as KAERI's inspection report are integrated as attachments to this report. Attached to this report are supplier's certificates and KAERI inspection reports for the procured materials and KAERI QC inspection reports for tubes, pads, spacers, buttons, end caps, end plates and fuel sheath. (author). 37 refs

  7. Gaining surgical access for repositioning the inferior alveolar neurovascular bundle.

    Science.gov (United States)

    Al-Siweedi, Saif Yousif Abdullah; Nambiar, P; Shanmuhasuntharam, P; Ngeow, W C

    2014-01-01

    This study is aimed at determining anatomical landmarks that can be used to gain access to the inferior alveolar neurovascular (IAN) bundle. Scanned CBCT (i-CAT machine) data of sixty patients and reconstructions performed using the SimPlant dental implant software were reviewed. Outcome variables were the linear distances of the mandibular canal to the inferior border and the buccal cortex of the mandible, measured immediately at the mental foramen (D1) and at 10, 20, 30, and 40 mm (D2-D5) distal to it. Predictor variables were age, ethnicity, and gender of subjects. Apicobasal assessment of the canal reveals that it is curving downward towards the inferior mandibular border until 20 mm (D3) distal to the mental foramen where it then curves upwards, making an elliptic-arc curve. The mandibular canal also forms a buccolingually oriented elliptic arc in relation to the buccal cortex. Variations due to age, ethnicity, and gender were evident and this study provides an accurate anatomic zone for gaining surgical access to the IAN bundle. The findings indicate that the buccal cortex-IAN distance was greatest at D3. Therefore, sites between D2 and D5 can be used as favorable landmarks to access the IAN bundle with the least complications to the patient.

  8. Gaining Surgical Access for Repositioning the Inferior Alveolar Neurovascular Bundle

    Directory of Open Access Journals (Sweden)

    Saif Yousif Abdullah Al-Siweedi

    2014-01-01

    Full Text Available This study is aimed at determining anatomical landmarks that can be used to gain access to the inferior alveolar neurovascular (IAN bundle. Scanned CBCT (i-CAT machine data of sixty patients and reconstructions performed using the SimPlant dental implant software were reviewed. Outcome variables were the linear distances of the mandibular canal to the inferior border and the buccal cortex of the mandible, measured immediately at the mental foramen (D1 and at 10, 20, 30, and 40 mm (D2–D5 distal to it. Predictor variables were age, ethnicity, and gender of subjects. Apicobasal assessment of the canal reveals that it is curving downward towards the inferior mandibular border until 20 mm (D3 distal to the mental foramen where it then curves upwards, making an elliptic-arc curve. The mandibular canal also forms a buccolingually oriented elliptic arc in relation to the buccal cortex. Variations due to age, ethnicity, and gender were evident and this study provides an accurate anatomic zone for gaining surgical access to the IAN bundle. The findings indicate that the buccal cortex-IAN distance was greatest at D3. Therefore, sites between D2 and D5 can be used as favorable landmarks to access the IAN bundle with the least complications to the patient.

  9. Feasibility Study for Cobalt Bundle Loading to CANDU Reactor Core

    International Nuclear Information System (INIS)

    Park, Donghwan; Kim, Youngae; Kim, Sungmin

    2016-01-01

    CANDU units are generally used to produce cobalt-60 at Bruce and Point Lepreau in Canada and Embalse in Argentina. China has started production of cobalt-60 using its CANDU 6 Qinshan Phase III nuclear power plant in 2009. For cobalt-60 production, the reactor’s full complement of stainless steel adjusters is replaced with neutronically equivalent cobalt-59 adjusters, which are essentially invisible to reactor operation. With its very high neutron flux and optimized fuel burn-up, the CANDU has a very high cobalt-60 production rate in a relatively short time. This makes CANDU an excellent vehicle for bulk cobalt-60 production. Several studies have been performed to produce cobalt-60 using adjuster rod at Wolsong nuclear power plant. This study proposed new concept for producing cobalt-60 and performed the feasibility study. Bundle typed cobalt loading concept is proposed and evaluated the feasibility to fuel management without physics and system design change. The requirement to load cobalt bundle to the core was considered and several channels are nominated. The production of cobalt-60 source is very depend on the flux level and burnup directly. But the neutron absorption characteristic of cobalt bundle is too high, so optimizing design study is needed in the future

  10. A Guide to Bundling Small-scale CDM Projects

    International Nuclear Information System (INIS)

    Mariyappan, J.; Bhardwaj, N.; De Coninck, H.; Van der Linden, N.

    2005-07-01

    Small-scale renewable energy and energy efficiency projects that fit the development needs of many developing countries, can potentially be supported via the Clean Development Mechanism (CDM), one of the Kyoto Protocol's flexible mechanisms for tackling climate change. However, there is concern that due to high transaction costs, as well as many existing barriers, very few investments will be made in small-scale projects, which are often the most suitable development option in countries such as India. In view of this, the 'bundling' together of appropriate small-scale projects on a regional basis has been proposed as a way in which funding can be leveraged from international sources and transaction costs reduced. IT Power, IT Power India and the Energy research Centre of the Netherlands (ECN) are carrying out a 2-year project to establish the capacity within India to enable individual small scale projects to be bundled as a single CDM project. Overall objectives are to develop the necessary institutional capabilities to formulate and implement small scale CDM projects in India; to provide a guide on how to bundle small scale projects under the CDM in developing countries; and to raise the awareness of the potential for investment in small scale energy projects which can gain funding through the CDM

  11. BACTERIAL PLASMIDS

    Directory of Open Access Journals (Sweden)

    Marina Dinic

    2007-12-01

    Full Text Available Plasmids, extrachromosomal DNA, were identified in bacteria pertaining to family of Enterobacteriacae for the very first time. After that, they were discovered in almost every single observed strain. The structure of plasmids is made of circular double chain DNA molecules which are replicated autonomously in a host cell. Their length may vary from few up to several hundred kilobase (kb. Among the bacteria, plasmids are mostly transferred horizontally by conjugation process. Plasmid replication process can be divided into three stages: initiation, elongation, and termination. The process involves DNA helicase I, DNA gyrase, DNA polymerase III, endonuclease, and ligase.Plasmids contain genes essential for plasmid function and their preservation in a host cell (the beginning and the control of replication. Some of them possess genes whichcontrol plasmid stability. There is a common opinion that plasmids are unnecessary fora growth of bacterial population and their vital functions; thus, in many cases they can be taken up or kicked out with no lethal effects to a plasmid host cell. However,there are numerous biological functions of bacteria related to plasmids. Plasmids identification and classification are based upon their genetic features which are presented permanently in all of them, and these are: abilities to preserve themselves in a host cell and to control a replication process. In this way, plasmids classification among incompatibility groups is performed. The method of replicon typing, which is based on genotype and not on phenotype characteristics, has the same results as in compatibility grouping.

  12. Compactifications of the Heterotic string with unitary bundles

    Energy Technology Data Exchange (ETDEWEB)

    Weigand, T.

    2006-05-23

    In this thesis we investigate a large new class of four-dimensional supersymmetric string vacua defined as compactifications of the E{sub 8} x E{sub 8} and the SO(32) heterotic string on smooth Calabi-Yau threefolds with unitary gauge bundles and heterotic five-branes. The first part of the thesis discusses the implementation of this idea into the E{sub 8} x E{sub 8} heterotic string. After specifying a large class of group theoretic embeddings featuring unitary bundles, we analyse the effective four-dimensional N=1 supergravity upon compactification. From the gauge invariant Kaehler potential for the moduli fields we derive a modification of the Fayet-Iliopoulos D-terms arising at one-loop in string perturbation theory. From this we conjecture a one-loop deformation of the Hermitian Yang-Mills equation and introduce the idea of {lambda}-stability as the perturbatively correct stability concept generalising the notion of Mumford stability valid at tree-level. We then proceed to a definition of SO(32) heterotic vacua with unitary gauge bundles in the presence of heterotic five-branes and find agreement of the resulting spectrum with the S-dual framework of Type I/Type IIB orientifolds. A similar analysis of the effective four-dimensional supergravity is performed. Further evidence for the proposed one-loop correction to the stability condition is found by identifying the heterotic corrections as the S-dual of the perturbative part of {pi}-stability as the correct stability concept in Type IIB theory. After reviewing the construction of holomorphic stable vector bundles on elliptically fibered Calabi-Yau manifolds via spectral covers, we provide semi-realistic examples for SO(32) heterotic vacua with Pati-Salam and MSSM-like gauge sectors. We finally discuss the construction of realistic vacua with flipped SU(5) GUT and MSSM gauge group within the E{sub 8} x E{sub 8} framework, based on the embedding of line bundles into both E{sub 8} factors. Some of the appealing

  13. Getting the Most from Your CD-ROM Dollars: The CD-ROM Bundle [and] The Pros and Cons of CD-ROM Bundling.

    Science.gov (United States)

    Sarjeant, Eric W.; O'Connor, Mary Ann

    1992-01-01

    Discusses and reviews CD-ROM bundles--i.e., hardware, software and CD-ROM kits--including their features, specifications, drawbacks, and prices. Recommends buying through mail order for the best selection and price. The pros and cons of bundling as a marketing strategy are discussed and a list of vendors is provided. (EA)

  14. Bacterial diseases of tomato plants in terms of open and covered growing of Ukraine

    Directory of Open Access Journals (Sweden)

    J.V. Kolomiets

    2017-06-01

    Full Text Available It was established that the main causes of mass diseases of tomato in covered ground in Ukraine are agents of bacterial black spotting, bacterial speck and in open ground are agent of bacterial cancer of tomato plants. Typical symptoms of diseases are wilting and die-off of young plants, blackening of fiber vascular bundles, black spotting of leaves and fruits, and fruit stem rot. It was studied morphological and cultural, as well as physiological and biochemical properties of the selected strains of the agents of tomato bacterial diseases. We recommended biological preparations Phytocide and Phytohelp based on the bacteria Bacillus subtilis, to restrict the development of the agents of bacterial black spotting Xanthomonas vesicatoria and bacterial cancer Clavibacter michiganensis subsp. michiganensis.

  15. One stage revision single-bundle anterior cruciate ligament reconstruction with impacted morselized bone graft following a failed double-bundle reconstruction

    Directory of Open Access Journals (Sweden)

    Ho Jong Ra

    2017-01-01

    Full Text Available Although double-bundle anterior cruciate ligament (ACL reconstruction has theoretical benefits such as more accurate reproduction of ACL anatomy, it is technically more demanding surgery. This report describes the case of a one stage revision single-bundle ACL reconstruction after primary double-bundle ACL reconstruction. A professional dancer had an ACL previously reconstructed with a double-bundle technique, but the femoral tunnels were malpositioned resulting in residual laxity and rotational instability. The previous femoral tunnel positions were vertical and widened. The previous vertical tunnels were filled with impacted bone graft and a revision single-bundle ACL reconstruction was performed via the new femoral tunnel with a 2 O'clock position between the previous two tunnels. After 10 months of postoperative rehabilitation, the patient returned to professional dancing with sound bony union and without any residual instability.

  16. Double-bundle depiction of the anterior cruciate ligament at 3 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Adriaensen, M.E.A.P.M. [Atrium Medical Center Parkstad, Department of Radiology, Heerlen (Netherlands); Hogan, B. [Sports Surgery Clinic, Department of Radiology, Dublin (Ireland); Al-Bulushi, H.I.J. [Armed Forces Hospital, Department of Radiology, Muscat (Oman); Kavanagh, E.C. [Mater Misericordiae Hospital, Department of Radiology, Dublin (Ireland)

    2012-07-15

    Magnetic resonance imaging on 3 Tesla (3T MRI) with arthroscopic correlation has proven to adequately identify the anteromedial bundle (AMB) and posterolateral bundle (PLB) in cadaver knees. The purpose of this study was to describe the depiction of ACL bundle anatomy on 3T MRI in daily practice. In a retrospective cohort study, we included 50 consecutive patients who underwent standard 3T MRI of the knee and had an intact ACL. Two musculoskeletal radiologists independently reviewed all scans for depiction of ACL bundle anatomy using standardized forms. Descriptive statistics were used. Twenty-three right knees (46%) and 27 left knees (54%) were included in the study. Mean age of the patients was 35 years (range 12 to 68 years); 37 patients were male (74%). ACL bundle anatomy was best depicted in the axial plane in 44 knees (88%) and in the coronal plane in six knees (12%). Two bundles were seen in 47 knees (94%). The AMB was completely seen in 45 knees (90%). The PLB was completely seen in 40 knees (80%). Both bundles were completely seen in 37 knees (76%). The double-bundle anatomy of the ACL is visualized in 94% of patients on 3T MRI. Because of potentially associated clinical benefits, we advocate to report separately on the anteromedial bundle and posterolateral bundle in case of anterior cruciate ligament injury of the knee. (orig.)

  17. New models of droplet deposition and entrainment for prediction of CHF in cylindrical rod bundles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haibin, E-mail: hb-zhang@xjtu.edu.cn [School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an 710049 (China); Department of Chemical Engineering, Imperial College, London SW7 2BY (United Kingdom); Hewitt, G.F. [Department of Chemical Engineering, Imperial College, London SW7 2BY (United Kingdom)

    2016-08-15

    Highlights: • New models of droplet deposition and entrainment in rod bundles is developed. • A new phenomenological model to predict the CHF in rod bundles is described. • The present model is well able to predict CHF in rod bundles. - Abstract: In this paper, we present a new set of model of droplet deposition and entrainment in cylindrical rod bundles based on the previously proposed model for annuli (effectively a “one-rod” bundle) (2016a). These models make it possible to evaluate the differences of the rates of droplet deposition and entrainment for the respective rods and for the outer tube by taking into account the geometrical characteristics of the rod bundles. Using these models, a phenomenological model to predict the CHF (critical heat flux) for upward annular flow in vertical rod bundles is described. The performance of the model is tested against the experimental data of Becker et al. (1964) for CHF in 3-rod and 7-rod bundles. These data include tests in which only the rods were heated and data for simultaneous uniform and non-uniform heating of the rods and the outer tube. It was shown that the predicted CHFs by the present model agree well with the experimental data and with the experimental observation that dryout occurred first on the outer rods in 7-rod bundles. It is expected that the methodology used will be generally applicable in the prediction of CHF in rod bundles.

  18. Architecture of the Flagellar Switch Complex of Escherichia coli: Conformational Plasticity of FliG and Implications for Adaptive Remodeling.

    Science.gov (United States)

    Kim, Eun A; Panushka, Joseph; Meyer, Trevor; Carlisle, Ryan; Baker, Samantha; Ide, Nicholas; Lynch, Michael; Crane, Brian R; Blair, David F

    2017-05-05

    Structural models of the complex that regulates the direction of flagellar rotation assume either ~34 or ~25 copies of the protein FliG. Support for ~34 came from crosslinking experiments identifying an intersubunit contact most consistent with that number; support for ~25 came from the observation that flagella can assemble and rotate when FliG is genetically fused to FliF, for which the accepted number is ~25. Here, we have undertaken crosslinking and other experiments to address more fully the question of FliG number. The results indicate a copy number of ~25 for FliG. An interaction between the C-terminal and middle domains, which has been taken to support a model with ~34 copies, is also supported. To reconcile the interaction with a FliG number of ~25, we hypothesize conformational plasticity in an interdomain segment of FliG that allows some subunits to bridge gaps created by the number mismatch. This proposal is supported by mutant phenotypes and other results indicating that the normally helical segment adopts a more extended conformation in some subunits. The FliG amino-terminal domain is organized in a regular array with dimensions matching a ring in the upper part of the complex. The model predicts that FliG copy number should be tied to that of FliF, whereas FliM copy number can increase or decrease according to the number of FliG subunits that adopt the extended conformation. This has implications for the phenomenon of adaptive switch remodeling, in which the FliM copy number varies to adjust the bias of the switch. Copyright © 2017. Published by Elsevier Ltd.

  19. Proteomic Analysis of Intact Flagella of Procyclic Trypanosoma brucei Cells Identifies Novel Flagellar Proteins with Unique Sub-localization and Dynamics*

    Science.gov (United States)

    Subota, Ines; Julkowska, Daria; Vincensini, Laetitia; Reeg, Nele; Buisson, Johanna; Blisnick, Thierry; Huet, Diego; Perrot, Sylvie; Santi-Rocca, Julien; Duchateau, Magalie; Hourdel, Véronique; Rousselle, Jean-Claude; Cayet, Nadège; Namane, Abdelkader; Chamot-Rooke, Julia; Bastin, Philippe

    2014-01-01

    Cilia and flagella are complex organelles made of hundreds of proteins of highly variable structures and functions. Here we report the purification of intact flagella from the procyclic stage of Trypanosoma brucei using mechanical shearing. Structural preservation was confirmed by transmission electron microscopy that showed that flagella still contained typical elements such as the membrane, the axoneme, the paraflagellar rod, and the intraflagellar transport particles. It also revealed that flagella severed below the basal body, and were not contaminated by other cytoskeletal structures such as the flagellar pocket collar or the adhesion zone filament. Mass spectrometry analysis identified a total of 751 proteins with high confidence, including 88% of known flagellar components. Comparison with the cell debris fraction revealed that more than half of the flagellum markers were enriched in flagella and this enrichment criterion was taken into account to identify 212 proteins not previously reported to be associated to flagella. Nine of these were experimentally validated including a 14-3-3 protein not yet reported to be associated to flagella and eight novel proteins termed FLAM (FLAgellar Member). Remarkably, they localized to five different subdomains of the flagellum. For example, FLAM6 is restricted to the proximal half of the axoneme, no matter its length. In contrast, FLAM8 is progressively accumulating at the distal tip of growing flagella and half of it still needs to be added after cell division. A combination of RNA interference and Fluorescence Recovery After Photobleaching approaches demonstrated very different dynamics from one protein to the other, but also according to the stage of construction and the age of the flagellum. Structural proteins are added to the distal tip of the elongating flagellum and exhibit slow turnover whereas membrane proteins such as the arginine kinase show rapid turnover without a detectible polarity. PMID:24741115

  20. Proteomic analysis of intact flagella of procyclic Trypanosoma brucei cells identifies novel flagellar proteins with unique sub-localization and dynamics.

    Science.gov (United States)

    Subota, Ines; Julkowska, Daria; Vincensini, Laetitia; Reeg, Nele; Buisson, Johanna; Blisnick, Thierry; Huet, Diego; Perrot, Sylvie; Santi-Rocca, Julien; Duchateau, Magalie; Hourdel, Véronique; Rousselle, Jean-Claude; Cayet, Nadège; Namane, Abdelkader; Chamot-Rooke, Julia; Bastin, Philippe

    2014-07-01

    Cilia and flagella are complex organelles made of hundreds of proteins of highly variable structures and functions. Here we report the purification of intact flagella from the procyclic stage of Trypanosoma brucei using mechanical shearing. Structural preservation was confirmed by transmission electron microscopy that showed that flagella still contained typical elements such as the membrane, the axoneme, the paraflagellar rod, and the intraflagellar transport particles. It also revealed that flagella severed below the basal body, and were not contaminated by other cytoskeletal structures such as the flagellar pocket collar or the adhesion zone filament. Mass spectrometry analysis identified a total of 751 proteins with high confidence, including 88% of known flagellar components. Comparison with the cell debris fraction revealed that more than half of the flagellum markers were enriched in flagella and this enrichment criterion was taken into account to identify 212 proteins not previously reported to be associated to flagella. Nine of these were experimentally validated including a 14-3-3 protein not yet reported to be associated to flagella and eight novel proteins termed FLAM (FLAgellar Member). Remarkably, they localized to five different subdomains of the flagellum. For example, FLAM6 is restricted to the proximal half of the axoneme, no matter its length. In contrast, FLAM8 is progressively accumulating at the distal tip of growing flagella and half of it still needs to be added after cell division. A combination of RNA interference and Fluorescence Recovery After Photobleaching approaches demonstrated very different dynamics from one protein to the other, but also according to the stage of construction and the age of the flagellum. Structural proteins are added to the distal tip of the elongating flagellum and exhibit slow turnover whereas membrane proteins such as the arginine kinase show rapid turnover without a detectible polarity. © 2014 by The

  1. Complex Interplay between FleQ, Cyclic Diguanylate and Multiple σ Factors Coordinately Regulates Flagellar Motility and Biofilm Development in Pseudomonas putida.

    Directory of Open Access Journals (Sweden)

    Alicia Jiménez-Fernández

    Full Text Available Most bacteria alternate between a free living planktonic lifestyle and the formation of structured surface-associated communities named biofilms. The transition between these two lifestyles requires a precise and timely regulation of the factors involved in each of the stages that has been likened to a developmental process. Here we characterize the involvement of the transcriptional regulator FleQ and the second messenger cyclic diguanylate in the coordinate regulation of multiple functions related to motility and surface colonization in Pseudomonas putida. Disruption of fleQ caused strong defects in flagellar motility, biofilm formation and surface attachment, and the ability of this mutation to suppress multiple biofilm-related phenotypes associated to cyclic diguanylate overproduction suggests that FleQ mediates cyclic diguanylate signaling critical to biofilm growth. We have constructed a library containing 94 promoters potentially involved in motility and biofilm development fused to gfp and lacZ, screened this library for FleQ and cyclic diguanylate regulation, and assessed the involvement of alternative σ factors σN and FliA in the transcription of FleQ-regulated promoters. Our results suggest a dual mode of action for FleQ. Low cyclic diguanylate levels favor FleQ interaction with σN-dependent promoters to activate the flagellar cascade, encompassing the flagellar cluster and additional genes involved in cyclic diguanylate metabolism, signal transduction and gene regulation. On the other hand, characterization of the FleQ-regulated σN- and FliA-independent PlapA and PbcsD promoters revealed two disparate regulatory mechanisms leading to a similar outcome: the synthesis of biofilm matrix components in response to increased cyclic diguanylate levels.

  2. Limits of feedback control in bacterial chemotaxis.

    Directory of Open Access Journals (Sweden)

    Yann S Dufour

    2014-06-01

    Full Text Available Inputs to signaling pathways can have complex statistics that depend on the environment and on the behavioral response to previous stimuli. Such behavioral feedback is particularly important in navigation. Successful navigation relies on proper coupling between sensors, which gather information during motion, and actuators, which control behavior. Because reorientation conditions future inputs, behavioral feedback can place sensors and actuators in an operational regime different from the resting state. How then can organisms maintain proper information transfer through the pathway while navigating diverse environments? In bacterial chemotaxis, robust performance is often attributed to the zero integral feedback control of the sensor, which guarantees that activity returns to resting state when the input remains constant. While this property provides sensitivity over a wide range of signal intensities, it remains unclear how other parameters such as adaptation rate and adapted activity affect chemotactic performance, especially when considering that the swimming behavior of the cell determines the input signal. We examine this issue using analytical models and simulations that incorporate recent experimental evidences about behavioral feedback and flagellar motor adaptation. By focusing on how sensory information carried by the response regulator is best utilized by the motor, we identify an operational regime that maximizes drift velocity along chemical concentration gradients for a wide range of environments and sensor adaptation rates. This optimal regime is outside the dynamic range of the motor response, but maximizes the contrast between run duration up and down gradients. In steep gradients, the feedback from chemotactic drift can push the system through a bifurcation. This creates a non-chemotactic state that traps cells unless the motor is allowed to adapt. Although motor adaptation helps, we find that as the strength of the feedback

  3. High-resolution flow structure measurements in a rod bundle

    International Nuclear Information System (INIS)

    Ylönen, A. T.

    2013-01-01

    Flow behaviour inside a rod bundle has been an active research topic since the early days of the nuclear power industry. Of particular interest in previous studies have been topics such as flow mixing, two-phase flow structure and mapping of two-phase flow transitions. The optimisation of fuel element design can only be achieved by truly understanding the nature of flow. The ultimate goal in this research is to enhance the heat transfer and increase the critical heat flux, which would improve the fuel economy. A better understanding of the flow would also improve nuclear safety as departure from nucleate boiling (DNB) can be predicted more accurately. The motivation for the current project (SUBFLOW) was to increase knowledge of the complex flow phenomena inside a rod bundle. A dedicated sub-channel flow test facility was designed and constructed at the Paul Scherrer Institut (PSI), Villigen, Switzerland. An adiabatic test loop has an up-scaled (1:2.6) vertical fuel rod bundle model with a 4 × 4 geometry. For the very first time, the wire-mesh sensor measurement technique was implemented in a rod bundle as two 64×64 conductivity wire-mesh sensors were installed in the upper part of the test section. The measurement technique enables one to study single- and two-phase flow behaviour with high spatial and temporal resolution. The research topics addressed in this thesis cover a wide range of flow conditions with and without a spacer grid in a rod bundle. The experimental campaign was started by studying natural mixing of a passive scalar to characterise the development of turbulent diffusion in an injection sub-channel and, later on, cross-mixing between adjacent sub-channels. The results were also used in comparison with the in-house CFD code PSI-Boil that is being developed at PSI. The code could estimate the mixing inside the sub-channel and the transition to cross-mixing with a good accuracy. As a natural transition, the SUBFLOW experiments were continued by

  4. Experimental study on the effect of heat flux tilt on rod bundle dryout limitation

    International Nuclear Information System (INIS)

    Sugawara, S.; Terunuma, K.; Kamoshida, H.

    1995-01-01

    The effect of heat flux tilt on rod bundle dryout limitation was studied experimentally using a full-scale mock-up test facility and simulated 36-rod fuel bundles in which heater pins have azimuthal nonuniform heat flux distribution (i.e., heat flux tilt). Experimental results for typical lateral power distribution in the bundle indicate that the bundle dryout power with azimuthal heat flux tilt is higher than that without azimuthal heat flux tilt in the entire experimental range. Consequently, it is concluded that the dryout experiment using the test bundle with heater pins which has circumferentially uniform heat flux distribution gives conservative results for the usual lateral power distribution in a bundle in which the relative power of outermost-circle fuel rods is higher than those of middle- and inner-circle ones. (author). 15 refs., 2 tabs., 8 figs

  5. Bundle Gel Fibers with a Tunable Microenvironment for in Vitro Neuron Cell Guiding.

    Science.gov (United States)

    Tachizawa, Sayaka; Takahashi, Haruko; Kim, Young-Jin; Odawara, Aoi; Pauty, Joris; Ikeuchi, Yoshiho; Suzuki, Ikuro; Kikuchi, Akihiko; Matsunaga, Yukiko T

    2017-12-13

    As scaffolds for neuron cell guiding in vitro, gel fibers with a bundle structure, comprising multiple microfibrils, were fabricated using a microfluidic device system by casting a phase-separating polymer blend solution comprising hydroxypropyl cellulose (HPC) and sodium alginate (Na-Alg). The topology and stiffness of the obtained bundle gel fibers depended on their microstructure derived by the polymer blend ratio of HPC and Na-Alg. High concentrations of Na-Alg led to the formation of small microfibrils in a one-bundle gel fiber and stiff characteristics. These bundle gel fibers permitted for the elongation of the neuron cells along their axon orientation with the long axis of fibers. In addition, human-induced pluripotent-stem-cell-derived dopaminergic neuron progenitor cells were differentiated into neuronal cells on the bundle gels. The bundle gel fibers demonstrated an enormous potential as cell culture scaffold materials with an optimal microenvironment for guiding neuron cells.

  6. CURRENT STATUS OF INTEGRITY ASSESSMENT BY SIPPING SYSTEM OF SPENT FUEL BUNDLES IRRADIATED IN CANDU REACTOR

    Directory of Open Access Journals (Sweden)

    JONG-YOUL PARK

    2014-12-01

    Full Text Available In terms of safety and the efficient management of spent fuel storage, detecting failed fuel is one of the most important tasks in a CANada Deuterium Uranium (CANDU reactor operation. It has been successfully demonstrated that in a CANDU reactor, on-power failed fuel detection and location systems, along with alarm area gamma monitors, can detect and locate defective and suspect fuel bundles before discharging them from the reactor to the spent fuel storage bay. In the reception bay, however, only visual inspection has been used to identify suspect bundles. Gaseous fission product and delayed neutron monitoring systems cannot precisely distinguish failed fuel elements from each fuel bundle. This study reports the use of a sipping system in a CANDU reactor for the integrity assessment of spent fuel bundles. The integrity assessment of spent fuel bundles using this sipping system has shown promise as a nondestructive test for detecting a defective fuel bundle in a CANDU reactor.

  7. Two new species of Piaroa (Arachnida: Schizomida, Hubbardiidae) from Colombia, with comments on the genus taxonomy and the flagellar setae pattern of Hubbardiinae.

    Science.gov (United States)

    Moreno-González, Jairo A; Delgado-Santa, Leonardo; De Armas, Luis F

    2014-08-14

    Two new species of the genus Piaroa Villarreal, Tourinho & Giupponi, 2008, P. escalerete sp. nov. and P. bacata sp. nov. are described from Valle del Cauca, and Cundinamarca departments, Colombia, respectively. The female flagellum is fully illustrated for a Piaroa species for the first time; the generic diagnosis is also emended and the relationships of the new species with those previously described are discussed. New characters for Piaroa species, a new nomenclature for the chitinized arch and a reinterpretation of the Hubbardiinae flagellar setae pattern are proposed. A distribution map of the known species of Piaroa is provided. 

  8. An eddy viscosity model for flow in a tube bundle

    International Nuclear Information System (INIS)

    Soussan, D.; Grandotto, M.

    1998-01-01

    The work described in this paper is part of the development of GENEPI a 3-dimensional finite element code, designed for the thermalhydraulic analysis of steam generators. It focuses on the implementation of two-phase flow turbulence-induced viscosity in a tube bundle. The GENEPI code, as other industrial codes, uses the eddy viscosity concept introduced by Boussinesq for single phase flow. The concept assumes that the turbulent momentum transfer is similar to the viscous shear stresses. Eddy viscosity formulation is reasonably well known for single phase flows, especially in simple geometries (i.e., in smooth tube, around a single body, or behind a row of bars/tubes), but there exists very little information on it for two-phase flows. An analogy between single and two-phases is used to set up a model for eddy viscosity. The eddy viscosity model examined in this paper is used for a tube bundle geometry and, therefore, is extended to include anisotropy to the classic model. Each of the main flow directions (cross flow inline, cross flow staggered, and parallel flows) gives rise to a specific eddy viscosity formula. The results from a parametric study indicate that the eddy viscosity in the staggered flow is roughly 1.5 times as large as that for the inline cross flow, 60 times as large as that for the parallel flow, and 105 as large as that for the molecular viscosity. Then, the different terms are combined with each other to result in a global eddy viscosity model for a steam generator tube bundle flow. (author)

  9. Hydrodynamic behavior of a bare rod bundle. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Bartzis, J.G.; Todreas, N.E.

    1977-06-01

    The temperature distribution within the rod bundle of a nuclear reactor is of major importance in nuclear reactor design. However temperature information presupposes knowledge of the hydrodynamic behavior of the coolant which is the most difficult part of the problem due to complexity of the turbulence phenomena. In the present work a 2-equation turbulence model--a strong candidate for analyzing actual three dimensional turbulent flows--has been used to predict fully developed flow of infinite bare rod bundle of various aspect ratios (P/D). The model has been modified to take into account anisotropic effects of eddy viscosity. Secondary flow calculations have been also performed although the model seems to be too rough to predict the secondary flow correctly. Heat transfer calculations have been performed to confirm the importance of anisotropic viscosity in temperature predictions. All numerical calculations for flow and heat have been performed by two computer codes based on the TEACH code. Experimental measurements of the distribution of axial velocity, turbulent axial velocity, turbulent kinetic energy and radial Reynolds stresses were performed in the developing and fully developed regions. A 2-channel Laser Doppler Anemometer working on the Reference mode with forward scattering was used to perform the measurements in a simulated interior subchannel of a triangular rod array with P/D = 1.124. Comparisons between the analytical results and the results of this experiment as well as other experimental data in rod bundle array available in literature are presented. The predictions are in good agreement with the results for the high Reynolds numbers.

  10. Transient void fraction measurements in rod bundle geometries

    International Nuclear Information System (INIS)

    Chan, A.M.C.

    1998-01-01

    A new gamma densitometer with a Ba-133 source and a Nal(TI) scintillator operated in the count mode has been designed for transient void fraction measurements in the RD-14M heated channels containing a seven-element heater bundle. The device was calibrated dynamically in the laboratory using an air-water flow loop. The void fraction measured was found to compare well with values obtained using the trapped-water method. The device was also found to follow very well the passage of air slugs in pulsating flow with slug passing frequencies of up to about 1.5 hz. (author)

  11. Visualization of the medial forebrain bundle using diffusion tensor imaging

    Directory of Open Access Journals (Sweden)

    Ardian eHana

    2015-10-01

    Full Text Available Diffusion tensor imaging is a technique that enables physicians the portrayal of white matter tracts in vivo. We used this technique in order to depict the medial forebrain bundle in 15 consecutive patients between 2012 and 2015. Men and women of all ages were included. There were 6 women and 9 men. The mean age was 58,6 years (39-77. Nine patients were candidates for an eventual deep brain stimulation. Eight of them suffered from Parkinson`s disease and one had multiple sclerosis. The remaining 6 patients suffered from different lesions which were situated in the frontal lobe. These were 2 metastasis, 2 meningiomas, 1 cerebral bleeding and 1 glioblastoma. We used a 3DT1-sequence for the navigation. Furthermore T2- and DTI- sequences were performed. The FOV was 200 x 200 mm², slice thickness 2 mm, and an acquisition matrix of 96 x 96 yielding nearly isotropic voxels of 2 x 2 x 2 mm. 3-Tesla-MRI was carried out strictly axial using 32 gradient directions and one b0-image. We used Echo-Planar-Imaging (EPI and ASSET parallel imaging with an acceleration factor of 2. b-value was 800 s/mm². The maximal angle was 50°. Additional scanning time was less than 9 minutes. We were able to visualize the medial forebrain bundle in 12 of our patients bilaterally and in the remaining 3 patients we depicted the medial forebrain bundle on one side. It was the contralateral side of the lesion. These were 2 meningiomas and one metastasis. Portrayal of the medial forebrain bundle is possible for everyday routine for neurosurgical interventions. As part of the reward circuitry it might be of substantial importance for neurosurgeons during deep brain stimulation in patients with psychiatric disorders. Furthermore it might explain at a certain extent character changes in patients with lesions in the frontal lobe. Surgery in this part of the brain should always take the preservation of this white matter tract into account.

  12. Heat transfer in rod bundles with severe clad deformations

    International Nuclear Information System (INIS)

    Ihle, P.

    1984-04-01

    The content of the paper is focused on heat transfer conditions during the reflood phase of a LOCA in slightly to severely deformed PWR fuel rod bundle geometries. The status of analytical and, especially, of experimental work is described as far as it is possible within this frame. Emphasis is placed on the presentation of the results of ''Flooding Experiments with Blocked Arrays'' (FEBA), a program performed at the Kernforschungszentrum Karlsruhe in the frame of the Project Nuclear Safety (PNS). (orig./WL) [de

  13. Numerical simulation of flow-induced vibrations in tube bundles

    International Nuclear Information System (INIS)

    Elisabeth Longatte; Zaky Bendjeddou; Mhamed Souli

    2005-01-01

    Full text of publication follows: In many industrial components mechanical structures like rod cluster control assembly, fuel assembly and heat exchanger tube bundles are submitted to complex flows causing possible vibrations and damage. Fluid forces are usually split into two parts: structure motion independent forces and fluid-elastic forces coupled with tube motion and responsible for possible dynamic instability development leading to possible short term failures through high amplitude vibrations. Most classical fluid force identification methods rely on structure response experimental measurements associated with convenient data processes. Owing to recent improvements in Computational Fluid Dynamics (C.F.D.), numerical fluid force identification is now practicable in the presence of industrial configurations. The present paper is devoted to numerical simulation of flow-induced vibrations of tube bundles submitted to single-phase cross flows by using C.F.D. codes. Direct Numerical Simulation (D.N.S.), Arbitrary Lagrange Euler formulation (A.L.E.) and code coupling process are involved to predict fluid forces responsible for tube bundle vibrations in the presence of fluid structure and fluid-elastic coupling effects. In the presence of strong multi-physics coupling, simulation of flow-induced vibrations requires a fluid structure code coupling process. The methodology consists in solving in the same time thermohydraulics and mechanics problems by using an A.L.E. formulation for the fluid computation. The purpose is to take into account coupling between flow and structure motions in order to be able to capture coupling effects. From a numerical point of view, there are three steps in the computation: the fluid problem is solved on the computational domain; fluid forces acting on the moving tube are estimated; finally they are introduced in the structure solver providing the tube displacement that is used to actualize the fluid computational domain. Specific

  14. Thermohydraulic tests of 3x3-rod bundle maquette

    International Nuclear Information System (INIS)

    Ladeira, L.C.D.

    1986-10-01

    The results of a 3x3-rod bundle thermohydraulic research program, performed in the Thermohydraulics Laboratory of NUCLEBRAS' Nuclear Technology Development Center, are briefly described. This program included measurements of pressure drops in one and two-phase flows, heat transfer coefficients, mixing between interconnected subchannels in one-phase flow conditions and critical heat fluxes. The measurements covered the following parameter ranges: heat fluxes from zero to the critical values, pressure ranging from 1 to 15 ata, inlet temperature from 25 to 150 sup(0)C and flow rate from 20 to 300l/min. (author)

  15. Maximum allowable heat flux for a submerged horizontal tube bundle

    International Nuclear Information System (INIS)

    McEligot, D.M.

    1995-01-01

    For application to industrial heating of large pools by immersed heat exchangers, the socalled maximum allowable (or open-quotes criticalclose quotes) heat flux is studied for unconfined tube bundles aligned horizontally in a pool without forced flow. In general, we are considering boiling after the pool reaches its saturation temperature rather than sub-cooled pool boiling which should occur during early stages of transient operation. A combination of literature review and simple approximate analysis has been used. To date our main conclusion is that estimates of q inch chf are highly uncertain for this configuration

  16. Hermitian-Einstein metrics on parabolic stable bundles

    International Nuclear Information System (INIS)

    Li Jiayu; Narasimhan, M.S.

    1995-12-01

    Let M-bar be a compact complex manifold of complex dimension two with a smooth Kaehler metric and D a smooth divisor on M-bar. If E is a rank 2 holomorphic vector bundle on M-bar with a stable parabolic structure along D, we prove the existence of a metric on E' = E module MbarD (compatible with the parabolic structure) which is Hermitian-Einstein with respect to the restriction of Kaehler metric of M-barD. A converse is also proved. (author). 24 refs

  17. Rigidity of minimal submanifolds with flat normal bundle

    Indian Academy of Sciences (India)

    Rigidity of minimal submanifolds with flat normal bundle. 461. = a. ∫. M u2(1+q)+ 2 a f 2 − 2. ∫. M u2q+1f 〈∇f, ∇u〉. − (2q + 1). ∫. M u2qf 2|∇u|2, which gives a .... that depends on n, ϵ and q. We now try to transform (2.15) the right hand side only involved u in the power two. For that, we use Young's inequality: ab ≤ βsas.

  18. Relative desorption of boiling crisis in rod bundles

    International Nuclear Information System (INIS)

    Bobkov, V.P.

    1997-01-01

    Results of describing critical heat fluxes rod bundles are presented on base of applying a generalization of the available massive of data on CHF in spherical tubes, performed on the base of a new model, developed by the physics and Power Institute specialists, as well as on the base of results of analysing comprehensive experimental material accumulated in the data bank of the Thermophysical Data Center of the PPI Ratios, allowing one to predict the values of the critical heat flux in a wide range of mode and geometry parameters under energy release with cross section variations and cross section geometry distortion are presented

  19. A locking device for fuel bundles of power nuclear reactors

    International Nuclear Information System (INIS)

    Long, John; Flora, B.S.

    1974-01-01

    The present invention relates to a locked assembly associated by brace rods and easily dismountable. It comprises a locking sleeve provided with lugs engaged in bores of the upper plate, said sleeve being biassed towards said plate by a spring. For dismounting the bundle, the plate is pushed against the action of the springs and each sleeve, provided with flat faces is pivoted until it reaches the unlocking position. A guide member prevents each brace rod from being unscrewed from the lower plate. This can be applied to the remote dis-assembling of the fuel rods of a power reactor [fr

  20. Noncommutative vector bundles over fuzzy CPN and their covariant derivatives

    International Nuclear Information System (INIS)

    Dolan, Brian P.; Huet, Idrish; Murray, Sean; O'Connor, Denjoe

    2007-01-01

    We generalise the construction of fuzzy CP N in a manner that allows us to access all noncommutative equivariant complex vector bundles over this space. We give a simplified construction of polarization tensors on S 2 that generalizes to complex projective space, identify Laplacians and natural noncommutative covariant derivative operators that map between the modules that describe noncommuative sections. In the process we find a natural generalization of the Schwinger-Jordan construction to su(n) and identify composite oscillators that obey a Heisenberg algebra on an appropriate Fock space

  1. Partial tears of anterior cruciate ligament: Results of single bundle augmentation

    OpenAIRE

    Sabat, Dhananjaya; Kumar, Vinod

    2015-01-01

    Background: Partial tears of the anterior cruciate ligament (ACL) are common and usually present with symptomatic instability. The remnant fibers are usually removed and a traditional ACL reconstruction is done. But with increased understanding of ACL double bundle anatomy, the remnant tissue preservation along with a single bundle augmentation of the torn bundle is also suggested. The purpose of this study was to evaluate the results of selective anatomic augmentation of symptomatic partial ...

  2. Classification theorem for principal fibre bundles, Berry's phase, and exact cycle evolution

    International Nuclear Information System (INIS)

    Bohm, A.; Boya, L.J.; Mostafazadeh, A.; Rudolph, G.

    1993-03-01

    The relation between the two mathematical interpretations of the geometric (Berry) phase is discussed, using either the fibre bundle over parameter space or over projective Hilbert space. It turns out that these two geometric constructions are linked by the classification theorem for vector bundles. The classification theorem provides the means to classify the parameter space bundles for adiabatic evolution and for non-adiabatic cyclic evolution of the statevectors

  3. Geometric quantization of vector bundles and the correspondence with deformation quantization

    International Nuclear Information System (INIS)

    Hawkins, E.

    2000-01-01

    I repeat my definition for quantization of a vector bundle. For the cases of the Toeplitz and geometric quantizations of a compact Kaehler manifold, I give a construction for quantizing any smooth vector bundle, which depends functorially on a choice of connection on the bundle. Using this, the classification of formal deformation quantizations, and the formal, algebraic index theorem, I give a simple proof as to which formal deformation quantization (modulo isomorphism) is derived from a given geometric quantization. (orig.)

  4. Channeling and energy losses of 10 MeV protons in straight chiral carbon nanotube bundles

    International Nuclear Information System (INIS)

    Karabarbounis, A.; Sarros, S.; Trikalinos, Ch.

    2013-01-01

    Channeling of 10 MeV protons in straight chiral single carbon nanotubes (6, 4) and (11, 9), as well as in corresponding nanotube bundles is considered. Monte Carlo simulation program is used for the calculation of the trajectories, energy losses and angular distributions of protons in nanotubes and bundles of various lengths and different incident angles. The energy distribution of protons channeled through single carbon nanotubes, as well as through corresponding nanotube bundles are also examined

  5. Preliminary analysis of axial flow-induced vibration on fuel bundle

    International Nuclear Information System (INIS)

    Sim, Woo-Gun; Park, Mi-Yeon

    2007-03-01

    An analytical simple-approach is introduced to review the experimental results of dynamic behavior for trial fuel bundle assembly. To develop the simple model, hydrodynamic force is introduced based on velocity potential and added mass coefficients of fuel bundles. General characteristics of FIV motion in parallel flow are discussed. Modal test for natural frequency of rod and bundle is required to be performed. Typical results of dynamic response are evaluated

  6. Effects of ABCDE Bundle on Hemodynamics in Patients on Mechanical Ventilation.

    Science.gov (United States)

    Ren, Xiao-Li; Li, Jian-Hua; Peng, Chong; Chen, Hong; Wang, Hai-Xia; Wei, Xue-Ling; Cheng, Qing-Hong

    2017-09-28

    BACKGROUND Mechanical ventilation is an important part of advanced life support in the intensive care unit (ICU). This study aimed to investigate the effects of ABCDE bundle on hemodynamics in patients on mechanical ventilation (MV). MATERIAL AND METHODS This study used a cross-sectional overall controlled approach in which 143 patients on mechanical ventilation were divided into 2 groups. In the pre-ABCDE bundle group (n=70), conventional sedation and analgesia strategy were used. In the post-ABCDE bundle group (n=73), ABCDE bundle was used. Changes in hemodynamics parameters and related prognostic indicators were monitored at various time points before (T0) and at 1 d (T1), 3 d (T3), 5 d (T5), and 7 d (T7) after implementation of the 2 strategies. RESULTS Mean arterial blood pressure (MAP), central venous pressure (CVP), heart rate (HR), and oxygenation index (PaO2/FiO2) in the bundle group were improved more significantly than those in the pre-ABCDE bundle group (P<0.05). For comparison between various monitoring time points in the same group, compared with before intervention, MAP, CVP, HR, and PaO2/FiO2 changed significantly in the bundle group at 3 d, 5 d, and 7 d after intervention, and the difference was statistically significant (P<0.05). Compared with before intervention, differences in all hemodynamics indicators were statistically significant in the pre-ABCDE bundle group at 5 d and 7 d after intervention (P<0.05). Compared with the pre-ABCDE bundle group, differences in prognostic indicators in the post-ABCDE bundle were statistically significant (P<0.05). CONCLUSIONS ABCDE bundle is safe and effective for patients on mechanical ventilation, and can improve hemodynamics and enhance oxygenation index. ABCDE bundle might be helpful in reducing 28-d mortality and improving prognosis.

  7. Helicobacter pylori FlhB function: the F1hB C-terminal homologue HP1575 acts as a "Spare part" to permit flagellar export when the HP0770 FlhB(CC) domain is deleted

    OpenAIRE

    Wand, Matthew E.; Sockett, R. Elizabeth; Evans, Katy J.; Doherty, Neil; Sharp, Paul M.; Hardie, Kim R.; Winzer, Klaus

    2006-01-01

    In Helicobacterpylori 26695, a gene annotated HP1575 encodes a putative protein of unknown function which shows significant similarity to part of the C-terminal domain of the flagellar export protein FlhB. In Salmonella enterica, this part (FibB,c) is proteolytically cleaved from the full-length FlhB, a processing event that is required for flagellar protein export and, thus, motility. The role of FlhB (HP0770) and its C-terminal homologue HP1575 was studied in H. pylori using a range of nonp...

  8. Effects of the somatic electrical circuit on spontaneous mechanical oscillations of inner ear hair bundles

    Science.gov (United States)

    Ramunno-Johnson, Damien; Strimbu, C. Elliott; Fredrickson, Lea; Kao, Albert; Bozovic, Dolores

    2010-03-01

    Under in vitro conditions, uncoupled hair bundles of the bullfrog (Rana catesbeiana) sacculus have been shown to exhibit spontaneous oscillations. We used a high-speed complementary metal oxide semiconductor camera to track the movements of hundreds of cells in parallel from dozens of preparations. We found that innate bundle movements exhibit a complex profile with multiple periodicities. Experiments inhibiting the electrical resonance in the cell body show a strong effect on the mechanical oscillations of the hair bundles. This indicates that the electrical oscillation is coupled with the mechanical oscillations of the hair bundles.

  9. Purification and alignment of arc-synthesis single-walled carbon nanotube bundles

    Science.gov (United States)

    Huang, Houjin; Kajiura, Hisashi; Yamada, Atsuo; Ata, Masafumi

    2002-04-01

    We report here a scalable method for purification and alignment of single-walled carbon nanotubes (SWNT) in an aqueous solution. Arc-synthesis soot containing SWNTs is first treated with a concentrated nitric acid. After removal of most of the impurities and water, macroscopic and well-aligned SWNT bundles up to several centimeters long are formed in a rotary evaporator. Alignment of the SWNT bundles is ascribed to the liquid flow induced by rotary evaporation and van der Waals interactions among the bundles. The aligned SWNT bundles are further purified by ultrasonic Soxhlet extraction and annealing.

  10. The value of the abnormalities of bronchovascular bundles in the diagnosis of diffused lung diseases

    International Nuclear Information System (INIS)

    Li Tieyi; Ji Jingling

    1997-01-01

    To evaluate the abnormalities of bronchovascular bundles in the differential diagnosis of the diffuse lung disease, seventy-two patients with diffuse lung diseases were evaluated, 15 of 72 patients were pathologically proven and the others clinically proven. Of these 72 patients, there were 33 patients with diffuse pulmonary interstitial disease, 5 patients with pulmonary parenchymal disease, 14 patients with bronchial disease, and 20 patients with disseminated disease. All patients had conventional CT scan of the chest, some also had HRCT scan. All CT images were jointly reviewed by two radiologists. The features of the abnormalities of bronchovascular bundles included: (1) Thinning of bronchovascular bundles, predominantly seen in diffuse interstitial disease of lung and chronic bronchitis; (2) thickening of bronchovascular bundles, predominantly seen in interstitial diseases and disseminated lung diseases such as sarcoidosis and lymphangitis carcinomatosis with beaded appearance of bronchovascular bundles; (3) Increased visibility of bronchovascular bundles, predominantly seen in bronchiolitis and disseminated lung diseases. CT features of the abnormalities of bronchovascular bundles are present in 80% of diffuse lung diseases. The features are not specific, but the beaded bronchovascular bundles are always seen in sarcoidosis and lymphangitis carcinomatosis. In making a distinction between idiopathic pulmonary fibrosis and chronic bronchitis complicated with interstitial fibrosis, the position of diaphragm is of value in differential diagnosis, normal or elevated diaphragm is usually seen in the former, while low and flattened diaphragm in the latter. Change of the appearance of bronchovascular bundles from normality to abnormality reflects the process of development of the lung disease

  11. Sperm competition promotes diversity of sperm bundles in Ohomopterus ground beetles

    Science.gov (United States)

    Takami, Yasuoki; Sota, Teiji

    2007-07-01

    Diversification of sperm morphology has been investigated in the context of sperm competition, but the adaptive significance of sperm bundles is still unclear. In analyzing 10 taxa of the genus Carabus subgenus Ohomopterus and one related Carabus ground beetles, we found that dimorphic sperm bundles occurred in most species with varied degrees of bimodality, whereas sperm were generally monomorphic. Comparative analyses with phylogenetically independent contrasts revealed that the sizes of large and small sperm bundles evolved more rapidly than, and were not correlated with, the length of sperm, suggesting more intense selection on sperm bundle sizes and their independent responses to different evolutionary forces. The size of large sperm bundles was positively correlated with male genital morphology (pertinent to displacement of rival spermatophores) and postcopulatory guarding duration as well as male body length, suggesting that larger sperm bundles have been favored when the risk of spermatophore displacement is high. Larger sperm bundles may be advantageous because of their ability to migrate more rapidly into the spermatheca. In contrast, no clear association was detected between the small sperm bundle size and mating traits despite its rapid diversification. The present study provides the first record of heteromorphic sperm bundles, the diversity of which may be promoted by sperm competition.

  12. Pressure drop redistribution experimental analysis in axial flow along the bundles

    International Nuclear Information System (INIS)

    Bastos Franco, C. de; Carajilescov, P.

    1992-01-01

    Fuel elements of PWR type nuclear reactors are composed of rod bundles, arranged in square arrays, held by grid type spacers. The coolant flows axially along the bundle. Although such elements are laterally open, pressure drop experiments are performed in closed type test sections, originating the appearance of subchannels of different geometries. Utilizing a test section of two bundles of 4 x 4 pins and performing experiments with and without separation between the bundles, the flow redistribution factors, the friction, and the grid drag coefficients were determined for the interior subchannels. 03 refs, 06 figs, 02 tabs. (B.C.A.)

  13. Canonical generators of the cohomology of moduli of parabolic bundles on curves

    International Nuclear Information System (INIS)

    Biswas, I.; Raghavendra, N.

    1994-11-01

    We determine generators of the rational cohomology algebras of moduli spaces of parabolic vector bundles on a curve, under some 'primality' conditions on the parabolic datum. These generators are canonical in a precise sense. Our results are new even for usual vector bundles (i.e., vector bundles without parabolic structure) whose rank is greater than 2 and is coprime to the degree; in this case, they are generalizations of a theorem of Newstead on the moduli of vector bundles of rank 2 and odd degree. (author). 11 refs

  14. Reducing the spread of Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus on a burns unit through the intervention of an infection control bundle.

    Science.gov (United States)

    Barbut, Frédéric; Yezli, Saber; Mimoun, Maurice; Pham, Julien; Chaouat, Marc; Otter, Jonathan A

    2013-05-01

    Methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii are major nosocomial pathogens in burns units. We investigated the impact of an infection control bundle on the incidence of nosocomial MRSA and A. baumannii in our burns unit, comparing a pre-intervention period (December 2006-August 2008) with an intervention period (September 2008-December 2009). The bundle comprised regular hydrogen peroxide vapour (HPV) disinfection of the rooms following discharge of patients colonized or infected by multidrug-resistant bacteria, pre-emptive cohort isolation of newly admitted patients before being proven culture negative, cohorting of colonized or infected patients, installation of two air disinfection systems in the corridors of the unit and improvement of material storage. We also investigated the microbiological efficacy of HPV disinfection by sampling the environment before and after HPV treatments. HPV disinfection eliminated pathogens from the environment and significantly reduced total bacterial surface counts, and total fungal air and surface counts, on both a unit and room scale. The incidence of nosocomial MRSA infection or colonization fell by 89.3% from 7.22 to 0.77 cases/1000 patient days (pcontrol bundle resulted in a significant reduction in the incidence of nosocomial MRSA and A. baumannii in our burns unit and prevented further outbreaks of these organisms. Copyright © 2012 Elsevier Ltd and ISBI. All rights reserved.

  15. Cortactin Adopts a Globular Conformation and Bundles Actin into Sheets

    Energy Technology Data Exchange (ETDEWEB)

    Cowieson, Nathan P.; King, Gordon; Cookson, David; Ross, Ian; Huber, Thomas; Hume, David A.; Kobe, Bostjan; Martin, Jennifer L. (Queensland); (Aust. Synch.)

    2008-08-21

    Cortactin is a filamentous actin-binding protein that plays a pivotal role in translating environmental signals into coordinated rearrangement of the cytoskeleton. The dynamic reorganization of actin in the cytoskeleton drives processes including changes in cell morphology, cell migration, and phagocytosis. In general, structural proteins of the cytoskeleton bind in the N-terminal region of cortactin and regulatory proteins in the C-terminal region. Previous structural studies have reported an extended conformation for cortactin. It is therefore unclear how cortactin facilitates cross-talk between structural proteins and their regulators. In the study presented here, circular dichroism, chemical cross-linking, and small angle x-ray scattering are used to demonstrate that cortactin adopts a globular conformation, thereby bringing distant parts of the molecule into close proximity. In addition, the actin bundling activity of cortactin is characterized, showing that fully polymerized actin filaments are bundled into sheet-like structures. We present a low resolution structure that suggests how the various domains of cortactin interact to coordinate its array of binding partners at sites of actin branching.

  16. Optimal file-bundle caching algorithms for data-grids

    Energy Technology Data Exchange (ETDEWEB)

    Otoo, Ekow; Rotem, Doron; Romosan, Alexandru

    2004-04-24

    The file-bundle caching problem arises frequently in scientific applications where jobs need to process several files simultaneously. Consider a host system in a data-grid that maintains a staging disk or disk cache for servicing jobs of file requests. In this environment, a job can only be serviced if all its file requests are present in the disk cache. Files must be admitted into the cache or replaced in sets of file-bundles, i.e. the set of files that must all be processed simultaneously. In this paper we show that traditional caching algorithms based on file popularity measures do not perform well in such caching environments since they are not sensitive to the inter-file dependencies and may hold in the cache non-relevant combinations of files. We present and analyze a new caching algorithm for maximizing the throughput of jobs and minimizing data replacement costs to such data-grid hosts. We tested the new algorithm using a disk cache simulation model under a wide range of conditions such as file request distributions, relative cache size, file size distribution, etc. In all these cases, the results show significant improvement as compared with traditional caching algorithms.

  17. Prostaglandins temporally regulate cytoplasmic actin bundle formation during Drosophila oogenesis

    Science.gov (United States)

    Spracklen, Andrew J.; Kelpsch, Daniel J.; Chen, Xiang; Spracklen, Cassandra N.; Tootle, Tina L.

    2014-01-01

    Prostaglandins (PGs)—lipid signals produced downstream of cyclooxygenase (COX) enzymes—regulate actin dynamics in cell culture and platelets, but their roles during development are largely unknown. Here we define a new role for Pxt, the Drosophila COX-like enzyme, in regulating the actin cytoskeleton—temporal restriction of actin remodeling during oogenesis. PGs are required for actin filament bundle formation during stage 10B (S10B). In addition, loss of Pxt results in extensive early actin remodeling, including actin filaments and aggregates, within the posterior nurse cells of S9 follicles; wild-type follicles exhibit similar structures at a low frequency. Hu li tai shao (Hts-RC) and Villin (Quail), an actin bundler, localize to all early actin structures, whereas Enabled (Ena), an actin elongation factor, preferentially localizes to those in pxt mutants. Reduced Ena levels strongly suppress early actin remodeling in pxt mutants. Furthermore, loss of Pxt results in reduced Ena localization to the sites of bundle formation during S10B. Together these data lead to a model in which PGs temporally regulate actin remodeling during Drosophila oogenesis by controlling Ena localization/activity, such that in S9, PG signaling inhibits, whereas at S10B, it promotes Ena-dependent actin remodeling. PMID:24284900

  18. Optimal Nonlinear Pricing, Bundling Commodities and Contingent Services

    International Nuclear Information System (INIS)

    Podesta, Marion; Poudou, Jean-Christophe

    2008-01-01

    In this paper, we propose to analyze optimal nonlinear pricing when a firm offers in a bundle a commodity and a contingent service. The paper studies a mechanism design where all private information can be captured in a single scalar variable in a monopoly context. We show that to propose the package for commodity and service is less costly for the consumer, the firm has lower consumers' rent than the situation where it sells their good and contingent service under an independent pricing strategy. In fact, the possibility to use price discrimination via the supply of package is dominated by the fact that it is costly for the consumer to sign two contracts. Bundling energy and a contingent service is a profitable strategy for a energetician monopoly practising optimal nonlinear tariff. We show that the rates of the energy and the contingent service depend to the optional character of the contingent service and depend to the degree of complementarity between commodities and services. (authors)

  19. Damping in heat exchanger tube bundles. A review

    International Nuclear Information System (INIS)

    Iqbal, Qamar; Khushnood, Shahab; Ghalban, Ali Roheim El; Sheikh, Nadeem Ahmed; Malik, Muhammad Afzaal; Arastu, Asif

    2007-01-01

    Damping is a major concern in the design and operation of tube bundles with loosely supported tubes in baffles for process shell and tube heat exchangers and steam generators which are used in nuclear, process and power generation industries. System damping has a strong influence on the amplitude of vibration. Damping depends upon the mechanical properties of the tube material, geometry of intermediate supports and the physical properties of shell-side fluid. Type of tube motion, number of supports, tube frequency, vibration amplitude, tube mass or diameter, side loads, support thickness, higher modes, shell-side temperature etc., affect damping in tube bundles. The importance of damping is further highlighted due to current trend of larger exchangers with increased shell-side velocities in modern units. Various damping mechanisms have been identified (Friction damping, Viscous damping, Squeeze film damping, Support damping. Two-Phase damping, and very recent-Thermal damping), which affect the performance of process exchangers and steam generators with respect to flow induced vibration design, including standard design guidelines. Damping in two-phase flow is very complex and highly void fraction, and flow-regime dependent. The current paper focuses on the various known damping mechanisms subjected to both single and two-phase cross-flow in process heat exchangers and steam generators and formulates the design guidelines for safer design. (author)

  20. Hair cell bundles: flexoelectric motors of the inner ear.

    Directory of Open Access Journals (Sweden)

    Kathryn D Breneman

    Full Text Available Microvilli (stereocilia projecting from the apex of hair cells in the inner ear are actively motile structures that feed energy into the vibration of the inner ear and enhance sensitivity to sound. The biophysical mechanism underlying the hair bundle motor is unknown. In this study, we examined a membrane flexoelectric origin for active movements in stereocilia and conclude that it is likely to be an important contributor to mechanical power output by hair bundles. We formulated a realistic biophysical model of stereocilia incorporating stereocilia dimensions, the known flexoelectric coefficient of lipid membranes, mechanical compliance, and fluid drag. Electrical power enters the stereocilia through displacement sensitive ion channels and, due to the small diameter of stereocilia, is converted to useful mechanical power output by flexoelectricity. This motor augments molecular motors associated with the mechanosensitive apparatus itself that have been described previously. The model reveals stereocilia to be highly efficient and fast flexoelectric motors that capture the energy in the extracellular electro-chemical potential of the inner ear to generate mechanical power output. The power analysis provides an explanation for the correlation between stereocilia height and the tonotopic organization of hearing organs. Further, results suggest that flexoelectricity may be essential to the exquisite sensitivity and frequency selectivity of non-mammalian hearing organs at high auditory frequencies, and may contribute to the "cochlear amplifier" in mammals.

  1. Hair cell bundles: flexoelectric motors of the inner ear.

    Science.gov (United States)

    Breneman, Kathryn D; Brownell, William E; Rabbitt, Richard D

    2009-01-01

    Microvilli (stereocilia) projecting from the apex of hair cells in the inner ear are actively motile structures that feed energy into the vibration of the inner ear and enhance sensitivity to sound. The biophysical mechanism underlying the hair bundle motor is unknown. In this study, we examined a membrane flexoelectric origin for active movements in stereocilia and conclude that it is likely to be an important contributor to mechanical power output by hair bundles. We formulated a realistic biophysical model of stereocilia incorporating stereocilia dimensions, the known flexoelectric coefficient of lipid membranes, mechanical compliance, and fluid drag. Electrical power enters the stereocilia through displacement sensitive ion channels and, due to the small diameter of stereocilia, is converted to useful mechanical power output by flexoelectricity. This motor augments molecular motors associated with the mechanosensitive apparatus itself that have been described previously. The model reveals stereocilia to be highly efficient and fast flexoelectric motors that capture the energy in the extracellular electro-chemical potential of the inner ear to generate mechanical power output. The power analysis provides an explanation for the correlation between stereocilia height and the tonotopic organization of hearing organs. Further, results suggest that flexoelectricity may be essential to the exquisite sensitivity and frequency selectivity of non-mammalian hearing organs at high auditory frequencies, and may contribute to the "cochlear amplifier" in mammals.

  2. Fluidic delivery of homogeneous solutions through carbon tube bundles

    International Nuclear Information System (INIS)

    Srikar, R; Yarin, A L; Megaridis, C M

    2009-01-01

    A wide array of technological applications requires localized high-rate delivery of dissolved compounds (in particular, biological ones), which can be achieved by forcing the solutions or suspensions of such compounds through nano or microtubes and their bundled assemblies. Using a water-soluble compound, the fluorescent dye Rhodamine 610 chloride, frequently used as a model drug release compound, it is shown that deposit buildup on the inner walls of the delivery channels and its adverse consequences pose a severe challenge to implementing pressure-driven long-term fluidic delivery through nano and microcapillaries, even in the case of such homogeneous solutions. Pressure-driven delivery (3-6 bar) of homogeneous dye solutions through macroscopically-long (∼1 cm) carbon nano and microtubes with inner diameters in the range 100 nm-1 μm and their bundled parallel assemblies is studied experimentally and theoretically. It is shown that the flow delivery gradually shifts from fast convection-dominated (unobstructed) to slow jammed convection, and ultimately to diffusion-limited transport through a porous deposit. The jamming/clogging phenomena appear to be rather generic: they were observed in a wide concentration range for two fluorescent dyes in carbon nano and microtubes, as well as in comparable transparent glass microcapillaries. The aim of the present work is to study the physics of jamming, rather than the chemical reasons for the affinity of dye molecules to the tube walls.

  3. A Xanthomonas citri subsp citri hypothetical protein related to virulence contains a non-functional HD domain and is implicated in flagellar motility.

    Science.gov (United States)

    Vieira, F C F; Gonçalves, A M; Mendoza, E F R; Ferreira, R M; Costa, M L M; Balbuena, T S; Sebinelli, H G; Ciancaglini, P; Pizauro Junior, J M; Ferro, J A

    2017-08-31

    Citrus canker, caused by the Gram-negative bacterium Xanthomonas citri subsp citri (Xac), severely affects most economically important citrus varieties worldwide. A previous study showed that disruption of the ORF XAC1201 from the Xac 306 strain by transposon Tn5 decreased bacterium virulence in the Rangpur lime host (Citrus limonia L. Osbeck). However, little is known regarding the possible function of the hypothetical protein XAC1201 and how it affects the virulence of Xac 306. Here, we confirmed that disruption of ORF XAC1201 reduces Xac 306 virulence in two different hosts, delaying the onset of typical symptoms. In silico analysis suggested that XAC1201 interacts with the flagellar proteins FliM and FliL, known to be an important factor for virulence. In fact, motility assays revealed that the XAC1201 mutant has a significant difference in motility compared to the wild-type Xac 306. Also, a 3-D structure model revealed modified cofactor binding sites and suggested that XAC1201 has a non-functional HD domain. This hypothesis was confirmed by enzymatic assays performed in purified, XAC1201 recombinant protein expressed in Escherichia coli, which revealed no significant activities previously associated with HD domains for the tested substrates. Thus, the role of the XAC1201 protein in Xac 306 virulence seems to be related to flagellar motility, although a non-classic role for the HD domain cannot be dismissed.

  4. Cloning, purification, crystallization and preliminary X-ray studies of flagellar hook scaffolding protein FlgD from Pseudomonas aeruginosa PAO1

    International Nuclear Information System (INIS)

    Luo, Miao; Niu, Siqiang; Yin, Yibing; Huang, Ailong; Wang, Deqiang

    2009-01-01

    In order to better elucidate the functions of FlgD in flagellar hook biosynthesis, the three-dimensional structure of FlgD is being determined by X-ray crystallography. Here, the expression, purification, crystallization and preliminary crystallographic analysis of FlgD from P. aeruginosa are reported. FlgD regulates the assembly of the hook cap structure to prevent leakage of hook monomers into the medium and hook monomer polymerization and also plays a role in determination of the correct hook length, with the help of the FliK protein. In order to better elucidate the functions of FlgD in flagellar hook biosynthesis, the three-dimensional structure of FlgD is being determined by X-ray crystallography. Here, the expression, purification, crystallization and preliminary crystallographic analysis of FlgD from P. aeruginosa are reported. The crystal belonged to space group I222 and diffracted to a resolution of 2.5 Å, with unit-cell parameters a = 116.47, b = 118.71, c = 118.85 Å. The crystals are most likely to contain three molecules in the asymmetric unit, with a V M value of 2.73 Å 3 Da −1

  5. Activation of ganglion cells and axon bundles using epiretinal electrical stimulation.

    Science.gov (United States)

    Grosberg, Lauren E; Ganesan, Karthik; Goetz, Georges A; Madugula, Sasidhar S; Bhaskhar, Nandita; Fan, Victoria; Li, Peter; Hottowy, Pawel; Dabrowski, Wladyslaw; Sher, Alexander; Litke, Alan M; Mitra, Subhasish; Chichilnisky, E J

    2017-09-01

    Epiretinal prostheses for treating blindness activate axon bundles, causing large, arc-shaped visual percepts that limit the quality of artificial vision. Improving the function of epiretinal prostheses therefore requires understanding and avoiding axon bundle activation. This study introduces a method to detect axon bundle activation on the basis of its electrical signature and uses the method to test whether epiretinal stimulation can directly elicit spikes in individual retinal ganglion cells without activating nearby axon bundles. Combined electrical stimulation and recording from isolated primate retina were performed using a custom multielectrode system (512 electrodes, 10-μm diameter, 60-μm pitch). Axon bundle signals were identified by their bidirectional propagation, speed, and increasing amplitude as a function of stimulation current. The threshold for bundle activation varied across electrodes and retinas, and was in the same range as the threshold for activating retinal ganglion cells near their somas. In the peripheral retina, 45% of electrodes that activated individual ganglion cells (17% of all electrodes) did so without activating bundles. This permitted selective activation of 21% of recorded ganglion cells (7% of expected ganglion cells) over the array. In one recording in the central retina, 75% of electrodes that activated individual ganglion cells (16% of all electrodes) did so without activating bundles. The ability to selectively activate a subset of retinal ganglion cells without axon bundles suggests a possible novel architecture for future epiretinal prostheses. NEW & NOTEWORTHY Large-scale multielectrode recording and stimulation were used to test how selectively retinal ganglion cells can be electrically activated without activating axon bundles. A novel method was developed to identify axon activation on the basis of its unique electrical signature and was used to find that a subset of ganglion cells can be activated at single

  6. A comparative CFD investigation of helical wire-wrapped 7, 19 and 37 fuel pin bundles and its extendibility to 217 pin bundle

    International Nuclear Information System (INIS)

    Gajapathy, R.; Velusamy, K.; Selvaraj, P.; Chellapandi, P.; Chetal, S.C.

    2009-01-01

    Preliminary investigations of sodium flow and temperature distributions in heat generating fuel pin bundles with helical spacer wires have been carried out. Towards this, the 3D conservation equations of mass, momentum and energy have been solved using a commercial computational fluid dynamics (CFD) code. Turbulence has been accounted through the use of high Reynolds number version of standard k-ε model, with uniform mesh density respecting wall function requirements. The geometric details of the bundle and the heat flux in are similar to that of the Indian Prototype Fast Breeder Reactor (PFBR) that is currently under construction. The mixing characteristics of the flow among the peripheral and central zones are compared for 7, 19 and 37 fuel pin bundles and the characteristics are extended to a 217 pin bundle. The friction factors of the pin bundles obtained from the present study is seen to agree well with the values derived from experimental correlations. It is found that the normalized outlet velocities in the peripheral and central zones are nearly equal to 1.1-0.9, respectively which is in good agreement with the published hydraulic experimental measurements of 1.1-0.85 for a 91 pin bundle. The axial velocity is the maximum in the peripheral zone where spacer wires are located and minimum in the zones which are diametrically opposite to the respective zone of maximum velocity. The sodium temperature is higher in the zones where the flow area and mass flow rates are less due to the presence of the spacer wires though the axial velocity is higher there. It is the minimum in the peripheral zones where the circumferential flow is larger. Based on the flow and temperature distributions obtained for 19 and 37 pin bundles, a preliminary extrapolation procedure has been established for estimating the temperatures of peripheral and central zones of 217 pin bundle.

  7. Incorporating Endmember Variability into Spectral Mixture Analysis Through Endmember Bundles

    Science.gov (United States)

    Bateson, C. Ann; Asner, Gregory P.; Wessman, Carol A.

    1998-01-01

    Variation in canopy structure and biochemistry induces a concomitant variation in the top-of-canopy spectral reflectance of a vegetation type. Hence, the use of a single endmember spectrum to track the fractional abundance of a given vegetation cover in a hyperspectral image may result in fractions with considerable error. One solution to the problem of endmember variability is to increase the number of endmembers used in a spectral mixture analysis of the image. For example, there could be several tree endmembers in the analysis because of differences in leaf area index (LAI) and multiple scatterings between leaves and stems. However, it is often difficult in terms of computer or human interaction time to select more than six or seven endmembers and any non-removable noise, as well as the number of uncorrelated bands in the image, limits the number of endmembers that can be discriminated. Moreover, as endmembers proliferate, their interpretation becomes increasingly difficult and often applications simply need the aerial fractions of a few land cover components which comprise most of the scene. In order to incorporate endmember variability into spectral mixture analysis, we propose representing a landscape component type not with one endmember spectrum but with a set or bundle of spectra, each of which is feasible as the spectrum of an instance of the component (e.g., in the case of a tree component, each spectrum could reasonably be the spectral reflectance of a tree canopy). These endmember bundles can be used with nonlinear optimization algorithms to find upper and lower bounds on endmember fractions. This approach to endmember variability naturally evolved from previous work in deriving endmembers from the data itself by fitting a triangle, tetrahedron or, more generally, a simplex to the data cloud reduced in dimension by a principal component analysis. Conceptually, endmember variability could make it difficult to find a simplex that both surrounds the data

  8. Non-properness of the functor of F-trivial bundles

    Indian Academy of Sciences (India)

    We study the properness of the functor of F-trivial bundles by relating it to the base change question for the .... a nonconstant family of stable, F-trivial vector bundles, which is not constant. Therefore,. Question 2 is false, hence ..... Pure Math., 80, Part I, AMS, Providence RI (2009). [9] Langton S G, Valuative criteria for families ...

  9. Textbook-Bundled Metacognitive Tools: A Study of LearnSmart's Efficacy in General Chemistry

    Science.gov (United States)

    Thadani, Vandana; Bouvier-Brown, Nicole C.

    2016-01-01

    College textbook publishers increasingly bundle sophisticated technology-based study tools with their texts. These tools appear promising, but empirical work on their efficacy is needed. We examined whether LearnSmart, a study tool bundled with McGraw-Hill's textbook "Chemistry" (Chang & Goldsby, 2013), improved learning in an…

  10. Pure infiniteness and ideal structure of C*-algebras associated to Fell bundles

    DEFF Research Database (Denmark)

    Kwasniewski, Bartosz; Szymanski, Wojciech

    2017-01-01

    We investigate structural properties of the reduced cross-sectional algebra C^*_r(B) of a Fell bundle B over a discrete group G. Conditions allowing one to determine the ideal structure of C^*_r(B) are studied. Notions of aperiodicity, paradoxicality and B-infiniteness for the Fell bundle B...

  11. Implementing a Sepsis Resuscitation Bundle Improved Clinical Outcome: A Before-and-After Study

    Directory of Open Access Journals (Sweden)

    Jeongmin Kim

    2014-11-01

    CONCLUSIONS: Repeated education led by a multidisciplinary team and interdisciplinary communication improved the compliance rate of the 6-h resuscitation bundle in severe sepsis and septic shock patients. Compliance with the sepsis resuscitation bundle was associated with improved 28-day mortality in the study population.

  12. On the non-existence of orthogonal instanton bundles on P^{2n+1}

    Directory of Open Access Journals (Sweden)

    Łucja Farnik

    2009-11-01

    Full Text Available In this paper we prove that there do not exist orthogonal instanton bundles on P^{2n+1} . In order to demonstrate this fact, we propose a new way of representing the invariant, introduced by L. Costa and G. Ottaviani, related to a rank 2n instanton bundle on P^{2n+1}.

  13. Darcy Permeability of Hollow Fiber Bundles Used in Blood Oxygenation Devices.

    Science.gov (United States)

    Pacella, Heather E; Eash, Heidi J; Federspiel, William J

    2011-10-15

    Many industrial and biomedical devices (e.g. blood oxygenators and artificial lungs) use bundles of hollow fiber membranes for separation processes. Analyses of flow and mass transport within the shell-side of the fiber bundles most often model the bundle for simplicity as a packed bed or porous media, using a Darcy permeability coefficient estimated from the Blake-Kozeny equation to account for viscous drag from the fibers. In this study, we developed a simple method for measuring the Darcy permeability of hollow fiber membrane bundles and evaluated how well the Blake-Kozeny (BK) equation predicted the Darcy permeability for these bundles. Fiber bundles were fabricated from commercially available Celgard® ×30-240 fiber fabric (300 μm outer diameter fibers @ 35 and 54 fibers/inch) and from a fiber fabric with 193 μm fibers (61 fibers/inch). The fiber bundles were mounted to the bottom of an acrylic tube and Darcy permeability was determined by measuring the elapsed time for a column of glycerol solution to flow through a fiber bundle. The ratio of the measured Darcy permeability to that predicted from the BK equation varied from 1.09 to 0.56. A comprehensive literature review suggested a modified BK equation with the "constant" correlated to porosity. This modification improved the predictions of the BK equation, with the ratio of measured to predicted permeability varying from 1.13 to 0.84.

  14. On rationality of moduli spaces of vector bundles on real Hirzebruch ...

    Indian Academy of Sciences (India)

    Introduction. Moduli spaces of semistable vector bundles on a smooth projective variety are studied from various points of view. One of the questions that is often addressed is the birational type of the moduli space, more precisely, the question of rationality. It is known that the moduli space of semistable vector bundles of ...

  15. Accuracy of Shack-Hartmann wavefront sensor using a coherent wound fibre image bundle

    Science.gov (United States)

    Zheng, Jessica R.; Goodwin, Michael; Lawrence, Jon

    2018-03-01

    Shack-Hartmannwavefront sensors using wound fibre image bundles are desired for multi-object adaptive optical systems to provide large multiplex positioned by Starbugs. The use of a large-sized wound fibre image bundle provides the flexibility to use more sub-apertures wavefront sensor for ELTs. These compact wavefront sensors take advantage of large focal surfaces such as the Giant Magellan Telescope. The focus of this paper is to study the wound fibre image bundle structure defects effect on the centroid measurement accuracy of a Shack-Hartmann wavefront sensor. We use the first moment centroid method to estimate the centroid of a focused Gaussian beam sampled by a simulated bundle. Spot estimation accuracy with wound fibre image bundle and its structure impact on wavefront measurement accuracy statistics are addressed. Our results show that when the measurement signal-to-noise ratio is high, the centroid measurement accuracy is dominated by the wound fibre image bundle structure, e.g. tile angle and gap spacing. For the measurement with low signal-to-noise ratio, its accuracy is influenced by the read noise of the detector instead of the wound fibre image bundle structure defects. We demonstrate this both with simulation and experimentally. We provide a statistical model of the centroid and wavefront error of a wound fibre image bundle found through experiment.

  16. Unpacking ecosystem service bundles : Towards predictive mapping of synergies and trade-offs between ecosystem services

    NARCIS (Netherlands)

    Spake, Rebecca; Lasseur, Rémy; Crouzat, Emilie; Bullock, James M.; Lavorel, Sandra; Parks, Katherine E.; Schaafsma, Marije; Bennett, Elena M.; Maes, Joachim; Mulligan, Mark; Mouchet, Maud; Peterson, Garry D.; Schulp, Catharina J.E.; Thuiller, Wilfried; Turner, Monica G.; Verburg, Peter H.; Eigenbrod, Felix

    2017-01-01

    Multiple ecosystem services (ES) can respond similarly to social and ecological factors to form bundles. Identifying key social-ecological variables and understanding how they co-vary to produce these consistent sets of ES may ultimately allow the prediction and modelling of ES bundles, and thus,

  17. Lexical bundles in an advanced INTOCSU writing class and engineering texts: A functional analysis

    Science.gov (United States)

    Alquraishi, Mohammed Abdulrahman

    The purpose of this study is to investigate the functions of lexical bundles in two corpora: a corpus of engineering academic texts and a corpus of IEP advanced writing class texts. This study is concerned with the nature of formulaic language in Pathway IEPs and engineering texts, and whether those types of texts show similar or distinctive formulaic functions. Moreover, the study looked into lexical bundles found in an engineering 1.26 million-word corpus and an ESL 65000-word corpus using a concordancing program. The study then analyzed the functions of those lexical bundles and compared them statistically using chi-square tests. Additionally, the results of this investigation showed 236 unique frequent lexical bundles in the engineering corpus and 37 bundles in the pathway corpus. Also, the study identified several differences between the density and functions of lexical bundles in the two corpora. These differences were evident in the distribution of functions of lexical bundles and the minimal overlap of lexical bundles found in the two corpora. The results of this study call for more attention to formulaic language at ESP and EAP programs.

  18. Unwrapping the Bundle: An Examination of Research Libraries and the "Big Deal"

    Science.gov (United States)

    Strieb, Karla L.; Blixrud, Julia C.

    2014-01-01

    This study presents and analyzes the findings of a 2012 survey of member libraries belonging to the Association of Research Libraries (ARL) about publishers' large journal bundles and compares the results to earlier surveys. The data illuminate five research questions: market penetration, journal bundle construction, collection format shifts,…

  19. The determinant bundle on the moduli space of stable triples over a ...

    Indian Academy of Sciences (India)

    The curvature of the Chern connection of this holomorphic Hermitian line bundle is computed. The curvature is shown to coincide with a constant scalar multiple of the natural Kähler form on the moduli space. The construction is based on a result of Quillen on the determinant line bundle over the space of Dolbeault ...

  20. Vector bundles with a fixed determinant on an irreducible nodal curve

    Indian Academy of Sciences (India)

    sheaves with a fixed determinant in the moduli space of torsion-free sheaves on Y. The relation to Seshadri–Nagaraj conjecture is studied. Keywords. Nodal curves; torsion-free sheaves; fixed determinant. 1. Introduction. Generalized parabolic vector bundles (GPBs) on a smooth curve X are vector bundles on. X together ...