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Sample records for atf damping ring

  1. Status of the ATF Damping Ring BPM Upgrade Project

    SciTech Connect

    Briegel, C.; Eddy, N.; Haynes, B.; May, J.; McCormick, D.; Nelson, J.; Nicklaus, D.; Prieto, P.; Rechenmacher, R.; Smith, T.; Teranuma, N.; Urakawa, J.; Voy, D.; Wendt, M.; Woodley, M.; /SLAC

    2011-12-01

    A substantial upgrade of the beam position monitors (BPM) at the ATF (Accelerator Test Facility) damping ring is currently in progress. Implementing digital read-out signal processing techniques in line with an optimized, low-noise analog downconverter, a resolution well below 1 mum could be demonstrated at 20 (of 96) upgraded BPM stations. The narrowband, high resolution BPM mode permits investigation of all types of non-linearities, imperfections and other obstacles in the machine which may limit the very low target aimed vertical beam emittance of < 2 pm. The technical status of the project, first beam measurements and an outlook to it's finalization are presented.

  2. High resolution upgrade of the ATF damping ring BPM system

    SciTech Connect

    Terunuma, N.; Urakawa, J.; Frisch, J.; May, J.; McCormick, D.; Nelson, J.; Seryi, A.; Smith, T.; Woodley, M.; Briegel, C.; Dysert, R.; /Fermilab

    2008-05-01

    A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished in its first stage, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and digital downconversion techniques, digital signal processing, and also tests a new automatic gain error correction schema. The technical concept and realization, as well as preliminary results of beam studies are presented.

  3. Bunch Length Measurements at the ATF Damping Ring in April 2000

    SciTech Connect

    Bane, K.L.F.; Naito, T.; Okugi, T.; Urakawa, J.; /KEK, Tsukuba

    2005-12-19

    We want to accurately know the energy spread and bunch length dependence on current in the ATF damping ring. One reason is to know the strength of the impedance: From the energy spread measurements we know whether or not we are above the threshold to the microwave instability, and from the energy spread and bunch length measurements we find out the extent of potential-well bunch lengthening (PWBL). Another reason for these measurements is to help in our understanding of the intra-beam scattering (IBS) effect in the ATF. The ATF as it is now, running below design energy and with the wigglers turned off, is strongly affected by IBS. To check for consistency with IBS theory of, for example, the measured vertical beam size, we need to know all dimensions of the beam, including the longitudinal one. But beyond this practical reason for studying IBS, IBS is currently a hot research topic at many accelerators around the world (see e.g. Ref. [1]), and the effect in actual machines is not well understood. Typically, when comparing theory with measurements fudge factors are needed to get agreement (see e.g. Ref. [1]). With its strong IBS effect, the ATF is an ideal machine for studying IBS, and an indispensable ingredient for this study is a knowledge of the longitudinal phase space of the beam. The results of earlier bunch lengthening measurements in the ATF can be found in Refs. [2]-[4]. Measurements of current dependent effects, especially bunch length measurements using a streak camera, can be difficult to perform accurately. For example, space charge in the camera itself can lead to systematic errors in the measurement results. It is important the results be accurate and reproducible. In the measurements of both December 1998[3] and December 1999[4], by using light filters, the authors first checked that space charge in the streak camera was not significant. And then the Dec 99 authors show that their results agree with those Dec 98, i.e. on the dates of the two

  4. Exotic damping ring lattices

    SciTech Connect

    Palmer, R.B.

    1987-05-01

    This paper looks at, and compares three types of damping ring lattices: conventional, wiggler lattice with finite ..cap alpha.., wiggler lattice with ..cap alpha.. = 0, and observes the attainable equilibrium emittances for the three cases assuming a constraint on the attainable longitudinal impedance of 0.2 ohms. The emittance obtained are roughly in the ratio 4:2:1 for these cases.

  5. Intrabeam Scattering in the NLC Main Damping Rings

    SciTech Connect

    Wolski, Andrzej

    2006-06-08

    We use Bane's approximation to the Bjorken-Mtingwa theory of intrabeam scattering to calculate the emittance growth as a function of bunch charge in the KEK ATF. We find that our results are consistent with the experimental data. We then calculate the emittance growth in the NLC Main Damping Rings using the same formulae; we allow for some uncertainty in the ATF data by using two different values for the Coulomb log factor in the formulae for the emittance growth rates. We find that despite the IBS emittance growth, it should still be possible to achieve the specified transverse and longitudinal emittances in the NLC Main Damping Rings at the specified bunch charge.

  6. Damping ring designs and issues

    SciTech Connect

    Wolski, Andrzej; Decking, Winfried

    2003-05-12

    The luminosity performance of a future linear collider (LC) will depend critically on the performance of the damping rings. The design luminosities of the current LC proposals require rings with very short damping times, large acceptance, low equilibrium emittance and high beam intensity. We discuss the design strategies for lattices achieving the goals of dynamical stability, examine the challenges for alignment and coupling correction, and consider a variety of collective effects that threaten to limit beam quality. We put the design goals in context by referring to the experience of operating facilities, and outline the further research and development that is needed.

  7. Study for ILC Damping Ring at KEKB

    SciTech Connect

    Flanagan, J.W.; Fukuma, H.; Kanazawa, K.I.; Koiso, H.; Masuzawa, M.; Ohmi, Kazuhito; Ohnishi, Y.; Oide, Katsunobu; Suetsugu, Y.; Tobiyama, M.; Pivi, M.; /SLAC

    2011-11-04

    ILC damping ring consists of very low emittance electron and positron storage rings. It is necessary for ILC damping ring to study electron cloud effects in such low emittance positron ring. We propose a low emittance operation of KEKB to study the effects.

  8. ATF2 Commissioning

    SciTech Connect

    Seryi, A.; Christian, G.; Parker, B.; Schulte, D.; Delahaye, J.-P.; Tomas, R.; Zimmermann, F.; Wolski, A.; Elsen, E.; Sanuki, T.; Gianfelice-Wendt, E.; Ross, M.; Wendt, M.; Takahashi, T.; Bai, S.; Gao, J.; Bolzon, B.; Geffroy, N.; Jeremie, A.; Apsimon, R.; Burrows, P.; /Oxford U., JAI /Kyoto U., Inst. Chem. Res. /Kyungpook Natl. U. /Orsay, LAL /Phang Accelerator Lab /Royal Holloway, U. of London /SLAC /Daresbury /University Coll. London /Manchester U. /Univ. of Tokyo U.

    2009-10-30

    ATF2 is a final-focus test beam line that aims to focus the low-emittance beam from the ATF damping ring to a beam size of about 37 nm, and at the same time to demonstrate nm beam stability, using numerous advanced beam diagnostics and feedback tools. The construction has been finished at the end of 2008 and the beam commissioning of ATF2 has started in December of 2008. ATF2 is constructed and commissioned by ATF international collaborations with strong US, Asian and European participation.

  9. Beam dynamic issues in TESLA damping ring

    SciTech Connect

    Shiltsev, V.

    1996-05-01

    In this paper we study general requirements on impedances of the linear collider TESLA damping ring design. Quantitative consideration is performed for 17-km long ``dog-bone`` ring. Beam dynamics in alternative options of 6.3 and 2.3-km long damping rings is briefly discussed. 5 refs., 2 tabs.

  10. SLC positron damping ring optics design

    SciTech Connect

    Delahaye, J.P.; Rivkin, L.

    1984-12-01

    The basic SLAC Linear Collider operation scheme assumes the use of two damping rings, one for the e/sup -/, one for the e/sup +/, in order to reduce the colliding beam normalized emittances to 30..pi.. ..mu..radm hence raising the corresponding luminosity by a factor 170. The e/sup -/ damping ring which optics was designed by H. Wiedemann, has been extensively studied and modelled since it's completion at the end of 1982. The e/sup +/ damping ring to be built soon will be based on the same design except for some modifications resulting from the studies on the e/sup -/ damping ring which clearly pointed out two major optics weak points: the extracted normalized emittances are 30 to 60% bigger than the design values, which already left no margin for unavoidable blow-up between the damping rings and the SLC interaction point, and the chromaticity correction based on distributed sextupole components provided by shaping the ends of the bending magnet poles was insufficient. Moreover the QDI quadrupoles introduce a strong coupling between transverse planes due to an undesirable skew component. The present note describes the basic modifications of the ring lattice and main equipment positions in order to improve the first two points in the Positron Damping Ring. The QDI quadrupole design has already been modified and magnets of a new type will be implemented in both damping rings.

  11. Electron beam depolarization in a damping ring

    SciTech Connect

    Minty, M.

    1993-04-01

    Depolarization of a polarized electron beam injected into a damping ring is analyzed by extending calculations conventionally applied to proton synchrotrons. Synchrotron radiation in an electron ring gives rise to both polarizing and depolarizing effects. In a damping ring, the beam is stored for a time much less than the time for self polarization. Spin flip radiation may therefore be neglected. Synchrotron radiation without spin flips, however, must be considered as the resonance strength depends on the vertical betatron oscillation amplitude which changes as the electron beam is radiation damped. An expression for the beam polarization at extraction is derived which takes into account radiation damping. The results are applied to the electron ring at the Stanford Linear Collider and are compared with numerical matrix formalisms.

  12. Status of the SLC damping rings

    SciTech Connect

    Hutton, A.M.; Davies-White, W.A.; Delahaye, J.P.; Fieguth, T.H.; Hofmann, A.; Jager, J.; Kloeppel, P.K.; Lee, M.J.; Linebarger, W.A.; Rivkin, L.

    1985-06-01

    Electron beams of full design energy 1.21 GeV and nearly full design intensity 4 x 10/sup 10/ particles/pulse (design 5 x 10/sup 10/) have been extracted from the Stanford Linac and successfully stored in the electron damping ring. Beams of less intensity have been extracted from the ring and reinjected into the Linac. The present intensity limits are not thought to be fundamental. The operating experience with the electron ring and the status of the construction of the positron ring will be discussed. 11 refs., 1 fig., 2 tabs.

  13. Harmonic cavities for the NLC damping rings

    SciTech Connect

    de Santis, S.; Wolski, A.

    2003-05-29

    To achieve high luminosity, a linear collider needs damping rings to produce beams with very small transverse emittances. In the NLC, design constraints place the Main Damping Rings in a parameter regime where intrabeam scattering (IBS) is likely to be a limitation on the emittance, and hence on the final luminosity. It is possible to mitigate the effects of IBS by lengthening the bunch: this may be achieved by redesigning the lattice with higher momentum compaction, or by use of higher harmonic cavities. Here, we consider the latter approach. We estimate the required bunch lengthening that might be needed, outline some appropriate parameters for the harmonic cavities, and discuss some of the effects that might be introduced or exacerbated by the cavities, such as synchronous phase variation along the bunch train.

  14. Comparison of Alignment Tolerances in the Linear Collider Damping with Those in Operating Rings(LCC-0112)

    SciTech Connect

    Raubenheimer, T

    2004-01-05

    The next generation linear colliders require damping rings to generate beam with very small transverse emittances to attain the desired luminosity. The required emittances are smaller than that of most operating synchrotron radiation sources. In this paper, the alignment tolerances needed to attain these small emittances are compared with those of the operating synchrotron radiation facilities and a prototype damping ring, the ATF at KEK. The concept of this study originated at the Nanobeams Workshop during a discussion in the Storage Rings Working Group although the results were not discussed at that meeting.

  15. Intrabeam Scattering Studies for the ILC Damping Rings Using a NewMATLAB Code

    SciTech Connect

    Reichel, I.; Wolski, A.

    2006-06-21

    A new code to calculate the effects of intrabeam scattering (IBS) has been developed in MATLAB based on the approximation suggested by K. Bane. It interfaces with the Accelerator Toolbox but can also read in lattice functions from other codes. The code has been benchmarked against results from other codes for the ATF that use this approximation or do the calculation in a different way. The new code has been used to calculate the emittance growth due to intrabeam scattering for the lattices currently proposed for the ILC Damping Rings, as IBS is a concern, especially for the electron ring. A description of the code and its user interface, as well as results for the Damping Rings, will be presented.

  16. Analytical estimation of ATF beam halo distribution

    NASA Astrophysics Data System (ADS)

    Wang, Dou; Philip, Bambade; Kaoru, Yokoya; Gao, Jie

    2014-12-01

    In order to study the backgrounds in the ATF2 beam line and the interaction point (IP), this paper has developed an analytical method to give an estimation of the ATF beam halo distribution based on K. Hirata and K. Yokoya's theory. The equilibrium particle distribution of the beam tail in the ATF damping ring is presented, with each electron affected by several stochastic processes such as beam-gas scattering, beam-gas bremsstrahlung and intra-beam scattering, in addition to the synchrotron radiation damping effects. This is a general method which can also be applied to other electron rings.

  17. Accelerator physics measurements at the damping ring

    SciTech Connect

    Rivkin, L.; Delahaye, J.P.; Wille, K.; Allen, M.; Bane, K.; Fieguth, T.; Hofmann, A.; Hutton, A.; Lee, M.; Linebarger, W.

    1985-05-01

    Besides the optics measurements described elsewhere, machine experiments were done at the SLC damping ring to determine some of its parameters. The synchrotron radiation energy loss which gives the damping rates was measured by observing the rf-voltage dependence of the synchronous phase angle. The emittance was obtained from the synchrotron light monitor, scraper measurements and by extracting the beam through a doublet and measuring its size for different quadrupole settings. Current dependent effects such as parasitic mode losses, head tail instabilities, synchrotron and betatron frequency shifts were measured to estimate the impedance. Rf-cavity beam loading and its compensation were also studied and ion collection was investigated. All results agree reasonably well with expectations and indicate no limitations to the design performance.

  18. Flexible ring baffles for damping liquid slosh

    NASA Technical Reports Server (NTRS)

    Brooks, G. W.; Stephens, D. G.

    1968-01-01

    Slosh damping, obtained through the use of small, less massive, flexible baffles, provides a relatively lightweight system for damping the motions of liquid propellants in launch vehicles, missiles, and other tankage systems.

  19. Effects of damping wigglers on beam dynamics in the NLC damping rings

    SciTech Connect

    Wolski, Andrzej; Wu, Ying

    2001-06-16

    To achieve the required damping time in the main damping rings for the Next Linear Collider (NLC), a wiggler will be required in each ring with integrated squared field strength up to 110 T{sup 2}m. There are concerns that nonlinear components of the wiggler field will damage the dynamic aperture of the ring, leading to poor injection efficiency. Severe effects from an insertion device have been observed and corrected in SPEAR 2. In this paper, we describe a model that we have developed to study the effects of the damping wiggler, compare the predictions of the model with actual experience in the case of the SPEAR 2 wiggler, and consider the predicted effects of current damping wiggler design on the NLC main damping rings.

  20. Damping Ring R&D at CESR-TA

    SciTech Connect

    Rubin, David L.

    2015-01-23

    Accelerators that collide high energy beams of matter and anti-matter are essential tools for the investigation of the fundamental constituents of matter, and the search for new forms of matter and energy. A “Linear Collider” is a machine that would bring high energy and very compact bunches of electrons and positrons (anti-electrons) into head-on collision. Such a machine would produce (among many other things) the newly discovered Higgs particle, enabling a detailed study of its properties. Among the most critical and challenging components of a linear collider are the damping rings that produce the very compact and intense beams of electrons and positrons that are to be accelerated into collision. Hot dilute particle beams are injected into the damping rings, where they are compressed and cooled. The size of the positron beam must be reduced more than a thousand fold in the damping ring, and this compression must be accomplished in a fraction of a second. The cold compact beams are then extracted from the damping ring and accelerated into collision at high energy. The proposed International Linear Collider (ILC), would require damping rings that routinely produce such cold, compact and intense beams. The goal of the Cornell study was a credible design for the damping rings for the ILC. Among the technical challenges of the damping rings; the development of instrumentation that can measure the properties of the very small beams in a very narrow window of time, and mitigation of the forces that can destabilize the beams and prevent adequate cooling, or worse lead to beam loss. One of the most pernicious destabilizing forces is due to the formation of clouds of electrons in the beam pipe. The electron cloud effect is a phenomenon in particle accelerators in which a high density of low energy electrons, build up inside the vacuum chamber. At the outset of the study, it was anticipated that electron cloud effects would limit the intensity of the positron ring

  1. Recommendation for the Feasibility of more Compact LC Damping Rings

    SciTech Connect

    Pivi, M.T.F.; Wang, L.; Demma, T.; Guiducci, S.; Suetsugu, Y.; Shibata, K.; Ohmi, K.; Dugan, G.; Palmer, M.; Crittenden, J.A.; Harkay, K.; Boon, L.; Furman, M.A.; Venturini, M.; Celata, C.; Malyshev, O.B.; Papaphilippou, I.; /CERN

    2010-06-15

    As part of the international Linear Collider (ILC) collaboration, we have compared the electron cloud (EC) effect for different Damping Ring (DR) designs respectively with 6.4 km and 3.2 km circumference and investigated the feasibility of the shorter damping ring with respect to the electron cloud build-up and related beam instabilities. The studies for a 3.2 km ring were carried out with beam parameters of the ILC Low Power option. A reduced damping ring circumference has been proposed for the new ILC baseline design SB2009 [1] and would allow considerable reduction of the number of components, wiggler magnets and costs. We discuss the impact of the proposed operation of the ILC at high repetition rate 10 Hz and address the necessary modifications for the DRs. We also briefly discuss the plans for future studies including the luminosity upgrade option with shorter bunch spacing, the evaluation of mitigation techniques and the integration of the CesrTA results into the Damping Ring design.

  2. Recommendation for the Feasibility of more Compact LC Damping Rings

    SciTech Connect

    Pivi, M. T. F.; Wang, L.; Demma, T.; Guiducci, S.; Suetsugu, Y.; Fukuma, H.; Shibata, K.; Dugan, K.,G.; Palmer, M.; Crittenden, J.; Harkay, K.; Boon, L.; Furman, M. A.; Venturini, M.; Celata, C.; Malyshev, O.; Papaphilippou, I.

    2010-05-23

    As part of the international Linear Collider (ILC) collaboration, we have compared the electron cloud (EC) effect for different Damping Ring (DR) designs respectively with 6.4 km and 3.2 km circumference and investigated the feasibility of a shorter damping ring with respect to the electron cloud build-up and related beam instability. The studies for a 3.2 km ring were carried out with beam parameters of the ILC Low Power option. A reduced damping ring circumference has been proposed for the new ILC baseline design SB2009 [1] and would allow to considerably reduce the number of components, wiggler magnets and costs. We discuss the impact of the proposed operation of the ILC at high repetition rate 10 Hz and address the necessary modifications for the DRs. We also briefly discuss the plans for future studies including the luminosity upgrade option with shorter bunch spacing, the evaluation of mitigations and the integration of the CesrTA results into the Damping Ring design.

  3. Damping of Resonantly Forced Density Waves in Dense Planetary Rings

    NASA Astrophysics Data System (ADS)

    Lehmann, Marius; Schmidt, Jürgen; Salo, Heikki

    2016-10-01

    We address the stability of resonantly forced density waves in dense planetary rings.Already by Goldreich and Tremaine (1978) it has been argued that density waves might be unstable, depending on the relationship between the ring's viscosity and the surface mass density. In the recent paper (Schmidt et al. 2016) we have pointed out that when - within a fluid description of the ring dynamics - the criterion for viscous overstability is satisfied, forced spiral density waves become unstable as well. In this case, linear theory fails to describe the damping.We apply the multiple scale formalism to derive a weakly nonlinear damping relation from a hydrodynamical model.This relation describes the resonant excitation and nonlinear viscous damping of spiral density waves in a vertically integrated fluid disk with density dependent transport coefficients. The model consistently predicts linear instability of density waves in a ring region where the conditions for viscous overstability are met. In this case, sufficiently far away from the Lindblad resonance, the surface mass density perturbation is predicted to saturate to a constant value due to nonlinear viscous damping. In general the model wave damping lengths depend on a set of input parameters, such as the distance to the threshold for viscous overstability and the ground state surface mass density.Our new model compares reasonably well with the streamline model for nonlinear density waves of Borderies et al. 1986.Deviations become substantial in the highly nonlinear regime, corresponding to strong satellite forcing.Nevertheless, we generally observe good or at least qualitative agreement between the wave amplitude profiles of both models. The streamline approach is superior at matching the total wave profile of waves observed in Saturn's rings, while our new damping relation is a comparably handy tool to gain insight in the evolution of the wave amplitude with distance from resonance, and the different regimes of

  4. Analytic estimates of coupling in damping rings

    SciTech Connect

    Raubenheimer, T.O.; Ruth, R.D.

    1989-03-01

    In this paper we present analytic formulas to estimate the vertical emittance in weakly coupled electron/positron storage rings. We consider contributions from both the vertical dispersion and linear coupling of the betatron motions. In addition to simple expressions for random misalignments and rotations of the magnets, formulas are presented to calculate the vertical emittance blowup due to orbit distortions. The orbit distortions are assumed to be caused by random misalignments, but because the closed orbit is correlated from point to point, the effects must be treated differently. We consider only corrected orbits. Finally, the analytic expressions are compared with computer simulations of storage rings with random misalignments. 6 refs., 3 figs.

  5. Injection and Extraction Lines for the ILC Damping Rings

    SciTech Connect

    Reichel, Ina

    2007-06-20

    The current design for the injection and extraction linesintoand out of the ILC Damping Rings is presented as well as the designfor the abort line. Due to changes of the geometric boundary conditionsby other subsystems of the ILC, a modular approach has been used to beable to respond to recurring layout changes whilereusing previouslydesigned parts.

  6. Frequency-Dependent Material Damping Using Augmenting Thermodynamic Fields (ATF) with Fractional Time Derivatives

    DTIC Science & Technology

    1990-09-01

    field, z - (q + r)7T/2 a,, a2 - material parameter, relation of affinity to the augmenting thermodynamic field a 3 - coupling between two ATFs 0T...frequency range, coupled material constitutive ix relations are developed using the concept of augmenting thermodynamic fields, with non-integer...material, for which the relation of stress to strain is defined by Hooke’s law a = EE , where E is called the modulus of elasticity. For this

  7. Evaluation of flexible ring baffles for damping liquid oscillations

    NASA Technical Reports Server (NTRS)

    Bugg, F.

    1973-01-01

    An experimental study was undertaken of damping produced by single flexible-ring baffles in a 396-cm diameter tank of liquid nitrogen. Two 24.8-cm wide baffles were tested. One baffle was 0.00635 cm thick type 301 stainless steel and the other 0.0254 cm thick Teflon FEP. Each baffle produced damping of liquid oscillations equal to or greater than that expected from rigid baffles of the same size. The equations used to determine the baffle thickness required were found to be adequate baffle design equations.

  8. Dynamic aperture study for the NLC main damping rings

    SciTech Connect

    Wolski, Andrzej; Venturini, Marco; Marks, Steve

    2004-07-05

    A sufficiently large acceptance is critical for the NLC Main Damping Rings (MDR) as the high power carried by the beams demands very high injection efficiency. Chromatic sextupoles and wiggler insertions (needed for rapid damping) are substantial sources of nonlinearities limiting the dynamic aperture. We report on the techniques we are using for analysis of single-particle beam dynamics in the presence of wiggler fields with significant nonlinear components. We demonstrate that our approach gives results in good agreement with experimental data when applied to the BL11 wiggler in SPEAR2, and discuss the present status of studies for the NLC MDR.

  9. Status of the SLC damping ring kicker systems

    SciTech Connect

    Mattison, T.; Cassel, R.; Donaldson, A.; Gough, D.; Gross, G.; Harvey, A.; Hutchinson, D.; Nguyen, M.

    1991-05-01

    The damping ring kickers for the SLAC Linear Collider must meet extreme requirements on rise and fall time, flatness, time and amplitude jitter and drift, voltage, repetition rate, and reliability. After several generations of improvements to the pulsers, magnets, and controls, and evolution in the understanding of the requirements, the kicker systems are no longer a serious constraint on SLC performance. Implications for future linear colliders are discussed. 14 refs.

  10. Optomechanical damping of a nanomembrane inside an optical ring cavity

    NASA Astrophysics Data System (ADS)

    Yilmaz, Arzu; Schuster, Simon; Wolf, Philip; Schmidt, Dag; Eisele, Max; Zimmermann, Claus; Slama, Sebastian

    2017-01-01

    We experimentally and theoretically investigate mechanical nanooscillators coupled to the light in an optical ring resonator made of dielectric mirrors. We identify an optomechanical damping mechanism that is fundamentally different to the well known cooling in standing wave cavities. While in a standing wave cavity the mechanical oscillation shifts the resonance frequency of the cavity, in a ring resonator the frequency does not change. Instead the position of the nodes is shifted with the mechanical excursion. We derive the damping rates and test the results experimentally with a silicon-nitride nanomembrane. It turns out that scattering from small imperfections of the dielectric mirror coatings has to be taken into account to explain the value of the measured damping rate. We extend our theoretical model and consider a second reflector in the cavity that captures the effects of mirror back scattering. This model can be used to also describe the situation of two membranes that both interact with the cavity fields. This may be interesting for future work on synchronization of distant oscillators that are coupled by intracavity light fields.

  11. Configuration Studies and Recommendations for the ILC DampingRings

    SciTech Connect

    Wolski, Andrzej; Gao, Jie; Guiducci, Susanna

    2006-02-04

    We describe the results of studies comparing different options for the baseline configuration of the ILC damping rings. The principal configuration decisions apply to the circumference, beam energy, lattice type, and technology options for key components, including the injection/extraction kickers and the damping wigglers. To arrive at our recommended configuration, we performed detailed studies of a range of lattices representing a variety of different configuration options; these lattices are described in Chapter 2. The results of the various studies are reported in chapters covering issues of beam dynamics, technical subsystems, costs, and commissioning, reliability and upgrade ability. Our detailed recommendations for the baseline configuration are given in Chapter 7, where we also outline further research and development that is needed before a machine using our recommended configuration can be built and operated successfully. In the same chapter, we suggest possible alternatives to the baseline configuration.

  12. Configuration Studies and Recommendations for the ILC DampingRings

    SciTech Connect

    Wolski, Andrzej; Gao, Jie; Guiducci, Susanna

    2006-02-04

    We describe the results of studies comparing differentoptions for the baseline configuration of the ILC damping rings. Theprincipal configuration decisions apply to the circumference, beamenergy, lattice type, and technology options for key components,including the injection/extraction kickers and the damping wigglers. Toarrive at our recommended configuration, we performed detailed studies ofa range of lattices representing a variety of different configurationoptions; these lattices are described in Chapter 2. The results of thevarious studies are reported in chapters covering issues of beamdynamics, technical subsystems, costs, and commissioning, reliability andupgradeability. Our detailed recommendations for the baselineconfiguration are given in Chapter 7, where we also outline furtherresearch and development that is needed before a machine using ourrecommended configuration can be built and operated successfully. In thesame chapter, we suggest possible alternatives to the baselineconfiguration.

  13. Instantaneous Frequency and Damping from Transient Ring-Down Data

    SciTech Connect

    Kuether, Robert J.; Brake, Matthew Robert

    2015-10-01

    Broadband impact excitation in structural dynamics is a common technique used to detect and characterize nonlinearities in mechanical systems since it excites many frequencies of a structure at once and can be applied with a variety of boundary conditions. Non-stationary time signals from transient ring-down measurements require time-frequency analysis tools to observe variations in frequency and energy dissipation as the response evolves. This work uses the short-time Fourier transform to estimate the instantaneous frequency and damping ratio from either measured or simulated transient ring-down data. By combining the discrete Fourier transform with an expanding or contracting window function that moves along the time axis, the resulting spectrum is used to estimate the instantaneous frequencies, damping and complex Fourier coefficients. This method is demonstrated on a multi-degree-of-freedom beam with a cubic spring attachment, and investigates the amplitudefrequency dependence in connection to the undamped nonlinear normal modes. A second example shows the results from experiment ring-down response on a beam with a lap joint, and reveals how the system behaves as energy dissipates.

  14. Impedance and instabilities in the NLC damping rings

    SciTech Connect

    Corlett,J.; Li, D.; Pivi, M.; Rimmer, R.; DeSantis, S.; Wolski, A.; Novokhatski,A.; Ng, C.

    2001-06-12

    We report on impedance calculations and single-bunch and multi-bunch instabilities in the NLC damping rings. Preliminary designs of vacuum chambers and major components have addressed beam impedance issues, with the desire to increase instability current thresholds and reducing growth rates. MAFIA calculations of short-range and long-range wakefields have allowed computations of growth rates and thresholds, which are presented here. Resistive wall instability dominates long-range effects, and requires a broadband feedback system to control coupled-bunch motion. Growth rates are within the range addressable by current feedback system technologies. Single-bunch instability thresholds are safely above nominal operating current.

  15. IMPEDANCE AND INSTABILITIES IN THE NLC DAMPING RINGS

    SciTech Connect

    Novokhatski, Alexander

    2002-08-20

    We report on impedance calculations and single-bunch and multi-bunch instabilities in the NLC damping rings. Preliminary designs of vacuum chambers and major components have addressed beam impedance issues, with the desire to increase instability current thresholds and reducing growth rates. MAFIA calculations of short-range and long-range wakefields have allowed computations of growth rates and thresholds, which are presented here. Resistive wall instability dominates long-range effects, and requires a broadband feedback system to control coupled-bunch motion. Growth rates are within the range addressable by current feedback system technologies. Single-bunch instability thresholds are safely above nominal operating current.

  16. The NLC Main Damping Ring Lattice(LCC-0113)

    SciTech Connect

    Woodley, M

    2003-10-02

    Studies of the NLC Main Damping Ring lattice since April 2001 have indicated that there are a number of collective effects that potentially limit operational performance. One possible way to reduce the impact of these effects is to raise the momentum compaction of the lattice, which requires a significant re-design. In this note, we present a lattice that has a momentum compaction four times larger than the previous design. We discuss the linear and nonlinear dynamical properties of the lattice, and present some initial estimates of the sensitivity of the new design to various magnet misalignments.

  17. Operational experience with SLC damping ring kicker magnets

    SciTech Connect

    Mattison, T.; Cassel, R.; Donaldson, A.; Gross, G.; Harvey, A.

    1991-05-01

    The damping ring kickers for the SLAC Linear Collider must provide 7 mrad kicks to 1.2 GeV beams with 60 nsec rise and fall times and fit in a 50 cm length around a 21 mm diameter ceramic beam pipe. This requires that they operate at up to 40 KV. The construction and operation of two types of quasi-coaxial ferrite magnet potted with RTV silicone rubber is discussed. Production yield has been improved by changes in RTV degassing, transfer, and cure. Operation lifetime is dominated by voltage, radiation, and thermal cycling. 4 refs., 2 figs.

  18. Stiffness and damping of elastomeric O-ring bearing mounts

    NASA Technical Reports Server (NTRS)

    Smalley, A. J.

    1977-01-01

    A test rig to measure the dynamic stiffness and damping of elastomer O rings was described. Test results for stiffness and loss coefficient in the frequency range from 50 Hz to 1000 Hz are presented. Results are given for three different materials, for five temperatures, for three amplitudes, for five values of squeeze for three values of stretch for three values of cross-section diameter and for three values of groove width. All test data points were plotted. In addition, trend summary plots were presented which compare the effect of material, temperature, amplitude, squeeze, stretch, cross-section diameter, and groove width. O ring deflections under a static load for different material were presented; and effective static stiffness values were compared with dynamic values.

  19. Damping Ring to Interaction Point Beam Transport Issues

    SciTech Connect

    Tenenbaum, Peter G

    2003-08-08

    One of the major challenges facing the proposed high-energy linear e{sup +}e{sup -} colliders is the preservation of the extremely small vertical emittance from the damping rings to the interaction point (IP). This emittance must be transported through bunch compression sections, the main linac and finally through the beam delivery system to the IP. Historically, the beam dynamics issues of each subsystem have been studied quasi-independently, with the beam conditions and tolerances being specified at the boundaries. As part of the recent International Linear Collider Technical Review Committee [1], new simulation tools have been developed to simulate the beam transport through the integrated system, including static and dynamic errors, stabilization systems, and tuning algorithms.

  20. ATF2 Summary and Status

    SciTech Connect

    Alabau-Gonzalvo, J.; Alabau Pons, M.; Amann, J.; Angal-Kalinin, D.; Apsimon, R.; Araki, S.; Aryshev, A.; Bai, S.; Bambade, P.; Bellomo, P.; Bett, D.; Blair, G.; Blanch, C.; Bolzon, B.; Boogert, S.; Boorman, G.; Burrows, P.; Christian, G.; Coe, P.; Constance, B.; Corner, L.; /Oxford U., JAI /Oxford U., JAI /CERN /Oxford U., JAI /DESY /Valencia U., IFIC /SLAC /KEK, Tsukuba /Beijing, Inst. High Energy Phys. /ESIA, Annecy /Fermilab /Ecole Polytechnique /KEK, Tsukuba /Kyungpook Natl. U. /KEK, Tsukuba /Pohang Accelerator Lab. /Pohang Accelerator Lab. /Kyoto U., Inst. Chem. Res. /ESIA, Annecy /Cockcroft Inst. Accel. Sci. Tech. /Tokyo U. /Oxford U., JAI /Kyungpook Natl. U. /Kyungpook Natl. U. /Pohang Accelerator Lab. /Kyungpook Natl. U. /Tokyo U. /KEK, Tsukuba /KEK, Tsukuba /KEK, Tsukuba /SLAC /University Coll. London /KEK, Tsukuba /SLAC /Oxford U., JAI /KEK, Tsukuba /Tokyo U. /SLAC /Oxford U., JAI /Tohoku U. /KEK, Tsukuba /Tokyo U. /Pohang Accelerator Lab. /Brookhaven /SLAC /Oxford U., JAI /SLAC /SLAC /CERN /Oxford U., JAI /Orsay, LAL /Fermilab /Tohoku U. /Manchester U. /CERN /Oxford U., JAI /SLAC /SLAC /SLAC /Tokyo U. /KEK, Tsukuba /Oxford U., JAI /Hiroshima U. /KEK, Tsukuba /KEK, Tsukuba /CERN /KEK, Tsukuba /Oxford U., JAI /Ecole Polytechnique /Oxford U., JAI /Beijing, Inst. High Energy Phys. /SLAC /Oxford U., JAI /Fermilab /SLAC /SLAC /Liverpool U. /SLAC /Tokyo U. /Tokyo U. /Tokyo U. /Tokyo U. /KEK, Tsukuba /SLAC /CERN

    2012-04-19

    The Accelerator Test Facility (ATF) [1] at KEK was originally constructed as a Damping Ring (DR) demonstration facility for the next generation of electron linear colliders. It consists of a 1.3 GeV s-band linac and a 136m circumference damping ring which can routinely generate 1.6 nC electron bunches with very small vertical emittances (<10pm.rad). Completed in December of 2008, a new extraction line and final focus optics was built, this is referred to as ATF2 [2]. The location of ATF in-relation to the KEK site can be seen in Figure 1. ATF is a general-purpose facility for accelerator physics related R and D activities, with approximately 50% of the available beam time currently devoted to the ATF2 program. The ATF2 extraction line (EXT) and final focus system (FFS) extends about 90 meters from the DR extraction point, a sketch of this system can be seen in figure 2, along with the location of key instrumentation. The primary purpose of the ATF2 beam line is to demonstrate a new style of magnetic focusing optics intended for use at future linear colliders, such as ILC or CLIC based on a local chromaticity correction scheme. The primary goal of the collaboration is to demonstrate the ability of this optics to focus an electron beam of similar emittance to the ILC using a FFS of the same design chromaticity. A comparison of some of the ATF2 design parameters with those of the ILC and CLIC are shown in table 1. With the 1.3 GeV beam energy of ATF2, the target spot size to prove the operability of this optics for ILC is 37nm. This is referred to as 'Goal 1'. In addition, Goal 1 requires the demonstration of stable operations with such a beam size at the Interaction Point (IP). 'Goal 2' is to demonstrate nm-level stability with respect to the IP beam monitors, such as is required for stable beam collisions at ILC or CLIC. A further goal is to attempt to increase the chromaticity of the final focus optics, reducing the IP beta functions to a level where the system

  1. Final Focus Test Facility ATF2 Status

    SciTech Connect

    Bambade, P.; Seryi, A.; Tauchi, T.; /KEK, Tsukuba

    2012-04-06

    ATF2 is a final-focus test beam line which aims to focus the low emittance beam from the ATF damping ring to a vertical size of about 37 nm and to demonstrate nanometre level beam stability. Several advanced beam diagnostics and feedback tools are used. In December 2008, construction and installation were completed and beam commissioning started, supported by an international team of Asian, European and American scientists. In this paper, the present status and performance of the recently deployed ATF2 systems are briefly described, based on the first experience with beam measurements and tuning during winter, spring and early autumn of 2009. The near and longer term plans are outlined as well. The ATF collaboration has completed the construction of ATF2 and has started its commissioning. Important experience operating the new cavity BPM and BSM instrumentation in real conditions has been gained and first beam measurements have been performed in a magnetic configuration with reduced optical demagnification. Both horizontal and vertical emittances were successfully tuned and measured in the extraction line, with values approaching the design values of 2 nm and 12 pm, respectively. First checks of the first order optics along the beam line and at the IP were also done. Hardware developments for the second ATF2 goal are being pursued in parallel with the present commissioning work for the first goal. The collaboration is also preparing several near and long terms plans for ATF2. In the next few years, information very valuable for any future collider with local chromaticity correction and tuning of very low emittance beams can be expected. In the previous experience at the FFTB, the smallest vertical beam sizes which were achieved were about 70 nanometers. The work described here continues to address this largely unexplored regime in a systematic way.

  2. Resistive-Wall Instability in the Damping Rings of the ILC

    SciTech Connect

    Wang, L.; Bane, K.L.F.; Raubenheimer, T.; Ross, M.; /SLAC

    2006-07-05

    In the damping rings of the International Linear Collider (ILC), the resistive-wall instability is one of the dominant transverse instabilities. This instability directly influences the choice of material and aperture of the vacuum pipe, and the parameters of the transverse feedback system. This paper investigates the resistive-wall instabilities in an ILC damping ring under various conditions of beam pipe material, aperture, and fill pattern.

  3. Ring baffle pressure distribution and slosh damping in large cylindrical tanks

    NASA Technical Reports Server (NTRS)

    Scholl, H. F.; Stephens, D. G.; Davis, P. K.

    1972-01-01

    An investigation was conducted to determine the pressure loads and damping associated with rigid ring baffles in relatively large cylindrical tanks. The radial and circumferential pressure distribution, as well as the damping, was measured on a ring baffle subjected to fundamental antisymmetric slosh in a 284-cm-diameter rigid tank. Experimental and analytical data are presented as a function of slosh velocity or amplitude, baffle spacing, and baffle locations both above and below the liquid surface. Results suggest that pressure distributions and damping values can be determined from available theories for the design of single and multiple baffle configurations.

  4. Frequency map analysis of nonlinear dynamics in the NLC main damping rings

    SciTech Connect

    Wolski, Andrzej; Venturini, Marco; Wan, Weishi; Marks, Steve

    2004-10-11

    To avoid radiation damage, the acceptance of linear collider damping rings must be large enough that injection efficiency close to 100 percent can be achieved. Survival plots based on tracking particles in the NLC Main Damping Ring lattice suggest a dynamic aperture with some margin over the specified injected beam size and energy spread. Here, we apply Frequency Map Analysis to give a more detailed picture of the dynamical stability of particle trajectories in the presence of lattice nonlinearities arising from the sextupoles and the damping wiggler. The techniques that we use are of general applicability to nonlinear elements in beamlines, and in particular will be used for analysis of wiggler effects in future damping ring designs.

  5. NLC Damping Ring Lattice Design Using TME Cells and Wigglers (LCC-0037)

    SciTech Connect

    Emma, P

    2004-03-23

    The design process is described for the damping rings of the Next Linear Collider (NLC) [1]. While the main (e{sup -}/e{sup +}) damping ring is the primary subject, some reference to the (e{sup +}) pre-damping ring is also included. An attempt is made to be systematic in the design, given the emittance and repetition rate requirements of the collider, in conjunction with the beam quality from the injector systems. In addition, qualitative efforts are made to minimize the cost and maximize the dynamic aperture. The approximate interdependencies of the various lattice parameters are derived and arguments for the parameter choices are presented. The rings are a race-track design with wiggler insertions and Theoretical Minimum Emittance (TME) cells. Collective effects and dynamic aperture calculations, while studied in previous designs [1], are not included here.

  6. Tracking Studies to Determine the Required Wiggler Aperture forthe ILC Damping Rings

    SciTech Connect

    Reichel, I.; Wolski, A.

    2006-06-21

    The injection efficiency of an ILC damping ring is closely tied to its acceptance. To maximize both, one wants a physical aperture as large as possible in the wiggler magnets, as these are likely to be the limiting physical apertures in the ring. On the other hand, a small aperture in the wiggler magnets is needed to achieve the required field profile, a high magnetic field that is very linear over the whole physical aperture of the magnet. Tracking studies were done for all proposed ILC damping ring lattices to determine their required physical apertures. Although a half-aperture of 8 or 10mm had been proposed, our studies showed that, for most lattices, a 16mm half-aperture is required. For some lattices a 12mm half aperture might suffice. We present here the results of our studies, which led to adopting a 16mm half-aperture in the current ILC damping ring baseline design.

  7. Bunch lengthening calculations for the SLC (Stanford Linear Collider) damping rings

    SciTech Connect

    Bane, K.L.F.; Ruth, R.D.

    1989-03-01

    The problem of bunch lengthening in electron storage rings has been treated by many people, and there have been many experiments. In the typical experiment, the theory is used to determine the impedance of the ring. What has been lacking thus far, however, is a calculation of bunch lengthening that uses a carefully calculated ring impedance (or wakefield). In this paper we begin by finding the potential well distortion due to some very simple impedance models, in order to illustrate different types of bunch lengthening behavior. We then give a prescription for extending potential well calculations into the turbulent regime once the threshold is known. Then finally, using the wakefield calculated for the SLC damping rings, combined with the measured value of the threshold, we calculate bunch lengthening for the damping rings, and compare the results with the measurements. 9 refs., 6 figs.

  8. Transverse Field Profile of the NLC Damping Rings Eletromagnet Wiggler (LCC-0038)

    SciTech Connect

    Ross, M

    2004-03-19

    The primary effort for damping ring wiggler studies has been to develop a credible radiation hard electromagnet wiggler conceptual design that meets NLC main electron and positron damping ring physics requirements [1]. Based upon an early assessment of requirements, a hybrid magnet similar to existing designs satisfies basic requirements. However, radiation damage is potentially a serious problem for the Nd-Fe-B permanent magnet material, and cost remains an issue for samarium cobalt magnets. Superconducting magnet designs have not been pursued due to their increased complexity and our unfamiliarity with the technology. Having produced and developed an electromagnet design, we now find that the transverse field roll-off is severe, and recognizing similar experience with beamline 11 at SSRL we believe that the resulting beam quality will not meet the damping ring requirements. We therefore propose, in parallel with more detailed optics studies of the wiggler field requirements, to revisit the hybrid permanent magnet design.

  9. A Weakly Nonlinear Model for the Damping of Resonantly Forced Density Waves in Dense Planetary Rings

    NASA Astrophysics Data System (ADS)

    Lehmann, Marius; Schmidt, Jürgen; Salo, Heikki

    2016-10-01

    In this paper, we address the stability of resonantly forced density waves in dense planetary rings. Goldreich & Tremaine have already argued that density waves might be unstable, depending on the relationship between the ring’s viscosity and the surface mass density. In the recent paper Schmidt et al., we have pointed out that when—within a fluid description of the ring dynamics—the criterion for viscous overstability is satisfied, forced spiral density waves become unstable as well. In this case, linear theory fails to describe the damping, but nonlinearity of the underlying equations guarantees a finite amplitude and eventually a damping of the wave. We apply the multiple scale formalism to derive a weakly nonlinear damping relation from a hydrodynamical model. This relation describes the resonant excitation and nonlinear viscous damping of spiral density waves in a vertically integrated fluid disk with density dependent transport coefficients. The model consistently predicts density waves to be (linearly) unstable in a ring region where the conditions for viscous overstability are met. Sufficiently far away from the Lindblad resonance, the surface mass density perturbation is predicted to saturate to a constant value due to nonlinear viscous damping. The wave’s damping lengths of the model depend on certain input parameters, such as the distance to the threshold for viscous overstability in parameter space and the ground state surface mass density.

  10. Installation and Measurement of the ATF Injection Kicker

    SciTech Connect

    Blum, Piotr

    2003-05-16

    An injection kicker system of the same type as SLC North Damping Ring (NDR, for e-injection) is used at ATF DR for future linear collider development in KEK. The magnet and the power supply have been constructed at SLAC and installed to the ATF DR at June 1996. The system has been operated from the beginning of commissioning, January 1997, to the present operation, July 1997, with single bunch injection mode. The construction and the operation has been done as a part of the collaboration program of the ATF project. The operation characteristics of the injection kicker were measured using beam. The system configuration and the result are described in this paper.

  11. Investigation into electron cloud effects in the International Linear Collider positron damping ring

    SciTech Connect

    Crittenden, J. A.; Conway, J.; Dugan, G. F.; Palmer, M. A.; Rubin, D. L.; Shanks, J.; Sonnad, K. G.; Boon, L.; Harkay, K.; Ishibashi, T.; Furman, M. A.; Guiducci, S.; Pivi, M. T. F.; Wang, L.

    2014-03-01

    We report modeling results for electron cloud buildup and instability in the International Linear Collider positron damping ring. Updated optics, wiggler magnets, and vacuum chamber designs have recently been developed for the 5 GeV, 3.2-km racetrack layout. An analysis of the synchrotron radiation profile around the ring has been performed, including the effects of diffuse and specular photon scattering on the interior surfaces of the vacuum chamber. The results provide input to the cloud buildup simulations for the various magnetic field regions of the ring. The modeled cloud densities thus obtained are used in the instability threshold calculations. We conclude that the mitigation techniques employed in this model will suffice to allow operation of the damping ring at the design operational specifications

  12. Measured Two-Dimensional Damping Effectiveness of Fuel-Sloshing Baffles applied to Ring Baffles in Cylindrical Tanks

    NASA Technical Reports Server (NTRS)

    Cole, Henry A., Jr.; Gambucci, Bruno J.

    1961-01-01

    Measured two-dimensional damping forces of baffles with various shapes and perforations are presented for fluid conditions representative of those in liquid-fuel rocket vehicles. The effect of amplitude and frequency of fuel sloshing, and surface proximity on baffle damping are shown. Application of the result sin the prediction of damping effectiveness of ring baffles in cylindrical tanks is demonstrated. Finally, some measurements of damping in a free-free cylindrical tank are presented which verify the predictions based on two-dimensional results. Measurements of certain three-dimensional baffles show that they provide greater damping than ring baffles.

  13. Longitudinal single-bunch instabilities in the NLC main damping rings

    SciTech Connect

    Venturini, Marco

    2004-05-10

    Because of tight requirements on beam quality longitudinal single-bunch instabilities are a serious concern for the damping rings of the next generation of linear colliders. Unlike multi-bunch instabilities they cannot be damped using feed-back systems and need to be avoided altogether. We present an analysis of these instabilities for the current Feb. 03 NLC main damping ring design, with attention paid to coherent synchrotron radiation and vacuum chamber effects, with the latter including the main components (RF cavities, BPM's, and resistive wall). The study is carried out by solving the Vlasov-Fokker-Planck equation for the longitudinal motion numerically. Comparison is made, whenever possible, with linear theory. We find that collective effects are dominated by coherent synchrotron radiation and estimate the instability threshold to be safely above 6 times the design current.

  14. Longitudinal Stability Study for the FACET-II e+ Damping Ring

    SciTech Connect

    Bane, Karl

    2016-11-29

    This is an initial study of the longitudinal, single-bunch stability in the proposed FACET-II e+ damping ring. It is preliminary because, at present, only a few specific features of the vacuum chamber are known.

  15. An ultimate storage ring lattice with vertical emittance generated by damping wigglers

    SciTech Connect

    Huang, Xiaobiao

    2015-01-06

    We discuss the approach of generating round beams for ultimate storage rings using vertical damping wigglers (with horizontal magnetic field). The vertical damping wigglers provide damping and excite vertical emittance. This eliminates the need to generate large linear coupling that is impractical with traditional off-axis injection. We use a PEP-X compatible lattice to demonstrate the approach. This lattice uses separate quadrupole and sextupole magnets with realistic gradient strengths. Intrabeam scattering effects are calculated. As a result, the horizontal and vertical emittances are 22.3 pm and 10.3 pm, respectively, for a 200 mA, 4.5 GeV beam, with a vertical damping wiggler of a total length of 90 m, a peak field of 1.5 T and a wiggler period of 100 mm.

  16. Direct space-charge effects on the ILC damping rings: Task ForceReport

    SciTech Connect

    Venturini, Marco; Oide, Katsunobu

    2006-02-28

    In 2005 a global effort was initiated to conduct studies for a baseline recommendation for the various components of the International Linear Collider (ILC). Work for the damping rings was subdivided in a number of tasks. This Report contains the contribution to this effort by the Authors as Coordinators of the Task Force on space charge. (A slightly reduced version of this document can also be found as part of the ''Configuration Studies and Recommendations for the ILC Damping Rings'', Edts. A. Wolski, et al., LBNL-59449.) The studies documented in this Report were carried out for several of the reference lattices considered for the baseline recommendation. Space charge effects were found to be quite noticeable in the lattices with the longest circumference. Although it does not appear that they could prevent operation of any machine having such lattices they do favor a choice of a ring design with shorter ({approx}6km) circumference at 5 GeV.

  17. Design and system integration of the superconducting wiggler magnets for the Compact Linear Collider damping rings

    NASA Astrophysics Data System (ADS)

    Schoerling, Daniel; Antoniou, Fanouria; Bernhard, Axel; Bragin, Alexey; Karppinen, Mikko; Maccaferri, Remo; Mezentsev, Nikolay; Papaphilippou, Yannis; Peiffer, Peter; Rossmanith, Robert; Rumolo, Giovanni; Russenschuck, Stephan; Vobly, Pavel; Zolotarev, Konstantin

    2012-04-01

    To achieve high luminosity at the collision point of the Compact Linear Collider (CLIC), the normalized horizontal and vertical emittances of the electron and positron beams must be reduced to 500 and 4 nm before the beams enter the 1.5 TeV linear accelerators. An effective way to accomplish ultralow emittances with only small effects on the electron polarization is using damping rings operating at 2.86 GeV equipped with superconducting wiggler magnets. This paper describes a technical design concept for the CLIC damping wigglers.

  18. Simulations of the Electron Cloud Builld Up and Instabilities for Various ILC Damping Ring Configurations

    SciTech Connect

    Pivi, Mauro; Raubenheimer, Tor O.; Wang, Lanfa; Ohmi, Kazuhito; Wanzenberg, Rainer; Wolski, Andrzej; /Liverpool U. /Cockcroft Inst. Accel. Sci. Tech.

    2007-03-12

    In the beam pipe of the positron damping ring of the International Linear Collider (ILC), an electron cloud may be first produced by photoelectrons and ionization of residual gases and then increased by the secondary emission process. This paper reports the assessment of electron cloud effects in a number of configuration options for the ILC baseline configuration. Careful estimates were made of the secondary electron yield (sometimes in the literature also referred as secondary emission yield SEY or {delta}, with a peak value {delta}{sub max}) threshold for electron cloud build-up, and the related single- and coupled-bunch instabilities, as a function of beam current and surface properties for a variety of optics designs. When the configuration for the ILC damping rings was chosen at the end of 2005, the results from these studies were important considerations. On the basis of the joint theoretical and experimental work, the baseline configuration currently specifies a pair of 6 km damping rings for the positron beam, to mitigate the effects of the electron cloud that could present difficulties in a single 6 km ring. However, since mitigation techniques are now estimated to be sufficiently mature, a reduced single 6-km circumference is presently under consideration so as to reduce costs.

  19. Active Damping of the E-P Instability at the Los Alamos Proton Storage Ring

    SciTech Connect

    Macek, R.J.; Assadi, S.; Byrd, J.M.; Deibele, C.E.; Henderson, S.D.; Lee, S.Y.; McCrady, R.C.; Pivi, M.F.T.; Plum, M.A.; Walbridge, S.B.; Zaugg, T.J.; /Los Alamos

    2008-03-17

    A prototype of an analog, transverse (vertical) feedback system for active damping of the two-stream (e-p) instability has been developed and successfully tested at the Los Alamos Proton Storage Ring (PSR). This system was able to improve the instability threshold by approximately 30% (as measured by the change in RF buncher voltage at instability threshold). The feedback system configuration, setup procedures, and optimization of performance are described. Results of several experimental tests of system performance are presented including observations of instability threshold improvement and grow-damp experiments, which yield estimates of instability growth and damping rates. A major effort was undertaken to identify and study several factors limiting system performance. Evidence obtained from these tests suggests that performance of the prototype was limited by higher instability growth rates arising from beam leakage into the gap at lower RF buncher voltage and the onset of instability in the horizontal plane, which had no feedback.

  20. Active damping of the e-p instability at the Los Alamos Proton Storage Ring

    SciTech Connect

    Macek, R. J.; Assadi, S.; Byrd, J. M.; Deibele, C. E.; Henderson, S. D.; Lee, S. Y.; McCrady, R. C.; Pivi, M. F. T.; Plum, M. A.; Walbridge, S. B.; Zaugg, T. J.

    2007-12-15

    A prototype of an analog, transverse (vertical) feedback system for active damping of the two-stream (e-p) instability has been developed and successfully tested at the Los Alamos Proton Storage Ring (PSR). This system was able to improve the instability threshold by approximately 30% (as measured by the change in RF buncher voltage at instability threshold). The feedback system configuration, setup procedures, and optimization of performance are described. Results of several experimental tests of system performance are presented including observations of instability threshold improvement and grow-damp experiments, which yield estimates of instability growth and damping rates. A major effort was undertaken to identify and study several factors limiting system performance. Evidence obtained from these tests suggests that performance of the prototype was limited by higher instability growth rates arising from beam leakage into the gap at lower RF buncher voltage and the onset of instability in the horizontal plane, which had no feedback.

  1. Control of damping partition numbers in a ring accelerator with rf electromagnetic fields.

    PubMed

    Shimosaki, Yoshito; Tanaka, Hitoshi

    2013-04-12

    A novel scheme to reduce transverse beam emittance in a ring accelerator is proposed by using a pair of coupling cavities as a basic unit to control damping partition numbers. As indicated by Robinson in 1958, a simple rf electromagnetic field (e.g., a TM210 mode by a single coupling cavity) cannot control the damping partition of three eigenoscillation modes in a ring accelerator due to the cancellation between the contributions from the magnetic and electric fields. Based on both analytical and numerical studies, we show that a pair of coupling cavities that satisfy phase and optics matching conditions can overcome this cancellation. The results indicate that the horizontal emittance is reducible to the theoretical limit based on the steady state condition and also, the emittance is reducible below the reduction limit under a nonsteady state by driving the coupling cavities with gated signals.

  2. Ion Effects in the Electron Damping Ring of the International Linear Collider

    SciTech Connect

    Wang, L.; Raubenheimer, T.; Wolski, A.; /Liverpool U.

    2006-07-17

    Ion-induced beam instabilities and tune shifts are critical issues for the electron damping ring of the International Linear Collider (ILC). To avoid conventional ion trapping, a long gap is introduced in the electron beam by omitting a number of successive bunches out of a long train. However, the beam can still suffer from the fast ion instability, driven by ions that last only for a single passage of the electron bunches. Our study shows that the ion effects can be significantly mitigated by using multiple gaps, so that the stored beam consists of a number of relatively short bunch trains. The ion effects in the ILC damping rings are investigated using both analytical and numerical methods.

  3. Landau damping effects and evolutions of energy spread in small isochronous ring

    SciTech Connect

    Li, Yingjie; Wang, Langfa; Lin, Fanglei

    2014-11-01

    This paper presents the Landau damping effects on the microwave instability of a coasting long bunch in an isochronous ring due to finite energy spread and emittance. Our two-dimensional (2D) dispersion relation gives more accurate predictions of the microwave instability growth rates of short-wavelength perturbations than the conventional 1D formula. The long-term evolution of energy spread is also studied by measurements and simulations.

  4. A modified post damping ring bunch compressor beamline for the TESLA linear collider

    SciTech Connect

    Philippe R.-G. Piot; Winfried Decking

    2004-03-23

    We propose a modified bunch compressor beamline, downstream of the damping ring, for the TESLA linear collider. This modified beamline uses a third harmonic radio-frequency section based on the 3.9 GHz superconducting cavity under development at Fermilab. In our design the beam deceleration is about {approx}50 MeV instead of {approx}450 MeV in the original design proposed.

  5. Wake field analysis and modelling of microwave instability in the ILC damping ring

    NASA Astrophysics Data System (ADS)

    Korostelev, M.; Wolski, A.; Thorley, A.

    2011-12-01

    Wake field simulations are performed for given technical designs of the vacuum chamber components for the 6.4 km ILC damping ring, in order to calculate longitudinal wake functions. Modelling of the microwave instability based on multi-turn tracking with many particles is described. A comparison is presented between the potential well distortion found from solving the Haissinski equation and the results of tracking simulations. The threshold for the microwave instability is found for the given designs and lattice parameters.

  6. Design and optimisation of the positron production chain for CLIC from the target to the damping ring

    NASA Astrophysics Data System (ADS)

    Bayar, C.; Ciftci, A. K.; Doebert, S.; Latina, A.

    2017-10-01

    The CLIC Positron source has been designed to produce non-polarised positron beams using a hybrid target composed of a crystal followed by an amorphous target. After production, positrons are captured and accelerated to 200 MeV in the pre-injector linac and subsequently accelerated further up to 2.86 GeV in the injector linac. At this point they enter the pre-damping ring and afterwards the main damping ring to obtain the necessary beam quality for a linear collider. In this study, we have designed and optimised the beam transport and acceleration from the target to the pre-damping ring which has a limiting transverse and longitudinal acceptance. The goal of the study was to maximise the positron yield accepted by the pre-damping ring.

  7. Extension of Miles Equation for Ring Baffle Damping Predictions to Small Slosh Amplitudes and Large Baffle Widths

    NASA Technical Reports Server (NTRS)

    West, Jeff; Yang, H. Q.; Brodnick, Jacob; Sansone, Marco; Westra, Douglas

    2016-01-01

    The Miles equation has long been used to predict slosh damping in liquid propellant tanks due to ring baffles. The original work by Miles identifies defined limits to its range of application. Recent evaluations of the Space Launch System identified that the Core Stage baffle designs resulted in violating the limits of the application of the Miles equation. This paper describes the work conducted by NASA/MSFC to develop methods to predict slosh damping from ring baffles for conditions for which Miles equation is not applicable. For asymptotically small slosh amplitudes or conversely large baffle widths, an asymptotic expression for slosh damping was developed and calibrated using historical experimental sub-scale slosh damping data. For the parameter space that lies between region of applicability of the asymptotic expression and the Miles equation, Computational Fluid Dynamics simulations of slosh damping were used to develop an expression for slosh damping. The combined multi-regime slosh prediction methodology is shown to be smooth at regime boundaries and consistent with both sub-scale experimental slosh damping data and the results of validated Computational Fluid Dynamics predictions of slosh damping due to ring baffles.

  8. Lattice design for an ILC damping ring with 3 km circumference

    SciTech Connect

    Wolski, Andrzej

    2004-10-11

    We describe a simple lattice that meets the specifications for the damping times and horizontal and longitudinal emittances for the International Linear Collider (ILC) damping rings. The circumference of a little over 3 km leads to a bunch spacing of around 3 ns, which will require advances in kicker technology for injection and extraction. We present the lattice design, and initial results of studies of the acceptance and collective effects. With the high bunch charge and close spacing, the ion and electron cloud effects are expected to be severe; however, the simple structure of the lattice allows for easy variation of the circumference and bunch spacing, which may make it useful for future investigations.

  9. The Conversion and operation of the Cornell electron storage ring as a test accelerator (cesrta) for damping rings research and development

    SciTech Connect

    Palmer, M.A.; Alexander, J.; Byrd, J.; Celata, C.M.; Corlett, J.; De Santis, S.; Furman, M.; Jackson, A.; Kraft, R.; Munson, D.; Penn, G.; Plate, D.; Rawlins, A.; Venturini, M.; Zisman, M.; Billing, M.; Calvey, J.; Chapman, S.; Codner, G.; Conolly, C.; Crittenden, J.; Dobbins, J.; Dugan, G.; Fontes, E.; Forster, M.; Gallagher, R.; Gray, S.; Greenwald, S.; Hartill, D.; Hopkins, W.; Kandaswamy, J.; Kreinick, D.; Li, Y.; Liu, X.; Livezey, J.; Lyndaker, A.; Medjidzade, V.; Meller, R.; Peck, S.; Peterson, D.; Rendina, M.; Revesz, P.; Rice, D.; Rider, N.; Rubin, D.; Sagan, D.; Savino, J.; Seeley, R.; Sexton, J.; Shanks, J.; Sikora, J.; Smolenski, K.; Strohman, C.; Temnykh, A.; tigner, M.; Whitney, W.; Williams, H.; Vishniakou, S.; Wilkens, T.; Harkay, K.; Holtzapple, R.; Smith, E.; Jones, J.; Wolski, A.; He, Y.; Ross, M.; Tan, C.Y.; Zwaska, R.; Flanagan, J.; Jain, P.; Kanazawa, K.; Ohmi, K.; Sakai, H.; Shibata, K.; Suetsugu, Y.; Kharakh, D.; Pivi, M.; Wang, L.

    2009-05-01

    In March of 2008, the Cornell Electron Storage Ring (CESR) concluded twenty eight years of colliding beam operations for the CLEO high energy physics experiment. We have reconfigured CESR as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R&D. The primary goals of the CesrTA program are to achieve a beam emittance approaching that of the ILC Damping Rings with a positron beam, to investigate the interaction of the electron cloud with both low emittance positron and electron beams, to explore methods to suppress the electron cloud, and to develop suitable advanced instrumentation required for these experimental studies (in particular a fast x-ray beam size monitor capable of single pass measurements of individual bunches). We report on progress with the CESR conversion activities, the status and schedule for the experimental program, and the first experimental results that have been obtained.

  10. Wigglers and single-particle dynamics in the NLC damping rings

    SciTech Connect

    Venturini, Marco; Wolski, Andrzej; Dragt, Alex

    2003-05-06

    Wiggler insertions are expected to occupy a significant portion of the lattice of the Next Linear Collider (NLC) Main Damping Rings (MDR) and have a noticeable impact on the single-particle beam dynamics. Starting from a realistic 3D representation of the magnetic fields we calculate the transfer maps for the wigglers, accounting for linear and nonlinear effects, and we study the beam dynamics with particular attention paid to the Dynamic Aperture(DA). A DA reduction is observed but appears to remain within acceptable limits.

  11. Development of an Adder-Topology ILC Damping Ring Kicker Modulator

    SciTech Connect

    Tang, Tao; Burkhart, Craig; /SLAC

    2009-05-08

    The ILC damping ring injection and extraction kickers will require high availability modulators that can deliver {+-}5 kV pulses into 50 {Omega} with a 2 ns flattop ({approx}1 ns rise and fall time) at up to 6 MHz. An effort is underway at SLAC National Accelerator Laboratory to meet these requirements using a transmission line adder topology to combine the output of an array of {approx}1 kV modules. The modules employ an ultra-fast hybrid MOSFET/driver that can switch 33 A in 1.2 ns. Experimental results for a scale adder structure are presented.

  12. Operating experience with high beam currents and transient beam loading in the SLC damping rings

    SciTech Connect

    Minty, M.G.; Akre, R.; Krejcik, P.; Siemann, R.H.

    1995-06-01

    During the 1994 SLC run the nominal operating intensity in the damping rings was raised from 3.5 {times} 10{sup 10} to greater than 4 {times} 10{sup 10} particles per bunch (ppb). Stricter regulation of rf system parameters was required to maintain stability of the rf system and particle beam. Improvements were made in the feedback loops which control the cavity amplitude and loading angles. Compensation for beam loading was also required to prevent klystron saturation during repetition rate changes. To minimize the effects of transient loading on the rf system, the gain of the direct rf feedback loop and the loading angles were optimized.

  13. Klystron power specifications based on transient beam loading analysis in damping rings

    SciTech Connect

    Minty, M.G.; Siemann, R.H.

    1995-06-01

    A useful diagram is presented and used to study rf cavity voltage regulation in a damping ring or other circular accelerator where large beam currents are injected and extracted rapidly. With conventional feedback systems and high particle beam currents, the maximum beam current can be limited by the ability of the klystron to maintain constant gap voltage at high currents, low currents, or in the absence of beam. Techniques for storing high current beams are suggested when the maximum klystron output power is predetermined. Alternately, these techniques may be applied and used to specify the performance requirements of the klystron if the desired particle beam current and nominal rf cavity voltage are known.

  14. Simulation and analysis of rf feedback systems on the SLC damping rings

    SciTech Connect

    Minty, M.; Himel, T.; Krejcik, P.; Siemann, R.H.; Tighe, R.

    1993-09-01

    The rf system of the SLC Damping Rings has evolved since tighter tolerances on beam stability are encountered as beam intensities are increased. There are now many feedback systems controlling the phase and amplitude of the rf, the phase of the beam, and the tune of the cavity. The bandwidths of the feedback loops range from several MHz to compensate for beam loading to a few Hz for the cavity tuners. To improve our understanding of the interaction of these loops and verify the expected behavior, we have simulated their behavior using computer models. A description of the models and the first results are discussed.

  15. TOSCA calculations and measurements for the SLAC SLC damping ring dipole magnet

    SciTech Connect

    Early, R.A.; Cobb, J.K.

    1985-04-01

    The SLAC damping ring dipole magnet was originally designed with removable nose pieces at the ends. Recently, a set of magnetic measurements was taken of the vertical component of induction along the center of the magnet for four different pole-end configurations and several current settings. The three dimensional computer code TOSCA, which is currently installed on the National Magnetic Fusion Energy Computer Center's Cray X-MP, was used to compute field values for the four configurations at current settings near saturation. Comparisons were made for magnetic induction as well as effective magnetic lengths for the different configurations. 1 ref., 12 figs., 2 tabs.

  16. Simulation Studies On The Vertical Emittance Growth At The Existing ATF Extraction Beamline

    SciTech Connect

    Zhou, F.; Amann, J.; Seletskiy, S.; Seryi, A.; Spencer, C.M.; Woodley, M.D.

    2008-06-27

    Significant beam intensity-dependence of the vertical emittance growth was experimentally observed at the Accelerator Test Facility (ATF) at KEK extraction beamline. This paper presents the simulations of possible vertical emittance growth sources, particularly in the extraction channel, where the magnets are shared by both the ATF extraction beamline and its damping ring. The vertical emittance growth is observed in the simulations by changing the beam orbit in the extraction channel, even with all optics corrections. The possible reasons for the experimentally observed dependence of the vertical emittance growth on the beam intensity are also discussed. An experiment to measure the emittance versus beam orbit at the existing ATF extraction beamline is on-going led by the European colleagues.

  17. Electron Cloud in the Wigglers of the Positron Damping Ring of the International Linear Collider

    SciTech Connect

    Wang, L.; /SLAC

    2007-07-06

    The ILC positron damping ring comprises hundreds of meters of wiggler sections, where many more photons than in the arcs are emitted, and with the smallest beampipe aperture of the ring. A significant electron-cloud density can therefore be accumulated via photo-emission and via beam-induced multipacting. In field-free regions the electron-cloud build up may be suppressed by adding weak solenoid fields, but the electron cloud remaining in the wigglers as well as in the arc dipole magnets can still drive single-bunch and multi-bunch beam instabilities. This paper studies the electron-cloud formation in an ILC wiggler section for various scenarios, as well as its character, and possible mitigation schemes.

  18. RF cavity R&D at LBNL for the NLC damping rings, FY1999

    SciTech Connect

    Rimmer, R.A.; Corlett, J.N.; Koehler, G.; Li, D.; Hartman, N.; Rasson, J.; Saleh, T.

    1999-11-01

    This report contains a summary of the R&D activities at LBNL on RF cavities for the NLC damping rings during fiscal year19999. These activities include the optimization of the RF design for both efficiency and damping of higher-order (HOMs), by systematic study of the cavity profile, the effect of the beam pipe diameter, nosecone angle and gap, the cross section and position of the HOM damping waveguides and the coupler. The effect of the shape of the HOM waveguides and their intersection with the cavity wall on the local surface heating is also an important factor, since it determines the highest stresses in the cavity body. This was taken into account during the optimization so that the stresses could be reduced at the same time as the HOP damping was improved over previous designs. A new method of calculating the RF heating was employed, using a recently released high frequency electromagnetic element in ANSYS. This greatly facilitates the thermal and stress analysis of the design and fabrication methods have been developed with the goals of lower stresses, fewer parts and simpler assembly compared to previous designs. This should result in substantial cost savings. Preliminary designs are described for the cavity ancillary components including the RF window, HOM loads, and tuners. A preliminary manufacturing plan is included, with an initial estimate of the resource requirements. Other cavity options are discussed which might be desirable to either lower the R/Q, for reduced transient response, or lower the residual HOM impedance to reduce coupled-bunch growth rates further still.

  19. Thermoelastic damping effect of the micro-ring resonator with irregular mass and stiffness

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Hwan; Kim, Ji-Hwan

    2016-05-01

    Fundamentally, vibration characteristic is a main factor for the stability of structures. In this regard, the irregularity of mass and stiffness distributions for the structure have been an interesting issue for many years. Recently, the Micro Electro Mechanical Systems (MEMS) are developed for various applications such as gyro sensors. In the present work, in-plane vibration of micro-ring structure with multiple finite-sized imperfections is investigated. Then, the unbalance of the structure is represented using Heaviside Step Function for the inextensional modeling of the ring. Also, thermoelastic damping (TED) due to internal friction is studied based on Fourier's one-dimensional heat conduction equation using Laplace Transform. To obtain the quality-factors (Q-factors) for imperfect micro-ring, analytical solutions are calculated from governing equations of motion with TED. And then, the natural frequencies and the Q-factors are observed to separate into lower and higher modes. Additionally, the vibration mode shapes are presented, and the frequency trimming concept due to attached imperfections is investigated.

  20. Longitudinal beam-transfer-function measurements at the SLC damping rings

    SciTech Connect

    Minty, M.G.; Zimmermann, F.

    1997-05-01

    A longitudinal single-bunch instability in the damping rings at the Stanford Linear Collider (SLC) is thought to contribute to pulse-to-pulse orbit variations in downstream accelerator sections. To better understand this instability, the authors measured the beam phase and bunch length under harmonic modulations of the rf phase and rf voltage. For small phase-modulations the measured response can be explained by interaction of the beam with the cavity fundamental mode. For larger excitations, they observed bifurcation and hysteresis effects. The response to an rf voltage modulation revealed two peaks near the quadrupole-mode frequency, one of which appears to be related to the longitudinal instability. In this paper they present the experimental results.

  1. Particle-in-Cell Calculationsof the Electron Cloud in the ILCPositron Damping Ring Wigglers

    SciTech Connect

    Celata, C.M.; Furman, M.A.; Vay, J.-L.; Grote, D.P.

    2007-07-01

    The self-consistent code suite WARP-POSINST is being used to study electron cloud effects in the ILC positron damping ring wiggler. WARP is a parallelized, 3D particle-in-cell code which is fully self-consistent for all species. The POSINST models for the production of photoelectrons and secondary electrons are used to calculate electron creation. Mesh refinement and a moving reference frame for the calculation will be used to reduce the computer time needed by several orders of magnitude. We present preliminary results for cloud buildup showing 3D electron effects at the nulls of the vertical wiggler field. First results from a benchmark of WARP-POSINST vs. POSINST are also discussed.

  2. Longitudinal Single-Bunch Instability in the ILC Damping Rings: Estimate of Current Threshold

    SciTech Connect

    Venturini, Marco; Venturini, Marco

    2008-06-25

    Characterization of single-bunch instabilities in the International Linear Collider (ILC) damping rings (DRs) has been indicated as a high-priority activity toward completion of an engineering design. In this paper we report on a first estimate ofthe current thresholds for the instability using numerical and analytical models of the wake potentials associated with the various machine components. The numerical models were derived (upon appropriate scaling) from designs of the correspondingcomponents installed in existing machines. The current thresholds for instabilities were determined by numerical solution of the Vlasov equation for the longitudinal dynamics. For the DR baseline lattice as of Feb. 2007 we find the critical current forinstability to be safely above the design specifications leaving room for further optimization of the choice of the momentum compaction.

  3. Review of stripline beam impedance: application to the extraction kicker for the CLIC damping rings

    NASA Astrophysics Data System (ADS)

    Belver-Aguilar, C.; Barnes, M. J.

    2017-07-01

    The beam coupling impedance of the stripline kicker for beam extraction from the CLIC Damping Rings (DRs) has been studied analytically, numerically with Computer Simulation Technology (CST) Particle Studio (PS) and measured in the laboratory, although not all the results were previously understood. In order to have a better knowledge about the beam coupling impedance of a stripline kicker, a simple model has now been studied, with flat electrodes and a cylindrical beam pipe. From this preliminary study, a new approach for the dipolar component of the horizontal impedance has been derived, when considering both odd and even operating modes of the striplines. This new approach has been used to understand the differences found between the predicted transverse impedance and the two wires measurements carried out in the laboratory for the prototype CLIC DR striplines. Future tests of beam coupling impedance with beam in the ALBA Synchrotron Light Source will complete this study.

  4. Phase detector and phase feedback for a single bunch in a two-bunch damping ring for the SLAC Linear Collider

    SciTech Connect

    Schwarz, H.D.; Judkins, J.G.

    1987-03-01

    The synchronous phase of a bunch of positrons or electrons being damped in a SLAC Linear Collider (SLC) damping ring is dependent on beam intensity. Injection for alternate bunches into the SLC linac from the damping rings should occur at a constant phase. A phase detector was developed allowing the measurement of phase of a single-stored bunch in the presence of a second bunch in reference to the phase of the linac. The single-bunch phase is derived from beam position monitor signals using a switching scheme to separate the two bunches circulating in each damping ring. The hardware is described including feedback loops to stabilize the extraction phase.

  5. CESR Conversion Damping Ring Studies of Electron Cloud Instabilities (CESR-TA)

    SciTech Connect

    Rubin, David L.; Palmer, Mark A.

    2011-08-02

    In the International Linear Collider, two linear accelerators will accelerate bunches of positrons and electrons to over a hundred billion electron volts and collide them in a central detector. In order to obtain useful collision rates, the bunches, each containing twenty billion particles, must be compressed to a cross section of a few nanometers by a few hundred nanometers. In order to prepare these ultra high density bunches, damping rings (DRs) are employed before the linear accelerators. The DRs take the high emittance bunches that are provided by the electron and positron sources and, through the process of radiation damping, squeeze them into ultra low emittance beams that are ready for the main linear accelerators. In the damping rings, a number of effects can prevent the successful preparation of the beams. In the electron ring, an effect known as the fast ion instability can lead to beam growth and, in the positron ring, the build-up of an electron cloud (EC), which interacts with the circulating bunches, can produce the same effect. EC build-up and the subsequent interaction of the cloud with the positron beam in the DR have been identified as major risks for the successful construction of a linear collider. The CESRTA research program at the Cornell Electron Storage Ring (CESR) was developed in order to study the build-up of the EC, the details of its impact on ultra low emittance beams, as well as methods to mitigate the impact of the cloud. In the DR, the EC forms when synchrotron photons radiated from the circulating beam strike the walls of the vacuum chamber, resulting in the emission of photoelectrons. These low energy electrons can be accelerated across the vacuum chamber by the electric field of the beam, and strike the walls, causing the emission of secondary electrons. The secondary electrons are subsequently accelerated into the walls yet again via the same mechanism. The result is that the EC can rapidly begin to fill the vacuum chamber. In

  6. Energy matching of 1. 2 GeV positron beam to the SLC (Stanford Linear Collider) damping ring

    SciTech Connect

    Clendenin, J.E.; Helm, R.H.; Jobe, R.K.; Kulikov, A.; Sheppard, J.C.

    1989-08-01

    Positrons collected at the SLC positron source are transported over a 2-km path at 220 MeV to be reinjected into the linac for acceleration to 1.2 GeV, the energy of the emittance damping ring. Since the positron bunch length is a significant fraction of a cycle of the linac-accelerating RF, the energy spread at 1.2 GeV is considerably larger than the acceptance of the linac-to-ring (LTR) transport system. Making use of the large pathlength difference at the beginning of the LTR due to this energy spread, a standard SLAC 3-m accelerating section has been installed in the LTR to match the longitudinal phase space of the positron beam to the acceptance of the damping ring. The design of the matching system is described, and a comparison of operating results within simulations is presented. 5 refs., 4 figs., 1 tab.

  7. Study of Abnormal Vertical Emittance Growth in ATF Extraction Line

    SciTech Connect

    Alabau, M.; Faus-Golfe, A.; Alabau, M.; Bambade, P.; Brossard, J.; Le Meur, G.; Rimbault, C.; Touze, F.; Angal-Kalinin, D.; Jones, J.K.; Appleby, R.; Scarfe, A.; Kuroda, S.; White, G.R.; Woodley, M.; Zimmermann, F.; /CERN

    2011-11-04

    Since several years, the vertical beam emittance measured in the Extraction Line (EXT) of the Accelerator Test Facility (ATF) at KEK, that will transport the electron beam from the ATF Damping Ring (DR) to the future ATF2 Final Focus beam line, is significantly larger than the emittance measured in the DR itself, and there are indications that it grows rapidly with increasing beam intensity. This longstanding problem has motivated studies of possible sources of this anomalous emittance growth. One possible contribution is non-linear magnetic fields in the extraction region experimented by the beam while passing off-axis through magnets of the DR during the extraction process. In this paper, simulations of the emittance growth are presented and compared to observations. These simulations include the effects of predicted non-linear field errors in the shared DR magnets and orbit displacements from the reference orbit in the extraction region. Results of recent measurements using closed orbit bumps to probe the relation between the extraction trajectory and the anomalous emittance growth are also presented.

  8. Stripline design for the extraction kicker of Compact Linear Collider damping rings

    NASA Astrophysics Data System (ADS)

    Belver-Aguilar, C.; Faus-Golfe, A.; Toral, F.; Barnes, M. J.

    2014-07-01

    In the framework of the design study of future linear colliders, the Compact Linear Collider (CLIC) aims for electron-positron collisions with high luminosity at a nominal center-of-mass energy of 3 TeV. To achieve the luminosity requirements, predamping rings (PDRs) and damping rings (DRs) are required: they reduce the beam emittance before the beam is accelerated in the main linac. Several kicker systems are needed to inject and extract the beam from the PDRs and DRs. In order to achieve both low beam coupling impedance and reasonable broadband impedance matching to the electrical circuit, striplines have been chosen for the kicker elements. In this paper, we present the complete design of the striplines for the DR extraction kicker, since it is the most challenging from the field homogeneity point of view. The excellent field homogeneity required, as well as a good transmission of the high voltage pulse through the electrodes, has been achieved by choosing a novel electrode shape. With this new geometry, it has been possible to benefit from all the advantages that the most common shapes introduce separately. Furthermore, a detailed study of the different operating modes of a stripline kicker allowed the beam coupling impedance to be reduced at low frequencies: this cannot be achieved by tapering the electrodes. The optimum design of the striplines and their components has been based on studies of impedance matching, field homogeneity, power transmission, beam coupling impedance, and manufacturing tolerances. Finally, new ideas for further improvement of the performance of future striplines are reported.

  9. Effect of Wiggler insertions on the single-particle dynamics of the NLC main damping rings

    SciTech Connect

    Venturini, Marco

    2003-07-30

    As they are expected to occupy a large portion of the lattice, wiggler insert ions will introduce significant linear and nonlinear perturbations to the single-particle dynamics in the NLC Main Damping Rings (MDR). The nonlinearities are of particular concern as a sufficiently large Dynamic Aperture (DA) is required for high injection efficiency. The main content of this report is a study of the wigglers impact on the DA of the NLC-MDR latest lattice design. The particle dynamics is modeled by transfer maps calculated by integration through the wiggler fields. For field representation we employed a 3D multipole expansion derived from the field data that were obtained with the aid of a magnet design code. Additional contents of this paper include an investigation of a simplified model of wiggler consisting of a sequence of standard magnet elements (where thin octupoles are used to represent the dominant nonlinearities) and the suggestion of a possible correction scheme to compensate the wiggler nonlinearities.

  10. ILC Damping Rings: Benefit of the Antechamber or: Antechamber vs. SEY

    SciTech Connect

    Furman, M. A.

    2011-03-30

    We present simulation results of the build-up of the electron-cloud density ne for the two proposed ILC damping ring lattices, DC04 and DSB3, with particular attention to the potential benefit of an antechamber. We examine a field-free region and a dipole bending magnet, with or without an antechamber. We assume a secondary electronemission model for the chamber surface based on approximate fits to measured data for TiN, except that we let the peak value of the secondary emission yield (SEY), delta max, be a variable. We conclude that there is a critical value of delta max below which the antechamber provides a substantial benefit, roughly a factor ~;;40 reduction in ne relative to the case in which max exceeds the critical value. We estimate the steady-state value of ne as a function of delta max, and thereby obtain the critical value of delta max for all cases considered. Thus, from the perspective of the electron-cloud effect, the inclusion of an antechamber in the design is justified only if delta max is below the critical value. The results presented here constitute a slight extension of those previously presented in March and September, 2010 [1, 2].

  11. Recent Electron-Cloud Simulation Results for the Main Damping Rings of the NLC and the TESLA Linear Colliders

    SciTech Connect

    Pivi, Mauro T F

    2003-05-19

    In the beam pipe of the Main Damping Ring (MDR) of the Next Linear Collider (NLC), ionization of residual gases and secondary emission give rise to an electron-cloud which stabilizes to equilibrium after few bunch trains. In this paper, we present recent computer simulation results for the main features of the electron cloud at the NLC and preliminary simulation results for the TESLA main damping rings, obtained with the code POSINST that has been developed at LBNL, and lately in collaboration with SLAC, over the past 7 years. Possible remedies to mitigate the effect are also discussed. We have recently included the possibility to simulate different magnetic field configurations in our code including solenoid, quadrupole, sextupole and wiggler.

  12. Recent electron-cloud simulation results for the main damping rings of the NLC and TESLA linear colliders

    SciTech Connect

    Pivi, M.; Raubenheimer, T.O.; Furman, M.A.

    2003-05-01

    In the beam pipe of the Main Damping Ring (MDR) of the Next Linear Collider (NLC), ionization of residual gases and secondary emission give rise to an electron-cloud which stabilizes to equilibrium after few bunch trains. In this paper, we present recent computer simulation results for the main features of the electron cloud at the NLC and preliminary simulation results for the TESLA main damping rings, obtained with the code POSINST that has been developed at LBNL, and lately in collaboration with SLAC, over the past 7 years. Possible remedies to mitigate the effect are also discussed. We have recently included the possibility to simulate different magnetic field configurations in our code including solenoid, quadrupole, sextupole and wiggler.

  13. Numerical investigation of beam halo from beam gas scattering in KEK-ATF

    NASA Astrophysics Data System (ADS)

    Yang, R.; Bambade, P.; Kubo, K.; Okugi, T.; Terunuma, N.; Zhou, D.

    2017-07-01

    To demonstrate the final focus schemes of the Future Linear Collider (FLC), the Accelerator Test Facility 2 (ATF2) at KEK is devoted to focus the beam to a RMS size of a few tens of nanometers (nm) vertically and to provide stability at the nm level at the virtual Interaction Point (IP). However, the loss of halo particles upstream will introduce background to the diagnostic instrument measuring the ultra-small beam, using a laser interferometer monitor. To help the realization of the above goals and beam operation, understanding and mitigation of beam halo are crucial. In this paper, we present the systematical simulation of beam halo formation from beam gas Coulomb scattering (BGS) in the ATF damping ring. The behavior of beam halo with various machine parameters is also discussed.

  14. HOM-damped re-entrant quasi-half-cell cavity for the SPring-8 storage ring

    NASA Astrophysics Data System (ADS)

    Ego, Hiroyasu

    2004-01-01

    A newly designed RF accelerating cavity resonating 508.58 MHz is proposed for reinforcement of beam current in the SPring-8 storage ring. Since an increase in beam current induces coupled-bunch instabilities arising from coupling impedances of higher-order modes in RF cavities, the new RF cavity is provided with three ways for damping the higher-order modes: a re-entrant quasi-half-cell structure, ports skewing the field distributions of the higher-order modes and a grooved beam pipe terminated by materials absorbing RF power. The RF properties of the higher-order modes in the RF cavity were examined by the MAFIA frequency-domain simulation. The measured RF properties of the higher-order modes in an aluminum model cavity were consistent with the simulations and verified the performance of damping the higher-order modes in the RF cavity.

  15. Instability Thresholds And Generation of the Electron-Cloud in the GLC/NLC And Tesla Damping Rings

    SciTech Connect

    Pivi, M.

    2005-04-11

    In the beam pipe of the Damping Ring (DR) of a linear collider, an electron cloud may be produced by ionization of residual gas or photoelectrons and develop by the secondary emission process [1]. Coupling between the electrons and the circulating beam can cause coupled-bunch instabilities, coherent single-bunch instabilities or incoherent tune spreads that may lead to increased emittance, beam blow-up and ultimately to beam losses. We present recent computer simulation results for the electron cloud instability thresholds in the GLC/NLC (X-Band) main DR and for the TESLA DR.

  16. RF cavity R&D at LBNL for the NLC Damping Rings,FY2000/2001

    SciTech Connect

    Rimmer, R.A.; Atkinson, D.; Corlett, J.N.; Koehler, G.; Li, D.; Hartman, N.; Rasson, J.; Saleh, T.; Weidenbach, W.

    2001-06-01

    This report contains a summary of the R&D activities at LBNL on RF cavities for the NLC damping rings during fiscal years 2000/2001. This work is a continuation of the NLC RF system R&D of the previous year [1]. These activities include the further optimization and fine tuning of the RF cavity design for both efficiency and damping of higher-order modes (HOMs). The cavity wall surface heating and stresses were reduced at the same time as the HOM damping was improved over previous designs. Final frequency tuning was performed using the high frequency electromagnetic analysis capability in ANSYS. The mechanical design and fabrication methods have been developed with the goals of lower stresses, fewer parts and simpler assembly compared to previous designs. This should result in substantial cost savings. The cavity ancillary components including the RF window, coupling box, HOM loads, and tuners have been studied in more detail. Other cavity options are discussed which might be desirable to either further lower the HOM impedance or increase the stored energy for reduced transient response. Superconducting designs and the use of external ''energy storage'' cavities are discussed. A section is included in which the calculation method is summarized and its accuracy assessed by comparisons with the laboratory measurements of the PEP-II cavity, including errors, and with the beam-sampled spectrum.

  17. Novel Slide-Ring Material/Natural Rubber Composites with High Damping Property

    NASA Astrophysics Data System (ADS)

    Wang, Wencai; Zhao, Detao; Yang, Jingna; Nishi, Toshio; Ito, Kohzo; Zhao, Xiuying; Zhang, Liqun

    2016-03-01

    A novel class of polymers called “slide-ring” (SR) materials with slideable junctions were used for high damping composites for the first time. The SR acts as the high damping phase dispersed in the natural rubber (NR) matrix, and epoxidized natural rubber (ENR) acts as the compatibilizer. The morphological, structural, and mechanical properties of the composites were investigated by atomic force microscope (AFM), transmission electron microscope (TEM), dynamic mechanical thermal analyzer (DMTA), rubber processing analyzer (RPA), and tensile tester. AFM and TEM results showed that the SR phase was uniformly dispersed in the composites, in a small size that is a function of ENR. DMTA and RPA results showed that the damping factor of the composites is much higher than that of NR, especially at room temperatures. Stretch hysteresis was used to study the energy dissipation of the composites at large strains. The results showed that SR and ENR can significantly improve the dissipation efficiency at strains lower than 200% strain. Wide-angle X-ray diffraction was used to study the strain-induced crystallization of the composites. The results indicated that the impact of the SR on the crystallization of NR is mitigated by the insulating effect of ENR.

  18. Novel Slide-Ring Material/Natural Rubber Composites with High Damping Property

    PubMed Central

    Wang, Wencai; Zhao, Detao; Yang, Jingna; Nishi, Toshio; Ito, Kohzo; Zhao, Xiuying; Zhang, Liqun

    2016-01-01

    A novel class of polymers called “slide-ring” (SR) materials with slideable junctions were used for high damping composites for the first time. The SR acts as the high damping phase dispersed in the natural rubber (NR) matrix, and epoxidized natural rubber (ENR) acts as the compatibilizer. The morphological, structural, and mechanical properties of the composites were investigated by atomic force microscope (AFM), transmission electron microscope (TEM), dynamic mechanical thermal analyzer (DMTA), rubber processing analyzer (RPA), and tensile tester. AFM and TEM results showed that the SR phase was uniformly dispersed in the composites, in a small size that is a function of ENR. DMTA and RPA results showed that the damping factor of the composites is much higher than that of NR, especially at room temperatures. Stretch hysteresis was used to study the energy dissipation of the composites at large strains. The results showed that SR and ENR can significantly improve the dissipation efficiency at strains lower than 200% strain. Wide-angle X-ray diffraction was used to study the strain-induced crystallization of the composites. The results indicated that the impact of the SR on the crystallization of NR is mitigated by the insulating effect of ENR. PMID:26949077

  19. Superconducting 72-pole Indirect Cooling 3Tesla Wiggler for CLIC Damping Ring and ANKA Image Beamline

    NASA Astrophysics Data System (ADS)

    Bragin, A.; Gusev, Ye.; Khrushchev, S.; Mezentsev, N.; Shkaruba, V.; Syrovatin, V.; Tarasenko, O.; Tsukanov, V.; Volkov, A.; K. Zolotarev; Zorin, A.

    One of the directions of BINP activity is the creation of multipole superconducting wigglers with the magnetic field levels from 2 T to 7.5 T which are installed on many SR sources. Special efforts were made by BINP to develop the cryogenic system with zero liquid helium consumption. The next significant step became the design and creation of superconducting full size prototype of damping wiggler for CLIC project where supposed the installation of 104 wigglers. For operation of CLIC damping wiggler it is required the magnetic field of 3 T and the period about 50 mm with a beam vertical aperture of 13 mm. Design features of the wiggler which was proposed and created by BINP is the application of the indirect cooling method. In this case Nb-Ti magnet with the length of 1.9 m and the weight of 700 kg is located in a vacuum and is cooled by four Gifford-McMahon cryocoolers. To maintain the temperature about 4.2 K on the magnet it is used the tubes with circulating liquid helium as the heat conducting elements. To increase the efficiency of pre-cooling down of the magnet it is used nitrogen-based heat pipes of siphon type. The features of the magnetic and cryogenic systems of CLIC damping wiggler full size prototype and test results are presented in this article.

  20. Simulation of radiation damping in rings, using stepwise ray-tracing methods

    DOE PAGES

    Meot, F.

    2015-06-26

    The ray-tracing code Zgoubi computes particle trajectories in arbitrary magnetic and/or electric field maps or analytical field models. It includes a built-in fitting procedure, spin tracking many Monte Carlo processes. The accuracy of the integration method makes it an efficient tool for multi-turn tracking in periodic machines. Energy loss by synchrotron radiation, based on Monte Carlo techniques, had been introduced in Zgoubi in the early 2000s for studies regarding the linear collider beam delivery system. However, only recently has this Monte Carlo tool been used for systematic beam dynamics and spin diffusion studies in rings, including eRHIC electron-ion collider projectmore » at the Brookhaven National Laboratory. Some beam dynamics aspects of this recent use of Zgoubi capabilities, including considerations of accuracy as well as further benchmarking in the presence of synchrotron radiation in rings, are reported here.« less

  1. Simulation of radiation damping in rings, using stepwise ray-tracing methods

    SciTech Connect

    Meot, F.

    2015-06-26

    The ray-tracing code Zgoubi computes particle trajectories in arbitrary magnetic and/or electric field maps or analytical field models. It includes a built-in fitting procedure, spin tracking many Monte Carlo processes. The accuracy of the integration method makes it an efficient tool for multi-turn tracking in periodic machines. Energy loss by synchrotron radiation, based on Monte Carlo techniques, had been introduced in Zgoubi in the early 2000s for studies regarding the linear collider beam delivery system. However, only recently has this Monte Carlo tool been used for systematic beam dynamics and spin diffusion studies in rings, including eRHIC electron-ion collider project at the Brookhaven National Laboratory. Some beam dynamics aspects of this recent use of Zgoubi capabilities, including considerations of accuracy as well as further benchmarking in the presence of synchrotron radiation in rings, are reported here.

  2. Beam-Based Alignment, Tuning and Beam Dynamics Studies for the ATF2 Extraction Line and Final Focus System

    SciTech Connect

    White, Glen R.; Molloy, S.; Woodley, M.; /SLAC

    2008-07-25

    Using a new extraction line currently under construction, the ATF2 experiment plans to test the novel compact final focus optics design with local chromaticity correction intended for use in future linear colliders. With a 1.3 GeV design beam of 30nm normalized vertical emittance extracted from the ATF damping ring, the primary goal is to achieve a vertical spot-size at the IP waist of 37nm. We discuss our planned strategy for tuning the ATF2 beam to meet the primary goal. Simulation studies have been performed to asses the effectiveness of the strategy, including 'static' (installation) errors and dynamical effects (ground-motion, mechanical vibration, ring extraction jitter etc.). We have simulated all steps in the tuning procedure, from initial orbit establishment to final IP spot-size tuning. Through a Monte Carlo study of 100's of simulation seeds we find we can achieve a spot-size within {approx}10% of the design optics value in at least 75% of cases. We also ran a simulation to study the long-term performance with the use of beam-based feedbacks.

  3. ATF2 Proposal

    SciTech Connect

    Grishanov, Boris Ivanovich; Logachev, Pavel; Podgorny, Fedor; Telnov, Valery; Angal-Kalinin, Deepa; Appleby, Robert; Jones, James; Kalinin, Alexander; Napoly, Olivier; Payet, Jacques; Braun, Hans-Heinrich; Schulte, Daniel; Zimmermann, Frank; Barlow, Roger; Bailey, Ian; Jenner, Leo; Jones, Roger; Kourevlev, German; Walker, Nick; Takahasi, Tohru; Gao, Jie; /Beijing, Inst. High Energy Phys. /Oxford U. /KEK, Tsukuba /Kyoto U., Inst. Chem. Res. /Orsay, LAL /LBL, Berkeley /LLNL, Livermore /University Coll. London /Chiba, Natl. Inst. Rad. Sci. /North Carolina A-T State U. /Oregon U. /Pohang Accelerator Lab. /Queen Mary, U. of London /SLAC /Tokyo U.

    2005-08-23

    This document is the first of two volumes describing the ATF2 project. The present volume discusses the technical justification for ATF2 and presents a design description. Since the International Committee for Future Accelerator (ICFA) decision on the choice of technology, a world-wide collaboration on the design of the International Linear Collider (ILC) has rapidly progressed [1]. The formation of the Global Design Effort (GDE) will accelerate the work towards a final design. An important technical challenge is obviously the high gradient acceleration but what is similarly challenging is the collision of extremely small beams of a few nanometer size. The latter challenge has three distinct issues: creating small emittance beams, preserving the emittance during acceleration and transport, and focusing the beams to nanometers. Most studies have been done using computer simulations but many issues still remain that require experimental verification. Accelerator Test Facility (ATF) at KEK was built to create small emittance beams, and succeeded in obtaining an emittance that almost satisfies the ILC requirements [2]. In this proposal we present a project, ATF2, which addresses the focusing of the beam into a nanometer spot. The ATF2 project will extend the extraction beamline of the ATF with an ILC-type final focus system to create a tightly focused, stable beam by making use of the small emittance of the ATF. The layout is shown in Figure 1.1. In the longer term, the ATF2 project would also provide invaluable input for the CLIC design of a future multi-TeV collider.

  4. Straw Formation and Enhanced Damping of Strong Density Waves in Saturn’s Rings

    NASA Astrophysics Data System (ADS)

    Stewart, Glen R.

    2017-06-01

    High resolution Cassini images of strong density waves in Saturn’s rings often show kilometer-scale structures in the wave troughs that are sometimes described as straw-like structures. These structures are likely formed by transient gravitational instabilities within the density wave and have the potential to greatly enhance the local viscous angular momentum transport and thereby limit the maximum amplitude of the density wave. A Hamiltonian theory for density waves has been developed that can describe the rate of local gravitational instabilities in the wave train. The Hamiltonian for single particle motion in the vicinity of an inner Lindblad resonance with a Saturnian satellite can be formulated such that the angle variable conjugate to the radial action is the resonant argument for the resonance. The density wave can then be derived using Hamiltonian perturbation methods to remove the satellite perturbation such that the transformed radial action and conjugate angles include the usual solution for self-gravitating density waves. Local gravitational instabilities in the density wave can now be formulated using a linearized collisionless Boltzmann equation that is expressed in terms of the transformed action-angle variables that contain the density wave solution. The gravitational potential of the linearized perturbation is found to be enhanced by a factor of ten or more in strong density waves, which likely explains the observation of kilometer-scale structures in these waves. The Hamiltonian formalism can also be used to derive an enhanced effective viscosity that results from these straw-like structures.

  5. Electromagnetic characterization of nonevaporable getter properties between 220-330 and 500-750 GHz for the Compact Linear Collider damping rings

    NASA Astrophysics Data System (ADS)

    Koukovini-Platia, E.; Rumolo, G.; Zannini, C.

    2017-01-01

    Due to its effective pumping ability, nonevaporable getter (NEG) coating is considered for the vacuum chambers of the Compact Linear Collider (CLIC) electron damping rings (EDR). The aim is to suppress fast beam ion instabilities. The electromagnetic (EM) characterization of the NEG properties up to ultra-high frequencies is required for the correct impedance modeling of the damping ring (DR) components. The properties are determined using rectangular waveguides which are coated with NEG. The method is based on a combination of complex transmission coefficient S21 measurements with a vector network analyzer (VNA) and 3D simulations using CST Microwave Studio® (CST MWS). The frequency ranges discussed in this paper are 220-330 and 500-750 GHz.

  6. Damping higher order modes in the PEP-II B-Factory storage ring collider

    NASA Astrophysics Data System (ADS)

    Weathersby, Stephen

    2007-05-01

    The PEP-II B-Factory storage ring collider at SLAC provides crucial experimental evidence for the physics of CP violation. To investigate rare B-meson decays requires high luminosity which comes mainly from increasing bunch currents and reducing bunch sizes. Electromagnetic effects of intense bunch fields in the form of wake fields couple into accelerator components, inducing Joule heating at levels detrimental to vacuum chamber components. Additionally, wake fields contribute to beam instability, decreasing luminosity. These effects are limiting B-factory performance. Computer simulations and experimental evidence indicate that beam collimators produce wake fields in the form of dipole and quadrupole waveguide modes which can propagate tens of meters from their source before depositing energy at remote locations. Simulations confirm that coupling through narrow slots into bellows cavities occurs for beam pipe modes. Two proposals are set forth to mitigate wake field effects. The first proposal is to reduce the quality factor of resonant structures with a water cooled dielectric lossy material. Electromagnetic energy coupling into resonant structures can be isolated and safely dissipated. Prototype devices have been built and have been shown to reduce resistive heating in large pumping chambers coupled to the beam chamber. Designs and simulations which incorporate such techiques into bellows devices are presented. The second proposal incorporates novel devices introduced in the accelerator vacuum chamber which selectively traps dipole and quadrupole propagating wake fields before they can couple into sensitive beam line components without introducing impedance to the beam. Scattering parameter analysis is used to tailor device response to specific modes. Dangerous modes are extracted from the beam chamber, trapped and dissipated in a water cooled lossy material. Modes which represent an impedance to the beam are not affected. After design optimization, production

  7. High brightness, high current injector design for the ATF upgrade at Brookhaven National Laboratory

    NASA Astrophysics Data System (ADS)

    Stratakis, Diktys

    2015-04-01

    Brookhaven National Accelerator Test Facility (BNL ATF) is in the process of moving to a new place and upgrading its major capabilities: The electron beam energy and CO2 laser power. Specifically, the maximum electron beam energy will be first projected to 100-150 MeV and then upgraded to 500 MeV while at the same time the laser power will increase 100 fold, thus making the new ATF a powerful tool in advanced accelerator concept research. The bright electron bunch produced by the new state-of-the-art photocathode rf gun will be accelerated and optionally delivered to multiple beamlines. The injector is a key element of this accelerator upgrade. It must deliver a high average current beam with very small transverse and longitudinal emittances, at a sufficiently high energy that space charge effects are under control. We review here the detailed injector design and present first results from beam dynamics simulations. We give emphasis in the production of compressed flat beams which have important applications in novel light-source concepts and could possibly alleviate the need for damping rings in lepton colliders. We present a theoretical model and with the aid of simulation examine the influence of space charge, bunch compression and suggest a operating regime with minimal phase space dilutions.

  8. KEK ATF Injector Upgrade

    SciTech Connect

    Yeremian, anahid D

    1999-03-24

    The main goal at the Accelerator Test Facility (ATF) at the KEK laboratory in Japan is to develop the technology that can stably supply the main linac with an extremely flat multi-bunch beam. The injector for this accelerator was upgraded to produce greater than 2 x 10{sup 10} in electrons a single bunch at 80 MeV in a very narrow bunch.

  9. ATF2 Proposal Volume 2

    SciTech Connect

    Grishanov, B.I.; Logachev, P.; Podgorny, F.; Telnov, V.; Angal-Kalinin, D.; Jones, J.; Kalinin, A.; Napoly, O.; Payet, J.; Braun, H.H.; Schulte, D.; Zimmermann, F.; Appleby, R.; Barlow, R.; Bailey, I.; Jenner, L.; Jones, R.; Kourevlev, G.; Elsen, E.; Vogel, V.; Walker, N.; /DESY /Fermilab /Hiroshima U. /Beijing, Inst. High Energy Phys. /Oxford U. /Royal Holloway, U. of London /KEK, Tsukuba /Kyoto U., Inst. Chem. Res. /Orsay, LAL /Valencia U. /Annecy, LAPP /LBL, Berkeley /LLNL, Livermore /University Coll. London /Chiba, Natl. Inst. Rad. Sci. /North Carolina A-T State U. /Oregon U. /Pohang Accelerator Lab. /Queen Mary, U. of London /SLAC /Tokyo U.

    2006-02-27

    For achieving the high luminosity required at the International Linear Collider (ILC), it is critical to focus the beams to nanometer size with the ILC Beam Delivery System (BDS), and to maintain the beam collision with a nanometer-scale stability. To establish the technologies associated with this ultra-high precision beam handling, it has been proposed to implement an ILC-like final focus optics in an extension of the existing extraction beamline of ATF at KEK. The ATF is considered to be the best platform for this exercise, since it provides an adequate ultra-low emittance electron beam in a manner dedicated to the development of ILC. The two major goals for this facility, called ATF2, are: (A) Achievement of a 37 nm beam size, and (B) control of beam position down to 2 nm level. The scientific justification for the ATF2 project and its technical design have been described in Volume 1 of the ATF2 Proposal [1]. We present here Volume 2 of the ATF2 Proposal, in which we present specifics of the construction plans and the group organization to execute the research programs at ATF2. The sections in this report have been authored by relevant ATF2 subgroups within the International ATF Collaboration. The time line of the project is described in Section 2. Section 3 discuss the structure of the international collaboration. Sections 4 and 5 discuss budget considerations, which are presented as well as the design and construction tasks to be shared by the international collaboration at ATF2. Concluding remarks have been contributed by Dr. Ewan Paterson, Chair of the International Collaboration Board of the ATF collaboration.

  10. A Cytoplasmic Negative Regulator Isoform of ATF7 Impairs ATF7 and ATF2 Phosphorylation and Transcriptional Activity

    PubMed Central

    Diring, Jessica; Camuzeaux, Barbara; Donzeau, Mariel; Vigneron, Marc; Rosa-Calatrava, Manuel; Kedinger, Claude; Chatton, Bruno

    2011-01-01

    Alternative splicing and post-translational modifications are processes that give rise to the complexity of the proteome. The nuclear ATF7 and ATF2 (activating transcription factor) are structurally homologous leucine zipper transcription factors encoded by distinct genes. Stress and growth factors activate ATF2 and ATF7 mainly via sequential phosphorylation of two conserved threonine residues in their activation domain. Distinct protein kinases, among which mitogen-activated protein kinases (MAPK), phosphorylate ATF2 and ATF7 first on Thr71/Thr53 and next on Thr69/Thr51 residues respectively, resulting in transcriptional activation. Here, we identify and characterize a cytoplasmic alternatively spliced isoform of ATF7. This variant, named ATF7-4, inhibits both ATF2 and ATF7 transcriptional activities by impairing the first phosphorylation event on Thr71/Thr53 residues. ATF7-4 indeed sequesters the Thr53-phosphorylating kinase in the cytoplasm. Upon stimulus-induced phosphorylation, ATF7-4 is poly-ubiquitinated and degraded, enabling the release of the kinase and ATF7/ATF2 activation. Our data therefore conclusively establish that ATF7-4 is an important cytoplasmic negative regulator of ATF7 and ATF2 transcription factors. PMID:21858082

  11. A cytoplasmic negative regulator isoform of ATF7 impairs ATF7 and ATF2 phosphorylation and transcriptional activity.

    PubMed

    Diring, Jessica; Camuzeaux, Barbara; Donzeau, Mariel; Vigneron, Marc; Rosa-Calatrava, Manuel; Kedinger, Claude; Chatton, Bruno

    2011-01-01

    Alternative splicing and post-translational modifications are processes that give rise to the complexity of the proteome. The nuclear ATF7 and ATF2 (activating transcription factor) are structurally homologous leucine zipper transcription factors encoded by distinct genes. Stress and growth factors activate ATF2 and ATF7 mainly via sequential phosphorylation of two conserved threonine residues in their activation domain. Distinct protein kinases, among which mitogen-activated protein kinases (MAPK), phosphorylate ATF2 and ATF7 first on Thr71/Thr53 and next on Thr69/Thr51 residues respectively, resulting in transcriptional activation. Here, we identify and characterize a cytoplasmic alternatively spliced isoform of ATF7. This variant, named ATF7-4, inhibits both ATF2 and ATF7 transcriptional activities by impairing the first phosphorylation event on Thr71/Thr53 residues. ATF7-4 indeed sequesters the Thr53-phosphorylating kinase in the cytoplasm. Upon stimulus-induced phosphorylation, ATF7-4 is poly-ubiquitinated and degraded, enabling the release of the kinase and ATF7/ATF2 activation. Our data therefore conclusively establish that ATF7-4 is an important cytoplasmic negative regulator of ATF7 and ATF2 transcription factors.

  12. Astrometry with the ATF

    NASA Technical Reports Server (NTRS)

    Jefferys, William H.

    1990-01-01

    A detailed study of the effects of gravitational radiation on the relative positions of objects was carried out with the hope that astrometric detection of gravitational radiation might be possible. The results are discouraging. It would appear that narrow-field instruments in the Astrometric Telescope Facility (ATF) class are still several orders of magnitude less accurate than would be required for this very delicate kind of measurement. However, the situation changes considerably when wide-field instruments are considered. An instrument such as POINTS ought to be able to detect gravitational radiation at this level with ease. The list of bright quasars has been augmented. Of particular interest is the finding of quasars near two open clusters and one planetary nebula. These would be useful in determining absolute parallaxes of these objects.

  13. DAMPING THE HIGH ORDER MODES IN THE PUMPING CHAMBER OF THE PEP-II LOW ENERGY RING

    SciTech Connect

    Novokhatski, A

    2004-06-30

    The Low Energy Ring of the PEP-II B-factory operates with extremely high currents of short positron bunches. Any discontinuity in the vacuum chamber can excite a broad-band spectrum of high order modes (HOM). A temperature rise has been found in the vacuum chamber elements in one junction of straight and arc chambers. The power in the wake fields was high enough to char beyond use the feed-through for the titanium sublimation pump (TSP). This pumping section is 5.5 m long and consists of the beam chamber and an ante-chamber. Electromagnetic fields, excited in the beam chamber penetrate to the ante-chamber and then through the heater feed-through come out. To be sure that these electromagnetic fields are present a small ceramic tile with a high loss tangent was placed near the TSP feed-through outside of the pumping chamber. A thermocouple that was attached to this tile showed a strong temperature rise. A short wire antenna was also placed there. The antenna was connected directly to a spectrum analyzer. Measurements show a wide frequency HOM spectrum with a maximum in the 2-3 GHz region. Based on these measurements a special water cooled HOM absorber was designed and installed in the vacuum chamber. As a result, the HOM power in the section decreased and the temperature rise went down. The power loss in the absorber reaches 1200 W for a positron beam current of 2.4 A. The absorber helped to find the source of HOM. Steering the beam on the vertical collimators upstream of the absorber resulted in the significant HOM power change in the absorber.

  14. Elevated cJUN expression and an ATF/CRE site within the ATF3 promoter contribute to activation of ATF3 transcription by the amino acid response.

    PubMed

    Fu, Lingchen; Kilberg, Michael S

    2013-02-15

    Mammalian cells respond to amino acid deprivation through multiple signaling pathways referred to as the amino acid response (AAR). Transcription factors mediate the AAR after their activation by several mechanisms; examples include translational control (activating transcription factor 4, ATF4), phosphorylation (p-cJUN), and transcriptional control (ATF3). ATF4 induces ATF3 transcription through a promoter-localized C/EBP-ATF response element (CARE). The present report characterizes an ATF/CRE site upstream of the CARE that also contributes to AAR-induced ATF3 transcription. ATF4 binds to the ATF/CRE and CARE sequences and both are required for a maximal response to ATF4 induction. ATF3, which antagonizes ATF4 and represses its own gene, also exhibited binding activity to the ATF/CRE and CARE sequences. The AAR resulted in elevated total cJUN and p-cJUN protein levels and both forms exhibited binding activity to the ATF/CRE and CARE ATF3 sequences. Knockdown of AAR-enhanced cJUN expression blocked induction of the ATF3 gene and mutation of either the ATF/CRE or the CARE site prevented the cJUN-dependent increase in ATF3-driven luciferase activity. The results indicate that both increased cJUN and the cis-acting ATF/CRE sequence within the ATF3 promoter contribute to the transcriptional activation of the gene during the AAR.

  15. Elevated cJUN expression and an ATF/CRE site within the ATF3 promoter contribute to activation of ATF3 transcription by the amino acid response

    PubMed Central

    Fu, Lingchen

    2013-01-01

    Mammalian cells respond to amino acid deprivation through multiple signaling pathways referred to as the amino acid response (AAR). Transcription factors mediate the AAR after their activation by several mechanisms; examples include translational control (activating transcription factor 4, ATF4), phosphorylation (p-cJUN), and transcriptional control (ATF3). ATF4 induces ATF3 transcription through a promoter-localized C/EBP-ATF response element (CARE). The present report characterizes an ATF/CRE site upstream of the CARE that also contributes to AAR-induced ATF3 transcription. ATF4 binds to the ATF/CRE and CARE sequences and both are required for a maximal response to ATF4 induction. ATF3, which antagonizes ATF4 and represses its own gene, also exhibited binding activity to the ATF/CRE and CARE sequences. The AAR resulted in elevated total cJUN and p-cJUN protein levels and both forms exhibited binding activity to the ATF/CRE and CARE ATF3 sequences. Knockdown of AAR-enhanced cJUN expression blocked induction of the ATF3 gene and mutation of either the ATF/CRE or the CARE site prevented the cJUN-dependent increase in ATF3-driven luciferase activity. The results indicate that both increased cJUN and the cis-acting ATF/CRE sequence within the ATF3 promoter contribute to the transcriptional activation of the gene during the AAR. PMID:23269699

  16. ATF3 — EDRN Public Portal

    Cancer.gov

    ATF3 is a member of the the mammalian activation transcription factor/cAMP responsive element-binding (CREB) protein family of transcription factors. The ATF3 protein binds the cAMP response element (CRE) (consensus: 5'-GTGACGT[AC][AG]-3'), a sequence present in many viral and cellular promoters. the ATF3 gene is induced by many signals that are also involved in cancer cell signaling. ATF3 represses transcription from promoters with ATF sites. Several transcript variants encoding multiple isoforms have been found. It is thought that alternative splicing of this gene may be involved in the regulation of target genes.

  17. BNL ATF II beamlines design

    SciTech Connect

    Fedurin, M.; Jing, Y.; Stratakis, D.; Swinson, C.

    2015-05-03

    The Brookhaven National Laboratory. Accelerator Test Facility (BNL ATF) is currently undergoing a major upgrade (ATF-II). Together with a new location and much improved facilities, the ATF will see an upgrade in its major capabilities: electron beam energy and quality and CO2 laser power. The electron beam energy will be increased in stages, first to 100-150 MeV followed by a further increase to 500 MeV. Combined with the planned increase in CO2 laser power (from 1-100 TW), the ATF-II will be a powerful tool for Advanced Accelerator research. A high-brightness electron beam, produced by a photocathode gun, will be accelerated and optionally delivered to multiple beamlines. Besides the energy range (up to a possible 500 MeV in the final stage) the electron beam can be tailored to each experiment with options such as: small transverse beam size (<10 um), short bunch length (<100 fsec) and, combined short and small bunch options. This report gives a detailed overview of the ATFII capabilities and beamlines configuration.

  18. Damped flexible seal

    SciTech Connect

    DuBois, Neil J.; Amaral, Antonio M.

    1992-10-27

    A damped flexible seal assembly for a torpedo isolates the tailcone thereof rom vibrational energy present in the drive shaft assembly. A pair of outside flanges, each of which include an inwardly facing groove and an O-ring constrained therein, provide a watertight seal against the outer non-rotating surface of the drive shaft assembly. An inside flange includes an outwardly-facing groove and an O-ring constrained therein, and provides a watertight seal against the inner surface of the tail cone. Two cast-in-place elastomeric seals provide a watertight seal between the flanges and further provide a damping barrier between the outside flanges and the inside flanges for damping vibrational energy present in the drive shaft assembly before the energy can reach the tailcone through the seal assembly.

  19. Quadratic Damping

    ERIC Educational Resources Information Center

    Fay, Temple H.

    2012-01-01

    Quadratic friction involves a discontinuous damping term in equations of motion in order that the frictional force always opposes the direction of the motion. Perhaps for this reason this topic is usually omitted from beginning texts in differential equations and physics. However, quadratic damping is more realistic than viscous damping in many…

  20. Quadratic Damping

    ERIC Educational Resources Information Center

    Fay, Temple H.

    2012-01-01

    Quadratic friction involves a discontinuous damping term in equations of motion in order that the frictional force always opposes the direction of the motion. Perhaps for this reason this topic is usually omitted from beginning texts in differential equations and physics. However, quadratic damping is more realistic than viscous damping in many…

  1. Pellet injection into ATF plasmas

    SciTech Connect

    Wilgen, J.B.; Bell, J.D.; England, A.C.; Fisher, P.W.; Howe, H.C.; Murakami, M.; Rasmussen, D.A.; Richards, R.K.; Uckan, T.; Wing, W.R. ); Bell, G.L. ); Qualls, A.L. ); Sudo, S. )

    1990-01-01

    Based on the favorable empirical scaling of stellarator confinement with increasing electron density, pellet fueling is expected to result in significant performance improvement of the ATF plasma. With gas-puff fueling, NBI heated plasmas in ATF are limited by a thermal collapse. Pellet fueling provides a potential means to delay this effect and gain access to the favorable high density confinement regime. To provide flexibility for optimization and physics studies, eight different pellet sizes are available. To date, line average densities of up to 4 {times} 10{sup 13} cm{sup {minus}3} have been achieved with a single pellet injected into a 0.7 MW NBI plasma at 0.95 T; the results from optimization studies with up to 1.5 MW of NBI power at 2 T will be presented.

  2. Damping device for a stationary labyrinth seal

    NASA Technical Reports Server (NTRS)

    El-Aini, Yehia M. (Inventor); Mitchell, William S. (Inventor); Roberts, Lawrence P. (Inventor); Montgomery, Stuart K. (Inventor); Davis, Gary A. (Inventor)

    2010-01-01

    A stationary labyrinth seal system includes a seal housing having an annular cavity, a plurality of damping devices, and a retaining ring. The damping devices are positioned within the annular cavity and are maintained within the annular cavity by the retaining ring.

  3. Landau damping

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2010-10-01

    Section 2.5.8 of the Handbook of Accelerator Physics and Engineering on Landau damping is rewritten. An solvable example is first given to demonstrate the interplay between Landau damping and decoherence. This example is an actual one when the beam oscillatory motion is driven by a wake force. The dispersion relation is derived and its implication on Landau damping is illustrated. The rest of the article touches on the Landau damping of transverse and longitudinal beam oscillations. The stability criteria are given for a bunched beam and the changes of the criteria when the beam is lengthened and becomes unbunched.

  4. Chondrocytic Atf4 regulates osteoblast differentiation and function via Ihh

    PubMed Central

    Wang, Weiguang; Lian, Na; Ma, Yun; Li, Lingzhen; Gallant, Richard C.; Elefteriou, Florent; Yang, Xiangli

    2012-01-01

    Atf4 is a leucine zipper-containing transcription factor that activates osteocalcin (Ocn) in osteoblasts and indian hedgehog (Ihh) in chondrocytes. The relative contribution of Atf4 in chondrocytes and osteoblasts to the regulation of skeletal development and bone formation is poorly understood. Investigations of the Atf4–/–;Col2a1-Atf4 mouse model, in which Atf4 is selectively overexpressed in chondrocytes in an Atf4-null background, demonstrate that chondrocyte-derived Atf4 regulates osteogenesis during development and bone remodeling postnatally. Atf4 overexpression in chondrocytes of the Atf4–/–;Col2a1-Atf4 double mutants corrects the reduction in stature and limb in Atf4–/– embryos and rectifies the decrease in Ihh expression, Hh signaling, proliferation and accelerated hypertrophy that characterize the Atf4–/– developing growth plate cartilages. Unexpectedly, this genetic manipulation also restores the expression of osteoblastic marker genes, namely Ocn and bone sialoprotein, in Atf4–/– developing bones. In Atf4–/–;Col2a1-Atf4 adult mice, all the defective bone parameters found in Atf4–/– mice, including bone volume, trabecular number and thickness, and bone formation rate, are rescued. In addition, the conditioned media of ex vivo cultures from wild-type or Atf4–/–;Col2a1-Atf4, but not Atf4–/– cartilage, corrects the differentiation defects of Atf4–/– bone marrow stromal cells and Ihh-blocking antibody eliminates this effect. Together, these data indicate that Atf4 in chondrocytes is required for normal Ihh expression and for its paracrine effect on osteoblast differentiation. Therefore, the cell-autonomous role of Atf4 in chondrocytes dominates the role of Atf4 in osteoblasts during development for the control of early osteogenesis and skeletal growth. PMID:22190639

  5. Coulomb Damping

    ERIC Educational Resources Information Center

    Fay, Temple H.

    2012-01-01

    Viscous damping is commonly discussed in beginning differential equations and physics texts but dry friction or Coulomb friction is not despite dry friction being encountered in many physical applications. One reason for avoiding this topic is that the equations involve a jump discontinuity in the damping term. In this article, we adopt an energy…

  6. Coulomb Damping

    ERIC Educational Resources Information Center

    Fay, Temple H.

    2012-01-01

    Viscous damping is commonly discussed in beginning differential equations and physics texts but dry friction or Coulomb friction is not despite dry friction being encountered in many physical applications. One reason for avoiding this topic is that the equations involve a jump discontinuity in the damping term. In this article, we adopt an energy…

  7. Status of the ATF2 Lattices

    SciTech Connect

    Marin, E.; Tomas, R.; Bambade, P.; Okugi, T.; Tauchi, T.; Terunuma, N.; Urakawa, J.; Seryi, A.; White, G.; Woodley, M.; /SLAC

    2011-12-09

    The current status for the ATF2 Nominal and Ultra-low {beta}* lattices are presented in this paper. New lattice designs have been obtained in order to minimise the impact of the last interpretation of multipole measurements that have been included into the model. However, the new ATF2 Ultra-low design is not able to recover the expected vertical beam size at the IP with the current magnet distribution. Therefore, different quadrupole sorting have been studied. A significant gain is evident for the ATF2 Ultra-low lattice when sorting the magnets according to the skew-sextupolar components. The ATF2 Nominal lattice is also expected to benefit from the new sorting. Tuning results of the new ATF2 Ultra-low lattice under realistic imperfections are also reported.

  8. Initial Studies of Nonlinear Dynamics in the KEK-ATF Wigglers

    SciTech Connect

    Wolski, A.

    2005-02-28

    The nonlinear fields in insertion devices can have a significant impact on the beam dynamics in storage rings. Various tools have been developed which allow the dynamical effects of a wiggler to be predicted, based on a detailed model of the magnetic field. The wigglers in the KEK-ATF have recently been commissioned, and provide an opportunity for benchmarking some of the analysis tools. We report on initial studies of the nonlinear effects of the KEK-ATF wigglers, based on studies of the change in betatron tunes with change in orbit through the wigglers, and compare the results with the predictions based on detailed field models.

  9. Copurification of casein kinase II with transcription factor ATF/E4TF3.

    PubMed Central

    Wada, T; Takagi, T; Yamaguchi, Y; Kawase, H; Hiramoto, M; Ferdous, A; Takayama, M; Lee, K A; Hurst, H C; Handa, H

    1996-01-01

    We have developed a simple method to purify sequence-specific DNA-binding proteins directly from crude cell extracts by using DNA affinity latex beads. The method enabled us to purify not only DNA-binding proteins, but also their associated proteins. Using beads bearing the ATF/E4TF3 site from the adenovirus E4 gene promoter, a protein kinase activity was copurified with the ATF/E4TF3 family. We found that the kinase interacted with ATF1 in vitro efficiently. The kinase did not bind directly to DNA. The kinase mainly phosphorylated ATF1 on serine 36, which was one of target amino acids for casein kinase (CK) II. Biological features of the kinase were the same as those of CKII and an anti-CKII serum reacted with the kinase, indicating that the kinase was CKII. Moreover, it was clearly shown that one of CKII subunits, the CKII alpha protein bound to glutathione-S-transferase (GST) fusion ATF1 but not GST in vitro. It has been reported that a specific CKII inhibitor, 5,6-dichloro-1-beta-D-ribo-furanosylbenzimidazole (DRB) inhibits transcription by RNA polymerase II [Zandomeni et al., (1986) J. Biol. Chem. 261, 3414-3419]. Taken together, these results suggest that ATF/E4TF3 may recruit the CKII activity to a transcription initiation machinery and stimulate transcription. PMID:8600455

  10. The Straightness Monitor System at ATF2

    SciTech Connect

    Hildreth, Michael; Aryshev, Alexander; Boogert, Stewart; Honda, Yosuke; Tauchi, Toshiaki; Terunuma, Nobuhiro; White, Glen; /SLAC

    2012-07-06

    The demonstration of absolute stability of the position of the focused beam is the primary goal of the ATF2 commissioning effort. We have installed a laser interferometer system that will eventually correct the measurement of high-precision Beam Position Monitors used in the ATF2Final Focus Steering Feedback for mechanical motion or vibrations. Here, we describe the installed system and present preliminary data on the short- and long-term mechanical stability of the BPM system.

  11. Advanced Thermal control Flight Experiment (ATFE)

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A comprehensive description of the design and performance of the Advanced Thermal Control Flight Experiment (ATFE) is presented. The ATFE studied in a space environment for five years the steady state, transient ground and flight performance of (1) a thermal diode heat pipe, (2) a phase change material, and (3) a feedback controlled variable conductance heat pipe. It was found that all were flight worthy and highly reliable.

  12. Expression Levels of the Yeast Alcohol Acetyltransferase Genes ATF1, Lg-ATF1, and ATF2 Control the Formation of a Broad Range of Volatile Esters

    PubMed Central

    Verstrepen, Kevin J.; Van Laere, Stijn D. M.; Vanderhaegen, Bart M. P.; Derdelinckx, Guy; Dufour, Jean-Pierre; Pretorius, Isak S.; Winderickx, Joris; Thevelein, Johan M.; Delvaux, Freddy R.

    2003-01-01

    Volatile aroma-active esters are responsible for the fruity character of fermented alcoholic beverages such as beer and wine. Esters are produced by fermenting yeast cells in an enzyme-catalyzed intracellular reaction. In order to investigate and compare the roles of the known Saccharomyces cerevisiae alcohol acetyltransferases, Atf1p, Atf2p and Lg-Atf1p, in volatile ester production, the respective genes were either deleted or overexpressed in a laboratory strain and a commercial brewing strain. Subsequently, the ester formation of the transformants was monitored by headspace gas chromatography and gas chromatography combined with mass spectroscopy (GC-MS). Analysis of the fermentation products confirmed that the expression levels of ATF1 and ATF2 greatly affect the production of ethyl acetate and isoamyl acetate. GC-MS analysis revealed that Atf1p and Atf2p are also responsible for the formation of a broad range of less volatile esters, such as propyl acetate, isobutyl acetate, pentyl acetate, hexyl acetate, heptyl acetate, octyl acetate, and phenyl ethyl acetate. With respect to the esters analyzed in this study, Atf2p seemed to play only a minor role compared to Atf1p. The atfatf2Δ double deletion strain did not form any isoamyl acetate, showing that together, Atf1p and Atf2p are responsible for the total cellular isoamyl alcohol acetyltransferase activity. However, the double deletion strain still produced considerable amounts of certain other esters, such as ethyl acetate (50% of the wild-type strain), propyl acetate (50%), and isobutyl acetate (40%), which provides evidence for the existence of additional, as-yet-unknown ester synthases in the yeast proteome. Interestingly, overexpression of different alleles of ATF1 and ATF2 led to different ester production rates, indicating that differences in the aroma profiles of yeast strains may be partially due to mutations in their ATF genes. PMID:12957907

  13. ATF3 inhibits PPARγ-stimulated transactivation in adipocyte cells

    SciTech Connect

    Jang, Min-Kyung; Jung, Myeong Ho

    2015-01-02

    Highlights: • ATF3 inhibits PPARγ-stimulated transcriptional activation. • ATF3 interacts with PPARγ. • ATF3 suppresses p300-mediated transcriptional coactivation. • ATF3 decreases the binding of PPARγ and recruitment of p300 to PPRE. - Abstract: Previously, we reported that activating transcription factor 3 (ATF3) downregulates peroxisome proliferator activated receptor (PPARγ) gene expression and inhibits adipocyte differentiation in 3T3-L1 cells. Here, we investigated another role of ATF3 on the regulation of PPARγ activity. ATF3 inhibited PPARγ-stimulated transactivation of PPARγ responsive element (PPRE)-containing reporter or GAL4/PPARγ chimeric reporter. Thus, ATF3 effectively repressed rosiglitazone-stimulated expression of adipocyte fatty acid binding protein (aP2), PPARγ target gene, in 3T3-L1 cells. Coimmunoprecipitation and GST pulldown assay demonstrated that ATF3 interacted with PPARγ. Accordingly, ATF3 prevented PPARγ from binding to PPRE on the aP2 promoter. Furthermore, ATF3 suppressed p300-mediated transcriptional coactivation of PPRE-containing reporter. Chromatin immunoprecipitation assay showed that overexpression of ATF3 blocked both binding of PPARγ and recruitment of p300 to PPRE on aP2 promoter induced by rosiglitazone treatment in 3T3-L1 cells. Taken together, these results suggest that ATF3 interacts with PPARγ and represses PPARγ-mediated transactivation through suppression of p300-stimulated coactivation in 3T3-L1 cells, which may play a role in inhibition of adipocyte differentiation.

  14. Viscosity in Saturn's rings

    NASA Technical Reports Server (NTRS)

    Lissauer, J. J.; Shu, F. H.; Cuzzi, J. N.

    1982-01-01

    The technique of estimating the viscosity in Saturn's rings from the damping rate of waves observed to be propagating within the rings is discussed. The wavetrains of attempts using spiral density waves as a diagnostic suffer significant complications that compromise the interpretations. A method that considers the damping of spiral bending waves was used to deduce a kinematic viscosity of 260 (+150, -100) sqcm/sec for the middle of the A ring where bending waves are excited by the 5:3 vertical resonance with Mimas. This value implies upper limits on the particle velocity dispersion and local ring thickness of 0.4 cm/sec and 30 m, respectively.

  15. ATF3 represses PPARγ expression and inhibits adipocyte differentiation

    SciTech Connect

    Jang, Min-Kyung; Jung, Myeong Ho

    2014-11-07

    Highlights: • ATF3 decrease the expression of PPARγ and its target gene in 3T3-L1 adipocytes. • ATF3 represses the promoter activity of PPARγ2 gene. • ATF/CRE (−1537/−1530) is critical for ATF3-mediated downregulation of PPARγ. • ATF3 binds to the promoter region containing the ATF/CRE. • ER stress inhibits adipocyte differentiation through downregulation of PPARγ by ATF3. - Abstract: Activating transcription factor 3 (ATF3) is a stress-adaptive transcription factor that mediates cellular stress response signaling. We previously reported that ATF3 represses CCAAT/enhancer binding protein α (C/EBPα) expression and inhibits 3T3-L1 adipocyte differentiation. In this study, we explored potential role of ATF3 in negatively regulating peroxisome proliferator activated receptor-γ (PPARγ). ATF3 decreased the expression of PPARγ and its target gene in 3T3-L1 adipocytes. ATF3 also repressed the activity of −2.6 Kb promoter of mouse PPARγ2. Overexpression of PPARγ significantly prevented the ATF3-mediated inhibition of 3T3-L1 differentiation. Transfection studies with 5′ deleted-reporters showed that ATF3 repressed the activity of −2037 bp promoter, whereas it did not affect the activity of −1458 bp promoter, suggesting that ATF3 responsive element is located between the −2037 and −1458. An electrophoretic mobility shift assay and chromatin immunoprecipitation assay demonstrated that ATF3 binds to ATF/CRE site (5′-TGACGTTT-3′) between −1537 and −1530. Mutation of the ATF/CRE site abrogated ATF3-mediated transrepression of the PPARγ2 promoter. Treatment with thapsigargin, endoplasmic reticulum (ER) stress inducer, increased ATF3 expression, whereas it decreased PPARγ expression. ATF3 knockdown significantly blocked the thapsigargin-mediated downregulation of PPARγ expression. Furthermore, overexpression of PPARγ prevented inhibition of 3T3-L1 differentiation by thapsigargin. Collectively, these results suggest that ATF3-mediated

  16. Automatic emittance measurement at the ATF

    SciTech Connect

    Wang, X.J.; Malone, R.; Batchelor, K.; Ben-Zvi, I.

    1993-07-01

    An automatic emittance measurement system to characterize the transverse emittance of the electron beam produced by the BNL photocathode electron gun is described. The system utilize a VAX workstation and a Spiricon beam analyzer. A operator window (created through the Vista control software package) controls the emittance measurement system and the graphic presentation of the results. Quadrupole variation method is used for the ATF automatic emittance measurement system. A simple emittance formula was derived to study the performance of the quadrupole variation method, and compared with the ATF experimental data is also presented.

  17. Fission yeast ATF/CREB family protein Atf21 plays important roles in production of normal spores.

    PubMed

    Morita, Tomohiko; Yamada, Takatomi; Yamada, Shintaro; Matsumoto, Kouji; Ohta, Kunihiro

    2011-02-01

    Activating transcription factor/cAMP response element binding protein (ATF/CREB) family transcription factors play central roles in maintaining cellular homeostasis. They are activated in response to environmental stimuli, bind to CRE sequences in the promoters of stress-response genes and regulate transcription. Although ATF/CREB proteins are widely conserved among most eukaryotes, their characteristics are highly diverse. Here, we investigated the functions of a fission yeast ATF/CREB protein Atf21 to find out its unique properties. We show that Atf21 is dispensable for the adaptive response to several stresses such as nitrogen starvation and for meiotic events including nuclear divisions. However, spores derived from atf21Δ mutants are not as mature as wild-type ones and are unable to form colonies under nutrition-rich conditions. Furthermore, we demonstrate that the Atf21 protein, which is scarce in early meiosis, gradually accumulates as meiosis proceeds; it reaches maximum levels approximately 8 h after nitrogen starvation and is present during germination. These results suggest that Atf21 is expressed and functions long after nitrogen starvation. Given that other well-characterized fission yeast ATF/CREB proteins Atf1 and Pcr1 accumulate and function promptly upon exposure to environmental stresses, we propose that Atf21 is a distinct member of the ATF/CREB family in fission yeast. © 2010 The Authors. Journal compilation © 2010 by the Molecular Biology Society of Japan/Blackwell Publishing Ltd.

  18. The transcription factor ATF-3 promotes neurite outgrowth.

    PubMed

    Seijffers, Rhona; Allchorne, Andrew J; Woolf, Clifford J

    2006-01-01

    Dorsal root ganglion (DRG) neurons regenerate after a peripheral nerve injury but not after injury to their axons in the spinal cord. A key question is which transcription factors drive the changes in gene expression that increase the intrinsic growth state of peripherally injured sensory neurons? A prime candidate is activating transcription factor-3 (ATF-3), a transcription factor that we find is induced in all DRG neurons after peripheral, but not central axonal injury. Moreover, we show in adult DRG neurons that a preconditioning peripheral, but not central axonal injury, increases their growth, correlating closely with the pattern of ATF-3 induction. Using viral vectors, we delivered ATF-3 to cultured adult DRG neurons and find that ATF-3 enhances neurite outgrowth. Furthermore, ATF-3 promotes long sparsely branched neurites. ATF-3 overexpression did not increase c-Jun expression. ATF-3 may contribute, therefore, to neurite outgrowth by orchestrating the gene expression responses in injured neurons.

  19. Association analysis of ATF4 and ATF5, genes for interacting-proteins of DISC1, in bipolar disorder.

    PubMed

    Kakiuchi, Chihiro; Ishiwata, Mizuho; Nanko, Shinichiro; Kunugi, Hiroshi; Minabe, Yoshio; Nakamura, Kazuhiko; Mori, Norio; Fujii, Kumiko; Yamada, Kazuo; Yoshikawa, Takeo; Kato, Tadafumi

    2007-05-07

    Disrupted in schizophrenia 1 (DISC1) and its molecular cascade are implicated in the pathophysiology of schizophrenia and bipolar disorder. As interacting-proteins with DISC1, Nudel, ATF4, ATF5, LIS1, alpha-tubulin, PDE4B, eIF3, FEZ1, Kendrin, MAP1A and MIPT3 were identified. We previously showed the down-regulation of ATF5 in the lymphoblastoid cells derived from affected co-twin of monozygotic twins discordant for bipolar disorder. We also suggested the contribution of endoplasmic reticulum stress response pathway to the illness, and ATF4 is one of major components in the pathway. Truncated mutant DISC1 reportedly cannot interact with ATF4 and ATF5. These findings suggest the role of these genes in the pathophysiology of bipolar disorder. In this study, we tested genetic association of ATF4 and ATF5 genes with bipolar disorder by a case-control study in Japanese population (438 patients and 532 controls) and transmission disequilibrium test in 237 trio samples from NIMH Genetics Initiative Pedigrees. We also performed gene expression analysis in lymphoblastoid cells. We did not find any significant association in both genetic study and expression analysis. By the exploratory haplotype analysis, nominal association of ATF4 with bipolar II patients was observed, but it was not significant after correction of multiple testing. Contribution of common variations of ATF4 and ATF5 to the pathophysiology of bipolar disorder may be minimal if any.

  20. ATF3 deficiency in chondrocytes alleviates osteoarthritis development.

    PubMed

    Iezaki, Takashi; Ozaki, Kakeru; Fukasawa, Kazuya; Inoue, Makoto; Kitajima, Shigetaka; Muneta, Takeshi; Takeda, Shu; Fujita, Hiroyuki; Onishi, Yuki; Horie, Tetsuhiro; Yoneda, Yukio; Takarada, Takeshi; Hinoi, Eiichi

    2016-08-01

    Activating transcription factor 3 (Atf3) has been implicated in the pathogenesis of various diseases, including cancer and inflammation, as well as in the regulation of cell proliferation and differentiation. However, the involvement of Atf3 in developmental skeletogenesis and joint disease has not been well studied to date. Here, we show that Atf3 is a critical mediator of osteoarthritis (OA) development through its expression in chondrocytes. ATF3 expression was markedly up-regulated in the OA cartilage of both mice and humans. Conditional deletion of Atf3 in chondrocytes did not result in skeletal abnormalities or affect the chondrogenesis, but alleviated the development of OA generated by surgically inducing knee joint instability in mice. Inflammatory cytokines significantly up-regulated Atf3 expression through the nuclear factor-kB (NF-kB) pathway, while cytokine-induced interleukin-6 (Il6) expression was repressed, in ATF3-deleted murine and human chondrocytes. Mechanistically, Atf3 deficiency decreased cytokine-induced Il6 transcription in chondrocytes through repressing NF-kB signalling by the attenuation of the phosphorylation status of IkB and p65. These findings suggest that Atf3 is implicated in the pathogenesis of OA through modulation of inflammatory cytokine expression in chondrocytes, and the feed-forward loop of inflammatory cytokines/NF-kB/Atf3 in chondrocytes may be a novel therapeutic target for the treatment for OA. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

  1. Reduced levels of ATF-2 predispose mice to mammary tumors.

    PubMed

    Maekawa, Toshio; Shinagawa, Toshie; Sano, Yuji; Sakuma, Takahiko; Nomura, Shintaro; Nagasaki, Koichi; Miki, Yoshio; Saito-Ohara, Fumiko; Inazawa, Johji; Kohno, Takashi; Yokota, Jun; Ishii, Shunsuke

    2007-03-01

    Transcription factor ATF-2 is a nuclear target of stress-activated protein kinases, such as p38, which are activated by various extracellular stresses, including UV light. Here, we show that ATF-2 plays a critical role in hypoxia- and high-cell-density-induced apoptosis and the development of mammary tumors. Compared to wild-type cells, Atf-2(-/-) mouse embryonic fibroblasts (MEFs) were more resistant to hypoxia- and anisomycin-induced apoptosis but remained equally susceptible to other stresses, including UV. Atf-2(-/-) and Atf-2(+/-) MEFs could not express a group of genes, such as Gadd45alpha, whose overexpression can induce apoptosis, in response to hypoxia. Atf-2(-/-) MEFs also had a higher saturation density than wild-type cells and expressed lower levels of Maspin, the breast cancer tumor suppressor, which is also known to enhance cellular sensitivity to apoptotic stimuli. Atf-2(-/-) MEFs underwent a lower degree of apoptosis at high cell density than wild-type cells. Atf-2(+/-) mice were highly prone to mammary tumors that expressed reduced levels of Gadd45alpha and Maspin. The ATF-2 mRNA levels in human breast cancers were lower than those in normal breast tissue. Thus, ATF-2 acts as a tumor susceptibility gene of mammary tumors, at least partly, by activating a group of target genes, including Maspin and Gadd45alpha.

  2. A Superconducting Magnet Upgrade of the ATF2 Final Focus

    SciTech Connect

    Parker B.; Anerella M.; Escallier J.; He P.; Jain A.; Marone A.; Wanderer P.; Wu K.C.; Hauviller C.; Marin E.; Tomas R.; Zimmermann F.; Bolzon B.; Jeremie A.; Kimura N.; Kubo K.; Kume T.; Kuroda S.; Okugi T.; Tauchi T.; Terunuma N.; Tomaru T.; Tsuchiya K.; Urakawa J.; Yamamoto A.; Bambabe P.; Coe P.; Urner D.; Seryi A.; Spencer C.; White G.

    2010-05-23

    The ATF2 facility at KEK is a proving ground for linear collider technology with a well instrumented extracted beam line and Final Focus (FF). The primary ATF2 goal is to demonstrate the extreme beam demagnification and spot stability needed for a linear collider FF. But the ATF2 FF uses water cooled magnets and the ILC baseline has a superconducting (SC) FF. We plan to upgrade ATF2 and replace some of the warm FF magnets with SC FF magnets. The ATF2 SC magnets, like the ILC FF, will made via direct wind construction. ATF2 coil winding is in progress at BNL and warm magnetic measurements indicate we have achieved good field quality. Studies indicate that having ATF2 FF magnets with larger aperture and better field quality should allow reducing the ATF2 FF beta function for study of focusing regimes relevant to CLIC. The ATF2 magnet cryostat will have laser view ports for directly monitoring cold mass movement. We plan to make stability measurements at BNL and KEK to relate ATF2 FF magnet performance to that of a full length ILC QD0 R and D FF prototype under construction at BNL.

  3. A Superconducting Magnet Upgrade of the ATF2 Final Focus

    SciTech Connect

    Parker, Brett; Anerella, Michael; Escallier, John; He, Ping; Jain, Animesh; Marone, Andrew; Wanderer, Peter; Wu, Kuo-Chen; Bambade, Philip; Bolzon, Benoit; Jeremie, Andrea; Coe, Paul; Urner, David Hauviller, Claude; Marin, Eduardo; Tomas, Rogelio; Zimmermann, Frank; Kimura, Nobuhiro; Kubo, Kiyoshi; Kume, Tatsuya Kuroda, Shigeru; /KEK, Tsukuba /KEK, Tsukuba /KEK, Tsukuba /KEK, Tsukuba /KEK, Tsukuba /KEK, Tsukuba /KEK, Tsukuba /KEK, Tsukuba /SLAC /SLAC /SLAC

    2012-07-05

    The ATF2 facility at KEK is a proving ground for linear collider technology with a well instrumented extracted beam line and Final Focus (FF). The primary ATF2 goal is to demonstrate the extreme beam demagnification and spot stability needed for a linear collider FF. But the ATF2 FF uses water cooled magnets and the ILC baseline has a superconducting (SC) FF. We plan to upgrade ATF2 and replace some of the warm FF magnets with SC FF magnets. The ATF2 SC magnets, like the ILC FF, will made via direct wind construction. ATF2 coil winding is in progress at BNL and warm magnetic measurements indicate we have achieved good field quality. Studies indicate that having ATF2 FF magnets with larger aperture and better field quality should allow reducing the ATF2 FF beta function for study of focusing regimes relevant to CLIC. The ATF2 magnet cryostat will have laser view ports for directly monitoring cold mass movement. We plan to make stability measurements at BNL and KEK to relate ATF2 FF magnet performance to that of a full length ILC QD0 R&D FF prototype under construction at BNL.

  4. Measurement of damping of graphite epoxy materials

    NASA Technical Reports Server (NTRS)

    Crocker, M. J.

    1985-01-01

    Work on a damping measurement test apparatus is discussed. The device is designed to excite tube specimens in a vacuum chamber. Also some experiments were conducted on a tube specimen to confirm previously reported results. A table of data showing the results of forced vibration tests using a half ring and a free-free boundary is given. The main purpose was to study the effect of the frequency resolution on the damping ratio measurements.

  5. ATF (Advanced Toroidal Facility)-2 studies

    SciTech Connect

    Lyon, J.F.; Carreras, B.A.; Dominguez, N.; Dresner, L.; Hedrick, C.L.; Hirshman, S.P.; Lubell, M.S.; Lue, J.W.; Morris, R.N.; Painter, S.L.; Rome, J.A.; van Rij, W.I.

    1989-10-01

    Design studies for a low-aspect-ratio, large next-generation stellarator, ATF-II, with high-current-density, high-field, stable NbTi/Cu helical windings are described. The design parameters are an average plasma radius of 0.52 m, a major radius of 2 m, and a field on axis of 4-5 T, with 10 to 15 MW of heating power. Such a device would be comparable in scope to other next-generation stellarators but would have roughly the same aspect ratio as the tokamaks without, however, the need for current drive to sustain steady-state operation. A number of low-aspect-ratio physics issues need to be addressed in the design of ATF-II, primarily compromises between high-beta capability and good confinement properties. A six-field-period Compact Torsatron is chosen as a reference design for ATF-II, and its main features and performance predictions are discussed. An integrated (beta capability and confinement) optimization approach and optimization of superconducting windings are also discussed. 36 refs., 13 figs., 2 tabs.

  6. Multi Bunch Gmma Ray Generation Experiment at ATF

    NASA Astrophysics Data System (ADS)

    Takahashi, Tohru

    2013-10-01

    We construct a new detector to monitor γ yields in bunch by bunch basis for the Laser Compton experiment at the KEK ATF which is capable to separate γ rays in 5.6ns spacing multi-bunch operation of the KEK ATF. In this article we report a result of measurement of multi bunch γ ray detection for the first time at the KEK ATF.

  7. Normoxic destabilization of ATF-4 depends on proteasomal degradation.

    PubMed

    Wottawa, M; Köditz, J; Katschinski, D M

    2010-04-01

    Hypoxia-inducible gene expression is an important physiological adaptive mechanism in response to a decreased oxygen supply. We have recently described an oxygen- and prolyl-4-hydroxylase (PHD)3-dependent stabilization of the activating transcription factor 4 (ATF-4). The aim of the present study was to examine if the normoxic destabilization of ATF-4 is regulated by oxygen-dependent proteasomal degradation. We determined poly-ubiquitination of ATF-4 in normoxia compared to hypoxia by immunoprecipitation and immunoblots. Furthermore, we analysed the expression of the ATF-4 target gene GADD153 as a function of oxygen concentration. ATF-4 protein levels were not detectable in normoxia. Normoxic degradation correlated with an oxygen-dependent poly-ubiquitination of ATF-4, which was hindered by hypoxic incubation of the cells. As a result of hypoxia, GADD153 was expressed. The hypoxic GADD153 expression was attenuated or increased by transfecting the cells with ATF-4 siRNA or PHD3 siRNA respectively. Our results demonstrate the involvement of oxygen-dependent proteasomal degradation of ATF-4 in the hypoxia-induced expression of GADD153. Taken together, hypoxia/PHD3-regulated stabilization of ATF-4 by hindering oxygen-dependent degradation may play a critical role in linking cell fate decisions to oxygen availability.

  8. ATF-2 regulates lipopolysaccharide-induced transcription in macrophage cells.

    PubMed

    Hirose, Noriyuki; Maekawa, Toshio; Shinagawa, Toshie; Ishii, Shunsuke

    2009-07-17

    The transcription factor ATF-2, a member of the ATF/CREB family, is a target of p38 that are involved in stress-induced apoptosis and in Toll-like receptor (TLR)-mediated signaling. Phosphorylation of ATF-2 at Thr-71 was enhanced by treating of RAW264.7 macrophage cells with either LPS, MALP-2, or CpG-ODN. LPS treatment enhanced the trans-activation capacity of ATF-2. Among multiple LPS-induced genes, the LPS-induced expression of Socs-3 was significantly reduced by the treatment of RAW264.7 cells with an Atf-2 siRNA. Transcription from the Socs-3 promoter was synergistically stimulated by ATF-2 and LPS, whereas it was suppressed by Atf-2 siRNA. Histone deacetylase 1 (HDAC1) interacted with ATF-2 after LPS treatment, but not before treatment. Treatment of RAW264.7 cells with trichostatin A, an inhibitor of HDAC, suppressed the LPS-induced Socs-3 expression, suggesting that HDAC1 positively regulates the LPS-induced transcription of Socs-3. Thus, ATF-2 plays an important role in TLR-mediated transcriptional control in macrophage cells.

  9. Ringing wormholes

    SciTech Connect

    Konoplya, R.A.; Molina, C.

    2005-06-15

    We investigate the response of traversable wormholes to external perturbations through finding their characteristic frequencies and time-domain profiles. The considered solution describes traversable wormholes between the branes in the two brane Randall-Sundrum model and was previously found within Einstein gravity with a conformally coupled scalar field. The evolution of perturbations of a wormhole is similar to that of a black hole and represents damped oscillations (ringing) at intermediately late times, which are suppressed by power-law tails (proportional to t{sup -2} for monopole perturbations) at asymptotically late times.

  10. Next generation HOM-damping

    NASA Astrophysics Data System (ADS)

    Marhauser, Frank

    2017-06-01

    can push the envelope towards quasi HOM-free operation suited for next generation storage and collider rings. Geometrical end-cell shape alterations for the five-cell cavity with already efficient mode damping are discussed as a possibility to further lower specific high impedance modes. The findings are eventually put into relation with demanding impedance instability thresholds in future collider rings.

  11. Next generation HOM-damping

    DOE PAGES

    Marhauser, Frank

    2017-05-15

    since it can push the envelope towards quasi HOM-free operation suited for next generation storage and collider rings. Geometrical end-cell shape alterations for the five-cell cavity with already efficient mode damping are discussed as a possibility to further lower specific high impedance modes. Lastly, the findings are eventually put into relation with demanding impedance instability thresholds in future collider rings.« less

  12. CREB1/ATF1 Activation in Photoreceptor Degeneration and Protection

    PubMed Central

    Beltran, William A.; Allore, Heather G.; Johnson, Elizabeth; Towle, Virginia; Tao, Weng; Acland, Gregory M.; Aguirre, Gustavo D.

    2009-01-01

    Purpose. The cAMP response element binding protein 1 (CREB1) and activating transcription factor 1 (ATF1) are closely related members of the bZIP superfamily of transcription factors. Both are activated in response to a wide array of stimuli, including cellular stress. This study was conducted to assess the CREB1/ATF1 pathway in photoreceptor disease and protection. Methods. The expression levels of p-CREB1, CREB1, and ATF1 were examined by immunoblot and immunohistochemistry in normal canine retina and retinas of several canine models of retinal degeneration (rcd1, rcd2, erd, prcd, XLPRA1, XLPRA2, T4R RHO). Humans retinas affected with age-related macular degeneration (AMD) were also examined. p-CREB1/ATF1 immunolabeling was assessed in normal and rcd1 dogs treated with ciliary neurotrophic factor (CNTF), to examine the effect of a neuroprotective stimulus on activation of CREB1/ATF1. Results. Native CREB1 and ATF1 as well as phosphorylated CREB1/ATF1 was examined in normal canine retina by immunoblot. The p-CREB1 antibody identified phosphorylated CREB1 and ATF1 and labeled the inner retina only in normal dogs. In degenerate canine and human retinas, strong immunolabeling appeared in rod and cone photoreceptors, indicating increased expression of native CREB1 and ATF1, as well as increased phosphorylation of these proteins. Retinal protection by CNTF in rcd1 dogs was accompanied by a significant increase in the number of p-CREB1/ATF1-labeled photoreceptor nuclei. Conclusions. Positive association of CREB1/ATF1 phosphorylation with photoreceptor protection suggests that it may contribute to an innate protective response. These data identify a signaling mechanism in rods and cones of potential importance for therapies of RP and AMD. PMID:19643965

  13. Inheritance of stress-induced, ATF-2-dependent epigenetic change.

    PubMed

    Seong, Ki-Hyeon; Li, Dong; Shimizu, Hideyuki; Nakamura, Ryoichi; Ishii, Shunsuke

    2011-06-24

    Atf1, the fission yeast homolog of activation transcription factor-2 (ATF-2), contributes to heterochromatin formation. However, the role of ATF-2 in chromatin assembly in higher organisms remains unknown. This study reveals that Drosophila ATF-2 (dATF-2) is required for heterochromatin assembly, whereas the stress-induced phosphorylation of dATF-2, via Mekk1-p38, disrupts heterochromatin. The dATF-2 protein colocalized with HP1, not only on heterochromatin but also at specific loci in euchromatin. Heat shock or osmotic stress induced phosphorylation of dATF-2 and resulted in its release from heterochromatin. This heterochromatic disruption was an epigenetic event that was transmitted to the next generation in a non-Mendelian fashion. When embryos were exposed to heat stress over multiple generations, the defective chromatin state was maintained over multiple successive generations, though it gradually returned to the normal state. The results suggest a mechanism by which the effects of stress are inherited epigenetically via the regulation of a tight chromatin structure.

  14. Multi-OTR System for ATF2

    NASA Astrophysics Data System (ADS)

    Faus-Golfe, A.; Gonzalvo, J. Alabau; Gutierrez, C. Blanch; McCormick, D.; Cruz, J.; Woodley, M.; White, G.

    In this paper we describe the first measurements performed during fall of 2010 and the beginning of 2011. We discuss software development, realistic simulations and new hardware improvements of a Multi-Optical Transition Radiation System installed in the beam diagnostics section of the Extraction (EXT) line of ATF2, close to the Multi Wire Scanner System. 2D emittance measurements have been successfully demonstrated and the system is being routinely used for coupling correction. Realistic beam simulations have been made and compared with measurements. A 4D emittance procedure is being prepared and some preliminary measurements have been performed. An improved optical system including a demagnifier lens to improve the beam finding procedure is being designed and will be installed during the autumn 2011 operations period. A systematic measurement campaign will take place after recovery of ATF operations (post the 2011 Tohoku Earthquake), then a comparison with wire scanners can be done. This will be a definitive test of the OTR as a beam emittance diagnostic device, which will provide fast beam emittance measurements with high statistics, giving a low error and a good understanding of emittance jitter and sources.

  15. ATF2 High Availability Power Supplies

    SciTech Connect

    Bellomo, A; Lira, C.de; Lam, B.; MacNair, D.; White, G.; /SLAC

    2008-06-27

    ATF2 is an accelerator test facility modeled after the final focus beamline envisioned for the ILC. By the end of 2008, KEK plans to commission the ATF2 [1]. SLAC and OCEM collaborated on the design of 38 power systems for beamline magnets. The systems range in output power from 1.5 kW to 6 kW. Since high availability is essential for the success of the ILC, Collaborators employed an N+1 modular approach, allowing for redundancy and the use of a single power module rating. This approach increases the availability of the power systems. Common power modules reduces inventory and eases maintenance. Current stability requirements are as tight as 10 ppm. A novel, SLAC designed 20-bit Ethernet Power Supply Controller provides the required precision current regulation. In this paper, Collaborators present the power system design, the expected reliability, fault immunity features, and the methods for satisfying the control and monitoring challenges. Presented are test results and the status of the power systems.

  16. Magnetic Damping For Maglev

    DOE PAGES

    Zhu, S.; Cai, Y.; Rote, D. M.; ...

    1998-01-01

    Magnetic damping is one of the important parameters that control the response and stability of maglev systems. An experimental study to measure magnetic damping directly is presented. A plate attached to a permanent magnet levitated on a rotating drum was tested to investigate the effect of various parameters, such as conductivity, gap, excitation frequency, and oscillation amplitude, on magnetic damping. The experimental technique is capable of measuring all of the magnetic damping coefficients, some of which cannot be measured indirectly.

  17. Damped leaf flexure hinge

    NASA Astrophysics Data System (ADS)

    Chen, Zhong; Chen, Guisheng; Zhang, Xianmin

    2015-05-01

    Flexure-based mechanism like compliant actuation system embeds complex dynamics that will reduce the control bandwidth and limits their dynamic positioning precision. This paper presents a theoretical model of a leaf flexure hinge with damping layers using strain energy method and Kelvin damping model. The modified loss factor of the damped leaf flexure hinge is derived, and the equivalent viscous damping coefficient of the damped leaf hinge is obtained, which could be used to improve the pseudo-rigid-model. The free vibration signals of the hinge in three different damping configurations are measured. The experimental modal analysis also is performed on the three kinds of damped leaf flexure hinges in order to evaluate their 1st order bending natural frequency and vibration-suppressing effects. The evaluation of modified loss factor model also is performed. The experimental results indicate that the constrained layer damping can enhance the structure damping of the hinge even if only single damping layer each side, the modified loss factor model can get good predicts of a damped leaf flexure hinge in the frequency range below 1st order natural frequency, and it is necessary that the dimensional parameters of the damping layers and basic layer of the hinge should be optimized for simplification at the mechanism's design stage.

  18. Damped leaf flexure hinge.

    PubMed

    Chen, Zhong; Chen, Guisheng; Zhang, Xianmin

    2015-05-01

    Flexure-based mechanism like compliant actuation system embeds complex dynamics that will reduce the control bandwidth and limits their dynamic positioning precision. This paper presents a theoretical model of a leaf flexure hinge with damping layers using strain energy method and Kelvin damping model. The modified loss factor of the damped leaf flexure hinge is derived, and the equivalent viscous damping coefficient of the damped leaf hinge is obtained, which could be used to improve the pseudo-rigid-model. The free vibration signals of the hinge in three different damping configurations are measured. The experimental modal analysis also is performed on the three kinds of damped leaf flexure hinges in order to evaluate their 1st order bending natural frequency and vibration-suppressing effects. The evaluation of modified loss factor model also is performed. The experimental results indicate that the constrained layer damping can enhance the structure damping of the hinge even if only single damping layer each side, the modified loss factor model can get good predicts of a damped leaf flexure hinge in the frequency range below 1st order natural frequency, and it is necessary that the dimensional parameters of the damping layers and basic layer of the hinge should be optimized for simplification at the mechanism's design stage.

  19. The oxido-metabolic driver ATF4 enhances temozolamide chemo-resistance in human gliomas

    PubMed Central

    Chen, Daishi; Rauh, Manfred; Buchfelder, Michael; Eyupoglu, Ilker Y.; Savaskan, Nicolai

    2017-01-01

    Malignant gliomas are devastating neoplasia with limited curative treatment options. Temozolomide (TMZ, Temcat®, Temodal® or Temodar®) is a first-line treatment for malignant gliomas but the development of drug resistance remains a major concern. Activating transcription factor 4 (ATF4) is a critical oxido-metabolic regulator in gliomas, and its role in the pathogenesis of TMZ-resistance remains elusive. We investigated the effect of TMZ on human glioma cells under conditions of enhanced ATF4 expression (ATF4OE) and ATF4 knock down (ATF4KD). We monitored cell survival, ATF4 mRNA expression of ATF4 and xCT (SLC7a11) regulation within human gliomas. TMZ treatment induces a transcriptional response with elevated expression of ATF4, xCT and Nrf2, as a sign of ER stress and toxic cell damage response. ATF4 overexpression (ATF4OE) fosters TMZ resistance in human gliomas and inhibits TMZ-induced autophagy. Conversely, ATF4 suppression by small interfering RNAs (ATF4KD) leads to increased TMZ susceptibility and autophagy in comparison to wild type gliomas. ATF4OE gliomas show reduced cell cycle shift and apoptotic cell death, whereas ATF4KD gliomas reveal higher susceptibility towards cell cycle rearrangements. Hence, the migration capacity of ATF4OE glioma cells is almost not affected by TMZ treatment. In contrast, ATF4KD gliomas show a migratory stop following TMZ application. Mechanistically, xCT elevation is a consequence of ATF4 activation and increased levels of xCT amplifies ATF4-induced TMZ resistance. Our data show that ATF4 operates as a chemo-resistance gene in gliomas, and the tumor promoting function of ATF4 is mainly determined by its transcriptional target xCT. Therefore, therapeutic inactivation of ATF4 can be a promising strategy to overcome chemo-resistance and promote drug efficacy in human gliomas. PMID:28881638

  20. Runaway electron studies in the ATF torsatron

    SciTech Connect

    England, A.C.; Bell, G.L.; Fowler, R.H.; Glowienka, J.C.; Harris, J.H.; Lee, D.K.; Murakami, M.; Neilson, G.H.; Rasmussen, D.A.; Rome, J.A.; Saltmarsh, M.J.; Wilgen, J.B. )

    1991-07-01

    Runaway electron formation and confinement occur readily in pulsed torsatrons and heliotrons because of the high loop voltages during initiation and termination of the helical and vertical fields ( field ramping'') and the inherently good containment of the electrons on the flux surfaces in the vacuum fields. This has been confirmed for the Advanced Toroidal Facility (AFT) (Fusion Technol. {bold 10}, 179 (1986)) and other stellarators by orbit calculations. Since runaway electrons can cause an unacceptable level of hard x rays near the machine, a runaway electron suppression system was incorporated in ATF. The main component of the system is a movable paddle, which is normally left in the center of the plasma chamber during the field ramps. This device, in conjunction with programmed vertical field ramping, which reduces the volume of good flux surfaces, has proved to be very effective in reducing the runaway electron population. Measurements of hard x rays from ATF have shown that the runaway electrons are produced primarily during the field ramping but that there is usually also a small steady-state runaway electron component during the flat-top'' portion of the fields. The paddle is the main source of the hard x radiation (thick-target bremsstrahlung). There is evidence that some of the runaway electrons may be confined to islands. The maximum x-ray energy found by pulse height analysis is {similar to}12--15 MeV. The mean energy appears to be a few million electron volts. There is a noticeable forward peaking of the bremsstrahlung from the paddle. The limiters do not appear to be major sources of x rays.

  1. Sin1 binds to both ATF-2 and p38 and enhances ATF-2-dependent transcription in an SAPK signaling pathway.

    PubMed

    Makino, Chieko; Sano, Yuji; Shinagawa, Toshie; Millar, Jonathan B A; Ishii, Shunsuke

    2006-11-01

    Yeast Sin1 binds to the Sty1 kinase, a member of the stress-activated kinases (SAPKs), and is required for stress-induced phosphorylation and activation of the transcription factor Atf1, a homolog of the vertebrate-activating transcription factor-2 (ATF-2). Here we report that mammalian Sin1 plays an important role in the SAPK signaling pathway by binding to both ATF-2 and p38. In response to stress, ATF-2, a member of the ATF/cAMP response element-binding protein family, is phosphorylated by p38/Jun NH2-terminal protein kinase and activates the transcription of apoptosis-related genes. In contrast, in response to serum stimulation, ATF-2 is phosphorylated via the Ras effector pathway and leads to the induction of growth-related genes. We found that Sin1 binds directly to both ATF-2 and p38. Sin1 over-expression enhanced osmotic stress-induced phosphorylation of ATF-2 and ATF-2-mediated transcription, whereas knockdown of Sin1 expression by siRNA suppressed these responses. Moreover, a reduction in Sin1 expression suppressed osmotic stress-induced apoptosis and the expression of Gadd45beta, one of the ATF-2 target genes that is correlated with apoptosis. Decreased Sin1 expression, however, did not affect the serum stimulation-induced phosphorylation of ATF-2. Sin1 may contribute to ATF-2 signaling specificity by acting as a nuclear scaffold.

  2. ATF3 suppresses ESCC via downregulation of ID1.

    PubMed

    Li, Jian; Yang, Zishan; Chen, Zhiuguo; Bao, Yonghua; Zhang, Huijuan; Fang, Xinhui; Yang, Wancai

    2016-09-01

    Esophageal cancer is one of the most prevalent forms of cancer and has a particularly high mortality rate due to early metastasis; however, the underlying mechanisms of its formation and progression remain unclear. The present study performed immunohistochemical analysis and observed that the expression of activating transcription factor 3 (ATF3) was reduced in esophageal squamous cell carcinoma (ESCC) in comparison with non-tumor adjacent tissues. By contrast, inhibitor of DNA binding 1 (ID1) was overexpressed in ESCC tissues, demonstrating an inverse correlation with ATF3 (P<0.01). In ESCC EC109 and KYSE450 cells lines, transfection with an ATF3-overexpression plasmid resulted in the inhibition of cell proliferation, motility and migration, which was associated with the induction of E-cadherin expression and inhibition of cyclin D1 and Twist. Notably, ATF3 exerted an inverse regulatory interaction with ID1. The results of the present study provide additional evidence of the tumor suppressive features of ATF3 and demonstrate a novel mechanism of ATF3-mediated inhibition of cancer metastasis in esophageal cancer.

  3. ATF3 suppresses ESCC via downregulation of ID1

    PubMed Central

    Li, Jian; Yang, Zishan; Chen, Zhiuguo; Bao, Yonghua; Zhang, Huijuan; Fang, Xinhui; Yang, Wancai

    2016-01-01

    Esophageal cancer is one of the most prevalent forms of cancer and has a particularly high mortality rate due to early metastasis; however, the underlying mechanisms of its formation and progression remain unclear. The present study performed immunohistochemical analysis and observed that the expression of activating transcription factor 3 (ATF3) was reduced in esophageal squamous cell carcinoma (ESCC) in comparison with non-tumor adjacent tissues. By contrast, inhibitor of DNA binding 1 (ID1) was overexpressed in ESCC tissues, demonstrating an inverse correlation with ATF3 (P<0.01). In ESCC EC109 and KYSE450 cells lines, transfection with an ATF3-overexpression plasmid resulted in the inhibition of cell proliferation, motility and migration, which was associated with the induction of E-cadherin expression and inhibition of cyclin D1 and Twist. Notably, ATF3 exerted an inverse regulatory interaction with ID1. The results of the present study provide additional evidence of the tumor suppressive features of ATF3 and demonstrate a novel mechanism of ATF3-mediated inhibition of cancer metastasis in esophageal cancer. PMID:27602100

  4. Spin-Damping in an RF atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Alem, Orang; Romalis, Michael V.; Sauer, Karen L.

    2009-05-01

    Optically pumped atomic magnetometers have demonstrated an improved sensitivity over standard tuned coils for frequencies less than 50 MHz, making these radio-frequency (RF) magnetometers attractive for low-field NMR (for example, Budker and Romalis, Nature Physics 3, April 2007). Such magnetometers are often plagued by transient effects resulting in decreased sensitivity. The decay time of these transients, or ringing, can last for milliseconds, which is particularly detrimental for rapidly decaying NMR signals. We have found that actively damping the ringing of the atomic spins can significantly reduce such dead time. This spin-damping of the atomic transients is achieved through a negative feedback mechanism in which part of the optical signal during ringing is used to apply an RF field forcing the realignment of the atomic spins with the static magnetic field. We have successfully implemented spin-damping in 100 μs and recovered our femto-Tesla signal previously obscured by the ringing.

  5. Critically damped quantum search.

    PubMed

    Mizel, Ari

    2009-04-17

    Although measurement and unitary processes can accomplish any quantum evolution in principle, thinking in terms of dissipation and damping can be powerful. We propose a modification of Grover's algorithm in which the idea of damping plays a natural role. Remarkably, we find that there is a critical damping value that divides between the quantum O(sqrt[N]) and classical O(N) search regimes. In addition, by allowing the damping to vary in a fashion we describe, one obtains a fixed-point quantum search algorithm in which ignorance of the number of targets increases the number of oracle queries only by a factor of 1.5.

  6. Engineered damping treatments

    NASA Astrophysics Data System (ADS)

    Oh, J.; Ray, Manas C.; Baz, Amr M.

    2001-07-01

    Engineered Damping Treatments (EDT) that have high damping characteristics per unit volume are presented. The EDT's under consideration, consist of cellular viscoelastic damping matrices with optimally selected cell configuration, size and distribution. The cellular topology of the EDT's is designed using Computer-Aided-Design (CAD) strategies and the obtained optimal configurations will be manufactured using the state-of-the-art technology of Rapid Prototyping (RP). The EDT's are modeled using the finite element method in an attempt to determine the optimal topologies that maximize the strain energy, maximize the damping characteristics and minimize the total weight. The CAD files of the prototypes of the EDT's. The damping characteristics of the manufactured EDT's are evaluated and compared with the corresponding characteristics obtained by conventional solid damping treatments in order to emphasize the importance of using optimally configured damping treatment to achieve high damping characteristics. The presented procedures are invaluable for designing efficient damping treatments for many military and civilian structures whose vibrations and noise must be effectively controlled.

  7. Drosophila ATF-2 regulates sleep and locomotor activity in pacemaker neurons.

    PubMed

    Shimizu, Hideyuki; Shimoda, Masami; Yamaguchi, Terumi; Seong, Ki-Hyeon; Okamura, Tomoo; Ishii, Shunsuke

    2008-10-01

    Stress-activated protein kinases such as p38 regulate the activity of transcription factor ATF-2. However, the physiological role of ATF-2, especially in the brain, is unknown. Here, we found that Drosophila melanogaster ATF-2 (dATF-2) is expressed in large ventral lateral neurons (l-LN(v)s) and also, to a much lesser extent, in small ventral lateral neurons, the pacemaker neurons. Only l-LN(v)s were stained with the antibody that specifically recognizes phosphorylated dATF-2, suggesting that dATF-2 is activated specifically in l-LN(v)s. The knockdown of dATF-2 in pacemaker neurons using RNA interference decreased sleep time, whereas the ectopic expression of dATF-2 increased sleep time. dATF-2 knockdown decreased the length of sleep bouts but not the number of bouts. The ATF-2 level also affected the sleep rebound after sleep deprivation and the arousal threshold. dATF-2 negatively regulated locomotor activity, although it did not affect the circadian locomotor rhythm. The degree of dATF-2 phosphorylation was greater in the morning than at night and was enhanced by forced locomotion via the dp38 pathway. Thus, dATF-2 is activated by the locomotor while it increases sleep, suggesting a role for dATF-2 as a regulator to connect sleep with locomotion.

  8. Problems with the equation for viscous damping of density waves

    NASA Astrophysics Data System (ADS)

    Schmidt, J.; Salo, H.; Spahn, F.

    2011-12-01

    Numerous resonances with external satellites excite density waves in Saturn's rings. A theoretical expression for the damping of these waves, when they propagate away from the resonance location, is derived from a fluid model (GT78: Goldreich and Tremaine, 1978, Icarus, 34, 240, see also: Shu et al., 1984, in Planetary Rings). The magnitude of the shear viscosity of Saturn's rings is inferred from comparison of this theory to the actual damping length of density waves observed in various data sets (e.g. Esposito et al., 1983, Lissauer et al., 1984, Tiscareno et al., 2007). In the theoretical expression for the damping length the fluid's bulk viscosity enters (in addition to the shear viscosity) as well as the dependence of both viscosities on the density of the ring matter. However, generally the bulk viscosity and the effects of the density dependences are neglected when the shear viscosity is inferred from the data. It has already been pointed out in the original paper (GT78) that this neglect lacks adequate justification. This raises the question in how far the inferred viscosities are representative for the rings. In particular, if one takes into acount the density dependence of the viscosities, the expression for the viscous damping transforms into a relation that is equivalent to the stability criterion for viscous overstability. In this case the theory implies that there might be ring regions where density waves do not damp at all but grow in amplitude (GT78). In this paper we re-derive the expression for the wave damping, including the terms stemming from the density dependence of the viscosities. We discuss their effect in the light of the presence of self-gravity wakes in the rings, contributing to viscosity, the probable detection of viscous overstability in parts of Saturn's ring system, and the behaviour of the Janus/Epimetheus m:m-1 wavetrains.

  9. Decoherence and Landau-Damping

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2005-12-01

    The terminologies, decoherence and Landau damping, are often used concerning the damping of a collective instability. This article revisits the difference and relation between decoherence and Landau damping. A model is given to demonstrate how Landau damping affects the rate of damping coming from decoherence.

  10. Turbine blade damping study

    NASA Technical Reports Server (NTRS)

    Dominic, R. J.

    1984-01-01

    Research results and progress on the performance of bladed systems is reported the different topics discussed include: the study of turbine blade damping; forced vibrations of friction damped beam moistures in two dimensions; and a users manual for a computer program for dynamic analysis of bladed systems.

  11. Turbojet engine blade damping

    NASA Technical Reports Server (NTRS)

    Srinivasan, A. V.; Cutts, D. G.; Sridhar, S.

    1981-01-01

    The potentials of various sources of nonaerodynamic damping in engine blading are evaluated through a combination of advanced analysis and testing. The sources studied include material hysteresis, dry friction at shroud and root disk interfaces as well as at platform type external dampers. A limited seris of tests was conducted to evaluate damping capacities of composite materials (B/AL, B/AL/Ti) and thermal barrier coatings. Further, basic experiments were performed on titanium specimens to establish the characteristics of sliding friction and to determine material damping constants J and n. All the tests were conducted on single blades. Mathematical models were develthe several mechanisms of damping. Procedures to apply this data to predict damping levels in an assembly of blades are developed and discussed.

  12. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry

    2014-03-01

    Preface: a personal view of planetary rings; 1. Introduction: the allure of the ringed planets; 2. Studies of planetary rings 1610-2013; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Uranus' rings and moons; 13. Neptune's partial rings; 14. Jupiter's ring-moon system after Galileo and New Horizons; 15. Ring photometry; 16. Dusty rings; 17. Concluding remarks; Afterword; Glossary; References; Index.

  13. Variations of hybrid damping

    NASA Astrophysics Data System (ADS)

    Lam, Margaretha J.; Inman, Daniel J.; Saunders, William R.

    1998-06-01

    Damping is important to structures and can be achieved through the addition of viscoelastic materials (VEM). The damping of the VEM is enhanced if a constraining layer is attached to the VEM. If this constraining layer is active, the treatment is called active constrained layer damping (ACLD). In the last few years, ACLD has proven to be superior in vibration control to active or passive damping. The active element makes ACLD more effective than passive constrained layer damping. It also provides a fail-safe in case of breakdown of the active element that is not present for purely active control. It is shown that the control effort needed to damp vibration using ACLD can be significantly higher than purely active control. In order to combine the inherent damping of passive control with the effectiveness of the active element, this paper will explore different variations of active, passive and hybrid damping. Some of the variations include: passive constrained layer damping (PCLD) separate from active element but on the same side of beam, PCLD separate from active on the opposite side of the beam, and active element underneath PCLD. The discretized system equations will be obtained using assumed modes method and Lagrange's equation. The damping will be modeled using the Golla-Hughes-McTavish (GHM) method. The optimal placement and size of the active, passive, ACLD and hybrid treatments will be found using different schemes. The issue of overshoot and settling time of the output and control force using LQR will be addressed, as well as the control effort, passive and active vibration suppression, and LQR cost function. It will be shown that the hybrid treatments are capable of greater vibration control for lower control effort for different optimization schemes. 31

  14. Effect of ATF3-deletion on apoptosis of cultured retinal ganglion cells

    PubMed Central

    Sun, Ming-Ming; Wang, Ya-Chen; Li, Yi; Guo, Xiao-Dan; Chen, Yan-Ming; Zhang, Zhong-Zhi

    2017-01-01

    AIM To investigate the effect of activating transcription factor-3 (ATF3)-deletion on apoptosis of cultured retinal ganglion cells (RGCs). METHODS Three ATF3 siRNA (ATF3-rat-651, ATF3-rat-319, ATF3-rat-520) were constructed, and were transiently transfected into RGC-5 cells. Quantitative real-time polymerase chain reaction (PCR) was used to examine ATF3 expression and the most effective ATF3 siRNA was selected for further studies. Flow cytometry was applied to investigate the effects of ATF3 deletion on RGC-5 apoptosis under elevated hydrostatic pressure. Quantitative real-time PCR and Western blot were performed to validate differentially expressed genes and proteins in ATF3-knockdown RGC-5 cells. RESULTS ATF3 specific siRNA effectively down-regulated ATF3 expression and significantly inhibited cell apoptosis in RGC-5 cells. Quantitative real-time PCR and Western blot confirmed that ATF3 knockdown remarkably decreased Jun-B and increased c-Jun at both mRNA and protein levels in RGC-5 cells. CONCLUSION ATF/cAMP-response element-binding family of transcription factors may be involved in the development of glaucoma and could be novel treatment targets for glaucoma. PMID:28546922

  15. ATF7 ablation prevents diet-induced obesity and insulin resistance.

    PubMed

    Liu, Yang; Maekawa, Toshio; Yoshida, Keisuke; Furuse, Tamio; Kaneda, Hideki; Wakana, Shigeharu; Ishii, Shunsuke

    2016-09-16

    The activating transcription factor (ATF)2 family of transcription factors regulates a variety of metabolic processes, including adipogenesis and adaptive thermogenesis. ATF7 is a member of the ATF2 family, and mediates epigenetic changes induced by environmental stresses, such as social isolation and pathogen infection. However, the metabolic role of ATF7 remains unknown. The aim of the present study is to examine the role of ATF7 in metabolism using ATF7-dificeint mice. Atf7(-/-) mice exhibited lower body weight and resisted diet-induced obesity. Serum triglycerides, resistin, and adipose tissue mass were all significantly lower in ATF7-deficient mice. Fasting glucose levels and glucose tolerance were unaltered, but systemic insulin sensitivity was increased, by ablation of ATF7. Indirect calorimetry revealed that oxygen consumption by Atf7(-/-) mice was comparable to that of wild-type littermates on a standard chow diet, but increased energy expenditure was observed in Atf7(-/-) mice on a high-fat diet. Hence, ATF7 ablation may impair the development and function of adipose tissue and result in elevated energy expenditure in response to high-fat-feeding obesity and insulin resistance, indicating that ATF7 is a potential therapeutic target for diet-induced obesity and insulin resistance. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. ATF4-dependent regulation of the JMJD3 gene during amino acid deprivation can be rescued in Atf4-deficient cells by inhibition of deacetylation.

    PubMed

    Shan, Jixiu; Fu, Lingchen; Balasubramanian, Mukundh N; Anthony, Tracy; Kilberg, Michael S

    2012-10-19

    Following amino acid deprivation, the amino acid response (AAR) induces transcription from specific genes through a collection of signaling mechanisms, including the GCN2-eIF2-ATF4 pathway. The present report documents that the histone demethylase JMJD3 is an activating transcription factor 4 (ATF4)-dependent target gene. The JMJD3 gene contains two AAR-induced promoter activities and chromatin immunoprecipitation (ChIP) analysis showed that the AAR leads to enhanced ATF4 recruitment to the C/EBP-ATF response element (CARE) upstream of Promoter-1. AAR-induced histone modifications across the JMJD3 gene locus occur upon ATF4 binding. Jmjd3 transcription is not induced in Atf4-knock-out cells, but the AAR-dependent activation was rescued by inhibition of histone deacetylation with trichostatin A (TSA). The TSA rescue of AAR activation in the absence of Atf4 also occurred for the Atf3 and C/EBP homology protein (Chop) genes, but not for the asparagine synthetase gene. ChIP analysis of the Jmjd3, Atf3, and Chop genes in Atf4 knock-out cells documented that activation of the AAR in the presence of TSA led to specific changes in acetylation of histone H4. The results suggest that a primary function of ATF4 is to recruit histone acetyltransferase activity to a sub-set of AAR target genes. Thus, absolute binding of ATF4 to these particular genes is not required and no ATF4 interaction with the general transcription machinery is necessary. The data are consistent with the hypothesis that ATF4 functions as a pioneer factor to alter chromatin structure and thus, enhance transcription in a gene-specific manner.

  17. NEDD8-activating enzyme inhibitor, MLN4924 (Pevonedistat) induces NOXA-dependent apoptosis through up-regulation of ATF-4.

    PubMed

    Liu, Xiaojun; Jiang, Yanan; Wu, Jianfu; Zhang, Wenjuan; Liang, Yupei; Jia, Lijun; Yu, Jinha; Jeong, L S; Li, Lihui

    2017-06-17

    It has been reported that MLN4924 can inhibit cell growth and metastasis in various kinds of cancer. We have reported that MLN4924 is able to inhibit angiogenesis through the induction of cell apoptosis both in vitro and in vivo models. Moreover, Neddylation inhibition using MLN4924 triggered the accumulation of pro-apoptotic protein NOXA in Human umbilical vein endothelial cells (HUVECs). However, the mechanism of MLN4924-induced NOXA up-regulation has not been addressed in HUVECs yet. In this study, we investigated how MLN4924 induced NOXA expression and cellular apoptosis in HUVECs treated with MLN4924 at indicated concentrations. MLN4924-induced apoptosis was evaluated by Annexin V-FITC/PI analysis and expression of genes associated with apoptosis was assessed by Quantitative RT-PCR and western blotting. As a result, MLN4924 triggered NOXA-dependent apoptosis in a dose-dependent manner in HUVECs. Mechanistically, inactivation of Neddylation pathway caused up-regulation of activating transcription factor 4 (ATF-4), a substrate of Cullin-Ring E3 ubiquitin ligases (CRL). NOXA was subsequently transactivated by ATF-4 and further induced apoptosis. More importantly, knockdown of ATF-4 by siRNA significantly decreased NOXA expression and apoptotic induction in HUVECs. In summary, our study reveals a new mechanism underlying MLN4924-induced NOXA accumulation in HUVECs, which may help extend further study of MLN4924 for angiogenesis inhibition treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Spatial cyclotron damping

    NASA Technical Reports Server (NTRS)

    Olson, C. L.

    1970-01-01

    To examine spatial electron cyclotron damping in a uniform Vlasov plasma, it is noted that the plasma response to a steady-state transverse excitation consists of several terms (dielectric-pole, free-streaming, and branch-cut), but that the cyclotron-damped pole term is the dominant term for z l = c/w sub ce provided (w sub pe/w sub ce) squared (c/a) is much greater than 1. If the latter inequality does not hold, then the free-streaming and branch-cut terms persist well past z = c/w sub ce as w sub 1 approaches w sub ce, making experimental measurement of cyclotron damping essentially impossible. Considering only (w sub pe/w sub ce) squared (c/a) is much greater than 1, it is shown how collisional effects should be estimated and how a finite-width excitation usually has little effect on the cyclotron-damped part of the response. Criteria is established concerning collisional damping, measurable damping length sizes, and allowed uncertainty in the magnetic field Beta. Results of numerical calculations, showing the regions in the appropriate parameter spaces that meet these criteria, are presented. From these results, one can determine the feasibility of, or propose parameter values for, an experiment designed to measure spatial cyclotron damping. It is concluded that the electron temperature T sub e should be at least 1 ev., and preferably 10 ev. or higher, for a successful experiment.

  19. ATF3 activates Stat3 phosphorylation through inhibition of p53 expression in skin cancer cells.

    PubMed

    Hao, Zhen-Feng; Ao, Jun-Hong; Zhang, Jie; Su, You-Ming; Yang, Rong-Ya

    2013-01-01

    ATF3, a member of the ATF/CREB family of transcription factors, has been found to be selectively induced by calcineurin/NFAT inhibition and to enhance keratinocyte tumor formation, although the precise role of ATF3 in human skin cancer and possible mechanisms remain unknown. In this study, clinical analysis of 30 skin cancer patients and 30 normal donors revealed that ATF3 was accumulated in skin cancer tissues. Functional assays demonstrated that ATF3 significantly promoted skin cancer cell proliferation. Mechanically, ATF3 activated Stat3 phosphorylation in skin cancer cell through regulation of p53 expression. Moreover, the promotion effect of ATF3 on skin cancer cell proliferation was dependent on the p53-Stat3 signaling cascade. Together, the results indicate that ATF3 might promote skin cancer cell proliferation and enhance skin keratinocyte tumor development through inhibiting p53 expression and then activating Stat3 phosphorylation.

  20. Acoustic transducer with damping means

    DOEpatents

    Smith, Richard W.; Adamson, Gerald E.

    1976-11-02

    An ultrasonic transducer specifically suited to high temperature sodium applications is described. A piezoelectric active element is joined to the transducer faceplate by coating the faceplate and juxtaposed active element face with wetting agents specifically compatible with the bonding procedure employed to achieve the joint. The opposite face of the active element is fitted with a backing member designed to assure continued electrical continuity during adverse operating conditions which can result in the fracturing of the active element. The fit is achieved employing a spring-loaded electrode operably arranged to electrically couple the internal transducer components, enclosed in a hermetically sealed housing, to accessory components normally employed in transducer applications. Two alternative backing members are taught for assuring electrical continuity. The first employs a resilient, discrete multipoint contact electrode in electrical communication with the active element face. The second employs a resilient, elastomeric, electrically conductive, damped member in electrical communication with the active element face in a manner to effect ring-down of the transducer. Each embodiment provides continued electrical continuity within the transducer in the event the active element fractures, while the second provides the added benefit of damping.

  1. Emittance reconstruction from measured beam sizes in ATF2 and perspectives for ILC

    NASA Astrophysics Data System (ADS)

    Faus-Golfe, A.; Navarro, J.; Fuster Martinez, N.; Resta Lopez, J.; Giner Navarro, J.

    2016-05-01

    The projected emittance (2D) and the intrinsic emittance (4D) reconstruction method by using the beam size measurements at different locations is analyzed in order to study analytically the conditions of solvability of the systems of equations involved in this process. Some conditions are deduced and discussed, and general guidelines about the locations of the measurement stations have been obtained to avoid unphysical results. The special case of the multi-Optical Transition Radiation system (m-OTR), made of four measurement stations, in the Extraction Line (EXT) of Accelerator Test Facility 2 (ATF2) has been simulated in much detail and compared with measurements. Finally a feasibility study of a multi-station system for fast transverse beam size measurement, emittance reconstruction and coupling correction in the Ring to Main Linac (RTML) of International Linear Collider (ILC) Diagnostic sections of the RTML has been discussed in detail.

  2. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.

    2011-07-01

    Preface; 1. Introduction: the allure of ringed planets; 2. Studies of planetary rings 1610-2004; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-Body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Neptune's partial rings; 13. Jupiter's ring-moon system after Galileo; 14. Ring photometry; 15. Dusty rings; 16. Cassini observations; 17. Summary: the big questions; Glossary; References; Index.

  3. Crosstalk between ATF4 and MTA1/HDAC1 promotes osteosarcoma progression.

    PubMed

    Zeng, Heng; Zhang, Jin-Ming; Du, Yu; Wang, Jiang; Ren, Ye; Li, Mi; Li, Hao; Cai, Zhuo; Chu, Qian; Yang, Caihong

    2016-02-09

    The stress response gene activating transcription factor 4 (ATF4) is involved in metastatic behavior and cellular protection. Here we show that ATF4 is upregulated in osteosarcoma (OS) cell lines and patient clinical samples as compared to matched non-tumor tissue. Overexpression of ATF4 in OS cells promoted cell proliferation, migration and lung metastasis. Furthermore, the expression of ATF4 was markedly reduced in metastasis associated protein (MTA1) or histone deacetylase 1 (HDAC1) knockdown OS cells, but MTA1 overexpression increased the stability and activity of ATF4 protein via ATF4 deacetylation by HDAC1. ATF4 in turn enhanced the expression of MTA1 and HDAC1 at the transcription level, suggesting a positive feedback loop between ATF4 and MTA1/HDAC1. Clinically, the level of ATF4 was positively correlated with that of MTA1 in OS. Mice injected with ATF4-overexpressing cells exhibited a higher rate of tumor growth, and the average weight of these tumors was ~90% greater than the controls. Taken together, these data establish a direct correlation between ATF4-induced OS progression and MTA1/HDAC1-associated metastasis, and support the potential therapeutic value of targeting ATF4 in the treatment of OS.

  4. Silencing of ATF2 inhibits growth of pancreatic cancer cells and enhances sensitivity to chemotherapy.

    PubMed

    Li, Mu; Wu, Xingda; Liu, Ning; Li, Xiaoying; Meng, Fanbin; Song, Shaowei

    2017-03-20

    Pancreatic cancer is one of the leading causes of cancer-related death worldwide. Activating transcription factor 2 (ATF2) is a multifunctional transcription factor, and is implicated in tumor progress, yet its role in pancreatic cancer remains unclear. In the present study, the level of ATF2 in pancreatic cancer tissues and the adjacent non-tumorous tissues was detected by quantitative real-time PCR and western blot. The roles of ATF2 in the proliferation, cell cycle, and apoptosis of pancreatic cancer cells were investigated through ATF2 silencing, and the effect of ATF2 shRNA on the sensitivity of pancreatic cancer cells to gemcitabine, an anti-tumor drug, was explored. The results of our study showed that the ATF2 level in the pancreatic cancer tissues was higher than that in the adjacent non-tumorous tissues. Silencing of ATF2 was found to inhibit proliferation, arrest cell cycle at G1 phase and induce apoptosis in pancreatic cancer cells. Moreover, ATF2 silencing enhanced gemcitabine-induced growth-inhibition and apoptosis-induction effects in pancreatic cancer cells. In summary, silencing of ATF2 inhibited the growth of pancreatic cancer cells and enhanced the anti-tumor effects of gemcitabine, suggesting that ATF2 plays a pro-survival role in pancreatic cancer. Our results also propose that a high level of ATF2 may serve as a potential biomarker of pancreatic cancer, and that ATF2 may become a potential target for anti-tumor therapy.

  5. Control System Damps Vibrations

    NASA Technical Reports Server (NTRS)

    Kopf, E. H., Jr.; Brown, T. K.; Marsh, E. L.

    1983-01-01

    New control system damps vibrations in rotating equipment with help of phase-locked-loop techniques. Vibrational modes are controlled by applying suitable currents to drive motor. Control signals are derived from sensors mounted on equipment.

  6. Stability Study of ATF 80MeV Injector Linac

    SciTech Connect

    McCormick, Douglas

    2003-06-09

    A beam stability test was carried out at ATF 80 MeV injector linac. The test was performed by taking data of each monitor in pulse to pulse base. A data acquisition system which consists of a PC and a GPIB network was used for the test. In order to analyze the data, ''Correlation Plot'' method is used which is effective to find out some source of the observed beam fluctuation. This paper describes the result of the stability measurement and the comparison between ATF injector and SLC injector.

  7. DAMPs, ageing, and cancer: The 'DAMP Hypothesis'.

    PubMed

    Huang, Jin; Xie, Yangchun; Sun, Xiaofang; Zeh, Herbert J; Kang, Rui; Lotze, Michael T; Tang, Daolin

    2015-11-01

    Ageing is a complex and multifactorial process characterized by the accumulation of many forms of damage at the molecular, cellular, and tissue level with advancing age. Ageing increases the risk of the onset of chronic inflammation-associated diseases such as cancer, diabetes, stroke, and neurodegenerative disease. In particular, ageing and cancer share some common origins and hallmarks such as genomic instability, epigenetic alteration, aberrant telomeres, inflammation and immune injury, reprogrammed metabolism, and degradation system impairment (including within the ubiquitin-proteasome system and the autophagic machinery). Recent advances indicate that damage-associated molecular pattern molecules (DAMPs) such as high mobility group box 1, histones, S100, and heat shock proteins play location-dependent roles inside and outside the cell. These provide interaction platforms at molecular levels linked to common hallmarks of ageing and cancer. They can act as inducers, sensors, and mediators of stress through individual plasma membrane receptors, intracellular recognition receptors (e.g., advanced glycosylation end product-specific receptors, AIM2-like receptors, RIG-I-like receptors, and NOD1-like receptors, and toll-like receptors), or following endocytic uptake. Thus, the DAMP Hypothesis is novel and complements other theories that explain the features of ageing. DAMPs represent ideal biomarkers of ageing and provide an attractive target for interventions in ageing and age-associated diseases. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Collision mechanics and the structure of planetary ring edges

    NASA Technical Reports Server (NTRS)

    Spaute, Dominique; Greenberg, Richard

    1987-01-01

    The present numerical simulation of collisional evolution, in the case of a hypothetical ring whose parameters are modeled after those of Saturn's rings, gives attention to changes in radial structure near the ring edges and notes that when random motion is in equilibrium, the rings tend to spread in order to conserve angular momentum while energy is dissipated in collisions. As long as random motion is damped, ring edges may contract rather than spread, producing a concentration of material at the ring edges. For isotropic scattering, damping dominates for a coefficient of restitution of velocity value of up to 0.83.

  9. ATF5 polymorphisms influence ATF function and response to treatment in children with childhood acute lymphoblastic leukemia

    PubMed Central

    Rousseau, Julie; Gagné, Vincent; Labuda, Malgorzata; Beaubois, Cyrielle; Sinnett, Daniel; Laverdière, Caroline; Moghrabi, Albert; Sallan, Stephen E.; Silverman, Lewis B.; Neuberg, Donna; Kutok, Jeffery L.

    2011-01-01

    Asparaginase is a standard and critical component in the therapy of childhood acute lymphoblastic leukemia. Asparagine synthetase (ASNS) and the basic region leucine zipper activating transcription factor 5 (ATF5) and arginosuccinate synthase 1 (ASS1) have been shown to mediate the antileukemic effect of asparaginase and to display variable expression between leukemia cells that are resistant and sensitive to treatment. Fourteen polymorphisms in the regulatory and coding regions of these genes were investigated for an association with acute lymphoblastic leukemia outcome. Lower event-free survival (EFS) was associated with ATF5 T1562C, tandem-repeat ASNS polymorphism, derived haplotype, and ASS1 G1343T and G34T substitutions (P ≤ .03). Associations were limited to patients who received Escherichia coli asparaginase. Variations that sustained correction for multiple testing (ATF5 T1562C, P = .005; ASNS tandem-repeat and related haplotype, P ≤ .01) were subsequently analyzed in the replication cohort. The E coli–dependent association of the ATF5 T1562 allele with reduced EFS was confirmed (P = .01). A gene-reporter assay showed that the haplotype tagged by T1562 had higher promoter activity (P ≤ .01). The remaining regulatory polymorphisms also appeared to affect ATF5 function; 2 additional high-activity haplotypes were identified (P ≤ .02) and were further corroborated by quantitative mRNA analysis in lymphoblastoid cell lines. The ATF5-regulated increase in ASNS expression in response to more efficacious E coli–induced asparagine depletion may explain our observed results. PMID:21972289

  10. ATF5 polymorphisms influence ATF function and response to treatment in children with childhood acute lymphoblastic leukemia.

    PubMed

    Rousseau, Julie; Gagné, Vincent; Labuda, Malgorzata; Beaubois, Cyrielle; Sinnett, Daniel; Laverdière, Caroline; Moghrabi, Albert; Sallan, Stephen E; Silverman, Lewis B; Neuberg, Donna; Kutok, Jeffery L; Krajinovic, Maja

    2011-11-24

    Asparaginase is a standard and critical component in the therapy of childhood acute lymphoblastic leukemia. Asparagine synthetase (ASNS) and the basic region leucine zipper activating transcription factor 5 (ATF5) and arginosuccinate synthase 1 (ASS1) have been shown to mediate the antileukemic effect of asparaginase and to display variable expression between leukemia cells that are resistant and sensitive to treatment. Fourteen polymorphisms in the regulatory and coding regions of these genes were investigated for an association with acute lymphoblastic leukemia outcome. Lower event-free survival (EFS) was associated with ATF5 T1562C, tandem-repeat ASNS polymorphism, derived haplotype, and ASS1 G1343T and G34T substitutions (P ≤ .03). Associations were limited to patients who received Escherichia coli asparaginase. Variations that sustained correction for multiple testing (ATF5 T1562C, P = .005; ASNS tandem-repeat and related haplotype, P ≤ .01) were subsequently analyzed in the replication cohort. The E coli-dependent association of the ATF5 T1562 allele with reduced EFS was confirmed (P = .01). A gene-reporter assay showed that the haplotype tagged by T1562 had higher promoter activity (P ≤ .01). The remaining regulatory polymorphisms also appeared to affect ATF5 function; 2 additional high-activity haplotypes were identified (P ≤ .02) and were further corroborated by quantitative mRNA analysis in lymphoblastoid cell lines. The ATF5-regulated increase in ASNS expression in response to more efficacious E coli-induced asparagine depletion may explain our observed results.

  11. The neuroprotective transcription factor ATF5 is decreased and sequestered into polyglutamine inclusions in Huntington's disease.

    PubMed

    Hernández, Ivó H; Torres-Peraza, Jesús; Santos-Galindo, María; Ramos-Morón, Eloísa; Fernández-Fernández, M Rosario; Pérez-Álvarez, María J; Miranda-Vizuete, Antonio; Lucas, José J

    2017-08-31

    Activating transcription factor-5 (ATF5) is a stress-response transcription factor induced upon different cell stressors like fasting, amino-acid limitation, cadmium or arsenite. ATF5 is also induced, and promotes transcription of anti-apoptotic target genes like MCL1, during the unfolded protein response (UPR) triggered by endoplasmic reticulum stress. In the brain, high ATF5 levels are found in gliomas and also in neural progenitor cells, which need to decrease their ATF5 levels for differentiation into mature neurons or glia. This initially led to believe that ATF5 is not expressed in adult neurons. More recently, we reported basal neuronal ATF5 expression in adult mouse brain and its neuroprotective induction during UPR in a mouse model of status epilepticus. Here we aimed to explore whether ATF5 is also expressed by neurons in human brain both in basal conditions and in Huntington's disease (HD), where UPR has been described to be partially impaired due to defective ATF6 processing. Apart from confirming that ATF5 is present in human adult neurons, here we report accumulation of ATF5 within the characteristic polyglutamine-containing neuronal nuclear inclusions in brains of HD patients and mice. This correlates with decreased levels of soluble ATF5 and of its antiapoptotic target MCL1. We then confirmed the deleterious effect of ATF5 deficiency in a Caenorhabditis elegans model of polyglutamine-induced toxicity. Finally, ATF5 overexpression attenuated polyglutamine-induced apoptosis in a cell model of HD. These results reflect that decreased ATF5 in HD-probably secondary to sequestration into inclusions-renders neurons more vulnerable to mutant huntingtin-induced apoptosis and that ATF5-increasing interventions might have therapeutic potential for HD.

  12. Damping modeling in Timoshenko beams

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Wang, Y.

    1992-01-01

    Theoretical and numerical results of damping model studies for composite material beams using the Timoshenko theory is presented. Based on the damping models developed for Euler-Bernoulli beams, the authors develop damping methods for both bending and shear in investigation of Timoshenko beams. A computational method for the estimation of the damping parameters is given. Experimental data with high-frequency excitation were used to test Timoshenko beam equations with different types of damping models for bending and shear in various combinations.

  13. Human CHAC1 Protein Degrades Glutathione, and mRNA Induction Is Regulated by the Transcription Factors ATF4 and ATF3 and a Bipartite ATF/CRE Regulatory Element.

    PubMed

    Crawford, Rebecca R; Prescott, Eugenia T; Sylvester, Charity F; Higdon, Ashlee N; Shan, Jixiu; Kilberg, Michael S; Mungrue, Imran N

    2015-06-19

    Using an unbiased systems genetics approach, we previously predicted a role for CHAC1 in the endoplasmic reticulum stress pathway, linked functionally to activating transcription factor 4 (ATF4) following treatment with oxidized phospholipids, a model for atherosclerosis. Mouse and yeast CHAC1 homologs have been shown to degrade glutathione in yeast and a cell-free system. In this report, we further defined the ATF4-CHAC1 interaction by cloning the human CHAC1 promoter upstream of a luciferase reporter system for in vitro assays in HEK293 and U2OS cells. Mutation and deletion analyses defined two major cis DNA elements necessary and sufficient for CHAC1 promoter-driven luciferase transcription under conditions of ER stress or ATF4 coexpression: the -267 ATF/cAMP response element (CRE) site and a novel -248 ATF/CRE modifier (ACM) element. We also examined the ability of the CHAC1 ATF/CRE and ACM sequences to bind ATF4 and ATF3 using immunoblot-EMSA and confirmed ATF4, ATF3, and CCAAT/enhancer-binding protein β binding at the human CHAC1 promoter in the proximity of the ATF/CRE and ACM using ChIP. To further validate the function of CHAC1 in a human cell model, we measured glutathione levels in HEK293 cells with enhanced CHAC1 expression. Overexpression of CHAC1 led to a robust depletion of glutathione, which was alleviated in a CHAC1 catalytic mutant. These results suggest an important role for CHAC1 in oxidative stress and apoptosis with implications for human health and disease. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. Human CHAC1 Protein Degrades Glutathione, and mRNA Induction Is Regulated by the Transcription Factors ATF4 and ATF3 and a Bipartite ATF/CRE Regulatory Element*

    PubMed Central

    Crawford, Rebecca R.; Prescott, Eugenia T.; Sylvester, Charity F.; Higdon, Ashlee N.; Shan, Jixiu; Kilberg, Michael S.; Mungrue, Imran N.

    2015-01-01

    Using an unbiased systems genetics approach, we previously predicted a role for CHAC1 in the endoplasmic reticulum stress pathway, linked functionally to activating transcription factor 4 (ATF4) following treatment with oxidized phospholipids, a model for atherosclerosis. Mouse and yeast CHAC1 homologs have been shown to degrade glutathione in yeast and a cell-free system. In this report, we further defined the ATF4-CHAC1 interaction by cloning the human CHAC1 promoter upstream of a luciferase reporter system for in vitro assays in HEK293 and U2OS cells. Mutation and deletion analyses defined two major cis DNA elements necessary and sufficient for CHAC1 promoter-driven luciferase transcription under conditions of ER stress or ATF4 coexpression: the −267 ATF/cAMP response element (CRE) site and a novel −248 ATF/CRE modifier (ACM) element. We also examined the ability of the CHAC1 ATF/CRE and ACM sequences to bind ATF4 and ATF3 using immunoblot-EMSA and confirmed ATF4, ATF3, and CCAAT/enhancer-binding protein β binding at the human CHAC1 promoter in the proximity of the ATF/CRE and ACM using ChIP. To further validate the function of CHAC1 in a human cell model, we measured glutathione levels in HEK293 cells with enhanced CHAC1 expression. Overexpression of CHAC1 led to a robust depletion of glutathione, which was alleviated in a CHAC1 catalytic mutant. These results suggest an important role for CHAC1 in oxidative stress and apoptosis with implications for human health and disease. PMID:25931127

  15. The Vibration Ring. Phase 1; [Seedling Fund

    NASA Technical Reports Server (NTRS)

    Asnani, Vivake M.; Krantz, Timothy L.; Delap, Damon C.; Stringer, David B.

    2014-01-01

    The vibration ring was conceived as a driveline damping device to prevent structure-borne noise in machines. It has the appearance of a metal ring, and can be installed between any two driveline components like an ordinary mechanical spacer. Damping is achieved using a ring-shaped piezoelectric stack that is poled in the axial direction and connected to an electrical shunt circuit. Surrounding the stack is a metal structure, called the compression cage, which squeezes the stack along its poled axis when excited by radial driveline forces. The stack in turn generates electrical energy, which is either dissipated or harvested using the shunt circuit. Removing energy from the system creates a net damping effect. The vibration ring is much stiffer than traditional damping devices, which allows it to be used in a driveline without disrupting normal operation. In phase 1 of this NASA Seedling Fund project, a combination of design and analysis was used to examine the feasibility of this concept. Several designs were evaluated using solid modeling, finite element analysis, and by creating prototype hardware. Then an analytical model representing the coupled electromechanical response was formulated in closed form. The model was exercised parametrically to examine the stiffness and loss factor spectra of the vibration ring, as well as simulate its damping effect in the context of a simplified driveline model. The results of this work showed that this is a viable mechanism for driveline damping, and provided several lessons for continued development.

  16. Overview of the ATF (Advanced Toroidal Facility) Program

    SciTech Connect

    Lyon, J.F.; Bigelow, T.S.; Carreras, B.A.; Carter, M.D.; Colchin, R.J.; Crume, E.C.; Dominguez, N.; Dunlap, J.L.; Dyer, G.R.; England, A.C.; Glowienka, J.C.; Goulding, R.H.; Halliwell, J.W.; Harris, J.H.; Hillis, D.L.; Hiroe, S.; Horton, L.D.; Howe, H.C.; Hutchinson, D.P.; Isler, R.C.; Jernigan, T.C.; Kindsfather, R.R.; Langley, R.A.; Leboeuf, J.N.; Ma, C.H.; Menon, M.M.; Meyer, F.W.; Mioduszewski, P.K.; Murakami, M.; Neilso

    1989-01-01

    Initial operation of ATF showed narrow pressure profiles and second stability behavior at lower beta than expected and revealed uncompensated dipoles in the HF winding leads that have since been corrected. Energy confinement times obtained with neutral beam injection and electron cyclotron heating roughly follow the LHD scaling. However, a plasma collapse is observed with NBI 6 refs., 9 figs.

  17. A Laser-Wire System at the ATF Extraction Line

    SciTech Connect

    Boogert, S.T.; Blair, G.; Boorman, G.; Bosco, A.; Deacon, L.; Driouichi, C.; Karataev, P.; Kamps, T.; Delerue, N.; Dixit, S.; Foster, B.; Gannaway, F.; Howell, D.F.; Qureshi, M.; Reichold, A.; Senanayake, R.; Aryshev, A.; Hayano, H.; Kubo, K.; Terunuma, N.; Urakawa, J.; /KEK, Tsukuba /Liverpool U. /Cockcroft Inst. Accel. Sci. Tech. /SLAC

    2007-02-12

    A new laser-wire (LW) system has been installed at the ATF extraction line at KEK, Tsukuba. The system aims at a micron-scale laser spot size and employs a mode-locked laser system. The purpose-built interaction chamber, light delivery optics, and lens systems are described, and the first results are presented.

  18. Comparative study of the expression of ATF-3 and ATF-4 genes in vessels involved into atherosclerosis process and in psoriatic skin.

    PubMed

    Sobolev, V V; Starodubtseva, N L; Piruzyan, A L; Minnibaev, M T; Sautin, M E; Tumanov, V P; Bruskin, S A

    2011-10-01

    Expression of ATF-3 and ATF-4 genes was examined quantitatively by real-time PCR and changes in the expression of these genes in atherosclerotic lesions and in psoriatic skin were demonstrated. It was found that concomitant pathologies do not affect the expression of these genes. Opposite changes in the expression of ATF-3 and ATF-4 genes in atherosclerotic and psoriatic samples were revealed and a hypothesis was put forward that this parameter could be a criterion of pathological process in both diseases.

  19. Ceapins inhibit ATF6α signaling by selectively preventing transport of ATF6α to the Golgi apparatus during ER stress

    PubMed Central

    Gallagher, Ciara M; Walter, Peter

    2016-01-01

    The membrane-bound transcription factor ATF6α is activated by proteolysis during endoplasmic reticulum (ER) stress. ATF6α target genes encode foldases, chaperones, and lipid biosynthesis enzymes that increase protein-folding capacity in response to demand. The off-state of ATF6α is maintained by its spatial separation in the ER from Golgi-resident proteases that activate it. ER stress induces trafficking of ATF6α. We discovered Ceapins, a class of pyrazole amides, as selective inhibitors of ATF6α signaling that do not inhibit the Golgi proteases or other UPR branches. We show that Ceapins block ATF6α signaling by trapping it in ER-resident foci that are excluded from ER exit sites. Removing the requirement for trafficking by pharmacological elimination of the spatial separation of the ER and Golgi apparatus restored cleavage of ATF6α in the presence of Ceapins. Washout of Ceapins resensitized ATF6α to ER stress. These results suggest that trafficking of ATF6α is regulated by its oligomeric state. DOI: http://dx.doi.org/10.7554/eLife.11880.001 PMID:27435962

  20. p38beta2-mediated phosphorylation and sumoylation of ATF7 are mutually exclusive.

    PubMed

    Camuzeaux, Barbara; Diring, Jessica; Hamard, Pierre-Jacques; Oulad-Abdelghani, Mustapha; Donzeau, Mariel; Vigneron, Marc; Kedinger, Claude; Chatton, Bruno

    2008-12-26

    The ubiquitous activating transcription factor (ATF) 7 binds as a homodimer to the cAMP response element/TPA response element motifs present in the promoters of its target genes. ATF7 is homologous to ATF2 and heterodimerizes with Jun or Fos proteins, modulating their DNA-binding specificities. We previously demonstrated that TAF12, a component of the TFIID general transcription factor, mediates ATF7 transcriptional activity through direct interactions between the two proteins. By contrast, ATF7, but not ATF2, is modified in vivo by sumoylation, which restricts its subcellular localization, thereby inhibiting its transcriptional activity. In the present study, we dissect the mechanism of this functional switch. We characterized the multisite phosphorylation of the ATF7 activation domain and identified one of the involved kinase, p38beta2 mitogen-activated protein kinase. In addition, we show that epidermal growth factor treatment results in a two-step modification mechanism of ATF7 activation domain. The Thr53 residue is phosphorylated first by a presently unknown kinase, allowing p38beta2 mitogen-activated protein kinase to modify the Thr51 residue, excluding the sumoylation of ATF7 protein. The resulting activation of transcription is related to an increased association of TAF12 with this phosphorylated form of ATF7. Our data therefore conclusively establish that sumoylation and phosphorylation of ATF7 are two antagonistic posttranslational modifications.

  1. Damping in Space Constructions

    NASA Astrophysics Data System (ADS)

    de Vreugd, Jan; de Lange, Dorus; Winters, Jasper; Human, Jet; Kamphues, Fred; Tabak, Erik

    2014-06-01

    Monolithic structures are often used in optomechanical designs for space applications to achieve high dimensional stability and to prevent possible backlash and friction phenomena. The capacity of monolithic structures to dissipate mechanical energy is however limited due to the high Q-factor, which might result in high stresses during dynamic launch loads like random vibration, sine sweeps and shock. To reduce the Q-factor in space applications, the effect of constrained layer damping (CLD) is investigated in this work. To predict the damping increase, the CLD effect is implemented locally at the supporting struts in an existing FE model of an optical instrument. Numerical simulations show that the effect of local damping treatment in this instrument could reduce the vibrational stresses with 30-50%. Validation experiments on a simple structure showed good agreement between measured and predicted damping properties. This paper presents material characterization, material modeling, numerical implementation of damping models in finite element code, numerical results on space hardware and the results of validation experiments.

  2. Mutation of ATF6 causes autosomal recessive achromatopsia.

    PubMed

    Ansar, Muhammad; Santos-Cortez, Regie Lyn P; Saqib, Muhammad Arif Nadeem; Zulfiqar, Fareeha; Lee, Kwanghyuk; Ashraf, Naeem Mahmood; Ullah, Ehsan; Wang, Xin; Sajid, Sundus; Khan, Falak Sher; Amin-ud-Din, Muhammad; Smith, Joshua D; Shendure, Jay; Bamshad, Michael J; Nickerson, Deborah A; Hameed, Abdul; Riazuddin, Saima; Ahmed, Zubair M; Ahmad, Wasim; Leal, Suzanne M

    2015-09-01

    Achromatopsia (ACHM) is an early-onset retinal dystrophy characterized by photophobia, nystagmus, color blindness and severely reduced visual acuity. Currently mutations in five genes CNGA3, CNGB3, GNAT2, PDE6C and PDE6H have been implicated in ACHM. We performed homozygosity mapping and linkage analysis in a consanguineous Pakistani ACHM family and mapped the locus to a 15.12-Mb region on chromosome 1q23.1-q24.3 with a maximum LOD score of 3.6. A DNA sample from an affected family member underwent exome sequencing. Within the ATF6 gene, a single-base insertion variant c.355_356dupG (p.Glu119Glyfs*8) was identified, which completely segregates with the ACHM phenotype within the family. The frameshift variant was absent in public variant databases, in 130 exomes from unrelated Pakistani individuals, and in 235 ethnically matched controls. The variant is predicted to result in a truncated protein that lacks the DNA binding and transmembrane domains and therefore affects the function of ATF6 as a transcription factor that initiates the unfolded protein response during endoplasmic reticulum (ER) stress. Immunolabeling with anti-ATF6 antibodies showed localization throughout the mouse neuronal retina, including retinal pigment epithelium, photoreceptor cells, inner nuclear layer, inner and outer plexiform layers, with a more prominent signal in retinal ganglion cells. In contrast to cytoplasmic expression of wild-type protein, in heterologous cells ATF6 protein with the p.Glu119Glyfs*8 variant is mainly confined to the nucleus. Our results imply that response to ER stress as mediated by the ATF6 pathway is essential for color vision in humans.

  3. Bim and VDAC1 are hierarchically essential for mitochondrial ATF2 mediated cell death.

    PubMed

    Liu, Zhaoyun; Luo, Qianfu; Guo, Chunbao

    2015-01-01

    ATF2 mediated cytochrome c release is the formation of a channel with some unknown factors larger than that of the individual proteins. BHS-only proteins (BH3s), such as Bim, could induce BAX and VDAC, forming a new channel. According to this facts, we can speculated that there is possible signal relationship with BH3s and ATF2, which is associated with mitochondrial-based death programs. The growth inhibitory effects of mitochondrial ATF2 were tested in cancer cell lines B16F10, A549, EG7, and LL2. Apoptosis was measured by flow cytometry. The effects of ATF2 and levels of apoptosis regulatory proteins were measured by Western blotting. The interaction of proteins were evaluated by immunoprecipitation analysis. The in vivo antitumor activity of mitochondrial ATF2 were tested in xenograft B16F10 models. Genotoxic stress enabled mitochondrial ATF2 accumulation, perturbing the HK1-VDAC1 complex, increasing mitochondrial permeability, and promoting apoptosis. ATF2 inhibition strongly reduced the conformational activation of Bim, suggesting that Bim acts downstream of ATF2. Although Bim downregulation had no effect on ATF2 activation, Bim knockdown abolished VDAC1 activation; the failure of VDAC1 activation in Bim-depleted cells could be reversed by the BH3-only protein mimic ABT-737. We also demonstrate that silencing of ATF2 in B16F10 cells increases both the incidence and prevalence of tumor xenografts in vivo, whereas stably mitochondrial ATF2 transfection inhibited B16F10 tumor xenografts growth. Altogether, these results show that ATF2 is a component of the apoptosis machinery that involves a hierarchical contribution of ATF2, Bim, and VDAC1. Our data offer new insight into the mechanism of mitochondrial ATF2 in mitochondrial apoptosis.

  4. Fuel Cycle Research and Development Accident Tolerant Fuels Series 1 (ATF-1) Irradiation Testing FY 2016 Status Report

    SciTech Connect

    Core, Gregory Matthew

    2016-09-01

    This report contains a summary of irradiation testing of Fuel Cycle Research and Development (FCRD) Accident Tolerant Fuels Series 1 (ATF 1) experiments performed at Idaho National Laboratory (INL) in FY 2016. ATF 1 irradiation testing work performed in FY 2016 included design, analysis, and fabrication of ATF-1B drop in capsule ATF 1 series experiments and irradiation testing of ATF-1 capsules in the ATR.

  5. Damping of thermoacoustic oscillations

    NASA Technical Reports Server (NTRS)

    Tward, E.; Mason, P. V.

    1982-01-01

    A commonly encountered and troublesome problem in cryogenic systems is related to the occurrence of thermoacoustic oscillations (TAO). The oscillations are accompanied by large heat fluxes which can cause large increases in the boiloff from dewars. Such a boiloff can lead to a serious degradation in performance. It appears, therefore, highly advisable to incorporate mechanisms for damping TAO in those parts of the system where there oscillations might occur. The present investigation is concerned with the criteria for the design of such damping mechanisms. Attention is given to the theory regrading the suppression of TAO, a damper consisting of a capillary with a surge tank, and porous solid dampers.

  6. Rubber-coated bellows improves vibration damping in vacuum lines

    NASA Technical Reports Server (NTRS)

    Hegland, D. E.; Smith, R. J.

    1966-01-01

    Compact-vibration damping systems, consisting of rubber-coated metal bellows with a sliding O-ring connector, are used in vacuum lines. The device presents a metallic surface to the vacuum system and combines flexibility with the necessary stiffness. It protects against physical damage, reduces fatigue failure, and provides easy mating of nonparallel lines.

  7. The DAMPE Neutron Detector

    NASA Astrophysics Data System (ADS)

    Yan, Zhang; Tao, Ma; Yongyi, Huang

    2016-07-01

    The first Chinese space observatory DAMPE (DArk Matter Particle Explorer) was successfully launched on Dec. 17th, 2015. One major scientific object of DAMPE is to measure electrons between 5GeV to 10TeV with excellent energy resolution (1.5% at 800GeV) to search for possible dark matter signatures. The detector consists of four subsystems: a plastic scintillator detector (PSD), a silicon-tungsten tracker (STK), a BGO calorimeter (BGO), and a neutron detector (NUD). The NUD on board DAMPE is designed to detect moderated neutrons via the boron capture of thermal neutrons in boron-doped plastics. Given the fact that hadron showers initiated in the BGO calorimeter by incident nuclei tend to be followed by significantly more neutron activities comparing to electromagnetic cascades triggered by electrons, the NUD provides an additional order of magnitude hadron rejection capability to improve the overall e/p discrimination of DAMPE up to 10 ^{5}. Preliminary analysis of the in-orbit data is given, together with comparisons to the results obtained by a detailed GEANT4 simulation of the NUD instrument.

  8. Identification of ATF2 as a transcriptional regulator of renin gene.

    PubMed

    Desch, Michael; Hackmayer, Gerit; Todorov, Vladimir T

    2012-01-01

    The cAMP response element (enhCRE) in the distal enhancer regulatory region of renin gene is believed to play a major role in the control of renin transcription. enhCRE binds the CRE-binding protein (CREB), which is the main transcription factor target of cAMP signaling. Using the mouse renin-producing cell line As4.1 we found that activating transcription factor-2 (ATF2) also binds to enhCRE. N-terminal phosphorylation of ATF2, which controls its transactivation, is associated with downregulation of renin gene expression by the cytokine tumor necrosis factor-α (TNFα). The ubiquitin proteasome inhibitor MG132 also phosphorylates ATF2 and inhibits renin expression. Knockdown of ATF2 attenuated the suppression of renin gene expression by MG132, thus demonstrating that ATF2 mediates the inhibitory effect of MG132. In addition, MG132 increased the DNA-binding of ATF2 as well as the ratio of bound ATF2 to CREB. Using ATF2- and CREB-Gal4 fusion protein constructs coupled with luciferase reporter system we showed that ATF2 has a weaker transactivating capacity than CREB. These data suggest that ATF2 represses renin expression by drifting the transcriptional control of renin gene away from CREB. Accordingly, TNFα completely abrogated the cAMP-dependent stimulation of renin gene expression.

  9. Atf4 regulates chondrocyte proliferation and differentiation during endochondral ossification by activating Ihh transcription

    PubMed Central

    Wang, Weiguang; Lian, Na; Li, Lingzhen; Moss, Heather E.; Wang, Weixi; Perrien, Daniel S.; Elefteriou, Florent; Yang, Xiangli

    2009-01-01

    Activating transcription factor 4 (Atf4) is a leucine-zipper-containing protein of the cAMP response element-binding protein (CREB) family. Ablation of Atf4 (Atf4−/−) in mice leads to severe skeletal defects, including delayed ossification and low bone mass, short stature and short limbs. Atf4 is expressed in proliferative and prehypertrophic growth plate chondrocytes, suggesting an autonomous function of Atf4 in chondrocytes during endochondral ossification. In Atf4−/− growth plate, the typical columnar structure of proliferative chondrocytes is disturbed. The proliferative zone is shortened, whereas the hypertrophic zone is transiently expanded. The expression of Indian hedgehog (Ihh) is markedly decreased, whereas the expression of other chondrocyte marker genes, such as type II collagen (Col2a1), PTH/PTHrP receptor (Pth1r) and type X collagen (Col10a1), is normal. Furthermore, forced expression of Atf4 in chondrocytes induces endogenous Ihh mRNA, and Atf4 directly binds to the Ihh promoter and activates its transcription. Supporting these findings, reactivation of Hh signaling pharmacologically in mouse limb explants corrects the Atf4−/− chondrocyte proliferation and short limb phenotypes. This study thus identifies Atf4 as a novel transcriptional activator of Ihh in chondrocytes that paces longitudinal bone growth by controlling growth plate chondrocyte proliferation and differentiation. PMID:19906842

  10. Identification and characterization of a mitochondrial unfolded protein response transcription factor ATFS-1 in Litopenaeus vannamei.

    PubMed

    Chen, Yong-Gui; Yue, Hai-Tao; Zhang, Ze-Zhi; Yuan, Feng-Hua; Bi, Hai-Tao; Yuan, Kai; Weng, Shao-Ping; He, Jian-Guo; Chen, Yi-Hong

    2016-07-01

    A mitochondrial specific stress response termed mitochondrial unfolded protein response (UPR(mt)) is activated in responding to disturbance of protein homeostasis in mitochondria. The activating transcription factor associated with stress-1 (designated as ATFS-1) is the key regulator of UPR(mt). To investigating the roles of ATFS-1 (LvATFS-1) in Litopenaeus vannamei mitochondrial stress remission and immunity, it's full length cDNA was cloned. The open reading frame of LvATFS-1 was 1, 557 bp in length, deducing to a 268 amino acids protein. LvATFS-1 was highly expressed in muscle, hemocytes and eyestalk. Subcellular location assays showed that N-terminal of LvATFS-1 contained a mitochondrial targeting sequence, which could directed the fused EGFP located to mitochondria. And the C-terminal of LvATFS-1, which had a nuclear localization signal, expressed in nucleus. The in vitro experiments verified that LvATFS-1 could reduced the level of intracellular reactive oxygen species (ROS). And results of real-time RT-PCR indicated that LvATFS-1 might scavenge excess ROS via ROS-eliminating genes regulation. Reporter gene assays showed that LvATFS-1 could upregulated the expression of the antimicrobial peptide genes in Drosophila Schneider 2 cells. Results of real-time RT-PCR showed that Vibrio alginolyticus or white spot syndrome virus (WSSV) infection induced the expression of LvATFS-1. And knocked-down LvATFS-1 by RNAi resulted in a higher cumulative mortality of L. vannamei upon V. alginolyticus or WSSV infection. These results suggested that LvATFS-1 not only rolled in mitochondrial specific stress responding, but also important for L. vannamei immunologic defence.

  11. Nutational Damping Revisited

    NASA Astrophysics Data System (ADS)

    Burns, J. A.; Sharma, I.

    2000-10-01

    Motivated by the recent detection of complex rotational states for several asteroids and comets, as well as by the ongoing and planned spacecraft missions to such bodies, which should allow their rotational states to be accurately determined, we revisit the problem of the nutational damping of small solar system bodies. The nutational damping of asteroids has been approximately analyzed by Prendergast (1958), Burns and Safronov (1973), and Efroimsky and Lazarian (2000). Many other similar dynamical studies concern planetary wobble decay (e.g., Peale 1973; Yoder and Ward 1979), interstellar dust grain alignment (e.g., Purcell 1979; Lazarian and Efroimsky 1999) and damping of Earth's Chandler wobble (Lambeck 1980). Recall that rotational energy loss for an isolated body aligns the body's angular momentum vector with its axis of maximum inertia. Assuming anelastic dissipation, simple dimensional analysis determines a functional form of the damping timescale, on which all the above authors agree. However, the numerical coefficients of published results are claimed to differ by orders of magnitude. Differences have been ascribed to absent physics, to solutions that fail to satisfy boundary conditions perfectly, and to unphysical choices for the Q parameter. The true reasons for the discrepancy are unclear since, despite contrary claims, the full 3D problem (nutational damping of an anelastic ellipsoid) is analytically intractable so far. To move the debate forward, we compare the solution of a related 2D problem to the expressions found previously, and we present results from a finite element model. On this basis, we feel that previous rates for the decay of asteroidal tumbling (Harris 1994), derived from Burns and Safronov (1973), are likely to be accurate, at least to a factor of a few. Funded by NASA.

  12. Damping formulas and experimental values of damping in flutter models

    NASA Technical Reports Server (NTRS)

    Coleman, Robert P

    1940-01-01

    The problem of determining values of structural damping for use in flutter calculations is discussed. The concept of equivalent viscous damping is reviewed and its relation to the structural damping coefficient g introduced in NACA Technical Report No. 685 is shown. The theory of normal modes is reviewed and a number of methods are described for separating the motions associated with different modes. Equations are developed for use in evaluating the damping parameters from experimental data. Experimental results of measurements of damping in several flutter models are presented.

  13. ATF4 is involved in the regulation of simulated microgravity induced integrated stress response

    NASA Astrophysics Data System (ADS)

    Li, Yingxian; Li, Qi; Wang, Xiaogang; Sun, Qiao; Wan, Yumin; Li, Yinghui; Bai, Yanqiang

    Objective: Many important metabolic and signaling pathways have been identified as being affected by microgravity, thereby altering cellular functions such as proliferation, differentiation, maturation and cell survival. It has been demonstrated that microgravity could induce all kinds of stress response such as endoplasmic reticulum stress and oxidative stress et al. ATF4 belongs to the ATF/CREB family of basic region leucine zipper transcription factors. ATF4 is induced by stress signals including anoxia/hypoxia, ER stress, amino acid deprivation and oxidative stress. ATF4 regulates the expression of genes involved in oxidative stress, amino acid synthesis, differentiation, metastasis and angiogenesis. The aim of this study was to examine the changes of ATF4 under microgravity, and to investigate the role of ATF4 in microgravity induced stress. MethodsMEF cells were cultured in clinostat to simulate microgravity. Reverse transcription polymerase chain reaction (RT-PCR) and western blotting were used to examine mRNA and protein levels of ATF4 expression under simulated microgravity in MEF cells. ROS levels were measured with the use of the fluorescent signal H2DCF-DA. GFP-XBP1 stably transfected cell lines was used to detect the extent of ER stress under microgravity by the intensity of GFP. Dual luciferase reporter assay was used to detect the activity of ATF4. Co-immunoprecipitation was performed to analyze protein interaction. Results: ATF4 protein levels in MEF cells increased under simulated microgravity. However, ATF4 mRNA levels were consistent. XBP1 splicing can be induced due to ER stress caused by simulated microgravity. At the same time, ROS levels were also increased. Increased ATF4 could promote the expression of CHOP, which is responsible for cell apoptosis. ATF4 also play an important role in cellular anti-oxidant stress. In ATF4 -/-MEF cells, the ROS levels after H2O2 treatment were obviously higher than that of wild type cells. HDAC4 was

  14. Transforming growth factor-beta1 regulation of ATF-3 and identification of ATF-3 target genes in breast cancer cells.

    PubMed

    Kwok, Sukyee; Rittling, Susan R; Partridge, Nicola C; Benson, Chellakkan S; Thiyagaraj, Mayuranathan; Srinivasan, Narasimhan; Selvamurugan, Nagarajan

    2009-10-01

    Transforming growth factor-beta1 (TGF-beta1) is a crucial molecule for stimulation of breast cancer invasion and formation of bone metastases. The molecular mechanisms of how TGF-beta1 mediates these effects have yet to be completely determined. We have found that activating transcription factor-3 (ATF-3) is strongly stimulated and its level is sustained by TGF-beta1 in highly invasive and metastatic human breast cancer (MDA-MB231) and in mouse mammary pad tumor cells (r3T). ATF-3 is also overexpressed in human primary breast cancer tissue. Overexpression of ATF-3 increased normal human mammary epithelial cell number and DNA synthesis suggesting a role for ATF-3 in cell proliferation. The functional role of ATF-3 in breast cancer progression was determined by the RNA interference technique. Knockdown of ATF-3 by ATF-3 shRNA in MDA-MB231 cells decreased expression of cell cycle gene, cyclin A1 in MDA-MB231 cells. ATF-3 shRNA also decreased expression of an invasive and metastatic gene, matrix metalloproteinase-13 (MMP-13; collagenase-3) in these cells. Chromatin immunoprecipitation experiments identified the direct physical interaction of ATF-3 protein on the human MMP-13 promoter. Thus, the dysregulation of ATF-3 by TGF-beta1 is likely to activate cyclin A1 and MMP-13 genes in breast cancer cells and that would be key to the subsequent cancer cell invasion and metastasis. (c) 2009 Wiley-Liss, Inc.

  15. Computer simulation of magnetic field circuits in ATF

    SciTech Connect

    White, J.A.; Googe, J.M.; Nickels, L.E.

    1983-01-01

    The proposed design of the Advanced Toroidal Facility (ATF) contains several closely coupled magnetic field circuits that are being modeled using the SUPER*SCEPTRE computer program in order to predict their transient behavior. The results of this transient analysis study will be used to determine component values and/or special precautions that may be required for power supply and other circuit element protection due to the mutual coupling between circuits. ATF is a continuous-coil torsatron device using resistive coils in a pulsed mode of operation in which a current fluctuation in one coil induces voltages in the other circuit element protection due to the mutual coupling between circuits. ATF is a continuous-coil torsatron device using resistive coils in a pulsed mode of operation in which a current fluctuation in one coil induces voltages in the other circuit that may not be desirable. The model contains the solid-state power supplies' equivalent circuits, the resistance and self-inductance of each magnetic field coil, and the mutual inductances of every coil combination. The SUPER*SCEPTRE program allows for the direct input of all electrical components as well as the mutual inductances. The power supply voltages are entered as preprogrammed wave shapes designed to achieve the desired magnetic field strengths. The outputs of this program are tables and plots of voltages and currents associated with each circuit component.

  16. Impurity and recycling control with gettering in ATF

    SciTech Connect

    Simpkins, J.E.; Mioduszewski, P.K.; Isler, R.C.

    1991-01-01

    The vacuum vessel of the Advanced Toroidal Facility (ATF) is Ti-gettered with a surface coverage of 70%. The major effects of gettering are: (1) reduction of the oxygen, carbon, and nitrogen content in the plasma and (2) improved density control due to wall pumping of the working gas hydrogen. The overall leak rate in ATF is 2{times}10{sup {minus}4} Torr-l/s which is too high for successful plasma operation. Ti-gettering is routinely employed every morning prior to operation and compensates for this shortcoming by reducing the partial pressure of nitrogen and other residual gas components to the low 10{sup {minus}9} Torr range which is close to the RGA background pressure. Rate-of-rise measurements at this stage show only argon and some methane. The argon is used to monitor the leak rate. In addition to impurity reduction, gettering leads to low recycling of the working gas which appears to be crucial for density control in ATF. The capacity of the gettered surface is large enough to show a strong effect even after 24 hours. An extensive data base on the short-term and long-term effects of gettering on the residual gas composition and its effects on plasma performance has been established over the past three years and will be discussed in this paper. 9 refs., 7 figs.

  17. Cavity Beam Position Monitor System for ATF2

    SciTech Connect

    Boogert, Stewart; Boorman, Gary; Swinson, Christina; Ainsworth, Robert; Molloy, Stephen; Aryshev, Alexander; Honda, Yosuke; Tauchi, Toshiaki; Terunuma, Nobuhiro; Urakawa, Junji; Frisch, Josef; May, Justin; McCormick, Douglas; Nelson, Janice; Smith, Tonee; White, Glen; Woodley, Mark; Heo, Ae-young; Kim, Eun-San; Kim, Hyoung-Suk; Kim, Youngim; /Kyungpook Natl. U. /University Coll. London /Kyungpook Natl. U. /Fermilab /Pohang Accelerator Lab.

    2012-07-09

    The Accelerator Test Facility 2 (ATF2) in KEK, Japan, is a prototype scaled demonstrator system for the final focus required for a future high energy lepton linear collider. The ATF2 beam-line is instrumented with a total of 38 C and S band resonant cavity beam position monitors (CBPM) with associated mixer electronics and digitizers. The current status of the BPM system is described, with a focus on operational techniques and performance. The ATF2 C-band system is performing well, with individual CBPM resolution approaching or at the design resolution of 50 nm. The changes in the CBPM calibration observed over three weeks can probably be attributed to thermal effects on the mixer electronics systems. The CW calibration tone power will be upgraded to monitor changes in the electronics gain and phase. The four S-band CBPMs are still to be investigated, the main problem associated with these cavities is a large cross coupling between the x and y ports. This combined with the large design dispersion in that degion makes the digital signal processing difficult, although various techniques exist to determine the cavity parameters and use these coupled signals for beam position determination.

  18. Green tea catechin (-)-epicatechin gallate induces tumour suppressor protein ATF3 via EGR-1 activation.

    PubMed

    Cho, Kyou-Nam; Sukhthankar, Mugdha; Lee, Seong-Ho; Yoon, Joo-Heon; Baek, Seung Joon

    2007-11-01

    Epicatechin gallate (ECG) is the third major catechin component in green tea, but it shows strong biological activity in some aspects, including apoptosis, cell growth inhibition, and membrane transport system in various cells. We previously reported that ECG induces activating transcription factor 3 (ATF3), which is involved in pro-apoptosis in HCT-116 cells. In this report, we present a molecular mechanism by which ECG induces ATF3 expression at the transcriptional level. We found that Sp3 contributed to the basal expression of the ATF3 gene, whereas EGR-1 played an important role in ECG-induced ATF3 expression in HCT-116 cells, as assessed by EMSA and co-transfection experiments. These results suggested that EGR-1, a tumour suppressor protein, could substantiate ECG's role of ATF3 expression in human colorectal cancer cells. We also found that pro-oxidant activity of ECG contributed to ECG-induced ATF3 expression.

  19. Surviving Stress: Modulation of ATF4-Mediated Stress Responses in Normal and Malignant Cells.

    PubMed

    Wortel, Inge M N; van der Meer, Laurens T; Kilberg, Michael S; van Leeuwen, Frank N

    2017-08-07

    Activating transcription factor 4 (ATF4) is a stress-induced transcription factor that is frequently upregulated in cancer cells. ATF4 controls the expression of a wide range of adaptive genes that allow cells to endure periods of stress, such as hypoxia or amino acid limitation. However, under persistent stress conditions, ATF4 promotes the induction of apoptosis. Recent advances point to a role for post-translational modifications (PTMs) and epigenetic mechanisms in balancing these pro- and anti-survival effects of ATF4. We review here how PTMs and epigenetic modifiers associated with ATF4 may be exploited by cancer cells to cope with cellular stress conditions that are intrinsically associated with tumor growth. Identification of mechanisms that modulate ATF4-mediated transcription and its effects on cellular metabolism may uncover new targets for cancer treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Suppression of x-rays generated by runaway electrons in ATF

    SciTech Connect

    Rasmussen, D.A.; England, A.C.; Eberle, C.C.; Devan, W.R.; Harris, J.H.; Jernigan, T.C.; Kindsfather, R.R.; Morris, R.N.; Murakami, M.; Neilson, G.H.

    1987-01-01

    X-ray emission from runaway electrons on ATF is a serious issue. Runaway suppression techniques used on Heliotron-E are not adequate for ATF. Three approaches have been developed to suppress runaway production. Monitoring devices have been installed in occupied areas and personnel access and exposure will be limited. Additional shielding will be added as required. These systems will be ready for installation and testing on ATF prior to commissioning or first plasma operation.

  1. Multiple roles for acetylation in the interaction of p300 HAT with ATF-2.

    PubMed

    Karanam, Balasubramanyam; Wang, Ling; Wang, Dongxia; Liu, Xin; Marmorstein, Ronen; Cotter, Robert; Cole, Philip A

    2007-07-17

    The transcriptional coactivator paralogues p300 and CBP contain acetyltransferase domains (HAT) and catalyze the lysine acetylation of histones and other proteins as an important aspect of their functions. Prior studies revealed that the basic leucine zipper domain (b-ZIP) of transcription factor ATF-2 (also called CRE-BP1) can interact with the CBP HAT domain. In this study, we have examined the ATF-2 b-ZIP interaction with the p300 HAT domain and shown that p300 HAT autoacetylation can enhance the binding affinity. Pull-down assays revealed that hyperacetylated p300 HAT is more efficiently retained by immobilized ATF-2 b-ZIP than hypoacetylated p300 HAT. Loop deleted p300 HAT lacking autoacetylation was retained about as well as hyperacetylated p300 HAT, suggesting that the loop and ATF-2 compete for p300 HAT binding. While ATF-2 b-ZIP is a weak inhibitor of hypoacetylated p300 HAT acetylation of a histone H4 peptide, hyperacetylated p300 HAT is much more potently inhibited by ATF-2 b-ZIP. Moreover, we showed that ATF-2 b-ZIP could serve as an acetyltransferase substrate for p300 HAT. Using mass spectrometry, two p300 HAT lysine acetylation sites were mapped in ATF-2 b-ZIP. Immunoprecipitation-Western blot analysis with anti-acetyl-lysine antibody revealed that ATF-2 can undergo reversible acetylation in vivo. Mutational analysis of the two ATF-2 b-ZIP acetylation sites revealed their potential contributions to ATF-2-mediated transcriptional activation. Taken together, these studies suggest multiple roles for protein acetylation in the regulation of transcription by p300/CBP and ATF-2.

  2. Damping of thermoacoustic oscillations

    SciTech Connect

    Tward, E.; Mason, P.V.

    1982-01-01

    The design criteria for the damping mechanism required to suppress thermoacoustic oscillation is discussed. The theory is presented with formulas stated. Incident acoustic wave generation is illustrated with the pipes and damper positions indicated. Capillary and surge tank functions are described with illustrations and formulas relevant to the thermoacoustic oscillation process. Porous solid dampers were introduced which used glass wool. The problem of damping of the thermoacoustic oscillation appears to be solvable in many applications through the use of an orifice and surge tank. This device can be installed either as a termination in an oscillating pipe or in a branch. It is suggested that such a device be incorporated into cryogenic systems whenever thermoacoustic oscillations could cause a problem.

  3. Increased expression of tyrosine hydroxylase and anomalous neurites in catecholaminergic neurons of ATF-2 null mice.

    PubMed

    Kojima, Masayo; Suzuki, Takahiro; Maekawa, Toshio; Ishii, Shunsuke; Sumi-Ichinose, Chiho; Nomura, Takahide; Ichinose, Hiroshi

    2008-02-15

    ATF-2/CRE-BP1 was originally identified as a cAMP-responsive element (CRE) binding protein abundant in the brain. We previously reported that phosphorylation of ATF-2 increased the expression of tyrosine hydroxylase (TH), which is the rate-limiting enzyme for catecholamine biosynthesis, directly acting on the CRE in the promoter region of the TH gene in PC12D cells (Suzuki et al. [2002] J. Biol. Chem. 277:40768-40774). To examine the role of ATF-2 on transcriptional control of the TH gene in the brain, we investigated the TH expression in ATF-2-/- mice. We found that TH expression was greatly increased in medulla oblongata and locus ceruleus of the ATF-2-deficient embryos. Ectopic expression of TH was observed in the raphe magnus nucleus, where serotonergic neural cell bodies are located. Interestingly, A10 dorsal neurons were lost in the embryos of ATF-2-/- mice. There was no difference in the TH immunoreactivity in the olfactory bulb. The data showed that alteration in TH expression by absence of ATF-2 gradually declined from caudal to rostral part of the brain. We also found anomalous neurite extension in catecholaminergic neurons of ATF-2 null mice, i.e., increased dendritic arborization and shortened axons. These data suggest that ATF-2 plays critical roles for proper expression of the TH gene and for neurite extension of catecholaminergic neurons, possibly through a repressor-like action. (c) 2007 Wiley-Liss, Inc.

  4. Glucose deprivation induces chemoresistance in colorectal cancer cells by increasing ATF4 expression

    PubMed Central

    Hu, Ya-Ling; Yin, Yuan; Liu, He-Yong; Feng, Yu-Yang; Bian, Ze-Hua; Zhou, Le-Yuan; Zhang, Ji-Wei; Fei, Bo-Jian; Wang, Yu-Gang; Huang, Zhao-Hui

    2016-01-01

    AIM: To investigate the role of activating transcription factor 4 (ATF4) in glucose deprivation (GD) induced colorectal cancer (CRC) drug resistance and the mechanism involved. METHODS: Chemosensitivity and apoptosis were measured under the GD condition. Inhibition of ATF4 using short hairpin RNA in CRC cells under the GD condition and in ATF4-overexpressing CRC cells was performed to identify the role of ATF4 in the GD induced chemoresistance. Quantitative real-time RT-PCR and Western blot were used to detect the mRNA and protein expression of drug resistance gene 1 (MDR1), respectively. RESULTS: GD protected CRC cells from drug-induced apoptosis (oxaliplatin and 5-fluorouracil) and induced the expression of ATF4, a key gene of the unfolded protein response. Depletion of ATF4 in CRC cells under the GD condition can induce apoptosis and drug re-sensitization. Similarly, inhibition of ATF4 in the ATF4-overexpressing CRC cells reintroduced therapeutic sensitivity and apoptosis. In addition, increased MDR1 expression was observed in GD-treated CRC cells. CONCLUSION: These data indicate that GD promotes chemoresistance in CRC cells through up-regulating ATF4 expression. PMID:27468213

  5. ATF3 inhibits adipocyte differentiation of 3T3-L1 cells

    SciTech Connect

    Jang, Min Kyung; Kim, Cho Hee; Seong, Je Kyung; Jung, Myeong Ho

    2012-04-27

    Highlights: Black-Right-Pointing-Pointer Overexpression of ATF3 inhibits adipocyte differentiation in 3T3-L1 cells. Black-Right-Pointing-Pointer Overexpression of ATF3 represses C/EBP{alpha} expression. Black-Right-Pointing-Pointer ATF3 directly binds to mouse C/EBP{alpha} promoter spanning from -1928 to -1907. Black-Right-Pointing-Pointer ATF3 may play a role in hypoxia-mediated inhibition of adipocyte differentiation. -- Abstract: ATF3 is a stress-adaptive gene that regulates proliferation or apoptosis under stress conditions. However, the role of ATF3 is unknown in adipocyte cells. Therefore, in this study, we investigated the functional role of ATF3 in adipocytes. Both lentivirus-mediated overexpression of ATF3 and stably-overexpressed ATF3 inhibited adipocyte differentiation in 3T3-L1 cells, as revealed by decreased lipid staining with oil red staining and reduction in adipogenic genes. Thapsigargin treatment and overexpression of ATF3 decreased C/EBP{alpha} transcript and repressed the activity of the 3.6-kb mouse C/EBP{alpha} promoter, demonstrating that ATF3 downregulates C/EBP{alpha} expression. Transfection studies using mutant constructs containing 5 Prime -deletions in the C/EBP{alpha} promoter revealed that a putative ATF/CRE element, GGATGTCA, is located between -1921 and -1914. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay demonstrated that ATF3 directly binds to mouse C/EBP{alpha} promoter spanning from -1928 to -1907. Both chemical hypoxia-mimetics or physical hypoxia led to reduce the C/EBP{alpha} mRNA and repress the promoter activity of the C/EBP{alpha} gene, whereas increase ATF3 mRNA, suggesting that ATF3 may contribute to the inhibition of adipocyte differentiation in hypoxia through downregulation of C/EBP{alpha} expression. Collectively, these results demonstrate that ATF3 represses the C/EBP{alpha} gene, resulting in inhibition of adipocyte differentiation, and thus plays a role in hypoxia-mediated inhibition

  6. A functional interaction between ATF7 and TAF12 that is modulated by TAF4.

    PubMed

    Hamard, Pierre-Jacques; Dalbies-Tran, Rozenn; Hauss, Charlotte; Davidson, Irwin; Kedinger, Claude; Chatton, Bruno

    2005-05-12

    The ATF7 proteins, which are members of the cyclic AMP responsive binding protein (CREB)/activating transcription factor (ATF) family of transcription factors, display quite versatile properties: they can interact with the adenovirus E1a oncoprotein, mediating part of its transcriptional activity; they heterodimerize with the Jun, Fos or related transcription factors, likely modulating their DNA-binding specificity; they also recruit to the promoter a stress-induced protein kinase (JNK2). In the present study, we investigate the functional relationships of ATF7 with hsTAF12 (formerly hsTAF(II)20/15), which has originally been identified as a component of the general transcription factor TFIID. We show that overexpression of hsTAF12 potentiates ATF7-induced transcriptional activation through direct interaction with ATF7, suggesting that TAF12 is a functional partner of ATF7. In support of this conclusion, chromatin immunoprecipitation experiments confirm the interaction of ATF7 with TAF12 on an ATF7-responsive promoter, in the absence of any artificial overexpression of both proteins. We also show that the TAF12-dependent transcriptional activation is competitively inhibited by TAF4. Although both TAF12 isoforms (TAF12-1 and -2, formerly TAF(II)20 and TAF(II)15) interact with the ATF7 activation region through their histone-fold domain, only the largest, hsTAF12-1, mediates transcriptional activation through its N-terminal region.

  7. Development of Electrical Capacitance Sensors for Accident Tolerant Fuel (ATF) Testing at the Transient Reactor Test (TREAT) Facility

    SciTech Connect

    Liu, Maolong; Ryals, Matthew; Ali, Amir; Blandford, Edward; Jensen, Colby; Condie, Keith; Svoboda, John; O'Brien, Robert

    2016-08-01

    A variety of instruments are being developed and qualified to support the Accident Tolerant Fuels (ATF) program and future transient irradiations at the Transient Reactor Test (TREAT) facility at Idaho National Laboratory (INL). The University of New Mexico (UNM) is working with INL to develop capacitance-based void sensors for determining the timing of critical boiling phenomena in static capsule fuel testing and the volume-averaged void fraction in flow-boiling in-pile water loop fuel testing. The static capsule sensor developed at INL is a plate-type configuration, while UNM is utilizing a ring-type capacitance sensor. Each sensor design has been theoretically and experimentally investigated at INL and UNM. Experiments are being performed at INL in an autoclave to investigate the performance of these sensors under representative Pressurized Water Reactor (PWR) conditions in a static capsule. Experiments have been performed at UNM using air-water two-phase flow to determine the sensitivity and time response of the capacitance sensor under a flow boiling configuration. Initial measurements from the capacitance sensor have demonstrated the validity of the concept to enable real-time measurement of void fraction. The next steps include designing the cabling interface with the flow loop at UNM for Reactivity Initiated Accident (RIA) ATF testing at TREAT and further characterization of the measurement response for each sensor under varying conditions by experiments and modeling.

  8. Cadmium interferes with the degradation of ATF5 via a post-ubiquitination step of the proteasome degradation pathway

    SciTech Connect

    Uekusa, Hiroyuki; Namimatsu, Mihoko; Hiwatashi, Yusuke; Akimoto, Takuya; Nishida, Tamotsu; Takahashi, Shigeru Takahashi, Yuji

    2009-03-13

    ATF5 is a member of the CREB/ATF family of transcription factors. In the current study, using a transient transfection system to express FLAG epitope fusion proteins of ATF5, we have shown that CdCl{sub 2} or NaAsO{sub 3} increases the protein levels of ATF5 in cells, and that cadmium stabilizes the ATF5 protein. Proteasome inhibitors had a similar effect to cadmium on the cellular accumulation of ATF5. Proteasome inhibition led to an increase in ubiquitinated ATF5, while cadmium did not appear to reduce the extent of ATF5 ubiquitination. ATF5 contains a putative nuclear export signal within its N-terminus. We demonstrated that whereas deletion of N-terminal region resulted in a increase of ATF5 levels, this region does not appear to be involved in the ubiquitination of ATF5. These results indicate that ATF5 is targeted for degradation by the ubiquitin-proteasome pathway, and that cadmium slows the rate of ATF5 degradation via a post-ubiquitination mechanism.

  9. A Flight Simulator for ATF2 - A Mechanism for International Collaboration in the Writing and Deployment of Online Beam Dynamics Algorithms

    SciTech Connect

    White, Glen; Molloy, Stephen; Seryi, Andrei; Schulte, Daniel; Tomas, Rogelio; Kuroda, Shigeru; Bambade, Philip; Renier, Yves; /Orsay, LAL

    2008-07-25

    The goals of ATF2 are to test a novel compact final focus optics design with local chromaticity correction intended for use in future linear colliders. The newly designed extraction line and final focus system will be used to produce a 37nm vertical waist from an extracted beam from the ATF ring of {approx}30nm vertical normalized emittance, and to stabilize it at the IP-waist to the {approx}2nm level. Static and dynamic tolerances on all accelerator components are very tight; the achievement of the ATF2 goals is reliant on the application of multiple high-level beam dynamics control algorithms to align and tune the electron beam in the extraction line and final focus system. Much algorithmic development work has been done in Japan and by colleagues in collaborating nations in North America and Europe. We describe here development work towards realizing a 'flight simulator' environment for the shared development and implementation of beam dynamics code. This software exists as a 'middle-layer' between the lower-level control systems (EPICS and V-SYSTEM) and the multiple higher-level beam dynamics modeling tools in use by the three regions (SAD, Lucretia, PLACET, MAD...).

  10. On damping mechanisms in beams

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Inman, D. J.

    1991-01-01

    A partial differential equation model of a cantilevered beam with a tip mass at its free end is used to study damping in a composite. Four separate damping mechanisms consisting of air damping, strain rate damping, spatial hysteresis and time hysteresis are considered experimentally. Dynamic tests were performed to produce time histories. The time history data is then used along with an approximate model to form a sequence of least squares problems. The solution of the least squares problem yields the estimated damping coefficients. The resulting experimentally determined analytical model is compared with the time histories via numerical simulation of the dynamic response. The procedure suggested here is compared with a standard modal damping ratio model commonly used in experimental modal analysis.

  11. On damping mechanisms in beams

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Inman, D. J.

    1989-01-01

    A partial differential equation model of a cantilevered beam with a tip mass at its free end is used to study damping in a composite. Four separate damping mechanisms consisting of air damping, strain rate damping, spatial hysteresis and time hysteresis are considered experimentally. Dynamic tests were performed to produce time histories. The time history data is then used along with an approximate model to form a sequence of least squares problems. The solution of the least squares problem yields the estimated damping coefficients. The resulting experimentally determined analytical model is compared with the time histories via numerical simulation of the dynamic response. The procedure suggested here is compared with a standard modal damping ratio model commonly used in experimental modal analysis.

  12. Magnetically Damped Furnace (MDF)

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The Magnetically Damped Furnace (MDF) breadboard is being developed in response to NASA's mission and goals to advance the scientific knowledge of microgravity research, materials science, and related technologies. The objective of the MDF is to dampen the fluid flows due to density gradients and surface tension gradients in conductive melts by introducing a magnetic field during the sample processing. The MDF breadboard will serve as a proof of concept that the MDF performance requirements can be attained within the International Space Station resource constraints.

  13. Magnetically Damped Furnace (MDF)

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The Magnetically Damped Furnace (MDF) breadboard is being developed in response to NASA's mission and goals to advance the scientific knowledge of microgravity research, materials science, and related technologies. The objective of the MDF is to dampen the fluid flows due to density gradients and surface tension gradients in conductive melts by introducing a magnetic field during the sample processing. The MDF breadboard will serve as a proof of concept that the MDF performance requirements can be attained within the International Space Station resource constraints.

  14. The Joint Damping Experiment (JDX)

    NASA Technical Reports Server (NTRS)

    Folkman, Steven L.; Bingham, Jeff G.; Crookston, Jess R.; Dutson, Joseph D.; Ferney, Brook D.; Ferney, Greg D.; Rowsell, Edwin A.

    1997-01-01

    The Joint Damping Experiment (JDX), flown on the Shuttle STS-69 Mission, is designed to measure the influence of gravity on the structural damping of a high precision three bay truss. Principal objectives are: (1) Measure vibration damping of a small-scale, pinjointed truss to determine how pin gaps give rise to gravity-dependent damping rates; (2) Evaluate the applicability of ground and low-g aircraft tests for predicting on-orbit behavior; and (3) Evaluate the ability of current nonlinear finite element codes to model the dynamic behavior of the truss. Damping of the truss was inferred from 'Twang' tests that involve plucking the truss structure and recording the decay of the oscillations. Results are summarized as follows. (1) Damping, rates can change by a factor of 3 to 8 through changing the truss orientation; (2) The addition of a few pinned joints to a truss structure can increase the damping by a factor as high as 30; (3) Damping is amplitude dependent; (4) As gravity induced preloads become large (truss long axis perpendicular to gravity vector) the damping is similar to non-pinjointed truss; (5) Impacting in joints drives higher modes in structure; (6) The torsion mode disappears if gravity induced preloads are low.

  15. Antenna Test Facility (ATF): User Test Planning Guide

    NASA Technical Reports Server (NTRS)

    Lin, Greg

    2011-01-01

    Test process, milestones and inputs are unknowns to first-time users of the ATF. The User Test Planning Guide aids in establishing expectations for both NASA and non-NASA facility customers. The potential audience for this guide includes both internal and commercial spaceflight hardware/software developers. It is intended to assist their test engineering personnel in test planning and execution. Material covered includes a roadmap of the test process, roles and responsibilities of facility and user, major milestones, facility capabilities, and inputs required by the facility. Samples of deliverables, test article interfaces, and inputs necessary to define test scope, cost, and schedule are included as an appendix to the guide.

  16. The atf2 gene is involved in triacylglycerol biosynthesis and accumulation in the oleaginous Rhodococcus opacus PD630.

    PubMed

    Hernández, Martín A; Arabolaza, Ana; Rodríguez, Eduardo; Gramajo, Hugo; Alvarez, Héctor M

    2013-03-01

    Rhodococcus opacus PD630 is an oleaginous bacterium able to accumulate large amounts of triacylglycerols (TAG) in different carbon sources. The last reaction for TAG biosynthesis is catalyzed by the bifunctional wax ester synthase/acyl-CoA:diacylglycerol acyltransferase (WS/DGAT) enzymes encoded by atf genes. R. opacus PD630 possesses at least 17 putative atf homologous genes in its genome, but only atf1 and atf2 exhibited a significant DGAT activity when expressed in E. coli, as revealed in a previous study. The contribution of atf1 gene to TAG accumulation by strain PD630 has been demonstrated previously, although additional Atfs may also contribute to lipid accumulation, since the atf1-disrupted mutant is still able to produce significant amounts of TAG (Alvarez et al., Microbiology 154:2327-2335, 2008). In this study, we investigated the in vivo role of atf2 gene in TAG accumulation by R. opacus PD630 by using different genetic strategies. The atf2-disrupted mutant exhibited a decrease in TAG accumulation (up to 25-30 %, w/w) and an approximately tenfold increase in glycogen formation in comparison with the wild-type strain. Surprisingly, in contrast to single mutants, a double mutant generated by the disruption of atf1 and atf2 genes only showed a very low effect in TAG and in glycogen accumulation under lipid storage conditions. Overexpression of atf1 and atf2 genes in strain PD630 promoted an increase of approximately 10 % (w/w) in TAG accumulation, while heterologous expression of atf2 gene in Mycobacterium smegmatis caused an increase in TAG accumulation during cultivation in nitrogen-rich media. This study demonstrated that, in addition to atf1 gene, atf2 is actively involved in TAG accumulation by the oleaginous R. opacus PD630.

  17. ATF4-dependent induction of heme oxygenase 1 prevents anoikis and promotes metastasis

    PubMed Central

    Dey, Souvik; Sayers, Carly M.; Verginadis, Ioannis I.; Lehman, Stacey L.; Cheng, Yi; Cerniglia, George J.; Tuttle, Stephen W.; Feldman, Michael D.; Zhang, Paul J.L.; Fuchs, Serge Y.; Diehl, J. Alan; Koumenis, Constantinos

    2015-01-01

    The integrated stress response (ISR) is a critical mediator of cancer cell survival, and targeting the ISR inhibits tumor progression. Here, we have shown that activating transcription factor 4 (ATF4), a master transcriptional effector of the ISR, protects transformed cells against anoikis — a specialized form of apoptosis — following matrix detachment and also contributes to tumor metastatic properties. Upon loss of attachment, ATF4 activated a coordinated program of cytoprotective autophagy and antioxidant responses, including induced expression of the major antioxidant enzyme heme oxygenase 1 (HO-1). HO-1 upregulation was the result of simultaneous activation of ATF4 and the transcription factor NRF2, which converged on the HO1 promoter. Increased levels of HO-1 ameliorated oxidative stress and cell death. ATF4-deficient human fibrosarcoma cells were unable to colonize the lungs in a murine model, and reconstitution of ATF4 or HO-1 expression in ATF4-deficient cells blocked anoikis and rescued tumor lung colonization. HO-1 expression was higher in human primary and metastatic tumors compared with noncancerous tissue. Moreover, HO-1 expression correlated with reduced overall survival of patients with lung adenocarcinoma and glioblastoma. These results establish HO-1 as a mediator of ATF4-dependent anoikis resistance and tumor metastasis and suggest ATF4 and HO-1 as potential targets for therapeutic intervention in solid tumors. PMID:26011642

  18. Functional Contribution of the Transcription Factor ATF4 to the Pathogenesis of Amyotrophic Lateral Sclerosis

    PubMed Central

    Matus, Soledad; Lopez, Estefanía; Valenzuela, Vicente; Nassif, Melissa; Hetz, Claudio

    2013-01-01

    Endoplasmic reticulum (ER) stress represents an early pathological event in amyotrophic lateral sclerosis (ALS). ATF4 is a key ER stress transcription factor that plays a role in both adaptation to stress and the activation of apoptosis. Here we investigated the contribution of ATF4 to ALS. ATF4 deficiency reduced the rate of birth of SOD1G86R transgenic mice. The fraction of ATF4−/−-SOD1G85R transgenic mice that were born are more resistant to develop ALS, leading to delayed disease onset and prolonged life span. ATF4 deficiency completely attenuated the induction of pro-apoptotic genes, including BIM and CHOP, and also led to quantitative changes in the ER protein homeostasis network. Unexpectedly, ATF4 deficiency enhanced mutant SOD1 aggregation at the end stage of the disease. Studies in the motoneuron cell line NSC34 demonstrated that knocking down ATF4 enhances mutant SOD1 aggregation possibly due to alteration in the redox status of the cell. Our results support a functional role of ATF4 in ALS, offering a novel target for disease intervention. PMID:23874395

  19. Functional contribution of the transcription factor ATF4 to the pathogenesis of amyotrophic lateral sclerosis.

    PubMed

    Matus, Soledad; Lopez, Estefanía; Valenzuela, Vicente; Nassif, Melissa; Hetz, Claudio

    2013-01-01

    Endoplasmic reticulum (ER) stress represents an early pathological event in amyotrophic lateral sclerosis (ALS). ATF4 is a key ER stress transcription factor that plays a role in both adaptation to stress and the activation of apoptosis. Here we investigated the contribution of ATF4 to ALS. ATF4 deficiency reduced the rate of birth of SOD1(G86R) transgenic mice. The fraction of ATF4(-/-)-SOD1(G85R) transgenic mice that were born are more resistant to develop ALS, leading to delayed disease onset and prolonged life span. ATF4 deficiency completely attenuated the induction of pro-apoptotic genes, including BIM and CHOP, and also led to quantitative changes in the ER protein homeostasis network. Unexpectedly, ATF4 deficiency enhanced mutant SOD1 aggregation at the end stage of the disease. Studies in the motoneuron cell line NSC34 demonstrated that knocking down ATF4 enhances mutant SOD1 aggregation possibly due to alteration in the redox status of the cell. Our results support a functional role of ATF4 in ALS, offering a novel target for disease intervention.

  20. 78 FR 77494 - Agency Information Collection Activities; Proposed Collection; Comments Requested: ATF Adjunct...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-23

    ... of Alcohol, Tobacco, Firearms and Explosives Agency Information Collection Activities; Proposed... Justice (DOJ), Bureau of Alcohol, Tobacco, Firearms ] and Explosives (ATF), will submit the following... sponsoring the collection: Form Number: ATF F 6140.3. Bureau of Alcohol, Tobacco, Firearms and Explosives. (4...

  1. 27 CFR 646.153 - Authority of appropriate ATF officers to enter business premises.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... REGULATIONS RELATING TO ALCOHOL AND TOBACCO CONTRABAND CIGARETTES Other Provisions Relating to the Distribution of Cigarettes § 646.153 Authority of appropriate ATF officers to enter business premises. Any appropriate ATF officer may enter the business premises of any distributor of cigarettes to inspect the...

  2. 27 CFR 646.153 - Authority of appropriate ATF officers to enter business premises.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... REGULATIONS RELATING TO ALCOHOL AND TOBACCO CONTRABAND CIGARETTES Other Provisions Relating to the Distribution of Cigarettes § 646.153 Authority of appropriate ATF officers to enter business premises. Any appropriate ATF officer may enter the business premises of any distributor of cigarettes to inspect the...

  3. 27 CFR 646.153 - Authority of appropriate ATF officers to enter business premises.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... REGULATIONS RELATING TO ALCOHOL AND TOBACCO CONTRABAND CIGARETTES Other Provisions Relating to the Distribution of Cigarettes § 646.153 Authority of appropriate ATF officers to enter business premises. Any appropriate ATF officer may enter the business premises of any distributor of cigarettes to inspect...

  4. 27 CFR 646.153 - Authority of appropriate ATF officers to enter business premises.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... REGULATIONS RELATING TO ALCOHOL AND TOBACCO CONTRABAND CIGARETTES Other Provisions Relating to the Distribution of Cigarettes § 646.153 Authority of appropriate ATF officers to enter business premises. Any appropriate ATF officer may enter the business premises of any distributor of cigarettes to inspect...

  5. Neuronal injury marker ATF-3 is induced in primary afferent neurons of monoarthritic rats.

    PubMed

    Nascimento, Diana; Pozza, Daniel Humberto; Castro-Lopes, José Manuel; Neto, Fani Lourença

    2011-01-01

    Activating transcription factor 3 (ATF-3) expression has been associated with several signaling pathways implicated in cellular stress response in many cell types and is usually regarded as a neuronal damage marker in dorsal root ganglia (DRG). We investigated ATF-3 expression in primary afferents in the monoarthritic (MA) model of chronic inflammatory joint pain. Immunohistochemistry revealed that ATF-3 is highly induced mainly in small and medium neurons, especially at 2 and 4 days of MA in L(5) DRGs. Colocalization with calcitonin gene-related peptide (CGRP) and isolectin B4 (IB4) demonstrated that ATF-3-immunoreactive cells are mainly peptidergic. The lack of significant differences in ATF-3 and pAkt colocalization indicated that ATF-3 is probably not involved in a pAkt-mediated survival pathway. Anti-inflammatory (ketoprofen) administration failed to reverse ATF-3 induction in MA rats, but significantly increased CGRP expression. These data suggest that ATF-3 expression is definitely involved in MA, actually marking injured neurons. Some degree of neuronal damage seems to occur right from the first days of disease, mainly affecting small-to-medium peptidergic neurons. The intra-articular injection of complete Freund's adjuvant and the generation of a neuroinflammatory environment seem to be the plausible explanation for the local nerve damage. Copyright © 2011 S. Karger AG, Basel.

  6. ATF2, a paradigm of the multifaceted regulation of transcription factors in biology and disease.

    PubMed

    Watson, Gregory; Ronai, Ze'ev; Lau, Eric

    2017-02-15

    Stringent transcriptional regulation is crucial for normal cellular biology and organismal development. Perturbations in the proper regulation of transcription factors can result in numerous pathologies, including cancer. Thus, understanding how transcription factors are regulated and how they are dysregulated in disease states is key to the therapeutic targeting of these factors and/or the pathways that they regulate. Activating transcription factor 2 (ATF2) has been studied in a number of developmental and pathological conditions. Recent findings have shed light on the transcriptional, post-transcriptional, and post-translational regulatory mechanisms that influence ATF2 function, and thus, the transcriptional programs coordinated by ATF2. Given our current knowledge of its multiple levels of regulation and function, ATF2 represents a paradigm for the mechanistic complexity that can regulate transcription factor function. Thus, increasing our understanding of the regulation and function of ATF2 will provide insights into fundamental regulatory mechanisms that influence how cells integrate extracellular and intracellular signals into a genomic response through transcription factors. Characterization of ATF2 dysfunction in the context of pathological conditions, particularly in cancer biology and response to therapy, will be important in understanding how pathways controlled by ATF2 or other transcription factors might be therapeutically exploited. In this review, we provide an overview of the currently known upstream regulators and downstream targets of ATF2.

  7. ATF4, A Novel Mediator of the Anabolic Actions of PTH on Bone

    DTIC Science & Technology

    2009-07-01

    permeabilization (MOMP) and can be either pro- apoptotic (Bax, BAD, Bak, and Bok ) or anti-apoptotic (including Bcl-2, Bcl-xL, and Bcl-w) [Adams, 2003]. Atf4...Sivaprasad U. 1999. ATF3 and stress responses. Gene Expr 7:321–335. He CH, Gong P, Hu B, Stewart D, Choi ME, Choi AM, Alam J. 2001. Identification of

  8. Improved antibody production in Chinese hamster ovary cells by ATF4 overexpression.

    PubMed

    Haredy, Ahmad M; Nishizawa, Akitoshi; Honda, Kohsuke; Ohya, Tomoshi; Ohtake, Hisao; Omasa, Takeshi

    2013-12-01

    To improve antibody production in Chinese hamster ovary (CHO) cells, the humanized antibody-producing CHO DP-12-SF cell line was transfected with the gene encoding activating transcription factor 4 (ATF4), a central factor in the unfolded protein response. Overexpression of ATF4 significantly enhanced the production of antibody in the CHO DP-12-SF cell line. The specific IgG production rate of in the ATF4-overexpressing CHO-ATF4-16 cells was approximately 2.4 times that of the parental host cell line. Clone CHO-ATF4-16 did not show any change in growth rate compared with the parental cells or mock-transfected CHO-DP12-SF cells. The expression levels of mRNAs encoding both the antibody heavy and light chains in the CHO-ATF4-16 clone were analyzed. This analysis showed that ATF4 overexpression improved the total production and specific production rate of antibody without affecting the mRNA transcription level. These results indicate that ATF4 overexpression is a promising method for improving recombinant IgG production in CHO cells.

  9. Atf3 mutant mice show reduced axon regeneration and impaired regeneration-associated gene induction after peripheral nerve injury

    PubMed Central

    Gey, Manuel; Wanner, Renate; Schilling, Corinna; Pedro, Maria T.; Sinske, Daniela

    2016-01-01

    Axon injury in the peripheral nervous system (PNS) induces a regeneration-associated gene (RAG) response. Atf3 (activating transcription factor 3) is such a RAG and ATF3's transcriptional activity might induce ‘effector’ RAGs (e.g. small proline rich protein 1a (Sprr1a), Galanin (Gal), growth-associated protein 43 (Gap43)) facilitating peripheral axon regeneration. We provide a first analysis of Atf3 mouse mutants in peripheral nerve regeneration. In Atf3 mutant mice, facial nerve regeneration and neurite outgrowth of adult ATF3-deficient primary dorsal root ganglia neurons was decreased. Using genome-wide transcriptomics, we identified a neuropeptide-encoding RAG cluster (vasoactive intestinal peptide (Vip), Ngf, Grp, Gal, Pacap) regulated by ATF3. Exogenous administration of neuropeptides enhanced neurite growth of Atf3 mutant mice suggesting that these molecules might be effector RAGs of ATF3's pro-regenerative function. In addition to the induction of growth-promoting molecules, we present data that ATF3 suppresses growth-inhibiting molecules such as chemokine (C-C motif) ligand 2. In summary, we show a pro-regenerative ATF3 function during PNS nerve regeneration involving transcriptional activation of a neuropeptide-encoding RAG cluster. ATF3 is a general injury-inducible factor, therefore ATF3-mediated mechanisms identified herein might apply to other cell and injury types. PMID:27581653

  10. Essential role of eIF5-mimic protein in animal development is linked to control of ATF4 expression

    USDA-ARS?s Scientific Manuscript database

    Translational control of ATF4 through upstream ORFs (uORFs) plays an important role in eukaryotic gene regulation. While ATF4 translation is typically induced by inhibitory phosphorylation of eIF2, ATF4 translation can be also induced by expression of a new translational inhibitor protein, eIF5-mimi...

  11. Upregulation of ATF-3 is correlated with prognosis and proliferation of laryngeal cancer by regulating Cyclin D1 expression

    PubMed Central

    Feng, Jiapeng; Sun, Qingfeng; Wu, Tianyi; Lu, Jianguang; Qu, Lingmei; Sun, Yanan; Tian, Linli; Zhang, Binghui; Li, Dandan; Liu, Ming

    2013-01-01

    Objective: This study aimed to investigate the expression and significance of ATF-3 in laryngeal squamous cell carcinoma (LSCC). Methods: Expression of ATF-3 was examined using immunohistochemistry methods in samples from 83 cases of LSCC carcinoma. MTT assay was used to detect proliferation of Hep-2 cells after ATF-3 knocked down by siRNA lentivirus. A mouse model was used to investigate the inhibitive role of ATF-3 siRNA in LSCC xenografts. Realtime RCR was used to detect Cyclin D1 expression after ATF-3 downregulation in Hep-2 cells. Results: The expression of ATF-3 was positively detected in all the 83 cases of LSCC cancer tissues while Only 4 cases of adjacent non-neoplastic tissues were detected with positive ATF-3 expression. The ATF-3 expression was statistically related with T stage, neck nodal metastasis, clinical stage and prognosis of LSCC. Both cell proliferation in vitro and tumor growth in vivo were suppressed after ATF-3 knockdown. Furthermore, the expression of Cyclin D1 was decreased after ATF-3 downregulation in Hep-2 cells. Conclusion: ATF-3 is involved in the progress of LSCC, and may provide clinical information for evaluation of prognosis of LSCC. The oncologic role of ATF-3 may be correlated with Cyclin D1 regulation. PMID:24133584

  12. Upregulation of ATF-3 is correlated with prognosis and proliferation of laryngeal cancer by regulating Cyclin D1 expression.

    PubMed

    Feng, Jiapeng; Sun, Qingfeng; Wu, Tianyi; Lu, Jianguang; Qu, Lingmei; Sun, Yanan; Tian, Linli; Zhang, Binghui; Li, Dandan; Liu, Ming

    2013-01-01

    This study aimed to investigate the expression and significance of ATF-3 in laryngeal squamous cell carcinoma (LSCC). Expression of ATF-3 was examined using immunohistochemistry methods in samples from 83 cases of LSCC carcinoma. MTT assay was used to detect proliferation of Hep-2 cells after ATF-3 knocked down by siRNA lentivirus. A mouse model was used to investigate the inhibitive role of ATF-3 siRNA in LSCC xenografts. Realtime RCR was used to detect Cyclin D1 expression after ATF-3 downregulation in Hep-2 cells. The expression of ATF-3 was positively detected in all the 83 cases of LSCC cancer tissues while Only 4 cases of adjacent non-neoplastic tissues were detected with positive ATF-3 expression. The ATF-3 expression was statistically related with T stage, neck nodal metastasis, clinical stage and prognosis of LSCC. Both cell proliferation in vitro and tumor growth in vivo were suppressed after ATF-3 knockdown. Furthermore, the expression of Cyclin D1 was decreased after ATF-3 downregulation in Hep-2 cells. ATF-3 is involved in the progress of LSCC, and may provide clinical information for evaluation of prognosis of LSCC. The oncologic role of ATF-3 may be correlated with Cyclin D1 regulation.

  13. ATF-2 controls transcription of Maspin and GADD45 alpha genes independently from p53 to suppress mammary tumors.

    PubMed

    Maekawa, T; Sano, Y; Shinagawa, T; Rahman, Z; Sakuma, T; Nomura, S; Licht, J D; Ishii, S

    2008-02-14

    The activating transcription factor, ATF-2, is a target of p38 and JNK that are involved in stress-induced apoptosis. Heterozygous Atf-2 mutant (Atf-2+/-) mice are highly prone to mammary tumors. The apoptosis-regulated gene GADD45alpha and the breast cancer suppressor gene Maspin, both of which are known to be p53 target genes, are downregulated in the mammary tumors arisen in Atf-2+/- mice. Here, we have analysed how ATF-2 controls the transcription of GADD45alpha and Maspin. ATF-2 and p53 independently activate the GADD45alpha transcription. ATF-2 does not directly bind to the GADD45alpha promoter; instead, it is recruited via Oct-1 and NF-I. ATF-2 simultaneously binds to Oct-1, NF-I and breast cancer suppressor BRCA1 to activate transcription. With regard to Maspin, ATF-2 and p53 directly bind to different sites in the Maspin promoter to independently activate its transcription. Consistent with the observation that ATF-2 and p53 independently activate the transcription of Maspin and GADD45alpha is that the loss of one copy of p53 shortened the period required for mammary tumor development in Atf-2+/- mice. These studies suggest the functional link between the ATF-2 and the two tumor suppressors BRCA1 and p53.

  14. Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Cuzzi, J. N.

    2014-12-01

    The rings are changing before our eyes; structure varies on all timescales and unexpected things have been discovered. Many questions have been answered, but some answers remain elusive (see Cuzzi et al 2010 for a review). Here we highlight the major ring science progress over the mission to date, and describe new observations planned for Cassini's final three years. Ring Composition and particle sizes: The rings are nearly all water ice with no other ices - so why are they reddish? The C Ring and Cassini Division are "dirtier" than the more massive B and A Rings, as shown by near-IR and, recently, microwave observations. Particle sizes, from stellar and radio occultations, vary from place to place. Ring structure, micro and macro: numerous spiral density waves and ubiquitous "self-gravity wakes" reveal processes which fostered planet formation in the solar system and elsewhere. However, big puzzles remain regarding the main ring divisions, the C Ring plateau structures, and the B Ring irregular structure. Moonlets, inside and out, seen and unseen: Two gaps contain sizeable moonlets, but more gaps seem to contain none; even smaller embedded "propeller" objects wander, systematically or randomly, through the A ring. Rubble pile ringmoons just outside the rings may escaped from the rings, and the recently discovered "Peggy" may be trying this as we watch. Impact bombardment of the rings: Comet fragments set the rings to rippling on century-timescales, and boulders crash through hourly; meanwhile, the constant hail of infalling Kuiper belt material has a lower mass flux than previously thought. Origin and Age of the Rings: The ring mass and bombardment play key roles. The ring mass is well known everywhere but in the B Ring (where most of it is). New models suggest how tidal breakup of evolving moons may have formed massive ancient rings, of which the current ring is just a shadow. During its last three years, the Cassini tour profile will allow entirely new

  15. Runaway studies in the ATF (Advanced Toroidal Facility) torsatron

    SciTech Connect

    England, A.C.; DeVan, W.R.; Eberle, C.C.; Fowler, R.H.; Gabbard, W.A.; Glowienka, J.C.; Harris, J.H.; Haste, G.R.; Kindsfather, R.R.; Morris, R.N.

    1989-01-01

    Pulsed torsatrons and heliotrons are susceptible to runaway electron formation and confinement resulting from the inherent good containment in the vacuum fields and the high loop voltages during the initiation and termination of the helical and vertical fields (''field ramping''). Because runaway electrons can cause an unacceptable level of hard X rays near the machine, a runaway suppression system was designed and included in the initial operation of the Advanced Toroidal Facility (ATF). The main component of the system is a rotating paddle that is normally left in the vacuum chamber during the field ramps. This device proved to be very effective in reducing the runaway population. Measurements of hard X rays from ATF have shown that the runaways are produced primarily during the field ramping but that usually a small steady-state runaway component is also present during the ''flat-top'' portion of the fields. The paddle is the main source of the hard X rays (thick-target bremsstrahlung), although other objects in the vacuum chamber also serve as targets for the runaways at various times. The maximum X-ray energy found by pulse height analysis is /approximately/12--15 MeV; the mean energy appears to be a few mega-electron-volts. A noticeable forward peaking of the bremsstrahlung from the paddle is evident. The limiters do not appear to be major sources of bremsstrahlung. 17 refs., 14 figs.

  16. Surge-damping vacuum valve

    DOEpatents

    Bullock, Jack C.; Kelly, Benjamin E.

    1980-01-01

    A valve having a mechanism for damping out flow surges in a vacuum system which utilizes a slotted spring-loaded disk positioned adjacent the valve's vacuum port. Under flow surge conditions, the differential pressure forces the disk into sealing engagement with the vacuum port, thereby restricting the flow path to the slots in the disk damping out the flow surge.

  17. Neptune's rings

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This 591-second exposure of the rings of Neptune were taken with the clear filter by the Voyager 2 wide-angle camera. The two main rings are clearly visible and appear complete over the region imaged. Also visible in this image is the inner faint ring and the faint band which extends smoothly from the ring roughly halfway between the two bright rings. Both of these newly discovered rings are broad and much fainter than the two narrow rings. The bright glare is due to over-exposure of the crescent on Neptune. Numerous bright stars are evident in the background. Both bright rings have material throughout their entire orbit, and are therefore continuous. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.

  18. Ring World

    NASA Image and Video Library

    2007-03-01

    Our robotic emissary, flying high above Saturn, captured this view of an alien copper-colored ring world. The overexposed planet has deliberately been removed to show the unlit rings alone, seen from an elevation of 60 degrees

  19. Neptune Rings

    NASA Image and Video Library

    1999-10-29

    This 591-second exposure of the rings of Neptune were taken with the clear filter by NASA Voyager 2 wide-angle camera. The two main rings are clearly visible and appear complete over the region imaged.

  20. Ring Backdrop

    NASA Image and Video Library

    2011-01-03

    Saturn moon Enceladus brightly reflects sunlight before a backdrop of the planet rings and the rings shadows cast onto the planet. NASA Cassini spacecraft captured this snapshot during its flyby of the moon on Nov. 30, 2010.

  1. Damping measurements using operational data

    SciTech Connect

    James, G.H.; Carne, T.G.; Veers, P.S.

    1996-08-01

    The authors have measured modal damping using strain-gauge data from an operating wind turbine. This new technique for measuring modal damping is easier and less expensive than previously used methods. Auto-correlation and cross-correlation functions of the strain-gauge data have been shown to consist of decaying sinusoids which correspond to the modal frequencies and damping ratios of the wind turbine. The authors have verified the method by extracting damping values from an analytically generated data set. Actual operating response data from the DOE/Sandia 34-m Test Bed has been used to calculate modal damping ratios as a function of rotor rotation rate. This capability will allow more accurate fatigue life prediction and control.

  2. ATF-7, a novel bZIP protein, interacts with the PRL-1 protein-tyrosine phosphatase.

    PubMed

    Peters, C S; Liang, X; Li, S; Kannan, S; Peng, Y; Taub, R; Diamond, R H

    2001-04-27

    We have identified a novel basic leucine zipper (bZIP) protein, designated ATF-7, that physically interacts with the PRL-1 protein-tyrosine phosphatase (PTPase). PRL-1 is a predominantly nuclear, farnesylated PTPase that has been linked to the control of cellular growth and differentiation. This interaction was initially found using the yeast two-hybrid system. ATF-7 is most closely related to members of the ATF/CREB family of bZIP proteins, with highest homology to ATF-4. ATF-7 homodimers can bind specifically to CRE elements. ATF-7 is expressed in a number of different tissues and is expressed in association with differentiation in the Caco-2 cell model of intestinal differentiation. We have confirmed the PRL-1.ATF-7 interaction and mapped the regions of ATF-7 and PRL-1 important for interaction to ATF-7's bZIP region and PRL-1's phosphatase domain. Finally, we have determined that PRL-1 is able to dephosphorylate ATF-7 in vitro. Further insight into ATF-7's precise cellular roles, transcriptional function, and downstream targets are likely be of importance in understanding the mechanisms underlying the complex processes of maintenance, differentiation, and turnover of epithelial tissues.

  3. Deletion of ATF4 in AgRP Neurons Promotes Fat Loss Mainly via Increasing Energy Expenditure.

    PubMed

    Deng, Jiali; Yuan, Feixiang; Guo, Yajie; Xiao, Yuzhong; Niu, Yuguo; Deng, Yalan; Han, Xiao; Guan, Youfei; Chen, Shanghai; Guo, Feifan

    2017-03-01

    Although many functions of activating transcription factor 4 (ATF4) are identified, a role of ATF4 in the hypothalamus in regulating energy homeostasis is unknown. Here, we generated adult-onset agouti-related peptide neuron-specific ATF4 knockout (AgRP-ATF4 KO) mice and found that these mice were lean, with improved insulin and leptin sensitivity and decreased hepatic lipid accumulation. Furthermore, AgRP-ATF4 KO mice showed reduced food intake and increased energy expenditure, mainly because of enhanced thermogenesis in brown adipose tissue. Moreover, AgRP-ATF4 KO mice were resistant to high-fat diet-induced obesity, insulin resistance, and liver steatosis and maintained at a higher body temperature under cold stress. Interestingly, the expression of FOXO1 was directly regulated by ATF4 via binding to the cAMP-responsive element site on its promoter in hypothalamic GT1-7 cells. Finally, Foxo1 expression was reduced in the arcuate nucleus (ARC) of the hypothalamus of AgRP-ATF4 KO mice, and adenovirus-mediated overexpression of FOXO1 in ARC increased the fat mass in AgRP-ATF4 KO mice. Collectively, our data demonstrate a novel function of ATF4 in AgRP neurons of the hypothalamus in energy balance and lipid metabolism and suggest hypothalamic ATF4 as a potential drug target for treating obesity and its related metabolic disorders. © 2017 by the American Diabetes Association.

  4. Endoplasmic Reticulum Stress-Activated Transcription Factor ATF6α Requires the Disulfide Isomerase PDIA5 To Modulate Chemoresistance

    PubMed Central

    Higa, Arisa; Taouji, Said; Lhomond, Stéphanie; Jensen, Devon; Fernandez-Zapico, Martin E.; Simpson, Jeremy C.; Pasquet, Jean-Max; Schekman, Randy

    2014-01-01

    ATF6α, a membrane-anchored transcription factor from the endoplasmic reticulum (ER) that modulates the cellular response to stress as an effector of the unfolded-protein response (UPR), is a key player in the development of tumors of different origin. ATF6α activation has been linked to oncogenic transformation and tumor maintenance; however, the mechanism(s) underlying this phenomenon remains elusive. Here, using a phenotypic small interfering RNA (siRNA) screening, we identified a novel role for ATF6α in chemoresistance and defined the protein disulfide isomerase A5 (PDIA5) as necessary for ATF6α activation upon ER stress. PDIA5 contributed to disulfide bond rearrangement in ATF6α under stress conditions, thereby leading to ATF6α export from the ER and activation of its target genes. Further analysis of the mechanism demonstrated that PDIA5 promotes ATF6α packaging into coat protein complex II (COPII) vesicles and that the PDIA5/ATF6α activation loop is essential to confer chemoresistance on cancer cells. Genetic and pharmacological inhibition of the PDIA5/ATF6α axis restored sensitivity to the drug treatment. This work defines the mechanisms underlying the role of ATF6α activation in carcinogenesis and chemoresistance; furthermore, it identifies PDIA5 as a key regulator ATF6α-mediated cellular functions in cancer. PMID:24636989

  5. Transcription factor ATF3 links host adaptive response to breast cancer metastasis

    PubMed Central

    Wolford, Chris C.; McConoughey, Stephen J.; Jalgaonkar, Swati P.; Leon, Marino; Merchant, Anand S.; Dominick, Johnna L.; Yin, Xin; Chang, Yiseok; Zmuda, Erik J.; O’Toole, Sandra A.; Millar, Ewan K.A.; Roller, Stephanie L.; Shapiro, Charles L.; Ostrowski, Michael C.; Sutherland, Robert L.; Hai, Tsonwin

    2013-01-01

    Host response to cancer signals has emerged as a key factor in cancer development; however, the underlying molecular mechanism is not well understood. In this report, we demonstrate that activating transcription factor 3 (ATF3), a hub of the cellular adaptive response network, plays an important role in host cells to enhance breast cancer metastasis. Immunohistochemical analysis of patient tumor samples revealed that expression of ATF3 in stromal mononuclear cells, but not cancer epithelial cells, is correlated with worse clinical outcomes and is an independent predictor for breast cancer death. This finding was corroborated by data from mouse models showing less efficient breast cancer metastasis in Atf3-deficient mice than in WT mice. Further, mice with myeloid cell–selective KO of Atf3 showed fewer lung metastases, indicating that host ATF3 facilitates metastasis, at least in part, by its function in macrophage/myeloid cells. Gene profiling analyses of macrophages from mouse tumors identified an ATF3-regulated gene signature that could distinguish human tumor stroma from distant stroma and could predict clinical outcomes, lending credence to our mouse models. In conclusion, we identified ATF3 as a regulator in myeloid cells that enhances breast cancer metastasis and has predictive value for clinical outcomes. PMID:23921126

  6. The Stress Response Mediator ATF3 Represses Androgen Signaling by Binding the Androgen Receptor

    PubMed Central

    Wang, Hongbo; Jiang, Ming; Cui, Hongmei; Chen, Mengqian; Buttyan, Ralph; Hayward, Simon W.; Hai, Tsonwin; Wang, Zhengxin

    2012-01-01

    Activating transcription factor 3 (ATF3) is a common mediator of cellular stress response signaling and is often aberrantly expressed in prostate cancer. We report here that ATF3 can directly bind the androgen receptor (AR) and consequently repress AR-mediated gene expression. The ATF3-AR interaction requires the leucine zipper domain of ATF3 that independently binds the DNA-binding and ligand-binding domains of AR, and the interaction prevents AR from binding to cis-acting elements required for expression of androgen-dependent genes while inhibiting the AR N- and C-terminal interaction. The functional consequences of the loss of ATF3 expression include increased transcription of androgen-dependent genes in prostate cancer cells that correlates with increased ability to grow in low-androgen-containing medium and increased proliferative activity of the prostate epithelium in ATF3 knockout mice that is associated with prostatic hyperplasia. Our results thus demonstrate that ATF3 is a novel repressor of androgen signaling that can inhibit AR functions, allowing prostate cells to restore homeostasis and maintain integrity in the face of a broad spectrum of intrinsic and environmental insults. PMID:22665497

  7. Chronic ethanol consumption inhibits glucokinase transcriptional activity by Atf3 and triggers metabolic syndrome in vivo.

    PubMed

    Kim, Ji Yeon; Hwang, Joo-Yeon; Lee, Dae Yeon; Song, Eun Hyun; Park, Keon Jae; Kim, Gyu Hee; Jeong, Eun Ae; Lee, Yoo Jeong; Go, Min Jin; Kim, Dae Jin; Lee, Seong Su; Kim, Bong-Jo; Song, Jihyun; Roh, Gu Seob; Gao, Bin; Kim, Won-Ho

    2014-09-26

    Chronic ethanol consumption induces pancreatic β-cell dysfunction through glucokinase (Gck) nitration and down-regulation, leading to impaired glucose tolerance and insulin resistance, but the underlying mechanism remains largely unknown. Here, we demonstrate that Gck gene expression and promoter activity in pancreatic β-cells were suppressed by chronic ethanol exposure in vivo and in vitro, whereas expression of activating transcription factor 3 (Atf3) and its binding to the putative Atf/Creb site (from -287 to -158 bp) on the Gck promoter were up-regulated. Furthermore, in vitro ethanol-induced Atf3 inhibited the positive effect of Pdx-1 on Gck transcriptional regulation, enhanced recruitment of Hdac1/2 and histone H3 deacetylation, and subsequently augmented the interaction of Hdac1/Pdx-1 on the Gck promoter, which were diminished by Atf3 siRNA. In vivo Atf3-silencing reversed ethanol-mediated Gck down-regulation and β-cell dysfunction, followed by the amelioration of impaired glucose tolerance and insulin resistance. Together, we identified that ethanol-induced Atf3 fosters β-cell dysfunction via Gck down-regulation and that its loss ameliorates metabolic syndrome and could be a potential therapeutic target in treating type 2 diabetes. The Atf3 gene is associated with the induction of type 2 diabetes and alcohol consumption-induced metabolic impairment and thus may be the major negative regulator for glucose homeostasis.

  8. Loss of ATF2 function leads to cranial motoneuron degeneration during embryonic mouse development.

    PubMed

    Ackermann, Julien; Ashton, Garry; Lyons, Steve; James, Dominic; Hornung, Jean-Pierre; Jones, Nic; Breitwieser, Wolfgang

    2011-04-21

    The AP-1 family transcription factor ATF2 is essential for development and tissue maintenance in mammals. In particular, ATF2 is highly expressed and activated in the brain and previous studies using mouse knockouts have confirmed its requirement in the cerebellum as well as in vestibular sense organs. Here we present the analysis of the requirement for ATF2 in CNS development in mouse embryos, specifically in the brainstem. We discovered that neuron-specific inactivation of ATF2 leads to significant loss of motoneurons of the hypoglossal, abducens and facial nuclei. While the generation of ATF2 mutant motoneurons appears normal during early development, they undergo caspase-dependent and independent cell death during later embryonic and foetal stages. The loss of these motoneurons correlates with increased levels of stress activated MAP kinases, JNK and p38, as well as aberrant accumulation of phosphorylated neurofilament proteins, NF-H and NF-M, known substrates for these kinases. This, together with other neuropathological phenotypes, including aberrant vacuolisation and lipid accumulation, indicates that deficiency in ATF2 leads to neurodegeneration of subsets of somatic and visceral motoneurons of the brainstem. It also confirms that ATF2 has a critical role in limiting the activities of stress kinases JNK and p38 which are potent inducers of cell death in the CNS.

  9. ATF-2 stimulates the human insulin promoter through the conserved CRE2 sequence.

    PubMed

    Hay, Colin W; Ferguson, Laura A; Docherty, Kevin

    2007-02-01

    The insulin promoter contains a number of dissimilar cis-acting regulatory elements that bind a range of tissue specific and ubiquitous transcription factors. Of the regulatory elements within the insulin promoter, the cyclic AMP responsive element (CRE) binds by far the most diverse array of transcription factors. Rodent insulin promoters have a single CRE site, whereas there are four CREs within the human insulin gene, of which CRE2 is the only one conserved between species. The aim of this study was to characterise the human CRE2 site and to investigate the effects of the two principal CRE-associated transcription factors; CREB-1 and ATF-2. Co-transfection of INS-1 pancreatic beta-cells with promoter constructs containing the human insulin gene promoter placed upstream of the firefly luciferase reporter gene and expression plasmids for ATF-2 or CREB-1 showed that ATF-2 stimulated transcriptional activity while CREB-1 elicited an inhibitory effect. Mutagenesis of CRE2 diminished the effect of ATF-2 but not that of CREB-1. ATF-2 was shown to bind to the CRE2 site by electrophoretic mobility shift assay and by chromatin immunoprecipitation, while siRNA mediated knockdown of ATF-2 diminished the stimulatory effects of cAMP related signalling on promoter activity. These results suggest that ATF-2 may be a key regulator of the human insulin promoter possibly stimulating activity in response to extracellular signals.

  10. [Construction and identification of small interfering RNA expression vector targeting ATF-2 gene].

    PubMed

    Mao, Wei-wei; Xiong, Peng; Han, Feng; Hu, Zhi-jian

    2012-09-01

    To construct an eukaryotic expression vector for RNA interference targeting activating transcription factor 2 (ATF-2) gene, and explore its effect on proliferation and apoptosis of HepG2 cells. Two complementary oligonucleotides were synthesized based on ATF-2 mRNA sequence. The annealed fragment was inserted into the vector PBA-siU6. The recombinant plasmid PBA-siATF-2 was confirmed by DNA sequencing and transfected into HepG2 cells mediated by liposome. After transfection, ATF-2 protein was detected by Western blotting. The cellular growth activity and apoptosis rate were measured by MTT assay and flow cytometry, respectively. Recombinant plasmid expressing siRNA targeting ATF-2 gene was confirmed by DNA sequencing. Plasmid transfection down-regulated the level of ATF-2 protein in HepG2 cells, which blocked cellular growth and induced cell apoptosis. The eukaryotic expression vector for RNA interference targeting ATF-2 gene was constructed successfully, which inhibits HepG2 cell proliferation and induces cell apoptosis.

  11. Design and Analysis of Constrained Layer Damping Treatments for Bending and Torsion

    DTIC Science & Technology

    1994-09-01

    kinetic energy into heat . Passive damping methods are attractive in many applications because of their relative simplicity, low cost, low weight, and...material converts kinetic energy into heat when it undergoes mechanical strain. There are two primary viscoelastic coating classifications. In the...constrained layer damping treament on a beam of circular cross section, as well as lumped mass dampers mounted on rings (47:199). Fowler and others used

  12. The potential role of ATF3 on immune response is regulated by BMP10 through Smad dependent pathway.

    PubMed

    Wang, Yong; Zhang, Yi-Wei; Xu, Li; Xin, Hong-bo

    2011-05-01

    It is hypothesis that ATF3 is a downstream component of BMP10. The possible function of ATF3 on immune response is partially regulated by BMP10 via Smad dependent pathway. BMP10 is highly expressed in blood cells during embryonic development based on our in situ hybridization. The expression of ATF3 is enhanced by BMP10 in overexpression transgenic mice. Both BMP10 and ATF3 can response to stress stimulate, and ATF3 is well understood as a stress inducible gene which possible contributes to immune response. The Smad dependent pathway is well established for BMP10 in regulation expression of downstream targets. It would be interesting for us to determine the relationship between BMP10 and ATF3, especially to understand the mechanism of BMP10 and ATF3 effecting on heart development, as well as immune response exposed to stress stimulates.

  13. Regulation of ATF1 and ATF2 transcripts by sequences in their 3' untranslated region in cleavage-stage cattle embryos.

    PubMed

    Orozco-Lucero, Ernesto; Dufort, Isabelle; Sirard, Marc-André

    2017-04-01

    The sequence of a 3' untranslated region (3'UTR) of mRNA governs the timing of its polyadenylation and translation in mammalian oocytes and early embryos. The objective of this study was to assess the influence of cis-elements in the 3'UTR of the developmentally important ATF1 and ATF2 transcripts on their timely translation during first cleavages in bovine embryos. Eight different reporter mRNAs (coding sequence of green fluorescent protein [GFP] fused to the 3'UTR of short or long isoforms of cattle ATF1 or -2, with or without polyadenylation) or a control GFP mRNA were microinjected separately into presumptive bovine zygotes at 18 hr post-insemination (hpi), followed by epifluorescence assessment for GFP translation between 24 and 80 hpi (expressed as percentage of GFP-positive embryos calculated from the total number of individuals). The presence of either polyadenine or 3'UTR sequence in deadenylated constructs is required for GFP translation (implying the need for polyadenylation), and all exogenous mRNAs that met either criteria were translated as soon as 24 hpi-except for long-deadenylated ATF2-UTR, whose translation began at 36 hpi. Overall, GFP was more visibly translated in competent (cleaving) embryos, particularly in long ATF1/2 constructs. The current data shows a timely GFP translation in bovine embryos depending on sequences in the 3'UTR of ATF1/2, and indicates a difference between short and long isoforms. In addition, cleaving embryos displayed increased translational capacity of the tested constructs. Functional confirmation of the identification cis-sequences in the 3'UTR of ATF1/2 will contribute to the understanding of maternal mRNA translation regulation during early cattle development. © 2017 Wiley Periodicals, Inc.

  14. The Loss of Activating Transcription Factor 4 (ATF4) Reduces Bone Toughness and Fracture Toughness

    PubMed Central

    Makowski, Alexander J.; Uppuganti, Sasidhar; Waader, Sandra A.; Whitehead, Jack M.; Rowland, Barbara J.; Granke, Mathilde; Mahadevan-Jansen, Anita; Yang, Xiangli; Nyman, Jeffry S.

    2014-01-01

    Even though age-related changes to bone tissue affecting fracture risk are well characterized, only a few matrix-related factors have been identified as important to maintaining fracture resistance. As a gene critical to osteoblast differentiation, activating transcription factor 4 (ATF4) is possibly one of the seimportant factors. To test the hypothesis that the loss of ATF4 affects the fracture resistance of bone beyond bone mass and structure, we harvested bones from Atf4+/+ and Atf4−/− littermates at 8 and 20 weeks of age (n≥9 per group) for bone assessment across several length scales. From whole bone mechanical tests in bending, femurs from Atf4−/− mice were found to be brittle with reduced toughness and fracture toughness compared to femurs from Atf4+/+ mice. However, there were no differences in material strength and in tissue hardness, as determined by nanoindentation, between the genotypes, irrespective age. Tissue mineral density of the cortex at the point of loading as determined by micro-computed tomography was also not significantly different. However, by analyzing local composition by Raman Spectroscopy (RS), bone tissue of Atf4−/− mice was found to have higher mineral to collagen ratio compared to wild-type tissue, primarily at 20 weeks of age. From RS analysis of intact femurs at 2 orthogonal orientations relative to the polarization axis of the laser, we also found that the organizational-sensitive peak ratio, ν1 Phosphate per Amide I, changed to a greater extent upon bone rotation for Atf4-deficient tissue, implying bone matrix organization may contribute to the brittleness phenotype. Target genes of ATF4 activity are not only important to osteoblast differentiation but also maintaining bone toughness and fracture toughness. PMID:24509412

  15. Immunoreactivity of ATF-2 and Fra-2 in human dental follicle.

    PubMed

    Bolat, Ilker; Keklikoglu, Nurullah

    2010-01-01

    It is asserted that epithelial rests in dental follicle (DF) existing around the impacted teeth in adults are effective in cyst formation. In this study, it is intended for determining and comparing the immunoreactivity (IR) ratio of ATF-2 and Fra-2 proteins, the members of Activator Protein-1 (AP-1) family which regulates important cellular activities such as growth, proliferation and differentiation, in DF epithelial cells (EC) and connective tissue cells (CC). In this study, ATF-2 and Fra-2 immunoreactivity (ATF-2-IR and Fra-2-IR) in EC and CC in DF tissues obtained from 30 patients were analyzed by using immunohistochemical method. Ratios of ATF-2-IR positive cells were found 17.36+/-9.55% in EC, 27.27+/-14.86% in CC and ratios of Fra-2-IR positive cells were found 20.04+/-11.47% in EC, 16.71+/-9.05% in CC. In the statistically comparison performed; significant differences were found between EC and CC in terms of both ATF-2-IR (p<0.001) and Fra-2-IR (p<0.05). In EC, no significant difference was found between ATF-2-IR and Fra-2-IR (p>0.05), whereas significant difference was found between ATF-2-IR and Fra-2-IR in CC (p<0.001). According to these data, it can be suggested that Fra-2 protein may be more effective than ATF-2 protein in cyst formation originated from EC of DF. Besides, finding that ATF-2-IR and Fra-2-IR are different in CC although similar in EC shows that AP-1 members can be expressed at different ratios in same tissues.

  16. GSTpi modulates JNK activity through a direct interaction with JNK substrate, ATF2

    PubMed Central

    Thévenin, Anastasia F; Zony, Chati L; Bahnson, Brian J; Colman, Roberta F

    2011-01-01

    Human GSTpi, an important detoxification enzyme, has been shown to modulate the activity of JNKs by inhibiting apoptosis and by causing cell proliferation and tumor growth. In this work, we describe a detailed analysis of the interaction in vitro between GSTpi and JNK isoforms (both in their inactive and active, phosphorylated forms). The ability of active JNK1 or JNK2 to phosphorylate their substrate, ATF2, is inhibited by two naturally occurring GSTpi haplotypes (Ile105/Ala114, WT or haplotype A, and Val105/Val114, haplotype C). Haplotype C of GSTpi is a more potent inhibitor of JNK activity than haplotype A, yielding 75–80% and 25–45% inhibition, respectively. We show that GSTpi is not a substrate of JNK, as was earlier suggested by others. Through binding studies, we demonstrate that the interaction between GSTpi and phosphorylated, active JNKs is isoform specific, with JNK1 being the preferred isoform. In contrast, GSTpi does not interact with unphosphorylated, inactive JNKs unless a JNK substrate, ATF2, is present. We also demonstrate, for the first time, a direct interaction: between GSTpi and ATF2. GSTpi binds with similar affinity to active JNK + ATF2 and to ATF2 alone. Direct binding experiments between ATF2 and GSTpi, either alone or in the presence of glutathione analogs or phosphorylated ATF2, indicate that the xenobiotic portion of the GSTpi active site and the JNK binding domain of ATF2 are involved in this interaction. Competition between GSTpi and active JNK for the substrate ATF2 may be responsible for the inhibition of JNK catalysis by GSTpi. PMID:21384452

  17. The loss of activating transcription factor 4 (ATF4) reduces bone toughness and fracture toughness.

    PubMed

    Makowski, Alexander J; Uppuganti, Sasidhar; Wadeer, Sandra A; Whitehead, Jack M; Rowland, Barbara J; Granke, Mathilde; Mahadevan-Jansen, Anita; Yang, Xiangli; Nyman, Jeffry S

    2014-05-01

    Even though age-related changes to bone tissue affecting fracture risk are well characterized, only a few matrix-related factors have been identified as important to maintaining fracture resistance. As a gene critical to osteoblast differentiation, activating transcription factor 4 (ATF4) is possibly one of these important factors. To test the hypothesis that the loss of ATF4 affects the fracture resistance of bone beyond bone mass and structure, we harvested bones from Atf4+/+ and Atf4-/- littermates at 8 and 20 weeks of age (n≥9 per group) for bone assessment across several length scales. From whole bone mechanical tests in bending, femurs from Atf4-/- mice were found to be brittle with reduced toughness and fracture toughness compared to femurs from Atf4+/+ mice. However, there were no differences in material strength and in tissue hardness, as determined by nanoindentation, between the genotypes, irrespective of age. Tissue mineral density of the cortex at the point of loading as determined by micro-computed tomography was also not significantly different. However, by analyzing local composition by Raman Spectroscopy (RS), bone tissue of Atf4-/- mice was found to have higher mineral to collagen ratio compared to wild-type tissue, primarily at 20 weeks of age. From RS analysis of intact femurs at 2 orthogonal orientations relative to the polarization axis of the laser, we also found that the organizational-sensitive peak ratio, ν1Phosphate per Amide I, changed to a greater extent upon bone rotation for Atf4-deficient tissue, implying bone matrix organization may contribute to the brittleness phenotype. Target genes of ATF4 activity are not only important to osteoblast differentiation but also in maintaining bone toughness and fracture toughness. Published by Elsevier Inc.

  18. ATF4 Protein Deficiency Protects against High Fructose-induced Hypertriglyceridemia in Mice*

    PubMed Central

    Xiao, Guozhi; Zhang, Ting; Yu, Shibing; Lee, Sojin; Calabuig-Navarro, Virtu; Yamauchi, Jun; Ringquist, Steven; Dong, H. Henry

    2013-01-01

    Hypertriglyceridemia is the most common lipid disorder in obesity and type 2 diabetes. It results from increased production and/or decreased clearance of triglyceride-rich lipoproteins. To better understand the pathophysiology of hypertriglyceridemia, we studied hepatic regulation of triglyceride metabolism by the activating transcription factor 4 (ATF4), a member of the basic leucine zipper-containing protein subfamily. We determined the effect of ATF4 on hepatic lipid metabolism in Atf4−/− mice fed regular chow or provided with free access to fructose drinking water. ATF4 depletion preferentially attenuated hepatic lipogenesis without affecting hepatic triglyceride production and fatty acid oxidation. This effect prevented excessive fat accumulation in the liver of Atf4−/− mice, when compared with wild-type littermates. To gain insight into the underlying mechanism, we showed that ATF4 depletion resulted in a significant reduction in hepatic expression of peroxisome proliferator-activated receptor-γ, a nuclear receptor that acts to promote lipogenesis in the liver. This effect was accompanied by a significant reduction in hepatic expression of sterol regulatory element-binding protein 1c (SREBP-1c), acetyl-CoA carboxylase, and fatty-acid synthase, three key functions in the lipogenic pathway in Atf4−/− mice. Of particular significance, we found that Atf4−/− mice, as opposed to wild-type littermates, were protected against the development of steatosis and hypertriglyceridemia in response to high fructose feeding. These data demonstrate that ATF4 plays a critical role in regulating hepatic lipid metabolism in response to nutritional cues. PMID:23888053

  19. Transverse instability at the recycler ring

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2004-10-01

    Sporadic transverse instabilities have been observed at the Fermilab Recycler Ring leading to increase in transverse emittances and beam loss. The driving source of these instabilities has been attributed to the resistive-wall impedance with space-charge playing an important role in suppressing Landau damping. Growth rates of the instabilities are computed. Remaining problems are discussed.

  20. ATF4 Targets RET for Degradation and Is a Candidate Tumor Suppressor Gene in Medullary Thyroid Cancer.

    PubMed

    Bagheri-Yarmand, Rozita; Williams, Michelle D; Grubbs, Elizabeth G; Gagel, Robert F

    2017-03-01

    Medullary thyroid cancer (MTC) is an aggressive tumor that harbors activating mutations of the RET proto-oncogene. We previously reported that RET inhibits transcriptional activity of ATF4, the master regulator of the stress response pathway, to prevent cell death. We hypothesized that loss of function of ATF4 plays a role in initiation of MTC. Targeted deletion of Atf4 in mice was used to assess ATF4 function in the thyroid gland. ATF4 overexpression was achieved by adenoviral and lentiviral vectors. We used immunohistochemical analysis and western blotting of MTC tumors to determine protein levels of RET and ATF4 and the Kaplan-Meier method to determine their association with clinical outcome. Targeted deletion of Atf4 in mice causes C-cell hyperplasia, a precancerous lesion for MTC. Forced ATF4 expression decreased survival of MTC cells and blocked the activation of RET downstream signaling pathways (phosphorylated ERK, phosphorylated AKT, and p70S6K). ATF4 knockdown decreased sensitivity to tyrosine kinase inhibitor-induced apoptosis. Moreover, ATF4 expression decreased RET protein levels by promoting RET ubiquitination. We found decreased or loss of ATF4 in 52% of MTC tumors (n = 39) compared with normal thyroid follicle cells. A negative correlation was observed between RET and ATF4 protein levels in MTC tumors, and low ATF4 expression was associated with poor overall survival in patients with MTC. ATF4 was identified as a negative regulator of RET, a candidate tumor suppressor gene, and may be a molecular marker that distinguishes patients at high risk of MTC from those with a longer survival prognosis.

  1. p53 and ATF4 mediate distinct and additive pathways to skeletal muscle atrophy during limb immobilization

    PubMed Central

    Fox, Daniel K.; Ebert, Scott M.; Bongers, Kale S.; Dyle, Michael C.; Bullard, Steven A.; Dierdorff, Jason M.; Kunkel, Steven D.

    2014-01-01

    Immobilization causes skeletal muscle atrophy via complex signaling pathways that are not well understood. To better understand these pathways, we investigated the roles of p53 and ATF4, two transcription factors that mediate adaptations to a variety of cellular stresses. Using mouse models, we demonstrate that 3 days of muscle immobilization induces muscle atrophy and increases expression of p53 and ATF4. Furthermore, muscle fibers lacking p53 or ATF4 are partially resistant to immobilization-induced muscle atrophy, and forced expression of p53 or ATF4 induces muscle fiber atrophy in the absence of immobilization. Importantly, however, p53 and ATF4 do not require each other to promote atrophy, and coexpression of p53 and ATF4 induces more atrophy than either transcription factor alone. Moreover, muscle fibers lacking both p53 and ATF4 are more resistant to immobilization-induced atrophy than fibers lacking only p53 or ATF4. Interestingly, the independent and additive nature of the p53 and ATF4 pathways allows for combinatorial control of at least one downstream effector, p21. Using genome-wide mRNA expression arrays, we identified p21 mRNA as a skeletal muscle transcript that is highly induced in immobilized muscle via the combined actions of p53 and ATF4. Additionally, in mouse muscle, p21 induces atrophy in a manner that does not require immobilization, p53 or ATF4, and p21 is required for atrophy induced by immobilization, p53, and ATF4. Collectively, these results identify p53 and ATF4 as essential and complementary mediators of immobilization-induced muscle atrophy and discover p21 as a critical downstream effector of the p53 and ATF4 pathways. PMID:24895282

  2. Self-Damping Sprung Wheel

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce

    1993-01-01

    Self-damping sprung wheel provides shock-absorbing suspension for wheelchair, reducing user's discomfort when traversing rough terrain or obstacles. Pair of self-damping sprung wheels installed in place of conventional large rear wheels of standard wheelchair, which user operates in conventional manner. Rim deflects in vicinity of contact with ground or floor. Includes inner and outer hoops bending when obstacle encountered. Shear deformation of elastomeric hoop between them absorbs energy. Thus, three hoops act together as damping spring. Alternative version of wheel designed for bicycle.

  3. Bearing-Cartridge Damping Seal

    NASA Technical Reports Server (NTRS)

    Goggins, David G.; Scharrer, Joseph K.; Chen, Wei C.

    1991-01-01

    In proposed design for improved ball-bearing cartridge, damping seal in form of thin-layer fluid journal bearing incorporated into cartridge. Damping seal acts as auxiliary bearing, relieving bearing balls of significant portions of both static and dynamic bearing loads. Damping from seal reduces dynamic loads even further by reducing amplitude of vibrations in second vibrational mode of rotor, which mode occurs when rotor turning at nearly full operating speed. Intended for use in high-pressure-oxygen turbopump of Space Shuttle main engine, also applicable to other turbomachinery bearings.

  4. Self-Damping Sprung Wheel

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce

    1993-01-01

    Self-damping sprung wheel provides shock-absorbing suspension for wheelchair, reducing user's discomfort when traversing rough terrain or obstacles. Pair of self-damping sprung wheels installed in place of conventional large rear wheels of standard wheelchair, which user operates in conventional manner. Rim deflects in vicinity of contact with ground or floor. Includes inner and outer hoops bending when obstacle encountered. Shear deformation of elastomeric hoop between them absorbs energy. Thus, three hoops act together as damping spring. Alternative version of wheel designed for bicycle.

  5. Specifications of the octupole magnets required for the ATF2 ultra-low ß* lattice

    SciTech Connect

    Marin, E.; Modena, M.; Tauchi, T.; Terunuma, N.; Tomas, R.; White, G.R.; /SLAC

    2014-05-28

    The Accelerator Test Facility 2 (ATF2) aims to test the novel chromaticity correction for higher chromaticity lattices as the one of CLIC. To this end the ATF2 ultra-low ß* lattice is designed to vertically focus the beam at the focal point or usually referred to as interaction point (IP), down to 23 nm. However when the measured multipole components of the ATF2 magnets are considered in the simulations, the evaluated spot sizes at the IP are well above the design value. The designed spot size is effectively recovered by inserting a pair of octupole magnets. In this note we address the technical specifications required for these octupole magnets.

  6. ATF CO{sub 2} laser system upgrade to terawatt peak power

    SciTech Connect

    Pogorelsky, I.V.

    1995-05-01

    This document describes the proposed upgrade of the 10-GW peak power 50-ps CO{sub 2} laser presently operational at the ATF to the 1 TW level at a shorter, 3--10 ps, pulse duration. The approach adopted is based on state of the art CO{sub 2} laser technology and an experience gained in the course of the ATF laser design and application for the laser accelerator experiment. The proposed upgrade is an economical way for the ATF to become in a short time among leading users facilities available for next generation ({ge} 100 MeV) laser accelerator studies.

  7. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Tiscareno, Matthew S.

    Planetary rings are the only nearby astrophysical disks and the only disks that have been investigated by spacecraft (especially the Cassini spacecraft orbiting Saturn). Although there are significant differences between rings and other disks, chiefly the large planet/ring mass ratio that greatly enhances the flatness of rings (aspect ratios as small as 10- 7), understanding of disks in general can be enhanced by understanding the dynamical processes observed at close range and in real time in planetary rings.We review the known ring systems of the four giant planets, as well as the prospects for ring systems yet to be discovered. We then review planetary rings by type. The A, B, and C rings of Saturn, plus the Cassini Division, comprise our solar system's only dense broad disk and host many phenomena of general application to disks including spiral waves, gap formation, self-gravity wakes, viscous overstability and normal modes, impact clouds, and orbital evolution of embedded moons. Dense narrow rings are found both at Uranus (where they comprise the main rings entirely) and at Saturn (where they are embedded in the broad disk) and are the primary natural laboratory for understanding shepherding and self-stability. Narrow dusty rings, likely generated by embedded source bodies, are surprisingly found to sport azimuthally confined arcs at Neptune, Saturn, and Jupiter. Finally, every known ring system includes a substantial component of diffuse dusty rings.Planetary rings have shown themselves to be useful as detectors of planetary processes around them, including the planetary magnetic field and interplanetary impactors as well as the gravity of nearby perturbing moons. Experimental rings science has made great progress in recent decades, especially numerical simulations of self-gravity wakes and other processes but also laboratory investigations of coefficient of restitution and spectroscopic ground truth. The age of self-sustained ring systems is a matter of

  8. Scenarios For The ATF2 Ultra-Low Betas Proposal

    SciTech Connect

    Marin E.; Parker B.; Tomas R. Bambade Kuroda S. Okugi T. Tauchi T. Terunuma N. Urakawa J. Seryi A. White G. Woodley M.

    2010-05-23

    The current ATF2 Ultra-Low beta proposal was designed to achieve 20nm vertical IP beam size without considering the multipolar components of the FD magnets. In this paper we describe different scenarios that avoid the detrimental effect of these multipolar errors to the beam size at the interaction point (IP). The simplest approach consists in modifying the optics, but other solutions are studied as the introduction of super-conducting wigglers to reduce the emittance or the replacement of the normal-conducting focusing quadrupole in the Final Doublet (NC-QF1FF) with a super-conducting quadrupole one (SC-QF1FF). These are fully addressed in the paper.

  9. Scenarios for the ATF2 Ultra-Low Betas Proposal

    SciTech Connect

    Marin, Eduardo; Tomas, Rogelio; Bambade, Philip; Kuroda, Shigeru; Okugi, Toshiyuki; Tauchi, Toshiaki; Terunuma, Nobuhiro; Urakawa, Junji; Parker, Brett; Seryi, Andrei; White, Glen; Woodley, Mark; /SLAC

    2012-06-29

    The current ATF2 Ultra-Low beta proposal was designed to achieve 20nm vertical IP beam size without considering the multipolar components of the FD magnets. In this paper we describe different scenarios that avoid the detrimental effect of these multipolar errors to the beam size at the interaction point (IP). The simplest approach consists in modifying the optics, but other solutions are studied as the introduction of super-conducting wigglers to reduce the emittance or the replacement of the normal-conducting focusing quadrupole in the Final Doublet (NC-QF1FF) with a super-conducting quadrupole one (SC-QF1FF). These are fully addressed in the paper.

  10. Validation of High-Resolution CFD Method for Slosh Damping Extraction of Baffled Tanks

    NASA Technical Reports Server (NTRS)

    Yang, H. Q.; West, Jeff

    2016-01-01

    Determination of slosh damping is a very challenging task as there is no analytical solution. The damping physics involve the vorticity dissipation which requires the full solution of the nonlinear Navier-Stokes equations. As a result, previous investigations and knowledge were mainly carried out by extensive experimental studies. A Volume-Of-Fluid (VOF) based CFD program developed at NASA MSFC was applied to extract slosh damping in a baffled tank from the first principle. First, experimental data using water with subscale smooth wall tank were used as the baseline validation. CFD simulation was demonstrated to be capable of accurately predicting natural frequency and very low damping value from the smooth wall tank at different fill levels. The damping due to a ring baffle at different liquid fill levels from barrel section and into the upper dome was then investigated to understand the slosh damping physics due to the presence of a ring baffle. Based on this study, the Root-Mean-Square error of our CFD simulation in estimating slosh damping was less than 4.8%, and the maximum error was less than 8.5%. Scalability of subscale baffled tank test using water was investigated using the validated CFD tool, and it was found that unlike the smooth wall case, slosh damping with baffle is almost independent of the working fluid and it is reasonable to apply water test data to the full scale LOX tank when the damping from baffle is dominant. On the other hand, for the smooth wall, the damping value must be scaled according to the Reynolds number. Comparison of experimental data, CFD, with the classical and modified Miles equations for upper dome was made, and the limitations of these semi-empirical equations were identified.

  11. Placental endoplasmic reticulum stress negatively regulates transcription of placental growth factor via ATF4 and ATF6β: implications for the pathophysiology of human pregnancy complications.

    PubMed

    Mizuuchi, Masahito; Cindrova-Davies, Tereza; Olovsson, Matts; Charnock-Jones, D Stephen; Burton, Graham J; Yung, Hong Wa

    2016-03-01

    Low maternal circulating concentrations of placental growth factor (PlGF) are one of the hallmarks of human pregnancy complications, including fetal growth restriction (FGR) and early-onset pre-eclampsia (PE). Currently, PlGF is used clinically with other biomarkers to screen for high-risk cases, although the mechanisms underlying its regulation are largely unknown. Placental endoplasmic reticulum (ER) stress has recently been found to be elevated in cases of FGR, and to an even greater extent in early-onset PE complicated with FGR. ER stress activates the unfolded protein response (UPR); attenuation of protein translation and a reduction in cell growth and proliferation play crucial roles in the pathophysiology of these complications of pregnancy. In this study, we further identified that ER stress regulates release of PlGF. We first observed that down-regulation of PlGF protein was associated with nuclear localization of ATF4, ATF6α and ATF6β in the syncytiotrophoblast of placentae from PE patients. Transcript analysis showed a decrease of PlGF mRNA, and an increase from genes encoding those UPR transcription factors in placentae from cases of early-onset PE, but not of late-onset (>34 weeks) PE, compared to term controls. Further investigations indicated a strong correlation between ATF4 and PlGF mRNA levels only (r = - 0.73, p < 0.05). These results could be recapitulated in trophoblast-like cells exposed to chemical inducers of ER stress or hypoxia-reoxygenation. The stability of PlGF transcripts was unchanged. The use of small interfering RNA specific for transcription factors in the UPR pathways revealed that ATF4 and ATF6β, but not ATF6α, modulate PlGF transcription. To conclude, ATF4 and ATF6β act synergistically in the negative regulation of PlGF mRNA expression, resulting in reduced PlGF secretion by the trophoblast in response to stress. Therefore, these results further support the targeting of placental ER stress as a potential new therapeutic

  12. Electrorheologically damped impact system

    NASA Astrophysics Data System (ADS)

    Hardt, Lee R.

    1991-05-01

    An impact switch is described having a housing containing a rigid coaxial conductor entering one end. An inner cylindrical contact extends axially inward from and beyond the in housing end of an outer tubular contact which has a spiral spring extending axially from within a recess therein. The free end of the spring supports a mass spaced from the end of the inner contact. The contacts, spring and mass are enclosed within a flexible shroud spaced from the inner wall of the housing. The space between the shroud and housing contains an electrorheological fluid, the viscosity of which is a function of the voltage supplied by two electrodes extending through the housing and into the fluid. The voltage controlled viscosity permits control of damping of the shroud, mass, and spring movements in response to impact caused switch deceleration and control of time for switch closure and fuze delay by means of mass contact with the inner cylindrical contact, or spring contact with the outer tubular contact.

  13. Fast and reliable kicker magnets for the SLC damping rings

    SciTech Connect

    Mattison, T.S.; Cassel, R.L.; Donaldson, A.R.; Gross, G.

    1995-06-01

    The design, construction, and operation of a kicker magnet with superior electromagnetic performance and greatly improved radiation tolerance is described. A short flux return of high mu ferrite improves the field strength and linearity with current, and novel metallic field-confining structures minimize the inductance. An 8-cell structure with capacitance integrated into each cell makes the magnet a nearly perfect transmission line. The capacitor dielectric is 1 cm thick alumina-loaded epoxy, processed to eliminate air voids, and cast in a multiple step procedure developed to circumvent epoxy shrinkage. The magnet operates with pulses of up to 40 kV and 3.2 kA at 120 Hz, with magnet transit times of less than 35 nsec and field rise and fall times of less than 60 nsec.

  14. Damping measurements using operational data

    SciTech Connect

    James, G.H.; Carne, T.G.; Veers, P.S.

    1991-01-01

    We have measured modal damping using strain-gauge data from an operating wind turbine. Previously, such measurements were difficult and expensive. Auto-correlation and cross-correlation functions of the strain-gauge data have been shown to consist of decaying sinusoids which correspond to the modal frequencies and damping ratios of the wind turbine. We have verified the method by extracting damping values from an analytically generated data set. Actual operating response data from the DOE/Sandia 34-meter Test Bed has been used to calculate modal damping ratios as a function of rotor rotation rate. This capability will allow more accurate fatigue life prediction and control. 16 refs., 3 figs., 2 tabs.

  15. Landau damping in space plasmas

    NASA Technical Reports Server (NTRS)

    Thorne, Richard M.; Summers, Danny

    1991-01-01

    The Landau damping of electrostatic Langmuir waves and ion-acoustic waves in a hot, isotropic, nonmagnetized, generalized Lorentzian plasma is analyzed using the modified plasma dispersion function. Numerical solutions for the real and imaginary parts of the wave frequency omega sub 0 - (i)(gamma) have been obtained as a function of the normalized wave number (k)(lambda sub D), where lambda sub D is the electron Debye length. For both particle distributions the electrostatic modes are found to be strongly damped at short wavelengths. At long wavelengths, this damping becomes less severe, but the attenuation of Langmuir waves is much stronger for a generalized Lorentzian plasma than for a Maxwellian plasma. It is concluded that Landau damping of ion-acoustic waves is only slightly affected by the presence of a high energy tail, but is strongly dependent on the ion temperature.

  16. Vortex rings

    NASA Technical Reports Server (NTRS)

    Shariff, Karim; Leonard, Anthony

    1992-01-01

    The vortex-ring problem in fluid mechanics is examined generally in terms of formation, the steady state, the duration of the rings, and vortex interactions. The formation is studied by examining the generation of laminar and turbulent vortex rings and their resulting structures with attention given to the three stages of laminar ring development. Inviscid dynamics is addressed to show how core dynamics affects overall ring motion, and laminar vortex structures are described in two dimensions. Viscous and inviscid structures are related in terms of 'leapfrogging', head-on collisions, and collisions with a no-slip wall. Linear instability theory is shown to successfully describe observational data, although late stages in the breakdown are not completely understood. This study of vortex rings has important implications for key aerodynamic issues including sound generation, transport and mixing, and vortex interactions.

  17. Vibration damping method and apparatus

    DOEpatents

    Redmond, James M.; Barney, Patrick S.; Parker, Gordon G.; Smith, David A.

    1999-01-01

    The present invention provides vibration damping method and apparatus that can damp vibration in more than one direction without requiring disassembly, that can accommodate varying tool dimensions without requiring re-tuning, and that does not interfere with tool tip operations and cooling. The present invention provides active dampening by generating bending moments internal to a structure such as a boring bar to dampen vibration thereof.

  18. Vibration damping method and apparatus

    DOEpatents

    Redmond, J.M.; Barney, P.S.; Parker, G.G.; Smith, D.A.

    1999-06-22

    The present invention provides vibration damping method and apparatus that can damp vibration in more than one direction without requiring disassembly, that can accommodate varying tool dimensions without requiring re-tuning, and that does not interfere with tool tip operations and cooling. The present invention provides active dampening by generating bending moments internal to a structure such as a boring bar to dampen vibration thereof. 38 figs.

  19. Shape optimization of damping layers

    NASA Technical Reports Server (NTRS)

    Lin, T.-C.; Scott, R. A.

    1987-01-01

    Shape optimization of unconstrained and constrained damping layers is completed. The specific problem analyzed is a cantilever beam loaded at its tip by a harmonic force. Finite element modeling and mathematical programming techniques are used to obtain the solution. Performance measures are taken to be reduction of maximum diplacement and increase in fatigue lifetime. Results include the improvement, over the uniform treatment case, of these measures when the profile of the damping layer is optimized.

  20. Translucent Rings

    NASA Image and Video Library

    2014-12-08

    Although solid-looking in many images, Saturn's rings are actually translucent. In this picture, we can glimpse the shadow of the rings on the planet through (and below) the A and C rings themselves, towards the lower right hand corner. For centuries people have studied Saturn's rings, but questions about the structure and composition of the rings lingered. It was only in 1857 when the physicist James Clerk Maxwell demonstrated that the rings must be composed of many small particles and not solid rings around the planet, and not until the 1970s that spectroscopic evidence definitively showed that the rings are composed mostly of water ice. This view looks toward the sunlit side of the rings from about 17 degrees above the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on Aug. 12, 2014 in near-infrared light centered at 752 nanometers. The view was obtained at a distance of approximately 1.4 million miles (2.3 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 24 degrees. Image scale is 85 miles (136 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA18295

  1. Turbomachinery rotor support with damping

    NASA Technical Reports Server (NTRS)

    Vonpragenau, George L. (Inventor)

    1990-01-01

    Damping seals, damping bearings, and a support sleeve are presented for the ball bearings of a high speed rotor. The ball bearings consist of a duplex set having the outer races packaged tightly within the sleeve while the sleeve provides a gap with a support member so that the bearings may float with the sleeve. The sleeve has a web extending radially between the pair of outer races and acts in conjunction with one or more springs to apply an axial preload to the outer races. The sleeves have a series of slits which provide the sleeve with a spring-like quality so that the spring acts to center the rotor upon which the bearings are mounted during start up and shut down. A damping seal or a damping bearing may be used in conjunction with the ball bearings and supporting sleeve, the damping seal and damping bearing having rotor portions including rigid outer surfaces mounted within the bore of a stator portion having triangular shaped pockets on the surface facing the rotor. Axial gates are provided between adjacent pockets in sections of the stator permitting fluid to flow with less resistance axially relative to the flow of fluids circumferentially between the rotor and the stator.

  2. Damping Measurements of Plasma Modes

    NASA Astrophysics Data System (ADS)

    Anderegg, F.; Affolter, M.; Driscoll, C. F.

    2010-11-01

    For azimuthally symmetric plasma modes in a magnesium ion plasma, confined in a 3 Tesla Penning-Malmberg trap with a density of n ˜10^7cm-3, we measure a damping rate of 2s-1< γ< 10^4s-1 over a wide range in temperature (5 x10-6 eV< T < 5eV) and aspect ratio (0.25 < α< 25), with a wave amplitude of δn / n ˜5%. Changing the aspect ratio, α= Lp/ 2rp, of the plasma column, alters the frequency of the mode from 16 KHz to 192 KHz. The oscillatory fluid displacement is small compared to the wavelength of the mode; in contrast, the fluid velocity, δvf, can be large compared to v. The real part of the frequency satisfies a linear dispersion relation. In long thin plasmas (α> 10) these modes are Trivelpiece-Gould (TG) modes, and for smaller values of α they are Dubin spheroidal modes. However the damping appears to be non-linear; initially large waves have weaker exponential damping, which is not yet understood. Recent theoryootnotetextM.W. Anderson and T.M. O'Neil, Phys. Plasmas 14, 112110 (2007). calculates the damping of TG modes expected from viscosity due to ion-ion collisions; but the measured damping, while having a similar temperature and density dependence, is about 40 times larger than calculated. This discrepancy might be due to an external damping mechanism.

  3. Damping characterization in large structures

    NASA Technical Reports Server (NTRS)

    Eke, Fidelis O.; Eke, Estelle M.

    1991-01-01

    This research project has as its main goal the development of methods for selecting the damping characteristics of components of a large structure or multibody system, in such a way as to produce some desired system damping characteristics. The main need for such an analytical device is in the simulation of the dynamics of multibody systems consisting, at least partially, of flexible components. The reason for this need is that all existing simulation codes for multibody systems require component-by-component characterization of complex systems, whereas requirements (including damping) often appear at the overall system level. The main goal was met in large part by the development of a method that will in fact synthesize component damping matrices from a given system damping matrix. The restrictions to the method are that the desired system damping matrix must be diagonal (which is almost always the case) and that interbody connections must be by simple hinges. In addition to the technical outcome, this project contributed positively to the educational and research infrastructure of Tuskegee University - a Historically Black Institution.

  4. Analysis of ATF3, a transcription factor induced by physiological stresses and modulated by gadd153/Chop10.

    PubMed Central

    Chen, B P; Wolfgang, C D; Hai, T

    1996-01-01

    We demonstrate that ATF3, a member of the ATF/CREB family of transcription factors, is induced in a variety of stressed tissues: mechanically injured liver, toxin-injured liver, blood-deprived heart, and postseizure brain. We also demonstrate that an ATF3-interacting protein, gadd153/Chop10, forms a nonfunctional heterodimer with ATF3: the heterodimer, in contrast to the ATF3 homodimer, does not bind to the ATF/cyclic AMP response element consensus site and does not repress transcription. Interestingly, ATF3 and gadd153/Chop10 are expressed in inverse but overlapping manners during the liver's response to carbon tetrachloride (CCl4): the level of gadd153/Chop10 mRNA is high in the normal liver and greatly decreases upon CCl4 treatment; the level of ATF3 mRNA, on the other hand, is low in the normal liver and greatly increases upon CCl4 treatment. We hypothesize that in nonstressed liver, gadd153/Chop10 inhibits the limited amount of ATF3 by forming an inactive heterodimer with it, whereas in CCl4-injured liver, the synthesis of gadd153/Chop10 is repressed, allowing the induced ATF3 to function. PMID:8622660

  5. The Stress-responsive Gene ATF3 Mediates Dichotomous UV Responses by Regulating the Tip60 and p53 Proteins.

    PubMed

    Cui, Hongmei; Li, Xingyao; Han, Chunhua; Wang, Qi-En; Wang, Hongbo; Ding, Han-Fei; Zhang, Junran; Yan, Chunhong

    2016-05-13

    The response to UV irradiation is important for a cell to maintain its genetic integrity when challenged by environmental genotoxins. An immediate early response to UV irradiation is the rapid induction of activating transcription factor 3 (ATF3) expression. Although emerging evidence has linked ATF3 to stress pathways regulated by the tumor suppressor p53 and the histone acetyltransferase Tip60, the role of ATF3 in the UV response remains largely unclear. Here, we report that ATF3 mediated dichotomous UV responses. Although UV irradiation enhanced the binding of ATF3 to Tip60, knockdown of ATF3 expression decreased Tip60 stability, thereby impairing Tip60 induction by UV irradiation. In line with the role of Tip60 in mediating UV-induced apoptosis, ATF3 promoted the death of p53-defective cells in response to UV irradiation. However, ATF3 could also activate p53 and promote p53-mediated DNA repair, mainly through altering histone modifications that could facilitate recruitment of DNA repair proteins (such as DDB2) to damaged DNA sites. As a result, ATF3 rather protected the p53 wild-type cells from UV-induced apoptosis. Our results thus indicate that ATF3 regulates cell fates upon UV irradiation in a p53-dependent manner.

  6. Phosphorylation of activating transcription factor-2 (ATF-2) within the activation domain is a key determinant of sensitivity to tamoxifen in breast cancer.

    PubMed

    Rudraraju, Bharath; Droog, Marjolein; Abdel-Fatah, Tarek M A; Zwart, Wilbert; Giannoudis, Athina; Malki, Mohammed I; Moore, David; Patel, Hetal; Shaw, Jacqui; Ellis, Ian O; Chan, Steve; Brooke, Greg N; Nevedomskaya, Ekaterina; Lo Nigro, Christiana; Carroll, Jason; Coombes, R Charles; Bevan, Charlotte; Ali, Simak; Palmieri, Carlo

    2014-09-01

    Activating transcription factor-2 (ATF-2) has been implicated as a tumour suppressor in breast cancer (BC). c-JUN N-terminal kinase (JNK) and p38 MAPK phosphorylate ATF-2 within the activation domain (AD), which is required for its transcriptional activity. To date, the role of ATF-2 in determining response to endocrine therapy has not been explored. Effects of ATF-2 loss in the oestrogen receptor (ER)-positive luminal BC cell line MCF7 were explored, as well as its role in response to tamoxifen treatment. Genome-wide chromatin binding patterns of ATF-2 when phosphorylated within the AD in MCF-7 cells were determined using ChIP-seq. The expression of ATF-2 and phosphorylated ATF-2 (pATF-2-Thr71) was determined in a series of 1,650 BC patients and correlated with clinico-pathological features and clinical outcome. Loss of ATF-2 diminished the growth-inhibitory effects of tamoxifen, while tamoxifen treatment induced ATF-2 phosphorylation within the AD, to regulate the expression of a set of 227 genes for proximal phospho-ATF-2 binding, involved in cell development, assembly and survival. Low expression of both ATF-2 and pATF-2-Thr71 was significantly associated with aggressive pathological features. Furthermore, pATF-2 was associated with both p-p38 and pJNK1/2 (< 0.0001). While expression of ATF-2 is not associated with outcome, pATF-2 is associated with longer disease-free (p = 0.002) and BC-specific survival in patients exposed to tamoxifen (p = 0.01). Furthermore, multivariate analysis confirmed pATF-2-Thr71 as an independent prognostic factor. ATF-2 is important for modulating the effect of tamoxifen and phosphorylation of ATF-2 within the AD at Thr71 predicts for improved outcome for ER-positive BC receiving tamoxifen.

  7. Retinoic acid decreases ATF-2 phosphorylation and sensitizes melanoma cells to taxol-mediated growth inhibition.

    PubMed

    Huang, Ying; Minigh, Jennifer; Miles, Sarah; Niles, Richard M

    2008-02-12

    Cutaneous melanoma is often resistant to chemo- and radiotherapy. This resistance has recently been demonstrated to be due, at least in part, to high activating transcription factor 2 (ATF-2) activity in these tumors. In concordance with these reports, we found that B16 mouse melanoma cells had higher levels of ATF-2 than immortalized, but non-malignant mouse melanocytes. In addition, the melanoma cells had a much higher amount of phosphorylated (active) ATF-2 than the immortalized melanocytes. In the course of determining how retinoic acid (RA) stimulates activating protein-1 (AP-1) activity in B16 melanoma, we discovered that this retinoid decreased the phosphorylation of ATF-2. It appears that this effect is mediated through p38 MAPK, because RA decreased p38 phosphorylation, and a selective inhibitor of p38 MAPK (SB203580) also inhibited the phosphorylation of ATF-2. Since ATF-2 activity appears to be involved in resistance of melanoma to chemotherapy, we tested the hypothesis that treatment of the melanoma cells with RA would sensitize them to the growth-inhibitory effect of taxol. We found that pretreatment of B16 cells with RA decreased the IC50 from 50 nM to 1 nM taxol. On the basis of these findings and our previous work on AP-1, we propose a model in which treatment of B16 cells with RA decreases the phosphorylation of ATF-2, which results in less dimer formation with Jun. The "freed-up" Jun can then form a heterodimer with Fos, resulting in the increased AP-1 activity observed in RA-treated B16 cells. Shifting the balance from predominantly ATF-2:Jun dimers to a higher amount of Jun:Fos dimers could lead a change in target gene expression that reduces resistance to chemotherapeutic drugs and contributes to the pathway by which RA arrests proliferation and induces differentiation.

  8. Internet Cigarette Sales: Giving ATF Investigative Authority May Improve Reporting and Enforcement

    DTIC Science & Technology

    2002-08-01

    Title and Subtitle INTERNET CIGARETTE SALES: Giving ATF Investigative Authority May Improve Reporting and Enforcement Contract Number Grant Number...Report to Congressional Requesters United States General Accounting Office GAO August 2002 INTERNET CIGARETTE SALES Giving ATF Investigative...Authority May Improve Reporting and Enforcement GAO-02-743 Report Documentation Page Report Date 00AUG2002 Report Type N/A Dates Covered (from... to

  9. SAMS: The synchronization and monitoring system for ATF (Advanced Toroidal Facility) data acquisition

    SciTech Connect

    Greenwood, D.E.

    1987-01-01

    SAMS performs much of the synchronization of the distributed data acquisition system for the Advanced Toroidal Facility (ATF). SAMS is responsible for propagating shot information and managing te data system directories and logical names. This paper describes how SAMS communicates with other processes, both within the VAX cluster that supports most of the ATF data acquisition and on VAXes that are connected to the cluster via DECnet. 3 refs.

  10. Widening Rings

    NASA Image and Video Library

    2010-03-18

    Saturn rings and its moon Rhea are imaged before a crescent of the planet in this image captured by NASA Cassini spacecraft. The shadows of the rings continue to grow wider after their disappearing act during the planet August 2009 equinox.

  11. Planetary Rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.

    1994-01-01

    Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary ring particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary rings, and the fundamental questions were, why is Saturn the only planet with rings, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system

  12. Ring Slicer

    NASA Image and Video Library

    2015-07-06

    Saturn's moon Prometheus, seen here looking suspiciously blade-like, is captured near some of its sculpting in the F ring. Prometheus' (53 miles or 86 kilometers across) orbit sometimes takes it into the F ring. When it enters the ring, it leaves a gore where its gravitational influence clears out some of the smaller ring particles. Below Prometheus, the dark lanes interior to the F ring's bright core provide examples of previous ring-moon interactions. This view looks toward the unilluminated side of the rings from about 7 degrees below the ring plane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on March 15, 2015. The view was obtained at a distance of approximately 286,000 miles (461,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 115 degrees. Image scale is 1.7 miles (2.8 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA18324

  13. Planetary Rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.

    1994-01-01

    Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary ring particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary rings, and the fundamental questions were, why is Saturn the only planet with rings, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system

  14. Oxygen-dependent ATF-4 stability is mediated by the PHD3 oxygen sensor.

    PubMed

    Köditz, Jens; Nesper, Jutta; Wottawa, Marieke; Stiehl, Daniel P; Camenisch, Gieri; Franke, Corinna; Myllyharju, Johanna; Wenger, Roland H; Katschinski, Dörthe M

    2007-11-15

    The activating transcription factor-4 (ATF-4) is translationally induced under anoxic conditions, mediates part of the unfolded protein response following endoplasmic reticulum (ER) stress, and is a critical regulator of cell fate. Here, we identified the zipper II domain of ATF-4 to interact with the oxygen sensor prolyl-4-hydroxylase domain 3 (PHD3). The PHD inhibitors dimethyloxalylglycine (DMOG) and hypoxia, or proteasomal inhibition, all induced ATF-4 protein levels. Hypoxic induction of ATF-4 was due to increased protein stability, but was independent of the ubiquitin ligase von Hippel-Lindau protein (pVHL). A novel oxygen-dependent degradation (ODD) domain was identified adjacent to the zipper II domain. Mutations of 5 prolyl residues within this ODD domain or siRNA-mediated down-regulation of PHD3, but not of PHD2, was sufficient to stabilize ATF-4 under normoxic conditions. These data demonstrate that PHD-dependent oxygen-sensing recruits both the hypoxia-inducible factor (HIF) and ATF-4 systems, and hence not only confers adaptive responses but also cell fate decisions.

  15. ATF-2 immunoreactivity in post-mitotic and terminally differentiated human odontoblasts.

    PubMed

    Keklikoglu, Nurullah; Akinci, Sevtap

    2015-09-01

    Activating transcription factor 2 (ATF-2/CRE-BP1; cAMP-responsive element binding protein 1) is a member of nuclear transcription factor activator protein-1 (AP-1) family. AP-1 regulates cellular processes including growth, proliferation, differentiation and apoptosis. However, biological relationship of cellular process to each member of the AP-1 family is not clear yet. The objective of the present study was to compare the ATF-2 immunoreactivity in the post-mitotic and terminally differentiated odontoblasts and in the pulpal fibroblasts which can be divided by mitosis when required. Fibroblasts at various stages of differentiation co-exist in the human dental pulp. ATF-2 was investigated immunohistochemically in 20 permanent human teeth. According to the findings obtained, the mean percentage of ATF-2 positive cells was 68.5 ± 19.2% in the odontoblasts and 22.8 ± 13.7% in the pulpal fibroblasts. The comparison of ATF-2 positivity revealed a statistically significant difference between odontoblasts and pulpal fibroblasts. These findings have suggested that ATF-2 is more associated with cell survival rather than cell proliferation, and revealed much of effectiveness in maintaining terminal differentiation than the various differentiation stages of the cells.

  16. ATF3 acts as a rheostat to control JNK signalling during intestinal regeneration

    PubMed Central

    Zhou, Jun; Edgar, Bruce A.; Boutros, Michael

    2017-01-01

    Epithelial barrier function is maintained by coordination of cell proliferation and cell loss, whereas barrier dysfunction can lead to disease and organismal death. JNK signalling is a conserved stress signalling pathway activated by bacterial infection and tissue damage, often leading to apoptotic cell death and compensatory cell proliferation. Here we show that the stress inducible transcription factor ATF3 restricts JNK activity in the Drosophila midgut. ATF3 regulates JNK-dependent apoptosis and regeneration through the transcriptional regulation of the JNK antagonist, Raw. Enterocyte-specific ATF3 inactivation increases JNK activity and sensitivity to infection, a phenotype that can be rescued by Raw overexpression or JNK suppression. ATF3 depletion enhances intestinal regeneration triggered by infection, but does not compensate for the loss of enterocytes and ATF3-depleted flies succumb to infection due to intestinal barrier dysfunction. In sum, we provide a mechanism to explain how an ATF3-Raw module controls JNK signalling to maintain normal intestinal barrier function during acute infection. PMID:28272390

  17. Patulin induces colorectal cancer cells apoptosis through EGR-1 dependent ATF3 up-regulation

    PubMed Central

    Kwon, Osong; Soung, Nak Kyun; Thimmegowda, N.R.; Jeong, Sook Jung; Jang, Jae Hyuk; Moon, Dong-Oh; Chung, Jong Kyeong; Lee, Kyung Sang; Kwon, Yong Tae; Erikson, Raymond Leo; Ahn, Jong Seog; Kim, Bo Yeon

    2013-01-01

    Patulin is a fungal mycotoxin of Aspergilus and Penicillium that is commonly found in rotting fruits and exerts its potential toxic effect mainly by reactive oxygen species (ROS) generation. However, the effect of patulin on cancer cells as well as its intracellular mechanism has been controversial and not clearly defined yet. In this study, patulin was found to induce G1/S accumulation and cell growth arrest accompanied by caspase-3 activation, PARP cleavage and ATF3 expression in human colon cancer cell line HCT116. Ser/Thr phosphorylation of a transcription factor, EGR-1, was increased while its expression did not change upon patulin treatment to the cells. Knockdown of ATF3 and EGR-1 using their respective siRNAs showed EGR-1 dependent ATF3 expression. Moreover, treatment of the cells with antioxidants N-acetylcysteine (NAC) and glutathione (GSH) revealed that patulin induced ATF3 expression and apoptosis were dependent on ROS generation. ATF3 expression was also increased by patulin in other colorectal cancer cell types, Caco2 and SW620. Collectively, our data present a new anti-cancer molecular mechanism of patulin, suggesting EGR-1 and ATF3 as critical targets for the development of anti-cancer chemotherapeutics. In this regard, patulin could be a candidate for the treatment of colorectal cancers. PMID:22230687

  18. Patulin induces colorectal cancer cells apoptosis through EGR-1 dependent ATF3 up-regulation.

    PubMed

    Kwon, Osong; Soung, Nak Kyun; Thimmegowda, N R; Jeong, Sook Jung; Jang, Jae Hyuk; Moon, Dong-Oh; Chung, Jong Kyeong; Lee, Kyung Sang; Kwon, Yong Tae; Erikson, Raymond Leo; Ahn, Jong Seog; Kim, Bo Yeon

    2012-04-01

    Patulin is a fungal mycotoxin of Aspergilus and Penicillium that is commonly found in rotting fruits and exerts its potential toxic effect mainly by reactive oxygen species (ROS) generation. However, the effect of patulin on cancer cells as well as its intracellular mechanism has been controversial and not clearly defined yet. In this study, patulin was found to induce G1/S accumulation and cell growth arrest accompanied by caspase-3 activation, PARP cleavage and ATF3 expression in human colon cancer cell line HCT116. Ser/Thr phosphorylation of a transcription factor, EGR-1, was increased while its expression did not change upon patulin treatment to the cells. Knockdown of ATF3 and EGR-1 using their respective siRNAs showed EGR-1 dependent ATF3 expression. Moreover, treatment of the cells with antioxidants N-acetylcysteine (NAC) and glutathione (GSH) revealed that patulin induced ATF3 expression and apoptosis were dependent on ROS generation. ATF3 expression was also increased by patulin in other colorectal cancer cell types, Caco2 and SW620. Collectively, our data present a new anti-cancer molecular mechanism of patulin, suggesting EGR-1 and ATF3 as critical targets for the development of anti-cancer chemotherapeutics. In this regard, patulin could be a candidate for the treatment of colorectal cancers. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. An ATF4-ATG5 signaling in hypothalamic POMC neurons regulates obesity.

    PubMed

    Xiao, Yuzhong; Deng, Yalan; Yuan, Feixiang; Xia, Tingting; Liu, Hao; Li, Zhigang; Chen, Shanghai; Liu, Zhixue; Ying, Hao; Liu, Yi; Zhai, Qiwei; Guo, Feifan

    2017-03-28

    ATF4 (activating transcription factor 4) is an important transcription factor that has many biological functions, while its role in hypothalamic POMC (pro-opiomelanocortin-alpha) neurons in the regulation of energy homeostasis has not been explored. We recently discovered that mice with an Atf4 deletion specific to POMC neurons (PAKO mice) are lean and have higher energy expenditure. Furthermore, these mice are resistant to high-fat diet (HFD)-induced obesity and obesity-related metabolic disorders. Mechanistically, we found the expression of ATG5 (autophagy related 5) is upregulated in POMC neurons of PAKO mice, and ATF4 regulates ATG5 expression by binding directly to its promoter. Mice with Atf4 and Atg5 double knockout in POMC neurons have reduced energy expenditure and gain more fat mass compared with PAKO mice under a HFD. Finally, the effect of Atf4 knockout in POMC neurons is possibly mediated by enhanced ATG5-dependent macroautophagy/autophagy and α-melanocyte-stimulating hormone (α-MSH) production in the hypothalamus. Together, this work not only identifies a beneficial role for ATF4 in hypothalamic POMC neurons in the regulation of obesity, but also provides a new potential therapeutic target for obesity and obesity-related metabolic diseases.

  20. Development of Electronics for the ATF2 Interaction Point Region Beam Position Monitor

    SciTech Connect

    Kim, Youngim; Heo, Ae-young; Kim, Eun-San; Boogert, Stewart; Honda, Yosuke; Tauchi, Toshiaki; Terunuma, Nobuhiro; May, Justin; McCormick, Douglas; Smith, Tonee; /SLAC

    2012-08-14

    Nanometer resolution beam position monitors have been developed to measure and control beam position stability at the interaction point region of ATF2. The position of the beam has to be measured to within a few nanometers at the interaction point. In order to achieve this performance, electronics for the low-Q IP-BPM was developed. Every component of the electronics have been simulated and checked on the bench and using the ATF2 beam. We will explain each component and define their working range. Then, we will show the performance of the electronics measured with beam signal. ATF2 is a final focus test beam line for ILC in the framework of the ATF international collaboration. The new beam line was constructed to extend the extraction line at ATF, KEK, Japan. The first goal of ATF2 is the acheiving of a 37 nm vertical beam size at focal point (IP). The second goal is to stabilize the beam at the focal point at a few nanometer level for a long period in order to ensure the high luminosity. To achieve these goals a high resolution IP-BPM is essential. In addition for feedback applications a low-Q system is desirable.

  1. Sumoylation delays the ATF7 transcription factor subcellular localization and inhibits its transcriptional activity.

    PubMed

    Hamard, Pierre-Jacques; Boyer-Guittaut, Michaël; Camuzeaux, Barbara; Dujardin, Denis; Hauss, Charlotte; Oelgeschläger, Thomas; Vigneron, Marc; Kedinger, Claude; Chatton, Bruno

    2007-01-01

    Over the past few years, small ubiquitin-like modifier (SUMO) modification has emerged as an important regulator of diverse pathways and activities including protein localization and transcriptional regulation. We identified a consensus sumoylation motif (IKEE), located within the N-terminal activation domain of the ATF7 transcription factor and thus investigated the role of this modification. ATF7 is a ubiquitously expressed transcription factor, homologous to ATF2, that binds to CRE elements within specific promoters. This protein is able to heterodimerize with Jun or Fos proteins and its transcriptional activity is mediated by interaction with TAF12, a subunit of the general transcription factor TFIID. In the present article, we demonstrate that ATF7 is sumoylated in vitro (using RanBP2 as a E3-specific ligase) and in vivo. Moreover, we show that ATF7 sumoylation affects its intranuclear localization by delaying its entry into the nucleus. Furthermore, SUMO conjugation inhibits ATF7 transactivation activity by (i) impairing its association with TAF12 and (ii) blocking its binding-to-specific sequences within target promoters.

  2. Complexes containing activating transcription factor (ATF)/cAMP-responsive-element-binding protein (CREB) interact with the CCAAT/enhancer-binding protein (C/EBP)-ATF composite site to regulate Gadd153 expression during the stress response.

    PubMed Central

    Fawcett, T W; Martindale, J L; Guyton, K Z; Hai, T; Holbrook, N J

    1999-01-01

    Gadd153, also known as chop, encodes a member of the CCAAT/enhancer-binding protein (C/EBP) transcription factor family and is transcriptionally activated by cellular stress signals. We recently demonstrated that arsenite treatment of rat pheochromocytoma PC12 cells results in the biphasic induction of Gadd153 mRNA expression, controlled in part through binding of C/EBPbeta and two uncharacterized protein complexes to the C/EBP-ATF (activating transcription factor) composite site in the Gadd153 promoter. In this report, we identified components of these additional complexes as two ATF/CREB (cAMP-responsive-element-binding protein) transcription factors having differential binding activities dependent upon the time of arsenite exposure. During arsenite treatment of PC12 cells, we observed enhanced binding of ATF4 to the C/EBP-ATF site at 2 h as Gadd153 mRNA levels increased, and enhanced binding of ATF3 complexes at 6 h as Gadd153 expression declined. We further demonstrated that ATF4 activates, while ATF3 represses, Gadd153 promoter activity through the C/EBP-ATF site. ATF3 also repressed ATF4-mediated transactivation and arsenite-induced activation of the Gadd153 promoter. Our results suggest that numerous members of the ATF/CREB family are involved in the cellular stress response, and that regulation of stress-induced biphasic Gadd153 expression in PC12 cells involves the ordered, sequential binding of multiple transcription factor complexes to the C/EBP-ATF composite site. PMID:10085237

  3. Green tea catechin (−)-epicatechin gallate induces tumour suppressor protein ATF3 via EGR-1 activation

    PubMed Central

    Cho, Kyou-Nam; Sukhthankar, Mugdha; Lee, Seong-Ho; Yoon, Joo-Heon; Baek, Seung Joon

    2007-01-01

    Epicatechin gallate (ECG) is the third major catechin component in green tea, but it shows strong biological activity in some aspects, including apoptosis, cell growth inhibition, and membrane transport system in various cells. We previously reported that ECG induces activating transcription factor 3 (ATF3), which is involved in pro-apoptosis in HCT-116 cells. In this report, we present a molecular mechanism by which ECG induces ATF3 expression at the transcriptional level. We found that Sp3 contributed to the basal expression of the ATF3 gene, whereas EGR-1 played an important role in ECG-induced ATF3 expression in HCT-116 cells, as assessed by EMSA and co-transfection experiments. These results suggested that EGR-1, a tumour suppressor protein, could substantiate ECG’s role of ATF3 expression in human colorectal cancer cells. We also found that pro-oxidant activity of ECG contributed to ECG-induced ATF3 expression. PMID:17764926

  4. Damping mechanisms of a pendulum

    NASA Astrophysics Data System (ADS)

    Dolfo, Gilles; Castex, Daniel; Vigué, Jacques

    2016-11-01

    In this paper, we study the damping mechanisms of a pendulum. The originality of our setup is the use of a metal strip suspension and the development of extremely sensitive electric measurements of the pendulum velocity and position. Their sensitivity is absolutely necessary for a reliable measurement of the pendulum damping time constant because this measurement is possible only for very low oscillation amplitudes, when air friction forces quadratic in velocity have a negligible contribution to the observed damping. We have thus carefully studied damping by air friction forces, which is the dominant mechanism for large values of the Reynolds number Re but which is negligible in the Stokes regime, {Re} ∼ 1. In this last case, we have found that the dominant damping is due to internal friction in the metal strip, a universal effect called anelasticity, and, for certain frequencies, to resonant coupling to the support of the pendulum. All our measurements are well explained by theory. We believe this paper would be of interest to students in an undergraduate classical mechanics course.

  5. Damping modification factors for eastern Canada

    NASA Astrophysics Data System (ADS)

    Daneshvar, Poulad; Bouaanani, Najib

    2017-07-01

    This paper investigates damping modification factors in eastern Canada based on historical and simulated records compatible with seismic hazard in this region. Damping modification factors are characterized as a function of magnitude, distance, site condition, and damping ratio. Damping modification factors corresponding to historical and simulated ground motions on rock sites are shown to exhibit the same trends for all damping levels. In addition to period dependency of damping modification factors, we demonstrate their sensitivity to magnitude variations at longer periods. The effect of distance is shown to be less pronounced. It is also observed that soil conditions affect damping modification factors at short as well as longer periods. Period-dependent equations are proposed for practical assessment of damping modification factors corresponding to damping ratios between 1 and 40%, considering different magnitude-distance combinations and soil conditions representative of seismic hazard in eastern Canada.

  6. Increased damping of irregular resonators.

    PubMed

    Russ, S; Sapoval, B

    2002-03-01

    It is shown that fractal drums and jagged geometry resonators may be more damped than ordinary Euclidean systems. Several damping mechanisms are examined and studied by numerical calculations. The results depend on the dissipation mechanisms but globally they increase with localization, frequency, and the irregularity of the resonator. The increased dissipation is due to the uneven spatial distribution of the vibrational amplitude in two different ways. First, it is related to the partial confinement of the vibrational modes. Secondly, increased dissipation may be due to singularities in the amplitude distribution. This is the case when a few points exist where the vibration is pinned to zero inducing local logarithmic singularities. This last effect can be spectacular: a single defect can dominate the surface damping by viscous forces of a square drum.

  7. Increased damping in irregular resonators

    NASA Astrophysics Data System (ADS)

    Sapoval, Bernard; Asch, Mark; Felix, Simon; Filoche, Marcel

    2005-04-01

    The relation between shape and damping of shallow acoustical cavities has been studied numerically in the case where the dissipation occurs only on the cavity walls. It is first found that whatever the type of geometrical irregularity, many, but not all the modes are localized. It is shown that the localization mechanism is what is called weak localization. The more irregular, the smaller the quality factors are found. However this effect is very different for the non-localized and the localized modes. For non-localized modes the damping increases roughly proportionally to the cavity surface. The localized modes are even more damped. These results generalize the results already obtained both numerically and experimentally on prefractal acoustical cavities. [B. Sapoval, O. Haeberle, and S. Russ, J. Acoust. Soc. Am. 102, 2014-2019 (1997); B. Hebert, B. Sapoval, and S. Russ, ibid. 105, 1567-1576 (1999)].

  8. ATF (Advanced Toroidal Facility) flux surfaces and related plasma effects

    SciTech Connect

    Colchin, R.J.; England, A.C.; Harris, J.H.; Hillis, D.L.; Jernigan, T.C.; Murakami, M.; Neilson, G.H.; Rome, J.A.; Saltmarsh, M.J.; Anderson, F.S.B.

    1989-01-01

    Flux surfaces in the Advanced Toroidal Facility (ATF) were mapped using an electron beam which was incident on a fluorescent screen. Islands were found at r/a greater than or equal to 0.6, indicating the existence of field errors. Failure of the island size to scale with magnetic field indicated that the islands were intrinsic to the coils. The source of the field errors was found to be uncompensated dipoles in the helical coil feeds. The electron temperature was observed to be very low in the vicinity of the islands. Modifications were made to the helical field buswork to eliminate the field errors, and the flux surfaces were again checked using an electron beam. Islands at r/a greater than or equal to 0.6 were found to be greatly reduced in size, with the residual island at /tau/ = 1/2 scaling to 1 cm at B = 1 T. Initial experiments indicate that the plasma operating space has been extended since the buswork modifications. 4 refs., 3 figs.

  9. Effects of limiter biasing on the ATF torsatron

    SciTech Connect

    Uckan, T.; Baylor, L.R.; Bell, J.D.; Bigelow, T.S.; England, A.C.; Harris, J.H.; Isler, R.C.; Jernigan, T.C.; Lyon, J.F.; Ma, C.H.; Mioduszewski, P.K.; Murakami, M.; Rasmussen, D.A.; Wilgen, J.B. ); Aceto, S.C.; Zielinski, J.J. )

    1992-09-01

    Positive limiter biasing on the currentless Advanced Toroidal Facility (ATF) torsatron produces a significant increase in the particle confinement with no improvement in the energy confinement. Experiments have been carried out in 1-T plasmas with {approximately}400 kill of electron cyclotron heating ECM. Two rail limiters located at the last closed flux surface (LCFS), one at the top and one at the bottom of the device, are biased at positive and negative potentials with respect to the vessel. When the limiters are positively biased at up to 300 V, the density increases sharply to the ECH cutoff value. At the same time, the H{sub {alpha}} radiation drops, indicating that the particle confinement improves. When the density is kept constant, the H{sub {alpha}} radiation is further reduced and there is almost no change in the plasma stored energy. Under these conditions, the density profile becomes peaked and the electric field becomes outward-pointing outside the LCFS and more negative inside the LCFS. In contrast, negative biasing yields some reduction of the density and stored energy at constant gas feed, and the plasma potential profile remains the same. Biasing has almost no effect on the intrinsic impurity levels in the plasma.

  10. Landau damping of auroral hiss

    NASA Technical Reports Server (NTRS)

    Morgan, D. D.; Gurnett, D. A.; Menietti, J. D.; Winningham, J. D.; Burch, J. L.

    1994-01-01

    Auroral hiss is observed to propagate over distances comparable to an Earth radius from its source in the auroral oval. The role of Landau damping is investigated for upward propagating auroral hiss. By using a ray tracing code and a simplified model of the distribution function, the effect of Landau damping is calculated for auroral hiss propagation through the environment around the auroral oval. Landau damping is found to be the likely mechanism for explaining some of the one-sided auroral hiss funnels observed by Dynamics Explorer 1. It is also found that Landau damping puts a lower limit on the wavelength of auroral hiss. Poleward of the auroral oval, Landau damping is found in a typical case to limit omega/k(sub parallel) to values of 3.4 x 10(exp 4) km/s or greater, corresponding to resonance energies of 3.2 keV or greater and wavelengths of 2 km or greater. For equatorward propagation, omega/k(sub parallel) is limited to values greater than 6.8 x 10(exp 4) km/s, corresponding to resonance energies greater than 13 keV and wavelengths greater than 3 km. Independent estimates based on measured ratios of the magnetic to electric field intensity also show that omega/k(sub parallel) corresponds to resonance energies greater than 1 keV and wavelengths greater than 1 km. These results lead to the difficulty that upgoing electron beams sufficiently energetic to directly generate auroral hiss of the inferred wavelength are not usually observed. A partial transmission mechanism utilizing density discontinuities oblique to the magnetic field is proposed for converting auroral hiss to wavelengths long enough to avoid damping of the wave over long distances. Numerous reflections of the wave in an upwardly flared density cavity could convert waves to significantly increased wavelengths and resonance velocities.

  11. Landau damping of auroral hiss

    NASA Technical Reports Server (NTRS)

    Morgan, D. D.; Gurnett, D. A.; Menietti, J. D.; Winningham, J. D.; Burch, J. L.

    1994-01-01

    Auroral hiss is observed to propagate over distances comparable to an Earth radius from its source in the auroral oval. The role of Landau damping is investigated for upward propagating auroral hiss. By using a ray tracing code and a simplified model of the distribution function, the effect of Landau damping is calculated for auroral hiss propagation through the environment around the auroral oval. Landau damping is found to be the likely mechanism for explaining some of the one-sided auroral hiss funnels observed by Dynamics Explorer 1. It is also found that Landau damping puts a lower limit on the wavelength of auroral hiss. Poleward of the auroral oval, Landau damping is found in a typical case to limit omega/k(sub parallel) to values of 3.4 x 10(exp 4) km/s or greater, corresponding to resonance energies of 3.2 keV or greater and wavelengths of 2 km or greater. For equatorward propagation, omega/k(sub parallel) is limited to values greater than 6.8 x 10(exp 4) km/s, corresponding to resonance energies greater than 13 keV and wavelengths greater than 3 km. Independent estimates based on measured ratios of the magnetic to electric field intensity also show that omega/k(sub parallel) corresponds to resonance energies greater than 1 keV and wavelengths greater than 1 km. These results lead to the difficulty that upgoing electron beams sufficiently energetic to directly generate auroral hiss of the inferred wavelength are not usually observed. A partial transmission mechanism utilizing density discontinuities oblique to the magnetic field is proposed for converting auroral hiss to wavelengths long enough to avoid damping of the wave over long distances. Numerous reflections of the wave in an upwardly flared density cavity could convert waves to significantly increased wavelengths and resonance velocities.

  12. Berberine, a natural isoquinoline alkaloid, induces NAG-1 and ATF3 expression in human colorectal cancer cells.

    PubMed

    Piyanuch, Rojsanga; Sukhthankar, Mugdha; Wandee, Gritsanapan; Baek, Seung Joon

    2007-12-18

    Berberine is known to possess a wide variety of pharmacological activities, including pro-apoptotic activity. However, its molecular targets are not elucidated at present. NAG-1 and ATF3 are induced by several dietary compounds associated with pro-apoptotic activity. Berberine induces cell growth arrest, apoptosis, NAG-1, and ATF3 in human colorectal cancer cells. ATF3 induction by berberine is mediated in a p53-dependent manner, whereas NAG-1 induction by berberine is mediated by multiple signaling pathways. Our results suggest that berberine facilitates apoptosis and that NAG-1 and ATF3 expression plays an important role in berberine-induced apoptosis.

  13. Berberine, a natural isoquinoline alkaloid, induces NAG-1 and ATF3 expression in human colorectal cancer cells

    PubMed Central

    Piyanuch, Rojsanga; Sukhthankar, Mugdha; Baek, Seung Joon

    2007-01-01

    Berberine is known to possess a wide variety of pharmacological activities, including pro-apoptotic activity. However, its molecular targets are not elucidated at present. NAG-1 and ATF3 are induced by several dietary compounds associated with pro-apoptotic activity. Berberine induces cell growth arrest, apoptosis, NAG-1, and ATF3 in human colorectal cancer cells. ATF3 induction by berberine is mediated in a p53-dependent manner, whereas NAG-1 induction by berberine is mediated by multiple signaling pathways. Our results suggest that berberine facilitates apoptosis and that NAG-1 and ATF3 expression plays an important role in berberine-induced apoptosis. PMID:17964072

  14. ATF7 is stabilized during mitosis in a CDK1-dependent manner and contributes to cyclin D1 expression

    PubMed Central

    Schaeffer, Etienne; Vigneron, Marc; Sibler, Annie-Paule; Oulad-Abdelghani, Mustapha; Chatton, Bruno; Donzeau, Mariel

    2015-01-01

    The transcription factor ATF7 undergoes multiple post-translational modifications, each of which has distinct effects upon ATF7 function. Here, we show that ATF7 phosphorylation on residue Thr112 exclusively occurs during mitosis, and that ATF7 is excluded from the condensed chromatin. Both processes are CDK1/cyclin B dependent. Using a transduced neutralizing monoclonal antibody directed against the Thr112 epitope in living cells, we could demonstrate that Thr112 phosphorylation protects endogenous ATF7 protein from degradation, while it has no effect on the displacement of ATF7 from the condensed chromatin. The crucial role of Thr112 phosphorylation in stabilizing ATF7 protein during mitosis was confirmed using phospho-mimetic and phospho-deficient mutants. Finally, silencing ATF7 by CRISPR/Cas9 technology leads to a decrease of cyclin D1 protein expression levels. We propose that mitotic stabilized ATF7 protein re-localizes onto chromatin at the end of telophase and contributes to induce the cyclin D1 gene expression. PMID:26101806

  15. ATF7 is stabilized during mitosis in a CDK1-dependent manner and contributes to cyclin D1 expression.

    PubMed

    Schaeffer, Etienne; Vigneron, Marc; Sibler, Annie-Paule; Oulad-Abdelghani, Mustapha; Chatton, Bruno; Donzeau, Mariel

    2015-01-01

    The transcription factor ATF7 undergoes multiple post-translational modifications, each of which has distinct effects upon ATF7 function. Here, we show that ATF7 phosphorylation on residue Thr112 exclusively occurs during mitosis, and that ATF7 is excluded from the condensed chromatin. Both processes are CDK1/cyclin B dependent. Using a transduced neutralizing monoclonal antibody directed against the Thr112 epitope in living cells, we could demonstrate that Thr112 phosphorylation protects endogenous ATF7 protein from degradation, while it has no effect on the displacement of ATF7 from the condensed chromatin. The crucial role of Thr112 phosphorylation in stabilizing ATF7 protein during mitosis was confirmed using phospho-mimetic and phospho-deficient mutants. Finally, silencing ATF7 by CRISPR/Cas9 technology leads to a decrease of cyclin D1 protein expression levels. We propose that mitotic stabilized ATF7 protein re-localizes onto chromatin at the end of telophase and contributes to induce the cyclin D1 gene expression.

  16. Analysis of Ring Wake Simulations

    NASA Astrophysics Data System (ADS)

    Lewis, M. C.; Stewart, G. R.

    1999-09-01

    indent=20pt Collisional N-body simulations at the edge of a perturbed planetary ring are used to model the edges of the Encke gap in Saturn's rings. A small satellite, Pan, orbits inside the Encke gap and excites forced eccentricities and density wakes on both edges of the gap. The simulations use a local cell method to model a narrow ring using particles of the appropriate size for the A-ring at the proper optical depth. In the simulations we see evidence for shear reversal at the wake peaks. Our results imply that the most significant factor in the damping of the wakes is the reduction of the forced eccentricity and not randomization of the phase angles of the particles. The reduction of the forced eccentricity occurs in an orderly fashion with steep drops at each successive wake maximum following the highest density wake peak. indent=20pt At the inner edge (that nearer the perturber) we see phase shifts visible as bending of the line wake maxima. Because the simulations are actually of narrow rings, we also see a number of interesting phenomena at the outer edge. A strong boundary layer forms at that edge, which becomes partially detached from the rest of the ring. The wake patterns persist much further downstream in this boundary layer than they do in the rest of the ring. We also observe that in the less dense region between the main section of the ring and the boundary layer the magnitude of the forced eccentricities reverse their behavior in the main part and increase at each wake maxima. indent=20pt At the talk we will compare our results to the various analytic theories of Borderies, Goldreich, and Tremaine.

  17. Ring King

    NASA Image and Video Library

    2014-08-18

    Saturn reigns supreme, encircled by its retinue of rings. Although all four giant planets have ring systems, Saturn's is by far the most massive and impressive. Scientists are trying to understand why by studying how the rings have formed and how they have evolved over time. Also seen in this image is Saturn's famous north polar vortex and hexagon. This view looks toward the sunlit side of the rings from about 37 degrees above the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on May 4, 2014 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 752 nanometers. The view was acquired at a distance of approximately 2 million miles (3 million kilometers) from Saturn. Image scale is 110 miles (180 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA18278

  18. Remarks on modeling the flexible seal ring housing

    NASA Astrophysics Data System (ADS)

    Kundera, C.; Martsynkovskyy, V.; Zahorulko, A.

    2017-08-01

    When formulating models of dynamic face seals, two issues are of essential importance. The first concerns the determination of the forces formed in the medium film in the gap formed by the faces of two rings, while the second refers to the model of the flexible housing of one of the seal rings. The first issue includes the analysis of the medium flow through a narrow slit, taking thermal phenomena and deformations of slit-forming surfaces into account. The second issue concerns the modeling of properties of seal structural components, especially the modeling of elastic-damping properties of the flexible seal ring housing. This paper presents the results of simple relaxation tests of elastomeric rings and the procedure for analyzing these results and evaluating the elastic-damping properties of the rings tested. Finally, experimental results will be compared with theory.

  19. Rings from Close Encounters

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-09-01

    the centaur internal structure, its spin, and the distance of closest approach of the centaur to the giant planet. Blue and red represent icy and silicate material, respectively. [Hyodo et al. 2016]The outcomes of the close encounters are diverse, depending strongly on the internal structure and spin of the minor planet and the geometry of the encounter. But the team finds that, in many scenarios, the centaur is only partially destroyed by tidal forces from the giant as it passes close by.In these cases the icy mantle and even some of the centaurs core can be ripped away and scattered, becoming gravitationally bound to the largest remaining clump of the core. The particles travel in highly eccentric orbits, gradually damping as they collide with each other and forming a disk around the remaining core. Further dynamical evolution of this disk could easily shape the rings that we observe today around Chariklo and Chiron.If Hyodo and collaborators scenario is correct, then Chariklo and Chiron are differentiated bodies with dense silicate cores, and their rings are either pure water ice, or a mixture of water ice and a small amount of silicate. Future observations of these minor planets will help to test this model and observations of other centaurs may discover yet more ring systems hiding in our solar system!BonusCheck out this awesomeanimation from ESO showing an artists impression of thering system around Chariklo! [ESO/L. Calada/M. Kornmesser]CitationRyuki Hyodo et al 2016 ApJ 828 L8. doi:10.3847/2041-8205/828/1/L8

  20. Vascular rings.

    PubMed

    Backer, Carl L; Mongé, Michael C; Popescu, Andrada R; Eltayeb, Osama M; Rastatter, Jeffrey C; Rigsby, Cynthia K

    2016-06-01

    The term vascular ring refers to congenital vascular anomalies of the aortic arch system that compress the esophagus and trachea, causing symptoms related to those two structures. The most common vascular rings are double aortic arch and right aortic arch with left ligamentum. Pulmonary artery sling is rare and these patients need to be carefully evaluated for frequently associated tracheal stenosis. Another cause of tracheal compression occurring only in infants is the innominate artery compression syndrome. In the current era, the diagnosis of a vascular ring is best established by CT imaging that can accurately delineate the anatomy of the vascular ring and associated tracheal pathology. For patients with a right aortic arch there recently has been an increased recognition of a structure called a Kommerell diverticulum which may require resection and transfer of the left subclavian artery to the left carotid artery. A very rare vascular ring is the circumflex aorta that is now treated with the aortic uncrossing operation. Patients with vascular rings should all have an echocardiogram because of the incidence of associated congenital heart disease. We also recommend bronchoscopy to assess for additional tracheal pathology and provide an assessment of the degree of tracheomalacia and bronchomalacia. The outcomes of surgical intervention are excellent and most patients have complete resolution of symptoms over a period of time. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. The high mobility group protein HMG I(Y) can stimulate or inhibit DNA binding of distinct transcription factor ATF-2 isoforms.

    PubMed

    Du, W; Maniatis, T

    1994-11-22

    The high mobility group protein HMG I(Y) stimulates the binding of a specific isoform of the activating transcription factor 2 (ATF-2(195)) to the interferon beta (IFN-beta) gene promoter. HMG I(Y) specifically interacts with the basic-leucine zipper region of ATF-2(195), and HMG I(Y) binds to two sites immediately flanking the ATF-2 binding site of the IFN-beta promoter. Here, we show that HMG I(Y) can stimulate the binding of ATF-2(195), at least in part, by promoting ATF-2 dimerization. In addition, we report the characterization of a naturally occurring isoform of ATF-2 (ATF-2(192)) that binds specifically to the IFN-beta promoter but is unable to interact with HMG I(Y). Remarkably, HMG I(Y) inhibits the binding of ATF-2(192) to the IFN-beta promoter. Thus, the ability of HMG I(Y) to specifically interact with ATF-2 correlates with its ability to stimulate ATF-2 binding to the IFN-beta promoter. Comparisons of the amino acid sequences of the basic-leucine zipper domains of ATF-2(195) and ATF-2(192) suggest that HMG I(Y) interacts with a short stretch of basic amino acids near the amino terminus of the basic-leucine zipper domain of ATF-2(195).

  2. Saturn Ring

    NASA Image and Video Library

    2007-12-12

    Like Earth, Saturn has an invisible ring of energetic ions trapped in its magnetic field. This feature is known as a "ring current." This ring current has been imaged with a special camera on Cassini sensitive to energetic neutral atoms. This is a false color map of the intensity of the energetic neutral atoms emitted from the ring current through a processed called charged exchange. In this process a trapped energetic ion steals and electron from cold gas atoms and becomes neutral and escapes the magnetic field. The Cassini Magnetospheric Imaging Instrument's ion and neutral camera records the intensity of the escaping particles, which provides a map of the ring current. In this image, the colors represent the intensity of the neutral emission, which is a reflection of the trapped ions. This "ring" is much farther from Saturn (roughly five times farther) than Saturn's famous icy rings. Red in the image represents the higher intensity of the particles, while blue is less intense. Saturn's ring current had not been mapped before on a global scale, only "snippets" or areas were mapped previously but not in this detail. This instrument allows scientists to produce movies (see PIA10083) that show how this ring changes over time. These movies reveal a dynamic system, which is usually not as uniform as depicted in this image. The ring current is doughnut shaped but in some instances it appears as if someone took a bite out of it. This image was obtained on March 19, 2007, at a latitude of about 54.5 degrees and radial distance 1.5 million kilometres (920,000 miles). Saturn is at the center, and the dotted circles represent the orbits of the moon's Rhea and Titan. The Z axis points parallel to Saturn's spin axis, the X axis points roughly sunward in the sun-spin axis plane, and the Y axis completes the system, pointing roughly toward dusk. The ion and neutral camera's field of view is marked by the white line and accounts for the cut-off of the image on the left. The

  3. Surfactant damping of water waves

    NASA Astrophysics Data System (ADS)

    Lapham, Gary S.; Dowling, David R.; Schultz, William W.

    1997-11-01

    The most well known and perhaps most important distinguishing characteristic of a water surface laden with surfactant is the profound increase in small-wave damping with the addition of even small amounts of surfactant material. It would seem to follow that damping increases with increasing surfactant concentration. This is undoubtedly true for some surfactants, however our experiments with a soluble surfactant show that it is possible to increase surfactant concentration and measure a decrease in damping. While the increased concentration is accompanied by a dramatic decrease in measured static surface tension, some of the capillary-wave frequency regime is less damped. Experimental measurements of the real and imaginary parts of the wave speed are compared with existing theory where at least one other physical quantity besides surface tension is needed to properly model the interface. Our on-going work with insoluble surfactants may also provide an example of this type of behavior for materials that do not readily transfer to and from the bulk water. [Supported by the Office of Naval Research

  4. Dealing with damping-off

    USDA-ARS?s Scientific Manuscript database

    Damping-off is a common disease that rots and kills both seeds and recently germinated seedlings. The disease is caused by number of different soilborne pathogens, including true fungi (Botrytis, Fusarium, and Rhizoctonia species) and oomycetes (Phytophthora and Pythium species). The seedlings of mo...

  5. Vibration Damping Circuit Card Assembly

    NASA Technical Reports Server (NTRS)

    Hunt, Ronald Allen (Inventor)

    2016-01-01

    A vibration damping circuit card assembly includes a populated circuit card having a mass M. A closed metal container is coupled to a surface of the populated circuit card at approximately a geometric center of the populated circuit card. Tungsten balls fill approximately 90% of the metal container with a collective mass of the tungsten balls being approximately (0.07) M.

  6. Red cell DAMPs and inflammation.

    PubMed

    Mendonça, Rafaela; Silveira, Angélica A A; Conran, Nicola

    2016-09-01

    Intravascular hemolysis, or the destruction of red blood cells in the circulation, can occur in numerous diseases, including the acquired hemolytic anemias, sickle cell disease and β-thalassemia, as well as during some transfusion reactions, preeclampsia and infections, such as those caused by malaria or Clostridium perfringens. Hemolysis results in the release of large quantities of red cell damage-associated molecular patterns (DAMPs) into the circulation, which, if not neutralized by innate protective mechanisms, have the potential to activate multiple inflammatory pathways. One of the major red cell DAMPs, heme, is able to activate converging inflammatory pathways, such as toll-like receptor signaling, neutrophil extracellular trap formation and inflammasome formation, suggesting that this DAMP both activates and amplifies inflammation. Other potent DAMPs that may be released by the erythrocytes upon their rupture include heat shock proteins (Hsp), such as Hsp70, interleukin-33 and Adenosine 5' triphosphate. As such, hemolysis represents a major inflammatory mechanism that potentially contributes to the clinical manifestations that have been associated with the hemolytic diseases, such as pulmonary hypertension and leg ulcers, and likely plays a role in specific complications of sickle cell disease such as endothelial activation, vaso-occlusive processes and tissue injury.

  7. Damped Oscillator with Delta-Kicked Frequency

    NASA Technical Reports Server (NTRS)

    Manko, O. V.

    1996-01-01

    Exact solutions of the Schrodinger equation for quantum damped oscillator subject to frequency delta-kick describing squeezed states are obtained. The cases of strong, intermediate, and weak damping are investigated.

  8. Mutations in the unfolded protein response regulator ATF6 cause the cone dysfunction disorder achromatopsia

    PubMed Central

    Kohl, Susanne; Zobor, Ditta; Chiang, Wei-Chieh; Weisschuh, Nicole; Staller, Jennifer; Menendez, Irene Gonzalez; Chang, Stanley; Beck, Susanne C; Garrido, Marina Garcia; Sothilingam, Vithiyanjali; Seeliger, Mathias W; Stanzial, Franco; Benedicenti, Francesco; Inzana, Francesca; Héon, Elise; Vincent, Ajoy; Beis, Jill; Strom, Tim M; Rudolph, Günther; Roosing, Susanne; den Hollander, Anneke I; Cremers, Frans P M; Lopez, Irma; Ren, Huanan; Moore, Anthony T; Webster, Andrew R; Michaelides, Michel; Koenekoop, Robert K; Zrenner, Eberhart; Kaufman, Randal J; Tsang, Stephen H; Wissinger, Bernd; Lin, Jonathan H

    2015-01-01

    Achromatopsia (ACHM) is an autosomal recessive disorder characterized by color blindness, photophobia, nystagmus and severely reduced visual acuity. Using homozygosity mapping and whole-exome and candidate gene sequencing, we identified ten families carrying six homozygous and two compound-heterozygous mutations in the ATF6 gene (encoding activating transcription factor 6A), a key regulator of the unfolded protein response (UPR) and cellular endoplasmic reticulum (ER) homeostasis. Patients had evidence of foveal hypoplasia and disruption of the cone photoreceptor layer. The ACHM-associated ATF6 mutations attenuate ATF6 transcriptional activity in response to ER stress. Atf6−/− mice have normal retinal morphology and function at a young age but develop rod and cone dysfunction with increasing age. This new ACHM-related gene suggests a crucial and unexpected role for ATF6A in human foveal development and cone function and adds to the list of genes that, despite ubiquitous expression, when mutated can result in an isolated retinal photoreceptor phenotype. PMID:26029869

  9. Inhibition of tumor growth and metastasis by ATF-Fc, an engineered antibody targeting urokinase receptor.

    PubMed

    Hu, Xian-Wen; Duan, Hai-Feng; Gao, Li-Hua; Pan, Shu-Yuan; Li, Yong-Mei; Xi, Yongyi; Zhao, Su-Rong; Yin, Liang; Li, Jin-Feng; Chen, Hui-Peng; Wu, Chu-Tse

    2008-05-01

    Urokinase (uPA) and its receptor (uPAR) play an important role in tumor growth and metastasis, and overexpression of these molecules is strongly correlated with poor prognosis in a variety of malignant tumors. In this study, ATF-Fc, an antibody-like molecule comprising the amino-terminal fragment of human uPA (ATF) linked to the Fc fragment of human IgG1 via a flexible linker was developed. Its antitumor activities were evaluated in vitro and in vivo. The results showed that ATF-Fc had obvious cytotoxic effect on several types of tumor cells, which is dependent on cellular expression of uPAR and its Fc fragment. Treatment with ATF-Fc caused a significant suppression on tumor growth and metastasis of xenograft human tumors (MCF-7 breast cancer and BGC-823 gastric cancer) in athymic nude mice. Furthermore, we demonstrated that ATF-Fc had an anti-angiogenesis activity both in vitro and in vivo. In conclusion, we provided a novel therapeutic antibody-like molecule in the management of a variety of solid tumors by disrupting the uPA/uPAR interaction.

  10. Determinants of half-site spacing preferences that distinguish AP-1 and ATF/CREB bZIP domains.

    PubMed Central

    Kim, J; Struhl, K

    1995-01-01

    The AP-1 and ATF/CREB families of eukaryotic transcription factors are dimeric DNA-binding proteins that contain the bZIP structural motif. The AP-1 and ATF/CREB proteins are structurally related and recognize identical half-sites (TGAC), but they differ in their requirements for half-site spacing. AP-1 proteins such as yeast GCN4 preferentially bind to sequences with overlapping half-sites, whereas ATF/CREB proteins bind exclusively to sequences with adjacent half-sites. Here we investigate the distinctions between AP-1 and ATF/CREB proteins by determining the DNA-binding properties of mutant and hybrid proteins. First, analysis of GCN4-ATF1 hybrid proteins indicates that a short surface spanning the basic and fork regions of the bZIP domain is the major determinant of half-site spacing. Replacement of two GCN4 residues on this surface (Ala244 and Leu247) by their ATF1 counterparts largely converts GCN4 into a protein with ATF/CREB specificity. Secondly, analysis of a Fos derivative containing the GCN4 leucine zipper indicates that Fos represents a novel intermediate between AP-1 and ATF/CREB proteins. Thirdly, we examine the effects of mutations in the invariant arginine residue of GCN4 (Arg243) that contacts the central base pair(s) of the target sites. While most mutations abolish DNA binding, substitution of a histidine residue results in a GCN4 derivative with ATF/CREB binding specificity. These results suggest that the AP-1 and ATF/CREB proteins differ in positioning a short surface that includes the invariant arginine and that AP-1 proteins may represent a subclass (and perhaps evolutionary offshoot) of ATF/CREB proteins that can tolerate overlapping half-sites. Images PMID:7630732

  11. FIAT is co-expressed with its dimerization target ATF4 in early osteoblasts, but not in osteocytes.

    PubMed

    Yu, Vionnie W C; Akhouayri, Omar; St-Arnaud, René

    2009-06-01

    FIAT represses osteocalcin gene transcription by heterodimerizing with ATF4 and preventing it from binding to DNA. We report here the expression profiles of FIAT and ATF4 during osteoblastogenesis. Messenger RNA levels for the osteoblast transcriptional regulators Satb2, Runx2, Fiat, and Atf4 were quantified using real-time reverse-transcription PCR (RT-qPCR) and respective protein levels monitored by immunodetection in differentiating primary osteoblast cultures. Satb2, Fiat, and Atf4 mRNA levels remained constant throughout the differentiation sequence, whereas Runx2 transcript levels were significantly increased by 12 days post-confluency. Using immunofluorescence, the SATB2, RUNX2, and ATF4 signals appeared to increase as a function of time in culture. FIAT protein expression was readily detected in early cultures, but signal intensity decreased thereafter. When immunoblotting was used to quantify the relative amounts of FIAT and ATF4 proteins, the expression levels of the two proteins were found to be inversely correlated. The decrease in FIAT protein levels coincided with increased binding of ATF4 to the osteocalcin gene promoter, and with increased osteocalcin expression measured by RT-qPCR or immunoblotting. Immunohistochemistry of long bones from mice at E16.5 and 2 days post-natal revealed that both proteins are initially expressed in osteoblasts. In adult bone, FIAT was detected in osteocytes, while ATF4 expression was observed in active osteoblasts and lining cells, but not in osteocytes. Taken together, these data support the idea that a stoichiometric excess of ATF4 over FIAT in mature osteoblasts releases ATF4 from sequestration by FIAT, thereby allowing ATF4 homodimerization and subsequent transactivation of the osteocalcin gene.

  12. Storage-ring Electron Cooler for Relativistic Ion Beams

    SciTech Connect

    Lin, Fanglei; Derbenev, Yaroslav; Douglas, David R.; Guo, Jiquan; Johnson, Rolland P.; Krafft, Geoffrey A.; Morozov, Vasiliy; Zhang, Yuhong

    2016-05-01

    Application of electron cooling at ion energies above a few GeV has been limited due to reduction of electron cooling efficiency with energy and difficulty in producing and accelerating a high-current high-quality electron beam. A high-current storage-ring electron cooler offers a solution to both of these problems by maintaining high cooling beam quality through naturally-occurring synchrotron radiation damping of the electron beam. However, the range of ion energies where storage-ring electron cooling can be used has been limited by low electron beam damping rates at low ion energies and high equilibrium electron energy spread at high ion energies. This paper reports a development of a storage ring based cooler consisting of two sections with significantly different energies: the cooling and damping sections. The electron energy and other parameters in the cooling section are adjusted for optimum cooling of a stored ion beam. The beam parameters in the damping section are adjusted for optimum damping of the electron beam. The necessary energy difference is provided by an energy recovering SRF structure. A prototype linear optics of such storage-ring cooler is presented.

  13. FODO-Supercell Based Compact Ring Design with Tunable Momentum Compaction and Optimized Dynamic Aperture

    SciTech Connect

    Sun, Yipeng; /SLAC

    2012-05-11

    A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and pre-damping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a supercell is presented, which achieves a tunable momentum compaction while maintaining a large dynamic aperture.

  14. Squeezed states of damped oscillator chain

    NASA Technical Reports Server (NTRS)

    Manko, O. V.

    1993-01-01

    The Caldirola-Kanai model of one-dimensional damped oscillator is extended to the chain of coupled parametric oscillators with damping. The correlated and squeezed states for the chain of coupled parametric oscillators with damping are constructed. Based on the concept of the integrals of motion, it is demonstrated how squeezing phenomenon arises due to parametric excitation.

  15. The Secular Evolution of a Close Ring-Satellite System

    NASA Astrophysics Data System (ADS)

    Hahn, Joseph M.

    2006-06-01

    We use the rings model of Hahn (2003) to examine the secular evolution of a small satellite orbiting in a narrow gap in a dense planetary ring. The model shows that if the satellite has a small eccentricity, then its secular perturbations excites the eccentricities of the nearest ring particles orbiting at the gap edge. The ring's self-gravity then allows that disturbance to propagate outwards and across the ring in the form of a spiral density wave. Similarly, an inclined satellite also launches a spiral bending wave that propagates radially outwards from the gap's outer edge. When we use the rings model to consider Pan, which inhabits the Encke gap in Saturn's main A ring, we find that the satellite excites low amplitude spiral waves having very long wavelengths that are hundreds of km. Whether these low-amplitude waves might be observed by the Cassini spacecraft is also under investigation. The excitation of these waves transmits angular momentum from the satellite to the ring, so this form of wave-action tends to damp the satellite's eccentricity and inclination. Note that the fates of a satellite's eccentricity and inclination are uncertain when it orbits in a gap. This is due to the competition between the satellite's many Lindblad resonances in the ring, which excites the satellite's eccentricity, and and its corotation resonances, which might or might not damp its eccentricity (Goldreich and Tremaine 1980, Goldreich and Sari 2003). The satellite's inclination is also precarious, since its many vertical resonances in the ring tends to pump up the satellite's inclination (Borderies et al 1984). However, the rings model shows that the satellite's secular perturbation of the ring tends to damp its eccentricity and inclination at rates that dwarf the excitation mechanisms. The stability of the satellite's eccentricity and inclination thus seems assured.

  16. Luminescent Rings

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This view shows the unlit face of Saturn's rings, visible via scattered and transmitted light. In these views, dark regions represent gaps and areas of higher particle densities, while brighter regions are filled with less dense concentrations of ring particles.

    The dim right side of the image contains nearly the entire C ring. The brighter region in the middle is the inner B ring, while the darkest part represents the dense outer B Ring. The Cassini Division and the innermost part of the A ring are at the upper-left.

    Saturn's shadow carves a dark triangle out of the lower right corner of this image.

    The image was taken in visible light with the Cassini spacecraft wide-angle camera on June 8, 2005, at a distance of approximately 433,000 kilometers (269,000 miles) from Saturn. The image scale is 22 kilometers (14 miles) per pixel.

    The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

    For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

  17. Cave Rings

    DTIC Science & Technology

    2010-10-13

    hypothesis, that cave rings are formed in the same manner as coffee rings[3], that is, due to the enhanced deposition at the edges of sessile drops ...Literature The ‘splash ring’ conjecture is described in [5]. It is claimed that 45◦ is the most probable angle for secondary drops to be ejected at, and that...ring’ is the deposit formed when a sessile drop of a solution containing dissolved particles, such as coffee or salt, dries. This was investigated by

  18. Molecular pathway of near-infrared laser phototoxicity involves ATF-4 orchestrated ER stress.

    PubMed

    Khan, Imran; Tang, Elieza; Arany, Praveen

    2015-06-01

    High power lasers are used extensively in medicine while lower power applications are popular for optical imaging, optogenetics, skin rejuvenation and a therapeutic modality termed photobiomodulation (PBM). This study addresses the therapeutic dose limits, biological safety and molecular pathway of near-infrared (NIR) laser phototoxicity. Increased erythema and tissue damage were noted in mice skin and cytotoxicity in cell cultures at phototoxic laser doses involving generation of reactive oxygen species (ROS) coupled with a rise in surface temperature (>45 °C). NIR laser phototoxicity results from Activating Transcription Factor-4 (ATF-4) mediated endoplasmic reticulum stress and autophagy. Neutralizations of heat or ROS and overexpressing ATF-4 were noted to rescue NIR laser phototoxicity. Further, NIR laser mediated phototoxicity was noted to be non-genotoxic and non-mutagenic. This study outlines the mechanism of NIR laser phototoxicity and the utility of monitoring surface temperature and ATF4 expression as potential biomarkers to develop safe and effective clinical applications.

  19. ATF2 for Final Focus Test Beam for Future Linear Colliders

    NASA Astrophysics Data System (ADS)

    Kuroda, S.; ATF2 Collaboration

    2016-04-01

    In future linear colliders, extremely small beam size is required at collision point for high luminosity. For example, it is of order of nanometer in ILC(International Linear Collider). ATF2 is a project at ATF(Accelerator Test Facility) in KEK which demonstrates performance of final focus system experimentally. ATF2 beam line is a prototype of ILC final focus system where the local chromaticity correction scheme is adopted. The optics is basically the same and the natural chromaticity, too. Thus the tolerance of magnet alignment and field error is similar for both of the beam lines. We report here observation of small beam size of about 45nm there. We also report plan for smaller beam size with higher beam intensity.

  20. 28 CFR 16.106 - Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)-Limited Access.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 1 2011-07-01 2011-07-01 false Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)-Limited Access. 16.106 Section 16.106 Judicial Administration... the Privacy Act § 16.106 Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF...

  1. 28 CFR 16.106 - Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)-Limited Access.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)-Limited Access. 16.106 Section 16.106 Judicial Administration... the Privacy Act § 16.106 Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF...

  2. 28 CFR 16.106 - Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)-Limited Access.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 1 2013-07-01 2013-07-01 false Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)-Limited Access. 16.106 Section 16.106 Judicial Administration... the Privacy Act § 16.106 Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF...

  3. 28 CFR 16.106 - Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)-Limited Access.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 1 2014-07-01 2014-07-01 false Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)-Limited Access. 16.106 Section 16.106 Judicial Administration... the Privacy Act § 16.106 Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF...

  4. 28 CFR 16.106 - Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)-Limited Access.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 1 2012-07-01 2012-07-01 false Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)-Limited Access. 16.106 Section 16.106 Judicial Administration... the Privacy Act § 16.106 Exemption of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF...

  5. DAMPs, Ageing, and Cancer: The ‘DAMP Hypothesis’

    PubMed Central

    Huang, Jin; Xie, Yangchun; Sun, Xiaofang; Zeh, Herbert J.; Kang, Rui; Lotze, Michael T.; Tang, Daolin

    2014-01-01

    Ageing is a complex and multifactorial process characterized by the accumulation of many forms of damage at the molecular, cellular, and tissue level with advancing age. Ageing increases the risk of the onset of chronic inflammation-associated diseases such as cancer, diabetes, stroke, and neurodegenerative disease. In particular, ageing and cancer share some common origins and hallmarks such as genomic instability, epigenetic alteration, aberrant telomeres, inflammation and immune injury, reprogrammed metabolism, and degradation system impairment (including within the ubiquitin-proteasome system and the autophagic machinery). Recent advances indicate that damage-associated molecular pattern molecules (DAMPs) such as high mobility group box 1, histones, S100, and heat shock proteins play location-dependent roles inside and outside the cell. These provide interaction platforms at molecular levels linked to common hallmarks of ageing and cancer. They can act as inducers, sensors, and mediators of stress through individual plasma membrane receptors, intracellular recognition receptors (e.g., advanced glycosylation end product-specific receptors, AIM2-like receptors, RIG-I-like receptors, and NOD1-like receptors, and toll-like receptors), or following endocytic uptake. Thus, the DAMP Hypothesis is novel and complements other theories that explain the features of ageing. DAMPs represent ideal biomarkers of ageing and provide an attractive target for interventions in ageing and age-associated diseases. PMID:25446804

  6. A Compact Ring Design with Tunable Momentum Compaction

    SciTech Connect

    Sun, Y.; /SLAC

    2012-05-17

    A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and predamping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a supercell is presented, which achieves a tunable momentum compaction while maintaining a large dynamic aperture.

  7. Transcription factor ATF-3 regulates allele variation phenotypes of the human SLC11A1 gene.

    PubMed

    Taka, Styliani; Gazouli, Maria; Politis, Panagotis K; Pappa, Kalliopi I; Anagnou, Nicholas P

    2013-03-01

    Genetic polymorphisms in the human solute carrier family 11 member 1 (SLC11A1) gene predispose to susceptibility to infectious/inflammatory diseases and cancer. Human susceptibility to these diseases exhibits allelic association with a polymorphic regulatory Z-DNA-forming microsatellite of a (GT/AC)n repeat. The carriage of different alleles may influence chromatin remodeling and accessibility by transcription factors. Of particular importance is the binding site for the Activating Protein 1 (AP-1) elements, (ATF-3 and c-Jun), adjacent to the 5' sequence of the Z-DNA-forming polymorphism. The aim of the study was to characterize the transcriptional mechanisms controlling different alleles of SLC11A1 expression by ATF-3 and c-Jun. Allele 2, [T(GT)5AC(GT)5AC(GT)10GGCAGA(G)6], and Allele 3, [T(GT)5AC(GT)5AC(GT)9GGCAGA(G)6], were subcloned into the PGL2Basic vector. Transient transfections of THP-1 cells with the constructs, in the presence or absence of pATF-3 were preformed. Luciferase expression was determined. To document the recruitment of ATF-3 and c-Jun, to the polymorphic promoter alleles in vivo, we performed ChIP assays with transient transfected THP-1 cells treated with or without lipopolyssacharides. Our data documented that ATF-3 suppresses the transcriptional activation of Allele-3, and this suppression is enhanced in the presence of lipopolyssacharides. Our findings suggest that ATF-3 and c-Jun may influence heritable variation in SLC11A1-dependent innate resistance to infection and inflammation both within and between populations.

  8. Inhibition of ATF-3 expression by B-Raf mediates the neuroprotective action of GW5074.

    PubMed

    Chen, Hsin-Mei; Wang, Lulu; D'Mello, Santosh R

    2008-05-01

    GW5074 a brain-permeable 3' substituted indolone, protects neurons from death in culture and in an in vivo paradigm of neurodegeneration. Using low potassium (LK) induced apoptosis of cerebellar granule neurons, we report here that the protective action of GW5074 is mediated through the activation of B-Raf. Over-expression of a kinase-dead form of B-Raf blocks the ability of GW5074 to neuroprotect, whereas over-expression of active forms of B-Raf protect even in the absence of GW5074. Although mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated protein kinase (ERK) are activated by GW5074, pharmacological inhibition of MEK-ERK signaling by U0126 or PD98059 does not reduce neuroprotection suggesting that B-Raf signals through a non-canonical signaling pathway. GeneChip microarray analyses identified activating transcription factor-3 (ATF-3) as a gene whose expression is induced by LK but that is negatively regulated by GW5074. Forced inhibition of ATF-3 expression using siRNA protects neurons against LK-induced apoptosis, whereas the over-expression of ATF-3 blocks GW5074-mediated neuroprotection. Not unexpectedly, expression of active B-Raf inhibits the apoptosis-associated increase in ATF-3 expression. We extended our work to include three other 3' substituted indolones - a commercially available inhibitor of RNA-dependent protein kinase and two novel compounds designated as SK4 and SK6. Like GW5074, RNA-dependent protein kinase inhibitor, SK4, and SK6 all inhibited c-Raf in vitro but activated B-Raf in neuronal cultures. All four compounds also inhibited ATF-3 expression. Taken together our results indicate that all four indolones mediate neuroprotection by a common mechanism which involves B-Raf activation, and that a downstream target of B-Raf is ATF-3.

  9. A Multiyear Analysis of the Clinical Encounters of the ATF Tactical Medical Program.

    PubMed

    Tang, Nelson; Kubit, Josh; Berrett, Oliver M; Levy, Matthew J

    2014-01-01

    The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) Tactical Medical Program provides tactical medical support for ATF's tactical Special Response Teams (SRTs) and investigative National Response Teams (NRTs) through the deployment of specially trained ATF Agent-Medics. All patient care activities are centrally coordinated through ATF Headquarters. A retrospective analysis of de-identified patient care reports (PCRs) from the ATF Tactical Medical Program from 2009 to 2012 was performed. Clinical and operational data were extracted from PCRs and were entered into a database by the research team. Descriptive and summative analyses were performed to assess patient type, law enforcement incident type, chief complaint, and interventions performed. Analysis was performed on the 254 charts. Nearly half (114; 44.9%) of patients encountered during the study period were law enforcement officers. High-risk warrant service was associated with one third (85; 33.5%) of the ATF medics' clinical encounters. The most common chief complaints of patients encountered were musculoskeletal pain/injury (57; 22.4%) and wounds/lacerations (57; 22.4%), followed by heat illness (17; 6.7%). The most common intervention was wound care (61; 26.9%), followed by control of bleeding with direct pressure (43; 18.9%). The most common medications administered were ibuprofen (28; 25.2%), topical antibiotic (12; 10.8%), and acetaminophen (12;10.8%). This multiyear analysis represents an important contribution to the growing body of scientific literature surrounding tactical medicine. The results of this analysis demonstrate a continued need for expanded scope of practice training, as well as enhanced treatment protocols for tactical medics. 2014.

  10. Endoplasmic reticulum stress signal impairs erythropoietin production: a role for ATF4.

    PubMed

    Chiang, Chih-Kang; Nangaku, Masaomi; Tanaka, Tetsuhiro; Iwawaki, Takao; Inagi, Reiko

    2013-02-15

    Hypoxia upregulates the hypoxia-inducible factor (HIF) pathway and the endoplasmic reticulum (ER) stress signal, unfolded protein response (UPR). The cross talk of both signals affects the pathogenic alteration by hypoxia. Here we showed that ER stress induced by tunicamycin or thapsigargin suppressed inducible (CoCl(2) or hypoxia) transcription of erythropoietin (EPO), a representative HIF target gene, in HepG2. This suppression was inversely correlated with UPR activation, as estimated by expression of the UPR regulator glucose-regulated protein 78, and restored by an ER stress inhibitor, salubrinal, in association with normalization of the UPR state. Importantly, the decreased EPO expression was also observed in HepG2 overexpressing UPR activating transcription factor (ATF)4. Overexpression of mutated ATF4 that lacks the transcriptional activity did not alter EPO transcriptional regulation. Transcriptional activity of the EPO 3'-enhancer, which is mainly regulated by HIF, was abolished by both ER stressors and ATF4 overexpression, while nuclear HIF accumulation or expression of other HIF target genes was not suppressed by ER stress. Chromatin immunoprecipitation analysis identified a novel ATF4 binding site (TGACCTCT) within the EPO 3'-enhancer region, suggesting a distinct role for ATF4 in UPR-dependent suppression of the enhancer. Induction of ER stress in rat liver and kidney by tunicamycin decreased the hepatic and renal mRNA and plasma level of EPO. Collectively, ER stress selectively impairs the transcriptional activity of EPO but not of other HIF target genes. This effect is mediated by suppression of EPO 3'-enhancer activity via ATF4 without any direct effect on HIF, indicating that UPR contributes to oxygen-sensing regulation of EPO.

  11. ATF6 Is Mutated in Early Onset Photoreceptor Degeneration With Macular Involvement

    PubMed Central

    Xu, Mingchu; Gelowani, Violet; Eblimit, Aiden; Wang, Feng; Young, Marielle P.; Sawyer, Briana L.; Zhao, Li; Jenkins, Glen; Creel, Donnell J.; Wang, Keqing; Ge, Zhongqi; Wang, Hui; Li, Yumei; Hartnett, M. Elizabeth; Chen, Rui

    2015-01-01

    Purpose. Photoreceptor degeneration (PRD) is a genetically heterogeneous retinal disorder. Although a number of genes involved in PRD have been identified, their genetic basis remains unknown in a significant number of patients. In this study, we aimed to identify novel disease-causing genes of PRD. Methods. Comprehensive ocular examinations were performed in a 2-year-old patient diagnosed with early onset PRD. Retinal capture sequencing was performed to screen causative mutations in known retinal disease-causing loci. Whole-exome sequencing (WES) and a series of variant-filtering strategies were applied for identifying novel disease-causing genes. Retina ATF6 expression was confirmed by immunohistochemistry. RT-PCR was performed to identify ATF6 mRNA in the patient. Results. The patient showed typical PRD features, with macular involvement and ellipsoid zone irregularities. Results of retinal capture sequencing were negative. WES data led to identification of biallelic loss-of-function mutations in the ATF6 gene. The first variant generates a premature stop codon (NCBI accession no. NM_007348: c.1126C>T, p.R376*) and the second variant affects a splicing donor site (NM_007348: c.1533+1G>C). Sanger sequencing confirmed the 2 alleles are from 1 parent each. Both of the variants are extremely rare in the population. The splicing variant causes either intron inclusion or exon skipping in the patient, thus severely disrupting ATF6 functional domains. ATF6 is expressed in three neuronal cell layers of mouse retina. Conclusions. Our results support ATF6 as a novel disease-causing gene for PRD and suggest that disrupted protein quality control mechanisms may be a novel pathological mechanism underlying human retinal degeneration. PMID:26070061

  12. Cocured damped layers in composite structure

    SciTech Connect

    Rotz, C.A. ); Barrett, D.J. )

    1992-01-01

    A study was made on the feasibility of laminating and cocuring graphite fiber-epoxy prepreg with plies of commercially available damping materials for form beams and hat-stiffened panels. Experiments showed that cocuring did not adversely affect the damping materials and that excellent structural damping properties could be obtained. The construction of the hat-stiffened panels proved that complex parts containing damping materials could be fabricated. Dynamic testing of these components showed that internal architectural features could be designed to promote damping in primary structure.

  13. A Mechanical System Damping Measurement Technique Using a One-Degree-of-Freedom (1DOF) Cylindrical Gas Bearing

    DTIC Science & Technology

    1993-08-01

    sec for roll rate obtained with a one-spot tachometer ring, ± 0.001 in.-Ibf for viscous damping moment, or, in terms of energy dissipation, ± 1 mW. The...coulomb rolling-moment uncertainty could not be established because of its variable nature. 14. SUBJECT TERMS 15. NUMBER OF PAGES mechanical damping...to the moment to be deducted from all other data. For some classes of aerodynamic configurations at hypersonic speeds , the tare damping moment can

  14. Clipped viscous damping with negative stiffness for semi-active cable damping

    NASA Astrophysics Data System (ADS)

    Weber, F.; Boston, C.

    2011-04-01

    This paper investigates numerically and experimentally clipped viscous damping with negative stiffness for semi-active cable damping. From simulations it is concluded that unclipped and clipped viscous damping with negative stiffness is equivalent to unclipped and clipped LQR. It is shown that optimized unclipped viscous damping with negative stiffness generates critical cable damping by an anti-node at the actuator position. The resulting curvature at the actuator position is larger than the curvature close to the anchors due to the disturbance forces which may lead to premature cable fatigue at the actuator position. Optimized clipped viscous damping with negative stiffness does not show this drawback, can be implemented using a semi-active damper and produces twice as much cable damping as optimal viscous damping. Close to the optimal tuning, it leads to approximately the same control force as optimal semi-active friction damping with negative stiffness, which explains the superior cable damping. The superior damping results from the negative stiffness that increases the damper motion. Clipped viscous damping with negative stiffness is validated on a strand cable with a magneto-rheological damper. The measured cable damping is twice that achieved by emulated viscous damping, which confirms the numerical results. A tuning rule for clipped viscous damping with negative stiffness of real cables with flexural rigidity is given.

  15. 27 CFR 555.34 - Replacement of stolen or lost ATF Form 5400.30 (Intrastate Purchase of Explosives Coupon (IPEC)).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... lost ATF Form 5400.30 (Intrastate Purchase of Explosives Coupon (IPEC)). 555.34 Section 555.34 Alcohol... or lost ATF Form 5400.30 (Intrastate Purchase of Explosives Coupon (IPEC)). When any Form 5400.30 is... the Director by telephoning 1-888-ATF-BOMB (nationwide toll free number). The report will explain in...

  16. The transcription factor ATF7 mediates lipopolysaccharide-induced epigenetic changes in macrophages involved in innate immunological memory.

    PubMed

    Yoshida, Keisuke; Maekawa, Toshio; Zhu, Yujuan; Renard-Guillet, Claire; Chatton, Bruno; Inoue, Kentaro; Uchiyama, Takeru; Ishibashi, Ken-ichi; Yamada, Takuji; Ohno, Naohito; Shirahige, Katsuhiko; Okada-Hatakeyama, Mariko; Ishii, Shunsuke

    2015-10-01

    Immunological memory is thought to be mediated exclusively by lymphocytes. However, enhanced innate immune responses caused by a previous infection increase protection against reinfection, which suggests the presence of innate immunological memory. Here we identified an important role for the stress-response transcription factor ATF7 in innate immunological memory. ATF7 suppressed a group of genes encoding factors involved in innate immunity in macrophages by recruiting the histone H3K9 dimethyltransferase G9a. Treatment with lipopolysaccharide, which mimics bacterial infection, induced phosphorylation of ATF7 via the kinase p38, which led to the release of ATF7 from chromatin and a decrease in repressive histone H3K9me2 marks. A partially disrupted chromatin structure and increased basal expression of target genes were maintained for long periods, which enhanced resistance to pathogens. ATF7 might therefore be important in controlling memory in cells of the innate immune system.

  17. Impedance Calculation and Verification in Storage Rings

    SciTech Connect

    Bane, K.

    2005-01-31

    For both the SLC damping rings and the DAPHNE collider a systematic approach to understanding single bunch, longitudinal, current dependent behavior was taken: First, using a bunch significantly shorter than nominal, a careful calculation of the wakefield of the entire vacuum chamber was obtained. This ''pseudo-Green'' function was then used in bunch lengthening and instability calculations. We review, for both projects, the history of these calculations and comparisons with measurement.

  18. Studies of plasma performance and transport in the advanced toroidal facility (ATF)

    SciTech Connect

    Neilson, G.H.; Bigelow, T.S.; Carreras, B.A.; Colchin, R.J.; Crume, E.C.; Dunlap, J.L.; Dyer, G.R.; England, A.C.; Glowienka, J.C.; Halliwell, J.W.; Harris, J.H.; Hedrick, C.L.; Hillis, D.L.; Hiroe, S.; Horton, L.D.; Howe, H.C.; Isler, R.C.; Jernigan, T.C.; Langley, R.A.; Lue, J.W.; Lyon, J.F.; Ma, C.H.; Mioduszewski, P.K.; Murakami, M.; Rasmussen, D.A.; Schwenterly, S.W.; Shepard, T.D.; Simpkins, J.E.; Uckan, T.; Wilgen, J.B

    1989-01-01

    An overview of recent ATF experimental results and program plans is presented, with emphasis on the role of magnetic configuration controls in transport studies. The ATF operating space is bounded by a density limit that effectively sets a limit on the energy confinement time {tau}{sub E}. Although this limit is not solely due to impurities, it has recently been raised by improved cleanliness following titanium gettering. This has led to collapse-free neutral beam injection (NBI) discharges with global {tau}{sub E} {approx} 16 ms. Preliminary experiments show that stored energy and bootstrap current are sensitive to details of the magnetic configuration. 13 refs., 8 figs.

  19. Design of bunch compressing system with suppression of coherent synchrotron radiation for ATF upgrade

    SciTech Connect

    Jing, Yichao; Fedurin, Mikhail; Stratakis, Diktys

    2015-05-03

    One of the operation modes for Accelerator Test Facility (ATF) upgrade is to provide high peak current, high quality electron beam for users. Such operation requires a bunch compressing system with a very large compression ratio. The CSR originating from the strong compressors generally could greatly degrade the quality of the electron beam. In this paper, we present our design for the entire bunch compressing system that will limit the effect of CSR on the e-beam’s quality. We discuss and detail the performance from the start to end simulation of such a compressor for ATF.

  20. MicroRNA-451 regulates chemoresistance in renal cell carcinoma by targeting ATF-2 gene.

    PubMed

    Sun, Xiang; Lou, Longhua; Zhong, Kezhao; Wan, Lijuan

    2017-01-01

    Renal cell carcinoma (RCC) is a malignant tumor, which severely threatens human's life, moreover, the multi-drug resistance (MDR) under RCC undoubtedly strengthen the difficulties in the treatment. MiR-451 has been considered to play an important role in regulation of MDR in several cancers, but the role of it in MDR of RCC has not been explored. This study aims to explore the mechanism of miR-451 as a target to regulate chemotherapy resistance, which is crucial for further exploring novel therapy for RCC. Two human cell lines (ACHN and GRC-1) were performed in this study and adriamycin (ADM) was used to construct MDR cell lines. qRT-PCR was used to determine the mRNA expression of miR-451 and ATF-2. Weston blot was used to determine protein expression. MTT assay and flow cytometry were used for assessing cell viability and apoptosis, individually. Luciferase reporter assay was used to detect the targeting of miR-451 and ATF-2. Results presented that the expression of miR-451 was higher in low MDR cell line (ACHN) comparing with the high MDR cell line (GRC-1), while the expression of ATF-2 revealed an opposite results. MiR-451 targeted ATF-2 and regulated its expression. Overexpression of miR-451 strengthened drug resistance, decreased cell viability, and increased cell apoptosis of GRC-1 pretreated by ADM, while overexpressed ATF-2 reversed the effect induced by miR-451 overexpression. Then miR-451 knockdown improved drug susceptibility, decreased cell apoptosis, and increased cell viability of ACHN induced by ADM, however, ATF-2 suppression reversed the low rate of cell apoptosis and high rate of cell viability induced by miR-451 knockdown. Our results revealed that miR-451 regulates the drug resistance of RCC by targeting ATF-2 gene, which might be critical for overcoming MDR in RCC patients. Impact statement This is the first study to emphasize the expression of miR-451 on regulating multi-drug resistance (MDR) in renal cell carcinoma (RCC). Our study found

  1. A Comprehensive Study of Nanometer Resolution of the IPBPM at ATF2

    SciTech Connect

    Kim, Y.I.; Park, H.; Boogert, S.T.; Frisch, J.; McCormick, D.; Nelson, J.; Smith, T.; White, G.R.; Woodley, M.; Honda, Y.; Sugahara, R.; Terunuma, N.; Tauchi, T.; Urakawa, J.; /aff KEK, Tsukuba

    2011-12-13

    High-resolution beam position monitors (IPBPMs) have been developed in order to measure the electron beam position at the focus point of ATF2 to a few nanometers in the vertical plane. To date, the IPBPM system has operated in test mode with a highest demonstrated resolution of 8.7 nm in the ATF extraction line during 2008. After expected noise source calculations there still remains 7.9 nm of noise of unexplained origin. We summarize the experimental work on the IPBPM system since this measurement and outline the possible origins of these sources. We then present a study plan to be performed at the ATF2 facility designed to identify and to improve the resolution performance and comment on the expected ultimate resolution of this system. The Accelerator Test Facility 2 (ATF2) is a test beamline for ILC final focus system in the framework of the ATF international collaboration which was constructed to extend the extraction line at ATF, located at KEK, Japan. There are two goals of the ATF2: firstly to demonstrate focusing to 37 nm vertical beam size, secondly to achieve a few nanometer level beam orbit stability at the focus point in the vertical plane. High-resolution beam position monitors (IPBPMs) for the interaction point (IP) have been developed in order to measure the electron beam position at the focus point of the ATF2 to a few nanometers in the vertical plane. The previous measured position resolution of IPBPMs was 8.7 nm for a 0.68 x 10{sup 10} e/bunch beam with a dynamic range of 5 {mu}m. The intrinsic noise of the system was estimated to be 2.6 nm at 10{sup 10} e/bunch. It is scaled to 3.8 nm at 0.68 x 10{sup 10} e/bunch which means that 7.9 nm of unknown noise remains. The origin of the unknown noise must be studied in order to improve the resolution. This paper describes the ongoing work to improve the resolution of IPBPMs.

  2. Route Flap Damping Made Usable

    NASA Astrophysics Data System (ADS)

    Pelsser, Cristel; Maennel, Olaf; Mohapatra, Pradosh; Bush, Randy; Patel, Keyur

    The Border Gateway Protocol (BGP), the de facto inter-domain routing protocol of the Internet, is known to be noisy. The protocol has two main mechanisms to ameliorate this, MinRouteAdvertisementInterval (MRAI), and Route Flap Damping (RFD). MRAI deals with very short bursts on the order of a few to 30 seconds. RFD deals with longer bursts, minutes to hours. Unfortunately, RFD was found to severely penalize sites for being well-connected because topological richness amplifies the number of update messages exchanged. So most operators have disabled it. Through measurement, this paper explores the avenue of absolutely minimal change to code, and shows that a few RFD algorithmic constants and limits can be trivially modified, with the result being damping a non-trivial amount of long term churn without penalizing well-behaved prefixes' normal convergence process.

  3. Evaluation of SDRC Damping Analysis.

    DTIC Science & Technology

    1980-01-01

    Appendix C - Mechanical Analysis Dita Appendix D - Basic Program plus results Appendix E - American Bureau of Shipping Letter Appendix F - Power ...SEWC supplied a table of estimated roots and an associated damping power spectra. The tables of modal parameters and the data plots are connected by...appropriate table and plot. Appendix F provides a complete listing of all daping power spectras submitted by 51110. 2 Figure 6 (a,b,c) shows a plot of

  4. Effects of radiation and creep on viscoelastic damping materials

    NASA Astrophysics Data System (ADS)

    Henderson, John P.; Lewis, Tom M.; Murrell, Fred H.; Mangra, Danny

    1995-05-01

    The Advanced Photon Source (APS), under construction at Argonne National Laboratory (ANL), requires precise alignment of several large magnets. Submicron vibratory displacements of the magnets can degrade the performance of this important facility. Viscoelastic materials (VEM) have been shown to be effective in the control of the vibration of these magnets. Damping pads, placed under the magnet support structures in the APS storage ring, use thin layers of VEM. These soft VEM layers are subject to both high-energy radiation environment and continuous through-the-thickness compressive loads. Material experiments were conducted to answer concerns over the long term effects of the radiation environment and creep in the viscoelastic damping layers. The effects of exposure to radiation as high as 108 rad on the complex modulus were measured. Through-the-thickness creep displacements of VEM thin layers subjected to static loads of 50 psi were measured. Creep tests were conducted at elevated temperatures. Time-temperature equivalence principles were used to project creep displacements at room temperatures over several years. These damping material measurements should be of interest to vibration control engineers working with a variety of applications of fields ranging from aerospace to industrial machinery.

  5. Foucault pendulum with eddy-current damping of the elliptical motion

    NASA Astrophysics Data System (ADS)

    Mastner, G.; Vokurka, V.; Maschek, M.; Vogt, E.; Kaufmann, H. P.

    1984-10-01

    A newly designed Foucault pendulum is described in which the mechanical Charron ring, used throughout in previous designs for damping of the elliptical motion of the pendulum, is replaced by an electromagnetic eddy-current brake, consisting of a permanent magnet attached to the bottom of the bob and a metallic ring. This damping device is very efficient, as it is self-aligning, symmetrical in the damping effect, and never wears out. The permanent magnet is also used, together with a coil assembly and an electronic circuitry, for the dipole-torque drive of the pendulum as well as for accurate stabilization of the amplitude of the swing. A latched time display, controlled by Hall probes activated by the magnet, is used to visualize the Foucault rotation. The pendulum system and its associated electronic circuitry are described in detail. The optimizing of the drive mode is discussed. Measurements of deviations from theoretical value of the Foucault rotation velocity made automatically in a continuous run show a reproducible accuracy of ±1% or better in individual 360° rotations during the summer months. The quality factor of the pendulum as mechanical resonator was measured as a function of the amplitude in the presence of the eddy-current damping ring.

  6. Phosphorylation of the Conserved Transcription Factor ATF-7 by PMK-1 p38 MAPK Regulates Innate Immunity in Caenorhabditis elegans

    PubMed Central

    Kooistra, Tristan; Richardson, Claire E.; Reddy, Kirthi C.; Whitney, Janelle K.; Kamanzi, Odile; Matsumoto, Kunihiro; Hisamoto, Naoki; Kim, Dennis H.

    2010-01-01

    Innate immunity in Caenorhabditis elegans requires a conserved PMK-1 p38 mitogen-activated protein kinase (MAPK) pathway that regulates the basal and pathogen-induced expression of immune effectors. The mechanisms by which PMK-1 p38 MAPK regulates the transcriptional activation of the C. elegans immune response have not been identified. Furthermore, in mammalian systems the genetic analysis of physiological targets of p38 MAPK in immunity has been limited. Here, we show that C. elegans ATF-7, a member of the conserved cyclic AMP–responsive element binding (CREB)/activating transcription factor (ATF) family of basic-region leucine zipper (bZIP) transcription factors and an ortholog of mammalian ATF2/ATF7, has a pivotal role in the regulation of PMK-1–mediated innate immunity. Genetic analysis of loss-of-function alleles and a gain-of-function allele of atf-7, combined with expression analysis of PMK-1–regulated genes and biochemical characterization of the interaction between ATF-7 and PMK-1, suggest that ATF-7 functions as a repressor of PMK-1–regulated genes that undergoes a switch to an activator upon phosphorylation by PMK-1. Whereas loss-of-function mutations in atf-7 can restore basal expression of PMK-1–regulated genes observed in the pmk-1 null mutant, the induction of PMK-1–regulated genes by pathogenic Pseudomonas aeruginosa PA14 is abrogated. The switching modes of ATF-7 activity, from repressor to activator in response to activated PMK-1 p38 MAPK, are reminiscent of the mechanism of regulation mediated by the corresponding ancestral Sko1p and Hog1p proteins in the yeast response to osmotic stress. Our data point to the regulation of the ATF2/ATF7/CREB5 family of transcriptional regulators by p38 MAPK as an ancient conserved mechanism for the control of innate immunity in metazoans, and suggest that ATF2/ATF7 may function in a similar manner in the regulation of mammalian innate immunity. PMID:20369020

  7. Phosphorylation of the conserved transcription factor ATF-7 by PMK-1 p38 MAPK regulates innate immunity in Caenorhabditis elegans.

    PubMed

    Shivers, Robert P; Pagano, Daniel J; Kooistra, Tristan; Richardson, Claire E; Reddy, Kirthi C; Whitney, Janelle K; Kamanzi, Odile; Matsumoto, Kunihiro; Hisamoto, Naoki; Kim, Dennis H

    2010-04-01

    Innate immunity in Caenorhabditis elegans requires a conserved PMK-1 p38 mitogen-activated protein kinase (MAPK) pathway that regulates the basal and pathogen-induced expression of immune effectors. The mechanisms by which PMK-1 p38 MAPK regulates the transcriptional activation of the C. elegans immune response have not been identified. Furthermore, in mammalian systems the genetic analysis of physiological targets of p38 MAPK in immunity has been limited. Here, we show that C. elegans ATF-7, a member of the conserved cyclic AMP-responsive element binding (CREB)/activating transcription factor (ATF) family of basic-region leucine zipper (bZIP) transcription factors and an ortholog of mammalian ATF2/ATF7, has a pivotal role in the regulation of PMK-1-mediated innate immunity. Genetic analysis of loss-of-function alleles and a gain-of-function allele of atf-7, combined with expression analysis of PMK-1-regulated genes and biochemical characterization of the interaction between ATF-7 and PMK-1, suggest that ATF-7 functions as a repressor of PMK-1-regulated genes that undergoes a switch to an activator upon phosphorylation by PMK-1. Whereas loss-of-function mutations in atf-7 can restore basal expression of PMK-1-regulated genes observed in the pmk-1 null mutant, the induction of PMK-1-regulated genes by pathogenic Pseudomonas aeruginosa PA14 is abrogated. The switching modes of ATF-7 activity, from repressor to activator in response to activated PMK-1 p38 MAPK, are reminiscent of the mechanism of regulation mediated by the corresponding ancestral Sko1p and Hog1p proteins in the yeast response to osmotic stress. Our data point to the regulation of the ATF2/ATF7/CREB5 family of transcriptional regulators by p38 MAPK as an ancient conserved mechanism for the control of innate immunity in metazoans, and suggest that ATF2/ATF7 may function in a similar manner in the regulation of mammalian innate immunity.

  8. Nonlinear damping identification from transient data

    NASA Astrophysics Data System (ADS)

    Smith, Clifford B.; Wereley, Norman M.

    1999-06-01

    To study new damping augmentation methods for helicopter rotor systems, accurate and reliable nonlinear damping identification techniques are needed. For example, current studies on applications of magnetorheological (MR) dampers for rotor stability augmentation suggest that a strong Coulomb damping characteristic will be manifested as the field applied to the MR fluid is maximized. Therefore, in this work, a single degree of freedom (SDOF) system having either nonlinear Coulomb or quadratic damping is considered. This paper evaluates three analyses for identifying damping from transient test data; an FFT-based moving block analysis, an analysis based on a periodic Fourier series decomposition, and a Hilbert transform based technique. Analytical studies are used to determine the effects of block length, noise, and error in identified modal frequency on the accuracy of the identified damping level. The FFT-based moving block has unacceptable performance for systems with nonlinear damping. These problems were remedied in the Fourier series based analysis and acceptable performance is obtained for nonlinear damping identification from both this technique and the Hilbert transform based method. To more closely simulate a helicopter rotor system test, these techniques were then applied to a signal composed of two closely spaced modes. This data was developed to simulate a response containing the first lag and 1/rev modes. The primary mode of interest (simulated lag mode) had either Coulomb or quadratic damping, and the close mode (1/rev) was either undamped or had a specified viscous damping level. A comprehensive evaluation of the effects of close mode amplitude, frequency, and damping level was performed. A classifier was also developed to identify the dominant damping mechanism in a signal of 'unknown' composition. This classifier is based on the LMS error of a fit of the analytical envelope expression to the experimentally identified envelope signal. In most

  9. Development of Semi-Empirical Damping Equation for Baffled Tank with Oblate Spheroidal Dome

    NASA Technical Reports Server (NTRS)

    Yang, H. Q.; West, Jeff; Brodnick, Jacob; Eberhart, Chad

    2016-01-01

    Propellant slosh is a potential source of disturbance that can significantly impact the stability of space vehicles. The slosh dynamics are typically represented by a mechanical model of a spring-mass-damper. This mechanical model is then included in the equation of motion of the entire vehicle for Guidance, Navigation and Control analysis. The typical parameters required by the mechanical model include natural frequency of the slosh, slosh mass, slosh mass center location, and the critical damping ratio. A fundamental study has been undertaken at NASA MSFC to understand the fluid damping physics from a ring baffle in the barrel section of a propellant tank. An asymptotic damping equation and CFD blended equation have been derived by NASA MSFC team to complement the popularly used Miles equation at different flow regimes. The new development has found success in providing a nonlinear damping model for the Space Launch System. The purpose of this study is to further extend the semi-empirical damping equations into the oblate spheroidal dome section of the propellant tanks. First, previous experimental data from the spherical baffled tank are collected and analyzed. Several methods of taking the dome curvature effect, including a generalized Miles equation, area projection method, and equalized fill height method, are assessed. CFD simulation is used to shed light on the interaction of vorticity around the baffle with the locally curved wall and liquid-gas interface. The final damping equation will be validated by a recent subscale test with an oblate spheroidal dome conducted at NASA MSFC.

  10. KDM4C and ATF4 Cooperate in Transcriptional Control of Amino Acid Metabolism

    PubMed Central

    Xia, Yingfeng; Liu, Mengling; Ye, Bingwei; Choi, Jeong-Hyeon; Yan, Chunhong; Dong, Zheng; Huang, Shuang; Zha, Yunhong; Yang, Liqun; Cui, Hongjuan; Ding, Han-Fei

    2015-01-01

    SUMMARY The histone lysine demethylase KDM4C is often overexpressed in cancers primarily through gene amplification. The molecular mechanisms of KDM4C action in tumorigenesis are not well defined. Here we report that KDM4C transcriptionally activates amino acid biosynthesis and transport, leading to a significant increase in intracellular amino acid levels. Examination of the serine-glycine synthesis pathway reveals that KDM4C epigenetically activates the pathway genes under steady-state and serine deprivation conditions by removing the repressive histone modification H3 lysine 9 (H3K9) trimethylation. This action of KDM4C requires ATF4, a transcriptional master regulator of amino acid metabolism and stress responses. KDM4C activates ATF4 transcription and interacts with ATF4 to target serine pathway genes for transcriptional activation. We further present evidence for KDM4C in transcriptional coordination of amino acid metabolism and cell proliferation. These findings suggest a molecular mechanism linking KDM4C-mediated H3K9 demethylation and ATF4-mediated transactivation in reprogramming amino acid metabolism for cancer cell proliferation. PMID:26774480

  11. BESTIA (Brookhaven Experimental Supra-Terawatt Infrared at ATF) laser: A status report

    NASA Astrophysics Data System (ADS)

    Polyanskiy, Mikhail N.; Babzien, Marcus; Pogorelsky, Igor V.

    2017-03-01

    Development of a next-generation CO2 laser aiming at 100 TW peak power at a wavelength of 10 µm ts underway at the Brookhaven Accelerator Test Facility (ATF). A new laser facility is being deployed as part of the ATF-II upgrade. New high-pressure power amplifiers are being fabricated and assembled, while R&D continues with ATF's present 2 TW CO2 laser system. Our plan for increasing the peak laser power envisions several discrete steps in the upgrade. First will be demonstration of a 10 TW capability utilizing chirped pulse amplification, with an extended power amplifier chain filled with high-pressure isotopic gas. Further development aimed at a demonstration of 25 TW operation will require the addition of a nonlinear compressor system to shrink the pulse width below the nominal gain-bandwidth limit. These upgrades will then enable a longer-term R&D effort to achieve the 100 TW goal. Over the last two years, significant R&D effort has been focused on the development of chirped-pulse amplification, the study of the behavior of optical materials under the action of high-peak-power mid-IR pulses, and the optimization of the beam quality, which is required for nonlinear pulse compression. The results of this R&D have been implemented into the ongoing operation of the ATF's CO2 laser and have already benefited our users in their experimental programs.

  12. ATF4, A Novel Mediator of the Anabolic Actions of PTH on Bone

    DTIC Science & Technology

    2012-01-01

    element. Proc Natl Acad Sci USA 89:4820–4824. Kato JY, Matsuoka M, Polyak K, Massague J, Sherr CJ. 1994. Cyclic AMP- induced G1 phase arrest mediated...interaction of the HTLV-1 transactivator Tax with activating transcription factor-4 (ATF4). Oncogene 14:2785–2792. Roberts JM, Koff A, Polyak K, Firpo E

  13. ATF4, A Novel Mediator of the Anabolic Actions of PTH on Bone

    DTIC Science & Technology

    2011-07-01

    JY, Matsuoka M, Polyak K, Massague J, Sherr CJ. 1994. Cyclic AMP- induced G1 phase arrest mediated by an inhibitor (p27Kip1) of cyclin- dependent...activating transcription factor-4 (ATF4). Oncogene 14:2785–2792. Roberts JM, Koff A, Polyak K, Firpo E, Collins S, Ohtsubo M, Massague J. 1994. Cyclins

  14. ATF6α regulates morphological changes associated with senescence in human fibroblasts

    PubMed Central

    Martin, Nathalie; Saas, Laure; Cormenier, Johanna; Malaquin, Nicolas; Huot, Ludovic; Slomianny, Christian; Bouali, Fatima; Vercamer, Chantal; Hot, David; Pourtier, Albin; Chevet, Eric; Abbadie, Corinne; Pluquet, Olivier

    2016-01-01

    Cellular senescence is known as an anti-tumor barrier and is characterized by a number of determinants including cell cycle arrest, senescence associated β-galactosidase activity and secretion of pro-inflammatory mediators. Senescent cells are also subjected to enlargement, cytoskeleton-mediated shape changes and organelle alterations. However, the underlying molecular mechanisms responsible for these last changes remain still uncharacterized. Herein, we have identified the Unfolded Protein Response (UPR) as a player controlling some morphological aspects of the senescent phenotype. We show that senescent fibroblasts exhibit ER expansion and mild UPR activation, but conserve an ER stress adaptive capacity similar to that of exponentially growing cells. By genetically invalidating the three UPR sensors in senescent fibroblasts, we demonstrated that ATF6α signaling dictates senescence-associated cell shape modifications. We also show that ER expansion and increased secretion of the pro-inflammatory mediator IL6 were partly reversed by silencing ATF6α in senescent cells. Moreover, ATF6α drives the increase of senescence associated-β-galactosidase activity. Collectively, these findings unveil a novel and central role for ATF6α in the establishment of morphological features of senescence in normal human primary fibroblasts. PMID:27563820

  15. ATF6α regulates morphological changes associated with senescence in human fibroblasts.

    PubMed

    Druelle, Clémentine; Drullion, Claire; Deslé, Julie; Martin, Nathalie; Saas, Laure; Cormenier, Johanna; Malaquin, Nicolas; Huot, Ludovic; Slomianny, Christian; Bouali, Fatima; Vercamer, Chantal; Hot, David; Pourtier, Albin; Chevet, Eric; Abbadie, Corinne; Pluquet, Olivier

    2016-10-18

    Cellular senescence is known as an anti-tumor barrier and is characterized by a number of determinants including cell cycle arrest, senescence associated β-galactosidase activity and secretion of pro-inflammatory mediators. Senescent cells are also subjected to enlargement, cytoskeleton-mediated shape changes and organelle alterations. However, the underlying molecular mechanisms responsible for these last changes remain still uncharacterized. Herein, we have identified the Unfolded Protein Response (UPR) as a player controlling some morphological aspects of the senescent phenotype. We show that senescent fibroblasts exhibit ER expansion and mild UPR activation, but conserve an ER stress adaptive capacity similar to that of exponentially growing cells. By genetically invalidating the three UPR sensors in senescent fibroblasts, we demonstrated that ATF6α signaling dictates senescence-associated cell shape modifications. We also show that ER expansion and increased secretion of the pro-inflammatory mediator IL6 were partly reversed by silencing ATF6α in senescent cells. Moreover, ATF6α drives the increase of senescence associated-β-galactosidase activity. Collectively, these findings unveil a novel and central role for ATF6α in the establishment of morphological features of senescence in normal human primary fibroblasts.

  16. Dickkopf Homolog 3 Induces Stem Cell Differentiation into Smooth Muscle Lineage via ATF6 Signalling*

    PubMed Central

    Wang, Xiaocong; Karamariti, Eirini; Simpson, Russell; Wang, Wen; Xu, Qingbo

    2015-01-01

    Smooth muscle cells (SMCs) are a key component of healthy and tissue engineered vessels and play a crucial role in vascular development and the pathogenic events of vascular remodeling i.e. restenosis. However, the cell source from which they can be isolated is limited. Embryonic stem (ES) cells that have the remarkable capability to differentiate into vascular SMCs in response to specific stimuli provide a useful model for studying SMC differentiation. Previous studies suggested that dickkopf homolog 3 (DKK3) has a role in human partially induced pluripotent stem cell to SMC differentiation. Here, we demonstrate that the expression of DKK3 is essential for the expression of SMC markers and myocardin at both the mRNA and protein levels during mouse ES cell differentiation into SMCs (ESC-SMC differentiation). Overexpression of DKK3 leads to further up-regulation of the aforementioned markers. Further investigation indicates that DKK3 added as a cytokine activates activating transcription factor 6 (ATF6), leading to the increased binding of ATF6 on the myocardin promoter and increased its expression. In addition, inhibition of extracellular signal-regulated kinases 1/2 (ERK1/2) promotes the expression of ATF6 and leads to further increase of myocardin transcription. Our findings offer a novel mechanism by which DKK3 regulates ESC-SMC differentiation by activating ATF6 and promoting myocardin expression. PMID:26105053

  17. ATF3 increases the intrinsic growth state of DRG neurons to enhance peripheral nerve regeneration.

    PubMed

    Seijffers, Rhona; Mills, Charles D; Woolf, Clifford J

    2007-07-25

    Peripheral axons of dorsal root ganglion (DRG) neurons, but not their central axons in the dorsal columns, regenerate after injury. However, if the neurons are conditioned by a peripheral nerve injury into an actively growing state, the rate of peripheral axonal growth is accelerated and the injured central axons begin to regenerate. The growth-promoting effects of conditioning injuries have two components, increased axonal growth and a reduced response to inhibitory myelin cues. We have examined which transcription factors activated by peripheral axonal injury may mediate the conditioning effect by regulating expression of effectors that increase the intrinsic growth state of the neurons. Activating transcription factor 3 (ATF3) is a prime candidate because it is induced in all injured DRG neurons after peripheral, but not central, axonal damage. To investigate if ATF3 promotes regeneration, we generated transgenic mice that constitutively express this transcription factor in non-injured adult DRG neurons. The rate of peripheral nerve regeneration was enhanced in the transgenic mice to an extent comparable to that produced by a preconditioning nerve injury. The expression of some growth-associated genes, such as SPRR1A, but not others like GAP-43, was increased in the non-injured neurons. ATF3 increased DRG neurite elongation when cultured on permissive substrates but did not overcome the inhibitory effects of myelin or promote central axonal regeneration in the spinal cord in vivo. We conclude that ATF3 contributes to nerve regeneration by increasing the intrinsic growth state of injured neurons.

  18. Numerical study of self modulation instability of 1 nC electron bunch at ATF

    NASA Astrophysics Data System (ADS)

    Fang, Yun; Mori, Warren; Muggli, Patric

    2012-12-01

    The development of self-modulation instability (SMI) is investigated numerically for the 1 nC electron bunch available at Accelerator Test Facility (ATF) of Brookhaven National Laboratory (BNL). Possible experiment based on the simulation results is proposed. All the simulations are performed with the 2D-cylindrically symmetric particle-in-cell code.

  19. Neurodegenerative, with expression ATF-2 by p38 in cortical neurons.

    PubMed

    Hosseini, M; Ostad, N; Parivar, K; Ghahremani, M H

    2010-03-01

    DNA damage, as an important initiator of neuronal cell death, has been implicated in numerous neurodegenerative conditions. We previously delineated several pathways that control embryonic cortical neuronal cell death evoked by the DNA-damaging agent, camptothecin. The topisomerase-1 inhibitor, camptothecin, has been shown to induce cortical neuronal cell death in a reproducible and synchronistic manner. Primary embryonic neuronal cell culture cortical neurons were prepared. In the study, the survival % of neurons in camptothecin P38 group, after 6 hours (85%), 24 hours (64%) and 48 hours (50%), compared to camptothecin ATF-2 and P38 group after 4 hours (97 and 95%), have been significantly lower, and the expression % of neurons in camptothecin P38 group , after 6 hours (20%), 24 hours (40%) and 48 hours (55%), compared to camptothecin ATF-2 and P38 group after 4 hours (5 and 3%) have been significant lower (p<0.05). The expression % of neurons in camptothecin P38 group, after 24 hours (40%), compared to camptothecin ATF-2 group after 24hours (30%), have been significant lower (p<0.05). This study revealed that camptothecin induces P38 expression and P38 in embryonic cortical neurons to determine the importance of the P38 pathway in neuronal death following DNA damage, and P38 is induce phosphorylation of ATF-2 in embryonic cortical neurons following DNA damage.

  20. Melatonin, a novel selective ATF-6 inhibitor, induces human hepatoma cell apoptosis through COX-2 downregulation.

    PubMed

    Bu, Li-Jia; Yu, Han-Qing; Fan, Lu-Lu; Li, Xiao-Qiu; Wang, Fang; Liu, Jia-Tao; Zhong, Fei; Zhang, Cong-Jun; Wei, Wei; Wang, Hua; Sun, Guo-Ping

    2017-02-14

    To clarify the mechanisms involved in the critical endoplasmic reticulum (ER) stress initiating unfolded protein response pathway modified by melatonin. Hepatoma cells, HepG2, were cultured in vitro. Flow cytometry and TUNEL assay were used to measure HepG2 cell apoptosis. Western blotting and quantitative reverse transcription-polymerase chain reaction methods were used to determine the protein and messenger RNA levels of ER stress and apoptosis related genes' expression, respectively. Tissue microarray construction from patients was verified by immunohistochemical analysis. In the present study, we first identified that melatonin selectively blocked activating transcription factor 6 (ATF-6) and then inhibited cyclooxygenase-2 (COX-2) expression, leading to enhanced liver cancer cell apoptosis under ER stress condition. Dramatically increased CCAAT-enhancer-binding protein homologous protein level, suppressed COX-2 and decreased Bcl-2/Bax ratio by melatonin or ATF-6 siRNA contributed the enhanced HepG2 cell apoptosis under tunicamycin (an ER stress inducer) stimulation. In clinical hepatocellular carcinoma patients, the close relationship between ATF-6 and COX-2 was further confirmed. These findings indicate that melatonin as a novel selective ATF-6 inhibitor can sensitize human hepatoma cells to ER stress inducing apoptosis.

  1. Melatonin, a novel selective ATF-6 inhibitor, induces human hepatoma cell apoptosis through COX-2 downregulation

    PubMed Central

    Bu, Li-Jia; Yu, Han-Qing; Fan, Lu-Lu; Li, Xiao-Qiu; Wang, Fang; Liu, Jia-Tao; Zhong, Fei; Zhang, Cong-Jun; Wei, Wei; Wang, Hua; Sun, Guo-Ping

    2017-01-01

    AIM To clarify the mechanisms involved in the critical endoplasmic reticulum (ER) stress initiating unfolded protein response pathway modified by melatonin. METHODS Hepatoma cells, HepG2, were cultured in vitro. Flow cytometry and TUNEL assay were used to measure HepG2 cell apoptosis. Western blotting and quantitative reverse transcription-polymerase chain reaction methods were used to determine the protein and messenger RNA levels of ER stress and apoptosis related genes’ expression, respectively. Tissue microarray construction from patients was verified by immunohistochemical analysis. RESULTS In the present study, we first identified that melatonin selectively blocked activating transcription factor 6 (ATF-6) and then inhibited cyclooxygenase-2 (COX-2) expression, leading to enhanced liver cancer cell apoptosis under ER stress condition. Dramatically increased CCAAT-enhancer-binding protein homologous protein level, suppressed COX-2 and decreased Bcl-2/Bax ratio by melatonin or ATF-6 siRNA contributed the enhanced HepG2 cell apoptosis under tunicamycin (an ER stress inducer) stimulation. In clinical hepatocellular carcinoma patients, the close relationship between ATF-6 and COX-2 was further confirmed. CONCLUSION These findings indicate that melatonin as a novel selective ATF-6 inhibitor can sensitize human hepatoma cells to ER stress inducing apoptosis. PMID:28246472

  2. Shear contributions to cell culture performance and product recovery in ATF and TFF perfusion systems.

    PubMed

    Wang, Samantha; Godfrey, Scott; Ravikrishnan, Janani; Lin, Henry; Vogel, Jens; Coffman, Jon

    2017-03-20

    Achievement of a robust and scalable cell retention device remains a challenge in perfusion systems. Of the two filtration systems commonly used, tangential flow filtration (TFF) systems often have an inferior product sieving profile compared to alternating tangential flow filtration (ATF) systems, which is typically attributed to the ATF's unique alternating flow. Here, we demonstrate that observed performance differences between the two systems are a function of cell lysis and not the alternating flow as previously thought. The peristaltic pump used in typical TFF perfusion systems is shown to be the single major contributor to shear stress and cell lysis. Replacing the peristaltic pump with a low shear centrifugal pump brought cell growth, cell lysis, particle concentration, and product sieving in a TFF perfusion system to levels comparable with that of an ATF. These results provide a correlation where poor product sieving can be partially explained by high shear in cell retention systems and demonstrate that low shear TFF systems are a feasible alternative to ATF systems. Copyright © 2017 Boehringer Ingelheim. Published by Elsevier B.V. All rights reserved.

  3. KDM4C and ATF4 Cooperate in Transcriptional Control of Amino Acid Metabolism.

    PubMed

    Zhao, Erhu; Ding, Jane; Xia, Yingfeng; Liu, Mengling; Ye, Bingwei; Choi, Jeong-Hyeon; Yan, Chunhong; Dong, Zheng; Huang, Shuang; Zha, Yunhong; Yang, Liqun; Cui, Hongjuan; Ding, Han-Fei

    2016-01-26

    The histone lysine demethylase KDM4C is often overexpressed in cancers primarily through gene amplification. The molecular mechanisms of KDM4C action in tumorigenesis are not well defined. Here, we report that KDM4C transcriptionally activates amino acid biosynthesis and transport, leading to a significant increase in intracellular amino acid levels. Examination of the serine-glycine synthesis pathway reveals that KDM4C epigenetically activates the pathway genes under steady-state and serine deprivation conditions by removing the repressive histone modification H3 lysine 9 (H3K9) trimethylation. This action of KDM4C requires ATF4, a transcriptional master regulator of amino acid metabolism and stress responses. KDM4C activates ATF4 transcription and interacts with ATF4 to target serine pathway genes for transcriptional activation. We further present evidence for KDM4C in transcriptional coordination of amino acid metabolism and cell proliferation. These findings suggest a molecular mechanism linking KDM4C-mediated H3K9 demethylation and ATF4-mediated transactivation in reprogramming amino acid metabolism for cancer cell proliferation.

  4. Numerical study of self modulation instability of 1 nC electron bunch at ATF

    SciTech Connect

    Fang Yun; Mori, Warren; Muggli, Patric

    2012-12-21

    The development of self-modulation instability (SMI) is investigated numerically for the 1 nC electron bunch available at Accelerator Test Facility (ATF) of Brookhaven National Laboratory (BNL). Possible experiment based on the simulation results is proposed. All the simulations are performed with the 2D-cylindrically symmetric particle-in-cell code.

  5. ATF3 Expression in the corpus luteum: possible role in luteal regression

    USDA-ARS?s Scientific Manuscript database

    The present study investigated the induction and possible role of activating transcription factor 3 (ATF3) in the corpus luteum. Postpubertal cattle were treated at midcycle with prostaglandin F2alpha(PGF) for 0–4 hours. Luteal tissue was processed for immunohistochemistry, in situ hybridization, an...

  6. FIAT represses ATF4-mediated transcription to regulate bone mass in transgenic mice.

    PubMed

    Yu, Vionnie W C; Ambartsoumian, Gourgen; Verlinden, Lieve; Moir, Janet M; Prud'homme, Josée; Gauthier, Claude; Roughley, Peter J; St-Arnaud, René

    2005-05-23

    We report the characterization of factor inhibiting activating transcription factor 4 (ATF4)-mediated transcription (FIAT), a leucine zipper nuclear protein. FIAT interacted with ATF4 to inhibit binding of ATF4 to DNA and block ATF4-mediated transcription of the osteocalcin gene in vitro. Transgenic mice overexpressing FIAT in osteoblasts also had reduced osteocalcin gene expression and decreased bone mineral density, bone volume, mineralized volume, trabecular thickness, trabecular number, and decreased rigidity of long bones. Mineral homeostasis, osteoclast number and activity, and osteoblast proliferation and apoptosis were unchanged in transgenics. Expression of osteoblastic differentiation markers was largely unaffected and type I collagen synthesis was unchanged. Mineral apposition rate was reduced in transgenic mice, suggesting that the lowered bone mass was due to a decline in osteoblast activity. This cell-autonomous decrease in osteoblast activity was confirmed by measuring reduced alkaline phosphatase activity and mineralization in primary osteoblast cultures. These results show that FIAT regulates bone mass accrual and establish FIAT as a novel transcriptional regulator of osteoblastic function.

  7. ATF4 is Necessary and Sufficient for ER Stress-induced Upregulation of REDD1 Expression

    PubMed Central

    Whitney, Michael L.; Jefferson, Leonard S.; Kimball, Scot R.

    2009-01-01

    In response to a variety of cell stresses, e.g. endoplasmic reticulum (ER) stress, expression of REDD1 (regulated in development and DNA damage responses) is transcriptionally upregulated. However, the mechanism through which ER stress acts to upregulate REDD1 expression is unknown. In the present study, REDD1 expression was found to be upregulated by ER stress in several cell lines. However, in MEF cells lacking the eIF2α kinase PERK, ER stress failed to upregulate REDD1 expression, demonstrating that phosphorylation of eIF2α was necessary for the effect. Moreover, ER stress led to upregulated expression of the transcription factor ATF4, but in MEF cells lacking ATF4, REDD1 mRNA expression was not increased by ER stress. In contrast, exogenous expression of ATF4 was sufficient to induce REDD1 expression. Overall, the results suggest that REDD1 expression is upregulated during ER stress through a mechanism involving activation of PERK, phosphorylation of eIF2α, and increased ATF4 expression. PMID:19114033

  8. ATF4 plays a pivotal role in the development of functional hematopoietic stem cells in mouse fetal liver

    PubMed Central

    Zhao, Yunze; Zhou, Jie; Liu, Dan; Dong, Fang; Cheng, Hui; Wang, Weili; Pang, Yakun; Wang, Yajie; Mu, Xiaohuan; Ni, Yanli; Li, Zhuan; Xu, Huiyu; Hao, Sha; Wang, Xiaochen; Ma, Shihui; Wang, Qian-fei; Xiao, Guozhi; Yuan, Weiping; Liu, Bing

    2015-01-01

    The fetal liver (FL) serves as a predominant site for expansion of functional hematopoietic stem cells (HSCs) during mouse embryogenesis. However, the mechanisms for HSC development in FL remain poorly understood. In this study, we demonstrate that deletion of activating transcription factor 4 (ATF4) significantly impaired hematopoietic development and reduced HSC self-renewal in FL. In contrast, generation of the first HSC population in the aorta-gonad-mesonephros region was not affected. The migration activity of ATF4−/− HSCs was moderately reduced. Interestingly, the HSC-supporting ability of both endothelial and stromal cells in FL was significantly compromised in the absence of ATF4. Gene profiling using RNA-seq revealed downregulated expression of a panel of cytokines in ATF4−/− stromal cells, including angiopoietin-like protein 3 (Angptl3) and vascular endothelial growth factor A (VEGFA). Addition of Angptl3, but not VEGFA, partially rescued the repopulating defect of ATF4−/− HSCs in the culture. Furthermore, chromatin immunoprecipitation assay in conjunction with silencing RNA-mediated silencing and complementary DNA overexpression showed transcriptional control of Angptl3 by ATF4. To summarize, ATF4 plays a pivotal role in functional expansion and repopulating efficiency of HSCs in developing FL, and it acts through upregulating transcription of cytokines such as Angptl3 in the microenvironment. PMID:26384355

  9. Hyperosmotic stress-induced ATF-2 activation through Polo-like kinase 3 in human corneal epithelial cells.

    PubMed

    Wang, Ling; Payton, Reid; Dai, Wei; Lu, Luo

    2011-01-21

    Elevated extracellular solute concentration (hyperosmotic stress) perturbs cell function and stimulates cell responses by evoking MAPK cascades and activating AP-1 transcription complex resulting in alterations of gene expression, cell cycle arrest, and apoptosis. The results presented here demonstrate that hyperosmotic stress elicited increases in ATF-2 phosphorylation through a novel Polo-like kinase 3 (Plk3) pathway in human corneal epithelial (HCE) cells. We found in hyperosmotic stress-induced HCE cells that Plk3 transferred to the nuclear compartment and was colocalized with ATF-2 in nuclei. Kinase activity of Plk3 was significantly activated by hyperosmotic stimulation. Further downstream, active Plk3 phosphorylated ATF-2 at the Thr-71 site in vivo and in vitro. Overexpression of Plk3 and its mutants enhanced hyperosmotic stress-induced ATF-2 phosphorylation. In contrast, suppression of Plk3 by knocking down Plk3 mRNA effectively diminished the effect of hyperosmotic stress-induced ATF-2 phosphorylation. The effect of hyperosmotic stress-induced activation of Plk3 on ATF-2 transcription factor function was also examined in CRE reporter-overexpressed HCE cells. Our results for the first time reveal that hyperosmotic stress can activate the Plk3 signaling pathway that subsequently regulates the AP-1 complex by directly phosphorylating ATF-2 independent from the effects of JNK and p38 activation.

  10. The role of ATF-2 family transcription factors in adipocyte differentiation: antiobesity effects of p38 inhibitors.

    PubMed

    Maekawa, Toshio; Jin, Wanzhu; Ishii, Shunsuke

    2010-02-01

    ATF-2 is a member of the ATF/CREB family of transcription factors and is activated by stress-activated protein kinases, such as p38. To analyze the physiological role of ATF-2 family transcription factors, we have generated mice with mutations in Atf-2 and Cre-bpa, an Atf-2-related gene. The trans-heterozygotes of both mutants were lean and had reduced white adipose tissue (WAT). ATF-2 and CRE-BPa were required for bone morphogenetic protein 2 (BMP-2)-and p38-dependent induction of peroxisome proliferator-activated receptor gamma2 (PPARgamma2), a key transcription factor mediating adipocyte differentiation. Since stored fat supplies have been recognized as a possible target for antiobesity treatments, we tested whether inhibition of the p38-ATF-2 pathway suppresses adipocyte differentiation and leads to reduced WAT by treating mice with a p38 inhibitor for long periods of time. High-fat diet (HFD)-induced obesity was significantly reduced in mice fed the p38 inhibitor. Furthermore, the p38 inhibitor alleviated HFD-induced insulin resistance. In p38 inhibitor-treated mice, macrophage infiltration into WAT was reduced and the tumor necrosis factor alpha (TNF-alpha) levels were lower than control mice. Thus, p38 inhibitors may provide a novel antiobesity treatment.

  11. Hyperosmotic Stress-induced ATF-2 Activation through Polo-like Kinase 3 in Human Corneal Epithelial Cells*

    PubMed Central

    Wang, Ling; Payton, Reid; Dai, Wei; Lu, Luo

    2011-01-01

    Elevated extracellular solute concentration (hyperosmotic stress) perturbs cell function and stimulates cell responses by evoking MAPK cascades and activating AP-1 transcription complex resulting in alterations of gene expression, cell cycle arrest, and apoptosis. The results presented here demonstrate that hyperosmotic stress elicited increases in ATF-2 phosphorylation through a novel Polo-like kinase 3 (Plk3) pathway in human corneal epithelial (HCE) cells. We found in hyperosmotic stress-induced HCE cells that Plk3 transferred to the nuclear compartment and was colocalized with ATF-2 in nuclei. Kinase activity of Plk3 was significantly activated by hyperosmotic stimulation. Further downstream, active Plk3 phosphorylated ATF-2 at the Thr-71 site in vivo and in vitro. Overexpression of Plk3 and its mutants enhanced hyperosmotic stress-induced ATF-2 phosphorylation. In contrast, suppression of Plk3 by knocking down Plk3 mRNA effectively diminished the effect of hyperosmotic stress-induced ATF-2 phosphorylation. The effect of hyperosmotic stress-induced activation of Plk3 on ATF-2 transcription factor function was also examined in CRE reporter-overexpressed HCE cells. Our results for the first time reveal that hyperosmotic stress can activate the Plk3 signaling pathway that subsequently regulates the AP-1 complex by directly phosphorylating ATF-2 independent from the effects of JNK and p38 activation. PMID:21098032

  12. ATF4 plays a pivotal role in the development of functional hematopoietic stem cells in mouse fetal liver.

    PubMed

    Zhao, Yunze; Zhou, Jie; Liu, Dan; Dong, Fang; Cheng, Hui; Wang, Weili; Pang, Yakun; Wang, Yajie; Mu, Xiaohuan; Ni, Yanli; Li, Zhuan; Xu, Huiyu; Hao, Sha; Wang, Xiaochen; Ma, Shihui; Wang, Qian-fei; Xiao, Guozhi; Yuan, Weiping; Liu, Bing; Cheng, Tao

    2015-11-19

    The fetal liver (FL) serves as a predominant site for expansion of functional hematopoietic stem cells (HSCs) during mouse embryogenesis. However, the mechanisms for HSC development in FL remain poorly understood. In this study, we demonstrate that deletion of activating transcription factor 4 (ATF4) significantly impaired hematopoietic development and reduced HSC self-renewal in FL. In contrast, generation of the first HSC population in the aorta-gonad-mesonephros region was not affected. The migration activity of ATF4(-/-) HSCs was moderately reduced. Interestingly, the HSC-supporting ability of both endothelial and stromal cells in FL was significantly compromised in the absence of ATF4. Gene profiling using RNA-seq revealed downregulated expression of a panel of cytokines in ATF4(-/-) stromal cells, including angiopoietin-like protein 3 (Angptl3) and vascular endothelial growth factor A (VEGFA). Addition of Angptl3, but not VEGFA, partially rescued the repopulating defect of ATF4(-/-) HSCs in the culture. Furthermore, chromatin immunoprecipitation assay in conjunction with silencing RNA-mediated silencing and complementary DNA overexpression showed transcriptional control of Angptl3 by ATF4. To summarize, ATF4 plays a pivotal role in functional expansion and repopulating efficiency of HSCs in developing FL, and it acts through upregulating transcription of cytokines such as Angptl3 in the microenvironment.

  13. Activating Transcription Factor 4 (ATF4) modulates Rho GTPase levels and function via regulation of RhoGDIα

    PubMed Central

    Pasini, Silvia; Liu, Jin; Corona, Carlo; Peze-Heidsieck, Eugenie; Shelanski, Michael; Greene, Lloyd A.

    2016-01-01

    In earlier studies, we showed that ATF4 down-regulation affects post-synaptic development and dendritic spine morphology in neurons through increased turnover of the Rho GTPase Cell Division Cycle 42 (Cdc42) protein. Here, we find that ATF4 down-regulation in both hippocampal and cortical neuron cultures reduces protein and message levels of RhoGDIα, a stabilizer of the Rho GTPases including Cdc42. This effect is rescued by an shATF4-resistant active form of ATF4, but not by a mutant that lacks transcriptional activity. This is, at least in part, due to the fact that Arhgdia, the gene encoding RhoGDIα, is a direct transcriptional target of ATF4 as is shown in ChIP assays. This pathway is not restricted to neurons. This is seen in an impairment of cell migration on ATF4 reduction in non-neuronal cells. In conclusion, we have identified a new cellular pathway in which ATF4 regulates the expression of RhoGDIα that in turn affects Rho GTPase protein levels, and thereby, controls cellular functions as diverse as memory and cell motility. PMID:27841340

  14. Social isolation stress induces ATF-7 phosphorylation and impairs silencing of the 5-HT 5B receptor gene.

    PubMed

    Maekawa, Toshio; Kim, Seungjoon; Nakai, Daisuke; Makino, Chieko; Takagi, Tsuyoshi; Ogura, Hiroo; Yamada, Kazuyuki; Chatton, Bruno; Ishii, Shunsuke

    2010-01-06

    Many symptoms induced by isolation rearing of rodents may be relevant to neuropsychiatric disorders, including depression. However, identities of transcription factors that regulate gene expression in response to chronic social isolation stress remain elusive. The transcription factor ATF-7 is structurally related to ATF-2, which is activated by various stresses, including inflammatory cytokines. Here, we report that Atf-7-deficient mice exhibit abnormal behaviours and increased 5-HT receptor 5B (Htr5b) mRNA levels in the dorsal raphe nuclei. ATF-7 silences the transcription of Htr5B by directly binding to its 5'-regulatory region, and mediates histone H3-K9 trimethylation via interaction with the ESET histone methyltransferase. Isolation-reared wild-type (WT) mice exhibit abnormal behaviours that resemble those of Atf-7-deficient mice. Upon social isolation stress, ATF-7 in the dorsal raphe nucleus is phosphorylated via p38 and is released from the Htr5b promoter, leading to the upregulation of Htr5b. Thus, ATF-7 may have a critical role in gene expression induced by social isolation stress.

  15. ATF7IP-Mediated Stabilization of the Histone Methyltransferase SETDB1 Is Essential for Heterochromatin Formation by the HUSH Complex.

    PubMed

    Timms, Richard T; Tchasovnikarova, Iva A; Antrobus, Robin; Dougan, Gordon; Lehner, Paul J

    2016-10-11

    The histone methyltransferase SETDB1 plays a central role in repressive chromatin processes, but the functional requirement for its binding partner ATF7IP has remained enigmatic. Here, we show that ATF7IP is essential for SETDB1 stability: nuclear SETDB1 protein is degraded by the proteasome upon ablation of ATF7IP. As a result, ATF7IP is critical for repression that requires H3K9 trimethylation by SETDB1, including transgene silencing by the HUSH complex. Furthermore, we show that loss of ATF7IP phenocopies loss of SETDB1 in genome-wide assays. ATF7IP and SETDB1 knockout cells exhibit near-identical defects in the global deposition of H3K9me3, which results in similar dysregulation of the transcriptome. Overall, these data identify a critical functional role for ATF7IP in heterochromatin formation by regulating SETDB1 abundance in the nucleus.

  16. ICAN/DAMP-integrated composite analyzer with damping analysis capabilities: User's manual

    NASA Technical Reports Server (NTRS)

    Saravanos, Dimitrious A.; Sanfeliz, Jose G.

    1992-01-01

    This manual describes the use of the computer code ICAN/DAMP (Integrated Composite Analyzer with Damping Analysis Capabilities) for the prediction of damping in polymer-matrix composites. The code is written in FORTRAN 77 and is a version of the ICAN (Integrated Composite ANalyzer) computer program. The code incorporates a new module for synthesizing the material damping from micromechanics to laminate level. Explicit micromechanics equations based on hysteretic damping are programmed relating the on-axis damping capacities to the fiber and matrix properties and fiber volume ratio. The damping capacities of unidirectional composites subjected to off-axis loading are synthesized from on-axis damping values. The hygrothermal effect on the damping performance of unidirectional composites caused by temperature and moisture variation is modeled along with the damping contributions from interfacial friction between broken fibers and matrix. The temperature rise is continuously vibrating composite plies and composite laminates is also estimated. The ICAN/DAMP user's manual provides descriptions of the damping analysis module's functions, structure, input requirements, output interpretation, and execution requirements. It only addresses the changes required to conduct the damping analysis and is used in conjunction with the 'Second Generation Integrated Composite Analyzer (ICAN) Computer Code' user's manual (NASA TP-3290).

  17. Introduction to DAMPE event reconstruction (On behalf of DAMPE collaboration)

    NASA Astrophysics Data System (ADS)

    Zang, Jingjing

    2016-07-01

    The Dark Matter Particle Explorer (DAMPE) is a high energy particle physics experiment satellite, launched on 17 Dec 2015. To measure basic attributes of cosmic ray particles, DAMPE is equipped with four sub-detectors, BGO calorimeter (BGO), plastic scintillator detector (PSD), silicon tungsten tracker (STK) and neutron detector (NUD). On orbit, the high energy particle data are acquired and recorded by well-designed Data Acquisition system. After that, a series of elaborate event reconstruction algorithms are implemented to determine the energy, direction and particle ID of each event. The energy reconstruction algorithm firstly treats the sum of the BGO crystal energy as the overall energy estimator and various corrections are performed to calculate energy leakage from side and back of the calorimeter. The track reconstruction starts with cluster finding in STK, then shower axis of BGO and barycentre of clusters are used to extract seed of tracks. These seeds will be projected on the next layer by Kalman Filter method which will finally give location and direction of particle tracks. Based on shower development in BGO and tracks reconstructed by STK, we also combine data from PSD and NUD and developed a series of algorithms to evaluate particle's charge and identification. In this talk, we will describe technical strategies of event reconstruction and provide their basic performance.

  18. Damped transverse oscillations of interacting coronal loops

    NASA Astrophysics Data System (ADS)

    Soler, Roberto; Luna, Manuel

    2015-10-01

    Damped transverse oscillations of magnetic loops are routinely observed in the solar corona. This phenomenon is interpreted as standing kink magnetohydrodynamic waves, which are damped by resonant absorption owing to plasma inhomogeneity across the magnetic field. The periods and damping times of these oscillations can be used to probe the physical conditions of the coronal medium. Some observations suggest that interaction between neighboring oscillating loops in an active region may be important and can modify the properties of the oscillations. Here we theoretically investigate resonantly damped transverse oscillations of interacting nonuniform coronal loops. We provide a semi-analytic method, based on the T-matrix theory of scattering, to compute the frequencies and damping rates of collective oscillations of an arbitrary configuration of parallel cylindrical loops. The effect of resonant damping is included in the T-matrix scheme in the thin boundary approximation. Analytic and numerical results in the specific case of two interacting loops are given as an application.

  19. Critically stable damping in flexible structure control

    NASA Astrophysics Data System (ADS)

    Xing, Zhigang; Zheng, Gangtie

    2017-10-01

    The concept of critically stable damping and its application to flexible structure control are presented. Critically stable damping was originally noted from the viewpoint of control-structure integration. It was recognized that a slight augmentation of structural damping would result in substantially more robust control without decreased performance and could guarantee the stability margin for any structural frequency increase. This paper illustrates the wide occurrence of critically stable damping phenomenon, establishes its basic relationship for the insight of the general design procedure, and applies the concept into the practical design of a satellite with a large deployable antenna. It is noted that the critically stable damping concept could provide a feasible approach to overcome the difficulty in ultra-large space structure design and control, and enhance the performance of a variety of excellent control design methodologies for flexible structure control. This critically stable damping provides new insight into the integrated design of control and structure.

  20. Angiotensin II limits NO production by upregulating arginase through a p38 MAPK - ATF-2 pathway

    PubMed Central

    Shatanawi, Alia; Lemtalsi, Tahira; Yao, Lin; Patel, Chintan; Caldwell, Ruth B.; Caldwell, R. William

    2014-01-01

    Enhanced vascular arginase activity can impair endothelium-dependent vasorelaxation by decreasing L-arginine availability to endothelial nitric oxide (NO) synthase, thereby reducing NO production and uncoupling NOS function. Elevated angiotensin II (Ang II) is a key component of endothelial dysfunction in many cardiovascular diseases and has been linked to elevated arginase activity. In this study we explored the signaling pathway leading to increased arginase expression/activity in response to Ang II in bovine aortic endothelial cells (BAEC). Our previous studies indicate involvement of p38 mitogen activated protein kinase (MAPK) in Ang II-induced arginase upregulation and reduced NO production. In this study, we further investigated the Ang II-transcriptional regulation of arginase 1 in endothelial cells. Our results indicate the involvement of ATF-2 transcription factor of the AP1 family in arginase 1 upregulation and in limiting NO production. Using small interfering RNA (siRNA) targeting ATF-2, we showed that this transcription factor is required for Ang II-induced arginase 1 gene upregulation and increased arginase 1 expression and activity, leading to reduced NO production. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay further confirmed the involvement of ATF-2. Moreover, our data indicate that p38 MAPK phosphorylates ATF-2 in response to Ang II. Collectively, our results indicate that Ang II increases endothelial arginase activity/expression through a p38 MAPK/ATF-2 pathway leading to reduced endothelial NO production. These signaling steps might be therapeutic targets for preventing vascular endothelial dysfunction associated with elevated arginase activity/expression. PMID:25446432

  1. Vitreous Enamel Damping Material Development.

    DTIC Science & Technology

    1982-11-01

    PROCEDURES 3 2.1. EXPERIMENTAL 3 2.1.1. GLASS PREPARATION 3 2.1.2. METHOD OF COATING APPLICATION 3 2.1.3. VIBRATION DAMPING MEASUREMENTS 3 2.2. CALCULATION OF...discussion in this report. fL 2 SECTION II TECHNICAL PROCEDURES 2.1 EXPERIMENTAL 2.1.1 Glass Preparation All of the compositions, except the standard...After heat treatments of composition "B", a- cristobalite and devitrite (Na20.3CaO-6SiO 2) appear as crystalline phases; a- cristobalite being the major

  2. Slip Damping of Turbine Blades.

    DTIC Science & Technology

    1978-12-01

    between stress and energy dissipated of the form N D = J0 (73) B - j was assumed. J and N are empirically derived constants and a is the B bending...November 1977. 12. Klumpp, James H., and Benjamin J . Lazan . Frictional Damping and Resonant Vibration Characteristics of an Axial Slip Lap Joint. WADC...GAE/AA/78D-1 I 4-80OI *mmmmmmih. 00 DTIC ELECTEK ~OF 4 MAR 18 US0 B ,C) UNITED STATES AIR FORCE AIR UNIVERSITY ;* AIR FORCE INSTITUTE OF TECHNOLOGY

  3. The intrinsic damping of the fractional oscillator

    NASA Astrophysics Data System (ADS)

    Tofighi, Ali

    2003-11-01

    We obtain analytical expressions for the time rate of change of the potential energy, the kinetic energy and the total energy of a fractional oscillator in terms of the products of Mittag-Leffler functions. We propose a definition for the intrinsic damping force of this oscillator. We obtain a general expression for this damping force. An expression for this damping force in the asymptotic limit ( ωt→0) is also obtained.

  4. CHARACTERIZATION OF DAMPING IN BOLTED LAP JOINTS

    SciTech Connect

    C. MALONEY; D. PEAIRS; ET AL

    2000-08-01

    The dynamic response of a jointed beam was measured in laboratory experiments. The data were analyzed and the system was mathematically modeled to establish plausible representations of joint damping behavior. Damping is examined in an approximate, local linear framework using log decrement and half power bandwidth approaches. in addition, damping is modeled in a nonlinear framework using a hybrid surface irregularities model that employs a bristles-construct. Experimental and analytical results are presented.

  5. Compton backscattering of intracavity storage ring free-electron laser radiation

    SciTech Connect

    Dattoli, G.; Giannessi, L.; Torre, A.

    1995-12-31

    We discuss the{gamma}-ray production by Compton backscattering of intracavity storage ring Free-Electron Laser radiation. We use a semi-analytical model which provides the build up of the signal combined with the storage ring damping mechanism and derive simple relations yielding the connection between backscattered. Photons brightness and the intercavity laser equilibrium intensity.

  6. Induced ATF-2 represses CDK4 transcription through dimerization with JunD inhibiting intestinal epithelial cell growth after polyamine depletion

    PubMed Central

    Xiao, Lan; Rao, Jaladanki N.; Zou, Tongtong; Liu, Lan; Yu, Ting-Xi; Zhu, Xiao-Yu; Donahue, James M.

    2010-01-01

    Intestinal epithelium is a rapidly self-renewing tissue in the body, and its homeostasis is tightly regulated by numerous factors including polyamines. Decreased levels of cellular polyamines increase activating transcription factor (ATF)-2, but the exact role and mechanism of induced ATF-2 in the regulation of intestinal epithelial cell (IEC) growth remain elusive. Cyclin-dependent kinase (CDK) 4 is necessary for the G1-to-S phase transition during the cell cycle, and its expression is predominantly controlled at the transcription level. Here, we reported that induced ATF-2 following polyamine depletion repressed CDK4 gene transcription in IECs by increasing formation of the ATF-2/JunD heterodimers. ATF-2 formed complexes with JunD as measured by immunoprecipitation using the ATF-2 and JunD antibodies and by glutathione S-transferase (GST) pull-down assays using GST-ATF-2 fusion proteins. Studies using various mutants of GST-ATF-2 revealed that formation of the ATF-2/JunD dimers depended on the COOH-terminal basic region-leucine zipper domain of ATF-2. Polyamine depletion increased ATF-2/JunD complex and inhibited CDK4 transcription as indicated by a decrease in the levels of CDK4-promoter activity and its mRNA. ATF-2 silencing not only prevented inhibition of CDK4 transcription in polyamine-deficient cells but also abolished repression of CDK4 expression induced by ectopic JunD overexpression. ATF-2 silencing also promoted IEC growth in polyamine-depleted cells. These results indicate that induced ATF-2/JunD association following polyamine depletion represses CDK4 transcription, thus contributing to the inhibition of IEC growth. PMID:20181929

  7. Induced ATF-2 represses CDK4 transcription through dimerization with JunD inhibiting intestinal epithelial cell growth after polyamine depletion.

    PubMed

    Xiao, Lan; Rao, Jaladanki N; Zou, Tongtong; Liu, Lan; Yu, Ting-Xi; Zhu, Xiao-Yu; Donahue, James M; Wang, Jian-Ying

    2010-05-01

    Intestinal epithelium is a rapidly self-renewing tissue in the body, and its homeostasis is tightly regulated by numerous factors including polyamines. Decreased levels of cellular polyamines increase activating transcription factor (ATF)-2, but the exact role and mechanism of induced ATF-2 in the regulation of intestinal epithelial cell (IEC) growth remain elusive. Cyclin-dependent kinase (CDK) 4 is necessary for the G1-to-S phase transition during the cell cycle, and its expression is predominantly controlled at the transcription level. Here, we reported that induced ATF-2 following polyamine depletion repressed CDK4 gene transcription in IECs by increasing formation of the ATF-2/JunD heterodimers. ATF-2 formed complexes with JunD as measured by immunoprecipitation using the ATF-2 and JunD antibodies and by glutathione S-transferase (GST) pull-down assays using GST-ATF-2 fusion proteins. Studies using various mutants of GST-ATF-2 revealed that formation of the ATF-2/JunD dimers depended on the COOH-terminal basic region-leucine zipper domain of ATF-2. Polyamine depletion increased ATF-2/JunD complex and inhibited CDK4 transcription as indicated by a decrease in the levels of CDK4-promoter activity and its mRNA. ATF-2 silencing not only prevented inhibition of CDK4 transcription in polyamine-deficient cells but also abolished repression of CDK4 expression induced by ectopic JunD overexpression. ATF-2 silencing also promoted IEC growth in polyamine-depleted cells. These results indicate that induced ATF-2/JunD association following polyamine depletion represses CDK4 transcription, thus contributing to the inhibition of IEC growth.

  8. Activating transcription factor 3 (ATF3) protects against lipopolysaccharide-induced acute lung injury via inhibiting the expression of TL1A.

    PubMed

    Qian, Lanlan; Zhao, Yunfeng; Guo, Liang; Li, Shaoying; Wu, Xueling

    2017-12-01

    Excessive inflammatory responses are critical in the pathogenesis of acute lung injury (ALI). Activating transcription factor 3 (ATF3) is a stress-induced transcriptional regulator that is a negative regulator of inflammatory responses. Therefore, we investigated the role and signaling pathways of ATF3 in lipopolysaccharide (LPS)-induced ALI in mice. The mouse macrophage RAW264.7 cells were cultured on HTS 24-Transwell filter plates in presence of ATF3 siRNA before exposure to LPS. ATF3 knock-out (KO) and wild type (WT) mice were challenged by intra-peritoneal injection of LPS (15 mg/kg). Gene analysis was used to analyze differential gene expression between ATF3 KO and WT mice. LPS increased the expression of ATF3 in RAW264.7 cells and in lung tissues of mice, The concentration of TNFα and IL-6 was significantly increased in ATF3 siRNA-treated RAW264.7 cells compared to control cells after LPS stimulation. The concentration of TNFα, IL-6 and IL-1β in serum and lung tissue of ATF3 KO mice was significantly increased compared to ATF3 WT mice. In addition, the lung wet/dry weight and BALF protein were significantly increased in ATF3 KO mice after LPS injection at 6, 24, and 48 hr. The survival of ATF3 KO mice significantly decreased. Differential gene analysis showed that TL1A was highly expressed in LPS-induced lung tissues of ATF3 KO mice.Moreover, ATF3 down-regulated the expression of TL1A in RAW264.7 cells and in lung tissues. These findings suggest that ATF3 protects against LPS-induced ALI via inhibiting TL1A expression. © 2017 Wiley Periodicals, Inc.

  9. Viscous damped space structure for reduced jitter

    NASA Technical Reports Server (NTRS)

    Wilson, James F.; Davis, L. Porter

    1987-01-01

    A technique to provide modal vibration damping in high performance space structures was developed which uses less than one once of incompressible fluid. Up to 50 percent damping can be achieved which can reduce the settling times of the lowest structural mode by as much as 50 to 1. This concept allows the designers to reduce the weight of the structure while improving its dynamic performance. Damping by this technique is purely viscous and has been shown by test to be linear over 5 orders of input magnitude. Amplitudes as low as 0.2 microinch were demonstrated. Damping in the system is independent of stiffness and relatively insensitive to temperature.

  10. Damping constant estimation in magnetoresistive readers

    SciTech Connect

    Stankiewicz, Andrzej Hernandez, Stephanie

    2015-05-07

    The damping constant is a key design parameter in magnetic reader design. Its value can be derived from bulk or sheet film ferromagnetic resonance (FMR) line width. However, dynamics of nanodevices is usually defined by presence of non-uniform modes. It triggers new damping mechanisms and produces stronger damping than expected from traditional FMR. This work proposes a device-level technique for damping evaluation, based on time-domain analysis of thermally excited stochastic oscillations. The signal is collected using a high bandwidth oscilloscope, by direct probing of a biased reader. Recorded waveforms may contain different noise signals, but free layer FMR is usually a dominating one. The autocorrelation function is a reflection of the damped oscillation curve, averaging out stochastic contributions. The damped oscillator formula is fitted to autocorrelation data, producing resonance frequency and damping constant values. Restricting lag range allows for mitigation of the impact of other phenomena (e.g., reader instability) on the damping constant. For a micromagnetically modeled reader, the technique proves to be much more accurate than the stochastic FMR line width approach. Application to actual reader waveforms yields a damping constant of ∼0.03.

  11. Hysteretic damping in rotordynamics: An equivalent formulation

    NASA Astrophysics Data System (ADS)

    Genta, Giancarlo; Amati, Nicola

    2010-10-01

    The hysteretic damping model cannot be applied to time domain dynamic simulations: this is a well-known feature that has been discussed in the literature since the time when analog computers were widespread. The constant equivalent damping often introduced to overcome this problem is also discussed, and its limitations are stated, in particular those linked with its application in rotordynamics to simulate rotating damping. An alternative model based on the nonviscous damping (NVD) model, but with a limited number of additional degrees of freedom, is proposed, and the relevant equations are derived. Some examples show applications to the rotordynamics field.

  12. Material Damping Experiments at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Levine, Marie; White, Christopher

    2003-01-01

    A unique experimental facility has been designed to measure damping of materials at cryogenic temperatures. The test facility pays special attention to removing other sources of damping in the measurement by avoiding frictional interfaces, decoupling the test specimen from the support system, and by using a non-contacting measurement device; Damping data is obtained for materials (AI, GrEp, Be, Fused Quartz), strain amplitudes (less than 10-6 ppm), frequencies (20Hz-330Hz) and temperatures (20K-293K) relevant to future precision optical space missions. The test data shows a significant decrease in viscous damping at cryogenic temperatures and can be as low as 10-4%, but the amount of the damping decrease is a function of frequency and material. Contrary to the other materials whose damping monotonically decreased with temperature, damping of Fused Quartz increased substantially at cryo, after reaching a minimum at around l50 K. The damping is also shown to be insensitive to strain for low strain levels. At room temperatures, the test data correlates well to the analytical predictions of the Zener damping model. Discrepancies at cryogenic temperatures between the model predictions and the test data are observed.

  13. A Novel Damping Mechanism for Diocotron Modes

    NASA Astrophysics Data System (ADS)

    Chim, Chi Yung; O'Neil, Thomas M.

    2014-10-01

    Recent experiments with pure electron plasmas in a Malmberg-Penning trap have observed the algebraic damping of m = 1 and m = 2 diocotron modes. Transport due to small field asymmetries produces a low density halo of electrons moving radially outward from the plasma core, and the mode damping begins when the halo reaches the resonant radius, where f = mfE × B (r) . The damping rate is proportional to the flux of halo particles through the resonant layer. The damping is related to, but distinct from spatial Landau damping, in which a linear wave-particle resonance produces exponential damping. This poster explains with analytic theory and simulations the new algebraic damping due to both mobility and diffusive fluxes. The damping is due to transfer of canonical angular momentum from the mode to halo particles, as they are swept around the ``cat's eye'' orbits of resonant wave-particle interaction. Another picture is that the electrons in the resonant layer form a dipole (m = 1) or quadrupole (m = 2) density distribution, and the electric field for this distribution produces E × B drifts that symmetrizes the core and damps the mode. Supported by NSF/DOE Partnership Grants PHY-0903877 and DE-SC0002451.

  14. Superconductive material and magnetic field for damping and levitation support and damping of cryogenic instruments

    NASA Technical Reports Server (NTRS)

    Dolgin, Benjamin P. (Inventor)

    1994-01-01

    A superconductive load bearing support without a mechanical contact and vibration damping for cryogenic instruments in space is presented. The levitation support and vibration damping is accomplished by the use of superconducting magnets and the 'Meissner' effect. The assembly allows for transfer of vibration energy away from the cryogenic instrument which then can be damped by the use of either an electronic circuit or conventional vibration damping mean.

  15. Relaxation damping in oscillating contacts

    PubMed Central

    Popov, M.; Popov, V.L.; Pohrt, R.

    2015-01-01

    If a contact of two purely elastic bodies with no sliding (infinite coefficient of friction) is subjected to superimposed oscillations in the normal and tangential directions, then a specific damping appears, that is not dependent on friction or dissipation in the material. We call this effect “relaxation damping”. The rate of energy dissipation due to relaxation damping is calculated in a closed analytic form for arbitrary axially-symmetric contacts. In the case of equal frequency of normal and tangential oscillations, the dissipated energy per cycle is proportional to the square of the amplitude of tangential oscillation and to the absolute value of the amplitude of normal oscillation, and is dependent on the phase shift between both oscillations. In the case of low frequency tangential oscillations with superimposed high frequency normal oscillations, the dissipation is proportional to the ratio of the frequencies. Generalization of the results for macroscopically planar, randomly rough surfaces as well as for the case of finite friction is discussed. PMID:26549011

  16. Damped Lyman-α Systems

    NASA Astrophysics Data System (ADS)

    Petitjean, P.; Ledoux, C.

    Recently, Prochaska & Wolfe (1997) have used Keck spectra of 17 DLA absorbers to investigate the kinematics of the neutral gas using unsaturated low excitation transitions such as Si iiλ 1808. They show that the absorption profiles are inconsistent with models of galactic haloes with random motions, spherically infalling gas and slowly rotating hot disks. The CDM model (Kauffmann 1996) is rejected as it produces disks with rotation velocities too small to account for the large observed velocity broadening of the absorption lines. Models of thick disks (h ~0.3 R, where h is the vertical scale and R the radius) with large rotational velocity (v 225kms-1) can reproduce the data. By combining new data on five damped systems with information gathered in the literature, we study the kinematics of the low and high-ionization phases in a sample of 26 damped Lyman-α systems in the redshift range 1.17 - 4.38. We show that the broader the line the more asymmetric, as expected in case rotation dominates the line broadening. However this correlation does not hold for velocities larger than 150 km/s indicating that evidence for rotational motions if any is restricted to velocity broadenings Δ V < 150kms-1. The systems with Δ V > 200kms-1 are peculiar with kinematics consistent with random motions. They show sub-systems as those expected if the objects are in the process of merging.

  17. Tuned vibration absorbers with nonlinear viscous damping for damped structures under random load

    NASA Astrophysics Data System (ADS)

    Shum, K. M.

    2015-06-01

    The classical problem for the application of a tuned vibration absorber is to minimize the response of a structural system, such as displacement, velocity, acceleration or to maximize the energy dissipated by tuned vibration absorber. The development of explicit optimal absorber parameters is challenging for a damped structural system since the fixed points no longer exist in the frequency response curve. This paper aims at deriving a set of simple design formula of tuned vibration absorber with nonlinear viscous damping based on the frequency tuning for harmonic load for a damped structural system under white noise excitation. The vibration absorbers being considered include tuned mass damper (TMD) and liquid column vibration absorber (LCVA). Simple approximate expression for the standard deviation velocity response of tuned vibration absorber for damped primary structure is also derived in this study to facilitate the estimation of the damping coefficient of TMD with nonlinear viscous damping and the head loss coefficient of LCVA. The derived results indicate that the higher the structural inherent damping the smaller the supplementary damping provided by a tuned vibration absorber. Furthermore, the optimal damping of tuned vibration absorber is shown to be independent of structural damping when it is tuned using the frequency tuning for harmonic load. Finally, the derived closed-form expressions are demonstrated to be capable of predicting the optimal parameters of tuned vibration absorbers with sufficient accuracy for preliminary design of tuned vibration absorbers with nonlinear viscous damping for a damped primary structure.

  18. Validation of High-Resolution CFD Method for Slosh Damping Extraction of Baffled Cryogenic Propellant Tanks

    NASA Technical Reports Server (NTRS)

    Yang, H. Q.; West, Jeff

    2016-01-01

    Propellant slosh is a potential source of disturbance critical to the stability of space vehicles. The slosh dynamics are typically represented by a mechanical model of a spring-mass-damper. This mechanical model is then included in the equation of motion of the entire vehicle for Guidance, Navigation and Control analysis. A Volume-Of-Fluid (VOF) based Computational Fluid Dynamics (CFD) program developed at MSFC was applied to extract slosh damping in the baffled tank from the first principle. First the experimental data using water with sub-scale smooth wall tank were used as the baseline validation. It is demonstrated that CFD can indeed accurately predict low damping values from the smooth wall at different fill levels. The damping due to a ring baffles at different depths from the free surface was then simulated, and fairly good agreement with experimental measurement was observed. Comparison with an empirical correlation of Miles equation is also made.

  19. Controllable damping of high-Q violin modes in fused silica suspension fibers

    NASA Astrophysics Data System (ADS)

    Dmitriev, A. V.; Mescheriakov, S. D.; Tokmakov, K. V.; Mitrofanov, V. P.

    2010-01-01

    Fused silica fiber suspension of the test masses will be used in the interferometric gravitational wave detectors of the next generation. This allows a significant reduction of losses in the suspension and thermal noise associated with the suspension. Unfortunately, unwanted violin modes may be accidentally excited in the suspension fibers. The Q-factor of the violin modes also exceeds 108. They have a ring-down time that is too long and may complicate the stable control of the interferometer. Results of the investigation of a violin mode active damping system are described. An original sensor and actuator were especially developed to realize the effective coupling of a thin, optically transparent, non-conducting fused silica fiber with an electric circuit. The damping system allowed the changing of the violin mode's damping rate over a wide range.

  20. Quasienergy formulation of damped response theory.

    PubMed

    Kristensen, Kasper; Kauczor, Joanna; Kjaergaard, Thomas; Jørgensen, Poul

    2009-07-28

    We present a quasienergy-based formulation of damped response theory where a common effective lifetime parameter has been introduced for all excited states in terms of complex excitation energies. The introduction of finite excited state lifetimes leads to a set of (complex) damped response equations, which have the same form to all orders in the perturbation. An algorithm is presented for solving the damped response equations in Hartree-Fock theory and Kohn-Sham density functional theory. The use of the quasienergy formulation allows us to obtain directly the computationally simplest expressions for damped response functions by applying a set of response parameter elimination rules, which minimize the total number of damped response equations to be solved. In standard response theory broadened absorption spectra are obtained by ad hoc superimposing lineshape functions onto the absorption stick spectra, whereas an empirical lineshape function common to all excitations is an integrated part of damped response theory. By superimposing the lineshape functions inherent in damped response theory onto the stick spectra of standard response theory, we show that the absorption spectra obtained in standard and damped response theory calculations are identical. We demonstrate that damped response theory may be applied to obtain absorption spectra in all frequency ranges, also those that are not readily addressed using standard response theory. This makes damped response theory an effective tool, e.g., for determining absorption spectra for large molecules, where the density of the excited states may be very high, and where standard response theory therefore is not applicable in practice. A thorough comparison is given between our formulation of damped response theory and the formulation by Norman et al. [J. Chem. Phys. 123, 194103 (2005)].

  1. The Secular Evolution of a Close Ring-Satellite System

    NASA Astrophysics Data System (ADS)

    Hahn, Joseph M.

    2007-10-01

    Current literature on ring-satellite interactions tells us that the long-term orbital stability of a satellite that orbits near a planetary ring is uncertain. This is because the satellite's perturbations at its Lindblad and corotation resonances in the ring tend to alter the satellite's eccentricity e, but it is unclear whether e-damping or e-excitation is the result, since that depends on whether particle motions at the corotation resonances are unsaturated (Goldreich & Tremaine 1982). Further, the stability of the satellite's inclination I seems grim, since the satellite's inclination is excited by its many vertical resonances in the ring (Borderies et al 1984). Consequently, it is unclear whether the small gap-embedded satellites Pan (which inhabits the Encke gap in Saturn's A ring) and Daphnis (which inhabits the Keeler gap) should in fact reside in nearly circular orbits that are coplanar with the ring. To address this uncertainty, the following considers the satellite's secular gravitational perturbations of the ring, which can also alter the satellite's e and I. The Lagrange planetary equations are used to show that a small gap-embedded satellite can launch spiral density and spiral bending waves that propagate radially outwards from the gap's outer edge. These one-armed waves propagate via the secular part of the ring's self-attraction, and they tend to have low amplitudes and long wavelengths, 100's of km in Saturn's A ring. The excitation of these waves also damps the satellite's e and I at rates that depend on the satellite's mass, ring surface density, the gap width, and the planet's oblateness (Hahn 2007). These analytic predictions are also confirmed using the `rings-model' of Hahn (2003) to simulate a ring-satellite system. Whether this secular interaction can stabilize a satellite's e and I will be determined, and whether these low-amplitude waves have any observational consequences will also be discussed.

  2. The Secular Evolution of a Close Ring-Satellite System: The Excitation of Spiral Bending Waves at a Nearby Gap Edge

    NASA Astrophysics Data System (ADS)

    Hahn, Joseph M.

    2007-08-01

    The secular perturbations exerted by an inclined satellite orbiting in a gap in a broad planetary ring tend to excite the inclinations of the nearby ring particles, and the ring's self-gravity can allow that disturbance to propagate away in the form of a spiral bending wave. The amplitude of this spiral bending wave is determined, as well as the wavelength, which shrinks as the waves propagate outward due to the effects of the central planet's oblateness. The excitation of these bending waves also damps the satellite's inclination I. This secular I damping is also compared to the inclination excitation that is due to the satellite's many other vertical resonances in the ring, and the condition for inclination damping is determined. The secular I damping is likely responsible for confining the orbits of Saturn's two known gap-embedded moons, Pan and Daphnis, to the ring plane.

  3. Prediction of Liquid Slosh Damping Using a High Resolution CFD Tool

    NASA Technical Reports Server (NTRS)

    Yang, H. Q.; Purandare, Ravi; Peugeot, John; West, Jeff

    2012-01-01

    Propellant slosh is a potential source of disturbance critical to the stability of space vehicles. The slosh dynamics are typically represented by a mechanical model of a spring mass damper. This mechanical model is then included in the equation of motion of the entire vehicle for Guidance, Navigation and Control analysis. Our previous effort has demonstrated the soundness of a CFD approach in modeling the detailed fluid dynamics of tank slosh and the excellent accuracy in extracting mechanical properties (slosh natural frequency, slosh mass, and slosh mass center coordinates). For a practical partially-filled smooth wall propellant tank with a diameter of 1 meter, the damping ratio is as low as 0.0005 (or 0.05%). To accurately predict this very low damping value is a challenge for any CFD tool, as one must resolve a thin boundary layer near the wall and must minimize numerical damping. This work extends our previous effort to extract this challenging parameter from first principles: slosh damping for smooth wall and for ring baffle. First the experimental data correlated into the industry standard for smooth wall were used as the baseline validation. It is demonstrated that with proper grid resolution, CFD can indeed accurately predict low damping values from smooth walls for different tank sizes. The damping due to ring baffles at different depths from the free surface and for different sizes of tank was then simulated, and fairly good agreement with experimental correlation was observed. The study demonstrates that CFD technology can be applied to the design of future propellant tanks with complex configurations and with smooth walls or multiple baffles, where previous experimental data is not available.

  4. Assessing the contribution of thrombospondin-4 induction and ATF6α activation to endoplasmic reticulum expansion and phenotypic modulation in bladder outlet obstruction

    PubMed Central

    Krawczyk, Katarzyna K.; Ekman, Mari; Rippe, Catarina; Grossi, Mario; Nilsson, Bengt-Olof; Albinsson, Sebastian; Uvelius, Bengt; Swärd, Karl

    2016-01-01

    Phenotypic modulation of smooth muscle cells is a hallmark of disease. The associated expansion of endoplasmic reticulum (ER) volume remains unexplained. Thrombospondin-4 was recently found to promote ATF6α activation leading to ER expansion. Using bladder outlet obstruction as a paradigm for phenotypic modulation, we tested if thrombospondin-4 is induced in association with ATF6α activation and ER expansion. Thrombospondin-4 was induced and ATF6α was activated after outlet obstruction in rodents. Increased abundance of spliced of Xbp1, another ER-stress sensor, and induction of Atf4 and Creb3l2 was also seen. Downstream of ATF6α, Calr, Manf, Sdf2l1 and Pdi increased as did ER size, whereas contractile markers were reduced. Overexpression of ATF6α, but not of thrombospondin-4, increased Calr, Manf, Sdf2l1 and Pdi and caused ER expansion, but the contractile markers were inert. Knockout of thrombospondin-4 neither affected bladder growth nor expression of ATF6α target genes, and repression of contractile markers was the same, even if ATF6α activation was curtailed. Increases of Xbp1s, Atf4 and Creb3l2 were similar. Our findings demonstrate reciprocal regulation of the unfolded protein response, including ATF6α activation and ER expansion, and reduced contractile differentiation in bladder outlet obstruction occurring independently of thrombospondin-4, which however is a sensitive indicator of obstruction. PMID:27581066

  5. DAMPs from Cell Death to New Life

    PubMed Central

    Vénéreau, Emilie; Ceriotti, Chiara; Bianchi, Marco Emilio

    2015-01-01

    Our body handles tissue damage by activating the immune system in response to intracellular molecules released by injured tissues [damage-associated molecular patterns (DAMPs)], in a similar way as it detects molecular motifs conserved in pathogens (pathogen-associated molecular patterns). DAMPs are molecules that have a physiological role inside the cell, but acquire additional functions when they are exposed to the extracellular environment: they alert the body about danger, stimulate an inflammatory response, and finally promote the regeneration process. Beside their passive release by dead cells, some DAMPs can be secreted or exposed by living cells undergoing a life-threatening stress. DAMPs have been linked to inflammation and related disorders: hence, inhibition of DAMP-mediated inflammatory responses is a promising strategy to improve the clinical management of infection- and injury-elicited inflammatory diseases. However, it is important to consider that DAMPs are not only danger signals but also central players in tissue repair. Indeed, some DAMPs have been studied for their role in tissue healing after sterile or infection-associated inflammation. This review is focused on two exemplary DAMPs, HMGB1 and adenosine triphosphate, and their contribution to both inflammation and tissue repair. PMID:26347745

  6. Understanding the Damped SHM without ODEs

    ERIC Educational Resources Information Center

    Ng, Chiu-king

    2016-01-01

    Instead of solving ordinary differential equations (ODEs), the damped simple harmonic motion (SHM) is surveyed qualitatively from basic mechanics and quantitatively by the instrumentality of a graph of velocity against displacement. In this way, the condition b ? [square root]4mk for the occurrence of the non-oscillating critical damping and…

  7. Bending rate damping in elastic systems

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Wang, Y.; Fabiano, R. H.

    1989-01-01

    Preliminary results of an investigation of the bending rate damping model for elastic structures are presented. A model for which the internal damping term is physically plausible and which can accomodate cantilevered boundary conditions is discussed. The model formulation and mathematical foundations are given, and numerical results are discussed.

  8. Damping-off in forest nurseries

    Treesearch

    Carl Hartley

    1921-01-01

    Damping-off is the commonest English name for a symptomatic group of diseases affecting great numbers of plant species of widely separated phylogenetic groups. It is commonly used for any disease which results in the rapid decay of young succulent seedlings or soft cuttings. Young shoots from underground rootstocks may also be damped-off before they break through the...

  9. Understanding the Damped SHM without ODEs

    ERIC Educational Resources Information Center

    Ng, Chiu-king

    2016-01-01

    Instead of solving ordinary differential equations (ODEs), the damped simple harmonic motion (SHM) is surveyed qualitatively from basic mechanics and quantitatively by the instrumentality of a graph of velocity against displacement. In this way, the condition b ? [square root]4mk for the occurrence of the non-oscillating critical damping and…

  10. Transcriptional Repression of ATF4 Gene by CCAAT/Enhancer-binding Protein β (C/EBPβ) Differentially Regulates Integrated Stress Response*

    PubMed Central

    Dey, Souvik; Savant, Sudha; Teske, Brian F.; Hatzoglou, Maria; Calkhoven, Cornelis F.; Wek, Ronald C.

    2012-01-01

    Different environmental stresses induce the phosphorylation of eIF2 (eIF2∼P), repressing global protein synthesis coincident with preferential translation of ATF4. ATF4 is a transcriptional activator of genes involved in metabolism and nutrient uptake, antioxidation, and regulation of apoptosis. Because ATF4 is a common downstream target that integrates signaling from different eIF2 kinases and their respective stress signals, the eIF2∼P/ATF4 pathway is collectively referred to as the integrated stress response. Although eIF2∼P elicits translational control in response to many different stresses, there are selected stresses, such as exposure to UV irradiation, that do not increase ATF4 expression despite robust eIF2∼P. The rationale for this discordant induction of ATF4 expression and eIF2∼P in response to UV irradiation is that transcription of ATF4 is repressed, and therefore ATF4 mRNA is not available for preferential translation. In this study, we show that C/EBPβ is a transcriptional repressor of ATF4 during UV stress. C/EBPβ binds to critical elements in the ATF4 promoter, resulting in its transcriptional repression. Expression of C/EBPβ increases in response to UV stress, and the liver-enriched inhibitory protein (LIP) isoform of C/EBPβ, but not the liver-enriched activating protein (LAP) version, represses ATF4 transcription. Loss of the liver-enriched inhibitory protein isoform results in increased ATF4 mRNA levels in response to UV irradiation and subsequent recovery of ATF4 translation, leading to enhanced expression of its target genes. Together these results illustrate how eIF2∼P and translational control combined with transcription factors regulated by alternative signaling pathways can direct programs of gene expression that are specifically tailored to each environmental stress. PMID:22556424

  11. Interplay of CREB and ATF2 in Ionizing Radiation-Induced Neuroendocrine Differentiation of Prostate Cancer Cells

    DTIC Science & Technology

    2012-06-01

    that contributes to IR- induced phos- phorylation of CREB. It will be interesting to determine whether this effect is independent of or dependent on...S. (2010) Growth factor stimulation induces cell survival by c- Jun. ATF2- dependent activation of Bcl-XL. J. Biol. Chem. 285, 23096–23104 7. Shimizu...08-1-0394 TITLE: Interplay of CREB and ATF2 in Ionizing Radiation- Induced Neuroendocrine Differentiation of Prostate Cancer Cells

  12. Metformin Suppresses Lipopolysaccharide (LPS)-induced Inflammatory Response in Murine Macrophages via Activating Transcription Factor-3 (ATF-3) Induction*

    PubMed Central

    Kim, Juyoung; Kwak, Hyun Jeong; Cha, Ji-Young; Jeong, Yun-Seung; Rhee, Sang Dahl; Kim, Kwang Rok; Cheon, Hyae Gyeong

    2014-01-01

    Metformin, a well known antidiabetic agent that improves peripheral insulin sensitivity, also elicits anti-inflammatory actions, but its mechanism is unclear. Here, we investigated the mechanism responsible for the anti-inflammatory effect of metformin action in lipopolysaccharide (LPS)-stimulated murine macrophages. Metformin inhibited LPS-induced production of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in a concentration-dependent manner and in parallel induction of activating transcription factor-3 (ATF-3), a transcription factor and member of the cAMP-responsive element-binding protein family. ATF-3 knockdown abolished the inhibitory effects of metformin on LPS-induced proinflammatory cytokine production accompanied with reversal of metformin-induced suppression of mitogen-activated protein kinase (MAPK) phosphorylation. Conversely, AMP-activated protein kinase (AMPK) phosphorylation and NF-κB suppression by metformin were unaffected by ATF-3 knockdown. ChIP-PCR analysis revealed that LPS-induced NF-κB enrichments on the promoters of IL-6 and TNF-α were replaced by ATF-3 upon metformin treatment. AMPK knockdown blunted all the effects of metformin (ATF-3 induction, proinflammatory cytokine inhibition, and MAPK inactivation), suggesting that AMPK activation by metformin is required for and precedes ATF-3 induction. Oral administration of metformin to either mice with LPS-induced endotoxemia or ob/ob mice lowered the plasma and tissue levels of TNF-α and IL-6 and increased ATF-3 expression in spleen and lungs. These results suggest that metformin exhibits anti-inflammatory action in macrophages at least in part via pathways involving AMPK activation and ATF-3 induction. PMID:24973221

  13. Metformin suppresses lipopolysaccharide (LPS)-induced inflammatory response in murine macrophages via activating transcription factor-3 (ATF-3) induction.

    PubMed

    Kim, Juyoung; Kwak, Hyun Jeong; Cha, Ji-Young; Jeong, Yun-Seung; Rhee, Sang Dahl; Kim, Kwang Rok; Cheon, Hyae Gyeong

    2014-08-15

    Metformin, a well known antidiabetic agent that improves peripheral insulin sensitivity, also elicits anti-inflammatory actions, but its mechanism is unclear. Here, we investigated the mechanism responsible for the anti-inflammatory effect of metformin action in lipopolysaccharide (LPS)-stimulated murine macrophages. Metformin inhibited LPS-induced production of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in a concentration-dependent manner and in parallel induction of activating transcription factor-3 (ATF-3), a transcription factor and member of the cAMP-responsive element-binding protein family. ATF-3 knockdown abolished the inhibitory effects of metformin on LPS-induced proinflammatory cytokine production accompanied with reversal of metformin-induced suppression of mitogen-activated protein kinase (MAPK) phosphorylation. Conversely, AMP-activated protein kinase (AMPK) phosphorylation and NF-κB suppression by metformin were unaffected by ATF-3 knockdown. ChIP-PCR analysis revealed that LPS-induced NF-κB enrichments on the promoters of IL-6 and TNF-α were replaced by ATF-3 upon metformin treatment. AMPK knockdown blunted all the effects of metformin (ATF-3 induction, proinflammatory cytokine inhibition, and MAPK inactivation), suggesting that AMPK activation by metformin is required for and precedes ATF-3 induction. Oral administration of metformin to either mice with LPS-induced endotoxemia or ob/ob mice lowered the plasma and tissue levels of TNF-α and IL-6 and increased ATF-3 expression in spleen and lungs. These results suggest that metformin exhibits anti-inflammatory action in macrophages at least in part via pathways involving AMPK activation and ATF-3 induction. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. Mutation of ATF4 mediates resistance of neuronal cell lines against oxidative stress by inducing xCT expression

    PubMed Central

    Lewerenz, J; Sato, H; Albrecht, P; Henke, N; Noack, R; Methner, A; Maher, P

    2012-01-01

    Selecting neuronal cell lines for resistance against oxidative stress might recapitulate some adaptive processes in neurodegenerative diseases where oxidative stress is involved like Parkinson's disease. We recently reported that in hippocampal HT22 cells selected for resistance against oxidative glutamate toxicity, the cystine/glutamate antiporter system xc−, which imports cystine for synthesis of the antioxidant glutathione, and its specific subunit, xCT, are upregulated. (Lewerenz et al., J Neurochem 98(3):916–25). Here, we show that in these glutamate-resistant HT22 cells upregulation of xCT mediates glutamate resistance, and xCT expression is induced by upregulation of the transcription factor ATF4. The mechanism of ATF4 upregulation consists of a 13 bp deletion in the upstream open reading frame (uORF2) overlapping the ATF4 open reading frame. The resulting uORF2–ATF4 fusion protein is efficiently translated even at a low phosphorylation levels of the translation initiation factor eIF2α, a condition under which ATF4 translation is normally suppressed. A similar ATF4 mutation associated with prominent upregulation of xCT expression was identified in PC12 cells selected for resistance against amyloid β-peptide. Our data indicate that ATF4 has a central role in regulating xCT expression and resistance against oxidative stress. ATF4 mutations might have broader significance as upregulation of xCT is found in tumor cells and associated with anticancer drug resistance. PMID:22095285

  15. Damping characteristics of damaged fiber composite components

    NASA Technical Reports Server (NTRS)

    Eberle, K.

    1986-01-01

    Defects in fiber composite components produce changes with respect to the vibrational characteristics of the material. These changes can be recognized in the form of a frequency shift or an alteration of the damping process. The present investigation is concerned with questions regarding the possibility of a utilization of the changes in suitable defect-detecting inspection procedures. A description is given of a method for measuring the damping characteristics of a specimen. This method provides a spectrum of the damping coefficients of the sample as a basis for a comprehensive evaluation of the damping behavior. The correlation between defects and change in the damping characteristics is demonstrated with the aid of results obtained in measurements involving specimens of carbon-fiber composites and a component consisting of glass-fiber-reinforced plastics.

  16. Landau damping in a turbulent setting

    SciTech Connect

    Plunk, G. G.

    2013-03-15

    To address the problem of Landau damping in kinetic turbulence, we consider the forcing of the linearized Vlasov equation by a stationary random source. It is found that the time-asymptotic density response is dominated by resonant particle interactions that are synchronized with the source. The energy consumption of this response is calculated, implying an effective damping rate, which is the main result of this paper. Evaluating several cases, it is found that the effective damping rate can differ from the Landau damping rate in magnitude and also, remarkably, in sign. A limit is demonstrated in which the density and current become phase-locked, which causes the effective damping to be negligible; this result offers a fresh perspective from which to reconsider recent observations of kinetic turbulence satisfying critical balance.

  17. A finite element model with nonviscous damping

    NASA Technical Reports Server (NTRS)

    Roussos, L. A.; Hyer, M. W.; Thornton, E. A.

    1981-01-01

    A constitutive law by which structural damping is modeled as a relationship between stress, strain, and strain rate in a material is used in conjunction with the finite element method to develop general integral expressions for viscous and nonviscous damping matrices. To solve the set of nonlinear equations resulting from the presence of nonviscous damping, a solution technique is developed by modifying the Newmark method to accommodate an iterative solution and treat the nonviscous damping as a pseudo-force. The technique is then checked for accuracy and convergence in single- and multi-degree-of-freedom problems, and is found to be accurate and efficient for initial-condition problems with small nonviscous damping.

  18. Magnetic damping of rotation. [in satellites

    NASA Technical Reports Server (NTRS)

    Opik, E. J.

    1977-01-01

    Based on Wilson's (1977) article on the magnetic effects on space vehicles and other celestial bodies, the magnetic damping of rotation is considered. The inadequacy of the interstellar magnetic field in overcoming solar wind shielding and thus influencing the rotation of bodies is described. The ionospheric shielding of the interstellar field is discussed along with the permeability and magnetic damping by the solar or stellar wind. Star formation and angular momentum is discussed and attention is given to the magnetic damping of unshielded small bodies. Calculations of the rate for damping through random particle impact are made. Theories concerning the rotation of asteroids and the origin of meteorites are reviewed. The shielding process of ionospheric plasmas is outlined and the damping effect of the geomagnetic field on the rotation of artificial satellites is evaluated.

  19. Large space structure damping design

    NASA Technical Reports Server (NTRS)

    Pilkey, W. D.; Haviland, J. K.

    1983-01-01

    Several FORTRAN subroutines and programs were developed which compute complex eigenvalues of a damped system using different approaches, and which rescale mode shapes to unit generalized mass and make rigid bodies orthogonal to each other. An analytical proof of a Minimum Constrained Frequency Criterion (MCFC) for a single damper is presented. A method to minimize the effect of control spill-over for large space structures is proposed. The characteristic equation of an undamped system with a generalized control law is derived using reanalysis theory. This equation can be implemented in computer programs for efficient eigenvalue analysis or control quasi synthesis. Methods to control vibrations in large space structure are reviewed and analyzed. The resulting prototype, using electromagnetic actuator, is described.

  20. VIBRATION DAMPING AND SHOCK MOUNT

    DOEpatents

    Stevens, D.J.; Forman, G.W.

    1963-12-10

    A shock absorbing mount in which vibrations are damped by an interference fit between relatively movable parts of the mount is described. A pair of generally cup-shaped parts or members have skirt portions disposed in an oppositely facing nesting relationship with the skirt of one member frictionally engaging the skirt of the other. The outermost skirt may be slotted to provide spring-like segments which embrace the inner skirt for effecting the interference fit. Belleville washers between the members provide yieldable support for a load carried by the mount. When a resonant frequency of vibration forces acting upon the moumt attains a certain level the kinetic energy of these forces is absorbed by sliding friction between the parts. (AEC)

  1. Langmuir wave damping decreases slowly

    NASA Astrophysics Data System (ADS)

    Rose, Harvey

    2006-10-01

    The onset of stimulated Raman scatter in a single laser speckle occurs (D. S. Montgomery et al., Phys. Plasmas, 9, 2311 (2002)) at lower laser intensity, I, than predicted by linear theory based on classical Landau damping, νL, of the SRS daughter Langmuir wave. Does this imply that SRS onset in a speckled laser beam, propagating through long scale length plasma, is also at odds with linear theory? It has been shown (Harvey A. Rose and D. F. DuBois, Phys. Rev. Lett. 72, 2883 (1994)) that linear convective gain in speckles with large fluctuations of I about the average, , leads to onset at a value of , Ic, small compared to that for onset in a uniform beam. While nonlinear electron trapping effects may occur in very intense speckles, whether or not these effects are sufficient to lower the onset value of below Ic depends on how strongly electrons must be trapped before there is significant reduction in νL. As the amplitude of an SRS daughter Langmuir wave increases, its νL decreases by the factor ν/φb, due to the competition between electron trapping, with electron bounce frequency, φb, and escape of these trapped electrons by advection out of a speckle's side, at rate ν. This result (Harvey A. Rose and David A. Russell, Phys. Plasmas, 8, 4784 (2001)) is valid for ν/φb 1. In this talk I present a nonlinear, transit time damping, calculation of νL and find that reduction by a factor of two does not occur until φb/ν 5. This slow turn on of trapping effects suggests that the linear calculation of Ic is NIF relevant.

  2. Kinetics of ring formation

    NASA Astrophysics Data System (ADS)

    Ben-Naim, E.; Krapivsky, P. L.

    2011-06-01

    We study reversible polymerization of rings. In this stochastic process, two monomers bond and, as a consequence, two disjoint rings may merge into a compound ring or a single ring may split into two fragment rings. This aggregation-fragmentation process exhibits a percolation transition with a finite-ring phase in which all rings have microscopic length and a giant-ring phase where macroscopic rings account for a finite fraction of the entire mass. Interestingly, while the total mass of the giant rings is a deterministic quantity, their total number and their sizes are stochastic quantities. The size distribution of the macroscopic rings is universal, although the span of this distribution increases with time. Moreover, the average number of giant rings scales logarithmically with system size. We introduce a card-shuffling algorithm for efficient simulation of the ring formation process and we present numerical verification of the theoretical predictions.

  3. ATF3 is a novel nuclear marker for migrating ependymal stem cells in the rat spinal cord.

    PubMed

    Mladinic, Miranda; Bianchetti, Elena; Dekanic, Ana; Mazzone, Graciela L; Nistri, Andrea

    2014-05-01

    The present study identified ATF3 as a novel dynamic marker for ependymal stem/progenitor cells (nestin, vimentin and SOX2 positive) around the central canal of the neonatal or adult rat spinal cord. While quiescent ependymal cells showed cytoplasmic ATF3 expression, during 6-24h in vitro these cells mobilized and acquired intense nuclear ATF3 staining. Their migratory pattern followed a centrifugal pathway toward the dorsal and ventral funiculi, reminiscent of the rostral migratory stream of the brain subventricular stem cells. Thus, the chain cell formation was, by analogy, termed funicular migratory stream (FMS). The FMS process preceded the strong proliferation of ependymal cells occurring only after 24h in vitro. Pharmacological inhibition of MAPK-p38 and JNK/c-Jun (upstream effectors of ATF3 activation) prevented the FMS mobilization of ATF3 nuclear-positive cells. Excitotoxicity or ischemia-like conditions, reported to evoke neuronal and glial injury, did not further enhance migration of ependymal cells at 24h, suggesting that, at this early stage of damage, the FMS phenomenon had peaked and that more extensive repair processes are delayed beyond this time point. ATF3 is, therefore, useful to identify activation and migration of endogenous stem cells of the rat spinal cord in vitro.

  4. Ceapins are a new class of unfolded protein response inhibitors, selectively targeting the ATF6α branch

    PubMed Central

    Gallagher, Ciara M; Garri, Carolina; Cain, Erica L; Ang, Kenny Kean-Hooi; Wilson, Christopher G; Chen, Steven; Hearn, Brian R; Jaishankar, Priyadarshini; Aranda-Diaz, Andres; Arkin, Michelle R; Renslo, Adam R; Walter, Peter

    2016-01-01

    The membrane-bound transcription factor ATF6α plays a cytoprotective role in the unfolded protein response (UPR), required for cells to survive ER stress. Activation of ATF6α promotes cell survival in cancer models. We used cell-based screens to discover and develop Ceapins, a class of pyrazole amides, that block ATF6α signaling in response to ER stress. Ceapins sensitize cells to ER stress without impacting viability of unstressed cells. Ceapins are highly specific inhibitors of ATF6α signaling, not affecting signaling through the other branches of the UPR, or proteolytic processing of its close homolog ATF6β or SREBP (a cholesterol-regulated transcription factor), both activated by the same proteases. Ceapins are first-in-class inhibitors that can be used to explore both the mechanism of activation of ATF6α and its role in pathological settings. The discovery of Ceapins now enables pharmacological modulation all three UPR branches either singly or in combination. DOI: http://dx.doi.org/10.7554/eLife.11878.001 PMID:27435960

  5. Ceapins are a new class of unfolded protein response inhibitors, selectively targeting the ATF6α branch.

    PubMed

    Gallagher, Ciara M; Garri, Carolina; Cain, Erica L; Ang, Kenny Kean-Hooi; Wilson, Christopher G; Chen, Steven; Hearn, Brian R; Jaishankar, Priyadarshini; Aranda-Diaz, Andres; Arkin, Michelle R; Renslo, Adam R; Walter, Peter

    2016-07-20

    The membrane-bound transcription factor ATF6α plays a cytoprotective role in the unfolded protein response (UPR), required for cells to survive ER stress. Activation of ATF6α promotes cell survival in cancer models. We used cell-based screens to discover and develop Ceapins, a class of pyrazole amides, that block ATF6α signaling in response to ER stress. Ceapins sensitize cells to ER stress without impacting viability of unstressed cells. Ceapins are highly specific inhibitors of ATF6α signaling, not affecting signaling through the other branches of the UPR, or proteolytic processing of its close homolog ATF6β or SREBP (a cholesterol-regulated transcription factor), both activated by the same proteases. Ceapins are first-in-class inhibitors that can be used to explore both the mechanism of activation of ATF6α and its role in pathological settings. The discovery of Ceapins now enables pharmacological modulation all three UPR branches either singly or in combination.

  6. c-Jun, Fra-2, and ATF-2 immunoreactivity in the jejunal tissues of the healthy rat.

    PubMed

    Keklikoglu, Nurullah

    2008-10-01

    The aim of this study was to compare the localization of some activator protein-1 (AP-1) proteins in healthy rat jejunum. For this purpose, the AP-1 members c-Jun, Fra-2, and ATF-2 immunoreactivity (c-Jun-IR, Fra-2-IR, ATF-2-IR) in villus epithelial cells (ECs), intravillous lamina propria cells (LPCs), crypt cells (CCs), and smooth muscle cells (SMCs) were analyzed by immunohistochemical methods. Among all the cell groups, the lowest positivity ratio was found in c-Jun-IR and the highest positivity ratio was found in ATF-2-IR. For each group of ECs, LPCs, CCs, and SMCs, c-Jun-IR, Fra-2-IR, and ATF-2-IR were compared and statistically significant differences found. There were no significant differences among the cell groups with respect to c-Jun-IR and Fra-2-IR, but there was a statistically significant difference in ATF-2-IR. These findings suggest that each member of AP-1 is expressed differently and that ATF-2 is more active than c-Jun and Fra-2 in physiological conditions in healthy rat jejunum.

  7. Transgenic mouse model for imaging of ATF4 translational activation-related cellular stress responses in vivo

    PubMed Central

    Iwawaki, Takao; Akai, Ryoko; Toyoshima, Takae; Takeda, Naoki; Ishikawa, Tomo-o; Yamamura, Ken-ichi

    2017-01-01

    Activating transcription factor 4 (ATF4) is a translationally activated protein that plays a role in cellular adaptation to several stresses. Because these stresses are associated with various diseases, the translational control of ATF4 needs to be evaluated from the physiological and pathological points of view. We have developed a transgenic mouse model to monitor the translational activation of ATF4 in response to cellular stress. By using this mouse model, we were able to detect nutrient starvation response, antivirus response, endoplasmic reticulum (ER) stress response, and oxidative stress in vitro and ex vivo, as well as in vivo. The reporter system introduced into our mouse model was also shown to work in a stress intensity-dependent manner and a stress duration-dependent manner. The mouse model is therefore a useful tool for imaging ATF4 translational activation at various levels, from cell cultures to whole bodies, and it has a range of useful applications in investigations on the physiological and pathological roles of ATF4-related stress and in the development of clinical drugs for treating ATF4-associated diseases. PMID:28387317

  8. ATF3 reduces migration capacity by regulation of matrix metalloproteinases via NFκB and STAT3 inhibition in glioblastoma

    PubMed Central

    Guenzle, Jessica; Wolf, Louisa J; Garrelfs, Nicklas W C; Goeldner, Jonathan M; Osterberg, Nadja; Schindler, Cora R; Saavedra, Joseph E; Weyerbrock, Astrid

    2017-01-01

    Glioblastoma is associated with poor survival and a high recurrence rate in patients due to inevitable uncontrolled infiltrative tumor growth. The elucidation of the molecular mechanisms may offer opportunities to prevent relapses. In this study we investigated the role of the activating transcription factor 3 (ATF3) in migration of GBM cells in vitro. RNA microarray revealed that gene expression of ATF3 is induced by a variety of chemotherapeutics and experimental agents such as the nitric oxide donor JS-K (O2-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate). We found NFκB and STAT3 to be downstream targets inhibited by overexpression of ATF3. We demonstrate that ATF3 is directly involved in the regulation of matrix metalloproteinase expression and activation. Overexpression of ATF3 therefore leads to a significantly reduced migration capacity and induction of tissue inhibitors of matrix metalloproteinases. Our study for the first time identifies ATF3 as a potential novel therapeutic target in glioblastoma. PMID:28250971

  9. Regression/Eradication of gliomas in mice by a systemically-deliverable ATF5 dominant-negative peptide

    PubMed Central

    Cates, Charles C.; Arias, Angelo D.; Wong, Lynn S. Nakayama; Lamé, Michael W.; Sidorov, Maxim; Cayanan, Geraldine; Rowland, Douglas J.; Fung, Jennifer; Karpel-Massler, Georg; Siegelin, Markus D.; Greene, Lloyd A.; Angelastro, James M.

    2016-01-01

    Malignant gliomas have poor prognosis and urgently require new therapies. Activating Transcription Factor 5 (ATF5) is highly expressed in gliomas, and interference with its expression/function precipitates targeted glioma cell apoptosis in vitro and in vivo. We designed a novel deliverable truncated-dominant-negative (d/n) form of ATF5 fused to a cell-penetrating domain (Pen-d/n-ATF5-RP) that can be intraperitoneally/subcutaneously administered to mice harboring malignant gliomas generated; (1) by PDGF-B/sh-p53 retroviral transformation of endogenous neural progenitor cells; and (2) by human U87-MG xenografts. In vitro Pen-d/n-ATF5-RP entered into glioma cells and triggered massive apoptosis. In vivo, subcutaneously-administered Pen-d/n-ATF5-RP passed the blood brain barrier, entered normal brain and tumor cells, and then caused rapid selective tumor cell death. MRI verified elimination of retrovirus-induced gliomas within 8-21 days. Histopathology revealed growth-suppression of intracerebral human U87-MG cells xenografts. For endogenous PDGF-B gliomas, there was no recurrence or mortality at 6-12 months versus 66% mortality in controls at 6 months. Necropsy and liver-kidney blood enzyme analysis revealed no adverse effects on brain or other tissues. Our findings thus identify Pen-d/n-ATF5-RP as a potential therapy for malignant gliomas. PMID:26863637

  10. ATF7IP as a novel PDGFRB fusion partner in acute lymphoblastic leukaemia in children.

    PubMed

    Kobayashi, Kenichiro; Mitsui, Kazumasa; Ichikawa, Hitoshi; Nakabayashi, Kazuhiko; Matsuoka, Masaki; Kojima, Yasuko; Takahashi, Hiroyuki; Iijima, Kazutoshi; Ootsubo, Kaori; Oboki, Keisuke; Okita, Hajime; Yasuda, Kazuki; Sakamoto, Hiromi; Hata, Kenichiro; Yoshida, Teruhiko; Matsumoto, Kenji; Kiyokawa, Nobutaka; Ohara, Akira

    2014-06-01

    We identified ATF7IP as a novel PDGFRB fusion partner in B-progenitor acute lymphoblastic leukaemia (B-ALL) and showed that B-ALL with ATF7IP/PDGFRB translocation is included within the genomic lesions of a Philadelphia chromosome (Ph)-like ALL subgroup. Comprehensive analyses of previous repositories of gene expression data sets disclosed that B-ALL cases with high PDGFRB expression level in the context of the Ph-like ALL gene are likely to have a PDGFRB translocation. Thus, it is possible that measurement of the PDGFRB expression level can be utilized as a screening test for the detection of the cryptic PDGFRB translocation, especially within the Ph-like ALL subgroup.

  11. ALD5, PAD1, ATF1 and ATF2 facilitate the catabolism of coniferyl aldehyde, ferulic acid and p-coumaric acid in Saccharomyces cerevisiae

    PubMed Central

    Adeboye, Peter Temitope; Bettiga, Maurizio; Olsson, Lisbeth

    2017-01-01

    The ability of Saccharomyces cerevisiae to catabolize phenolic compounds remains to be fully elucidated. Conversion of coniferyl aldehyde, ferulic acid and p-coumaric acid by S. cerevisiae under aerobic conditions was previously reported. A conversion pathway was also proposed. In the present study, possible enzymes involved in the reported conversion were investigated. Aldehyde dehydrogenase Ald5, phenylacrylic acid decarboxylase Pad1, and alcohol acetyltransferases Atf1 and Atf2, were hypothesised to be involved. Corresponding genes for the four enzymes were overexpressed in a S. cerevisiae strain named APT_1. The ability of APT_1 to tolerate and convert the three phenolic compounds was tested. APT_1 was also compared to strains B_CALD heterologously expressing coniferyl aldehyde dehydrogenase from Pseudomonas, and an ald5Δ strain, all previously reported. APT_1 exhibited the fastest conversion of coniferyl aldehyde, ferulic acid and p-coumaric acid. Using the intermediates and conversion products of each compound, the catabolic route of coniferyl aldehyde, ferulic acid and p-coumaric acid in S. cerevisiae was studied in greater detail. PMID:28205618

  12. ORMDL3 is an inducible lung epithelial gene regulating metalloproteases, chemokines, OAS, and ATF6.

    PubMed

    Miller, Marina; Tam, Arvin B; Cho, Jae Youn; Doherty, Taylor A; Pham, Alexa; Khorram, Naseem; Rosenthal, Peter; Mueller, James L; Hoffman, Hal M; Suzukawa, Maho; Niwa, Maho; Broide, David H

    2012-10-09

    Orosomucoid like 3 (ORMDL3) has been strongly linked with asthma in genetic association studies, but its function in asthma is unknown. We demonstrate that in mice ORMDL3 is an allergen and cytokine (IL-4 or IL-13) inducible endoplasmic reticulum (ER) gene expressed predominantly in airway epithelial cells. Allergen challenge induces a 127-fold increase in ORMDL3 mRNA in bronchial epithelium in WT mice, with lesser 15-fold increases in ORMDL-2 and no changes in ORMDL-1. Studies of STAT-6-deficient mice demonstrated that ORMDL3 mRNA induction highly depends on STAT-6. Transfection of ORMDL3 in human bronchial epithelial cells in vitro induced expression of metalloproteases (MMP-9, ADAM-8), CC chemokines (CCL-20), CXC chemokines (IL-8, CXCL-10, CXCL-11), oligoadenylate synthetases (OAS) genes, and selectively activated activating transcription factor 6 (ATF6), an unfolded protein response (UPR) pathway transcription factor. siRNA knockdown of ATF-6α in lung epithelial cells inhibited expression of SERCA2b, which has been implicated in airway remodeling in asthma. In addition, transfection of ORMDL3 in lung epithelial cells activated ATF6α and induced SERCA2b. These studies provide evidence of the inducible nature of ORMDL3 ER expression in particular in bronchial epithelial cells and suggest an ER UPR pathway through which ORMDL3 may be linked to asthma.

  13. ORMDL3 is an inducible lung epithelial gene regulating metalloproteases, chemokines, OAS, and ATF6

    PubMed Central

    Miller, Marina; Tam, Arvin B.; Cho, Jae Youn; Doherty, Taylor A.; Pham, Alexa; Khorram, Naseem; Rosenthal, Peter; Mueller, James L.; Hoffman, Hal M.; Suzukawa, Maho; Niwa, Maho; Broide, David H.

    2012-01-01

    Orosomucoid like 3 (ORMDL3) has been strongly linked with asthma in genetic association studies, but its function in asthma is unknown. We demonstrate that in mice ORMDL3 is an allergen and cytokine (IL-4 or IL-13) inducible endoplasmic reticulum (ER) gene expressed predominantly in airway epithelial cells. Allergen challenge induces a 127-fold increase in ORMDL3 mRNA in bronchial epithelium in WT mice, with lesser 15-fold increases in ORMDL-2 and no changes in ORMDL-1. Studies of STAT-6–deficient mice demonstrated that ORMDL3 mRNA induction highly depends on STAT-6. Transfection of ORMDL3 in human bronchial epithelial cells in vitro induced expression of metalloproteases (MMP-9, ADAM-8), CC chemokines (CCL-20), CXC chemokines (IL-8, CXCL-10, CXCL-11), oligoadenylate synthetases (OAS) genes, and selectively activated activating transcription factor 6 (ATF6), an unfolded protein response (UPR) pathway transcription factor. siRNA knockdown of ATF-6α in lung epithelial cells inhibited expression of SERCA2b, which has been implicated in airway remodeling in asthma. In addition, transfection of ORMDL3 in lung epithelial cells activated ATF6α and induced SERCA2b. These studies provide evidence of the inducible nature of ORMDL3 ER expression in particular in bronchial epithelial cells and suggest an ER UPR pathway through which ORMDL3 may be linked to asthma. PMID:23011799

  14. Power and particle balance studies using an instrumented limiter system on ATF

    SciTech Connect

    Uckan, T.; Mioduszewski, P.K.; Bigelow, T.S.; Glowienka, J.C.; Hiroe, S.; Murakami, M.; Wilgen, J.B.; Wing, W.R.

    1991-06-01

    Power and particle balance studies on the Advanced Toroidal Facility (ATF) torsatron are carried out using a rail limiter system. Both top and bottom limiters are made of graphite tile arrays, and these tiles are instrumented with thermocouples and Langmuir probes for calorimetric and particle flux measurements. Initial experimental results indicate that the limiter power loss accounts for about 12% of the total and the radiation loss for about 30% of the total; the rest of the plasma heating power appears to be going to the vessel wall. The particle flux to the limiters is also about 18%. The fractions of power and particle flux to the limiters are relatively lower than in tokamaks because of the low edge safety factor, q {approximately}1 rather than q {approximately}3 as in a typical tokamak, at the natural boundary of the ATF plasma (which results from the magnetic stellarator configuration of this currentless device). Therefore, for limiters of the same size, these fractions are about a factor of q lower in ATF than in a comparable tokamak device. 11 refs., 8 figs.

  15. Capillary electrophoresis as an analytical tool for monitoring nicotine in ATF regulated tobacco products.

    PubMed

    Ralapati, S

    1997-07-18

    Tobacco products are classified at different excise tax rates according to the Code of Federal Regulations. These include cigars, cigarettes, pipe tobacco, roll-your-own tobacco, chewing tobacco and snuff. Nicotine is the primary determinant of what constitutes a tobacco product from a regulatory standpoint. Determination of nicotine, therefore, is of primary importance and interest to ATF. Since nicotine is also the most abundant alkaloid found in tobacco, comprising about 98% of the total alkaloid content, a rapid method for the determination of nicotine in ATF regulated products is desirable. Capillary electrophoresis (CE), as an analytical technique, is rapidly gaining importance capturing the interest of analysts in several areas. The unique and powerful capabilities of CE including high resolution and short analysis times, make it a powerful analytical tool in the regulatory area as well. Preliminary studies using a 25 mM sodium phosphate buffer, pH 2.5 at 260 nm have yielded promising results for the analysis of nicotine in tobacco products. Application of an analytical method for the determination of nicotine by CE to ATF regulated tobacco products will be presented.

  16. Molecular pathway of near-infrared laser phototoxicity involves ATF-4 orchestrated ER stress

    PubMed Central

    Khan, Imran; Tang, Elieza; Arany, Praveen

    2015-01-01

    High power lasers are used extensively in medicine while lower power applications are popular for optical imaging, optogenetics, skin rejuvenation and a therapeutic modality termed photobiomodulation (PBM). This study addresses the therapeutic dose limits, biological safety and molecular pathway of near-infrared (NIR) laser phototoxicity. Increased erythema and tissue damage were noted in mice skin and cytotoxicity in cell cultures at phototoxic laser doses involving generation of reactive oxygen species (ROS) coupled with a rise in surface temperature (>45 °C). NIR laser phototoxicity results from Activating Transcription Factor-4 (ATF-4) mediated endoplasmic reticulum stress and autophagy. Neutralizations of heat or ROS and overexpressing ATF-4 were noted to rescue NIR laser phototoxicity. Further, NIR laser mediated phototoxicity was noted to be non-genotoxic and non-mutagenic. This study outlines the mechanism of NIR laser phototoxicity and the utility of monitoring surface temperature and ATF4 expression as potential biomarkers to develop safe and effective clinical applications. PMID:26030745

  17. Initial high-power testing of the ATF (Advanced Toroidal Facility) ECH (electron cyclotron heating) system

    SciTech Connect

    White, T.L.; Bigelow, T.S.; Kimrey, H.D. Jr.

    1987-01-01

    The Advanced Toroidal Facility (ATF) is a moderate aspect ratio torsatron that will utilize 53.2 GHz 200 kW Electron Cyclotron Heating (ECH) to produce nearly current-free target plasmas suitable for subsequent heating by strong neutral beam injection. The initial configuration of the ECH system from the gyrotron to ATF consists of an optical arc detector, three bellows, a waveguide mode analyzer, two TiO/sub 2/ mode absorbers, two 90/sup 0/ miter bends, two waveguide pumpouts, an insulating break, a gate valve, and miscellaneous straight waveguide sections feeding a launcher radiating in the TE/sub 02/ mode. Later, a focusing Vlasov launcher will be added to beam the ECH power to the saddle point in ATF magnetic geometry for optimum power deposition. The ECH system has several unique features; namely, the entire ECH system is evacuated, the ECH system is broadband, forward power is monitored by a newly developed waveguide mode analyzer, phase correcting miter bends will be employed, and the ECH system will be capable of operating short pulse to cw. Initial high-power tests show that the overall system efficiency is 87%. The waveguide mode analyzer shows that the gyrotron mode output consists of 13% TE/sub 01/, 82.6% TE/sub 02/, 2.5% TE/sub 03/, and 1.9% TE/sub 04/. 4 refs.

  18. ATF2 impairs glucocorticoid receptor–mediated transactivation in human CD8+ T cells

    PubMed Central

    Li, Ling-bo; Leung, Donald Y. M.; Strand, Matthew J.

    2007-01-01

    Chronic inflammatory diseases often have residual CD8+ T-cell infiltration despite treatment with systemic corticosteroids, which suggests divergent steroid responses between CD4+ and CD8+ cells. To examine steroid sensitivity, dexamethasone (DEX)–induced histone H4 lysine 5 (K5) acetylation and glucocorticoid receptor α (GCRα) translocation were evaluated. DEX treatment for 6 hours significantly induced histone H4 K5 acetylation in normal CD4+ cells (P = .001) but not in CD8+ cells. DEX responses were functionally impaired in CD8+ compared with CD4+ cells when using mitogen-activated protein kinase phosphatase (1 hour; P = .02) and interleukin 10 mRNA (24 hours; P = .004) induction as a readout of steroid-induced transactivation. Normal DEX-induced GCRα nuclear translocation and no significant difference in GCRα and GCRβ mRNA expression were observed in both T-cell types. In addition, no significant difference in SRC-1, p300, or TIP60 expression was found. However, activating transcription factor-2 (ATF2) expression was significantly lower in CD8+ compared with CD4+ cells (P = .009). Importantly, inhibition of ATF2 expression by small interfering RNA in CD4+ cells resulted in inhibition of DEX-induced transactivation in CD4+ cells. The data indicate refractory steroid-induced transactivation but similar steroid-induced transrepression of CD8+ cells compared with CD4+ cells caused by decreased levels of the histone acetyltransferase ATF2. PMID:17525285

  19. Ringing phenomenon of the fiber ring resonator.

    PubMed

    Ying, Diqing; Ma, Huilian; Jin, Zhonghe

    2007-08-01

    A resonator fiber-optic gyro (R-FOG) is a high-accuracy inertial rotation sensor based on the Sagnac effect. A fiber ring resonator is the core sensing element in the R-FOG. When the frequency of the fiber ring resonator input laser is swept linearly with time, ringing of the output resonance curve is observed. The output field of the fiber ring resonator is derived from the superposition of the light transmitted through the directional coupler directly and the multiple light components circulated in the fiber ring resonator when the frequency of the laser is swept. The amplitude and phase of the output field are analyzed, and it is found that the difference in time for different light components in the fiber ring resonator to reach a point of destructive interference causes the ringing phenomenon. Finally the ringing phenomenon is observed in experiments, and the experimental results agree with the theoretical analysis well.

  20. Validation Of Equivalent Viscous Damping Methodologies

    NASA Astrophysics Data System (ADS)

    Vaquer Araujo, Xavier; Fransen, S. H. J. A.; Germes, S.; Thiry, N.

    2012-07-01

    An important step in the design and verification process of spacecraft structures is the coupled dynamic analysis with the launch vehicle in the low-frequency domain. To obtain accurate predictions of the satellite’s dynamic environment it is essential that the damping of the system is correctly defined and taken into account within the resolution methodologies for the Coupled Loads Analysis (CLA). When working with finite element models, the materials’ damping is characterized by structural damping ratios. In addition, most of the load cases present in the CLA are transient excitations so the resolution of the equations of motion must be done in the time domain. Unfortunately, transient analyses cannot be carried out using structural damping models. Thus, a transformation from a structural to a viscous damping characterization is necessary. Nevertheless, this transformation is not trivial. There exist many methodologies aiming at computing an equivalent viscous damping matrix of the system so it can be used in transient analyses. This paper describes the results obtained in the validation of equivalent viscous damping methodologies used in the European Space Agency. This work permitted to identify the limitations of these methodologies and to come up with an enhanced methodology that predicts more reliable results.

  1. Material damping experiments at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Levine, Marie B.; White, Christopher

    2003-12-01

    NASA's James Webb Space Telescope (JWST) will be operating at temperatures below 40K to image in the infrared. The 7-m class telescope will require nanometric jitter stability of the optical elements such as the primary and secondary mirrors. Of particular concern is the vibration response of these cryogenic systems when subjected to on-board disturbance sources such as the reaction wheels, the amplitude of which is governed by damping. Unfortunately there is relatively little data available for flight grade materials at these temperatures and within the frequency bands of interest. The paper will describe the experimental setup designed to measure viscous damping to values as low 10^-4%. The tests measure damping from room temperature all the way down to 20K in a controlled thermal and disturbance free environment. Data is obtained for strain levels of about 0.1 micro-strain down to nano-strains to verify vibration level effects on material damping. Damping is also measured for several frequencies in the range of 20Hz to 300Hz to assess the trend of damping as a function of vibrational frequency. Data for several materials, such as Aluminum, Beryllium, Quartz, and various composites are presented. The data is compared to analytical predictions using the Zener damping theory and is shown to match well at room temperature but to disagree at colder temperatures.

  2. Bounce harmonic Landau damping of plasma waves

    NASA Astrophysics Data System (ADS)

    Anderegg, F.; Affolter, M.; Kabantsev, A. A.; Dubin, D. H. E.; Ashourvan, A.; Driscoll, C. F.

    2016-05-01

    We present measurements of bounce harmonic Landau damping due to z-variations in the plasma potential, created by an azimuthally symmetric "squeeze" voltage Vs applied to the cylindrical wall. Traditional Landau damping on spatially uniform plasma is weak in regimes where the wave phase velocity vp h≡ω/k is large compared to the thermal velocity. However, z-variations in plasma density and potential create higher spatial harmonics, which enable resonant wave damping by particles with bounce-averaged velocities vp h/n , where n is an integer. In our geometry, the applied squeeze predominantly generates a resonance at vp h/3 . Wave-coherent laser induced fluorescence measurements of particle velocities show a distinctive Landau damping signature at vp h/3 , with amplitude proportional to the applied Vs. The measured (small amplitude) wave damping is then proportional to Vs2 , in quantitative agreement with theory over a range of 20 in temperature. Significant questions remain regarding "background" bounce harmonic damping due to ubiquitous confinement fields and regarding the saturation of this damping at large wave amplitudes.

  3. The Ring Sculptor

    NASA Image and Video Library

    2006-09-08

    Prometheus zooms across the Cassini spacecraft field of view, attended by faint streamers and deep gores in the F ring. This movie sequence of five images shows the F ring shepherd moon shaping the ring inner edge

  4. Beyond Bright Rings

    NASA Image and Video Library

    2009-12-30

    The tiny moon Pandora appears beyond the bright disk of Saturn rings in this image taken by NASA Cassini spacecraft. Pandora orbits outside the F ring and, in this image, is farther from Cassini than the rings are.

  5. Enhanced Damping for Capillary Bridge Oscillation Using Velocity Feedback

    NASA Technical Reports Server (NTRS)

    Wei, Wei; Thiessen, David B.; Marston, Philip L.

    2004-01-01

    The stability of cylindrical liquid bridges in reduced gravity is affected by ambient vibrations of the spacecraft. Such vibrations are expected to excite capillary modes of the bridge. The lowest-order unstable mode is particularly susceptible to vibration as the length of the bridge approaches the stability limit. This low-order mode is known as the (2,0) mode and is an axisymmetric varicose mode of one wavelength in the axial direction. In this work, an optical system is used to detect the (2,0)-mode amplitude. The derivative of the error signal produced by this detector is used to produce the appropriate voltages on a pair of ring electrodes which are concentric with the bridge. A mode-coupled Maxwell stress profile is thus generated in proportional to the modal velocity. Depending on the sign of the gain, the damping of the capillary oscillation can be either increased or decreased. This effect has been demonstrated in Plateau-tank experiments. Increasing the damping of the capillary modes on free liquid surfaces in space could be beneficial for containerless processing and other novel technologies.

  6. Enhanced Damping for Capillary Bridge Oscillation Using Velocity Feedback

    NASA Technical Reports Server (NTRS)

    Wei, Wei; Thiessen, David B.; Marston, Philip L.

    2004-01-01

    The stability of cylindrical liquid bridges in reduced gravity is affected by ambient vibrations of the spacecraft. Such vibrations are expected to excite capillary modes of the bridge. The lowest-order unstable mode is particularly susceptible to vibration as the length of the bridge approaches the stability limit. This low-order mode is known as the (2,0) mode and is an axisymmetric varicose mode of one wavelength in the axial direction. In this work, an optical system is used to detect the (2,0)-mode amplitude. The derivative of the error signal produced by this detector is used to produce the appropriate voltages on a pair of ring electrodes which are concentric with the bridge. A mode-coupled Maxwell stress profile is thus generated in proportional to the modal velocity. Depending on the sign of the gain, the damping of the capillary oscillation can be either increased or decreased. This effect has been demonstrated in Plateau-tank experiments. Increasing the damping of the capillary modes on free liquid surfaces in space could be beneficial for containerless processing and other novel technologies. [work supported by NASA

  7. 49 CFR 40.227 - May employers use the ATF for non-DOT tests, or non-DOT forms for DOT tests?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false May employers use the ATF for non-DOT tests, or..., Equipment and Supplies Used in Alcohol Testing § 40.227 May employers use the ATF for non-DOT tests, or non-DOT forms for DOT tests? (a) No, as an employer, BAT, or STT, you are prohibited from using the ATF...

  8. Asymmetric dipolar ring

    DOEpatents

    Prosandeev, Sergey A.; Ponomareva, Inna V.; Kornev, Igor A.; Bellaiche, Laurent M.

    2010-11-16

    A device having a dipolar ring surrounding an interior region that is disposed asymmetrically on the ring. The dipolar ring generates a toroidal moment switchable between at least two stable states by a homogeneous field applied to the dipolar ring in the plane of the ring. The ring may be made of ferroelectric or magnetic material. In the former case, the homogeneous field is an electric field and in the latter case, the homogeneous field is a magnetic field.

  9. Experimental verification of damping mechanisms in a composite beam

    NASA Technical Reports Server (NTRS)

    Cudney, Harley H.; Inman, Daniel J.

    1989-01-01

    A method of estimating the distributed damping parameters based on the measured modal parameters (frequency and damping ratios) was derived. Three different mathematical models were used to model the damping mechanism of a quasi-isotropic pultruded cantilevered beam. These three models were (1) viscous (air) damping, (2) strain rate damping, and (3) both viscous and strain rate damping. The eigenvalues of the partial differential equation model were found to be uninfluenced by any of the three assumed damping models. Values were obtained for each of the damping models as well as the modulus of elasticity of the beam. It was found that the two-parameter damping model provided the best fit to measured modal data. However, the two-parameter damping model could only reproduce the measured damping ratios to within 85 percent.

  10. Investigation on the mechanism of damping behavior of magnetorheological elastomers

    NASA Astrophysics Data System (ADS)

    Yang, Jie; Gong, Xinglong; Deng, Huaxia; Qin, Lijun; Xuan, Shouhu

    2012-12-01

    Magnetorheological elastomers (MREs) are a group of smart materials which have many applications such as dynamic vibration absorbers, engine mounts, and so on. The damping behavior is important for applications of MREs. However, the mechanism of the damping of MREs has not been investigated thoroughly. In this study, MREs are modeled as special particle reinforced composites with magneto-induced properties and the mechanism of the damping behavior of MREs is investigated theoretically and experimentally. It has been found that there are three types of damping property in MREs: the intrinsic damping, the interface damping and the magneto-mechanical damping. The presented damping model is successfully validated by damping tests on a series of MRE samples. Furthermore, the relationships between the damping properties and formulas of MREs are discussed; this provides guidance for the manufacture of MREs with various damping properties.

  11. A Resonant Damping Study Using Piezoelectric Materials

    NASA Technical Reports Server (NTRS)

    Min, J. B.; Duffy, K. P.; Choi, B. B.; Morrison, C. R.; Jansen, R. H.; Provenza, A. J.

    2008-01-01

    Excessive vibration of turbomachinery blades causes high cycle fatigue (HCF) problems requiring damping treatments to mitigate vibration levels. Based on the technical challenges and requirements learned from previous turbomachinery blade research, a feasibility study of resonant damping control using shunted piezoelectric patches with passive and active control techniques has been conducted on cantilever beam specimens. Test results for the passive damping circuit show that the optimum resistive shunt circuit reduces the third bending resonant vibration by almost 50%, and the optimum inductive circuit reduces the vibration by 90%. In a separate test, active control reduced vibration by approximately 98%.

  12. Radiation damping of a polarizable particle

    NASA Astrophysics Data System (ADS)

    Novotny, Lukas

    2017-09-01

    A polarizable body moving in an external electromagnetic field will slow down. This effect is referred to as radiation damping and is analogous to Doppler cooling in atomic physics. Using the principles of special relativity we derive an expression for the radiation damping force and find that it solely depends on the scattered power. The cooling of the particle's center-of-mass motion is balanced by heating due to radiation pressure shot noise, giving rise to an equilibrium that depends on the ratio of the field's frequency and the particle's mass. While damping is of relativistic nature, heating has its roots in quantum mechanics.

  13. Oscillation damped movement of suspended objects

    SciTech Connect

    Jones, J.F.; Petterson, B.J.

    1988-01-01

    Transportation of objects using overhead cranes or manipulators can induce pendulum motion of the object. Residual oscillation from transportation typically must be damped or allowed to decay before the next process can take place. By properly programming the acceleration of the transporting device (e.g., crane) an oscillation damped transport and swing free stop is obtainable. This paper reviews the theory associated with oscillation damped trajectories for simply suspended objects and describes a particular implementation using a CIMCORP XR 6100 gantry robot. 8 refs., 7 figs., 1 tab.

  14. Nonlinear Landau damping of Alfven waves.

    NASA Technical Reports Server (NTRS)

    Hollweg, J. V.

    1971-01-01

    Demonstration that large-amplitude linearly or elliptically polarized Alfven waves propagating parallel to the average magnetic field can be dissipated by nonlinear Landau damping. The damping is due to the longitudinal electric field associated with the ion sound wave which is driven (in second order) by the Alfven wave. The damping rate can be large even in a cold plasma (beta much less than 1, but not zero), and the mechanism proposed may be the dominant one in many plasmas of astrophysical interest.

  15. Transcription factor ATF4 directs basal and stress-induced gene expression in the unfolded protein response and cholesterol metabolism in the liver.

    PubMed

    Fusakio, Michael E; Willy, Jeffrey A; Wang, Yongping; Mirek, Emily T; Al Baghdadi, Rana J T; Adams, Christopher M; Anthony, Tracy G; Wek, Ronald C

    2016-05-01

    Disturbances in protein folding and membrane compositions in the endoplasmic reticulum (ER) elicit the unfolded protein response (UPR). Each of three UPR sensory proteins-PERK (PEK/EIF2AK3), IRE1, and ATF6-is activated by ER stress. PERK phosphorylation of eIF2 represses global protein synthesis, lowering influx of nascent polypeptides into the stressed ER, coincident with preferential translation of ATF4 (CREB2). In cultured cells, ATF4 induces transcriptional expression of genes directed by the PERK arm of the UPR, including genes involved in amino acid metabolism, resistance to oxidative stress, and the proapoptotic transcription factor CHOP (GADD153/DDIT3). In this study, we characterize whole-body and tissue-specific ATF4-knockout mice and show in liver exposed to ER stress that ATF4 is not required for CHOP expression, but instead ATF6 is a primary inducer. RNA-Seq analysis indicates that ATF4 is responsible for a small portion of the PERK-dependent UPR genes and reveals a requirement for expression of ATF4 for expression of genes involved in oxidative stress response basally and cholesterol metabolism both basally and under stress. Consistent with this pattern of gene expression, loss of ATF4 resulted in enhanced oxidative damage, and increased free cholesterol in liver under stress accompanied by lowered cholesterol in sera.

  16. Binding of the transcription factor Atf1 to promoters serves as a barrier to phase nucleosome arrays and avoid cryptic transcription

    PubMed Central

    García, Patricia; Paulo, Esther; Gao, Jun; Wahls, Wayne P.; Ayté, José; Lowy, Ernesto; Hidalgo, Elena

    2014-01-01

    Schizosaccharomyces pombe displays a large transcriptional response common to several stress conditions, regulated primarily by the transcription factor Atf1. Atf1-dependent promoters contain especially broad nucleosome depleted regions (NDRs) prior to stress imposition. We show here that basal binding of Atf1 to these promoters competes with histones to create wider NDRs at stress genes. Moreover, deletion of atf1 results in nucleosome disorganization specifically at stress coding regions and derepresses antisense transcription. Our data indicate that the transcription factor binding to promoters acts as an effective barrier to fix the +1 nucleosome and phase downstream nucleosome arrays to prevent cryptic transcription. PMID:25122751

  17. Transcription factor ATF4 directs basal and stress-induced gene expression in the unfolded protein response and cholesterol metabolism in the liver

    PubMed Central

    Fusakio, Michael E.; Willy, Jeffrey A.; Wang, Yongping; Mirek, Emily T.; Al Baghdadi, Rana J. T.; Adams, Christopher M.; Anthony, Tracy G.; Wek, Ronald C.

    2016-01-01

    Disturbances in protein folding and membrane compositions in the endoplasmic reticulum (ER) elicit the unfolded protein response (UPR). Each of three UPR sensory proteins—PERK (PEK/EIF2AK3), IRE1, and ATF6—is activated by ER stress. PERK phosphorylation of eIF2 represses global protein synthesis, lowering influx of nascent polypeptides into the stressed ER, coincident with preferential translation of ATF4 (CREB2). In cultured cells, ATF4 induces transcriptional expression of genes directed by the PERK arm of the UPR, including genes involved in amino acid metabolism, resistance to oxidative stress, and the proapoptotic transcription factor CHOP (GADD153/DDIT3). In this study, we characterize whole-body and tissue-specific ATF4-knockout mice and show in liver exposed to ER stress that ATF4 is not required for CHOP expression, but instead ATF6 is a primary inducer. RNA-Seq analysis indicates that ATF4 is responsible for a small portion of the PERK-dependent UPR genes and reveals a requirement for expression of ATF4 for expression of genes involved in oxidative stress response basally and cholesterol metabolism both basally and under stress. Consistent with this pattern of gene expression, loss of ATF4 resulted in enhanced oxidative damage, and increased free cholesterol in liver under stress accompanied by lowered cholesterol in sera. PMID:26960794

  18. Damping of the dipole vortex.

    PubMed

    Li, Xin; Pierce, Donna M; Arnoldus, Henk F

    2011-05-01

    When a circular electric dipole moment, rotating in the x-y plane, is embedded in a material with relative permittivity ε(r) and relative permeability μ(r), the field lines of energy flow of the emitted radiation are dramatically influenced by the surrounding material. For emission in free space, the field lines swirl around the z axis and lie on a cone. The direction of rotation of the field lines around the z axis is the same as the direction of rotation of the dipole moment. We found that when the real part of ε(r) is negative, the rotation of the field lines changes direction, and hence the energy counter-rotates the dipole moment. When there is damping in the material, due to an imaginary part of ε(r), the cone turns into a funnel, and the density of the field lines diminishes near the location of the source. In addition, all radiation is emitted along the z axis and the x-y plane, whereas for emission in free space, the radiation is emitted in all directions. It is also shown that the displacement of the dipole image in the far field depends on the material parameters and that the shift can be much larger than the shift of the image in free space.

  19. Turbine blade friction damping study

    NASA Technical Reports Server (NTRS)

    Dominic, R. J.

    1985-01-01

    A lumped parameter method, implemented on a VAX 11/780 computer shows that the primary parameters affecting the performance of the friction damper of the first stage turbine of the SSME high pressure fuel pump are: the damper-blade coefficient of friction; the normal force applied to the friction interface; the amplitude of the periodic forcing function; the relative phase angle of the forcing functions for adjacent blades bridged by a damper (effectively, the engine order of the forcing function); and the amount of hysteretic damping that acts to limit the vibration amplitude of the blade in its resonance modes. The low order flexural resonance vibration modes of HPFTP blades without dampers, with production dampers, and with two types of lightweight experimental dampers were evaluated in high speed spin pit tests. Results agree with those of the analytical study in that blades fitted with production friction dampers experienced the airfoil-alone flexural resonance mode, while those without dampers or with lighter weight dampers did not. No blades fitted with dampers experienced the whole blade flexural resonance mode during high speed tests, while those without dampers did.

  20. Bursts of Coherent Synchrotron Radiation in Electron Storage Rings: a Dynamical Model

    SciTech Connect

    Venturini, Marco

    2002-09-17

    Evidence of coherent synchrotron radiation (CSR) has been reported recently at the electron storage rings of several light source facilities. The main features of the observations are (i) a radiation wavelength short compared to the nominal bunch length, and (ii) a coherent signal showing recurrent bursts of duration much shorter than the radiation damping time, but with spacing equal to a substantial fraction of the damping time. We present a model of beam longitudinal dynamics that reproduces these features.