Effects of outer perturbances on dynamics of wake vortices
International Nuclear Information System (INIS)
Baranov, N.A.; Belotserkovsky, A.S.; Turchak, L.I.
2004-01-01
One of the problems in aircraft flight safety is reduction of the risk related with aircraft encounter with wake vortices generated by other aircraft. An efficient approach to this problem is design of systems providing information on areas of potential danger of wake vortices to pilots in real time. The main components of such a system are a unit for calculations of wake vortices behind aircraft and a unit for calculations of areas of potential danger. A promising way to development of real time algorithms for calculation of wake vortices is the use of vortex methods in CFD based on the hypothesis of quasi-3D flow in the area of wake vorticity. The mathematical model developed by our team calculates positions and intensity of wake vortices past aircraft taking account of such effects as viscous dissipation of vortices, effects of ambient turbulence, wind shear, as well as viscous interaction between wake vortices and the underlying surface. The necessity of including the last factor could be stems from the fact that in the case where wake vortices are in close proximity of the rigid surface, the viscous interaction between the wake vortices and the surface boundary layer results in the boundary layer separation changing the overall intensity and dynamics of the wake vortices. To evaluate the boundaries of the danger areas the authors use an approach based on calculation of additional aerodynamic forces and moments acting on the aircraft encountering wake vortices by means of evaluation of the aircraft additional velocities and angular rates corresponding to distribution of disturbed velocities on the aircraft surface. These criteria could be based on local characteristics of the vorticity areas or on characteristics related to the perturbation effects on the aircraft. The latter characteristics include the actual aerodynamic roll moment, the maximum angular rate or the maximum roll of the aircraft under perturbations in the wake vortices. To estimate the accuracy
International Nuclear Information System (INIS)
Iyer, S.V.; Vafai, K.
1999-01-01
The study of natural convection flow and heat transfer within a cylindrical annulus has received considerable attention because of its numerous applications, such as in nuclear reactor design, electronic component cooling, thermal storage systems, energy conservation, energy storage, and energy transmission. Here, the effects of multiple geometric perturbations on the inner and outer cylinders of an annulus with impermeable end walls are investigated in this work. A three-dimensional study was done using a numerical scheme based on a Galerkin method of finite element formulation. The nature of the buoyancy-induced flow field has been analyzed in detail. The flow fields for the cases considered were found to be qualitatively similar, and the introduction of each additional perturbation altered the flow field in a regular and recurring manner. The introduction of each perturbation on the outer cylinder causes clockwise and counterclock-wise rotating patterns on either side of the perturbation in the upper circumferential regions of the annulus. The motion of the fluid entrained by these circulatory patterns constitutes the key features of the flow pattern observed in the annulus. It is observed that the presence of multiple perturbations on the inner and outer cylinders substantially increases the overall heat transfer rate as compared to the regular annulus without any perturbation. Key qualitative and quantitative effects of the introduction of perturbations on both the inner and outer cylinders of the annulus are discussed
Ultrasonic examination of defects close to the outer surface
International Nuclear Information System (INIS)
Benoist, P.; Serre, M.; Champigny, F.
1986-11-01
During the examination of a pressurized water reactor vessel with an in Service Inspection Machine (MIS), various welds are scanned with immersion ultrasonic focused transducers from the inside of the vessel. Defects close to the outer surface are sometimes detected, and sizing with the successive 6 dB drop method leads to oversize some indications; this is caused by various reflections on the outer wall; the corner echo is of particular importance here. CEA and EDF have started an experimental program in order to study the response of volumetric and planar defects located near the outer surface. We present here the first results obtained with artificial defects. 2 refs
Stability of marginally outer trapped surfaces and symmetries
Energy Technology Data Exchange (ETDEWEB)
Carrasco, Alberto; Mars, Marc, E-mail: acf@usal.e, E-mail: marc@usal.e [Facultad de Ciencias, Universidad de Salamanca, Plaza de la Merced s/n, 37008 Salamanca (Spain)
2009-09-07
We study the properties of stable, strictly stable and locally outermost marginally outer trapped surfaces in spacelike hypersurfaces of spacetimes possessing certain symmetries such as isometries, homotheties and conformal Killings. We first obtain results for general diffeomorphisms in terms of the so-called metric deformation tensor and then particularize to different types of symmetries. In particular, we find restrictions at the surfaces on the vector field generating the symmetry. Some consequences are discussed. As an application, we present a result on non-existence of stable marginally outer trapped surfaces in slices of FLRW.
Current Density and Plasma Displacement Near Perturbed Rational Surface
International Nuclear Information System (INIS)
Boozer, A.H.; Pomphrey, N.
2010-01-01
The current density in the vicinity of a rational surface of a force-free magnetic field subjected to an ideal perturbation is shown to be the sum of both a smooth and a delta-function distribution, which give comparable currents. The maximum perturbation to the smooth current density is comparable to a typical equilibrium current density and the width of the layer in which the current flows is shown to be proportional to the perturbation amplitude. In the standard linearized theory, the plasma displacement has an unphysical jump across the rational surface, but the full theory gives a continuous displacement.
Fluid flow near the surface of earth's outer core
Bloxham, Jeremy; Jackson, Andrew
1991-01-01
This review examines the recent attempts at extracting information on the pattern of fluid flow near the surface of the outer core from the geomagnetic secular variation. Maps of the fluid flow at the core surface are important as they may provide some insight into the process of the geodynamo and may place useful constraints on geodynamo models. In contrast to the case of mantle convection, only very small lateral variations in core density are necessary to drive the flow; these density variations are, by several orders of magnitude, too small to be imaged seismically; therefore, the geomagnetic secular variation is utilized to infer the flow. As substantial differences exist between maps developed by different researchers, the possible underlying reasons for these differences are examined with particular attention given to the inherent problems of nonuniqueness.
International Nuclear Information System (INIS)
Kubo, S; Ioka, S; Onchi, S; Matsumoto, Y
2010-01-01
When slug flow runs through a pipe, nonuniform and time-varying thermal stresses develop and there is a possibility that thermal fatigue occurs. Therefore it is necessary to know the temperature distributions and the stress distributions in the pipe for the integrity assessment of the pipe. It is, however, difficult to measure the inner surface temperature directly. Therefore establishment of the estimation method of the temperature history on inner surface of pipe is needed. As a basic study on the estimation method of the temperature history on the inner surface of a pipe with slug flow, this paper presents an estimation method of the temperature on the inner surface of a plate from the temperature on the outer surface. The relationship between the temperature history on the outer surface and the inner surface is obtained analytically. Using the results of the mathematical analysis, the inverse analysis method of the inner surface temperature history estimation from the outer surface temperature history is proposed. It is found that the inner surface temperature history can be estimated from the outer surface temperature history by applying the inverse analysis method, even when it is expressed by the multiple frequency components.
International Nuclear Information System (INIS)
Ohta, Takahiro; Terasaki, Toshio
2009-01-01
The new process called L-SIP (outer surface irradiated Laser Stress Improvement Process) is developed to improve the tensile residual stress of the inner surface near the butt welded joints of pipes in the compression stress. The temperature gradient occurs in the thickness of pipes in heating the outer surface rapidly by laser beam. By the thermal expansion difference between the inner surface and the outer surface, the compression plastic strain generates near the outer surface and the tensile plastic strain generates near the inner surface of pipes. The compression stress occurs near the inner surface of pipes by the plastic deformation. In this paper, the theoretical equation which calculates residual stress distribution from the inherent strain distribution in the thickness of pipes is derived. And, the relation between the distribution of temperature and the residual stress in the thickness is examined for various pipes size. (1) By rapidly heating from the outer surface, the residual stress near the inner surface of the pipe is improved to the compression stress. (2) Pipes size hardly affects the distribution of the residual stress in the stainless steel pipes for piping (JISG3459). (3) The temperature rising area from the outside is smaller, the area of the compression residual stress near the inner surface becomes wider. (author)
Random surfaces: A non-perturbative regularization of strings?
International Nuclear Information System (INIS)
Ambjoern, J.
1989-12-01
I review the basic properties of the theory of randum surfaces. While it is by now well known that the theory of (discretized) random surfaces correctly describes the (perturbative) aspects of non-critical strings in d 1. In these lectures I intend to show that the theory of dynamical triangulated random surfaces provides us with a lot of information about the dynamics of both the bosonic string and the superstring even for d>1. I also briefly review recent attempts to define a string field theory (sum over all genus) in this approach. (orig.)
Fine tuning the ionic liquid-vacuum outer atomic surface using ion mixtures.
Villar-Garcia, Ignacio J; Fearn, Sarah; Ismail, Nur L; McIntosh, Alastair J S; Lovelock, Kevin R J
2015-03-28
Ionic liquid-vacuum outer atomic surfaces can be created that are remarkably different from the bulk composition. In this communication we demonstrate, using low-energy ion scattering (LEIS), that for ionic liquid mixtures the outer atomic surface shows significantly more atoms from anions with weaker cation-anion interactions (and vice versa).
Semiclassical perturbation theory for diffraction in heavy atom surface scattering.
Miret-Artés, Salvador; Daon, Shauli; Pollak, Eli
2012-05-28
The semiclassical perturbation theory formalism of Hubbard and Miller [J. Chem. Phys. 78, 1801 (1983)] for atom surface scattering is used to explore the possibility of observation of heavy atom diffractive scattering. In the limit of vanishing ℏ the semiclassical theory is shown to reduce to the classical perturbation theory. The quantum diffraction pattern is sensitive to the characteristics of the beam of incoming particles. Necessary conditions for observation of quantum diffraction are derived for the angular width of the incoming beam. An analytic expression for the angular distribution as a function of the angular and momentum variance of the incoming beam is obtained. We show both analytically and through some numerical results that increasing the angular width of the incident beam leads to decoherence of the quantum diffraction peaks and one approaches the classical limit. However, the incoherence of the beam in the parallel direction does not destroy the diffraction pattern. We consider the specific example of Ar atoms scattered from a rigid LiF(100) surface.
Non-perturbative string theories and singular surfaces
International Nuclear Information System (INIS)
Bochicchio, M.
1990-01-01
Singular surfaces are shown to be dense in the Teichmueller space of all Riemann surfaces and in the grasmannian. This happens because a regular surface of genus h, obtained identifying 2h disks in pairs, can be approximated by a very large genus singular surface with punctures dense in the 2h disks. A scale ε is introduced and the approximate genus is defined as half the number of connected regions covered by punctures of radius ε. The non-perturbative partition function is proposed to be a scaling limit of the partition function on such infinite genus singular surfaces with a weight which is the coupling constant g raised to the approximate genus. For a gaussian model in any space-time dimension the regularized partition function on singular surfaces of infinite genus is the partition function of a two-dimensional lattice gas of charges and monopoles. It is shown that modular invariance of the partition function implies a version of the Dirac quantization condition for the values of the e/m charges. Before the scaling limit the phases of the lattice gas may be classified according to the 't Hooft criteria for the condensation of e/m operators. (orig.)
Charged particle modification of surfaces in the outer solar system
International Nuclear Information System (INIS)
Johnson, R.E.
1987-01-01
Voyager reflectance spectra data have indicated clear leading/trailing differences in the albedo of the icy Galilean and Saturian satellites. For the Galilean satellites, these have been analyzed by Nelson, et al. and, more recently, by McEwen. They have described the longitudinal dependence of this data and attempted to interpret this in terms of plasma and meteorite modification of the surface. Primary attention has been paid to Europa at which the leading/trailing differences are the largest. This data was reanalyzed extracting the single grain albedo (w) and constructing the Espat-function, W = (1-w)/w from this. Because w is near unity, W is approximately 2(alpha)D where alpha is the absorption coefficient and D is the grain size. In doing so, a direct comparison to the longitudinal plasma bombardment flux was found for the first time. This occurs primarily in the UV and is probably due to an absorption associated with implanted S, as the UV band of Voyager overlaps the IUE data of Lane et al. The relative importance of grain size effects and implant impurity effects can now be studied
New configuration for efficient and durable copper coating on the outer surface of a tube
Directory of Open Access Journals (Sweden)
Irfan Ahmad
2017-03-01
Full Text Available A well-adhered copper coating on stainless steel power coupler parts is required in superconducting radio frequency (SRF accelerators. Radio frequency power coupler parts are complex, tubelike stainless steel structures, which require copper coating on their outer and inner surfaces. Conventional copper electroplating sometimes produces films with inadequate adhesion strength for SRF applications. Electroplating also requires a thin nickel strike layer under the copper coating, whose magnetic properties can be detrimental to SRF applications. Coaxial energetic deposition (CED and sputtering methods have demonstrated efficient conformal coating on the inner surfaces of tubes but coating the outer surface of a tube is challenging because these coating methods are line of sight. When the substrate is off axis and the plasma source is on axis, only a small section of the substrate’s outer surface is exposed to the source cathode. The conventional approach is to rotate the tube to achieve uniformity across the outer surface. This method results in poor film thickness uniformity and wastes most of the source plasma. Alameda Applied Sciences Corporation (AASC has developed a novel configuration called hollow external cathode CED (HEC-CED to overcome these issues. HEC-CED produces a film with uniform thickness and efficiently uses all eroded source material. The Cu film deposited on the outside of a stainless steel tube using the new HEC-CED configuration survived a high pressure water rinse adhesion test. HEC-CED can be used to coat the outside of any cylindrical structure.
Bouchon, B.; Klein, Michele; Bischoff, Rainer; Van Dorsselaer, A.; Roitsch, C.
1997-01-01
The outer surface protein A, OspA, from the spirochete Borrelia burgdorferi is a lipoprotein of 25 kDa. The recombinant OspA (rOspA) expressed in Escherichia coli has been purified and analyzed by electrospray mass spectrometry (ESMS). A heterogenous spectrum gave a measured mass of 28,462 +/- 9 Da
Comparison of two perturbation methods to estimate the land surface modeling uncertainty
Su, H.; Houser, P.; Tian, Y.; Kumar, S.; Geiger, J.; Belvedere, D.
2007-12-01
In land surface modeling, it is almost impossible to simulate the land surface processes without any error because the earth system is highly complex and the physics of the land processes has not yet been understood sufficiently. In most cases, people want to know not only the model output but also the uncertainty in the modeling, to estimate how reliable the modeling is. Ensemble perturbation is an effective way to estimate the uncertainty in land surface modeling, since land surface models are highly nonlinear which makes the analytical approach not applicable in this estimation. The ideal perturbation noise is zero mean Gaussian distribution, however, this requirement can't be satisfied if the perturbed variables in land surface model have physical boundaries because part of the perturbation noises has to be removed to feed the land surface models properly. Two different perturbation methods are employed in our study to investigate their impact on quantifying land surface modeling uncertainty base on the Land Information System (LIS) framework developed by NASA/GSFC land team. One perturbation method is the built-in algorithm named "STATIC" in LIS version 5; the other is a new perturbation algorithm which was recently developed to minimize the overall bias in the perturbation by incorporating additional information from the whole time series for the perturbed variable. The statistical properties of the perturbation noise generated by the two different algorithms are investigated thoroughly by using a large ensemble size on a NASA supercomputer and then the corresponding uncertainty estimates based on the two perturbation methods are compared. Their further impacts on data assimilation are also discussed. Finally, an optimal perturbation method is suggested.
Nawasreh, Zakariya; Logerstedt, David; Failla, Mathew; Snyder-Mackler, Lynn
2017-10-27
Manual perturbation training improves dynamic knee stability and functional performance after anterior cruciate ligament rupture (ACL-rupture). However, it is limited to static standing position and does not allow time-specific perturbations at different phase of functional activities. The purpose of this study was to investigate whether administering mechanical perturbation training including compliant surface provides effects similar to manual perturbation training on knee functional measures after an acute ACL-rupture. Sixteen level I/II athletes with ACL-ruptures participated in this preliminary study. Eight patients received mechanical (Mechanical) and eight subjects received manual perturbation training (Manual). All patients completed a functional testing (isometric quadriceps strength, single-legged hop tests) and patient-reported measures (Knee Outcome Survey-Activities of Daily Living Scale (KOS-ADLS), Global Rating Score (GRS), International Knee Documentation Committee 2000 (IKDC 2000) at pre- and post-training. 2 × 2 ANOVA was used for data analysis. No significant group-by-time interactions were found for all measures (p > 0.18). Main effects of time were found for single hop (Pre-testing: 85.14% ± 21.07; Post-testing: 92.49% ± 17.55), triple hop (Pre-testing: 84.64% ± 14.17; Post-testing: 96.64% ± 11.14), KOS-ADLS (Pre-testing: 81.13% ± 11.12; Post-testing: 88.63% ± 12.63), GRS (Pre-testing: 68.63% ± 15.73; Post-testing: 78.81% ± 13.85), and IKDC 2000 (Pre-testing: 66.66% ± 9.85; Post-testing: 76.05% ± 14.62) (p training using compliant surfaces induce effects similar to manual perturbation training on knee functional performance after acute ACL-rupture. The clinical significance is both modes of training improve patients' functional-performance and limb-to-limb movement symmetry, and enhancing the patients' self-reported of knee functional measures after ACL rupture. Mechanical
DEFF Research Database (Denmark)
Koehler, JF; Birkelund, Svend; Stephens, RS
1992-01-01
The Chlamydia trachomatis major outer membrane protein (MOMP) is the quantitatively predominant surface protein which has important functional, structural and antigenic properties. We have cloned and overexpressed the MOMP in Escherichia coli. The MOMP is surface exposed in C. trachomatis....... The induction of MOMP expression had a rapidly lethal effect on the L2rMOMP E. coli clone. Although no genetic system exists for Chlamydia, development of a stable, inducible E. coli clone which overexpresses the chlamydial MOMP permits a study of the biological properties of the MOMP, including...
International Nuclear Information System (INIS)
Mercier, C.
1989-02-01
The effect of a perturbing magnetic field on a field whose magnetic surfaces are tori nested around a closed central line is studied. This perturbation effect creates magnetic islands around surfaces with rational rotational transform. These islands are investigated analytically, which makes it possible to evaluate their size. The resulting turbulence of the medium can then be studied by calculating the interaction of two neighbouring islands
Non-perturbational surface-wave inversion: A Dix-type relation for surface waves
Haney, Matt; Tsai, Victor C.
2015-01-01
We extend the approach underlying the well-known Dix equation in reflection seismology to surface waves. Within the context of surface wave inversion, the Dix-type relation we derive for surface waves allows accurate depth profiles of shear-wave velocity to be constructed directly from phase velocity data, in contrast to perturbational methods. The depth profiles can subsequently be used as an initial model for nonlinear inversion. We provide examples of the Dix-type relation for under-parameterized and over-parameterized cases. In the under-parameterized case, we use the theory to estimate crustal thickness, crustal shear-wave velocity, and mantle shear-wave velocity across the Western U.S. from phase velocity maps measured at 8-, 20-, and 40-s periods. By adopting a thin-layer formalism and an over-parameterized model, we show how a regularized inversion based on the Dix-type relation yields smooth depth profiles of shear-wave velocity. In the process, we quantitatively demonstrate the depth sensitivity of surface-wave phase velocity as a function of frequency and the accuracy of the Dix-type relation. We apply the over-parameterized approach to a near-surface data set within the frequency band from 5 to 40 Hz and find overall agreement between the inverted model and the result of full nonlinear inversion.
International Nuclear Information System (INIS)
Chen, C.-K.; Su, C.-R.
2008-01-01
This study provides an inverse analysis to estimate the boundary thermal behavior of a furnace with two layer walls. The unknown temperature distribution of the outer surface and the geometry of the inner surface were estimated from the temperatures of a small number of measured points within the furnace wall. The present approach rearranged the matrix forms of the governing differential equations and then combined the reversed matrix method, the linear least squares error method and the concept of virtual area to determine the unknown boundary conditions of the furnace system. The dimensionless temperature data obtained from the direct problem were used to simulate the temperature measurements. The influence of temperature measurement errors upon the precision of the estimated results was also investigated. The advantage of this approach is that the unknown condition can be directly solved by only one calculation process without initially guessed temperatures, and the iteration process of the traditional method can be avoided in the analysis of the heat transfer. Therefore, the calculation in this work is more rapid and exact than the traditional method. The result showed that the estimation error of the geometry increased with increasing distance between measured points and inner surface and in preset error, and with decreasing number of measured points. However, the geometry of the furnace inner surface could be successfully estimated by only the temperatures of a small number of measured points within and near the outer surface under reasonable preset error
Magnetic surfaces and localized perturbations in the Wendelstein VII-A stellarator
International Nuclear Information System (INIS)
Wobig, H.
1986-09-01
The critical dependence of plasma confinement in low-shear stellarators, such as Wendelstein VII-A, on the external rotational transform can be explained on the basis of magnetic surface destruction. External symmetry-breaking perturbations generate islands on the low order rational magnetic surfaces. The islands are largest at t=1/2 and t=1/3. Confinement is optimum in close proximity to these values. In order to study the structure of surfaces under the influence of perturbations, a mapping procedure is used instead of field line integration. It is found that the neighbourhood of low- order rational surfaces is particularly robust against surface destruction. The reason is that in this vicinity only rational surfaces with large m and n exist (t=m/n). On these surfaces the external perturbation only generates small islands. In W VII-A the current leads to the helical windings are one symmetry- breaking perturbation, and there might also be others. It is possible to avoid field errors of this kind in future stellarators. (orig.)
Finite element simulation of surface defects in the automobile door outer panel
International Nuclear Information System (INIS)
Fukumura, Masaru; Yamasaki, Yuji; Inage, Daisuke; Fujita, Takashi
2004-01-01
Recently, a sheet metal forming simulation has become an indispensable tool for developing a new model of an automobile part within a limited short period. In these days, the utilization of a springback calculation of the formed part has been increasing. However, only a few papers on the prediction of surface defects have been reported in spite of serious needs.In this paper, surface defects in the door outer panel, especially those around the door handle embossment, have been investigated. Applying an explicit solver to the forming simulation, and an implicit solver to the springback calculation, we have tried to evaluate surface defects in the panel. In order to improve the accuracy of the simulation, numerical tools have been modeled including the precise shape of the draw beads so that the draw bead effects on both the material flow and the restraint on the springback deformation have been considered. Compared with the actual panel shape, which shows apparent surface defects, the simulated result has closely predicted the above defects around the embossment.To demonstrate the applicability of our simulation, a few sensitivity analyses have been carried out, modifying forming conditions such as blank holder force. Each result has shown slight but distinctive differences in the cross section profile of the panel. As a result, it has been realized that the influence of each considered factor on surface defects is qualitatively consistent with our practical knowledge
Miyata, Yoshiki; Minami, Masayo; Onbe, Shin; Sakamoto, Minoru; Matsuzaki, Hiroyuki; Nakamura, Toshio; Imamura, Mineo
2011-01-01
AMS (Accelerator Mass Spectrometry) radiocarbon dates for eight potsherds from a single piece of pottery from a wetland archaeological site indicated that charred material from the inner pottery surfaces (5052 ± 12 BP; N = 5) is about 90 (14)C years older than that from the outer surfaces (4961 ± 22 BP; N = 7). We considered three possible causes of this difference: the old wood effect, reservoir effects, and diagenesis. We concluded that differences in the radiocarbon ages between materials from the inner and outer surfaces of the same pot were caused either by the freshwater reservoir effect or by diagenesis. Moreover, we found that the radiocarbon ages of carbonized material on outer surfaces (soot) of pottery from other wetland archaeological sites were the same as the ages of material on inner surfaces (charred food) of the same pot within error, suggesting absence of freshwater reservoir effect or diagenesis.
International Nuclear Information System (INIS)
Ohta, Takahiro; Kamo, Kazuhiko; Muroya, Itaru; Asada, Seiji; Nakamura, Yasuo
2009-01-01
The new process called L-SIP (outer surface irradiated Laser Stress Improvement Process) is developed to improve the tensile residual stress of the inner surface near the butt welded joints of pipes in the compression stress. The temperature gradient occurs in the thickness of pipes in heating the outer surface rapidly by laser beam. By the thermal expansion difference between the inner surface and the outer surface, the compression stress occurs near the inner surface of pipes. In this paper, the essential variables for L-SIP is studied by experimental and FEM analysis. The range of the essential variables for L-SIP, which are defined by thermo-elastic FEM analysis, are Tmax=550 - 650degC, L Q /√rh ≥ 3, W Q /√rh ≥ 1.7, and, 0.04 ≤ F 0 ≤ 0.10 where Tmax is maximum temperature on the monitor point of the outer surface, F 0 is k x τ 0 /h 2 , k is thermal diffusivity coefficient, τ 0 is the temperature rise time from 100degC to maximum temperature on the monitor point of the outer surface, W Q is τ 0 x v, υ is moving velocity, L Q is the uniform temperature length in the axial direction, h is thickness of the pipe, and r is average radius of the pipe. It is showed by thermo-elastic-plastic FEM analysis that the residual stresses near the inner surface of pipes are improved in 4 different size pipes under the same essential variables. L-SIP is actually applied to welding joints of 4B x Sch160 and 2B x Sch80 SUS304 type stainless steel pipes within the defined range of the essential variables. The measured welding residual stresses on the inner surface near the welding joints are tensile. The residual stresses on the inner surface change to compression in all joints by L-SIP. (author)
Modeling Surface Processes Occurring on Moons of the Outer Solar System
Umurhan, O. M.; White, O. L.; Moore, J. M.; Howard, A. D.; Schenk, P.
2016-12-01
A variety of processes, some with familiar terrestrial analogs, are known to take place on moon surfaces in the outer solar system. In this talk, we discuss the observed features of mass wasting and surface transport seen on both Jupiter's moon Calisto and one of Saturn's Trojan moons Helene. We provide a number of numerical models using upgraded version of MARSSIM in support of several hypotheses suggested on behalf of the observations made regarding these objects. Calisto exhibits rolling plains of low albedo materials surrounding relatively high jutting peaks harboring high albedo deposits. Our modeling supports the interpretation that Calisto's surface is a record of erosion driven by the sublimation of CO2 and H2O contained in the bedrock. Both solar insolation and surface re-radiation drives the sublimation leaving behind debris which we interpret to be the observed darkened regolith and, further, the high albedo peaks are water ice deposits on surface cold traps. On the other hand, the 45 km scale Helene, being a milligravity environment, exhibits mysterious looking streaks and grooves of very high albedo materials extending for several kilometers with a down-sloping grade of 7o-9o. Helene's cratered terrain also shows evidence of narrowed septa. The observed surface features suggest some type of advective processes are at play in this system. Our modeling lends support to the suggestion that Helene's surface materials behave as a Bingham plastic material - our flow modeling with such rheologies can reproduce the observed pattern of streakiness depending upon the smoothness of the underlying bedrock; the overall gradients observed; and the narrowed septa of inter-crater regions.
Elastic-plastic fracture mechanics analysis of a pressure vessel with an axial outer surface flaw
International Nuclear Information System (INIS)
Aurich, D.
1988-04-01
Elastic-plastic finite element analyses of a test vessel (steel 1.6310=20 MnMoNi 55) with a semi-elliptical axial outer surface crack have been performed. The variations of J and CTOD along the crack front and the stresse state in the vicinity of the crack are presented. The applicability of approaches to determine J is examined. The FE results are compared with the experimental data. The results are analyzed with respect to the validity of J-controlled crack growth. It will be shown that the local ductile crack growth and, especially, the 'canoe effect' for a semi-elliptical crack can only be described correctly if local J R -curves are used which account for the varying triaxiality of the stress state along the crack front. (orig./HP) [de
Ionescu, Michael; Zaini, Paulo A; Baccari, Clelia; Tran, Sophia; da Silva, Aline M; Lindow, Steven E
2014-09-16
Outer membrane vesicles (OMVs) of Gram-negative bacteria have been studied intensively in recent years, primarily in their role in delivering virulence factors and antigens during pathogenesis. However, the near ubiquity of their production suggests that they may play other roles, such as responding to envelope stress or trafficking various cargoes to prevent dilution or degradation by other bacterial species. Here we show that OMVs produced by Xylella fastidiosa, a xylem-colonizing plant pathogenic bacterium, block its interaction with various surfaces such as the walls of xylem vessels in host plants. The release of OMVs was suppressed by the diffusible signal factor-dependent quorum-sensing system, and a X. fastidiosa ΔrpfF mutant in which quorum signaling was disrupted was both much more virulent to plants and less adhesive to glass and plant surfaces than the WT strain. The higher virulence of the ΔrpfF mutant was associated with fivefold higher numbers of OMVs recovered from xylem sap of infected plants. The frequency of attachment of X. fastidiosa to xylem vessels was 20-fold lower in the presence of OMVs than in their absence. OMV production thus is a strategy used by X. fastidiosa cells to adjust attachment to surfaces in its transition from adhesive cells capable of insect transmission to an "exploratory" lifestyle for systemic spread within the plant host which would be hindered by attachment. OMV production may contribute to the movement of other bacteria in porous environments by similarly reducing their contact with environmental constituents.
International Nuclear Information System (INIS)
Chen, Faze; Song, Jinlong; Huang, Shuai; Xu, Wenji; Sun, Jing; Liu, Xin; Xu, Sihao; Xia, Guangqing; Yang, Dezheng
2016-01-01
Plasma hydrophilization is a general method to increase the surface free energy of materials. However, only a few works about plasma modification focus on the hydrophilization of tube inner and outer walls. In this paper, we realize simultaneous and long-lasting plasma hydrophilization on the inner and outer walls of polytetrafluoroethylene (PTFE) tubes by atmospheric pressure plasmas (APPs). Specifically, an Ar atmospheric pressure plasma jet (APPJ) is used to modify the PTFE tube’s outer wall and meanwhile to induce transferred He APP inside the PTFE tube to modify its inner wall surface. The optical emission spectrum (OES) shows that the plasmas contain many chemically active species, which are known as enablers for various applications. Water contact angle (WCA) measurements, x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) are used to characterize the plasma hydrophilization. Results demonstrate that the wettability of the tube walls are well improved due to the replacement of the surface fluorine by oxygen and the change of surface roughness. The obtained hydrophilicity decreases slowly during more than 180 d aging, indicating a long-lasting hydrophilization. The results presented here clearly demonstrate the great potential of transferring APPs for surface modification of the tube’s inner and outer walls simultaneously. (paper)
Eshghi, Azad; Pinne, Marija; Haake, David A; Zuerner, Richard L; Frank, Ami; Cameron, Caroline E
2012-03-01
Recent studies have revealed that bacterial protein methylation is a widespread post-translational modification that is required for virulence in selected pathogenic bacteria. In particular, altered methylation of outer-membrane proteins has been shown to modulate the effectiveness of the host immune response. In this study, 2D gel electrophoresis combined with MALDI-TOF MS identified a Leptospira interrogans serovar Copenhageni strain Fiocruz L1-130 protein, corresponding to ORF LIC11848, which undergoes extensive and differential methylation of glutamic acid residues. Immunofluorescence microscopy implicated LIC11848 as a surface-exposed outer-membrane protein, prompting the designation OmpL32. Indirect immunofluorescence microscopy of golden Syrian hamster liver and kidney sections revealed expression of OmpL32 during colonization of these organs. Identification of methylated surface-exposed outer-membrane proteins, such as OmpL32, provides a foundation for delineating the role of this post-translational modification in leptospiral virulence.
On the geodesic incompleteness of spacetimes containing marginally (outer) trapped surfaces
International Nuclear Information System (INIS)
Costa e Silva, I P
2012-01-01
In a recent paper, Eichmair et al (2012 arXiv:1204.0278v1) have proved a Gannon–Lee-type singularity theorem based on the existence of marginally outer trapped surfaces (MOTS) on noncompact initial data sets for globally hyperbolic spacetimes. A natural question is whether the corresponding incomplete geodesics could still be complete in a possible non-globally hyperbolic extension of spacetime. In this paper, some variants of their result are given with weaker causality assumptions, thus suggesting that the answer is generically negative, at least if the putative extension has no closed timelike curves. We consider first marginally trapped surfaces (MTS) in chronological spacetimes, introducing the natural notion of a generic MTS, a notion also applicable to MOTS. In particular, a Hawking–Penrose-type singularity theorem is proven in chronological spacetimes with dimension n ⩾ 3 containing a generic MTS. Such surfaces naturally arise as cross-sections of quasi-local generalizations of black hole horizons, such as dynamical and trapping horizons, and we discuss some natural conditions which ensure the existence of MTS in initial data sets. Nevertheless, much of the more recent literature has focused on MOTS rather than MTS as quasi-local substitutes for the description of black holes, as they are arguably more natural and easier to handle in a number of situations. It is therefore pertinent to ask to what extent one can deduce the existence of singularities in the presence of MOTS alone. We address this issue and show that singularities indeed arise in the presence of generic MOTS, but under slightly stronger causal conditions than those in the case of MTS (specifically, for causally simple spacetimes). On the other hand, we show that with additional conditions on the MOTS itself, namely that it is either the boundary of a compact spatial region, or strictly stable in a suitable sense, a Penrose–Hawking-type singularity theorem can still be established for
Mesoscale model response to random, surface-based perturbations — A sea-breeze experiment
Garratt, J. R.; Pielke, R. A.; Miller, W. F.; Lee, T. J.
1990-09-01
The introduction into a mesoscale model of random (in space) variations in roughness length, or random (in space and time) surface perturbations of temperature and friction velocity, produces a measurable, but barely significant, response in the simulated flow dynamics of the lower atmosphere. The perturbations are an attempt to include the effects of sub-grid variability into the ensemble-mean parameterization schemes used in many numerical models. Their magnitude is set in our experiments by appeal to real-world observations of the spatial variations in roughness length and daytime surface temperature over the land on horizontal scales of one to several tens of kilometers. With sea-breeze simulations, comparisons of a number of realizations forced by roughness-length and surface-temperature perturbations with the standard simulation reveal no significant change in ensemble mean statistics, and only small changes in the sea-breeze vertical velocity. Changes in the updraft velocity for individual runs, of up to several cms-1 (compared to a mean of 14 cms-1), are directly the result of prefrontal temperature changes of 0.1 to 0.2K, produced by the random surface forcing. The correlation and magnitude of the changes are entirely consistent with a gravity-current interpretation of the sea breeze.
Rapid outer-surface protein C DNA tattoo vaccination protects against Borrelia afzelii infection.
Wagemakers, A; Mason, L M K; Oei, A; de Wever, B; van der Poll, T; Bins, A D; Hovius, J W R
2014-12-01
Borrelia afzelii is the predominant Borrelia species causing Lyme borreliosis in Europe. Currently there is no human vaccine against Lyme borreliosis, and most research focuses on recombinant protein vaccines against Borrelia burgdorferi sensu stricto. DNA tattooing is a novel vaccination method that can be applied in a rapid vaccination schedule. We vaccinated C3H/HeN mice with B. afzelii strain PKo OspC (outer-surface protein C) using a codon-optimized DNA vaccine tattoo and compared this with recombinant protein vaccination in a 0-2-4 week vaccination schedule. We also assessed protection by DNA tattoo in a 0-3-6 day schedule. DNA tattoo and recombinant OspC vaccination induced comparable total IgG responses, with a lower IgG1/IgG2a ratio after DNA tattoo. Two weeks after syringe-challenge with 5 × 10(5) B. afzelii spirochetes most vaccinated mice had negative B. afzelii tissue DNA loads and all were culture negative. Furthermore, DNA tattoo vaccination in a 0-3-6 day regimen also resulted in negative Borrelia loads and cultures after challenge. To conclude, DNA vaccination by tattoo was fully protective against B. afzelii challenge in mice in a rapid vaccination protocol, and induces a favorable humoral immunity compared to recombinant protein vaccination. Rapid DNA tattoo is a promising vaccination strategy against spirochetes.
Directory of Open Access Journals (Sweden)
Girish Neelakanta
2007-03-01
Full Text Available Survival of Borrelia burgdorferi in ticks and mammals is facilitated, at least in part, by the selective expression of lipoproteins. Outer surface protein (Osp A participates in spirochete adherence to the tick gut. As ospB is expressed on a bicistronic operon with ospA, we have now investigated the role of OspB by generating an OspB-deficient B. burgdorferi and examining its phenotype throughout the spirochete life cycle. Similar to wild-type isolates, the OspB-deficient B. burgdorferi were able to readily infect and persist in mice. OspB-deficient B. burgdorferi were capable of migrating to the feeding ticks but had an impaired ability to adhere to the tick gut and survive within the vector. Furthermore, the OspB-deficient B. burgdorferi bound poorly to tick gut extracts. The complementation of the OspB-deficient spirochete in trans, with a wild-type copy of ospB gene, restored its ability to bind tick gut. Taken together, these data suggest that OspB has an important role within Ixodes scapularis and that B. burgdorferi relies upon multiple genes to efficiently persist in ticks.
Sedimentology and geochemistry of surface sediments, outer continental shelf, southern Bering Sea
Gardner, J.V.; Dean, W.E.; Vallier, T.L.
1980-01-01
Islands and the outer continental shelf and slope, indicates that Holocene sediment dynamics cannot be used to explain the observed distribution of surface sediment derived from the Aleutian Islands. We suggest that this pattern is relict and resulted from sediment dynamics during lower sea levels of the Pleistocene. ?? 1980.
DEFF Research Database (Denmark)
Ruiz-Ramos, M.; Ferrise, Roberto; Rodríguez, A
2018-01-01
type were analysed by constructing response surfaces, which we termed, in accordance with their specific purpose, adaptation response surfaces (ARSs). These were created to assess the effect of adaptations through a range of plausible P, T and [CO2] perturbations. The results indicated that impacts....... However, a single sI was sufficient to develop a high adaptation potential, including options mainly based on spring wheat, current cycle duration and early sowing date. Depending on local environment (e.g. soil type), many of these adaptations can maintain current yield levels under moderate changes in T...
Null-polygonal minimal surfaces in AdS4 from perturbed W minimal models
International Nuclear Information System (INIS)
Hatsuda, Yasuyuki; Ito, Katsushi; Satoh, Yuji
2012-11-01
We study the null-polygonal minimal surfaces in AdS 4 , which correspond to the gluon scattering amplitudes/Wilson loops in N=4 super Yang-Mills theory at strong coupling. The area of the minimal surfaces with n cusps is characterized by the thermodynamic Bethe ansatz (TBA) integral equations or the Y-system of the homogeneous sine-Gordon model, which is regarded as the SU(n-4) 4 /U(1) n-5 generalized parafermion theory perturbed by the weight-zero adjoint operators. Based on the relation to the TBA systems of the perturbed W minimal models, we solve the TBA equations by using the conformal perturbation theory, and obtain the analytic expansion of the remainder function around the UV/regular-polygonal limit for n = 6 and 7. We compare the rescaled remainder function for n=6 with the two-loop one, to observe that they are close to each other similarly to the AdS 3 case.
Null-polygonal minimal surfaces in AdS{sub 4} from perturbed W minimal models
Energy Technology Data Exchange (ETDEWEB)
Hatsuda, Yasuyuki [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ito, Katsushi [Tokyo Institute of Technology (Japan). Dept. of Physics; Satoh, Yuji [Tsukuba Univ., Sakura, Ibaraki (Japan). Inst. of Physics
2012-11-15
We study the null-polygonal minimal surfaces in AdS{sub 4}, which correspond to the gluon scattering amplitudes/Wilson loops in N=4 super Yang-Mills theory at strong coupling. The area of the minimal surfaces with n cusps is characterized by the thermodynamic Bethe ansatz (TBA) integral equations or the Y-system of the homogeneous sine-Gordon model, which is regarded as the SU(n-4){sub 4}/U(1){sup n-5} generalized parafermion theory perturbed by the weight-zero adjoint operators. Based on the relation to the TBA systems of the perturbed W minimal models, we solve the TBA equations by using the conformal perturbation theory, and obtain the analytic expansion of the remainder function around the UV/regular-polygonal limit for n = 6 and 7. We compare the rescaled remainder function for n=6 with the two-loop one, to observe that they are close to each other similarly to the AdS{sub 3} case.
Laboratory Studies of Ethane Ice Relevant to Outer Solar System Surfaces
Moore, Marla H.; Hudson, Reggie; Raines, Lily
2009-01-01
Oort Cloud comets, as well as TNOs Makemake (2045 FYg), Quaoar, and Pluto, are known to contain ethane. However, even though this molecule is found on several outer Solar System objects relatively little information is available about its amorphous and crystalline phases. In new experiments, we have prepared ethane ices at temperatures applicable to the outer Solar System, and have heated and ion-irradiated these ices to study phase changes and ethane's radiation chemistry using mid-IR spectroscopy (2.2 - 16.6 microns). Included in our work is the meta-stable phase that exists at 35 - 55 K. These results, including newly obtained optical constants, are relevant to ground-based observational campaigns, the New Horizons mission, and supporting laboratory work. An improved understanding of solid-phase ethane may contribute to future searches for this and other hydrocarbons in the outer Solar System.
Nawasreh, Zakariya; Failla, Mathew; Marmon, Adam; Logerstedt, David; Snyder-Mackler, Lynn
2018-05-23
Performing physical activities on a compliant surface alters joint kinematics and increases joints stiffness. However, the effect of compliant surface on joint kinematics after ACL-rupture is yet unknown. To compare the effects of mechanical perturbation training with a compliant surface to manual perturbation training on joint kinematics after ACL-rupture. Sixteen level I/II athletes with ACL-rupture participated in this preliminary study. Eight patients received mechanical perturbation with compliant surface (Mechanical) and 8 patients received manual perturbation training (Manual). Patients completed standard gait analysis before (Pre) and after (Post) training. Significant group-by-time interactions were found for knee flexion angle at initial contact (IC) and peak knee flexion (PKF) (pMechanical:27.68+4.08°, p = 0.011), hip rotation angle at PKE (Manual:-3.40+4.78°, Mechanical:5.43+4.78°, p Mechanical:0.55+2.23°, p = 0.039). Main effects of time were found for hip adduction angle at PKE (Pre:6.98+4.48°, Post:8.41+4.91°, p = 0.04), knee adduction angle at IC (Pre:-2.90+3.50°, Post:-0.62+2.58°, p = 0.03), ankle adduction angle at IC (Pre:2.16+3.54, Post:3.8+3.68, p = 0.008), and ankle flexion angle at PKF (Pre:-4.55+2.77°, Post:-2.39+3.48°, p = 0.01). Training on a compliant surface induces different effects on joint kinematics compared to manual perturbation training after ACL-rupture. Manual perturbation improved hip alignment and increased knee flexion angles, while mechanical training decreased knee flexion angles throughout the stance phase. Administering training on a compliant surface after ACL-rupture may help improving dynamic knee stability, however, long-term effects on knee health needs to be determined. Copyright © 2018 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Sauer, G.
1999-01-01
A method for computing the temperatures of a fluid flowing through a pipe on the basis of temperatures recorded at the pipe's outer surface is presented. The heat conduction in the pipe wall is described by one-dimensional heat conduction elements. Heat transfer between fluid, pipe and surrounding is allowed for. The equation system resulting from the standard finite element discretization is reformulated to enable the computation of temperature events preceding the recorded temperature in time. It is shown that the method can be used to identify the actual fluid temperature from temperature data obtained only at the outer surface of the pipe. The temperatures in the pipe wall are computed with good accuracy even in the case of a severe thermal shock. (orig.) [de
Detection of surface deformation and ionospheric perturbation by the North Korea nuclear test
Park, S. C.; Lee, W. J.; Sohn, D. H.; Lee, D. K.; Jung, H. S.
2017-12-01
We used remote sensing data to detect the changes on surface and ionosphere due to the North Korea nuclear test. To analyze the surface deformation before and after the 6th North Korea (NK) nuclear test, we used Satellite Aperture Radar (SAR) images. It was reported that there were some surface deformation with about 10 cm by the 4th test (Wei, 2017) and the 5th test (Jo, 2017) using Interferometric SAR (InSAR) technique. However we could not obtain surface deformation by the 6th test using InSAR with Advanced Land Observation Satellite 2 (ALOS-2) data because of low coherence in the area close to the epicenter. Although the low coherence can be occurred due to several reasons, the main reason may be large deformation in this particular case. Therefore we applied pixel offset method to measure the amount of surface deformation in the area with low coherence. Pixel offset method calculates the deformation in the directions along track and Line-of-Sight (LOS) using cross correlation of intensity of two SAR images before and after the event for a pixel and is used frequently to obtain large deformation of glacier (e.g. Lee et al., 2015). Applying pixel offset method to the area of the 6th NK nuclear test, we obtained about 3 m surface deformation in maximum. It seems that the larger deformation occurs as the mountain slope is steeper.We then analyzed ionospheric perturbation using Global Navigation Satellite System (GNSS) data. If acoustic wave by a nuclear test goes up to the ionosphere and disturbs electron density, then the changes in slant total electron content (STEC) may be detected by GNSS satellites. STEC perturbation has been reported in the previous NK nuclear tests (e.g. Park et al., 2011). We analyzed the third order derivatives of STEC for 51 GNSS stations in South Korea and found that some perturbation were appeared at 4 stations about 20 40 minutes after the test.
Arai, Yuji; Moran, P B; Honeyman, B D; Davis, J A
2007-06-01
Np(V) surface speciation on hematite surfaces at pH 7-9 under pC2 = 10(-3.45) atm was investigated using X-ray absorption spectroscopy (XAS). In situ XAS analyses suggest that bis-carbonato inner-sphere and tris-carbonato outer-sphere ternary surface species coexist at the hematite-water interface at pH 7-8.8, and the fraction of outer-sphere species gradually increases from 27 to 54% with increasing pH from 7 to 8.8. The results suggest that the heretofore unknown Np(V)-carbonato ternary surface species may be important in predicting the fate and transport of Np(V) in the subsurface environment down gradient of high-level nuclear waste respositories.
Mass and heat transfer at the outer surface of helical coils under single and two phase flow
International Nuclear Information System (INIS)
Abdel-Aziz, M.H.; Nirdosh, I.; Sedahmed, G.H.
2016-01-01
Highlights: • The work aims to develop reactors which need rapid temperature control. • Mass and heat transfer at the outer surface of helical coils was studied experimentally. • The experiments were conducted under gas sparing, single and two phase flow. • Variables were helical tube diameter, physical properties, and gas and liquid velocity. • Results verification in terms of natural convection and surface renewal mechanism was explained. - Abstract: The mass transfer behavior of the outer surface of vertical helical coil was studied by the electrochemical technique under single phase flow, gas sparging and two phase flow. Variables studied were helical tube diameter, physical properties of the solution, solution velocity and superficial gas velocity. The mass transfer data were correlated by dimensionless equations. Mass transfer enhancement ratio in case of two phase flow ranged from 1.1 to 4.9 compared to single phase flow. Implication of the results for the design and operation of helical coil reactors used to conduct L–S exothermic diffusion controlled reactions which need rapid temperature control were outlined. In this case the inner coil surface will act as a cooler while the outer surface will act a reaction surface. Immobilized enzyme catalyzed biochemical reactions where heat sensitive materials may be involved represent an example for the reactions which can employ the helical coil reactor. Also the importance of the results in the design of and operation of diffusion controlled membrane processes which employ helical coil membrane was noted. In view of the analogy between heat and mass transfer the possibility of using the results in the design and operation of helical coil heat exchangers was highlighted.
Energy Technology Data Exchange (ETDEWEB)
Zhou, Yun, E-mail: zhou.yun.x@gmail.com; Pollak, Eli, E-mail: eli.pollak@weizmann.ac.il [Chemical Physics Department, Weizmann Institute of Science, 76100 Rehovot (Israel); Miret-Artés, Salvador, E-mail: s.miret@iff.csic.es [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain)
2014-01-14
A second order classical perturbation theory is developed and applied to elastic atom corrugated surface scattering. The resulting theory accounts for experimentally observed asymmetry in the final angular distributions. These include qualitative features, such as reduction of the asymmetry in the intensity of the rainbow peaks with increased incidence energy as well as the asymmetry in the location of the rainbow peaks with respect to the specular scattering angle. The theory is especially applicable to “soft” corrugated potentials. Expressions for the angular distribution are derived for the exponential repulsive and Morse potential models. The theory is implemented numerically to a simplified model of the scattering of an Ar atom from a LiF(100) surface.
Sea surface wind perturbations over the Kashevarov Bank of the Okhotsk Sea. A satellite study
Energy Technology Data Exchange (ETDEWEB)
Tarkhova, T.I.; Permyakov, M.S.; Potalova, E.Yu.; Semykin, V.I. [V.I. Il' ichev Pacific Oceanological Institute of the Far Eastern Branch of Russian Academy of Sciences, Vladivostok (Russian Federation). Lab. of the Ocean and Atmosphere Interaction Studies
2011-07-01
Sea surface wind perturbations over sea surface temperature (SST) cold anomalies over the Kashevarov Bank (KB) of the Okhotsk Sea are analyzed using satellite (AMSR-E and QuikSCAT) data during the summerautumn period of 2006-2009. It is shown, that frequency of cases of wind speed decreasing over a cold spot in August- September reaches up to 67%. In the cold spot center SST cold anomalies reached 10.5 C and wind speed lowered down to {proportional_to}7ms {sup -1} relative its value on the periphery. The wind difference between a periphery and a centre of the cold spot is proportional to SST difference with the correlations 0.5 for daily satellite passes data, 0.66 for 3-day mean data and 0.9 for monthly ones. For all types of data the coefficient of proportionality consists of {proportional_to}0.3 {sup -1} on 1 C. (orig.)
Zhou, Yun; Pollak, Eli; Miret-Artés, Salvador
2014-01-14
A second order classical perturbation theory is developed and applied to elastic atom corrugated surface scattering. The resulting theory accounts for experimentally observed asymmetry in the final angular distributions. These include qualitative features, such as reduction of the asymmetry in the intensity of the rainbow peaks with increased incidence energy as well as the asymmetry in the location of the rainbow peaks with respect to the specular scattering angle. The theory is especially applicable to "soft" corrugated potentials. Expressions for the angular distribution are derived for the exponential repulsive and Morse potential models. The theory is implemented numerically to a simplified model of the scattering of an Ar atom from a LiF(100) surface.
Selective association of outer surface lipoproteins with the lipid rafts of Borrelia burgdorferi.
Toledo, Alvaro; Crowley, Jameson T; Coleman, James L; LaRocca, Timothy J; Chiantia, Salvatore; London, Erwin; Benach, Jorge L
2014-03-11
Borrelia burgdorferi contains unique cholesterol-glycolipid-rich lipid rafts that are associated with lipoproteins. These complexes suggest the existence of macromolecular structures that have not been reported for prokaryotes. Outer surface lipoproteins OspA, OspB, and OspC were studied for their participation in the formation of lipid rafts. Single-gene deletion mutants with deletions of ospA, ospB, and ospC and a spontaneous gene mutant, strain B313, which does not express OspA and OspB, were used to establish their structural roles in the lipid rafts. All mutant strains used in this study produced detergent-resistant membranes, a common characteristic of lipid rafts, and had similar lipid and protein slot blot profiles. Lipoproteins OspA and OspB but not OspC were shown to be associated with lipid rafts by transmission electron microscopy. When the ability to form lipid rafts in live B. burgdorferi spirochetes was measured by fluorescence resonance energy transfer (FRET), strain B313 showed a statistically significant lower level of segregation into ordered and disordered membrane domains than did the wild-type and the other single-deletion mutants. The transformation of a B313 strain with a shuttle plasmid containing ospA restored the phenotype shared by the wild type and the single-deletion mutants, demonstrating that OspA and OspB have redundant functions. In contrast, a transformed B313 overexpressing OspC neither rescued the FRET nor colocalized with the lipid rafts. Because these lipoproteins are expressed at different stages of the life cycle of B. burgdorferi, their selective association is likely to have an important role in the structure of prokaryotic lipid rafts and in the organism's adaptation to changing environments. IMPORTANCE Lipid rafts are cholesterol-rich clusters within the membranes of cells. Lipid rafts contain proteins that have functions in sensing the cell environment and transmitting signals. Although selective proteins are present in
Dosimetric perturbations of a lead shield for surface and interstitial high-dose-rate brachytherapy
International Nuclear Information System (INIS)
Candela-Juan, Cristian; Granero, Domingo; Vijande, Javier; Ballester, Facundo; Perez-Calatayud, Jose; Rivard, Mark J
2014-01-01
In surface and interstitial high-dose-rate brachytherapy with either 60 Co, 192 Ir, or 169 Yb sources, some radiosensitive organs near the surface may be exposed to high absorbed doses. This may be reduced by covering the implants with a lead shield on the body surface, which results in dosimetric perturbations. Monte Carlo simulations in Geant4 were performed for the three radionuclides placed at a single dwell position. Four different shield thicknesses (0, 3, 6, and 10 mm) and three different source depths (0, 5, and 10 mm) in water were considered, with the lead shield placed at the phantom surface. Backscatter dose enhancement and transmission data were obtained for the lead shields. Results were corrected to account for a realistic clinical case with multiple dwell positions. The range of the high backscatter dose enhancement in water is 3 mm for 60 Co and 1 mm for both 192 Ir and 169 Yb. Transmission data for 60 Co and 192 Ir are smaller than those reported by Papagiannis et al (2008 Med. Phys. 35 4898–4906) for brachytherapy facility shielding; for 169 Yb, the difference is negligible. In conclusion, the backscatter overdose produced by the lead shield can be avoided by just adding a few millimetres of bolus. Transmission data provided in this work as a function of lead thickness can be used to estimate healthy organ equivalent dose saving. Use of a lead shield is justified. (paper)
International Nuclear Information System (INIS)
Evans, R.; Kumaravadivel, R.
1976-01-01
A simple scheme for determining the ion density profile and the surface tension of a liquid metal is described. Assuming that the interaction between metallic pseudo-ions is of the form introduced by Evans, an approximate expression for the excess free energy of the system is derived using the thermodynamic perturbation theory of Weeks, Chandler and Anderson. This excess free energy is then minimized with respect to a parameter which specifies the ion density profile, and the surface tension is given directly. From a consideration of the dependence of the interionic forces on the electron density it is predicted that the ions should take up a very steep density profile at the liquid metal surface. This behaviour is contrasted with that to be expected for rare-gas fluids in which the interatomic forces are density-independent. The values of the surface tension calculated for liquid Na, K and Al from a simplified version of the theory are in reasonable agreement with experiment. (author)
A Miniaturized Seismometer for Surface Measurements in the Outer Solar System
Banerdt, W. B.; Pike, W. T.
2001-01-01
Seismology is a powerful tool for investigating the inner structure and dynamic processes of a planetary body. The interior structure information derived from seismic measurements is complementary to other methods of probing the subsurface (such as gravity and electromagnetics), both in terms of spatial and depth resolution and the relevant types of material properties being sensed. The propagation of seismic waves is sensitive to composition (via density and elastic parameters), temperature (via attenuation) and physical state (solid vs. liquid). In addition, the seismicity (level and distribution in space and time of seismic activity) provides information on the impact flux and tectonic forces currently active within the body. The major satellites of the outer solar system provide obvious targets for seismic investigations. In addition, small bodies, such as asteroids and comets, can also benefit from seismic measurements. We have developed an extremely small, lightweight, low-power seismometer for planetary applications which is ideally suited for use in the outer solar system. This instrument has previously been proposed and selected for use on a comet (on the Rosetta Lander, subsequently deselected for programmatic reasons) and Mars (on the NetLander mission). Additional information is contained in the original extended abstract.
Directory of Open Access Journals (Sweden)
Kelly P Nevin
Full Text Available The mechanisms by which Geobacter sulfurreducens transfers electrons through relatively thick (>50 microm biofilms to electrodes acting as a sole electron acceptor were investigated. Biofilms of Geobacter sulfurreducens were grown either in flow-through systems with graphite anodes as the electron acceptor or on the same graphite surface, but with fumarate as the sole electron acceptor. Fumarate-grown biofilms were not immediately capable of significant current production, suggesting substantial physiological differences from current-producing biofilms. Microarray analysis revealed 13 genes in current-harvesting biofilms that had significantly higher transcript levels. The greatest increases were for pilA, the gene immediately downstream of pilA, and the genes for two outer c-type membrane cytochromes, OmcB and OmcZ. Down-regulated genes included the genes for the outer-membrane c-type cytochromes, OmcS and OmcT. Results of quantitative RT-PCR of gene transcript levels during biofilm growth were consistent with microarray results. OmcZ and the outer-surface c-type cytochrome, OmcE, were more abundant and OmcS was less abundant in current-harvesting cells. Strains in which pilA, the gene immediately downstream from pilA, omcB, omcS, omcE, or omcZ was deleted demonstrated that only deletion of pilA or omcZ severely inhibited current production and biofilm formation in current-harvesting mode. In contrast, these gene deletions had no impact on biofilm formation on graphite surfaces when fumarate served as the electron acceptor. These results suggest that biofilms grown harvesting current are specifically poised for electron transfer to electrodes and that, in addition to pili, OmcZ is a key component in electron transfer through differentiated G. sulfurreducens biofilms to electrodes.
Thermal analysis of dry eye subjects and the thermal impulse perturbation model of ocular surface.
Zhang, Aizhong; Maki, Kara L; Salahura, Gheorghe; Kottaiyan, Ranjini; Yoon, Geunyoung; Hindman, Holly B; Aquavella, James V; Zavislan, James M
2015-03-01
In this study, we explore the usage of ocular surface temperature (OST) decay patterns to distinguished between dry eye patients with aqueous deficient dry eye (ADDE) and meibomian gland dysfunction (MGD). The OST profiles of 20 dry eye subjects were measured by a long-wave infrared thermal camera in a standardized environment (24 °C, and relative humidity (RH) 40%). The subjects were instructed to blink every 5 s after 20 ∼ 25 min acclimation. Exponential decay curves were fit to the average temperature within a region of the central cornea. We find the MGD subjects have both a higher initial temperature (p model, referred to as the thermal impulse perturbation (TIP) model. We conclude that long-wave-infrared thermal imaging is a plausible tool in assisting with the classification of dry eye patient. Copyright © 2015 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Ferreira, L.C.S.; Almeida, D.F. de
1987-01-01
Surface proteins of Escherichia coli K12 were identified by radiolabelling using 1,3,4,6 - tatrachloro, 3-alpha, 6-alpha - diphenylgycoluryl (Iodo-Gen) and 131 I. Labelled proteins were localized in the outer membrane of the cells. Using this technique it has been possible to observe technique it has been possible to observe that the eletrophoretic pattern of surface proteins changes according to the growth phases in culture. Radiolabelling of E.coli cells inculbated at 42 0 C showed that the syntheses of two surface proteins were temperature-inducible. At least one such protein may be involved in the process of cell division in E.coli K12. (author) [pt
Energy Technology Data Exchange (ETDEWEB)
Ferreira, L C.S.; Almeida, D.F. de
1987-12-01
Surface proteins of Escherichia coli K12 were identified by radiolabelling using 1,3,4,6 - tatrachloro, 3-alpha, 6-alpha - diphenylgycoluryl (Iodo-Gen) and /sup 131/I. Labelled proteins were localized in the outer membrane of the cells. Using this technique it has been possible to observe technique it has been possible to observe that the eletrophoretic pattern of surface proteins changes according to the growth phases in culture. Radiolabelling of E.coli cells inculbated at 42/sup 0/C showed that the syntheses of two surface proteins were temperature-inducible. At least one such protein may be involved in the process of cell division in E.coli K12.
Directory of Open Access Journals (Sweden)
McClafferty Heather
2005-01-01
Full Text Available Abstract Background Chlamydial bacteria are obligate intracellular pathogens containing a cysteine-rich porin (Major Outer Membrane Protein, MOMP with important structural and, in many species, immunity-related roles. MOMP forms extensive disulphide bonds with other chlamydial proteins, and is difficult to purify. Leaderless, recombinant MOMPs expressed in E. coli have yet to be refolded from inclusion bodies, and although leadered MOMP can be expressed in E. coli cells, it often misfolds and aggregates. We aimed to improve the surface expression of correctly folded MOMP to investigate the membrane topology of the protein, and provide a system to display native and modified MOMP epitopes. Results C. trachomatis MOMP was expressed on the surface of E. coli cells (including "porin knockout" cells after optimizing leader sequence, temperature and medium composition, and the protein was functionally reconstituted at the single-channel level to confirm it was folded correctly. Recombinant MOMP formed oligomers even in the absence of its 9 cysteine residues, and the unmodified protein also formed inter- and intra-subunit disulphide bonds. Its topology was modeled as a (16-stranded β-barrel, and specific structural predictions were tested by removing each of the four putative surface-exposed loops corresponding to highly immunogenic variable sequence (VS domains, and one or two of the putative transmembrane strands. The deletion of predicted external loops did not prevent folding and incorporation of MOMP into the E. coli outer membrane, in contrast to the removal of predicted transmembrane strands. Conclusions C. trachomatis MOMP was functionally expressed on the surface of E. coli cells under newly optimized conditions. Tests of its predicted membrane topology were consistent with β-barrel oligomers in which major immunogenic regions are displayed on surface-exposed loops. Functional surface expression, coupled with improved understanding of MOMP
International Nuclear Information System (INIS)
Ohta, Takahiro; Kamo, Kazuhiko; Asada, Seiji; Terasaki, Toshio
2009-01-01
The new process called L-SIP (outer surface irradiated Laser Stress Improvement Process) is developed to improve the tensile residual stress of the inner surface near the butt welded joints of pipes in the compression stress. The temperature gradient occurs in the thickness of pipes in heating the outer surface rapidly by laser beam. By the thermal expansion difference between the inner surface and the outer surface, the compression stress occurs near the inner surface of pipes. In this paper, the theoretical equation for the temperature distributions of pipes heated by moving rectangular Gauss distribution heat source on the outer surface is derived. The temperature histories of pipes calculated by theoretical equation agree well with FEM analysis results. According to the theoretical equation, the controlling parameters of temperature distributions and histories are q/2a y , vh, a x /h and a y /h, where q is total heat input, a y is heat source length in the axial direction, a x is Gaussian radius of heat source in the hoop direction, ν is moving velocity, and h is thickness of the pipe. The essential variables for L-SIP, which are defined on the basis of the measured temperature histories on the outer surface of the pipe, are Tmax, F 0 =kτ 0 /h 2 , vh, W Q and L Q , where Tmax is maximum temperature on the monitor point of the outer surface, k is thermal diffusivity coefficient, τ 0 is the temperature rise time from 100degC to maximum temperature on the monitor point of the outer surface, W Q is τ 0 x ν, and L Q is the uniform temperature length in the axial direction. It is verified that the essential variables for L-SIP match the controlling parameters by the theoretical equation. (author)
Albert, A D; Watts, A; Spooner, P; Groebner, G; Young, J; Yeagle, P L
1997-08-14
Structural information on mammalian integral membrane proteins is scarce. As part of work on an alternative approach to the structure of bovine rhodopsin, a method was devised to obtain an intramolecular distance between two specific sites on rhodopsin while in the rod outer segment disk membrane. In this report, the distance between the rhodopsin kinase phosphorylation site(s) on the carboxyl terminal and the top of the third transmembrane helix was measured on native rhodopsin. Rhodopsin was labeled with a nuclear spin label (31P) by limited phosphorylation with rhodopsin kinase. Major phosphorylation occurs at serines 343 and 338 on the carboxyl terminal. The phosphorylated rhodopsin was then specifically labeled on cysteine 140 with an electron spin label. Magic angle spinning 31P-nuclear magnetic resonance revealed the resonance arising from the phosphorylated protein. The enhancement of the transverse relaxation of this resonance by the paramagnetic spin label was observed. The strength of this perturbation was used to determine the through-space distance between the phosphorylation site(s) and the spin label position. A distance of 18 +/- 3 A was obtained.
Sea surface wind perturbations over the Kashevarov Bank of the Okhotsk Sea: a satellite study
Directory of Open Access Journals (Sweden)
T. I. Tarkhova
2011-02-01
Full Text Available Sea surface wind perturbations over sea surface temperature (SST cold anomalies over the Kashevarov Bank (KB of the Okhotsk Sea are analyzed using satellite (AMSR-E and QuikSCAT data during the summer-autumn period of 2006–2009. It is shown, that frequency of cases of wind speed decreasing over a cold spot in August–September reaches up to 67%. In the cold spot center SST cold anomalies reached 10.5 °C and wind speed lowered down to ~7 m s−1 relative its value on the periphery. The wind difference between a periphery and a centre of the cold spot is proportional to SST difference with the correlations 0.5 for daily satellite passes data, 0.66 for 3-day mean data and 0.9 for monthly ones. For all types of data the coefficient of proportionality consists of ~0.3 m s−1 on 1 °C.
Fabrication of cell outer membrane mimetic polymer brush on polysulfone surface via RAFT technique
International Nuclear Information System (INIS)
Ma Qian; Zhang Hui; Zhao Jiang; Gong Yongkuan
2012-01-01
Highlights: ► Cell membrane mimetic antifouling polymer brush was grown on polysulfone surface. ► Graft density and polymerization degree were calculated from XPS results. ► Water contact angle measurements showed an extremely hydrophilic surface. ► Platelet adhesion and protein adsorption results suggested excellent antifouling ability. - Abstract: Cell membrane mimetic antifouling polymer brush was grown on polysulfone (PSF) membrane by surface-induced reversible addition–fragmentation chain transfer (RAFT) polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC). The RAFT agent immobilized PSF substrate was prepared by successive chloromethylation, amination with ethylenediamine (EDA) and amidation of the amine group of grafted EDA with the carboxylic group of 4-cyanopentanoic acid dithiobenzoate (CPAD). The surface RAFT polymerization of MPC was initiated in aqueous solution by 4,4′-azobis-4-cyanopentanoic acid (ACPA). The formation of PMPC brush coating is evidenced by X-ray photoelectron spectroscopy and water contact angle measurements. The degree of polymerization of PMPC and the polymer grafting density were calculated from the high resolution XPS spectra. The platelet adhesion and protein adsorption results showed that the PMPC-grafted PSF surface has excellent antifouling ability to resist platelet adhesion completely and suppress protein adsorption significantly. This biomimetic and bio-friendly surface RAFT polymerization strategy could be promising for a variety of biomedical applications.
OPUS - Outer Planets Unified Search with Enhanced Surface Geometry Parameters - Not Just for Rings
Gordon, Mitchell; Showalter, Mark Robert; Ballard, Lisa; Tiscareno, Matthew S.; Heather, Neil
2016-10-01
In recent years, with the massive influx of data into the PDS from a wide array of missions and instruments, finding the precise data you need has been an ongoing challenge. For remote sensing data obtained from Jupiter to Pluto, that challenge is being addressed by the Outer Planets Unified Search, more commonly known as OPUS.OPUS is a powerful search tool available at the PDS Ring-Moon Systems Node (RMS) - formerly the PDS Rings Node. While OPUS was originally designed with ring data in mind, its capabilities have been extended to include all of the targets within an instrument's field of view. OPUS provides preview images of search results, and produces a zip file for easy download of selected products, including a table of user specified metadata. For Cassini ISS and Voyager ISS we have generated and include calibrated versions of every image.Currently OPUS supports data returned by Cassini ISS, UVIS, VIMS, and CIRS (Saturn data through June 2010), New Horizons Jupiter LORRI, Galileo SSI, Voyager ISS and IRIS, and Hubble (ACS, WFC3 and WFPC2).At the RMS Node, we have developed and incorporated into OPUS detailed geometric metadata, based on the most recent SPICE kernels, for all of the bodies in the Cassini Saturn observations. This extensive set of geometric metadata is unique to the RMS Node and enables search constraints such as latitudes and longitudes (Saturn, Titan, and icy satellites), viewing and illumination geometry (phase, incidence and emission angles), and distances and resolution.Our near term plans include adding the full set of Cassini CIRS Saturn data (with enhanced geometry), New Horizons MVIC Jupiter encounter images, New Horizons LORRI and MVIC Pluto data, HST STIS observations, and Cassini and Voyager ring occultations. We also plan to develop enhanced geometric metadata for the New Horizons LORRI and MVIC instruments for both the Jupiter and the Pluto encounters.OPUS: http://pds-rings.seti.org/search/
The outer disks of early-type galaxies. I. Surface-brightness profiles of barred galaxies
Erwin, Peter; Pohlen, Michael; Beckman, John E.
We present a study of 66 barred, early-type (S0-Sb) disk galaxies, focused on the disk surface brightness profile outside the bar region, with the aim of throwing light on the nature of Freeman type I and II profiles, their origins, and their possible relation to disk truncations. This paper
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N. E. Rosário
2013-03-01
. This highlights the need to improve modelling of the regional smoke plume in order to enhance the accuracy of the radiative energy budget. An aerosol optical model based on the mean intensive properties of smoke from the southern part of the Amazon basin produced a radiative flux perturbation efficiency (RFPE of −158 Wm−2/AOD550 nm at noon. This value falls between −154 Wm−2/AOD550 nm and −187 Wm−2/AOD550 nm, the range obtained when spatially varying optical models were considered. The 24 h average surface radiative flux perturbation over the biomass burning season varied from −55 Wm−2 close to smoke sources in the southern part of the Amazon basin and cerrado to −10 Wm−2 in remote regions of the southeast Brazilian coast.
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A. I. Uvarov
2014-01-01
Full Text Available An analytical model of plastic deformation of a conical shell with the transformation of internal surface into outer one was developed with a use of the kinematic method. The shell material was assumed to be perfectly plastic. The theory of thin shells and the kinematic theorem of limit equilibrium were utilized in this work. Both geometric and physical nonlinearities were taken into account. Dependences for calculating radius of curvature of the intensive deformation zones, value of chain ring deformation and values of the deforming force as a function of axial displacement were determined. Analysis showed the possibility of using a conical shell to absorb energy with high efficiency. Obtained results could be used for calculation and selection of optimal parameters of the energy-absorbing elements in shock absorbers.
International Nuclear Information System (INIS)
Tanaka, Yasuhiro; Umemoto, Tadahiro
1988-01-01
Many techniques have been proposed as countermeasures for the External Stress Corrosion Cracking (ESCC) on austenitic stainless steel piping caused by sea salt particles. However, not one seems perfect. The method proposed here is an expansion of IHSI (Induction Heating Stress Improvement) which has been successfully implemented in many nuclear power plants as a remedy for Intergranular Stress Corrossion Cracking. The proposed method named EIHSI (External IHSI) can make the residual stress compressive on the outer surface of the piping components. In order to confirm the effectiveness of EIHSI, one series of tests were conducted on a weld joint between the pipe flange and the straight pipe. The measured residual stresses and also the results of the cracking test revealed that EIHSI is a superior method to suppress the ESCC. The outline of EIHSI and the verification tests are presented in this paper. (author)
Turbine airfoil with outer wall thickness indicators
Marra, John J; James, Allister W; Merrill, Gary B
2013-08-06
A turbine airfoil usable in a turbine engine and including a depth indicator for determining outer wall blade thickness. The airfoil may include an outer wall having a plurality of grooves in the outer surface of the outer wall. The grooves may have a depth that represents a desired outer surface and wall thickness of the outer wall. The material forming an outer surface of the outer wall may be removed to be flush with an innermost point in each groove, thereby reducing the wall thickness and increasing efficiency. The plurality of grooves may be positioned in a radially outer region of the airfoil proximate to the tip.
Environment on the Surfaces of the Drip Shield and Waste Package Outer Barrier
International Nuclear Information System (INIS)
T. Wolery
2005-01-01
This report provides supporting analysis of the conditions at which an aqueous solution can exist on the drip shield or waste package surfaces, including theoretical underpinning for the evolution of concentrated brines that could form by deliquescence or evaporation, and evaluation of the effects of acid-gas generation on brine composition. This analysis does not directly feed the total system performance assessment for the license application (TSPA-LA), but supports modeling and abstraction of the in-drift chemical environment (BSC 2004 [DIRS 169863]; BSC 2004 [DIRS 169860]). It also provides analyses that may support screening of features, events, and processes, and input for response to regulatory inquiries. This report emphasizes conditions of low relative humidity (RH) that, depending on temperature and chemical conditions, may be dry or may be associated with an aqueous phase containing concentrated electrolytes. Concentrated solutions at low RH may evolve by evaporative concentration of water that seeps into emplacement drifts, or by deliquescence of dust on the waste package or drip shield surfaces. The minimum RH for occurrence of aqueous conditions is calculated for various chemical systems based on current understanding of site geochemistry and equilibrium thermodynamics. The analysis makes use of known characteristics of Yucca Mountain waters and dust from existing tunnels, laboratory data, and relevant information from the technical literature and handbooks
Environment on the Surfaces of the Drip Shield and Waste Package Outer Barrier
Energy Technology Data Exchange (ETDEWEB)
T. Wolery
2005-02-22
This report provides supporting analysis of the conditions at which an aqueous solution can exist on the drip shield or waste package surfaces, including theoretical underpinning for the evolution of concentrated brines that could form by deliquescence or evaporation, and evaluation of the effects of acid-gas generation on brine composition. This analysis does not directly feed the total system performance assessment for the license application (TSPA-LA), but supports modeling and abstraction of the in-drift chemical environment (BSC 2004 [DIRS 169863]; BSC 2004 [DIRS 169860]). It also provides analyses that may support screening of features, events, and processes, and input for response to regulatory inquiries. This report emphasizes conditions of low relative humidity (RH) that, depending on temperature and chemical conditions, may be dry or may be associated with an aqueous phase containing concentrated electrolytes. Concentrated solutions at low RH may evolve by evaporative concentration of water that seeps into emplacement drifts, or by deliquescence of dust on the waste package or drip shield surfaces. The minimum RH for occurrence of aqueous conditions is calculated for various chemical systems based on current understanding of site geochemistry and equilibrium thermodynamics. The analysis makes use of known characteristics of Yucca Mountain waters and dust from existing tunnels, laboratory data, and relevant information from the technical literature and handbooks.
International Nuclear Information System (INIS)
Brocks, W.; Kuenecke, G.
1989-06-01
Continuing preceding investigations, a further elastic-plastic finite element analysis of a test vessel with a semi-elliptical axial outer surface crack has been performed. The variations of J and CTOD along the crack front and the stress state in the vicinity of the crack are presented. The applicability of analytical approaches to determine J is examined. The FE results are used to analyze the experimental data with respect to the validity of J-controlled crack growth. Local J R -curves of the surface flaw are compared with J R -curves of various specimens of different geometries. Again, it became evident that the local ductile crack growth and, especially, the developing 'canoe shape' of the surface crack cannot be described by a single resistance curve which is assumed to be a material property. A method described in a previous report to predict the ductile crack growth by using local J R -curves which depend on the triaxiality of the stress state did not result in a satisfactory outcome, in the present case. The presumed reasons will be discussed. (orig.) [de
Energy Technology Data Exchange (ETDEWEB)
Omar, W. [Department of Natural Resources and Chemical Engineering, Tafila Technical University, Tafila (Jordan); Ulrich, J. [FB Ingenieurwissenschaften, Institut fuer Verfahrenstechnik/TVT, Martin-Luther-Universitaet Halle-Wittenberg, Halle (Germany)
2006-08-15
The scaling problem in Multi Effect Distillation (MED) evaporators is investigated by the experimental measurement of the deposition rate under different operating conditions. The measurements are conducted in a batch vessel containing artificial seawater, which is allowed to contact the outer surface of a hot pipe under controlled temperature, salinity and pH. The rate of mass deposition is higher at elevated temperature. The salinity of the seawater also influences the scaling process - an increase in salinity from 47-59 g/L leads to an increase of 75.6 % in the deposition rate. Decreasing the pH value of seawater to 2.01 results in a complete inhibition of scaling, whereas the severity of the scaling increases in neutral and basic mediums. Polyacrylic acid is tested as an antifoulant and it was found that its presence in seawater reduces the scaling process. The nature of the heat transfer surface material also plays an important role in the scaling process. It is found experimentally that the rate of scaling is higher in the case of a Cu-Ni alloy as the surface material of the tube rather than stainless steel. (Abstract Copyright [2006], Wiley Periodicals, Inc.)
International Nuclear Information System (INIS)
Lambert, P.A.; Booth, B.R.
1982-01-01
The authors have investigated the exposure of the major outer membrane proteins on the cell surface by treating whole cells of P. aeruginosa with [ 125 I]lactoperoxidase. This reagent catalyses the iodination of tyrosine and histidine residues of proteins in the presence of hydrogen peroxide. It is too large to penetrate the outer membrane (Msub(r) 77500), therefore it is assumed to label only those proteins which have such residues exposed on the cell surface and has been applied to a number of Gram-negative organisms. It is found that F was the major labelled protein, D1 and/or D2 were less heavily labelled, and G was very faintly labelled. In addition, two proteins (Msub(r) 72500 and 38000) which did not appear to be major outer membrane proteins were labelled. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Kallinikos, N.; Isliker, H.; Vlahos, L.; Meletlidou, E. [Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece)
2014-06-15
An analytical description of magnetic islands is presented for the typical case of a single perturbation mode introduced to tokamak plasma equilibrium in the large aspect ratio approximation. Following the Hamiltonian structure directly in terms of toroidal coordinates, the well known integrability of this system is exploited, laying out a precise and practical way for determining the island topology features, as required in various applications, through an analytical and exact flux surface label.
Kallinikos, N.; Isliker, H.; Vlahos, L.; Meletlidou, E.
2014-06-01
An analytical description of magnetic islands is presented for the typical case of a single perturbation mode introduced to tokamak plasma equilibrium in the large aspect ratio approximation. Following the Hamiltonian structure directly in terms of toroidal coordinates, the well known integrability of this system is exploited, laying out a precise and practical way for determining the island topology features, as required in various applications, through an analytical and exact flux surface label.
International Nuclear Information System (INIS)
Kallinikos, N.; Isliker, H.; Vlahos, L.; Meletlidou, E.
2014-01-01
An analytical description of magnetic islands is presented for the typical case of a single perturbation mode introduced to tokamak plasma equilibrium in the large aspect ratio approximation. Following the Hamiltonian structure directly in terms of toroidal coordinates, the well known integrability of this system is exploited, laying out a precise and practical way for determining the island topology features, as required in various applications, through an analytical and exact flux surface label
International Nuclear Information System (INIS)
Kraenkel, R.A.; Pereira, J.G.; Manna, M.A.
1991-01-01
The (2+1)-dimensional Burgers equation is obtained as the equation of motion governing the surface perturbations of a shallow viscous fluid heated from below, provided the Rayleigh number of the system satisfy the condition R ≠ 30. A solution to this equation is explicity exhibited and it is argued that it describes the nonlinear evolution of a nearly one-dimensional kink. (author)
Directory of Open Access Journals (Sweden)
Matteo Maria Emiliano Metruccio
2016-06-01
Full Text Available Pseudomonas aeruginosa is a leading cause of human morbidity and mortality that often targets epithelial surfaces. Host immunocompromise, or the presence of indwelling medical devices, including contact lenses, can predispose to infection. While medical devices are known to accumulate bacterial biofilms, it is not well understood why resistant epithelial surfaces become susceptible to P. aeruginosa. Many bacteria, including P. aeruginosa, release Outer Membrane Vesicles (OMVs in response to stress that can fuse with host cells to alter their function. Here, we tested the hypothesis that mucosal fluid can trigger OMV release to compromise an epithelial barrier. This was tested using tear fluid and corneal epithelial cells in vitro and in vivo. After 1 h both human tear fluid, and the tear component lysozyme, greatly enhanced OMV release from P. aeruginosa strain PAO1 compared to PBS controls (~100 fold. TEM and SDS-PAGE showed tear fluid and lysozyme-induced OMVs were similar in size and protein composition, but differed from biofilm-harvested OMVs, the latter smaller with fewer proteins. Lysozyme-induced OMVs were cytotoxic to human corneal epithelial cells in vitro and murine corneal epithelium in vivo. OMV exposure in vivo enhanced Ly6G/C expression at the corneal surface, suggesting myeloid cell recruitment, and primed the cornea for bacterial adhesion (~4-fold, P < 0.01. Sonication disrupted OMVs retained cytotoxic activity, but did not promote adhesion, suggesting the latter required OMV-mediated events beyond cell killing. These data suggest that mucosal fluid induced P. aeruginosa OMVs could contribute to loss of epithelial barrier function during medical device-related infections.
Caine, Jennifer A; Lin, Yi-Pin; Kessler, Julie R; Sato, Hiromi; Leong, John M; Coburn, Jenifer
2017-12-01
Borrelia burgdorferi (Bb) is the causative agent of Lyme disease in the United States, a disease that can result in carditis, and chronic and debilitating arthritis and/or neurologic symptoms if left untreated. Bb survives in the midgut of the Ixodes scapularis tick, or within tissues of immunocompetent hosts. In the early stages of infection, the bacteria are present in the bloodstream where they must resist clearance by the innate immune system of the host. We have found a novel role for outer surface protein C (OspC) from B. burgdorferi and B. garinii in interactions with the complement component C4b and bloodstream survival in vivo. Our data show that OspC inhibits the classical and lectin complement pathways and competes with complement protein C2 for C4b binding. Resistance to complement is important for maintenance of the lifecycle of Bb, enabling survival of the pathogen within the host as well as in the midgut of a feeding tick when ospC expression is induced. © 2017 John Wiley & Sons Ltd.
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Krasnoshlykov Alexander
2017-01-01
Full Text Available Numerical analysis of thermal conditions of a lithium-ion battery using the software package ANSYS Electric and ANSYS Fluent has been carried out. Time dependence of the electrolyte temperature on the various heat exchange conditions on the outer surface has been obtained.
Energy Technology Data Exchange (ETDEWEB)
Hong, Youngjoon, E-mail: hongy@uic.edu; Nicholls, David P., E-mail: davidn@uic.edu
2017-02-01
The accurate numerical simulation of linear waves interacting with periodic layered media is a crucial capability in engineering applications. In this contribution we study the stable and high-order accurate numerical simulation of the interaction of linear, time-harmonic waves with a periodic, triply layered medium with irregular interfaces. In contrast with volumetric approaches, High-Order Perturbation of Surfaces (HOPS) algorithms are inexpensive interfacial methods which rapidly and recursively estimate scattering returns by perturbation of the interface shape. In comparison with Boundary Integral/Element Methods, the stable HOPS algorithm we describe here does not require specialized quadrature rules, periodization strategies, or the solution of dense non-symmetric positive definite linear systems. In addition, the algorithm is provably stable as opposed to other classical HOPS approaches. With numerical experiments we show the remarkable efficiency, fidelity, and accuracy one can achieve with an implementation of this algorithm.
Directory of Open Access Journals (Sweden)
G. H. Gudmundsson
2008-07-01
Full Text Available New analytical solutions describing the effects of small-amplitude perturbations in boundary data on flow in the shallow-ice-stream approximation are presented. These solutions are valid for a non-linear Weertman-type sliding law and for Newtonian ice rheology. Comparison is made with corresponding solutions of the shallow-ice-sheet approximation, and with solutions of the full Stokes equations. The shallow-ice-stream approximation is commonly used to describe large-scale ice stream flow over a weak bed, while the shallow-ice-sheet approximation forms the basis of most current large-scale ice sheet models. It is found that the shallow-ice-stream approximation overestimates the effects of bed topography perturbations on surface profile for wavelengths less than about 5 to 10 ice thicknesses, the exact number depending on values of surface slope and slip ratio. For high slip ratios, the shallow-ice-stream approximation gives a very simple description of the relationship between bed and surface topography, with the corresponding transfer amplitudes being close to unity for any given wavelength. The shallow-ice-stream estimates for the timescales that govern the transient response of ice streams to external perturbations are considerably more accurate than those based on the shallow-ice-sheet approximation. In particular, in contrast to the shallow-ice-sheet approximation, the shallow-ice-stream approximation correctly reproduces the short-wavelength limit of the kinematic phase speed given by solving a linearised version of the full Stokes system. In accordance with the full Stokes solutions, the shallow-ice-sheet approximation predicts surface fields to react weakly to spatial variations in basal slipperiness with wavelengths less than about 10 to 20 ice thicknesses.
Hennig, Anna; Bonfig, Katharina; Roitsch, Thomas; Warzecha, Heribert
2007-11-01
Bacterial lipoproteins play crucial roles in host-pathogen interactions and pathogenesis and are important targets for the immune system. A prominent example is the outer surface protein A (OspA) of Borrelia burgdorferi, which has been efficiently used as a vaccine for the prevention of Lyme disease. In a previous study, OspA could be produced in tobacco chloroplasts in a lipidated and immunogenic form. To further explore the potential of chloroplasts for the production of bacterial lipoproteins, the role of the N-terminal leader sequence was investigated. The amount of recombinant OspA could be increased up to ten-fold by the variation of the insertion site in the chloroplast genome. Analysis of OspA mutants revealed that replacement of the invariant cysteine residue as well as deletion of the leader sequence abolishes palmitolyation of OspA. Also, decoration of OspA with an N-terminal eukaryotic lipidation motif does not lead to palmitoylation in chloroplasts. Strikingly, the bacterial signal peptide of OspA efficiently targets the protein to thylakoids, and causes a mutant phenotype. Plants accumulating OspA at 10% total soluble protein could not grow without exogenously supplied sugars and rapidly died after transfer to soil under greenhouse conditions. The plants were found to be strongly affected in photosystem II, as revealed by the analyses of temporal and spatial dynamics of photosynthetic activity by chlorophyll fluorescence imaging. Thus, overexpression of OspA in chloroplasts is limited by its concentration-dependent interference with essential functions of chloroplastic membranes required for primary metabolism.
International Nuclear Information System (INIS)
Fraser, Wesley C.; Brown, Michael E.; Glass, Florian
2015-01-01
Here, we present additional photometry of targets observed as part of the Hubble Wide Field Camera 3 (WFC3) Test of Surfaces in the Outer Solar System. Twelve targets were re-observed with the WFC3 in the optical and NIR wavebands designed to complement those used during the first visit. Additionally, all of the observations originally presented by Fraser and Brown were reanalyzed through the same updated photometry pipeline. A re-analysis of the optical and NIR color distribution reveals a bifurcated optical color distribution and only two identifiable spectral classes, each of which occupies a broad range of colors and has correlated optical and NIR colors, in agreement with our previous findings. We report the detection of significant spectral variations on five targets which cannot be attributed to photometry errors, cosmic rays, point-spread function or sensitivity variations, or other image artifacts capable of explaining the magnitude of the variation. The spectrally variable objects are found to have a broad range of dynamical classes and absolute magnitudes, exhibit a broad range of apparent magnitude variations, and are found in both compositional classes. The spectrally variable objects with sufficiently accurate colors for spectral classification maintain their membership, belonging to the same class at both epochs. 2005 TV189 exhibits a sufficiently broad difference in color at the two epochs that span the full range of colors of the neutral class. This strongly argues that the neutral class is one single class with a broad range of colors, rather than the combination of multiple overlapping classes
International Nuclear Information System (INIS)
Schardt, A.W.; Behannon, K.W.; Lepping, R.P.; Carbary, J.F.; Eviatar, A.; Siscoe, G.L.
1984-01-01
Similarities between the Saturnian and terrestrial outer magnetosphere are examined. Saturn, like earth, has a fully developed magnetic tail, 80 to 100 RS in diameter. One major difference between the two outer magnetospheres is the hydrogen and nitrogen torus produced by Titan. This plasma is, in general, convected in the corotation direction at nearly the rigid corotation speed. Energies of magnetospheric particles extend to above 500 keV. In contrast, interplanetary protons and ions above 2 MeV have free access to the outer magnetosphere to distances well below the Stormer cutoff. This access presumably occurs through the magnetotail. In addition to the H+, H2+, and H3+ ions primarily of local origin, energetic He, C, N, and O ions are found with solar composition. Their flux can be substantially enhanced over that of interplanetary ions at energies of 0.2 to 0.4 MeV/nuc
International Nuclear Information System (INIS)
Alfaro, Pedro; Palavicini, Alessio; Wang, Chumin
2014-01-01
Based on the density functional perturbation theory (DFPT), infrared absorption spectra of porous silicon are calculated by using an ordered pore model, in which columns of silicon atoms are removed along the [001] direction and dangling bonds are initially saturated with hydrogen atoms. When these atoms on the pore surface are gradually replaced by oxygen ones, the ab-initio infrared absorption spectra reveal oxygen, hydroxyl, and coupled hydrogen–oxygen vibrational modes. In a parallel way, freestanding porous silicon samples were prepared by using electrochemical etching and they were further thermally oxidized in a dry oxygen ambient. Fourier transform infrared spectroscopy was used to investigate the surface modifications caused by oxygen adsorption. In particular, the predicted hydroxyl and oxygen bound to the silicon pore surface are confirmed. Finally, a global analysis of measured transmittance spectra has been performed by means of a combined DFPT and thin-film optics approach. - Highlights: • The density functional perturbation theory is used to study infrared absorption. • An ordered pore model is used to investigate the oxidation in porous silicon (PSi). • Infrared transmittance spectra of oxidized PSi freestanding samples are measured
Directory of Open Access Journals (Sweden)
Pranab Kanti Roy
2015-09-01
Full Text Available This work aimed at studying the effects of environmental temperature and surface emissivity parameter on the temperature distribution, efficiency and heat transfer rate of a conductive–radiative fin. The Homotopy Perturbation Method (HPM being one of the semi-numerical methods for highly nonlinear and inhomogeneous equations, the local temperature distribution efficiencies and heat transfer rates are obtained using HPM in which Newton–Raphson method is used for the insulated boundary condition. It is found that the results of the present works are in good agreement with results available in the literature.
Asymptotic behavior of monodromy singularly perturbed differential equations on a Riemann surface
Simpson, Carlos
1991-01-01
This book concerns the question of how the solution of a system of ODE's varies when the differential equation varies. The goal is to give nonzero asymptotic expansions for the solution in terms of a parameter expressing how some coefficients go to infinity. A particular classof families of equations is considered, where the answer exhibits a new kind of behavior not seen in most work known until now. The techniques include Laplace transform and the method of stationary phase, and a combinatorial technique for estimating the contributions of terms in an infinite series expansion for the solution. Addressed primarily to researchers inalgebraic geometry, ordinary differential equations and complex analysis, the book will also be of interest to applied mathematicians working on asymptotics of singular perturbations and numerical solution of ODE's.
Recent studies have revealed that bacterial protein methylation is a widespread post-translational modification that is required for virulence in selected pathogenic bacteria. In particular, altered methylation of outer membrane proteins has been shown to modulate the effectiveness of the host immu...
Destruction of Invariant Surfaces and Magnetic Coordinates for Perturbed Magnetic Fields
International Nuclear Information System (INIS)
Hudson, S.R.
2003-01-01
Straight-field-line coordinates are constructed for nearly integrable magnetic fields. The coordinates are based on the robust, noble-irrational rotational-transform surfaces, whose existence is determined by an application of Greene's residue criterion. A simple method to locate these surfaces is described. Sequences of surfaces with rotational-transform converging to low order rationals maximize the region of straight-field-line coordinates
DEFF Research Database (Denmark)
Schmidt, Per Simmendefeldt; Thygesen, Kristian Sommer
2018-01-01
(RPA) is found to yield high accuracy for both adsorption and surface energies. In contrast, all the considered density functionals fail to describe both quantities accurately. This establishes the RPA as a universally accurate method for surface science. In the second part, we use the RPA to construct...... be significant. RPA is compared to the more advanced renormalized adiabatic LDA (rALDA) method for a subset of the reactions, and they are found to describe the adsorbate-metal bond as well as adsorbate-adsorbate interactions similarly. The RPA results are compared to a range of standard density functional...... theory methods typically employed for surface reactions representing the various rungs on Jacob's ladder. The deviations are found to be highly functional, surface, and reaction dependent. Our work establishes the RPA and rALDA methods as universally accurate full ab initio methods for surface science...
Kilic, Veli Tayfun; Unal, Emre; Demir, Hilmi Volkan
2017-05-01
In this work, we investigate a method proposed for vessel detection and coil powering in an all-surface inductive heating system composed of outer squircle coils. Besides conventional circular coils, coils with different shapes such as outer squircle coils are used for and enable efficient all-surface inductive heating. Validity of the method, which relies on measuring inductance and resistance values of a loaded coil at different frequencies, is experimentally demonstrated for a coil with shape different from conventional circular coil. Simple setup was constructed with a small coil to model an all-surface inductive heating system. Inductance and resistance maps were generated by measuring coil's inductance and resistance values at different frequencies loaded by a plate made of different materials and located at various positions. Results show that in an induction hob for various coil geometries it is possible to detect a vessel's presence, to identify its material type and to specify its position on the hob surface by considering inductance and resistance of the coil measured on at least two different frequencies. The studied method is important in terms of enabling safe, efficient and user flexible heating in an all-surface inductive heating system by automatically detecting the vessel's presence and powering on only the coils that are loaded by the vessel with predetermined current levels.
Perturbed angular correlation study of surface magnetization in iron single crystals
International Nuclear Information System (INIS)
Sawicka, B.D.; Sawicki, J.A.; Pleiter, F.; Waard, H. de
1983-01-01
The behaviour of closure domains at the surface of iron single crystals in an external magnetic field was studied by DPAC on samples implanted with 111 In. It is observed that the surface magnetization does not follow that of the bulk. The movement of both the 90 0 and 180 0 walls of the closure domains is blocked up to a certain 'starting' value of the external field that is related to the demagnetization factor of the sample and also depends on the precise orientation of the crystal axes and on the implanted indium dose. (Auth.)
Polarized Light Scattering from Perfect and Perturbed Surfaces and Fundamental Scattering Systems
1992-02-29
ob- one frequency, an extension of it to multiple-field interac- served in the elastically scattered light emitted from glass tions would follow the...that 8. V CeIll . A. A. Maradudin, A. M. Marvin, and A. R. McGurn, can explain only gross scattering features. It is inde "Some aspects of light...and a surface of index n a 10.0 - 0.01. Such a surface could be made with a series of 1/4-wave dielectric layers on a glass substrate. It Is more
Ab-initio perturbed-cluster study of carbon monoxide adsorption at a stepped LiF(001) surface
Pisani, C.; Corà, F.; Orlando, R.; Nada, R.
1993-02-01
The perturbed-cluster ab-initio Hartree-Fock approach to the study of local defects in crystals [J. Chem. Phys. 92(1990)7448] is applied to the study of CO adsorption at a stepped LiF(001) surface. The step is simulated by a tablet of four ions superimposed on an infinite LiF(001) monolayer. The geometry of the step is first optimized, and corresponds to an important relaxation of cations and anions of the tablet inwards and outwards, respectively. The equilibrium configuration, adsorption energy and vibrational frequency of CO at a corner of the tablet occupied by a lithium cation are calculated. With respect to adsorption at a perfect (100) face, there is a large increase in interaction energy, especially when adsorption occurs via the oxygen atom. This difference is essentially related to modifications of the electrostatic field experienced by the adsorbed molecule.
Baumgart, Christian; Hoppe, Matthias Wilhelm; Freiwald, Jürgen
2016-01-01
The authors aimed to evaluate the differences in postural control during stance and gait between train conductors and controls. Twenty-one train conductors and 21 office workers performed 6 unilateral and bilateral balance tests on stable and unstable surfaces as well as a gait analysis. In the balance tests, the mean velocity of the center of pressure and unstable surface was measured. In the bilateral balance tests the selected stance width was measured. During gait the length, width, frequency, and velocity of the steps were calculated from the ground reaction forces. Train conductors showed a significantly greater step width during gait (15.4 ± 4.7 vs. 13.0 ± 3.4 cm; p = .035) and stance width during the bilateral stance on the unstable surface (21.0 ± 5.1 vs. 17.8 ± 3.7 cm; p = .026) than the office workers, while no differences were revealed in balance variables. The revealed differences between train conductors and office workers may represent task-specific feedforward control strategies, which increase the base of support and may be helpful to resist unexpected perturbations in trains.
International Nuclear Information System (INIS)
Zhou Bin; Sun Qi; Huang Yaodong; Shen Jun; Wu Guangming; Wang Jue
2004-01-01
The developments of the surface perturbation target and the thin silicon foil target used to research Rayleigh-Taylor instability in the resolved experiments of Inertial Confinement Fusion (ICF) are carried out. Based on the laser interference process combined with the figure-transfer process, the surface perturbation target with sine modulated perturbation is gotten, the wavelength is in the range of 20-100 μm and the amplitude is several micrometers. The thin silicon foil within the thickness about 3-4 μm is prepared by semiconductor process together with heavy-doped self-stop etching. Combined with ion beam etching, the check or the stripe patterns are transferred to the surface of thin silicon foils, and then the silicon grating foil is obtained
Coustenis, A.; Atreya, S.; Castillo-Rogez, J.; Mueller-Wodarg, I.; Spilker, L.; Strazzulla, G.
2018-06-01
This issue contains six articles on original research and review papers presented in the past year in sessions organized during several international meetings and congresses including the European Geosciences Union (EGU), European Planetary Science Congress (EPSC) and others. The manuscripts cover recent observations and models of the atmospheres, magnetospheres and surfaces of the giant planets and their satellites based on ongoing and recent planetary missions. Concepts of architecture and payload for future space missions are also presented. The six articles in this special issue cover a variety of objects in the outer solar system ranging from Jupiter to Neptune and the possibilities for their exploration. A brief introductory summary of their findings follows.
International Nuclear Information System (INIS)
Remetti, Romolo; Andreoli, Giulio; Keshishian, Silvina
2012-01-01
Highlights: ► We deal with HTR-10, that is a helium-cooled graphite-moderated pebble bed reactor. ► We carried out Monte Carlo simulation of the core by MCNP5. ► Extensive use of MCNP5 variance reduction methods has been done. ► We calculated the trend of neutron flux within the biological shield. ► We calculated neutron effective dose at the outer surface of biological shield. - Abstract: Research on experimental reactors, such as HTR-10, provide useful data about potentialities of very high temperature gas-cooled reactors (VHTR). The latter is today rated as one of the six nuclear reactor types involved in the Generation-IV International Forum (GIF) Initiative. In this study, the MCNP5 code has been employed to evaluate the neutron radiation trend vs. the biological shield's thickness and to calculate the neutron effective dose rate at the outer surface. The reactor's geometry has been completely modeled by means of lattices and universes provided by MCNP, even though some approximations were required. Monte Carlo calculations have been performed by means of a simple PC and, as a consequence, in order to obtain acceptable run times, it was made an extensive recourse to variance reduction methods.
Absence of Ni on the outer surface of Sr doped La 2 NiO 4 single crystals
Burriel, Mó nica; Wilkins, Stuart; Hill, John P.; Muñ oz-Má rquez, Miguel A.; Brongersma, Hidde H.; Kilner, John A.; Ryan, Mary P.; Skinner, Stephen J.
2014-01-01
A combination of surface sensitive techniques was used to determine the surface structure and chemistry of La2-xSrxNiO 4+δ. These measurements unequivocally showed that Ni is not present in the outermost atomic layer, suggesting that the accepted model with the B-site cations exposed to the environment is incorrect. © 2014 The Royal Society of Chemistry.
Directory of Open Access Journals (Sweden)
Naoto Imajo
2015-01-01
Full Text Available Terrestrial hermit crabs which are a type of hermit crabs live on land, whereas typical hermit crabs inhabit the sea. They have an ability of climbing a tree vertically. Their claws allow them to hang on the tree. In this study, an outer-pipe inspection robot was developed. Its locomotion mechanism was developed in imitation of the terrestrial hermit crab’s claws. It is equipped with two rimless wheels. Each of the spokes is tipped with a neodymium magnet, which allows the robot to remain attached to even a vertical steel pipe. Moreover, the robot has a mechanism for adjusting the camber angle of the right and left wheels, allowing it to tightly grip pipes with different diameters. Experiments were conducted to check the performance of the robot using steel pipes with different diameters, placed horizontally, vertically, or obliquely. The robot attempted to move a certain distance along a pipe, and its success rate was measured. It was found that the robot could successfully travel along pipes with vertical orientations, although it sometimes fell from oblique or horizontal pipes. The most likely reason for this is identified and discussed. Certain results were obtained in laboratory. Further experiments in actual environment are required.
Xin, Hongliang; Linic, Suljo
2016-06-01
Many commercial heterogeneous catalysts are complex structures that contain metal active sites promoted by multiple additives. Developing fundamental understanding about the impact of these perturbations on the local surface reactivity is crucial for catalyst development and optimization. In this contribution, we develop a general framework for identifying underlying mechanisms that control the changes in the surface reactivity of a metal site (more specifically the adsorbate-surface interactions) upon a perturbation in the local environment. This framework allows us to interpret fairly complex interactions on metal surfaces in terms of specific, physically transparent contributions that can be evaluated independently of each other. We use Cs-promoted dissociation of O2 as an example to illustrate our approach. We concluded that the Cs adsorbate affects the outcome of the chemical reaction through a strong alkali-induced electric field interacting with the static dipole moment of the O2/Ag(111) system.
Vacuum Outer-Gap Structure in Pulsar Outer Magnetospheres
International Nuclear Information System (INIS)
Gui-Fang, Lin; Li, Zhang
2009-01-01
We study the vacuum outer-gap structure in the outer magnetosphere of rotation-powered pulsars by considering the limit of trans-field height through a pair production process. In this case, the trans-field height is limited by the photon-photon pair production process and the outer boundary of the outer gap can be extended outside the light cylinder. By solving self-consistently the Poisson equation for electrical potential and the Boltzmann equations of electrons/positrons and γ-rays in a vacuum outer gap for the parameters of Vela pulsar, we obtain an approximate geometry of the outer gap, i.e. the trans-field height is limited by the pair-production process and increases with the radial distance to the star and the width of the outer gap starts at the inner boundary (near the null charge surface) and ends at the outer boundary which locates inside or outside the light cylinder depending on the inclination angle. (geophysics, astronomy, and astrophysics)
Lion, Alexis; Gette, Paul; Meyer, Christophe; Seil, Romain; Theisen, Daniel
2018-02-01
Our study aimed to evaluate the effect of cognitive challenge on double-leg postural control under visual and surface perturbations of patients with anterior cruciate ligament reconstruction (ACLR) cleared to return to sport. Double-leg stance postural control of 19 rehabilitated patients with ACLR (age: 24.8 ± 6.7 years, time since surgery: 9.2 ± 1.6 months) and 21 controls (age: 24.9 ± 3.7 years) was evaluated in eight randomized situations combining two cognitive (with and without silent backward counting in steps of seven), two visual (eyes open, eyes closed) and two surface (stable support, foam support) conditions. Sway area and sway path of the centre of foot pressure were measured during three 20-s recordings for each situation. Higher values indicated poorer postural control. Generally, postural control of patients with ACLR and controls was similar for sway area and sway path (p > 0.05). The lack of visual anchorage and the disturbance of the plantar input by the foam support increased sway area and sway path (p postural control during double-leg stance tests. The use of a dual task paradigm under increased task complexity modified postural control, but in a similar way in patients with ACLR than in healthy controls. Double-leg stance tests, even under challenging conditions, are not sensitive enough to reveal postural control differences between rehabilitated patients with ACLR and controls. Copyright © 2017 Elsevier B.V. All rights reserved.
Turbine airfoil with a compliant outer wall
Campbell, Christian X [Oviedo, FL; Morrison, Jay A [Oviedo, FL
2012-04-03
A turbine airfoil usable in a turbine engine with a cooling system and a compliant dual wall configuration configured to enable thermal expansion between inner and outer layers while eliminating stress formation in the outer layer is disclosed. The compliant dual wall configuration may be formed a dual wall formed from inner and outer layers separated by a support structure. The outer layer may be a compliant layer configured such that the outer layer may thermally expand and thereby reduce the stress within the outer layer. The outer layer may be formed from a nonplanar surface configured to thermally expand. In another embodiment, the outer layer may be planar and include a plurality of slots enabling unrestricted thermal expansion in a direction aligned with the outer layer.
Directory of Open Access Journals (Sweden)
A. Barth
2010-02-01
Full Text Available High-Frequency (HF radars measure the ocean surface currents at various spatial and temporal scales. These include tidal currents, wind-driven circulation, density-driven circulation and Stokes drift. Sequential assimilation methods updating the model state have been proven successful to correct the density-driven currents by assimilation of observations such as sea surface height, sea surface temperature and in-situ profiles. However, the situation is different for tides in coastal models since these are not generated within the domain, but are rather propagated inside the domain through the boundary conditions. For improving the modeled tidal variability it is therefore not sufficient to update the model state via data assimilation without updating the boundary conditions. The optimization of boundary conditions to match observations inside the domain is traditionally achieved through variational assimilation methods. In this work we present an ensemble smoother to improve the tidal boundary values so that the model represents more closely the observed currents. To create an ensemble of dynamically realistic boundary conditions, a cost function is formulated which is directly related to the probability of each boundary condition perturbation. This cost function ensures that the boundary condition perturbations are spatially smooth and that the structure of the perturbations satisfies approximately the harmonic linearized shallow water equations. Based on those perturbations an ensemble simulation is carried out using the full three-dimensional General Estuarine Ocean Model (GETM. Optimized boundary values are obtained by assimilating all observations using the covariances of the ensemble simulation.
Energy Technology Data Exchange (ETDEWEB)
Loomis, E. N.; Batha, S. H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Braun, D.; Sorce, C.; Landen, O. L. [Lawrence Livermore National Laboratory, Livermore, California 95281 (United States)
2011-09-15
Isolated defects on inertial confinement fusion ignition capsules are a concern as defects taller than a few hundred nanometers are calculated to form jets of high-Z material, which enter the main fuel. If this mixing of high-Z material is not controlled, a serious degradation in thermonuclear burn can occur. A path towards controlling the growth of defects on the outer surface of plastic capsules is currently under development, but requires accurate predictions of defect evolution driven by the early time ablative Richtmyer-Meshkov (RM) effect. The chief uncertainty is the Equation of State (EOS) for polystyrene and its effect on ablative RM. We report on measurements of the growth of isolated defects made at the onset of ablative RM oscillations driven by x-ray ablation to differentiate between EOS models used in design calculations. Experiments at the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] used on-axis area backlighting radiography and x-ray framing cameras to determine bump areal densities at discrete times. Bumps 12 and 14 {mu}m tall and 33 {mu}m FWHM were found to grow to 2 x their initial areal density by 3 ns after the start of the drive laser pulse. Shock speed measurements established target conditions resulting from the ablation process. The tabular LEOS 5310 [D. Young and E. Corey, J. Appl. Phys. 78, 3748 (1995)] model shows good agreement with measured shock speeds and bump growth whereas the QEOS model [R. More et al., Phys. Fluids 31, 3059 (1988)] over predicts shock speed and under predicts bump growth by 6x. Differences in ablative RM behavior were also found for x-ray ablation compared to laser ablation, which result in an overestimation (or non-existence) of oscillation frequency for x-ray ablation as predicted by theory.
International Nuclear Information System (INIS)
Blake, R.L.
1979-06-01
This report presents an objective discussion of the importance of the atmospheric/solar-terrestrial system to national energy programs. A brief sketch is given of the solar-terrestrial environment, extending from the earth's surface to the sun. Processes in this natural system influence several energy activities directly or indirectly, and some present and potential energy activities can influence the natural system. It is not yet possible to assess the two-way interactions quantitatively or to evaluate the economic impact. An investment by the Department of Energy (DOE) in a long-range basic research program would be an important part of the department's mission. Existing programs by other agencies in this area of research are reviewed, and a compatible DOE program is outlined. 18 figures, 5 tables
International Nuclear Information System (INIS)
Zipser, R.; Dose, G.F.
1977-01-01
The device makes possible periodical in-service inspections of welding seams and material of a reactor pressure vessel without local human presence. A 'support ring' encloses the pressure vessel in a horizontal plane with free space. It is vertically moved up and down in the space between pressure vessel and thermal shield by means of tackles. At a control desk placed in a protected area its movement is controlled and its vertical position is indicated. A 'rotating track' with its own drive is rotating remote-controlled on the 'support ring'. By a combination of the vertical with the rotating movement, an ultrasonic probe placed removably on the 'rotating hack', or a television camera will be brought to any position on the cylindrical circumference of the pressure vessel. Special devices extend the radius of action, in upward direction for inspecting the welding seams of the coolant nozzles, and in downward direction for the inspection of welds on the hemispherical bottom of the pressure vessel or on the outlet pipe nozzle placed there. The device remains installed during reactor operation, but is moved down to the lower horizontal surface of the thermal shield. Parts which are sensible to radiation like probes or television cameras and special devices will then be removed respectively mounted before beginning an inspection compaign. This position may be reached by the lower access in the biological shield and through an opening in the horizontal surface of the thermal shield. (HP) [de
Energy Technology Data Exchange (ETDEWEB)
Danisik, Martin; Frisch, Wolfgang [Tuebingen Univ. (Germany). Inst. of Geosciences; Panek, Tomas [Ostrava Univ. (Czech Republic). Dept. of Physical Geography and Geoecology; Matysek, Dalibor [Technical Univ. of Ostrava (Czech Republic). Dept. of Geological Engineering; Dunkl, Istvan [Geoscience Center Goettingen (Germany). Sedimentology and Environmental Geology
2008-09-15
The age of planation surfaces in the Podbeskydska pahorkatina Upland in the Outer Western Carpathians (OWC, Czech Republic) is constrained by low-temperature thermochronological dating methods for the first time. Our apatite fission track and apatite (U-Th)/He data measured on teschenite intrusions show that planation surfaces in the study area formed in post-Pannonian time (>7.1 Ma) and are therefore younger than traditionally believed. This contradicts the classical concepts, which stipulate that a large regional planation surface of Pannonian age (the so-called ''midmountain level'') developed in the whole Western Carpathians. Geodynamic implications of our data are the following: (i) the investigated Tesin and Godula nappes of the OWC were buried and thermally overprinted in the accretionary wedge in different ways, and consequently experienced different cooling histories. This indicates a dynamic basin setting with an active accretionary process in a subduction zone; (ii) accretionary processes in the OWC were active already during Late Eocene times. (orig.)
International Nuclear Information System (INIS)
Bartlett, R.; Kirtman, B.; Davidson, E.R.
1978-01-01
After noting some advantages of using perturbation theory some of the various types are related on a chart and described, including many-body nonlinear summations, quartic force-field fit for geometry, fourth-order correlation approximations, and a survey of some recent work. Alternative initial approximations in perturbation theory are also discussed. 25 references
International Nuclear Information System (INIS)
Komuro, Atsushi; Konno, Kaiki; Ando, Akira; Takashima, Keisuke; Kaneko, Toshiro; Tanaka, Naoki; Nonomura, Taku; Asai, Keisuke
2017-01-01
Gas-density perturbations near an airfoil surface generated by a nanosecond dielectric-barrier-discharge plasma actuator (ns-DBDPA) are visualized using a high-speed Schlieren imaging method. Wind-tunnel experiments are conducted for a wind speed of 20 m s −1 with an NACA0015 airfoil whose chord length is 100 mm. The results show that the ns-DBDPA first generates a pressure wave and then stochastic perturbations of the gas density near the leading edge of the airfoil. Two structures with different characteristics are observed in the stochastic perturbations. One structure propagates along the boundary between the shear layer and the main flow at a speed close to that of the main flow. The other propagates more slowly on the surface of the airfoil and causes mixing between the main and shear flows. It is observed that these two heated structures interact with each other, resulting in a recovery in the negative pressure coefficient at the leading edge of the airfoil. (paper)
Directory of Open Access Journals (Sweden)
D. S. Vakhlyarskiy
2016-01-01
Full Text Available This paper proposes a method to calculate the splitting of natural frequency of the shell of hemispherical resonator gyro. (HRG. The paper considers splitting that arises from the small defect of the middle surface, which makes the resonator different from the rotary shell. The presented method is a combination of the perturbation method and the finite element method. The method allows us to find the frequency splitting caused by defects in shape, arbitrary distributed in the circumferential direction. This is achieved by calculating the perturbations of multiple natural frequencies of the second and higher orders. The proposed method allows us to calculate the splitting of multiple frequencies for the shell with the meridian of arbitrary shape.A developed finite element is an annular element of the shell and has two nodes. Projections of movements are used on the axis of the global cylindrical system of coordinates, as the unknown. To approximate the movements are used polynomials of the second degree. Within the finite element the geometric characteristics are arranged in a series according to the small parameter of perturbations of the middle surface geometry.Movements on the final element are arranged in series according to the small parameter, and in a series according to circumferential angle. With computer used to implement the method, three-dimensional arrays are used to store the perturbed quantities. This allows the use of regular expressions for the mass and stiffness matrices, when building the finite element, instead of analytic dependencies for each perturbation of these matrices of the required order with desirable mathematical operations redefined in accordance with the perturbation method.As a test task, is calculated frequency splitting of non-circular cylindrical resonator with Navier boundary conditions. The discrepancy between the results and semi-analytic solution to this problem is less than 1%. For a cylindrical shell is
Dunn, John J.; Lade, Barbara N.
1991-01-01
The OspA gene from a North American strain of the Lyme disease Spirochete, Borrelia burgdorferi, was cloned under the control of transciption and translation signals from bacteriophage T7. Full-length OspA protein, a 273 amino acid (31kD) lipoprotein, is expressed poorly in Escherichia coli and is associated with the insoluble membrane fraction. In contrast, a truncated form of OspA lacking the amino-terminal signal sequence which normally would direct localization of the protein to the outer membrane is expressed at very high levels (less than or equal to 100 mg/liter) and is soluble. The truncated protein was purified to homogeneity and is being tested to see if it will be useful as an immunogen in a vaccine against Lyme disease. Circular dichroism and fluorescence spectroscopy was used to characterize the secondary structure and study conformational changes in the protein. Studies underway with other surface proteins from B burgdorferi and a related spirochete, B. hermsii, which causes relapsing fever, leads us to conclude that a strategy similar to that used to express the truncated OspA can provide a facile method for producing variations of Borrelia lipoproteins which are highly expressed in E. coli and soluble without exposure to detergents.
C. Colloca TS/FM
2004-01-01
TS/FM group informs you that, for the progress of the works at the Prévessin site entrance, some perturbation of the traffic may occur during the week between the 14th and 18th of June for a short duration. Access will be assured at any time. For more information, please contact 160239. C. Colloca TS/FM
Makabe, Koki; Nakamura, Takashi; Dhar, Debanjan; Ikura, Teikichi; Koide, Shohei; Kuwajima, Kunihiro
2018-04-27
Although many naturally occurring proteins consist of multiple domains, most studies on protein folding to date deal with single-domain proteins or isolated domains of multi-domain proteins. Studies of multi-domain protein folding are required for further advancing our understanding of protein folding mechanisms. Borrelia outer surface protein A (OspA) is a β-rich two-domain protein, in which two globular domains are connected by a rigid and stable single-layer β-sheet. Thus, OspA is particularly suited as a model system for studying the interplays of domains in protein folding. Here, we studied the equilibria and kinetics of the urea-induced folding-unfolding reactions of OspA probed with tryptophan fluorescence and ultraviolet circular dichroism. Global analysis of the experimental data revealed compelling lines of evidence for accumulation of an on-pathway intermediate during kinetic refolding and for the identity between the kinetic intermediate and a previously described equilibrium unfolding intermediate. The results suggest that the intermediate has the fully native structure in the N-terminal domain and the single layer β-sheet, with the C-terminal domain still unfolded. The observation of the productive on-pathway folding intermediate clearly indicates substantial interactions between the two domains mediated by the single-layer β-sheet. We propose that a rigid and stable intervening region between two domains creates an overlap between two folding units and can energetically couple their folding reactions. Copyright © 2018. Published by Elsevier Ltd.
Magni, Ruben; Espina, Benjamin H; Shah, Ketul; Lepene, Benjamin; Mayuga, Christine; Douglas, Temple A; Espina, Virginia; Rucker, Sally; Dunlap, Ross; Petricoin, Emanuel F Iii; Kilavos, Mary Frekko; Poretz, Donald M; Irwin, Gilbert R; Shor, Samuel M; Liotta, Lance A; Luchini, Alessandra
2015-11-04
Prompt antibiotic treatment of early stage Lyme borreliosis (LB) prevents progression to severe multisystem disease. There is a clinical need to improve the diagnostic specificity of early stage Lyme assays in the period prior to the mounting of a robust serology response. Using a novel analyte harvesting nanotechnology, Nanotrap particles, we evaluated urinary Borrelia Outer surface protein A (OspA) C-terminus peptide in early stage LB before and after treatment, and in patients suspected of late stage disseminated LB. We employed Nanotrap particles to concentrate urinary OspA and used a highly specific anti-OspA monoclonal antibody (mAb) as a detector of the C-terminus peptides. We mapped the mAb epitope to a narrow specific OspA C-terminal domain OspA236-239 conserved across infectious Borrelia species but with no homology to human proteins and no cross-reactivity with relevant viral and non-Borrelia bacterial proteins. 268 urine samples from patients being evaluated for all categories of LB were collected in a LB endemic area. The urinary OspA assay, blinded to outcome, utilized Nanotrap particle pre-processing, western blotting to evaluate the OspA molecular size, and OspA peptide competition for confirmation. OspA test characteristics: sensitivity 1.7 pg/mL (lowest limit of detection), % coefficient of variation (CV) = 8 %, dynamic range 1.7-30 pg/mL. Pre-treatment, 24/24 newly diagnosed patients with an erythema migrans (EM) rash were positive for urinary OspA while false positives for asymptomatic patients were 0/117 (Chi squared p antibiotic therapy, 10/10 were positive for urinary OspA. Urinary OspA of 8/8 patients switched from detectable to undetectable following symptom resolution post-treatment. Specificity of the urinary OspA test for the clinical symptoms was 40/40. Specificity of the urinary OspA antigen test for later serology outcome was 87.5 % (21 urinary OspA positive/24 serology positive, Chi squared p = 4.072e(-15)). 41 of 100 patients under
Hong, Youngjoon; Nicholls, David P.
2017-09-01
The capability to rapidly and robustly simulate the scattering of linear waves by periodic, multiply layered media in two and three dimensions is crucial in many engineering applications. In this regard, we present a High-Order Perturbation of Surfaces method for linear wave scattering in a multiply layered periodic medium to find an accurate numerical solution of the governing Helmholtz equations. For this we truncate the bi-infinite computational domain to a finite one with artificial boundaries, above and below the structure, and enforce transparent boundary conditions there via Dirichlet-Neumann Operators. This is followed by a Transformed Field Expansion resulting in a Fourier collocation, Legendre-Galerkin, Taylor series method for solving the problem in a transformed set of coordinates. Assorted numerical simulations display the spectral convergence of the proposed algorithm.
Renormalized Lie perturbation theory
International Nuclear Information System (INIS)
Rosengaus, E.; Dewar, R.L.
1981-07-01
A Lie operator method for constructing action-angle transformations continuously connected to the identity is developed for area preserving mappings. By a simple change of variable from action to angular frequency a perturbation expansion is obtained in which the small denominators have been renormalized. The method is shown to lead to the same series as the Lagrangian perturbation method of Greene and Percival, which converges on KAM surfaces. The method is not superconvergent, but yields simple recursion relations which allow automatic algebraic manipulation techniques to be used to develop the series to high order. It is argued that the operator method can be justified by analytically continuing from the complex angular frequency plane onto the real line. The resulting picture is one where preserved primary KAM surfaces are continuously connected to one another
Energy Technology Data Exchange (ETDEWEB)
Forini, V. [Institut für Physik, Humboldt-Universität zu Berlin, IRIS Adlershof,Zum Großen Windkanal 6, 12489 Berlin (Germany); Tseytlin, A.A. [Theoretical Physics Group, Blackett Laboratory, Imperial College,London, SW7 2AZ (United Kingdom); Vescovi, E. [Institut für Physik, Humboldt-Universität zu Berlin, IRIS Adlershof,Zum Großen Windkanal 6, 12489 Berlin (Germany); Institute of Physics, University of São Paulo,Rua do Matão 1371, 05508-090 São Paulo (Brazil)
2017-03-01
We revisit the computation of the 1-loop string correction to the “latitude' minimal surface in AdS{sub 5}×S{sup 5} representing 1/4 BPS Wilson loop in planar N=4 SYM theory previously addressed in https://arxiv.org/abs/1512.00841 and https://arxiv.org/abs/1601.04708. We resolve the problem of matching with the subleading term in the strong coupling expansion of the exact gauge theory result (derived previously from localization) using a different method to compute determinants of 2d string fluctuation operators. We apply perturbation theory in a small parameter (angle of the latitude) corresponding to an expansion near the AdS{sub 2} minimal surface representing 1/2 BPS circular Wilson loop. This allows us to compute the corrections to the heat kernels and zeta-functions of the operators in terms of the known heat kernels on AdS{sub 2}. We apply the same method also to two other examples of Wilson loop surfaces: generalized cusp and k-wound circle.
Vision-Based Autonomous Landing of a Quadrotor on the Perturbed Deck of an Unmanned Surface Vehicle
Directory of Open Access Journals (Sweden)
Riccardo Polvara
2018-04-01
Full Text Available Autonomous landing on the deck of an unmanned surface vehicle (USV is still a major challenge for unmanned aerial vehicles (UAVs. In this paper, a fiducial marker is located on the platform so as to facilitate the task since it is possible to retrieve its six-degrees of freedom relative-pose in an easy way. To compensate interruption in the marker’s observations, an extended Kalman filter (EKF estimates the current USV’s position with reference to the last known position. Validation experiments have been performed in a simulated environment under various marine conditions. The results confirmed that the EKF provides estimates accurate enough to direct the UAV in proximity of the autonomous vessel such that the marker becomes visible again. Using only the odometry and the inertial measurements for the estimation, this method is found to be applicable even under adverse weather conditions in the absence of the global positioning system.
Supersingular quantum perturbations
International Nuclear Information System (INIS)
Detwiler, L.C.; Klauder, J.R.
1975-01-01
A perturbation potential is called supersingular whenever generally every matrix element of the perturbation in the unperturbed eigenstates is infinite. It follows that supersingular perturbations do not have conventional perturbation expansions, say for energy eigenvalues. By invoking variational arguments, we determine the asymptotic behavior of the energy eigenvalues for asymptotically small values of the coupling constant of the supersingular perturbation
Johnson, Christopher Daniel
2018-01-01
Negotiated at the United Nations and in force since 1967, the Outer Space Treaty has been ratified by over 100 countries and is the most important and foundational source of space law. The treaty, whose full title is "Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies," governs all of humankind's activities in outer space, including activities on other celestial bodies and many activities on Earth related to outer space. All space exploration and human spaceflight, planetary sciences, and commercial uses of space—such as the global telecommunications industry and the use of space technologies such as position, navigation, and timing (PNT), take place against the backdrop of the general regulatory framework established in the Outer Space Treaty. A treaty is an international legal instrument which balances rights and obligations between states, and exists as a kind of mutual contract of shared understandings, rights, and responsibilities between them. Negotiated and drafted during the Cold War era of heightened political tensions, the Outer Space Treaty is largely the product of efforts by the United States and the USSR to agree on certain minimum standards and obligations to govern their competition in "conquering" space. Additionally, the Outer Space Treaty is similar to other treaties, including treaties governing the high seas, international airspace, and the Antarctic, all of which govern the behavior of states outside of their national borders. The treaty is brief in nature and only contains 17 articles, and is not comprehensive in addressing and regulating every possible scenario. The negotiating states knew that the Outer Space Treaty could only establish certain foundational concepts such as freedom of access, state responsibility and liability, non-weaponization of space, the treatment of astronauts in distress, and the prohibition of non-appropriation of
Schardt, A. W.; Behannon, K. W.; Carbary, J. F.; Eviatar, A.; Lepping, R. P.; Siscoe, G. L.
1983-01-01
Similarities between the Saturnian and terrestrial outer magnetosphere are examined. Saturn, like Earth, has a fully developed magnetic tail, 80 to 100 RS in diameter. One major difference between the two outer magnetospheres is the hydrogen and nitrogen torus produced by Titan. This plasma is, in general, convected in the corotation direction at nearly the rigid corotation speed. Energies of magnetospheric particles extend to above 500 keV. In contrast, interplanetary protons and ions above 2 MeV have free access to the outer magnetosphere to distances well below the Stormer cutoff. This access presumably occurs through the magnetotail. In addition to the H+, H2+, and H3+ ions primarily of local origin, energetic He, C, N, and O ions are found with solar composition. Their flux can be substantially enhanced over that of interplanetary ions at energies of 0.2 to 0.4 MeV/nuc.
International Nuclear Information System (INIS)
Stumpf, Th.; Fanghaenel, Th.; Bauer, A.; Kim, J.I.
2002-01-01
The surface sorption process of Eu(III) onto smectite was investigated by TRLFS in the trace concentration range. With increasing pH the formation of an inner-sphere Eu(III) surface complex was observed. The differences in the spectra and the fluorescence emission lifetimes of the surface sorbed Eu(III) in presence and absence of carbonate indicate the formation of ternary clay/Eu(III)/carbonate complexes /1/. (orig.)
Long-Lived Glass Mirrors For Outer Space
Bouquet, Frank L.; Maag, Carl R.; Heggen, Philip M.
1988-01-01
Paper summarizes available knowledge about glass mirrors for use in outer space. Strengths and weaknesses of various types of first and second reflective surfaces identified. Second-surface glass mirrors used in outer space designed to different criteria more stringent for terrestrial mirrors. Protons, electrons, cosmic rays, meteorites, and orbiting space debris affect longevities of components. Contamination also factor in space.
Venkatapathy, Ethiraj; Ellerby, D.; Gage, P.; Gasch, M.; Hwang, H.; Prabhu, D.; Stackpoole, M.; Wercinski, Paul
2018-01-01
This invited talk will provide an assessment of the TPS needs for Outer Planet In-situ missions to destinations with atmosphere. The talk will outline the drivers for TPS from destination, science, mission architecture and entry environment. An assessment of the readiness of the TPS, both currently available and under development, for Saturn, Titan, Uranus and Neptune are provided. The challenges related to sustainability of the TPS for future missions are discussed.
International Nuclear Information System (INIS)
Gianoulakis, S.; Klein, D.E.
1993-01-01
Buoyancy-driven natural-convection heat transfer in enclosures has been the subject of considerable research with applications to electronic packaging, solar collectors, and shipping containers for spent nuclear fuel. A numerical study has been carried out to predict combined natural-convection and radiation heat transfer in the annular region between concentric tubes. The inner tube was volumetrically heated. Both tubes were of finite conductance. The surfaces of the annular region were diffuse and gray. The gas in the annulus was assumed to be nonparticipating. A newly developed hybrid finite element finite difference method was used for the study. This method combines finite element discretization of geometries with finite difference discretized solution procedures for the governing differential equations. This study examined the effects of surface radiative properties and material conductivities on the temperature and velocity fields and on local heat transfer rates. Fluid Raleigh numbers ranging from 10 3 to 10 7 , ratios of solid to fluid region thermal conductivities ranging from 10 to 10 4 , and surface total hemispherical emissivities ranging from 0.0 to 1.0 were examined in this study. It was found that the heat transfer across the annulus was dominated by conduction and radiation for the lower Raleigh number flows. As the fluid Raleigh number increased, convection became a primary mode of heat transfer. As the surface emissivity was increased in the annulus, the average Nusselt number on the inner tube surface decreased
Outer Continental Shelf Lands Act
National Oceanic and Atmospheric Administration, Department of Commerce — This data represents geographic terms used within the Outer Continental Shelf Lands Act (OCSLA or Act). The Act defines the United States outer continental shelf...
International Nuclear Information System (INIS)
Roik, N.V.; Belyakova, L.A.
2014-01-01
Mesoporous silicas with hexagonally arranged pore channels were synthesized in water–ethanol-ammonia solution using cetyltrimethylammonium bromide as template. Directed modification of silica surface with N-[N′-(N′-phenyl)-2-aminophenyl]-3-aminopropyl groups was realized by postsynthetic activation of halogenoalkylsilicas, which have surface uniformly or selectively distributed 3-chloropropyl groups, with 2-aminodiphenylamine in the liquid phase. Chemical composition of silica materials was estimated by IR spectroscopy and chemical analysis of the surface products of reactions. Characteristics of porous structure of MCM-41-type silicas were determined from X-ray and low-temperature nitrogen ad-desorption measurements. Release ability of synthesized silica carriers was established on encapsulation of 4-aminobenzoic acid in pore channels and subsequent delivery at pH=6.86 and pH=1.00. It was found that N-[N′-(N′-phenyl)-2-aminophenyl]-3-aminopropyl groups block pore entrances at neutral pH preventing 4-aminobenzoic acid release. At pH=1.00 repulsion of positively charged surface aromatic amino groups localized near pore orifices provides unhindered liberation of aromatic amino acid from mesoporous channels. - Graphical abstract: Blocking of pores with N-[N′-(N′-phenyl)-2-aminophenyl]-3-aminopropyl groups at pH=6.86 for storage of ABA and opening of pore entrances at pH=1.00 for unhindered ABA liberation. - Highlights: • Modification of MCM-41 with N-[N′-(N′-phenyl)-2-aminophenyl]-3-aminopropyl groups. • Study of release ability of synthesized silica carriers in relation to amino acid. • Controlled blocking and opening of pores by amino groups at pH change were performed. • Retention of amino acid at pH=6.86 and its liberation at pH=1.00 was proved
Perek, Lubos
1993-10-01
Various aspects of space-environment management are discussed. Attention is called to the fact that, while space radio communications are already under an adequate management by the International Communications Union, the use of nuclear power sources is regulated by the recently adopted set of principles, and space debris will be discussed in the near future at the UN COPUOS, other aspects of management of outer space received little or no attention of the international community. These include the competency of crews and technical equipment of spacecraft launched by newcomers to space exploration; monitoring of locations and motions of space objects (now in national hands), with relevant data made accessible through a computer network; and the requirement to use space only for beneficial purposes and not for promoting narrow and debatable interests damaging the outer space environment and impeding on astronomical observations. It is suggested that some of these tasks would be best performed by an international space agency within the UN system of organizations.
Developments in perturbation theory
International Nuclear Information System (INIS)
Greenspan, E.
1976-01-01
Included are sections dealing with perturbation expressions for reactivity, methods for the calculation of perturbed fluxes, integral transport theory formulations for reactivity, generalized perturbation theory, sensitivity and optimization studies, multigroup calculations of bilinear functionals, and solution of inhomogeneous Boltzmann equations with singular operators
International Nuclear Information System (INIS)
Anderson, J.L.
1988-01-01
The region above the earth from about 90 km to 150 km is a major part of the upper or outer atmosphere. It is relatively unexplored, being too high for balloons or aircraft and too low for persistent orbiting spacecraft. However, the concept of a tethered subsatellite, deployed downward from an orbiting, more massive craft such as the Space Shuttle, opens the possibility of a research capability that could provide global mapping of this region. The need for research in this thick spherical shell above the earth falls into two major categories: (1) scientific data for understanding and modeling the global atmosphere and thereby determining its role in the earth system, and (2) engineering data for the design of future aerospace vehicles that will operate there. This paper presents an overview and synthesis of the currently perceived research needs and the state-of-the-art of the proposed tethered research capability. 16 references
The Eccentric Kozai-Lidov Mechanism for Outer Test Particle
Naoz, Smadar; Li, Gongjie; Zanardi, Macarena; de Elía, Gonzalo Carlos; Di Sisto, Romina P.
2017-07-01
The secular approximation of the hierarchical three body systems has been proven to be very useful in addressing many astrophysical systems, from planets to stars to black holes. In such a system, two objects are on a tight orbit and the tertiary is on a much wider orbit. Here, we study the dynamics of a system by taking the tertiary mass to zero and solve the hierarchical three body system up to the octupole level of approximation. We find a rich dynamics that the outer orbit undergoes due to gravitational perturbations from the inner binary. The nominal result of the precession of the nodes is mostly limited for the lowest order of approximation; however, when the octupole level of approximation is introduced, the system becomes chaotic, as expected, and the tertiary oscillates below and above 90°, similarly to the non-test particle flip behavior. We provide the Hamiltonian of the system and investigate the dynamics of the system from the quadrupole to the octupole level of approximations. We also analyze the chaotic and quasi-periodic orbital evolution by studying the surfaces of sections. Furthermore, including general relativity, we showcase the long-term evolution of individual debris disk particles under the influence of a far-away interior eccentric planet. We show that this dynamics can naturally result in retrograde objects and a puffy disk after a long timescale evolution (a few Gyr) for initially aligned configuration.
The Eccentric Kozai–Lidov Mechanism for Outer Test Particle
Energy Technology Data Exchange (ETDEWEB)
Naoz, Smadar [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Li, Gongjie [Harvard Smithsonian Center for Astrophysics, Institute for Theory and Computation, 60 Garden Street, Cambridge, MA 02138 (United States); Zanardi, Macarena; De Elía, Gonzalo Carlos; Di Sisto, Romina P., E-mail: snaoz@astro.ucla.edu [Instituto de Astrofísica de La Plata, CCT La Plata-CONICET-UNLP Paseo del Bosque S/N (1900), La Plata (Argentina)
2017-07-01
The secular approximation of the hierarchical three body systems has been proven to be very useful in addressing many astrophysical systems, from planets to stars to black holes. In such a system, two objects are on a tight orbit and the tertiary is on a much wider orbit. Here, we study the dynamics of a system by taking the tertiary mass to zero and solve the hierarchical three body system up to the octupole level of approximation. We find a rich dynamics that the outer orbit undergoes due to gravitational perturbations from the inner binary. The nominal result of the precession of the nodes is mostly limited for the lowest order of approximation; however, when the octupole level of approximation is introduced, the system becomes chaotic, as expected, and the tertiary oscillates below and above 90°, similarly to the non-test particle flip behavior. We provide the Hamiltonian of the system and investigate the dynamics of the system from the quadrupole to the octupole level of approximations. We also analyze the chaotic and quasi-periodic orbital evolution by studying the surfaces of sections. Furthermore, including general relativity, we showcase the long-term evolution of individual debris disk particles under the influence of a far-away interior eccentric planet. We show that this dynamics can naturally result in retrograde objects and a puffy disk after a long timescale evolution (a few Gyr) for initially aligned configuration.
Energy Technology Data Exchange (ETDEWEB)
Campo, Antonio [Idaho State Univ., Nuclear Engineering Dept., Pocatello, ID (United States); Sanchez, Alejo [Universidad de los Andes, Depto. de Ingenieria Mecanica, Merida (Venezuela)
1998-03-01
A semi-analytical analysis was conducted for the prediction of the mean bulk- and interface temperatures of gaseous and liquid fluids moving laminarly at high pressures inside thick-walled metallic tubes. The outer surfaces of the tubes are isothermal. The central goal of this article is to critically examine the thermal response of this kind of in-tube flows utilizing two versions of the 1-D lumped model: one is differential-numerical while the other is differential-algebraic. For the former, the local Nusselt number characterizing an inactive, isothermal tube was taken from correlation equations reported in the heat transfer literature. For the latter, a streamwise-mean Nusselt number associated with an active, isothermal tube was taken from standard correlation equations that appear in text-books on basic heat transfer. For the two different versions of the 1-D lumped model tested, the computed results consistently demonstrate that the differential-algebraic, provides accurate estimates of both the mean bulk- and the interface temperatures when compared with those temperature results computed with formal 2-D differential models. (author)
Outer Solar System Nomenclature
National Research Council Canada - National Science Library
Owen, Tobias C
2000-01-01
The work to be carried out on the subject grant during the next funding period will center on names needed for surface features on the Galilean satellites of Jupiter, names for the newly discovered...
Will Outer Tropical Cyclone Size Change due to Anthropogenic Warming?
Schenkel, B. A.; Lin, N.; Chavas, D. R.; Vecchi, G. A.; Knutson, T. R.; Oppenheimer, M.
2017-12-01
Prior research has shown significant interbasin and intrabasin variability in outer tropical cyclone (TC) size. Moreover, outer TC size has even been shown to vary substantially over the lifetime of the majority of TCs. However, the factors responsible for both setting initial outer TC size and determining its evolution throughout the TC lifetime remain uncertain. Given these gaps in our physical understanding, there remains uncertainty in how outer TC size will change, if at all, due to anthropogenic warming. The present study seeks to quantify whether outer TC size will change significantly in response to anthropogenic warming using data from a high-resolution global climate model and a regional hurricane model. Similar to prior work, the outer TC size metric used in this study is the radius in which the azimuthal-mean surface azimuthal wind equals 8 m/s. The initial results from the high-resolution global climate model data suggest that the distribution of outer TC size shifts significantly towards larger values in each global TC basin during future climates, as revealed by 1) statistically significant increase of the median outer TC size by 5-10% (p<0.05) according to a 1,000-sample bootstrap resampling approach with replacement and 2) statistically significant differences between distributions of outer TC size from current and future climate simulations as shown using two-sample Kolmogorov Smirnov testing (p<<0.01). Additional analysis of the high-resolution global climate model data reveals that outer TC size does not uniformly increase within each basin in future climates, but rather shows substantial locational dependence. Future work will incorporate the regional mesoscale hurricane model data to help focus on identifying the source of the spatial variability in outer TC size increases within each basin during future climates and, more importantly, why outer TC size changes in response to anthropogenic warming.
On the domain of string perturbation theory
International Nuclear Information System (INIS)
Davis, S.
1989-06-01
For a large class of effectively closed surfaces, it is shown that the only divergences in string scattering amplitudes at each order in perturbation theory are those associated with the coincidence of vertex operators and the boundary of moduli space. This class includes all closed surfaces of finite genus, and infinite-genus surfaces which can be uniformized by a group of Schottky type. While the computation is done explicitly for bosonic strings in their ground states, it can also be extended to excited states and to superstrings. The properties of these amplitudes lead to a definition of the domain of perturbation theory as the set of effectively closed surfaces. The implications of the restriction to effectively closed surfaces on the behavior of the perturbation series are discussed. (author). 20 refs, 6 figs
International Nuclear Information System (INIS)
Collins, J.C.
1985-01-01
Progress in quantum chromodynamics in the past year is reviewed in these specific areas: proof of factorization for hadron-hadron collisions, fast calculation of higher order graphs, perturbative Monte Carlo calculations for hadron-hadron scattering, applicability of perturbative methods to heavy quark production, and understanding of the small-x problem. 22 refs
Perturbative and constructive renormalization
International Nuclear Information System (INIS)
Veiga, P.A. Faria da
2000-01-01
These notes are a survey of the material treated in a series of lectures delivered at the X Summer School Jorge Andre Swieca. They are concerned with renormalization in Quantum Field Theories. At the level of perturbation series, we review classical results as Feynman graphs, ultraviolet and infrared divergences of Feynman integrals. Weinberg's theorem and Hepp's theorem, the renormalization group and the Callan-Symanzik equation, the large order behavior and the divergence of most perturbation series. Out of the perturbative regime, as an example of a constructive method, we review Borel summability and point out how it is possible to circumvent the perturbation diseases. These lectures are a preparation for the joint course given by professor V. Rivasseau at the same school, where more sophisticated non-perturbative analytical methods based on rigorous renormalization group techniques are presented, aiming at furthering our understanding about the subject and bringing field theoretical models to a satisfactory mathematical level. (author)
Strings as perturbations of evolving spin networks
International Nuclear Information System (INIS)
Smolin, Lee
2000-01-01
One step in the construction of a background independent formulation of string theory is detailed, in which it is shown how perturbative strings may arise as small fluctuations around histories in a formulation of non-perturbative dynamics of spin networks due to Markopoulou. In this formulation the dynamics of spin network states and their generalizations is described in terms of histories which have discrete analogues of the causal structure and many fingered time of Lorentzian spacetimes. Perturbations of these histories turn out to be described in terms of spin systems defined on 2-dimensional timelike surfaces embedded in the discrete spacetime. When the history has a classical limit which is Minkowski spacetime, the action of the perturbation theory is given to leading order by the spacetime area of the surface, as in bosonic string theory. This map between a non-perturbative formulation of quantum gravity and a 1+1 dimensional theory generalizes to a large class of theories in which the group SU(2) i s extended to any quantum group or supergroup. It is argued that a necessary condition for the non-perturbative theory to have a good classical limit is that the resulting 1+1 dimensional theory defines a consistent and stable perturbative string theory
Cryovolcanism in the outer solar system
Geissler, Paul E.
2015-01-01
Cryovolcanism is defined as the extrusion of liquids and vapors of materials that would be frozen solid at the planetary surface temperatures of the icy bodies of the outer solar system. Active cryovolcanism is now known to occur on Saturn's moon Enceladus and on Neptune's moon Triton and is suspected on Jupiter's moon Europa, while evidence for past cryovolcanic activity is widespread throughout the outer solar system. This chapter examines the mechanisms and manifestations of cryovolcanism, beginning with a review of the materials that make up these unusual ‘‘magmas’’ and the means by which they might erupt and concluding with a volcanologist's tour of the farthest reaches of the solar system.
International Nuclear Information System (INIS)
Mueller, A.H.
1986-03-01
A brief review of some of the recent progress in perturbative QCD is given (heavy quark production, small-x physics, minijets and related topics, classical simulations in high energy reactions, coherence and the string effect)
Ionization of inner shells of atoms taking account of outer shell rearrangement
International Nuclear Information System (INIS)
Amusia, M.Ya.
1977-01-01
The application of the general many-body theory and methods formulated with its help, in particular, the so-called random phase approximation with exchange (RPAE) and the many-body perturbation theory (MBPT) makes possible a description of ionization processes for many outer and intermediate shells of a number of atoms. This investigation of outer- and intermediate-shell ionization by photons and electrons demonstrates the collective character of these processes and the possibility of describing them by RPAE. 28 references
Generalized chiral perturbation theory
International Nuclear Information System (INIS)
Knecht, M.; Stern, J.
1994-01-01
The Generalized Chiral Perturbation Theory enlarges the framework of the standard χPT (Chiral Perturbation Theory), relaxing certain assumptions which do not necessarily follow from QCD or from experiment, and which are crucial for the usual formulation of the low energy expansion. In this way, experimental tests of the foundations of the standard χPT become possible. Emphasis is put on physical aspects rather than on formal developments of GχPT. (author). 31 refs
Existence of localizing solutions in plasticity via the geometric singular perturbation theory
Lee, Min-Gi; Tzavaras, Athanasios
2017-01-01
system has fast and slow time scales, forming a singularly perturbed problem. Geometric singular perturbation theory is applied to this problem to achieve an invariant surface. The flow on the invariant surface is analyzed via the Poincaré
The CMS Outer Hadron Calorimeter
Acharya, Bannaje Sripathi; Banerjee, Sunanda; Banerjee, Sudeshna; Bawa, Harinder Singh; Beri, Suman Bala; Bhandari, Virender; Bhatnagar, Vipin; Chendvankar, Sanjay; Deshpande, Pandurang Vishnu; Dugad, Shashikant; Ganguli, Som N; Guchait, Monoranjan; Gurtu, Atul; Kalmani, Suresh Devendrappa; Kaur, Manjit; Kohli, Jatinder Mohan; Krishnaswamy, Marthi Ramaswamy; Kumar, Arun; Maity, Manas; Majumder, Gobinda; Mazumdar, Kajari; Mondal, Naba Kumar; Nagaraj, P; Narasimham, Vemuri Syamala; Patil, Mandakini Ravindra; Reddy, L V; Satyanarayana, B; Sharma, Seema; Singh, B; Singh, Jas Bir; Sudhakar, Katta; Tonwar, Suresh C; Verma, Piyush
2006-01-01
The CMS hadron calorimeter is a sampling calorimeter with brass absorber and plastic scintillator tiles with wavelength shifting fibres for carrying the light to the readout device. The barrel hadron calorimeter is complemented with a outer calorimeter to ensure high energy shower containment in CMS and thus working as a tail catcher. Fabrication, testing and calibrations of the outer hadron calorimeter are carried out keeping in mind its importance in the energy measurement of jets in view of linearity and resolution. It will provide a net improvement in missing $\\et$ measurements at LHC energies. The outer hadron calorimeter has a very good signal to background ratio even for a minimum ionising particle and can hence be used in coincidence with the Resistive Plate Chambers of the CMS detector for the muon trigger.
Holman, Matthew J.; Lindstrom, David (Technical Monitor)
2005-01-01
Our ongoing research program combines extensive deep and wide-field observations using a variety of observational platforms with numerical studies of the dynamics of small bodies in the outer solar system in order to advance the main scientific goals of the community studying the Kuiper belt and the outer solar system. These include: (1) determining the relative populations of the known classes of KBOs as well as other possible classes; ( 2 ) determining the size distributions or luminosity function of the individual populations or the Kuiper belt as a whole; (3) determining the inclinations distributions of these populations; (4) establishing the radial extent of the Kuiper belt; ( 5 ) measuring and relating the physical properties of different types of KBOs to those of other solar system bodies; and, (6) completing our systematic inventory of the satellites of the outer planets.
International Nuclear Information System (INIS)
Dasnieres de Veigy, A.; Ouvry, S.; Paris-6 Univ., 75
1992-06-01
The problem of the statistical mechanics of an anyon gas is addressed. A perturbative analysis in the anyonic coupling constant α is reviewed, and the thermodynamical potential is computed at first and second order. An adequate second quantized formalism (field theory at finite temperature) is proposed. At first order in perturbation theory, the results are strikingly simple: only the second virial coefficient close to bosonic statistics is corrected. At second order, however, the complexity of the anyon model appears. One can compute exactly the perturbative correction to each cluster coefficient. However, and contrary to first order, a closed expression for the equation of state seems out of reach. As an illustration, the perturbative expressions of a 3 , a 4 , a 5 and a 6 are given at second order. Finally, using the same formalism, the equation of state of an anyon gas in a constant magnetic field is analyzed at first order in perturbation theory. (K.A.) 16 refs.; 3 figs.; 7 tabs
Rhen, Turk; Simmons, Rebecca B.
2016-01-01
Butterfly eyespots are complex morphological traits that can vary in size, shape and color composition even on the same wing surface. Homology among eyespots suggests they share a common developmental basis and function as an integrated unit in response to selection. Despite strong evidence of genetic integration, eyespots can also exhibit modularity or plasticity, indicating an underlying flexibility in pattern development. The extent to which particular eyespots or eyespot color elements exhibit modularity or integration is poorly understood, particularly following exposure to novel conditions. We used perturbation experiments to explore phenotypic correlations among different eyespots and their color elements on the ventral hindwing of V. cardui. Specifically, we identified which eyespots and eyespot features are most sensitive to perturbation by heat shock and injection of heparin—a cold shock mimic. For both treatments, the two central eyespots (3 + 4) were most affected by the experimental perturbations, whereas the outer eyespot border was more resistant to modification than the interior color elements. Overall, the individual color elements displayed a similar response to heat shock across all eyespots, but varied in their response to each other. Graphical modeling also revealed that although eyespots differ morphologically, regulation of eyespot size and colored elements appear to be largely integrated across the wing. Patterns of integration, however, were disrupted following heat shock, revealing that the strength of integration varies across the wing and is strongest between the two central eyespots. These findings support previous observations that document coupling between eyespots 3 + 4 in other nymphalid butterflies. PMID:27560365
International Nuclear Information System (INIS)
Duncan, R.; Craver, J.E.
1989-01-01
This patent describes a nuclear reactor fuel assembly grid. It comprises a first outer grip strap segment end. The first end having a first tab arranged in substantially the same plane as the plane defined by the first end; a second outer grip strap end. The second end having a second slot arranged in substantially the same plane as the plane defined by the second end, with the tab being substantially disposed in the slot, defining a socket therebetween; and a fort tine interposed substantially perpendicularly in the socket
International Nuclear Information System (INIS)
Ecker, G.
1996-06-01
After a general introduction to the structure of effective field theories, the main ingredients of chiral perturbation theory are reviewed. Applications include the light quark mass ratios and pion-pion scattering to two-loop accuracy. In the pion-nucleon system, the linear σ model is contrasted with chiral perturbation theory. The heavy-nucleon expansion is used to construct the effective pion-nucleon Lagrangian to third order in the low-energy expansion, with applications to nucleon Compton scattering. (author)
Getting Sloshed in Outer Space
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 12. Getting Sloshed in Outer Space - Liquid Behavior in Microgravity. N Ananthkrishnan. General Article Volume 12 Issue 12 December 2007 pp 40-45. Fulltext. Click here to view fulltext PDF. Permanent link:
Outer space structure and development
International Nuclear Information System (INIS)
Zeldovich, J.; Novikov, I.
1975-01-01
A brief account is presented answering the question of what in fact the outer space we observe consists of. The principle of spatial homogeneity of the universe and the idea of non-stationary cosmology are discussed. The origin and the future development of the universe are explained using the two above mentioned and some other hypotheses. (J.K.)
Outer space structure and development
Energy Technology Data Exchange (ETDEWEB)
Zeldovich, J; Novikov, I
1975-10-01
A brief account is presented answering the question of what in fact the outer space we observe consists of. The principle of spatial homogeneity of the universe and the idea of non-stationary cosmology are discussed. The origin and the future development of the universe are explained using the two above mentioned and some other hypotheses.
Plasmas in the outer heliosphere
Belcher, J. W.; Richardson, J. D.; Lazarus, A. J.; Gazis, P. R.; Barnes, A.
1995-01-01
We review the observed properties of the solar wind in the outer heliosphere, including observations from Voyager and the Pioneers, as well as from inner heliospheric probes as appropriate. These observations are crucial to modeling of the heliosphere and its interactions with the interstellar medium, since the wind ram pressure and its temporal variations are important in understanding the distance to the termination shock and heliopause and how those boundaries might vary in time. We focus on results since Solar Wind 7. Among the issues we will discuss are: (1) the time scales for and statistical properties of variations in the ram pressure in the outer heliosphere, and how those variations might affect the morphology of the heliospheric/interstellar medium interface; (2) the question of possible solar wind slowing in the outer heliosphere due to the pick-up of interstellar ions; (3) the issue of whether there is bulk heating of the solar wind associated either with interstellar ion pick-up or with continued heating due to stream-stream interactions; (4) evidence for latitudinal variations in solar wind properties; and (5) the 1.3 year periodicities apparent in the outer heliosphere, and the close correspondence with similar variations seen with inner heliospheric probes.
Outer Synchronization of Complex Networks by Impulse
International Nuclear Information System (INIS)
Sun Wen; Yan Zizong; Chen Shihua; Lü Jinhu
2011-01-01
This paper investigates outer synchronization of complex networks, especially, outer complete synchronization and outer anti-synchronization between the driving network and the response network. Employing the impulsive control method which is uncontinuous, simple, efficient, low-cost and easy to implement in practical applications, we obtain some sufficient conditions of outer complete synchronization and outer anti-synchronization between two complex networks. Numerical simulations demonstrate the effectiveness of the proposed impulsive control scheme. (general)
Thermographic studies of outer target heat fluxes on KSTAR
Directory of Open Access Journals (Sweden)
H.H. Lee
2017-08-01
Full Text Available A new infra-red (IR thermography system with high spatial resolution has been installed on KSTAR and is now mainly applied to measure the outer divertor heat load profile. The first measurement results of the outer divertor heat load profiles between ELMs have been applied to characterize the inter-ELMs outer divertor heat loads in KSTAR H-mode plasmas. In particular, the power decay length (λq of the divertor heat load profile has been determined by fitting the profile to a convolution of an exponential decay and a Gaussian function. The analysis on the power decay length shows a good agreement with the recent multi-machine λq scaling, which predicts λq of the inter-ELMs divertor heat load to be ∼1 mm under the standard H-mode scenario in ITER. The divertor IR thermography system has also successfully measured the strike point splitting of the outer divertor heat flux during the application of resonant magnetic perturbation (RMP fields. In addition, it has provided a clear evidence that the strike point splitting pattern depends on the RMP fields configuration.
Low velocity encounters of minor bodies with the outer planets
International Nuclear Information System (INIS)
Carusi, A.; Perozzi, E.; Valsecchi, G.B.
1983-01-01
Previous studies of close encounters of minor bodies with Jupiter have shown that the perturbations are stronger either if the encounter is very deep or if the velocity of the minor body relative to the planet is low. In the present research the author investigates the effects of low velocity encounters between fictitious minor bodies and the four outer planets. Two possible outcomes of this type of encounter are the temporary satellite capture of the minor body by the planet, and the exchange of perihelion with aphelion of the minor body orbit. Different occurrence rates of these processes are found for different planets, and the implications for the orbital evolution of minor bodies in the outer Solar System are discussed. (Auth.)
Helical temperature perturbations associated with tearing modes in tokamak plasmas
International Nuclear Information System (INIS)
Fitzpatrick, R.
1994-06-01
An investigation is made into the electron temperature perturbations associated with tearing modes in tokamak plasmas, with a view to determining the mode structure using Electron Cyclotron Emission (ECE) data. It is found that there is a critical magnetic island width below which the conventional picture where the temperature is flattened inside the separatrix is invalid. This effect comes about because of the stagnation of magnetic field lines in the vicinity of the rational surface and the finite parallel thermal conductivity of the plasma. For islands whose widths lie below the critical value there is no flattening of the electron temperature inside the separatrix. Such islands have quite different ECE signatures to conventional magnetic islands. In fact the two island types could, in principle, be differentiated experimentally. It should also be possible to map out the outer ideal magnetohydrodynamical eigenfunctions using ECE data. Islands whose widths are much less than the critical value are not destabilized by the perturbed bootstrap current, unlike conventional magnetic islands. This effect is found to have a number of very interesting consequences and may, indeed, provide an explanation for some puzzling experimental results regarding error field induced magnetic reconnection. All islands whose widths are much greater than the critical width possess a boundary layer on the separatrix which enables heat to be transported from one side of the island to the other via the X-point region. The structure of this boundary layer is described in some detail. Finally, the critical island width is found to be fairly substantial in conventional tokamak plasmas, provided that the long mean free path nature of parallel heat transport and the anomalous nature of perpendicular heat transport are taken into account in the calculation
Behaviour of scalar perturbations of a Reissner-Nordstroem black hole inside the event horizon
International Nuclear Information System (INIS)
McNamara, J.M.
1978-01-01
This paper considers general scalar perturbations of a Reissner-Nordstrom black hole and examines the qualitative behaviour of these perturbations in the region between and on the inner and outer horizons. Initial data are specified in terms of the ingoing radiation crossing the outer (event) horizon. The only essential restriction on these data is that the radiation should not die away too slowly on this horizon. The resultant perturbations are shown to be bounded and continuous. In particular, these properties hold for perturbations on the inner horizon. For certain types of scalar field (including the zero rest mass scalar field) perturbations vanish at the cross-over point on the inner horizon. (author)
Energy Technology Data Exchange (ETDEWEB)
Gerber, R [Commissariat a l' Energie Atomique, Section des Transferts Thermiques, Grenoble (France).Centre d' Etudes Nucleaires; Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires
1960-07-01
In experiments on forced convection heat transfer in an electrically heated channel, the temperature of the channel face in contact with the fluid is generally calculated from the measured temperature of the isolated face. A process for measuring this temperature leads to the study of the theoretical influence of a local perturbation of the wall thickness on the temperature distribution in this wall. Various problems at the limits, posed by this question of measurement, are dealt with. (author) [French] Dans les experiences de transfert thermique en convection forcee, dans un canal chauffe electriquement, la temperature de la face du canal en contact avec le fluide, est generalement calculee a partir de la temperature mesuree de la face isolee. Un procede de mesure de cette temperature conduit a etudier l'influence theorique d'une perturbation locale de l'epaisseur de la paroi sur la repartition de la temperature dans cette paroi. Divers problemes aux limites, posees par cette question de mesure, sont traites. (auteur)
Preheating curvaton perturbations
International Nuclear Information System (INIS)
Bastero-Gil, M.; Di Clemente, V.; King, S.F.
2005-01-01
We discuss the potentially important role played by preheating in certain variants of the curvaton mechanism in which isocurvature perturbations of a D-flat (and F-flat) direction become converted to curvature perturbations during reheating. We discover that parametric resonance of the isocurvature components amplifies the superhorizon fluctuations by a significant amount. As an example of these effects we develop a particle physics motivated model which involves hybrid inflation with the waterfall field N being responsible for generating the μ term, the right-handed neutrino mass scale, and the Peccei-Quinn symmetry breaking scale. The role of the curvaton field can be played either by usual Higgs field, or the lightest right-handed sneutrino. Our new results show that it is possible to achieve the correct curvature perturbations for initial values of the curvaton fields of order the weak scale. In this model we show that the prediction for the spectral index of the final curvature perturbation only depends on the mass of the curvaton during inflation, where consistency with current observational data requires the ratio of this mass to the Hubble constant to be 0.3
String perturbation theory diverges
International Nuclear Information System (INIS)
Gross, D.J.; Periwal, V.
1988-01-01
We prove that perturbation theory for the bosonic string diverges for arbitrary values of the coupling constant and is not Borel summable. This divergence is independent of the existence of the infinities that occur in the theory due to the presence of tachyons and dilaton tadpoles. We discuss the physical implications of such a divergence
International Nuclear Information System (INIS)
Suslov, I.M.
2005-01-01
Various perturbation series are factorially divergent. The behavior of their high-order terms can be determined by Lipatov's method, which involves the use of instanton configurations of appropriate functional integrals. When the Lipatov asymptotic form is known and several lowest order terms of the perturbation series are found by direct calculation of diagrams, one can gain insight into the behavior of the remaining terms of the series, which can be resummed to solve various strong-coupling problems in a certain approximation. This approach is demonstrated by determining the Gell-Mann-Low functions in φ 4 theory, QED, and QCD with arbitrary coupling constants. An overview of the mathematical theory of divergent series is presented, and interpretation of perturbation series is discussed. Explicit derivations of the Lipatov asymptotic form are presented for some basic problems in theoretical physics. A solution is proposed to the problem of renormalon contributions, which hampered progress in this field in the late 1970s. Practical perturbation-series summation schemes are described both for a coupling constant of order unity and in the strong-coupling limit. An interpretation of the Borel integral is given for 'non-Borel-summable' series. Higher order corrections to the Lipatov asymptotic form are discussed
Instantaneous stochastic perturbation theory
International Nuclear Information System (INIS)
Lüscher, Martin
2015-01-01
A form of stochastic perturbation theory is described, where the representative stochastic fields are generated instantaneously rather than through a Markov process. The correctness of the procedure is established to all orders of the expansion and for a wide class of field theories that includes all common formulations of lattice QCD.
Cosmological perturbations in antigravity
Oltean, Marius; Brandenberger, Robert
2014-10-01
We compute the evolution of cosmological perturbations in a recently proposed Weyl-symmetric theory of two scalar fields with oppositely signed conformal couplings to Einstein gravity. It is motivated from the minimal conformal extension of the standard model, such that one of these scalar fields is the Higgs while the other is a new particle, the dilaton, introduced to make the Higgs mass conformally symmetric. At the background level, the theory admits novel geodesically complete cyclic cosmological solutions characterized by a brief period of repulsive gravity, or "antigravity," during each successive transition from a big crunch to a big bang. For simplicity, we consider scalar perturbations in the absence of anisotropies, with potential set to zero and without any radiation. We show that despite the necessarily wrong-signed kinetic term of the dilaton in the full action, these perturbations are neither ghostlike nor tachyonic in the limit of strongly repulsive gravity. On this basis, we argue—pending a future analysis of vector and tensor perturbations—that, with respect to perturbative stability, the cosmological solutions of this theory are viable.
Solan, Eilon; Vieille, Nicolas
2015-01-01
We study irreducible time-homogenous Markov chains with finite state space in discrete time. We obtain results on the sensitivity of the stationary distribution and other statistical quantities with respect to perturbations of the transition matrix. We define a new closeness relation between transition matrices, and use graph-theoretic techniques, in contrast with the matrix analysis techniques previously used.
Scalar cosmological perturbations
International Nuclear Information System (INIS)
Uggla, Claes; Wainwright, John
2012-01-01
Scalar perturbations of Friedmann-Lemaitre cosmologies can be analyzed in a variety of ways using Einstein's field equations, the Ricci and Bianchi identities, or the conservation equations for the stress-energy tensor, and possibly introducing a timelike reference congruence. The common ground is the use of gauge invariants derived from the metric tensor, the stress-energy tensor, or from vectors associated with a reference congruence, as basic variables. Although there is a complication in that there is no unique choice of gauge invariants, we will show that this can be used to advantage. With this in mind our first goal is to present an efficient way of constructing dimensionless gauge invariants associated with the tensors that are involved, and of determining their inter-relationships. Our second goal is to give a unified treatment of the various ways of writing the governing equations in dimensionless form using gauge-invariant variables, showing how simplicity can be achieved by a suitable choice of variables and normalization factors. Our third goal is to elucidate the connection between the metric-based approach and the so-called 1 + 3 gauge-invariant approach to cosmological perturbations. We restrict our considerations to linear perturbations, but our intent is to set the stage for the extension to second-order perturbations. (paper)
Generalized perturbation series
International Nuclear Information System (INIS)
Baird, L.C.; Stinchcomb, G.
1973-01-01
An approximate solution of the Green's function equation may be used to generate an exact solution of the Schroedinger equation. This is accomplished through an iterative procedure. The procedure is equivalent to a perturbation expansion if the approximate Green's function is exact with respect to some reference potential
DEFF Research Database (Denmark)
jora, Renata; Schechter, Joseph; Naeem Shahid, M.
2009-01-01
We study the effects of the perturbation which violates the permutation symmetry of three Majorana neutrinos but preserves the well known (23) interchange symmetry. This is done in the presenceof an arbitrary Majorana phase which serves to insure the degeneracy of the three neutrinos at the unper...... at the unperturbed level....
Inner- and outer-sphere complexation of ions at the goethite-solution interface
Rahnemaie, R.; Hiemstra, T.; Riemsdijk, van W.H.
2006-01-01
Formation of inner- and outer-sphere complexes of environmentally important divalent ions on the goethite surface was examined by applying the charge distribution CD model for inner- and outer-sphere complexation. The model assumes spatial charge distribution between the surface (0-plane) and the
Energy Technology Data Exchange (ETDEWEB)
Isegawa, Miho; Liu, Fengyi [Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Kyoto 606-8103 (Japan); Maeda, Satoshi [Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan); Morokuma, Keiji, E-mail: morokuma@fukui.kyoto-u.ac.jp [Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Kyoto 606-8103 (Japan); Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322 (United States)
2014-10-21
We report reaction paths starting from N({sup 2}D) + H{sub 2}O for doublet spin states, D{sub 0} and D{sub 1}. The potential energy surfaces are explored in an automated fashion using the global reaction route mapping strategy. The critical points and reaction paths have been fully optimized at the complete active space second order perturbation theory level taking all valence electrons in the active space. In addition to direct dissociation pathways that would be dominant, three roaming processes, two roaming dissociation, and one roaming isomerization: (1) H{sub 2}ON → H–O(H)N → H–HON → NO({sup 2}Π) + H{sub 2}, (2) cis-HNOH → HNO–H → H–HNO → NO + H{sub 2}, (3) H{sub 2}NO → H–HNO → HNO–H → trans-HNOH, are confirmed on the D{sub 0} surface.
Studying the perturbative Reggeon
International Nuclear Information System (INIS)
Griffiths, S.; Ross, D.A.
2000-01-01
We consider the flavour non-singlet Reggeon within the context of perturbative QCD. This consists of ladders built out of ''reggeized'' quarks. We propose a method for the numerical solution of the integro-differential equation for the amplitude describing the exchange of such a Reggeon. The solution is known to have a sharp rise at low values of Bjorken-x when applied to non-singlet quantities in deep-inelastic scattering. We show that when the running of the coupling is taken into account this sharp rise is further enhanced, although the Q 2 dependence is suppressed by the introduction of the running coupling. We also investigate the effects of simulating non-perturbative physics by introducing a constituent mass for the soft quarks and an effective mass for the soft gluons exchanged in the t-channel. (orig.)
Turbine exhaust diffuser with region of reduced flow area and outer boundary gas flow
Orosa, John
2014-03-11
An exhaust diffuser system and method for a turbine engine. The outer boundary may include a region in which the outer boundary extends radially inwardly toward the hub structure and may direct at least a portion of an exhaust flow in the diffuser toward the hub structure. At least one gas jet is provided including a jet exit located on the outer boundary. The jet exit may discharge a flow of gas downstream substantially parallel to an inner surface of the outer boundary to direct a portion of the exhaust flow in the diffuser toward the outer boundary to effect a radially outward flow of at least a portion of the exhaust gas flow toward the outer boundary to balance an aerodynamic load between the outer and inner boundaries.
Nonperturbative perturbation theory
International Nuclear Information System (INIS)
Bender, C.M.
1989-01-01
In this talk we describe a recently proposed graphical perturbative calculational scheme for quantum field theory. The basic idea is to expand in the power of the interaction term. For example, to solve a λφ 4 theory in d-dimensional space-time, we introduce a small parameter δ and consider a λ(φ 2 ) 1+δ field theory. We show how to expand such a theory as a series in powers of δ. The resulting perturbation series appears to have a finite radius of convergence and numerical results for low-dimensional models are good. We have computed the two-point and four-point Green's functions to second order in powers of δ and the 2n-point Green's functions (n>2) to order δ. We explain how to renormalize the theory and show that, to first order in powers of δ, when δ>0 and d≥4 the theory is free. This conclusion remains valid to second order in powers of δ, and we believe that it remains valid to all orders in powers of δ. The new perturbative scheme is consistent with global supersymmetry invariance. We examine a two-dimensional supersymmetric quantum field theory in which we do not know of any other means for doing analytical calculations. We illustrate the power of this new technique by computing the ground-state energy density E to second order in this new perturbation theory. We show that there is a beautiful and delicate cancellation between infinite classes of graphs which leads to the result that E=0. (orig.)
Perturbed asymptotically linear problems
Bartolo, R.; Candela, A. M.; Salvatore, A.
2012-01-01
The aim of this paper is investigating the existence of solutions of some semilinear elliptic problems on open bounded domains when the nonlinearity is subcritical and asymptotically linear at infinity and there is a perturbation term which is just continuous. Also in the case when the problem has not a variational structure, suitable procedures and estimates allow us to prove that the number of distinct crtitical levels of the functional associated to the unperturbed problem is "stable" unde...
Capillary and viscous perturbations to Helmholtz flows
Moore, M. R.; Ockendon, H.; Ockendon, J. R.; Oliver, J. M.
2014-01-01
Inspired by recent calculations by Thoraval et al. (Phys. Rev. Lett., vol. 108, 2012, p.Â 264506) relating to droplet impact, this paper presents an analysis of the perturbations to the free surface caused by small surface tension and viscosity in steady Helmholtz flows. In particular, we identify the regimes in which appreciable vorticity can be shed from the boundary layer to the bulk flow. © 2014 Cambridge University Press.
Capillary and viscous perturbations to Helmholtz flows
Moore, M. R.
2014-02-21
Inspired by recent calculations by Thoraval et al. (Phys. Rev. Lett., vol. 108, 2012, p.Â 264506) relating to droplet impact, this paper presents an analysis of the perturbations to the free surface caused by small surface tension and viscosity in steady Helmholtz flows. In particular, we identify the regimes in which appreciable vorticity can be shed from the boundary layer to the bulk flow. © 2014 Cambridge University Press.
Twisting perturbed parafermions
Directory of Open Access Journals (Sweden)
A.V. Belitsky
2017-07-01
Full Text Available The near-collinear expansion of scattering amplitudes in maximally supersymmetric Yang–Mills theory at strong coupling is governed by the dynamics of stings propagating on the five sphere. The pentagon transitions in the operator product expansion which systematize the series get reformulated in terms of matrix elements of branch-point twist operators in the two-dimensional O(6 nonlinear sigma model. The facts that the latter is an asymptotically free field theory and that there exists no local realization of twist fields prevents one from explicit calculation of their scaling dimensions and operator product expansion coefficients. This complication is bypassed making use of the equivalence of the sigma model to the infinite-level limit of WZNW models perturbed by current–current interactions, such that one can use conformal symmetry and conformal perturbation theory for systematic calculations. Presently, to set up the formalism, we consider the O(3 sigma model which is reformulated as perturbed parafermions.
Heating of the outer solar atmosphere
International Nuclear Information System (INIS)
Parker, E.N.
1983-01-01
The author discusses the idea that there must be a source of magnetic fields somewhere below the solar surface. He starts by considering present day ideas about the sun's internal structure. The sun has a radius of approximately 700,000 km, of which the outer 100,000 km or so is the convective zone, according to mixing-length models. The dynamo is believed to operate in the convective zone, across which there may be a 5-10% variation in the angular velocity. There are the stretched east-west fields similar to the ones in the earth's core. Associated with these are poloidal fields which contribute to a net dipole moment of the sun and are generated by a dynamo. The author shows that essentially no magnetic field configuration has an equilibrium; they dissipate quickly in spite of the high conductivity in fluid motions and heating. This is probably the major part of the heating of the sun's outer atmosphere. (Auth.)
Mitochondrial dysfunction underlying outer retinal diseases
DEFF Research Database (Denmark)
Lefevere, Evy; Toft-Kehler, Anne Katrine; Vohra, Rupali
2017-01-01
Dysfunction of photoreceptors, retinal pigment epithelium (RPE) or both contribute to the initiation and progression of several outer retinal disorders. Disrupted Müller glia function might additionally subsidize to these diseases. Mitochondrial malfunctioning is importantly associated with outer...
Identification of outer membrane proteins of Yersinia pestis through biotinylation
Smither, S.J.; Hill, J.; Baar, B.L.M. van; Hulst, A.G.; Jong, A.L. de; Titball, R.W.
2007-01-01
The outer membrane of Gram-negative bacteria contains proteins that might be good targets for vaccines, antimicrobials or detection systems. The identification of surface located proteins using traditional methods is often difficult. Yersinia pestis, the causative agent of plague, was labelled with
Tension perturbations of black brane spacetimes
International Nuclear Information System (INIS)
Traschen, Jennie; Fox, Daniel
2004-01-01
We consider black brane spacetimes that have at least one spatial translation Killing field that is tangent to the brane. A new parameter, the tension of a spacetime, is defined. The tension parameter is associated with spatial translations in much the same way that the ADM mass is associated with the time translation Killing field. In this work, we explore the implications of the spatial translation symmetry for small perturbations around a background black brane. For static-charged black branes we derive a law which relates the tension perturbation to the surface gravity times the change in the horizon area, plus terms that involve variations in the charges and currents. We find that as a black brane evaporates the tension decreases. We also give a simple derivation of a first law for black brane spacetimes. These constructions hold when the background stress-energy is governed by a Hamiltonian, and the results include arbitrary perturbative stress-energy sources
Perturbation measurement of waveguides for acoustic thermometry
Lin, H.; Feng, X. J.; Zhang, J. T.
2013-09-01
Acoustic thermometers normally embed small acoustic transducers in the wall bounding a gas-filled cavity resonator. At high temperature, insulators of transducers loss electrical insulation and degrade the signal-to-noise ratio. One essential solution to this technical trouble is to couple sound by acoustic waveguides between resonator and transducers. But waveguide will break the ideal acoustic surface and bring perturbations(Δf+ig) to the ideal resonance frequency. The perturbation model for waveguides was developed based on the first-order acoustic theory in this paper. The frequency shift Δf and half-width change g caused by the position, length and radius of waveguides were analyzed using this model. Six different length of waveguides (52˜1763 mm) were settled on the cylinder resonator and the perturbation (Δf+ig) were measured at T=332 K and p=250˜500 kPa. The experiment results agreed with the theoretical prediction very well.
WORKSHOP: Inner space - outer space
International Nuclear Information System (INIS)
Anon.
1984-01-01
During the first week of May, the Fermilab theoretical astrophysics group hosted an international conference on science at the interface of particle physics and cosmology/astrophysics. The conference (Inner Space-Outer Space) was attended by a very diverse group of more than 200 physical scientists, including astronomers, astrophysicists, cosmologists, low-temperature physicists, and elementary particle theorists and experimentalists. The common interest which brought this diverse group to gether is the connection between physics on the smallest scale probed by man - the realm of elementary particle physics - and physics on the largest scale imaginable (the entire Universe) - the realm of cosmology
WORKSHOP: Inner space - outer space
Energy Technology Data Exchange (ETDEWEB)
Anon.
1984-09-15
During the first week of May, the Fermilab theoretical astrophysics group hosted an international conference on science at the interface of particle physics and cosmology/astrophysics. The conference (Inner Space-Outer Space) was attended by a very diverse group of more than 200 physical scientists, including astronomers, astrophysicists, cosmologists, low-temperature physicists, and elementary particle theorists and experimentalists. The common interest which brought this diverse group to gether is the connection between physics on the smallest scale probed by man - the realm of elementary particle physics - and physics on the largest scale imaginable (the entire Universe) - the realm of cosmology.
Outer scale of atmospheric turbulence
Lukin, Vladimir P.
2005-10-01
In the early 70's, the scientists in Italy (A.Consortini, M.Bertolotti, L.Ronchi), USA (R.Buser, Ochs, S.Clifford) and USSR (V.Pokasov, V.Lukin) almost simultaneously discovered the phenomenon of deviation from the power law and the effect of saturation for the structure phase function. During a period of 35 years we have performed successively the investigations of the effect of low-frequency spectral range of atmospheric turbulence on the optical characteristics. The influence of the turbulence models as well as a outer scale of turbulence on the characteristics of telescopes and systems of laser beam formations has been determined too.
Non-Perturbative Renormalization
Mastropietro, Vieri
2008-01-01
The notion of renormalization is at the core of several spectacular achievements of contemporary physics, and in the last years powerful techniques have been developed allowing to put renormalization on a firm mathematical basis. This book provides a self-consistent and accessible introduction to the sophisticated tools used in the modern theory of non-perturbative renormalization, allowing an unified and rigorous treatment of Quantum Field Theory, Statistical Physics and Condensed Matter models. In particular the first part of this book is devoted to Constructive Quantum Field Theory, providi
Perturbative quantum chromodynamics
1989-01-01
This book will be of great interest to advanced students and researchers in the area of high energy theoretical physics. Being the most complete and updated review volume on Perturbative QCD, it serves as an extremely useful textbook or reference book. Some of the reviews in this volume are the best that have been written on the subject anywhere. Contents: Factorization of Hard Processes in QCD (J C Collins, D E Soper & G Sterman); Exclusive Processes in Quantum Chromodynamics (S J Brodsky & G P Lepage); Coherence and Physics of QCD Jets (Yu L Dokshitzer, V A Khoze & S I Troyan); Pomeron in Qu
Perturbative quantum chromodynamics
International Nuclear Information System (INIS)
Radyushkin, A.V.
1987-01-01
The latest achievements in perturbative quantum chromodynamics (QCD) relating to the progress in factorization of small and large distances are presented. The following problems are concerned: Development of the theory of Sudakov effects on the basis of mean contour formalism. Development of nonlocal condensate formalism. Calculation of hadron wave functions and hadron distribution functions using QCD method of sum rules. Development of the theory of Regge behaviour in QCD, behaviour of structure functions at small x. Study of polarization effects in hadron processes with high momentum transfer
Perturbed effects at radiation physics
International Nuclear Information System (INIS)
Külahcı, Fatih; Şen, Zekâi
2013-01-01
Perturbation methodology is applied in order to assess the linear attenuation coefficient, mass attenuation coefficient and cross-section behavior with random components in the basic variables such as the radiation amounts frequently used in the radiation physics and chemistry. Additionally, layer attenuation coefficient (LAC) and perturbed LAC (PLAC) are proposed for different contact materials. Perturbation methodology provides opportunity to obtain results with random deviations from the average behavior of each variable that enters the whole mathematical expression. The basic photon intensity variation expression as the inverse exponential power law (as Beer–Lambert's law) is adopted for perturbation method exposition. Perturbed results are presented not only in terms of the mean but additionally the standard deviation and the correlation coefficients. Such perturbation expressions provide one to assess small random variability in basic variables. - Highlights: • Perturbation methodology is applied to Radiation Physics. • Layer attenuation coefficient (LAC) and perturbed LAC are proposed for contact materials. • Perturbed linear attenuation coefficient is proposed. • Perturbed mass attenuation coefficient (PMAC) is proposed. • Perturbed cross-section is proposed
AN N-BODY INTEGRATOR FOR GRAVITATING PLANETARY RINGS, AND THE OUTER EDGE OF SATURN'S B RING
International Nuclear Information System (INIS)
Hahn, Joseph M.; Spitale, Joseph N.
2013-01-01
A new symplectic N-body integrator is introduced, one designed to calculate the global 360° evolution of a self-gravitating planetary ring that is in orbit about an oblate planet. This freely available code is called epi i nt, and it is distinct from other such codes in its use of streamlines to calculate the effects of ring self-gravity. The great advantage of this approach is that the perturbing forces arise from smooth wires of ring matter rather than discreet particles, so there is very little gravitational scattering and so only a modest number of particles are needed to simulate, say, the scalloped edge of a resonantly confined ring or the propagation of spiral density waves. The code is applied to the outer edge of Saturn's B ring, and a comparison of Cassini measurements of the ring's forced response to simulations of Mimas's resonant perturbations reveals that the B ring's surface density at its outer edge is σ 0 = 195 ± 60 g cm –2 , which, if the same everywhere across the ring, would mean that the B ring's mass is about 90% of Mimas's mass. Cassini observations show that the B ring-edge has several free normal modes, which are long-lived disturbances of the ring-edge that are not driven by any known satellite resonances. Although the mechanism that excites or sustains these normal modes is unknown, we can plant such a disturbance at a simulated ring's edge and find that these modes persist without any damping for more than ∼10 5 orbits or ∼100 yr despite the simulated ring's viscosity ν s = 100 cm 2 s –1 . These simulations also indicate that impulsive disturbances at a ring can excite long-lived normal modes, which suggests that an impact in the recent past by perhaps a cloud of cometary debris might have excited these disturbances, which are quite common to many of Saturn's sharp-edged rings
Non-perturbative versus perturbative renormalization of lattice operators
International Nuclear Information System (INIS)
Goeckeler, M.; Technische Hochschule Aachen; Horsley, R.; Ilgenfritz, E.M.; Oelrich, H.; Forschungszentrum Juelich GmbH; Schierholz, G.; Forschungszentrum Juelich GmbH; Perlt, H.; Schiller, A.; Rakow, P.
1995-09-01
Our objective is to compute the moments of the deep-inelastic structure functions of the nucleon on the lattice. A major source of uncertainty is the renormalization of the lattice operators that enter the calculation. In this talk we compare the renormalization constants of the most relevant twist-two bilinear quark operators which we have computed non-perturbatively and perturbatively to one loop order. Furthermore, we discuss the use of tadpole improved perturbation theory. (orig.)
Topological analysis of Chlamydia trachomatis L2 outer membrane protein 2
DEFF Research Database (Denmark)
Mygind, P; Christiansen, Gunna; Birkelund, Svend
1998-01-01
Using monospecific polyclonal antisera to different parts of Chlamydia trachomatis L2 outer membrane protein 2 (Omp2), we show that the protein is localized at the inner surface of the outer membrane. Omp2 becomes immunoaccessible when Chlamydia elementary bodies are treated with dithiothreitol...
Ohmic losses in coaxial resonators with longitudinal inner-outer corrugation
Energy Technology Data Exchange (ETDEWEB)
Shenyong Hou, A. [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China); Yangtze Normal University, Chongqing 408001 (China); Sheng Yu, B.; Hongfu Li, C.; Qixiang Zhao, D. [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China); Xiang Li, E. [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China); Queen Mary University of London, London E1 4NS (United Kingdom)
2013-05-15
In this paper, a coaxial resonator with longitudinal inner-outer corrugation is introduced. Its eigen-equation and expression of ohmic losses are derived. Ohmic losses in the cavity are investigated. Results show that ohmic losses in the outer and inner conductors share a similar variation trend, while the former is larger than the later. What's more, changes of the inner and outer slot depth and width induce different variations of ohmic losses on the surface of the inner and outer conductors.
Perturbation studies on KAHTER
Energy Technology Data Exchange (ETDEWEB)
Rueckert, M.; Jonas, H.; Neef, R. D.
1974-10-15
The paper describes experimental and analytical results by both transport theory and diffusion theory calculations of perturbation tests in the KAHTER pebble bed critical experiment. The fission-weighted adjoint flux is measured from in-core detector responses by introducing a Cf-source into the core. Adjoint-weighted reactivities are calculated and compared to reactivity measurements for the introduction of a fuel and graphite pebble onto the top of the critical pile, the central rod worth, and the effect of replacing B4C with varying amounts of HfC in the central rod. In addition, analytical studies were made of the sensitivity of criticality to the fuel to graphite pebble ratio as measured in tests and of the effect of the upper void cavity as simulated in tests by placing cadmium layer across the top of the pebble pile to force a zero flux boundary condition.
Introduction to perturbation methods
Holmes, M
1995-01-01
This book is an introductory graduate text dealing with many of the perturbation methods currently used by applied mathematicians, scientists, and engineers. The author has based his book on a graduate course he has taught several times over the last ten years to students in applied mathematics, engineering sciences, and physics. The only prerequisite for the course is a background in differential equations. Each chapter begins with an introductory development involving ordinary differential equations. The book covers traditional topics, such as boundary layers and multiple scales. However, it also contains material arising from current research interest. This includes homogenization, slender body theory, symbolic computing, and discrete equations. One of the more important features of this book is contained in the exercises. Many are derived from problems of up- to-date research and are from a wide range of application areas.
Perturbation theory with instantons
International Nuclear Information System (INIS)
Carruthers, P.; Pinsky, S.S.; Zachariasen, F.
1977-05-01
''Perturbation theory'' rules are developed for calculating the effect of instantons in a pure Yang-Mills theory with no fermions, in the ''dilute gas'' approximation in which the N-instanton solution is assumed to be the sum of N widely separated one-instanton solutions. These rules are then used to compute the gluon propagator and proper vertex function including all orders of the instanton interaction but only to lowest order in the gluon coupling. It is to be expected that such an approximation is valid only for momenta q larger than the physical mass μ. The result is that in this regime instantons cause variations in the propagator and vertex of the form (μ 2 /q 2 )/sup -8π 2 b/ where b is the coefficient in the expansion of the β function: β = bg 3 +...
Rotational instability in the outer region of protoplanetary disks
Energy Technology Data Exchange (ETDEWEB)
Ono, Tomohiro [Department of Astronomy, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Nomura, Hideko; Takeuchi, Taku, E-mail: ono.t@kusastro.kyoto-u.ac.jp [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551 (Japan)
2014-05-20
We analytically calculate the marginally stable surface density profile for the rotational instability of protoplanetary disks. The derived profile can be utilized for considering the region in a rotating disk where radial pressure gradient force is comparable to the gravitational force, such as an inner edge, steep gaps or bumps, and an outer region of the disk. In this paper, we particularly focus on the rotational instability in the outer region of disks. We find that a protoplanetary disk with a surface density profile of similarity solution becomes rotationally unstable at a certain radius, depending on its temperature profile and a mass of the central star. If the temperature is relatively low and the mass of the central star is high, disks have rotationally stable similarity profiles. Otherwise, deviation from the similarity profiles of surface density could be observable, using facilities with high sensitivity, such as ALMA.
Rotational instability in the outer region of protoplanetary disks
International Nuclear Information System (INIS)
Ono, Tomohiro; Nomura, Hideko; Takeuchi, Taku
2014-01-01
We analytically calculate the marginally stable surface density profile for the rotational instability of protoplanetary disks. The derived profile can be utilized for considering the region in a rotating disk where radial pressure gradient force is comparable to the gravitational force, such as an inner edge, steep gaps or bumps, and an outer region of the disk. In this paper, we particularly focus on the rotational instability in the outer region of disks. We find that a protoplanetary disk with a surface density profile of similarity solution becomes rotationally unstable at a certain radius, depending on its temperature profile and a mass of the central star. If the temperature is relatively low and the mass of the central star is high, disks have rotationally stable similarity profiles. Otherwise, deviation from the similarity profiles of surface density could be observable, using facilities with high sensitivity, such as ALMA.
Singular perturbation of simple eigenvalues
International Nuclear Information System (INIS)
Greenlee, W.M.
1976-01-01
Two operator theoretic theorems which generalize those of asymptotic regular perturbation theory and which apply to singular perturbation problems are proved. Application of these theorems to concrete problems is involved, but the perturbation expansions for eigenvalues and eigenvectors are developed in terms of solutions of linear operator equations. The method of correctors, as well as traditional boundary layer techniques, can be used to apply these theorems. The current formulation should be applicable to highly singular ''hard core'' potential perturbations of the radial equation of quantum mechanics. The theorems are applied to a comparatively simple model problem whose analysis is basic to that of the quantum mechanical problem
Outer grid strap protruding spring repair apparatus
International Nuclear Information System (INIS)
Widener, W.H.
1987-01-01
This patent describes a nuclear fuel assembly grid spring repair apparatus for repairing a spring formed on an outer strap of a fuel assembly grid and having a portion protruding outwardly beyond the strap, the apparatus comprising: (a) a support frame defining an opening and having means defining a guide channel extending along the opening in a first direction; (b) means mounted on the frame and being adjustable for attaching the frame to the outer strap of the support grid so that the frame opening is aligned with the outwardly protruding spring on the outer strap; (c) an outer slide having a passageway defined therethrough and being mounted in the guide channel for reciprocable movement along the frame opening in the first direction for aligning the passageway with the outwardly protruding portion of the spring on the outer strap. The outer slide also has means defining a guide way extending along the passageway in a second direction generally orthogonal to the first direction; (d) a spring reset mechanism being operable for resetting the protruding spring to a nonprotruding position relative to the outer strap when the mechanism is aligned with the protruding portion of the spring; and (e) an inner slide supporting the spring reset mechanism and being mounted to the guide way for reciprocable movement along the passageway of the outer slide in the second direction for aligning the spring reset mechanism with the protruding portion of the spring on the outer strap
Non-linear perturbations of a spherically collapsing star
International Nuclear Information System (INIS)
Brizuela, David
2009-01-01
Linear perturbation theory has been a successful tool in General Relativity, and can be considered as complementary to full nonlinear simulations. Going to second and higher perturbative orders improves the approximation and offers a controlled way to analyze the nonlinearities of the theory, though the problem becomes much harder computationally. We present a systematic approach to the treatment of high order metric perturbations, focusing on the scenario of nonspherical perturbations of a dynamical spherical background. It is based on the combination of adapted geometrical variables and the use of efficient computer algebra techniques. After dealing with a number of theoretical issues, like the construction of gauge invariants, we apply the formalism to the particular case of a perfect fluid star surrounded by a vacuum exterior. We describe the regularization of the divergences of the perturbations at null infinity and the matching conditions through the surface of the star.
Gouré, Eric
2011-01-01
Ammonia N-H bond is cleaved at room temperature by the silica-supported tantalum imido amido complex [(≡SiO)2Ta(NH)(-NH2)], 2, if excess ammonia is present, but requires 150 °C to achieve the same reaction if only one equivalent NH3 is added to 2. MAS solid-state 15N NMR and in situ IR spectroscopic studies of the reaction of either 15N or 2H labeled ammonia with 2 show that initial coordination of the ammonia is followed by scrambling of either 15N or 2H among ammonia, amido and imido groups. Density functional theory (DFT) calculations with a cluster model [{(μ-O)[(H3SiO) 2SiO]2}Ta(NH)(-NH2)(NH3)], 2 q·NH3, show that the intramolecular H transfer from Ta-NH2 to TaNH is ruled out, but the H transfers from the coordinated ammonia to the amido and imido groups have accessible energy barriers. The energy barrier for the ammonia N-H activation by the Ta-amido group is energetically preferred relative to the Ta-imido group. The importance of excess NH3 for getting full isotope scrambling is rationalized by an outer sphere assistance of ammonia acting as proton transfer agent, which equalizes the energy barriers for H transfer from coordinated ammonia to the amido and imido groups. In contrast, additional coordinated ammonia does not favor significantly the H transfer. These results rationalize the experimental conditions used. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.
International Nuclear Information System (INIS)
Harada, Masayasu
2009-01-01
Chiral perturbation theory has been used for great number of phenomenological analyses in low energy QCD as well as the lattice QCD analyses since the creation of the theory by Weinberg in 1979 followed by its consolidation by Gasser and Leutwyler in 1984 and 85. The theory is now the highly established one as the approach based on the effective field theory to search for Green function including quantum correlations in the frame of the systematic expansion technique using Lagrangian which includes all of the terms allowed by the symmetry. This review has been intended to describe how systematically physical quantities are calculated in the framework of the chiral symmetry. Consequently many of the various phenomenological analyses are not taken up here for which other reports are to be referred. Further views are foreseen to be developed based on the theory in addition to numbers of results reported up to the present. Finally π-π scattering is taken up to discuss to what energy scale the theory is available. (S. Funahashi)
International Nuclear Information System (INIS)
Fabris, J.D.
1977-01-01
The electric quadrupolar interaction in some hafnium complexes, measured at the metal nucleus level is studied. For that purpose, the technique of γ-γ perturbed angular correlation is used: the frequencies of quadrupolar interaction are compared with some hafnium α-hydroxicarboxilates, namely glycolate, lactate, mandelate and benzylate; the influence of the temperature on the quadrupolar coupling on the hafnium tetramandelate is studied; finally, the effects associated with the capture of thermal neutrons by hafnium tetramandelate are examined locally at the nuclear level. The first group of results shows significant differences in a series of complexes derived from glycolic acid. On the other hand, the substitution of the protons in hafnium tetramandelate structure by some alkaline cations permits to verify a correlation between the variations in the quadrupolar coupling and the electronegativities of the substituent elements. Measurements at high temperatures show that this complex is thermally stable at 100 and 150 0 C. It is possible to see the appearance of two distinct sites for the probe nucleus, after heating the sample at 100 0 C for prolonged time. This fact is attributed to a probable interconversion among the postulated structural isomers for the octacoordinated compounds. Finally, measurements of angular correlation on the irradiated complex show that there is an effective destruction of the target molecule by neutron capture [pt
Perturbative quantum chromodynamics
International Nuclear Information System (INIS)
Brodsky, S.J.
1979-12-01
The application of QCD to hadron dynamics at short distances, where asymptotic freedom allows a systematic perturbative approach, is addressed. The main theme of the approach is to incorporate systematically the effects of the hadronic wave function in large momentum transfer exclusive and inclusive reactions. Although it is conventional to treat the hadron as a classical source of on-shell quarks, there are important dynamical effects due to hadronic constituent structure which lead to a broader testing ground for QCD. QCD predictions are discussed for exclusive processes and form factors at large momentum transfer in which the short-distance behavior and the finite compositeness of the hadronic wave functions play crucial roles. Many of the standard tests of QCD are reviewed including the predictions for R = sigma/sub e + e - →had//sigma/sub e + e - →μ + μ - /, the structure functions of hadrons and photons, jet phenomena, and the QCD corrections to deep inelastic processes. The exclusive-inclusive connection in QCD, the effects of power-law scale-breaking contributions, and the important role of the available energy in controlling logarithmic scale violations are also discussed. 150 references, 44 figures
Dynamics of a single ion in a perturbed Penning trap: Octupolar perturbation
International Nuclear Information System (INIS)
Lara, Martin; Salas, J. Pablo
2004-01-01
Imperfections in the design or implementation of Penning traps may give rise to electrostatic perturbations that introduce nonlinearities in the dynamics. In this paper we investigate, from the point of view of classical mechanics, the dynamics of a single ion trapped in a Penning trap perturbed by an octupolar perturbation. Because of the axial symmetry of the problem, the system has two degrees of freedom. Hence, this model is ideal to be managed by numerical techniques like continuation of families of periodic orbits and Poincare surfaces of section. We find that, through the variation of the two parameters controlling the dynamics, several periodic orbits emanate from two fundamental periodic orbits. This process produces important changes (bifurcations) in the phase space structure leading to chaotic behavior
Lattice regularized chiral perturbation theory
International Nuclear Information System (INIS)
Borasoy, Bugra; Lewis, Randy; Ouimet, Pierre-Philippe A.
2004-01-01
Chiral perturbation theory can be defined and regularized on a spacetime lattice. A few motivations are discussed here, and an explicit lattice Lagrangian is reviewed. A particular aspect of the connection between lattice chiral perturbation theory and lattice QCD is explored through a study of the Wess-Zumino-Witten term
CERN. Geneva
2013-01-01
Perturbative QCD is the general theoretical framework for describing hard scattering processes yielding multiparticle production at hadron colliders. In these lectures, we shall introduce fundamental features of perturbative QCD and describe its application to several high energy collider processes, including jet production in electron-positron annihilation, deep inelastic scattering, Higgs boson and gauge boson production at the LHC.
Propagation of Ion Acoustic Perturbations
DEFF Research Database (Denmark)
Pécseli, Hans
1975-01-01
Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered.......Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered....
On summation of perturbation expansions
International Nuclear Information System (INIS)
Horzela, A.
1985-04-01
The problem of the restoration of physical quantities defined by divergent perturbation expansions is analysed. The Pad'e and Borel summability is proved for alternating perturbation expansions with factorially growing coefficients. The proof is based on the methods of the classical moments theory. 17 refs. (author)
Continual integral in perturbation theory
International Nuclear Information System (INIS)
Slavnov, A.A.
1975-01-01
It is shown that all results obtained by means of continual integration within the framework of perturbation theory are completely equivalent to those obtained by the usual diagram technique and are therfore just as rigorous. A rigorous justification is given for the rules for operating with continual integrals in perturbation theory. (author)
Cauchy-perturbative matching reexamined: Tests in spherical symmetry
International Nuclear Information System (INIS)
Zink, Burkhard; Pazos, Enrique; Diener, Peter; Tiglio, Manuel
2006-01-01
During the last few years progress has been made on several fronts making it possible to revisit Cauchy-perturbative matching (CPM) in numerical relativity in a more robust and accurate way. This paper is the first in a series where we plan to analyze CPM in the light of these new results. One of the new developments is an understanding of how to impose constraint-preserving boundary conditions (CPBC); though most of the related research has been driven by outer boundaries, one can use them for matching interface boundaries as well. Another front is related to numerically stable evolutions using multiple patches, which in the context of CPM allows the matching to be performed on a spherical surface, thus avoiding interpolations between Cartesian and spherical grids. One way of achieving stability for such schemes of arbitrary high order is through the use of penalty techniques and discrete derivatives satisfying summation by parts (SBP). Recently, new, very efficient and high-order accurate derivatives satisfying SBP and associated dissipation operators have been constructed. Here we start by testing all these techniques applied to CPM in a setting that is simple enough to study all the ingredients in great detail: Einstein's equations in spherical symmetry, describing a black hole coupled to a massless scalar field. We show that with the techniques described above, the errors introduced by Cauchy-perturbative matching are very small, and that very long-term and accurate CPM evolutions can be achieved. Our tests include the accretion and ring-down phase of a Schwarzschild black hole with CPM, where we find that the discrete evolution introduces, with a low spatial resolution of Δr=M/10, an error of 0.3% after an evolution time of 1,000,000M. For a black hole of solar mass, this corresponds to approximately 5s, and is therefore at the lower end of timescales discussed e.g. in the collapsar model of gamma-ray burst engines
On dark energy isocurvature perturbation
International Nuclear Information System (INIS)
Liu, Jie; Zhang, Xinmin; Li, Mingzhe
2011-01-01
Determining the equation of state of dark energy with astronomical observations is crucially important to understand the nature of dark energy. In performing a likelihood analysis of the data, especially of the cosmic microwave background and large scale structure data the dark energy perturbations have to be taken into account both for theoretical consistency and for numerical accuracy. Usually, one assumes in the global fitting analysis that the dark energy perturbations are adiabatic. In this paper, we study the dark energy isocurvature perturbation analytically and discuss its implications for the cosmic microwave background radiation and large scale structure. Furthermore, with the current astronomical observational data and by employing Markov Chain Monte Carlo method, we perform a global analysis of cosmological parameters assuming general initial conditions for the dark energy perturbations. The results show that the dark energy isocurvature perturbations are very weakly constrained and that purely adiabatic initial conditions are consistent with the data
Large-scale density structures in the outer heliosphere
Belcher, J. W.; Lazarus, A. J.; Mcnutt, R. L., Jr.; Gordon, G. S., Jr.
1993-01-01
The Plasma Science experiment on the Voyager 2 spacecraft has measured the solar wind density from 1 to 38 AU. Over this distance, the solar wind density decreases as the inverse square of the heliocentric distance. However, there are large variations in this density at a given radius. Such changes in density are the dominant cause of changes in the solar wind ram pressure in the outer heliosphere and can cause large perturbations in the location of the termination shock of the solar wind. Following a simple model suggested by Suess, we study the non-equilibrium, dynamic location of the termination shock as it responds to these pressure changes. The results of this study suggest that the termination shock is rarely if ever at its equilibrium distance and may depart from that distance by as much as 50 AU at times.
Geometry of perturbed Gaussian states and quantum estimation
International Nuclear Information System (INIS)
Genoni, Marco G; Giorda, Paolo; Paris, Matteo G A
2011-01-01
We address the non-Gaussianity (nG) of states obtained by weakly perturbing a Gaussian state and investigate the relationships with quantum estimation. For classical perturbations, i.e. perturbations to eigenvalues, we found that the nG of the perturbed state may be written as the quantum Fisher information (QFI) distance minus a term depending on the infinitesimal energy change, i.e. it provides a lower bound to statistical distinguishability. Upon moving on isoenergetic surfaces in a neighbourhood of a Gaussian state, nG thus coincides with a proper distance in the Hilbert space and exactly quantifies the statistical distinguishability of the perturbations. On the other hand, for perturbations leaving the covariance matrix unperturbed, we show that nG provides an upper bound to the QFI. Our results show that the geometry of non-Gaussian states in the neighbourhood of a Gaussian state is definitely not trivial and cannot be subsumed by a differential structure. Nevertheless, the analysis of perturbations to a Gaussian state reveals that nG may be a resource for quantum estimation. The nG of specific families of perturbed Gaussian states is analysed in some detail with the aim of finding the maximally non-Gaussian state obtainable from a given Gaussian one. (fast track communication)
Improved method of measurement for outer leak
International Nuclear Information System (INIS)
Xu Guang
2012-01-01
Pneumatic pipeline is installed for the airborne radioactivity measurement equipment, air tightness and outer leak rate are essential for the testing of the characteristics, both in the national criteria and ISO standards, an improved practical method is available for the measurement of the outer air leak rate based on the engineering experiences for the equipment acceptance and testing procedure. (authors)
Infrared problems in field perturbation theory
International Nuclear Information System (INIS)
David, Francois.
1982-12-01
The work presented mainly covers questions related to the presence of ''infrared'' divergences in perturbation expansions of the Green functions of certain massless field theories. It is important to determine the mathematical status of perturbation expansions in field theory in order to define the region in which they are valid. Renormalization and the symmetry of a theory are important factors in infrared problems. The main object of this thesis resides in the mathematical techniques employed: integral representations of the Feynman amplitudes; methods for desingularization, regularization and dimensional renormalization. Nonlinear two dimensional space-time sigma models describing Goldstone's low energy boson dynamics associated with a breaking of continuous symmetry are studied. Random surface models are then investigated followed by infrared divergences in super-renormalizable theories. Finally, nonperturbation effects in massless theories are studied by expanding the two-dimensional nonlinear sigma model in 1/N [fr
Disformal transformation of cosmological perturbations
Directory of Open Access Journals (Sweden)
Masato Minamitsuji
2014-10-01
Full Text Available We investigate the gauge-invariant cosmological perturbations in the gravity and matter frames in the general scalar–tensor theory where two frames are related by the disformal transformation. The gravity and matter frames are the extensions of the Einstein and Jordan frames in the scalar–tensor theory where two frames are related by the conformal transformation, respectively. First, it is shown that the curvature perturbation in the comoving gauge to the scalar field is disformally invariant as well as conformally invariant, which gives the predictions from the cosmological model where the scalar field is responsible both for inflation and cosmological perturbations. Second, in case that the disformally coupled matter sector also contributes to curvature perturbations, we derive the evolution equations of the curvature perturbation in the uniform matter energy density gauge from the energy (nonconservation in the matter sector, which are independent of the choice of the gravity sector. While in the matter frame the curvature perturbation in the uniform matter energy density gauge is conserved on superhorizon scales for the vanishing nonadiabatic pressure, in the gravity frame it is not conserved even if the nonadiabatic pressure vanishes. The formula relating two frames gives the amplitude of the curvature perturbation in the matter frame, once it is evaluated in the gravity frame.
Disformal transformation of cosmological perturbations
International Nuclear Information System (INIS)
Minamitsuji, Masato
2014-01-01
We investigate the gauge-invariant cosmological perturbations in the gravity and matter frames in the general scalar–tensor theory where two frames are related by the disformal transformation. The gravity and matter frames are the extensions of the Einstein and Jordan frames in the scalar–tensor theory where two frames are related by the conformal transformation, respectively. First, it is shown that the curvature perturbation in the comoving gauge to the scalar field is disformally invariant as well as conformally invariant, which gives the predictions from the cosmological model where the scalar field is responsible both for inflation and cosmological perturbations. Second, in case that the disformally coupled matter sector also contributes to curvature perturbations, we derive the evolution equations of the curvature perturbation in the uniform matter energy density gauge from the energy (non)conservation in the matter sector, which are independent of the choice of the gravity sector. While in the matter frame the curvature perturbation in the uniform matter energy density gauge is conserved on superhorizon scales for the vanishing nonadiabatic pressure, in the gravity frame it is not conserved even if the nonadiabatic pressure vanishes. The formula relating two frames gives the amplitude of the curvature perturbation in the matter frame, once it is evaluated in the gravity frame
International Nuclear Information System (INIS)
Mazzeo, D.; Oliveti, G.; Arcuri, N.
2016-01-01
Highlights: • Dynamic thermal behaviour of building walls subjected to actual periodic loadings. • Dynamic parameters of wall in terms of energy and of heat flux are defined. • Different solar absorption coefficients and orientations of wall are considered. • On the internal surface is present or absent a shortwave radiant field. • Seasonal thermal characteristics for different plant operating regime are provided. - Abstract: In this work, the dynamic characteristics of the external walls of air-conditioned buildings subject to the joint action of periodic non-sinusoidal external and internal loadings are determined. The dynamic parameters used are the energy decrement factor, which is evaluated by means of the fluctuating heat flux in a semi-period exiting and entering the wall, the decrement factor of the maximum peak and minimum peak of the heat flux in a period and the relative time lags. The fluctuating heat flux in the wall in steady periodic regime conditions is determined with an analytical model obtained by resolving the equivalent electrical circuit. The preceding parameters are used for a study of the influence of solar radiation on the dynamic characteristics of the walls in summer and winter air-conditioning. Solar radiation is considered as operating on the external surface and on the internal surface due to the presence in the indoor environments of a shortwave radiant field. The absorbed solar heat flux by the external surface varies, modifying the solar absorption coefficient and wall orientation. Indoors, we considered a continuous operating regime of the plant and a regime with nocturnal attenuation. The results obtained, relating to 1152 different boundary conditions, were used for the construction of maps of dynamic characteristics, different on variation of the plant functioning regime and of the shortwave radiant load on the internal surface. The maps show the dependence of the decrement factors and of the time lags on variation of
The Effects of Earth's Outer Core's Viscosity on Geodynamo Models
Dong, C.; Jiao, L.; Zhang, H.
2017-12-01
Geodynamo process is controlled by mathematic equations and input parameters. To study effects of parameters on geodynamo system, MoSST model has been used to simulate geodynamo outputs under different outer core's viscosity ν. With spanning ν for nearly three orders when other parameters fixed, we studied the variation of each physical field and its typical length scale. We find that variation of ν affects the velocity field intensely. The magnetic field almost decreases monotonically with increasing of ν, while the variation is no larger than 30%. The temperature perturbation increases monotonically with ν, but by a very small magnitude (6%). The averaged velocity field (u) of the liquid core increases with ν as a simple fitted scaling relation: u∝ν0.49. The phenomenon that u increases with ν is essentially that increasing of ν breaks the Taylor-Proudman constraint and drops the critical Rayleigh number, and thus u increases under the same thermal driving force. Forces balance is analyzed and balance mode shifts with variation of ν. When compared with former studies of scaling laws, this study supports the conclusion that in a certain parameter range, the magnetic field strength doesn't vary much with the viscosity, but opposes to the assumption that the velocity field has nothing to do with the outer core viscosity.
Functional Architecture of the Outer Arm Dynein Conformational Switch*
King, Stephen M.; Patel-King, Ramila S.
2012-01-01
Dynein light chain 1 (LC1/DNAL1) is one of the most highly conserved components of ciliary axonemal outer arm dyneins, and it associates with both a heavy chain motor unit and tubulin located within the A-tubule of the axonemal outer doublet microtubules. In a variety of model systems, lack of LC1 or expression of mutant forms leads to profound defects in ciliary motility, including the failure of the hydrodynamic coupling needed for ciliary metachronal synchrony, random stalling during the power/recovery stroke transition, an aberrant response to imposed viscous load, and in some cases partial failure of motor assembly. These phenotypes have led to the proposal that LC1 acts as part of a mechanical switch to control motor function in response to alterations in axonemal curvature. Here we have used NMR chemical shift mapping to define the regions perturbed by a series of mutations in the C-terminal domain that yield a range of phenotypic effects on motility. In addition, we have identified the subdomain of LC1 involved in binding microtubules and characterized the consequences of an Asn → Ser alteration within the terminal leucine-rich repeat that in humans causes primary ciliary dyskinesia. Together, these data define a series of functional subdomains within LC1 and allow us to propose a structural model for the organization of the dynein heavy chain-LC1-microtubule ternary complex that is required for the coordinated activity of dynein motors in cilia. PMID:22157010
Milosevic, Matija; Shinya, Masahiro; Masani, Kei; Patel, Kramay; McConville, Kristiina M V; Nakazawa, Kimitaka; Popovic, Milos R
2016-02-01
Trunk muscles are responsible for maintaining trunk stability during sitting. However, the effects of anticipation of perturbation on trunk muscle responses are not well understood. The objectives of this study were to identify the responses of trunk muscles to sudden support surface translations and quantify the effects of anticipation of direction and time of perturbation on the trunk neuromuscular responses. Twelve able-bodied individuals participated in the study. Participants were seated on a kneeling chair and support surface translations were applied in the forward and backward directions with and without direction and time of perturbation cues. The trunk started moving on average approximately 40ms after the perturbation. During unanticipated perturbations, average latencies of the trunk muscle contractions were in the range between 103.4 and 117.4ms. When participants anticipated the perturbations, trunk muscle latencies were reduced by 16.8±10.0ms and the time it took the trunk to reach maximum velocity was also reduced, suggesting a biomechanical advantage caused by faster muscle responses. These results suggested that trunk muscles have medium latency responses and use reflexive mechanisms. Moreover, anticipation of perturbation decreased trunk muscles latencies, suggesting that the central nervous system modulated readiness of the trunk based on anticipatory information. Copyright © 2015 Elsevier Ltd. All rights reserved.
Cosmological perturbations beyond linear order
CERN. Geneva
2013-01-01
Cosmological perturbation theory is the standard tool to understand the formation of the large scale structure in the Universe. However, its degree of applicability is limited by the growth of the amplitude of the matter perturbations with time. This problem can be tackled with by using N-body simulations or analytical techniques that go beyond the linear calculation. In my talk, I'll summarise some recent efforts in the latter that ameliorate the bad convergence of the standard perturbative expansion. The new techniques allow better analytical control on observables (as the matter power spectrum) over scales very relevant to understand the expansion history and formation of structure in the Universe.
Instabilities in mimetic matter perturbations
Energy Technology Data Exchange (ETDEWEB)
Firouzjahi, Hassan; Gorji, Mohammad Ali [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Mansoori, Seyed Ali Hosseini, E-mail: firouz@ipm.ir, E-mail: gorji@ipm.ir, E-mail: shosseini@shahroodut.ac.ir, E-mail: shossein@ipm.ir [Physics Department, Shahrood University of Technology, P.O. Box 3619995161 Shahrood (Iran, Islamic Republic of)
2017-07-01
We study cosmological perturbations in mimetic matter scenario with a general higher derivative function. We calculate the quadratic action and show that both the kinetic term and the gradient term have the wrong sings. We perform the analysis in both comoving and Newtonian gauges and confirm that the Hamiltonians and the associated instabilities are consistent with each other in both gauges. The existence of instabilities is independent of the specific form of higher derivative function which generates gradients for mimetic field perturbations. It is verified that the ghost instability in mimetic perturbations is not associated with the higher derivative instabilities such as the Ostrogradsky ghost.
Perturbation theory of effective Hamiltonians
International Nuclear Information System (INIS)
Brandow, B.H.
1975-01-01
This paper constitutes a review of the many papers which have used perturbation theory to derive ''effective'' or ''model'' Hamiltonians. It begins with a brief review of nondegenerate and non-many-body perturbation theory, and then considers the degenerate but non-many-body problem in some detail. It turns out that the degenerate perturbation problem is not uniquely defined, but there are some practical criteria for choosing among the various possibilities. Finally, the literature dealing with the linked-cluster aspects of open-shell many-body systems is reviewed. (U.S.)
The theory of singular perturbations
De Jager, E M
1996-01-01
The subject of this textbook is the mathematical theory of singular perturbations, which despite its respectable history is still in a state of vigorous development. Singular perturbations of cumulative and of boundary layer type are presented. Attention has been given to composite expansions of solutions of initial and boundary value problems for ordinary and partial differential equations, linear as well as quasilinear; also turning points are discussed. The main emphasis lies on several methods of approximation for solutions of singularly perturbed differential equations and on the mathemat
The power of perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Serone, Marco [SISSA International School for Advanced Studies and INFN Trieste, Via Bonomea 265, 34136, Trieste (Italy); Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste (Italy); Spada, Gabriele [SISSA International School for Advanced Studies and INFN Trieste, Via Bonomea 265, 34136, Trieste (Italy); Villadoro, Giovanni [Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste (Italy)
2017-05-10
We study quantum mechanical systems with a discrete spectrum. We show that the asymptotic series associated to certain paths of steepest-descent (Lefschetz thimbles) are Borel resummable to the full result. Using a geometrical approach based on the Picard-Lefschetz theory we characterize the conditions under which perturbative expansions lead to exact results. Even when such conditions are not met, we explain how to define a different perturbative expansion that reproduces the full answer without the need of transseries, i.e. non-perturbative effects, such as real (or complex) instantons. Applications to several quantum mechanical systems are presented.
Incorporation of squalene into rod outer segments
International Nuclear Information System (INIS)
Keller, R.K.; Fliesler, S.J.
1990-01-01
We have reported previously that squalene is the major radiolabeled nonsaponifiable lipid product derived from [ 3 H]acetate in short term incubations of frog retinas. In the present study, we demonstrate that newly synthesized squalene is incorporated into rod outer segments under similar in vitro conditions. We show further that squalene is an endogenous constituent of frog rod outer segment membranes; its concentration is approximately 9.5 nmol/mumol of phospholipid or about 9% of the level of cholesterol. Pulse-chase experiments with radiolabeled precursors revealed no metabolism of outer segment squalene to sterols in up to 20 h of chase. Taken together with our previous absolute rate studies, these results suggest that most, if not all, of the squalene synthesized by the frog retina is transported to rod outer segments. Synthesis of protein is not required for squalene transport since puromycin had no effect on squalene incorporation into outer segments. Conversely, inhibition of isoprenoid synthesis with mevinolin had no effect on the incorporation of opsin into the outer segment. These latter results support the conclusion that the de novo synthesis and subsequent intracellular trafficking of opsin and isoprenoid lipids destined for the outer segment occur via independent mechanisms
Pressure-driven amplification and penetration of resonant magnetic perturbations
Energy Technology Data Exchange (ETDEWEB)
Loizu, J. [Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald (Germany); Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States); Hudson, S. R.; Lazerson, S. A.; Bhattacharjee, A. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States); Helander, P. [Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald (Germany)
2016-05-15
We show that a resonant magnetic perturbation applied to the boundary of an ideal plasma screw-pinch equilibrium with nested surfaces can penetrate inside the resonant surface and into the core. The response is significantly amplified with increasing plasma pressure. We present a rigorous verification of nonlinear equilibrium codes against linear theory, showing excellent agreement.
Tunnelling instability via perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Graffi, S. (Bologna Univ. (Italy). Dip. di Matematica); Grecchi, V. (Moderna Univ. (Italy). Dip. di Matematica); Jona-Lasinio, G. (Paris-11 Univ., 91 - Orsay (France). Lab. de Physique Theorique et Hautes Energies)
1984-10-21
The semiclassical limit of low lying states in a multiwell potential is studied by rigorous perturbative techniques. In particular tunnelling instability and localisation of wave functions is obtained in a simple way under small deformations of symmetric potentials.
Perturbation theory of quantum resonances
Czech Academy of Sciences Publication Activity Database
Durand, P.; Paidarová, Ivana
2016-01-01
Roč. 135, č. 7 (2016), s. 159 ISSN 1432-2234 Institutional support: RVO:61388955 Keywords : Partitioning technique * Analytic continuation * Perturbative expansion Subject RIV: CF - Physical ; Theoretical Chemistry
Perturbation Theory of Embedded Eigenvalues
DEFF Research Database (Denmark)
Engelmann, Matthias
project gives a general and systematic approach to analytic perturbation theory of embedded eigenvalues. The spectral deformation technique originally developed in the theory of dilation analytic potentials in the context of Schrödinger operators is systematized by the use of Mourre theory. The group...... of dilations is thereby replaced by the unitary group generated y the conjugate operator. This then allows to treat the perturbation problem with the usual Kato theory.......We study problems connected to perturbation theory of embedded eigenvalues in two different setups. The first part deals with second order perturbation theory of mass shells in massive translation invariant Nelson type models. To this end an expansion of the eigenvalues w.r.t. fiber parameter up...
Perturbative tests of quantum chromodynamics
International Nuclear Information System (INIS)
Michael, C.
1978-01-01
A review is given of perturbation theory results for quantum chromodynamics and of tests in deep inelastic lepton scattering, electron-positron annihilation, hadronic production of massive dileptons and hadronic large-momentum-transfer processes. (author)
Large-order perturbation theory
International Nuclear Information System (INIS)
Wu, T.T.
1982-01-01
The original motivation for studying the asymptotic behavior of the coefficients of perturbation series came from quantum field theory. An overview is given of some of the attempts to understand quantum field theory beyond finite-order perturbation series. At least is the case of the Thirring model and probably in general, the full content of a relativistic quantum field theory cannot be recovered from its perturbation series. This difficulty, however, does not occur in quantum mechanics, and the anharmonic oscillator is used to illustrate the methods used in large-order perturbation theory. Two completely different methods are discussed, the first one using the WKB approximation, and a second one involving the statistical analysis of Feynman diagrams. The first one is well developed and gives detailed information about the desired asymptotic behavior, while the second one is still in its infancy and gives instead information about the distribution of vertices of the Feynman diagrams
Review of chiral perturbation theory
Indian Academy of Sciences (India)
Abstract. A review of chiral perturbation theory and recent developments on the comparison of its predictions with experiment is presented. Some interesting topics with scope for further elaboration are touched upon.
Small RNAs controlling outer membrane porins
DEFF Research Database (Denmark)
Valentin-Hansen, Poul; Johansen, Jesper; Rasmussen, Anders A
2007-01-01
are key regulators of environmental stress. Recent work has revealed an intimate interplay between small RNA regulation of outer membrane proteins and the stress-induced sigmaE-signalling system, which has an essential role in the maintenance of the integrity of the outer membrane.......Gene regulation by small non-coding RNAs has been recognized as an important post-transcriptional regulatory mechanism for several years. In Gram-negative bacteria such as Escherichia coli and Salmonella, these RNAs control stress response and translation of outer membrane proteins and therefore...
Perturbation theory in light-cone gauge
International Nuclear Information System (INIS)
Vianello, Eliana
2000-01-01
Perturbation calculations are presented for the light-cone gauge Schwinger model. Eigenstates can be calculated perturbatively but the perturbation theory is nonstandard. We hope to extend the work to QCD 2 to resolve some outstanding issues in those theories
Outer brain barriers in rat and human development
DEFF Research Database (Denmark)
Brøchner, Christian B; Holst, Camilla Bjørnbak; Møllgård, Kjeld
2015-01-01
Complex barriers at the brain's surface, particularly in development, are poorly defined. In the adult, arachnoid blood-cerebrospinal fluid (CSF) barrier separates the fenestrated dural vessels from the CSF by means of a cell layer joined by tight junctions. Outer CSF-brain barrier provides...... diffusion restriction between brain and subarachnoid CSF through an initial radial glial end feet layer covered with a pial surface layer. To further characterize these interfaces we examined embryonic rat brains from E10 to P0 and forebrains from human embryos and fetuses (6-21st weeks post...
Students’ misconceptions about Newton's second law in outer space
International Nuclear Information System (INIS)
Temiz, B K; Yavuz, A
2014-01-01
Students’ misconceptions about Newton's second law in frictionless outer space were investigated. The research was formed according to an epistemic game theoretical framework. The term ‘epistemic’ refers to students’ participation in problem-solving activities as a means of constructing new knowledge. The term ‘game’ refers to a coherent activity that consists of moves and rules. A set of questions in which students are asked to solve two similar Newton's second law problems, one of which is on the Earth and the other in outer space, was administered to 116 undergraduate students. The findings indicate that there is a significant difference between students’ epistemic game preferences and race-type (outer space or frictional surface) question. So students who used Newton's second law on the ground did not apply this law and used primitive reasoning when it came to space. Among these students, voluntary interviews were conducted with 18 students. Analysis of interview transcripts showed that: (1) the term ‘space’ causes spontaneity among students that prevents the use of the law; (2) students hesitate to apply Newton's second law in space due to the lack of a condition—the friction; (3) students feel that Newton's second law is not valid in space for a variety of reasons, but mostly for the fact that the body in space is not in contact with a surface. (paper)
Boundary Layer Instabilities Generated by Freestream Laser Perturbations
Chou, Amanda; Schneider, Steven P.
2015-01-01
A controlled, laser-generated, freestream perturbation was created in the freestream of the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT). The freestream perturbation convected downstream in the Mach-6 wind tunnel to interact with a flared cone model. The geometry of the flared cone is a body of revolution bounded by a circular arc with a 3-meter radius. Fourteen PCB 132A31 pressure transducers were used to measure a wave packet generated in the cone boundary layer by the freestream perturbation. This wave packet grew large and became nonlinear before experiencing natural transition in quiet flow. Breakdown of this wave packet occurred when the amplitude of the pressure fluctuations was approximately 10% of the surface pressure for a nominally sharp nosetip. The initial amplitude of the second mode instability on the blunt flared cone is estimated to be on the order of 10 -6 times the freestream static pressure. The freestream laser-generated perturbation was positioned upstream of the model in three different configurations: on the centerline, offset from the centerline by 1.5 mm, and offset from the centerline by 3.0 mm. When the perturbation was offset from the centerline of a blunt flared cone, a larger wave packet was generated on the side toward which the perturbation was offset. The offset perturbation did not show as much of an effect on the wave packet on a sharp flared cone as it did on a blunt flared cone.
A hybrid perturbation-Galerkin technique for partial differential equations
Geer, James F.; Anderson, Carl M.
1990-01-01
A two-step hybrid perturbation-Galerkin technique for improving the usefulness of perturbation solutions to partial differential equations which contain a parameter is presented and discussed. In the first step of the method, the leading terms in the asymptotic expansion(s) of the solution about one or more values of the perturbation parameter are obtained using standard perturbation methods. In the second step, the perturbation functions obtained in the first step are used as trial functions in a Bubnov-Galerkin approximation. This semi-analytical, semi-numerical hybrid technique appears to overcome some of the drawbacks of the perturbation and Galerkin methods when they are applied by themselves, while combining some of the good features of each. The technique is illustrated first by a simple example. It is then applied to the problem of determining the flow of a slightly compressible fluid past a circular cylinder and to the problem of determining the shape of a free surface due to a sink above the surface. Solutions obtained by the hybrid method are compared with other approximate solutions, and its possible application to certain problems associated with domain decomposition is discussed.
High-order perturbations of a spherical collapsing star
International Nuclear Information System (INIS)
Brizuela, David; Martin-Garcia, Jose M.; Sperhake, Ulrich; Kokkotas, Kostas D.
2010-01-01
A formalism to deal with high-order perturbations of a general spherical background was developed in earlier work [D. Brizuela, J. M. Martin-Garcia, and G. A. Mena Marugan, Phys. Rev. D 74, 044039 (2006); D. Brizuela, J. M. Martin-Garcia, and G. A. Mena Marugan, Phys. Rev. D 76, 024004 (2007)]. In this paper, we apply it to the particular case of a perfect fluid background. We have expressed the perturbations of the energy-momentum tensor at any order in terms of the perturbed fluid's pressure, density, and velocity. In general, these expressions are not linear and have sources depending on lower-order perturbations. For the second-order case we make the explicit decomposition of these sources in tensor spherical harmonics. Then, a general procedure is given to evolve the perturbative equations of motions of the perfect fluid for any value of the harmonic label. Finally, with the problem of a spherical collapsing star in mind, we discuss the high-order perturbative matching conditions across a timelike surface, in particular, the surface separating the perfect fluid interior from the exterior vacuum.
Xiao, W W; Evans, T E; Tynan, G R; Yoon, S W; Jeon, Y M; Ko, W H; Nam, Y U; Oh, Y K
2017-11-17
The propagation dynamics of resonant magnetic perturbation fields in KSTAR H-mode plasmas with injection of small edge perturbations produced by a supersonic molecular beam injection is reported for the first time. The results show that the perturbation field first excites a plasma response on the q=3 magnetic surface and then propagates inward to the q=2 surface with a radially averaged propagation velocity of resonant magnetic perturbations field equal to 32.5 m/ s. As a result, the perturbation field brakes the toroidal rotation on the q=3 surface first causing a momentum transport perturbation that propagates both inward and outward. A higher density fluctuation level is observed. The propagation velocity of the resonant magnetic perturbations field is larger than the radial propagation velocity of the perturbation in the toroidal rotation.
Outer Magnetospheric Boundaries Cluster Results
Paschmann, Goetz; Schwartz, S J
2006-01-01
When the stream of plasma emitted from the Sun (the solar wind) encounters Earth's magnetic field, it slows down and flows around it, leaving behind a cavity, the magnetosphere. The magnetopause is the surface that separates the solar wind on the outside from the Earth's magnetic field on the inside. Because the solar wind moves at supersonic speed, a bow shock must form ahead of the magnetopause that acts to slow the solar wind to subsonic speeds. Magnetopause, bow shock and their environs are rich in exciting processes in collisionless plasmas, such as shock formation, magnetic reconnection, particle acceleration and wave-particle interactions. They are interesting in their own right, as part of Earth's environment, but also because they are prototypes of similar structures and phenomena that are ubiquitous in the universe, having the unique advantage that they are accessible to in situ measurements. The boundaries of the magnetosphere have been the target of direct in-situ measurements since the beginning ...
Base case and perturbation scenarios
Energy Technology Data Exchange (ETDEWEB)
Edmunds, T
1998-10-01
This report describes fourteen energy factors that could affect electricity markets in the future (demand, process, source mix, etc.). These fourteen factors are believed to have the most influence on the State's energy environment. A base case, or most probable, characterization is given for each of these fourteen factors over a twenty year time horizon. The base case characterization is derived from quantitative and qualitative information provided by State of California government agencies, where possible. Federal government databases are nsed where needed to supplement the California data. It is envisioned that a initial selection of issue areas will be based upon an evaluation of them under base case conditions. For most of the fourteen factors, the report identities possible perturbations from base case values or assumptions that may be used to construct additional scenarios. Only those perturbations that are plausible and would have a significant effect on energy markets are included in the table. The fourteen factors and potential perturbations of the factors are listed in Table 1.1. These perturbations can be combined to generate internally consist.ent. combinations of perturbations relative to the base case. For example, a low natural gas price perturbation should be combined with a high natural gas demand perturbation. The factor perturbations are based upon alternative quantitative forecasts provided by other institutions (the Department of Energy - Energy Information Administration in some cases), changes in assumptions that drive the quantitative forecasts, or changes in assumptions about the structure of the California energy markets. The perturbations are intended to be used for a qualitative reexamination of issue areas after an initial evaluation under the base case. The perturbation information would be used as a "tiebreaker;" to make decisions regarding those issue areas that were marginally accepted or rejected under the base case. Hf a
Perturbation theory in large order
International Nuclear Information System (INIS)
Bender, C.M.
1978-01-01
For many quantum mechanical models, the behavior of perturbation theory in large order is strikingly simple. For example, in the quantum anharmonic oscillator, which is defined by -y'' + (x 2 /4 + ex 4 /4 - E) y = 0, y ( +- infinity) = 0, the perturbation coefficients, A/sub n/, in the expansion for the ground-state energy, E(ground state) approx. EPSILON/sub n = 0//sup infinity/ A/sub n/epsilon/sup n/, simplify dramatically as n → infinity: A/sub n/ approx. (6/π 3 )/sup 1/2/(-3)/sup n/GAMMA(n + 1/2). Methods of applied mathematics are used to investigate the nature of perturbation theory in quantum mechanics and show that its large-order behavior is determined by the semiclassical content of the theory. In quantum field theory the perturbation coefficients are computed by summing Feynman graphs. A statistical procedure in a simple lambda phi 4 model for summing the set of all graphs as the number of vertices → infinity is presented. Finally, the connection between the large-order behavior of perturbation theory in quantum electrodynamics and the value of α, the charge on the electron, is discussed. 7 figures
Colours of the Outer Solar System Origins Survey: An Update
Schwamb, Megan E.; Fraser, Wesley C.; Pike, Rosemary E.; Bannister, Michele T.; Marsset, Michaël; Kavelaars, J. J.; Benecchi, Susan; Delsanti, Audrey C.; Lehner, Matthew J.; Wang, Shiang-Yu; Thirouin, Audrey; Nesvorný, David
2018-01-01
The vast majority of the known dwarf-planet sized bodies are bright enough to be studied through optical and infrared spectroscopy. As a result, we have an understanding of the surface properties for the largest Kuiper belt objects (KBOs) which retain their primordial inventory of volatile ices. For the typically smaller > 22 mag KBO, we must rely instead on what colors reveal by proxy; yet this picture remains incomplete. Most KBO physical property studies examine the hodgepodge set of objects discovered by various surveys with different and varying detection biases that make it difficult if not impossible to reliably estimate the sizes of the different surface color groupings (compositional classes) residing in the modern-day Kuiper belt.The Colours of the Outer Solar System Origins Survey (Col-OSSOS) probes the surface properties within the Kuiper belt primarily through near simultaneous g,r and J colors with the Gemini North Telescope and u-band with Canada-France-Hawaii Telescope. The project aims to target ~100 KBOs brighter than 23.6 r‧ mag found by the Outer Solar System Origins Survey (OSSOS), a survey with a well-measured detection efficiency. Thus, Col-OSSOS provides the first brightness-complete, compositional-dynamical map of the Outer Solar System, probing in a new light the radial color distribution in the primordial planetesimal disk from which KBOs originated. We will provide an update on the current status of the program highlighting results from the first two years of the survey; including size estimates of the two color KBO subgroups (the red and neutral surfaces) within the dynamically excited Kuiper belt and implications for the early planetesimal disk composition based on neutral-colored binaries found in the cold classical Kuiper belt.
Water and Volatiles in the Outer Solar System
Grasset, O.; Castillo-Rogez, J.; Guillot, T.; Fletcher, L. N.; Tosi, F.
2017-10-01
Space exploration and ground-based observations have provided outstanding evidence of the diversity and the complexity of the outer solar system. This work presents our current understanding of the nature and distribution of water and water-rich materials from the water snow line to the Kuiper Belt. This synthesis is timely, since a thorough exploration of at least one object in each region of the outer solar system has now been achieved. Next steps, starting with the Juno mission now in orbit around Jupiter, will be more focused on understanding the processes at work than on describing the general characteristics of each giant planet systems. This review is organized in three parts. First, the nature and the distribution of water and volatiles in giant and intermediary planets are described from their inner core to their outer envelopes. A special focus is given to Jupiter and Saturn, which are much better understood than the two ice giants (Uranus and Neptune) thanks to the Galileo and Cassini missions. Second, the icy moons will be discussed. Space missions and ground-based observations have revealed the variety of icy surfaces in the outer system. While Europa, Enceladus, and maybe Titan present past or even active tectonic and volcanic activities, many other moons have been dead worlds for more than 3 billion years. Ice compositions found at these bodies are also complex and it is now commonly admitted that icy surfaces are never composed of pure ices. A detailed review of the distribution of non-ice materials on the surfaces and in the tenuous atmospheres of the moons is proposed, followed by a more focused discussion on the nature and the characteristics of the liquid layers trapped below the cold icy crusts that have been suggested in the icy Galilean moons, and in Enceladus, Dione, and Titan at Saturn. Finally, the recent observations collected by Dawn at Ceres and New Horizons at Pluto, as well as the state of knowledge of other transneptunian objects
Oscillations of the Outer Boundary of the Outer Radiation Belt During Sawtooth Oscillations
Directory of Open Access Journals (Sweden)
Jae-Hun Kim
2006-09-01
Full Text Available We report three sawtooth oscillation events observed at geosynchronous orbit where we find quasi-periodic (every 2-3 hours sudden flux increases followed by slow flux decreases at the energy levels of ˜50-400 keV. For these three sawtooth events, we have examined variations of the outer boundary of the outer radiation belt. In order to determine L values of the outer boundary, we have used data of relativistic electron flux observed by the SAMPEX satellite. We find that the outer boundary of the outer radiation belt oscillates periodically being consistent with sawtooth oscillation phases. Specifically, the outer boundary of the outer radiation belt expands (namely, the boundary L value increases following the sawtooth particle flux enhancement of each tooth, and then contracts (namely, the boundary L value decreases while the sawtooth flux decreases gradually until the next flux enhancement. On the other hand, it is repeatedly seen that the asymmetry of the magnetic field intensity between dayside and nightside decreases (increases due to the dipolarization (the stretching on the nightside as the sawtooth flux increases (decreases. This implies that the periodic magnetic field variations during the sawtooth oscillations are likely responsible for the expansion-contraction oscillations of the outer boundary of the outer radiation belt.
Perturbations of the Friedmann universe
International Nuclear Information System (INIS)
Novello, M.; Salim, J.M.; Heintzmann, H.
1982-01-01
Correcting and extending previous work by Hawking (1966) and Olson (1976) the complete set of perturbation equations of a Friedmann Universe in the quasi-Maxwellian form is derived and analized. The formalism is then applied to scalar, vector and tensor perturbations of a phenomenological fluid, which is modelled such as to comprise shear and heat flux. Depending on the equation of state of the background it is found that there exist unstable (growing) modes of purely rotational character. It is further found that (to linear order at least) any vortex perturbation is equivalent to a certain heat flux vector. The equation for the gravitational waves are derived in a completely equivalent method as in case of the propagation, in a curved space-time, of electromagnetic waves in a plasma endowed with some definite constitutive relations. (Author) [pt
Analytic continuation in perturbative QCD
International Nuclear Information System (INIS)
Caprini, Irinel
2002-01-01
We discuss some attempts to improve standard perturbative expansion in QCD by using the analytic continuation in the momentum and the Borel complex planes. We first analyse the momentum-plane analyticity properties of the Borel-summed Green functions in perturbative QCD and the connection between the Landau singularities and the infrared renormalons. By using the analytic continuation in the Borel complex plane, we propose a new perturbative series replacing the standard expansion in powers of the normalized coupling constant a. The new expansion functions have branch point and essential singularities at the origin of the complex a-plane and divergent Taylor expansions in powers of a. On the other hand the modified expansion of the QCD correlators is convergent under rather conservative conditions. (author)
Perturbative coherence in field theory
International Nuclear Information System (INIS)
Aldrovandi, R.; Kraenkel, R.A.
1987-01-01
A general condition for coherent quantization by perturbative methods is given, because the basic field equations of a fild theory are not always derivable from a Lagrangian. It's seen that non-lagrangian models way have well defined vertices, provided they satisfy what they call the 'coherence condition', which is less stringent than the condition for the existence of a Lagrangian. They note that Lagrangian theories are perturbatively coherent, in the sense that they have well defined vertices, and that they satisfy automatically that condition. (G.D.F.) [pt
Cosmological perturbation theory and quantum gravity
Energy Technology Data Exchange (ETDEWEB)
Brunetti, Romeo [Dipartimento di Matematica, Università di Trento,Via Sommarive 14, 38123 Povo TN (Italy); Fredenhagen, Klaus [II Institute für Theoretische Physik, Universität Hamburg,Luruper Chaussee 149, 22761 Hamburg (Germany); Hack, Thomas-Paul [Institute für Theoretische Physik, Universität Leipzig,Brüderstr. 16, 04103 Leipzig (Germany); Pinamonti, Nicola [Dipartimento di Matematica, Università di Genova,Via Dodecaneso 35, 16146 Genova (Italy); INFN, Sezione di Genova,Via Dodecaneso 33, 16146 Genova (Italy); Rejzner, Katarzyna [Department of Mathematics, University of York,Heslington, York YO10 5DD (United Kingdom)
2016-08-04
It is shown how cosmological perturbation theory arises from a fully quantized perturbative theory of quantum gravity. Central for the derivation is a non-perturbative concept of gauge-invariant local observables by means of which perturbative invariant expressions of arbitrary order are generated. In particular, in the linearised theory, first order gauge-invariant observables familiar from cosmological perturbation theory are recovered. Explicit expressions of second order quantities are presented as well.
Chaotic inflation with metric and matter perturbations
International Nuclear Information System (INIS)
Feldman, H.A.; Brandenberger, R.H.
1989-01-01
A perturbative scheme to analyze the evolution of both metric and scalar field perturbations in an expanding universe is developed. The scheme is applied to study chaotic inflation with initial metric and scalar field perturbations present. It is shown that initial gravitational perturbations with wavelength smaller than the Hubble radius rapidly decay. The metric simultaneously picks up small perturbations determined by the matter inhomogeneities. Both are frozen in once the wavelength exceeds the Hubble radius. (orig.)
Odd-parity perturbations of the self-similar LTB spacetime
Energy Technology Data Exchange (ETDEWEB)
Duffy, Emily M; Nolan, Brien C, E-mail: emilymargaret.duffy27@mail.dcu.ie, E-mail: brien.nolan@dcu.ie [School of Mathematical Sciences, Dublin City University, Glasnevin, Dublin 9 (Ireland)
2011-05-21
We consider the behaviour of odd-parity perturbations of those self-similar LemaItre-Tolman-Bondi spacetimes which admit a naked singularity. We find that a perturbation which evolves from initially regular data remains finite on the Cauchy horizon. Finiteness is demonstrated by considering the behaviour of suitable energy norms of the perturbation (and pointwise values of these quantities) on natural spacelike hypersurfaces. This result holds for a general choice of initial data and initial data surface. Finally, we examine the perturbed Weyl scalars in order to provide a physical interpretation of our results. Taken on its own, this result does not support cosmic censorship; however, a full perturbation of this spacetime would include even-parity perturbations, so we cannot conclude that this spacetime is stable to all linear perturbations.
Spheres of influence: Porphyromonas gingivalis outer membrane vesicles.
Gui, M J; Dashper, S G; Slakeski, N; Chen, Y-Y; Reynolds, E C
2016-10-01
Outer membrane vesicles (OMVs) are asymmetrical single bilayer membranous nanostructures produced by Gram-negative bacteria important for bacterial interaction with the environment. Porphyromonas gingivalis, a keystone pathogen associated with chronic periodontitis, produces OMVs that act as a virulence factor secretion system contributing to its pathogenicity. Despite their biological importance, the mechanisms of OMV biogenesis have not been fully elucidated. The ~14 times more curvature of the OMV membrane than cell outer membrane (OM) indicates that OMV biogenesis requires energy expenditure for significant curvature of the OMV membrane. In P. gingivalis, we propose that this may be achieved by upregulating the production of certain inner or outer leaflet lipids, which causes localized outward curvature of the OM. This results in selection of anionic lipopolysaccharide (A-LPS) and associated C-terminal domain (CTD) -family proteins on the outer surface due to their ability to accommodate the curvature. Deacylation of A-LPS may further enable increased curvature leading to OMV formation. Porphyromonas gingivalis OMVs that are selectively enriched in CTD-family proteins, largely the gingipains, can support bacterial coaggregation, promote biofilm development and act as an intercessor for the transport of non-motile bacteria by motile bacteria. The P. gingivalis OMVs are also believed to contribute to host interaction and colonization, evasion of immune defense mechanisms, and destruction of periodontal tissues. They may be crucial for both micro- and macronutrient capture, especially heme and probably other assimilable compounds for its own benefit and that of the wider biofilm community. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Basics of QCD perturbation theory
International Nuclear Information System (INIS)
Soper, D.E.
1997-01-01
This is an introduction to the use of QCD perturbation theory, emphasizing generic features of the theory that enable one to separate short-time and long-time effects. The author also covers some important classes of applications: electron-positron annihilation to hadrons, deeply inelastic scattering, and hard processes in hadron-hadron collisions. 31 refs., 38 figs
Current issues in perturbative QCD
International Nuclear Information System (INIS)
Hinchliffe, I.
1994-12-01
This review talk discusses some issues of active research in perturbative QCD. The following topics are discussed: (1) current value of αs; (2) heavy quark production in hadron collisions; (3) production of Ψ and Υ in p anti p collisions; (4) prompt photon production; (5) small-x and related phenomena; and (6) particle multiplicity in heavy quark jets
New results in perturbative QCD
International Nuclear Information System (INIS)
Ellis, R.K.
1986-01-01
Three topics in perturbative QCD important for Super-collider physics are reviewed. The topics are: 1. (2 → 2) jet phenomena calculated in O(αs 3 ). 2. New techniques for the calculation of tree graphs. 3. Color coherence in jet phenomena. 31 references, 6 figures
Perturbation theory from stochastic quantization
International Nuclear Information System (INIS)
Hueffel, H.
1984-01-01
By using a diagrammatical method it is shown that in scalar theories the stochastic quantization method of Parisi and Wu gives the usual perturbation series in Feynman diagrams. It is further explained how to apply the diagrammatical method to gauge theories, discussing the origin of ghost effects. (Author)
Seven topics in perturbative QCD
International Nuclear Information System (INIS)
Buras, A.J.
1980-09-01
The following topics of perturbative QCD are discussed: (1) deep inelastic scattering; (2) higher order corrections to e + e - annihilation, to photon structure functions and to quarkonia decays; (3) higher order corrections to fragmentation functions and to various semi-inclusive processes; (4) higher twist contributions; (5) exclusive processes; (6) transverse momentum effects; (7) jet and photon physics
Reggeon interactions in perturbative QCD
International Nuclear Information System (INIS)
Kirschner, R.
1994-08-01
We study the pairwise interaction of reggeized gluons and quarks in the Regge limit of perturbative QCD. The interactions are represented as integral kernels in the transverse momentum space and as operators in the impact parameter space. We observe conformal symmetry and holomorphic factorization in all cases. (orig.)
Basics of QCD perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Soper, D.E. [Univ. of Oregon, Eugene, OR (United States). Inst. of Theoretical Science
1997-06-01
This is an introduction to the use of QCD perturbation theory, emphasizing generic features of the theory that enable one to separate short-time and long-time effects. The author also covers some important classes of applications: electron-positron annihilation to hadrons, deeply inelastic scattering, and hard processes in hadron-hadron collisions. 31 refs., 38 figs.
Status of chiral perturbation theory
International Nuclear Information System (INIS)
Ecker, G.
1996-10-01
A survey is made of semileptonic and nonleptonic kaon decays in the framework of chiral perturbation theory. The emphasis is on what has been done rather than how it was done. The theoretical predictions are compared with available experimental results. (author)
Principles of chiral perturbation theory
International Nuclear Information System (INIS)
Leutwyler, H.
1995-01-01
An elementary discussion of the main concepts used in chiral perturbation theory is given in textbooks and a more detailed picture of the applications may be obtained from the reviews. Concerning the foundations of the method, the literature is comparatively scarce. So, I will concentrate on the basic concepts and explain why the method works. (author)
Superfield perturbation theory and renormalization
International Nuclear Information System (INIS)
Delbourgo, R.
1975-01-01
The perturbation theory graphs and divergences in super-symmetric Lagrangian models are studied by using superfield techniques. In super PHI 3 -theory very little effort is needed to arrive at the single infinite (wave function) renormalization counterterm, while in PHI 4 -theory the method indicates the counter-Lagrangians needed at the one-loop level and possibly beyond
Chiral symmetry in perturbative QCD
International Nuclear Information System (INIS)
Trueman, T.L.
1979-04-01
The chiral symmetry of quantum chromodynamics with massless quarks is unbroken in perturbation theory. Dimensional regularization is used. The ratio of the vector and axial vector renormalization constante is shown to be independent of the renormalization mass. The general results are explicitly verified to fourth order in g, the QCD coupling constant
Perturbative QCD and exclusive processes
International Nuclear Information System (INIS)
Bennett, J.; Hawes, F.; Zhao, M.; Zyla, P.
1991-01-01
The authors discuss perturbation theory as applied to particle physics calculations. In particle physics one is generally interested in the scattering amplitude for a system going from some initial state to a final state. The intermediate state or states are unknown. To get the scattering amplitude it is necessary to sum the contributions from processes which pass through all possible intermediate states. Intermediate states involve the exchange of intermediate vector bosons between the particles, and with this interaction is associated a coupling constant α. Each additional boson exchange involves an additional contribution of α to the coupling. If α is less than 1, one can see that the relative contribution of higher order processes is less and less important as α falls. In QCD the gluons serve as the intermediate vector bosons exchanged by quarks and gluons, and the interaction constant is not really a constant, but depends upon the distance between the particles. At short distances the coupling is small, and one can assume perturbative expansions may converge rapidly. Exclusive scattering processes, as opposed to inclusive, are those in which all of the final state products are detected. The authors then discuss the application of perturbative QCD to the deuteron. The issues of chiral conservation and color transparancy are also discussed, in the scheme of large Q 2 interations, where perturbative QCD should be applicable
Perturbative treatment of nuclear rotations
International Nuclear Information System (INIS)
Civitarese, O.
1980-01-01
In this work, it is described the case corresponding to perturbative quantum treatment of a fermion system in free rotation and the divergences which resulted from the 'break' in symmetry, associated by the adoption of a deformed basis as a non pertubed solution. (A.C.A.S.) [pt
Outer planet probe cost estimates: First impressions
Niehoff, J.
1974-01-01
An examination was made of early estimates of outer planetary atmospheric probe cost by comparing the estimates with past planetary projects. Of particular interest is identification of project elements which are likely cost drivers for future probe missions. Data are divided into two parts: first, the description of a cost model developed by SAI for the Planetary Programs Office of NASA, and second, use of this model and its data base to evaluate estimates of probe costs. Several observations are offered in conclusion regarding the credibility of current estimates and specific areas of the outer planet probe concept most vulnerable to cost escalation.
Application of the perturbation iteration method to boundary layer type problems.
Pakdemirli, Mehmet
2016-01-01
The recently developed perturbation iteration method is applied to boundary layer type singular problems for the first time. As a preliminary work on the topic, the simplest algorithm of PIA(1,1) is employed in the calculations. Linear and nonlinear problems are solved to outline the basic ideas of the new solution technique. The inner and outer solutions are determined with the iteration algorithm and matched to construct a composite expansion valid within all parts of the domain. The solutions are contrasted with the available exact or numerical solutions. It is shown that the perturbation-iteration algorithm can be effectively used for solving boundary layer type problems.
Effects of core perturbations on the structure of the sun
International Nuclear Information System (INIS)
Sweigart, A.V.
1983-01-01
A number of numerical experiments have been carried out in order to investigate the sensivity of the solar luminosity and radius to perturbations within the radiative core. In these experiments the core was perturbed by suddenly mixing various parts of the composition profile during evolutionary sequences for the present Sun. The hydrostatic readjustment caused by these ''mixing events'' induced an immediate change in the surface luminosity and radius on both the hydrodynamic time scale (approx.15 minutes) and the thermal time scale of the superadiabatic layers (approx.1 day). The subsequent evolution of the luminosity and radius perturbations was followed for 5 x 10 5 yr after each mixing event. The time-dependent behavior of these perturbations was found to depend on where the mixing event occurred. In all cases, however, the ratio W(t) = Δ log R/Δ log L had an initial value of 0.71 and showed only a mild time dependence during the first several thousand years. Two other relationships between the luminosity and radius perturbations are also discussed. One of these, V(t) = (d log R/dd)/(d log L/dt), has a fairly constant value of 0.3 +- 0.1. Both perturbations in the mixing-length ratio α and perturbations in the magnetic pressure within the solar convective envelope yield the same value for V/(t). During the normal unperturbed evolution of the present Sun, V(t) = 0.4. Our results show that core perturbations such as the present mixing events cannot explain the decrease in the solar radius indicated by the solar eclipse data between 1925 and 1980
Linear analysis on the growth of non-spherical perturbations in supersonic accretion flows
Energy Technology Data Exchange (ETDEWEB)
Takahashi, Kazuya; Yamada, Shoichi, E-mail: ktakahashi@heap.phys.waseda.ac.jp [Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku 169-8555 (Japan)
2014-10-20
We analyzed the growth of non-spherical perturbations in supersonic accretion flows. We have in mind an application to the post-bounce phase of core-collapse supernovae (CCSNe). Such non-spherical perturbations have been suggested by a series of papers by Arnett, who has numerically investigated violent convections in the outer layers of pre-collapse stars. Moreover, Couch and Ott demonstrated in their numerical simulations that such perturbations may lead to a successful supernova even for a progenitor that fails to explode without fluctuations. This study investigated the linear growth of perturbations during the infall onto a stalled shock wave. The linearized equations are solved as an initial and boundary value problem with the use of a Laplace transform. The background is a Bondi accretion flow whose parameters are chosen to mimic the 15 M {sub ☉} progenitor model by Woosley and Heger, which is supposed to be a typical progenitor of CCSNe. We found that the perturbations that are given at a large radius grow as they flow down to the shock radius; the density perturbations can be amplified by a factor of 30, for example. We analytically show that the growth rate is proportional to l, the index of the spherical harmonics. We also found that the perturbations oscillate in time with frequencies that are similar to those of the standing accretion shock instability. This may have an implication for shock revival in CCSNe, which will be investigated in our forthcoming paper in more detail.
27 CFR 9.207 - Outer Coastal Plain.
2010-04-01
... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Outer Coastal Plain. 9.207... Outer Coastal Plain. (a) Name. The name of the viticultural area described in this section is “Outer Coastal Plain”. For purposes of part 4 of this chapter, “Outer Coastal Plain” is a term of viticultural...
Murphy, J. P.
1972-01-01
Analytical prediction of expected eccentricity perturbations for the RAE 2 lunar orbit shows that the eccentricity will grow linearly in time. Parametric inclination studies and analysis of perturbation equations establish a critical retrograde inclination of 116.565 at which the positive perturbation slope vanishes for a circular orbit about 1100 m above the lunar surface with an eccentricity constraint of less than 0.005 during a period of about one year.
Outer-2-independent domination in graphs
Indian Academy of Sciences (India)
independent dominating set of a graph is a set of vertices of such that every vertex of ()\\ has a neighbor in and the maximum vertex degree of the subgraph induced by ()\\ is at most one. The outer-2-independent domination ...
Intershell correlations in photoionization of outer shells
Energy Technology Data Exchange (ETDEWEB)
Amusia, M.Ya. [The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel); A.F. Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russian Federation); Chernysheva, L.V. [A.F. Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russian Federation); Drukarev, E.G. [National Research Center “Kurchatov Institute”, Konstantinov Petersburg Nuclear Physics Institute, St. Petersburg 188300 (Russian Federation)
2016-02-15
We demonstrate that the cross sections for photoionization of the outer shells are noticeably modified at the photon energies close to the thresholds of ionization of the inner shells due to correlations with the latter. The correlations may lead to increase or to decrease of the cross sections just above the ionization thresholds.
Outer-2-independent domination in graphs
Indian Academy of Sciences (India)
Outer-2-independent domination in graphs. MARCIN KRZYWKOWSKI1,2,∗, DOOST ALI MOJDEH3 and MARYEM RAOOFI4. 1Department of Pure and Applied Mathematics, University of Johannesburg,. Johannesburg, South Africa. 2Faculty of Electronics, Telecommunications and Informatics, Gdansk University.
Intershell correlations in photoionization of outer shells
International Nuclear Information System (INIS)
Amusia, M.Ya.; Chernysheva, L.V.; Drukarev, E.G.
2016-01-01
We demonstrate that the cross sections for photoionization of the outer shells are noticeably modified at the photon energies close to the thresholds of ionization of the inner shells due to correlations with the latter. The correlations may lead to increase or to decrease of the cross sections just above the ionization thresholds.
Outer Sphere Adsorption of Pb(II)EDTA on Goethite
Energy Technology Data Exchange (ETDEWEB)
Bargar, John R
1999-07-16
FTIR and EXAFS spectroscopic measurements were performed on Pb(II)EDTA adsorbed on goethite as functions of pH (4-6), Pb(II)EDTA concentration (0.11 {micro}M - 72 {micro}M), and ionic strength (16 {micro}M - 0.5M). FTIR measurements show no evidence for carboxylate-Fe(III) bonding or protonation of EDTA at Pb:EDTA = 1:1. Both FTIR and EXAFS measurements suggest that EDTA acts as a hexadentate ligand, with all four of its carboxylate and both amine groups bonded to Pb(II). No evidence was observed for inner-sphere Pb(II)-goethite bonding at Pb:EDTA = 1:1. Hence, the adsorbed complexes should have composition Pb(II)EDTA{sup 2{minus}}. Since substantial uptake of PbEDTA(II){sup 2{minus}} occurred in the samples, we infer that Pb(II)EDTA{sup 2{minus}} adsorbed as outer-sphere complexes and/or as complexes that lose part of their solvation shells and hydrogen bond directly to goethite surface sites. We propose the term ''hydration-sphere'' for the latter type of complexes because they should occupy space in the primary hydration spheres of goethite surface functional groups, and to distinguish this mode of sorption from common structural definitions of inner- and outer-sphere complexes. The similarity of Pb(II) uptake isotherms to those of other divalent metal ions complexed by EDTA suggests that they too adsorb by these mechanisms. The lack of evidence for inner-sphere EDTA-Fe(III) bonding suggests that previously proposed metal-ligand - promoted dissolution mechanisms should be modified, specifically to account for the presence of outer-sphere precursor species.
Perturbations in electromagnetic dark energy
International Nuclear Information System (INIS)
Jiménez, Jose Beltrán; Maroto, Antonio L.; Koivisto, Tomi S.; Mota, David F.
2009-01-01
It has been recently proposed that the presence of a temporal electromagnetic field on cosmological scales could explain the phase of accelerated expansion that the universe is currently undergoing. The field contributes as a cosmological constant and therefore, the homogeneous cosmology produced by such a model is exactly the same as that of ΛCDM. However, unlike a cosmological constant term, electromagnetic fields can acquire perturbations which in principle could affect CMB anisotropies and structure formation. In this work, we study the evolution of inhomogeneous scalar perturbations in this model. We show that provided the initial electromagnetic fluctuations generated during inflation are small, the model is perfectly compatible with both CMB and large scale structure observations at the same level of accuracy as ΛCDM
Perturbative instabilities in Horava gravity
International Nuclear Information System (INIS)
Bogdanos, Charalampos; Saridakis, Emmanuel N
2010-01-01
We investigate the scalar and tensor perturbations in Horava gravity, with and without detailed balance, around a flat background. Once both types of perturbations are taken into account, it is revealed that the theory is plagued by ghost-like scalar instabilities in the range of parameters which would render it power-counting renormalizable, that cannot be overcome by simple tricks such as analytic continuation. Implementing a consistent flow between the UV and IR limits seems thus more challenging than initially presumed, regardless of whether the theory approaches general relativity at low energies or not. Even in the phenomenologically viable parameter space, the tensor sector leads to additional potential problems, such as fine-tunings and super-luminal propagation.
The status of perturbative QCD
International Nuclear Information System (INIS)
Ellis, R.K.
1988-10-01
The advances in perturbative QCD are reviewed. The status of determinations of the coupling constant α/sub S/ and the parton distribution functions is presented. New theoretical results on the spin dependent structure functions of the proton are also reviewed. The theoretical description of the production of vector bosons, jets and heavy quarks is outlined with special emphasis on new results. Expected rates for top quark production at hadronic colliders are presented. 111 refs., 8 figs
Scalar perturbations and conformal transformation
International Nuclear Information System (INIS)
Fabris, J.C.; Tossa, J.
1995-11-01
The non-minimal coupling of gravity to a scalar field can be transformed into a minimal coupling through a conformal transformation. We show how to connect the results of a perturbation calculation, performed around a Friedman-Robertson-Walker background solution, before and after the conformal transformation. We work in the synchronous gauge, but we discuss the implications of employing other frames. (author). 16 refs
Perturbative QCD at finite temperature
International Nuclear Information System (INIS)
Altherr, T.
1989-03-01
We discuss an application of finite temperature QCD to lepton-pair production in a quark-gluon plasma. The perturbative calculation is performed within the realtime formalism. After cancellation of infrared and mass singularities, the corrections at O (α s ) are found to be very small in the region where the mass of the Drell-Yan pair is much larger than the temperature of the plasma. Interesting effects, however, appear at the annihilation threshold of the thermalized quarks
Outer boundary as arrested history in general relativity
International Nuclear Information System (INIS)
Lau, Stephen R
2002-01-01
We present explicit outer boundary conditions for the canonical variables of general relativity. The conditions are associated with the causal evolution of a finite Cauchy domain, a so-called quasilocal boost, and they suggest a consistent scheme for modelling such an evolution numerically. The scheme involves a continuous boost in the spacetime orthogonal complement 'orthogonal' T p (B) of the tangent space T p (B) belonging to each point p on the system boundary B. We show how the boost rate may be computed numerically via equations similar to those appearing in canonical investigations of black-hole thermodynamics (although here holding at an outer two-surface rather than the bifurcate two-surface of a Killing horizon). We demonstrate the numerical scheme on a model example, the quasilocal boost of a spherical three-ball in Minkowski spacetime. Developing our general formalism with recent hyperbolic formulations of the Einstein equations in mind, we use Anderson and York's 'Einstein-Christoffel' hyperbolic system as the evolution equations for our numerical simulation of the model
Outer boundary as arrested history in general relativity
Lau, Stephen R.
2002-06-01
We present explicit outer boundary conditions for the canonical variables of general relativity. The conditions are associated with the causal evolution of a finite Cauchy domain, a so-called quasilocal boost, and they suggest a consistent scheme for modelling such an evolution numerically. The scheme involves a continuous boost in the spacetime orthogonal complement ⊥Tp(B) of the tangent space Tp(B) belonging to each point p on the system boundary B. We show how the boost rate may be computed numerically via equations similar to those appearing in canonical investigations of black-hole thermodynamics (although here holding at an outer two-surface rather than the bifurcate two-surface of a Killing horizon). We demonstrate the numerical scheme on a model example, the quasilocal boost of a spherical three-ball in Minkowski spacetime. Developing our general formalism with recent hyperbolic formulations of the Einstein equations in mind, we use Anderson and York's 'Einstein-Christoffel' hyperbolic system as the evolution equations for our numerical simulation of the model.
Outer boundary as arrested history in general relativity
Lau, S
2002-01-01
We present explicit outer boundary conditions for the canonical variables of general relativity. The conditions are associated with the causal evolution of a finite Cauchy domain, a so-called quasilocal boost, and they suggest a consistent scheme for modelling such an evolution numerically. The scheme involves a continuous boost in the spacetime orthogonal complement 'orthogonal' T sub p (B) of the tangent space T sub p (B) belonging to each point p on the system boundary B. We show how the boost rate may be computed numerically via equations similar to those appearing in canonical investigations of black-hole thermodynamics (although here holding at an outer two-surface rather than the bifurcate two-surface of a Killing horizon). We demonstrate the numerical scheme on a model example, the quasilocal boost of a spherical three-ball in Minkowski spacetime. Developing our general formalism with recent hyperbolic formulations of the Einstein equations in mind, we use Anderson and York's 'Einstein-Christoffel' hy...
Gauge-invariant cosmological density perturbations
International Nuclear Information System (INIS)
Sasaki, Misao.
1986-06-01
Gauge-invariant formulation of cosmological density perturbation theory is reviewed with special emphasis on its geometrical aspects. Then the gauge-invariant measure of the magnitude of a given perturbation is presented. (author)
Perturbation of an exact strong gravity solution
International Nuclear Information System (INIS)
Baran, S.A.
1982-10-01
Perturbations of an exact strong gravity solution are investigated. It is shown, by using the new multipole expansions previously presented, that this exact and static spherically symmetric solution is stable under odd parity perturbations. (author)
Outer- and middle-ear contributions to presbycusis in the Brown Norway rat.
Gratton, Michael Anne; Bateman, Kristin; Cannuscio, Joseph F; Saunders, James C
2008-01-01
This paper examines the contribution of the outer and middle ears to the hearing loss associated with presbycusis in Brown Norway rats. Animals were formed into two groups; young adults (2-3 months old) and aged animals (approximately 34 months old). Auditory brainstem response (ABR) thresholds were obtained with the outer ear intact or surgically removed. Tympanic membrane (TM) velocity transfer functions were measured from the umbo with the outer ear removed. The length of the auditory meatus, TM surface area, and TM thickness were quantified. The ABR thresholds were 17-26 dB less sensitive in the aged animals between 8.0 and 40.0 kHz when the outer ear was intact. A significant and reliable reduction in the aged rat velocity transfer function of 5-8 dB occurred between 10.0 and 32.0 kHz, while the low frequency velocity response was only a few decibels greater in the younger animals. The ABR threshold differences between young adult and aged ears were compensated by removing the outer/middle ear effects of aging to reveal a purely sensorineural component of presbycusis. The outer and middle ear effects were calculated directly when the ABR and TM velocity data were obtained with the outer ear removed. The outer ear intact condition was modeled in order to compare the ABR data obtained with the outer ear intact with the TM velocity data obtained with the outer removed. With either procedure, removal of the age-related contributions of the outer and middle ear to the ABR threshold resulted in similar age-related ABR threshold shifts between the two age groups. The pure sensorineural threshold shift component of the ABR response was restricted to frequencies between 5.0 and 20.0 kHz and reached a maximum of approximately 15 dB. These results support the conclusion that there is an outer- and middle-ear contribution to the threshold loss defining presbycusis. (c) 2008 S. Karger AG, Basel.
Acute Zonal Cone Photoreceptor Outer Segment Loss.
Aleman, Tomas S; Sandhu, Harpal S; Serrano, Leona W; Traband, Anastasia; Lau, Marisa K; Adamus, Grazyna; Avery, Robert A
2017-05-01
The diagnostic path presented narrows down the cause of acute vision loss to the cone photoreceptor outer segment and will refocus the search for the cause of similar currently idiopathic conditions. To describe the structural and functional associations found in a patient with acute zonal occult photoreceptor loss. A case report of an adolescent boy with acute visual field loss despite a normal fundus examination performed at a university teaching hospital. Results of a complete ophthalmic examination, full-field flash electroretinography (ERG) and multifocal ERG, light-adapted achromatic and 2-color dark-adapted perimetry, and microperimetry. Imaging was performed with spectral-domain optical coherence tomography (SD-OCT), near-infrared (NIR) and short-wavelength (SW) fundus autofluorescence (FAF), and NIR reflectance (REF). The patient was evaluated within a week of the onset of a scotoma in the nasal field of his left eye. Visual acuity was 20/20 OU, and color vision was normal in both eyes. Results of the fundus examination and of SW-FAF and NIR-FAF imaging were normal in both eyes, whereas NIR-REF imaging showed a region of hyporeflectance temporal to the fovea that corresponded with a dense relative scotoma noted on light-adapted static perimetry in the left eye. Loss in the photoreceptor outer segment detected by SD-OCT co-localized with an area of dense cone dysfunction detected on light-adapted perimetry and multifocal ERG but with near-normal rod-mediated vision according to results of 2-color dark-adapted perimetry. Full-field flash ERG findings were normal in both eyes. The outer nuclear layer and inner retinal thicknesses were normal. Localized, isolated cone dysfunction may represent the earliest photoreceptor abnormality or a distinct entity within the acute zonal occult outer retinopathy complex. Acute zonal occult outer retinopathy should be considered in patients with acute vision loss and abnormalities on NIR-REF imaging, especially if
Geometric Hamiltonian structures and perturbation theory
International Nuclear Information System (INIS)
Omohundro, S.
1984-08-01
We have been engaged in a program of investigating the Hamiltonian structure of the various perturbation theories used in practice. We describe the geometry of a Hamiltonian structure for non-singular perturbation theory applied to Hamiltonian systems on symplectic manifolds and the connection with singular perturbation techniques based on the method of averaging
Multiplicative perturbations of local C-semigroups
Indian Academy of Sciences (India)
2016-08-26
Aug 26, 2016 ... In this paper, we establish some left and right multiplicative perturbation theorems concerning local -semigroups when the generator of a perturbed local -semigroup S(⋅) may not be densely defined and the perturbation operator is a bounded linear operator from ¯D(A) into () such that = ...
Multiplicative perturbations of local C-semigroups
Indian Academy of Sciences (India)
In this paper, we establish some left and right multiplicative perturbation theorems concerning local -semigroups when the generator of a perturbed local -semigroup S ( ⋅ ) may not be densely defined and the perturbation operator is a bounded linear operator from D ( A ) ¯ into () such that = on D ( A ) ¯ ...
FRW Cosmological Perturbations in Massive Bigravity
Comelli, D; Pilo, L
2014-01-01
Cosmological perturbations of FRW solutions in ghost free massive bigravity, including also a second matter sector, are studied in detail. At early time, we find that sub horizon exponential instabilities are unavoidable and they lead to a premature departure from the perturbative regime of cosmological perturbations.
Geometric singular perturbation analysis of systems with friction
DEFF Research Database (Denmark)
Bossolini, Elena
This thesis is concerned with the application of geometric singular perturbation theory to mechanical systems with friction. The mathematical background on geometric singular perturbation theory, on the blow-up method, on non-smooth dynamical systems and on regularization is presented. Thereafter......, two mechanical problems with two diﬀerent formulations of the friction force are introduced and analysed. The ﬁrst mechanical problem is a one-dimensional spring-block model describing earthquake faulting. The dynamics of earthquakes is naturally a multiple timescale problem: the timescale...... scales. The action of friction is generally explained as the loss and restoration of linkages between the surface asperities at the molecular scale. However, the consequences of friction are noticeable at much larger scales, like hundreds of kilometers. By using geometric singular perturbation theory...
Effects of stratospheric perturbations on the solar radiation budget
International Nuclear Information System (INIS)
Luther, F.M.
1978-04-01
The changes in solar absorption and in local heating rates due to perturbations to O 3 and NO 2 concentrations caused by stratospheric injection of NO/sub x/ and CFM pollutants are assessed. The changes in species concentration profiles are derived from theoretical calculations using a transport-kinetics model. Because of significant changes in our understanding of stratospheric chemistry during the past year, the assessment of the effect of stratospheric perturbations on the solar radiation budget differs from previous assessments. Previously, a reduction in O 3 due to an NO/sub x/ injection caused a net decrease in the gaseous solar absorption;now the same perturbation leads to a net increase. The implication of these changes on the surface temperature is also discussed
Performance of the LHCb Outer Tracker
Arink, R; Bachmann, S.; Bagaturia, Y.; Band, H.; Bauer, Th.; Berkien, A.; Farber, Ch.; Bien, A.; Blouw, J.; Ceelie, L.; Coco, V.; Deckenhoff, M.; Deng, Z.; Dettori, F.; van Eijk, D.; Ekelhof, R.; Gersabeck, E.; Grillo, L.; Hulsbergen, W.D.; Karbach, T.M.; Koopman, R.; Kozlinskiy, A.; Langenbruch, Ch.; Lavrentyev, V.; Linn, Ch.; Merk, M.; Merkel, J.; Meissner, M.; Michalowski, J.; Morawski, P.; Nawrot, A.; Nedos, M.; Pellegrino, A.; Polok, G.; van Petten, O.; Rovekamp, J.; Schimmel, F.; Schuylenburg, H.; Schwemmer, R.; Seyfert, P.; Serra, N.; Sluijk, T.; Spaan, B.; Spelt, J.; Storaci, B.; Szczekowski, M.; Swientek, S.; Tolk, S.; Tuning, N.; Uwer, U.; Wiedner, D.; Witek, M.; Zeng, M.; Zwart, A.
2014-01-01
The LHCb Outer Tracker is a gaseous detector covering an area of 5x6 m2 with 12 double layers of straw tubes. The detector with its services are described together with the commissioning and calibration procedures. Based on data of the first LHC running period from 2010 to 2012, the performance of the readout electronics and the single hit resolution and efficiency are presented. The efficiency to detect a hit in the central half of the straw is estimated to be 99.2%, and the position resolution is determined to be approximately 200 um. The Outer Tracker received a dose in the hottest region corresponding to 0.12 C/cm, and no signs of gain deterioration or other ageing effects are observed.
The Outer Space as an Educational Motivation
Pérez-Pérez, Melquíades; Hernández-López, Montserrat
2017-06-01
STEAM is an educational approach to learning that uses Science, Technology, Engineering, the Arts and Mathematics as access points for guiding student inquiry, dialogue, and critical thinking. The end results are students who take thoughtful risks, engage in experiential learning, persist in problem-solving, embrace collaboration, and work through the creative process. The Outer Space is a window to the past and the future of our travel around the history of the Universe and can be used as a educational tool in primary and secondary education. This paper talks about the integration of the resources of European Space Agency, Space Awareness, Nuclio, Scientix and Schoolnet as motivation to integrate STEAM methodology in secondary education. Keywords: STEAM, outer space, motivation, methodology
The Outer Banks of North Carolina
Dolan, Robert; Lins, Harry F.; Smith, Jodi Jones
2016-12-27
The Outer Banks of North Carolina are excellent examples of the nearly 300 barrier islands rimming the Atlantic and Gulf coasts of the United States. These low, sandy islands are among the most dynamic natural landscapes occupied by man. Beach sands move offshore, onshore, and along the shore in the direction of the prevailing longshore currents. In this way, sandy coasts continuously adjust to different tide, wave, and current conditions and to rising sea level that causes the islands to migrate landward.Despite such changes, barrier islands are of considerable environmental importance. The Outer Banks are home to diverse natural ecosystems that are adapted to the harsh coastal environment. Native species tend to be robust and many are specifically adapted to withstand salt spray, periodic saltwater flooding, and the islands’ well-drained sandy soil. The Outer Banks provide an important stopover for birds on the Atlantic flyway, and many species inhabit the islands year round. In addition, Outer Banks beaches provide an important nesting habitat for five endangered or threatened sea turtle species.European explorers discovered North Carolina’s barrier islands in the 16th century, although the islands were not permanently settled until the middle 17th century. By the early 19th century, shipbuilding and lumber industries were among the most successful, until forest resources were depleted. Commercial fishing eventually followed, and it expanded considerably after the Civil War. By the Great Depression, however, little industry existed on the Outer Banks. In response to the effects of a severe hurricane in 1933, the National Park Service and the Civilian Conservation Corps proposed a massive sand-fixation program to stabilize the moving sand and prevent storm waves from sweeping across the entire width of some sections of the islands. Between 1933 and 1940, this program constructed sand fencing on 185 kilometers (115 miles) of beach and planted grass seedlings
Protection of nuclear facilities against outer aggressions
International Nuclear Information System (INIS)
Aussourd, P.; Candes, P.; Le Quinio, R.
1976-01-01
The various types of outer aggressions envisaged in safety analysis for nuclear facilities are reviewed. These outer aggressions are classified as natural and non-natural phenomena, the latter depending on the human activities in the vicinity of nuclear sites. The principal natural phenomena able to constitute aggressions are atmospheric phenomena (strong winds, snow storms, hail, frosting mists), hydrologie phenomena such as tides, surges, flood, low waters, and geologic phenomena such as earthquakes. Artificial phenomena are concerned with aircraft crashes, projectiles, fire, possible ruptures of dams, and intentional human aggressions. The protection against intentional human aggressions is of two sorts: first, the possibility of access to the installations mostly sensitive to sabotage are to be prevented or reduced, secondly redundant circuits and functions must be separated for preventing their simultaneous destruction in the case when sabotage actors have reach the core of the facility [fr
Outer crust of nonaccreting cold neutron stars
International Nuclear Information System (INIS)
Ruester, Stefan B.; Hempel, Matthias; Schaffner-Bielich, Juergen
2006-01-01
The properties of the outer crust of nonaccreting cold neutron stars are studied by using modern nuclear data and theoretical mass tables, updating in particular the classic work of Baym, Pethick, and Sutherland. Experimental data from the atomic mass table from Audi, Wapstra, and Thibault of 2003 are used and a thorough comparison of many modern theoretical nuclear models, both relativistic and nonrelativistic, is performed for the first time. In addition, the influences of pairing and deformation are investigated. State-of-the-art theoretical nuclear mass tables are compared to check their differences concerning the neutron drip line, magic neutron numbers, the equation of state, and the sequence of neutron-rich nuclei up to the drip line in the outer crust of nonaccreting cold neutron stars
Boundary layers of the earth's outer magnetosphere
Eastman, T. E.; Frank, L. A.
1984-01-01
The magnetospheric boundary layer and the plasma-sheet boundary layer are the primary boundary layers of the earth's outer magnetosphere. Recent satellite observations indicate that they provide for more than 50 percent of the plasma and energy transport in the outer magnetosphere although they constitute less than 5 percent by volume. Relative to the energy density in the source regions, plasma in the magnetospheric boundary layer is predominantly deenergized whereas plasma in the plasma-sheet boundary layer has been accelerated. The reconnection hypothesis continues to provide a useful framework for comparing data sampled in the highly dynamic magnetospheric environment. Observations of 'flux transfer events' and other detailed features near the boundaries have been recently interpreted in terms of nonsteady-state reconnection. Alternative hypotheses are also being investigated. More work needs to be done, both in theory and observation, to determine whether reconnection actually occurs in the magnetosphere and, if so, whether it is important for overall magnetospheric dynamics.
Boundary layers of the earth's outer magnetosphere
International Nuclear Information System (INIS)
Eastman, T.E.; Frank, L.A.
1984-01-01
The magnetospheric boundary layer and the plasma-sheet boundary layer are the primary boundary layers of the earth's outer magnetosphere. Recent satellite observations indicate that they provide for more than 50 percent of the plasma and energy transport in the outer magnetosphere although they constitute less than 5 percent by volume. Relative to the energy density in the source regions, plasma in the magnetospheric boundary layer is predominantly deenergized whereas plasma in the plasma-sheet boundary layer has been accelerated. The reconnection hypothesis continues to provide a useful framework for comparing data sampled in the highly dynamic magnetospheric environment. Observations of flux transfer events and other detailed features near the boundaries have been recently interpreted in terms of nonsteady-state reconnection. Alternative hypotheses are also being investigated. More work needs to be done, both in theory and observation, to determine whether reconnection actually occurs in the magnetosphere and, if so, whether it is important for overall magnetospheric dynamics. 30 references
Differential Rotation within the Earth's Outer Core
Hide, R.; Boggs, D. H.; Dickey, J. O.
1998-01-01
Non-steady differential rotation drive by bouyancy forces within the Earth's liquid outer core (OC) plays a key role not only in the generation of the main geomagnetic field by the magnetohydrodynamic (MHD) dynamo process but also in the excitation of irregular fluctuations in the angular speed of rotation of the overlying solid mantle, as evidenced by changes in the length of the day (LOD) on decadal and longer timescales (1-8).
Fluxgate magnetometers for outer planets exploration
Acuna, M. H.
1974-01-01
The exploration of the interplanetary medium and the magnetospheres of the outer planets requires the implementation of magnetic field measuring instrumentation with wide dynamic range, high stability, and reliability. The fluxgate magnetometers developed for the Pioneer 11 and Mariner-Jupiter-Saturn missions are presented. These instruments cover the range of .01 nT to 2 million nT with optimum performance characteristics and low power consumption.
Outer Limits of Biotechnologies: A Jewish Perspective
Directory of Open Access Journals (Sweden)
John D. Loike
2018-01-01
Full Text Available A great deal of biomedical research focuses on new biotechnologies such as gene editing, stem cell biology, and reproductive medicine, which have created a scientific revolution. While the potential medical benefits of this research may be far-reaching, ethical issues related to non-medical applications of these technologies are demanding. We analyze, from a Jewish legal perspective, some of the ethical conundrums that society faces in pushing the outer limits in researching these new biotechnologies.
The bispectrum of matter perturbations from cosmic strings
Energy Technology Data Exchange (ETDEWEB)
Regan, Donough; Hindmarsh, Mark, E-mail: d.regan@sussex.ac.uk, E-mail: m.b.hindmarsh@sussex.ac.uk [Astronomy Centre, University of Sussex, Falmer, Brighton, BN1 9QH (United Kingdom)
2015-03-01
We present the first calculation of the bispectrum of the matter perturbations induced by cosmic strings. The calculation is performed in two different ways: the first uses the unequal time correlators (UETCs) of the string network - computed using a Gaussian model previously employed for cosmic string power spectra. The second approach uses the wake model, where string density perturbations are concentrated in sheet-like structures whose surface density grows with time. The qualitative and quantitative agreement of the two gives confidence to the results. An essential ingredient in the UETC approach is the inclusion of compensation factors in the integration with the Green's function of the matter and radiation fluids, and we show that these compensation factors must be included in the wake model also. We also present a comparison of the UETCs computed in the Gaussian model, and those computed in the unconnected segment model (USM) used by the standard cosmic string perturbation package CMBACT. We compare numerical estimates for the bispectrum of cosmic strings to those produced by perturbations from an inflationary era, and discover that, despite the intrinsically non-Gaussian nature of string-induced perturbations, the matter bispectrum is unlikely to produce competitive constraints on a population of cosmic strings.
Acoustic wavefield evolution as a function of source location perturbation
Alkhalifah, Tariq Ali
2010-12-01
The wavefield is typically simulated for seismic exploration applications through solving the wave equation for a specific seismic source location. The direct relation between the form (or shape) of the wavefield and the source location can provide insights useful for velocity estimation and interpolation. As a result, I derive partial differential equations that relate changes in the wavefield shape to perturbations in the source location, especially along the Earth\\'s surface. These partial differential equations have the same structure as the wave equation with a source function that depends on the background (original source) wavefield. The similarity in form implies that we can use familiar numerical methods to solve the perturbation equations, including finite difference and downward continuation. In fact, we can use the same Green\\'s function to solve the wave equation and its source perturbations by simply incorporating source functions derived from the background field. The solutions of the perturbation equations represent the coefficients of a Taylor\\'s series type expansion of the wavefield as a function of source location. As a result, we can speed up the wavefield calculation as we approximate the wavefield shape for sources in the vicinity of the original source. The new formula introduces changes to the background wavefield only in the presence of lateral velocity variation or in general terms velocity variations in the perturbation direction. The approach is demonstrated on the smoothed Marmousi model.
A New Strain Collection for Improved Expression of Outer Membrane Proteins
Directory of Open Access Journals (Sweden)
Ina Meuskens
2017-11-01
Full Text Available Almost all integral membrane proteins found in the outer membranes of Gram-negative bacteria belong to the transmembrane β-barrel family. These proteins are not only important for nutrient uptake and homeostasis, but are also involved in such processes as adhesion, protein secretion, biofilm formation, and virulence. As surface exposed molecules, outer membrane β-barrel proteins are also potential drug and vaccine targets. High production levels of heterologously expressed proteins are desirable for biochemical and especially structural studies, but over-expression and subsequent purification of membrane proteins, including outer membrane proteins, can be challenging. Here, we present a set of deletion mutants derived from E. coli BL21(DE3 designed for the over-expression of recombinant outer membrane proteins. These strains harbor deletions of four genes encoding abundant β-barrel proteins in the outer membrane (OmpA, OmpC, OmpF, and LamB, both single and in all combinations of double, triple, and quadruple knock-outs. The sequences encoding these outer membrane proteins were deleted completely, leaving only a minimal scar sequence, thus preventing the possibility of genetic reversion. Expression tests in the quadruple mutant strain with four test proteins, including a small outer membrane β-barrel protein and variants thereof as well as two virulence-related autotransporters, showed significantly improved expression and better quality of the produced proteins over the parent strain. Differences in growth behavior and aggregation in the presence of high salt were observed, but these phenomena did not negatively influence the expression in the quadruple mutant strain when handled as we recommend. The strains produced in this study can be used for outer membrane protein production and purification, but are also uniquely useful for labeling experiments for biophysical measurements in the native membrane environment.
Hadronic Structure from Perturbative Dressing
Energy Technology Data Exchange (ETDEWEB)
Arash, Firooz [Physics Department, Tafresh University, Tafresh, Iran and Center for theoretical physics and Mathematics, AEOI, P.O. Box 11365-8486, Tehran (Iran, Islamic Republic of)]. E-mail: farash@cic.aut.ac.ir
2005-09-15
Perturbative dressing of a valence quark in QCD produces the internal structure of an extended object, the so-called Valon. The valon structure is universal and independent of the hosting hadron. Polarized and unpolarized proton and pion structure functions are calculated in the valon representation. One finds that although all the available data on g{sub 1}{sup p,n,d} are easily reproduced, a sizable orbital angular momentum associated with the partonic structure of the valon is required in order to have a spin 1/2 valon.
Perturbations in loop quantum cosmology
International Nuclear Information System (INIS)
Nelson, W; Agullo, I; Ashtekar, A
2014-01-01
The era of precision cosmology has allowed us to accurately determine many important cosmological parameters, in particular via the CMB. Confronting Loop Quantum Cosmology with these observations provides us with a powerful test of the theory. For this to be possible, we need a detailed understanding of the generation and evolution of inhomogeneous perturbations during the early, quantum gravity phase of the universe. Here, we have described how Loop Quantum Cosmology provides a completion of the inflationary paradigm, that is consistent with the observed power spectra of the CMB
Perturbation calculations with Wilson loop
International Nuclear Information System (INIS)
Peixoto Junior, L.B.
1984-01-01
We present perturbative calculations with the Wilson loop (WL). The dimensional regularization method is used with a special attention concerning to the problem of divergences in the WL expansion in second and fourth orders, in three and four dimensions. We show that the residue in the pole, in 4d, of the fourth order graphs contribution sum is important for the charge renormalization. We compute up to second order the exact expression of the WL, in three-dimensional gauge theories with topological mass as well as its assimptotic behaviour for small and large distances. the author [pt
Mobile ankle and knee perturbator.
Andersen, Jacob Buus; Sinkjaer, Thomas
2003-10-01
A mobile ankle and knee perturbator has been developed. It consists of a functional joint with an integrated clutch. Four Bowden wires connect the joint to a powerful motor and a double pneumatic cylinder. When needed during any time of the gait cycle, it is possible to impose an ankle rotation by engaging the clutch and rotating the ankle or knee joint with a predefined displacement. The system is designed to investigate electrophysiological and biomechanical features of the human ankle or knee joint during gait.
Effect of perturbation of convective energy transport on the luminosity and radius of the sun
International Nuclear Information System (INIS)
Endal, A.S.; Twigg, L.W.
1982-01-01
The response of solar models to perturbations of the efficiency of convective energy transport is studied for a number of cases. Such perturbations primarily affect the shallow superadiabatic layer of the convective envelope (at depths 3 km below the photosphere). Independent of the details of the perturbation scheme, the resulting change in the solar radius (ΔR/R) is always very small compared to the change in luminosity (ΔL/L). This appears to be true for any physical mechanism of solar variability which operates in the outer layers of the convection zone. Changes of the solar radius have been inferred by Dunham et al. from historical observations of solar eclipses in 1715 and 1925. Considering the constraints on concurrent luminosity changes, this type of solar variability must be indicative of changes in the solar structure at substantial depths below the superadiabatic layer of the convective envelope
"Phonon" scattering beyond perturbation theory
Qiu, WuJie; Ke, XueZhi; Xi, LiLi; Wu, LiHua; Yang, Jiong; Zhang, WenQing
2016-02-01
Searching and designing materials with intrinsically low lattice thermal conductivity (LTC) have attracted extensive consideration in thermoelectrics and thermal management community. The concept of part-crystalline part-liquid state, or even part-crystalline part-amorphous state, has recently been proposed to describe the exotic structure of materials with chemical- bond hierarchy, in which a set of atoms is weakly bonded to the rest species while the other sublattices retain relatively strong rigidity. The whole system inherently manifests the coexistence of rigid crystalline sublattices and fluctuating noncrystalline substructures. Representative materials in the unusual state can be classified into two categories, i.e., caged and non-caged ones. LTCs in both systems deviate from the traditional T -1 relationship ( T, the absolute temperature), which can hardly be described by small-parameter-based perturbation approaches. Beyond the classical perturbation theory, an extra rattling-like scattering should be considered to interpret the liquid-like and sublattice-amorphization-induced heat transport. Such a kind of compounds could be promising high-performance thermoelectric materials, due to the extremely low LTCs. Other physical properties for these part-crystalline substances should also exhibit certain novelty and deserve further exploration.
Perturbation theory for Alfven wave
International Nuclear Information System (INIS)
Yoshida, Z.; Mahajan, S.M.
1995-01-01
The Alfven wave is the dominant low frequency transverse mode of a magnetized plasma. The Alfven wave propagation along the magnetic field, and displays a continuous spectrum even in a bounded plasma. This is essentially due to the degeneracy of the wave characteristics, i.e. the frequency (ω) is primarily determined by the wave number in the direction parallel to the ambient magnetic field (k parallel ) and is independent of the perpendicular wavenumbers. The characteristics, that are the direction along which the wave energy propagates, are identical to the ambient magnetic field lines. Therefore, the spectral structure of the Alfven wave has a close relationship with the geometric structure of the magnetic field lines. In an inhomogeneous plasma, the Alfven resonance constitutes a singularity for the defining wave equation; this results in a singular eigenfunction corresponding to the continuous spectrum. The aim of this review is to present an overview of the perturbation theory for the Alfven wave. Emphasis is placed on those perturbations of the continuous spectrum which lead to the creation of point spectra. Such qualitative changes in the spectrum are relevant to many plasma phenomena
Influence of perturbation velocity on balance control in Parkinson's disease.
Directory of Open Access Journals (Sweden)
Lars B Oude Nijhuis
Full Text Available Underlying somatosensory processing deficits of joint rotation velocities may cause patients with Parkinson's disease (PD to be more unstable for fast rather than slow balance perturbations. Such deficits could lead to reduced proprioceptive amplitude feedback triggered by perturbations, and thereby to smaller or delayed stabilizing postural responses. For this reason, we investigated whether support surface perturbation velocity affects balance reactions in PD patients. We examined postural responses of seven PD patients (OFF medication and eight age-matched controls following backward rotations of a support-surface platform. Rotations occurred at three different speeds: fast (60 deg/s, medium (30 deg/s or slow (3.8 deg/s, presented in random order. Each subject completed the protocol under eyes open and closed conditions. Full body kinematics, ankle torques and the number of near-falls were recorded. Patients were significantly more unstable than controls following fast perturbations (26% larger displacements of the body's centre of mass; P<0.01, but not following slow perturbations. Also, more near-falls occurred in patients for fast rotations. Balance correcting ankle torques were weaker for patients than controls on the most affected side, but were stronger than controls for the least affected side. These differences were present both with eyes open and eyes closed (P<0.01. Fast support surface rotations caused greater instability and discriminated Parkinson patients better from controls than slow rotations. Although ankle torques on the most affected side were weaker, patients partially compensated for this by generating larger than normal stabilizing torques about the ankle joint on the least affected side. Without this compensation, instability may have been greater.
75 FR 1076 - Outer Continental Shelf Civil Penalties
2010-01-08
... initiate civil penalty proceedings; however, violations that cause injury, death, or environmental damage... DEPARTMENT OF THE INTERIOR Minerals Management Service Outer Continental Shelf Civil Penalties... daily civil penalty assessment. SUMMARY: The Outer Continental Shelf Lands Act requires the MMS to...
Effects of 3D Magnetic Perturbations on Toroidal Plasmas
International Nuclear Information System (INIS)
Callen, J.D.
2010-01-01
Full text: To lowest order tokamaks are two-dimensional (2D) axisymmetric magnetic systems. But small 3D magnetic perturbations (both externally applied and from plasma instabilities) have many interesting and useful effects on tokamak (and quasi-symmetric stellarator) plasmas. Plasma transport equations that include these effects, especially on diamagnetic-level toroidal plasma rotation, have recently been developed. The 3D magnetic perturbations and their plasma effects can be classified according to their toroidal mode number n: low n (1 to 5) resonant (q = m/n in plasma) and non-resonant fields, medium n (due to toroidal field ripple), and high n (due to microturbulence). This paper concentrates on low and medium n perturbations. Low n non-resonant magnetic fields induce a neoclassical toroidal viscosity (NTV) that damps toroidal plasma rotation throughout the plasma toward an offset flow in the counter-I p direction; recent tokamak experiments have confirmed and exploited these predictions by applying external low n non-resonant magnetic perturbations. Medium n perturbations have similar effects plus possible ripple trapping and resultant edge ion losses. A low n resonant magnetic field induces a toroidal plasma torque in the vicinity of the rational surface; when large enough it can stop plasma rotation there and lead to a locked mode, which often causes a plasma disruption. Externally applied 3D magnetic perturbations usually have many components; in the plasma their lowest n components are amplified by plasma responses, particularly at high beta. Low n plasma instabilities (e.g., NTMs, RWMs) cause additional 3D magnetic perturbations in tokamak plasmas; tearing modes can bifurcate the topology and form magnetic islands. Finally, multiple resonant magnetic perturbations (RMPs) can cause local magnetic stochasticity and influence H-mode edge pedestal transport. These various effects of 3D magnetic perturbations can be used to control the toroidal plasma
Tyler, G. L.
1972-01-01
Scientific instrumentation for satellite communication and radio tracking systems in the outer planet exploration mission is discussed. Mission planning considers observations of planetary and satellite-masses, -atmospheres, -magnetic fields, -surfaces, -gravitational fields, solar wind composition, planetary radio emissions, and tests of general relativity in time delay and ray bending experiments.
Perturbative transport experiments in JET Advanced Tokamak plasmas
Energy Technology Data Exchange (ETDEWEB)
Mantica, P.; Gorini, G.; Sozzi, C. [Istituto di Fisica del Plasma, EURATOM-ENEA-CNR Association, Milan (Italy); Imbeaux, F.; Sarazin, Y.; Garbet, X. [Association Euratom-CEA, St. Paul-lez-Durance Cedex (France); Kinsey, J. [Lehigh Univ., Bethlehem, Pennsylvania (United States); Budny, R. [Princeton Plasma Physics Lab, New Jersey (United States); Coffey, I.; Parail, V.; Walden, A. [Euratom/UKAEA Fusion Association, Abingdon, Oxon (United Kingdom); Dux, R. [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Garzotti, L. [Istituto Gas Ionizzati, Padova (Italy); Ingesson, C. [FOM-Instituut voor Plasmafysica, Nieuwegein (Netherlands); Kissick, M. [University of California, Los Angeles (United States)
2003-07-01
Perturbative transport experiments have been performed in JET Advanced Tokamak plasmas either in conditions of fully developed Internal Transport Barrier (ITB) or during a phase where an ITB was not observed. Transient peripheral cooling was induced by either Laser Ablation or Shallow Pellet Injection and the ensuing travelling cold pulse was used to probe the plasma transport in the electron and, for the first time, also in the ion channel. Cold pulses travelling through ITBs are observed to erode the ITB outer part, but, if the inner ITB portion survives, it strongly damps the propagating wave. The result is discussed in the context of proposed possible pictures for ITB formation. In the absence of an ITB, the cold pulse shows a fast propagation in the outer plasma half, which is consistent with a region of stiff transport, while in the inner half it slows down but shows the peculiar feature of amplitude growing while propagating. The data are powerful tests for the validation of theoretical transport models. (author)
Issues concerning outer space investments in international law ...
African Journals Online (AJOL)
Issues concerning outer space investments in international law. ... Recent improvements in technology have in essence increased the viability of outer space as the next frontier for international investment and development. In addition to ... Key words: Outer Space, Investments, International Law, International Space Station ...
Perturbations i have Known and Loved
Field, Robert W.
2011-06-01
A spectroscopic perturbation is a disruption of a ^1Σ-^1Σ-like regular pattern that can embody level-shifts, extra lines, and intensity anomalies. Once upon a time, when a band was labeled ``perturbed,'' it was considered worthless because it could at best yield molecular constants unsuited for archival tables. Nevertheless, a few brave spectroscopists, notably Albin Lagerqvist and Richard Barrow, collected perturbations because they knew that the pattern of multiple perturbations formed an intricate puzzle that would eventually reveal the presence and electronic symmetry of otherwise unobservable electronic states. There are many kinds of patterns of broken patterns. In my PhD thesis I showed how to determine absolute vibrational assignments for the perturber from patterns among the observed values of perturbation matrix elements. When a ^3Π state is perturbed, its six (Ω, parity) components capture a pattern of level shifts and intensity anomalies that reveals more about the nature of the perturber than a simple perturbation of the single component of a ^1Σ state. In perturbation-facilitated OODR, a perturbed singlet level acts as a spectroscopic doorway through which the entire triplet manifold may be systematically explored. For polyatomic molecule vibrations, a vibrational polyad (a group of mutually perturbing vibrational levels, among which the perturbation matrix elements are expected to follow harmonic oscillator scaling rules) can contain more components than a ^3Π state and intrapolyad patterns can be exquisitely sensitive not merely to the nature of an interloper within the polyad but also to the eigenvector character of the vibronic state from which the polyad is viewed. Variation of scaled polyad interaction parameters from one polyad to the next, a pattern of patterns, can signal proximity to an isomerization barrier. Everything in Rydberg-land seems to scale as N⋆-3, yet a trespassing valence state causes all scaling and propensity rules go
New Methods in Non-Perturbative QCD
Energy Technology Data Exchange (ETDEWEB)
Unsal, Mithat [North Carolina State Univ., Raleigh, NC (United States)
2017-01-31
In this work, we investigate the properties of quantum chromodynamics (QCD), by using newly developing mathematics and physics formalisms. Almost all of the mass in the visible universe emerges from a quantum chromodynamics (QCD), which has a completely negligible microscopic mass content. An intimately related issue in QCD is the quark confinement problem. Answers to non-perturbative questions in QCD remained largely elusive despite much effort over the years. It is also believed that the usual perturbation theory is inadequate to address these kinds of problems. Perturbation theory gives a divergent asymptotic series (even when the theory is properly renormalized), and there are non-perturbative phenomena which never appear at any order in perturbation theory. Recently, a fascinating bridge between perturbation theory and non-perturbative effects has been found: a formalism called resurgence theory in mathematics tells us that perturbative data and non-perturbative data are intimately related. Translating this to the language of quantum field theory, it turns out that non-perturbative information is present in a coded form in perturbation theory and it can be decoded. We take advantage of this feature, which is particularly useful to understand some unresolved mysteries of QCD from first principles. In particular, we use: a) Circle compactifications which provide a semi-classical window to study confinement and mass gap problems, and calculable prototypes of the deconfinement phase transition; b) Resurgence theory and transseries which provide a unified framework for perturbative and non-perturbative expansion; c) Analytic continuation of path integrals and Lefschetz thimbles which may be useful to address sign problem in QCD at finite density.
What galaxy masses perturb the local cosmic expansion?
Peñarrubia, Jorge; Fattahi, Azadeh
2017-06-01
We use 12 cosmological N-body simulations of Local Group systems (the apostle models) to inspect the relation between the virial mass of the main haloes (Mvir,1 and Mvir,2), the mass derived from the relative motion of the halo pair (Mtim), and that inferred from the local Hubble flow (Mlhf). We show that within the spherical collapse model (SCM), the correspondence between the three mass estimates is exact, I.e. Mlhf = Mtim = Mvir,1 + Mvir,2. However, comparison with apostle simulations reveals that, contrary to what the SCM states, a relatively large fraction of the mass that perturbs the local Hubble flow and drives the relative trajectory of the main galaxies is not contained within Rvir, and that the amount of 'extravirial' mass tends to increase in galaxies with a slow accretion rate. In contrast, modelling the peculiar velocities around the Local Group returns an unbiased constraint on the virial mass ratio of the main galaxy pair. Adopting the outer halo profile found in N-body simulations, which scales as ρ ˜ R-4 at R ≳ Rvir, indicates that the galaxy masses perturbing the local Hubble flow roughly correspond to the asymptotically convergent (total) masses of the individual haloes. We show that estimates of Mvir based on the dynamics of tracers at R ≫ Rvir require a priori information on the internal matter distribution and the growth rate of the main galaxies, both of which are typically difficult to quantify.
Dark matter in the outer solar system
Owen, T.; Cruikshank, D.; De Bergh, C.; Geballe, T.
1994-01-01
There are now a large number of small bodies in the outer solar system that are known to be covered with dark material. Attempts to identify that material have been thwarted by the absence of discrete absorption features in the reflection spectra of these planetesimals. An absorption at 2.2 micrometers that appeared to be present in several objects has not been confirmed by new observations. Three absorptions in the spectrum of the unusually red planetesimal 5145 Pholus are well-established, but their identity remains a mystery.
DEFF Research Database (Denmark)
Lundgaard Andersen, Linda
2012-01-01
involving people to people interactions offered by psychodynamic theories and methods take up a pivotal position. Psychoanalytic organisational and work life research explores how work, organisations and individuals are affected by psychic dynamics, the influence of the unconscious in the forms of human...... development and interaction situated in a societal context. Based on this substantial work I draw upon two influential psychoanalytical positions—the British Tavistock position and German psychoanalytic social psychology in order to situate and identify how to understand the inner and outer life at work...
The urgency of outer territories anthropology
Directory of Open Access Journals (Sweden)
Miloš Milenković
2016-02-01
Full Text Available In the context of transforming a part of Serbian anthropology into social theoretic management of identity, I suggest both comparative historiographic and ethnographic learning from societies with similar post-colonial experience, with the aim to include the discipline into an urgent defense of Serbia and Belgrade from further ethno-profiteering interests of elites in/from outer territories, left over on the ruins of our ill judged, resource incompatible, exaggerated or immoral twentieth century adventures. Serbian anthropology, written by anthropologists to whom Serbia and Belgrade are "homeland" by origin or civilized choice, should play the key role in the defense of Serbian citizens from the interest of elites in/from the outer "homelands", particularly by revealing the processes for which it is, as a discipline, most expert at – the professionalization of ethnicity, interactive and hybrid nature of identity, instrumental nature of tradition and the identity politics in general. Having in mind the latest attempt, a particularly successful one, conducted by the end of the 20th and the beginning of the 21st century that the lives, health, well-being, dignity and future of persons born in and loyal to the interest of Serbia and Belgrade, in large scale, thoroughly and long term be sacrificed and dedicated to the interests of ethno-profiteering elites in/from outer territories, in this article I point to the possibility to, along with the comparative learning from the above mentioned post-colonial experiences, delicate experiences of urgent anthropology be applied as well as the rich tradition of collective research. This text analyzes the results of first such research, that represenst the initial, praiseworthy and a brave step in the wise striving to engage social sciences and humanities in a search of expert and not mythical/daily-political solutions of the key problem of the Serbian nation – that of how to settle the interests of the
Potential alternative energy technologies on the Outer Continental Shelf.
Energy Technology Data Exchange (ETDEWEB)
Elcock, D.; Environmental Assessment
2007-04-20
This technical memorandum (TM) describes the technology requirements for three alternative energy technologies for which pilot and/or commercial projects on the U.S. Outer Continental Shelf (OCS) are likely to be proposed within the next five to seven years. For each of the alternative technologies--wind, wave, and ocean current--the TM first presents an overview. After each technology-specific overview, it describes the technology requirements for four development phases: site monitoring and testing, construction, operation, and decommissioning. For each phase, the report covers the following topics (where data are available): facility description, electricity generated, ocean area (surface and bottom) occupied, resource requirements, emissions and noise sources, hazardous materials stored or used, transportation requirements, and accident potential. Where appropriate, the TM distinguishes between pilot-scale (or demonstration-scale) facilities and commercial-scale facilities.
Perturbativity in the seesaw mechanism
International Nuclear Information System (INIS)
Asaka, Takehiko; Tsuyuki, Takanao
2016-01-01
We consider the Standard Model extended by right-handed neutrinos to explain massive neutrinos through the seesaw mechanism. The new fermion can be observed when it has a sufficiently small mass and large mixings to left-handed neutrinos. If such a particle is the lightest right-handed neutrino, its contribution to the mass matrix of active neutrinos needs to be canceled by that of a heavier one. Yukawa couplings of the heavier one are then larger than those of the lightest one. We show that the perturbativity condition gives a severe upper bound on the mixing of the lightest right-handed neutrino, depending on the masses of heavier ones. Models of high energy phenomena, such as leptogenesis, can be constrained by low energy experiments.
Initial conditions for cosmological perturbations
Ashtekar, Abhay; Gupt, Brajesh
2017-02-01
Penrose proposed that the big bang singularity should be constrained by requiring that the Weyl curvature vanishes there. The idea behind this past hypothesis is attractive because it constrains the initial conditions for the universe in geometric terms and is not confined to a specific early universe paradigm. However, the precise statement of Penrose’s hypothesis is tied to classical space-times and furthermore restricts only the gravitational degrees of freedom. These are encapsulated only in the tensor modes of the commonly used cosmological perturbation theory. Drawing inspiration from the underlying idea, we propose a quantum generalization of Penrose’s hypothesis using the Planck regime in place of the big bang, and simultaneously incorporating tensor as well as scalar modes. Initial conditions selected by this generalization constrain the universe to be as homogeneous and isotropic in the Planck regime as permitted by the Heisenberg uncertainty relations.
Initial conditions for cosmological perturbations
International Nuclear Information System (INIS)
Ashtekar, Abhay; Gupt, Brajesh
2017-01-01
Penrose proposed that the big bang singularity should be constrained by requiring that the Weyl curvature vanishes there. The idea behind this past hypothesis is attractive because it constrains the initial conditions for the universe in geometric terms and is not confined to a specific early universe paradigm. However, the precise statement of Penrose’s hypothesis is tied to classical space-times and furthermore restricts only the gravitational degrees of freedom. These are encapsulated only in the tensor modes of the commonly used cosmological perturbation theory. Drawing inspiration from the underlying idea, we propose a quantum generalization of Penrose’s hypothesis using the Planck regime in place of the big bang, and simultaneously incorporating tensor as well as scalar modes. Initial conditions selected by this generalization constrain the universe to be as homogeneous and isotropic in the Planck regime as permitted by the Heisenberg uncertainty relations . (paper)
Curvature perturbations from dimensional decoupling
Giovannini, Massimo
2005-01-01
The scalar modes of the geometry induced by dimensional decoupling are investigated. In the context of the low energy string effective action, solutions can be found where the spatial part of the background geometry is the direct product of two maximally symmetric Euclidean manifolds whose related scale factors evolve at a dual rate so that the expanding dimensions first accelerate and then decelerate while the internal dimensions always contract. After introducing the perturbative treatment of the inhomogeneities, a class of five-dimensional geometries is discussed in detail. Quasi-normal modes of the system are derived and the numerical solution for the evolution of the metric inhomogeneities shows that the fluctuations of the internal dimensions provide a term that can be interpreted, in analogy with the well-known four-dimensional situation, as a non-adiabatic pressure density variation. Implications of this result are discussed with particular attention to string cosmological scenarios.
Magnetohydrodynamic Convection in the Outer Core and its Geodynamic Consequences
Kuang, Weijia; Chao, Benjamin F.; Fang, Ming
2004-01-01
The Earth's fluid outer core is in vigorous convection through much of the Earth's history. In addition to generating and maintaining Earth s time-varying magnetic field (geodynamo), the core convection also generates mass redistribution in the core and a dynamical pressure field on the core-mantle boundary (CMB). All these shall result in various core-mantle interactions, and contribute to surface geodynamic observables. For example, electromagnetic core-mantle coupling arises from finite electrically conducting lower mantle; gravitational interaction occurs between the cores and the heterogeneous mantle; mechanical coupling may also occur when the CMB topography is aspherical. Besides changing the mantle rotation via the coupling torques, the mass-redistribution in the core shall produce a spatial-temporal gravity anomaly. Numerical modeling of the core dynamical processes contributes in several geophysical disciplines. It helps explain the physical causes of surface geodynamic observables via space geodetic techniques and other means, e.g. Earth's rotation variation on decadal time scales, and secular time-variable gravity. Conversely, identification of the sources of the observables can provide additional insights on the dynamics of the fluid core, leading to better constraints on the physics in the numerical modeling. In the past few years, our core dynamics modeling efforts, with respect to our MoSST model, have made significant progress in understanding individual geophysical consequences. However, integrated studies are desirable, not only because of more mature numerical core dynamics models, but also because of inter-correlation among the geophysical phenomena, e.g. mass redistribution in the outer core produces not only time-variable gravity, but also gravitational core-mantle coupling and thus the Earth's rotation variation. They are expected to further facilitate multidisciplinary studies of core dynamics and interactions of the core with other
Cosmics in the LHCb Outer Tracker
Aaij, Roel
2010-01-01
The LHCb experiment at the Large Hadron Collider studies the decay of B mesons to test the description of CP violation in the Standard Model and to search for new physics. The decay $B_s \\to \\mu^+ \\mu^-$ has been identified as very promising in the search for new physics. An excellent invariant mass resolution is required to suppress backgrounds to this decay. This in turn requires a momentum resolution of dp/p = 0.4%. The Outer Tracker is part of the LHCb tracking system and has been commissioned with cosmic muons. The noise in the Outer Tracker is shown to be less than 0.05%. To use drift time information in the reconstruction of cosmic tracks, the event time must be known. Four methods to obtain the event time are studied and compared. It is shown that the event time can be obtained with a resolution better than 2.6 ns. Using drift time information, tracks are reconstructed with a resolution of 344 $\\mu$m. Knowledge of the event time enables the calibration of electronic time offsets and the r(t)– relati...
Gamma rays from pulsar outer gaps
International Nuclear Information System (INIS)
Chiang, J.; Romani, R.W.; Cheng Ho
1993-01-01
We describe a gamma ray pulsar code which computes the high energy photon emissivities from vacuum gaps in the outer magnetosphere, after the model outlined by Cheng, Ho and Ruderman (1986) and Ho (1989). Pair-production due to photon-photon interactions and radiation processes including curvature, synchrotron and inverse Compton processes are computed with an iterative scheme which converges to self-consistent photon and particle distributions for a sampling of locations in the outer magnetosphere. We follow the photons from these distributions as they propagate through the pulsar magnetosphere toward a distant observer. We include the effects of relativistic aberration, time-of-flight delays and reabsorption by photon-photon pair-production to determine an intensity map of the high energy pulsar emission on the sky. Using data from radio and optical observations to constrain the geometry of the magnetosphere as well as the possible observer viewing angles, we derive light curves and phase dependent spectra which can be directly compared to data from the Compton Observatory. Observations for Crab, Vela and the recently identified gamma ray pulsars Geminga, PSR1706-44 aNd PSR 1509-58 will provide important tests of our model calculations, help us to improve our picture of the relevant physics at work in pulsar magnetospheres and allow us to comment on the implications for future pulsar discoveries
Residual Stress Testing of Outer 3013 Containers
International Nuclear Information System (INIS)
Dunn, K.
2004-01-01
A Gas Tungsten Arc Welded (GTAW) outer 3013 container and a laser welded outer 3013 container have been tested for residual stresses according to the American Society for Testing Materials (ASTM) Standard G-36-94 [1]. This ASTM standard describes a procedure for conducting stress-corrosion cracking tests in boiling magnesium chloride (MgCl2) solution. Container sections in both the as-fabricated condition as well as the closure welded condition were evaluated. Significantly large residual stresses were observed in the bottom half of the as-fabricated container, a result of the base to can fabrication weld because through wall cracks were observed perpendicular to the weld. This observation indicates that regardless of the closure weld technique, sufficient residual stresses exist in the as-fabricated container to provide the stress necessary for stress corrosion cracking of the container, at the base fabrication weld. Additionally, sufficiently high residual stresses were observed in both the lid and the body of the GTAW as well as the laser closure welded containers. The stresses are oriented perpendicular to the closure weld in both the container lid and the container body. Although the boiling MgCl2 test is not a quantitative test, a comparison of the test results from the closure welds shows that there are noticeably more through wall cracks in the laser closure welded container than in the GTAW closure welded container
Radioiodination of an outer membrane protein in intact Rickettsia prowazekii
International Nuclear Information System (INIS)
Smith, D.K.; Winkler, H.H.
1980-01-01
Intact Rickettsia prowazekii was radiolabeled with the glucose oxidase-lactoperoxidase method of iodination. Separation of the rickettsial extract into cytoplasmic, outer and inner membrane fractions demonstrated that the outer membrane was preferentially labeled. Analysis of the polypeptides of these fractions on high-resolution slab polyacrylamide gels showed that most of the 125 I was in polypeptide T49, an outer membrane constituent. Additional outer membrane polypeptides were iodinated in broken envelope preparations, demonstrating that T49 is uniquely accessible to the external environment and the asymmetric polypeptide organization of the outer membrane
Closed form bound-state perturbation theory
Directory of Open Access Journals (Sweden)
Ollie J. Rose
1980-01-01
Full Text Available The perturbed Schrödinger eigenvalue problem for bound states is cast into integral form using Green's Functions. A systematic algorithm is developed and applied to the resulting equation giving rise to approximate solutions expressed as functions of the given perturbation parameter. As a by-product, convergence radii for the traditional Rayleigh-Schrödinger and Brillouin-Wigner perturbation theories emerge in a natural way.
The neutron field perturbation effect in the Dalat Reactor
Energy Technology Data Exchange (ETDEWEB)
Huy, Ngo Quang [Centre for Nuclear Technique Application, Ho Chi Minh City (Viet Nam); Thong, Ha Van; Long, Vu Hai; Khang, Ngo Phu; Binh, Nguyen Duc; Tuan, Nguyen Minh; Vinh, Le Vinh [Nuclear Research Inst., Da Lat (Viet Nam)
1994-10-01
The perturbation effect of the thermal neutron field of the Dalat reactor is investigated when a fuel element is replaced by a water column or a plexiglass rod. In consequence, it is possible to replace the measurement of the relative distribution of the thermal neutron field on the surface of fuel element by that in the water column or in the plexiglass rod. (author). 5 refs. 4 figs. 4 tabs.
Kato expansion in quantum canonical perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Nikolaev, Andrey, E-mail: Andrey.Nikolaev@rdtex.ru [Institute of Computing for Physics and Technology, Protvino, Moscow Region, Russia and RDTeX LTD, Moscow (Russian Federation)
2016-06-15
This work establishes a connection between canonical perturbation series in quantum mechanics and a Kato expansion for the resolvent of the Liouville superoperator. Our approach leads to an explicit expression for a generator of a block-diagonalizing Dyson’s ordered exponential in arbitrary perturbation order. Unitary intertwining of perturbed and unperturbed averaging superprojectors allows for a description of ambiguities in the generator and block-diagonalized Hamiltonian. We compare the efficiency of the corresponding computational algorithm with the efficiencies of the Van Vleck and Magnus methods for high perturbative orders.
Perturbative spacetimes from Yang-Mills theory
Energy Technology Data Exchange (ETDEWEB)
Luna, Andrés [School of Physics and Astronomy, University of Glasgow,Glasgow G12 8QQ, Scotland (United Kingdom); Monteiro, Ricardo [Theoretical Physics Department, CERN,Geneva (Switzerland); Nicholson, Isobel; Ochirov, Alexander; O’Connell, Donal [Higgs Centre for Theoretical Physics,School of Physics and Astronomy, The University of Edinburgh,Edinburgh EH9 3JZ, Scotland (United Kingdom); Westerberg, Niclas [Institute of Photonics and Quantum Sciences,School of Engineering and Physical Sciences, Heriot-Watt University,Edinburgh (United Kingdom); Higgs Centre for Theoretical Physics,School of Physics and Astronomy, The University of Edinburgh,Edinburgh EH9 3JZ, Scotland (United Kingdom); White, Chris D. [Centre for Research in String Theory,School of Physics and Astronomy, Queen Mary University of London,327 Mile End Road, London E1 4NS (United Kingdom)
2017-04-12
The double copy relates scattering amplitudes in gauge and gravity theories. In this paper, we expand the scope of the double copy to construct spacetime metrics through a systematic perturbative expansion. The perturbative procedure is based on direct calculation in Yang-Mills theory, followed by squaring the numerator of certain perturbative diagrams as specified by the double-copy algorithm. The simplest spherically symmetric, stationary spacetime from the point of view of this procedure is a particular member of the Janis-Newman-Winicour family of naked singularities. Our work paves the way for applications of the double copy to physically interesting problems such as perturbative black-hole scattering.
Kato expansion in quantum canonical perturbation theory
International Nuclear Information System (INIS)
Nikolaev, Andrey
2016-01-01
This work establishes a connection between canonical perturbation series in quantum mechanics and a Kato expansion for the resolvent of the Liouville superoperator. Our approach leads to an explicit expression for a generator of a block-diagonalizing Dyson’s ordered exponential in arbitrary perturbation order. Unitary intertwining of perturbed and unperturbed averaging superprojectors allows for a description of ambiguities in the generator and block-diagonalized Hamiltonian. We compare the efficiency of the corresponding computational algorithm with the efficiencies of the Van Vleck and Magnus methods for high perturbative orders.
Perturbation methods for power and reactivity reconstruction
International Nuclear Information System (INIS)
Palmiotti, G.; Salvatores, M.; Estiot, J.C.; Broccoli, U.; Bruna, G.; Gomit, J.M.
1987-01-01
This paper deals with recent developments and applications in perturbation methods. Two types of methods are used. The first one is an explicit method, which allows the explicit reconstruction of a perturbed flux using a linear combination of a library of functions. In our application, these functions are the harmonics (i.e. the high order eigenfunctions of the system). The second type is based on the Generalized Perturbation Theory GPT and needs the calculation of an importance function for each integral parameter of interest. Recent developments of a particularly useful high order formulation allows to obtain satisfactory results also for very large perturbations
On adiabatic perturbations in the ekpyrotic scenario
International Nuclear Information System (INIS)
Linde, A.; Mukhanov, V.; Vikman, A.
2010-01-01
In a recent paper, Khoury and Steinhardt proposed a way to generate adiabatic cosmological perturbations with a nearly flat spectrum in a contracting Universe. To produce these perturbations they used a regime in which the equation of state exponentially rapidly changed during a short time interval. Leaving aside the singularity problem and the difficult question about the possibility to transmit these perturbations from a contracting Universe to the expanding phase, we will show that the methods used in Khoury are inapplicable for the description of the cosmological evolution and of the process of generation of perturbations in this scenario
Structure of Rotavirus Outer-Layer Protein VP7 Bound with a Neutralizing Fab
Energy Technology Data Exchange (ETDEWEB)
Aoki, Scott T.; Settembre, Ethan C.; Trask, Shane D.; Greenberg, Harry B.; Harrison, Stephen C.; Dormitzer, Philip R.; (Stanford-MED); (CH-Boston)
2009-06-17
Rotavirus outer-layer protein VP7 is a principal target of protective antibodies. Removal of free calcium ions (Ca{sup 2+}) dissociates VP7 trimers into monomers, releasing VP7 from the virion, and initiates penetration-inducing conformational changes in the other outer-layer protein, VP4. We report the crystal structure at 3.4 angstrom resolution of VP7 bound with the Fab fragment of a neutralizing monoclonal antibody. The Fab binds across the outer surface of the intersubunit contact, which contains two Ca{sup 2+} sites. Mutations that escape neutralization by other antibodies suggest that the same region bears the epitopes of most neutralizing antibodies. The monovalent Fab is sufficient to neutralize infectivity. We propose that neutralizing antibodies against VP7 act by stabilizing the trimer, thereby inhibiting the uncoating trigger for VP4 rearrangement. A disulfide-linked trimer is a potential subunit immunogen.
Effects of 3D magnetic perturbations on toroidal plasmas
International Nuclear Information System (INIS)
Callen, J.D.
2011-01-01
Small three-dimensional (3D) magnetic field perturbations have many interesting and possibly useful effects on tokamak and quasi-symmetric stellarator plasmas. Plasma transport equations that include these effects, most notably on diamagnetic-level toroidal plasma flows, have recently been developed. The 3D field perturbations and their plasma effects can be classified according to their toroidal mode number n: low n (say 1-5) resonant (with field line pitch, q = m/n) and non-resonant fields, medium n (∼20, due to toroidal field ripple) and high n (due to microturbulence). Low n non-resonant fields induce a neoclassical toroidal viscosity (NTV) that damps toroidal rotation throughout the plasma towards an offset rotation in the counter-current direction. Recent tokamak experiments have generally confirmed and exploited these predictions by applying external low n non-resonant magnetic perturbations. Medium n toroidal field ripple produces similar effects plus possible ripple-trapping NTV effects and ion direct losses in the edge. A low n (e.g. n = 1) resonant field is mostly shielded by the toroidally rotating plasma at and inside the resonant (rational) surface. If it is large enough it can stop plasma rotation at the rational surface, facilitate magnetic reconnection there and lead to a growing stationary magnetic island (locked mode), which often causes a plasma disruption. Externally applied 3D magnetic perturbations usually have many components. In the plasma their lowest n (e.g. n = 1) externally resonant components can be amplified by kink-type plasma responses, particularly at high β. Low n plasma instabilities (e.g. resistive wall modes, neoclassical tearing modes) cause additional 3D magnetic perturbations in tokamak plasmas. Tearing modes in their nonlinear (Rutherford) regime bifurcate the topology and form magnetic islands. Finally, multiple resonant magnetic perturbations (RMPs) can, if not shielded by plasma rotation effects, cause local magnetic
Outer membrane lipoprotein biogenesis: Lol is not the end.
Konovalova, Anna; Silhavy, Thomas J
2015-10-05
Bacterial lipoproteins are lipid-anchored proteins that contain acyl groups covalently attached to the N-terminal cysteine residue of the mature protein. Lipoproteins are synthesized in precursor form with an N-terminal signal sequence (SS) that targets translocation across the cytoplasmic or inner membrane (IM). Lipid modification and SS processing take place at the periplasmic face of the IM. Outer membrane (OM) lipoproteins take the localization of lipoproteins (Lol) export pathway, which ends with the insertion of the N-terminal lipid moiety into the inner leaflet of the OM. For many lipoproteins, the biogenesis pathway ends here. We provide examples of lipoproteins that adopt complex topologies in the OM that include transmembrane and surface-exposed domains. Biogenesis of such lipoproteins requires additional steps beyond the Lol pathway. In at least one case, lipoprotein sequences reach the cell surface by being threaded through the lumen of a beta-barrel protein in an assembly reaction that requires the heteropentomeric Bam complex. The inability to predict surface exposure reinforces the importance of experimental verification of lipoprotein topology and we will discuss some of the methods used to study OM protein topology. © 2015 The Author(s).
Encrenaz, T; Owen, T. C; Sotin, C
2005-01-01
This volume gives an integrated summary of the science related to the four giant planets in our solar system. It is the result of an ISSI workshop on «A comparative study of the outer planets before the exploration of Saturn by Cassini-Huygens» which was held at ISSI in Bern on January 12-16, 2004. Representatives of several scientific communities, such as planetary scientists, astronomers, space physicists, chemists and astrobiologists have met with the aim to review the knowledge on four major themes: (1) the study of the formation and evolution processes of the outer planets and their satellites, beginning with the formation of compounds and planetesimals in the solar nebula, and the subsequent evolution of the interiors of the outer planets, (2) a comparative study of the atmospheres of the outer planets and Titan, (3) the study of the planetary magnetospheres and their interactions with the solar wind, and (4) the formation and properties of satellites and rings, including their interiors, surfaces, an...
Directory of Open Access Journals (Sweden)
Deirdre R Ducken
Full Text Available Anaplasma marginale is a tick-borne rickettsial pathogen of cattle with a worldwide distribution. Currently a safe and efficacious vaccine is unavailable. Outer membrane protein (OMP extracts or a defined surface protein complex reproducibly induce protective immunity. However, there are several knowledge gaps limiting progress in vaccine development. First, are these OMPs conserved among the diversity of A. marginale strains circulating in endemic regions? Second, are the most highly conserved outer membrane proteins in the immunogens recognized by immunized and protected animals? Lastly, can this subset of OMPs recognized by antibody from protected vaccinates and conserved among strains recapitulate the protection of outer membrane vaccines? To address the first goal, genes encoding OMPs AM202, AM368, AM854, AM936, AM1041, and AM1096, major subdominant components of the outer membrane, were cloned and sequenced from geographically diverse strains and isolates. AM202, AM936, AM854, and AM1096 share 99.9 to 100% amino acid identity. AM1041 has 97.1 to 100% and AM368 has 98.3 to 99.9% amino acid identity. While all four of the most highly conserved OMPs were recognized by IgG from animals immunized with outer membranes, linked surface protein complexes, or unlinked surface protein complexes and shown to be protected from challenge, the highest titers and consistent recognition among vaccinates were to AM854 and AM936. Consequently, animals were immunized with recombinant AM854 and AM936 and challenged. Recombinant vaccinates and purified outer membrane vaccinates had similar IgG and IgG2 responses to both proteins. However, the recombinant vaccinates developed higher bacteremia after challenge as compared to adjuvant-only controls and outer membrane vaccinates. These results provide the first evidence that vaccination with specific antigens may exacerbate disease. Progressing from the protective capacity of outer membrane formulations to
Recurrent Neural Network for Computing Outer Inverse.
Živković, Ivan S; Stanimirović, Predrag S; Wei, Yimin
2016-05-01
Two linear recurrent neural networks for generating outer inverses with prescribed range and null space are defined. Each of the proposed recurrent neural networks is based on the matrix-valued differential equation, a generalization of dynamic equations proposed earlier for the nonsingular matrix inversion, the Moore-Penrose inversion, as well as the Drazin inversion, under the condition of zero initial state. The application of the first approach is conditioned by the properties of the spectrum of a certain matrix; the second approach eliminates this drawback, though at the cost of increasing the number of matrix operations. The cases corresponding to the most common generalized inverses are defined. The conditions that ensure stability of the proposed neural network are presented. Illustrative examples present the results of numerical simulations.
Ageing of the LHCb outer tracker
Blom, M R; Tuning, N
2009-01-01
The modules of the LHCb outer tracker have shown to suffer severe gain loss under moderate irradiation. This process is called ageing. Ageing of the modules results from contamination of the gas system by glue, araldite AY 103-1, used in their construction. In this thesis the ageing process will be shown. The schemes known to reduce, reverse, or prevent ageing have been investigated to determine their effect on the detector performance. The addition of O2 to the gas mixture lowers the detector response by an acceptable amount and does not affect the gas transport properties significantly. The ageing rate is decreased after extensive flushing and HV training could eventually repair the irradiation damage. The risks of HV training have been assessed. Furthermore, several gaseous and aquatic additions have been tested for their capability to prevent, or moderate ageing, but none showed significant improvement.
The fate of the outer plasmasphere
International Nuclear Information System (INIS)
Elphic, R.C.; Thomsen, M.F.; Borovsky, J.E.
1997-01-01
Both the solar wind and the ionosphere contribute to Earth close-quote s magnetospheric plasma environment. However, it is not widely appreciated that the plasmasphere is a large reservoir of ionospheric ions that can be tapped to populate the plasma sheet. We employ empirical models of high-latitude ionospheric convection and the geomagnetic field to describe the transport of outer plasmasphere flux tubes from the dayside, over the polar cap and into the magnetotail during the early phases of a geomagnetic storm. We calculate that this process can give rise to high densities of cold plasma in the magnetotail lobes and in the near-Earth plasma sheet during times of enhanced geomagnetic activity, and especially during storms. This model can help explain both polar cap ionization patches and the presence of cold flowing ions downtail.copyright 1997 American Geophysical Union
Impulsive ion acceleration in earth's outer magnetosphere
International Nuclear Information System (INIS)
Baker, D.N.; Belian, R.D.
1985-01-01
Considerable observational evidence is found that ions are accelerated to high energies in the outer magnetosphere during geomagnetic disturbances. The acceleration often appears to be quite impulsive causing temporally brief (10's of seconds), very intense bursts of ions in the distant plasma sheet as well as in the near-tail region. These ion bursts extend in energy from 10's of keV to over 1 MeV and are closely associated with substorm expansive phase onsets. Although the very energetic ions are not of dominant importance for magnetotail plasma dynamics, they serve as an important tracer population. Their absolute intensity and brief temporal appearance bespeaks a strong and rapid acceleration process in the near-tail, very probably involving large induced electric fields substantially greater than those associated with cross-tail potential drops. Subsequent to their impulsive acceleration, these ions are injected into the outer trapping regions forming ion ''drift echo'' events, as well as streaming tailward away from their acceleration site in the near-earth plasma sheet. Most auroral ion acceleration processes occur (or are greatly enhanced) during the time that these global magnetospheric events are occurring in the magnetotail. A qualitative model relating energetic ion populations to near-tail magnetic reconnection at substorm onset followed by global redistribution is quite successful in explaining the primary observational features. Recent measurements of the elemental composition and charge-states have proven valuable for showing the source (solar wind or ionosphere) of the original plasma population from which the ions were accelerated
On the Existence of Regular and Irregular Outer Moons Orbiting the Pluto–Charon System
Energy Technology Data Exchange (ETDEWEB)
Michaely, Erez; Perets, Hagai B.; Grishin, Evgeni [Physics Department, Technion—Israel Institute of Technology, Haifa 3200004 (Israel)
2017-02-10
The dwarf planet Pluto is known to host an extended system of five co-planar satellites. Previous studies have explored the formation and evolution of the system in isolation, neglecting perturbative effects by the Sun. Here we show that secular evolution due to the Sun can strongly affect the evolution of outer satellites and rings in the system, if such exist. Although precession due to extended gravitational potential from the inner Pluto–Charon binary quench such secular evolution up to a {sub crit} ∼ 0.0035 au (∼0.09 R {sub Hill} the Hill radius; including all of the currently known satellites), outer orbits can be significantly altered. In particular, we find that co-planar rings and satellites should not exist beyond a {sub crit}; rather, satellites and dust particles in these regions secularly evolve on timescales ranging between 10{sup 4} and 10{sup 6} years, and quasi-periodically change their inclinations and eccentricities through secular evolution (Lidov–Kozai oscillations). Such oscillations can lead to high inclinations and eccentricities, constraining the range where such satellites (and dust particles) can exist without crossing the orbits of the inner satellites or crossing the outer Hill stability range. Outer satellites, if such exist are therefore likely to be irregular satellites, with orbits limited to be non-circular and/or highly inclined. Current observations, including the recent data from the New-Horizons mission explored only inner regions (<0.0012 au) and excluded the existence of additional satellites; however, the irregular satellites discussed here should reside farther, in the yet uncharted regions around Pluto.
On the Existence of Regular and Irregular Outer Moons Orbiting the Pluto–Charon System
International Nuclear Information System (INIS)
Michaely, Erez; Perets, Hagai B.; Grishin, Evgeni
2017-01-01
The dwarf planet Pluto is known to host an extended system of five co-planar satellites. Previous studies have explored the formation and evolution of the system in isolation, neglecting perturbative effects by the Sun. Here we show that secular evolution due to the Sun can strongly affect the evolution of outer satellites and rings in the system, if such exist. Although precession due to extended gravitational potential from the inner Pluto–Charon binary quench such secular evolution up to a crit ∼ 0.0035 au (∼0.09 R Hill the Hill radius; including all of the currently known satellites), outer orbits can be significantly altered. In particular, we find that co-planar rings and satellites should not exist beyond a crit ; rather, satellites and dust particles in these regions secularly evolve on timescales ranging between 10 4 and 10 6 years, and quasi-periodically change their inclinations and eccentricities through secular evolution (Lidov–Kozai oscillations). Such oscillations can lead to high inclinations and eccentricities, constraining the range where such satellites (and dust particles) can exist without crossing the orbits of the inner satellites or crossing the outer Hill stability range. Outer satellites, if such exist are therefore likely to be irregular satellites, with orbits limited to be non-circular and/or highly inclined. Current observations, including the recent data from the New-Horizons mission explored only inner regions (<0.0012 au) and excluded the existence of additional satellites; however, the irregular satellites discussed here should reside farther, in the yet uncharted regions around Pluto.
Perturbed angular correlations and distributions
International Nuclear Information System (INIS)
Makaryunas, K.
1976-01-01
The present index comprises original works and review papers on the perturbed angular correlations (PAC) and distributions (PAD). The articles published in the Soviet and foreign journals as well as the materials of conferences, monographs and collections published in the USSR and abroad, the preprints produced by various institutes and abstracts of disertations are included from 1948 up to 1973. The whole material compiled in this index is divided into three parts. Part one is a bibliographic index. All papers in this part are divided into three sections. Section one comprises the papers devoted to the theoretical works on PAC, review papers, monographs, materials of conferences. Section two deals with the works of methodical character where correlation spectrometers as well as the treatment of experimental data are described. In section three experimental works with concrete nuclei are compiled. Part two gives the characteristic of works performed with concrete nuclei. This part is presented in the form of the table in which the works are systematized according to the chemical elements and isotopes. The table shows the characteristics of the nuclear levels used in the investigations by PAC as well as brief characteristics of experiments and results obtained. Part three - appendix contains alphabetic index of the authors, the list of the used editions with the abbreviations of the titles of these editions. The lists indicating the dynamic of the quantity of works on PAC and the distribution according to the literature sources are also given
Chiral perturbation theory with nucleons
International Nuclear Information System (INIS)
Meissner, U.G.
1991-09-01
I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external moments and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward-identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures of consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the methods. Some processes which are discussed are threshold photopion production, low-energy compton scattering off nucleons, πN scattering and the σ-term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon
2D heat flux pattern in ASDEX upgrade L-mode with magnetic perturbation
Energy Technology Data Exchange (ETDEWEB)
Faitsch, Michael; Sieglin, Bernhard; Eich, Thomas; Herrmann, Albrecht; Suttrop, Wolfgang [Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, D-85748 Garching (Germany); Collaboration: the ASDEDX Upgrade Team
2016-07-01
A future fusion reactor is likely to operate in high confinement mode (H-mode). This mode is associated with a periodic instability at the plasma edge that expels particles and energy. This instability is called edge localized mode (ELM). External magnetic perturbation (MP) is one technique that is thought to be able to mitigate or even suppress large ELMs in next step fusion devices such as ITER, where the ELM induced heat load for unmitigated ELMs might limit the lifetime of the divertor. Applying an external magnetic perturbation breaks the axisymmetry and leads to a 2D steady state heat flux pattern at the divertor. The ASDEX Upgrade tokamak is equipped with 16 perturbation coils, 8 above (upper row) and 8 below (lower row) the outer mid plane, toroidal equally distributed. A high resolution infra red system is measuring the heat flux at the outer target at a fixed toroidal position with a resolution of around 0.6 mm. In order to measure the 2D structure a slow rotation of the MP field was applied (1 Hz) with a toroidal mode number n=2. The differential phase between the upper and lower row was changed to investigate the effect of the alignment with the field lines at the edge. The density was varied to study the density dependence of the heat transport with applied external MP and compare it to the axisymmetric scenario.
Massive states in chiral perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Mallik, S [Saha Inst. of Nuclear Physics, Calcutta (India)
1995-08-01
It is shown that the chiral nonanalytic terms generated by {Delta}{sub 33} resonance in the nucleon self-energy is reproduced in chiral perturbation theory by perturbing appropriate local operators contained in the pion-nucleon effective Lagrangian itself. (orig.)
On the non-perturbative effects
International Nuclear Information System (INIS)
Manjavidze, J.; Voronyuk, V.
2004-01-01
The quantum correspondence principle based on the time reversibility is adopted to take into account the non-Abelian symmetry constrains. The main properties of the new strong-coupling perturbation theory which take into account non-perturbative effects are described. (author)
Scalar Quantum Electrodynamics: Perturbation Theory and Beyond
International Nuclear Information System (INIS)
Bashir, A.; Gutierrez-Guerrero, L. X.; Concha-Sanchez, Y.
2006-01-01
In this article, we calculate scalar propagator in arbitrary dimensions and gauge and the three-point scalar-photon vertex in arbitrary dimensions and Feynman gauge, both at the one loop level. We also discuss constraints on their non perturbative structure imposed by requirements of gauge invariance and perturbation theory
Fast in vivo volume dose reconstruction via reference dose perturbation
International Nuclear Information System (INIS)
Lu, Weiguo; Chen, Mingli; Mo, Xiaohu; Parnell, Donald; Olivera, Gustavo; Galmarini, Daniel
2014-01-01
Purpose: Accurate on-line reconstruction of in-vivo volume dose that accounts for both machine and patient discrepancy is not clinically available. We present a simple reference-dose-perturbation algorithm that reconstructs in-vivo volume dose fast and accurately. Methods: We modelled the volume dose as a function of the fluence map and density image. Machine (output variation, jaw/leaf position errors, etc.) and patient (setup error, weight loss, etc.) discrepancies between the plan and delivery were modelled as perturbation of the fluence map and density image, respectively. Delivered dose is modelled as perturbation of the reference dose due to change of the fluence map and density image. We used both simulated and clinical data to validate the algorithm. The planned dose was used as the reference. The reconstruction was perturbed from the reference and accounted for output-variations and the registered daily image. The reconstruction was compared with the ground truth via isodose lines and the Gamma Index. Results: For various plans and geometries, the volume doses were reconstructed in few seconds. The reconstruction generally matched well with the ground truth. For the 3%/3mm criteria, the Gamma pass rates were 98% for simulations and 95% for clinical data. The differences mainly appeared on the surface of the phantom/patient. Conclusions: A novel reference-dose-perturbation dose reconstruction model is presented. The model accounts for machine and patient discrepancy from planning. The algorithm is simple, fast, yet accurate, which makes online in-vivo 3D dose reconstruction clinically feasible.
Effect of a static external magnetic perturbation on resistive mode stability in tokamaks
International Nuclear Information System (INIS)
Fitzpatrick, R.
1994-03-01
The influence of a general static external magnetic perturbation on the stability of resistive modes in a tokamak plasma is examined. There are three main parts to this investigation. Firstly, the vacuum perturbation is expanded as a set of well-behaved toroidal ring functions and is, thereafter, specified by the coefficients of this expansion. Secondly, a dispersion relation is derived for resistive plasma instabilities in the presence of a general external perturbation and finally, this dispersion relation is solved for the amplitudes of the tearing and twisting modes driven in the plasma by a specific perturbation. It is found that the amplitudes of driven tearing and twisting modes are negligible until a certain critical perturbation strength is exceeded. Only tearing modes are driven in low-β plasmas with εβ p p ∼>1. For error-field perturbations made up of a large number of different poloidal and toroidal harmonics the critical strength to drive locked modes has a open-quote staircase close-quote variation with edge-q, characterized by strong discontinuities as coupled rational surfaces enter or leave the plasma. For single harmonic perturbations the variation with edge-q is far smoother. Both types of behaviour have been observed experimentally. The critical perturbation strength is found to decrease strongly close to an ideal external kink stability boundary. This is also in agreement with experimental observations
Importance of Plasma Response to Non-axisymmetric Perturbations in Tokamaks
International Nuclear Information System (INIS)
Park, Jong-kyu; Boozer, Allen H.; Menard, Jonathan E.; Garofalo, Andrea M.; Schaffer, Michael J.; Hawryluk, Richard J.; Kaye, Stanley M.; Gerhardt, Stefan P.; Sabbagh, Steve A. and the NSTX Team
2009-01-01
Tokamaks are sensitive to deviations from axisymmetry as small as (delta)B/B 0 ∼ 10 -4 . These non-axisymmetric perturbations greatly modify plasma confinement and performance by either destroying magnetic surfaces with subsequent locking or deforming magnetic surfaces with associated non-ambipolar transport. The Ideal Perturbed Equilibrium Code (IPEC) calculates ideal perturbed equilibria and provides important basis for understanding the sensitivity of tokamak plasmas to perturbations. IPEC calculations indicate that the ideal plasma response, or equivalently the effect by ideally perturbed plasma currents, is essential to explain locking experiments on National Spherical Torus eXperiment (NSTX) and DIII-D. The ideal plasma response is also important for Neoclassical Toroidal Viscosity (NTV) in non-ambipolar transport. The consistency between NTV theory and magnetic braking experiments on NSTX and DIII-D can be improved when the variation in the field strength in IPEC is coupled with generalized NTV theory. These plasma response effects will be compared with the previous vacuum superpositions to illustrate the importance. However, plasma response based on ideal perturbed equilibria is still not sufficiently accurate to predict the details of NTV transport, and can be inconsistent when currents associated with a toroidal torque become comparable to ideal perturbed currents
Shishkin, G. I.
2015-11-01
An initial-boundary value problem is considered for a singularly perturbed parabolic convection-diffusion equation with a perturbation parameter ɛ (ɛ ∈ (0, 1]) multiplying the highest order derivative. The stability of a standard difference scheme based on monotone approximations of the problem on a uniform mesh is analyzed, and the behavior of discrete solutions in the presence of perturbations is examined. The scheme does not converge ɛ-uniformly in the maximum norm as the number of its grid nodes is increased. When the solution of the difference scheme converges, which occurs if N -1 ≪ ɛ and N -1 0 ≪ 1, where N and N 0 are the numbers of grid intervals in x and t, respectively, the scheme is not ɛ-uniformly well conditioned or stable to data perturbations in the grid problem and to computer perturbations. For the standard difference scheme in the presence of data perturbations in the grid problem and/or computer perturbations, conditions on the "parameters" of the difference scheme and of the computer (namely, on ɛ, N, N 0, admissible data perturbations in the grid problem, and admissible computer perturbations) are obtained that ensure the convergence of the perturbed solutions. Additionally, the conditions are obtained under which the perturbed numerical solution has the same order of convergence as the solution of the unperturbed standard difference scheme.
Polar tent for reduced perturbation of NIF ignition capsules
Hammel, B. A.; Pickworth, L.; Stadermann, M.; Field, J.; Robey, H.; Scott, H. A.; Smalyuk, V.
2016-10-01
In simulations, a tent that contacts the capsule near the poles and departs tangential to the capsule surface greatly reduces the capsule perturbation, and the resulting mass injected into the hot-spot, compared to current capsule support methods. Target fabrication appears feasible with a layered tent (43-nm polyimide + 8-nm C) for increased stiffness. We are planning quantitative measurements of the resulting shell- ρR perturbation near peak implosion velocity (PV) using enhanced self-emission backlighting, achieved by adding 1% Ar to the capsule fill in Symcaps (4He + H). Layered DT implosions are also planned for an integrated test of capsule performance. We will describe the design and simulation predictions. Prepared by LLNL under Contract DE-AC52-07NA27344.
Doppler reflectometry for the investigation of poloidally propagating density perturbations
International Nuclear Information System (INIS)
Hirsch, M.; Baldzuhn, J.; Kurzan, B.; Holzhauer, E.
1999-01-01
A modification of microwave reflectometry is discussed where the direction of observation is tilted with respect to the normal onto the reflecting surface. The experiment is similar to scattering where a finite resolution in k-space exists but keeps the radial localization of reflectometry. The observed poloidal wavenumber is chosen by Bragg's condition via the tilt angle and the resolution in k-space is determined by the antenna pattern. From the Doppler shift of the reflected wave the poloidal propagation velocity of density perturbations is obtained. The diagnostic capabilities of Doppler reflectometry are investigated using full wave code calculations. The method offers the possibility to observe changes in the poloidal propagation velocity of density perturbations and their radial shear with a temporal resolution of about 10μs. (authors)
Perturbative analysis of transport and fluctuation studies on RFX
International Nuclear Information System (INIS)
Martini, S.
2002-01-01
On the RFX reversed field pinch different transport mechanisms govern the centre and the edge of the plasma. Core transport is driven by parallel transport in a stochastic magnetic field, giving rise to an outward directed particle convection velocity. At the edge, roughly corresponding to the region outside the toroidal field reversal surface (where q=0), electrostatic fluctuations are an important loss channel, but more than 50% of the power losses have been associated to localized plasma-wall interaction due to the non-axisymmetric magnetic perturbations caused by locked modes. In the paper we present the most recent progress made in the modeling and understanding of the above mechanisms underlying particle and energy transport. The paper also discusses the correlations between core and edge transport phenomena. The main tools are perturbative transport studies by pellet injection and the analysis of the contribution of intermittency processes to particle transport in the edge. (author)
HERSCHEL OBSERVATIONS OF THE T CHA TRANSITION DISK: CONSTRAINING THE OUTER DISK PROPERTIES
International Nuclear Information System (INIS)
Cieza, Lucas A.; Olofsson, Johan; Henning, Thomas; Harvey, Paul M.; Evans II, Neal J.; Pinte, Christophe; Augereau, Jean-Charles; Ménard, Francois; Merín, Bruno; Najita, Joan
2011-01-01
T Cha is a nearby (d ∼ 100 pc) transition disk known to have an optically thin gap separating optically thick inner and outer disk components. Huélamo et al. recently reported the presence of a low-mass object candidate within the gap of the T Cha disk, giving credence to the suspected planetary origin of this gap. Here we present the Herschel photometry (70, 160, 250, 350, and 500 μm) of T Cha from the 'Dust, Ice, and Gas in Time' Key Program, which bridges the wavelength range between existing Spitzer and millimeter data and provide important constraints on the outer disk properties of this extraordinary system. We model the entire optical to millimeter wavelength spectral energy distribution (SED) of T Cha (19 data points between 0.36 and 3300 μm without any major gaps in wavelength coverage). T Cha shows a steep spectral slope in the far-IR, which we find clearly favors models with outer disks containing little or no dust beyond ∼40 AU. The full SED can be modeled equally well with either an outer disk that is very compact (only a few AU wide) or a much larger one that has a very steep surface density profile. That is, T Cha's outer disk seems to be either very small or very tenuous. Both scenarios suggest a highly unusual outer disk and have important but different implications for the nature of T Cha. Spatially resolved images are needed to distinguish between the two scenarios.
HERSCHEL OBSERVATIONS OF THE T CHA TRANSITION DISK: CONSTRAINING THE OUTER DISK PROPERTIES
Energy Technology Data Exchange (ETDEWEB)
Cieza, Lucas A. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Olofsson, Johan; Henning, Thomas [Max Planck Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany); Harvey, Paul M.; Evans II, Neal J. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Pinte, Christophe; Augereau, Jean-Charles; Menard, Francois [UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d' Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, F-38041 (France); Merin, Bruno [Herschel Science Centre, European Space Agency (ESAC), P.O. Box 78, 28691 Villanueva de la Canada, Madrid (Spain); Najita, Joan, E-mail: lcieza@ifa.hawaii.edu [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 86719 (United States)
2011-11-10
T Cha is a nearby (d {approx} 100 pc) transition disk known to have an optically thin gap separating optically thick inner and outer disk components. Huelamo et al. recently reported the presence of a low-mass object candidate within the gap of the T Cha disk, giving credence to the suspected planetary origin of this gap. Here we present the Herschel photometry (70, 160, 250, 350, and 500 {mu}m) of T Cha from the 'Dust, Ice, and Gas in Time' Key Program, which bridges the wavelength range between existing Spitzer and millimeter data and provide important constraints on the outer disk properties of this extraordinary system. We model the entire optical to millimeter wavelength spectral energy distribution (SED) of T Cha (19 data points between 0.36 and 3300 {mu}m without any major gaps in wavelength coverage). T Cha shows a steep spectral slope in the far-IR, which we find clearly favors models with outer disks containing little or no dust beyond {approx}40 AU. The full SED can be modeled equally well with either an outer disk that is very compact (only a few AU wide) or a much larger one that has a very steep surface density profile. That is, T Cha's outer disk seems to be either very small or very tenuous. Both scenarios suggest a highly unusual outer disk and have important but different implications for the nature of T Cha. Spatially resolved images are needed to distinguish between the two scenarios.
The anisotropy of the cosmic background radiation from local dynamic density perturbations
International Nuclear Information System (INIS)
Dyer, C.C.; Ip, P.S.S.
1988-01-01
Contrary to the usual assumption, it is shown here that the anisotropy of the cosmic background radiation need not be dominated by perturbations at the last scattering surface. The results of computer simulations are shown in which local dynamic density perturbations, in the form of Swiss cheese holes with finite, uniform density central lumps, are the main source of anisotropy of the cosmic background radiation. (author)
Anisotropic Pressure, Transport, and Shielding of Magnetic Perturbations
International Nuclear Information System (INIS)
Mynick, H.E.; Boozer, A.H.
2008-01-01
We compute the effect on a tokamak of applying a nonaxisymmetric magnetic perturbation (delta)B. An equilibrium with scalar pressure p yields zero net radial current, and therefore zero torque. Thus, the usual approach, which assumes scalar pressure, is not self-consistent, and masks the close connection which exists between that radial current and the in-surface currents, which provide shielding or amplification of (delta)B. Here, we analytically compute the pressure anisotropy, anisotropy, p # parallel#, p # perpendicular# and ≠ p, and from this, both the radial and in-surface currents. The surface-average of the radial current recovers earlier expressions for ripple transport, while the in-surface currents provide an expression for the amount of self-consistent shielding the plasma provides.
Statistics of the outer radiation belt
International Nuclear Information System (INIS)
Rodgers, D.J.; Johnstone, A.D.
1996-01-01
The highly variable electron flux levels in the outer radiation belt come about by competition between time-dependent source and loss mechanisms. In order to identify some of the different mechanisms involved, we examine the statistics of the variability of fluxes at geostationary orbit. Data from the SEM-2 analyzer on Meteosat-3 and from GOES-7 are used. Correlation analysis is used to find time-delays between changes in flux at different energies. We see that low energy flux is added to this region during sub-storms and that higher energy fluxes appear after 2 or 3 days. Whilst the timescale for this process is brief compared to a complete cycle of the open-quote Recirculation close-quote energization process, it is consistent with the timescale of its final step endash outward radial diffusion. By isolating periods when no new injection of plasma occurs, we make an assessment of flux loss rates in a quiet magnetosphere. copyright 1996 American Institute of Physics
Perturbation analysis of linear control problems
International Nuclear Information System (INIS)
Petkov, Petko; Konstantinov, Mihail
2017-01-01
The paper presents a brief overview of the technique of splitting operators, proposed by the authors and intended for perturbation analysis of control problems involving unitary and orthogonal matrices. Combined with the technique of Lyapunov majorants and the implementation of the Banach and Schauder fixed point principles, it allows to obtain rigorous non-local perturbation bounds for a set of sensitivity analysis problems. Among them are the reduction of linear systems into orthogonal canonical forms, the feedback synthesis problem and pole assignment problem in particular, as well as other important problems in control theory and linear algebra. Key words: perturbation analysis, canonical forms, feedback synthesis
Kerr-CFT and gravitational perturbations
International Nuclear Information System (INIS)
Dias, Oscar J.C.; Reall, Harvey S.; Santos, Jorge E.
2009-01-01
Motivated by the Kerr-CFT conjecture, we investigate perturbations of the near-horizon extreme Kerr spacetime. The Teukolsky equation for a massless field of arbitrary spin is solved. Solutions fall into two classes: normal modes and traveling waves. Imposing suitable (outgoing) boundary conditions, we find that there are no unstable modes. The explicit form of metric perturbations is obtained using the Hertz potential formalism, and compared with the Kerr-CFT boundary conditions. The energy and angular momentum associated with scalar field and gravitational normal modes are calculated. The energy is positive in all cases. The behaviour of second order perturbations is discussed.
Resolution of ambiguities in perturbative QCD
International Nuclear Information System (INIS)
Nakkagawa, Hisao; Niegawa, Akira.
1984-01-01
In the perturbative QCD analyses of the deeply inelastic processes, the coupling constant depends on at least two mass-scales, the renormalization scale and the factorization scale. By integrating the coupled renormalization group equations with respect to these two mass-scales, the running coupling constant is defined. A perturbative approximation then introduces a new ambiguity, the integration-path dependence, into the theory. We show that the problem of this new ambiguity is resolved by imposing Stevenson's principle of minimal sensitivity. Together with the analogous analysis of the operator matrix element or the cut vertex, we can completely solve the problem of getting an unambiguous perturbative QCD prediction. (author)
Mass generation in perturbed massless integrable models
International Nuclear Information System (INIS)
Controzzi, D.; Mussardo, G.
2005-01-01
We extend form-factor perturbation theory to non-integrable deformations of massless integrable models, in order to address the problem of mass generation in such systems. With respect to the standard renormalisation group analysis this approach is more suitable for studying the particle content of the perturbed theory. Analogously to the massive case, interesting information can be obtained already at first order, such as the identification of the operators which create a mass gap and those which induce the confinement of the massless particles in the perturbed theory
Non-perturbative effects in supersymmetry
International Nuclear Information System (INIS)
Veneziano, G.
1987-01-01
Some non perturbative aspects of globally supersymmetric (SUSY) gauge theories are discussed. These share with their non-supersymmetric analogues interesting non perturbative features, such as the spontaneous breaking of chiral symmetries via condensates. What is peculiar about supersymmetric theories, however, is that one is able to say a lot about non-perturbative effects even without resorting to elaborate numerical calculations: general arguments, supersymmetric and chiral Ward identities and analytic, dynamical calculations will turn out to effectively determine most of the supersymmetric vacuum properties. 28 references, 5 figures
On perturbation theory for distance dependent statistics.
Energy Technology Data Exchange (ETDEWEB)
Mashkevich, S V
1994-12-31
It is known that perturbation theory for anyons has to be modified near Bose statistics in order to get correct finite results. For ``distance dependent statistics`` or anyons with smeared flux tubes, perturbation theory is in principle applicable directly but gives results which hold for too small values of the statistical parameter and, in particular, are not valid as the flux tube radius tends to zero. In this paper we discuss the way to modify perturbation theory for this situation, which allows to obtain the appropriate results. (author). 6 refs.
Solitonic Integrable Perturbations of Parafermionic Theories
Fernández-Pousa, C R; Hollowood, Timothy J; Miramontes, J L
1997-01-01
The quantum integrability of a class of massive perturbations of the parafermionic conformal field theories associated to compact Lie groups is established by showing that they have quantum conserved densities of scale dimension 2 and 3. These theories are integrable for any value of a continuous vector coupling constant, and they generalize the perturbation of the minimal parafermionic models by their first thermal operator. The classical equations-of-motion of these perturbed theories are the non-abelian affine Toda equations which admit (charged) soliton solutions whose semi-classical quantization is expected to permit the identification of the exact S-matrix of the theory.
Critical behaviors of gravity under quantum perturbations
Directory of Open Access Journals (Sweden)
ZHANG Hongsheng
2014-02-01
Full Text Available Phase transition and critical phenomenon is a very interesting topic in thermodynamics and statistical mechanics. Gravity is believed to have deep and inherent relation to thermodynamics. Near the critical point,the perturbation becomes significant. Thus for ordinary matter (governed by interactions besides gravity the critical behavior will become very different if we ignore the perturbations around the critical point,such as mean field theory. We find that the critical exponents for RN-AdS spacetime keep the same values even when we consider the full quantum perturbations. This indicates a key difference between gravity and ordinary thermodynamic system.
Sensitivity of decadal predictions to the initial atmospheric and oceanic perturbations
Energy Technology Data Exchange (ETDEWEB)
Du, H.; Garcia-Serrano, J.; Guemas, V.; Soufflet, Y. [Institut Catala de Ciencies del Clima (IC3), Barcelona (Spain); Doblas-Reyes, F.J. [Institut Catala de Ciencies del Clima (IC3), Barcelona (Spain); Institucio Catalana de Recerca i Estudis Avancats (ICREA), Barcelona (Spain); Wouters, B. [Royal Netherlands Meteorological Institute (KNMI), De Bilt (Netherlands)
2012-10-15
A coupled global atmosphere-ocean model is employed to investigate the impact of initial perturbation methods on the behaviour of five-member ensemble decadal re-forecasts. Three initial-condition perturbation strategies, atmosphere only, ocean only and atmosphere-ocean, have been used and the impact on selected variables have been investigated. The impact has been assessed in terms of climate drift, forecast quality and spread. The simulated global means of near-surface air temperature (T2M), sea surface temperature (SST) and sea ice area (SIA) for both Arctic and Antarctic show reasonably good quality, in spite of the non-negligible drift of the model. The skill in terms of correlation is not significantly affected by the particular perturbation method employed. The ensemble spread generated for T2M, SST and land surface precipitation (PCP) saturates quickly with any of the perturbation methods. However, for SIA, Atlantic meridional overturning circulation (AMOC) and ocean heat content (OHC), the spread increases substantially during the forecast time when ocean perturbations are applied. Ocean perturbations are particularly important for Antarctic SIA and OHC for the middle and deep layers of the ocean. The results will be helpful in the design of ensemble prediction experiments. (orig.)
Radiolysis of Amino Acids in Outer Solar-System Ice Analogs
Gerakines, Perry A.; Hudson, Reggie L.
2011-01-01
Amino acids have been found in cometary dust particles and in the organic component of meteorites. These molecules, important for pre-biotic chemistry and for active biological systems, might be formed in cold planetary or interstellar environments and then delivered to H20-rich surfaces in the outer solar system. Many models for the availability of organic species on Earth and elsewhere depend on the ability of these molecules to survive in radiation-rich space environments. This poster presents results of O.8-MeV proton radiolysis of ice films at lS-140K. using infrared spectroscopy, the destruction rates of glycine, alanine, and phenylalanine have been determined for both pure films and those containing amino acids diluted in H2o. our results are discussed in terms of the survivability of these molecules in the icy surfaces present in the outer solar system and the possibility of their detection by instruments on board the New Horizons spacecraft
Stability under persistent perturbation by white noise
International Nuclear Information System (INIS)
Kalyakin, L
2014-01-01
Deterministic dynamical system which has an asymptotical stable equilibrium is considered under persistent perturbation by white noise. It is well known that if the perturbation does not vanish in the equilibrium position then there is not Lyapunov's stability. The trajectories of the perturbed system diverge from the equilibrium to arbitrarily large distances with probability 1 in finite time. New concept of stability on a large time interval is discussed. The length of interval agrees the reciprocal quantity of the perturbation parameter. The measure of stability is the expectation of the square distance from the trajectory till the equilibrium position. The method of parabolic equation is applied to both estimate the expectation and prove such stability. The main breakthrough is the barrier function derived for the parabolic equation. The barrier is constructed by using the Lyapunov function of the unperturbed system
Inflation and the theory of cosmological perturbations
International Nuclear Information System (INIS)
Riotto, A.
2003-01-01
These lectures provide a pedagogical introduction to inflation and the theory of cosmological perturbations generated during inflation which are thought to be the origin of structure in the universe. (author)
't Hooft loops and perturbation theory
De Forcrand, Philippe; Noth, D; Forcrand, Philippe de; Lucini, Biagio; Noth, David
2005-01-01
We show that high-temperature perturbation theory describes extremely well the area law of SU(N) spatial 't Hooft loops, or equivalently the tension of the interface between different Z_N vacua in the deconfined phase. For SU(2), the disagreement between Monte Carlo data and lattice perturbation theory for sigma(T)/T^2 is less than 2%, down to temperatures O(10) T_c. For SU(N), N>3, the ratios of interface tensions, (sigma_k/sigma_1)(T), agree with perturbation theory, which predicts tiny deviations from the ratio of Casimirs, down to nearly T_c. In contrast, individual tensions differ markedly from the perturbative expression. In all cases, the required precision Monte Carlo measurements are made possible by a simple but powerful modification of the 'snake' algorithm.
Isocurvature perturbations in the Ekpyrotic Universe
International Nuclear Information System (INIS)
Notari, A.; Riotto, A.
2002-01-01
The Ekpyrotic scenario assumes that our visible Universe is a boundary brane in a five-dimensional bulk and that the hot Big Bang occurs when a nearly supersymmetric five-brane travelling along the fifth dimension collides with our visible brane. We show that the generation of isocurvature perturbations is a generic prediction of the Ekpyrotic Universe. This is due to the interactions in the kinetic terms between the brane modulus parameterizing the position of the five-brane in the bulk and the dilaton and volume moduli. We show how to separate explicitly the adiabatic and isocurvature modes by performing a rotation in field space. Our results indicate that adiabatic and isocurvature perturbations might be cross-correlated and that curvature perturbations might be entirely seeded by isocurvature perturbations
Simple Perturbation Example for Quantum Chemistry.
Goodfriend, P. L.
1985-01-01
Presents a simple example that illustrates various aspects of the Rayleigh-Schrodinger perturbation theory. The example is a particularly good one because it is straightforward and can be compared with both the exact solution and with experimental data. (JN)
SHARP ENTRYWISE PERTURBATION BOUNDS FOR MARKOV CHAINS.
Thiede, Erik; VAN Koten, Brian; Weare, Jonathan
For many Markov chains of practical interest, the invariant distribution is extremely sensitive to perturbations of some entries of the transition matrix, but insensitive to others; we give an example of such a chain, motivated by a problem in computational statistical physics. We have derived perturbation bounds on the relative error of the invariant distribution that reveal these variations in sensitivity. Our bounds are sharp, we do not impose any structural assumptions on the transition matrix or on the perturbation, and computing the bounds has the same complexity as computing the invariant distribution or computing other bounds in the literature. Moreover, our bounds have a simple interpretation in terms of hitting times, which can be used to draw intuitive but rigorous conclusions about the sensitivity of a chain to various types of perturbations.
Renormalization scheme-invariant perturbation theory
International Nuclear Information System (INIS)
Dhar, A.
1983-01-01
A complete solution to the problem of the renormalization scheme dependence of perturbative approximants to physical quantities is presented. An equation is derived which determines any physical quantity implicitly as a function of only scheme independent variables. (orig.)
Cosmological perturbations in the new Higgs inflation
Energy Technology Data Exchange (ETDEWEB)
Germani, Cristiano [Arnold Sommerfeld Center, Ludwig-Maximilians-University, Theresienstr, 37 80333 Muenchen (Germany); Kehagias, Alex, E-mail: cristiano.germani@lmu.de, E-mail: kehagias@central.ntua.gr [Physics Division, National Technical University of Athens, 15780 Zografou Campus, Athens (Greece)
2010-05-01
We study the cosmological perturbations created during the New Higgs inflationary phase. In the New Higgs Inflation, the Higgs boson is kinetically coupled to the Einstein tensor and only three perturbative degrees of freedom, a scalar and two tensorial (gravitational waves), propagate during Inflation. Scalar perturbations are found to match the latest WMAP-7yrs data within Standard Model Higgs parameters. Primordial gravitational waves also, although propagating with superluminal speed, are consistent with present data. Finally, we estimate the values of the parameter of the New Higgs Inflation in relation to the Higgs mass, the spectral index and amplitude of the primordial scalar perturbations showing that the unitarity bound of the theory is not violated.
Prospects of inflation with perturbed throat geometry
International Nuclear Information System (INIS)
Ali, Amna; Chingangbam, R.; Panda, Sudhakar; Sami, M.
2009-01-01
We study brane inflation in a warped deformed conifold background that includes general possible corrections to the throat geometry sourced by coupling to the bulk of a compact Calabi-Yau space. We focus specifically, on the perturbation by chiral operator of dimension 3/2 in the CFT. We find that the effective potential in this case can give rise to required number of e-foldings and the spectral index n S consistent with observation. The tensor to scalar ratio of perturbations is generally very low in this scenario. The COBE normalization, however, poses certain difficulties which can be circumvented provided model parameters are properly fine tuned. We find the numerical values of parameters which can give rise to enough inflation, observationally consistent values of density perturbations, scalar to tensor ratio of perturbations and the spectral index n S .
46 CFR 154.170 - Outer hull steel plating.
2010-10-01
... 46 Shipping 5 2010-10-01 2010-10-01 false Outer hull steel plating. 154.170 Section 154.170... STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Hull Structure § 154.170 Outer hull steel plating. (a) Except as required in paragraph (b) of this section, the...
Outer space and nuclear deterrence: problems and prospects
International Nuclear Information System (INIS)
Gasparini Alves, P.
1993-01-01
The presentation deals with the role of outer-space applications and prospects for near future developments in nuclear deterrence. Outer space capabilities of United Sates, Russian Federation, Belarus, Kazakhstan, Ukraine, China, and United Kingdom as well as other states are analyzed. Conceptual problems of offensive and defensive doctrines are reviewed together with legal implications
Newborns' Face Recognition: Role of Inner and Outer Facial Features
Turati, Chiara; Macchi Cassia, Viola; Simion, Francesca; Leo, Irene
2006-01-01
Existing data indicate that newborns are able to recognize individual faces, but little is known about what perceptual cues drive this ability. The current study showed that either the inner or outer features of the face can act as sufficient cues for newborns' face recognition (Experiment 1), but the outer part of the face enjoys an advantage…
Discrete state perturbation theory via Green's functions
International Nuclear Information System (INIS)
Rubinson, W.
1975-01-01
The exposition of stationary-state perturbation theory via the Green's function method in Goldberger and Watson's Collision Theory is reworked in a way that makes explicit its mathematical basis. It is stressed that the theory consists of the construction of, and manipulations on, a mathematical identity. The perturbation series fall out of the identity almost immediately. The logical status of the method is commented on
Algebraic renormalization. Perturbative renormalization, symmetries and anomalies
International Nuclear Information System (INIS)
Piguet, O.
1995-01-01
This book is an introduction to the algebraic method in the perturbative renormalization of relativistic quantum field theory. After a general introduction to renormalized perturbation theory the quantum action principle and Ward identities are described. Then Yang-Mills gauge theories are considered. Thereafter the BRS cohomology and descent equations are described. Then nonrenormalization theorems and topological field theories are considered. Finally an application to the bosonic string is described. (HSI)
A new perturbative approach to QCD
International Nuclear Information System (INIS)
Pervushin, V.N.; Kallies, W.; Sarikov, N.A.
1988-01-01
For the description of bound states in QED and QCD the physical perturbation theory on the spatial components of the vector over the exact solution, defined by the time one, is proposed. It is shown this perturbation theory in QCD can be redefined so that it reproduces the main elements of hadron physics: confinement, spectroscopy of light and heavy quarkonia, dual-resonance amplitudes, chiral Lagrangians and the parton model
Cylindrical dust acoustic waves with transverse perturbation
International Nuclear Information System (INIS)
Xue Jukui
2003-01-01
The nonlinear dust acoustic waves in dusty plasmas with the combined effects of bounded cylindrical geometry and the transverse perturbation are studied. Using the perturbation method, a cylindrical Kadomtsev-Petviashvili (CKP) equation that describes the dust acoustic waves is deduced for the first time. A particular solution of this CKP equation is also obtained. It is shown that the dust acoustic solitary waves can exist in the CKP equation
The triangulation in a perturbed Friedmann universe
International Nuclear Information System (INIS)
Kasai, Masumi.
1987-12-01
A formula for the parallax distance in a general space-time is shown and it is applied to the linearly perturbed Friedmann universe. Its invariance under any coordinate-gauge transformations and any infinitesimal affine transformations is also shown. Then it is applied to the Einstein-de Sitter background model, and it is found that the perturbed space-time behaves as a Friedmann-like universe with the direction-dependent H 0 and q 0 . (author)
Alternative perturbation approaches in classical mechanics
International Nuclear Information System (INIS)
Amore, Paolo; Raya, Alfredo; Fernandez, Francisco M
2005-01-01
We discuss two alternative methods, based on the Lindstedt-Poincare technique, for the removal of secular terms from the equations of perturbation theory. We calculate the period of an anharmonic oscillator by means of both approaches and show that one of them is more accurate for all values of the coupling constant. We believe that present discussion and comparison may be a suitable exercise for teaching perturbation theory in advanced undergraduate courses on classical mechanics
Double soft theorem for perturbative gravity
Saha, Arnab
2016-01-01
Following up on the recent work of Cachazo, He and Yuan \\cite{arXiv:1503.04816 [hep-th]}, we derive the double soft graviton theorem in perturbative gravity. We show that the double soft theorem derived using CHY formula precisely matches with the perturbative computation involving Feynman diagrams. In particular, we find how certain delicate limits of Feynman diagrams play an important role in obtaining this equivalence.
On perturbations of a quintom bounce
International Nuclear Information System (INIS)
Cai Yifu; Qiu Taotao; Zhang Xinmin; Brandenberger, Robert; Piao Yunsong
2008-01-01
A quintom universe with an equation of state crossing the cosmological constant boundary can provide a bouncing solution dubbed the quintom bounce and thus resolve the big bang singularity. In this paper, we investigate the cosmological perturbations of the quintom bounce both analytically and numerically. We find that the fluctuations in the dominant mode in the post-bounce expanding phase couple to the growing mode of the perturbations in the pre-bounce contracting phase
Proteomics of Aggregatibacter actinomycetemcomitans Outer Membrane Vesicles.
Directory of Open Access Journals (Sweden)
Thomas Kieselbach
Full Text Available Aggregatibacter actinomycetemcomitans is an oral and systemic pathogen associated with aggressive forms of periodontitis and with endocarditis. Outer membrane vesicles (OMVs released by this species have been demonstrated to deliver effector proteins such as cytolethal distending toxin (CDT and leukotoxin (LtxA into human host cells and to act as triggers of innate immunity upon carriage of NOD1- and NOD2-active pathogen-associated molecular patterns (PAMPs. To improve our understanding of the pathogenicity-associated functions that A. actinomycetemcomitans exports via OMVs, we studied the proteome of density gradient-purified OMVs from a rough-colony type clinical isolate, strain 173 (serotype e using liquid chromatography-tandem mass spectrometry (LC-MS/MS. This analysis yielded the identification of 151 proteins, which were found in at least three out of four independent experiments. Data are available via ProteomeXchange with identifier PXD002509. Through this study, we not only confirmed the vesicle-associated release of LtxA, and the presence of proteins, which are known to act as immunoreactive antigens in the human host, but we also identified numerous additional putative virulence-related proteins in the A. actinomycetemcomitans OMV proteome. The known and putative functions of these proteins include immune evasion, drug targeting, and iron/nutrient acquisition. In summary, our findings are consistent with an OMV-associated proteome that exhibits several offensive and defensive functions, and they provide a comprehensive basis to further disclose roles of A. actinomycetemcomitans OMVs in periodontal and systemic disease.
Computer fan performance enhancement via acoustic perturbations
Energy Technology Data Exchange (ETDEWEB)
Greenblatt, David, E-mail: davidg@technion.ac.il [Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa (Israel); Avraham, Tzahi; Golan, Maayan [Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa (Israel)
2012-04-15
Highlights: Black-Right-Pointing-Pointer Computer fan effectiveness was increased by introducing acoustic perturbations. Black-Right-Pointing-Pointer Acoustic perturbations controlled blade boundary layer separation. Black-Right-Pointing-Pointer Optimum frequencies corresponded with airfoils studies. Black-Right-Pointing-Pointer Exploitation of flow instabilities was responsible for performance improvements. Black-Right-Pointing-Pointer Peak pressure and peak flowrate were increased by 40% and 15% respectively. - Abstract: A novel technique for increasing computer fan effectiveness, based on introducing acoustic perturbations onto the fan blades to control boundary layer separation, was assessed. Experiments were conducted in a specially designed facility that simultaneously allowed characterization of fan performance and introduction of the perturbations. A parametric study was conducted to determine the optimum control parameters, namely those that deliver the largest increase in fan pressure for a given flowrate. The optimum reduced frequencies corresponded with those identified on stationary airfoils and it was thus concluded that the exploitation of Kelvin-Helmholtz instabilities, commonly observed on airfoils, was responsible for the fan blade performance improvements. The optimum control inputs, such as acoustic frequency and sound pressure level, showed some variation with different fan flowrates. With the near-optimum control conditions identified, the full operational envelope of the fan, when subjected to acoustic perturbations, was assessed. The peak pressure and peak flowrate were increased by up to 40% and 15% respectively. The peak fan efficiency increased with acoustic perturbations but the overall system efficiency was reduced when the speaker input power was accounted for.
Secondary isocurvature perturbations from acoustic reheating
Ota, Atsuhisa; Yamaguchi, Masahide
2018-06-01
The superhorizon (iso)curvature perturbations are conserved if the following conditions are satisfied: (i) (each) non adiabatic pressure perturbation is zero, (ii) the gradient terms are ignored, that is, at the leading order of the gradient expansion (iii) (each) total energy momentum tensor is conserved. We consider the case with the violation of the last two requirements and discuss the generation of secondary isocurvature perturbations during the late time universe. Second order gradient terms are not necessarily ignored even if we are interested in the long wavelength modes because of the convolutions which may pick products of short wavelength perturbations up. We then introduce second order conserved quantities on superhorizon scales under the conditions (i) and (iii) even in the presence of the gradient terms by employing the full second order cosmological perturbation theory. We also discuss the violation of the condition (iii), that is, the energy momentum tensor is conserved for the total system but not for each component fluid. As an example, we explicitly evaluate second order heat conduction between baryons and photons due to the weak Compton scattering, which dominates during the period just before recombination. We show that such secondary effects can be recast into the isocurvature perturbations on superhorizon scales if the local type primordial non Gaussianity exists a priori.
Computer fan performance enhancement via acoustic perturbations
International Nuclear Information System (INIS)
Greenblatt, David; Avraham, Tzahi; Golan, Maayan
2012-01-01
Highlights: ► Computer fan effectiveness was increased by introducing acoustic perturbations. ► Acoustic perturbations controlled blade boundary layer separation. ► Optimum frequencies corresponded with airfoils studies. ► Exploitation of flow instabilities was responsible for performance improvements. ► Peak pressure and peak flowrate were increased by 40% and 15% respectively. - Abstract: A novel technique for increasing computer fan effectiveness, based on introducing acoustic perturbations onto the fan blades to control boundary layer separation, was assessed. Experiments were conducted in a specially designed facility that simultaneously allowed characterization of fan performance and introduction of the perturbations. A parametric study was conducted to determine the optimum control parameters, namely those that deliver the largest increase in fan pressure for a given flowrate. The optimum reduced frequencies corresponded with those identified on stationary airfoils and it was thus concluded that the exploitation of Kelvin–Helmholtz instabilities, commonly observed on airfoils, was responsible for the fan blade performance improvements. The optimum control inputs, such as acoustic frequency and sound pressure level, showed some variation with different fan flowrates. With the near-optimum control conditions identified, the full operational envelope of the fan, when subjected to acoustic perturbations, was assessed. The peak pressure and peak flowrate were increased by up to 40% and 15% respectively. The peak fan efficiency increased with acoustic perturbations but the overall system efficiency was reduced when the speaker input power was accounted for.
Petersson, Hannie; Dustler, Magnus; Tingberg, Anders; Timberg, Pontus
2016-03-01
The large image volumes in breast tomosynthesis (BT) have led to large amounts of data and a heavy workload for breast radiologists. The number of slice images can be decreased by combining adjacent image planes (slabbing) but the decrease in depth resolution can considerably affect the detection of lesions. The aim of this work was to assess if thicker slabbing of the outer slice images (where lesions seldom are present) could be a viable alternative in order to reduce the number of slice images in BT image volumes. The suggested slabbing (an image volume with thick outer slabs and thin slices between) were evaluated in two steps. Firstly, a survey of the depth of 65 cancer lesions within the breast was performed to estimate how many lesions would be affected by outer slabs of different thicknesses. Secondly, a selection of 24 lesions was reconstructed with 2, 6 and 10 mm slab thickness to evaluate how the appearance of lesions located in the thicker slabs would be affected. The results show that few malignant breast lesions are located at a depth less than 10 mm from the surface (especially for breast thicknesses of 50 mm and above). Reconstruction of BT volumes with 6 mm slab thickness yields an image quality that is sufficient for lesion detection for a majority of the investigated cases. Together, this indicates that thicker slabbing of the outer slice images is a promising option in order to reduce the number of slice images in BT image volumes.
A and F stars as probes of outer Galactic disc kinematics
Harris, A.; Drew, J. E.; Farnhill, H. J.; Monguió, M.; Gebran, M.; Wright, N. J.; Drake, J. J.; Sale, S. E.
2018-04-01
Previous studies of the rotation law in the outer Galactic disc have mainly used gas tracers or clump giants. Here, we explore A and F stars as alternatives: these provide a much denser sampling in the outer disc than gas tracers and have experienced significantly less velocity scattering than older clump giants. This first investigation confirms the suitability of A stars in this role. Our work is based on spectroscopy of ˜1300 photometrically selected stars in the red calcium-triplet region, chosen to mitigate against the effects of interstellar extinction. The stars are located in two low Galactic latitude sightlines, at longitudes ℓ = 118°, sampling strong Galactic rotation shear, and ℓ = 178°, near the anticentre. With the use of Markov Chain Monte Carlo parameter fitting, stellar parameters and radial velocities are measured, and distances computed. The obtained trend of radial velocity with distance is inconsistent with existing flat or slowly rising rotation laws from gas tracers (Brand & Blitz 1993; Reid et al. 2014). Instead, our results fit in with those obtained by Huang et al. (2016) from disc clump giants that favoured rising circular speeds. An alternative interpretation in terms of spiral arm perturbation is not straight forward. We assess the role that undetected binaries in the sample and distance error may have in introducing bias, and show that the former is a minor factor. The random errors in our trend of circular velocity are within ±5 km s-1.
On the fates of minor bodies in the outer solar system
International Nuclear Information System (INIS)
Gladman, B.; Duncan, M.
1990-01-01
The equations of motion of roughly one thousand test particles in the outer solar system for up to 22.5 million years have been integrated. The test particles are placed on initially circular orbits about the sun and feel the gravitational influence of the sun and four (or in some cases two) of the giant planets. The initial conditions of the planets are obtained from their current orbital elements, and their mutual gravitational interactions are fully included. Test particles that undergo a close approach to a planet are removed from the integration. Interior to Jupiter the creation of gaps in the test-particle semimajor-axis distribution appears to be associated with resonances in the outer asteroid belt. Exterior to Neptune there is a dynamical erosion of the region just beyond the giant planets (i.e., at the inner edge of the Kuiper belt). The majority of the test particles between the giant planets are perturbed to a close approach to a planet on timescales of millions of years. These results suggest that there are very few initially circular orbits between the giant planets that are stable against a close approach to a planet over the lifetime of the solar system. 45 refs
Geocosmos: mapping outer space into a hollow earth
Energy Technology Data Exchange (ETDEWEB)
Abdelkader, M.A. (Alexandria, Egypt)
1983-04-01
The authors regards the earth's surface as a sphere and applies a purely mathematical mapping taking outer space in the Copernican universe (C) into a hollow earth, Geocosmos (G). The enormous galaxies and other remote objects are mapped inside as microscopic objects, and the moon as by far the largest of the celestial objects, all of which revolve daily around the earth's axis. Straight rays of light are mapped as arcs of circles, so that all celestial phenomena appear to inside observers in G just as they do to outside observers in C. He next considers the hypothesis that, conversely, the actual universe is this finite G. Then there seems to be no way of testing this, except by drilling a hole right through the earth's centre. However, in C the origin of cosmic rays of super-high energies is very controversial, whereas in G it is unequivocal. The idea of G was first conceived qualitatively by Karl E. Neupert in 1900; this revival is somewhat different. The main appeal of G stems from the very grave difficulty of believing in the fantastic vastness of C, and the consequent reduction of the earth to an infinitesimal.
A geocosmos: mapping outer space into a hollow earth
International Nuclear Information System (INIS)
Abdelkader, M.A.
1983-01-01
The authors regards the earth's surface as a sphere and applies a purely mathematical mapping taking outer space in the Copernican universe (C) into a hollow earth, Geocosmos (G). The enormous galaxies and other remote objects are mapped inside as microscopic objects, and the moon as by far the largest of the celestial objects, all of which revolve daily around the earth's axis. Straight rays of light are mapped as arcs of circles, so that all celestial phenomena appear to inside observers in G just as they do to outside observers in C. He next considers the hypothesis that, conversely, the actual universe is this finite G. Then there seems to be no way of testing this, except by drilling a hole right through the earth's centre. However, in C the origin of cosmic rays of super-high energies is very controversial, whereas in G it is unequivocal. The idea of G was first conceived qualitatively by Karl E. Neupert in 1900; this revival is somewhat different. The main appeal of G stems from the very grave difficulty of believing in the fantastic vastness of C, and the consequent reduction of the earth to an infinitesimal. (Auth.)
Li, Fei; Li, Peng; Xu, Wenjian; Peng, Yuxing; Bo, Xiaochen; Wang, Shengqi
2010-01-15
The propagation of perturbations in protein concentration through a protein interaction network (PIN) can shed light on network dynamics and function. In order to facilitate this type of study, PerturbationAnalyzer, which is an open source plugin for Cytoscape, has been developed. PerturbationAnalyzer can be used in manual mode for simulating user-defined perturbations, as well as in batch mode for evaluating network robustness and identifying significant proteins that cause large propagation effects in the PINs when their concentrations are perturbed. Results from PerturbationAnalyzer can be represented in an intuitive and customizable way and can also be exported for further exploration. PerturbationAnalyzer has great potential in mining the design principles of protein networks, and may be a useful tool for identifying drug targets. PerturbationAnalyzer can be accessed from the Cytoscape web site http://www.cytoscape.org/plugins/index.php or http://biotech.bmi.ac.cn/PerturbationAnalyzer. Supplementary data are available at Bioinformatics online.
Accommodation of the spinal cat to a tripping perturbation
Directory of Open Access Journals (Sweden)
Hui eZhong
2012-05-01
Full Text Available Adult cats with a complete spinal cord transection at T12-T13 can relearn over a period of days-to-weeks how to generate full weight-bearing stepping on a treadmill or standing ability if trained specifically for that task. In the present study, we assessed short-term (msec-min adaptations by repetitively imposing a mechanical perturbation on the hindlimb of chronic spinal cats by placing a rod in the path of the leg during the swing phase to trigger a tripping response. The kinematics and EMG were recorded during control (10 steps, trip (1 to 60 steps with various patterns and then release (without any tripping stimulus, 10 to 20 steps sequences. Our data show that the activation patterns and kinematics of the hindlimb in the step cycle immediately following the initial trip (mechanosensory stimulation of the dorsal surface of the paw was modified in a way that increased the probability of avoiding the obstacle in the subsequent step. This indicates that the spinal sensorimotor circuitry reprogrammed the trajectory of the swing following a perturbation prior to the initiation of the swing phase of the subsequent step, in effect attempting to avoid the re-occurrence of the perturbation. The average height of the release steps was elevated compared to control regardless of the pattern and the length of the trip sequences. In addition, the average impact force on the tripping rod tended to be lower with repeated exposure to the tripping stimulus. EMG recordings suggest that the semitendinosus, a primary knee flexor, was a major contributor to the adaptive tripping response. These results demonstrate that the lumbosacral locomotor circuitry can modulate the activation patterns of the hindlimb motor pools within the time frame of single step in a manner that tends to minimize repeated perturbations. Furthermore, these adaptations remained evident for a number of steps after removal of the mechanosensory stimulation.
Wavefunction of the Universe and Chern-Simons perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Soo Chopin [Department of Physics, National Cheng Kung University Tainan 70101, Taiwan (China)
2002-03-21
The Chern-Simons exact solution of four-dimensional quantum gravity with nonvanishing cosmological constant is presented in metric variables as the partition function of Chern-Simons theory with nontrivial source. The perturbative expansion is given, and the wavefunction is computed to the lowest order of approximation for the Cauchy surface which is topologically a 3-sphere. The state is well-defined even at degenerate and vanishing values of the dreibein. Reality conditions for the Ashtekar variables are also taken into account, and remarkable features of the Chern-Simons state and their relevance to cosmology are pointed out.
HOW WELL DO WE KNOW THE ORBITS OF THE OUTER PLANETS?
International Nuclear Information System (INIS)
Page, Gary L.; Wallin, John F.; Dixon, David S.
2009-01-01
This paper deals with the problem of astrometric determination of the orbital elements of the outer planets, in particular by assessing the ability of astrometric observations to detect perturbations of the sort expected from the Pioneer effect or other small perturbations to gravity. We also show that while using simplified models of the dynamics can lead to some insights, one must be careful to not oversimplify the issues involved lest one be misled by the analysis onto false paths. Specifically, we show that the current ephemeris of Pluto does not preclude the existence of the Pioneer effect. We show that the orbit of Pluto is simply not well enough characterized at present to make such an assertion. A number of misunderstandings related to these topics have now propagated through the literature and have been used as a basis for drawing conclusions about the dynamics of the solar system. Thus, the objective of this paper is to address these issues. Finally, we offer some comments dealing with the complex topic of model selection and comparison.
Stepping stability: effects of sensory perturbation
Directory of Open Access Journals (Sweden)
Krebs David E
2005-05-01
Full Text Available Abstract Background Few tools exist for quantifying locomotor stability in balance impaired populations. The objective of this study was to develop and evaluate a technique for quantifying stability of stepping in healthy people and people with peripheral (vestibular hypofunction, VH and central (cerebellar pathology, CB balance dysfunction by means a sensory (auditory perturbation test. Methods Balance impaired and healthy subjects performed a repeated bench stepping task. The perturbation was applied by suddenly changing the cadence of the metronome (100 beat/min to 80 beat/min at a predetermined time (but unpredictable by the subject during the trial. Perturbation response was quantified by computing the Euclidian distance, expressed as a fractional error, between the anterior-posterior center of gravity attractor trajectory before and after the perturbation was applied. The error immediately after the perturbation (Emax, error after recovery (Emin and the recovery response (Edif were documented for each participant, and groups were compared with ANOVA. Results Both balance impaired groups exhibited significantly higher Emax (p = .019 and Emin (p = .028 fractional errors compared to the healthy (HE subjects, but there were no significant differences between CB and VH groups. Although response recovery was slower for CB and VH groups compared to the HE group, the difference was not significant (p = .051. Conclusion The findings suggest that individuals with balance impairment have reduced ability to stabilize locomotor patterns following perturbation, revealing the fragility of their impairment adaptations and compensations. These data suggest that auditory perturbations applied during a challenging stepping task may be useful for measuring rehabilitation outcomes.
Perturbations of ultralight vector field dark matter
Energy Technology Data Exchange (ETDEWEB)
Cembranos, J.A.R.; Maroto, A.L.; Jareño, S.J. Núñez [Departamento de Física Teórica I, Universidad Complutense de Madrid, E-28040 Madrid (Spain)
2017-02-13
We study the dynamics of cosmological perturbations in models of dark matter based on ultralight coherent vector fields. Very much as for scalar field dark matter, we find two different regimes in the evolution: for modes with k{sup 2}≪Hma, we have a particle-like behaviour indistinguishable from cold dark matter, whereas for modes with k{sup 2}≫Hma, we get a wave-like behaviour in which the sound speed is non-vanishing and of order c{sub s}{sup 2}≃k{sup 2}/m{sup 2}a{sup 2}. This implies that, also in these models, structure formation could be suppressed on small scales. However, unlike the scalar case, the fact that the background evolution contains a non-vanishing homogeneous vector field implies that, in general, the evolution of the three kinds of perturbations (scalar, vector and tensor) can no longer be decoupled at the linear level. More specifically, in the particle regime, the three types of perturbations are actually decoupled, whereas in the wave regime, the three vector field perturbations generate one scalar-tensor and two vector-tensor perturbations in the metric. Also in the wave regime, we find that a non-vanishing anisotropic stress is present in the perturbed energy-momentum tensor giving rise to a gravitational slip of order (Φ−Ψ)/Φ∼c{sub s}{sup 2}. Moreover in this regime the amplitude of the tensor to scalar ratio of the scalar-tensor modes is also h/Φ∼c{sub s}{sup 2}. This implies that small-scale density perturbations are necessarily associated to the presence of gravity waves in this model. We compare their spectrum with the sensitivity of present and future gravity waves detectors.
Acoustic anisotropic wavefields through perturbation theory
Alkhalifah, Tariq Ali
2013-09-01
Solving the anisotropic acoustic wave equation numerically using finite-difference methods introduces many problems and media restriction requirements, and it rarely contributes to the ability to resolve the anisotropy parameters. Among these restrictions are the inability to handle media with η<0 and the presence of shear-wave artifacts in the solution. Both limitations do not exist in the solution of the elliptical anisotropic acoustic wave equation. Using perturbation theory in developing the solution of the anisotropic acoustic wave equation allows direct access to the desired limitation-free solutions, that is, solutions perturbed from the elliptical anisotropic background medium. It also provides a platform for parameter estimation because of the ability to isolate the wavefield dependency on the perturbed anisotropy parameters. As a result, I derive partial differential equations that relate changes in the wavefield to perturbations in the anisotropy parameters. The solutions of the perturbation equations represented the coefficients of a Taylor-series-type expansion of the wavefield as a function of the perturbed parameter, which is in this case η or the tilt of the symmetry axis. The expansion with respect to the symmetry axis allows use of an acoustic transversely isotropic media with a vertical symmetry axis (VTI) kernel to estimate the background wavefield and the corresponding perturbation coefficients. The VTI extrapolation kernel is about one-fourth the cost of the transversely isotropic model with a tilt in the symmetry axis kernel. Thus, for a small symmetry axis tilt, the cost of migration using a first-order expansion can be reduced. The effectiveness of the approach was demonstrated on the Marmousi model.
Pressure Gradients in the Inner Surf and Outer Swash Zone
Kidwell, A.; Puleo, J. A.; Torres-Freyermuth, A.
2010-12-01
The swash zone is a highly dynamic region of the beach profile. Although there has been significant progression in understanding the complex hydrodynamics of the swash zone, an improvement in the understanding of the sediment transport mechanisms deserves further investigation. Prior studies have demonstrated that the existing formulations derived from the energetics-type formulation do not accurately and consistently predict sediment transport. Thus, measurements and numerical modeling can contribute in the improvement of the current predictive capability of sediment transport. A potential enhancement to nearshore sediment transport is the horizontal pressure gradient. However, measuring the dynamic pressure gradient in nearshore flows is a difficult task. For instance, standard pressure sensors are generally ill-suited for this type of measurement in shallow swash flows due to the obstructing size of the sensor and the potential for flow interference. With improved measurement apparati and techniques, it is possible to obtain measurements of the horizontal pressure gradient. Our current research includes laboratory and numerical model investigation of the horizontal pressure gradient in the inner surf and outer swash zone. An inexpensive differential pressure gauge is employed allowing for a pressure port on the order of 2 mm diameter. Four pressure sensor pairs are installed 1 cm above the bed with a cross-shore spacing of 8 cm. The sensors are deployed just outside of and at various locations within the outer swash zone to determine spatio-temporal pressure variations. The measurement of total pressure coupled with the corresponding free surface measurements from co-located capacitance wave gauges yields time series of the hydrostatic and dynamic pressure and pressure gradients. A VOF-type RANS model is employed in this investigation. Firstly, the numerical model is validated with swash measurements. Then, model simulations will be performed in order to
Quantitative kinetic analysis of blood vessels in the outer membranes of chronic subdural hematomas
International Nuclear Information System (INIS)
Mori, Kentaro; Adachi, Keiji; Cho, Kajin; Ishimaru, Sumio; Maeda, Minoru
1998-01-01
Dynamic biologic modeling was used to calculate the transfer rate constant for gadolinium-diethylenetriaminepenta-acetic acid (Gd-DTPA) and capillary permeability in the outer membrane of chronic subdural hematomas and effusions. Following intravenous Gd-DTPA injection, Gd concentrations in the subdural fluid and in timed arterial blood samples were measured by ion-coupled plasma emission spectrometry in 53 chronic subdural hematomas and 18 chronic subdural effusions. The capillary surface area in outer membrane was assessed morphometrically. Transfer rate constants for subdural hematomas and subdural effusions were 12.4±1.0 and 20.6±1.7 (x 10 -4 )min -1 , respectively. Capillary permeabilities for subdural hematomas and subdural effusions were 16±1.2 and 19±3.7 ml·min -1 (mm 2 /mm 3 ) -1 , respectively. The capillary surface areas for subdural hematomas and subdural effusions were 48±3 and 77±10 mm 2 /mm 3 , respectively. The high degree of infiltration of Gd into subdural effusions reflects the high capillary surface area in the outer membrane rather than greater permeability of individual capillaries. The value of transfer rate constant was correlated inversely with the duration of the chronic subdural fluid collection. Immature outer membrane has a high transfer rate constant which allows extravasation of plasma components into the subdural space, resulting in increasing volume of the subdural effusion. Delayed magnetic resonance imaging following Gd administration may be clinically useful for estimating the age of chronic subdural fluid accumulations. (author)
Simulations and experiments of the growth of the “tent” perturbation in NIF ignition implosions
Hammel, B. A.; Tommasini, R.; Clark, D. S.; Field, J.; Stadermann, M.; Weber, C.
2016-05-01
NIF capsules are supported in the hohlraum by two thin (∼15-110 nm) Formvar films (“tent”). Highly resolved HYDRA simulations indicate that a large (∼40% peak-average) areal density (ρR) perturbation develops on the capsule during acceleration as a consequence of this support geometry. This perturbation results in a jet of dense DT and, in some cases, CH that penetrates and cools the hot spot, significantly degrading the neutron yield (∼10-20% of 1D yield). We examine “low-foot” and “high-foot” pulse shapes, tent thicknesses, and geometries. Simulations indicate that thinner tents result in a smaller pR perturbation, however, the departure angle of the tent from the capsule surface is important, with steeper angles resulting in larger perturbations.
Effects of resonant magnetic perturbation on the triggering and the evolution of double-tearing mode
Wang, L.; Lin, W. B.; Wang, X. Q.
2018-02-01
The effects of resonant magnetic perturbation on the triggering and the evolution of the double-tearing mode are investigated by using nonlinear magnetohydrodynamics simulations in a slab geometry. It is found that the double-tearing mode can be destabilized by boundary magnetic perturbation. Moreover, the mode has three typical development stages before it reaches saturation: the linear stable stage, the linear-growth stage, and the exponential-growth stage. The onset and growth of the double-tearing mode significantly depend on the boundary magnetic perturbations, particularly in the early development stage of the mode. The influences of the magnetic perturbation amplitude on the mode for different separations of the two rational surfaces are also discussed.
Nodulation outer proteins: double-edged swords of symbiotic rhizobia.
Staehelin, Christian; Krishnan, Hari B
2015-09-15
Rhizobia are nitrogen-fixing bacteria that establish a nodule symbiosis with legumes. Nodule formation depends on signals and surface determinants produced by both symbiotic partners. Among them, rhizobial Nops (nodulation outer proteins) play a crucial symbiotic role in many strain-host combinations. Nops are defined as proteins secreted via a rhizobial T3SS (type III secretion system). Functional T3SSs have been characterized in many rhizobial strains. Nops have been identified using various genetic, biochemical, proteomic, genomic and experimental approaches. Certain Nops represent extracellular components of the T3SS, which are visible in electron micrographs as bacterial surface appendages called T3 (type III) pili. Other Nops are T3 effector proteins that can be translocated into plant cells. Rhizobial T3 effectors manipulate cellular processes in host cells to suppress plant defence responses against rhizobia and to promote symbiosis-related processes. Accordingly, mutant strains deficient in synthesis or secretion of T3 effectors show reduced symbiotic properties on certain host plants. On the other hand, direct or indirect recognition of T3 effectors by plant cells expressing specific R (resistance) proteins can result in effector triggered defence responses that negatively affect rhizobial infection. Hence Nops are double-edged swords that may promote establishment of symbiosis with one legume (symbiotic factors) and impair symbiotic processes when bacteria are inoculated on another legume species (asymbiotic factors). In the present review, we provide an overview of our current understanding of Nops. We summarize their symbiotic effects, their biochemical properties and their possible modes of action. Finally, we discuss future perspectives in the field of T3 effector research. © 2015 Authors; published by Portland Press Limited.
Prevention of an arms race in outer space
International Nuclear Information System (INIS)
Anon.
1990-01-01
The space age may be the to have begun in 1957, when for the first time a man-made object was lofted into orbit round the Earth. Since that date, the new problems of outer space have been discussed in the United Nations, particularly in the General Assembly, in the Committee on the Peaceful Uses of Outer Space and its subsidiary bodies, and in the Conference on Disarmament. The discussions have contributed to the conclusion of a number of international agreements concerning both military and peaceful aspects of the use of outer space. This paper reports that according to the 1967 Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, known as the outer space Treaty, outer space, including the moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means (article II), and the parties undertake not to place in orbit around the earth any objects carrying nuclear weapons or any other kinds of weapons of ass destruction, install such weapons on celestial bodies, or station such weapons in outer space in any other manner (article IV). Detailed norms for States' actions in this environment are included in the 1979 Agreement Governing the Activities of States on the Moon and other Celestial Bodies to ensure that the Moon and other celestial bodies within the solar system, other than Earth, are used exclusively for peaceful purposes
Application of linear and higher perturbation theory in reactor physics
International Nuclear Information System (INIS)
Woerner, D.
1978-01-01
For small perturbations in the material composition of a reactor according to the first approximation of perturbation theory the eigenvalue perturbation is proportional to the perturbation of the system. This assumption is true for the neutron flux not influenced by the perturbance. The two-dimensional code LINESTO developed for such problems in this paper on the basis of diffusion theory determines the relative change of the multiplication constant. For perturbations varying the neutron flux in the space of energy and position the eigenvalue perturbation is also influenced by this changed neutron flux. In such cases linear perturbation theory yields larger errors. Starting from the methods of calculus of variations there is additionally developed in this paper a perturbation method of calculation permitting in a quick and simple manner to assess the influence of flux perturbation on the eigenvalue perturbation. While the source of perturbations is evaluated in isotropic approximation of diffusion theory the associated inhomogeneous equation may be used to determine the flux perturbation by means of diffusion or transport theory. Possibilities of application and limitations of this method are studied in further systematic investigations on local perturbations. It is shown that with the integrated code system developed in this paper a number of local perturbations may be checked requiring little computing time. With it flux perturbations in first approximation and perturbations of the multiplication constant in second approximation can be evaluated. (orig./RW) [de
Legal Provisions Applicable to the Definition of Outer Space
Thorin, T.
2002-01-01
and decreeing the basic principle that no state can make claims to sovereignty or territory in space. This is followed by the Agreement of 11th September 1984 which governs the activities of states on the Moon and other celestial bodies. There are also three multilateral agreements which provide guiding principles in three specific areas: the Agreement on the Rescue and Return of Astronauts; the Convention on International Liability for Damage Caused by Space Objects; and, the Convention on Registration of Objects Launched into Outer Space. We shall then discuss other sources of law which also contribute towards defining the notion of space. These are essentially doctrinal positions which surface from the fundamental debate among legal experts divided between "functionalists" and "spacialists", which discussion is part of the general economic framework of international law, and considering naturally that Space law is an integral part of this framework. We shall also examine, as mentioned previously, the position taken by the various political and thus economic players in the international arena and we shall see that their somewhat diverging conceptions are often legitimised by very concrete concerns, far removed from theoretical debates, contributing to the development of international law. Finally, this will lead us to consider the pragmatic approach to such a problem, by discussing the various applications of legitimacy in demarcating space. So, we will among others discuss whether it is feasible to study a given territory without the permission of the country concerned; if "forbidden" orbits exist; in particular considering frequencies allocations and, of course, the simple right of flying and crossing, by shuttle designed vehicles both plane and rocket, over various states and their upper areas. In summary, the purpose of this paper is to determine when space law takes over from air law.
Outer membrane biogenesis in Helicobacter pylori: A deviation from the paradigm
Directory of Open Access Journals (Sweden)
George W. Liechti
2012-04-01
Full Text Available The bacterial pathogen Helicobacter pylori is capable of colonizing the gastric mucosa of the human stomach using a variety of factors associated with or secreted from its outer membrane (OM. Lipopolysaccharide (LPS and numerous outer membrane proteins have been shown to be involved in adhesion and immune stimulation/evasion. Many of these factors are essential for colonization and/or pathogenesis in a variety of animal models. Despite this wide array of potential targets present on the bacterial surface, the ability of H. pylori to vary its outer membrane profile limits the effectiveness of vaccines that use any single one of these components. However, it has become evident that the proteins comprising the complexes that transport the majority of these molecules to the OM are highly conserved and often essential. The field of membrane biogenesis has progressed remarkably in the last few years, and the possibility now exists for targeting the mechanisms by which β-barrel proteins, lipoproteins, and LPS are transported to the OM, resulting in loss of bacterial fitness and significant altering of membrane permeability. In this review, the OM transport machinery for LPS, lipoproteins, and outer membrane proteins are discussed. While the principal investigations of these transport mechanisms have been conducted in Escherichia coli and Neisseria meningitidis, here these systems will be presented in the genetic context of ε- proteobacteria. Bioinformatic analysis reveals that minimalist genomes, such as that of Helicobacter pylori, offer insight into the smallest number of components required for these essential pathways to function. Interestingly, in the majority of ε-proteobacteria, while the inner and outer membrane associated apparatus of LPS, lipoprotein, and OM protein transport pathways appear to all be intact, most of the components associated with the periplasmic compartment are either missing or are almost unrecognizable when compared to
Local perturbations perturb—exponentially–locally
International Nuclear Information System (INIS)
De Roeck, W.; Schütz, M.
2015-01-01
We elaborate on the principle that for gapped quantum spin systems with local interaction, “local perturbations [in the Hamiltonian] perturb locally [the groundstate].” This principle was established by Bachmann et al. [Commun. Math. Phys. 309, 835–871 (2012)], relying on the “spectral flow technique” or “quasi-adiabatic continuation” [M. B. Hastings, Phys. Rev. B 69, 104431 (2004)] to obtain locality estimates with sub-exponential decay in the distance to the spatial support of the perturbation. We use ideas of Hamza et al. [J. Math. Phys. 50, 095213 (2009)] to obtain similarly a transformation between gapped eigenvectors and their perturbations that is local with exponential decay. This allows to improve locality bounds on the effect of perturbations on the low lying states in certain gapped models with a unique “bulk ground state” or “topological quantum order.” We also give some estimate on the exponential decay of correlations in models with impurities where some relevant correlations decay faster than one would naively infer from the global gap of the system, as one also expects in disordered systems with a localized groundstate
Mode coupling of Schwarzschild perturbations: Ringdown frequencies
International Nuclear Information System (INIS)
Pazos, Enrique; Brizuela, David; Martin-Garcia, Jose M.; Tiglio, Manuel
2010-01-01
Within linearized perturbation theory, black holes decay to their final stationary state through the well-known spectrum of quasinormal modes. Here we numerically study whether nonlinearities change this picture. For that purpose we study the ringdown frequencies of gauge-invariant second-order gravitational perturbations induced by self-coupling of linearized perturbations of Schwarzschild black holes. We do so through high-accuracy simulations in the time domain of first and second-order Regge-Wheeler-Zerilli type equations, for a variety of initial data sets. We consider first-order even-parity (l=2, m=±2) perturbations and odd-parity (l=2, m=0) ones, and all the multipoles that they generate through self-coupling. For all of them and all the initial data sets considered we find that--in contrast to previous predictions in the literature--the numerical decay frequencies of second-order perturbations are the same ones of linearized theory, and we explain the observed behavior. This would indicate, in particular, that when modeling or searching for ringdown gravitational waves, appropriately including the standard quasinormal modes already takes into account nonlinear effects.
Supersymmetry restoration in superstring perturbation theory
International Nuclear Information System (INIS)
Sen, Ashoke
2015-01-01
Superstring perturbation theory based on the 1PI effective theory approach has been useful for addressing the problem of mass renormalization and vacuum shift. We derive Ward identities associated with space-time supersymmetry transformation in this approach. This leads to a proof of the equality of renormalized masses of bosons and fermions and identities relating fermionic amplitudes to bosonic amplitudes after taking into account the effect of mass renormalization. This also relates unbroken supersymmetry to a given order in perturbation theory to absence of tadpoles of massless scalars to higher order. The results are valid at the perturbative vacuum as well as in the shifted vacuum when the latter describes the correct ground state of the theory. We apply this to SO(32) heterotic string theory on Calabi-Yau 3-folds where a one loop Fayet-Iliopoulos term apparently breaks supersymmetry at one loop, but analysis of the low energy effective field theory indicates that there is a nearby vacuum where supersymmetry is restored. We explicitly prove that the perturbative amplitudes of this theory around the shifted vacuum indeed satisfy the Ward identities associated with unbroken supersymmetry. We also test the general arguments by explicitly verifying the equality of bosonic and fermionic masses at one loop order in the shifted vacuum, and the appearance of two loop dilaton tadpole in the perturbative vacuum where supersymmetry is expected to be broken.
Supersymmetry restoration in superstring perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Sen, Ashoke [Harish-Chandra Research Institute,Chhatnag Road, Jhusi, Allahabad 211019 (India)
2015-12-14
Superstring perturbation theory based on the 1PI effective theory approach has been useful for addressing the problem of mass renormalization and vacuum shift. We derive Ward identities associated with space-time supersymmetry transformation in this approach. This leads to a proof of the equality of renormalized masses of bosons and fermions and identities relating fermionic amplitudes to bosonic amplitudes after taking into account the effect of mass renormalization. This also relates unbroken supersymmetry to a given order in perturbation theory to absence of tadpoles of massless scalars to higher order. The results are valid at the perturbative vacuum as well as in the shifted vacuum when the latter describes the correct ground state of the theory. We apply this to SO(32) heterotic string theory on Calabi-Yau 3-folds where a one loop Fayet-Iliopoulos term apparently breaks supersymmetry at one loop, but analysis of the low energy effective field theory indicates that there is a nearby vacuum where supersymmetry is restored. We explicitly prove that the perturbative amplitudes of this theory around the shifted vacuum indeed satisfy the Ward identities associated with unbroken supersymmetry. We also test the general arguments by explicitly verifying the equality of bosonic and fermionic masses at one loop order in the shifted vacuum, and the appearance of two loop dilaton tadpole in the perturbative vacuum where supersymmetry is expected to be broken.
Structural Aspects of Bacterial Outer Membrane Protein Assembly.
Calmettes, Charles; Judd, Andrew; Moraes, Trevor F
2015-01-01
The outer membrane of Gram-negative bacteria is predominantly populated by β-Barrel proteins and lipid anchored proteins that serve a variety of biological functions. The proper folding and assembly of these proteins is essential for bacterial viability and often plays a critical role in virulence and pathogenesis. The β-barrel assembly machinery (Bam) complex is responsible for the proper assembly of β-barrels into the outer membrane of Gram-negative bacteria, whereas the localization of lipoproteins (Lol) system is required for proper targeting of lipoproteins to the outer membrane.
DEFF Research Database (Denmark)
Sadegh, Payman; Spall, J. C.
1998-01-01
simultaneous perturbation approximation to the gradient based on loss function measurements. SPSA is based on picking a simultaneous perturbation (random) vector in a Monte Carlo fashion as part of generating the approximation to the gradient. This paper derives the optimal distribution for the Monte Carlo...
Development of a perturbation code, PERT-K, for hexagonal core geometry
Energy Technology Data Exchange (ETDEWEB)
Kim, Taek Kyum; Kim, Sang Ji; Song, Hoon; Kim, Young Il; Kim, Young Jin [Korea Atomic Energy Research Institute, Taejon (Korea)
1999-01-01
A perturbation code for hexagonal core geometry has been developed based on Nodal Expansion Method. By using relevant output files of DIF3D code, it can calculate the reactivity changes caused by perturbation in composition or/and neutron cross section libraries. The accuracy of PERT-K code has been validated by calculating the reactivity changes due to fuel composition change, the sodium void coefficients, and the sample reactivity worths of BFS-73-1 critical experiments. In the case of 10% reduction in all fuel isotopics at a assembly located in the outer core, PERT-K computation agrees with the direct computation by DIF3D within 60 pcm. The sample reactivity worths of BFS-73-1 critical experiments are predicted with PERT-K code within the experimental error bounds. For 100% sodium void occurrence at the inner core, the maximum difference of reactivity changes between PERT-K and direct DIF3D computations is less than 40 pcm. On the other hand, the same sodium void condition at the outer core leads to a difference of reactivity change greater than 400 pcm. However, as sodium voiding becomes near zero value, the difference becomes less and rapidly falls within the acceptable bound, i.e. 40 pcm. (author). 11 refs., 9 figs., 6 tabs.
The use of paraffin wax in a new solar cooker with inner and outer reflectors
Directory of Open Access Journals (Sweden)
Arabacigil Bihter
2015-01-01
Full Text Available In this paper, the potential use and effectiveness of paraffin wax in a new solar cooker was experimentally investigated during daylight and late evening hours. For these experiments, a cooker having an inner reflecting surface was designed, constructed by filling paraffin wax and metal shavings. The side- and sub-surface temperatures of the paraffin wax in the cooker are measured in the summer months of June and July. The thermal efficiency of the cooker was tested on different conditions. The results show that the optimum angle of the outer reflector is 30°. Here, the peak temperature of the paraffin wax in the solar cooker was 83.4 °C. The average solar radiation reflected makes a contribution of 9.26% to the temperature of paraffin wax with the outer reflector. The solar cooker with the outer reflector angle of 30° receives also reflected radiation from the inner reflectors. Besides, the heating time is decreased to approximately 1 hour. The designed solar cooker can be effectively used with 30.3% daily thermal efficiency and paraffin wax due to the amount of energy stored.
The propagation of varied timescale perturbations in landscapes
Bingham, N.; Johnson, K. N.; Bookhagen, B.; Chadwick, O.
2016-12-01
The classic assumption of steady-state landscapes greatly simplifies models of earth-surface processes. Theoretically, steady-state denotes time independence, but in real landscapes steady-state requires a timescale over which to assume (or document) no change. In the past, poor spatiotemporal resolution of eroding landscapes necessitated that shorter timescale perturbations be ignored in favor of regional formulations of rock uplift = erosion, 105, 6 years. Now, novel techniques and technologies provide an opportunity to define local landscape response to various timescales of perturbations; thus, allowing us to consider multiple steady-states on adjacent watersheds or even along a single watershed. This study seeks to identify the physical propagation of varied timescale perturbations in landscapes in order to provide an updated geomorphic context for interpreting critical zone processes. At our study site - Santa Cruz Island (SCI), CA - perturbations include sea level and climate fluctuations over 105 years coupled with pulses of overgrazing and extreme storm events during the last 200 years. Comprehensive knickpoint location maps and dated marine and fill terraces tighten the spatiotemporal constraints on erosion for SCI. In addition, the island hosts a wide range of lithologies, allowing us to compare lithologic effects on landscape response to perturbations. Our study uses lidar point clouds and high resolution (0.25 and 1 m) digital elevation model analysis to segment landscapes by the degree of their response to perturbations. Landscape response is measured by increases in topographic roughness. We ascertain roughness by analyzing the changes in different terrain attributes on multiple spatial scales: catchment, sub-catchments and individual hillslopes. Terrain attributes utilized include slope, curvature, local relief, flowpath length and contributing catchment area. Statistical analysis of these properties indicates narrower ranges in values for regions
Microfluidic mixing through oscillatory transverse perturbations
Wu, J. W.; Xia, H. M.; Zhang, Y. Y.; Zhu, P.
2018-05-01
Fluid mixing in miniaturized fluidic devices is a challenging task. In this work, the mixing enhancement through oscillatory transverse perturbations coupling with divergent circular chambers is studied. To simplify the design, an autonomous microfluidic oscillator is used to produce the oscillatory flow. It is then applied to four side-channels that intersect with a central channel of constant flow. The mixing performance is tested at high fluid viscosities of up to 16 cP. Results show that the oscillatory flow can cause strong transverse perturbations which effectively enhance the mixing. The influence of a fluidic capacitor in the central channel is also examined, which at low viscosities can intensify the perturbations and further improve the mixing.
One dimensional systems with singular perturbations
International Nuclear Information System (INIS)
Alvarez, J J; Gadella, M; Nieto, L M; Glasser, L M; Lara, L P
2011-01-01
This paper discusses some one dimensional quantum models with singular perturbations. Eventually, a mass discontinuity is added at the points that support the singular perturbations. The simplest model includes an attractive singular potential with a mass jump both located at the origin. We study the form of the only bound state. Another model exhibits a hard core at the origin plus one or more repulsive deltas with mass jumps at the points supporting these deltas. We study the location and the multiplicity of these resonances for the case of one or two deltas and settle the basis for a generalization. Finally, we consider the harmonic oscillator and the infinite square well plus a singular potential at the origin. We see how the energy of bound states is affected by the singular perturbation.
Perturbations of higher-dimensional spacetimes
Energy Technology Data Exchange (ETDEWEB)
Durkee, Mark; Reall, Harvey S, E-mail: M.N.Durkee@damtp.cam.ac.uk, E-mail: H.S.Reall@damtp.cam.ac.uk [DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)
2011-02-07
We discuss linearized gravitational perturbations of higher-dimensional spacetimes. For algebraically special spacetimes (e.g. Myers-Perry black holes), we show that there exist local gauge invariant quantities linear in the metric perturbation. These are the higher-dimensional generalizations of the 4D Newman-Penrose scalars that (in an algebraically special vacuum spacetime) satisfy decoupled equations of motion. We show that decoupling occurs in more than four dimensions if, and only if, the spacetime admits a null geodesic congruence with vanishing expansion, rotation and shear. Decoupling of electromagnetic perturbations occurs under the same conditions. Although these conditions are not satisfied in black hole spacetimes, they are satisfied in the near-horizon geometry of an extreme black hole.
Perturbation theory for continuous stochastic equations
International Nuclear Information System (INIS)
Chechetkin, V.R.; Lutovinov, V.S.
1987-01-01
The various general perturbational schemes for continuous stochastic equations are considered. These schemes have many analogous features with the iterational solution of Schwinger equation for S-matrix. The following problems are discussed: continuous stochastic evolution equations for probability distribution functionals, evolution equations for equal time correlators, perturbation theory for Gaussian and Poissonian additive noise, perturbation theory for birth and death processes, stochastic properties of systems with multiplicative noise. The general results are illustrated by diffusion-controlled reactions, fluctuations in closed systems with chemical processes, propagation of waves in random media in parabolic equation approximation, and non-equilibrium phase transitions in systems with Poissonian breeding centers. The rate of irreversible reaction X + X → A (Smoluchowski process) is calculated with the use of general theory based on continuous stochastic equations for birth and death processes. The threshold criterion and range of fluctuational region for synergetic phase transition in system with Poissonian breeding centers are also considered. (author)
MCNP perturbation technique for criticality analysis
International Nuclear Information System (INIS)
McKinney, G.W.; Iverson, J.L.
1995-01-01
The differential operator perturbation technique has been incorporated into the Monte Carlo N-Particle transport code MCNP and will become a standard feature of future releases. This feature includes first and/or second order terms of the Taylor Series expansion for response perturbations related to cross-section data (i.e., density, composition, etc.). Criticality analyses can benefit from this technique in that predicted changes in the track-length tally estimator of K eff may be obtained for multiple perturbations in a single run. A key advantage of this method is that a precise estimate of a small change in response (i.e., < 1%) is easily obtained. This technique can also offer acceptable accuracy, to within a few percent, for up to 20-30% changes in a response
Gravitational perturbation theory and synchrotron radiation
Energy Technology Data Exchange (ETDEWEB)
Breuer, R A [Max-Planck-Institut fuer Physik und Astrophysik, Muenchen (F.R. Germany). Inst. fuer Astrophysik
1975-01-01
This article presents methods and results for a gravitational perturbation theory which treats massless fields as linearized perturbations of an arbitrary gravitational vacuum background spacetime. The formalism is outlined for perturbations of type (22) spacetimes. As an application, high-frequency radiation emitted by particles moving approximately on relativistic circular geodesic orbits is computed. More precisely, the test particle assumption is made; throughout it is therefore assumed that the reaction of the radiation on the particle motion is negligible. In particular, these orbits are studied in the gravitational field of a spherically symmetric (Schwarzschild-) black hole as well as of a rotating (Kerr-) black hole. In this model, the outgoing radiation is highly focussed and of much higher fequency than the orbital frequency, i.e. one is dealing with 'gravitational synchrotron radiation'.
Gribov ambiguity, perturbation theory, and confinement
International Nuclear Information System (INIS)
Greensite, J.P.
1978-01-01
The generating functional proposed for gauge theories by Bender, Eguchi, and Pagels (BEP) is shown to be equivalent to a truncated form of the functional integral, in which only one field configuration from each gauge-equivalent Gribov set contributes to the functional integration. The standard perturbation technique provides a method of realizing this truncation condition. It is shown that any gauge-covariant quantity (such as the quark N-point functions), evaluated by perturbating around a field configuration gauge-equivalent to A = 0, is related by a gauge transformation to the same quantity evaluated perturbatively around the trivial vacuum. It follows that, contrary to the conclusion of BEP, the existence of degeneracies in the Coulomb gauge-fixing condition (the Gribov ambiguity) is not directly related to the physics of confinement
Non-Perturbative Quantum Geometry III
Krefl, Daniel
2016-08-02
The Nekrasov-Shatashvili limit of the refined topological string on toric Calabi-Yau manifolds and the resulting quantum geometry is studied from a non-perturbative perspective. The quantum differential and thus the quantum periods exhibit Stockes phenomena over the combined string coupling and quantized Kaehler moduli space. We outline that the underlying formalism of exact quantization is generally applicable to points in moduli space featuring massless hypermultiplets, leading to non-perturbative band splitting. Our prime example is local P1xP1 near a conifold point in moduli space. In particular, we will present numerical evidence that in a Stockes chamber of interest the string based quantum geometry reproduces the non-perturbative corrections for the Nekrasov-Shatashvili limit of 4d supersymmetric SU(2) gauge theory at strong coupling found in the previous part of this series. A preliminary discussion of local P2 near the conifold point in moduli space is also provided.
Redshift-space distortions from vector perturbations
Bonvin, Camille; Durrer, Ruth; Khosravi, Nima; Kunz, Martin; Sawicki, Ignacy
2018-02-01
We compute a general expression for the contribution of vector perturbations to the redshift space distortion of galaxy surveys. We show that they contribute to the same multipoles of the correlation function as scalar perturbations and should thus in principle be taken into account in data analysis. We derive constraints for next-generation surveys on the amplitude of two sources of vector perturbations, namely non-linear clustering and topological defects. While topological defects leave a very small imprint on redshift space distortions, we show that the multipoles of the correlation function are sensitive to vorticity induced by non-linear clustering. Therefore future redshift surveys such as DESI or the SKA should be capable of measuring such vector modes, especially with the hexadecapole which appears to be the most sensitive to the presence of vorticity.
Operator Decomposition Framework for Perturbation Theory
Energy Technology Data Exchange (ETDEWEB)
Abdel-Khalik, Hany S.; Wang, Congjian; Bang, Young Suk [North Carolina State University, Raleigh (United States)
2012-05-15
This summary describes a new framework for perturbation theory intended to improve its performance, in terms of the associated computational cost and the complexity of implementation, for routine reactor calculations in support of design, analysis, and regulation. Since its first introduction in reactor analysis by Winger, perturbation theory has assumed an aura of sophistication with regard to its implementation and its capabilities. Only few reactor physicists, typically mathematically proficient, have contributed to its development, with the general body of the nuclear engineering community remaining unaware of its current status, capabilities, and challenges. Given its perceived sophistication and the small body of community users, the application of perturbation theory has been limited to investigatory analyses only. It is safe to say that the nuclear community is split into two groups, a small one which understands the theory and, and a much bigger group with the perceived notion that perturbation theory is nothing but a fancy mathematical approach that has very little use in practice. Over the past three years, research has demonstrated two goals. First, reduce the computational cost of perturbation theory in order to enable its use for routine reactor calculations. Second, expose some of the myth about perturbation theory and present it in a form that is simple and relatable in order to stimulate the interest of nuclear practitioners, especially those who are currently working on the development of next generation reactor design and analysis tools. The operator decomposition approach has its roots in linear algebra and can be easily understood by code developers, especially those involved in the design of iterative numerical solution strategies
Schroedinger operators with singular perturbation potentials
International Nuclear Information System (INIS)
Harrell, E.M. II.
1976-01-01
This is a perturbative analysis of the eigenvalues and eigenfunctions of Schroedinger operators of the form -Δ + A + lambda V, defined on the Hilbert space L 2 (R/sup n/). A is a potential function (a smooth, real multiplication operator), and V is a ''spikelike'' perturbation, i.e., a perturbative potential function which diverges at some finite point. Lambda is a small real or complex parameter. The emphasis is on one-dimensional problems, and in particular the typical example is the ''spiked harmonic oscillator'' Hamiltonian, -d 2 /dx 2 + x 2 + lambda x/sup -α/, where α is a positive constant. An earlier study by L. Detwiler and J. R. Klauder [Phys. Rev. D 11 (1975) 1436] indicated that the lowest-order corrections to the ground-state eigenvalue of the spiked harmonic oscillator with lambda greater than 0 were proportional to lambda ln lambda when α = 3, and to lambda/sup 1/(α-2) when α is greater than 3. These and analogous results for a large class of operators and arbitrary eigenvalues are proved. Explicit constants in a modified perturbation series with a complicated dependence on lambda are determined and exhibited. Higher-order corrections for real lambda and lowest-order corrections for complex lambda are also discussed. While the substance of the dissertation is mathematical, its main applications are to quantum physics. The immediate cause of interest in such problems was the use of their peculiar convergence properties by J. R. Klauder as models for the behavior of nonrenormalizable quantum field theories. However, the results of this study are likely to be of greater importance in chemical or nuclear physics, as positive spikelike perturbations represent repulsive core interactions for quantum mechanical particles. The modified perturbation series are a new calculation technique for this situation
Atmospheric Mining in the Outer Solar System: Outer Planet Orbital Transfer and Lander Analyses
Palaszewski, Bryan
2016-01-01
Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and deuterium can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and deuterium were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. While capturing 3He, large amounts of hydrogen and 4He are produced. Analyses of orbital transfer vehicles (OTVs), landers, and the issues with in-situ resource utilization (ISRU) mining factories are included. Preliminary observations are presented on near-optimal selections of moon base orbital locations, OTV power levels, and OTV and lander rendezvous points. For analyses of round trip OTV flights from Uranus to Miranda or Titania, a 10- Megawatt electric (MWe) OTV power level and a 200 metricton (MT) lander payload were selected based on a relative short OTV trip time and minimization of the number of lander flights. A similar optimum power level is suggested for OTVs flying from low orbit around Neptune to Thalassa or Triton. Several moon base sites at Uranus and Neptune and the OTV requirements to support them are also addressed.
Outer hair cell piezoelectricity: frequency response enhancement and resonance behavior.
Weitzel, Erik K; Tasker, Ron; Brownell, William E
2003-09-01
Stretching or compressing an outer hair cell alters its membrane potential and, conversely, changing the electrical potential alters its length. This bi-directional energy conversion takes place in the cell's lateral wall and resembles the direct and converse piezoelectric effects both qualitatively and quantitatively. A piezoelectric model of the lateral wall has been developed that is based on the electrical and material parameters of the lateral wall. An equivalent circuit for the outer hair cell that includes piezoelectricity shows a greater admittance at high frequencies than one containing only membrane resistance and capacitance. The model also predicts resonance at ultrasonic frequencies that is inversely proportional to cell length. These features suggest all mammals use outer hair cell piezoelectricity to support the high-frequency receptor potentials that drive electromotility. It is also possible that members of some mammalian orders use outer hair cell piezoelectric resonance in detecting species-specific vocalizations.
Inner and Outer Recursive Neural Networks for Chemoinformatics Applications.
Urban, Gregor; Subrahmanya, Niranjan; Baldi, Pierre
2018-02-26
Deep learning methods applied to problems in chemoinformatics often require the use of recursive neural networks to handle data with graphical structure and variable size. We present a useful classification of recursive neural network approaches into two classes, the inner and outer approach. The inner approach uses recursion inside the underlying graph, to essentially "crawl" the edges of the graph, while the outer approach uses recursion outside the underlying graph, to aggregate information over progressively longer distances in an orthogonal direction. We illustrate the inner and outer approaches on several examples. More importantly, we provide open-source implementations [available at www.github.com/Chemoinformatics/InnerOuterRNN and cdb.ics.uci.edu ] for both approaches in Tensorflow which can be used in combination with training data to produce efficient models for predicting the physical, chemical, and biological properties of small molecules.
Photoreceptor atrophy in acute zonal occult outer retinopathy
DEFF Research Database (Denmark)
Zibrandtsen, N.; Munch, I.C.; Klemp, K.
2006-01-01
Purpose: To assess retinal morphology in acute zonal occult outer retinopathy (AZOOR). Methods: Three patients with a normal ophthalmoscopic fundus appearance, a history of photopsia, and visual field loss compatible with AZOOR were examined using optical coherence tomography, automated perimetry...
The molecular mechanism of Zinc acquisition by the neisserial outer-membrane transporter ZnuD
Calmettes, Charles; Ing, Christopher; Buckwalter, Carolyn M.; El Bakkouri, Majida; Chieh-Lin Lai, Christine; Pogoutse, Anastassia; Gray-Owen, Scott D.; Pomès, Régis; Moraes, Trevor F.
2015-01-01
Invading bacteria from the Neisseriaceae, Acinetobacteriaceae, Bordetellaceae and Moraxellaceae families express the conserved outer-membrane zinc transporter zinc-uptake component D (ZnuD) to overcome nutritional restriction imposed by the host organism during infection. Here we demonstrate that ZnuD is required for efficient systemic infections by the causative agent of bacterial meningitis, Neisseria meningitidis, in a mouse model. We also combine X-ray crystallography and molecular dynamics simulations to gain insight into the mechanism of zinc recognition and transport across the bacterial outer-membrane by ZnuD. Because ZnuD is also considered a promising vaccine candidate against N. meningitidis, we use several ZnuD structural intermediates to map potential antigenic epitopes, and propose a mechanism by which ZnuD can maintain high sequence conservation yet avoid immune recognition by altering the conformation of surface-exposed loops. PMID:26282243
Lipopolysaccharide biogenesis and transport at the outer membrane of Gram-negative bacteria.
Sperandeo, Paola; Martorana, Alessandra M; Polissi, Alessandra
2017-11-01
The outer membrane (OM) of Gram-negative bacteria is an asymmetric lipid bilayer containing a unique glycolipid, lipopolysaccharide (LPS) in its outer leaflet. LPS molecules confer to the OM peculiar permeability barrier properties enabling Gram-negative bacteria to exclude many toxic compounds, including clinically useful antibiotics, and to survive harsh environments. Transport of LPS poses several problems to the cells due to the amphipatic nature of this molecule. In this review we summarize the current knowledge on the LPS transport machinery, discuss the challenges associated with this process and present the solutions that bacterial cells have evolved to address the problem of LPS transport and assembly at the cell surface. Finally, we discuss how knowledge on LPS biogenesis can be translated for the development of novel antimicrobial therapies. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop. Copyright © 2016. Published by Elsevier B.V.
Perturbation expansions generated by an approximate propagator
International Nuclear Information System (INIS)
Znojil, M.
1987-01-01
Starting from a knowledge of an approximate propagator R at some trial energy guess E 0 , a new perturbative prescription for p-plet of bound states and of their energies is proposed. It generalizes the Rayleigh-Schroedinger (RS) degenerate perturbation theory to the nondiagonal operators R (eliminates a RS need of their diagnolisation) and defines an approximate Hamiltonian T by mere inversion. The deviation V of T from the exact Hamiltonian H is assumed small only after a substraction of a further auxiliary Hartree-Fock-like separable ''selfconsistent'' potential U of rank p. The convergence is illustrated numerically on the anharmonic oscillator example
On algebraically special perturbations of black holes
International Nuclear Information System (INIS)
Chandrasekhar, S.
1984-01-01
Algebraically special perturbations of black holes excite gravitational waves that are either purely ingoing or purely outgoing. Solutions, appropriate to such perturbations of the Kerr, the Schwarzschild, and the Reissner-Nordstroem black-holes, are obtained in explicit forms by different methods. The different methods illustrate the remarkable inner relations among different facets of the mathematical theory. In the context of the Kerr black-hole they derive from the different ways in which the explicit value of the Starobinsky constant emerges, and in the context of the Schwarzschild and the Reissner-Nordstroem black-holes they derive from the potential barriers surrounding them belonging to a special class. (author)
Primordial perturbations with pre-inflationary bounce
Cai, Yong; Wang, Yu-Tong; Zhao, Jin-Yun; Piao, Yun-Song
2018-05-01
Based on the effective field theory (EFT) of nonsingular cosmologies, we build a stable model, without the ghost and gradient instabilities, of bounce-inflation (inflation is preceded by a cosmological bounce). We perform a full simulation for the evolution of scalar perturbation, and find that the perturbation spectrum has a large-scale suppression (as expected), which is consistent with the power deficit of the cosmic microwave background (CMB) TT-spectrum at low multipoles, but unexpectedly, it also shows itself one marked lower valley. The depth of valley is relevant with the physics around the bounce scale, which is model-dependent.
Perturbative evaluation of the Thermal Wilson Loop
International Nuclear Information System (INIS)
Gava, E.; Jengo, R.
1981-06-01
The Thermal Wilson Loop 0 sup(β) dtauA 0 (tau, x-vector)>, representing an order parameter for the gauge theory and expected to be zero in the confining phase, is perturbatively evaluated up to the O(g 4 ) included for an SU(N) pure Yang-Mills theory. This evaluation should be meaningful at high temperature, β → 0. Its behaviour is discussed and a possible need for non-perturbative instanton-like contributions is pointed out. (author)
A generalized perturbation program for CANDU reactor
Energy Technology Data Exchange (ETDEWEB)
Kim, Do Heon; Kim, Jong Kyung [Hanyang University, Seoul (Korea, Republic of); Choi, Hang Bok; Roh, Gyu Hong [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Yang, Won Sik [Chosun University, Kwangju (Korea, Republic of)
1999-12-31
A generalized perturbation program has been developed for the purpose of estimating zonal power variation of a CANDU reactor upon refueling operation. The forward and adjoint calculation modules of RFSP code were used to construct the generalized perturbation program. The numerical algorithm for the generalized adjoint flux calculation was verified by comparing the zone power estimates upon refueling with those of forward calculation. It was, however, noticed that the truncation error from the iteration process of the generalized adjoint flux is not negligible. 2 refs., 1 figs., 1 tab. (Author)
Pre-inflation physics and scalar perturbations
International Nuclear Information System (INIS)
Hirai, Shiro
2005-01-01
The effect of pre-inflation physics on the power spectrum of scalar perturbations is investigated. Considering various pre-inflation models with radiation-dominated or matter-dominated periods before inflation, the power spectra of curvature perturbations for large scales are calculated, and the spectral index and running spectral index are derived. It is shown that pre-inflation models in which the length of inflation is near 60 e-folds may reproduce some key properties implied by the Wilkinson microwave anisotropy probe data
Non-perturbative QCD and hadron physics
International Nuclear Information System (INIS)
Cobos-Martínez, J J
2016-01-01
A brief exposition of contemporary non-perturbative methods based on the Schwinger-Dyson (SDE) and Bethe-Salpeter equations (BSE) of Quantum Chromodynamics (QCD) and their application to hadron physics is given. These equations provide a non-perturbative continuum formulation of QCD and are a powerful and promising tool for the study of hadron physics. Results on some properties of hadrons based on this approach, with particular attention to the pion distribution amplitude, elastic, and transition electromagnetic form factors, and their comparison to experimental data are presented. (paper)
Perturbative approach to Markovian open quantum systems.
Li, Andy C Y; Petruccione, F; Koch, Jens
2014-05-08
The exact treatment of Markovian open quantum systems, when based on numerical diagonalization of the Liouville super-operator or averaging over quantum trajectories, is severely limited by Hilbert space size. Perturbation theory, standard in the investigation of closed quantum systems, has remained much less developed for open quantum systems where a direct application to the Lindblad master equation is desirable. We present such a perturbative treatment which will be useful for an analytical understanding of open quantum systems and for numerical calculation of system observables which would otherwise be impractical.
Free-boundary perturbed MHD equilibria
International Nuclear Information System (INIS)
Nührenberg, C
2012-01-01
The concept of perturbed ideal MHD equilibria [Boozer A H and Nuhrenberg C 2006 Phys. Plasmas 13 102501] is employed to study the influence of external error-fields and of small plasma-pressure changes on toroidal plasma equilibria. In tokamak and stellarator free-boundary calculations, benchmarks were successful of the perturbed-equilibrium version of the CAS3D stability code [Nührenberg C et al. 2009 Phys. Rev. Lett. 102 235001] with the ideal MHD equilibrium code NEMEC [Hirshman S P et al. 1986 Comput. Phys. Commun. 43 143].
Death to perturbative QCD in exclusive processes?
Energy Technology Data Exchange (ETDEWEB)
Eckardt, R.; Hansper, J.; Gari, M.F. [Institut fuer Theoretische Physik, Bochum (Germany)
1994-04-01
The authors discuss the question of whether perturbative QCD is applicable in calculations of exclusive processes at available momentum transfers. They show that the currently used method of determining hadronic quark distribution amplitudes from QCD sum rules yields wave functions which are completely undetermined because the polynomial expansion diverges. Because of the indeterminacy of the wave functions no statement can be made at present as to whether perturbative QCD is valid. The authors emphasize the necessity of a rigorous discussion of the subject and the importance of experimental data in the range of interest.
Perturbative and nonperturbative renormalization in lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Goeckeler, M. [Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Horsley, R. [University of Edinburgh (United Kingdom). School of Physics and Astronomy; Perlt, H. [Leipzig Univ. (DE). Institut fuer Theoretische Physik] (and others)
2010-03-15
We investigate the perturbative and nonperturbative renormalization of composite operators in lattice QCD restricting ourselves to operators that are bilinear in the quark fields (quark-antiquark operators). These include operators which are relevant to the calculation of moments of hadronic structure functions. The nonperturbative computations are based on Monte Carlo simulations with two flavors of clover fermions and utilize the Rome-Southampton method also known as the RI-MOM scheme. We compare the results of this approach with various estimates from lattice perturbation theory, in particular with recent two-loop calculations. (orig.)
A generalized perturbation program for CANDU reactor
Energy Technology Data Exchange (ETDEWEB)
Kim, Do Heon; Kim, Jong Kyung [Hanyang University, Seoul (Korea, Republic of); Choi, Hang Bok; Roh, Gyu Hong [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Yang, Won Sik [Chosun University, Kwangju (Korea, Republic of)
1998-12-31
A generalized perturbation program has been developed for the purpose of estimating zonal power variation of a CANDU reactor upon refueling operation. The forward and adjoint calculation modules of RFSP code were used to construct the generalized perturbation program. The numerical algorithm for the generalized adjoint flux calculation was verified by comparing the zone power estimates upon refueling with those of forward calculation. It was, however, noticed that the truncation error from the iteration process of the generalized adjoint flux is not negligible. 2 refs., 1 figs., 1 tab. (Author)
Scaling violations and perturbative quantum chromodynamics
International Nuclear Information System (INIS)
Barbieri, R.; d'Emilio, E.; Caneschi, L.; Curci, G.
1979-01-01
The authors try to understand the meaning of the recent data on scaling violations of the moments of the structure function F 3 measured in γ and anti γ deep inelastic scattering, and their relevance as a test of QCD. This is done by reducing to the minimum the theoretical machinery and prejudices and stressing the perturbative nature of the problem. This leads to a definition of the perturbation coupling constant αsub(s) (Q = 2.5 GeV) = 0.61 +- 0.06, in terms of which the corrective terms for all quantities computed so far turn out to be relatively small. (Auth.)
Non-Gaussianity from isocurvature perturbations
Energy Technology Data Exchange (ETDEWEB)
Kawasaki, Masahiro; Nakayama, Kazunori; Sekiguchi, Toyokazu; Suyama, Teruaki [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582 (Japan); Takahashi, Fuminobu, E-mail: kawasaki@icrr.u-tokyo.ac.jp, E-mail: nakayama@icrr.u-tokyo.ac.jp, E-mail: sekiguti@icrr.u-tokyo.ac.jp, E-mail: suyama@icrr.u-tokyo.ac.jp, E-mail: fuminobu.takahashi@ipmu.jp [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa 277-8568 (Japan)
2008-11-15
We develop a formalism for studying non-Gaussianity in both curvature and isocurvature perturbations. It is shown that non-Gaussianity in the isocurvature perturbation between dark matter and photons leaves distinct signatures in the cosmic microwave background temperature fluctuations, which may be confirmed in future experiments, or possibly even in the currently available observational data. As an explicit example, we consider the quantum chromodynamics axion and show that it can actually induce sizable non-Gaussianity for the inflationary scale, H{sub inf} = O(10{sup 9}-10{sup 11}) GeV.
A perturbative DFT approach for magnetic anisotropy
Energy Technology Data Exchange (ETDEWEB)
Khoo, Khoong Hong; Laskowski, Robert, E-mail: rolask@ihpc.a-star.edu.sg
2017-04-15
We develop a perturbative formalism for computing magnetocrystalline anisotropy within density functional theory and the magnetic force theorem. Instead of computing eigenvalues of the spin–orbit Hamiltonian for selected spin polarizations, as in the conventional “force theorem” approach, we show that the effect can be cast into a redefined form of the spin–orbit operator. This allows to separate the large eigenvalue shift due to spin-orbit interaction common for both polarizations from the much smaller magnetic anisotropy splitting. As a consequence the anisotropy splitting may by considered as a perturbation.
Outer Rail for Wall Plate Covering
DEFF Research Database (Denmark)
2013-01-01
including an abutment part, which extends inwards from the inner side of the retention web such as to form an abutment surface for the respective screw web when the latter is positioned to be retained in the retention device, and extends from the abutment part into a locking part, which extends at an angle...... to the abutment part and at a distance from the respective retention web. Each locking part comprising a first resilient locking pin adapted to lock a first screw web configuration and a second, separate resilient locking pin adapted to lock a second screw web configuration, the first and second screw web...
Gauge-invariant perturbations in a spatially flat anisotropic universe
International Nuclear Information System (INIS)
Den, Mitsue.
1986-12-01
The gauge-invariant perturbations in a spatially flat anisotropic universe with an arbitrary dimension (= N) are studied. In a previous paper the equations for the perturbations with a wave vector k a in one of the axial directions were derived and their solutions were shown. In this paper the perturbations with k a in arbitrary directions are treated. The remarkable properties are that all three types (scalar, vector, and tensor) of perturbations are generally coupled, so that a density perturbation can be produced also by vector or tensor perturbations. The formulation is quite general, but the behavior of the perturbations is discussed in a simple case such that N = 4 and k a is orthogonal to one of the axial directions. In this case, the perturbations are divided into two groups which are dynamically decoupled from each other. The asymptotic behavior of the perturbations in the group containing the density perturbation is discussed. (author)
Proposal for the LHCb outer tracker front-end electronics
Deppe, H; Feuerstack-Raible, M; Srowig, A; Stange, U; Hommels, B; Sluijk, T
2001-01-01
A market survey on available TDCs for reading out the LHCb Outer Tracker has left over only one TDC, which is not optimal for this purpose. Hence, a new readout architecture which is based on a TDC to be developed anew has been defined. This system fits optimal the requirements of the LHCb Outer Tracker and also should be much cheaper. The system and its main issues are described in this paper.
Developments for the outer tracking system of the LHCb experiment
Bachmann, S; Haas, T; Uwer, U; Walter, M; Wiedner, D
2004-01-01
The outer tracking system of the LHCb experiment is discussed. The outer tracking system (OT) is made of three stations and every station is made up of four detecting planes with a double layer of straw tubes. The straw tubes are mounted in detector module boxes made up of sandwich panels. The use of a counting gas with a high drift velocity is suggested to cope with high bunch crossing rate at the LHCb experiment. (Edited abstract) 3 Refs.
Inner and outer cylinders of the CMS vacuum tank.
Patrice Loïez
2002-01-01
The vacuum tank of the CMS magnet system consists of inner and outer stainless-steel cylinders and houses the superconducting coil. The inner cylinder contains all the barrel sub-detectors, which it supports via a system of horizontal rails. The cylinder is pictured here in the vertical position on a yellow platform mounted on the ferris-wheel support structure. This will allow it to be pivoted and inserted into the already installed outer cylinder, through which this photo was taken.
Star laws: legal controls on armed conflict in outer space
International Nuclear Information System (INIS)
Stephens, Dale
2016-01-01
An undeclared military space race is unfolding yet there is no clear understanding of how international las operates in the field of armed conflict in outer space. In conjunction with McGill University Law School, Montreal, Canada, a 'Manual on international law applicable to military uses of outer space' has been drafted. This article looks at types of space weapons, previous space treaties and discusses humanitarian law.
Development of CHF models for inner and outer RPV gaps in a meltdown severe accident
International Nuclear Information System (INIS)
Wang, J.; Tian, W.X.; Feng, K.; Yu, H.X.; Zhang, Y.P.; Su, G.H.; Qiu, S.Z.
2013-01-01
Highlights: • A CHF model was developed to predict the CHF in hemispherical narrow gap. • The computed result was validated by the test data of Park and Köhler. • An analytical CHF model was developed to predict the CHF on the outer surface of the lower head. • The predicted CHF was compared with the experimental data of ULPU-V. • Two CHF models developed for the inner and outer CHF predict the CHF well. - Abstract: During a severe accident, the core melt relocates in the lower head and a hemispherical narrow gap may appear between the crust and the lower head because of the different material expansion ratio. The existence of this gap is very important to the integrity of the lower head. Based on the counter current flow limitation (CCFL) between the vapor phase and the liquid phase, a CHF model was developed to predict the CHF in hemispherical narrow gap. The CHF model developed was validated by the test data of Park and Köhler. The effect of key parameters, including the system pressure, radius of melt, and gap size, on the CHF were investigated. And the TMI-2 accident was also calculated by using the CHF formula. Moreover, based on the interface separation model, an analytical CHF model was developed to predict the CHF on the outer surface of the lower head. The predicted CHF was compared with the experimental data of ULPU-V. It indicated that the CHF models developed for the inner and outer CHF could predict the CHF well
THE OUTER MEMBRANE OF PATHOGENIC REPRESENTATIVES OF THE LEPTOSPIRA GENIUS
Directory of Open Access Journals (Sweden)
A. N. Vaganova
2011-01-01
Full Text Available Abstract. Pathogenic leptospires can infect wide spectrum of hosts and they can survive in the environment long time. The outer membrane is the cellular component participated in interaction of microorganisms and environment. In present time several proteins located in the outer membrane of leptospires which are responsible for colonization of host organism, protection from influence of immune system of host, transport of substances in to the cell and other processes have been described. The outer membrane contains proteins and lipopolysaccharide molecules which have citotoxic effect. It was shown that regulation of protein composition of membranes depends on several factors of environment such as temperature, osmolarity, presence of certain substances in environment. Lipopolysaccharide and protein molecules of outer membranes have antigenic properties. These molecules can be used in practice as the components of vaccine against leptospiroses and diagnostic tools. Current review summarize information concerning structural organization of the outer membrane of leptospires, diversities of incoming parts of molecules and regulation of their synthesis. Moreover, perspectives of practical using of the outer membrane components in diagnostics and prevention of leptospiroses are presented.
Is the Magnetic Field in the Heliosheath Sector Region and in the Outer Heliosheath Laminar?
Opher, M.; Drake, J. F.; Swisdak, M. M.; Toth, G.
2010-12-01
All the current global models of the heliosphere are based on the assumption that the magnetic field in the outer heliosheath close to the heliopause is laminar. We argue that in the outer heliosheath the heliospheric magnetic field is not laminar but instead consists of nested magnetic islands. Recently, we proposed (Drake et al. 2009) that the annihilation of the ``sectored'' magnetic field within the heliosheath as it is compressed on its approach to the heliopause produces the anomalous cosmic rays (ACRs) and also energetic electrons. As a product of the annihilation of the sectored magnetic field, densly-packed magnetic islands are produced. These magnetic islands will be convected with the ambient flows as the sector boundary is carried to higher latitudes filling the outer heliosheath. We further argue that the magnetic islands will develop upstream (but still within the heliosheath) where collisionless reconnection is unfavorable -- large perturbations of the sector structure near the heliopause will cause compressions of the current sheet upstream, triggering reconnection. As a result, the magnetic field in the heliosheath sector region will be disordered well upstream of the heliopause. We present a 3D MHD simulation with unprecedent numerical resolution that captures the sector boundary. We show that due to the high pressure of the interstellar magnetic field the disordered sectored region fills a large portion of the northern part of the heliosphere with a smaller extension in the southern hemisphere. We test these ideas with observations of energetic electrons, which because of their high velocity are most sensitive to the structure of the magnetic field. We suggest that within our scenario we can explain two significant anomalies in the observations of energetic electrons in the outer heliosphere: the sudden decrease in the intensity of low energy electrons (0.02-1.5MeV) from the LECP instrument on Voyager 2 in 2008 (Decker 2010); and the dramatic
Reduction of some perturbed Keplerian problems
Energy Technology Data Exchange (ETDEWEB)
Inarrea, Manuel [Universidad de La Rioja, Area de Fisica, 26006 Logrono (Spain); Lanchares, Victor [Universidad de La Rioja, Departamento de Matematicas y Computacion, 26004 Logrono (Spain)] e-mail: vlancha@dmc.unirioja.es; Palacian, Jesus F. [Universidad Publica de Navarra, Departamento de Matematica e Informatica, 31006 Pamplona (Spain); Pascual, Ana I. [Universidad de La Rioja, Departamento de Matematicas y Computacion, 26004 Logrono (Spain); Salas, J. Pablo [Universidad de La Rioja, Area de Fisica, 26006 Logrono (Spain); Yanguas, Patricia [Universidad Publica de Navarra, Departamento de Matematica e Informatica, 31006 Pamplona (Spain)
2006-01-01
Perturbed Hamiltonian Keplerian systems enjoying some discrete and continuous symmetries can be brought to a one degree of freedom system containing the main qualitative features of the original one. This reduced system is defined in a compact set of the plane where the qualitative dynamics can be studied in a systematic way.
CIRCUMSTELLAR DEBRIS DISKS: DIAGNOSING THE UNSEEN PERTURBER
Energy Technology Data Exchange (ETDEWEB)
Nesvold, Erika R. [Department of Terrestrial Magnetism, Carnegie Institution for Science, 5241 Broad Branch Rd., Washington, DC 20015 (United States); Naoz, Smadar; Vican, Laura [Department of Physics and Astronomy, UCLA, 475 Portola Plaza, Los Angeles, CA 90095 (United States); Farr, Will M. [School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT (United Kingdom)
2016-07-20
The first indication of the presence of a circumstellar debris disk is usually the detection of excess infrared emission from the population of small dust grains orbiting the star. This dust is short-lived, requiring continual replenishment, and indicating that the disk must be excited by an unseen perturber. Previous theoretical studies have demonstrated that an eccentric planet orbiting interior to the disk will stir the larger bodies in the belt and produce dust via interparticle collisions. However, motivated by recent observations, we explore another possible mechanism for heating a debris disk: a stellar-mass perturber orbiting exterior to and inclined to the disk and exciting the disk particles’ eccentricities and inclinations via the Kozai–Lidov mechanism. We explore the consequences of an exterior perturber on the evolution of a debris disk using secular analysis and collisional N -body simulations. We demonstrate that a Kozai–Lidov excited disk can generate a dust disk via collisions and we compare the results of the Kozai–Lidov excited disk with a simulated disk perturbed by an interior eccentric planet. Finally, we propose two observational tests of a dust disk that can distinguish whether the dust was produced by an exterior brown dwarf or stellar companion or an interior eccentric planet.
Perturbative renormalization of QED via flow equations
International Nuclear Information System (INIS)
Keller, G.; Kopper, C.
1991-01-01
We prove the perturbative renormalizability of euclidean QED 4 with a small photon mass in the framework of effective lagrangians due to Wilson and Polchinski. In particular we show that the QED identities, which become violated by our momentum space regularization at intermediate stages, are restored in the renormalized theory. (orig.)
Perturbative renormalization of QED via flow equations
Energy Technology Data Exchange (ETDEWEB)
Keller, G. (Max-Planck-Inst. fuer Physik, Werner-Heisenberg-Inst., Munich (Germany)); Kopper, C. (Max-Planck-Inst. fuer Physik, Werner-Heisenberg-Inst., Munich (Germany) Inst. fuer Theoretische Physik, Univ. Goettingen (Germany))
1991-12-19
We prove the perturbative renormalizability of euclidean QED{sub 4} with a small photon mass in the framework of effective lagrangians due to Wilson and Polchinski. In particular we show that the QED identities, which become violated by our momentum space regularization at intermediate stages, are restored in the renormalized theory. (orig.).
Perturbation of operators and approximation of spectrum
Indian Academy of Sciences (India)
outside the bounds of essential spectrum of A(x) can be approximated ... some perturbed discrete Schrödinger operators treating them as block ...... particular, one may think of estimating the spectrum and spectral gaps of Schrödinger.
On the divergences of inflationary superhorizon perturbations
Energy Technology Data Exchange (ETDEWEB)
Enqvist, K; Nurmi, S [Physics Department, University of Helsinki, PO Box 64, Helsinki, FIN-00014 (Finland); Podolsky, D; Rigopoulos, G I, E-mail: kari.enqvist@helsinki.fi, E-mail: sami.nurmi@helsinki.fi, E-mail: dmitry.podolsky@helsinki.fi, E-mail: gerasimos.rigopoulos@helsinki.fi [Helsinki Institute of Physics, University of Helsinki, PO Box 64, Helsinki, FIN-00014 (Finland)
2008-04-15
We discuss the infrared divergences that appear to plague cosmological perturbation theory. We show that, within the stochastic framework, they are regulated by eternal inflation so that the theory predicts finite fluctuations. Using the {Delta}N formalism to one loop, we demonstrate that the infrared modes can be absorbed into additive constants and the coefficients of the diagrammatic expansion for the connected parts of two-and three-point functions of the curvature perturbation. As a result, the use of any infrared cutoff below the scale of eternal inflation is permitted, provided that the background fields are appropriately redefined. The natural choice for the infrared cutoff would, of course, be the present horizon; other choices manifest themselves in the running of the correlators. We also demonstrate that it is possible to define observables that are renormalization-group-invariant. As an example, we derive a non-perturbative, infrared finite and renormalization point-independent relation between the two-point correlators of the curvature perturbation for the case of the free single field.
Effective field theory of cosmological perturbations
International Nuclear Information System (INIS)
Piazza, Federico; Vernizzi, Filippo
2013-01-01
The effective field theory of cosmological perturbations stems from considering a cosmological background solution as a state displaying spontaneous breaking of time translations and (adiabatic) perturbations as the related Nambu–Goldstone modes. With this insight, one can systematically develop a theory for the cosmological perturbations during inflation and, with minor modifications, also describe in full generality the gravitational interactions of dark energy, which are relevant for late-time cosmology. The formalism displays a unique set of Lagrangian operators containing an increasing number of cosmological perturbations and derivatives. We give an introductory description of the unitary gauge formalism for theories with broken gauge symmetry—that allows us to write down the most general Lagrangian—and of the Stückelberg ‘trick’—that allows to recover gauge invariance and to make the scalar field explicit. We show how to apply this formalism to gravity and cosmology and we reproduce the detailed analysis of the action in the ADM variables. We also review some basic applications to inflation and dark energy. (paper)
Modification of the perturbative QCD towards confinement
International Nuclear Information System (INIS)
Arodz, H.
1981-01-01
Modification of the low momentum behaviour of the perturbative SU(2) gauge theory is proposed. The modification is closely related (although not equivalent) to a nonstandard choice of boundary condition for the Euclidean 2-point gluonic Green function. In the resulting theory already single graphs lead to the confining potential between heavy, static quarks, V(r) = ar 2 for r → infinity. (author)
Geometric perturbation theory and plasma physics
International Nuclear Information System (INIS)
Omohundro, S.M.
1985-01-01
Modern differential geometric techniques are used to unify the physical asymptotics underlying mechanics, wave theory, and statistical mechanics. The approach gives new insights into the structure of physical theories and is suited to the needs of modern large-scale computer simulation and symbol manipulation systems. A coordinate-free formulation of non-singular perturbation theory is given, from which a new Hamiltonian perturbation structure is derived and related to the unperturbed structure in five different ways. The theory of perturbations in the presence of symmetry is developed, and the method of averaging is related to reduction by a circle-group action. The pseudo-forces and magnetic Poisson bracket terms due to reduction are given a natural asymptotic interpretation. Similar terms due to changing reference frames are related to the method of variation of parameters, which is also given a Hamiltonian formulation. These methods are used to answer a long-standing question posed by Kruskal about nearly periodic systems. The answer leads to a new secular perturbation theory that contains no adhoc elements, which is then applied to gyromotion. Eikonal wave theory is given a Hamiltonian formulation that generalizes Whitham's Lagrangian approach. The evolution of wave action density on ray phase space is given a Hamiltonian structure using a Lie-Poisson bracket. The relationship between dissipative and Hamiltonian systems is discussed. A theory motivated by free electron lasers gives new restrictions on the change of area of projected parallelepipeds under canonical transformations
Many body perturbation calculations of photoionization
International Nuclear Information System (INIS)
Kelly, H.P.
1979-01-01
The application of many body perturbation theory to the calculation of atomic photoionization cross sections is reviewed. The choice of appropriate potential for the single-particle state is discussed and results are presented for several atoms including resonance structure. In addition to single photoionization, the process of double photoionization is considered and is found to be significant. (Auth.)
Quenched Chiral Perturbation Theory to one loop
Colangelo, G.; Pallante, E.
The divergences of the generating functional of quenched Chiral Perturbation theory (qCHPT) to one loop are computed in closed form. We show how the quenched chiral logarithms can be reabsorbed in the renormalization of the B0 parameter of the leading order Lagrangian. Finally, we do the chiral
Reduction of some perturbed Keplerian problems
International Nuclear Information System (INIS)
Inarrea, Manuel; Lanchares, Victor; Palacian, Jesus F.; Pascual, Ana I.; Salas, J. Pablo; Yanguas, Patricia
2006-01-01
Perturbed Hamiltonian Keplerian systems enjoying some discrete and continuous symmetries can be brought to a one degree of freedom system containing the main qualitative features of the original one. This reduced system is defined in a compact set of the plane where the qualitative dynamics can be studied in a systematic way
Perturbation theory for arbitrary coupling strength?
Mahapatra, Bimal P.; Pradhan, Noubihary
2018-03-01
We present a new formulation of perturbation theory for quantum systems, designated here as: “mean field perturbation theory” (MFPT), which is free from power-series-expansion in any physical parameter, including the coupling strength. Its application is thereby extended to deal with interactions of arbitrary strength and to compute system-properties having non-analytic dependence on the coupling, thus overcoming the primary limitations of the “standard formulation of perturbation theory” (SFPT). MFPT is defined by developing perturbation about a chosen input Hamiltonian, which is exactly solvable but which acquires the nonlinearity and the analytic structure (in the coupling strength) of the original interaction through a self-consistent, feedback mechanism. We demonstrate Borel-summability of MFPT for the case of the quartic- and sextic-anharmonic oscillators and the quartic double-well oscillator (QDWO) by obtaining uniformly accurate results for the ground state of the above systems for arbitrary physical values of the coupling strength. The results obtained for the QDWO may be of particular significance since “renormalon”-free, unambiguous results are achieved for its spectrum in contrast to the well-known failure of SFPT in this case.
Higher order corrections in perturbative quantum chromodynamics
Indian Academy of Sciences (India)
Since the discovery of asymptotic freedom in non-abelian gauge field theories, like quan- tum chromodynamics (QCD), many perturbative calculations have been performed to ..... The integral above appears in the partial integration with respect to the momentum. &½ of the expression below (see figure 2). ¼. Т&½. ґѕπµТ.
Stratospheric HTO perturbations 1980-1983
Mason, A. S.
1985-02-01
Three perturbations of the stratospheric tritiated water burden have occurred. An atmospheric nuclear detonation in 1980 injected about 2.1 MCi. The massive eruptions of the volcano El Chichon may have contributed to a doubling of the removal rate in 1982. An unusually large wintertime exchange with the upper stratosphere may have occurred between 1982 and 1983.
Perturbed soliton excitations in inhomogeneous DNA
International Nuclear Information System (INIS)
Daniel, M.; Vasumathi, V.
2005-05-01
We study nonlinear dynamics of inhomogeneous DNA double helical chain under dynamic plane-base rotator model by considering angular rotation of bases in a plane normal to the helical axis. The DNA dynamics in this case is found to be governed by a perturbed sine-Gordon equation when taking into account the interstrand hydrogen bonding energy and intrastrand inhomogeneous stacking energy and making an analogy with the Heisenberg model of the Hamiltonian for an inhomogeneous anisotropic spin ladder with ferromagnetic legs and antiferromagentic rung coupling. In the homogeneous limit the dynamics is governed by the kink-antikink soliton of the sine-Gordon equation which represents the formation of open state configuration in DNA double helix. The effect of inhomogeneity in stacking energy in the form of localized and periodic variations on the formation of open states in DNA is studied under perturbation. The perturbed soliton is obtained using a multiple scale soliton perturbation theory by solving the associated linear eigen value problem and constructing the complete set of eigen functions. The inhomogeneity in stacking energy is found to modulate the width and speed of the soliton depending on the nature of inhomogeneity. Also it introduces fluctuations in the form of train of pulses or periodic oscillation in the open state configuration (author)