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1

ELECTRON INJECTION INTO CYCLIC ACCELERATOR USING  

E-print Network

ELECTRON INJECTION INTO CYCLIC ACCELERATOR USING LASER WAKEFIELD ACCELERATION Ya. V. Getmanov, O. A acceleration #12;Storage ring with laser injection CYCLIC ACCELERATOR RF Electron injection The LWFA beam ­ accelerating light, 5 ­ accelerated electrons, 6 ­fast kicker - + accelerating laser pulse evaporatinglaser

2

Rf cavity primer for cyclic proton accelerators  

SciTech Connect

The purpose of this note is to describe the electrical and mechanical properites of particle accelerator rf cavities in a manner which will be useful to physics and engineering graduates entering the accelerator field. The discussion will be limited to proton (or antiproton) synchrotron accelerators or storage rings operating roughly in the range of 20 to 200 MHz. The very high gradient, fixed frequency UHF or microwave devices appropriate for electron machines and the somewhat lower frequency and broader bandwidth devices required for heavy ion accelerators are discussed extensively in other papers in this series. While it is common pratice to employ field calculation programs such as SUPERFISH, URMEL, or MAFIA as design aids in the development of rf cavities, we attempt here to elucidate various of the design parameters commonly dealt with in proton machines through the use of simple standing wave coaxial resonator expressions. In so doing, we treat only standing wave structures. Although low-impedance, moderately broad pass-band travelling wave accelerating systems are used in the CERN SPS, such systems are more commonly found in linacs, and they have not been used widely in large cyclic accelerators. Two appendices providing useful supporting material regarding relativistic particle dynamics and synchrotron motion in cyclic accelerators are added to supplement the text.

Griffin, J.E.

1988-04-01

3

The application package DeCA for calculating cyclic accelerators  

Microsoft Academic Search

The application package DeCA (Design Cyclic Accelerator) is offered to solve a set of problems which arise on designing electron storage rings. The package is based on the block principle. This makes it extremely flexible in designing storage rings and investigating beam dynamics in them. The package is intended for a user not familiar with programming languages, it is arranged

P. I. Gladkikh; A. Yu. Zeliasky; M. A. Strelkov

1993-01-01

4

Accelerated hygrothermal cyclical tests for carbon\\/epoxy laminates  

Microsoft Academic Search

The paper deals with the design of reasonable accelerated test conditions to assess polymer matrix composite durability when it is subjected to supersonic flight-cycles. The study is closely linked to novel application of carbon fibre polymer matrix composites in supersonic aircraft primary structures, leading to substantial weight saving and stiffness improvement. A supersonic flight can result in surface temperatures close

J. Jedidi; F. Jacquemin; A. Vautrin

2006-01-01

5

Exposure to stallion accelerates the onset of mares' cyclicity.  

PubMed

Horses (Equus caballus) belong to the group of seasonally polyestrous mammals. Estrous cycles typically start with increasing daylight length after winter, but mares can differ greatly in the timing of onset of regular estrus cycles. Here, we test whether spatial proximity to a stallion also plays a role. Twenty-two anestrous mares were either exposed to one of two stallions (without direct physical contact) or not exposed (controls) under experimental conditions during two consecutive springs (February to April). Ovarian activity was monitored via transrectal ultrasound and stallion's direct contact time with each mare was determined three times per week for one hour each. We found that mares exposed to a stallion ovulated earlier and more often during the observational period than mares that were not exposed to stallions. Neither stallion identity nor direct contact time, mare age, body condition, size of her largest follicle at the onset of the experiment, or parasite burden significantly affected the onset of cyclicity. In conclusion, the timing of estrous cycles and cycle frequency, i.e., crucial aspects of female reproductive strategy, strongly depend on how the mares perceive their social environment. Exposing mares to the proximity of a stallion can therefore be an alternative to, for example, light programs or elaborated hormonal therapies to start the breeding season earlier and increase the number of estrous cycles in horses. PMID:24815602

Wespi, B; Sieme, H; Wedekind, C; Burger, D

2014-07-15

6

The effect of flow acceleration on the cyclic variation of blood echogenicity under pulsatile flow.  

PubMed

It has been shown that the echogenicity of blood varies during a flow cycle under pulsatile flow both invitro and invivo. In general, the echogenicity of flowing whole blood increases during the early systole phase and then reduces to a minimum at late diastole. While it has been postulated that this cyclic variation is associated with the dynamics of erythrocyte aggregation, the mechanisms underlying this increasing echogenicity with flow velocity remain uncertain. The effect of flow acceleration has also been proposed as an explanation for this phenomenon, but no specific experiments have been conducted to test this hypothesis. In addition, the influence of ultrasonic attenuation on the cyclic variation of echogenicity requires clarification. In the present study, a Couette flow system was designed to simulate blood flowing with different acceleration patterns, and the flow velocity, attenuation, and backscattering coefficient were measured synchronously from 20%- and 40%-hematocrit porcine whole blood and erythrocyte suspensions using 35-MHz ultrasound transducers. The results showed ultrasonic attenuation exerted only minor effects on the echogenicity of blood under pulsatile flow conditions. Cyclic variations of echogenicity were clearly observed for whole blood with a hematocrit of 40%, but no variations were apparent for erythrocyte suspensions. The echogenicity did not appear to be enhanced when instantaneous acceleration was applied to flowing blood in any case. These findings show that flow acceleration does not promote erythrocyte aggregation, even when a higher peak velocity is applied to the blood. Comparison of the results obtained with different accelerations revealed that the cyclic variation in echogenicity observed during pulsatile blood flow may be jointly attributable to the effect of shear rate and the distribution of erythrocyte on aggregation. PMID:23384462

Huang, Chih-Chung; Liao, Chen-Chih; Lee, Po-Yang; Shih, Cho-Chiang

2013-04-01

7

Three dimensional numerical simulations of the effect of cyclic perturbations on liner acceleration  

Microsoft Academic Search

Cyclic perturbations are employed to generate aerodynamically stabilized self forging projectiles with star shaped tails. Typical shaped charges , or self forging projectiles have axial symmetry, thus a two dimensional code can be used to model the configuration. In the presence of most perturbations, the above axial symmetry is lost and a full three dimensional calculation has to be carried

G. Luttwak; M. Meyseless

1997-01-01

8

Numerical method for accelerated calculation of cyclic steady state of ModiCon-SMB-processes  

Microsoft Academic Search

The classical SMB-process including its ModiCon-variant is considered. The mathematical model corresponds to a set of coupled nonlinear partial differential equations completed by initial and boundary conditions. In order to predict the quality of the separation process accurately and efficiently discretization schemes are needed. We propose a new cascadic multilevel method for the fast calculation of the cyclic steady state

R. Lbke; Andreas Seidel-morgenstern; L. Tobiska

2007-01-01

9

Three dimensional numerical simulations of the effect of cyclic perturbations on liner acceleration.  

NASA Astrophysics Data System (ADS)

Cyclic perturbations are employed to generate aerodynamically stabilized self forging projectiles with star shaped tails. Typical shaped charges , or self forging projectiles have axial symmetry, thus a two dimensional code can be used to model the configuration. In the presence of most perturbations, the above axial symmetry is lost and a full three dimensional calculation has to be carried out. This kind of numerical simulations are quite challenging,as they have to resolve the thin liner , and to follow its motion over many times its width, while the liner material can undergo severe deformations. The number of zones required to achieve a good resolution can in some cases, surpass the available computer memory in our workstation. However, for a cyclic perturbation over the charge circumference, the computational domain can be limited to an appropiate angular slice of the charge, depending on the wave length of the perturbation. We present numerical simulations, carried out in the three dimensional code MSC/Dytran. We disscuss the implementation of the boundary conditions and the appropiate combination of of Euler and Lagrange techniques utilized. We compare the results of our calculations with published data on the formation of self forging projectiles with star shaped tails.

Luttwak, G.; Meyseless, M.

1997-07-01

10

Combinatorial biosynthesis of cyclic lipopeptide antibiotics: a model for synthetic biology to accelerate the evolution of secondary metabolite biosynthetic pathways.  

PubMed

Nonribosomal peptide synthetases (NRPSs) are giant multi-enzymes that carry out sequencial assembly line couplings of amino acids to generate linear or cyclic peptides. NRPSs are composed of repeating enzyme domains with modular organization to activate and couple specific amino acids in a particular order. From a synthetic biology perspective, they can be considered as peptide assembly machines composed of devices to couple fatty acids to l-amino acids, l-amino acids to l-amino acids, and d-amino acids to l-amino acids. The coupling devices are composed of specific parts that contain two or more enzyme domains that can be exchanged combinatorially to generate novel peptide assembly machines to produce novel peptides. The potent lipopeptide antibiotics daptomycin and A54145E have identical cyclic depsipeptide ring structures and stereochemistry but have divergent amino acid sequences. As their biosynthetic gene clusters are derived from an ancient ancestral lipopetide pathway, these lipopeptides provided an attractive model to develop combinatorial biosynthesis to generate antibiotics superior to daptomycin. These studies on combinatorial biosynthesis have helped generate guidelines for the successful assembly of NRPS parts and devices that can be used to generate novel lipopeptide structures and have established a basis for future synthetic biology studies to further develop combinatorial biosynthesis as a robust approach to natural product drug discovery. PMID:23654258

Baltz, Richard H

2014-10-17

11

Accelerators  

NSDL National Science Digital Library

What is the purpose of particle accelerators? On this web page, part of a particle physics tutorial, students read that accelerators solve two problems. The accelerators provide an increase in momentum to produce particles of small wavelength, and the fast-moving particles can create new particles when smashed together. A photograph of the inside of a particle accelerator is provided. Copyright 2005 Eisenhower National Clearinghouse

Group, Lawrence B.

2002-01-01

12

Cyclic oxidation of superalloys  

NASA Technical Reports Server (NTRS)

The development of mathematical/computer models of cyclic oxidation in high-temperature alloys is described. The acceleration of oxidation attack caused by the spalling of protective oxide scales is discussed. The COREST paralinear model based on empirical data, designed by Barrett and Pressler, is found to be of limited value. Basic research on the spalling process in different alloy systems is reviewed, and the phenomenon is characterized: occurring mainly within the oxide, it is caused by the different thermal expansion coefficients of oxide and metal and is a linear function of the total retained oxide. This information has been used in the development of the discrete oxide-spall model COSP and in its modification by addition of a diffusion-zone-profile model to predict the failure of components (Heckel and Nesbitt, unpublished). The COSP model is shown to produce good predictions of cyclic oxidation under a variety of conditions, using data from simple isothermic tests.

Lowell, C. E.; Smialek, J. L.; Barrett, C. A.

1983-01-01

13

Cyclic fatigue of ceramics  

Microsoft Academic Search

The fatigue behaviour of alumina, zirconia-toughened alumina (ZTA) and tetragonal zirconia (TZP) have been investigated using three different techniques. Direct push-pull testing has been used to generate both static and cyclic fatigue data. The results clearly show that all the materials studied are susceptible to both static and cyclic fatigue, and that the times to failure under cyclic loading are

F. Guiu; M. J. Reece; D. A. J. Vaughan

1991-01-01

14

Cyclic phosphonium ionic liquids.  

PubMed

Ionic liquids (ILs) incorporating cyclic phosphonium cations are a novel category of materials. We report here on the synthesis and characterization of four new cyclic phosphonium bis(trifluoromethylsulfonyl)amide ILs with aliphatic and aromatic pendant groups. In addition to the syntheses of these novel materials, we report on a comparison of their properties with their ammonium congeners. These exemplars are slightly less conductive and have slightly smaller self-diffusion coefficients than their cyclic ammonium congeners. PMID:24605146

Lall-Ramnarine, Sharon I; Mukhlall, Joshua A; Wishart, James F; Engel, Robert R; Romeo, Alicia R; Gohdo, Masao; Ramati, Sharon; Berman, Marc; Suarez, Sophia N

2014-01-01

15

Canine Cyclic Neutropenia  

PubMed Central

Two normal collie dogs were given 1,200 R total body irradiation followed by successful marrow grafts from their grey collie littermates with cyclic hematopoiesis. During observation periods of 97 and 41 days after grafting, both previously normal recipients showed regular cyclic fluctuations of their granulocyte and reticulocyte counts similar to those observed in their donors. These findings suggest that canine cyclic neutropenia is due to a defect in the marrow stem cell. PMID:4591036

Weiden, Paul L.; Robinett, Barbra; Graham, Theodore C.; Adamson, John; Storb, Rainer

1974-01-01

16

EXISTENTIALLY EQUIVALENT CYCLIC ULTRAMETRIC SPACES AND CYCLICALLY VALUED GROUPS.  

E-print Network

EXISTENTIALLY EQUIVALENT CYCLIC ULTRAMETRIC SPACES AND CYCLICALLY VALUED GROUPS. G. LELOUP Abstract we characterize existentially equivalence between cyclically ultrametric spaces, as well as existentially equivalence between generalized ultrametric spaces. We also describe classes of existentially

17

Affordable Cyclic Voltammetry  

ERIC Educational Resources Information Center

Cyclic voltammetry is an important component of the undergraduate chemical curriculum. Unfortunately, undergraduate students rarely have the opportunity to conduct experiments in cyclic voltammetry owing to the high cost of potentiostats, which are required to control these experiments. By using MicroLab data acquisition interfaces in conjunction

Stewart, Greg; Kuntzleman, Thomas S.; Amend, John R.; Collins, Michael J.

2009-01-01

18

Finite element forced vibration analysis of rotating cyclic structures  

NASA Technical Reports Server (NTRS)

A capability was added to the general purpose finite element program NASTRAN Level 17.7 to conduct forced vibration analysis of tuned cyclic structures rotating about their axes of symmetry. The effects of Coriolis and centripetal accelerations together with those due to linear acceleration of the axis of rotation were included. The theoretical development of this capability is presented.

Elchuri, V.; Smith, G. C. C.

1981-01-01

19

Bioactive cyclic dipeptides  

Microsoft Academic Search

Cyclic dipeptides are among the simplest peptide derivatives commonly found in nature. Most cyclic dipeptides found to date appear to have emerged as by-products of fermentation and food processing. However, many are nedogenous to members of animal and plant kingdoms; these include cyclo(Pro-Leu), cyclo(Pro-Val), cyclo(Pro-Phe), cyclo(Ala-Leu), cyclo(Pro-Tyr), cyclo(Pro-Trp), and cyclo(His-Pro). Although the five cyclic dipeptidescyclo(His-Pro), cyclo(Leu-Gly), cyclo(Tyr-Arg), cyclo(Asp-Pro), and cyclo(Pro-Phe)exhibit

Chandan Prasad

1995-01-01

20

Cyclic Vomiting Syndrome Association  

MedlinePLUS

... with CVS 2014 CVS Family Conference PPT: Managing Stress & Anxiety 2014 CVS Family Conference PPT: Endocannabinoid Greys Anatomy, Chandra Wilson CVS Media Links Relevant Organizations Research Anxiety Risk in Youth with Cyclic Vomiting ...

21

On modular cyclic codes  

Microsoft Academic Search

We study cyclic codes of arbitrary length N over the ring of integers moduloM. We first reduce this to the study of cyclic codes of length N=pkn (n prime to p) over the ring Zpe for prime divisors p of N. We then use the discrete Fourier transform to obtain an isomorphism ? between Zpe[X]\\/?XN-1? and a direct sum ?i?ISi

Steven T. Dougherty; Young Ho Park

2007-01-01

22

Flow in cyclic cosmology  

SciTech Connect

In this paper, we use a known duality between expanding and contracting cosmologies to construct a dual of the inflationary flow hierarchy applicable to contracting cosmologies such as ekpyrotic and cyclic models. We show that the inflationary flow equations are invariant under the duality and therefore apply equally well to inflation or to cyclic cosmology. We construct a self-consistent small-parameter approximation dual to the slow-roll approximation in inflation, and calculate the power spectrum of perturbations in this limit. We also recover the matter-dominated contracting solution of Wands, and the recently proposed adiabatic ekpyrosis solution.

Kinney, William H.; Dizgah, Azadeh Moradinezhad [Department of Physics, University at Buffalo, State University of New York, Buffalo, New York 14260-1500 (United States)

2010-10-15

23

Liquefaction Induced by Cyclic Loading.  

National Technical Information Service (NTIS)

The results of a study of liquefaction induced by cyclic loading are presented. Liquefaction and cyclic mobility are defined and compared with published definitions. The steady state of deformation is described and its relationship to liquefaction is disc...

G. Castro, J. L. Enos, J. W. France, S. J. Poulos

1982-01-01

24

Forced vibration analysis of rotating cyclic structures in NASTRAN  

NASA Technical Reports Server (NTRS)

A new capability was added to the general purpose finite element program NASTRAN Level 17.7 to conduct forced vibration analysis of tuned cyclic structures rotating about their axis of symmetry. The effects of Coriolis and centripetal accelerations together with those due to linear acceleration of the axis of rotation were included. The theoretical, user's, programmer's and demonstration manuals for this new capability are presented.

Elchuri, V.; Gallo, A. M.; Skalski, S. C.

1981-01-01

25

Turnaround in cyclic cosmology.  

PubMed

It is speculated how dark energy in a brane world can help reconcile an infinitely cyclic cosmology with the second law of thermodynamics. A cyclic model is described, in which dark energy with w<-1 equation of state leads to a turnaround at a time, extremely shortly before the would-be big rip, at which both volume and entropy of our Universe decrease by a gigantic factor, while very many independent similarly small contracting universes are spawned. The entropy of our model decreases almost to zero at turnaround but increases for the remainder of the cycle by a vanishingly small amount during contraction, empty of matter, then by a large factor during inflationary expansion. PMID:17359014

Baum, Lauris; Frampton, Paul H

2007-02-16

26

The Cyclic Barzilai-Borwein Method for Unconstrained Optimization  

E-print Network

arg min f(xk - gk). (1.3) It is well-known that steepest descent can be very slow when the Hessian, the iterates slowly approach the minimum in a zigzag fashion. On the other hand, it has been shown that if the exact steepest descent step is reused in a cyclic fashion, then the convergence is accelerated. Given

Schittkowski, Klaus

27

Cyclic torsion testing  

NASA Technical Reports Server (NTRS)

Torsional fatigue testing and data analysis procedures are described. Since there are no standards governing cyclic torsion testing that are generally accepted on a widespread basis by the technical community, the different approaches that dominate current experimental activity, and the ramifications of each are discussed. Particular attention is given to the theoretical and experimental difficulties that have paced refinement and general acceptance of test procedures. Finally, specific quantities and nomenclature modelled after analagous axial fatigue properties are suggested as an effective way to communicate torsional fatigue results until accepted standards are established.

Leese, G. E.

1984-01-01

28

Interacting New Agegraphic Dark Energy in a Cyclic Universe  

E-print Network

The main goal of this work is investigation of NADE in the cyclic universe scenario. Since, cyclic universe is explained by a phantom phase ($\\omega<-1$), it is shown when there is no interaction between matter and dark energy, ADE and NADE do not produce a phantom phase, then can not describe cyclic universe. Therefore, we study interacting models of ADE and NADE in the modified Friedmann equation. We find out that, in the high energy regime, which it is a necessary part of cyclic universe evolution, only NADE can describe this phantom phase era for cyclic universe. Considering deceleration parameter tells us that the universe has a deceleration phase after an acceleration phase, and NADE is able to produce a cyclic universe. Also it is found valuable to study generalized second law of thermodynamics. Since the loop quantum correction is taken account in high energy regime, it may not be suitable to use standard treatment of thermodynamics, so we turn our attention to the result of \\citep{29}, which the authors have studied thermodynamics in loop quantum gravity, and we show that which condition can satisfy generalized second law of thermodynamics.

Kh. Saaidi; H. Sheikhahmadi; A. H. Mohammadi

2011-12-31

29

Linear Accelerators  

NASA Astrophysics Data System (ADS)

In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.

Sidorin, Anatoly

2010-01-01

30

GAF Domains: Cyclic Nucleotides Come Full Circle  

NSDL National Science Digital Library

Cyclic nucleotides are ubiquitous signaling molecules that are present in life forms ranging from bacteria to yeast to humans. In higher eukaryotes, conserved molecular machinery processes signals through both cyclic adenosine monophosphate (AMP) and cyclic guanosine monophosphate (GMP). Hurley describes how one widespread cyclic nucleotide recognition module, the GAF (cyclic GMP, adenylyl cyclase, FhlA) domain, formerly thought to bind only cyclic GMP, has now been found to bind cyclic AMP as well. Recent structural analysis of a cyclic GMP-binding GAF domain shows how conserved elements among the cyclic nucleotide-binding subgroup of GAF domains recognize the common chemical moieties in the two compounds.

James H. Hurley (National Institutes of Health;Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases REV)

2003-01-07

31

Laser accelerators  

NASA Astrophysics Data System (ADS)

Laser accelerators are characterized, by their mode of operation, into media, far field, and near field accelerators. The first category, media accelerators, include the inverse Cherenkov effect accelerator, the plasma focus accelerator, and the beat wave accelerator (BWA). The second category, far field accelerators, include the two wave device and the inverse free electron accelerator (IFEI). The third category, near field accelerators, includes conventional linac scaled to small dimensions, dielectric sheets, small holes in dielectric cylinders, and gratings. An example from each category is given; namely: (1) the BWA; (2) the IFEL; and (3) the linac scaled to small dimensions and powered by a free electron laser (FEL). Grating accelerators are also discussed.

Sessler, A.

1983-04-01

32

Liquefaction induced by cyclic loading  

Microsoft Academic Search

The results of a study of liquefaction induced by cyclic loading are presented. Liquefaction and cyclic mobility are defined and compared with published definitions. The steady state of deformation is described and its relationship to liquefaction is discussed. The results of comprehensive laboratory triaxial testing programs on two sands are supplied. The test data demonstrate that, for a given soil,

G. Castro; J. L. Enos; J. W. France; S. J. Poulos

1982-01-01

33

Can Accelerators Accelerate Learning?  

SciTech Connect

The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ)[1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil, Caixa Postal 68528, 21941-972 (Brazil)

2009-03-10

34

Cyclic AMP in prokaryotes.  

PubMed Central

Cyclic AMP (cAMP) is found in a variety of prokaryotes including both eubacteria and archaebacteria. cAMP plays a role in regulating gene expression, not only for the classic inducible catabolic operons, but also for other categories. In the enteric coliforms, the effects of cAMP on gene expression are mediated through its interaction with and allosteric modification of a cAMP-binding protein (CRP). The CRP-cAMP complex subsequently binds specific DNA sequences and either activates or inhibits transcription depending upon the positioning of the complex relative to the promoter. Enteric coliforms have provided a model to explore the mechanisms involved in controlling adenylate cyclase activity, in regulating adenylate cyclase synthesis, and in performing detailed examinations of CRP-cAMP complex-regulated gene expression. This review summarizes recent work focused on elucidating the molecular mechanisms of CRP-cAMP complex-mediated processes. For other bacteria, less detail is known. cAMP has been implicated in regulating antibiotic production, phototrophic growth, and pathogenesis. A role for cAMP has been suggested in nitrogen fixation. Often the only data that support cAMP involvement in these processes includes cAMP measurement, detection of the enzymes involved in cAMP metabolism, or observed effects of high concentrations of the nucleotide on cell growth. PMID:1315922

Botsford, J L; Harman, J G

1992-01-01

35

Cyclic Vomiting Syndrome  

PubMed Central

Initially described in children, cyclic vomiting syndrome (CVS) is an idiopathic disorder that affects patients of all ages and is characterized by recurrent episodes of vomiting separated by symptom-free intervals or baseline health. Frequent misdiagnoses and delays in diagnosis often lead to years of recurrent vomiting. Similarities in the clinical features and symptoms of children and adults with CVS are often linked to migraines. Association with mitochondrial disorders and neuroendocrine dysfunction have been described in the pediatric CVS literature, whereas migraines, anxiety, and panic are common in adults with CVS. Various psychological, infectious, and physical stressors commonly precipitate episodes of CVS. Treatment is mostly empiric, with few controlled therapeutic studies conducted thus far. Associations with migraines have aided in developing pharmacologic treatment strategies for prophylaxis as well as abortive therapy during episodes, including the use of trip-tans. Most children outgrow CVS with time, though some children transition to migraine headaches or continue to have CVS as adults. Improved recognition of CVS in adults, along with the emergence of data in the use of anticonvulsants and antiemetics, may help further delineate pathophysiologic connections and therapeutic options for this debilitating disorder.

2009-01-01

36

Synthesis and properties of cyclic acetal biomaterials.  

PubMed

There is an increasing need to develop new biomaterials as tissue engineering scaffolds. Unfortunately, many of the materials that have been studied for these purposes are polyesters that hydrolytically degrade into acidic products, which may harm the surrounding tissue, and lead to accelerated degradation of the biomaterial. To overcome this disadvantage, a novel class of biomaterials based on a cyclic acetal unit has been created. Specifically, materials based upon the monomer 5-ethyl-5-(hydroxymethyl)-beta,beta-dimethyl-1,3-dioxane-2-ethanol diacrylate (EHD) is examined. This study investigates the effects of fabrication parameters, including initiator content, volume of diluent, and volume of accelerant, on several properties of EHD networks. Twelve different formulations were fabricated by varying the three parameters in a factorial design. The effects of the fabrication parameters on properties of the EHD networks were examined. Results show that the volume of accelerant most affected the EHD network gelation time, while the volume of diluent most affected the maximum reaction temperature, sol fraction, and degree of swelling. Cell viability on the EHD networks varied between (18 +/- 6)% and (57 +/- 10)% of the control at 4 h, and between (36 +/- 14)% and (140 +/- 50)% of the control at 8 h. These results indicate that it is possible to control the properties of the EHD networks by varying the fabrication parameters, and that EHD networks support a viable cell population. PMID:17177269

Moreau, Jennifer L; Kesselman, Dafna; Fisher, John P

2007-06-01

37

NASTRAN forced vibration analysis of rotating cyclic structures  

NASA Technical Reports Server (NTRS)

Theoretical aspects of a new capability developed and implemented in NASTRAN level 17.7 to analyze forced vibration of a cyclic structure rotating about its axis of symmetry are presented. Fans, propellers, and bladed shrouded discs of turbomachines are some examples of such structures. The capability includes the effects of Coriolis and centripetal accelerations on the rotating structure which can be loaded with: (1) directly applied loads moving with the structure and (2) inertial loas due to the translational acceleration of the axis of rotation (''base' acceleration). Steady-state sinusoidal or general periodic loads are specified to represent: (1) the physical loads on various segments of the complete structure, or (2) the circumferential harmonic components of the loads in (1). The cyclic symmetry feature of the rotating structure is used in deriving and solving the equations of forced motion. Consequently, only one of the cyclic sectors is modelled and analyzed using finite elements, yielding substantial savings in the analysis cost. Results, however, are obtained for the entire structure. A tuned twelve bladed disc example is used to demonstrate the various features of the capability.

Elchuri, V.; Smith, G. C. C.; Gallo, A. M.

1983-01-01

38

Cyclic fatigue-crack propagation in magnesia-partially-stabilized zirconia ceramics  

Microsoft Academic Search

The subcritical growth of fatigue cracks under (tension-tension) cyclic loading is demonstrated for ceramic materials, based on experiments using compact C(T) specimens of a MgO-partially-stabilized zirconia (PSZ). Under variable-amplitude cyclic loading, crack-growth rates show transient accelerations following low-high block overloads and transient retardations following high-low block overloads or single tensile overloads, again analogous to behavior commonly observed in ductile metals.

R. H. Dauskardt; R. O. Ritchie; D. B. Marshall

1990-01-01

39

Cyclic nucleotide metabolism in the sympathetic ganglion  

Microsoft Academic Search

1.The synaptic processes controlling cyclic nucleotide metabolism in the rat superior cervical ganglion were examined through electrical stimulation of preganglionic and postganglionic nerves.2.Both cyclic AMP and cyclic GMP were measured in each ganglion. Cyclic AMP was increased twofold by preganglionic but not postganglionic stimulation for 30 sec.3.Carbachol also increased cyclic AMP twofold. These elevations were calcium dependent and atropine sensitive,

Clark A. Briggs; Gary J. Whiting; Marjorie A. Ariano; Donald A. McAfee

1982-01-01

40

Liquefaction induced by cyclic loading  

NASA Astrophysics Data System (ADS)

The results of a study of liquefaction induced by cyclic loading are presented. Liquefaction and cyclic mobility are defined and compared with published definitions. The steady state of deformation is described and its relationship to liquefaction is discussed. The results of comprehensive laboratory triaxial testing programs on two sands are supplied. The test data demonstrate that, for a given soil, the steady state line is independent of stress history, and the magnitude of cyclic loading required to trigger liquefaction is a function of static shear stress and number of load cycles. The steady state lines for the two sands tested are compared to steady state lines for a variety of other sands. General trends are recorded for variation of steady state lines in rain size distribution and in grain angularity. A procedure for practical application of state state concepts to geotechnical engineering is recommended.

Castro, G.; Enos, J. L.; France, J. W.; Poulos, S. J.

1982-03-01

41

Android Acceleration  

NSDL National Science Digital Library

Students prepare for the associated activity in which they investigate acceleration by collecting acceleration vs. time data using the accelerometer of a sliding Android device. Based on the experimental set-up for the activity, students form hypotheses about the acceleration of the device. Students will investigate how the force on the device changes according to Newton's Second Law. Different types of acceleration, including average, instantaneous and constant acceleration, are introduced. Acceleration and force is described mathematically and in terms of processes and applications.

IMPART RET Program, College of Information Science & Technology,

42

Design of a cyclic multiverse  

NASA Astrophysics Data System (ADS)

Recently, it has been noticed that the amplification of the amplitude of curvature perturbation cycle by cycle can lead to a cyclic multiverse scenario, in which the number of universes increases cycle by cycle. However, this amplification will also inevitably induce either the ultimate end of corresponding cycle, or the resulting spectrum of perturbations inside corresponding universe is not scale invariant, which baffles the existence of observable universes. In this Letter, we propose a design of a cyclic multiverse, in which the observable universe can emerges naturally. The significance of a long period of dark energy before the turnaround of each cycle for this implementing is shown.

Piao, Yun-Song

2010-08-01

43

Color visualization of cyclic magnitudes  

NASA Astrophysics Data System (ADS)

We exploit the perceptual, circular ordering of the hues in a technique for the visualization of cyclic variables. The hue is thus meaningfully used for the indication of variables such as the azimuth and the units of the measurement of time. The cyclic (or circular) variables may be both of the continuous type or the discrete type; among the first there is azimuth and among the last you find the musical notes and the days of the week. A correspondence between the values of a cyclic variable and the chromatic hues, where the natural circular ordering of the variable is respected, is called a color code for the variable. We base such a choice of hues on an assignment of of the unique hues red, yellow, green and blue, or one of the 8 even permutations of this ordered list, to 4 cardinal values of the cyclic variable, suitably ordered; color codes based on only 3 cardinal points are also possible. Color codes, being intuitive, are easy to remember. A possible low accuracy when reading instruments that use this technique is compensated by fast, ludic and intuitive readings; also, the use of a referential frame makes readings precise. An achromatic version of the technique, that can be used by dichromatic people, is proposed.

Restrepo, Alfredo; Estupin, Viviana

2014-02-01

44

Cationic Polymerization of Cyclic Sulfides  

Microsoft Academic Search

The mechanism of the cationic polymerization of several thietanes and of propylene sulfide under the influence of triethyloxonium tetrafluoroborate in methylene chloride is described. The thietane polymerizations stop at limited conversions because of a termination reaction occurring between the reactive chain ends (cyclic sulfonium salts) and the sulfur atoms of the polymer chain. The maximum conversions obtained under identical conditions

E. J. Goethals; W. Drijvers; D. Van Ooteghem; A. M. Buyle

1973-01-01

45

Accelerated Learning (?)  

Microsoft Academic Search

We wish to pose accelerated learning as a challenge for intelligent systems technology. Research on intelligent tutoring systems has proved that accelerated learning is possible. The Sherlock tutor for electronics troubleshooting, for example, condensed four years of on-the-job training to approximately 25 hours, compressing the duration of the experience-feedback-learning cycle. But accelerated learning should refer to more than the hastening

Robert R. Hoffman; Paul J. Feltovich; Stephen M. Fiore; Gary Klein; David Ziebell

2009-01-01

46

An experimental approach ta prove the efficiency of a cyclic topology of a sensor network  

E-print Network

-successor and immediate successor geographical positions. Each sensor measures the acceleration nodes and updates itsAn experimental approach ta prove the efficiency of a cyclic topology of a sensor network trajectory of mobile sensor. We propose also a geograpbic routing algorithm to minimize the transmission time

Paris-Sud XI, Université de

47

Protein misfolding cyclic amplification of infectious prions  

PubMed Central

Prions are proteinaceous infectious agents responsible for the transmission of prion diseases. The lack of a procedure for cultivating prions in the laboratory has been a major limitation to the study of the unorthodox nature of this infectious agent and the molecular mechanism by which the normal prion protein (PrPC) is converted into the abnormal isoform (PrPSc). Protein misfolding cyclic amplification (PMCA ), described in detail in this protocol, is a simple, fast and efficient methodology to mimic prion replication in the test tube. PMCA involves incubating materials containing minute amounts of infectious prions with an excess of PrPC and boosting the conversion by cycles of sonication to fragment the converting units, thereby leading to accelerated prion replication. PMCA is able to detect the equivalent of a single molecule of infectious PrPSc and propagate prions that maintain high infectivity, strain properties and species specificity. A single PMCA assay takes little more than 3 d to replicate a large amount of prions, which could take years in an in vivo situation. Since its invention 10 years ago, PMCA has helped to answer fundamental questions about this intriguing infectious agent and has been broadly applied in research areas that include the food industry, blood bank safety and human and veterinary disease diagnosis. PMID:22743831

Morales, Rodrigo; Duran-Aniotz, Claudia; Diaz-Espinoza, Rodrigo; Camacho, Manuel V; Soto, Claudio

2014-01-01

48

Cyclic Game Dynamics Driven by Iterated Reasoning  

PubMed Central

Recent theories from complexity science argue that complex dynamics are ubiquitous in social and economic systems. These claims emerge from the analysis of individually simple agents whose collective behavior is surprisingly complicated. However, economists have argued that iterated reasoningwhat you think I think you thinkwill suppress complex dynamics by stabilizing or accelerating convergence to Nash equilibrium. We report stable and efficient periodic behavior in human groups playing the Mod Game, a multi-player game similar to Rock-Paper-Scissors. The game rewards subjects for thinking exactly one step ahead of others in their group. Groups that play this game exhibit cycles that are inconsistent with any fixed-point solution concept. These cycles are driven by a hopping behavior that is consistent with other accounts of iterated reasoning: agents are constrained to about two steps of iterated reasoning and learn an additional one-half step with each session. If higher-order reasoning can be complicit in complex emergent dynamics, then cyclic and chaotic patterns may be endogenous features of real-world social and economic systems. PMID:23441191

Frey, Seth; Goldstone, Robert L.

2013-01-01

49

High-Intensity Proton Accelerator  

SciTech Connect

Analysis is presented for an eight-cavity proton cyclotron accelerator that could have advantages as compared with other accelerators because of its potentially high acceleration gradient. The high gradient is possible since protons orbit in a sequence of TE111 rotating mode cavities of equally diminishing frequencies with path lengths during acceleration that greatly exceed the cavity lengths. As the cavities operate at sequential harmonics of a basic repetition frequency, phase synchronism can be maintained over a relatively wide injection phase window without undue beam emittance growth. It is shown that use of radial vanes can allow cavity designs with significantly smaller radii, as compared with simple cylindrical cavities. Preliminary beam transport studies show that acceptable extraction and focusing of a proton beam after cyclic motion in this accelerator should be possible. Progress is also reported on design and tests of a four-cavity electron counterpart accelerator for experiments to study effects on beam quality arising from variations injection phase window width. This device is powered by four 500-MW pulsed amplifiers at 1500, 1800, 2100, and 2400 MHz that provide phase synchronous outputs, since they are driven from a with harmonics derived from a phase-locked 300 MHz source.

Jay L. Hirshfield

2011-12-27

50

Accelerated Reader.  

ERIC Educational Resources Information Center

This paper provides an overview of Accelerated Reader, a system of computerized testing and record-keeping that supplements the regular classroom reading program. Accelerated Reader's primary goal is to increase literature-based reading practice. The program offers a computer-aided reading comprehension and management program intended to motivate

Education Commission of the States, Denver, CO.

51

On numerically pluricanonical cyclic coverings  

NASA Astrophysics Data System (ADS)

We investigate some properties of cyclic coverings f\\colon Y\\to X (where X is a complex surface of general type) branched along smooth curves B\\subset X that are numerically equivalent to a multiple of the canonical class of X. Our main results concern coverings of surfaces of general type with p_g=0 and Miyaoka-Yau surfaces. In particular, such coverings provide new examples of multi-component moduli spaces of surfaces with given Chern numbers and new examples of surfaces that are not deformation equivalent to their complex conjugates.

Kulikov, V. S.; Kharlamov, V. M.

2014-10-01

52

Cyclic voltammetry of supported BLMs  

NASA Astrophysics Data System (ADS)

The transfer of an electron across a bilayer lipid membrane (BLM) is one of the BLMs most exciting processes. A number of well known electron mediators have been investigated using the method of cyclic voltammetry on a Teflon coated platinum wire, the tip of which has been modified by a self-assembled bilayer lipid membrane (s-BLM). The electrical capacitance of the s-BLM system was measured as a function of frequency. The results are discussed in terms of electron transfer and redox reactions.

Murgasova, Renata; Sabo, Jan; Ottova, Angelica L.; Tien, H. T.

1996-06-01

53

Wakefield accelerators  

SciTech Connect

The search for new methods to accelerate particle beams to high energy using high gradients has resulted in a number of candidate schemes. One of these, wakefield acceleration, has been the subject of considerable R D in recent years. This effort has resulted in successful proof of principle experiments and in increased understanding of many of the practical aspects of the technique. Some wakefield basics plus the status of existing and proposed experimental work is discussed, along with speculations on the future of wake field acceleration. 10 refs., 6 figs.

Simpson, J.D.

1990-01-01

54

Acceleration switch  

DOEpatents

The disclosure relates to an improved integrating acceleration switch of the type having a mass suspended within a fluid filled chamber, with the motion of the mass initially opposed by a spring and subsequently not so opposed.

Abbin, Jr., Joseph P. (Albuquerque, NM); Devaney, Howard F. (Cedar Crest, NM); Hake, Lewis W. (Albuquerque, NM)

1982-08-17

55

Podcast: Acceleration  

NSDL National Science Digital Library

The Podcast: Acceleration is a segment of the Force and Motion Short Course. The podcast is 2 minutes 13 seconds in duration. Presented by science experts and NSTA staff, the NSTA Online Short Courses are professional development opportunities de

2009-07-06

56

Acceleration of heavy ions to very high energies  

SciTech Connect

The current interest of physicists in the collisions of heavy ions closes an interesting circle in the technology of accelerator building. The first cyclic accelerator, built by R. Wideroe, was a linear accelerator designed to accelerate potassium ions. Subsequent to Wideroe's achievement, much of the art of accelerator construction has been devoted to creating energetic beams of electrons and protons. Now we find ourselves returning to the heavy ions, and Wideroe's linear accelerator structure still plays an important role in many acceleration schemes. Fortunately, while the particle physics community has concentrated on the electron and proton machines, the nuclear physicists have kept alive the interest in heavy ions. Now a host of electrostatic machines, cyclotrons, and heavy ion linear accelerators provide beams of all species of ions at energies from about 100 MeV per nucleon for light isotopes to 10 MeV per nucleon for the heaviest isotopes in support of vigorous physics programs.

Barton, M.Q.

1982-01-01

57

Cell reorientation under cyclic stretching  

NASA Astrophysics Data System (ADS)

Mechanical cues from the extracellular microenvironment play a central role in regulating the structure, function and fate of living cells. Nevertheless, the precise nature of the mechanisms and processes underlying this crucial cellular mechanosensitivity remains a fundamental open problem. Here we provide a novel framework for addressing cellular sensitivity and response to external forces by experimentally and theoretically studying one of its most striking manifestationscell reorientation to a uniform angle in response to cyclic stretching of the underlying substrate. We first show that existing approaches are incompatible with our extensive measurements of cell reorientation. We then propose a fundamentally new theory that shows that dissipative relaxation of the cells passively-stored, two-dimensional, elastic energy to its minimum actively drives the reorientation process. Our theory is in excellent quantitative agreement with the complete temporal reorientation dynamics of individual cells measured over a wide range of experimental conditions, thus elucidating a basic aspect of mechanosensitivity.

Livne, Ariel; Bouchbinder, Eran; Geiger, Benjamin

2014-05-01

58

Nonlinear, nonbinary cyclic group codes  

NASA Technical Reports Server (NTRS)

New cyclic group codes of length 2(exp m) - 1 over (m - j)-bit symbols are introduced. These codes can be systematically encoded and decoded algebraically. The code rates are very close to Reed-Solomon (RS) codes and are much better than Bose-Chaudhuri-Hocquenghem (BCH) codes (a former alternative). The binary (m - j)-tuples are identified with a subgroup of the binary m-tuples which represents the field GF(2 exp m). Encoding is systematic and involves a two-stage procedure consisting of the usual linear feedback register (using the division or check polynomial) and a small table lookup. For low rates, a second shift-register encoding operation may be invoked. Decoding uses the RS error-correcting procedures for the m-tuple codes for m = 4, 5, and 6.

Solomon, G.

1992-01-01

59

Cyclic olefin copolymer plasma millireactors.  

PubMed

The novelty of this paper lies in the development of a multistep process for the manufacturing of plasma millireactors operating at atmospheric pressure. The fabrication process relies on the integration of metallic electrodes over a cyclic olefin copolymer chip by a combination of photopatterning and sputtering. The developed plasma millireactors were successfully tested by creating air discharges in the gas volume of the millichannel. A sputtered silica layer was deposited on the channel walls to provide a barrier between the plasma and the polymer in order to prevent the alteration of polymer surfaces during the plasma treatment. Interest in this process of employing plasma millireactor as a high reactive environment is demonstrated here by the degradation of a volatile organic compound (acetaldehyde) in ambient air. In this miniaturized device, we obtained a high acetaldehyde conversion (98%) for a specific input energy lower than 200 J L(-1). PMID:24957952

Schelcher, G; Guyon, C; Ognier, S; Cavadias, S; Martinez, E; Taniga, V; Malaquin, L; Tabeling, P; Tatoulian, M

2014-08-21

60

All-cis cyclic peptides.  

PubMed

Amide bonds -NH-CO- preferentially exist in trans conformations, the cis conformation being thermodynamically unfavored with respect to the trans by about 2 kcal/mol. Yet, the main reason most proteins or peptides cannot be made from cis-peptide plaques only lies in that connecting them into open chains appears to be sterically impracticable. It is possible, however, to build all-cis cyclic peptides in which all cis-plaques are efficiently locked. The present work examines, through quantum calculations, the structural and energetic issues associated with these peculiar arrangements. Systematic exploration at DFT-B3LYP level of the potential-energy surfaces for all-cis cyclopolyglycines cG(n)(c) (n = 2-10,15), and to a lesser extent, for all-cis cyclopolyalanines and all-cis cyclopolyphenylalanines confirms that all these structures are true minima. Optimal ring size occurs around eight peptide units, resulting in planar cG7(c), cG8(c), and cG9(c). In smaller systems, the ring strain is relieved through nonplanar cup-like distortions, particularly in cG6(c). From 10 peptide units and beyond, the ring framework distorts into a saddle-edge shape. These molecules disclose some molecular flexibility, as combinatorial tilting of the plaques may give sets of minima close in energy. Indexes based on isodesmic reactions are used to estimate the energy for joining all-cis or all-trans plaques into cyclic peptides. One of them, the mean plaque-junction energy (MPJE) suggests that within sensible sizes from six peptide units and beyond, all-cis plaque association is almost equally favorable as all-trans one. The frame of radiating cis-amide bonds can be considered as defining a new kind of peptidic material, endowed with specific self-assembling properties. PMID:16201809

Poteau, Romuald; Trinquier, Georges

2005-10-12

61

Cup Products in Hopf-Cyclic Cohomology.  

E-print Network

We construct cup products of two different kinds for Hopf-cyclic cohomology. When the Hopf algebra reduces to the ground field our first cup product reduces to Connes' cup product in ordinary cyclic cohomology. The second cup product generalizes Connes-Moscovici's characteristic map for actions of Hopf algebras on algebras.

Masoud Khalkhali (Mathematics Department; University of Western Ontario; London ON; Canada); Bahram Rangipour (Mathematics and Statistics Department; Univerity of Victoria; Victoria BC; Canada)

62

Cyclic Steam Stimulation With Formation Parting  

Microsoft Academic Search

Cyclic steam stimulation in highly viscous oil-bearing formations, such as those of Cold Lake, entails formation parting in many cases. This work presents a numeric treatment of the phenomena involved in this process, viz., fluid flow in cyclic steam stimulation, formation parting, fracture propagation, and closure. The latter part of the model involves the calculation of stresses and strains in

S. M. Farouq. Ali; J. Blunschi

1983-01-01

63

MAM testbed data analysis: cyclic averaging  

Microsoft Academic Search

The micro-arcsecond metrology testbed (MAM) provides a testing ground for SIM to perform optical path difference measurements with picometer (pm) precision. Because of imperfect optics and non-ideal laser sources it is inevitable that the cyclic bias is one of the major error sources for SIM. Many experiments have been conducted to diagnose and to characterize cyclic bias in the laser

Xiaopei Pan; Feng Zhao; Michael Shao

2003-01-01

64

Ants, Crickets and Frogs in Cyclic Pursuit  

Microsoft Academic Search

. We consider a deterministic continuous pursuit, in which n ants chase each otherin cyclic order and with preassigned, varying speeds. We also consider two discrete analogs, inwhich crickets or frogs are engaged in cyclic pursuit with constant and equal speeds. We examinethe possible evolutions of these pursuits as time goes to infinity: collision, limit points, equilibriumstates and periodic motion.IntroductionImagine

A. m. Bruckstein; N. Cohen; A. Efrat

1991-01-01

65

Periodic Hematopoiesis in Human Cyclic Neutropenia  

PubMed Central

Human cyclic neutropenia is characterized by severe depression of blood neutrophil levels approximately every 21 days. To investigate the mechanism of cyclic neutropenia four patients were studied with daily complete blood counts, serial bone marrow examinations, marrow reserve testing, serum muramidase determinations, DF22P granulocytokinetic studies, and, in one patient, in vivo [3H]TdR labeling. Periodogram analysis of the serial blood counts in the latter patient and visual inspection of multiple cycles in the others revealed periodic fluctuations in the levels of blood neutrophils, monocytes, lymphocytes, reticulocytes, and platelets. Rhythmic changes in the morphologic and radioisotopic studies as well as the marrow reserve tests and muramidase measurements were consonant with a mechanism of periodic failure of marrow production rather than peripheral destruction. Human cyclic neutropenia is analogous to cyclic neutropenia in the grey collie dog and may be viewed as the consequence of cyclic hematopoiesis. Images PMID:4750451

Guerry, D.; Dale, D. C.; Omine, M.; Perry, S.; Wolff, S. M.

1973-01-01

66

Accelerator-induced transients in Accelerator Driven Subcritical Reactors  

NASA Astrophysics Data System (ADS)

Achieving higher particles energies and beam powers have long been the main focus of research in accelerator technology. Since Accelerator Driven Subcritical Reactors (ADSRs) have become the subject of increasing interest, accelerator reliability and modes of operation have become important matters that require further research and development in order to accommodate the engineering and economic needs of ADSRs. This paper focuses on neutronic and thermo-mechanical analyses of accelerator-induced transients in an ADSR. Such transients fall into three main categories: beam interruptions (trips), pulsed-beam operation, and beam overpower. The concept of a multiple-target ADSR is shown to increase system reliability and to mitigate the negative effects of beam interruptions, such as thermal cyclic fatigue in the fuel cladding and the huge financial cost of total power loss. This work also demonstrates the effectiveness of the temperature-to-reactivity feedback mechanisms in ADSRs. A comparison of shutdown mechanisms using control rods and beam cut-off highlights the intrinsic safety features of ADSRs. It is evident that the presence of control rods is crucial in an industrial-scale ADSR. This paper also proposes a method to monitor core reactivity online using the repetitive pattern of beam current fluctuations in a pulsed-beam operation mode. Results were produced using PTS-ADS, a computer code developed specifically to study the dynamic neutronic and thermal responses to beam transients in subcritical reactor systems.

Ahmad, Ali; Lindley, Benjamin A.; Parks, Geoffrey T.

2012-12-01

67

Particle acceleration  

NASA Technical Reports Server (NTRS)

Data is compiled from Solar Maximum Mission and Hinothori satellites, particle detectors in several satellites, ground based instruments, and balloon flights in order to answer fundamental questions relating to: (1) the requirements for the coronal magnetic field structure in the vicinity of the energization source; (2) the height (above the photosphere) of the energization source; (3) the time of energization; (4) transistion between coronal heating and flares; (5) evidence for purely thermal, purely nonthermal and hybrid type flares; (6) the time characteristics of the energization source; (7) whether every flare accelerates protons; (8) the location of the interaction site of the ions and relativistic electrons; (9) the energy spectra for ions and relativistic electrons; (10) the relationship between particles at the Sun and interplanetary space; (11) evidence for more than one acceleration mechanism; (12) whether there is single mechanism that will accelerate particles to all energies and also heat the plasma; and (13) how fast the existing mechanisms accelerate electrons up to several MeV and ions to 1 GeV.

Vlahos, L.; Machado, M. E.; Ramaty, R.; Murphy, R. J.; Alissandrakis, C.; Bai, T.; Batchelor, D.; Benz, A. O.; Chupp, E.; Ellison, D.

1986-01-01

68

Plasma accelerator  

DOEpatents

There has been invented an apparatus for acceleration of a plasma having coaxially positioned, constant diameter, cylindrical electrodes which are modified to converge (for a positive polarity inner electrode and a negatively charged outer electrode) at the plasma output end of the annulus between the electrodes to achieve improved particle flux per unit of power.

Wang, Zhehui (Los Alamos, NM); Barnes, Cris W. (Santa Fe, NM)

2002-01-01

69

Cyclic electron transfer in plant leaf  

PubMed Central

The turnover of linear and cyclic electron flows has been determined in fragments of dark-adapted spinach leaf by measuring the kinetics of fluorescence yield and of the transmembrane electrical potential changes under saturating illumination. When Photosystem (PS) II is inhibited, a cyclic electron flow around PSI operates transiently at a rate close to the maximum turnover of photosynthesis. When PSII is active, the cyclic flow operates with a similar rate during the first seconds of illumination. The high efficiency of the cyclic pathway implies that the cyclic and the linear transfer chains are structurally isolated one from the other. We propose that the cyclic pathway operates within a supercomplex including one PSI, one cytochrome bf complex, one plastocyanin, and one ferredoxin. The cyclic process induces the synthesis of ATP needed for the activation of the BensonCalvin cycle. A fraction of PSI (?50%), not included in the supercomplexes, participates in the linear pathway. The illumination would induce a dissociation of the supercomplexes that progressively increases the fraction of PSI involved in the linear pathway. PMID:12119384

Joliot, Pierre; Joliot, Anne

2002-01-01

70

Cyclic shearing deformation behavior of saturated clays  

NASA Astrophysics Data System (ADS)

The apparatus for static and dynamic universal triaxial and torsional shear soil testing is employed to perform stress-controlled cyclic single-direction torsional shear tests and two-direction coupled shear tests under unconsolidated-undrained conditions. Through a series of tests on saturated clay, the effects of initial shear stress and stress reversal on the clays strain-stress behavior are examined, and the behavior of pore water pressure is studied. The experimental results indicate that the patterns of stress-strain relations are distinctly influenced by the initial shear stress in the cyclic single-direction shear tests. When the initial shear stress is large and no stress reversal occurs, the predominant deformation behavior is characterized by an accumulative effect. When the initial shear stress is zero and symmetrical cyclic stress occurs, the predominant deformation behavior is characterized by a cyclic effect. The pore water pressure fluctuates around the confining pressure with the increase of cycle number. It seems that the fluctuating amplitude increases with the increase of the cyclic stress. But a buildup of pore water pressure does not occur. The deformations of clay samples under the complex initial and the cyclic coupled stress conditions include the normal deviatoric deformation and horizontal shear deformation, the average deformation and cyclic deformation. A general strain failure criterion taking into account these deformations is recommended and is proved more stable and suitable compared to the strain failure criteria currently used.

Qi, Jianfeng; Luan, Maotian; Feng, Xiuli; Ma, Tailei; Nie, Ying

2007-10-01

71

Cyclic dominance in adaptive networks  

NASA Astrophysics Data System (ADS)

The Rock-Paper-Scissors (RPS) game is a paradigmatic model for cyclic dominance in biological systems. Here we consider this game in the social context of competition between opinions in a networked society. In our model, every agent has an opinion which is drawn from the three choices: rock, paper or scissors. In every timestep a link is selected randomly and the game is played between the nodes connected by the link. The loser either adopts the opinion of the winner or rewires the link. These rules define an adaptive network on which the agents' opinions coevolve with the network topology of social contacts. We show analytically and numerically that nonequilibrium phase transitions occur as a function of the rewiring strength. The transitions separate four distinct phases which differ in the observed dynamics of opinions and topology. In particular, there is one phase where the population settles to an arbitrary consensus opinion. We present a detailed analysis of the corresponding transitions revealing an apparently paradoxical behavior. The system approaches consensus states where they are unstable, whereas other dynamics prevail when the consensus states are stable.

Demirel, G.; Prizak, R.; Reddy, P. N.; Gross, T.

2011-12-01

72

Compact accelerator  

DOEpatents

A compact linear accelerator having at least one strip-shaped Blumlein module which guides a propagating wavefront between first and second ends and controls the output pulse at the second end. Each Blumlein module has first, second, and third planar conductor strips, with a first dielectric strip between the first and second conductor strips, and a second dielectric strip between the second and third conductor strips. Additionally, the compact linear accelerator includes a high voltage power supply connected to charge the second conductor strip to a high potential, and a switch for switching the high potential in the second conductor strip to at least one of the first and third conductor strips so as to initiate a propagating reverse polarity wavefront(s) in the corresponding dielectric strip(s).

Caporaso, George J. (Livermore, CA); Sampayan, Stephen E. (Manteca, CA); Kirbie, Hugh C. (Los Alamos, NM)

2007-02-06

73

BICEP's acceleration  

NASA Astrophysics Data System (ADS)

The recent Bicep2 [1] detection of, what is claimed to be primordial B-modes, opens up the possibility of constraining not only the energy scale of inflation but also the detailed acceleration history that occurred during inflation. In turn this can be used to determine the shape of the inflaton potential V(phi) for the first time if a single, scalar inflaton is assumed to be driving the acceleration. We carry out a Monte Carlo exploration of inflationary trajectories given the current data. Using this method we obtain a posterior distribution of possible acceleration profiles epsilon(N) as a function of e-fold N and derived posterior distributions of the primordial power spectrum P(k) and potential V(phi). We find that the Bicep2 result, in combination with Planck measurements of total intensity Cosmic Microwave Background (CMB) anisotropies, induces a significant feature in the scalar primordial spectrum at scales k~ 10-3 Mpc -1. This is in agreement with a previous detection of a suppression in the scalar power [2].

Contaldi, Carlo R.

2014-10-01

74

BICEP's acceleration  

E-print Network

The recent BICEP2 detection of, what is claimed to be primordial $B$-modes, opens up the possibility of constraining not only the energy scale of inflation but also the detailed acceleration history that occurred during inflation. In turn this can be used to determine the shape of the inflaton potential $V(\\phi)$ for the first time - if a single, scalar inflaton is assumed to be driving the acceleration. We carry out a Monte Carlo exploration of inflationary trajectories given the current data. Using this method we obtain a posterior distribution of possible acceleration profiles $\\epsilon(N)$ as a function of $e$-fold $N$ and derived posterior distributions of the primordial power spectrum $P(k)$ and potential $V(\\phi)$. We find that the BICEP2 result, in combination with Planck measurements of total intensity Cosmic Microwave Background (CMB) anisotropies, induces a significant feature in the scalar primordial spectrum at scales $k\\sim 10^{-3}$ Mpc$^{-1}$. This is in agreement with a previous detection of a suppression in the scalar power.

Carlo R. Contaldi

2014-07-24

75

BICEP's acceleration  

E-print Network

The recent BICEP2 detection of, what is claimed to be primordial $B$-modes, opens up the possibility of constraining not only the energy scale of inflation but also the detailed acceleration history that occurred during inflation. In turn this can be used to determine the shape of the inflaton potential $V(\\phi)$ for the first time - if a single, scalar inflaton is assumed to be driving the acceleration. We carry out a Monte Carlo exploration of inflationary trajectories given the current data. Using this method we obtain a posterior distribution of possible acceleration profiles $\\epsilon(N)$ as a function of $e$-fold $N$ and derived posterior distributions of the primordial power spectrum $P(k)$ and potential $V(\\phi)$. We find that the BICEP2 result, in combination with Planck measurements of total intensity Cosmic Microwave Background (CMB) anisotropies, induces a significant feature in the scalar primordial spectrum at scales $k\\sim 10^{-3}$ Mpc$^{-1}$. This is in agreement with a previous detection of a...

Contaldi, Carlo R

2014-01-01

76

Advanced concepts for acceleration  

SciTech Connect

Selected examples of advanced accelerator concepts are reviewed. Such plasma accelerators as plasma beat wave accelerator, plasma wake field accelerator, and plasma grating accelerator are discussed particularly as examples of concepts for accelerating relativistic electrons or positrons. Also covered are the pulsed electron-beam, pulsed laser accelerator, inverse Cherenkov accelerator, inverse free-electron laser, switched radial-line accelerators, and two-beam accelerator. Advanced concepts for ion acceleration discussed include the electron ring accelerator, excitation of waves on intense electron beams, and two-wave combinations. (LEW)

Keefe, D.

1986-07-01

77

Cyclic strength of stratified soil samples  

NASA Astrophysics Data System (ADS)

This paper presents the results of a laboratory testing program on the influence of stratification on cyclic strength of soil samples. Reference undrained cyclic triaxial tests were conducted on fine Ottawa sand samples and a much finer silica silt sample. Both samples were prepared by pluviation under water. Undrained cyclic triaxial tests conducted on stratified sand-silt samples revealed that layering induced a much lower cyclic resistance than that developed in either of the materials. Differential pore pressure generation in each soil unit suggest that water migration occurred from the sand layer to the silt layer and caused this strength reduction. The experimental data have significant implication for field conditions, especially for submarine slopes.

Konrad, J.-M.; Dubeau, S.

2003-04-01

78

Nanosecond Temperature Jump Relaxation Dynamics of Cyclic ?-Hairpin Peptides  

PubMed Central

The thermal unfolding of a series of 6-, 10-, and 14-mer cyclic ?-hairpin peptides was studied to gain insight into the mechanism of formation of this important secondary structure. The thermodynamics of the transition were characterized using temperature dependent Fourier transform infrared spectroscopy. Thermodynamic data were analyzed using a two-state model which indicates increasing cooperativity along the series. The relaxation kinetics of the peptides in response to a laser induced temperature jump were probed using time-resolved infrared spectroscopy. Single exponential relaxation kinetics were observed and fit with a two-state model. The folding rate determined for these cyclic peptides is accelerated by some two orders of magnitude over the rate of a linear peptide that forms a ?-hairpin. This observation supports the argument that the rate limiting step in the linear system is either stabilization of compact collapsed structures or rearrangement of collapsed structures over a barrier to achieve the native interstrand registry. Small activation energies for folding of these peptides obtained from an Arrhenius analysis of the rates imply a primarily entropic barrier, hence an organized transition state having specific stabilizing interactions. PMID:12770893

Maness, Shelia J.; Franzen, Stefan; Gibbs, Alan C.; Causgrove, Timothy P.; Dyer, R. Brian

2003-01-01

79

Cyclic dynamics of eastern Canadian ermine populations  

Microsoft Academic Search

Based on partial autocorrelation analysis, 20 ermine (Mustela erminea) populations in Manitoba, Ontario, and Quebec demonstrated cyclic dynamics characterized by a latitudinal gradient of decreasing first-order feedback and increasing negativity of second-order feedback. Most of these populations exhibited three cyclic peaks and a 10-year interval of noncyclic dynamics during the sampling period (1915-1940). Changes in ermine density probably reflected those

Donald R. Johnson; Bradley J. Swanson; Judith L. Eger

2000-01-01

80

Antimicrobial activity of selected cyclic dipeptides.  

PubMed

Cyclic dipeptides are products of rational drug design, which may exhibit both antimicrobial and antitumor properties. The aim of this study was to investigate both the antimicrobial effects of the cyclic dipeptides cyclo(L-phenylalanyl-L-prolyl), cyclo(L-tyrosyl-L-prolyl), cyclo(L-tryptophanyl-L-prolyl) and cyclo(L-tryptophanyl-L-tryptophanyl) and the effects of these cyclic dipeptides on the gastrointestinal epithelium in vitro. Furthermore, a relevant solvent for the possible pharmaceutical application of the products was sought concurrently. The antimicrobial effect of the cyclic dipeptides was assayed using the Kirby-Bauer disc diffusion assay against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilis, Streptococcus pneumoniae, Candida albicans, Aspergillus niger and Penicillium notatum. The effect of the cyclic dipeptides on the gastrointestinal epithelium was assessed by changes in alkaline phosphatase expression of HT-29 cells. Cyclo(Pro-Trp) and cyclo(Phe-Pro) show broad spectrum antibacterial properties and cyclo(Trp-Pro) and cyclo(Trp-Trp) show broad spectrum antifungal properties. The maturation of the gastrointestinal cells was enhanced by cyclo(Phe-Pro), cyclo(Tyr-Pro), cyclo(Trp-Trp) and cyclo(Trp-Pro). The activity of these cyclic dipeptides thus indicates potential application of these compounds as pharmacological agents. PMID:10563376

Graz, M; Hunt, A; Jamie, H; Grant, G; Milne, P

1999-10-01

81

Radial-velocity distribution of electrons moving in an accelerator  

Microsoft Academic Search

A relativistic radial-velocity-distribution function that is close to the actual distribution of electrons moving in cyclic accelerators and accumulators is obtained. Using this function, mean values of certain useful physical parameters are calculated, and a brief analysis of the results is presented.

A. A. Starobinets; B. V. Kholomai

1976-01-01

82

Accelerators and the Accelerator Community  

SciTech Connect

In this paper, standing back--looking from afar--and adopting a historical perspective, the field of accelerator science is examined. How it grew, what are the forces that made it what it is, where it is now, and what it is likely to be in the future are the subjects explored. Clearly, a great deal of personal opinion is invoked in this process.

Malamud, Ernest; Sessler, Andrew

2008-06-01

83

Discrete and cyclical movements: unified dynamics or separate control?  

Microsoft Academic Search

In the literature on motor control, three theoretical perspectives on the relation between discrete and cyclical movements may be discerned: (a) cyclical movements are concatenated discrete movements; (b) discrete movements are a limiting case of cyclical movements, and (c) discrete and cyclical movements are motor primitives that may be combined but are irreducible to each other. To examine the tenability

Anke M. van Mourik; Peter J. Beek

2004-01-01

84

Impact accelerations  

NASA Technical Reports Server (NTRS)

The degree to which impact acceleration is an important factor in space flight environments depends primarily upon the technology of capsule landing deceleration and the weight permissible for the associated hardware: parachutes or deceleration rockets, inflatable air bags, or other impact attenuation systems. The problem most specific to space medicine is the potential change of impact tolerance due to reduced bone mass and muscle strength caused by prolonged weightlessness and physical inactivity. Impact hazards, tolerance limits, and human impact tolerance related to space missions are described.

Vongierke, H. E.; Brinkley, J. W.

1975-01-01

85

Ring accelerators  

SciTech Connect

We present two-dimensional simulations in (r-z) and r-theta) cylinderical geometries of imploding-liner-driven accelerators of rings of charged particles. We address issues of azimuthal and longitudinal stability of the rings. We discuss self-trapping designs in which beam injection and extraction is aided by means of external cusp fields. Our simulations are done with the 2-1/2-D particle-in-cell plasma simulation code CLINER, which combines collisionless, electromagnetic PIC capabilities with a quasi-MHD finite element package.

Gisler, G.; Faehl, R.

1983-01-01

86

Electrothermal accelerators  

SciTech Connect

In electrothermal (ET) guns, the projectile acceleration is governed by gas dynamics as in explosively-driven guns. In a conventional gun, however, both the energy for heating and the material to be heated are contained in the solid propellant. Electrothermal launchers allow an external electric power supply to be used to provide the necessary energy; hence, lower atomic weight propellants may be used and heated to higher temperatures while maintaining a tailored acceleration profile. Important improvements in hypervelocity performance and barrel degradation can be obtained by controlling the electric discharges via power conditioning. Complex voltage and current waveforms are achieved using complex power conditioning systems, since the existing power supplies do not conform to ET gun requirements. This paper advances the concept of a single element power supply for ET guns, showing that compulsator-type machines with waveform flexibility (pulse shaping capability) can satisfy all the ET gun power supply and conditioning requirements while maintaining a high efficiency and los mass. Additionally, compulsators are suitable for repetitive-fire applications. Also described in the paper is a system of homopolar generators (HPGs) and inductors for laboratory applications.

Driga, M.D.; Ingram, M.W.; Weldon, W.F. (Texas Univ., Austin, TX (USA). Center for Electromechanics)

1989-01-01

87

Measuring Cyclic Error in Laser Heterodyne Interferometers  

NASA Technical Reports Server (NTRS)

An improved method and apparatus have been devised for measuring cyclic errors in the readouts of laser heterodyne interferometers that are configured and operated as displacement gauges. The cyclic errors arise as a consequence of mixing of spurious optical and electrical signals in beam launchers that are subsystems of such interferometers. The conventional approach to measurement of cyclic error involves phase measurements and yields values precise to within about 10 pm over air optical paths at laser wavelengths in the visible and near infrared. The present approach, which involves amplitude measurements instead of phase measurements, yields values precise to about .0.1 microns . about 100 times the precision of the conventional approach. In a displacement gauge of the type of interest here, the laser heterodyne interferometer is used to measure any change in distance along an optical axis between two corner-cube retroreflectors. One of the corner-cube retroreflectors is mounted on a piezoelectric transducer (see figure), which is used to introduce a low-frequency periodic displacement that can be measured by the gauges. The transducer is excited at a frequency of 9 Hz by a triangular waveform to generate a 9-Hz triangular-wave displacement having an amplitude of 25 microns. The displacement gives rise to both amplitude and phase modulation of the heterodyne signals in the gauges. The modulation includes cyclic error components, and the magnitude of the cyclic-error component of the phase modulation is what one needs to measure in order to determine the magnitude of the cyclic displacement error. The precision attainable in the conventional (phase measurement) approach to measuring cyclic error is limited because the phase measurements are af-

Ryan, Daniel; Abramovici, Alexander; Zhao, Feng; Dekens, Frank; An, Xin; Azizi, Alireza; Chapsky, Jacob; Halverson, Peter

2010-01-01

88

Analytical tools in accelerator physics  

SciTech Connect

This paper is a sub-set of my lectures presented in the Accelerator Physics course (USPAS, Santa Rosa, California, January 14-25, 2008). It is based on my notes I wrote during period from 1976 to 1979 in Novosibirsk. Only few copies (in Russian) were distributed to my colleagues in Novosibirsk Institute of Nuclear Physics. The goal of these notes is a complete description starting from the arbitrary reference orbit, explicit expressions for 4-potential and accelerator Hamiltonian and finishing with parameterization with action and angle variables. To a large degree follow logic developed in Theory of Cyclic Particle Accelerators by A.A.Kolmensky and A.N.Lebedev [Kolomensky], but going beyond the book in a number of directions. One of unusual feature is these notes use of matrix function and Sylvester formula for calculating matrices of arbitrary elements. Teaching the USPAS course motivated me to translate significant part of my notes into the English. I also included some introductory materials following Classical Theory of Fields by L.D. Landau and E.M. Liftsitz [Landau]. A large number of short notes covering various techniques are placed in the Appendices.

Litvinenko, V.N.

2010-09-01

89

Accelerating deactivation  

SciTech Connect

In recent years, the focus of the U.S. Department of Energy (DOE) complex has shifted from defense production to facility stabilization, decommissioning, and environmental restoration. This shift from production to cleanup requires a parallel shift from operations-focused management to project-focused management for an efficient facility deactivation. In the operation-focused management organization, activities are planned and executed based on production goals and are typically repetitive and cyclic. In the project-focused management environment, activities are based on a defined scope/end objective, start date, and completion date. Since the workforce used to perform production operations is also usually relied onto perform facility deactivation, it is important to shift from an operations management approach to a project management approach. It is best if the transition is accomplished quickly so the project can move forward and workers don't spend a lot of energy anticipating change. Therefore, it is essential that managers, planners, and other workers understand the key elements associated with planning a deactivation project. This paper describes a planning approach that has been used successfully to plan deactivation projects consistent with the requirements provided in DOE Order 430.1A Life Cycle Asset Management and the companion Deactivation Implementation Guide, G430. 1A-3, while exceeding schedule expectations and reducing costs. Although the planning of a deactivation project closely mirrors the classic project planning for construction projects, there are unique variations associated with facility deactivation. The key elements of planning a deactivation project are discussed relative to scope, schedule, and cost. Management tools such as project metrics and histograms are discussed as desired outputs from the planning process. In addition, lessons learned from planning deactivation projects across the DOE complex are discussed relative to making the transition from operations management to project management and the implications for deactivation project planning.

FISHBACK, K.M.

1999-02-01

90

CyclicRainbow A Multivariate Signature Scheme with a Partially Cyclic Public Key based on Rainbow  

E-print Network

CyclicRainbow ­ A Multivariate Signature Scheme with a Partially Cyclic Public Key based on Rainbow key size of the UOV scheme by a large factor. In this paper we extend this idea to the Rainbow of the public key by up to 62 %. Keywords: Multivariate Cryptography, Rainbow Signature Scheme, keysize

91

CyclicRainbow -A Multivariate Signature Scheme with a Partially Cyclic Public Key based on Rainbow  

E-print Network

CyclicRainbow - A Multivariate Signature Scheme with a Partially Cyclic Public Key based on Rainbow key size of the UOV scheme by a large factor. In this paper we extend this idea to the Rainbow of the public key by up to 62 %. Keywords: Multivariate Cryptography, Rainbow Signature Scheme, keysize

92

Accelerator system and method of accelerating particles  

NASA Technical Reports Server (NTRS)

An accelerator system and method that utilize dust as the primary mass flux for generating thrust are provided. The accelerator system can include an accelerator capable of operating in a self-neutralizing mode and having a discharge chamber and at least one ionizer capable of charging dust particles. The system can also include a dust particle feeder that is capable of introducing the dust particles into the accelerator. By applying a pulsed positive and negative charge voltage to the accelerator, the charged dust particles can be accelerated thereby generating thrust and neutralizing the accelerator system.

Wirz, Richard E. (Inventor)

2010-01-01

93

Cyclic steam stimulation with formation parting  

SciTech Connect

Cyclic steam stimulation in highly viscous oil-bearing formations, such as those of Cold Lake, entails formation parting in many cases. This work presents a numeric treatment of the phenomena involved in this process, viz., fluid flow in cyclic steam stimulation, formation parting, fracture propagation, and closure. The latter part of the model involves the calculation of stresses and strains in the formation as well as in the surrounding rocks, as a result of pressure and temperature changes, which are used to calculate the fracture length at various times. Fluid flow in the cyclic steam stimulation process is simulated by a 3-phase heat-fluid flow model, with implicit solution and special procedures to minimize computational time. A coupled well model allows for 6 different well operation conditions, including fluid storage in the fracture. A new criterion for fracture propagation and closure is offered that seems to reflect the reported behavior in the field. 20 references.

Farouq.Ali, S.M.; Blunschi, J.

1983-01-01

94

Evaluation of homogeneous electrocatalysts by cyclic voltammetry.  

PubMed

The pursuit of solar fuels has motivated extensive research on molecular electrocatalysts capable of evolving hydrogen from protic solutions, reducing CO2, and oxidizing water. Determining accurate figures of merit for these catalysts requires the careful and appropriate application of electroanalytical techniques. This Viewpoint first briefly presents the fundamentals of cyclic voltammetry and highlights practical experimental considerations before focusing on the application of cyclic voltammetry for the characterization of electrocatalysts. Key metrics for comparing catalysts, including the overpotential (?), potential for catalysis (Ecat), observed rate constant (kobs), and potential-dependent turnover frequency, are discussed. The cyclic voltammetric responses for a general electrocatalytic one-electron reduction of a substrate are presented along with methods to extract figures of merit from these data. The extension of this analysis to more complex electrocatalytic schemes, such as those responsible for H2 evolution and CO2 reduction, is then discussed. PMID:25247280

Rountree, Eric S; McCarthy, Brian D; Eisenhart, Thomas T; Dempsey, Jillian L

2014-10-01

95

Generalized Coefficients for Hopf Cyclic Cohomology  

NASA Astrophysics Data System (ADS)

A category of coefficients for Hopf cyclic cohomology is defined. It is shown that this category has two proper subcategories of which the smallest one is the known category of stable anti Yetter-Drinfeld modules. The middle subcategory is comprised of those coefficients which satisfy a generalized SAYD condition depending on both the Hopf algebra and the (co)algebra in question. Some examples are introduced to show that these three categories are different. It is shown that all components of Hopf cyclic cohomology work well with the new coefficients we have defined.

Hassanzadeh, Mohammad; Kucerovsky, Dan; Rangipour, Bahram

2014-09-01

96

mMass as a Software Tool for the Annotation of Cyclic Peptide Tandem Mass Spectra  

PubMed Central

Natural or synthetic cyclic peptides often possess pronounced bioactivity. Their mass spectrometric characterization is difficult due to the predominant occurrence of non-proteinogenic monomers and the complex fragmentation patterns observed. Even though several software tools for cyclic peptide tandem mass spectra annotation have been published, these tools are still unable to annotate a majority of the signals observed in experimentally obtained mass spectra. They are thus not suitable for extensive mass spectrometric characterization of these compounds. This lack of advanced and user-friendly software tools has motivated us to extend the fragmentation module of a freely available open-source software, mMass (http://www.mmass.org), to allow for cyclic peptide tandem mass spectra annotation and interpretation. The resulting software has been tested on several cyanobacterial and other naturally occurring peptides. It has been found to be superior to other currently available tools concerning both usability and annotation extensiveness. Thus it is highly useful for accelerating the structure confirmation and elucidation of cyclic as well as linear peptides and depsipeptides. PMID:23028676

Niedermeyer, Timo H. J.; Strohalm, Martin

2012-01-01

97

Collecting Cyclic Distributed Garbage by Controlled Migration  

E-print Network

Collecting Cyclic Distributed Garbage by Controlled Migration Umesh Maheshwari Barbara Liskov M distributed across nodes. A common proposal is to migrate all objects on a garbage cycle to a single node due to unnecessary migration of objects. We present solutions to these problems: our scheme avoids

98

Cyclic steam injection successful at Wilmington  

Microsoft Academic Search

The Wilmington Field, largest oil field in the Los Angeles basin, extends southeast into the tidelands area off the City of Long Beach. Cyclic steam injections began in Feb 1965 on a site at Pier B which included 14 wells producing from the Tar Zone of Fault Block V. Production behavior for the 14 wells in the trail pattern is

J. A. Teberg; P. B. Kemp

1966-01-01

99

Cyclic Fatigue Behaviour of Adhesive Joints.  

National Technical Information Service (NTIS)

In the last six months we have: (a) Concentrated our efforts on the fatigue failure of carbon-fibre PEEK/AFl63 lap joints, and in particular we have started to predict the life time of single-lap joints under cyclic fatigue loading. The analysis is based ...

A. J. Kinloch, T. Toh

1995-01-01

100

Static and Cyclic Fatigue of Ceramic Materials.  

National Technical Information Service (NTIS)

Static and cyclic fatigue characteristics were determined for two ceramic materials, an alumina AD-94 and a hot-pressed boron carbide B4C. The static fatigue limits determined in three-point flexure were 23,500 psi for Al2,O3 and 43,000 psi for B4C, while...

R. Chait, S. J. Acquaviva

1972-01-01

101

Failure mechanism models for cyclic fatigue  

Microsoft Academic Search

This work illustrates design situations where mechanical fatigue under cyclic loading, of one or more components, can compromise system performance. In this failure mechanism, damage accumulates with each load cycle, thereby causing a physical wearout failure mechanism. Phenomenological continuum length-scale models, based on micromechanical considerations, are presented to predict the onset (or initiation) of fatigue cracking in ductile materials. Fatigue

Abhijit Dasgupta; Reader Aids

1993-01-01

102

Raft and Pile Foundations under Cyclic Loading  

Microsoft Academic Search

The paper presents typical phenomena which can occur due to cyclic loading in granular soil. Numerical analysis with different material laws shows the challenges to simulate the ground behaviour realistically. Results of numerical analysis by means of the Finite-Element-Method are presented and the limitation of material laws discussed.

S. Meissner; H. Quick; U. Arslan

103

Gonadotropins Regulate Inducible Cyclic Adenosine 3 ,5 -  

E-print Network

Gonadotropins Regulate Inducible Cyclic Adenosine 3 ,5 - Monophosphate Early Repressor in the Rat of CREM might have a role in the LH-mediated suppression of inhibin -subunit gene expression that occurs (ICER). ICER mRNAs are strongly induced in the ovary by exogenous gonadotropins in immature rats

Mayo, Kelly E.

104

Quadruped Gait Learning Using Cyclic Genetic Algorithms  

E-print Network

and in particular, Genetic Algorithms, have previously been used to develop gaits for legged (primarily hexapod]. In a previous work Parker made use of cyclic genetic algorithms to develop walking gaits for a hexapod robot [5]. Each of the six legs of this hexapod robot could only move vertically and horizontally and the number

Parker, Gary B.

105

Ants, Crickets and Frogs in Cyclic Pursuit  

E-print Network

Ants, Crickets and Frogs in Cyclic Pursuit A.M. Bruckstein 1 , N. Cohen 2 , A. Efrat 1 Abstract. We and with preassigned, varying speeds. We also consider two discrete analogs, in which crickets or frogs are engaged with synchronized crickets that jump together every unit of time. Here the relative complexity of the problem

Efrat, Alon

106

CYCLICITY OF (Z/(p)) KEITH CONRAD  

E-print Network

/(p))? is cyclic is that they are non-constructive. Up to this day, there is no algorithm known for finding discount earlier classified work by British intelligence) and ElGamal. You can find out how, the order of any element divides p - 1. For each positive divisor of p - 1, say d, let Np(d) be the number

Lozano-Robledo, Alvaro

107

Cyclic voltammetry studies on pure lead  

Microsoft Academic Search

The behavior of pure lead in sulfuric acid was studied by cyclic voltammetry. The appearance of an anodic current peak on the cathodic portion of the sweep, previously attributed to a phase change in the lead dioxide film, is re-interpreted in the light of this work as being due to the oxidation of water by an intermediate lead III species.

J. G. Sunderland

1976-01-01

108

A cyclic GMP-dependent signalling pathway regulates bacterial phytopathogenesis.  

PubMed

Cyclic guanosine 3',5'-monophosphate (cyclic GMP) is a second messenger whose role in bacterial signalling is poorly understood. A genetic screen in the plant pathogen Xanthomonas campestris (Xcc) identified that XC_0250, which encodes a protein with a class III nucleotidyl cyclase domain, is required for cyclic GMP synthesis. Purified XC_0250 was active in cyclic GMP synthesis in vitro. The linked gene XC_0249 encodes a protein with a cyclic mononucleotide-binding (cNMP) domain and a GGDEF diguanylate cyclase domain. The activity of XC_0249 in cyclic di-GMP synthesis was enhanced by addition of cyclic GMP. The isolated cNMP domain of XC_0249 bound cyclic GMP and a structure-function analysis, directed by determination of the crystal structure of the holo-complex, demonstrated the site of cyclic GMP binding that modulates cyclic di-GMP synthesis. Mutation of either XC_0250 or XC_0249 led to a reduced virulence to plants and reduced biofilm formation in vitro. These findings describe a regulatory pathway in which cyclic GMP regulates virulence and biofilm formation through interaction with a novel effector that directly links cyclic GMP and cyclic di-GMP signalling. PMID:23881098

An, Shi-Qi; Chin, Ko-Hsin; Febrer, Melanie; McCarthy, Yvonne; Yang, Jauo-Guey; Liu, Chung-Liang; Swarbreck, David; Rogers, Jane; Maxwell Dow, J; Chou, Shan-Ho; Ryan, Robert P

2013-09-11

109

Synthesis and characterization of cyclic acetal based degradable hydrogels.  

PubMed

While many synthetic, hydrolytically degradable hydrogels have been developed for biomedical applications, there are only a few examples whose polymer backbone does not form acidic products upon degradation. In order to address this concern, we proposed to develop a hydrogel based on a cyclic acetal unit that produces diols and propanals upon hydrolytic degradation. In particular, we proposed the fabrication of hydrogels formed by the free radical polymerization of two diacrylate monomers, 5-ethyl-5-(hydroxymethyl)-beta,beta-dimethyl-1,3-dioxane-2-ethanol diacrylate (EHD), a cyclic acetal having two acryl groups, and poly(ethylene glycol)diacrylate (PEGDA). However, the hydrophobicity of the EHD monomer inhibits hydrogel fabrication. Therefore this work develops a strategy to form hydrogels with a co-monomer system, one of which is hydrophobic, and subsequently describes the properties of the resulting hydrogel. Using benzoyl peroxide as an initiator and N,N-dimethyl-p-toluidine as an accelerator, the EHD and PEGDA monomers were reacted in an acetone/water co-solvent system. The chemical structure of the resulting EH-PEG [5-ethyl-5-(hydroxymethyl)-beta,beta-dimethyl-1,3-dioxane-2-ethanol-co-PEG] hydrogel was then characterized by FT-IR. Physicochemical properties of the EH-PEG hydrogel, including swelling degree, sol fraction, and contact angle, were determined so as to characterize the properties of these materials and ultimately investigate their use in drug delivery and tissue engineering applications. Results showed that EH-PEG hydrogel may be formed using the co-solvent system. Further results indicated that swelling degree is dependent upon initiator concentration, monomer concentration, and molar ratios of monomers, while sol fraction significantly depended on initiator concentration and monomer concentration, only. These results demonstrate the ability to fabricate hydrogels using EHD and PEGDA system as well as to control the properties of the resulting hydrophilic networks. PMID:17888640

Kaihara, Sachiko; Matsumura, Shuichi; Fisher, John P

2008-01-01

110

Chemical Accelerators The phrase "chemical accelerators"  

E-print Network

Meetings Chemical Accelerators The phrase "chemical accelerators" is scarcely older than for one or two dozen people grew to include nearly a hundred. Chemical accelerators is a name sug- gested by one of us for devices that produce beams of chemically interesting species at relative kinetic

Zare, Richard N.

111

Evolving Cyclic Control for a Hexapod Robot Performing Area Coverage  

E-print Network

Evolving Cyclic Control for a Hexapod Robot Performing Area Coverage Gary B. Parker Department. In this paper, we use cyclic genetic al- gorithms to learn the control cycles required to make an actual hexapod

Parker, Gary B.

112

Unified Constitutive Modeling for Proportional and Nonproportional Cyclic Plasticity Responses.  

E-print Network

??Several features of cyclic plasticity, e.g. cyclic hardening/softening, ratcheting, relaxation, and their dependence on strain range, nonproportionality of loading, time, and temperature determine the stress-strain (more)

Krishna, Shree

2009-01-01

113

Rhodium-catalyzed dehydrogenative borylation of cyclic alkenes  

E-print Network

A rhodium-catalyzed dehydrogenative borylation of cyclic alkenes is described. This reaction provides direct access to cyclic 1-alkenylboronic acid pinacol esters, useful intermediates in organic synthesis. SuzukiMiyaura ...

Kondoh, Azusa

114

Cyclic Diguanylate Signaling Proteins Control Intracellular Growth of Legionella pneumophila  

E-print Network

Cyclic Diguanylate Signaling Proteins Control Intracellular Growth of Legionella pneumophila Assaf, and virulence. The role of cyclic diguanylate signaling in the lifestyle of Legionella pneumophila of Legionnaires' disease, Legionella pneumophila, is an intracellular pathogen that grows inside environmental

115

Cyclic AMP-dependent functional forms of cyclic AMP receptor protein from Vibrio cholerae  

Microsoft Academic Search

The cyclic AMP receptor protein (CRP) from Escherichia coli, involved in the transcriptional regulation of a number of genes and operons, works by binding to specific sites upstream of promoters. CRP also binds cyclic AMP (cAMP), and this binding, which causes conformational changes in CRP, is mandatory for its activity. A cAMP-dependent variation in the conformation as well as biological

Rima Chattopadhyay; Pradeep Parrack

2006-01-01

116

Cyclic nucleotide-gated channels in non-sensory organs  

Microsoft Academic Search

Cyclic nucleotide-gated channels represent a class of ion channels activated directly by the binding of either cyclic-GMP or cyclic-AMP. They carry both mono and divalent cations, but select calcium over sodium. In the majority of the cases studied, binding of cyclic nucleotides to the channel results in the opening of the channel and the influx of calcium. As a consequence,

N. Kraus-Friedmann

2000-01-01

117

Design of cyclic shift interleavers for Turbo Codes  

Microsoft Academic Search

In this paper we consider cyclic shift interleavers for turbo coding. The properties of cyclic shift interleavers are discussed\\u000a and compared with S-random interleavers. It is shown that the cyclic shift interleavers are equivalent or better than the\\u000a S-random interleavers in the ability to break low weight input patterns. We estimated the performance of turbo codes with\\u000a cyclic shift interleavers

Jinhong Yuan; Branka Vucetic; Wen Feng; Mark Tan

2001-01-01

118

Blind adaptive equalization of OFDM transmission with insufficient cyclic prefix  

Microsoft Academic Search

We create a new blind equalization method with both batch and adaptive algorithms developed for OFDM systems with insufficient cyclic prefix. Special correlation property of cyclic prefix is exploited for constraint estimation. Then constrained minimum-output-energy (MOE) optimization is applied for blind equalizer estimation. Using shorter cyclic prefix, we can either reduce block size for low complexity or enhance bandwidth efficiency.

Taewoo Han; Xiaohua Li

2004-01-01

119

Synthesis of cyclic sulfones by ring-closing metathesis.  

PubMed

A general and highly efficient synthesis of cyclic sulfones based on ring-closing metathesis has been developed. The synthetic utility of the resulting cyclic sulfones was demonstrated by their participation in stereoselective Diels-Alder reactions and transformation to cyclic dienes by the Ramberg-Bcklund reaction. PMID:11820896

Yao, Qingwei

2002-02-01

120

1. Tensile test 2. Fatigue Test (Cyclic strain effects)  

E-print Network

METHODS 1. Tensile test 2. Fatigue Test (Cyclic strain effects) 3. Fatigue Test (Mean stress% Ag 1x7 316LVM MP35N Silver · Cables are tested in cyclic fatigue via bending over a mandrel (R = -1). · Mandrel radius controls stress and strain experienced by wires. Flex tester used for cyclic fatigue tests

Rollins, Andrew M.

121

MONOTONIC AND CYCLIC FATIGUE BEHAVIOR OF HIGH PERFORMANCE CERAMIC FIBERS  

Microsoft Academic Search

Monotonic and cyclic fatigue behavior of single fibers or fiber fabrics are of significant interest, since fiber assemblies or fiber reinforced composite materials in structural applications are often subjected to cyclic loading. Studying the cyclic fatigue behavior of fibers is particularly difficult because of their small diameter (~10 m) and high aspect ratio. In this paper, we report results of

N. Chawla; M. Kerr; K. K. Chawla

122

Cyclic nucleotide metabolism in pineal homogenates.  

PubMed

Adenylate cyclase (AC) in pineal particulate fractions from rabbit, rat, cow, and the vole Microtus montanus was stimulated by L-norepinephrine (NE) and L-isoproterenol (ISO). NE stimulation of rabbit and bovine pineal AC was biphasic, with a plateau between 0.01 microM and 1.0 microM and additional stimulation by NE above 1.0 microM. Stimulation by different ISO concentrations gave a typical hyperbolic curve, and optimal stimulation by ISO exceeded that by NE. Melatonin decreased ISO and NE stimulation of AC 10-20%. Although, alpha-adrenergic agonists increase beta-agonist-mediated adenosine-3',5'-cyclic monophosphate (cyclic AMP) accumulation in intact pinealocytes, similar amplification of AC stimulation was not seen with broken-cell preparations. Most (60-70%) pineal guanylate cyclase (GC) was recovered in supernatant fractions after centrifugation of homogenates at 110,000 x g; this soluble GC was unaffected by potential agonists. Low concentrations (0.01-1 nM) of NE, ISO, and phenylephrine (PE) stimulated GC in impure and purified membrane fractions, but each inhibited at concentrations above 10 microM. All concentrations of ISO and NE inhibited GC in the presence of the alpha-agonist PE. Melatonin alone did not affect particulate GC, but L-ISO stimulation was not seen in the presence of equivalent concentrations of melatonin. The in vitro data are consistent with both alpha- and beta-receptor regulation of cyclic nucleotide metabolism in pinealocytes. Endogenous NE may differentially regulate cyclic AMP and guanosine-3',5'-cyclic monophosphate (cyclic GMP) in pineal; low NE concentrations that stimulate GC have only a slight effect on AC, but higher NE concentrations that inhibit GC maximally stimulate AC. Particulate GC and AC also were resolved by equilibrium centrifugation, to give several discrete peaks of enzyme activity. The results support the existence of several forms of AC and GC, which have different responses to adrenergic agonists. PMID:2905388

Sweat, F W; Carmack, C F; Jewell, L S

1988-01-01

123

Cyclic Oxidation Modeling and Life Prediction  

NASA Technical Reports Server (NTRS)

The cyclic oxidation process can be described as an iterative scale growth and spallation sequence by a number of similar models. Model input variable include oxide scale type and growth parameters, spalling geometry, spall constant, and cycle duration. Outputs include net weight change, the amounts of retained and spalled oxide, the total oxygen and metal consumed, and the terminal rates of weight loss and metal consumption. All models and their variations produce a number of similar characteristic features. In general, spalling and material consumption increase to a steady state rate, at which point the retained scale approaches a constant and the rate of weight loss becomes linear. For one model, this regularity was demonstrated as dimensionless, universal expressions, obtained by normalizing the variables by critical performance factors. These insights were enabled through the use of the COSP for Windows cyclic oxidation spalling program.

Smialek, James L.

2004-01-01

124

Cyclic debonding of adhesively bonded composites  

NASA Technical Reports Server (NTRS)

The fatigue behavior of a simple composite to composite bonded joint was analyzed. The cracked lap shear specimen subjected to constant amplitude cyclic loading was studied. Two specimen geometries were tested for each bonded system: (1) a strap adherend of 16 plies bonded to a lap adherend of 8 plies; and (2) a strap adherend of 8 plies bonded to a lap adherend of 16 plies. In all specimens the fatigue failure was in the form of cyclic debonding with some 0 deg fiber pull off from the strap adherend. The debond always grew in the region of adhesive that had the highest mode (peel) loading and that region was close to the adhesive strap interface.

Mall, S.; Johnson, W. S.; Everett, R. A., Jr.

1982-01-01

125

Combustion oscillation control by cyclic fuel injection  

SciTech Connect

A number of recent articles have demonstrated the use of active control to mitigate the effects of combustion instability in afterburner and dump combustor applications. In these applications, cyclic injection of small quantities of control fuel has been proposed to counteract the periodic heat release that contributes to undesired pressure oscillations. This same technique may also be useful to mitigate oscillations in gas turbine combustors, especially in test rig combustors characterized by acoustic modes that do not exist in the final engine configuration. To address this issue, the present paper reports on active control of a subscale, atmospheric pressure nozzle/combustor arrangement. The fuel is natural gas. Cyclic injection of 14% control fuel in a premix fuel nozzle is shown to reduce oscillating pressure amplitude by a factor of 0.30 (i.e., {approximately}10 dB) at 300 Hz. Measurement of the oscillating heat release is also reported.

Richards, G.A.; Yip, M.J. [USDOE Morgantown Energy Technology Center, WV (United States); Robey, E. [EG& G Technical Services of West Virginia, Morgantown Energy Technology Center, WV (United States); Cowell, L.; Rawlins, D. [Solar Turbines, Inc., San Diedgo, CA (United States)

1995-04-01

126

Bouncing and cyclic string gas cosmologies  

SciTech Connect

We show that, in the presence of a string gas, simple higher-derivative modifications to the effective action for gravity can lead to bouncing and cyclic cosmological models. The modifications bound the expansion rate and avoid singularities at finite times. In these models the scale factors can have long loitering phases that solve the horizon problem. Adding a potential for the dilaton gives a simple realization of the pre-big bang scenario. Entropy production in the cyclic phase drives an eventual transition to a radiation-dominated Universe. As a test of the Brandenberger-Vafa scenario, we comment on the probability of decompactifying three spatial dimensions in this class of models.

Greene, Brian; Marnerides, Stefanos [Institute for Strings, Cosmology and Astroparticle Physics and Department of Physics, Columbia University, New York, New York 10027 (United States); Kabat, Daniel [Institute for Strings, Cosmology and Astroparticle Physics and Department of Physics, Columbia University, New York, New York 10027 (United States); Department of Physics and Astronomy, Lehman College, City University of New York, Bronx, New York 10468 (United States)

2009-09-15

127

Wakefield Acceleration in Structures  

Microsoft Academic Search

Wakefield acceleration in dielectric loaded structures is discussed in this paper. We present a description of the dielectric wakefield accelerator concept, comparing some features of the collinear and the two beam accelerator configurations. The Argonne Wakefield Accelerator Facility (AWA) is discussed in detail, including major upgrades that are presently taking place. The basic features and capabilities of the facility are

M. E. Conde

2002-01-01

128

Cyclic nucleotide signaling in polycystic kidney disease  

Microsoft Academic Search

Increased levels of 3?-5?-cyclic adenosine monophosphate (cAMP) stimulate cell proliferation and fluid secretion in polycystic kidney disease. Levels of this molecule are more sensitive to inhibition of phosphodiesterases (PDEs), whose activity far exceeds the rate of cAMP synthesis by adenylyl cyclase. Several PDEs exist, and here we measured the activity and expression of PDE families, their isoforms, and the expression

Xiaofang Wang; Christopher J Ward; Peter C Harris; Vicente E Torres

2010-01-01

129

Precedence Constraint Posting for Cyclic Scheduling Problems  

Microsoft Academic Search

\\u000a Resource constrained cyclic scheduling problems consist in planning the execution over limited resources of a set of activities,\\u000a to be indefinitely repeated. In such a context, the iteration period (i.e. the difference between the completion time of consecutive iterations) naturally\\u000a replaces the makespan as a quality measure; exploiting inter-iteration overlapping is the primary method to obtain high quality\\u000a schedules. Classical

Michele Lombardi; Alessio Bonfietti; Michela Milano; Luca Benini

2011-01-01

130

Protein denaturation induced by cyclic silicone  

Microsoft Academic Search

While it has been demonstrated that such low-molecular-weight cyclic silicones as octamethylcyclo-tetrasiloxane (D4) exhibit adjuvant activity, the mechanism of immunological response to silicone is still not clear. This study therefore used fluorescence and circular dichroism (CD) spectroscopy to investigate the denaturation and conformational change of two proteins, fibronectin (Fn) and fibrinogen (Fbg), induced by D4in vitro. Incubating D4 with Fbg

Linfeng Sun; Harold Alexander; Nina Lattarulo; Norman C. Blumenthal; John L. Ricci; Guo-gang Chen

1997-01-01

131

Cyclic pursuit with vision-assisted estimation  

Microsoft Academic Search

This paper presents vision-assisted cyclic pursuit for nonholonomic vehicles without direct communication among the agents. The requirement on communication among agents is relaxed by vision-assisted estimation via a local onboard camera for each agent. A fast estimator is utilized for estimation of the other agent's unknown time-varying velocity. The effectiveness of the proposed technique is demonstrated by numerical simulation examples.

Lili Ma; Naira Hovakimyan

2010-01-01

132

Precoder for DMT with insufficient cyclic prefix  

Microsoft Academic Search

Multi-carrier modulation is a modulation technique that enables higher transmission rate than traditional techniques, such as single-carrier quadrature amplitude modulation (QAM) systems. One implementation of multi-carrier modulation technique is discrete multi-tone (DMT). DMT used in asymmetric digital subscriber lines (ADSL) and very high speed DSL (VDSL) systems has a fixed cyclic prefix length. When the impulse response of the channel

Kok-Wui Cheong; J. M. Cioffi

1998-01-01

133

Optimum Cyclic Redundancy Codes for Noisy Channels  

NASA Technical Reports Server (NTRS)

Capabilities and limitations of cyclic redundancy codes (CRC's) for detecting transmission errors in data sent over relatively noisy channels (e.g., voice-grade telephone lines or very-high-density storage media) discussed in 16-page report. Due to prevalent use of bytes in multiples of 8 bits data transmission, report primarily concerned with cases in which both block length and number of redundant bits (check bits for use in error detection) included in each block are multiples of 8 bits.

Posner, E. C.; Merkey, P.

1986-01-01

134

Cyclic Thermodynamic Processes and Entropy Production  

Microsoft Academic Search

We study the time evolution of a periodically driven quantum-mechanical system coupled to several reservoirs of free fermions\\u000a at different temperatures. This is a paradigm of a cyclic thermodynamic process. We introduce the notion of a Floquet Liouvillean\\u000a as the generator of the dynamics of the coupled system on an extended Hilbert space. We show that the time-periodic state\\u000a which

Walid K. Abou Salem; Jrg Frhlich

2007-01-01

135

An undersampling 14-bit cyclic ADC  

Microsoft Academic Search

An undersampling 14-bit 357 kSps cyclic ADC is designed for radio frequency identification (RFID) transceiver system. Modified passive capacitor error-average (PCEA) technique is adopted for high accuracy. Opamp sharing and the removal of front-end SHA are utilized for low power dissipation and small chip area. The proposed chip is fabricated in a 180 nm CMOS process, and it occupies 0.65

Weitao Li; Fule Li; Dandan Guo; Chun Zhang; Zhihua Wang

2009-01-01

136

SLAC National Accelerator Laboratory Accelerator Physics Faculty Search  

E-print Network

SLAC National Accelerator Laboratory Accelerator Physics Faculty Search The SLAC National Accelerator Laboratory invites applications for a faculty appointment in Accelerator Physics (LCLS), LCLS-II, SPEAR-3, NLC Test Accelerator (NLCTA), Cathode Test Facility (CTF), the proposed

Ford, James

137

Wakefield acceleration in structures.  

SciTech Connect

Wakefield acceleration in dielectric loaded structures is discussed in this paper. We present a description of the dielectric wakefield accelerator concept, comparing some features of the collinear and the two beam accelerator configurations. The Argonne Wakefield Accelerator Facility (AWA) is discussed in detail, including major upgrades that are presently taking place. The basic features and capabilities of the facility are presented, and the dielectric wakefield acceleration results are briefly summarized. Possible variants of the two beam accelerator configuration are discussed, and work on planar dielectric structures in various institutions is presented. We conclude this report mentioning prospective achievements of dielectric wakefield accelerating structures.

Conde, M. E.

2002-09-17

138

Wakefield Acceleration in Structures  

NASA Astrophysics Data System (ADS)

Wakefield acceleration in dielectric loaded structures is discussed in this paper. We present a description of the dielectric wakefield accelerator concept, comparing some features of the collinear and the two beam accelerator configurations. The Argonne Wakefield Accelerator Facility (AWA) is discussed in detail, including major upgrades that are presently taking place. The basic features and capabilities of the facility are presented, and the dielectric wakefield acceleration results are briefly summarized. Possible variants of the two beam accelerator configuration are discussed, and work on planar dielectric structures in various institutions is presented. We conclude this report mentioning prospective achievements of dielectric wakefield accelerating structures.

Conde, M. E.

2002-01-01

139

Wakefield Acceleration in Structures  

NASA Astrophysics Data System (ADS)

Wakefield acceleration in dielectric loaded structures is discussed in this paper. We present a description of the dielectric wakefield accelerator concept, comparing some features of the collinear and the two beam accelerator configurations. The Argonne Wakefield Accelerator Facility (AWA) is discussed in detail, including major upgrades that are presently taking place. The basic features and capabilities of the facility are presented, and the dielectric wakefield acceleration results are briefly summarized. Possible variants of the two beam accelerator configuration are discussed, and work on planar dielectric structures in various institutions is presented. We conclude this report mentioning prospective achievements of dielectric wakefield accelerating structures.

Conde, Manoel E.

2002-12-01

140

Cyclic dominance in evolutionary games: A review  

E-print Network

Rock is wrapped by paper, paper is cut by scissors, and scissors are crushed by rock. This simple game is popular among children and adults to decide on trivial disputes that have no obvious winner, but cyclic dominance is also at the heart of predator-prey interactions, the mating strategy of side-blotched lizards, the overgrowth of marine sessile organisms, and the competition in microbial populations. Cyclical interactions also emerge spontaneously in evolutionary games entailing volunteering, reward, punishment, and in fact are common when the competing strategies are three or more regardless of the particularities of the game. Here we review recent advances on the rock-paper-scissors and related evolutionary games, focusing in particular on pattern formation, the impact of mobility, and the spontaneous emergence of cyclic dominance. We also review mean-field and zero-dimensional rock-paper-scissors models and the application of the complex Ginzburg-Landau equation, and we highlight the importance and use...

Szolnoki, Attila; Jiang, Luo-Luo; Szczesny, Bartosz; Rucklidge, Alastair M; Perc, Matjaz

2014-01-01

141

Cyclic debonding of adhesively bonded composites  

NASA Technical Reports Server (NTRS)

To analyze the fatigue behavior of a simple composite-to-composite bonded joint, a combined experimental and analytical study of the cracked-lap-shear specimen subjected to constant-amplitude cyclic loading was undertaken. Two bonded systems were studied: T300/5208 graphite/epoxy adherends bonded with adhesives EC 3445 and with FM-300. For each bonded system, two specimen geometries were tested: (1) a strap adherend of 16 plies bonded to a lap adherend of 8 plies, and (2) a strap adherend of 8 plies bonded to a lap adherend of 16 plies. In all specimens tested, the fatigue failure was in the form of cyclic debonding with some 0 deg fiber pull-off from the strap adherend. The debond always grew in the region of adhesive that had the highest mode I (peel) loading and that region was close to the adhesive-strap interface. Furthermore, the measured cyclic debond growth rates correlated well with total strain energy release rates G(T) as well as with its components G(I) (peel) and G(II) (shear) for the mixed-mode loading in the present study.

Mall, S.; Johnson, W. S.; Everett, R. A., Jr.

1984-01-01

142

High-affinity Cyclic Peptide Matriptase Inhibitors*  

PubMed Central

The type II transmembrane serine protease matriptase is a key activator of multiple signaling pathways associated with cell proliferation and modification of the extracellular matrix. Deregulated matriptase activity correlates with a number of diseases, including cancer and hence highly selective matriptase inhibitors may have therapeutic potential. The plant-derived cyclic peptide, sunflower trypsin inhibitor-1 (SFTI-1), is a promising drug scaffold with potent matriptase inhibitory activity. In the current study we have analyzed the structure-activity relationships of SFTI-1 and Momordica cochinchinensis trypsin inhibitor-II (MCoTI-II), a structurally divergent trypsin inhibitor from Momordica cochinchinensis that also contains a cyclic backbone. We show that MCoTI-II is a significantly more potent matriptase inhibitor than SFTI-1 and that all alanine mutants of both peptides, generated using positional scanning mutagenesis, have decreased trypsin affinity, whereas several mutations either maintain or result in enhanced matriptase inhibitory activity. These intriguing results were used to design one of the most potent matriptase inhibitors known to date with a 290 pm equilibrium dissociation constant, and provide the first indication on how to modulate affinity for matriptase over trypsin in cyclic peptides. This information might be useful for the design of more selective and therapeutically relevant inhibitors of matriptase. PMID:23548907

Quimbar, Pedro; Malik, Uru; Sommerhoff, Christian P.; Kaas, Quentin; Chan, Lai Y.; Huang, Yen-Hua; Grundhuber, Maresa; Dunse, Kerry; Craik, David J.; Anderson, Marilyn A.; Daly, Norelle L.

2013-01-01

143

Cyclic steaming in heavy oil diatomite  

SciTech Connect

Chevron currently uses cyclic steaming as a recovery method to produce economically its heavy oil diatomite resource in the Cymric field, San Joaquin Valley, California. A highly instrumented, cyclically steaming well from this field was simulated in this study to delineate important production mechanisms, to optimize operations, and to improve reservoir management. The model was constrained, as much as possible, by the available measured data. Results show that fluid flow from the well to the reservoir is primarily through the hydraulic fracture induced by the injected steam. Parameters with unique importance to modeling cyclic steaming in diatomites are: (1) induced fracture dimension (length and height), (2) matrix permeability, (3) oil/water capillary pressure, (4) grid size perpendicular to fracture face, and (5) producing bottomhole pressures. Additionally, parameters important for conventional steam injection processes, such as relative permeabilities and injected steam volume, quality, and rate, are important for diatomites also. Oil production rates and steam/oil ratios calculated by this model compare reasonably with field data.

Kumar, M.; Beatty, F.D.

1995-12-31

144

Cyclic dominance in evolutionary games: a review  

PubMed Central

Rock is wrapped by paper, paper is cut by scissors and scissors are crushed by rock. This simple game is popular among children and adults to decide on trivial disputes that have no obvious winner, but cyclic dominance is also at the heart of predatorprey interactions, the mating strategy of side-blotched lizards, the overgrowth of marine sessile organisms and competition in microbial populations. Cyclical interactions also emerge spontaneously in evolutionary games entailing volunteering, reward, punishment, and in fact are common when the competing strategies are three or more, regardless of the particularities of the game. Here, we review recent advances on the rockpaperscissors (RPS) and related evolutionary games, focusing, in particular, on pattern formation, the impact of mobility and the spontaneous emergence of cyclic dominance. We also review mean-field and zero-dimensional RPS models and the application of the complex GinzburgLandau equation, and we highlight the importance and usefulness of statistical physics for the successful study of large-scale ecological systems. Directions for future research, related, for example, to dynamical effects of coevolutionary rules and invasion reversals owing to multi-point interactions, are also outlined. PMID:25232048

Szolnoki, Attila; Mobilia, Mauro; Jiang, Luo-Luo; Szczesny, Bartosz; Rucklidge, Alastair M.; Perc, Matjaz

2014-01-01

145

Cyclic dominance in evolutionary games: a review.  

PubMed

Rock is wrapped by paper, paper is cut by scissors and scissors are crushed by rock. This simple game is popular among children and adults to decide on trivial disputes that have no obvious winner, but cyclic dominance is also at the heart of predator-prey interactions, the mating strategy of side-blotched lizards, the overgrowth of marine sessile organisms and competition in microbial populations. Cyclical interactions also emerge spontaneously in evolutionary games entailing volunteering, reward, punishment, and in fact are common when the competing strategies are three or more, regardless of the particularities of the game. Here, we review recent advances on the rock-paper-scissors (RPS) and related evolutionary games, focusing, in particular, on pattern formation, the impact of mobility and the spontaneous emergence of cyclic dominance. We also review mean-field and zero-dimensional RPS models and the application of the complex Ginzburg-Landau equation, and we highlight the importance and usefulness of statistical physics for the successful study of large-scale ecological systems. Directions for future research, related, for example, to dynamical effects of coevolutionary rules and invasion reversals owing to multi-point interactions, are also outlined. PMID:25232048

Szolnoki, Attila; Mobilia, Mauro; Jiang, Luo-Luo; Szczesny, Bartosz; Rucklidge, Alastair M; Perc, Matja

2014-11-01

146

Cyclic steady state stress-strain behavior of UHMW polyethylene.  

PubMed

To increase the long-term performance of total joint replacements, finite element analyses of ultra high molecular weight polyethylene (UHMWPE) components have been conducted to predict the effect of load on the stress and strain distributions occurring on and within these components. Early models incorporated the monotonic behavior of UHMWPE without considering the unloading and cyclic loading behavior. However, UHMWPE components undergo cyclic loading during use and at least two wear damage modes (pitting and delamination) are thought to be associated with the fatigue fracture properties of UHMWPE. The objective of this study was to examine the fully reversed uniaxial tension/compression cyclic steady state stress-strain behavior of UHMWPE as a first step towards developing a cyclic constitutive relationship for UHMWPE. The hypothesis that cycling results in a permanent change in the stress-strain relationship, that is, that the cyclic steady state represents a new cyclically stabilized state, was examined. It was found that, like other ductile polymers, UHMWPE substantially cyclically softens under fully reversed uniaxial straining. More cyclic softening occurred in tension than in compression. Furthermore, cyclic steady state was attained, but not cyclic stability. It is suggested that it may be more appropriate to base a material constitutive relationship for UHMWPE for finite element analyses of components upon a cyclically modified stress-strain relationship. PMID:10966018

Krzypow, D J; Rimnac, C M

2000-10-01

147

Reduced models of multi-stage cyclic structures using cyclic symmetry reduction and component mode synthesis  

NASA Astrophysics Data System (ADS)

Reduced models of multi-stage cyclic structures such as bladed-disk assemblies are developed by using the multi-stage cyclic symmetry reduction and/or component mode synthesis methods. The multi-stage cyclic symmetry reduction consists in writing the equations of the bladed disks, the inter-disk structures, the inter-disk constraints and the whole multi-stage coupled system in terms of the traveling wave coordinates for all the phase indexes of the reference sectors and for all the bladed disks. Several reduced coupled systems are then solved by selecting at each time only one or a few phase indexes for each bladed disk and by applying the cyclic symmetry boundary conditions. On the other hand, component mode synthesis methods are used either independently or in combination with the multi-stage cyclic symmetry reduction to obtain reduced models of the multi-stage structure. Two of them are particularly efficient, that are firstly component mode synthesis methods with interface modes applied on the bladed disks and secondly component mode synthesis methods with traveling wave coordinates applied on the reference sectors.

Tran, Duc-Minh

2014-10-01

148

A conceptual model of cyclical glacier flow in overdeepenings  

NASA Astrophysics Data System (ADS)

A nearly four-decade, satellite-based velocity survey of the largest glaciers in the Alaska Range, Chugach Mountains, and the Wrangell Mountains of southern Alaska, spanning the early- to mid-1970s through the 2000s, reveals nine pulsing glaciers: Capps, Copper, Eldridge, Kahiltna, Matanuska, Nabesna, Nizina, Ruth, and Sanford glaciers. The pulses increase velocity by up to 2449% (Capps Glacier) or as little as 77% (Nabesna Glacier), with velocity increases for the other glaciers in the range of 100-250%. The pulses may last from between six years (Copper Glacier) to 12 years (Nizina Glacier) and consist of a multi-year acceleration phase followed by a multi-year deceleration phase during which significant portions of each glacier move en masse. The segments of each glacier affected by the pulses may be anywhere from 14 km (Sanford Glacier) to 36 km (Nabesna Glacier) in length and occur where the glaciers are either laterally constricted or joined by a major tributary, and the surface slopes at these locations are very shallow, 1-2, suggesting the pulses occur where the glaciers are overdeepened. A conceptual model to explain the cyclical behavior of these pulsing glaciers is presented that incorporates the effects of glaciohydraulic supercooling, glacier dynamics, surface ablation, and subglacial sediment erosion, deposition, and deformation in overdeepenings.

Turrin, J. B.; Forster, R. R.

2014-08-01

149

Surface and interface properties of carbon fiber composites under cyclical aging  

NASA Astrophysics Data System (ADS)

Carbon fiber-reinforced BMI composites have been subjected to combination accelerated aging comprising a hygrothermal process, a thermal-oxidative process, and a freezing process in order to simulate their responses under complicated service environments. This cyclical condition, including the freezing process, has not been investigated by other researchers so far. The effects of this combination accelerated aging on the mechanical properties have been characterized by FTIR, SEM/EDXA, XRD, and moisture-uptake determination. The results indicated that combination accelerated aging had great effects on the mechanical properties of the composite, the network structure of the BMI matrix, and the moisture uptake by the composite. After a third cycle of accelerated aging, moisture reached the center layer of the composite and as a result led to an obvious decrease in ILSS due to deterioration of the carbon fiber-BMI interface. Sufficient moisture absorption on the composite surface made the network structure of the BMI matrix more open, which facilitated stress relaxation and the creation of micro-cracks, with a consequent obvious decrease in flexural strength. With increasing number of combined-action accelerated aging cycles, ever more moisture was absorbed during each hygrothermal process due to the plasticizing effect of water, and micro-cracks propagated as a result of internal stresses caused by the hygrothermal process, the thermal-oxidative process, and the freezing process of each cycle. XRD analysis indicated that moisture penetrated through the amorphous region of the BMI matrix.

Lv, Xinying; Wang, Rongguo; Liu, Wenbo; Jiang, Long

2011-10-01

150

Regulation of intracellular cyclic AMP in skeletal muscle cells involves the efflux of cyclic nucleotide to the extracellular compartment  

PubMed Central

This report analyses the intracellular and extracellular accumulation of cyclic AMP in primary rat skeletal muscle cultures, after direct and receptor-dependent stimulation of adenylyl cyclase (AC). Isoprenaline, calcitonin gene-related peptide (CGRP) and forskolin induced a transient increase in the intracellular cyclic AMP that peaked 5 min after onset stimulation. Under stimulation with isoprenaline or CGRP, the intracellular cyclic AMP initial rise was followed by an exponential decline, reaching 46 and 52% of peak levels in 10 min, respectively. Conversely, the forskolin-dependent accumulation of intracellular cyclic AMP decreased slowly and linearly, reaching 49% of the peak level in 30 min. The loss of intracellular cyclic AMP from peak levels, induced by direct or receptor-induced activation of AC, was followed by an increase in the extracellular cyclic AMP. This effect was independent on PDEs, since it was obtained in the presence of 3-isobutyl-1-methylxanthine (IBMX). Besides, in isoprenaline treated cells, the beta-adrenoceptor antagonist propranolol reduced both intra- and extracellular accumulation of cyclic AMP, whereas the organic anion transporter inhibitor probenecid reduced exclusively the extracellular accumulation. Together our data show that direct or receptor-dependent activation of skeletal muscle AC results in a transient increase in the intracellular cyclic AMP, despite the continuous presence of the stimulus. The temporal declining of intracellular cyclic AMP was not dependent on the cyclic AMP breakdown but associated to the efflux of cyclic nucleotide to the extracellular compartment, by an active transport since it was prevented by probenecid. PMID:12642402

Godinho, Rosely Oliveira; Costa-Jr, Valter Luiz

2003-01-01

151

The coefficient of cyclic variation: a novel statistic to measure the magnitude of cyclic variation  

PubMed Central

Background Periodic or cyclic data of known periodicity are frequently encountered in epidemiological and biomedical research: for instance, seasonality provides a useful experiment of nature while diurnal rhythms play an important role in endocrine secretion. There is, however, little consensus on how to analysis these data and less still on how to measure association or effect size for the often complex patterns seen. Results A simple statistic, readily derived from Fourier regression models, provides a readily-understood measure cyclic variation in a wide variety of situations. Conclusion The coefficient of cyclic variation or similar statistics derived from the variance of a Fourier series could provide a universal means of summarising the magnitude of periodic variation. PMID:25342954

2014-01-01

152

Cyclic AMP Receptor Protein-Aequorin Molecular Switch for Cyclic AMP  

PubMed Central

Molecular switches are designer molecules that combine the functionality of two individual proteins into one, capable of manifesting an on/off signal in response to a stimulus. These switches have unique properties and functionalities and thus, can be employed as nanosensors in a variety of applications. To that end, we have developed a bioluminescent molecular switch for cyclic AMP. Bioluminescence offers many advantages over fluorescence and other detection methods including the fact that there is essentially zero background signal in physiological fluids, allowing for more sensitive detection and monitoring. The switch was created by combining the properties of the cyclic AMP receptor protein (CRP), a transcriptional regulatory protein from E. coli that binds selectively to cAMP with those of aequorin, a bioluminescent photoprotein native of the jellyfish Aequorea victoria. Genetic manipulation to split the genetic coding sequence of aequorin in two and genetically attach the fragments to the N and C termini of CRP, resulted in a hybrid protein molecular switch. The conformational change experienced by CRP upon the binding of cyclic AMP is suspected to result in the observed loss of bioluminescent signal from aequorin. The on/off bioluminescence can be modulated by cyclic AMP over a range of several orders of magnitude in a linear fashion in addition to the capacity to detect changes in cellular cyclic AMP of intact cells exposed to different external stimuli without the need to lyse the cells. We envision that the molecular switch could find applications in vitro as well as in vivo cyclic AMP detection and/or imaging. PMID:21329338

Scott, Daniel; Hamorsky, Krystal Teasley; Ensor, C. Mark; Anderson, Kimberly W.; Daunert, Sylvia

2011-01-01

153

Status of the Fatigue Studies on the CLIC Accelerating Structures  

E-print Network

The need for high accelerating gradients for the future multi-TeV e+e- Compact Linear Collider (CLIC) imposes considerable constraints on the materials of the accelerating structures. The surfaces exposed to high pulsed RF (Radio Frequency) currents are subject to cyclic thermal stresses which are expected to induce surface break up by fatigue. Since no fatigue data exists in the literature up to very large numbers of cycles and for the particular stress pattern present in RF cavities, a comprehensive study of copper alloys in this parameter range has been initiated. Fatigue data for selected copper alloys in different states are presented

Calatroni, S; Neupert, H; Wuensch, Walter; CERN. Geneva

2006-01-01

154

Interactions of cyclic and non-cyclic naphthalene diimide derivatives with different nucleic acids.  

PubMed

Recently, strategy based on stabilization of G-quadruplex telomeric DNA by small organic molecule has been realized by naphthalene diimide derivatives (NDIs). At the same time NDIs bind to DNA duplex as threading intercalators. Here we present cyclic derivative of naphthalene diimide (ligand 1) as DNA-binding ligand with ability to recognition of different structures of telomeric G-quadruplexes and ability to bis-intercalate to double-stranded helixes. The results have been compared to non-cyclic derivative (ligand 2) and revealed that preferential binding of ligands to nucleic acids strongly depends on their topology and structural features of ligands. PMID:24726302

Czerwinska, Izabella; Sato, Shinobu; Juskowiak, Bernard; Takenaka, Shigeori

2014-05-01

155

TURBULENT SHEAR ACCELERATION  

SciTech Connect

We consider particle acceleration by large-scale incompressible turbulence with a length scale larger than the particle mean free path. We derive an ensemble-averaged transport equation of energetic charged particles from an extended transport equation that contains the shear acceleration. The ensemble-averaged transport equation describes particle acceleration by incompressible turbulence (turbulent shear acceleration). We find that for Kolmogorov turbulence, the turbulent shear acceleration becomes important on small scales. Moreover, using Monte Carlo simulations, we confirm that the ensemble-averaged transport equation describes the turbulent shear acceleration.

Ohira, Yutaka, E-mail: ohira@phys.aoyama.ac.jp [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara 252-5258 (Japan)

2013-04-10

156

Cyclic Failure Mechanisms of Thermal and Environmental Barrier Coating Systems Under Thermal Gradient Test Conditions  

NASA Technical Reports Server (NTRS)

Plasma-sprayed ZrO2-8wt%Y2O3 and mullite+BSAS/Si multilayer thermal and environmental barrier coating (TBC-EBC) systems on SiC/SiC ceramic matrix composite (CMC) substrates were thermally cyclic tested under high thermal gradients using a laser high-heat-flux rig in conjunction with furnace exposure in water-vapor environments. Coating sintering and interface damage were assessed by monitoring the real-time thermal conductivity changes during the laser heat-flux tests and by examining the microstructural changes after exposure. Sintering kinetics of the coating systems were also independently characterized using a dilatometer. It was found that the coating failure involved both the time-temperature dependent sintering and the cycle frequency dependent cyclic fatigue processes. The water vapor environments not only facilitated the initial coating conductivity increases due to enhanced sintering and interface reaction, but also promoted later conductivity reductions due to the accelerated coating cracking and delamination. The failure mechanisms of the coating systems are also discussed based on the cyclic test results and are correlated to the sintering and thermal stress behavior under the thermal gradient test conditions.

Zhu, Dongming; Lee, Kang N.; Miller, Robert A.

2002-01-01

157

Long-Term Cyclic Oxidation Behavior of Wrought Commercial Alloys at High Temperatures  

SciTech Connect

The oxidation resistance of a high-temperature alloy is dependent upon sustaining the formation of a protective scale, which is strongly related to the alloying composition and the oxidation condition. The protective oxide scale only provides a finite period of oxidation resistance owing to its eventual breakdown, which is especially accelerated under thermal cycling conditions. This current study focuses on the long-term cyclic oxidation behavior of a number of commercial wrought alloys. The alloys studied were Fe- and Ni-based, containing different levels of minor elements, such as Si, Al, Mn, and Ti. Oxidation testing was conducted at 1000 and 1100 C in still air under both isothermal and thermal cycling conditions (1-day and 7-days). The specific aspects studied were the oxidation behavior of chromia-forming alloys that are used extensively in industry. The current study analyzed the effects of alloying elements, especially the effect of minor element Si, on cyclic oxidation resistance. The behavior of oxide scale growth, scale spallation, subsurface changes, and chromium interdiffusion in the alloy were analyzed in detail. A novel model was developed in the current study to predict the life-time during cyclic oxidation by simulating oxidation kinetics and chromium interdiffusion in the subsurface of chromia-forming alloys.

Bingtao Li

2003-08-05

158

Universal Behavior of a Cyclic Oxidation Model  

NASA Technical Reports Server (NTRS)

A mathematical model has been generated to represent the iterative, discrete growth and spallation processes associated with cyclic oxidation. Parabolic growth kinetics (k(sub p)) over and a constant spall area (F(sub A)) were assumed, with spalling occurring interfacially at the thickest regions of the scale. Although most models require numerical techniques, the regularity and simplicity of this progression permitted an approximation by algebraic expressions. Normalization could now be performed to reflect all parametric effects, and a universal cyclic oxidation response was generated: W(sub u) = 1/2 {3J(sub u)(sup 1/2)+ J(sub u)(sup 3/2)} where W, is weight change normalized by the maximum and J(sub u) is the cycle number normalized by the number to reach maximum. Similarly, the total amount of metal consumed was represented by a single normalized curve. The factor [(S(sub c)-l)(raised dot)sqrt(F(sub A)k(sub p)DELTAt)] was identified as a general figure of merit, where S(sub c) is the mass ratio of oxide to oxygen and DELTAt is the cycle duration. A cyclic oxidation failure map was constructed, in normalized k(sub p)-F(sub A) space, as defined by the locus of points corresponding to a critical amount of metal consumption in a given time. All three constructions describe behavior for every value of growth rate, spall fraction, and cycle duration by means of single curves, but with two branches corresponding to the times before and after steady state is achieved.

Smialek, James L.

2003-01-01

159

Antioxidants Block Cyclic Loading Induced Chondrocyte Death  

PubMed Central

Articular cartilage in congruous joints benefits from the moderate stresses and strains associated with normal cyclic loading. However, loading of joints with surface incongruities can lead to local stress and strain elevation at step-off sites where cartilage is not fully buttressed by surrounding matrix. Excessive stresses and strains predicted to occur at such sites may induce apoptosis, a process thought to promote cartilage degeneration and osteoarthritis (OA) through chondrocyte attrition. We hypothesized that the induction of apoptosis is mediated by oxidants, and that antioxidants can reduce elevated stress-induced chondrocyte attrition. To test this we exposed cylindrical cartilage explants from human articular cartilage to radially unconfined cyclic axial compression (3600 cycles, 1 Hz, 50% duty cycle) using two different physiologic loads (2MPa and 5 MPa). We found that 30% of chondrocytes in the superficial zone died within 24 hours of exposure to loading with 5 MPa axial compression, whereas mortality was limited to less than 15% with 2 MPa axial compression. Similarly, lactate accumulation in the medium was suppressed by compression with 5 MPa, but not 2 MPa. Approximately 80% of cell death induced by 5 MPa compression was blocked by pre-incubation of the explants in a variety of anti-oxidants including vitamin E, n-acetyl cysteine (NAC), and a superoxide dismutase mimetic (SOD). SOD and NAC also prevented the suppression of lactate secretion after 5 MPa compression. These observations support the hypothesis that the harmful effects of abnormal cyclic loading are mediated by oxidants and suggest that treatments to prevent OA may include methods of minimizing oxidative damage to chondrocytes. PMID:17907423

Beecher, BR; Martin, JA; Pedersen, DR; Heiner, AD; Buckwalter, JA

2007-01-01

160

Cyclic peptides as inhibitors of amyloid fibrillation.  

PubMed

Many neurodegenerative diseases, like Parkinson's, Alzheimer's, or Huntington's disease, occur as a result of amyloid protein fibril formation and cell death induced by this process. Cyclic peptides (CPs) and their derivatives form a new class of powerful inhibitors that prevent amyloid fibrillation and decrease the cytotoxicity of aggregates. The strategies for designing CPs are described, with respect to their amino acid sequence and/or conformational similarity to amyloid fibrils. The implications of CPs for the study and possible treatment of amyloid-related diseases are discussed. PMID:24478167

Luo, Jinghui; Abrahams, Jan Pieter

2014-02-24

161

Cyclical Behaviour in Early Universe Cosmologies  

E-print Network

We study early universe cosmologies derived from a scalar-tensor action containing cosmological constant terms and massless fields. The governing equations can be written as a dynamical system which contains no past or future asymptotic equilibrium states (i.e. no sources nor sinks). This leads to dynamics with very interesting mathematical behaviour such as the existence of heteroclinic cycles. The corresponding cosmologies have novel characteristics, including cyclical and bouncing behaviour possibly indicating chaos. We discuss the connection between these early universe cosmologies and those derived from the low-energy string effective action.

Andrew P. Billyard; Alan A. Coley; James E. Lidsey

2000-05-26

162

Cyclic Dinucleotides and the Innate Immune Response  

PubMed Central

Cyclic dinucleotides (CDNs) have been previously recognized as important secondary signaling molecules in bacteria and, more recently, in mammalian cells. In the former case, they represent secondary messengers affecting numerous responses of the prokaryotic cell, whereas in the latter, they act as agonists of the innate immune response. Remarkable new discoveries have linked these two patterns of utilization of CDNs as secondary messengers and have revealed unexpected influences they likely had on shaping human genetic variation. This Review summarizes these recent insights and provides a perspective on future unanswered questions in this exciting field. PMID:23993090

Danilchanka, Olga; Mekalanos, John J.

2014-01-01

163

Minimax decoding of cyclic block codes  

NASA Technical Reports Server (NTRS)

A minimax decoding algorithm utilizing soft bit detection of an (n,k) cyclic block code is described which will permit the correction of up to n-k bit errors interspersed at random locations throughout the block. The decoding solution consists of: (1) identifying the ordered soft bit set and, (2) finding the minimum order solution to the resulting syndrome equations where the nonzero error vector components are constrained to be a subset of the soft bit set. An efficient implementation of the decoding operation is described. In essence, this algorithm focuses the correction capability of the code on those bit positions which have the lowest a posteriori probabilities of correct detection.

Greene, E. P.

1977-01-01

164

Linear Accelerator (LINAC)  

MedlinePLUS

... position doesn't vary from the original plan. Safety of the staff operating the linear accelerator is also important. The linear accelerator sits in a room with lead and concrete walls so that the ...

165

Improved plasma accelerator  

NASA Technical Reports Server (NTRS)

Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

Cheng, D. Y.

1971-01-01

166

Behavior of cyclic fatigue cracks in monolithic silicon nitride  

Microsoft Academic Search

Cyclic fatigue-crack propagation behavior in monolithic silicon nitride is characterized in light of current fatigue-crack growth models for ceramics toughened by grain-bridging mechanisms, with specific emphasis on the role of load ratio. Such models are based on diminished crack-tip shielding in the crack wave under cyclic loads due to frictional-wear degradation of the grain-bridging zone. The notion of cyclic crack

Christopher J. Gilbert; R. O. Ritchie; R. H. Dauskardt

1995-01-01

167

Unified constitutive modeling for proportional and nonproportional cyclic plasticity responses  

Microsoft Academic Search

Several features of cyclic plasticity, e.g. cyclic hardening\\/softening, ratcheting, relaxation, and their dependence on strain range, nonproportionality of loading, time, and temperature determine the stress-strain responses of materials under cyclic loading. Numerous efforts have been made in the past decades to characterize and model these responses. Many of these responses can be simulated reasonably by the existing constitutive models, but

Shree Krishna

2009-01-01

168

A study of cyclic pressuremeter testing for offshore applications  

E-print Network

with reasonable accuracy for any given pressure by multiplying the strain by a constant which depends only on the number of cycles. The use of the results is discussed briefly, especially with respect to the design of piles subjected to cyclic lateral loads... Data Corrections Cyclic Pressuremeter Data 39 44 45 CHAPTER VI. ANALYSIS OF RESULTS 47 Introduction . ~ ~ . ~ ~ ~ . ~ ~ ~ ~ ~ ~ ~ Discussion of Cyclic Loads Shear Modulus Degradation Deformation Model and Shear Modulus Model Factors...

Riner, Kenneth Byard

2012-06-07

169

Cyclical Parthenogenesis in Daphnia : Sexual Versus Asexual Reproduction  

Microsoft Academic Search

\\u000a In the current chapter, we discuss the peculiar but successful reproduction mode of cyclical parthenogenesis, using the cladoceran\\u000a genus Daphnia as a model. We first focus on the cyclically parthenogenetic life cycle of Daphnia, the phylogenetic backgrounds of this reproduction mode, and how cyclical parthenogenesis impacts the genetic structure of\\u000a Daphnia populations. Further, we discuss the advantages of sex. Finally,

Ellen Decaestecker; Luc De Meester; Joachim Mergeay

170

Cyclical components of local rainfall data  

NASA Astrophysics Data System (ADS)

This paper reports on the use of a comparatively simple statistical methodology to study local short time series rainfall data. The objective is to help in agricultural planning, by diminishing the risks associated with some uncertainties affecting this business activity.The analysis starts by assuming a model of unobservable components, trend, cycle, seasonal and irregular, that is well known in many areas of application. When series are in the realm of business and economics, the statistical methods popularized by the US Census Bureau US National Bureau of Economic Research are used for seasonal and cyclical estimation, respectively. The flexibility of these methods makes them good candidates to be applied in the meteorological context, and this is done in this paper for a selection of monthly rainfall time series.Use of the results to help in analysing and forecasting cyclical components is emphasized. The results are interesting. An agricultural entrepreneur, or a group of them located in a single geographical region, will profit by systematically collecting information (monthly in our work) about rainfall, and adopting the scheme of analysis described in this paper.

Mentz, R. P.; D'Urso, M. A.; Jarma, N. M.; Mentz, G. B.

2000-02-01

171

Effects of Cyclic Loading on Gravel  

NASA Astrophysics Data System (ADS)

The effects of a large number of load repetitions on gravel are discussed based on experimental evidences. To this purpose the results of several triaxial tests carried out on a coarse grained soil, artificially reconstituted at different prescribed levels of density, are reported and compared. The tests reproduce a broad variety of possible field conditions, being performed at different mean effective stresses, by applying sequences of load-unload repetitions, different by number of repetitions and amplitudes of cycles. The analysis of the experimental results has been conducted by focusing the attention on the plastic components of strain, calculated by scaling the non negligible elastic components from the measured ones. A theory for the interpretation of monotonic test results is first briefly presented to form the basis of the analysis of the cyclic test results. This last is referred to the evolution of the stress-strain relationships along with load repetitions, and particularly to the accumulation of distortional and volumetric strains and to the effects of previous cyclic loading on subsequent soil response.

Modoni, Giuseppe; Dan, Le Quang; Koseki, Junichi; Maqbool, Sajjad

172

Backstress, The Bauschinger Effect, and Cyclic Deformation  

SciTech Connect

Backstresses or long range internal stresses (LRIS) in the past have been suggested by many to exist in plastically deformed crystalline materials. Elevated stresses can be present in regions of elevated dislocation density or dislocation heterogeneities in the deformed microstructures. The heterogeneities include edge dislocation dipole bundles (veins) and the edge dipole walls of persistent slip bands (PSBs) in cyclically deformed materials and cell and subgrain walls in monotonically deformed materials. The existence of long range internal stress is especially important for the understanding of cyclic deformation and also monotonic deformation. X-ray microbeam diffraction experiments performed by the authors using synchrotron x-ray microbeams determined the elastic strains within the cell interiors. The studies were performed using, oriented, monotonically deformed Cu single crystals. The results demonstrate that small long-range internal stresses are present in cell interiors. These LRIS vary substantially from cell to cell as 0% to 50% of the applied stress. The results are related to the Bauschinger effect, often explained in terms of LRIS.

Kassner, Michael E. [University of Southern California; Geantil, P. [University of Southern California; Levine, Lyle E. [National Institute of Standards and Technology (NIST); Larson, Ben C [ORNL

2008-10-01

173

Backstress, the Bauschinger Effect and Cyclic Deformation  

SciTech Connect

Backstresses or long range internal stresses (LRIS) in the past have been suggested by many to exist in plastically deformed crystalline materials. Elevated stresses can be present in regions of elevated dislocation density or dislocation heterogeneities in the deformed microstructures. The heterogeneities include edge dislocation dipole bundles (veins) and the edge dipole walls of persistent slip bands (PSBs) in cyclically deformed materials and cell and subgrain walls in monotonically deformed materials. The existence of long range internal stress is especially important for the understanding of cyclic deformation and also monotonic deformation. X-ray microbeam diffraction experiments performed by the authors using synchrotron x-ray microbeams determined the elastic strains within the cell interiors. The studies were performed using, oriented, monotonically deformed Cu single crystals. The results demonstrate that small long-range internal stresses are present in cell interiors. These LRIS vary substantially from cell to cell as 0 % to 50 % of the applied stress. The results are related to the Bauschinger effect, often explained in terms of LRIS.

Kassner, Michael E. [University of Southern California; Geantil, P. [University of Southern California; Levine, Lyle E. [National Institute of Standards and Technology (NIST); Larson, Ben C [ORNL

2009-01-01

174

Angular Acceleration without Torque?  

ERIC Educational Resources Information Center

Hardly. Just as Robert Johns qualitatively describes angular acceleration by an internal force in his article "Acceleration Without Force?" here we will extend the discussion to consider angular acceleration by an internal torque. As we will see, this internal torque is due to an internal force acting at a distance from an instantaneous center.

Kaufman, Richard D.

2012-01-01

175

Sustained linear acceleration  

NASA Technical Reports Server (NTRS)

The subjective effects of sustained acceleration are discussed, including positive, negative, forward, backward, and lateral acceleration effects. Physiological effects, such as retinal and visual response, unconsciousness and cerebral function, pulmonary response, and renal output, are studied. Human tolerance and performance under sustained acceleration are ascertained.

Fraser, T. M.

1973-01-01

176

Direction of Acceleration  

NSDL National Science Digital Library

In this short lab, students observe the movement of an air bubble in a small level, attached to a toy truck, as it is moved from a stop, to a steady speed and back to a stop. This gives a visual to the concepts positive acceleration, zero acceleration and negative acceleration.

Mary Spaulding, Clearbrook-Gonvick Public School, Clearbrook Minnesota, based on an original activity from Physics Principles and Problems (1995) page 75.

177

Acceleration: It's Elementary  

ERIC Educational Resources Information Center

Acceleration is one tool for providing high-ability students the opportunity to learn something new every day. Some people talk about acceleration as taking a student out of step. In actuality, what one is doing is putting a student in step with the right curriculum. Whole-grade acceleration, also called grade-skipping, usually happens between

Willis, Mariam

2012-01-01

178

KEKB accelerator control system  

Microsoft Academic Search

The KEKB accelerator control system including a control computer system, a timing distribution system, and a safety control system are described. KEKB accelerators were installed in the same tunnel where the TRISTAN accelerator was. There were some constraints due to the reused equipment. The control system is based on Experimental Physics and Industrial Control System (EPICS). In order to reduce

Nobumasa Akasaka; Atsuyoshi Akiyama; Sakae Araki; Kazuro Furukawa; Tadahiko Katoh; Takashi Kawamoto; Ichitaka Komada; Kikuo Kudo; Takashi Naito; Tatsuro Nakamura; Jun-Ichi Odagiri; Yukiyoshi Ohnishi; Masayuki Sato; Masaaki Suetake; Shigeru Takeda; Yasunori Takeuchi; Noboru Yamamoto; Masakazu Yoshioka; Eji Kikutani

2003-01-01

179

Acceleration gradient of a plasma wakefield accelerator  

NASA Astrophysics Data System (ADS)

The phase velocity of the wakefield waves is identical to the electron beam velocity. A theoretical analysis indicates that the acceleration gradient of the wakefield accelerator normalized by the wave breaking amplitude is K0(?)/K1(?), where K0(?) and K1(?) are the modified Bessel functions of the second kind of order zero and one, respectively and ? is the beam parameter representing the beam intensity. It is also shown that the beam density must be considerably higher than the diffuse plasma density for the large radial velocity of plasma electrons that are required for a high acceleration gradient.

Uhm, Han S.

2008-02-01

180

21 CFR 862.1230 - Cyclic AMP test system.  

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems 862.1230 Cyclic AMP test system. (a)...

2014-04-01

181

Safety Discrete Event Models for Holonic Cyclic Manufacturing Systems  

NASA Astrophysics Data System (ADS)

In this paper the expression holonic cyclic manufacturing systems refers to complex assembly/disassembly systems or fork/join systems, kanban systems, and in general, to any discrete event system that transforms raw material and/or components into products. Such a system is said to be cyclic if it provides the same sequence of products indefinitely. This paper considers the scheduling of holonic cyclic manufacturing systems and describes a new approach using Petri nets formalism. We propose an approach to frame the optimum schedule of holonic cyclic manufacturing systems in order to maximize the throughput while minimize the work in process. We also propose an algorithm to verify the optimum schedule.

Ciufudean, Calin; Filote, Constantin

182

Compact Plasma Accelerator  

NASA Technical Reports Server (NTRS)

A plasma accelerator has been conceived for both material-processing and spacecraft-propulsion applications. This accelerator generates and accelerates ions within a very small volume. Because of its compactness, this accelerator could be nearly ideal for primary or station-keeping propulsion for spacecraft having masses between 1 and 20 kg. Because this accelerator is designed to generate beams of ions having energies between 50 and 200 eV, it could also be used for surface modification or activation of thin films.

Foster, John E.

2004-01-01

183

Notes on Laser Acceleration  

SciTech Connect

This note intends to motivate our effort toward the advent of new methods of particle acceleration, utilizing the fast rising laser technology. By illustrating the underlying principles in an intuitive manner and thus less jargon-clad fashion, we seek a direction in which we shall be able to properly control and harness the promise of laser acceleration. First we review the idea behind the laser wakefield. We then go on to examine ion acceleration by laser. We examine the sheath acceleration in particular and look for the future direction that allows orderly acceleration of ions in high energies.

Tajima, T. [Kansai Photon Science Institute and Photon Medical Research Center Japan Atomic Energy Agency Kyoto, 619-0215 (Japan)

2008-06-24

184

Virtual Accelerator for Accelerator Optics Improvement  

SciTech Connect

Through determination of all quadrupole strengths and sextupole feed-downs by fitting quantities derivable from precision orbit measurement, one can establish a virtual accelerator that matches the real accelerator optics. These quantities (the phase advances, the Green's functions, and the coupling ellipses tilt angles and axis ratios) are obtained by analyzing turn-by-turn Beam Position Monitor (BPM) data with a model-independent analysis (MIA). Instead of trying to identify magnet errors, a limited number of quadrupoles are chosen for optimized strength adjustment to improve the virtual accelerator optics and then applied to the real accelerator accordingly. These processes have been successfully applied to PEP-II rings for beta beating fixes, phase and working tune adjustments, and coupling reduction to improve PEP-II luminosity.

Yan, Y.T.; Cai, Y.; Decker, F-J.; Ecklund, S.; Irwin, J.; Seeman, J.; Sillivan, M.; Turner, J.; Wienands, U.; /SLAC

2005-09-30

185

Accelerated Life Testing Model for a Generalized Birnbaum-Saunders Distribution  

E-print Network

of the distribution, is the failure threshold level, is the standard deviation of the failure time dataAccelerated Life Testing Model for a Generalized Birnbaum-Saunders Distribution Yao Cheng and E. A@gmail.com, elsayed@rci.rutgers.edu Abstract--Fatigue failures caused by cyclic stresses are commonly

Boyer, Edmond

186

Deactivation of accelerated engine-aged and field-aged Fezeolite SCR catalysts  

Microsoft Academic Search

A single-cylinder diesel engine with an emissions control system diesel oxidation catalyst (DOC), Fezeolite selective catalytic reduction (SCR) catalyst, and diesel particulate filter (DPF) was used to perform accelerated thermal aging of the SCR catalyst. Cyclic aging is performed at SCR inlet temperatures of 650, 750 and 850C for up to 50 aging cycles. To assess the validity

Todd J. Toops; Ke Nguyen; Adam L. Foster; Bruce G. Bunting; Nathan A. Ottinger; Josh A. Pihl; Edward W. Hagaman; Jian Jiao

2010-01-01

187

Perturbation calculation of charged-particle motion and phase-free acceleration in electromagnetic fields  

Microsoft Academic Search

The cyclic motion of charged particles in azimuth-independent electromagnetic fields varying in time has been studied in first-order perturbation theory. It is shown that the addition of an azimuth-dependent azimuthal electric RF field changing sign at the stationary orbit radius combined with radial oscillations, allows a second-order phase-free acceleration. Possible applications are discussed.

H. Daniel

1985-01-01

188

High brightness electron accelerator  

SciTech Connect

A compact high brightness linear accelerator is provided for use, e.g., in a free electron laser. The accelerator has a first plurality of acclerating cavities having end walls with four coupling slots for accelerating electrons to high velocities in the absence of quadrupole fields. A second plurality of cavities receives the high velocity electrons for further acceleration, where each of the second cavities has end walls with two coupling slots for acceleration in the absence of dipole fields. The accelerator also includes a first cavity with an extended length to provide for phase matching the electron beam along the accelerating cavities. A solenoid is provided about the photocathode that emits the electrons, where the solenoid is configured to provide a substantially uniform magnetic field over the photocathode surface to minimize emittance of the electrons as the electrons enter the first cavity.

Sheffield, R.L.; Carlsten, B.E.; Young, L.M.

1992-12-31

189

High brightness electron accelerator  

DOEpatents

A compact high brightness linear accelerator is provided for use, e.g., in a free electron laser. The accelerator has a first plurality of acclerating cavities having end walls with four coupling slots for accelerating electrons to high velocities in the absence of quadrupole fields. A second plurality of cavities receives the high velocity electrons for further acceleration, where each of the second cavities has end walls with two coupling slots for acceleration in the absence of dipole fields. The accelerator also includes a first cavity with an extended length to provide for phase matching the electron beam along the accelerating cavities. A solenoid is provided about the photocathode that emits the electons, where the solenoid is configured to provide a substantially uniform magnetic field over the photocathode surface to minimize emittance of the electons as the electrons enter the first cavity.

Sheffield, Richard L. (Los Alamos, NM); Carlsten, Bruce E. (Los Alamos, NM); Young, Lloyd M. (Los Alamos, NM)

1994-01-01

190

Signal transduction for Schistocerca gregaria ion transport peptide is mediated via both cyclic AMP and cyclic GMP.  

PubMed

The second messengers involved in the signal transduction for Schistocerca gregaria, ion transport peptide (Schgr-ITP) that regulates ion and fluid transport across the ileum of the desert locust S. gregaria, were measured using competitive enzyme-linked immunosorbent assays (ELISAs). Synthetic Schgr-ITP elevates intracellular levels of both cyclic AMP and cyclic GMP, measured over a 15 min period in the presence of 3-isobutyl-1-methylxanthine, in a dose-dependent manner. Furthermore, crude corpora cardiaca (CC) extracts elevate intracellular cyclic AMP levels 2-fold greater than Schgr-ITP, suggesting that factors present in the CC, other than Schgr-ITP, also act via this second messenger. These results suggest that the interaction of Schgr-ITP with two separate receptors, most likely a G-protein coupled receptor and a membrane bound guanylate cyclase, elevates intracellular levels of cyclic AMP and cyclic GMP to regulate ion and fluid transport across the locust ileum. Cyclic AMP stimulates Cl(-), K(+) and Na(+) reabsorption, whereas secretion of H(+) into the lumen of the ileum is most likely mediated via cyclic GMP. Cyclic GMP also stimulates Cl(-) uptake in a similar manner to cyclic AMP. The measurement of tissue (central nervous system) levels of Schgr-ITP using an indirect ELISA confirms that the peptide is only present in the locust brain and the CC. The amounts present are greatest in the CC, where the peptide is presumably stored for release into the hemolymph when locusts feed. PMID:23147644

Audsley, Neil; Jensen, Derek; Schooley, David A

2013-03-01

191

An introduction to acceleration mechanisms  

SciTech Connect

This paper discusses the acceleration of charged particles by electromagnetic fields, i.e., by fields that are produced by the motion of other charged particles driven by some power source. The mechanisms that are discussed include: Ponderamotive Forces, Acceleration, Plasma Beat Wave Acceleration, Inverse Free Electron Laser Acceleration, Inverse Cerenkov Acceleration, Gravity Acceleration, 2D Linac Acceleration and Conventional Iris Loaded Linac Structure Acceleration. (LSP)

Palmer, R.B.

1987-05-01

192

Cyclic 7-edge-cuts in fullerene graphs Frantisek Kardosa  

E-print Network

Cyclic 7-edge-cuts in fullerene graphs Frantisek Kardosa , Matjaz Krncb , Borut Luzarb and Riste 19, 1111 Ljubljana, Slovenia {matjaz.krnc, borut.luzar}@gmail.com Abstract A fullerene graph-cuts of fullerene graphs of sizes up to 6 is known. In the paper we study cyclic 7-edge connectivity of fullerene

Paris-Sud XI, Université de

193

MICROWAVE-ASSISTED PREPARATION OF CYCLIC UREAS FROM DIAMINES  

EPA Science Inventory

Rajender S. Varma* and Yong-Jin Kim Cyclic ureas are useful intermediates for a variety of pharmaceuticals and pesticides. One of the attractive approaches for the synthesis of cyclic ureas uses condensation of diamines with urea as a carbonyl source under dynamic evacuation. ...

194

Cyclic plasticity of nickel single crystals at elevated temperatures  

Microsoft Academic Search

Single slip oriented nickel crystals have been cyclically deformed at deformation temperatures between 293 K and 900 K until saturation of the stress amplitude. Persistent slip bands (PSBs) with a typical ladder-like dislocation substructure occur at temperatures up to 800 K. At 600 K and 750 K the measured cyclic stress-strain curves (CSSCs) exhibit extended ranges in which the saturation

J. Bretschneider; C. Holste; B. Tippelt

1997-01-01

195

Model for fracture toughness alteration due to cyclic loading  

Microsoft Academic Search

A new model that is capable of predicting and explaining the effect of cyclic loading on the apparent fracture toughness of materials was developed. The model combines macroscopic fracture criteria with the assumption that transient flow properties of material in the cyclic plastic zone can be simulated by those of macroscopic low cycle fatigue specimens, tested in reversed strain control.

I. Roman; Kanji Ono

1982-01-01

196

Cyclic Motion of the Soft Palate in Feeding  

Microsoft Academic Search

The soft palate moves rhythmically during feeding, but the timing and frequency of this motion are not known. We tested the hypothesis that cyclic soft palate motion is temporally linked to cyclic jaw movement. Nine healthy, asymptomatic human subjects with normal dentition ate solid food coated with barium. Videofluorographic recordings showed that rhythmic motions of the soft palate during mastication

K. Matsuo; K. M. Hiiemae; J. B. Palmer

2005-01-01

197

Rescue of the Hypoplastic Lung by Prenatal Cyclical Strain  

Microsoft Academic Search

We determined the effects of sustained and cyclical prenatal me- chanical strain on the hypoplastic lung of the ovine model of con- genital diaphragmatic hernia. Over a period of 4 weeks in late gestation, repeated cyclical tracheal occlusion for 23 hours with 1-hour release stimulated minimal growth, but promoted matura- tion with the development of a saccular lung. In contrast,

Scott M. Nelson; Constantinos A. Hajivassiliou; Graham Haddock; Alan D. Cameron; Lindsay Robertson; Richard E. Olver; Robert Hume

2005-01-01

198

Cyclic deformation and fatigue behaviour of ion-nitrided steel  

Microsoft Academic Search

The effect of the ion-nitriding process on the axial fatigue and deformation behaviour of SAE 1045 steel was investigated using smooth specimens at room temperature. Both monotonic and cyclic deformation responses of the ion-nitrided specimens are evaluated and compared with those of the core and case materials. A composite model is used to predict the stable cyclic response of the

J. Wan; A. Fatemi

1995-01-01

199

Reproductive changes in a cyclic population of snowshoe hares  

E-print Network

Abstract: Reproductive output was estimated for a cyclic population of snowshoe hares (Lepus americanusIntroduction The causes of cyclic fluctuations in density of snowshoe hare (Lepus americanus) populations have been rendement de la reproduction a été estimé chez une population cyclique de Lièvres d'Amérique (Lepus

Krebs, Charles J.

200

CYCLIC GENETIC ALGORITHMS FOR THE LOCOMOTION OF HEXAPOD ROBOTS  

Microsoft Academic Search

Robotics control problems, such as gait coordination, require sequential solutions where a series of actions is continually repeated. Genetic Algorithms that do parameter optimization have not been widely applied to these cyclic sequential decision problems; although some form of evolutionary computation would be well suited for the adaptability required. In this paper we introduce Cyclic Genetic Algorithms, which were developed

GARY B. PARKER; GREGORY J. E. RAWLINS

1996-01-01

201

EVOLVING HEXAPOD GAITS USING A CYCLIC GENETIC ALGORITHM  

E-print Network

EVOLVING HEXAPOD GAITS USING A CYCLIC GENETIC ALGORITHM GARY B. PARKER, DAVID W. BRAUN, AND INGO is an integral part of a legged robot control. Hexapod gaits require the coordination of the simultaneous. KEYWORDS: genetic, cyclic, robot, hexapod, control. INTRODUCTION Autonomous hexapod robots can be useful

Parker, Gary B.

202

Cyclic Pure Greedy Algorithms for Recovering Compressively Sampled Sparse Signals  

E-print Network

Cyclic Pure Greedy Algorithms for Recovering Compressively Sampled Sparse Signals Bob L. Sturm 35042 Rennes Cedex France Email: remi.gribonval@inria.fr Abstract--The pure greedy algorithms matching problem by a cyclic application of the pure greedy algorithms matching pursuit (MP) [2], [5], [6

Paris-Sud XI, Université de

203

Modeling of cyclic mobility in saturated cohesionless soils  

Microsoft Academic Search

Cyclic mobility is exhibited by saturated medium to dense cohesionless soils during liquefaction, due to soil skeleton dilation at large shear strain excursions. This volume-shear coupling mechanism results in phases of significant regain in soil shear stiffness and strength, and limits the magnitude of cyclic shear deformations. Motivated by experimental observations, a plasticity model is developed for capturing the characteristics

Ahmed Elgamal; Zhaohui Yang; Ender Parra; Ahmed Ragheb

2003-01-01

204

The cyclic prefix of OFDM\\/DMT - an analysis  

Microsoft Academic Search

We address the impact of a too short cyclic prefix on multicarrier systems such as orthogonal frequency division multiplexing (OFDM) and discrete multitone (DMT). The main result is that the intersymbol interference (ISI) and intercarrier interference (ICI) may be spectrally concentrated and analytical expressions showing this are given. A practical implication is, e.g., that the cyclic prefix in some xDSL

Werner Henkel; Georg Taubock; Per Odling; Per Ola Borjesson; Niklas Petersson

2002-01-01

205

Enzymic formation of Glycerol 1:2-cyclic phosphate.  

PubMed Central

Glycerol 1:2-cyclic phosphate is released simultaneously with glycerophosphate when kidney glycerophosphinicocholine diesterase (EC 3.1.4.2) acts on glycerylphosphorylcholine and glycerylphosphorylethanolamine. The percentage of cyclic phosphate ester formed is increased at pH values below the optimum and is decreased when Mg2+ or Ca2+ is added to stimulate the reaction. PMID:182119

Clarke, N; Dawson, R M

1976-01-01

206

Building explicit induction schemas for cyclic induction reasoning  

E-print Network

Building explicit induction schemas for cyclic induction reasoning Sorin Stratulat Université de.stratulat@univ-lorraine.fr Abstract. In the setting of classical first-order logic with inductive predicates, two kinds of sequent-based induction reasoning are distin- guished: cyclic and structural. Proving their equivalence is of great the

Paris-Sud XI, Université de

207

Synthesis of Cyclic Guanidines via Pd-Catalyzed Alkene Carboamination  

PubMed Central

A new approach to the synthesis of substituted 5-membered cyclic guanidines is described. Palladium-catalyzed alkene carboamination reactions between acyclic N-allyl guanidines and aryl or alkenyl halides provide these products in good yield. This method allows access to a number of different cyclic guanidine derivatives in only two steps from readily available allylic amines. PMID:24147839

Zavesky, Blane P.; Babij, Nicholas R.; Fritz, Jonathan A.

2013-01-01

208

Cyclic hematopoiesis: the mechanism of cyclic neutropenia in grey collie dogs  

PubMed Central

Two grey collie dogs had regular cyclic fluctuations in the number of all formed elements of the blood. The period lengths for all elements for an individual dog were the same, but the pattern of fluctuation for each element was distinctive. Normal dogs lacked periodic fluctuations. The patterns of day-to-day variation in the normal dogs counts were consistent with a first-order autoregressive process of serial dependence (i.e., each observation of the series depends on the last preceding observation and no others). The grey collie counts showed the same pattern of serial dependence after the component of the over-all variability due to cyclic oscillation was removed. These data suggest that a defect of hematopoietic regulation at the stem cell level leads to periodic interruptions of production of all hematopoietic elements and accounts for the cycles seen in the peripheral blood counts. PMID:5054472

Dale, David C.; Alling, David W.; Wolff, Sheldon M.

1972-01-01

209

Convergence of cyclic and almost-cyclic learning with momentum for feedforward neural networks.  

PubMed

Two backpropagation algorithms with momentum for feedforward neural networks with a single hidden layer are considered. It is assumed that the training samples are supplied to the network in a cyclic or an almost-cyclic fashion in the learning procedure, i.e., in each training cycle, each sample of the training set is supplied in a fixed or a stochastic order respectively to the network exactly once. A restart strategy for the momentum is adopted such that the momentum coefficient is set to zero at the beginning of each training cycle. Corresponding weak and strong convergence results are then proved, indicating that the gradient of the error function goes to zero and the weight sequence goes to a fixed point, respectively. The convergence conditions on the learning rate, the momentum coefficient, and the activation functions are much relaxed compared with those of the existing results. PMID:21813357

Wang, Jian; Yang, Jie; Wu, Wei

2011-08-01

210

Cyclic-di-GMP and cyclic-di-AMP activate the NLRP3 inflammasome  

PubMed Central

The cyclic dinucleotides 3'-5'diadenylate (c-diAMP) and 3'-5' diguanylate (c-diGMP) are important bacterial second messengers that have recently been shown to stimulate the secretion of type I Interferons (IFN-Is) through the c-diGMP-binding protein MPYS/STING. Here, we show that physiologically relevant levels of cyclic dinucleotides also stimulate a robust secretion of IL-1? through the NLRP3 inflammasome. Intriguingly, this response is independent of MPYS/STING. Consistent with most NLRP3 inflammasome activators, the response to c-diGMP is dependent on the mobilization of potassium and calcium ions. However, in contrast to other NLRP3 inflammasome activators, this response is not associated with significant changes in mitochondrial potential or the generation of mitochondrial reactive oxygen species. Thus, cyclic dinucleotides activate the NLRP3 inflammasome through a unique pathway that could have evolved to detect pervasive bacterial pathogen-associated molecular patterns associated with intracellular infections. PMID:24008845

Abdul-Sater, Ali A; Tattoli, Ivan; Jin, Lei; Grajkowski, Andrzej; Levi, Assaf; Koller, Beverly H; Allen, Irving C; Beaucage, Serge L; Fitzgerald, Katherine A; Ting, Jenny P -Y; Cambier, John C; Girardin, Stephen E; Schindler, Christian

2013-01-01

211

Synergistic activation of insect cAMP-dependent protein kinase A (type II) by cyclicAMP and cyclicGMP  

E-print Network

honeybee regulatory subunit RII and phylogenetic comparison of the two cyclic nucleotide-binding sites Societies. Keywords: Insect; Protein kinase A; Regulatory subunit; Cyclic AMP; Cyclic cGMP; Nucleotide amino acids, interacts with the cyclic nucleotide [6,7]. The PBCs of the R subunits are highly conserved

Menzel, Randolf - Institut für Biologie

212

Uniformly accelerated black holes  

NASA Astrophysics Data System (ADS)

The static and stationary C metric are examined in a generic framework and their interpretations studied in some detail, especially those with two event horizons, one for the black hole and another for the acceleration. We find that (i) the spacetime of an accelerated static black hole is plagued by either conical singularities or a lack of smoothness and compactness of the black hole horizon, (ii) by using standard black hole thermodynamics we show that accelerated black holes have a higher Hawking temperature than Unruh temperature of the accelerated frame, and (iii) the usual upper bound on the product of the mass and acceleration parameters (<1/27) is just a coordinate artifact. The main results are extended to accelerated rotating black holes with no significant changes.

Letelier, Patricio S.; Oliveira, Samuel R.

2001-09-01

213

Optically pulsed electron accelerator  

DOEpatents

An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radiofrequency-powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

Fraser, J.S.; Sheffield, R.L.

1985-05-20

214

Space Acceleration Measurement System  

NASA Technical Reports Server (NTRS)

This training video, presented by the Lewis Research Center's Space Experiments Division, gives a background and detailed instructions for preparing the space acceleration measurement system (SAMS) for use. The SAMS measures, conditions, and records forces of low gravity accelerations, and is used to determine the effect of these forces on various experiments performed in microgravity. Inertial sensors are used to measure positive and negative acceleration over a specified frequency range. The video documents the SAMS' uses in different configurations during shuttle missions.

1993-01-01

215

G Accelerator Applications  

Microsoft Academic Search

This paper will review GEANT4 applications and extensions for accelerator studies, both as a general framework and for the simulation of specific accelerators. G4Beamline is a Geant4-based program intended to easily simulate many different aspects of beam-line design. G4Beamline implements accelerator components via an object-oriented ASCII input format. For instance, it allows the definition of a quadrupole magnet by its

Malcolm Ellis; Grahame Blair; Yagmur Torun; Tom Roberts

2006-01-01

216

Staged laser plasma accelerators  

NASA Astrophysics Data System (ADS)

We present current results on staged electron acceleration in the LOASIS program at the Lawrence Berkeley National Laboratory. The goal is to experimentally demonstrate laser driven electron acceleration in two stages, where each stage is driven by a separate laser pulse. This technology could provide the key to built compact laser driven accelerators which could potentially reach up to TeV in electron energy.

Sokollik, Thomas; Shiraishi, Satomi; Shaw, Brian; Gonsalves, Antony; Nakamura, Kei; van Tilborg, Jeroen; Esarey, Eric; Schroeder, Carl B.; Benedetti, Carlo; Toth, Csaba; Leemans, Wim

2012-12-01

217

Charged particle accelerator grating  

DOEpatents

A readily disposable and replaceable accelerator grating for a relativistic particle accelerator. The grating is formed for a plurality of liquid droplets that are directed in precisely positioned jet streams to periodically dispose rows of droplets along the borders of a predetermined particle beam path. A plurality of lasers are used to direct laser beams into the droplets, at predetermined angles, thereby to excite the droplets to support electromagnetic accelerating resonances on their surfaces. Those resonances operate to accelerate and focus particles moving along the beam path. As the droplets are distorted or destroyed by the incoming radiation, they are replaced at a predetermined frequency by other droplets supplied through the jet streams.

Palmer, Robert B. (Shoreham, NY)

1986-01-01

218

FFAGS for rapid acceleration  

NASA Astrophysics Data System (ADS)

When large transverse and longitudinal emittances are to be transported through a circular machine, extremely rapid acceleration holds the advantage that the beam becomes immune to nonlinear resonances because there is insufficient time for amplitudes to build up. Uncooled muon beams exhibit large emittances and require fast acceleration to avoid decay losses and would benefit from this style of acceleration. The approach here employs a fixed-field alternating gradient or FFAG magnet structure and a fixed-frequency acceleration system. Acceptance is enhanced by the use only of linear lattice elements, and fixed-frequency rf enables the use of cavities with large shunt resistance and quality factor.

Johnstone, C.; Koscielniak, S.

2003-05-01

219

Accelerator-based BNCT.  

PubMed

The activity in accelerator development for accelerator-based BNCT (AB-BNCT) both worldwide and in Argentina is described. Projects in Russia, UK, Italy, Japan, Israel, and Argentina to develop AB-BNCT around different types of accelerators are briefly presented. In particular, the present status and recent progress of the Argentine project will be reviewed. The topics will cover: intense ion sources, accelerator tubes, transport of intense beams, beam diagnostics, the (9)Be(d,n) reaction as a possible neutron source, Beam Shaping Assemblies (BSA), a treatment room, and treatment planning in realistic cases. PMID:24365468

Kreiner, A J; Baldo, M; Bergueiro, J R; Cartelli, D; Castell, W; Thatar Vento, V; Gomez Asoia, J; Mercuri, D; Padulo, J; Suarez Sandin, J C; Erhardt, J; Kesque, J M; Valda, A A; Debray, M E; Somacal, H R; Igarzabal, M; Minsky, D M; Herrera, M S; Capoulat, M E; Gonzalez, S J; del Grosso, M F; Gagetti, L; Suarez Anzorena, M; Gun, M; Carranza, O

2014-06-01

220

Android Acceleration Application  

NSDL National Science Digital Library

In the first of two sequential lessons, students create mobile apps that collect data from an Android device's accelerometer and then store that data to a database. This lesson provides practice with MIT's App Inventor software and culminates with students writing their own apps for measuring acceleration. In the second lesson, students are given an app for an Android device, which measures acceleration. They investigate acceleration by collecting acceleration vs. time data using the accelerometer of a sliding Android device. Then they use the data to create velocity vs. time graphs and approximate the maximum velocity of the device.

IMPART RET Program, College of Information Science & Technology,

221

Accelerators and Nobel Laureates  

NSDL National Science Digital Library

This online article written by Sven Kullander at the Nobel e-Museum discusses the importance of particle accelerators to physics in a historical context. After studying their basic operatation, users can then learn about the many accelerator inventions and their assistance in various discoveries such as x-rays and electrons. The website provides links to descriptions of the many Nobel Prize winners who have utilized accelerators in their important work. Users can view images of the large accelerators from all over the world including the United Kingdom, Sweden, and the United State.

Kullander, Sven

222

Cyclic environmental testing of electrochromic window devices  

Microsoft Academic Search

We report on a systematic study of the factors affecting the degradation of prototype electrochromic (EC) windows. Our research activities include accelerated lifetime testing, activation analysis studies (AAS), and interfacial analysis studies. EC windows made by several different US companies were subjected to alternate coloring and bleaching voltage cycles while exposed to simulated 1.2-sun UV irradiance in a temperature-controlled environmental

Se-Hee Lee; C Edwin Tracy; Gary Jorgensen; J Roland Pitts; Satyan K Deb

2001-01-01

223

Accelerators, Beams And Physical Review Special Topics - Accelerators And Beams  

SciTech Connect

Accelerator science and technology have evolved as accelerators became larger and important to a broad range of science. Physical Review Special Topics - Accelerators and Beams was established to serve the accelerator community as a timely, widely circulated, international journal covering the full breadth of accelerators and beams. The history of the journal and the innovations associated with it are reviewed.

Siemann, R.H.; /SLAC

2011-10-24

224

Angular velocities, angular accelerations, and coriolis accelerations  

NASA Technical Reports Server (NTRS)

Weightlessness, rotating environment, and mathematical analysis of Coriolis acceleration is described for man's biological effective force environments. Effects on the vestibular system are summarized, including the end organs, functional neurology, and input-output relations. Ground-based studies in preparation for space missions are examined, including functional tests, provocative tests, adaptive capacity tests, simulation studies, and antimotion sickness.

Graybiel, A.

1975-01-01

225

Accelerators (4/5)  

ScienceCinema

1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

None

2011-10-06

226

Accelerators (5/5)  

ScienceCinema

1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

None

2011-10-06

227

Piezoelectric angular acceleration sensor  

Microsoft Academic Search

This paper deals with a piezoelectric angular acceleration sensor, which might be proposed by us, first, as a new concept of the sensor to detect a rotational motion only. In the first part of this paper are dealt with some concrete constructions of this new concept of angular acceleration sensor, composed of piezoelectric transducers. The second part contains their basic

Y. Tomikawa; S. Okada

2003-01-01

228

Ion Induction Accelerators  

NASA Astrophysics Data System (ADS)

The description of beams in RF and induction accelerators share many common features. Likewise, there is considerable commonality between electron induction accelerators (see Chap. 7) and ion induction accelerators. However, in contrast to electron induction accelerators, there are fewer ion induction accelerators that have been operated as application-driven user facilities. Ion induction accelerators are envisioned for applications (see Chap. 10) such as Heavy Ion Fusion (HIF), High Energy Density Physics (HEDP), and spallation neutron sources. Most ion induction accelerators constructed to date have been limited scale facilities built for feasibility studies for HIF and HEDP where a large numbers of ions are required on target in short pulses. Because ions are typically non-relativistic or weakly relativistic in much of the machine, space-charge effects can be of crucial importance. This contrasts the situation with electron machines, which are usually strongly relativistic leading to weaker transverse space-charge effects and simplified longitudinal dynamics. Similarly, the bunch structure of ion induction accelerators relative to RF machines results in significant differences in the longitudinal physics.

Barnard, John J.; Horioka, Kazuhiko

229

Accelerators (4/5)  

SciTech Connect

1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

None

2009-07-08

230

Accelerators (3/5)  

SciTech Connect

1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

None

2009-07-07

231

Accelerators (5/5)  

SciTech Connect

1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

None

2009-07-09

232

Neutrino physics at accelerators  

E-print Network

Present and future neutrino experiments at accelerators are mainly concerned with understanding the neutrino oscillation phenomenon and its implications. Here a brief account of neutrino oscillations is given together with a description of the supporting data. Some current and planned accelerator neutrino experiments are also explained.

Enrique Fernandez

2006-07-16

233

Accelerators Beyond The Tevatron?  

SciTech Connect

Following the successful operation of the Fermilab superconducting accelerator three new higher energy accelerators were planned. They were the UNK in the Soviet Union, the LHC in Europe, and the SSC in the United States. All were expected to start producing physics about 1995. They did not. Why?.

Lach, Joseph [Fermi National Accelerator Laboratory, P.O Box 500, Batavia Illinois (United States)

2010-07-29

234

Accelerators (3/5)  

ScienceCinema

1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

None

2011-10-06

235

Microscale acceleration history discriminators  

DOEpatents

A new class of micromechanical acceleration history discriminators is claimed. These discriminators allow the precise differentiation of a wide range of acceleration-time histories, thereby allowing adaptive events to be triggered in response to the severity (or lack thereof) of an external environment. Such devices have applications in airbag activation, and other safety and surety applications.

Polosky, Marc A. (Albuquerque, NM); Plummer, David W. (Albuquerque, NM)

2002-01-01

236

Uniformly accelerated black holes  

Microsoft Academic Search

The static and stationary C metric are examined in a generic framework and their interpretations studied in some detail, especially those with two event horizons, one for the black hole and another for the acceleration. We find that (i) the spacetime of an accelerated static black hole is plagued by either conical singularities or a lack of smoothness and compactness

Patricio S. Letelier; Samuel R. Oliveira

2001-01-01

237

Effect of Cyclic Deformation on Magnetorheological Elastomers  

NASA Astrophysics Data System (ADS)

Fatigue properties of magnetorheological elastomer (MRE) samples were investigated based on cis-polybutadiene rubber by using a fatigue test machine. Three MRE samples with iron particles mass fraction of 60%, 70%, and 80% were fabricated, and their properties dependence of three strain amplitudes (50%, 75%, and 100%) were measured. The absolute magnetorheological (MR) effect, storage modulus, and loss modulus of MRE samples after fatigue were evaluated by a modified dynamic mechanical analyzer. The results revealed that MR effect, storage modulus, and loss modulus of MREs containing 80% iron particles depended strongly on the strain amplitudes and the number of cycles, while storage modulus and loss modulus of MREs containing 70% iron particles also depended on the strain amplitudes and the number of cycles but not as strongly as sample which contains 80% iron particles, but the properties of MREs containing 60% iron particles after cyclic deformation were almost independent of the fatigued conditions. In order to investigate the fatigue mechanism of MREs, the sample was carried out with a quasi-static tensile testing and its surface morphology during testing was observed in situ by scanning electron microscopy.

Zhang, Wei; Gong, Xing-long; Sun, Tao-lin; Fan, Yan-ceng; Jiang, Wan-quan

2010-04-01

238

A low-power arcjet cyclic lifetest  

NASA Technical Reports Server (NTRS)

A cyclic lifetest of a low power dc arcjet thruster using a hydrogen/nitrogen propellant mixture simulating hydrazine is currently in progress. Over 300 hr of operation have been accumulated to date in 2 hr duty cycles at a power level of about 1.15 kW, approximating that available on commercial communications satellites. A burn-in period was carried out before consistent operation was attained. After this period, the arcjet operated in a very stable fashion from cycle to cycle. At the beginning of each cycle, there was a brief starting transient followed by a rapid rise to a steady-state voltage. The steady-state voltage increased by about 5 V over the first 95 cycles. After this, it increased by only 1 V through the remainder of the test. Thrust measurements taken before the life test and again after the completion of the 144th cycle showed that both thrust, specific impulse, and arc voltage had increased over this period of operation. No life limiting mechanisms were observed during the course of the testing.

Curran, Francis M.; Hardy, Terry L.; Haag, Thomas W.

1987-01-01

239

Cyclical vomiting syndrome: Recognition, assessment and management  

PubMed Central

Cyclical vomiting syndrome (CVS) is a functional, debilitating disorder of childhood frequently leading to hospitalization. Affected children usually experience a stereotypical pattern of vomiting though it may vary between different individuals. The vomiting is intense often bilious, and accompanied by disabling nausea. Identifiable precipitating factors for CVS include psychosocial stressors, infections, lack of sleep and occasionally even food triggers. Often, it may be difficult to distinguish episodes of CVS from other causes of acute abdomen and altered consciousness. Thus, the diagnosis of CVS remains largely one of exclusion. Investigations routinely done during the work-up of a child with suspected CVS include both blood and imaging modalities. Plasma lactate, ammonia, amino acid and acylcarnitine profiles as well as urine organic acid profile are indicated to exclude inborn errors of metabolism. The treatment remains challenging and targeted at prevention or shortening of the attacks and can be considered as abortive, supportive and prophylactic. Use of non-pharmacological therapy is also part of the management of CVS. The prognosis of CVS is variable. More insight into the pathogenesis of this disorder as well as role of non-pharmacological therapy is needed.

Tan, Michelle LN; Liwanag, Maria Janelle; Quak, Seng Hock

2014-01-01

240

Noise-guided evolution within cyclical interactions  

NASA Astrophysics Data System (ADS)

We study a stochastic predator prey model on a square lattice, where each of the six species has two superior and two inferior partners. The invasion probabilities between species depend on the predator prey pair and are supplemented by Gaussian noise. Conditions are identified that warrant the largest impact of noise on the evolutionary process, and the results of Monte Carlo simulations are qualitatively reproduced by a four-point cluster dynamical mean-field approximation. The observed noise-guided evolution is deeply routed in short-range spatial correlations, which is supported by simulations on other host lattice topologies. Our findings are conceptually related to the coherence resonance phenomenon in dynamical systems via the mechanism of threshold duality. We also show that the introduced concept of noise-guided evolution via the exploitation of threshold duality is not limited to predator prey cyclical interactions, but may apply to models of evolutionary game theory as well, thus indicating its applicability in several different fields of research.

Perc, Matja; Szolnoki, Attila

2007-08-01

241

Cyclic dynamics in simulated plant populations.  

PubMed Central

Despite the general interest in nonlinear dynamics in animal populations, plant populations are supposed to show a stable equilibrium that is attributed to fundamental differences compared with animals. Some studies find more complex dynamics, but empirical studies usually are too short and most modelling studies ignore important spatial aspects of local competition and establishment. Therefore, we used a spatially explicit individual-based model of a hypothetical, non-clonal perennial to explore which mechanisms might generate complex dynamics, i.e. cycles. The model is based on the field-of-neighbourhood approach that describes local competition and establishment in a phenomenological manner. We found cyclic population dynamics for a wide spectrum of model variants, provided that mortality is determined by local competition and recruitment is virtually completely suppressed within the zone of influence of established plants. This destabilizing effect of local processes within plant populations might have wide-ranging implications for the understanding of plant community dynamics and coexistence. PMID:12495487

Bauer, Silke; Berger, Uta; Hildenbrandt, Hanno; Grimm, Volker

2002-01-01

242

Cyclical vomiting syndrome: Recognition, assessment and management.  

PubMed

Cyclical vomiting syndrome (CVS) is a functional, debilitating disorder of childhood frequently leading to hospitalization. Affected children usually experience a stereotypical pattern of vomiting though it may vary between different individuals. The vomiting is intense often bilious, and accompanied by disabling nausea. Identifiable precipitating factors for CVS include psychosocial stressors, infections, lack of sleep and occasionally even food triggers. Often, it may be difficult to distinguish episodes of CVS from other causes of acute abdomen and altered consciousness. Thus, the diagnosis of CVS remains largely one of exclusion. Investigations routinely done during the work-up of a child with suspected CVS include both blood and imaging modalities. Plasma lactate, ammonia, amino acid and acylcarnitine profiles as well as urine organic acid profile are indicated to exclude inborn errors of metabolism. The treatment remains challenging and targeted at prevention or shortening of the attacks and can be considered as abortive, supportive and prophylactic. Use of non-pharmacological therapy is also part of the management of CVS. The prognosis of CVS is variable. More insight into the pathogenesis of this disorder as well as role of non-pharmacological therapy is needed. PMID:25254185

Tan, Michelle Ln; Liwanag, Maria Janelle; Quak, Seng Hock

2014-08-01

243

Hot embossing of cyclic olefin copolymers  

NASA Astrophysics Data System (ADS)

The hot embossing properties of cyclic olefin copolymer (COC) have been examined as a function of comonomer content. Six standard grades of COC with varying norbornene content (61-82 wt%) were used in these experiments in order to provide a range of glass transition temperatures, Tg. All grades of COC exhibited sharp increases in embossed depth over a critical range of temperature. The transition temperature in embossed depth increased linearly with norbornene content for both 35 and 70 m deep structures. At temperatures above this transition, the dimensions of the embossed patterns were essentially independent of the COC grade, the applied pressure and duration of loading. Channels formed above the transition in a regime of viscous liquid flow were extremely smooth in morphology for all grades. The average surface roughness, Ra, measured at the base of the channels decreased sharply at the transition temperature, with a levelling off at higher temperatures. Grades of COC with a higher norbornene content exhibited extensive micro-cracking during embossing at temperatures close to the transition temperature.

Leech, P. W.

2009-05-01

244

Simulating the vapourliquid equilibria of large cyclic alkanes  

E-print Network

Self-adapting fixed endpoint configurational-bias Monte Carlo simulations in the Gibbs ensemble were carried out to determine the vapourliquid coexistence curves of cyclic alkanes from c-pentane to c-octadecane. In general, the critical temperatures and densities of the cyclic alkanes are substantially higher than those of their linear counterparts. Furthermore, the simulation data point to a maximum in the critical density for cyclic alkanes with about eight carbon atoms as also observed for the linear alkanes. 1.

Jun-seok Lee; Collin D. Wick; John M. Stubbs; J. Ilja Siepmann

2004-01-01

245

Cyclic plasticity models and application in fatigue analysis  

NASA Technical Reports Server (NTRS)

An analytical procedure for prediction of the cyclic plasticity effects on both the structural fatigue life to crack initiation and the rate of crack growth is presented. The crack initiation criterion is based on the Coffin-Manson formulae extended for multiaxial stress state and for inclusion of the mean stress effect. This criterion is also applied for the accumulated damage ahead of the existing crack tip which is assumed to be related to the crack growth rate. Three cyclic plasticity models, based on the concept of combination of several yield surfaces, are employed for computing the crack growth rate of a crack plane stress panel under several cyclic loading conditions.

Kalev, I.

1981-01-01

246

The SU(3) algebra in a cyclic basis  

NASA Astrophysics Data System (ADS)

With the couplings between the eight gluons constrained by the structure constants of the su(3) algebra in QCD, one would expect that there should exist a special basis (or set of bases) for the algebra wherein, unlike in a Cartan-Weyl basis, all gluons interact identically (cyclically) with each other, explicitly on an equal footing. We report here particular such bases, which we have found in a computer search, and we indicate associated 33 representations. We conjecture that essentially all cyclic bases for su(3) may be obtained from these making appropriate circulant transformations, and that cyclic bases may also exist for other su(n), n >3.

Harrison, P. F.; Krishnan, R.; Scott, W. G.

2014-07-01

247

Acceleration and vacuum temperature  

NASA Astrophysics Data System (ADS)

The quantum fluctuations of an accelerated vacuum state, that is, vacuum fluctuations in the presence of a constant electromagnetic field, can be described by the temperature TM. Considering TM for the gyromagnetic factor g=1 we show that TM(g=1)=TU, where TU is the Unruh temperature experienced by an accelerated observer. We conjecture that both particle production and nonlinear field effects inherent in the Unruh accelerated observer case are described by the case g=1 QED of strong fields. We present rates of particle production for g=0, 1, 2 and show that the case g=1 is experimentally distinguishable from g=0, 2. Therefore, either accelerated observers are distinguishable from accelerated vacuum or there is unexpected modification of the theoretical framework.

Labun, Lance; Rafelski, Johann

2012-08-01

248

Open accelerating structures  

SciTech Connect

An ''Open'' Accelerating Structure must first perform the mode matching function of any accelerating structure, i.e., it must couple an incoming free field to an accelerating mode. The simplest open periodic structure that can be considered is a grating. There has been an attempt to employ an inverse Purcell effect by illuminating a grating from directly above with plane parallel light and passing the particles over the surface of the grating at right angles to the lines. Unfortunately, it has been shown by the Lawson theorem that these geometries fail to accelerate relativistic particles. This paper will restate Lawson's theorem but show that it applies only to the simple two-dimensional situation. It is shown that accelerating fields above grating can be made to fall off exponentially from that surface. Several structures are examined that deal with the problem of fields spreading over the whole grating surface.

Palmer, R.B.

1986-12-01

249

The Accelerated Kepler Problem  

E-print Network

The accelerated Kepler problem is obtained by adding a constant acceleration to the classical two-body Kepler problem. This setting models the dynamics of a jet-sustaining accretion disk and its content of forming planets as the disk loses linear momentum through the asymmetric jet-counterjet system it powers. The dynamics of the accelerated Kepler problem is analyzed using physical as well as parabolic coordinates. The latter naturally separate the problem's Hamiltonian into two unidimensional Hamiltonians. In particular, we identify the origin of the secular resonance in the accelerated Kepler problem and determine analytically the radius of stability boundary of initially circular orbits that are of particular interest to the problem of radial migration in binary systems as well as to the truncation of accretion disks through stellar jet acceleration.

Fathi Namouni; Massimiliano Guzzo

2007-05-22

250

A cyclic viscoelastic-viscoplastic constitutive model for clay and liquefaction analysis of multi-layered ground  

NASA Astrophysics Data System (ADS)

In order to estimate viscous effect of clay in the wide range of low to high level of strain, a cyclic viscoelastic-viscoplastic constitutive model for clay is proposed. First, we confirm the performance of the proposed model by simulating the cyclic undrained triaxial tests to determine the cyclic strength and deformation characteristics of a natural marine clay. Then, the proposed model is incorporated into an effective stress based liquefaction analysis method to estimate the effect of an intermediate clay layer on the behaviour of liquefiable sand layers.The seismic response against foreshocks, main shock as well as aftershocks of 1995 Hyogoken Nambu Earthquake is analysed in the present study. The difference of shear strength characteristics of the alluvial clay layer is one of the reasons why Port Island has a higher liquefaction potential than that of Rokko Island. The proposed model gives a good description of the damping characteristics of clay layer during large earthquakes. Acceleration responses in both clay layer and liquefiable sand layer just above it are damped due to viscous effect of clay. In the case of main shock and the following aftershocks that occurred within less than 9 days after main event, acceleration responses near ground surface are de-amplified due to the developed excess pore water pressure, while responses near ground surface are amplified before and long after the main event. Using the viscoelastic-viscoplastic model for clay layer, time history of acceleration response in upper liquefiable sand layer can be well calculated, in particular in the range of microtremor process after the main seismic motion. Copyright

Oka, Fusao; Kodaka, Takeshi; Kim, Yong-Seong

2004-02-01

251

Analyzing radial acceleration with a smartphone acceleration sensor  

NASA Astrophysics Data System (ADS)

This paper continues the sequence of experiments using the acceleration sensor of smartphones (for description of the function and the use of the acceleration sensor, see Ref. 1) within this column, in this case for analyzing the radial acceleration.

Vogt, Patrik; Kuhn, Jochen

2013-03-01

252

Effects of cyclic flexural fatigue on porcine bioprosthetic heart valve heterograft biomaterials.  

PubMed

Although bioprosthetic heart valves (BHV) remain the primary treatment modality for adult heart valve replacement, continued problems with durability remain. Several studies have implicated flexure as a major damage mode in porcine-derived heterograft biomaterials used in BHV fabrication. Although conventional accelerated wear testing can provide valuable insights into BHV damage phenomena, the constituent tissues are subjected to complex, time-varying deformation modes (i.e., tension and flexure) that do not allow for the control of the amount, direction, and location of flexure. Thus, in this study, customized fatigue testing devices were developed to subject circumferentially oriented porcine BHV tissue strips to controlled cyclic flexural loading. By using this approach, we were able to study layer-specific structural damage induced by cyclic flexural tensile and compressive stresses alone. Cycle levels of 10 x 10(6), 25 x 10(6), and 50 x 10(6) were used, with resulting changes in flexural stiffness and collagen structure assessed. Results indicated that flexural rigidity was markedly reduced after only 10 x 10(6) cycles, and progressively decayed at a lower rate with cycle number thereafter. Moreover, the against-curvature fatigue direction induced the most damage, suggesting that the ventricularis and fibrosa layers have low resistance to cyclic flexural compressive and tensile loads, respectively. The histological analyses indicated progressive collagen fiber delamination as early as 10 x 10(6) cycles but otherwise no change in gross collagen orientation. Our results underscore that porcine-derived heterograft biomaterials are very sensitive to flexural fatigue, with delamination of the tissue layers the primary underlying mechanism. This appears to be in contrast to pericardial BHV, wherein high tensile stresses are considered to be the major cause of structural failure. These findings point toward the need for the development of chemical fixation technologies that minimize flexure-induced damage to extend porcine heterograft biomaterial durability. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010. PMID:20166221

Mirnajafi, Ali; Zubiate, Brett; Sacks, Michael S

2010-07-01

253

The Residual Stress Relaxation Behavior of Weldments During Cyclic Loading  

NASA Astrophysics Data System (ADS)

Accurate measurement of residual stress is necessary to obtain reliable predictions of fatigue lifetime and enable estimation of time-to-facture for any given stress level. In this article, relaxation of welding residual stresses as a function of cyclic loading was documented on three common steels: AISI 1008, ASTM A572, and AISI 4142. Welded specimens were subjected to cyclic bending ( R = 0.1) at different applied stresses, and the residual stress relaxation existing near the welds was measured as a function of cycles. The steels exhibited very different stress relaxation behaviors during cyclic loadings, which can be related to the differences in the microstructures of the specimens. A phenomenological model, which treats dislocation motion during cyclic loading as being analogous to creep of dislocations, is proposed for estimation of the residual stress relaxation.

Qian, Zhongyuan; Chumbley, Scott; Karakulak, Tugce; Johnson, Eric

2013-07-01

254

Gadolinium-binding cyclic hexapeptoids: synthesis and relaxometric properties.  

PubMed

Two new cyclic hexapeptoids incorporating N-carboxyethylglycine and N-methoxyethylglycine residues are able to efficiently bind Gd(3+). Their thermodynamic stabilities and relaxivities have been assessed by (1)H-relaxometric investigations. PMID:24287618

De Cola, Chiara; Fiorillo, Gaetano; Meli, Alessandra; Aime, Silvio; Gianolio, Eliana; Izzo, Irene; De Riccardis, Francesco

2014-01-21

255

21 CFR 862.1230 - Cyclic AMP test system.  

Code of Federal Regulations, 2013 CFR

...parathyroid gland). Cyclic AMP measurements may also be used in the diagnosis and treatment of Graves' disease (a disorder of the thyroid) and in the differentiation of causes of hypercalcemia (elevated levels of serum calcium.) (b) Classification....

2013-04-01

256

Risedronate and alendronate suppress osteocyte apoptosis following cyclic fatigue loading  

Microsoft Academic Search

PurposeThe purpose of this study was to determine whether bisphosphonate treatment can prevent or delay osteocyte apoptosis in a cyclic fatigue animal model and if there are differences between two different bisphosphonates in their effects on osteocyte apoptosis.

Helene Follet; Jiliang Li; Roger J. Phipps; Siu Hui; Keith Condon; David B. Burr

2007-01-01

257

AN ANALYSIS OF A PROLIFIC TORNADO PRODUCING CYCLIC SUPERCELL THUNDERSTORM  

E-print Network

1 P3.1 AN ANALYSIS OF A PROLIFIC TORNADO PRODUCING CYCLIC SUPERCELL THUNDERSTORM IN NUCKOLLS COUNTY thunderstorm (hereafter referred to as the "Thayer County storm") near Hastings, Nebraska and moved through

258

How turbulence regulates biodiversity in systems with cyclic competition  

E-print Network

Cyclic, non-hierarchical interactions among biological species represent a general mechanism by which ecosystems are able to maintain high levels of biodiversity. However, species coexistence is often possible only in spatially extended systems with a limited range of dispersal, whereas in well-mixed environments models for cyclic competition often lead to a loss of biodiversity. Here, we consider the dispersal of biological species in a fluid environment, where mixing is achieved by a combination of advection and diffusion. In particular, we perform a detailed numerical analysis of a model composed of turbulent advection, diffusive transport, and cyclic interactions among biological species in two spatial dimensions, and discuss the circumstances under which biodiversity is maintained when external environmental conditions, such as resource supply, are uniform in space. Cyclic interactions are represented by a model with three competitors, resembling the children's game of rock-paper-scissors, whereas the fl...

Groselj, Daniel; Frey, Erwin

2014-01-01

259

Atomistic mechanisms of cyclic hardening in metallic glass  

E-print Network

Molecular dynamics with an embedded-atom method potential is used to simulate the nanoindentation of Cu[subscript 63.5]Zr[subscript 36.5] metallic glasses. In particular, the effects of cyclic loading within the nominal ...

Deng, Chuang

260

High-Speed Computation of Cyclic Redundancy Checks  

E-print Network

and Computer Engineering New Mexico State University November 1995 Abstract Cyclic redundancy checks (CRCs) are widely used in error-prone channels to detect corruption of data blocks. This report describes

Johnson, Eric E.

261

Cyclical Cohabitation Among Unmarried Parents in Fragile Families  

PubMed Central

Building on past research suggesting that cohabitation is an ambiguous family form, the authors examined an understudied residential pattern among unmarried parents: cyclical cohabitation, in which parents have multiple cohabitation spells with each other. Using 9 years of panel data from the Fragile Families and Child Wellbeing Study (N = 2,084), they found that 10% of all parents with nonmarital births, and nearly a quarter of those living together when the child is 9 years old, are cyclical cohabitors. Cyclically cohabiting mothers reported more material hardships than mothers in most other relationship patterns but also reported more father involvement with children. On all measures of child well-being, except grade retention, children of cyclically cohabiting parents fared no worse than children of stably cohabiting biological parents and did not differ significantly from any other group. PMID:25067855

Nepomnyaschy, Lenna; Teitler, Julien

2013-01-01

262

Large electrostatic accelerators  

SciTech Connect

The increasing importance of energetic heavy ion beams in the study of atomic physics, nuclear physics, and materials science has partially or wholly motivated the construction of a new generation of large electrostatic accelerators designed to operate at terminal potentials of 20 MV or above. In this paper, the author briefly discusses the status of these new accelerators and also discusses several recent technological advances which may be expected to further improve their performance. The paper is divided into four parts: (1) a discussion of the motivation for the construction of large electrostatic accelerators, (2) a description and discussion of several large electrostatic accelerators which have been recently completed or are under construction, (3) a description of several recent innovations which may be expected to improve the performance of large electrostatic accelerators in the future, and (4) a description of an innovative new large electrostatic accelerator whose construction is scheduled to begin next year. Due to time and space constraints, discussion is restricted to consideration of only tandem accelerators.

Jones, C.M.

1984-01-01

263

Dynamic effects of predators on cyclic voles: field experimentation and model extrapolation.  

PubMed Central

Mechanisms generating the well-known 3-5 year cyclic fluctuations in densities of northern small rodents (voles and lemmings) have remained an ecological puzzle for decades. The hypothesis that these fluctuations are caused by delayed density-dependent impacts of predators was tested by replicated field experimentation in western Finland. We reduced densities of all main mammalian and avian predators through a 3 year vole cycle and compared vole abundances between four reduction and four control areas (each 2.5-3 km(2)). The reduction of predator densities increased the autumn density of voles fourfold in the low phase, accelerated the increase twofold, increased the autumn density of voles twofold in the peak phase, and retarded the initiation of decline of the vole cycle. Extrapolating these experimental results to their expected long-term dynamic effects through a demographic model produces changes from regular multiannual cycles to annual fluctuations with declining densities of specialist predators. This supports the findings of the field experiment and is in agreement with the predation hypothesis. We conclude that predators may indeed generate the cyclic population fluctuations of voles observed in northern Europe. PMID:12028754

Korpimaki, Erkki; Norrdahl, Kai; Klemola, Tero; Pettersen, Terje; Stenseth, Nils Chr

2002-01-01

264

Precipitation in solution-treated Al-4wt%Cu under cyclic strain  

SciTech Connect

Solution-treated Al-4wt%Cu was strain-cycled at ambient temperature and above and the precipitation behavior investigated by TEM. In the temperature range 100 C to 200 C precipitation of {Theta}'' appears to have been suppressed and precipitation of {Theta}' promoted via cyclic strain. Anomalously rapid growth of precipitates appears to have been facilitated by a vacancy supersaturation generated by dislocation motion, with a diminishing effect observed at higher temperatures due to the faster recovery of non-equilibrium vacancy concentrations. {Theta}' precipitates generated under cyclic strain are considerably smaller and more finely dispersed than those typically produced via quench-aging due to their heterogeneous nucleation on dislocations, and possess a low aspect ratio and rounded edges of the broad faces due to the introduction of ledges into the growing precipitates by dislocation cutting. Frequency effects indicate that dislocation motion, rather than the extremely small precipitate size, is responsible for the observed reduction in aspect ratio. Accelerated formation of grain boundary precipitates appears partially responsible for rapid intergranular fatigue failure following cycling at elevated temperatures, producing fatigue striations and ductile dimples coexistent on the fracture surface.

Farrow, Adam M [Los Alamos National Laboratory; Laird, Campbell [U PENN

2010-09-15

265

Cyclical Regolith Processes on Hydrous Asteroids  

NASA Astrophysics Data System (ADS)

Carbonaceous chondrites experienced and recorded a very wide range of chemical and physical processing in both nebular and asteroidal settings. Among the features arising from asteroidal processes are the following: (1) most of these meteorites are breccias; (2) some CV3s and CMs contain flattened chondrules and exhibit foliation; (3) veins are found in some CIs, CMs, CV3 dark inclusions; (4) CR2s, all CIs, some CR2s and CMs display weak alignment of matrix phyllosilicates, and (5) shearing (mylonitization) around lithic fragments. While these features have generally been assumed to have involved impact deformation in asteroidal regoliths, a process sometimes referred to as regolith or impact gardening, we suggest here that all of these particular features would have arisen naturally from cycles of wet-dry and freeze-thaw environmental conditions in asteroid regoliths. All of the extensively (Y82042, ALH 83100, Cold Bokkeveld, Y891198, EET 90047) and completely (ALH 88045, EET 83334, Kaidun CM1 lithology) altered CMs contain rounded to elliptical aggregates of phyllosilicates, carbonates, spinels (chromite and magnetite), Fe-Ni sulfides, and embayed olivines and pyroxenes, which we interpret as relict chondrules [1]; these sometimes define a definite foliation direction generally ascribed to impact shock [2&3]. We examined all available relict olivines from CMs showing the most pronounced chondrule flattening and foliation, and found only a few planar fractures in a single olivine grain in one sample (EET 90047), and no sign of shock effects in the others. We therefore suggest that static burial pressure was agent responsible for chondrule flattening in this case, and believe that the processes involved in burial compaction deserve more attention than they have hitherto received in the asteroid literature. It is probable that even in the wettest regions of an asteroid dry periods were experienced during the periodic breaching of an icy surficial rind [4], which could have occurred during impacts or "volcanic" venting of gas and heat from the interior (this assumes internal heating). Thus, there should have been multiple wet-dry cycles involved in the genesis of these materials. It is well-known to soil scientists that conditions of radically alternating humidity can have important morphologic and petrologic consequences. Grains and lithic clasts can become rotated, crushed and drawn out into linear features (shearing). Porosity (including contraction and shearing cracks) and other bulk physical properties will vary in dramatic manner. These effects would be most pronounced for the CI and CR chondrites, as well as the Kaidun CM1 lithology, where the swelling clay saponite is found in abundance. Easily altered materials will be dissolved while more resistant materials will be pulverized and mixed into matrix [5]. Another important process to be considered is periodic growth and melting of ice crystals in the regolith [6]. The positive molal volume change during crystallization of water will induce oriented microfabrics to develop in the regolith, normal to the direction of ice crystal growth. Thus, platy grains (such as phyllosilicates) will develop a pronounced compaction and preferred alignment. Since the orientation of the growing ice mass will vary for each succeeding generation of growth, the eventual result will be to impart a particular, invasive, regolith fabric consisting of anastomosing strings of phyllosilicates with roughly aligned basal directions for each string. Such textures are common in the wettest chondrites: CIs and CMs. Growth and collapse of these asteroidal icicles will also impart cyclical changes in bulk regolith porosity, induce rotation and movement of crystals and lithic fragments through frost heaving, and consequent shearing. This process could also account, to some degree, for the flattened chondrules. We therefore suggest that cyclical, indigenous environmental processes, rather than impact gardening, could be responsible for many (most?) of the late stage petrologic characteri

Zolensky, M. E.

1995-09-01

266

Unified constitutive modeling for proportional and nonproportional cyclic plasticity responses  

NASA Astrophysics Data System (ADS)

Several features of cyclic plasticity, e.g. cyclic hardening/softening, ratcheting, relaxation, and their dependence on strain range, nonproportionality of loading, time, and temperature determine the stress-strain responses of materials under cyclic loading. Numerous efforts have been made in the past decades to characterize and model these responses. Many of these responses can be simulated reasonably by the existing constitutive models, but the same models would fail in simulating the structural responses, local stress-strain or global deformation. One of the reasons for this deficiency is that the constitutive models are not robust enough to simulate the cyclic plasticity responses when they interact with each other. This deficiency can be understood better or resolved by developing and validating constitutive models against a broad set of experimental responses and two or more of the responses interacting with each other. This dissertation develops a unified constitutive model by studying the cyclic plasticity features in an integrated manner and validating the model by simulating a broad set of proportional and nonproportional cyclic plasticity responses. The study demonstrates the drawbacks of the existing nonlinear kinematic hardening model originally developed by Chaboche and then develop and incorporate novel ideas into the model for improving its cyclic response simulations. The Chaboche model is modified by incorporating strain-range dependent cyclic hardening/softening through the kinematic hardening rule parameters, in addition to the conventional method of using only the isotropic hardening parameters. The nonproportional loading memory parameters of Tanaka and of Benallal and Marquis are incorporated to study the influence of nonproportionality. The model is assessed by simulating hysteresis loop shape, cyclic hardening-softening, cross-effect, cyclic relaxation, subsequent cyclic softening, and finally a series of ratcheting responses under uniaxial and biaxial loading responses. Next, it is demonstrated that the hysteresis loop shape and width can be improved by incorporation of time dependence (visco-effect) and a novel modeling scheme of backstress shift. Overall, this dissertation demonstrates a methodical and systematic development of a constitutive model for simulating a broad set of low-cycle fatigue responses.

Krishna, Shree

267

Mechanistic understanding of surface plasmon assisted catalysis on a single particle: cyclic redox of 4-aminothiophenol  

PubMed Central

Surface plasmon assisted catalysis (SPAC) reactions of 4-aminothiophenol (4ATP) to and back from 4,4?-dimercaptoazobenzene (DMAB) have been investigated by single particle surface enhanced Raman spectroscopy, using a self-designed gas flow cell to control the reductive/oxidative environment over the reactions. Conversion of 4ATP into DMAB is induced by energy transfer (plasmonic heating) from surface plasmon resonance to 4ATP, where O2 (as an electron acceptor) is essential and H2O (as a base) can accelerate the reaction. In contrast, hot electron (from surface plasmon decay) induction drives the reverse reaction of DMAB to 4ATP, where H2O (or H2) acts as the hydrogen source. More interestingly, the cyclic redox between 4ATP and DMAB by SPAC approach has been demonstrated. This SPAC methodology presents a unique platform for studying chemical reactions that are not possible under standard synthetic conditions. PMID:24141289

Xu, Ping; Kang, Leilei; Mack, Nathan H.; Schanze, Kirk S.; Han, Xijiang; Wang, Hsing-Lin

2013-01-01

268

Protein denaturation induced by cyclic silicone.  

PubMed

While it has been demonstrated that such low-molecular-weight cyclic silicones as octamethylcyclotetrasiloxane (D4) exhibit adjuvant activity, the mechanism of immunological response to silicone is still not clear. This study therefore used fluorescence and circular dichroism (CD) spectroscopy to investigate the denaturation and conformational change of two proteins, fibronectin (Fn) and fibrinogen (Fbg), induced by D4 in vitro. Incubating D4 with Fbg or Fn at D4-to-protein ratios of > 100 or for > 10 h yielded white and mould-like precipitates of the proteins, indicating massive denaturation and aggregation. The fact that the decrease in fluorescence intensity of D4-treated Fn and Fbg was accompanied by a red shift in the maximum wavelength also indicated that denaturation of the proteins had taken place. These changes in fluorescence might result from exposure of tryptophan residuals in the proteins to polar water molecules inasmuch as the denaturation would lead to changes in the tertiary structures of the proteins and rearrangement of the tryptophan residues. The loss of the tertiary structure leads to protein denaturation and, consequently, precipitation. The difference in CD spectra between control Fbg (or Fn) and D4-treated Fbg (or Fn) indicated conformational changes of the proteins when incubated with D4. Thus it has been demonstrated that D4 can induce denaturation and conformational changes in Fbg and Fn and it can be expected that protein molecules that have undergone denaturation or conformational change induced by D4 may act as antigens and stimulate the immune system to generate antibodies, ultimately resulting in autoimmune disease. PMID:9613806

Sun, L; Alexander, H; Lattarulo, N; Blumenthal, N C; Ricci, J L; Chen, G

1997-12-01

269

Highly Efficient Protein Misfolding Cyclic Amplification  

PubMed Central

Protein misfolding cyclic amplification (PMCA) provides faithful replication of mammalian prions in vitro and has numerous applications in prion research. However, the low efficiency of conversion of PrPC into PrPSc in PMCA limits the applicability of PMCA for many uses including structural studies of infectious prions. It also implies that only a small sub-fraction of PrPC may be available for conversion. Here we show that the yield, rate, and robustness of prion conversion and the sensitivity of prion detection are significantly improved by a simple modification of the PMCA format. Conducting PMCA reactions in the presence of Teflon beads (PMCAb) increased the conversion of PrPC into PrPSc from ?10% to up to 100%. In PMCAb, a single 24-hour round consistently amplified PrPSc by 600-700-fold. Furthermore, the sensitivity of prion detection in one round (24 hours) increased by 2-3 orders of magnitude. Using serial PMCAb, a 1012-fold dilution of scrapie brain material could be amplified to the level detectible by Western blotting in 3 rounds (72 hours). The improvements in amplification efficiency were observed for the commonly used hamster 263K strain and for the synthetic strain SSLOW that otherwise amplifies poorly in PMCA. The increase in the amplification efficiency did not come at the expense of prion replication specificity. The current study demonstrates that poor conversion efficiencies observed previously have not been due to the scarcity of a sub-fraction of PrPC susceptible to conversion nor due to limited concentrations of essential cellular cofactors required for conversion. The new PMCAb format offers immediate practical benefits and opens new avenues for developing fast ultrasensitive assays and for producing abundant quantities of PrPSc in vitro. PMID:21347353

Ostapchenko, Valeriy G.; Savtchenk, Regina; Alexeeva, Irina; Rohwer, Robert G.; Baskakov, Ilia V.

2011-01-01

270

Cyclic Peptidomimetics and Pseudopeptides from Multicomponent Reactions  

NASA Astrophysics Data System (ADS)

Multicomponent reactions (MCRs) that provide in the final product amides are suitable to produce peptides and peptide-like moieties. The Passerini and Staudinger reactions provide one amide bond, and the Ugi-four-component reaction generates two amides from three or even four (or more) components, respectively. The Ugi-reaction thus is most important to produce peptides and peptoids while the Passerini reaction is useful to generate depsipeptoid moieties. In order to produce cyclic peptides and pseudopeptides, the linear peptidic MCR products have to be cyclized, usually with the help of bifunctional or activatable building blocks. Orthogonal but cyclizable secondary functionalities that need no protection in isonitrile MCRs commonly include alkenes (for ring closing metathesis), azide/alkyne (for Huisgen click reactions) or dienes and enoates (Diels-Alder) etc. If MCR-reactive groups are to be used also for the cyclisation, monoprotected bifunctional building blocks are used and deprotected after the MCR, e.g. for Ugi reactions as Ugi-Deprotection-Cyclisation (UDC). Alternatively one of the former building blocks or functional groups generated by the MCR can be activated. Most commonly these are activated amides (from so-called convertible isonitriles) which can be used e.g. for Ugi-Activation-Cyclisation (UAC) protocols, or most recently for a simultaneous use of both strategies Ugi-Deprotection/Activation-Cyclisation (UDAC). These methods mostly lead to small, medicinally relevant peptide turn mimics. In an opposing strategy, the MCR is rather used as ring-closing reaction, thereby introducing a (di-)peptide moiety. Most recently these processes have been combined to use MCRs for both, linear precursor synthesis and cyclisation. These multiple MCR approaches allow the most efficient and versatile one pot synthesis of macrocyclic pseudopeptides known to date.

Wessjohann, Ludger A.; Rhoden, Cristiano R. B.; Rivera, Daniel G.; Vercillo, Otilie Eichler

271

A New Interstellar Cyclic Molecule, Ethylene Oxide  

NASA Astrophysics Data System (ADS)

Ethylene oxide (c-C2H4O) is only the fourth known ring molecule identified in the interstellar medium, detected in the Galactic Center cloud SgrB2(N) by Dickens et al. (1997). It is the higher energy isomer of both the more familiar interstellar species acetaldehyde (CH3CHO) and the as yet undetected molecule vinyl alcohol (CH2CHOH). Dickens et al. (1997) reported a c-C2H4O molecular column density about an order of magnitude less than that reported for CH3CHO in SgrB2(N). This is a factor of 200 larger than the predictions of the new standard gas phase chemistry model of Lee, Bettens, and Herbst (1996), suggesting that the formation of c-C2H4O may be related to molecular formation on interstellar grains. We present observations of the c-C2H4O to CH3CHO abundance ratio in 5 additional molecular clouds. The data were taken in October 1997 with the Swedish-European Submillimeter Telescope in Chile. The confirmation of ethylene oxide in molecular clouds provides an appealing scenario for the first link in the chain of reactions leading to the origin of life, since it has been suggested as a possible pathway to the formation of the related cyclic molecule oxiranecarbonitrile (c-C3H3NO; cf., Dickens et al. 1996), a precursor to the synthesis of sugar phosphates which comprise the backbone of our molecular genetic structure. References: Dickens, J.E., Irvine, W.M., Ohishi, M., Ikeda, M., Ishikawa, S., Nummelin, A., and Hjalmarson, A. 1997, Astrophys. J., 489 (in press). Dickens, J.E. et al. 1996, Orig. Life Evol. Biosphere, 26, 97. Lee, H.-H., Bettens, R.P.A., and Herbst, E. 1996, Astron. Astrophys. Supp., 119, 111.

Dickens, J. E.; Irvine, W. M.; Ohishi, M.; Ikeda, M.; Ishikawa, S.; Nummelin, A.; Hjalmarson, A.

1997-12-01

272

Phantom energy accretion onto black holes in a cyclic universe  

SciTech Connect

Black holes pose a serious problem in cyclic or oscillating cosmology. It is speculated that, in the cyclic universe with phantom turnarounds, black holes will be torn apart by phantom energy prior to turnaround before they can create any problems. In this paper, using the mechanism of phantom accretion onto black holes, we find that black holes do not disappear before phantom turnaround. But the remanent black holes will not cause any problems due to Hawking evaporation.

Sun Chengyi [Institute of Modern Physics, Northwest University Xian, 710069 (China)

2008-09-15

273

Fine structure of the asymptotic expansion of cyclic integrals  

E-print Network

The asymptotic expansion of $n$-dimensional cyclic integrals was expressed as a series of functionals acting on the symmetric function involved in the cyclic integral. In this article, we give an explicit formula for the action of these functionals on a specific class of symmetric functions. These results are necessary for the computation of the O(1) part in the long-distance asymptotic behavior of correlation functions in integrable models.

K. K. Kozlowski

2010-01-20

274

Pilot cyclic prefixed single carrier communication: channel estimation and equalization  

Microsoft Academic Search

Cyclic prefixed single carrier (CP-SC) has emerged as a promising technique for wideband wireless communication. The cyclic prefix (CP) in CP-SC costs some bandwidth, but it cannot be used for channel estimation in fast-variant channel environment. In this letter, a new scheme is proposed for CP-SC which not only adds a CP but also a suffix. With the aid of

Yonghong Zeng; Tung Sang Ng

2005-01-01

275

Prediction of power semiconductors devices reliability working in cyclic mode  

NASA Astrophysics Data System (ADS)

A new approach prediction of reliability for power semiconductor devices in cyclic mode based on the numerical analysis of nonuniform temperature fields is proposed. We have compared the failure rates of semiconductor power devices in the real thermal regime under natural convection with statistical data. The necessity to consider the actual unsteady temperature fields to enhance the predicted working resource of the power semiconductor in cyclic mode is shown.

Kravchenko, E. V.; Kuznetsov, G. V.

2014-08-01

276

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics  

PubMed Central

Summary In the recent past, the design and synthesis of peptide mimics (peptidomimetics) has received much attention. This because they have shown in many cases enhanced pharmacological properties over their natural peptide analogues. In particular, the incorporation of cyclic constructs into peptides is of high interest as they reduce the flexibility of the peptide enhancing often affinity for a certain receptor. Moreover, these cyclic mimics force the molecule into a well-defined secondary structure. Constraint structural and conformational features are often found in biological active peptides. For the synthesis of cyclic constrained peptidomimetics usually a sequence of multiple reactions has been applied, which makes it difficult to easily introduce structural diversity necessary for fine tuning the biological activity. A promising approach to tackle this problem is the use of multicomponent reactions (MCRs), because they can introduce both structural diversity and molecular complexity in only one step. Among the MCRs, the isocyanide-based multicomponent reactions (IMCRs) are most relevant for the synthesis of peptidomimetics because they provide peptide-like products. However, these IMCRs usually give linear products and in order to obtain cyclic constrained peptidomimetics, the acyclic products have to be cyclized via additional cyclization strategies. This is possible via incorporation of bifunctional substrates into the initial IMCR. Examples of such bifunctional groups are N-protected amino acids, convertible isocyanides or MCR-components that bear an additional alkene, alkyne or azide moiety and can be cyclized via either a deprotectioncyclization strategy, a ring-closing metathesis, a 1,3-dipolar cycloaddition or even via a sequence of multiple multicomponent reactions. The sequential IMCR-cyclization reactions can afford small cyclic peptide mimics (ranging from four- to seven-membered rings), medium-sized cyclic constructs or peptidic macrocycles (>12 membered rings). This review describes the developments since 2002 of IMCRs-cyclization strategies towards a wide variety of small cyclic mimics, medium sized cyclic constructs and macrocyclic peptidomimetics. PMID:24605172

Koopmanschap, Gijs; Ruijter, Eelco

2014-01-01

277

A computer program for cyclic plasticity and structural fatigue analysis  

NASA Technical Reports Server (NTRS)

A computerized tool for the analysis of time independent cyclic plasticity structural response, life to crack initiation prediction, and crack growth rate prediction for metallic materials is described. Three analytical items are combined: the finite element method with its associated numerical techniques for idealization of the structural component, cyclic plasticity models for idealization of the material behavior, and damage accumulation criteria for the fatigue failure.

Kalev, I.

1980-01-01

278

Cyclic olefins as new hydrogen donor compounds for coal liquefaction  

Microsoft Academic Search

A new set of hydrogen donor compounds, cyclic olefins (CLO), has been evaluated to determine their effectiveness as hydrogen donors to coal. These cyclic olefins are hydroaromatic species which do not contain aromatic rings. The efficacy of these donors has been compared to conventional hydroaromatics. The CLO's under study are 1,4,5,8-tetrahydronaphthalene, also known as isotetralin, and 1,4,5,8,9,10-hexahydroanthracene. In this paper,

M. W. Bedell; C. W. Curtis

1990-01-01

279

Processing of Cosmological Perturbations in a Cyclic Cosmology  

E-print Network

The evolution of the spectrum of cosmological fluctuations from one cycle to the next is studied. It is pointed out that each cycle leads to a reddening of the spectrum. This opens up new ways to generate a scale-invariant spectrum of curvature perturbations. The large increase in the amplitude of the fluctuations quickly leads to a breakdown of the linear theory. More generaly, we see that, after including linearized cosmological perturbations, a cyclic universe cannot be truly cyclic.

Robert H. Brandenberger

2009-05-10

280

Equivalent rate 1\\/2 quasi-cyclic codes (Corresp.)  

Microsoft Academic Search

Chen et al. [1] give a list of quasi-cyclic (2m,m) codes which have the largest minimum distance of any quasi-cyclic code, for various values ofm. We present the weight distribution of these codes. It will be seen that many of the codes found by Chen et al. [1] are equivalent in the sense of having identical weight distributions.

J. Stein; V. Bhargava

1975-01-01

281

Channel equalization for DMT with insufficient cyclic prefix  

Microsoft Academic Search

In discrete multi-tone (DMT) systems a cyclic prefix is added to the front of each modulated symbol-frame in order to partition the whole channel into many narrow independent sub-channels. When the length of the cyclic prefix is shorter than the channel length, inter-carrier interference (ICI) and inter-symbol interference (ISI) will occur in the output signal. This paper presents a decision

Jie Zhu; Wee Ser; Arye Nehorai

2000-01-01

282

The resistance ratchet: theoretical implications of cyclic selection pressure  

Microsoft Academic Search

Results:Underasimulatedannualcyclicselectionpressurevariationof40%,withmaximumresistancerise andfallratesof10and0.5%,respectively,resistanceroseabovethelevelexpectedfromthemeanselection pressure by small ratchet-like increments. Over 50 simulated years, resistance increased to 62%, rather than the 50% expected from the mean level of selection. Welsh community prescribing for a selection of antibiotics showed a seasonal cyclic variation of 13-45%. Conclusions: The intuitive assumption that cyclic selective pressure would produce resistance levels commensurate with the mean selection pressure was

J. T. Magee

2005-01-01

283

Cyclic peptides and depsipeptides from cyanobacteria: A review  

Microsoft Academic Search

An elaborate array of structurally-novel and biologically-active cyclic peptides and depsipeptides are found in blue-green algae (cyanobacteria). Several of these compounds possess structures that are similar to those of natural products from marine invertebrates. Most of these cyclic peptides and depsipeptides, such as the microcystins and the lyngbyatoxins, will probably only be useful as biochemical research tools. A few, however,

R E Moore

1996-01-01

284

The Role of Opportunistic Migration in Cyclic Games  

PubMed Central

We study cyclic evolutionary games in a spatial diluted grid environment in which agents strategically interact locally but can also opportunistically move to other positions within a given migration radius. We find that opportunistic migration can inverse the cyclic prevalence between the strategies when the frequency of random imitation is large enough compared to the payoff-driven imitation. At the transition the average size of the patterns diverges and this threatens diversity of strategies. PMID:24892660

Buesser, Pierre; Tomassini, Marco

2014-01-01

285

Diagnostics for Laser Accelerators  

SciTech Connect

This tutorial paper discusses, at a basic level, some of the diagnostics used in plasma accelerators laboratories. Covered are measurements of laser beams, using probe laser beams to characterize the plasma itself (as opposed to the plasma wave accelerating structure) in various ways, including density fluctuations in the plasma and also static or near-static density structures in the plasma. Also covered are laser probe techniques that are especially suitable for studying the properties of the relativistic electron plasma wave that is ultimately the particle accelerator.

Clayton, C.E. [Department of Electrical Engineering, University of California at Los Angeles, 66-127E Engineering IV Bldg., Los Angeles, CA 90095 (United States)

2004-12-07

286

The MESA accelerator  

NASA Astrophysics Data System (ADS)

The MESA accelerator will operate for particle and nuclear physics experiments in two different modes. A first option is conventional c.w. acceleration yielding 150-200MeV spin-polarized external beam. Second, MESA will be operated as a superconducting multi-turn energy recovery linac (ERL), opening the opportunity to perform experiments with a windowless target with beam current of up to 10 mA. The perspectives for innovative experiments with such a machine are discussed together with a sketch of the accelerator physics issues that have to be solved.

Aulenbacher, Kurt

2013-11-01

287

Cyclic imino ethers in practical step-growth polymerizations  

SciTech Connect

Dicarboxylic acids, glycols, diamines, epoxy resins, phenolics, etc., have significant uses in a variety of thermoplastics and thermosets. Cyclic imino ethers may be used to react with the functionalities on the aforesaid starting compounds, providing practical paths to a host of improved performance materials. For example, the dicarboxylic acid-cyclic imino ether reaction may be employed to produce super tough, poly(amide-ester) thermosets. Or, phenolics may be chain extended and/or crosslinked with cyclic imino ethers to produce poly(amide-ether) thermosets with highly attractive thermal, physical and mechanical properties, with a wide variety of composite applications. In the recycling area, it is also very practical to use cyclic imino ethers to chain extend, i.e., enhance the molecules weight, of recovered polyesters or polyamides to enhance performance of the recovered materials. The use of monomers and polymers containing two or more cyclic imino ether moieties for production of new materials will be discussed. The phenolic hydroxyl-cyclic imino ether reaction will receive the main focus as a practical route to new poly(amide-ether) thermosets, based on the authors experience in using this chemistry to design matrix resins for high performance composities.

Culbertson, B.M. [Ohio State Univ., Columbus, OH (United States)

1993-12-31

288

Charged particle accelerator grating  

DOEpatents

A readily disposable and replaceable accelerator grating for a relativistic particle accelerator is described. The grating is formed for a plurality of liquid droplets that are directed in precisely positioned jet streams to periodically dispose rows of droplets along the borders of a predetermined particle beam path. A plurality of lasers are used to direct laser beams onto the droplets, at predetermined angles, thereby to excite the droplets to support electromagnetic accelerating resonances on their surfaces. Those resonances operate to accelerate and focus particles moving along the beam path. As the droplets are distorted or destroyed by the incoming radiation, they are replaced at a predetermined frequency by other droplets supplied through the jet streams.

Palmer, R.B.

1985-09-09

289

Non-accelerator experiments  

SciTech Connect

This report discusses several topics which can be investigated without the use of accelerators. Topics covered are: (1) proton decay, (2) atmospheric neutrinos, (3) neutrino detection, (4) muons from Cygnus X-3, and (5) the double-beta decay.

Goldhaber, M.

1986-01-01

290

Wake field acceleration experiments  

SciTech Connect

Where and how will wake field acceleration devices find use for other than, possibly, accelerators for high energy physics. I don't know that this can be responsibly answered at this time. What I can do is describe some recent results from an ongoing experimental program at Argonne which support the idea that wake field techniques and devices are potentially important for future accelerators. Perhaps this will spawn expanded interest and even new ideas for the use of this new technology. The Argonne program, and in particular the Advanced Accelerator Test Facility (AATF), has been reported in several fairly recent papers and reports. But because this is a substantially new audience for the subject, I will include a brief review of the program and the facility before describing experiments. 10 refs., 7 figs.

Simpson, J.D.

1988-01-01

291

STUDIES ON BLOOD GLUCOSE, TOTAL PROTEINS, UREA AND CHOLESTEROL LEVELS IN CYCLIC, NON-CYCLIC AND ENDOMETRITIC CROSSBRED COWS  

Microsoft Academic Search

Seventy-five crossbred cows kept at the Livestock Experimental Station, Qadirabad, District Sahiwal were divided into three equal groups i.e. cyclic, non cyclic and endometritic. Blood samples were collected from all the experimental animals, serum was separated and stored at -20C until assayed for glucose (g\\/dl), total protein (g\\/dl), urea (mg\\/dl) and cholesterol (mg\\/dl). The results revealed significantly (P<0.05) higher values

Ijaz Ahmad; L. A. Lodhi; Z. I. Qureshi; M. Younis

2004-01-01

292

Torsion Property and Cyclic Fatigue Fracture Behavior of Nickel-Titanium Endodontic Instruments  

E-print Network

Torsion Property and Cyclic Fatigue Fracture Behavior of Nickel-Titanium Endodontic Instruments gloomice@163.com, d lczhao@hit.edu.cn Keywords: NiTi alloy; Torsion; Cyclic fatigue; Endodontic instrument play a dominant role in fracture initiation during cyclic fatigue fracture. The cyclic number

Zheng, Yufeng

293

Cyclic fatigue-crack propagation in sapphire in air and simulated physiological environments  

E-print Network

Cyclic fatigue-crack propagation in sapphire in air and simulated physiological environments B corrosion (static fatigue) and by cyclic fatigue has been examined in sapphire along (1100) planes in 24°C. Mechanistically, a true cyclic fatigue effect was not found in sapphire as experimentally measured cyclic fatigue

Ritchie, Robert

294

Laser electron accelerator  

Microsoft Academic Search

An intense electromagnetic pulse can create weak plasma oscillations through the action of the nonlinear ponderomotive force. Electrons trapped in the wake can be accelerated to high energy. Existing glass lasers of power density 10 to the 18th W\\/sq cm shone on plasmas of densities 10 to the 18th\\/cu cm can yield gigaelectronvolts of electron energy per centimeter of acceleration

T. Tajima; J. M. Dawson

1979-01-01

295

CEBAF accelerator achievements  

SciTech Connect

In the past decade, nuclear physics users of Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF) have benefited from accelerator physics advances and machine improvements. As of early 2011, CEBAF operates routinely at 6 GeV, with a 12 GeV upgrade underway. This article reports highlights of CEBAF's scientific and technological evolution in the areas of cryomodule refurbishment, RF control, polarized source development, beam transport for parity experiments, magnets and hysteresis handling, beam breakup, and helium refrigerator operational optimization.

Y.C. Chao, M. Drury, C. Hovater, A. Hutton, G.A. Krafft, M. Poelker, C. Reece, M. Tiefenback

2011-06-01

296

Motion with Constant Acceleration  

NSDL National Science Digital Library

The purpose of this experiment is to track the motion for an air cart on a sloped track to fall a distance x with constant acceleration a = g sinq. You will verify that the distance and velocity along the incline are given by the parabola x = xo + vo t +1/2at2 and the line v = vo +at. Finally, you will determine the acceleration due to gravity.

Herman, Russell

2008-02-19

297

Breakthrough: Fermilab Accelerator Technology  

SciTech Connect

There are more than 30,000 particle accelerators in operation around the world. At Fermilab, scientists are collaborating with other laboratories and industry to optimize the manufacturing processes for a new type of powerful accelerator that uses superconducting niobium cavities. Experimenting with unique polishing materials, a Fermilab team has now developed an efficient and environmentally friendly way of creating cavities that can propel particles with more than 30 million volts per meter.

None

2012-04-23

298

Accelerating Cosmologies from Compactification  

Microsoft Academic Search

A solution of the (4+n)-dimensional vacuum Einstein equations is found for which spacetime is compactified on a compact hyperbolic manifold of time-varying volume to a flat four-dimensional FLRW cosmology undergoing accelerated expansion in Einstein conformal frame. This shows that the `no-go' theorem forbidding acceleration in `standard' (time-independent) compactifications of string\\/M-theory does not apply to `cosmological' (time-dependent) hyperbolic compactifications.

Paul K. Townsendand; Mattias N. R. Wohlfarth

2003-01-01

299

Rolamite acceleration sensor  

DOEpatents

A rolamite acceleration sensor which has a failsafe feature including a housing, a pair of rollers, a tension band wrapped in an S shaped fashion around the rollers, wherein the band has a force-generation cut out and a failsafe cut out or weak portion. The failsafe cut out or weak portion breaks when the sensor is subjected to an excessive acceleration so that the sensor fails in an open circuit (non-conducting) state permanently.

Abbin, Joseph P. (Albuquerque, NM); Briner, Clifton F. (Albuquerque, NM); Martin, Samuel B. (Albuquerque, NM)

1993-01-01

300

Rolamite acceleration sensor  

DOEpatents

A rolamite acceleration sensor is described which has a failsafe feature including a housing, a pair of rollers, a tension band wrapped in an S shaped fashion around the rollers, wherein the band has a force-generation cut out and a failsafe cut out or weak portion. The failsafe cut out or weak portion breaks when the sensor is subjected to an excessive acceleration so that the sensor fails in an open circuit (non-conducting) state permanently. 6 figures.

Abbin, J.P.; Briner, C.F.; Martin, S.B.

1993-12-21

301

Uniformly accelerated black holes  

Microsoft Academic Search

The static and stationary C-metric are revisited in a generic framework and\\u000atheir interpretations studied in some detail. Specially those with two event\\u000ahorizons, one for the black hole and another for the acceleration. We found\\u000athat: i) The spacetime of an accelerated static black hole is plagued by either\\u000aconical singularities or lack of smoothness and compactness of the

Patricio S. Letelierand; Samuel R. Oliveira

2001-01-01

302

8-Bromo-cyclic inosine diphosphoribose: towards a selective cyclic ADP-ribose agonist  

PubMed Central

cADPR (cyclic ADP-ribose) is a universal Ca2+ mobilizing second messenger. In T-cells cADPR is involved in sustained Ca2+ release and also in Ca2+ entry. Potential mechanisms for the latter include either capacitative Ca2+ entry, secondary to store depletion by cADPR, or direct activation of the non-selective cation channel TRPM2 (transient receptor potential cation channel, subfamily melastatin, member 2). Here we characterize the molecular target of the newly-described membrane-permeant cADPR agonist 8-Br-N1-cIDPR (8-bromo-cyclic IDP-ribose). 8-Br-N1-cIDPR evoked Ca2+ signalling in the human T-lymphoma cell line Jurkat and in primary rat T-lymphocytes. Ca2+ signalling induced by 8-Br-N1-cIDPR consisted of Ca2+ release and Ca2+ entry. Whereas Ca2+ release was sensitive to both the RyR (ryanodine receptor) blocker RuRed (Ruthenium Red) and the cADPR antagonist 8-Br-cADPR (8-bromo-cyclic ADP-ribose), Ca2+ entry was inhibited by the Ca2+ entry blockers Gd3+ (gadolinium ion) and SKF-96365, as well as by 8-Br-cADPR. To unravel a potential role for TRPM2 in sustained Ca2+ entry evoked by 8-Br-N1-cIDPR, TRPM2 was overexpressed in HEK (human embryonic kidney)-293 cells. However, though activation by H2O2 was enhanced dramatically in those cells, Ca2+ signalling induced by 8-Br-N1-cIDPR was almost unaffected. Similarly, direct analysis of TRPM2 currents did not reveal activation or co-activation of TRPM2 by 8-Br-N1-cIDPR. In summary, the sensitivity to the Ca2+ entry blockers Gd3+ and SKF-96365 is in favour of the concept of capacitative Ca2+ entry, secondary to store depletion by 8-Br-N1-cIDPR. Taken together, 8-Br-N1-cIDPR appears to be the first cADPR agonist affecting Ca2+ release and secondary Ca2+ entry, but without effect on TRPM2. PMID:19492987

Kirchberger, Tanja; Moreau, Christelle; Wagner, Gerd K.; Fliegert, Ralf; Siebrands, Cornelia C.; Nebel, Merle; Schmid, Frederike; Harneit, Angelika; Odoardi, Francesca; Flugel, Alexander; Potter, Barry V. L.; Guse, Andreas H.

2009-01-01

303

Effect of Cyclic Precalcification of Nanotubular TiO2 Layer on the Bioactivity of Titanium Implant  

PubMed Central

The objective of this study is to investigate the effect of cyclic precalcification treatment to impart bioactive properties for titanium implants. Before precalcification, the titanium implants were subjected to blasting using hydroxyapatite (HAp), a resorbable blasting medium (RBM treated), and anodized using an electrolyte containing glycerol, H2O, and NH4F. Precalcification treatment was performed by two different methods, namely, continuous immersion treatment (CIT) and alternate immersion treatment (AIT). In CIT, the RBM treated and anodized titanium implants were immersed in 0.05?M NaH2PO4 solution at 80C and saturated Ca(OH)2 solution at 100C for 20?min, whereas during AIT, they were immersed alternatively in both solutions for 1?min for 20 cycles. Anodizing of the titanium implants enables the formation of self-organized TiO2 nanotubes. Cyclic precalcification treatment imparts a better bioactive property and enables an increase in activation level of the titanium implants. The removal torque values of the RBM treated, CIT treated, and AIT treated titanium implants are 10.8 3.7?Ncm, 17.5 3.5?Ncm, and 28.1 2.4?Ncm, respectively. The findings of the study indicate the cyclic precalcification in an effective surface treatment method that would help accelerate osseointegration and impart bioactive property of titanium implants. PMID:24069596

Park, Il Song; Yang, Eun Jin; Bae, Tae Sung

2013-01-01

304

Cyclic ADP-ribose-mediated insulin secretion and Reg, regenerating gene  

Microsoft Academic Search

Glucose is the primary stimulus of insulin secretion in pancreatic ?-cells of the islets of Langerhans. CD38 has both ADP-ribosyl\\u000a cyclase, which catalyzes the formation of cyclic ADP-ribose from NAD+, and cyclic ADP-ribose hydrolase, which converts cyclic ADP-ribose to ADP-ribose. ATP, produced by glucose metabolism, inhibits\\u000a the cyclic ADP-ribose hydrolase of CD38 and therefore causes cyclic ADP-ribose accumulation in ?-cells.

Hiroshi Okamoto

1999-01-01

305

Effects of exogenous neurotransmitters on contractility and cyclic nucleotide metabolism in the isolated frog ventricle.  

PubMed

A study has been made of the effects of acetylcholine and adrenaline on the metabolism of 3',5'-cyclic nucleotides by the isolated frog ventricle. Measurements of adenosine 3',5'-cyclic monophosphate (cyclic AMP) and guanosine 3',5'-cyclic monophosphate (cyclic GMP) were made: (a) at various times during responses produced by a given concn of acetylcholine (10(-7) M) or adrenaline (10(-6) M); and (b) at fixed times following exposure to different concns of the two agonists. The negative inotropic effect of acetylcholine is accompanied by reciprocal changes in the two cyclic nucleotides: cyclic GMP levels rise and cyclic AMP falls. Both effects are dose-related. A more complex pattern of changes occurs during responses produced by adrenaline. The initial increase in twitch tension is accompanied by a transient reduction in cyclic GMP and by a large increase in cyclic AMP. The rate at which cyclic AMP accumulates is greatest at the time when cyclic GMP levels are maximally depressed. An increase in cyclic GMP, seen later, coincides with a gradual fall in both twitch tension and cyclic AMP. The increments in both cyclic AMP and cyclic GMP, measured when the twitch is maximally potentiated, are dose-related. The magnitude of the decrease in peak twitch tension produced by acetylcholine and of the increase produced by adrenaline correlate closely with corresponding changes in the relative proportion of cyclic AMP: cyclic GMP present in the fibres. The possible significance of the changes in cyclic AMP and cyclic GMP in modulating the response of the ventricle is discussed. PMID:6303351

Singh, J; Flitney, F W

1983-04-01

306

Binding of Regulatory Subunits of Cyclic AMP-Dependent Protein Kinase to Cyclic CMP Agarose  

PubMed Central

The bacterial adenylyl cyclase toxins CyaA from Bordetella pertussis and edema factor from Bacillus anthracis as well as soluble guanylyl cyclase ?1?1 synthesize the cyclic pyrimidine nucleotide cCMP. These data raise the question to which effector proteins cCMP binds. Recently, we reported that cCMP activates the regulatory subunits RI? and RII? of cAMP-dependent protein kinase. In this study, we used two cCMP agarose matrices as novel tools in combination with immunoblotting and mass spectrometry to identify cCMP-binding proteins. In agreement with our functional data, RI? and RII? were identified as cCMP-binding proteins. These data corroborate the notion that cAMP-dependent protein kinase may serve as a cCMP target. PMID:22808067

Zeiser, Johannes; Schroder, Anke; Genieser, Hans-Gottfried; Pich, Andreas; Kaever, Volkhard; Schwede, Frank; Wolter, Sabine; Seifert, Roland

2012-01-01

307

Electrostatic Plasma Accelerator (EPA)  

NASA Technical Reports Server (NTRS)

The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass. The goal of the present program is to demonstrate feasibility of the EPA thruster concept through experimental and theoretical investigations of the EPA acceleration mechanism and discharge chamber performance. Experimental investigations will include operating the test bed ion (TBI) engine as an EPA thruster and parametrically varying the thruster geometry and operating conditions to quantify the electrostatic plasma acceleration effect. The theoretical investigations will include the development of a discharge chamber model which describes the relationships between the engine size, plasma properties, and overall performance. For the EPA thruster to be a viable propulsion concept, overall thruster efficiencies approaching 30% with specific impulses approaching 1000 s must be achieved.

Brophy, John R.; Aston, Graeme

1989-01-01

308

Cyclic Adenosine 3?:5?-Monophosphate in Moss Protonema  

PubMed Central

From the protonema of the moss Funaria hygrometrica (L.) Sibth, a factor indistinguishable from cyclic adenosine 3?:5?-monophosphate (cAMP) has been isolated. The factor stimulated the activity of protein kinase from rabbit skeletal muscle and co-chromatographed with authentic cAMP in two solvent systems. Its ability to stimulate protein kinase activity was completely abolished by 3?:5?-cyclic nucleotide phosphodiesterase, the rate of inactivation being similar to that of authentic cAMP. Based on these properties, this factor is identified as 3?,5?-cAMP. Cyclic AMP could be readily removed from the cells and washing the cells with water reduced the endogenous level of cAMP by 2- to 3-fold. A comparison of cAMP levels by protein kinase and Gilman assays was made. The intracellular levels determined by protein kinase assay were about 7-fold lower than the values obtained by Gilman assay. This discrepancy was due to the presence of unidentified compounds which were completely degraded by 3?:5?-cyclic nucleotide phosphodiesterase. Although these displaced labeled cAMP in the Gilman assay, they did not stimulate the protein kinase activity. The protonema may contain cyclic nucleotides other than cAMP; these will not be detected in the protein kinase assay due to the specificity of this reaction. The crude extracts were found to be unsuitable for assaying cAMP by either method. PMID:16659878

Handa, Avtar Krishan; Johri, Man Mohan

1977-01-01

309

Synthesis of Cyclic Py-Im Polyamide Libraries  

PubMed Central

Cyclic Py-Im polyamides containing two GABA turn units exhibit enhanced DNA binding affinity, but extensive studies of their biological properties have been hindered due to synthetic inaccessibility. A facile modular approach toward cyclic polyamides has been developed via microwave-assisted solid-phase synthesis of hairpin amino acid oligomer intermediates followed by macrocyclization. A focused library of cyclic polyamides 17 targeted to the androgen response element (ARE) and the estrogen response element (ERE) were synthesized in 1217% overall yield. The Fmoc protection strategy also allows for selective modifications on the GABA turn units that have been shown to improve cellular uptake properties. The DNA binding affinities of a library of cyclic polyamides were measured by DNA thermal denaturation assays and compared to the corresponding hairpin polyamides. Fluorescein-labeled cyclic polyamides have been synthesized and imaged via confocal microscopy in A549 and T47D cell lines. The IC50 values of compounds 17 and 911 were determined, revealing remarkably varying levels of cytotoxicity. PMID:23106218

2012-01-01

310

Cyclic mechanical reinforcement of integrin-ligand interactions  

PubMed Central

Summary Cells regulate adhesion in response to internally-generated and externally-applied forces. Integrins connect the extracellular matrix to the cytoskeleton and provide cells with mechanical anchorages and signaling platforms. Here we show that cyclic forces applied to a fibronectinintegrin ?5?1 bond switch the bond from a short-lived state with 1-s lifetime to a long-lived state with 100-s lifetime. We term this phenomenon cyclic mechanical reinforcement as the bond strength remembers the history of force application, accumulates over repeated cycles, but does not require force to be sustained. Cyclic mechanical reinforcement strengthens the fibronectinintegrin ?5?1 bond through the RGD binding site of the ligand with the synergy binding site greatly facilitating the process. A flexible integrin hybrid domain is also important for cyclic mechanical reinforcement. Our results reveal a mechanical regulation of receptorligand interactions and identify a molecular mechanism for cell adhesion strengthening by cyclic forces. PMID:23416109

Kong, Fang; Li, Zhenhai; Parks, William M.; Dumbauld, David W.; Garcia, Andres J.; Mould, A. Paul; Humphries, Martin J.; Zhu, Cheng

2013-01-01

311

Low severity coal liquefaction promoted by cyclic olefins  

SciTech Connect

Low severity coal liquefaction promoted by cyclic olefins offers a means of liquefying coal at low severity conditions. Lower temperature, 350[degrees]C, and lower hydrogen pressure, 500 psi, have been used to perform liquefaction reactions. The presence of the cyclic olefin, hexahydroanthracene, made a substantial difference in the conversion of Illinois No. 6 coal at these low severity conditions. The Researchperformed this quarter was a parametric evaluation of the effect of different parameters on the coal conversion and product distribution from coal. The effect of the parameters on product distribution from hexahydroanthracene was also determined. The work planned for next quarter includes combining the most effective parametric conditions for the low severity reactions and determining their effect. The second part ofthe research performed this quarter involved performing Fourier transform infrared (FTIR) spectroscopy using cyclic olefins. The objective of this study was to determine the feasibility of using FTIR and a heated cell to determine the reaction pathway that occurs in the hydrogen donation reactions from cyclic olefins. The progress made to date includes evaluating the FTIR spectra of cyclic olefins and their expected reaction products. This work is included in this progress report.

Curtis, C.W.

1992-01-01

312

Analysis of cyclic combustion of the coal-water suspension  

NASA Astrophysics Data System (ADS)

Combustion technology of the coal-water suspension creates a number of new possibilities to organize the combustion process fulfilling contemporary requirements, e.g. in the environment protection. Therefore the in-depth analysis is necessary to examine the technical application of coal as a fuel in the form of suspension. The research undertakes the complex investigations of the continuous coal-water suspension as well as cyclic combustion. The cyclic nature of fuel combustion results from the movement of the loose material in the flow contour of the circulating fluidized bed (CFB): combustion chamber, cyclone and downcomer. The experimental results proved that the cyclic change of oxygen concentration around fuel, led to the vital change of both combustion mechanisms and combustion kinetics. The mathematical model of the process of fuel combustion has been presented. Its original concept is based on the allowance for cyclic changes of concentrations of oxygen around the fuel. It enables the prognosis for change of the surface and the centre temperatures as well as mass loss of the fuel during combustion in air, in the fluidized bed and during the cyclic combustion.

Kijo-Kleczkowska, Agnieszka

2011-04-01

313

Association of cyclic-AMP-dependent protein kinase with neurofilaments.  

PubMed Central

Neurofilament preparations isolated from bovine spinal cord contain cyclic-AMP-dependent protein kinase (PKA) activity. Treatment of this preparation with cyclic AMP, to dissociate the regulatory subunit of the kinase from the catalytic subunit, resulted in retention of the kinase activity but loss of cyclic AMP regulation. This suggests that PKA is associated via its catalytic subunit with the neurofilament preparation. The association of exogenous PKA from bovine heart with the neurofilament preparation and with neurofilaments reconstituted from purified neurofilament proteins was also investigated. Either the free catalytic subunit or combinations of the catalytic and regulatory subunits of PKA were incubated with the preparations, and the degree of association was determined as the level of kinase activity that co-sediments with neurofilaments. The results indicate that the free catalytic subunit of PKA co-sediments with neurofilaments reconstituted from purified proteins. The regulatory subunit of PKA from bovine heart, when pre-mixed with the catalytic subunit, decreased the level of kinase that co-sediments with the neurofilament fraction in a dose-dependent manner. This effect of the regulatory subunit was reversed by inclusion of cyclic AMP in the incubation medium before centrifugation. The above findings suggest that the regulatory subunit, when attached to the catalytic subunit, has an inhibitory effect on its association with neurofilaments, with the implication that the association may be a cyclic-AMP-regulated event. Images Fig. 1. PMID:1312331

Dosemeci, A; Pant, H C

1992-01-01

314

Cyclic electron flow around photosystem I is essential for photosynthesis.  

PubMed

Photosynthesis provides at least two routes through which light energy can be used to generate a proton gradient across the thylakoid membrane of chloroplasts, which is subsequently used to synthesize ATP. In the first route, electrons released from water in photosystem II (PSII) are eventually transferred to NADP+ by way of photosystem I (PSI). This linear electron flow is driven by two photochemical reactions that function in series. The cytochrome b6f complex mediates electron transport between the two photosystems and generates the proton gradient (DeltapH). In the second route, driven solely by PSI, electrons can be recycled from either reduced ferredoxin or NADPH to plastoquinone, and subsequently to the cytochrome b6f complex. Such cyclic flow generates DeltapH and thus ATP without the accumulation of reduced species. Whereas linear flow from water to NADP+ is commonly used to explain the function of the light-dependent reactions of photosynthesis, the role of cyclic flow is less clear. In higher plants cyclic flow consists of two partially redundant pathways. Here we have constructed mutants in Arabidopsis thaliana in which both PSI cyclic pathways are impaired, and present evidence that cyclic flow is essential for efficient photosynthesis. PMID:15175756

Munekage, Yuri; Hashimoto, Mihoko; Miyake, Chikahiro; Tomizawa, Ken-ichi; Endo, Tsuyoshi; Tasaka, Masao; Shikanai, Toshiharu

2004-06-01

315

Fermi acceleration in astrophysical jets  

E-print Network

We consider the acceleration of energetic particles by Fermi processes (i.e., diffusive shock acceleration, second order Fermi acceleration, and gradual shear acceleration) in relativistic astrophysical jets, with particular attention given to recent progress in the field of viscous shear acceleration. We analyze the associated acceleration timescales and the resulting particle distributions, and discuss the relevance of these processes for the acceleration of charged particles in the jets of AGNs, GRBs and microquasars, showing that multi-component powerlaw-type particle distributions are likely to occur.

Frank M. Rieger; Valenti Bosch-Ramon; Peter Duffy

2006-10-05

316

Microelectromechanical acceleration-sensing apparatus  

DOEpatents

An acceleration-sensing apparatus is disclosed which includes a moveable shuttle (i.e. a suspended mass) and a latch for capturing and holding the shuttle when an acceleration event is sensed above a predetermined threshold level. The acceleration-sensing apparatus provides a switch closure upon sensing the acceleration event and remains latched in place thereafter. Examples of the acceleration-sensing apparatus are provided which are responsive to an acceleration component in a single direction (i.e. a single-sided device) or to two oppositely-directed acceleration components (i.e. a dual-sided device). A two-stage acceleration-sensing apparatus is also disclosed which can sense two acceleration events separated in time. The acceleration-sensing apparatus of the present invention has applications, for example, in an automotive airbag deployment system.

Lee, Robb M. (Albuquerque, NM); Shul, Randy J. (Albuquerque, NM); Polosky, Marc A. (Albuquerque, NM); Hoke, Darren A. (Albuquerque, NM); Vernon, George E. (Rio Rancho, NM)

2006-12-12

317

Studies of accelerated compact toruses  

SciTech Connect

In an earlier publication we considered acceleration of plasma rings (Compact Torus). Several possible accelerator configurations were suggested and the possibility of focusing the accelerated rings was discussed. In this paper we consider one scheme, acceleration of a ring between coaxial electrodes by a B/sub theta/ field as in a coaxial rail-gun. If the electrodes are conical, a ring accelerated towards the apex of the cone undergoes self-similar compression (focusing) during acceleration. Because the allowable acceleration force, F/sub a/ = kappaU/sub m//R where (kappa < 1), increases as R/sup -2/, the accelerating distance for conical electrodes is considerably shortened over that required for coaxial electrodes. In either case, however, since the accelerating flux can expand as the ring moves, most of the accelerating field energy can be converted into kinetic energy of the ring leading to high efficiency.

Hartman, C.W.; Eddleman, J.; Hammer, J.H.

1983-01-04

318

Accelerating the culture change!  

PubMed

Exide Electronics, a major supplier of uninterruptible power system equipment, embarked on a journey of changing a culture to improve quality, enhance customer responsiveness, and reduce costs. This case study examines the evolution of change over a period of seven years, with particular emphasis on the most recent years, 1992 through 1995. The article focuses on the Raleigh plant operations and describes how each succeeding year built on the successes and fixed the shortcomings of the prior years to accelerate the culture change, including corrective action and continuous improvement processes, organizational structures, expectations, goals, achievements, and pitfalls. The real challenge to changing the culture was structuring a dynamic approach to accelerate change! The presentation also examines how the evolutionary process itself can be created and accelerated through ongoing communication, regular feedback of progress and goals, constant evaluation and direction of the process, and measuring and paying for performance. PMID:10162360

Klunk, S W; Panetta, J; Wooten, J

1996-11-01

319

Superconducting traveling wave accelerators  

NASA Astrophysics Data System (ADS)

The applicability of superconductivity to traveling wave accelerators is considered. Unlike CW operation of a superconducting standing wave or circulating wave accelerator section, which requires improvement factors (superconductor conductivity divided by copper conductivity) of about 10(6) in order to be of practical use, a Superconducting Traveling wave factors as low as about 10(3), which are attainable with niobium or lead at 4.2K, the temperature of liquid helium at atmospheric pressure. Changing from a copper traveling wave accelerator to SUTRA achieves the following: (1) for a given gradient SUTRA reduces the peak and average power requirements typically byu a factor of 2; (2) SUTRA reduces the peak power still further because it enables us to increase the filling time and thus trade pulse width for gradient; (3) SUTRA makes possible a reasonably long section at higher frequencies; and (4) SUTRA makes possible recirculation without additional RF average power.

Farkas, Z. D.

1984-11-01

320

Spectroscopic characterization of the oligomeric surface structures on polyamide materials formed during accelerated aging.  

PubMed

Crystalline surface species were observed at the surface of polyamide 12 materials upon accelerated aging. After detection of the depositions with scanning electron microscopy (SEM), the crystalline surface precipitations were analyzed with Fourier transform infrared (FT-IR) and Raman imaging microscopy. These surface species were supposed to be cyclic oligomers (dimer and trimer) of the PA12 monomer laurolactam, which are usually present in polyamide materials and tend to migrate to the surface when the material is subjected to accelerated aging. The evidence for the chemical identity of the crystalline surface structures to be mainly the cyclic dimer and trimer of laurolactam was given by melting-point identification and mass spectroscopic analysis of the methanol eluate of the surface. The Raman and FT-IR spectra of the mixture were extracted from the recorded images. PMID:21986073

Chernev, Boril S; Eder, Gabriele C

2011-10-01

321

A Smoother Acceleration  

NSDL National Science Digital Library

Some may argue that gifted children have many education options, but these options do not always help gifted students learn science. Unfortunately, gifted students often do not reach their full academic potential--they are frequently less motivated to succeed because they are not being academically challenged in regular classrooms (McCoach and Siegle 2003). To counter these problems, a strong option for educating gifted students is acceleration. This article describes the challenges that more and more gifted students face when accelerating, particularly when skipping an entire academic year. Strategies to lessen their intensity and duration and, ultimately, help gifted students to succeed are also included.

Chapman, Christine

2009-03-01

322

US LHC Accelerator Project  

NSDL National Science Digital Library

As the US part of the Large Hadron Collider Program, US LHC "consists of efforts of Brookhaven National Laboratory (BNL), Fermi National Accelerator Laboratory (FNAL), and Lawrence Berkeley National Laboratory (LBNL) to support the construction of the LHC at CERN." This Web site provides visitors with links to each of the three participating laboratories as well as information on recent papers, reports, and other materials related to the project. While a bit dated, there is also a press release covering the production of the highest energy producing superconducting accelerator in the world; it utilizes over 6,000 superconducting magnets.

323

Micromachined Ion Accelerators  

NASA Technical Reports Server (NTRS)

Proposed ion accelerators made by micromachining techniques. Advantages include small size and weight, modularity, and compatibility with integrated circuits. Used as sources of ion beams for industrial processes. Ion accelerator of this type combined with integrated electronic control and power circuitry, plus similarly miniaturized valves and other mechanisms for regulating flow of gas used to generate ions - all micromachined on single chip. Provides flexibility for tailoring characteristics of ion sources for specific applications; for example, construct array of many such devices to obtain large ion source or position multiple devices to obtain desired ion-beam pattern in processing chamber.

Brophy, John; Mueller, Juergen; Polk, James; Blandino, John

1996-01-01

324

Interfacing to accelerator instrumentation  

SciTech Connect

As the sensory system for an accelerator, the beam instrumentation provides a tremendous amount of diagnostic information. Access to this information can vary from periodic spot checks by operators to high bandwidth data acquisition during studies. In this paper, example applications will illustrate the requirements on interfaces between the control system and the instrumentation hardware. A survey of the major accelerator facilities will identify the most popular interface standards. The impact of developments such as isochronous protocols and embedded digital signal processing will also be discussed.

Shea, T.J.

1995-12-31

325

Paired Accelerated Frames  

E-print Network

The geometrical and quantum mechanical basis for Davies' and Unruh's acceleration temperature is traced to a type of quantum mechanical (``achronal'') spin. Its existence and definition are based on pairs of causally disjoint accelerated frames. For bosons the expected spin vector of monochromatic particles is given by the ``Planckian power'' and the ``r.m.s. thermal fluctuation'' spectra. Under spacetime translation the spin direction precesses around that ``Planckian'' vector. By exhibiting the conserved achronal spin four-current, we extend the identification of achronal spin from single quanta to multiparticle systems. Total achronal spin conservation is also shown to hold, even in the presence of quadratic interactions.

Ulrich H. Gerlach

1999-10-28

326

An accelerator technology legacy  

SciTech Connect

Accelerator technology has been a major beneficiary of the investment made over the last decade. It is the intention of this paper to provide the reader with a glimpse of the broad nature of those advances. Development has been on a broad front and this paper can highlight only a few of those. Two spin-off applications will be outlined -- a concept for a compact, active, beam probe for solar body exploration and the concept for an accelerator-driven transmutation system for energy production.

Heighway, E.A.

1994-11-01

327

High intensity hadron accelerators  

SciTech Connect

This rapporteur report consists mainly of two parts. Part I is an abridged review of the status of all High Intensity Hadron Accelerator projects in the world in semi-tabulated form for quick reference and comparison. Part II is a brief discussion of the salient features of the different technologies involved. The discussion is based mainly on my personal experiences and opinions, tempered, I hope, by the discussions I participated in in the various parallel sessions of the workshop. In addition, appended at the end is my evaluation and expression of the merits of high intensity hadron accelerators as research facilities for nuclear and particle physics.

Teng, L.C.

1989-05-01

328

Photocathodes in accelerator applications  

SciTech Connect

Some electron accelerator applications require bursts of short pulses at high microscopic repetition rates and high peak brightness. A photocathode, illuminated by a mode-locked laser, is well suited to filling this need. The intrinsic brightness of a photoemitter beam is high; experiments are under way at Los Alamos to study the brightness of short bunches with high space charge after acceleration. A laser-illuminated Cs/sub 3/Sb photoemitter is located in the first rf cavity of an injector linac. Diagnostics include a pepper-pot emittance analyzer, a magnetic spectrometer, and a streak camera.

Fraser, J.S.; Sheffield, R.L.; Gray, E.R.; Giles, P.M.; Springer, R.W.; Loebs, V.A.

1987-01-01

329

The SU(3) Algebra in a Cyclic Basis  

E-print Network

With the couplings between the eight gluons constrained by the structure constants of the su(3) algebra in QCD, one would expect that there should exist a special basis (or set of bases) for the algebra wherein, unlike in a Cartan-Weyl basis, {\\em all} gluons interact identically (cyclically) with each other, explicitly on an equal footing. We report here particular such bases, which we have found in a computer search, and we indicate associated $3 \\times 3$ representations. We conjecture that essentially all cyclic bases for su(3) may be obtained from these making appropriate circulant transformations,and that cyclic bases may also exist for other su(n), n>3.

P. F. Harrison; R. Krishnan; W. G. Scott

2014-07-31

330

Fatigue crack growth under general-yielding cyclic-loading  

NASA Technical Reports Server (NTRS)

In low cycle fatigue, cracks are initiated, and propagated under general-yielding cyclic loading. For general-yielding cyclic loading, Dowling and Begley (1976) have shown that fatigue crack growth rate correlates well with the measured Delta J. The correlation of da/dN with Delta J has also been studied by a number of other investigators. However, none of these studies has correlated da/dN with Delta J calculated specifically for the test specimens. Solomon measured fatigue crack growth in specimens in general-yielding cyclic loading. The crack tip fields for Solomon's specimens are calculated, using the finite element method, and the J-values of Solomon's tests are evaluated. The measured crack growth rate in Solomon's specimens correlates very well with the calculated Delta J.

Minzhong, Z.; Liu, H. W.

1986-01-01

331

Fatigue crack growth under general-yielding cyclic-loading  

NASA Technical Reports Server (NTRS)

In low cycle fatigue, cracks are initiated and propagated under general yielding cyclic loading. For general yielding cyclic loading, Dowling and Begley have shown that fatigue crack growth rate correlates well with the measured delta J. The correlation of da/dN with delta J was also studied by a number of other investigators. However, none of thse studies have correlated da/dN with delta J calculated specifically for the test specimens. Solomon measured fatigue crack growth in specimens in general yielding cyclic loading. The crack tips fields for Solomon's specimens are calculated using the finite element method and the J values of Solomon's tests are evaluated. The measured crack growth rate in Solomon's specimens correlates very well with the calculated delta J.

Minzhong, Z.; Liu, H. W.

1986-01-01

332

On the connection between multigrid and cyclic reduction  

NASA Technical Reports Server (NTRS)

A technique is shown whereby it is possible to relate a particular multigrid process to cyclic reduction using purely mathematical arguments. This technique suggest methods for solving Poisson's equation in 1-, 2-, or 3-dimensions with Dirichlet or Neumann boundary conditions. In one dimension the method is exact and, in fact, reduces to cyclic reduction. This provides a valuable reference point for understanding multigrid techniques. The particular multigrid process analyzed is referred to here as Approximate Cyclic Reduction (ACR) and is one of a class known as Multigrid Reduction methods in the literature. It involves one approximation with a known error term. It is possible to relate the error term in this approximation with certain eigenvector components of the error. These are sharply reduced in amplitude by classical relaxation techniques. The approximation can thus be made a very good one.

Merriam, M. L.

1984-01-01

333

Cannabinoid hyperemesis syndrome: a specific cause of cyclical vomiting.  

PubMed

Cyclical vomiting syndrome (CVS) is a disorder that occurs mostly in children, adolescents and young adults in which episodes of nausea and vomiting occur up to six to 12 times per year. In the past decade, one specific cause of cyclical vomiting syndrome, referred to as cannabinoid hyperemesis syndrome (CHS), has been described in a subset of patients who report chronic marijuana use. Of interest, almost all of these patients report compulsive bathing in hot water as part of the syndrome. In this report, we present the case of a 20-year-old female with CHS, review the issues generally encountered in CVS and discuss the known details of CHS. This is an important syndrome that needs to be considered as a potential diagnosis when patients present with cyclical vomiting. PMID:23370905

Morris, Reshmi; Fisher, Martin

2014-01-01

334

Application Of Shakedown Analysis To Cyclic Creep Damage Limits  

SciTech Connect

Shakedown analysis may be used to provide a conservative estimate of local rupture and hence cyclic creep damage for use in a creep-fatigue assessment. The shakedown analysis is based on an elastic-perfectly plastic material with a temperature-dependent pseudo yield stress defined to guarantee that a shakedown solution exists which does not exceed rupture stress and temperature for a defined life. The ratio of design life to the estimated maximum cyclic life is the shakedown creep damage. The methodology does not require stress classification and is also applicable to cycles over the full range of temperature above and below the creep regime. Full cyclic creep and damage analysis is the alternative when shakedown analysis appears to be excessively conservative.

Carter, Peter [Stress Engineering Services Inc.] [Stress Engineering Services Inc.; Jetter, Robert I [Consultant] [Consultant; Sham, Sam [ORNL] [ORNL

2012-01-01

335

Low Severity Coal Liquefaction Promoted by Cyclic Olefins  

SciTech Connect

The development of the donor solvent technology for coal liquefaction has drawn a good deal of attention over the last three decades. The search for better hydrogen donors led investigators to a class of compounds known as cyclic olefins. Cyclic olefins are analogues of the conventional hydroaromatic donor species but do not contain aromatic rings. The cyclic olefins are highly reactive compounds which readily release their hydrogen at temperatures of 200 C or higher. Considerable effort has been o expended toward understanding the process of hydrogen donation. Most of this work was conducted in bomb reactors, with product analysis being carried out after the reaction was complete. Efforts directed towards fundamental studies of these reactions in situ are rare. The current work employs a high temperature and high pressure infrared cell to monitor in situ the concentrations of reactants and products during hydrogen release from hydrogen donor compounds.

Christine W. Curtis

1998-04-09

336

Cyclic AMP system in muscle tissue during prolonged hypokinesia  

NASA Technical Reports Server (NTRS)

Components of the cyclic Adenosine-cyclic-35-monophosphate (AMP) system in the muscle tissue of white rats were studied during 70-75 days of hypokinesia, created by placing the animals in small booths which restricted their movements, and during the readaptation period. In the initial period, cyclic AMP levels and the activities of phosphodiesterase and adenylate cyclase in muscle tissue were increased. The values for these indices were roughly equal for controls and experimental animals during the adaptation period, but on the 70th day of the experiment cAMP levels dropped, phosphodiesterase activity increased, and the stimulative effect of epinephrine on the activity of adenylate cyclase decreased. The indices under study normalized during the readaptation period.

Antipenko, Y. A.; Bubeyev, Y. A.; Korovkin, B. F.; Mikhaleva, N. P.

1980-01-01

337

Cyclic electron transport around photosystem I in washed thylakoids  

SciTech Connect

A cyclic electron transport pathway around photosystem I, involving membrane-bound FNR, is described that is capable of generating both transmembrane electric field and proton gradient. The major distinctive features of this cycle are that it does not require the presence of soluble ferredoxin or NADPH, it is insensitive to antimycin A, and poising with O/sub 2/ is not necessary for its continuous operation. Moss and Bendall previously detected an antimycin-insensitive component in cyclic electron flow supported by ferredoxin, and suggested the existence of an alternative cyclic pathway such as that reported here. Bound ferredoxin that is presumed to be associated with membrane-bound FNR may also take part in this antimycin-insensitive pathway. 13 refs., 4 figs.

Garab, G.; Hind, G.

1986-01-01

338

Post-cyclic transmission in Acanthocephalus tumescens (Acanthocephala: Echinorhynchidae).  

PubMed

The aim of this study was to investigate the post-cyclic transmission of Acanthocephalus tumescens (von Linstow, 1896) from Galaxias maculatus Jenyns to Oncorhynchus mykiss (Walbaum). Wild G. maculatus naturally infected with A. tumescens were fed to cultured rainbow trout, which were sacrificed at the second, third and fourth weeks post infection. Normally attached male and female acanthocephalans were recovered alive from the intestine of rainbow trout. Parasites survive at least four weeks post infection, growing and attaining full sexual maturity. Prevalence and mean intensity generally decreased after infection. A. tumescens is the eighth acanthocephalan species in which post-cyclic transmission has been proven. PMID:12194485

Rauque, Carlos A; Semenas, Liliana G; Viozzi, Gustavo P

2002-01-01

339

The Physics Hypertextbook: Acceleration  

NSDL National Science Digital Library

This online tutorial offers support in understanding acceleration from both a conceptual and a quantitative framework. It features a discussion of key concepts, practice problems with answers provided, and a list of links to related activities for high school students. This resource is part of an online textbook in introductory physics.

Elert, Glenn

2006-10-19

340

Precocity and Acceleration.  

ERIC Educational Resources Information Center

This article discusses how schools can best meet the needs of precocious children by giving them access to higher level and more challenging instructional materials. Findings from a study of 40 precocious third and fourth graders are described and the benefits of acceleration are highlighted, particularly grade advancement and advanced placement

Feldhusen, John F.

2003-01-01

341

Radioisotope Dating with Accelerators.  

ERIC Educational Resources Information Center

Explains a new method of detecting radioactive isotopes by counting their accelerated ions rather than the atoms that decay during the counting period. This method increases the sensitivity by several orders of magnitude, and allows one to find the ages of much older and smaller samples. (GA)

Muller, Richard A.

1979-01-01

342

Acceleration and Mass  

NSDL National Science Digital Library

Although this lab is not an inquiry activity, it is very important in learning about acceleration and mass. It is a deeply held misconception among students that objects of different masses fall at different rates. Simply explaining that this is not true

Horton, Michael

2009-05-30

343

Acceleration of Time Integration  

SciTech Connect

We outline our strategies for accelerating time integration for long-running simulations, such as those for global climate modeling. The strategies target the Cray XT systems at the National Center for Computational Sciences at Oak Ridge National Laboratory. Our strategies include fully implicit, parallel-in-time, and curvelet methods.

White III, James B [ORNL; Drake, John B [ORNL; Worley, Patrick H [ORNL; Archibald, Richard K [ORNL; Evans, Katherine J [ORNL; Kothe, Douglas B [ORNL

2007-01-01

344

Plasma based accelerators  

SciTech Connect

A plasma medium can support a variety of wave motions which may be useful for accelerating charged particles. For highly relativistic beams the longitudinal electrostatic wave is most suitable and may be driven by laser or by particle beams. The basic principles, limitations and prospects for these devices are discussed.

Evans, R.G.

1987-05-05

345

Pulsed electromagnetic gas acceleration  

NASA Technical Reports Server (NTRS)

Detailed measurements of the axial velocity profile and electromagnetic structure of a high power, quasi-steady MPD discharge are used to formulate a gasdynamic model of the acceleration process. Conceptually dividing the accelerated plasma into an inner flow and an outer flow, it is found that more than two-thirds of the total power in the plasma is deposited in the inner flow, accelerating it to an exhaust velocity of 12.5 km/sec. The outer flow, which is accelerated to a velocity of only 6.2 km/sec, appears to provide a current conduction path between the inner flow and the anode. Related cathode studies have shown that the critical current for the onset of terminal voltage fluctuations, which was recently shown to be a function of the cathode area, appears to reach an asymptote for cathodes of very large surface area. Detailed floating potential measurements show that the fluctuations are confined to the vicinity of the cathode and hence reflect a cathode emission process rather than a fundamental limit on MPD performance.

Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

1974-01-01

346

Galactic Acceleration Phenomena  

NASA Astrophysics Data System (ADS)

I will review the current status of our observational knowledge of prominent classes of particle accelerators in the Galaxy, especially shell-type supernova remnants (SNRs) and pulsar wind nebulae. I will highlight in particular the contribution of the recent improvement in sensitivity of very-high-energy (VHE) gamma-ray observations, which are currently the most direct probe of particle acceleration in the Galaxy up to energies of several hundreds of TeV. Shell-type SNRs have long been proposed as sources of the Galactic cosmic rays, through Fermi acceleration at their outer blast waves. In recent years, X-ray observations have revealed very thin, non-thermal rims in many young SNRs, and I will discuss the implications of these observations of synchrotron emission from accelerated electrons, in particular for magnetic field amplification and the maximum accelerated particle energy attainable in these shock waves. I will then review the current status of the evidence for high-energy nuclei in these objects, especially in view of recent VHE gamma-ray observations. I will summarise current uncertainties and outline prospects for future progress through greater multi-wavelength studies. As a result of the survey of the Galactic plane in VHE gamma-rays undertaken by the HESS experiment, the most numerous class of identified Galactic VHE sources is currently that of pulsar wind nebulae (PWNe), also known as plerionic SNRs. In these objects, the VHE gamma-ray emission is generally thought to be dominantly leptonic, and I will outline the complementarity between the results of these observations and the better-known X-ray observations of synchrotron emission. I will discuss the evolutionary problems posed by the large observed sizes of several of the new gamma-ray pulsar wind nebulae, and outline prospects for progress in our understanding of these objects.

Gallant, Y. A.

2006-08-01

347

Accelerator applications of engineered media  

NASA Astrophysics Data System (ADS)

Material properties are vital for the field of accelerator R&D. Euclid Techlabs in collaboration with the Argonne Wakefield Accelerator facility team has investigated accelerator applications of metamaterials, photonic band gap structures, nonlinear, paramagnetic and ferroelectric materials. In this paper we will present results of our work on advanced accelerating structures and accelerating applications of engineered materials. These will include wakefield test of a photonic band gap accelerating structure, design of a dielectric loaded structure with built in tunable paramagnetic absorption mechanism and beam diagnostics applications of metamaterials.

Antipov, Sergey

2010-11-01

348

An accelerating section with a constant acceleration rate  

SciTech Connect

An accelerating section with varying cross section and 2..pi../3 working oscillation phase has been designed, built, and tested. The experimental results at low powers and in the acceleration mode are in satisfactory agreement with calculated results.

Zykov, A.I.; Kondratenko, V.V.; Kramskoi, G.D.; Mondrus, I.N.; Ryabtsov, A.V.; Smirnov, V.L.; Terekhov, B.A.; Chikatash, I.A.

1982-11-01

349

Novel Cyclic Sugar Imines: Carbohydrate Mimics and Easily  

E-print Network

Novel Cyclic Sugar Imines: Carbohydrate Mimics and Easily Elaborated Scaffolds for Aza (e.g., DNJ) imines not only are potential carbohydrate- processing enzyme inhibitors that may for a nitrogen atom.1 The often potent inhibitory activity of many of these compounds toward carbohydrate

Davis, Ben G.

350

Multiple Residence and Cyclical Migration: A Life Course Perspective  

Microsoft Academic Search

As a result of restrictive time-space bounds in viewing migration, surprisingly little is known about the tempos and rhythms of geographical mobility in America. We discuss limitations of the conventional definition of migration and develop a life course framework of multiple residence and cyclical migration. Results of an Arizona-based case study reveal that multiple residence is common and more diverse

Kevin E. McHugh; Timothy D. Hogan; Stephen K. Happel

1995-01-01

351

Damage evolution ahead of sharp notches under cyclic loading  

Microsoft Academic Search

The evolution of cyclic damage ahead of sharp notches has been investigated experimentally. The results are analyzed in terms of a loading parameter ?Bvm which is derived from averaging the calculated local stress and strain distribution at the notch root over some microstructure related size scale. This loading parameter is suggested to bridge the gap between the stress controlled crack

S. Shn; M. Schaper; V. B. Pham; B. Wurm; Th. Husert; E. Winschuh; G. Jaeger

1996-01-01

352

Continuum of Mechanisms for Nucleophilic Substitutions of Cyclic Acetals  

PubMed Central

The effect of nucleophile strength on diastereoselectivity in the nucleophilic substitution of cyclic acetals was explored. Stereoselectivity remained constant and high as nucleophilicity increased until a threshold value was reached. Beyond this point, however, selection of Lewis acid determined whether stereochemical inversion or erosion was observed. PMID:18844363

Krumper, Jennifer R.; Salamant, Walter A.; Woerpel, K. A.

2009-01-01

353

Mechanism of Tetracaine Block of Cyclic Nucleotide-gated Channels  

Microsoft Academic Search

Local anesthetics are a diverse group of ion channel blockers that can be used to probe conforma- tional changes in the pore. We examined the effects of the local anesthetic tetracaine on rod and olfactory cyclic nucleotide-gated channels expressed from subunit 1 in Xenopus oocytes. We found that 40 m M tetracaine effec- tively blocked the bovine rod channel but

Anthony A. Fodor; Sharona E. Gordon; William N. Zagotta

1997-01-01

354

Improving the Biopharmaceutical Properties of Cyclic Opioid Peptide Prodrugs  

E-print Network

microsomes and human recombinant cytochrome P450-3A4 (hCYP3A4). The sites of metabolite formation were located on the Tyr1 and Phe4 amino acids. New cyclic prodrug analogs of CA-DADLE, CA-[Cha4,D-Leu5]-Enk and CA-[Cha4,D-Ala5]-Enk were designed, synthesized...

Nofsinger, Rebecca Anne

2008-05-05

355

Cyclic material properties tests supporting elastic-plastic analysis development  

Microsoft Academic Search

Correlation studies have shown that hardening models currently available in the ABAQUS finite element code (isotropic, kinematic) do not accurately capture the inelastic strain reversals that occur due to structural rebounding from a rapidly applied transient dynamic load. The purpose of the Cyclic Material properties Test program was to obtain response data for the first several cycles of inelastic strain

S. C. Hodge; J. M. Minicucci

1996-01-01

356

Cyclic Irrigation of Turfgrass Using a Shallow Saline Aquifer  

Microsoft Academic Search

water as a supplemental irrigation source on landscapes would free up potable water for higher priority uses, A 2-yr cyclic irrigation study using shallow saline groundwater lower water tables in contact with structural founda- was conducted on a sports field in southern Nevada (bermudagrass (Cynodon dactylon L. 'Tifway') overseeded with perennial ryegrass tions, reduce the potential of contaminating the primary

C. M. Schaan; D. A. Devitt; R. L. Morris; L. Clark

2003-01-01

357

Preference cyclicity and money pumping in a virtual economy  

Microsoft Academic Search

Agents with transitive or cyclical preferences will pay to undo exchanges for which they had previously paid transaction costs. Such agents can be money pumped actively, by a knowing party that offers them a sequence of exchanges tailored eventually to strip them of all their assets, or passively by the accumulation of cases in which they reverse previous exchanges at

David Spurrett; John McCoy; Don Ross; Ben Murrell

358

Automorphism groups with cyclic commutator subgroup and Hamilton cycles  

E-print Network

Automorphism groups with cyclic commutator subgroup and Hamilton cycles Edward Dobson Heather Witte Department of Mathematics and Statistics Department of Mathematics Simon Fraser University the commutator subgroup of G is "small" in some sense. In this vein, K. Keating and D. Witte [KW] used a method

Morris, Joy

359

Nonlinearities and Cyclical Behavior: The Role of Chartists and Fundamentalists  

Microsoft Academic Search

We develop a behavioral exchange rate model with chartists and fundamentalists to study cyclical behavior in foreign exchange markets. Within our model, the market impact of fundamentalists depends on the strength of their belief in fundamental analysis. Estimation of a STAR GARCH model shows that the more the exchange rate deviates from its fundamental value, the more fundamentalists leave the

Frank H. Westerhoff

2003-01-01

360

Transcription of the yeast mitochondrial genome requires cyclic AMP  

Microsoft Academic Search

Using various mutant strains and nutritional manipulations, we investigated a potential role for cyclic AMP (cAMP) in the regulation of mitochondrial (mt) gene expression in the yeast Saccharomyces cerevisiae. In RAS mutants known to have either abnormally low or high cellular levels of this nucleotide, we show that both mt transcription rate and overall mt transcript levels vary directly with

Catherine M. McEntee; Robin Cantwell; Mahboob U. Rahman; Alan P. Hudson

1993-01-01

361

Cyclic Guanosine Monophosphate Compartmentation in Rat Cardiac Myocytes  

Microsoft Academic Search

BackgroundCyclic guanosine monophosphate (cGMP) is the common second messenger for the cardiovascular effects of nitric oxide (NO) and natriuretic peptides, such as atrial or brain natriuretic peptide, which activate the soluble and particulate forms of guanylyl cyclase, respectively. However, natriuretic peptides and NO donors exert different effects on cardiac and vascular smooth muscle function. We therefore tested whether these differences

Liliana R. V. Castro; Ignacio Verde; Dermot M. F. Cooper; Rodolphe Fischmeister

2006-01-01

362

Cyclic nucleotide crosstalk and the regulation of cerebral vasodilation  

Microsoft Academic Search

The vasodilating capability of cerebral vessels is vital to brain survival. There are multiple mechanisms participating in the regulation of cerebral vascular smooth muscle relaxation. The cyclic nucleotide-related signal transduction pathways are particularly important to the vasodilating function of cerebral arteries and arterioles. Those pathways are involved in the vasodilations elicited by a wide variety of stimuli, which include hypoxia

D. A Pelligrino; Qiong Wang

1998-01-01

363

Cyclic Gas\\/Steam Stimulation of Heavy-Oil Wells  

Microsoft Academic Search

Injecting air with steam nearly doubled oil production from three cyclic steam stimulations in a California reservoir producing 11\\/degree\\/API (0.99-g\\/cm³) oil. Computer model studies reveal several reasons for better oil recovery, including greater pressure drawdown, gas drive of heated oil near the well, and trapped residual gas deep in the reservoir. 10 refs.

Robert Meldau; Robert Shipley; Keith Coats

1981-01-01

364

Why Cyclic Steam Predictive Models Get No Respect  

Microsoft Academic Search

This paper analyzes the reasons for the lack of wide acceptance of analytical cyclic-steam models for well stimulation. A reservoir-specific model is presented that provides excellent history-matching results for a California heavy-oil project. Finally, several parameter-optimization projections that were carried to economic limit on a present-worth basis are presented.

Jeff Jones

1992-01-01

365

Cold Lake Cyclic Steam Stimulation: A Multiwell Process  

Microsoft Academic Search

Cyclic steam stimulation (CSS) typically is thought of as a single-well process. At Cold Lake, however, where steam injectivity is achieved by fracturing the formation, considerable interwell communication is observed. The result is usually the watering out of a producer by condensed steam from a neighboring injector. These interwell interactions greatly complicate steam-injection scheduling for commercial projects involving hundreds of

E. Vittoratos; G. R. Scott; C. I. Beattie

1990-01-01

366

Method for conducting cyclic steam injection in recovery of hydrocarbons  

Microsoft Academic Search

In the cyclic method of steam stimulation of an oil well, steam is injected for a period of from several days to several weeks, then stopped and usually after a time-- generally a few days--during which the steam is allowed to diffuse through the formation, the well is produced. There is considerable uncertainty in the art as to how long

A. Satter; F. F. Jr. Craig

1969-01-01

367

Why cyclic steam predictive models get no respect  

SciTech Connect

This paper analyzes the reasons for the lack of wide acceptance of analytical cyclic-steam models for well stimulation. A reservoir-specific model is presented that provides excellent history-matching results for a California heavy-oil project. Finally, several parameter-optimization projections that were carried to economic limit on a present-worth basis are presented.

Jones, J. (Santa Fe Energy Resources Inc. Co. (US))

1992-02-01

368

Cyclic gas/steam stimulation of heavy-oil wells  

SciTech Connect

Injecting air with steam nearly doubled oil production from three cyclic steam stimulations in a California reservoir producing 11/degree/API (0.99-g/cm/sup 3/) oil. Computer model studies reveal several reasons for better oil recovery, including greater pressure drawdown, gas drive of heated oil near the well, and trapped residual gas deep in the reservoir. 10 refs.

Meldau, R.F.; Shipley, R.G.; Coats, K.H.

1981-10-01

369

CYCLIC TRINUCLEAR GOLD(I) COMPOUNDS: SYNTHESIS, STRUCTURES AND  

E-print Network

, e.g. Hg(II) complexes.[2] Metal-metal inter- actions reach a maximum for the gold compounds where, structural investigations, reactivity, and supramolecular aggregation of cyclic trinuclear gold(I) complexes, Table 1. 1.1. Synthesis The first CTC gold(I) compound was reported by Vaughan in 1970.[5] The complex

Abdou, Hanan E.

370

Cyclic AMP negatively regulates prodigiosin production by Serratia marcescens  

Microsoft Academic Search

Many Serratia marcescens strains produce the red pigment prodigiosin, which has antimicrobial and anti-tumor properties. Previous reports suggest that cyclic AMP (cAMP) is a positive regulator of prodigiosin production. Supporting this model, the addition of glucose to growth medium inhibited pigment production in rich and minimal media. Unexpectedly, we observed highly elevated levels of prodigiosin production in isogenic strains with

Eric J. Kalivoda; Nicholas A. Stella; Marissa A. Aston; James E. Fender; Paul P. Thompson; Regis P. Kowalski; Robert M. Q. Shanks

2010-01-01

371

Repeated indentation method for studying cyclic fatigue in ceramics  

Microsoft Academic Search

A new method for studying cyclic fatigue in ceramics is proposed. It is based on the repeated indentation of the ceramic surface with a sharp indenter and on the relation between the indentation load and the number of indentation cycles needed to produce chipping. The technique is analyzed on the basis of observation on the development of the lateral cracks

Michael Reece; Frank Guiu

1990-01-01

372

Effects of cyclic hydraulic pressure on osteocytes , Yan Zhao b  

E-print Network

Effects of cyclic hydraulic pressure on osteocytes Chao Liu a , Yan Zhao b , Wing-Yee Cheung b , Ronak Gandhi c , Liyun Wang d , Lidan You a,b, a Department of Mechanical and Industrial Engineering: Osteocyte Mechanotransduction Hydraulic pressure Calcium Apoptosis Bone is able to adapt its composition

You, Lidan

373

The Cyclic Barzilai-Borwein Method for Unconstrained Optimization  

Microsoft Academic Search

In the cyclic Barzilai-Borwein (CBB) method, the same BB stepsize is reused for m consecutive iterations. It is proved that CBB is locally linearly convergent at a local minimizer with positive deflnite Hessian. Numerical evidence indicates that when m > n=2 3, CBB is locally superlinearly convergent. In the special case m = 3 and n = 2, it is

Yu-Hong Daiy; William W. Hager; Klaus Schittkowski; Hongchao Zhang

374

Geometric angles in cyclic evolutions of a classical system  

NASA Technical Reports Server (NTRS)

A perturbative method, using Lie transforms, is given for calculating the Hannay angle for slow, cyclic evolutions of a classical system, taking into account the finite rate of change of the Hamiltonian. The method is applied to the generalized harmonic oscillator. The classical Aharonov-Anandan angle is also calculated. The interpretational ambiguity in the definitions of geometrical angles is discussed.

Bhattacharjee, A.; Sen, Tanaji

1988-01-01

375

A genus six cyclic tetragonal reduction of the Benney equations  

E-print Network

A reduction of Benney's equations is constructed corresponding to Schwartz-Christoffel maps associated with a family of genus six cyclic tetragonal curves. The mapping function, a second kind Abelian integral on the associated Riemann surface, is constructed explicitly as a rational expression in derivatives of the Kleinian sigma-function of the curve.

Matthew England; John Gibbons

2009-03-30

376

CYCLIC GENETIC ALGORITHMS FOR THE LOCOMOTION OF HEXAPOD ROBOTS  

E-print Network

CYCLIC GENETIC ALGORITHMS FOR THE LOCOMOTION OF HEXAPOD ROBOTS GARY B. PARKER and GREGORY J. E, adaptive gait development for hexapod robots, was the impetus for this new kind of evolutionary computation, but it can be applied to other robotics domains. KEYWORDS: genetic, evolutionary, robot, hexapod, gait

Parker, Gary B.

377

Technical Report No. 494 Using Cyclic Genetic Algorithms  

E-print Network

automata for a small hexapod robot are generated by a cyclic genetic algorithm. From these automata of the hexapod's ``nervous system'' is part of a general environment for experimentation with multi involves a form of genetic algorithm generating locomotion control in very simple hexapod agents. Frequent

Parker, Gary B.

378

Technical Report No. 494 Using Cyclic Genetic Algorithms  

E-print Network

for a small hexapod robot are generated by a cyclic genetic algorithm. From these automata a Xilinx net list the communication network of an experimental robot colony. This recon guration of the hexapod's nervous system locomotion control in very simple hexapod agents. Frequent redesign of agent control is part of the evolving

Portland State University

379

CYCLIC GENETIC ALGORITHMS FOR EVOLVING MULTI-LOOP CONTROL PROGRAMS  

E-print Network

, genetic algorithms, sensors, learning, search, hexapod 1. INTRODUCTION The Cyclic Genetic Algorithm (CGA for hexapod gaits and area coverage path planning. However, in order for a robot to react properly to sensor walls and locate the desired target. The agent modeled in simulation is a hexapod robot equipped

Parker, Gary B.

380

CYCLIC GENETIC ALGORITHMS FOR EVOLVING MULTILOOP CONTROL PROGRAMS  

E-print Network

algorithms, sensors, learning, search, hexapod 1. INTRODUCTION Cyclic Genetic Algorithm (CGA), a variant of traditional successfully been used evolve single loop control programs hexapod gaits and area coverage path modeled simulation a hexapod robot equipped with sensors. The task of learning search behavior autonomous

Parker, Gary B.

381

Tadpole Labelled Oriented Graph Groups and Cyclically Presented Groups  

E-print Network

Tadpole Labelled Oriented Graph Groups and Cyclically Presented Groups James Howiea , Gerald-Watt University, Edinburgh EH14 4AS, U.K. bDepartment of Mathematical Sciences, University of Essex, Colchester, Essex CO4 3SQ, U.K. Abstract We study a class of Labelled Oriented Graph (LOG) group where

Howie, Jim

382

Analysis and optimization of cyclic methods in orbit computation  

NASA Technical Reports Server (NTRS)

The mathematical analysis and computation of the K=3, order 4; K=4, order 6; and K=5, order 7 cyclic methods and the K=5, order 6 Cowell method and some results of optimizing the 3 backpoint cyclic multistep methods for solving ordinary differential equations are presented. Cyclic methods have the advantage over traditional methods of having higher order for a given number of backpoints while at the same time having more free parameters. After considering several error sources the primary source for the cyclic methods has been isolated. The free parameters for three backpoint methods were used to minimize the effects of some of these error sources. They now yield more accuracy with the same computing time as Cowell's method on selected problems. This work is being extended to the five backpoint methods. The analysis and optimization are more difficult here since the matrices are larger and the dimension of the optimizing space is larger. Indications are that the primary error source can be reduced. This will still leave several parameters free to minimize other sources.

Pierce, S.

1973-01-01

383

Robust Nonparametric Cyclic Correlation Based Spectrum Sensing for Cognitive Radio  

Microsoft Academic Search

Cognitive radios sense the radio spectrum in order to find underutilized spectrum and then exploit it in an agile man- ner. Spectrum sensing has to be performed reliably in challeng- ing propagation environments characterized by shadowing and fading effects as well as heavy-tailed noise distributions. In this paper a robust computationally efficient nonparametric cyclic correlation estimator based on the multivariate

Jarmo Lunden; Saleem A. Kassam; Visa Koivunen

2009-01-01

384

Constitutive modeling of cyclic plasticity with emphasis on ratchetting  

Microsoft Academic Search

Constitutive modeling of cyclic plasticity for ratchetting has advanced significantly in the last about five years. Ohno and Wang [1, 2] contributed to the modeling by formulating the kinematic hardening model based on the critical state of dynamic recovery of back stress. This paper describes the characteristics of their model and its applications to uniaxial, multiaxial and thermal ratchettings as

N. Ohno

1998-01-01

385

A plasticity model for multiaxial cyclic loading and ratchetting  

Microsoft Academic Search

Summary The nonlinear behavior of metals when subjected to monotonic and cyclic non-proportional loading is modeled using the proposed hardening rule. The model is based on the Chaboche [1], [2] and Voyiadjis and Sivakumar [3], [4] models incorporating the bounding surface concept. The evolution of the backstress is governed by the deviatoric stress rate direction, the plastic strain rate, the

G. Z. Voyiadjis; I. N. Basuroychowdhury

1998-01-01

386

The Demographic Composition of Cyclical Variations in Employment.  

ERIC Educational Resources Information Center

This paper analyzes the demographic patterns of cyclical swings in the labor market by decomposing movement in employment into changes in unemployment and participation. The focus is on the interrelations among participation, employment and unemployment, with particular emphasis on the participation rate as a prime determinant of the labor market

Clark, Kim B.; Summers, Lawrence H.

387

Cyclic mechanical property degradation during fatigue loading of cortical bone  

Microsoft Academic Search

Fatigue damage accumulation has been demonstrated in living bone and postulated as a stimulus to the bone modeling and remodeling response. Mechanical property degradation is one manifestation of fatigue damage accumulation. This study examines changes in secant modulus and cyclic energy dissipation behavior during axial load-controlled fatigue loading of cortical bone specimens. The findings suggest that secant modulus degradation and

C. A. Pattin; W. E. Caler; D. R. Carter

1996-01-01

388

Counting Subgroups in a Direct Product of Finite Cyclic Groups  

ERIC Educational Resources Information Center

We calculate the number of subgroups in a direct product of finite cyclic groups by applying the fundamental theorem of finite abelian groups and a well-known structure theorem due to Goursat. We also suggest ways in which the results can be generalized to a direct product of arbitrary finite groups.

Petrillo, Joseph

2011-01-01

389

A Simulation of Counter-Cyclical Intervention: Some Practical Lessons  

ERIC Educational Resources Information Center

The author introduces a simulation of counter-cyclical interventions that highlights important issues surrounding the practice of government intervention. The simulation provides experiential insight as to why economists have long debated the degree of persistence exhibited by disequilibrating shocks and connects this debate to discussions about

Grawe, Nathan D.; Watts, Michael, Ed.

2007-01-01

390

Cyclic GMP Release by Acute Enhanced External Counterpulsation  

Microsoft Academic Search

Background: Enhanced external counterpulsation (EECP) is a noninvasive, pneumatic technique that provides favorable effects in patients with coronary artery disease and heart failure. The mechanisms by which EECP exerts its beneficial effects remain poorly understood. Cyclic GMP (cGMP) regulates vascular smooth muscle tone that may improve arterial function. We investigated the effect of a single session of EECP on plasma

Jaime Levenson; Marie G. Pernollet; Marie C. Iliou; Marie A. Devynck; Alain Simon

2006-01-01

391

The liquefaction of clayey soils under cyclic loading  

Microsoft Academic Search

This paper seeks to investigate the liquefaction of clayey soils, a phenomenon that has been the trigger for many natural disasters in the last few decades, including landslides. Research was conducted on artificial claysand mixtures and natural clayey soils collected from the sliding surfaces of earthquake-induced landslides. The undrained response of normally consolidated clayey soils to cyclic loading was studied

Ivan B. Gratchev; Kyoji Sassa; Victor I. Osipov; Viatcheslav N. Sokolov

2006-01-01

392

Atomic collapse in graphene and cyclic RG flow  

E-print Network

In this Letter we consider the problem of screening of external charge in graphene from the cyclic RG flow viewpoint. The analogy with conformal Calogero model is used to suggest the interpretation of the tower of resonant states as tower of Efimov states.

Alexander Gorsky; Fedor Popov

2013-12-28

393

Synthesis and characterization of cyclic acetal based degradable hydrogels  

Microsoft Academic Search

While many synthetic, hydrolytically degradable hydrogels have been developed for biomedical applications, there are only a few examples whose polymer backbone does not form acidic products upon degradation. In order to address this concern, we proposed to develop a hydrogel based on a cyclic acetal unit that produces diols and propanals upon hydrolytic degradation. In particular, we proposed the fabrication

Sachiko Kaihara; Shuichi Matsumura; John P. Fisher

2008-01-01

394

Efficient DMT\\/OFDM Transmission With Insufficient Cyclic Prefix  

Microsoft Academic Search

In this letter, we describe a new method to eliminate intersymbol interference (ISI) and interchannel interference (ICI) for discrete multitone\\/orthogonal frequency division multiplexing (DMT\\/OFDM) systems with insufficient cyclic prefix (CP). The proposed structure prevents ICI with a preprocessing method that utilizes redundancy in the frequency domain at the transmitter and removes ISI with a simple cancellation method at the receiver.

Cheol-Jin Park; Gi-Hong Im

2004-01-01

395

MODELING CYCLIC WAVES OF CIRCULATING T CELLS IN AUTOIMMUNE DIABETES  

E-print Network

MODELING CYCLIC WAVES OF CIRCULATING T CELLS IN AUTOIMMUNE DIABETES JOSEPH M. MAHAFFY AND LEAH EDELSTEIN-KESHET Abstract. Type 1 diabetes (T1D) is an autoimmune disease in which immune cells, notably T-lymphocytes target and kill the insulin-secreting pancreatic beta cells. Elevated blood sugar levels and full blown

Mahaffy, Joseph M.

396

Skill Retention and Relearning--A Proposed Cyclical Model.  

ERIC Educational Resources Information Center

The relationship between relearning and retention was examined during refresher training for 53 Israeli soldiers operating an electronic system. The longer the training interval, the lower the operator's performance level. Partial simulation was suitable for retraining in complex tasks. A cyclical behavior model of learning, forgetting, and

Ginzburg, S.; Dar-El, E. M.

2000-01-01

397

Imperfect Financial Markets and the Cyclicality of Social Transfers  

E-print Network

to endogenous risk premia because the government cannot commit to repay its debt. The government conducts debt for financing government ex- penditures (Reinhart and Rogoff 2011) and face countercyclical of government expenditure that the cyclical correlation of social spending exhibits the biggest differences

Nesterov, Yurii

398

Electrospun Polydioxanone, Elastin, and Collagen Vascular Scaffolds: Uniaxial Cyclic Distension  

Microsoft Academic Search

The development of vascular grafts requires the matching of material and viscoelastic properties to those of native artery. The hypothesis of this study was to subject electrospun tissue engineering scaffolds composed of polydioxanone, elastin, and collagen to cyclic loading in order to quantify the hysteretic properties, uniaxial tensile mechanical properties of conditioned scaffolds, and stress relaxation properties over a period

Michael J. McClure; Scott A. Sell; David G. Simpson; Gary L. Bowlin

2009-01-01

399

Passive cyclic pitch control for horizontal axis wind turbines  

NASA Technical Reports Server (NTRS)

A flexible rotor concept, called the balanced pitch rotor, is described. The system provides passive adjustment of cyclic pitch in response to unbalanced pitching moments across the rotor disk. Various applications are described and performance predictions are made for wind shear and cross wind operating conditions. Comparisons with the teetered hub are made and significant cost savings are predicted.

Bottrell, G. W.

1981-01-01

400

Cyclic, pseudocyclic and noncyclic photophosphorylation: new links in  

E-print Network

, California, showed that isolated chloroplasts are capable of direct, light-dependent synthesis of ATP, a reaction they called photosynthetic phosphorylation [1]. Albert Frenkel then found the same direct, light to absorption of light by chlorophyll (Fig. 1a) suggested a cyclic reaction. The Berkeley group then showed

Allen, John F.

401

High-temperature cyclic oxidation data. Part 2: Turbine alloys  

NASA Technical Reports Server (NTRS)

Specific-weight-change-versus-time data and x ray diffraction results are presented derived from high temperature cyclic tests on high temperature, high strength nickel-base gamma/gamma prime and cobalt-base turbine alloys. Each page of data summarizes a complete test on a given alloy sample.

Barrett, Charles A.; Garlick, Ralph G.

1989-01-01

402

Cyclic Properties of Superelastic Shape Memory Alloy Wires and Bars  

Microsoft Academic Search

This study evaluates the properties of superelastic Ni-Ti shape memory alloys under cyclic loading to assess their potential for applications in seismic resistant design and retrofit. Shape memory alloy wire and bars are tested to evaluate the effect of bar size and loading history on the strength, equivalent damping, and recentering properties of the shape memory alloys in superelastic form.

Reginald DesRoches; Jason McCormick; Michael Delemont

2004-01-01

403

Resonant Column and Cyclic Triaxial Testing of Tailing Dam Material  

Microsoft Academic Search

Aseries of resonant column and cyclic triaxial tests has been conducted in the frame of the analysis of tailing dam stability during earthquakes, The investigation program for a silty sand fro m uranium tailings is presented. The paper describes the testing procedures and presents all significant results of these experiments, Single-stage and multi-stage resonant co lumn tests were performed in

S. A. Savidis; C. Vrettos

404

Finite element analysis of the cyclic indentation of bilayer enamel  

NASA Astrophysics Data System (ADS)

Tooth enamel is often subjected to repeated contact and often experiences contact deformation in daily life. The mechanical strength of the enamel determines the biofunctionality of the tooth. Considering the variation of the rod arrangement in outer and inner enamel, we approximate enamel as a bilayer structure and perform finite element analysis of the cyclic indentation of the bilayer structure, to mimic the repeated contact of enamel during mastication. The dynamic deformation behaviour of both the inner enamel and the bilayer enamel is examined. The material parameters of the inner and outer enamel used in the analysis are obtained by fitting the finite element results with the experimental nanoindentation results. The penetration depth per cycle at the quasi-steady state is used to describe the depth propagation speed, which exhibits a two-stage power-law dependence on the maximum indentation load and the amplitude of the cyclic load, respectively. The continuous penetration of the indenter reflects the propagation of the plastic zone during cyclic indentation, which is related to the energy dissipation. The outer enamel serves as a protective layer due to its great resistance to contact deformation in comparison to the inner enamel. The larger equivalent plastic strain and lower stresses in the inner enamel during cyclic indentation, as calculated from the finite element analysis, indicate better crack/fracture resistance of the inner enamel.

Jia, Yunfei; Xuan, Fu-zhen; Chen, Xiaoping; Yang, Fuqian

2014-04-01

405

Parametric analysis of a passive cyclic control device for helicopters  

NASA Technical Reports Server (NTRS)

A parametric study of a passive device which provides a cyclic longitudinal control moment for a helicopter rotor was performed. It utilizes a rotor blade tip which is structurally decoupled from the blade inboard section. This rotor configuration is generally called the Free-Tip Rotor. A two dimensional numerical model was used to review the Constant Lift Tip Rotor, a predecessor of the current configuration, and then the same model was applied to the Passive Cyclic Control Device. The Constant Lift Tip was proven to have the ability to suppress the vibratory lift loading on the tip around the azimuth and to eliminate a significant negative lift peak on the advancing tip. The Passive Cyclic Control Device showed a once-per-revolution lift oscillation with a large amplitude, while minimizing the higher harmonic terms of the lift oscillation. This once-per-revolution oscillation results in the cyclic moment to trim the rotor longitudinally. A rotor performance analysis was performed by a three dimensional numerical model. It indicated that the vortices shed from the junction between the tip and the inboard section has a strong influence on the tip, and it may severely limit the tip performance. It was also shown that the Free-Tip allows the inboard section to have a larger twist, which results in a better performance.

Kumagai, H.

1984-01-01

406

Periodic travelling waves in cyclic populations: field studies and  

E-print Network

-year cycles (table 1). The same period has seen significant advances in the mathematical understandingREVIEW Periodic travelling waves in cyclic populations: field studies and reaction­diffusion models Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK Periodic travelling waves have been reported

Sherratt, Jonathan A.

407

Behavior of nonplastic silty soils under cyclic loading.  

PubMed

The engineering behavior of nonplastic silts is more difficult to characterize than is the behavior of clay or sand. Especially, behavior of silty soils is important in view of the seismicity of several regions of alluvial deposits in the world, such as the United States, China, and Turkey. In several hazards substantial ground deformation, reduced bearing capacity, and liquefaction of silty soils have been attributed to excess pore pressure generation during dynamic loading. In this paper, an experimental study of the pore water pressure generation of silty soils was conducted by cyclic triaxial tests on samples of reconstituted soils by the slurry deposition method. In all tests silty samples which have different clay percentages were studied under different cyclic stress ratios. The results have showed that in soils having clay content equal to and less than 10%, the excess pore pressure ratio buildup was quicker with an increase in different cyclic stress ratios. When fine and clay content increases, excess pore water pressure decreases constant cyclic stress ratio in nonplastic silty soils. In addition, the applicability of the used criteria for the assessment of liquefaction susceptibility of fine grained soils is examined using laboratory test results. PMID:24672343

Ural, Nazile; Gunduz, Zeki

2014-01-01

408

Evidence for a messenger function of cyclic GMP during phosphodiesterase induction in Dictyostelium discoideum.  

PubMed Central

Chemotactic stimulation of vegetative or aggregative Dictyostelium discoideum cells induced a transient elevation of cyclic GMP levels. The addition of chemoattractants to postvegetative cells by pulsing induced phosphodiesterase activity. The following lines of evidence suggest a messenger function for cyclic GMP in the induction of phosphodiesterase: (i) Folic acid and cyclic AMP increased cyclic GMP levels and induced phosphodiesterase activity. (ii) Cyclic AMP induced both cyclic GMP accumulation and phosphodiesterase activity by binding to a rate receptor. (iii) The effects of chemical modification of cyclic AMP or folic acid on cyclic GMP accumulation and phosphodiesterase induction were closely correlated. (iv) A close correlation existed between the increase of cyclic GMP levels and the amount of phosphodiesterase induced, independent of the type of chemoattractant by which this cyclic GMP accumulation was produced. (v) Computer simulation of cyclic GMP binding to intracellular cyclic GMP-binding proteins indicates that half-maximal occupation by cyclic GMP required the same chemoattractant concentration as did half-maximal phosphodiesterase induction. PMID:6288659

van Haastert, P J; Pasveer, F J; van der Meer, R C; van der Heijden, P R; van Walsum, H; Konijn, T M

1982-01-01

409

Advanced accelerator simulation research: miniaturizing accelerators from kilometers to meters  

E-print Network

as well as more mainstream problems in accelerator physics, such as the electron cloud instability in this quest. One of the goals of the SciDAC Accelerator Modeling Project is to develop code and software-scale experiments. We describe the existing hierarchy of software tools for modelling advanced accelerators, how

Geddes, Cameron Guy Robinson

410

Acceleration and Classical Electromagnetic Radiation  

E-print Network

Classical radiation from an accelerated charge is reviewed along with the reciprocal topic of accelerated observers detecting radiation from a static charge. This review commemerates Bahram Mashhoon's 60th birthday.

E. N. Glass

2008-01-09

411

Accelerated Insertion of Materials - Composites.  

National Technical Information Service (NTIS)

The objective of the Accelerated Insertion of Materials - Composites (AIM-C) program is to develop and validate new approaches for materials development that will accelerate the insertion of materials into production hardware.

G. Havskjold

2001-01-01

412

Cyclic Oxidation Modeling Program Rewritten for MS Windows  

NASA Technical Reports Server (NTRS)

Turbine superalloy components are subject to high-temperature oxidation during operation. Protection is often conferred by coatings designed to form slow-growing, adherent oxide scales. Degradation by oxidation is exacerbated by the thermal cycling encountered during normal aircraft operations. Cooling has been identified as the major contributor to stresses in the oxidation scales, and it may often cause some oxide scale spallation with a proportional loss of protective behavior. Overall oxidation resistance is, thus, studied by the weight change behavior of alloy coupons during high-temperature cyclic oxidation in furnace or burner rig tests. The various characteristics of this behavior are crucial in understanding the performance of alloys at high temperatures. This new modeling effort helps in the understanding of the major factors involved in the cyclic oxidation process. Weight change behavior in cyclic oxidation is typified by an initial parabolic weight gain response curve that eventually exhibits a maximum, then transitions into a linear rate of weight loss due to spalling. The overall shape and magnitude of the curve are determined by the parabolic growth rate, kp, the cycle duration, the type of oxide scale, and the regular, repetitive spalling process. This entire process was modeled by a computer program called the Cyclic Oxidation Spalling Program (COSP) previously developed at the NASA Glenn Research Center. Thus, by supplying appropriate oxidation input parameters, one can determine the best fit to the actual data. These parameters describe real behavior and can be used to compare alloys and project cyclic oxidation behavior for longer times or under different cycle frequencies.

Smialek, James L.; Auping, Judith V.

2002-01-01

413

Scaling behavior of cyclical roughness and maximal height of growing surfaces  

NASA Astrophysics Data System (ADS)

Two new problems in kinetic surface roughening, namely, the scaling behavior of cyclical growth and that of the maximal height, are investigated using a variety of analytical approaches as well as extensive numerical simulations. The scaling behavior of roughness is studied for surfaces grown by two alternating primary processes, typically deposition and desorption. To characterize the roughness in such cyclical processes, we have generalized the dynamic scaling hypothesis by replacing the time by the number of cycles n. In the early-time regime, the roughness is predicted to grow as nb . The roughness saturates to its maximal value in the late-time regime, which scales with the system size L as L alpha. The relations between the cyclical exponents and the corresponding exponents of the primary processes are explored. Exact results are obtained for linear primary processes, whereas an approximate renormalization scheme is employed to analyze nonlinear effects in the primary processes. Numerical simulations of atomistic growth models support the analytical results. When the distribution of the application times of the primary processes has a power law tail and a diverging mean, the dynamic and growth exponents change continuously with that power. In many realistic situations the maximal (or minimal) height of a growing surface is the most relevant characteristic of the surface. Scaling arguments are combined with the extremal value theory of independent random variables to infer that the maximal height relative to the average grows as tbln L-baln t+C 1/a in the early-time regime. Thus it increases logarithmically slower than the roughness. In the late-time regime of saturated roughness, the maximal height relative to the average increases as Lalpha , as does the roughness. Exact results for the maximal height of some specific models with a 1D Brownian curve behavior are derived. Numerical simulations of various surface growth models are consistent with our analytical predictions. Potential applications of these results include accelerated testing of rechargeable batteries, breakdown predictions and improved cancer treatment.

Raychaudhuri, Subhadip

2002-09-01

414

How amines accelerate delignification  

SciTech Connect

In soda pulping with primary aliphatic amines and diamines, the rate of delignification varies with the initial molar amount of amine. At a given temperature and time, the reciprocal of the kappa number of a pulp and the number of moles of amine initially introduced show a linear relationship that is valid at concentrations of amine below those at which phase separation occurs. On a molar basis, primary amines were six to ten times less efficient than hydrosulfide ion as accelerators of delignification, and 400-1200 times less efficient than anthraquinone. We propose that the primary role of the amine is to accelerate the delignification reaction through a chemical rather than physical mechanism. (Refs. 10).

Abbot, J.; Bolker, H.I.

1982-02-01

415

Hypervelocity plate acceleration  

SciTech Connect

Shock tubes have been used to accelerate 1.5-mm-thick stainless steel plates to high velocity while retaining their integrity. The fast shock tubes are 5.1-cm-diameter, 15.2-cm-long cylinders of PBX-9501 explosive containing a 1.1-cm-diameter cylindrical core of low-density polystyrene foam. The plates have been placed directly in contact with one face of the explosive system. Plane-wave detonation was initiated on the opposite face. A Mach disk was formed in the imploding styrofoam core, which provided the impulse required to accelerate the metal plate to high velocity. Parametric studies were made on this system to find the effect of varying plate metal, plate thickness, foam properties, and addition of a barrel. A maximum plate velocity of 9.0 km/s has been observed. 6 refs., 17 figs.

Marsh, S.P.; Tan, T.H.

1991-01-01

416

Adaptive control for accelerators  

DOEpatents

An adaptive feedforward control loop is provided to stabilize accelerator beam loading of the radio frequency field in an accelerator cavity during successive pulses of the beam into the cavity. A digital signal processor enables an adaptive algorithm to generate a feedforward error correcting signal functionally determined by the feedback error obtained by a beam pulse loading the cavity after the previous correcting signal was applied to the cavity. Each cavity feedforward correcting signal is successively stored in the digital processor and modified by the feedback error resulting from its application to generate the next feedforward error correcting signal. A feedforward error correcting signal is generated by the digital processor in advance of the beam pulse to enable a composite correcting signal and the beam pulse to arrive concurrently at the cavity.

Eaton, Lawrie E. (Los Alamos, NM); Jachim, Stephen P. (Los Alamos, NM); Natter, Eckard F. (Santa Fe, NM)

1991-01-01

417

Ion sources for accelerators  

NASA Astrophysics Data System (ADS)

A survey of different types of ion sources used for accelerator applications is given. Typical problems like the source life time, or the special need for technical solutions for specific elements will demonstrate the advantage of each type of ion source. In any case reliability is a main topic. Besides the plasma generation of the desired element, beam formation and beam transport to the accelerator are discussed. The influence of space charge on the beam transport can be of great importance if there is no space-charge compensation. Typical results achieved at GSI will be given for the following source types: Penning Ion Source (PIG), Electron Cyclotron Resonance (ECR), Cold or Hot Reflex Discharge Ion Source (CHORDIS), Multicusp Ion Source (MUCIS) and MEVVA.

Spdtke, P.; Bossler, J.; Emig, H.; Leible, K. D.; Mhle, C.; Schulte, H.; Tinschert, K.

1998-04-01

418

SUPERDIFFUSIVE SHOCK ACCELERATION  

SciTech Connect

The theory of diffusive shock acceleration is extended to the case of superdiffusive transport, i.e., when the mean square deviation grows proportionally to t{sup {alpha}}, with {alpha} > 1. Superdiffusion can be described by a statistical process called Levy random walk, in which the propagator is not a Gaussian but it exhibits power-law tails. By using the propagator appropriate for Levy random walk, it is found that the indices of energy spectra of particles are harder than those obtained where a normal diffusion is envisaged, with the spectral index decreasing with the increase of {alpha}. A new scaling for the acceleration time is also found, allowing substantially shorter times than in the case of normal diffusion. Within this framework we can explain a number of observations of flat spectra in various astrophysical and heliospheric contexts, for instance, for the Crab Nebula and the termination shock of the solar wind.

Perri, S.; Zimbardo, G. [Dipartimento di Fisica, Universita della Calabria, Ponte P. Bucci Cubo 31C, I-87036 Rende (Italy)

2012-05-10

419

Commissioning the GTA accelerator  

SciTech Connect

The Ground Test Accelerator (GTA) is supported by the Strategic Defense command as part of their Neutral Particle Beam (NPB) program. Neutral particles have the advantage that in space they are unaffected by the earth`s magnetic field and travel in straight lines unless they enter the earth`s atmosphere and become charged by stripping. Heavy particles are difficult to stop and can probe the interior of space vehicles; hence, NPB can function as a discriminator between warheads and decoys. We are using GTA to resolve the physics and engineering issues related to accelerating, focusing, and steering a high-brightness, high-current H{sup -} beam and then neutralizing it. Our immediate goal is to produce a 24-MeV, 50mA device with a 2% duty factor.

Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Bowling, S.; Brown, S.; Cole, R.; Gilpatrick, J.D.; Garnett, R.; Guy, F.W.; Ingalls, W.B.; Johnson, K.F.; Kerstiens, D.; Little, C.; Lohsen, R.A.; Lloyd, S.; Lysenko, W.P.; Mottershead, C.T.; Neuschaefer, G.; Power, J.; Rusthoi, D.P.; Sandoval, D.P. Stevens, R.R. Jr.; Vaughn, G.; Wadlinger, E.A.; Yuan, V. [Los Alamos National Lab., NM (United States); Connolly, R.; Weiss, R. [Grumman Space and Electronics Corp., Princeton, NJ (United States); Saadatmand, K. [Grumman Corp., Bethpage, NY (United States). Corporate Research Center

1992-09-01

420

Commissioning the GTA accelerator  

SciTech Connect

The Ground Test Accelerator (GTA) is supported by the Strategic Defense command as part of their Neutral Particle Beam (NPB) program. Neutral particles have the advantage that in space they are unaffected by the earth's magnetic field and travel in straight lines unless they enter the earth's atmosphere and become charged by stripping. Heavy particles are difficult to stop and can probe the interior of space vehicles; hence, NPB can function as a discriminator between warheads and decoys. We are using GTA to resolve the physics and engineering issues related to accelerating, focusing, and steering a high-brightness, high-current H{sup -} beam and then neutralizing it. Our immediate goal is to produce a 24-MeV, 50mA device with a 2% duty factor.

Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Bowling, S.; Brown, S.; Cole, R.; Gilpatrick, J.D.; Garnett, R.; Guy, F.W.; Ingalls, W.B.; Johnson, K.F.; Kerstiens, D.; Little, C.; Lohsen, R.A.; Lloyd, S.; Lysenko, W.P.; Mottershead, C.T.; Neuschaefer, G.; Power, J.; Rusthoi, D.P.; Sandoval, D.P. Stevens, R.R. Jr.; Vaughn, G.; Wadlinger, E.A.; Yuan, V. (Los Alamos National Lab., NM (United States)); Connolly, R.; Weiss, R. (Gr

1992-01-01

421

Pulsed electromagnetic gas acceleration  

NASA Technical Reports Server (NTRS)

Experimental data were combined with one-dimensional conservation relations to yield information on the energy deposition ratio in a parallel-plate accelerator, where the downstream flow was confined to a constant area channel. Approximately 70% of the total input power was detected in the exhaust flow, of which only about 20% appeared as directed kinetic energy, thus implying that a downstream expansion to convert chamber enthalpy into kinetic energy must be an important aspect of conventional high power MPD arcs. Spectroscopic experiments on a quasi-steady MPD argon accelerator verified the presence of A(III) and the absence of A(I), and indicated an azimuthal structure in the jet related to the mass injection locations. Measurements of pressure in the arc chamber and impact pressure in the exhaust jet using a piezocrystal backed by a Plexiglas rod were in good agreement with the electromagnetic thrust model.

Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

1971-01-01

422

Exploring Acceleration with an Android  

NSDL National Science Digital Library

Students conduct an experiment to study the acceleration of a mobile Android device. During the experiment, they run an application created with MIT's App Inventor that monitors linear acceleration in one-dimension. Students use an acceleration vs. time equation to construct an approximate velocity vs. time graph. Students will understand the relationship between the object's mass and acceleration and how that relates to the force applied to the object, which is Newton's second law of motion.

IMPART RET Program, College of Information Science & Technology,

423

Overview of accelerators in medicine  

SciTech Connect

Accelerators used for medicine include synchrotrons, cyclotrons, betatrons, microtrons, and electron, proton, and light ion linacs. Some accelerators which were formerly found only at physics laboratories are now being considered for use in hospital-based treatment and diagnostic facilities. This paper presents typical operating parameters for medical accelerators and gives specific examples of clinical applications for each type of accelerator, with emphasis on recent developments in the field.

Lennox, A.J. [Fermi National Accelerator Lab., Batavia, IL (US)]|[Rush Univ., Chicago, IL (US)

1993-06-01

424

Principles of Charged Particle Acceleration  

NSDL National Science Digital Library

This learning resources comprise a healthy introduction to charged particle acceleration. The site, by Stanley Humphries, a professor of electrical and computer engineering at University of New Mexico, amounts to an online textbook (.pdf) introducing the theory of charged particle acceleration. The book's fifteen chapters (with bibliography) summarize "the principles underlying all particle accelerators" and provide "a reference collection of equations and material essential to accelerator development and beam applications."

425

Cyclic exchange neighborhood search technique for the K-means clustering problem  

E-print Network

Cyclic Exchange is an application of the cyclic transfers neighborhood search technique for the k-means clustering problem. Neighbors of a feasible solution are obtained by moving points between clusters in a cycle. This ...

Thirathon, Nattavude, 1980-

2004-01-01

426

7 CFR 1412.33 - Payment yield for counter-cyclical payments for covered commodities.  

Code of Federal Regulations, 2010 CFR

...FOR THE 2008 AND SUBSEQUENT CROP YEARS Establishment of Yields for Direct and Counter-Cyclical...Counter cyclical payment yields for designated oilseeds or eligible pulse crops for which direct payment yields were not established as...

2010-01-01

427

Cyclic nucleotide responses and radiation-induced mitotic delay in Physarum polycephalum  

SciTech Connect

The response of the plasmodial levels of cyclic AMP and cyclic GMP in Physarum polycephalum to several putative phosphodiesterase inhibitors and to ionizing radiation has been measured. Isobutylmethylxanthine (2 mM) induces a rapid transient threefold elevation of cyclic AMP alone, with maximum response in about 10 min and return to the base line in about 30 min. Theophylline (2 mM) induces a rapid, sustained twofold elevation of cyclic GMP only. Caffeine (2mM) and Ro-20-1724 (18 ..mu..M) both elicit a rapid transient rise in cyclic AMP, resembling the isobutylmethylxanthine response, and a slow transient elevation of the cyclic GMP level. Of particular interest is the rapid threefold transient elevation of the cyclic AMP, but not of the cyclic GMP, level by ..gamma.. radiation.

Daniel, J.W.; Oleinick, N.L.

1984-02-01

428

Fermi National Accelerator Laboratory  

NSDL National Science Digital Library

Fermi National Accelerator Laboratory advances the understanding of the fundamental nature of matter and energy by providing leadership and resources for qualified researchers to conduct basic research at the frontiers of high energy physics and related disciplines. Fermilab's mission is to advance the understanding of the fundamental nature of matter and energy. Fermilab's world-class scientific research facility allows qualified researchers from around the world to conduct fundamental research at the frontiers of high-energy physics and related disciplines.

2009-05-18

429

Modulational effects in accelerators  

SciTech Connect

We discuss effects of field modulations in accelerators, specifically those that can be used for operational beam diagnostics and beam halo control. In transverse beam dynamics, combined effects of nonlinear resonances and tune modulations influence diffusion rates with applied tune modulation has been demonstrated. In the longitudinal domain, applied RF phase and voltage modulations provide mechanisms for parasitic halo transport, useful in slow crystal extraction. Experimental experiences with transverse tune and RF modulations are also discussed.

Satogata, T.

1997-12-01

430

A laser accelerator  

Microsoft Academic Search

We show that a laser can efficiently accelerate charged particles if a magnetic field is introduced to improve the coupling\\u000a between the particle and the wave. Solving the relativistic equations of motion for an electron in a uniform magnetic field\\u000a and superposed, circularly polarized electromagnetic wave, we find that in energy-position phase space an electron traces\\u000a out a curtate cycloid:

W. B. Colson; S. K. Ride

1979-01-01

431

Dielectric Stimulated Wakefield Accelerator  

Microsoft Academic Search

Wakefield acceleration in a dielectric-loaded waveguide has been previously analyzed and tested.(M. Rosing and W. Gai, Phys. Rev. D 42), 1829 (1990).^,3 We note that a dielectric geometry can be found in which the wakefield is a nearly-periodic function of z - ct, and that the multi-mode wakefield period and interbunch spacing can coincide. Thus, superposition of wakes can occur.

T. B. Zhang; J. L. Hirshfield; T. C. Marshall; B. Hafizi

1997-01-01

432

Linear induction accelerator  

DOEpatents

A linear induction accelerator includes a plurality of adder cavities arranged in a series and provided in a structure which is evacuated so that a vacuum inductance is provided between each adder cavity and the structure. An energy storage system for the adder cavities includes a pulsed current source and a respective plurality of bipolar converting networks connected thereto. The bipolar high-voltage, high-repetition-rate square pulse train sets and resets the cavities. 4 figs.

Buttram, M.T.; Ginn, J.W.

1988-06-21

433

Classifier Acceleration by Imitation  

Microsoft Academic Search

\\u000a This paper presents a framework named Classifier Molding that imitates arbitrary classifiers by linear regression trees\\u000a so as to accelerate classification speed. This framework requires an accurate (but slow) classifier and large amount of training\\u000a data. As an example of accurate classifier, we used the Compound Similarity Method (CSM) for Industrial Ink Jet Printer (IIJP)\\u000a character recognition problem. The input-output

Takahiro Ota; Toshikazu Wada; Takayuki Nakamura

2010-01-01

434

Progress of RIBF accelerators  

NASA Astrophysics Data System (ADS)

In order to greatly expand scientific opportunities with radioactive isotope (RI) beams, RIKEN has constructed a new heavy-ion accelerator facility, called "RI Beam Factory (RIBF)." Three new ring cyclotrons with K-values of 570 MeV, 980 MeV, and 2600 MeV, respectively, boost the energies of the output beams from the existing K540-MeV ring cyclotron up to 440 MeV/u for light ions and 345 MeV/u for very heavy ions. These energetic heavy-ion beams are converted into intense radioactive isotope (RI) beams via projectile fragmentation of stable isotopes or in-flight fission of uranium isotopes by a superconducting fragment separator, BigRIPS. The three ring cyclotrons were commissioned in 2006, and RI beams from uranium were first obtained in 2007. The beam intensities and available ion species are increasing at RIBF, owing to the continuous efforts that have been made since the first beam. So far, we have accelerated deuteron, helium, nitrogen, oxygen, aluminum, calcium, zinc, krypton, xenon, and uranium beams with the superconducting ring cyclotron (SRC). The extracted beam intensities reached 1000 pnA for the helium and oxygen beams, and the calcium beam intensity exceeded 400 pnA recently. The intensities of the xenon and uranium beams are also increasing; they reached 24 and 3.6 pnA, respectively. This paper illustrates the construction, commissioning, and various improvements carried out for the RIBF accelerators, as well as the present accelerator performance.

Okuno, H.; Fukunishi, N.; Kamigaito, O.

2012-12-01

435

Asymmetric synthesis of gem-diaryl substituted cyclic sulfamidates and sulfamides by rhodium-catalyzed arylation of cyclic ketimines.  

PubMed

Asymmetric addition of arylboronates to aryl-substituted cyclic ketimines proceeded in the presence of a rhodium catalyst coordinated with a chiral diene ligand to give high yields of sulfamidates and sulfamides with high enantioselectivity (up to 99% ee). PMID:23661175

Nishimura, Takahiro; Ebe, Yusuke; Fujimoto, Hiroto; Hayashi, Tamio

2013-06-18

436

Electrostatic Plasma Accelerator (EPA)  

NASA Technical Reports Server (NTRS)

The application of electric propulsion to communications satellites, however, has been limited to the use of hydrazine thrusters with electric heaters for thrust and specific impulse augmentation. These electrothermal thrusters operate at specific impulse levels of approximately 300 s with heater powers of about 500 W. Low power arcjets (1-3 kW) are currently being investigated as a way to increase specific impulse levels to approximately 500 s. Ion propulsion systems can easily produce specific impulses of 3000 s or greater, but have yet to be applied to communications satellites. The reasons most often given for not using ion propulsion systems are their high level of overall complexity, low thrust with long burn times, and the difficulty of integrating the propulsion system into existing commercial spacecraft busses. The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass.

Brophy, John R.; Aston, Graeme

1995-01-01

437

Accelerated Profile HMM Searches.  

PubMed

Profile hidden Markov models (profile HMMs) and probabilistic inference methods have made important contributions to the theory of sequence database homology search. However, practical use of profile HMM methods has been hindered by the computational expense of existing software implementations. Here I describe an acceleration heuristic for profile HMMs, the "multiple segment Viterbi" (MSV) algorithm. The MSV algorithm computes an optimal sum of multiple ungapped local alignment segments using a striped vector-parallel approach previously described for fast Smith/Waterman alignment. MSV scores follow the same statistical distribution as gapped optimal local alignment scores, allowing rapid evaluation of significance of an MSV score and thus facilitating its use as a heuristic filter. I also describe a 20-fold acceleration of the standard profile HMM Forward/Backward algorithms using a method I call "sparse rescaling". These methods are assembled in a pipeline in which high-scoring MSV hits are passed on for reanalysis with the full HMM Forward/Backward algorithm. This accelerated pipeline is implemented in the freely available HMMER3 software package. Performance benchmarks show that the use of the heuristic MSV filter sacrifices negligible sensitivity compared to unaccelerated profile HMM searches. HMMER3 is substantially more sensitive and 100- to 1000-fold faster than HMMER2. HMMER3 is now about as fast as BLAST for protein searches. PMID:22039361

Eddy, Sean R

2011-10-01

438

TRACKING ACCELERATOR SETTINGS.  

SciTech Connect

Recording setting changes within an accelerator facility provides information that can be used to answer questions about when, why, and how changes were made to some accelerator system. This can be very useful during normal operations, but can also aid with security concerns and in detecting unusual software behavior. The Set History System (SHS) is a new client-server system developed at the Collider-Accelerator Department of Brookhaven National Laboratory to provide these capabilities. The SHS has been operational for over two years and currently stores about IOOK settings per day into a commercial database management system. The SHS system consists of a server written in Java, client tools written in both Java and C++, and a web interface for querying the database of setting changes. The design of the SHS focuses on performance, portability, and a minimal impact on database resources. In this paper, we present an overview of the system design along with benchmark results showing the performance and reliability of the SHS over the last year.

D OTTAVIO,T.; FU, W.; OTTAVIO, D.P.

2007-10-15

439

Oxidised cosmic acceleration  

SciTech Connect

We give detailed proofs of several new no-go theorems for constructing flat four-dimensional accelerating universes from warped dimensional reduction. These new theorems improve upon previous ones by weakening the energy conditions, by including time-dependent compactifications, and by treating accelerated expansion that is not precisely de Sitter. We show that de Sitter expansion violates the higher-dimensional null energy condition (NEC) if the compactification manifold M is one-dimensional, if its intrinsic Ricci scalar R-ring vanishes everywhere, or if R-ring and the warp function satisfy a simple limit condition. If expansion is not de Sitter, we establish threshold equation-of-state parameters w below which accelerated expansion must be transient. Below the threshold w there are bounds on the number of e-foldings of expansion. If M is one-dimensional or R-ring everywhere vanishing, exceeding the bound implies the NEC is violated. If R-ring does not vanish everywhere on M, exceeding the bound implies the strong energy condition (SEC) is violated. Observationally, the w thresholds indicate that experiments with finite resolution in w can cleanly discriminate between different models which satisfy or violate the relevant energy conditions.

Wesley, Daniel H., E-mail: D.H.Wesley@damtp.cam.ac.uk [Centre for Theoretical Cosmology, DAMTP, Cambridge University, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

2009-01-15

440

Linear accelerator output variability.  

PubMed

The Wellington Cancer Centre is equipped with two matched linear accelerators (Varian 2100CD) linear accelerators (identified as SN1027 and SN42). Each morning, before treatments commence, a radiation therapist carries out an output constancy check of the radiation output and every fortnight a physicist measures, in a phantom, the delivered radiation dose to check on the machine calibration. The daily output checks have been recorded into a database (Argus QA for Radiation Oncology) since August 1997 and in June 1998 the fortnightly calibration measurements were added. The information in the database, up to April 2003, has been analysed to consider the quality of the daily constancy checks as compared with the fortnightly calibration measurements and whether the data contains useful information on machine performance. After allowance for the effects of machine recalibration the fortnightly calibration measurements had an average standard deviation of 0.4% and the daily constancy checks 0.8%. The daily constancy checks had a greater number of large deviations than would be expected assuming a normal distribution and were not a good predictor of the need for a recalibration. The fortnightly calibration measurements with a much lower spread give a reliable indication of the need for a recalibration allowing the adoption of a +/- 1% tolerance. Over the period analysed one accelerator (SN42) was relatively stable with the output generally drifting between +/- 1% while the other (SN1027) had a consistent increase in the average output of about 2.5% per year. PMID:15580846

Luketina, I A; Greig, L

2004-09-01

441

Accelerated Profile HMM Searches  

PubMed Central

Profile hidden Markov models (profile HMMs) and probabilistic inference methods have made important contributions to the theory of sequence database homology search. However, practical use of profile HMM methods has been hindered by the computational expense of existing software implementations. Here I describe an acceleration heuristic for profile HMMs, the multiple segment Viterbi (MSV) algorithm. The MSV algorithm computes an optimal sum of multiple ungapped local alignment segments using a striped vector-parallel approach previously described for fast Smith/Waterman alignment. MSV scores follow the same statistical distribution as gapped optimal local alignment scores, allowing rapid evaluation of significance of an MSV score and thus facilitating its use as a heuristic filter. I also describe a 20-fold acceleration of the standard profile HMM Forward/Backward algorithms using a method I call sparse rescaling. These methods are assembled in a pipeline in which high-scoring MSV hits are passed on for reanalysis with the full HMM Forward/Backward algorithm. This accelerated pipeline is implemented in the freely available HMMER3 software package. Performance benchmarks show that the use of the heuristic MSV filter sacrifices negligible sensitivity compared to unaccelerated profile HMM searches. HMMER3 is substantially more sensitive and 100- to 1000-fold faster than HMMER2. HMMER3 is now about as fast as BLAST for protein searches. PMID:22039361

Eddy, Sean R.

2011-01-01

442

A novel rotary acceleration sensor  

Microsoft Academic Search

The authors developed a new type of rotary acceleration sensor. It has the capability to sense an angular acceleration independently to the rotational speed and has an unlimited rotation range. The authors believe that this sensor can be used in robust motor control, vibration control, and any other application where a reliable acceleration signal is needed. The sensor's structure and

Ivan Godler; Akira Akahane; Kouhei Ohnishi; Tadashi Yamashita

1995-01-01

443

Solar Flares and particle acceleration  

E-print Network

Solar Flares and particle acceleration Eduard Kontar School of Physics and Astronomy University of Glasgow, UK STFC Summer School, Armagh, 2012 #12;Solar flares: basics X-raysradiowavesParticles1AU Figure and accelerated particles #12;Solar flares and accelerated particles From Emslie et al., 2004, 2005 Free magnetic

444

Heavy Ion Accelerator (UTI-2).  

National Technical Information Service (NTIS)

The design and test results of the 2 MeV ion accelerator designed for science of materials are described. The UTI-2 accelerator is developed on the basis of the UTI-1 accelerator and equipped with an injector of five-charge ions of iron, chromium and othe...

V. V. Bezuglyj, M. Y. Bredikhin, B. Il'enko I. M. Nekludov, V. K. Knorenko

1986-01-01

445

An experimental trial of cyclic nucleotides on multicellular spheroids derived from human brain tumours  

Microsoft Academic Search

The effects of cyclic nucleotides, dibutyryl cyclic adenosine monophosphate and dibutyryl cyclic guanosine monophosphate (db-cAMP and db-cGMP), on the growth rate of multicellular tumour spheroids were evaluated by comparing the growth delay and colony forming efficiency in vitro. Multicellular tumour spheroids were derived directly from human brain tumours. To compare the chemotherapeutic effect of cyclic nucleotides, CCNU was used as

Nezih Oktar; John L. Darling; David G. T. Thomas

1987-01-01

446

Cyclic3?,5?-nucleotide phosphodiesterase isozymes in cell biology and pathophysiology of the kidney  

Microsoft Academic Search

Cyclic-3?,5?-nucleotide phosphodiesterase isozymes in cell biology and pathophysiology of the kidney. Investigations of recent years revealed that isozymes of cyclic-3?,5?-nucleotide phosphodiesterase (PDE) are a critically important component of the cyclic-3?,5?-adenosine monophosphate (cAMP) protein kinase A (PKA) signaling pathway. The superfamily of cyclic-3?,5?-phosphodiesterase (PDE) isozymes consists of at least nine gene families (types): PDE1 to PDE9. Some PDE families are very

THOMAS P DOUSA

1999-01-01

447

KEKB accelerator control system  

NASA Astrophysics Data System (ADS)

The KEKB accelerator control system including a control computer system, a timing distribution system, and a safety control system are described. KEKB accelerators were installed in the same tunnel where the TRISTAN accelerator was. There were some constraints due to the reused equipment. The control system is based on Experimental Physics and Industrial Control System (EPICS). In order to reduce the cost and labor for constructing the KEKB control system, as many CAMAC modules as possible are used again. The guiding principles of the KEKB control computer system are as follows: use EPICS as the controls environment, provide a two-language system for developing application programs, use VMEbus as frontend computers as a consequence of EPICS, use standard buses, such as CAMAC, GPIB, VXIbus, ARCNET, RS-232 as field buses and use ergonomic equipment for operators and scientists. On the software side, interpretive Python and SAD languages are used for coding application programs. The purpose of the radiation safety system is to protect personnel from radiation hazards. It consists of an access control system and a beam interlock system. The access control system protects people from strong radiation inside the accelerator tunnel due to an intense beam, by controlling access to the beamline area. On the other hand, the beam interlock system prevents people from radiation exposure by interlocking the beam operation. For the convenience of accelerator operation and access control, the region covered by the safety system is divided into three major access control areas: the KEKB area, the PF-AR area, and the beam-transport (BT) area. The KEKB control system required a new timing system to match a low longitudinal acceptance due to a low-alpha machine. This timing system is based on a frequency divider/multiply technique and a digital delay technique. The RF frequency of the KEKB rings and that of the injector Linac are locked with a common divisor frequency. The common divisor frequency determines the injection timing. The RF bucket selection system is also described.

Akasaka, Nobumasa; Akiyama, Atsuyoshi; Araki, Sakae; Furukawa, Kazuro; Katoh, Tadahiko; Kawamoto, Takashi; Komada, Ichitaka; Kudo, Kikuo; Naito, Takashi; Nakamura, Tatsuro; Odagiri, Jun-ichi; Ohnishi, Yukiyoshi; Sato, Masayuki; Suetake, Masaaki; Takeda, Shigeru; Takeuchi, Yasunori; Yamamoto, Noboru; Yoshioka, Masakazu; Kikutani, Eji

2003-02-01

448

Both cyclic-AMP and cyclic-GMP can act as regulators of the phenylpropanoid pathway in Arabidopsis thaliana seedlings.  

PubMed

Cyclic nucleotides (cAMP and cGMP) are important signaling molecules that control a range of cellular functions and modulate different reactions. It is known that under abiotic or biotic stress plant cells synthesize these nucleotides and that they also enhance the activity of the phenylpropanoid pathway. Wondering what is the relation between these two facts, we investigated how the exogenously applied membrane-permeable derivatives, 8-Br-cAMP or 8-Br-cGMP, which are believed to act as the original cyclic nucleotides, affect the expression of the genes for and the specific activity of three enzymes of the phenylpropanoid pathway in Arabidopsis thaliana seedlings. We found that the expression of the genes of phenylalanine ammonia-lyase (PAL2), 4-coumarate:coenzyme A ligase (4CL1) and chalcone synthase (CHS), and the specific activities of PAL (EC 4.3.1.5), 4CL (EC 6.2.1.12) and CHS (EC 2.3.1.74) were induced in the same way by either of these cyclic nucleotides used at 5?M concentration. None of the possible cAMP and cGMP degradation products (AMP, GMP, adenosine or guanosine) evoked such effects. Expression of PAL1, 4CL2 and 4CL3 were practically not affected. Although the investigated nucleotides induced rapid expression of the aforementioned enzymes, they did not affect the level of anthocyanins within the same period. We discuss the effects exerted by the exogenously administered cyclic nucleotides, their relation with stress and the role which the phenylpropanoid pathways the cyclic nucleotides may play in plants. PMID:23774376

Pietrowska-Borek, Ma?gorzata; Nuc, Katarzyna

2013-09-01

449

J Am Cerom Soc 73 [4]893-903 (1990) Cyclic Fatigue-Crack Propagation in  

E-print Network

J Am Cerom Soc 73 [4]893-903 (1990) Cyclic Fatigue-Crack Propagation in Magnesia to degradation from cyclic fatigue.',' However, several investigation^'-'^ using smooth specimens, sometimes.e., static fatigue and dynamic fatigue. far-field cyclic compressive loads.16-21Here, limited crack ex

Ritchie, Robert

450

Modeling cyclic ratcheting based fatigue life of HSLA steels using crystal plasticity FEM simulations and experiments  

E-print Network

Modeling cyclic ratcheting based fatigue life of HSLA steels using crystal plasticity FEM; Cyclic ratcheting; Nucleation cycles; Total fatigue life 1. Introduction High strength low alloy (HSLA, the understanding of cyclic deformation and fatigue behavior of HSLA steels is of high technological relevance

Ghosh, Somnath

451

Cyclic Material Properties Test to Determine Hardening/Softening Characteristics of HY-80 Steel  

SciTech Connect

The Cyclic Material Properties Test was structured to obtain and provide experimental data for determining cyclic hardening/softening characteristics of HY-80 steel. The inelastic strain history data generated by this test program and the resulting cyclic stress-strain curve will be used to enhance material models in the finite element codes used to perform nonlinear elastic-plastic analysis.

S.C. Hodge; J.M. Minicucci; T.F. Trimble

2003-04-30

452

Modeling and characterization of cyclic relaxation and ratcheting using the distributed-element model  

Microsoft Academic Search

Constitutive modeling of cyclic relaxation and ratcheting (cumulative inelastic deformation) is developed on the basis of the distributed-element model (DEM). Although the original DEM is capable of describing general, elasticplastic behavior for cyclically stabilized materials, it has the inadequacy of not being able to account for the effect of cyclic relaxation and ratcheting. By introducing the nonlinear kinematic hardening rule

Dar-Yun Chiang

2008-01-01

453

Constitutive modeling of cyclic plasticity deformation of a pure polycrystalline copper  

Microsoft Academic Search

Cyclic plasticity experiments were conducted on a pure polycrystalline copper and the material was found to display significant cyclic hardening and nonproportional hardening. An effort was made to describe the cyclic plasticity behavior of the material. The model is based on the framework using a yield surface together with the ArmstrongFrederick type kinematic hardening rule. No isotropic hardening is considered

Jixi Zhang; Yanyao Jiang

2008-01-01

454

Cyclic Nucleotides as Intracellular Mediators of the Expression of Antigen-sensitive Cells  

Microsoft Academic Search

The interaction of antigen with antigen-sensitive cells can lead to antibody synthesis (induction) or can render these cells non-inducible (paralysis). Cyclic AMP may be the intracellular mediator of a paralytic signal whereas both cyclic AMP and cyclic GMP may be required as mediators of an inductive signal.

James Watson; Ruth Epstein; Melvin Cohn

1973-01-01

455

1106 / JOURNAL OF ENGINEERING MECHANICS / NOVEMBER 2001 DRAINED CYCLIC BEHAVIOR OF SAND WITH FABRIC DEPENDENCE  

E-print Network

stresses. A stress-dilatancy model for sand in the cyclic loading regime, taking into account on hypoplasticity so as to accurately calculate volume changes induced by fabric and dilatancy changes during cyclic to that of solids. INTRODUCTION Most studies of cyclic behavior of sand have mainly focused on liquefaction aspects

Wan, Richard G.

456

Stress state dependence of cyclic ratchetting behavior of two rail steels  

Microsoft Academic Search

Cumulative inelastic deformation or ratchetting occurs during cyclic loading in the presence of a mean stress. This problem has received considerable recent attention. The nonlinear kinematic hardening rule originally proposed by Armstrong and Frederick (AF rule) [1966] has been widely used for description of the overall character of hysteresis response during cyclic plasticity. However, this model generally overpredicts cyclic strain

D. L. McDowell

1995-01-01

457

Mechanisms governing cyclic deformation and failure during elevated temperature fatigue of aluminum alloy 7055  

Microsoft Academic Search

The cyclic stress response, deformation and damage characteristics of aluminum alloy 7055 was studied at ambient and elevated temperatures. Specimens of the alloy were cyclically deformed using tension-compression loading under total strain-amplitude control. The alloy showed evidence of softening to failure at the ambient and elevated test temperatures. The degree of cyclic softening increased with an increase in test temperature.

T. S Srivatsan

1999-01-01

458

A debris mechanism of cyclic strain hardening for F.C.C. metals  

Microsoft Academic Search

Prismatic dislocation loops (dislocation debris), formed by fatigue or cyclic straining, have been observed in a number of metals. To account for these observations a mechanism of cyclic strain hardening is proposed which depends on the ease of loop formation and the behaviour of the loops after they are formed. In the initial rapid hardening stage, the rate of cyclic

C. E. Feltner

1965-01-01

459

BotEC: Spacecraft Acceleration  

NSDL National Science Digital Library

Question Suppose someone offered you a ride to the nearest star in a new spacecraft that could travel at half the speed of light, or about 150,000 km/second. In order to reach such a cruising speed, you and the spacecraft must accelerate from a standstill to half the speed of light. Acceleration means uncomfortable (and maybe even fatal!) "g" forces, that pressed-into-the-seat feeling you get when a car or airplane accelerates. More than 3 g's of acceleration are tough to take for very long, so your spacecraft's engines are designed to accelerate you at not more than 29 meters/second/second (3 times the acceleration due to gravity at the Earth's surface). How long will it take you and your spacecraft to accelerate to half light speed?

Tewksbury, Barb

460

APT accelerator. Topical report  

SciTech Connect

The Accelerator Production of Tritium (APT) project, sponsored by Department of Energy Defense Programs (DOE/DP), involves the preconceptual design of an accelerator system to produce tritium for the nation`s stockpile of nuclear weapons. Tritium is an isotope of hydrogen used in nuclear weapons, and must be replenished because of radioactive decay (its half-life is approximately 12 years). Because the annual production requirements for tritium has greatly decreased since the end of the Cold War, an alternative approach to reactors for tritium production, based on a linear accelerator, is now being seriously considered. The annual tritium requirement at the time this study was undertaken (1992-1993) was 3/8 that of the 1988 goal, usually stated as 3/8-Goal. Continued reduction in the number of weapons in the stockpile has led to a revised (lower) production requirement today (March, 1995). The production requirement needed to maintain the reduced stockpile, as stated in the recent Nuclear Posture Review (summer 1994) is approximately 3/16-Goal, half the previous level. The Nuclear Posture Review also requires that the production plant be designed to accomodate a production increase (surge) to 3/8-Goal capability within five years, to allow recovery from a possible extended outage of the tritium plant. A multi-laboratory team, collaborating with several industrial partners, has developed a preconceptual APT design for the 3/8-Goal, operating at 75% capacity. The team has presented APT as a promising alternative to the reactor concepts proposed for Complex-21. Given the requirements of a reduced weapons stockpile, APT offers both significant safety, environmental, and production-fexibility advantages in comparison with reactor systems, and the prospect of successful development in time to meet the US defense requirements of the 21st Century.

Lawrence, G.; Rusthoi, D. [comp.] [ed.

1995-03-01

461

Accelerated Degradation of Polymers  

NSDL National Science Digital Library

For this laboratory exercise, you will monitor changes in the visual appearance of the samples, chemical changes and molecular weight changes as a function of exposure condition. Analysis of the neat and degraded systems will be done using visual evaluation, FTIR analysis and GPC analysis. After in-class presentation, completion of hands-on laboratory experiment and review of the information provided, you should be able to: Confidently discuss the mechanism of breakdown for a polymeric material exposed to various environmental conditions. Prepare samples and record an accurate account of their preparation for use in an outdoor environment and in an accelerated weathering chamber (Q-sun).

Derosa, Rebecca L.

2008-09-26

462

Accelerating Commercial Remote Sensing  

NASA Technical Reports Server (NTRS)

Through the Visiting Investigator Program (VIP) at Stennis Space Center, Community Coffee was able to use satellites to forecast coffee crops in Guatemala. Using satellite imagery, the company can produce detailed maps that separate coffee cropland from wild vegetation and show information on the health of specific crops. The data can control coffee prices and eventually may be used to optimize application of fertilizers, pesticides and irrigation. This would result in maximal crop yields, minimal pollution and lower production costs. VIP is a mechanism involving NASA funding designed to accelerate the growth of commercial remote sensing by promoting general awareness and basic training in the technology.

1995-01-01

463

Accelerated Innovation Pilot  

NASA Technical Reports Server (NTRS)

Opportunities: I. Engage NASA team (examples) a) Research and technology calls . provide suggestions to AES, HRP, OCT. b) Use NASA@Work to solicit other ideas; (possibly before R+D calls). II. Stimulate collaboration (examples) a) NHHPC. b) Wharton Mack Center for Technological Innovation (Feb 2013). c) International ] DLR ] :envihab (July 2013). d) Accelerated research models . NSF, Myelin Repair Foundation. III. Engage public Prizes (open platform: InnoCentive, yet2.com, NTL; Rice Business Plan, etc.) IV. Use same methods to engage STEM.

Davis, Jeffrey

2012-01-01

464

Circus Physics: Centripetal Acceleration  

NSDL National Science Digital Library

This video-based resource examines centripetal force through the motion of circus animals running around a ring. Objects moving in a circle (even at constant speed) are experiencing acceleration because the center-seeking force causes a change in velocity. The video can serve to help students understand that an unbalanced force can change the direction of the velocity vector but not its magnitude. It includes tips on how to incorporate the video into instruction, discussion questions, and accompanying classroom activities. This resource was developed in conjunction with the PBS series Circus. See Related Materials for a link to the full set of 8 Circus Physics video-based lessons.

2013-11-19

465

Identification of cyclic nucleotide gated channels using regular expressions.  

PubMed

Cyclic nucleotide-gated channels (CNGCs) are nonselective cation channels found in plants, animals, and some bacteria. They have a six-transmembrane/one-pore structure, a cytosolic cyclic nucleotide-binding domain, and a cytosolic calmodulin-binding domain. Despite their functional similarities, the plant CNGC family members appear to have different conserved amino acid motifs within corresponding functional domains than animal and bacterial CNGCs do. Here we describe the development and application of methods employing plant CNGC-specific sequence motifs as diagnostic tools to identify novel candidate channels in different plants. These methods are used to evaluate the validity of annotations of putative orthologs of CNGCs from plant genomes. The methods detail how to employ regular expressions of conserved amino acids in functional domains of annotated CNGCs and together with Web tools such as PHI-BLAST and ScanProsite to identify novel candidate CNGCs in species including Physcomitrella patens. PMID:23681581

Zelman, Alice K; Dawe, Adam; Berkowitz, Gerald A

2013-01-01

466

Dual cyclic power saving technique for XG-PON.  

PubMed

In a passive optical network (PON), energy conservation is an important system design goal to satisfy the global demands for an energy efficient green network. In this paper, we show that a separate period control for the transmitter and receiver of an optical transceiver can result in better power saving performances in PON systems. Then, we propose a power saving mode called the Dual Cyclic Sleep (DCS) mode. We have implemented the DCS mode in an ETRI XG-PON system and conducted experiments to show the power saving efficiency of the proposed DCS mode. The results indicate that the DCS mode provides higher power saving efficiency than the doze and cyclic sleep modes. PMID:25322186

Kim, Geunyong; Kim, Sungchang; Lee, Dongsoo; Yoo, Hark; Lim, Hyuk

2014-08-25

467

The robustness of cyclic dominance under random fluctuations.  

PubMed

We investigate the influence of random perturbations on a recently introduced three-species model that reproduces the empirically observed pattern of cyclic dominance in Fraser River sockeye salmon. Since the sockeye populations are subject to various types of fluctuations affecting their growth and survival, we investigate the robustness of the model under several types of noise. In particular, we evaluate the variation of population sizes around their values in the deterministic model, the frequency of phase shifts in the 4-year oscillation, the extent of synchronization between different sockeye populations, and the response to strong one-time perturbations. Our main conclusion is that cyclic dominance is very stable even under strong noise in this model. PMID:22677399

Schmitt, Christoph K; Guill, Christian; Drossel, Barbara

2012-09-01

468

Search for new cyclic AMP-binding proteins.  

PubMed

Today, there is evidence that the cAMP-dependent kinases (PKA) are not the only intracellular receptors involved in intracellular cAMP signalling in eukaryotes. Other cAMP-binding proteins have been recently identified, including some cyclic nucleotide-gated channels and Epac (exchange protein directly activated by cAMP) proteins. All these proteins bind cAMP through conserved cyclic nucleotide monophosphate-binding domains. However, all putative cAMP-binding proteins having such domains, as revealed by computer analysis, do not necessarily bind cAMP, indicating that their presence is not a sufficient criteria to predict cAMP-binding property for a protein. PMID:12829244

Dremier, S; Kopperud, R; Doskeland, S O; Dumont, J E; Maenhaut, C

2003-07-01

469

Endometriosis of the conus medullaris causing cyclic radiculopathy.  

PubMed

Intramedullary spinal cord hematomas are a rare neurosurgical pathological entity typically arising from vascular and neoplastic lesions. Endometriosis is an extremely rare cause of intramedullary spinal cord hematoma, with only 5 previously reported cases in the literature. Endometriosis is characterized by ectopic endometrial tissue, typically located in the female pelvic cavity, that causes a cyclical pain syndrome, bleeding, and infertility. In the rare case of intramedullary endometriosis of the spinal cord, symptoms include cyclical lower-extremity radiculopathies and voiding difficulties, and can acutely cause cauda equina syndrome. The authors report a case of endometriosis of the conus medullaris, the first to include radiological, intraoperative, and histopathological imaging. A brief review of the literature is also presented, with discussion including etiological theories surrounding intramedullary endometriosis. PMID:25192376

Steinberg, Jeffrey A; Gonda, David D; Muller, Karra; Ciacci, Joseph D

2014-11-01

470

Engine cyclic durability by analysis and material testing  

NASA Technical Reports Server (NTRS)

The problem of calculating turbine engine component durability is addressed. Nonlinear, finite-element structural analyses, cyclic constitutive behavior models, and an advanced creep-fatigue life prediction method called strainrange partitioning were assessed for their applicability to the solution of durability problems in hot-section components of gas turbine engines. Three different component or subcomponent geometries are examined: a stress concentration in a turbine disk; a louver lip of a half-scale combustor liner; and a squealer tip of a first-stage high-pressure turbine blade. Cyclic structural analyses were performed for all three problems. The computed strain-temperature histories at the critical locations of the combustor linear and turbine blade components were imposed on smooth specimens in uniaxial, strain-controlled, thermomechanical fatigue tests of evaluate the structural and life analysis methods.

Kaufman, A.; Halford, G. R.

1983-01-01

471

Engine cyclic durability by analysis and material testing  

NASA Technical Reports Server (NTRS)

The problem of calculating turbine engine component durability is addressed. Nonlinear, finite-element structural analyses, cyclic constitutive behavior models, and an advanced creep-fatigue life prediction method called strainrange partitioning were assessed for their applicability to the solution of durability problems in hot-section components of gas turbine engines. Three different component or subcomponent geometries are examined: a stress concentration in a turbine disk; a louver lip of a half-scale combustor linear; and a squealer tip of a first-stage high-pressure turbine blade. Cyclic structural analyses were performed for all three problems. The computed strain-temperature histories at the critical locations of the combustor linear and turbine blade components were imposed on smooth specimens in uniaxial, strain-controlled, thermomechanical fatigue tests of evaluate the structural and life analysis methods.

Kaufman, A.; Halford, G. R.

1984-01-01

472

Cyclic wear behavior (fretting) of a tempered martensite steel  

NASA Astrophysics Data System (ADS)

Cyclic wear experiments were conducted on a 4130 steel with a tempered martensitic structure in laboratory air and in flowing argon. Temperatures of the sliding interfaces were measured and were of the order of + 10 K above the ambient. The interface temperatures were observed to be cyclic and correlated with maxima in sliding velocities between the surfaces. Microhardness measurements and optical and electron metallographic observations of fretted surfaces indicated selective surface hardening and the formation of large numbers of thin metallic flakes. The thickness of the flakes corresponded to the thickness of the hardened layer and were formed from subsurface crack initiation processes. The results of this investigation do not support many previously proposed models for fretting damage. Rather a micromechanical cracking model is proposed which appears to explain observed results in terms of a delamination model.

Gaul, D. J.; Duquette, D. J.

1980-09-01

473

Cyclic rate-dependent fatigue life in reactor water  

SciTech Connect

The study of crack growth rates in mildly aggressive environments such as reactor water clearly demonstrates an important sensitivity to crack tip strain rate during the tensile portion of cyclic loadings. Moreover, the effects of strain rate interact directly with mean stress influences in such environments. Current safe-life analysis methods are based on fatigue data obtained in air and do not address strain rate sensitivity issues. In the present work strain rate sensitivities are quantified and used with environmental crack growth rate data to produce theoretical S-N fatigue data which explicitly include mean stress and strain rate (or cyclic rate) effects on crack growth rates in reactor water. Results are presented for several cases of loading rise time and mean stress level. Some combinations of these variables are observed to significantly reduce S-N fatigue life relative to that for air environments, while other combinations do not.

O`Donnell, T.P.; O`Donnell, W.J. [O`Donnell Consulting Engineers, Pittsburgh, PA (United States)

1995-12-31

474

LEARNING CYCLIC SIGNALING PATHWAY STRUCTURES WHILE MINIMIZING DATA REQUIREMENTS  

PubMed Central

Bayesian network structure learning is a useful tool for elucidation of regulatory structures of biomolecular pathways. The approach however is limited by its acyclicity constraint, a problematic one in the cycle-containing biological domain. Here, we introduce a novel method for modeling cyclic pathways in biology, by employing our newly introduced Generalized Bayesian Networks (GBNs). Our novel algorithm enables cyclic structure learning while employing biologically relevant data, as it extends our cycle-learning algorithm to permit learning with singly perturbed samples. We present theoretical arguments as well as structure learning results from realistic, simulated data of a biological system. We also present results from a real world dataset, involving signaling pathways in T-cells. PMID:19209696

SACHS, K.; ITANI, S.; FITZGERALD, J.; WILLE, L.; SCHOEBERL, B.; DAHLEH, M. A.; NOLAN, G. P.

2014-01-01

475

Evaluation of Cyclic Behavior of Aircraft Turbine Disk Alloys  

NASA Technical Reports Server (NTRS)

An evaluation of the cyclic behavior of three aircraft engine turbine disk materials was conducted to compare their relative crack initiation and crack propagation resistance. The disk alloys investigated were Inconel 718, hot isostatically pressed and forged powder metallurgy Rene '95, and as-hot-isostatically pressed Rene '95. The objective was to compare the hot isostatically pressed powder metallurgy alloy forms with conventionally processed superalloys as represented by Inconel 718. Cyclic behavior was evaluated at 650 C both under continuously cycling and a fifteen minute tensile hold time cycle to simulate engine conditions. Analysis of the test data were made to evaluate the strain range partitioning and energy exhaustion concepts for predicting hold time effects on low cycle fatigue.

Shahani, V.; Popp, H. G.

1978-01-01

476

Undrained behaviour of silt under static and cyclic loading  

NASA Astrophysics Data System (ADS)

In this study, the undrained behaviour of silt under low stress level is studied. An effective preparation method for builtin silt samples in the triaxial test was firstly developed. By triaxial testing of samples at low confining pressures it was found that silt easily loses stability and liquefies. Loose silt may show temporary liquefaction under static loading, and develop full liquefaction under cyclic loading. The most important factors influencing the silt behaviour are porosity, confining pressure, consolidation state, cyclic loading level and number of cycles. The maximum obtainable shear stress is primarily a function of the confining pressure and the internal frictional angle. The actual structure of the silt material is the key factor in controlling its behaviour.

Shaoli, Yang; Sandven, Rolf; Grande, Lars

2002-10-01

477

Nicral ternary alloy having improved cyclic oxidation resistance  

NASA Technical Reports Server (NTRS)

NiCrAl alloys are improved by the addition of zirconium. These alloys are in the Beta or gamma/gamma' + Beta region of the ternary system. Zirconium is added in a very low amount between 0.06 and 0.20 weight percent. There is a narrow optimum zirconium level at the low value of 0.13 weight percent. Maximum resistance to cyclic oxidation is achieved when the zirconium addition is at the optimum value.

Barrett, C. A.; Lowell, C. E.; Khan, A. S.

1982-01-01

478

Cyclic nucleotides in tissues during long-term hypokinesia  

NASA Technical Reports Server (NTRS)

Male Wistar rates were kept hypokinetic by placing them in small containers for 22 days. Blood plasma cAMP content was subsequently found increased, and cGMP content decreased, in the experimental animals. Liver and thymus cAMP content was similar in the control and experimental animals. There was a 20 and 38% decrease of cAMP content in the kidneys and spleen, respectively. Hypokinesia's reduction of cyclic nucleotides seems to inhibit RNA and protein synthesis.

Makeyeva, V. F.; Komolova, G. S.; Yegorov, I. A.; Serova, L. V.; Chelnaya, N. A.

1981-01-01

479

The effects of alcohol on cyclic AMP in mouse brain  

Microsoft Academic Search

Detailed analysis of the dose-response and time-course relationship of ethanol to changes in adenosine 3',5'-cyclic monophosphate (cAMP) content of mouse brain revealed several patterns of response, including both decreases and increases depending on brain area. Whole-brain cAMP content was decreased with ethanol injection at all doses (0.43.2 g\\/kg), and reflected the decreased levels in the cortex. The subcortical and cerebellar

E. K. Orenberg; J. Renson; J. D. Barchas

1976-01-01

480

Cyclic steaming of tar sands through hydraulically induced fractures  

Microsoft Academic Search

Fracture dimensions and process mechanisms resulting from cyclic steam stimulation above fracturing pressure in German and Canadian tar sands are analyzed using numerical modeling. Fracture radii of 100 feet and half-lengths of 250 feet with fracture surface areas of 30,000 to 70,000 square feet were sufficient to reproduce steam injectivity into reservoirs containing highly viscous oil and negligible amounts of

Deitrich

1983-01-01

481

Cyclic steaming of tar sands through hydraulically induced fractures  

SciTech Connect

Fracture dimensions and process mechanisms resulting from cyclic steam stimulation above fracturing pressure in German and Canadian tar sands are analyzed using numerical modeling. Fracture radii of 100 feet and half-lengths of 250 feet with fracture surface areas of 30,000 to 70,000 square feet were sufficient to reproduce steam injectivity into reservoirs containing highly viscous oil and negligible amounts of movable water saturation.

Deitrich, J.K.

1983-03-01

482

Cyclic steaming of tar sands through hydraulically induced fractures  

Microsoft Academic Search

Fracture dimensions and process mechanisms resulting from cyclic steam stimulation above fracturing pressure in German and Canadian tar sands are analyzed using numeric modeling. Fracture radii of 100 ft and half-lengths of 250 ft with fracture surface areas of 30,000 to 70,000 sq ft were sufficient to reproduce steam injectivity into reservoirs containing highly viscous oil and negligible amounts of

Dietrich

1983-01-01

483

Cyclic Steaming of Tar Sands Through Hydraulically Induced Fractures  

Microsoft Academic Search

Fracture dimensions and process mechanisms that resulted from cyclic steam stimulation above fracturing pressure in German and Canadian tar sands are analyzed with numerical modeling. Horizontal fracture radii of 100 ft (30.5 m) and vertical fracture half-lengths of 250 ft (76.2 m) with fracture surface areas of 30,000 to 70,000 sq ft (2787 to 6503 m²) are sufficient to reproduce

J. K. Dietrich

1986-01-01

484

Cyclic steaming of tar sands through hydraulically induced fractures  

SciTech Connect

Fracture dimensions and process mechanisms resulting from cyclic steam stimulation above fracturing pressure in German and Canadian tar sands are analyzed using numeric modeling. Fracture radii of 100 ft and half-lengths of 250 ft with fracture surface areas of 30,000 to 70,000 sq ft were sufficient to reproduce steam injectivity into reservoirs containing highly viscous oil and negligible amounts of movable water saturation.

Dietrich, J.K.

1983-01-01

485

A Dynamic Programming Model of the Cyclic Steam Injection Process  

Microsoft Academic Search

The cyclic steam-injection process has become the most widely applied and most successful thermal recovery technique in use today. Because it is a multistage-decision process, dynamic programing--characterized by a criterion function to be satisfied, a number of stages in time and space, and decisions to be made at each stage to satisfy the criterion function--may be used to predict an

R. G. Bentsen; D. A. T. Donohoe

1969-01-01

486

Enhanced catalyst stability for cyclic co methanation operations  

DOEpatents

Carbon monoxide-containing gas streams are passed over a catalyst to deposit a surface layer of active surface carbon thereon essentially without the formation of inactive coke. The active carbon is thereafter reacted with steam or hydrogen to form methane. Enhanced catalyst stability for long term, cyclic operation is obtained by the incorporation of an alkali or alkaline earth dopant in a silica binding agent added to the catalyst-support additive composition.

Risch, Alan P. (New Fairfield, CT); Rabo, Jule A. (Armonk, NY)

1983-01-01

487

Cyclic contact fatigue of a silver alternative to amalgam  

Microsoft Academic Search

Objective. The purpose of this study was to compare the cyclic contact fatigue resistance of a novel mercury-free silver direct filling material to that of a dental amalgam (Dispersalloy).Methods. The silver specimens were made by pressing a precipitated powder at room temperature with a pressure of 150MPa, which can be achieved in clinical hand-consolidation. To simulate clinical contact of restorations

Hockin H. K Xu; Frederick C Eichmiller; Anthony A Giuseppetti; Christian E Johnson

1998-01-01

488

Cyclic fatigue due to electric loading in ferroelectric ceramics  

Microsoft Academic Search

Mechanical fatigue of ferroelectric ceramics due to bipolar cyclic electric loading is examined. Beam specimens out of three different PZT materials were cut and precracks were initiated by Vickers indentation. The specimens were loaded by alternating electric fields varied from 09 to 10 and 15 times the coercive field Ec. In short intervals the crack propagation was measured. Before and

H Weitzing; G. A Schneider; J Steffens; M Hammer; M. J Hoffmann

1999-01-01

489

Cyclic fatigue of intrinsically brittle ceramics in contact with spheres  

Microsoft Academic Search

Contact damage modes in cyclic loading with spheres are investigated in three nominally brittle ceramics, soda-lime glass, porcelain and fine-grain silicon nitride, in moist environments. Initial damage at small numbers of cycles and low loads consists of tensile-driven macroscopic cone cracks (brittle mode). Secondary damage at large numbers of cycles and high loads consists of shear-driven distributed microdamage (quasi-plastic mode),

D. K. Kim; Y.-G. Jung; I. M. Peterson; B. R. Lawn

1999-01-01

490

Ring-Opening Polymerization of Cyclic Esters onto Liquefied Biomass  

Microsoft Academic Search

Ring-opening polymerization of cyclic esters (?-caprolactone, d-valerolactone, and l-lactide) onto liquefied biomass (LB) was conducted to obtain the polyester-type polyol and to regulate the characteristics of LB. IR and 1H-NMR spectra of the obtained polyol showed that the polymerization was successfully conducted in the presence of acid catalyst, which is used in liquefaction. The molecular weight (Mw), hydroxyl value, and

Seung-Hwan Lee; Tsutomu Ohkita

2004-01-01

491

Hydrolysis of the chlorophosphazenes: cyclic trimer and linear polymer  

E-print Network

Products of the Chlorophosphazene Cyclic Trimer (t). . 30 2. P NMR Spectroscopic Properties of Hydrolyzed Poly(dichlorophosphazene). 46 LIST OP PIGURES FIGURE Page Selected P NMR spectra from a representative hydrolysis study using 1 eq of water... additional peaks tenatively associated with the hydrolyzed species cis-4, trans-4 and 5. Hydrolysis affected with 12 eq water, spectra obtained after 16 hours. 27 Mole fractions of various hydrolysis products of t vs time for a representative hydrolysis...

Gabler, Douglas G

2012-06-07

492

Adjustable-Length Strut Withstands Large Cyclic Loads  

NASA Technical Reports Server (NTRS)

Adjustable-length strut designed for installation in structure subjected to large cyclic loads. Partly resembles large turnbuckle: includes oppositely threaded eyebolts engaging correspondingly threaded holes at opposite ends of shaft, and shaft turned to adjust length. However, unlike in turnbuckle, length setting not fixed by use of simple jam nuts: instead, length setting fixed by use of more complex threaded-end flanges partly resembling jam nuts but function somewhat differently.

Carner, Fred P.

1995-01-01

493

Cyclic loading of beams based on the Chaboche model  

Microsoft Academic Search

The time independent non-unified version of the Chaboche constitutive model for the cyclic loading which includes the kinematic\\u000a and isotropic hardening is discussed in detail. The performance of the Chaboche constitutive model in predicting ratcheting\\u000a response of CS1026 steel for a broad set of mechanical uniaxial and biaxial loading histories is considered. A numerical iterative\\u000a method is used to calculate

A. Shojaei; M. R. Eslami; H. Mahbadi

2010-01-01

494

Morphological evolution of thermal barrier coatings induced by cyclic oxidation  

Microsoft Academic Search

High temperature oxidation behavior of EB-PVD thermal barrier coatings (TBC) deposited on a single-crystal nickel-base superalloy with platinum aluminide bond coat has been studied using optical microscopy and luminescence spectroscopy. Examination of the TBC morphology in the course of cyclic oxidation at 1150 C reveals that the TBC surface may develop undulations, which grow with oxidation time and eventually link

V. K Tolpygo; D. R Clarke

2003-01-01

495

Liquefaction of Sand under BiDirectional Cyclic Loading  

Microsoft Academic Search

A laboratory study is presented of liquefaction behavior of saturated loose sand subjected to bi-directional cyclic loading\\u000a under isotropic consolidated conditions using the soil static and dynamic universal triaxial and torsional shear apparatus,\\u000a which can apply axial pressure W and torque M\\u000a \\u000a T\\u000a individually. Tests were performed following the stress path that is controlled by shape of ellipse in terms

Maotian Luan; Dan Jin; Zhendong Zhang; Qiyi Zhang

496

Non-isothermal plasticity model for cyclic behaviour of soils  

Microsoft Academic Search

SUMMARY On the one hand, it has been observed that liquefaction-induced shear deformation of soils accumulates in a cycle-by-cycle pattern. On the other hand, it is known that heating could induce plastic hardening. This study deals with the constitutive modelling of the effect that heat may have on the cyclic mechanical properties of cohesive soils, a relatively new area of

L. Laloui; C. Cekerevac

2008-01-01

497

Interaction between structural and cyclical shocks in production and employment  

Microsoft Academic Search

Interaction between Structural and Cyclical Shocks in Production and Employment. A major aim of recent empirical modelling\\u000a of the business cycle is to identify the relative importance of aggregate supply and demand shocks. This paper uses the methodology\\u000a of unobserved (or structural) components time series models for the identification of techn