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1

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

2

Stability and Scaling of High Current Cyclic Accelerators.  

National Technical Information Service (NTIS)

This report presents theoretical results on the stability and scaling of compact electron accelerators using continuous strong focusing in the form of stellarator windings. The work attempted to address in some considerable detail every major physics issu...

1989-01-01

3

Limiting electron beam current for cyclic induction acceleration in a constant guide field  

SciTech Connect

Theoretical relations are derived for the limiting beam current in a cyclic induction accelerator (CIA) with a constant guide field. The calculations are in agreement with the available experimental data. It is shown that the limiting average beam current in a CIA is of the order of 100 microamperes, i.e., the level attained in microtrons and linear accelerators. The CIA may find industrial applications.

Kanunnikov, V.N.

1982-09-01

4

Accelerated cyclic corrosion testing of structural steels and its application to assess steel bridge coatings  

Microsoft Academic Search

Purpose – The purpose of this study was to determine correlation between an accelerated cyclic corrosion test (S6-cycle test) specified in Japanese Industrial Standards K5621 and field exposure tests, and to open up applications of the accelerated tests in various regional environments. Design\\/methodology\\/approach – The S6-cycle corrosion test was carried out on structural steels for 30, 60, 90, 120 and

Yoshito Itoh; In-Tae Kim

2006-01-01

5

Accelerated kinetics and mechanism of growth of boride layers on titanium under isothermal and cyclic diffusion  

NASA Astrophysics Data System (ADS)

The tendency of titanium (Ti) and its alloys to wear, gall and seize during high contact stresses between sliding surfaces severely limits their applications in bearings, gears etc. One way to mitigate these problems is to modify their surfaces by applying hard and wear resistant surface coatings. Boriding, which involves solid state diffusion of boron (B) into Ti, thereby forming hard surface layers consisting of TiB2 and TiB compounds has been shown to produce extremely high wear resistant surfaces in Ti and its alloys. The growth kinetics of these layers are, however, limited by the low diffusivities of B in the high melting TiB2 and TiB compounds. On the basis of the fact that HCP metals such as Ti show enhanced (anomalous) self-diffusion near the phase transition temperature, the first hypothesis of this work has been that the diffusivity enhancement should cause rapid ingress of B atoms, thereby accelerating the growth of the hard boride layers. Isothermal boriding experiments were performed close to phase transition temperature (890, 910, and 915°C) for time periods ranging from 3 to 24 hours. It was found that indeed a much deeper growth of TiB into the Ti substrate (˜75 mum) occurred at temperatures very close to the transition temperature (910°C), compared to that obtained at 1050°C. A diffusion model based on error-function solutions of Fick's second law was developed to quantitatively illustrate the combined effects of the normal B diffusion in the TiB phase and the anomalous B diffusion in Ti phase in accelerating TiB layer growth. Furthermore, isothermal boriding experiments close to transition temperature (900°C) for a period of 71 hours resulted in coating thickness well above 100 mum, while at 1050°C, the layer growth saturated after about 24 hours of treatment time. In the second part of this work, a novel approach named "cyclic-phase-changediffusion, (CPCD)," to create deeper TiB2 and TiB coating layers on CP-Ti by cyclic thermal processing, has been investigated. It was found that thermal cyclic B diffusion in Ti across the alpha(alpha)-beta(beta) phase transition temperature led to highly hardened surface layers enriched with TiB whiskers that grow to depths exceeding 120 mum. By solving the transient heat transport problem for cyclic changes in surface temperatures, it was found that there is a "heat-packet" that travels back and forth from the surface to the interior of the material. This heat-packet appears to transport B dissolved in beta-Ti into interior causing increased coating depths.

Sarma, Biplab

6

Method of extrapolating inelastic deformations for the accelerated calculation of the kinetics of cyclic deformation  

Microsoft Academic Search

;I'hr calculation of the kinetics ryf inelastie deformation of structures makes it possible to use the most adecluate m\\/~dels of the medium and to obt,~ ~he most complete Information on the inelastic operation of structures .with ~real, often very complex programs of cyclic ~t, kermornechanlcaI actto~. Itowever, such a calculation is also the most l~:~0us one: before the cyclic de%rmatton

V. É. Gokhberg; O. S. Sadakov

1987-01-01

7

Influence of feedbacks in the RF accelerating system and feeders between RF power generators and accelerating resonators on the in-phase dipole oscillations of bunches in cyclic accelerators  

NASA Astrophysics Data System (ADS)

In cyclic accelerators, interaction of the beam with the RF accelerating system may generate inphase dipole oscillations of bunches, which govern the limiting current of charged particles in the accelerator. A method of calculating the influence of the parameters of the RF system on the limit current is suggested. It is shown that feedbacks stabilizing the performance of the RF system considerably influence the limiting current in the accelerator. Moreover, the length of feeders through which the power of RF generators is applied to accelerating resonators also has an effect on the limiting current. The efficiency of the method is demonstrated by calculating the limiting electron current in a Sibir'-2 storage ring installed at the Russian Research Centre Kurchatov Institute.

Mityanina, N. V.; Petrov, V. M.

2011-10-01

8

Perturbation techniques for accelerated convergence of cyclic steady state (CSS) in oxygen VSA simulations  

Microsoft Academic Search

Non-isothermal PSA bulk gas separations are notoriously slow to converge to cyclic steady state (CSS). Most numerical simulators that model the slow transient behaviour of these processes share this slow pace of convergence. This difficulty with numerical simulators has long been recognised, and has hampered the optimisation of oxygen VSA.This paper outlines the application of perturbation techniques to enable more

Simon J. Wilson; Paul A. Webley

2002-01-01

9

Application of cyclic strain for accelerated skeletal myogenic differentiation of mouse bone marrow-derived mesenchymal stromal cells with cell alignment.  

PubMed

The fabrication of biomimetic skeletal myocyte constructs continues to present a challenge to functional tissue engineering. The skeletal myogenesis of bone marrow-derived mesenchymal stromal cells (BMSCs) to mimic the native tissue architecture offers great therapeutic promise, but remains particularly difficult. The aim of this study was to examine the possibility of accelerating the skeletal myogenic differentiation of BMSCs with an aligned structure by applying cyclic strain. Mouse BMSCs (mBMSCs) were plated on silicone sheets that were coated with fibronectin and subjected to cyclic 10% uniaxial strain when they reached 80%-90% cell confluency. Cells cultured in a growth medium that were subjected to cyclic strain at a frequency of 0.17?Hz (10 times/min) demonstrated a shift of alignment within 48?h from a completely random orientation to a well-aligned morphology with well-organized actin stress fibers that were parallel to the strain vector. The cyclic strain restricted the motility and proliferation of the aligned mBMSCs in the growth medium, which resulted in tight cellular contact in the cell population. When mBMSCs were subjected to cyclic strain in a myogenic medium, reverse transcription-polymerase chain reaction analysis demonstrated the upregulation of skeletal myogenic marker genes (myogenic factor 5 [Myf5], myogenin, and myogenic regulatory factor 4 [MRF4]), but not smooth muscle marker genes (myocardin and ?-smooth muscle actin). In addition, immunocytochemistry showed that the mBMSCs fused to form multinucleated myosin- and myogenin-positive myotubes in the direction of the applied tension within 5 days. These results demonstrate that our simple method of applying of cyclic strain to cells cultured in a myogenic medium greatly accelerates the skeletal myogenic differentiation of mBMSCs with an aligned structure, and they highlight the importance of cellular alignment for creating physiologically relevant environments to study the myogenesis of BMSCs and engineer skeletal muscle. PMID:23072369

Egusa, Hiroshi; Kobayashi, Munemasa; Matsumoto, Takuya; Sasaki, Jun-Ichi; Uraguchi, Shinya; Yatani, Hirofumi

2012-11-21

10

Acceleration  

Microsoft Academic Search

IN NATURE, NO. 1415, p. 125, Prof. Lodge asserts that the subject of acceleration is at the root of the perennial debate between engineers and teachers of mechanics; and he urges clearness of idea and accuracy of speech on all who deal with the junior student. Towards this end I would suggest that the too common phrase ``acceleration of velocity''

Edward Geoghegan

1897-01-01

11

Rho-kinase accelerates synaptic vesicle endocytosis by linking cyclic GMP-dependent protein kinase activity to phosphatidylinositol-4,5-bisphosphate synthesis.  

PubMed

Rho-kinase plays diverse roles in cell motility. During neuronal development, Rho-kinase is involved in neuronal migration, and in neurite outgrowth and retraction. Rho-kinase remains highly expressed in mature neurons, but its physiological roles are poorly understood. Here we report that Rho-kinase plays a key role in the synaptic vesicle recycling system in presynaptic terminals. Vesicles consumed by excessive exocytosis are replenished by accelerating vesicle endocytosis via a retrograde feedback mechanism involving nitric oxide released from postsynaptic cells. This homeostatic control system involves presynaptic cyclic GMP-dependent protein kinase (PKG) and a plasma membrane phospholipid, phosphatidylinositol-4,5-bisphophate (PIP2). We found that application of a Rho-kinase inhibitor, a PKG inhibitor or both, reduced the PIP2 content in Wistar rat brainstem synaptosomes to a similar extent. Likewise, application of the Rho-kinase inhibitor into the calyx of Held presynaptic terminal slowed vesicle endocytosis to the same degree as did application of the PKG inhibitor. This endocytic slowing effect of the Rho-kinase inhibitor was canceled by coapplication of PIP2 into the terminal. By contrast, a RhoA activator increased the PIP2 content and reversed the effect of the PKG inhibitor in brainstem synaptosomes. The RhoA activator, when loaded into calyceal terminals, also rescued the endocytic slowing effect of the PKG inhibitor. Furthermore, intraterminal loading of anti-PIP2 antibody slowed vesicle endocytosis and blocked the rescuing effect of the RhoA activator. We conclude that Rho-kinase links presynaptic PKG activity to PIP2 synthesis, thereby controlling the homeostatic balance of vesicle exocytosis and endocytosis in nerve terminals. PMID:23864695

Taoufiq, Zacharie; Eguchi, Kohgaku; Takahashi, Tomoyuki

2013-07-17

12

Analysis of cyclic creep and rupture. Part 1: bounding theorems and cyclic reference stresses  

Microsoft Academic Search

Cyclic loading on structures can produce failures not readily predicted by conventional static analysis. Ratcheting or incremental distortion leads to structural failure, and complicates the problems of creep and fatigue prediction. Predicting shakedown, ratcheting, accelerated creep and rupture, for cyclic loading, are the objectives of cyclic stress analysis.Limit load, shakedown and ratcheting analyses provide a comprehensive basis to understand static

P. Carter

2005-01-01

13

Making Ends Meet: Microwave-Accelerated Synthesis of Cyclic and Disulfide Rich Proteins Via In Situ Thioesterification and Native Chemical Ligation.  

PubMed

The development of synthetic methodologies for cyclic peptides is driven by the discovery of cyclic peptide drug scaffolds such as the plant-derived cyclotides, sunflower trypsin inhibitor 1 (SFTI-1) and the development of cyclized conotoxins. Currently, the native chemical ligation reaction between an N-terminal cysteine and C-terminal thioester group remains the most robust method to obtain a head-to-tail cyclized peptide. Peptidyl thioesters are effectively generated by Boc SPPS. However, their generation is challenging using Fmoc SPPS because thioester linkers are not stable to repeated piperidine exposure during deprotection. Herein we describe a Fmoc-based protocol for synthesizing cyclic peptides adapted for microwave assisted solid phase peptide synthesis. The protocol relies on the linker Di-Fmoc-3,4-diaminobenzoic acid, and we demonstrate the use of Gly, Ser, Arg and Ile as C-terminal amino acids (using HBTU and HATU as coupling reagents). Following synthesis, an N-acylurea moiety is generated at the C-terminal of the peptide; the resin bound acylurea peptide is then deprotected and cleaved from the resin. The fully deprotected peptide undergoes thiolysis in aqueous buffer, generating the thioester in situ. Ultimately, the head-to-tail cyclized peptide is obtained via native chemical ligation. Two naturally occurring cyclic peptides, the prototypical Möbius cyclotide kalata B1 and SFTI-1 were synthesized efficiently, avoiding potential branching at the diamino linker, using the optimized protocol. In addition, we demonstrate the possibility to use the approach for the synthesis of long and synthetically challenging linear sequences, by the ligation of two truncated fragments of a 50-residue long plant defensin. PMID:23504256

Gunasekera, Sunithi; Aboye, Teshome L; Madian, Walid A; El-Seedi, Hesham R; Göransson, Ulf

2012-10-14

14

Accelerated atmospheric corrosion testing using a cyclic wet/dry exposure test; Galvanic couples of aluminum with graphite neoprene rubber, galvanized steel, and steel  

SciTech Connect

Aluminum corrosion is important in overhead electrical conductors constructed from aluminum wire centrally reinforced by galvanized steel strands. Inspection of conductor after long service has implicated rubber bushing material, on the outside, and the galvanized strands, on the inside, as providing potential galvanic sites for the initiation of rapid aluminum corrosion. Therefore, the galvanic corrosion of aluminum in contact with graphite-loaded neoprene rubber, hot-dip galvanized steel and steel was assessed in a cyclic wet/dry exposure test using mixed-salts spray solutions containing appropriate ratios of sulfate and chloride ion. Aluminum was found to corrode at between 3 to 6 times its uncoupled rate when associated with the rubber material. While the eta-phase, relatively pure Zn, galvanized layer remained intact, galvanic corrosion of aluminum was slow. However, on exposure of the zeta-phase, Zn/Fe intermetallic layer, aluminum corroded about 35 times faster than expected in a solution with a high level of Cl{sup -} ion. The importance of these data to conductor lifetime is discussed.

Lyon, S.B.; Thompson, G.E.; Johnson, J.E.; Wood, G.C. (Manchester Univ. (UK). Inst. of Science and Technology); Ferguson, J.M. (Central Electricity Generating Board, Guildford (UK))

1989-11-01

15

Diagonally cyclic latin squares  

Microsoft Academic Search

A latin square of order n possessing a cyclic automorphism of order n is said to be diagonally cyclic because its entries occur in cyclic order down each broken diagonal. More generally, we consider squares possessing any cyclic automorphism. Such squares will be named after Parker, in recognition of his seminal contribution to the study of orthogonal latin squares. Our

Ian M. Wanless

2004-01-01

16

Bayes Analysis and Comparison of Accelerated Weibull and Accelerated Birnbaum–Saunders Models  

Microsoft Academic Search

Several models are proposed in the literature for modeling fatigue data resulting from materials subject to cyclic stress and strain. Accelerated Weibull and accelerated Birnbaum–Saunders distributions are most commonly used models. Whereas the accelerated Weibull model is easier compared to accelerated Birnbaum–Saunders, it fails to represent the situation equally well. The present article focuses on Bayes analysis of the two

S. K. Upadhyay; Bhaswati Mukherjee

2009-01-01

17

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.

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

1974-01-01

18

No Arithmetic Cyclic Quadrilaterals  

ERIC Educational Resources Information Center

A quadrilateral is arithmetic if its area is an integer and its sides are integers in an arithmetic progression, and it is cyclic if it can be inscribed in a circle. The author shows that no quadrilateral is both arithmetic and cyclic.

Beauregard, Raymond A.

2006-01-01

19

Decoding of Cyclic Codes.  

National Technical Information Service (NTIS)

The report is a Russian translation devoted to methods of construction and decoding of cyclic correction codes. The properties of linear cyclic codes are considered in detail and new results on construction and analysis of the properties of such codes are...

E. T. Mironchikov V. D. Kolesnik

1973-01-01

20

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

21

Are Math Grades Cyclical?  

ERIC Educational Resources Information Center

|The cyclical nature of mathematics grades was studied for a cohort of elementary school students from a large metropolitan school district in Texas over six years (average cohort size of 8495). The study used an autoregressive integrated moving average (ARIMA) model. Results indicate that grades do exhibit a significant cyclical pattern. (SLD)|

Adams, Gerald J.; Dial, Micah

1998-01-01

22

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

23

Linear Accelerators  

SciTech Connect

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 [Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna (Russian Federation)

2010-01-05

24

Cyclic Voltammetry Experiment.  

ERIC Educational Resources Information Center

Describes a three-part experiment designed to introduce cyclic voltammetry to graduate/undergraduate students. Part 1 demonstrates formal reduction potential, redox electron transfer, diffusion coefficient, and electrochemical reversibility. Part 2 investigates electrochemical behavior of acetaminophen. Part 3 examines such experimental variables…

Van Benschoten, James J.; And Others

1983-01-01

25

Radioimmunoassay for cyclic nucleotides  

SciTech Connect

An improved radioimmunoassay for the determination of cyclic nucleotides in body fluids which comprises adding a source of divalent cation prior to assay minimizes the effects of both endogenous calcium ion and EDTA used as an anticoagulant in blood plasma samples.

Chiang, C.S.

1984-02-21

26

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

27

Cyclic and chronic neutropenia.  

PubMed

Patients with severe chronic neutropenia have blood neutrophil level <0.5 × 10(9)/L, predisposing them to increased susceptibility to life-threatening bacterial infections. This chapter focuses on cyclic and congenital neutropenia, two very interesting and rare hematological conditions causing severe chronic neutropenia. Both disorders respond well to treatment with the myeloid growth factor, granulocyte colony-stimulating factor (G-CSF). This chapter describes the basic features of these diseases and addresses several current clinical issues regarding their diagnosis and management. Cyclic neutropenia is a rare, inherited autosomal dominant disorder due to mutations in the gene for neutrophil elastase (ELA-2 or ELANE). Usually these patients have regular oscillation of blood neutrophil counts with periods of severe neutropenia occurring every 21 days. During these periods, they have painful mouth ulcers, fevers, and bacterial infections. The most severe consequences are gangrene, bacteremia, and septic shock. Cyclic neutropenia patients respond well to treatment with granulocyte colony-stimulating factor (G-CSF) given by subcutaneous injections on a daily or alternate-day basis. Severe congenital neutropenia is also a rare hematological disease, but it is probably more common than cyclic neutropenia. Blood neutrophils are extremely low on a continuing basis; the levels may be <0.2 × 10(9)/L, and the risk of severe bacterial infections is even greater than in cyclic neutropenia. The majority of cases are due to autosomal dominant inheritance of mutations in the ELA-2 or ELANE gene. Less commonly, mutations in HAX-1, G6PC3, and other genes cause this disorder. Treatment with G-CSF is usually effective, but the dose of G-CSF required to normalize blood neutrophils varies greatly. Ten to thirty percent of severe congenital neutropenia patients evolve to develop acute myeloid leukemia, necessitating careful clinical monitoring. PMID:21052952

Dale, David C; Welte, Karl

2011-01-01

28

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

29

Linear Accelerators  

SciTech Connect

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

Sidorin, A. [Joint Institute for Nuclear Research, Dubna (Russian Federation)

2007-11-26

30

Cyclic Modular ?-Sheets  

PubMed Central

The development of peptide ?-hairpins is problematic, because folding depends on the amino acid sequence and changes to the sequence can significantly decrease folding. Robust ?-hairpins that can tolerate such changes are attractive tools for studying interactions involving protein ?-sheets and developing inhibitors of these interactions. This paper introduces a new class of peptide models of protein ?-sheets that addresses the problem of separating folding from sequence. These model ?-sheets are macrocyclic peptides that fold in water to present a pentapeptide ?-strand along one edge; the other edge contains the tripeptide ?-strand mimic Hao [JACS 2000, 122, 7654] and two additional amino acids. The pentapeptide and Hao-containing peptide strands are connected by two ?-linked ornithine (?Orn) turns [JACS 2003, 125, 876]. Each ?Orn turn contains a free ?-amino group that permits the linking of individual modules to form divalent ?-sheets. These “cyclic modular ?-sheets” are synthesized by standard solid-phase peptide synthesis of a linear precursor followed by solution-phase cyclization. Eight cyclic modular ?-sheets 1a–1h containing sequences based on ?-amyloid and macrophage inflammatory protein 2 were synthesized and characterized by 1H NMR. Linked cyclic modular ?-sheet 2, which contains two modules of 1b, was also synthesized and characterized. 1H NMR studies show downfield ?-proton chemical shifts, ?Orn ?-proton magnetic anisotropy, and NOE crosspeaks that establish all compounds but 1c and 1g to be moderately or well folded into a conformation that resembles a ?-sheet. Pulsed-field gradient NMR diffusion experiments show little or no self-association at low (? 2 mM) concentrations. Changes to the residues in the Hao-containing strands of 1c and 1g improve folding and show that folding of the structures can be enhanced without altering the sequence of the pentapeptide strand. Well-folded cyclic modular ?-sheets 1a, 1b, and 1f each have a phenylalanine directly across from Hao, suggesting that cyclic modular ?-sheets containing aromatic residues across from Hao are better folded.

Woods, R. Jeremy; Brower, Justin O.; Castellanos, Elena; Hashemzadeh, Mehrnoosh; Khakshoor, Omid; Russu, Wade A.

2008-01-01

31

Method of controlling cyclic variation in engine combustion  

DOEpatents

Cyclic variation in combustion of a lean burning engine is reduced by detecting an engine combustion event output such as torsional acceleration in a cylinder (i) at a combustion event (k), using the detected acceleration to predict a target acceleration for the cylinder at the next combustion event (k+1), modifying the target output by a correction term that is inversely proportional to the average phase of the combustion event output of cylinder (i) and calculating a control output such as fuel pulse width or spark timing necessary to achieve the target acceleration for cylinder (i) at combustion event (k+1) based on anti-correlation with the detected acceleration and spill-over effects from fueling. 27 figs.

Davis, L.I. Jr.; Daw, C.S.; Feldkamp, L.A.; Hoard, J.W.; Yuan, F.; Connolly, F.T.

1999-07-13

32

Surface and interface properties of carbon fiber composites under cyclical aging  

Microsoft Academic Search

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

Xinying Lv; Rongguo Wang; Wenbo Liu; Long Jiang

2011-01-01

33

Plasma accelerators  

SciTech Connect

In this paper we discuss plasma accelerators which might provide high gradient accelerating fields suitable for TeV linear colliders. In particular we discuss two types of plasma accelerators which have been proposed, the Plasma Beat Wave Accelerator and the Plasma Wake Field Accelerator. We show that the electric fields in the plasma for both schemes are very similar, and thus the dynamics of the driven beams are very similar. The differences appear in the parameters associated with the driving beams. In particular to obtain a given accelerating gradient, the Plasma Wake Field Accelerator has a higher efficiency and a lower total energy for the driving beam. Finally, we show for the Plasma Wake Field Accelerator that one can accelerate high quality low emittance beams and, in principle, obtain efficiencies and energy spreads comparable to those obtained with conventional techniques.

Ruth, R.D.; Chen, P.

1986-03-01

34

The effects of aging on the cyclic stress-strain behavior and hysteresis loop evolution of lead free solders  

Microsoft Academic Search

Solder joints in electronic assemblies are typically subjected to thermal cycling, either in actual application or in accelerated life testing used for qualification. Mismatches in the thermal expansion coefficients of the assembly materials leads to the solder joints being subjected to cyclic (positive\\/negative) mechanical strains and stresses. This cyclic loading leads to thermomechanical fatigue damage that involves damage accumulation, crack

Muhannad Mustafa; Zijie Cai; Jeffrey C. Suhling; Pradeep Lall

2011-01-01

35

Future accelerators (?)  

SciTech Connect

I describe the future accelerator facilities that are currently foreseen for electroweak scale physics, neutrino physics, and nuclear structure. I will explore the physics justification for these machines, and suggest how the case for future accelerators can be made.

John Womersley

2003-08-21

36

Rope of Cyclical Helical Surfaces  

NASA Astrophysics Data System (ADS)

This paper describes one method for modeling the rope of cyclical helical surfaces as surfaces of technical practice. The cyclical helical surfaces are generated by continuous movement of the circle together with the moving trihedron of the helix along this helix. The rope is composed of equal sets of cyclical surfaces in two layers. In this paper there is described the creation of straight and helical rope and vector functions of the surfaces in the rope are derived. The author visualizes the resulting surfaces in the rope obtained by its parametric approach in the MAPLE program.

Olejníková, Tatiana

2012-11-01

37

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

38

Ring Injector of the IHEP Accelerator.  

National Technical Information Service (NTIS)

IHEP synchrotron new injection system under construction including 1.5 GeV high-cyclic booster has been described. Booster intensity equals 1.7x10 exp 12 prot/pulse, pulse recurrence frequency equals 20 Hz. 30 MeV ''Ural-30'' linear accelerator is being d...

Y. M. Ado E. A. Aleev V. I. Balbekov

1977-01-01

39

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.

Botsford, J L; Harman, J G

1992-01-01

40

Release of prostaglandins from the isolated frog ventricle and associated changes in endogenous cyclic nucleotide levels.  

PubMed Central

1. A study has been made of the decline in contractility and some associated metabolic changes which occur in the isolated frog ventricle during the development of hypodynamic depression. 2. The release of two identified prostaglandins (PG), E1 and E2, together with several as yet unknown prostaglandin-related substances (PRS), accompanies the development of hypodynamic depression. There is a close correlation between the extent to which the isometric twitch is depressed and the quantity of prostaglandin released into the superfusate. 3. Fractionation of extracts of 'used' superfusates, using preparative-scale thin-layer chromatography, revealed the presence of six major components, four of which (PGE1 and PGE2 and two unidentified components) were found to be cardioactive and potentiated contraction when tested subsequently on hypodynamic preparations. 4. Two agents which influence prostaglandin biosynthesis, arachidonic acid and indomethacin, are found to affect both the rate at which the hypodynamic state develops and the extent to which the 'steady-state' twitch tension is depressed, in a dose-dependent manner. Indomethacin, a PG-synthetase inhibitor, accelerates the decay and depresses the final 'steady-state' tension attained, whereas arachidonic acid, the principal precursor for prostaglandin biosynthesis, has the converse effects. 5. Measurements of endogenous 3'5'-cyclic nucleotide levels reveal a time-dependent decrease in intracellular adenosine 3'5'-cyclic monophosphate (3'5'-cyclic AMP) and a concomitant increase in guanosine 3'5' cyclic monophosphate (3'5'-cyclic GMP). The decline in isometric twitch tension is paralleled almost exactly by an equivalent reduction in the ratio 3'5'-cyclic AMP: 3'5'-cyclic GMP. 6. Superfusion of isolated ventricles with Ringer solution containing exogenous, lipid-soluble derivatives of 3'5'-cyclic AMP and 3'5'-cyclic GMP affects both the rate of decline of the isometric twitch and the steady-state tension ultimately reached: thus, 8-bromo-3'5'-cyclic GMP accelerates the decline in contractility and depresses the steady-state level, whereas dibutyryl 3'5'-cyclic AMP delays the development of hypodynamic depression, and elevates the final twitch tension. The effects of both 3'5' cyclic nucleotide derivatives are dose-dependent. 7. The possible involvement of prostaglandins and 3'5'-cyclic nucleotides as causal agents in the mechanism of hypodynamic depression is discussed. The biochemical basis for the implied antangonistic effects of 3'5'-cyclic AMP and 3'5'-cyclic GMP in regulating ventricular contractility is considered in the following paper (Flitney & Singh, 1980).

Flitney, F W; Singh, J

1980-01-01

41

Cyclic phosphines as flame retardants  

US Patent & Trademark Office Database

The present invention is related to the use of specific cyclic and/or polymeric aryl-phosphines as flame retardants and to a method for reducing the flammability of organic material by incorporating into the material these specific cyclic and/or polymeric phosphines. Moreover, the invention is related to a polymeric composition containing a polymeric material and at least one of the specific cyclic and/or polymeric phosphines in an amount of from 1 to 15% by weight, based on the weight of the polymeric material. The invention also relates to a composition comprising at least one of the specific cyclic and/or polymeric phosphines and at least one polymerizable monomer.

2013-08-27

42

Cyclic Strength of Titanium Alloys.  

National Technical Information Service (NTIS)

Results of fatigue and corrosion fatigue tests of certain titanium alloys, materials that show promise in transport ship building, are presented. Tests for low cyclic fatigue in a corrosive environment revealed marked reduction in longevity of notched spe...

E. D. Shekhovstsev E. N. Kostrov Y. E. Zobachev

1972-01-01

43

Genetics Home Reference: Cyclic neutropenia  

MedlinePLUS

... is thought to be responsible for the cyclic nature of this condition. When the affected neutrophils die ... Center . Where can I find general information about genetic conditions? The Handbook provides basic information about genetics ...

44

Five cases of cyclical Cushing's syndrome  

Microsoft Academic Search

Reported cases of cyclical Cushing's syndrome are rare. Of 14 successive patients with Cushing's syndrome nine collected sequential urine samples for the estimation of cortisol:creatinine ratio. Five had cyclical Cushing's syndrome while two had considerable variation in urinary cortisol excretion without a cyclical pattern being established. Two of the five patients with a cyclical syndrome had paradoxical responses to dexamethasone.

A B Atkinson; A L Kennedy; D J Carson; D R Hadden; J A Weaver; B Sheridan

1985-01-01

45

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.

46

Radical Acceleration  

ERIC Educational Resources Information Center

|Research has found that teachers' objections to accelerating gifted students are mainly based on a fear that acceleration will lead to social or emotional damage. Ironically, it is the academic and emotional maturity which characterizes intellectually gifted students, coupled with their high levels of academic achievement, which makes them such…

Gross, Miraca U. M.; Van Vliet, Helen E.

2005-01-01

47

Cyclic nucleotide phosphodiesterases in pancreatic islets  

Microsoft Academic Search

Cyclic nucleotide phosphodiesterases (PDEs) comprise a family of enzymes (PDE1-PDE11) which hydrolyse cyclic AMP and cyclic GMP to their biologically inactive 5 derivatives. Cyclic AMP is an important physiological amplifier of glucose-induced insulin secretion. As PDEs are the only known mechanism for inactivating cyclic nucleotides, it is important to characterise the PDEs present in the pancreatic islet beta cells. Several

N. J. Pyne; B. L. Furman

2003-01-01

48

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

49

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

50

Cyclic foam topological field theories  

NASA Astrophysics Data System (ADS)

This paper proposes an axiomatic form for cyclic foam topological field theories, that is, topological field theories corresponding to string theories where particles are arbitrary graphs. World surfaces in this case are 2-manifolds with one-dimensional singularities. I prove that cyclic foam topological field theories are in one-to-one correspondence with graph-Cardy-Frobenius algebras that are families (A,B?,?) where A={As|s?S} are families of commutative associative Frobenius algebras, B?=?B? is an associative algebra of Frobenius type graduated by graphs, and ?={??s:As?End(B?)|s?S,???} is a family of special representations. Examples of cyclic foam topological field theories and graph-Cardy-Frobenius algebras are constructed.

Natanzon, Sergey M.

2010-06-01

51

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

52

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

53

Angular Acceleration  

NSDL National Science Digital Library

The simulation of a rotating wheel below shows the relationship between angular position, angular velocity, and angular acceleration. Graphs of angular position and angular velocity as a function of time are shown.

Christian, Wolfgang; Belloni, Mario

2008-02-19

54

ION ACCELERATOR  

DOEpatents

An arrangement for the drift tubes in a linear accelerator is described whereby each drift tube acts to shield the particles from the influence of the accelerating field and focuses the particles passing through the tube. In one embodiment the drift tube is splii longitudinally into quadrants supported along the axis of the accelerator by webs from a yoke, the quadrants. webs, and yoke being of magnetic material. A magnetic focusing action is produced by energizing a winding on each web to set up a magnetic field between adjacent quadrants. In the other embodiment the quadrants are electrically insulated from each other and have opposite polarity voltages on adjacent quadrants to provide an electric focusing fleld for the particles, with the quadrants spaced sufficienily close enough to shield the particles within the tube from the accelerating electric field.

Bell, J.S.

1959-09-15

55

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

56

3':5'Cyclic AMP and Hormonal Control of Puparium Formation in the Fleshfly Sarcophaga bullata  

Microsoft Academic Search

Injection of 3':5'-cyclic AMP (cAMP) into larvae of the fly Sarcophaga bullata 3-4 hr before the beginning of puparium formation (red-spiracle stage) greatly accelerates the onset of tanning without affecting initiation of puparium formation (anterior retraction). Accelerated tanning resembles real tanning in two important respects: the solubility of cuticular proteins becomes reduced and [U-14C]tyrosine is incorporated into the cuticle. Of

G. Fraenkel; Ann Blechl; James Blechl; Paul Herman; Morris I. Seligman

1977-01-01

57

Note on Fast Cyclic Convolution.  

National Technical Information Service (NTIS)

The note presents a new algorithm for computing the cyclic convolution of two vectors over a commutative ring. The algorithm requires n((n sub 1)+1)...((n sub k)+1)/(2 to the kth power) multiplications for the convolution of two n-vectors, where n=(n sub ...

Y. Zalcstein

1970-01-01

58

Cyclical Upswing is Gaining Momentum  

Microsoft Academic Search

The cyclical forces driving the economy are getting stronger. Exports and output in manufacturing post high gains, and an increasing number of enterprises is viewing the economic situation with optimism. Most economic indicators suggest that the present upturn is proceeding at a faster pace than the recovery after the recession of 1982-83. The main problem areas continue to be the

Ewald Walterskirchen

1994-01-01

59

The endogenous cyclic AMP antagonist, cyclic PIP: its ubiquity, hormone-stimulated synthesis and identification as prostaglandylinositol cyclic phosphate.  

PubMed

This report shows that the cyclic AMP antagonist cyclic PIP is present in all organs and tissues of the rat so far examined: brain, heart, lung, intestine, kidney, liver, spleen, skeletal muscle and fat. The synthesis of cyclic PIP is stimulated by insulin or noradrenaline (alpha-adrenergic action) in a dose-dependent fashion. Increasing cyclic PIP synthesis with increasing insulin concentrations matches the insulin receptor binding curves. Cyclic PIP levels in blood serum remain low after hormonal stimulation and no cyclic PIP can be detected in urine. As an indication of its ubiquity, cyclic PIP was even detected in yeast. Prostaglandin E (as shown by incorporation of [3H]PGE into cyclic PIP and demonstration of a constant specific activity), myo-inositol (as shown by acid hydrolysis of the dephosphorylated cyclic PIP and mass spectrometric identification of the products) and one phosphate (as shown by the ionic nature of cyclic PIP and its inactivation by phosphodiesterase plus phosphatase) are components of cyclic PIP. Chemical derivatization experiments of cyclic PIP suggest the phosphate to be bound to myo-inositol and the myo-inositol phosphate to the prostaglandin E by its C15-hydroxyl group. PMID:8180414

Wasner, H K; Salge, U; Gebel, M

1993-01-01

60

Cumulative Fatigue Damage under Cyclic Strain Control.  

National Technical Information Service (NTIS)

Cyclic deformation resistance and fatigue damage accumulation are investigated using multiple level strain control. Data are reported for 2024-T4 and 7075-T6 aluminum alloys, aircraft quality SAE 4340 steel, and Titanium 811. Effects of cyclic strain leve...

T. H. Topper B. I. Sandor J. D. Morrow

1967-01-01

61

Cyclic deformation and fracture behavior of Al alloy 6061 under the action of positive mean stresses  

NASA Astrophysics Data System (ADS)

Cyclic deformation and fatigue fracture behavior of Al alloy 6061 were studied over an extensive range of positive mean stress. In the regime of low cyclic stress amplitude, both secondary stage creep rate and fracture process are retarded by decreasing mean stress, but they are accelerated if the cyclic stress ratio is smaller than 0. 75. The superimposition of cyclic compressive stress is found to decrease the creep rate, but it has no effect on the relationship between fatigue life and mean stress. Characteristic patterns on the specimen fracture surfaces, representing the interaction between creep and fatigue and also the mechanism of the fatigue-creep deformation in different mean stress ranges, are discussed analytically. Finally, the concept of equivalent creep rate is proposed and a method to predict fatigue life with positive mean stresses is established and verified using the present experimental results.

Yang, Zhi'an; Wang, Zhirui

1993-09-01

62

Origin of Cyclic Adenosine Monophosphate in Saliva  

Microsoft Academic Search

The level of cyclic adenosine monophosphate (AMP) in duct saliva from the dog submandibular gland was increased after cyclic AMP was administered intravenously in vivo. Isoproterenol increased the level of cyclic AMP in plasma and saliva in vivo and in salivary gland slices in vitro, but increased the level only slightly in saliva in a perfused dog submaxillary gland.

Takao Kanamori; Toshiharu Nagatsu; Shosei Matsumoto

1975-01-01

63

Bronchodilator drug efficacy via cyclic AMP  

Microsoft Academic Search

Cyclic adenosine 3', 5'-monophosphosphate (cyclic AMP) as measured by radioimmunoassay is found in diced rat lung in an amount approximating one picomole per milligram of wet weight lung tissue. Incubation of rat lung with adrenaline, a beta adrenergic agent, produced a rapid increase in cyclic AMP, 100% increase at 15 seconds and 340% at 2 minutes. Isoprenaline was more stimulatory

P E Duncan; J P Griffin; S S Solomon

1975-01-01

64

21 CFR 862.1230 - Cyclic AMP test system.  

Code of Federal Regulations, 2010 CFR

... Cyclic AMP test system. (a) Identification. A cyclic AMP test system is a device intended to measure the level of adenosine 3â², 5â²-monophosphate (cyclic AMP) in plasma, urine, and other body fluids. Cyclic AMP measurements are...

2009-04-01

65

21 CFR 862.1230 - Cyclic AMP test system.  

Code of Federal Regulations, 2010 CFR

... Cyclic AMP test system. (a) Identification. A cyclic AMP test system is a device intended to measure the level of adenosine 3â², 5â²-monophosphate (cyclic AMP) in plasma, urine, and other body fluids. Cyclic AMP measurements are...

2010-04-01

66

Photodissociation Spectra of Cyclic and Non-Cyclic Nucleotides  

NASA Astrophysics Data System (ADS)

We have studied the UV photodepletion and photofragment action spectra of deprotonated adenosine monophosphate and guanosine monophosphate as well as their cyclic analogs. We observe the same anionic fragments as in earlier experiments on collision-induced dissociation of deoxyribonucleotides, although their relative intensities are quite different, especially with respect to the abundance of the deprotonated base anions. The suppression and amplification of spectral features provides information about the threshold energies for the active fragment channels.

Kaufman, Sydney H.; Marcum, Jesse C.; Weber, J. Mathias

2010-06-01

67

The effects of surface pretreatment on the cyclic-fatigue characteristics of bonded aluminium-alloy joints  

Microsoft Academic Search

The present work has used an accelerated test method, based upon cyclic-fatigue testing using a fracture-mechanics approach, to study the durability of organosilane-pretreated joints which were adhesively-bonded using a hot-cured epoxy-film adhesive. The silane primer investigated was ?-glycidoxypropyltrimethoxysilane (GPS). The cyclic-fatigue tests were mainly conducted in (a) a ‘dry’ environment of 25±2°C with a relative humidity of 55±5% and (b)

M.-L. Abel; A. N. N. Adams; A. J. Kinloch; S. J. Shaw; J. F. Watts

2006-01-01

68

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

69

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 reasoning–what you think I think you think–will 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.

Frey, Seth; Goldstone, Robert L.

2013-01-01

70

MUON ACCELERATION  

SciTech Connect

One of the major motivations driving recent interest in FFAGs is their use for the cost-effective acceleration of muons. This paper summarizes the progress in this area that was achieved leading up to and at the FFAG workshop at KEK from July 7-12, 2003. Much of the relevant background and references are also given here, to give a context to the progress we have made.

BERG,S.J.

2003-11-18

71

3':5'-cyclic AMP and hormonal control of puparium formation in the fleshfly Sarcophaga bullata.  

PubMed

Injection of 3':5'-cyclic AMP (cAMP) into larvae of the fly Sarcophaga bullata 3-4 hr before the beginning of puparium formation (red-spiracle stage) greatly accelerates the onset of tanning without affecting initiation of puparium formation (anterior retraction). Accelerated tanning resembles real tanning in two important respects: the solubility of cuticular proteins becomes reduced and [U-14C]tyrosine is incorporated into the cuticle. Of a number of cAMP analogues tested, 3':5'- cyclic GMP, 2':3'-cyclic AMP, and 5'-AMP were inactive, dibutyryl-3':5'-cAMP had only slight activity, and cyclic IMP and deoxy-3':5'-cAMP showed some activity. Theophylline enhanced the effect of small doses of cAMP or of blood, diluted 1:8, active in the puparium tanning factor. Injection of dopa, dopamine, acetyldopamine, or epinephrine, but not of tyrosine, had an accelerating effect similar to that of cAMP. The tanning-inhibiting effect of DL-alpha-methyl-alpha-hydrazino-beta-(3,4-dihydroxyphenyl)propionic acid monohydrate is reversed by dopamine or epinephrine, but not by tyrosine, dopa, or cAMP. Evidence is presented to indicate that the responses to cAMP are not artifacts but reflect actual biochemical events during tanning. PMID:194250

Fraenkel, G; Blechl, A; Blechl, J; Herman, P; Seligman, M I

1977-05-01

72

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

73

Cyclic sciatica. A case report.  

PubMed

We report a case of endometrioma in the pelvic cavity. A 41-year-old woman presented with a peculiar periodic sciatica associated with her menses. Computed tomography showed an oval-shaped mass in the pelvic cavity compressing the right sciatic nerve. To confirm the diagnosis, hormonal therapy through nose dropping of buserelin acetate was given to stop menstruation. After treatment, her symptoms disappeared completely. When a sciatica is closely related to menses, orthopedic surgeons should consider cyclic sciatica resulting from endometrioma as a differential diagnosis. PMID:8153814

Takata, K; Takahashi, K

1994-01-01

74

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

75

Boolean Decomposition Based on Cyclic Chains  

Microsoft Academic Search

We present a new algorithm for decomposition of type f=g·h+r. The algorithm searches for Boolean products g·h of a special type, called cyclic chains. The number of cubes in a cyclic chain is no greater than the number of cubes in the part of the on-set of f covered by this chain. The number of literals is always smaller. Cyclic

Elena Dubrova; Maxim Teslenko; Johan Karlsson

2003-01-01

76

Plasma accelerators; Plazmennye uskoriteli  

Microsoft Academic Search

Papers concerning the physical processes in plasma accelerators are ; included, covering some specific accelerator types, magnetic plasma compressors, ; plasma diagnostics methods, and plasma accelerator applications in thermonuclear ; studies, gasdynamics, and space studies. The topics also include plasma ; acceleration control problems, high-vacuum technology, plasma accelerator designs ; with narrow and broad acceleration zones, and electrode processes in

Artsimovich

1973-01-01

77

Cyclic Vomiting Syndrome Developed after Stroke  

PubMed Central

Cyclic vomiting syndrome is characterized by recurrent episodes of stereotyped vomiting separated by regular symptom-free periods. We describe a case of cyclic vomiting syndrome developed after stroke, which has not been reported to date. A 69-year-old woman experienced recurrent vomiting following left cerebral infarct. The patient's vomiting pattern was consistent with cyclic vomiting syndrome, and the diagnosis of cyclic vomiting syndrome was established by exclusion of other known disorders which could have resulted in vomiting. She was treated with imipramine hydrochloride and her symptom was well controlled.

Shin, Jung In

2012-01-01

78

Copper-catalyzed oxidation of arene-fused cyclic amines to cyclic imides.  

PubMed

A novel copper-catalyzed oxidation of arene-fused cyclic amines to the corresponding cyclic imides has been developed. The reaction can be used to synthesize 1,3-disubstituted TPD in high yields. PMID:24100546

Yan, Xiaoyu; Fang, Kun; Liu, Hailan; Xi, Chanjuan

2013-10-17

79

Cyclic Behavior and Damage Analysis of Brass under Cyclic Torsional Loading  

Microsoft Academic Search

Fatigue behavior of brass was studied at a constant deformation rate of 5.6 ? 10?3 s?1 to understand the cyclic behavior and fatigue life under cyclic torsional deformation. Strains were in the range of 0.35\\u000a to 4.2%. In the as-drawn condition, it was found that the cyclic hardening\\/softening behavior strongly depends on the strain\\u000a amplitude. For low strain amplitude, cyclic saturation occurred after

Ridha Mnif; Mohamed Kchaou; Riadh Elleuch; Foued Halouani

2007-01-01

80

Biological conversion of cyclic alkanes and cyclic alcohols into dicarboxylic acids: biochemical and molecular basis  

Microsoft Academic Search

. Biological oxidation of cyclic alkanes and cyclic alcohols normally results in formation of the corresponding dicarboxylic acids, which are further metabolized in the cell. The biochemical pathways for oxidative conversion of cyclic compounds are similar in various phylogenetically diverse bacteria. Significant progress has been made in the past 2 years in the isolation and characterization of genes involved in

Q. Cheng; S. M. Thomas; P. Rouvière

2002-01-01

81

Cyclic stress-strain curves generated from random cyclic strain amplitude tests  

Microsoft Academic Search

Cyclic tests have been carried out to investigate the cyclic behaviour of two steels using a random sequence of cyclic strains. The waveform was triangular with a constant strain rate between reversals. It was found that a plot of stress and strain differences between successive reversals exhibited an apparent dual elastic region which was attributed to a stress relaxation effect

A Jones; R. C Hudd

1999-01-01

82

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

83

Evaluation of Anti-Weathering Performance of Different Construction Steels by inDoor Cyclic Corrosion Tests  

Microsoft Academic Search

Anti-weathering performance of the fire-resistant construction steel WGJ510C2, produced by Wuhan Steel, was investigated by in-door accelerated cyclic corrosion test (CCT), which is compared with the performance of conventional construction steels Q235 and Q345 studied by a compound circulation corrode testing. It was found that the corrosion speed and corrosion acceleration of WGJ510C2 is obviously lower than that of Q235

Ji-xiong LIU; Shi-hua CHEN; Jing LIU; Wan-ling ZHANG; Xiao CHEN

2007-01-01

84

Accelerating projects  

SciTech Connect

This chapter describes work at ORNL in the period around 1950, when the laboratory was evolving from its original mission of research aimed at producing the atomic bomb, to a new mission, which in many ways was unclear. The research division from Y-12 merged with the laboratory, which gave an increased work force, access to a wide array of equipment, and the opportunity to work on a number of projects related to nuclear propulsion. The first major project was for a nuclear aircraft. From work on this program, a good share of the laboratories work in peaceful application of nuclear energy would spring. A major concern was the development of light weight shielding to protect the crew and materials in such a plane. To do such shielding work, the laboratory employed existing, and new reactors. The original plans called for the transfer of reactor work to Argonne, but because of their own research load, and the needs of the lab, new reactor projects were started at the lab. They included the Low Intensity Test Reactor, the Swimming Pool Reactor, the Bulk Shielding Reactor, the Tower Shielding Facility, and others. The laboratory was able to extend early work on calutrons to accelerator development, pursuing both electrostatic accelerators and cyclotrons. The aircraft project also drove the need for immense quantities of scientific data, with rapid analysis, which resulted the development of divisions aimed at information support and calculational support. The laboratory also expanded its work in the effects of radiation and cells and biological systems, as well as in health physics.

Not Available

1992-01-01

85

Cyclical subnormal separation in A-groups.  

National Technical Information Service (NTIS)

Three main results, concerning A-groups in respect of cyclical subnormal separation as defined in, are presented. It is shown in theorem A that any A-group that is generated by elements of prime order and satisfying the cyclical subnormal separation condi...

M. U. Makarfi

1995-01-01

86

Cyclic electron flow in C3 plants  

Microsoft Academic Search

This paper summarized our present view on the mechanism of cyclic electron flow in C3 plants. We propose that cyclic and linear pathways are in competition for the reoxidation of the soluble primary PSI acceptor, Ferredoxin (Fd), that freely diffuses in the stromal compartment. In the linear mode, Fd binds ferredoxin-NADP-reductase and electrons are transferred to NADP+ and then to

Pierre Joliot; Anne Joliot

2006-01-01

87

Cyclic spectral analysis of radio pulsars  

Microsoft Academic Search

Cyclic spectral analysis is a signal-processing technique designed to deal with stochastic signals whose statistics vary periodically with time. Pulsar radio emission is a textbook example of this signal class, known as cyclostationary signals. In this paper, we discuss the application of cyclic spectral analysis methods to pulsar data and compare the results with the traditional filterbank approaches used for

P. B. Demorest

2011-01-01

88

Modular and p-adic Cyclic Codes  

Microsoft Academic Search

This paper presents some basic theorems giving the structure of cyclic codes of length n over the ring of integers modulo pa and over the p-adic numbers, where p is a prime not dividing n. An especially interesting example is the 2-adic cyclic code of length 7 with generator polynomial X3 + ?X2 + (? ? 1)X ? 1, where

A. Robert Calderbank; Neil J. A. Sloane

1995-01-01

89

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

90

The Role of Peel Stresses in Cyclic Debonding.  

National Technical Information Service (NTIS)

When an adhesively bonded joint is undergoing cyclic loading, one of the possible damage modes that occurs is called cyclic debonding - progressive separation of the adherends by failure of the adhesive bond under cyclic loading. In most practical structu...

R. A. Everett

1982-01-01

91

Teleportation of accelerated information  

NASA Astrophysics Data System (ADS)

A theoretical quantum teleportation protocal is suggested to teleport accelerated and non-accelerated information over different classes of accelerated quantum channels. For the accelerated information, it is shown that the fidelity of the teleported state increases as the entanglement of the initial quantum channel increases. However as the difference between the accelerated channel and the accelerated information decreases the fidelity increases. The fidelity of the non accelerated information increases as the entanglement of the initial quantum channel increases, while the accelerations of the quantum channel has a little effect. The possibility of sending quantum information over accelerated quantum channels is much better than sending classical information.

Metwally, Nasser

2013-01-01

92

Synthesis of superhard nanodispersed titanium compounds in a magnetoplasma accelerator operating in pulse-periodic regime  

NASA Astrophysics Data System (ADS)

It is demonstrated that a system based on a coaxial magnetoplasma accelerator with multiple use of the titanium barrel for a consumable provides a dynamic synthesis of nanodispersed titanium-based crystal phases such as cubic titanium nitride (cTiN) and TiO2. The efficiency of material yield from the surface of the accelerating channel of the titanium barrel increases for cyclic regime of accelerator operation with dead time smaller than 1.0 s.

Sivkov, A. A.; Gerasimov, D. Yu.; Saigash, A. S.; Evdokimov, A. A.

2012-03-01

93

Linear Accelerator (LINAC)  

MedlinePLUS

... of page • Equipment View larger with caption The linear accelerator uses microwave technology (similar to that used for radar) to accelerate electrons in a part of the accelerator called the "wave guide," then allows these electrons to collide with ...

94

Ionic pores formed by cyclic peptides.  

PubMed

It is shown that 2 cyclic tetrapeptides, namely tentoxin and HC toxin, are able to induce the formation of transmembrane ionic channels, although a carrier mechanism could be expected on the basis of their chemical structure (presence of proline or N-methylated residues). Since other cyclic peptides but of larger size, i.e., tyrocidines, gramicidin S (decapeptides) and an octapeptide with a sequence similar to that of HC toxin, are also able to form pores, it appears that this property can be extended to a large number of cyclic peptides. A pore structure based on aggregates is proposed. PMID:2470418

Heitz, F; Kaddari, F; Van Mau, N; Verducci, J; Raniri Seheno, H; Lazaro, R

1989-01-01

95

Cyclic steps formed by turbidity currents  

NASA Astrophysics Data System (ADS)

Levees of channels formed due to turbidity currents on submarine fans are often covered with step like bedforms. Circumstantial evidences emerged with numerical and experimental studies have suggested these sediment waves should probably be cyclic steps. The formation of cyclic steps in sub-aqueous environments through a mathematical perspective is presented in this research. A mathematical model preserving essential physics of the system is solved for one step wave length to obtain a preserved step shape of upstream migrating steps and the behavior of characteristic parameters governing this cyclic step formation phenomenon.

Dias, Duleeka Dahampriya; Izumi, Norihiro; Yokokawa, Miwa

96

Processable cyclic peptide nanotubes with tunable interiors.  

PubMed

A facile route to generate cyclic peptide nanotubes with tunable interiors is presented. By incorporating 3-amino-2-methylbenzoic acid in the D,L-alternating primary sequence of a cyclic peptide, a functional group can be presented in the interior of the nanotubes without compromising the formation of high aspect ratio nanotubes. The new design of such a cyclic peptide also enables one to modulate the nanotube growth process to be compatible with the polymer processing window without compromising the formation of high aspect ratio nanotubes, thus opening a viable approach toward molecularly defined porous membranes. PMID:21894889

Hourani, Rami; Zhang, Chen; van der Weegen, Rob; Ruiz, Luis; Li, Changyi; Keten, Sinan; Helms, Brett A; Xu, Ting

2011-09-14

97

Cyclic crack resistance of an anticorrosion surfacing steel joint  

SciTech Connect

An investigation was made of the cyclic crack resistance of the austenitic surfacing - 15Kh2MFA steel transition zone taking into consideration the fatigue crack geometry, the fracture mechanism, and the effect of crack closure. Microstructural analysis showed significant heterogeneity of the surfacing-base metal transition zone. An analysis of the base metal showed that in the area of low-fatigue crack growth rates, there is a significant spread in the experimental data obtained in tests of three specimens. Under steady service conditions, an increased loading asymmetry sharply accelerates failure of the alloy as the result of growth only of the subsurfacing crack, which is partically insensitive to the direction of crack development and to structural changes in the transition zone materials.

Zuezdin, Y.I.; Andrusiv, B.N.; Nikiforchin, G.N.; Timofeev, B.T.; Zima, Y.V.

1986-03-01

98

Alterations in cyclic necleotides in dogs after triiodothyronine.  

PubMed

The effects of triiodothyronine (T3) on plasma and tissue levels (liver, adipose tissue, muscle) of adenosine 3',5'-monophosphate (cyclic GMP) were determined in Mongrel dogs. Plasma cyclic AMP increased to a mean plateau value 165% greater than control values in response to a single intravenous injection of T3 (100-200 mug/kg body weight). This treatment resulted in no increase in plasma cyclic GMP. In liver, cyclic AMP concentration decreased 54%, while cyclic GMP increased 137%. Adipose tissue cyclic AMP levels decreased in control animals during the experimental procedure. On the other hand, animals given T3 had stable or (in one case) increasing adipose tissue cyclic AMP levels. Hence, T3, actually maintained higher levels than that expected, in comparison to the control. Cyclic GMP levels in adipose tissue were not affected by T3. Cyclic AMP and cyclic GMP were unchanged in muscle. In all cases, a time lag occurred (30-45 min) between administration of T3 and subsequent alterations in cyclic nucleotide levels. It was concluded that T3 is capable of altering concentrations of cyclic AMP and cyclic GMP in vivo and that cyclic AMP and cyclic GMP patterns of response are completely different. In liver, a converse relation of the two nucleotides is present. These findings are compatible with the hypothesis that some of T3's action may be explained by its effects upon either cyclic AMP or cyclic GMP. PMID:165647

Fernandez-Pol, J A; Hays, M T

1975-05-01

99

Fatigue Failure Criteria for Combined Cyclic Stress.  

National Technical Information Service (NTIS)

Failure criteria for combined cyclic stress are represented in terms of parametric families of failure surfaces in stress space. Quadratic approximations and symmetry arguments are employed in systematic fashion to construct isotropic failure criteria for...

Z. Hashin

1979-01-01

100

Genetics Home Reference: Cyclic vomiting syndrome  

MedlinePLUS

... Most people with cyclic vomiting syndrome have normal intelligence, although some affected people have experienced developmental delay ... of mitochondrial DNA. These changes likely impair the ability of mitochondria to produce energy. Defects in energy ...

101

Anelastic relaxation controlled cyclic creep and cyclic stress rupture behavior of an oxide dispersion strengthened alloy  

Microsoft Academic Search

Cyclic creep deceleration relative to static creep was observed in oxide dispersion strengthened alloy Inconel MA 754 at 760\\u000a °C and cyclic stresses of 221 MPa-41 MPa, 231 MPa-41 MPa, and 241 MPa-41 MPa. Tests were run over the range of frequency from\\u000a 0.05 cycles per hour to six cycles per hour. The maximum cyclic deceleration, which was manifested as

D. E. Matejczyk; Y. Zhuang; J. K. Tien

1983-01-01

102

Anelastic relaxation controlled cyclic creep and cyclic stress rupture behavior of an oxide dispersion strengthened alloy  

Microsoft Academic Search

Cyclic creep deceleration relative to static creep was observed in oxide dispersion strengthened alloy Inconel MA 754 at 760 °C and cyclic stresses of 221 MPa-41 MPa, 231 MPa-41 MPa, and 241 MPa-41 MPa. Tests were run over the range of frequency from 0.05 cycles per hour to six cycles per hour. The maximum cyclic deceleration, which was manifested as

D. E. Matejczyk; Y. Zhuang; J. K. Tien

1983-01-01

103

Cyclicity and manic-depressive illness  

Microsoft Academic Search

In an historical overview of the development of the concept of cyclicity and its fundamental significance in manic-depressive\\u000a illness, we underscore how the concept fell into neglect only to re-emerge in recent years. We then look at the intimate relationship\\u000a between cyclicity and the seasons, before moving on to examine the frequency of cycles and the varying patterns of the

Athanasios Koukopoulos; Gabriele Sani; Alexia E. Koukopoulos; Paolo Girardi

104

The Cyclic Executive Model and Ada  

Microsoft Academic Search

Periodic processes are major parts of many real-time embedded computer applications. The programming language Ada permits\\u000a programming simple periodic processes, but it has some serious limitations; producing Ada programs with real-time performance\\u000a comparable to those produced to date using traditional cyclic executives requires resorting to techniques that are specific\\u000a to one machine or compiler. We present and evaluate the cyclic

Theodore P. Baker; Alan C. Shaw

1989-01-01

105

Cyclic undrained behavior of silty sand  

Microsoft Academic Search

Laboratory cyclic triaxial tests were performed to investigate the effect of fine content on the pore pressure generation in sand. Strain-controlled, consolidated undrained tests have been performed with a cyclic shear strain range of 0·015-1·5%. These tests were carried to 1000 cycles or to initial liquefaction, which ever occurred first. Triaxial tests were performed on pure sand silt specimens and

D. Erten; M. H. Maher

1995-01-01

106

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

107

Cyclic fatigue of zirconia ceramics  

SciTech Connect

Uniaxial tension-compression fatigue behavior was studied for 3 mol% yttria-stabilized tetragonal zirconia polycrystals (Y-TZP), 12 mol% ceria-stabilized tetragonal zirconia polycrystals (Ce-TZP), and 8 mol% magnesia-partially stabilized zirconia (Mg-PSZ). Hysteresis loops, cyclic stress-strain curves, and lifetime data have been obtained. Additional experiments on fatigue crack growth under reverse loading were conducted using controlled surface flaws. The results form these studies have been used to obtain a comprehensive description of the fatigue deformation, damage and fracture behavior. Two distinct fatigue deformation mechanisms, microcracking was dominant in Y-TZP, while transformation plasticity was most evident in Ce-TZP and also in Mg-PSZ. The proportion of the plastic strain contribution due to these two mechanisms was dependent on the frequency, stress amplitude, and temperature, with transformation plasticity favored at lower frequency, higher stress, and lower temperature. Hysteresis in the stress-plastic strain curve reflects to the operation of forward, delayed phase transformation, reverse transformation, microcrack closure, and crack face sliding. Strain irreversibility was found to be closely related to the microstructure and more reversible in Ce-TZP and Y-TZP. Fatigue crack propagation in Y-TZP was found to follow a unique growth lay strongly dependent on the maximum stress intensity factor and quandratically dependent on the amplitude of the range of stress intensity factor. It applied for both surface flaws and internal flaws. The presence of residual stresses altered the growth mechanics so that an inverse growth rate dependence on the applied stress, reminiscent of the so-called short-crack behavior', was manifested. Fatigue striations resulting from alternate overload fracture and fatigue fracture during stress cycle was observed.

Liu, Shih-Yu.

1992-01-01

108

Accelerators for nuclear physics  

Microsoft Academic Search

This article describes the principal charged particle accelerators being used today for research in nuclear physics in the energy range up to about 1000 MeV. The accelerators include Van de Graaffs, sector cyclotrons and linear accelerators for both positive ions and electrons. For each type of accelerator a brief treatment is given of the recent history, operating principles, some special

D J Clark

1972-01-01

109

Future accelerator technology  

SciTech Connect

A general discussion is presented of the acceleration of particles. Upon this foundation is built a categorization scheme into which all accelerators can be placed. Special attention is devoted to accelerators which employ a wake-field mechanism and a restricting theorem is examined. It is shown how the theorem may be circumvented. Comments are made on various acceleration schemes.

Sessler, A.M.

1986-05-01

110

Accelerating machines: a review  

Microsoft Academic Search

This paper presents an overview of accelerating machines. We begin by exploring the history of the accelerating machine model and the potential power that it provides. We look at a number of computations that could be performed with an accelerating machine, and review various possible implementation methods that have been proposed. Finally, we expose the limitations of accelerating machines and

Robert Fraser; Selim G. Akl

2008-01-01

111

Cyclic nucleotides of cone-dominant retinas. Reduction of cyclic AMP levels by light and by cone degeneration.  

PubMed

Dark-adapted retinas or whole eyes of 13-line ground squirrels (Citellus tridecemlineatus) and western fence lizards (Sceloporus occidentalis) contain higher levels of cyclic AMP than of cyclic GMP. In these cone-dominant retinas, light reduces cyclic AMP content selectively. Freezing of dark- or light-adapted retinas or eyes also reduces cyclic AMP content, with only minimal changes in cyclic GMP levels. In addition, exposure of frozen retinas of dark-adapted ground squirrel to light results in a significant decrease in cyclic AMP content. The destruction of cone visual cells of ground squirrel retina by iodoacetic acid injection decreases the cyclic nucleotide content of the dark-adapted retina. Considering the relative loss of cyclic nucleotides from cone degeneration, we estimate that the content of cyclic AMP in visual cells of ground squirrel retina is about four times greater than that of cyclic GMP. PMID:6256308

Farber, D B; Souza, D W; Chase, D G; Lolley, R N

1981-01-01

112

Disiloxanes with cyclic or non-cyclic carbamate moieties as electrolytes for lithium-ion batteries.  

PubMed

Novel liquid disiloxanes, containing an n-propylic spacer group between the disiloxane fragment and a cyclic or non-cyclic carbamate moiety, were synthesized and characterized as liquid electrolytes. The ionic conductivity, thermal properties, viscosity and relative permittivity of these new solvents have been investigated, taking into account steric factors. PMID:23287984

Jeschke, Steffen; Gentschev, Ann-Christin; Wiemhöfer, Hans-Dieter

2013-01-04

113

Further studies on cyclic erythropoiesis in mice  

SciTech Connect

When young adult female W/Wv mice are given 0.5 micro+Ci /sup 89/Sr/g body weight intravenously, their hematocrit values oscillate from nadirs of 26% to zeniths of 42% with a periodicity of 16 days. The response of the W/Wv mouse to an assortment of radioactive and hematologic stresses have been examined in an effort to understand better the pathophysiology of cyclic erythropoiesis. When the dose of /sup 89/Sr is increased, the amplitude of cycling increases as nadirs are lowered, but periodicity is unchanged. When the dose of /sup 89/Sr is lowered to 0.3 microCi or less, cyclic erythropoiesis of substantial amplitude is observed only after five or six microoscillations. A single hematopoietic insult of 80 rad x-irradiation coupled with phlebotomy produces a transient form of cyclic erythropoiesis, namely, a series of dampened oscillations prior to recovery. Finally, we report that Wv/Wv mice exhibit a form of cyclic erythropoiesis in response to 0.5 microCi /sup 89/Sr/g body weight, in which the hematocrit values of successive nadirs gradually increase, and stabilize at about 100 days. /sup 89/Sr does not induce cyclic erythropoiesis in the +/+, W/+, or W/v/+ mice, the Hertwig strain of anemic mice, or in normal BDF1 mice.

Gibson, C.M.; Gurney, C.W.; Simmons, E.L.; Gaston, E.O.

1985-10-01

114

Biosynthesis of the endogenous cyclic adenosine monophosphate (AMP) antagonist, prostaglandylinositol cyclic phosphate (cyclic PIP), from prostaglandin E and activated inositol polyphosphate in rat liver plasma membranes  

Microsoft Academic Search

The endogenous cyclic adenosine monophosphate (AMP) antagonist, cyclic PIP, has been identified as a prostaglandylinositol cyclic phosphate. It inhibits protein kinase A 100% and activates protein serine phosphatase about sevenfold. It is biosynthesized by an enzyme of the plasma membrane when the assay mixture contains adenosine triphosphate (ATP), Mg2+, prostaglandin E and a novel inositol polyphosphate, which cannot be substituted

H. K. Wasner; M. Leßmann; M. Conrad; H. Amini; E. Psarakis; A. Mir-Mohammad-Sadegh

1996-01-01

115

Accelerated cleanup risk reduction  

SciTech Connect

There is no proven technology for remediating contaminant plume source regions in a heterogeneous subsurface. This project is an interdisciplinary effort to develop the requisite new technologies so that will be rapidly accepted by the remediation community. Our technology focus is hydrous pyrolysis/oxidation (HPO) which is a novel in situ thermal technique. We have expanded this core technology to leverage the action of steam injection and place an in situ microbial filter downstream to intercept and destroy the accelerated movement of contaminated groundwater. Most contaminant plume source regions, including the chlorinated solvent plume at LLNL, are in subsurface media characterized by a wide range in hydraulic conductivity. At LLNL, the main conduits for contaminant transport are buried stream channels composed of gravels and sands; these have a hydraulic conductivity in the range of 10{sup -1} to 10{sup -2} cm/s. Clay and silt units with a hydraulic conductivity of 10{sup -1} to 10{sup -6} cm/s bound these buried channels; these are barriers to groundwater movement and contain the highest contaminant concentrations in the source region. New remediation technologies are required because the current ones preferentially access the high conductivity units. HPO is an innovative process for the in situ destruction of contaminants in the entire subsurface. It operates by the injection of steam. We have demonstrated in laboratory experiments that many contaminants rapidly oxidize to harmless compounds at temperatures easily achieved by injecting steam, provided sufficient dissolved oxygen is present. One important challenge in a heterogeneous source region is getting heat, contaminants, and an oxidizing agent in the same place at the same time. We have used the NUFT computer program to simulate the cyclic injection of steam into a contaminated aquifer for design of a field demonstration. We used an 8 hour, steam/oxygen injection cycle followed by a 56 hour relaxation period in which the well was `capped`. Our results show the formation of an inclined gas phase during injection and a fast collapse of the steam zone within an hour of terminating steam injection. The majority of destruction occurs during the collapse phase, when contaminant laden water is drawn back towards the well. Little to no noncondensible gasses are created in this process, removing any possibility of sparging processes interfering with contaminant destruction. Our models suggest that the thermal region should be as hot and as large as possible. To have HPO accepted, we need to demonstrate the in situ destruction of contaminants. This requires the ability to inexpensively sample at depth and under high temperatures. We proved the ability to implies monitoring points at depths exceeding 150 feet in highly heterogeneous soils by use of cone penetrometry. In addition, an extractive system has been developed for sampling fluids and measuring their chemistry under the range of extreme conditions expected. We conducted a collaborative field test of HPO at a Superfund site in southern California where the contaminant is mainly creosote and pentachlorophenol. Field results confirm the destruction of contaminants by HPO, validate our field design from simulations, demonstrate that accurate field measurements of the critical fluid parameters can be obtained using existing monitoring wells (and minimal capital cost) and yield reliable cost estimates for future commercial application. We also tested the in situ microbial filter technology as a means to intercept and destroy the accelerated flow of contaminants caused by the injection of steam. A series of laboratory and field tests revealed that the selected bacterial species effectively degrades trichloroethene in LLNL Groundwater and under LLNL site conditions. In addition, it was demonstrated that the bacteria effectively attach to the LLNL subsurface media. An in-well treatability study indicated that the bacteria initially degrade greater than 99% of the contaminant, to concentrations less than regulatory limit

Knapp, R.B.; Aines, R.M.; Blake, R.G.; Copeland, A.B.; Newmark, R.L.; Tompson, A.F.B.

1998-02-01

116

Loop quantum gravity and the cyclic universe  

SciTech Connect

Loop quantum gravity introduces strong nonperturbative modifications to the dynamical equations in the semiclassical regime, which are responsible for various novel effects, including resolution of the classical singularity in a Friedman universe. Here we investigate the modifications for the case of a cyclic universe potential, assuming that we can apply the four-dimensional loop quantum formalism within the effective four-dimensional theory of the cyclic scenario. We find that loop quantum effects can dramatically alter the near-collision dynamics of the cyclic scenario. In the kinetic-dominated collapse era, the scalar field is effectively frozen by loop quantum friction, so that the branes approach collision and bounce back without actual collision.

Bojowald, Martin [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1, D-14476 Potsdam (Germany); Maartens, Roy [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 2EG (United Kingdom); Singh, Parampreet [IUCAA, Ganeshkhind, Pune 411 007 (India); Astronomy Unit, School of Mathematical Sciences, Queen Mary, University of London, London E1 4NS (United Kingdom)

2004-10-15

117

Cyclic Cocycles on Twisted Convolution Algebras  

NASA Astrophysics Data System (ADS)

We give a construction of cyclic cocycles on convolution algebras twisted by gerbes over discrete translation groupoids. For proper étale groupoids, Tu and Xu (Adv Math 207(2):455-483, 2006) provide a map between the periodic cyclic cohomology of a gerbe-twisted convolution algebra and twisted cohomology groups which is similar to the construction of Mathai and Stevenson (Adv Math 200(2):303-335, 2006). When the groupoid is not proper, we cannot construct an invariant connection on the gerbe; therefore to study this algebra, we instead develop simplicial techniques to construct a simplicial curvature 3-form representing the class of the gerbe. Then by using a JLO formula we define a morphism from a simplicial complex twisted by this simplicial curvature 3-form to the mixed bicomplex computing the periodic cyclic cohomology of the twisted convolution algebras.

Angel, Eitan

2013-01-01

118

Cyclic loading of notched dental composite specimens  

PubMed Central

Objective The purpose of this study was to examine the fracture toughness (KIC) of three direct dental composites and one indirect dental composite subject to cyclic loading. Methods The composites were a micro-filled (Micronew, Bisco INC., Schaumburg, IL, USA), a hybrid (Renew, Bisco INC.), a nano-filled composite (Filtek Supreme Plus, 3M ESPE, St. Paul, MN, USA) and an indirect dental composite (BelleGlass HP, SDS-Kerr, Orange, CA, USA). Rectangular bar specimens (3mm x 3mm x 25 mm) were fabricated, notched, aged (five months) and cyclic loaded in four different environments, air, water, artificial saliva, and a 50/50 by volume mixture of ethanol and water. Specimens were cyclic loaded for 1, 1,000, 10,000, and 100,000 cycles. Results A three-way ANOVA (non-aged and aged group, four aging media, four loading cycles) showed a significant difference between non-aged and aged, aging media, and loading cycles. For the control groups as the number of cycles increased, there were no significant differences on the number of cycles completed and fracture toughness, except for Micronew, which showed an increased specimen failure rate and decreased fracture toughness. In the aged groups, cyclic loading in water and artificial saliva did not have a significant effect on BelleGlass HP, Filtek Supreme Plus and Renew for fracture toughness and the number of cycles completed, However for Renew in the 50/50 mixture at 100,000 cycles, Filtek Supreme Plus in air and the 50/50 mixture, and Micronew, there was an increased specimen failure rate and a decreased fracture toughness during cyclic fatigue loading as the number of cycles increased. Significance BelleGlass HP displayed the best overall resistance to cyclic loading, followed by Renew and Filtek Supreme Plus, and Micronew.

Lin, Lihong; Drummond, James L.

2009-01-01

119

Incremental Update of Cyclic Association Rules  

NASA Astrophysics Data System (ADS)

A promising challenge of data mining, especially for association rules technique, is the incremental mining of association whatever is the trend of the association rules. Recently, some researches were devoted to incremental update of temporal association rules problem. In this paper, we focus on cyclic association rules, a class of temporal association rules. Thus, we introduce a new approach called IUPCAR dedicated to maintaining incrementally the cyclic association rules already extracted. Based on the carried out experimental study, we point out the efficiency of our proposal.

Ben Ahmed, Eya

120

Development of a service-simulating, accelerated aging test method for exterior tire rubber compounds II. Design and development of an accelerated outdoor aging simulator  

Microsoft Academic Search

During storage and service, exterior tire rubber compounds are subject to aging due to multiple factors. This process cannot be accurately represented by conventional single factor tests. The overall goal of our research is to develop an accelerated, service-simulating, artificial aging test for exterior rubber compounds. During the first part of this work, a cyclic test consisting of a series

Bart J. LaCount; Jose M. Castro; Frederick Ignatz-Hoover

2002-01-01

121

Development of a design methodology for high temperature cyclic applications of materials which experience cyclic softening  

SciTech Connect

The project has as its original focus the high temperature behavior of 2.25 Cr-1 Mo steel, heat treated to produce a predominantly bainitic microstructure and the load carrying response of components made of this material. Experiments were carried out on uniform and notched specimens under both steady and cyclic loading using specially acquired electromechanical test machines. It emerged that a very important feature of mechanical behavior under the conditions of interest was the strong tendency of this material to cyclically soften, particularly at high temperature in the creep range, giving the illusion of a severe creep-fatigue interaction under certain conditions. This finding led to a significant component of the project being devoted to investigation of the effects of local, as opposed to generalized, cyclic softening, and the implications this phenomenon might have on the setting of allowable design stress limits. The format of this report is as follows: The second chapter is a review of the work carried out in approximately chronological order under the headings of work was carried out under the following: (1) 2.25 Cr 1 Mo Steel -- Elevated Temperature Fatigue and Environmental Effects; (2) Preliminary Studies of Advanced Austenitics; (3) A Uniaxial Constitutive Model for Cyclic Softening; (4) The Iso-Cyclic Stress-Strain Approach to Evaluation of Components in Cyclic Softening Materials; (5) Testing of High Temperature Austenitic Alloys; and (6) Design Methodology for Aging Materials -- Application to Cyclic Softening. 65 refs., 39 figs., 7 tabs.

Marriott, D.L.; Stubbins, J.F. (Illinois Univ., Urbana, IL (USA). Dept. of Mechanical and Industrial Engineering)

1988-12-01

122

Collective Acceleration of Ions.  

National Technical Information Service (NTIS)

The collective method for acceleration of ions is described. The problem of the formation of an electron ring cluster charged with ions, its stability and focusing, and some questions of acceleration are discussed. (Author)

A. B. Kuznetsov E. A. Parelshtein I. N. Ivanov K. A. R. Reshetnikov V. A. Preizendorf

1973-01-01

123

Acceleration of Gravity 1  

NSDL National Science Digital Library

This lab is a Level 2 inquiry activity that should be taught after students understand acceleration but before they learn the equations for calculating the acceleration of a body dropped from a certain height. After this activity, students should understa

Horton, Michael

2009-05-30

124

Accelerator Technology Division  

NASA Astrophysics Data System (ADS)

In fiscal year (FY) 1991, the Accelerator Technology (AT) division continued fulfilling its mission to pursue accelerator science and technology and to develop new accelerator concepts for application to research, defense, energy, industry, and other areas of national interest. This report discusses the following programs: The Ground Test Accelerator Program; APLE Free-Electron Laser Program; Accelerator Transmutation of Waste; JAERI, OMEGA Project, and Intense Neutron Source for Materials Testing; Advanced Free-Electron Laser Initiative; Superconducting Super Collider; The High-Power Microwave Program; (Phi) Factory Collaboration; Neutral Particle Beam Power System Highlights; Accelerator Physics and Special Projects; Magnetic Optics and Beam Diagnostics; Accelerator Design and Engineering; Radio-Frequency Technology; Free-Electron Laser Technology; Accelerator Controls and Automation; Very High-Power Microwave Sources and Effects; and GTA Installation, Commissioning, and Operations.

1992-04-01

125

Gait analysis using gravitational acceleration measured by wearable sensors.  

PubMed

A novel method for measuring human gait posture using wearable sensor units is proposed. The sensor units consist of a tri-axial acceleration sensor and three gyro sensors aligned on three axes. The acceleration and angular velocity during walking were measured with seven sensor units worn on the abdomen and the lower limb segments (both thighs, shanks and feet). The three-dimensional positions of each joint are calculated from each segment length and joint angle. Joint angle can be estimated mechanically from the gravitational acceleration along the anterior axis of the segment. However, the acceleration data during walking includes three major components; translational acceleration, gravitational acceleration and external noise. Therefore, an optimization analysis was represented to separate only the gravitational acceleration from the acceleration data. Because the cyclic patterns of acceleration data can be found during constant walking, a FFT analysis was applied to obtain some characteristic frequencies in it. A pattern of gravitational acceleration was assumed using some parts of these characteristic frequencies. Every joint position was calculated from the pattern under the condition of physiological motion range of each joint. An optimized pattern of the gravitational acceleration was selected as a solution of an inverse problem. Gaits of three healthy volunteers were measured by walking for 20s on a flat floor. As a result, the acceleration data of every segment was measured simultaneously. The characteristic three-dimensional walking could be shown by the expression using a stick figure model. In addition, the trajectories of the knee joint in the horizontal plane could be checked by visual imaging on a PC. Therefore, this method provides important quantitive information for gait diagnosis. PMID:19121522

Takeda, Ryo; Tadano, Shigeru; Todoh, Masahiro; Morikawa, Manabu; Nakayasu, Minoru; Yoshinari, Satoshi

2009-01-01

126

A Solid state accelerator  

SciTech Connect

We present a solid state accelerator concept utilizing particle acceleration along crystal channels by longitudinal electron plasma waves in a metal. Acceleration gradients of order 100 GV/cm are theoretically possible, but channeling radiation limits the maximum attainable energy to 10/sup 5/ TeV for protons. Beam dechanneling due to multiple scattering is substantially reduced by the high acceleration gradient. Plasma wave dissipation and generation in metals are also discussed.

Chen, P.; Noble, R.J.

1986-11-06

127

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

128

Hig accelerator system  

Microsoft Academic Search

The design criteria and operational capabilities of the Hi-g accelerator system, a pneumatically operated device are described. The system was designed to accelerate an experiment package up the experimental tube of the Sandia Annular Core Pulse Reactor. A variety of experimental sizes can be accommodated by the system and a wide range of acceleration levels is possible.

J. P. Atencio

1976-01-01

129

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

130

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.

131

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

132

Force, mass and acceleration  

Microsoft Academic Search

Force, mass and acceleration are everyday words but often used inaccurately. Force is a physical influence, which when applied to an object causes it to accelerate in the direction from which it was applied. Mass is the amount of matter in an object and is expressed in kilograms. Acceleration is the rate of change of velocity of an object in

Phil Dalrymple; Richard Griffiths

2005-01-01

133

Mechanical Rotary Acceleration Sensor.  

National Technical Information Service (NTIS)

The mechanical rotary acceleration device senses both acceleration and deceleration of a rotating member and responds to control switches or the like to correct the acceleration. The device is used in the field of airlaunched, towed targetry in which a co...

E. J. McQuillen

1965-01-01

134

Covariant Uniform Acceleration  

NASA Astrophysics Data System (ADS)

We derive a 4D covariant Relativistic Dynamics Equation. This equation canonically extends the 3D relativistic dynamics equation , where F is the 3D force and p = m0?v is the 3D relativistic momentum. The standard 4D equation is only partially covariant. To achieve full Lorentz covariance, we replace the four-force F by a rank 2 antisymmetric tensor acting on the four-velocity. By taking this tensor to be constant, we obtain a covariant definition of uniformly accelerated motion. This solves a problem of Einstein and Planck. We compute explicit solutions for uniformly accelerated motion. The solutions are divided into four Lorentz-invariant types: null, linear, rotational, and general. For null acceleration, the worldline is cubic in the time. Linear acceleration covariantly extends 1D hyperbolic motion, while rotational acceleration covariantly extends pure rotational motion. We use Generalized Fermi-Walker transport to construct a uniformly accelerated family of inertial frames which are instantaneously comoving to a uniformly accelerated observer. We explain the connection between our approach and that of Mashhoon. We show that our solutions of uniformly accelerated motion have constant acceleration in the comoving frame. Assuming the Weak Hypothesis of Locality, we obtain local spacetime transformations from a uniformly accelerated frame K' to an inertial frame K. The spacetime transformations between two uniformly accelerated frames with the same acceleration are Lorentz. We compute the metric at an arbitrary point of a uniformly accelerated frame. We obtain velocity and acceleration transformations from a uniformly accelerated system K' to an inertial frame K. We introduce the 4D velocity, an adaptation of Horwitz and Piron s notion of "off-shell." We derive the general formula for the time dilation between accelerated clocks. We obtain a formula for the angular velocity of a uniformly accelerated object. Every rest point of K' is uniformly accelerated, and its acceleration is a function of the observer's acceleration and its position. We obtain an interpretation of the Lorentz-Abraham-Dirac equation as an acceleration transformation from K' to K.

Friedman, Yaakov; Scarr, Tzvi

2013-04-01

135

A cyclic GMP-dependent signalling pathway regulates bacterial phytopathogenesis  

PubMed Central

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.

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

2013-01-01

136

Queue simulation of cyclic construction operations  

Microsoft Academic Search

Cyclic construction operations may be modelled in terms of the waiting times of the entities (typically equipment, plant, materials or manpower) that repeatedly pass through the various phases of the cycle. The relevant model involves recursive expressions linking the waiting times of successive cycles. This permits a Monte Carlo type simulation to be carried out and represents an alternative method

D. G. Carmichael

1988-01-01

137

Juvenile cyclic amegakaryocytic thrombocytopenia: a novel entity.  

PubMed

Cyclic thrombocytopenia is a rare disorder described in adults, characterized by periodic platelet count fluctuations of unknown etiology. The authors describe a boy with cyclic changes in platelet counts ranging from 2 x 10(9)/L to 224 x 10(9)/L with a periodicity of 25 days. Since birth, the patient had periods of bruising. Platelet counts were periodically low during these periods. Thrombopoietin plasma levels oscillated inversely with the platelet count, whereas glycocalicin levels oscillated in phase with the platelets. No oscillation was seen in neutrophil and reticulocyte numbers. The bone marrow showed periodic reduction in megakaryocyte counts. In an in vitro megakaryocytopoiesis assay, the patient's CD34+ cells showed megakaryocyte formation, although to a lower level than controls. Addition of patient plasma, collected during the rise in platelet numbers, to cultures with normal bone marrow-derived CD34+ cells caused an increase in the development of CD41+ megakaryoblasts. Because the periods with bruising had existed since birth, apparently this is a form of congenital cyclic thrombocytopenia. The underlying mechanism of the cyclic thrombocytopenia in this patient is not yet clear, and until now, no therapy has been found for this patient. However, platelet transfusions have resulted in cessation of bleeding during thrombocytopenic periods. PMID:15750447

Bruin, Marrie; Tijssen, Marloes R; Bierings, Marc; de Haas, Masja

2005-03-01

138

A deterministic interfacial cyclic oxidation spalling model  

Microsoft Academic Search

A series summation has been developed to model the iterative scale growth and spalling process of cyclic oxidation. Parabolic scale growth has been assumed. Interfacial spallation of a constant area fraction was stipulated to occur only at the thickest portions. Inputs are the parabolic growth rate constant, spall area fraction, oxide stoichiometry, and cycle duration. Outputs include the net weight

James L. Smialek

2003-01-01

139

Inhibition of cyclic photophosphorylation by peroxyacetyl nitrate  

Microsoft Academic Search

The present paper describes the inhibitory effect of PAN on cyclic photophosphorylation by chloroplasts isolated from Black Valentine bean leaves. If the photophosphorylation reaction mixture is gassed with PAN during the assay, inhibition of photophosphorylation results. Moreover, inhibition of photophosphorylation is also observed if the complete reaction mixture containing the chloroplasts is gassed in complete darkness with PAN immediately before

J. Koukol; W. M. Jr. Dugger; N. O. Belser

1963-01-01

140

Symmetrization of cyclic sigma-telluranes  

SciTech Connect

The authors examine reactions involving cyclic sigma-telluranes. Refluxing 5,5-dichlorodibenzotellurophene with tellurium tetrachloride in o-dichlorobenzene results in symmetrization and the formation of 2,2'-bis(trichlorotelluro)diphenyl in high yield. The other compounds formed and described are polymeric ditelluride, dibenzotellurophene, and dimethyltellurium dibromide.

Sadekov, I.D.; Rivkin, B.B.; Maslakov, A.G.; Minkin, V.I.

1987-09-01

141

PERIOD LENGTH IN CYCLIC ANIMAL POPULATIONS  

Microsoft Academic Search

Although cyclic animal dynamics have long been a focus of scientific interest, the variable cycle lengths are poorly understood. Based on a review of the literature, we suggest that period length in animals showing multiannual cycles is related to the life span of their food plant rather than to any trait of the animal, such as mass or fecundity. We

Göran Högstedt; Tarald Seldal; Arild Breistøl

2005-01-01

142

Stochastic Equivariant Cohomologies and Cyclic Cohomology  

Microsoft Academic Search

We give two stochastic diffeologies on the free loop space which allow us to define stochastic equivariant cohomology theories in the Chen-Souriau sense and to establish a link with cyclic cohomology. With the second one, we can establish a stochastic fixed point theorem.

Remi Leandre

2005-01-01

143

Sequential steam; An engineered cyclic steaming method  

SciTech Connect

Cyclic steam injection has been the most widely used EOR method in areas of the Potter sand in the Midway-Sunset field, Kern County, CA. This paper discusses the field pilot and the statistical and theoretical studies leading to the design of a sequential steaming process,plus the implementation of this process on three leases.

Jones, J. (Santa Fe Energy Resources Inc., Bakersfield, CA (US)); Cawthon, J. (Groundwater Resources Inc. (US))

1990-07-01

144

Sequential Steam: An Engineered Cyclic Steaming Method  

Microsoft Academic Search

Cyclic steam injection has been the most widely used EOR method in areas of the Potter sand in the Midway-Sunset field, Kern County, CA. This paper discusses the field pilot and the statistical and theoretical studies leading to the design of a sequential steaming process,plus the implementation of this process on three leases.

Jeff Jones; Gary Cawthon

1990-01-01

145

Boston University Physics Applets: Cyclic Processes  

NSDL National Science Digital Library

This web page is an interactive physics simulation on cyclic processes. The user can put an engine through four steps, returning it to its original conditions. The work done by the engine is graphed after each step, showing the net work done. This is part of a collection of similar simulation-based student activities.

Duffy, Andrew

2008-08-01

146

The Cyclic Executive Model and Ada  

Microsoft Academic Search

Periodic processes are major parts of many real-time embedded computer applications. The programming language Ada permits programming simple periodic processes, but it has some serious limitations; produc- ing Ada programs with real-time performance com- parable to those produced to date usin traditional cyclic executives requires resorting to tee %* mques that are specific to one machine or compiler. We present

Theodore P. Baker; Alan C. Shaw

1988-01-01

147

Cyclic Cratonic Carbonates and Phanerozoic Calcite Seas.  

ERIC Educational Resources Information Center

|Discusses causes of cyclicity in cratonic carbonate sequences and evidence for and potential significance of postulated primary calcite sediment components in past Paleozoic seas, outlining problems, focusing on models explaining existing data, and identifying background. Future sedimentary geologists will need to address these and related areas…

Wilkinson, Bruce H.

1982-01-01

148

Phase Regulation of Decentralized Cyclic Robotic Systems  

Microsoft Academic Search

We address the problem of coupling cyclic robotic tasks to produce a specified coordinated behavior. Such coordination tasks are common in robotics, appearing in applications like walking, hopping, run- ning, juggling and factory automation. In this paper we introduce a general methodology for designing controllers for such settings. We introduce a class of dynamical systems defined over n-dimensional tori (the

Eric Klavins; Daniel E. Koditschek

2002-01-01

149

Rhodium-Catalyzed Dehydrogenative Borylation of Cyclic Alkenes  

PubMed Central

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. Suzuki-Miyaura cross-coupling applications are also presented.

Kondoh, Azusa; Jamison, Timothy F.

2010-01-01

150

Influence of Cyclic Tangential Loading on Indentation Fracture.  

National Technical Information Service (NTIS)

An indentation method is used to analyze the contact damage induced by cyclic tangential loading in the partial slip condition. Failure strengths are measured thereafter to indicate the degree of damage. The phenomenon of crack propagation during cyclic l...

M. C. Lu

1984-01-01

151

Effects of Laboratory Heating, Cyclic Pore Pressure, and Cyclic Loading on Fracture Properties of Asphalt Mixture.  

National Technical Information Service (NTIS)

In this project, researchers evaluated several laboratory conditioning procedures on granite, limestone, and/or hydrated lime mixtures. They investigated three procedures, alone and in combinations - heat oxidation conditioning (HOC), cyclic pore pressure...

C. Kho G. Lopp J. Zou M. Isola R. Roque S. Chun

2012-01-01

152

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

153

Precipitation in solution-treated aluminum-4wt%copper under cyclic strain  

NASA Astrophysics Data System (ADS)

With the aim of assessing the effects of cyclic plasticity on the precipitation behavior of Al-4wt%Cu, solutionized specimens were cycled at epsilon p=+/-0.001, 0.0025 and 0.005 at 25°C, 100°C, 175°C and 200°C. The temperatures and strain amplitudes sampled showed a broad range of behaviors, encompassing both the effects of the cyclic strain on the precipitation behavior, and of the precipitation behavior on the cyclic stress-strain response of the material. The excess vacancies produced by cyclic strain accelerated the diffusion kinetics of precipitate growth, while the presence of a high dislocation density provided ample sites for heterogeneous nucleation of precipitates. The combination of heterogeneous nucleation with accelerated growth led to the formation of theta' precipitates under conditions which would ordinarily be associated with the growth of theta" precipitates. It appears that the dominant factor in the promotion of theta' over theta" is heterogeneous nucleation on dislocations, although precipitate scissioning may play a role by suppressing formation of theta". Increasing strain amplitudes also led to an acceleration of precipitation kinetics, with decreasing effect at higher strain amplitudes where vacancy supersaturations are consumed by recovery. Above 100°C, recovery initially reduces the strain hardening of the sample material, but the onset of precipitation hardens the material, leading to different mechanical behaviors than observed at 100°C and room temperature. The effects of texture at 25°C and 100°C appear qualitatively similar to what would be expected on the basis of monotonic tests, but become more complicated at higher temperatures as hardening effects of precipitate formation interact with texture effects. Greater precipitation rates offset the effects of dynamic recovery at 175°C and 200°C, leading to continuous hardening throughout life. The expected mode of transgranular fatigue fracture was observed at 25°C and 100°C, but at 175°C and 200°C an unexpected mode of intergranular failure occurred at all strain amplitudes sampled. Although intergranular cracking is common in quench-aged Al-4wt%Cu, it is not commonly associated with very fine precipitation. The presence of ductile dimples on the fracture surface suggests that the formation of grain boundary precipitates may also be enhanced proportionally to the increase in diffusion under cyclic strain.

Farrow, Adam M.

154

Inflammation-related changes in cyclic AMP and cyclic GMP in bovine mastitis  

Microsoft Academic Search

Cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) cocentrations in milk and plasma samples from healthy and mastitic cows were determined by radioi-immunoassay and compared with prostaglandins (PGE2, PGF2a and thromboxane B2 [TXB2]), phospholipids and other relevant parameters in milk and blood. The concentrations of cAMP were about five times higher in plasma (pp<0.01) than that in plasma in

F. Atroshi; J. Parantainen; S. Sankari; T. Österman

1989-01-01

155

Design of cyclic fixed-bed adsorption processes. Part II: regeneration and cyclic operation  

SciTech Connect

Regeneration of polymeric adsorbents saturated with phenol in a fixed bed is modeled by an ''equilibrium model'' and a ''reaction front model.'' These models were previously tested over CSTR experiments. A package for the design of cyclic fixed-bed adsorbers was then prepared by linking the reaction front model for regeneration with a pore-diffusion model for saturation described in Part I (Costa and Rodrigues, 1985) and a model for washing. Predicted and experimental results were compared in a cyclic run.

Costa, C.; Rodrigues, A.

1985-10-01

156

Capturing cyclic nucleotides in action: snapshots from crystallographic studies  

Microsoft Academic Search

Fifty years ago, cyclic AMP was discovered as a second messenger of hormone action, heralding the age of signal transduction. Many cellular processes were found to be regulated by cAMP and the related cyclic GMP. Cyclic nucleotides function by binding to and activating their effectors — protein kinase A, protein kinase G, cyclic-nucleotide-regulated ion channels and the guanine nucleotide-exchange factor

Alfred Wittinghofer; Johannes L. Bos; Holger Rehmann

2007-01-01

157

Anelastic relaxation controlled cyclic creep and cyclic stress rupture behavior of an oxide dispersion strengthened alloy  

NASA Astrophysics Data System (ADS)

Cyclic creep deceleration relative to static creep was observed in oxide dispersion strengthened alloy Inconel MA 754 at 760 °C and cyclic stresses of 221 MPa-41 MPa, 231 MPa-41 MPa, and 241 MPa-41 MPa. Tests were run over the range of frequency from 0.05 cycles per hour to six cycles per hour. The maximum cyclic deceleration, which was manifested as a reduced net creep rate and increased rupture life, was observed at the highest cyclic frequency. Considerable anelastic strain, having a magnitude of ?a/?e˜ 1/3, is stored in MA 754 at 760 °C under these creep loads, and this strain may be recovered in the off-load half cycle of a cyclic creep test. During the higher frequency tests, the effect of an incomplete storage of anelastic strain on the accompanying nonrecoverable creep rate provides a mechanism for the frequency dependent cyclic creep deceleration. The proposed mechanism is in agreement with mixed-mode test results and with TEM examination of interrupted-test specimens.

Matejczyk, D. E.; Zhuang, Y.; Tien, J. K.

1983-02-01

158

Role of Ecdysone, Pupariation Factors, and Cyclic AMP in Formation and Tanning of the Puparium of the Fleshfly Sarcophaga bullata  

Microsoft Academic Search

Two pupariation factors, anterior retraction factor (ARF) and puparium tanning factor (PTF), are absent from the hemolymph of larvae at the time of tanning accelerated by ARF\\/PTF, cyclic AMP, or dopamine. ARF and PTF are not involved in derepression of dopa decarboxylase (aromatic L-amino-acid decarboxylase, aromatic L-amino-acid carboxy-lyase, EC 4.1.1.28) synthesis initiated by ecdysone. Tanning is entirely inhibited by injection

Morris Seligman; Ann Blechl; James Blechl; Paul Herman; G. Fraenkel

1977-01-01

159

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

160

21 CFR 862.1230 - Cyclic AMP test system.  

Code of Federal Regulations, 2010 CFR

...2012-04-01 2012-04-01 false Cyclic AMP test system. 862.1230 Section 862.1230...Chemistry Test Systems § 862.1230 Cyclic AMP test system. (a) Identification. A cyclic AMP test system is a device intended to measure...

2012-04-01

161

21 CFR 862.1230 - Cyclic AMP test system.  

Code of Federal Regulations, 2013 CFR

...false Cyclic AMP test system. 862.1230 Section...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED...Clinical Chemistry Test Systems § 862.1230 Cyclic... A cyclic AMP test system is a device intended...plasma, urine, and other body fluids....

2013-04-01

162

Stiffness degradation of natural fine grained soils during cyclic loading  

Microsoft Academic Search

Cyclic behavior of natural fine grained soils under a broad range of strains were investigated considering the effects of plasticity index and changes in confining pressures based on cyclic triaxial tests. A total of 98 stress controlled cyclic triaxial tests were conducted on normally consolidated and slightly overconsolidated samples. The investigation was divided into two parts. The first part consists

D. V. Okur; A. Ansal

2007-01-01

163

Some fixed point results for multi-valued cyclic mappings  

NASA Astrophysics Data System (ADS)

This paper investigates the fixed points and best proximity points of multivalued cyclic self-mappings in metric spaces under a generalized contractive condition involving Hausdorff distances. Some previous results for cyclic self-mappings or for multivalued self-mappings in metric fixed point theory are extended to cyclic multivalued self-mappings.

De la Sen, M.; Singh, S. L.; Gordji, M. E.

2013-09-01

164

Algebraic connections, universal bimodules and entire cyclic cohomology  

NASA Astrophysics Data System (ADS)

A new method of constructing homotopies suitable for entire cyclic cohomology is presented. As a result, the periodic and entire cyclic cohomology of Banach algebras of finite cohomological dimension are shown to be isomorphic. The same method can be used to calculate the algebraic entire cyclic cohomology of (non-commutative) tori.

Khalkhali, Masoud

1994-04-01

165

Regulation of Cyclic GMP, Cyclic amp and Lactate Dehydrogenase by Putative Neutrotransmitters in the C6 Rat Glioma Cell Line.  

National Technical Information Service (NTIS)

In C6 cells norepinephrine and dopamine caused transient increases in cyclic GMP and cyclic AMP, as well as an induction of lactate dehydrogenase. All of these responses were blocked by 1-propranolol, suggesting mediation by a beta -receptor. Phentolamine...

J. E. Bottenstein J. de Vellis

1977-01-01

166

Particle-accelerator decommissioning  

SciTech Connect

Generic considerations involved in decommissioning particle accelerators are examined. There are presently several hundred accelerators operating in the United States that can produce material containing nonnegligible residual radioactivity. Residual radioactivity after final shutdown is generally short-lived induced activity and is localized in hot spots around the beam line. The decommissioning options addressed are mothballing, entombment, dismantlement with interim storage, and dismantlement with disposal. The recycle of components or entire accelerators following dismantlement is a definite possibility and has occurred in the past. Accelerator components can be recycled either immediately at accelerator shutdown or following a period of storage, depending on the nature of induced activation. Considerations of cost, radioactive waste, and radiological health are presented for four prototypic accelerators. Prototypes considered range from small accelerators having minimal amounts of radioactive mmaterial to a very large accelerator having massive components containing nonnegligible amounts of induced activation. Archival information on past decommissionings is presented, and recommendations concerning regulations and accelerator design that will aid in the decommissioning of an accelerator are given.

Opelka, J.H.; Mundis, R.L.; Marmer, G.J.; Peterson, J.M.; Siskind, B.; Kikta, M.J.

1979-12-01

167

Plasma inverse transition acceleration  

SciTech Connect

It can be proved fundamentally from the reciprocity theorem with which the electromagnetism is endowed that corresponding to each spontaneous process of radiation by a charged particle there is an inverse process which defines a unique acceleration mechanism, from Cherenkov radiation to inverse Cherenkov acceleration (ICA) [1], from Smith-Purcell radiation to inverse Smith-Purcell acceleration (ISPA) [2], and from undulator radiation to inverse undulator acceleration (IUA) [3]. There is no exception. Yet, for nearly 30 years after each of the aforementioned inverse processes has been clarified for laser acceleration, inverse transition acceleration (ITA), despite speculation [4], has remained the least understood, and above all, no practical implementation of ITA has been found, until now. Unlike all its counterparts in which phase synchronism is established one way or the other such that a particle can continuously gain energy from an acceleration wave, the ITA to be discussed here, termed plasma inverse transition acceleration (PITA), operates under fundamentally different principle. As a result, the discovery of PITA has been delayed for decades, waiting for a conceptual breakthrough in accelerator physics: the principle of alternating gradient acceleration [5, 6, 7, 8, 9, 10]. In fact, PITA was invented [7, 8] as one of several realizations of the new principle.

Xie, Ming

2001-06-18

168

Cyclic GMP/cyclic GMP-dependent protein kinase system prevents excitotoxicity in an immortalized oligodendroglial cell line.  

PubMed

Previously, we have demonstrated that excitotoxicity of oligodendrocyte-like cells (OLC), differentiated from immortalized rat O-2A progenitor cells (CG-4 cells), is prevented by cyclic AMP-elevating agents. We now report that some agents that elevate cyclic GMP prevent OLC excitotoxicity. Kainate-induced injury was prevented by cyclic GMP analogues (8-bromo-cyclic GMP and dibutyryl cyclic GMP), a guanylate cyclase activator [atrial natriuretic peptide (ANP)], and phosphodiesterase inhibitors [3-isobutyl-1-methylxanthine (IBMX), ibudilast, propentofylline, and rolipram]. When both forskolin and 8-bromo-cyclic GMP were added, kainate-induced injury was additively prevented. There was a strong positive correlation between suppression of kainate-induced Ca2+ influx and prevention of injury by these chemicals. The measurement of intracellular cyclic AMP and cyclic GMP by radioimmunoassay demonstrated the following: an increase of cyclic GMP with treatment with 8-bromo-cyclic GMP, dibutyryl cyclic GMP, and ANP; an increase of cyclic AMP with treatment with ibudilast and rolipram; and an increase of both cyclic AMP and cyclic GMP with treatment with IBMX and propentofylline. Kainate-induced Ca2+ influx was decreased by 8-(4-chlorophenylthiol)-guanosine-3',5'-monophosphate, an activator of cyclic GMP-dependent protein kinase (PKG), or okadaic acid, an inhibitor of protein phosphatases 1 and 2A. RT-PCR and westem blotting of OLC demonstrated transcription of PKG II gene and translation of PKG Ibeta mRNA, but no translation of PKG Ialpha mRNA. Therefore, we concluded that the cyclic GMP/PKG system prevents OLC excitotoxicity. PMID:10646514

Yoshioka, A; Yamaya, Y; Saiki, S; Kanemoto, M; Hirose, G; Pleasure, D

2000-02-01

169

Accelerated Development of Corrosion Inhibitor Formulations by Electrochemical Methods and Short-Time Corrosion Tests  

Microsoft Academic Search

A combined general approach to the development of corrosion inhibitors for industrial applications based on electrochemical measurements along with both standard and accelerated corrosion tests has been developed. Electrochemical measurements (corrosion potential, cyclic voltammetry and polarization resistance) are used to assess both relevant physical properties and the relative corrosion protection efficiencies of new inhibitor formulations. Additionally, electrochemical techniques provide quick

Hochschule Zittau

170

Deactivation of accelerated engine-aged and field-aged Fe–zeolite SCR catalysts  

Microsoft Academic Search

A single-cylinder diesel engine with an emissions control system – diesel oxidation catalyst (DOC), Fe–zeolite 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 850°C 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

171

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

172

Synergistic effect of particles and cyclic pressure on cytokine production in human monocyte/macrophages: proposed role in periprosthetic osteolysis.  

PubMed

Macrophages, activated by particulate wear debris, are important in the process of osteolysis, which occurs during joint implant loosening. We previously found increased levels of interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor-alpha in cultured macrophages subjected to cyclical pressure of 0.138 MPa, suggesting that cyclic pressure may be another relevant cause of macrophage activation. The current study first investigated the effects of a range of cyclic pressures on cultured macrophages, including an investigation of the time course of cytokine expression. At 0.138 MPa, supernatant levels of TNF-alpha were maximal at 12 h, whereas IL-6 and IL-1beta were maximal at 24 h. All four cyclic pressure levels tested (without particles) resulted in increased production of all three cytokines relative to control. These increases were most marked at 0.069 and 0.035 MPa, and the increase in cytokine production at 0.017 MPa was not statistically significant. Further studies demonstrated that conditioned media from cyclically pressurized macrophages stimulated bone resorption in a neonatal mouse calvarial assay system. There were increased levels of calcium released from calvaria cultured in conditioned media from pressurised monocytes, and an increase in tartate-resistant acid phosphatase-positive osteoclasts was observed microscopically. As particulate wear debris is important in implant loosening, ultra high molecular weight polyethylene particles were also added to the pressurized cell cultures. The experiments compared the effect of atmospheric pressure, cyclic pressure alone, particles alone, and particles and cyclic pressure combined. A combination of ultra high molecular weight polyethylene particles and cyclic pressure at 0.017 MPa resulted in a dramatic synergistic elevation of levels of all three cytokines compared with the levels found with either pressure or particles alone. We propose that monocyte/macrophage activation by cyclic pressure plays a major role in the osteolysis seen in aseptic loosening of implants. The synergistic effect observed between particles and pressure could accelerate implant loosening, and implies that reduction in either cyclic pressure (by improving implant fixation) or wear debris load would reduce osteolysis. PMID:11792581

McEvoy, A; Jeyam, M; Ferrier, G; Evans, C E; Andrew, J G

2002-01-01

173

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

174

Linear induction accelerator  

SciTech Connect

A linear induction accelerator of charged particles, containing inductors and an acceleration circuit, characterized by the fact that, for the purpose of increasing the power of the accelerator, each inductor is made in the form of a toroidal line with distributed parameters, from one end of which in the gap of the line a ring commutator is included, and from the other end of the ine a resistor is hooked up, is described.

Bosamykin, V.S.; Pavlovskiy, A.I.

1984-03-01

175

Linear inductive accelerator  

SciTech Connect

A proposed accelerator, differing from existing ones in that it is loaded through a capacitor on a solenoid which is uniformly distributed throughout the accelerating system and connected to an independent electrical current source, is discussed. The design of the system makes it possible to improve the uniformity of the electrical field and increase the longitudinal focusing magnetic field. This is especially important for high-current accelerators.

Bosamykin, V.S.; Gerasimov, A.I.; Pavlovskiy, A.I.

1983-11-01

176

ACCELERATION RESPONSIVE SWITCH  

DOEpatents

An acceleration-responsive device with dual channel capabilities whereby a first circuit is actuated upon attainment of a predetermined maximum acceleration level and when the acceleration drops to a predetermined minimum acceleriltion level another circuit is actuated is described. A fluid-damped sensing mass slidably mounted in a relatively frictionless manner on a shaft through the intermediation of a ball bushing and biased by an adjustable compression spring provides inertially operated means for actuating the circuits. (AEC)

Chabrek, A.F.; Maxwell, R.L.

1963-07-01

177

Separation of isotopes by cyclical processes  

DOEpatents

Various isotopes of hydrogen are separated by a cyclic sorption process in which a gas stream containing the isotopes is periodically passed through a high pressure column containing a palladium sorbent. A portion of the product from the high pressure column is passed through a second column at lower pressure to act as a purge. Before the sorbent in the high pressure column becomes saturated, the sequence is reversed with the stream flowing through the former low-pressure column now at high pressure, and a portion of the product purging the former high pressure column now at low pressure. The sequence is continued in cyclic manner with the product being enriched in a particular isotope.

Hamrin, Jr., Charles E. (Lexington, KY); Weaver, Kenny (Lexington, KY)

1976-11-02

178

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

179

Cyclic transition to turbulence in rigid abdominal aortic aneurysm models  

NASA Astrophysics Data System (ADS)

The hydrodynamic stability of cyclic flows inside rigid abdominal aortic aneurysm (AAA) models was investigated. Rectified sine waveforms were used to simulate aortic flow conditions (Re mean=1600-2100 and ?=7.2-12.2). Depending on the bulge geometry ( D/ d and L/ d ratios), AAA flows can be broadly classified into three regimes, namely types A, B and C, respectively. While type A has no vortex formation, type B and C have distinctive laminar vortical structures that are very different from one another. The type of flow regimes would also determine where and when the transition to turbulence would occur and the portion of the cycle at which the flow remains turbulent in the bulge. The stability characteristics of types B and C are obtained from the linear stability analysis performed on the unsteady velocity profiles measured at different phases of a cycle. Based on the linear stability analyses, instability is found to initiate in the bulge for types B and C through the formation of vortical structures. Instability grows progressively during the acceleration phase and transition to turbulence in the bulge occurs shortly after the commencement of the deceleration phase in all cases investigated. The mechanisms of transition to turbulence for types B and C are discussed. Although transition to turbulence appears in all the cases investigated here, fully laminar flows in types B and C are predicted to exist by the linear stability theory under extreme flow conditions. Finally, the in vivo biological implications of the in vitro results were discussed.

Yip, T. H.; Yu, S. C. M.

2001-08-01

180

Before the Beginning...The Return of the Cyclic Universe  

NSDL National Science Digital Library

This is a summary written by Catherine Baker on a lecture by Dr Paul Steinhardt.In the last fifty years a great deal of evidence has accumulated in support of a "consensus" theory of the evolution of the universe. This theory holds that a "big bang" precipitated a huge split-second inflation of the universe, followed by a gradual expansion that continues to this day and is now accelerating."But just maybe that turns out to be wrong," says Paul Steinhardt, Ph.D. Dr. Steinhardt is Albert Einstein Professor of Science and Professor of Physics at Princeton University. Dr.Steinhardt and his colleague Neil Turok of Cambridge University have put forward a competing idea: that the universe exists in an infinite cycle of expansion and contraction.Dr. Steinhardt compared the consensus model with the new cyclic theory at a January 16 lecture sponsored by the Dialogue on Science, Ethics, and Religion (DoSER), a programof the American Association for the Advancement of Science (AAAS).Dr. Steinhardt explained that cosmology has been a subject of human inquiry as far back as recorded history, but it really only began as a science about 80 years ago. That waswhen telescopes became large and precise enough to get a detailed look at the universe beyond this solar system.

Catherine Baker (;)

2007-06-28

181

FFAGS FOR MUON ACCELERATION.  

SciTech Connect

Due to their finite lifetime, muons must be accelerated very rapidly. It is challenging to make the magnets ramp fast enough to accelerate in a synchrotron, and accelerating in a linac is very expensive. One can use a recirculating accelerator (like CEBAF), but one needs a different arc for each turn, and this limits the number of turns one can use to accelerate, and therefore requires significant amounts of RF to achieve the desired energy gain. An alternative method for muon acceleration is using a fixed field alternating gradient (FFAG) accelerator. Such an accelerator has a very large energy acceptance (a factor of two or three), allowing one to use the same arc with a magnetic field that is constant over time. Thus, one can in principle make as many turns as one can tolerate due to muon decay, therefore reducing the RF cost without increasing the arc cost. This paper reviews the current status of research into the design of FFAGs for muon acceleration. Several current designs are described and compared. General design considerations are also discussed.

BERG,J.S.KAHN,S.PALMER,R.TRBOJEVIC,D.JOHNSTONE,C.KEIL,Y.OGITSU,T.OHMORI,C.SESSLER,A.KOSCIELNIAK,S.

2003-06-26

182

High-intensity accelerators  

SciTech Connect

The design of high-intensity accelerators is described, using examples of machines being built at the Los Alamos National Laboratory. The major design problem with these accelerators is associated with control of beam loss when accelerator intensity is increased. Beam dynamics, beam loss, and the radio-frequency quadrupole structure are discussed in the first part of the chapter followed by an explanation of plans to achieve high-intensity operation in three projects: the Fusion Material Irradiation Tests (a joint effort with the Hanford Development Laboratory in Richland, Washington), the Proton Storage Ring (an addition to the LAMPF accelerator), and the Racetrack Microtron Project (with the National Bureau of Standards).

Knapp, E.A.

1981-01-01

183

Finite type invariants of cyclic branched covers  

Microsoft Academic Search

Updated rerefences and introduction. Given a knot in an integer homology sphere, one can construct a family of closed 3-manifolds (parametrized by the positive integers), namely the cyclic branched coverings of the knot. In this paper we give a formula for the the Casson-Walker invariants of these 3-manifolds in terms of residues of a rational function (which measures the 2-loop

Stavros Garoufalidis; Andrew Kricker

2001-01-01

184

On L ?-Morphisms of Cyclic Chains  

NASA Astrophysics Data System (ADS)

Recently the first two authors (Cattaneo and Felder in 2008) constructed an L ?-morphism using the S 1-equivariant version of the Poisson Sigma Model. Its role in the deformation quantization was not entirely clear. We give here a “good” interpretation and show that the resulting formality statement is equivalent to formality on cyclic chains as conjectured by Tsygan and proved recently by several authors (Dolgushev et al. in 2008; Willwacher in 2008).

Sergio Cattaneo, Alberto; Felder, Giovanni; Willwacher, Thomas

2009-12-01

185

Fisheries Management Under Cyclical Population Dynamics  

Microsoft Academic Search

Cycles in environmental conditions (e.g., sea-surface temperature) directly impact fish growth. This paper extends the classical\\u000a Gordon-Schaefer fishery model by replacing the constant growth rate with a cyclical growth rate. The optimal harvest rate\\u000a is shown to fluctuate, but the cycle of the harvest rate lags the cycle of the biological growth function with the highest\\u000a harvest rate occurring after

Richard T. Carson; Clive W. J. Granger; Jeremy B. C. Jackson; Wolfram Schlenker

2009-01-01

186

Estrus cyclicity of spinogenesis: underlying mechanisms  

Microsoft Academic Search

Hippocampal spine density varies with the estrus cycle. The cyclic change in estradiol levels in serum was hypothesized to\\u000a underlie this phenomenon, since treatment of ovariectomized animals with estradiol induced an increase in spine density in\\u000a hippocampal dendrites of rats, as compared to ovariectomized controls. In contrast, application of estradiol to hippocampal\\u000a slice cultures did not promote spinogenesis. In addressing

Janine Prange-Kiel; Lars Fester; Lepu Zhou; Hubertus Jarry; Gabriele M. Rune

2009-01-01

187

Cyclic thermal stresses in fusion reactors  

SciTech Connect

In this paper we model and analyze cyclic thermal loads and stresses in two critical components of inertial and magnetic confinement fusion reactors (including fusion-fission hybrids); namely, in the solid wall adjacent to the fusion plasma (first wall) and in the fuel elements located in the high power density region of the blanket. We derive explicit expressions for the parametric dependencies of thermal stresses that provide a quantitative basis for tradeoff and comparative assessment studies of different fusion reactors.

Bohachevsky, I.O.; Kostoff, R.N.

1981-01-01

188

Representing cyclic human motion using functional analysis  

Microsoft Academic Search

We present a robust automatic method for modeling cyclic 3D human motion such as walking using motion-capture data. The pose of the body is represented by a time-series of joint angles which are automatically segmented into a sequence of motion cycles. The mean and the principal components of these cycles are computed using a new algorithm that enforces smooth transitions

Dirk Ormoneit; Michael J. Black; Trevor Hastie; Hedvig Kjellström

2005-01-01

189

Cyclical variations of advertising and personal selling  

Microsoft Academic Search

This paper examines the cyclical behavior of advertising and personal selling, the two major promotional tools, during the\\u000a period 1958–1976. The study concludes that while advertising expenditures have fluctuated with business cycles (up following\\u000a increases in corporate income, sometimes up and sometimes down following decreases in corporate income), personal selling\\u000a effort has shown a steady increase over time, regardless of

Joseph A. Bellizzi; A. Frank Thompson; Lynn J. Loudenback

1983-01-01

190

Cosmic perturbations through the cyclic ages  

SciTech Connect

We analyze the evolution of cosmological perturbations in the cyclic model, paying particular attention to their behavior and interplay over multiple cycles. Our key results are: (1) galaxies and large scale structure present in one cycle are generated by the quantum fluctuations in the preceding cycle without interference from perturbations or structure generated in earlier cycles and without interfering with structure generated in later cycles; (2) the ekpyrotic phase, an epoch of gentle contraction with equation of state w>>1 preceding the hot big bang, makes the universe homogeneous, isotropic and flat within any given observer's horizon; and (3) although the universe is uniform within each observer's horizon, the structure of the cyclic universe on very large scales is more complex, owing to the effects of superhorizon length perturbations, and cannot be described globally as a Friedmann-Robertson-Walker cosmology. In particular, we show that the ekpyrotic contraction phase is so effective in smoothing, flattening and isotropizing the universe within the horizon that this phase alone suffices to solve the horizon and flatness problems even without an extended period of dark energy domination (a kind of low energy inflation). Instead, the cyclic model rests on a genuinely novel, noninflationary mechanism (ekpyrotic contraction) for resolving the classic cosmological conundrums.

Erickson, Joel K. [ISCAP, Columbia Astrophysics Laboratory, New York, New York 10027 (United States); Gratton, Steven [Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA (United Kingdom); Steinhardt, Paul J. [Joseph Henry Laboratories, Princeton University, Princeton, New Jersey 08544 (United States); Turok, Neil [DAMTP, CMS, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)

2007-06-15

191

Acceleration of polarized protons in circular accelerators  

SciTech Connect

The theory of depolarization in circular accelerators is presented. The spin equation is first expressed in terms of the particle orbit and then converted to the equivalent spinor equation. The spinor equation is then solved for three different situations: (1) a beam on a flat top near a resonance, (2) uniform acceleration through an isolated resonance, and (3) a model of a fast resonance jump. Finally, the depolarization coefficient, epsilon, is calculated in terms of properties of the particle orbit and the results are applied to a calculation of depolarization in the AGS.

Courant, E.D.; Ruth, R.D.

1980-09-12

192

The conformations of cyclic polymers in bidisperse blends of cyclic polymers  

NASA Astrophysics Data System (ADS)

The size of cyclic polymers in bidisperse blends of chemically identical molecules is analyzed by computer simulations. The compression of entangled rings can be explained by the changes in the penetrable fraction of the surface bounded by the ring. Corrections for small rings can be approximated by a concatenation probability 1-POO that a cyclic polymer entraps at least one other cyclic polymer. Both results are in line with a previous work [1] on the compression of entangled cyclic polymers in monodisperse melts. For entangled cyclic polymers, bond-bond correlations show a constant anti-correlation peak at a curvilinear distance of about ten segments that coincides with a horizontal tangent in the normalized mean square internal distances along the ring for sufficiently large degrees of polymerization. In consequence, the length scale of topological interactions must be considered as constant in contrast to a recent proposal by Sakaue [2]. Our data is not in accord with an extension of the model of Cates and Deutsch [3] to bidiperse blends of ring polymers.[4pt] [1] M. Lang, J. Fischer, J.-U. Sommer, Macromolecules 45 (2012) 7642-7648.[0pt] [2] T. Sakaue, Phys. Rev. Lett. 2011, 106, 167802.[0pt] [3] M. E. Cates, J. M. Deutsch, J. Phys. (Paris) 1986, 47, 2121- 2128.

Lang, Michael

2013-03-01

193

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

194

Accelerating the Development of Hardware Accelerators  

Microsoft Academic Search

ASC (1), A Stream Compiler, is designed to enable rapid development of hardware accelerators while still producing results that match hand-crafted equivalents. An ASC pro- gram represents a dataflow system which can be seen as a stream; to avoid the difficulties often associated with be- havioural synthesis, ASC allows direct implementation of a hardware design based on the programmer's input.

Lee W. Howes; Oliver Pell; Oskar Mencer; Olav Beckmann

195

Accelerator Toolbox for MATLAB.  

National Technical Information Service (NTIS)

This paper introduces Accelerator Toolbox (AT) - a collection of tools to model particle accelerators and beam transport lines in the MATLAB environment. At SSRL, it has become the modeling code of choice for the ongoing design and future operation of the...

A. Terebilo

2001-01-01

196

Accelerators for energy production  

NASA Astrophysics Data System (ADS)

A tremendous progress of accelerators for these several decades, has been motivated mainly by the research on subnuclear physics. The culmination in high energy accelerators might be SSC, 20 TeV collider in USA, probably the ultimate accelerator being built with the conventional principle. The technology cultivated and integrated for the accelerator development, can now stably offer the high power beam which could be used for the energy problems. The Inertial Confinement Fusion (ICF) with high current, 10 kA and short pulse, 20 ns heavy ion beam (HIB) of mass number approximately 200, would be the most promising application of accelerators for energy production. In this scenario, the fuel containing D-T mixture, will be compressed to the high temperature, approximately 10 keV and to the high density state, approximately 1000 times the solid density with the pressure of ablative plasma or thermal X ray produced by bombarding of high power HIB. The efficiency, beam power/electric power for accelerator, and the repetition rate of HIB accelerators could be most suitable for the energy production. In the present paper, the outline of HIB ICF (HIF) is presented emphasizing the key issues of high current heavy ion accelerator system.

Katayama, Takeshi

1993-11-01

197

KEK digital accelerator  

NASA Astrophysics Data System (ADS)

The High Energy Accelerator Research Organization KEK digital accelerator (KEK-DA) is a renovation of the KEK 500 MeV booster proton synchrotron, which was shut down in 2006. The existing 40 MeV drift tube linac and rf cavities have been replaced by an electron cyclotron resonance (ECR) ion source embedded in a 200 kV high-voltage terminal and induction acceleration cells, respectively. A DA is, in principle, capable of accelerating any species of ion in all possible charge states. The KEK-DA is characterized by specific accelerator components such as a permanent magnet X-band ECR ion source, a low-energy transport line, an electrostatic injection kicker, an extraction septum magnet operated in air, combined-function main magnets, and an induction acceleration system. The induction acceleration method, integrating modern pulse power technology and state-of-art digital control, is crucial for the rapid-cycle KEK-DA. The key issues of beam dynamics associated with low-energy injection of heavy ions are beam loss caused by electron capture and stripping as results of the interaction with residual gas molecules and the closed orbit distortion resulting from relatively high remanent fields in the bending magnets. Attractive applications of this accelerator in materials and biological sciences are discussed.

Iwashita, T.; Adachi, T.; Takayama, K.; Leo, K. W.; Arai, T.; Arakida, Y.; Hashimoto, M.; Kadokura, E.; Kawai, M.; Kawakubo, T.; Kubo, Tomio; Koyama, K.; Nakanishi, H.; Okazaki, K.; Okamura, K.; Someya, H.; Takagi, A.; Tokuchi, A.; Wake, M.

2011-07-01

198

Review of Accelerator Alignment  

Microsoft Academic Search

SUMMARY The history of twentieth century science and technology is intimately tied to the development of particle accelerators and the discoveries made using them. Today the breadth of science concerned by, and studied using particle accelerators is truly staggering. It ranges from attempts to understand the origin of our universe and what constitutes matter and radiation; to questions concerning the

David MARTIN

2010-01-01

199

Neutrino physics at accelerators  

Microsoft Academic Search

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. Neutrinos are particles that interact only weakly and this gives them a somewhat special

Enrique Fernandez

200

Twisted waveguide accelerating structure..  

National Technical Information Service (NTIS)

A hollow waveguide with a uniform cross section may be used for accelerating charged particles if the phase velocity of an accelerating mode is equal to or less than the fiee space speed of light. Regular straight hollow waveguides have phase velocities o...

Y. W. Kang

2000-01-01

201

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.

202

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.

203

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.

204

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

205

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

206

Acceleration of Gravity 2  

NSDL National Science Digital Library

This lab is between a Level 2 and Level 3 inquiry activity in that it should be assigned after students understand acceleration but before they learn about the acceleration gravity. Because there are many sources of error when using a pendulum, students c

Horton, Michael

2009-05-30

207

Exploring acceleration through vectors  

NSDL National Science Digital Library

This in class worksheet is designed to get students to think about and manipulate different accelerations in their head. Students work together with written descriptions of velocity and acceleration and draw the vectors in part one, and then turn that around in part two where they write descriptions of a car's motion based on the vector pictures they are given.

208

Diagnostics for induction accelerators  

SciTech Connect

The induction accelerator was conceived by N. C. Christofilos and first realized as the Astron accelerator that operated at LLNL from the early 1960`s to the end of 1975. This accelerator generated electron beams at energies near 6 MeV with typical currents of 600 Amperes in 400 ns pulses. The Advanced Test Accelerator (ATA) built at Livermore`s Site 300 produced 10,000 Ampere beams with pulse widths of 70 ns at energies approaching 50 MeV. Several other electron and ion induction accelerators have been fabricated at LLNL and LBNL. This paper reviews the principal diagnostics developed through efforts by scientists at both laboratories for measuring the current, position, energy, and emittance of beams generated by these high current, short pulse accelerators. Many of these diagnostics are closely related to those developed for other accelerators. However, the very fast and intense current pulses often require special diagnostic techniques and considerations. The physics and design of the more unique diagnostics developed for electron induction accelerators are presented and discussed in detail.

Fessenden, T.J.

1996-04-01

209

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

210

Effects of cyclic AMP- and cyclic GMP- phosphodiesterase inhibitors on immunological release of histamine and on lung contraction.  

PubMed

1 Cyclic adenosine 3',5'-monophosphate (cyclic AMP)- and cyclic guanosine 3',5'-monophosphate (cyclic GMP)-phosphodiesterase activities from rat lung were selectively inhibited by ZK 62711 and M & B 22948, respectively. Theophylline and papaverine inhibited both activities. 2 Rat lung strips contracted by carbachol were relaxed by 4-(3-cyclopentyloxy-4-methoxyphenyl)-2-pyrrolidone (ZK 26711, EC25 = 7 x 10(-8)M) and 2-O-propoxyphenyl-8-azapurin-6-one (M & B 22948, EC25 = 5 x 10(-7)M) indicating relaxant properties of both cyclic AMP and cyclic GMP. 3 The antigen-induced histamine release from human basophils was inhibited by ZK 62711 (IC25 = 8 x 10(-7)M), whereas M & B 22948 had no effect. On the contrary, the release from rat mast cells was inhibited by M & B 22948 (IC25 = 10(-6)M), while ZK 62711 had no effect. 4 These data show an inhibitory effect of cyclic AMP on histamine release to be involved with basophils, whereas cyclic GMP is predominantly involved with mast cells. Is is suggested that the antianaphylactic properties of cyclic nucleotide phosphodiesterase inhibitors are mainly linked to the increase of cyclic GMP. PMID:6168323

Frossard, N; Landry, Y; Pauli, G; Ruckstuhl, M

1981-08-01

211

Effects of cyclic AMP- and cyclic GMP- phosphodiesterase inhibitors on immunological release of histamine and on lung contraction.  

PubMed Central

1 Cyclic adenosine 3',5'-monophosphate (cyclic AMP)- and cyclic guanosine 3',5'-monophosphate (cyclic GMP)-phosphodiesterase activities from rat lung were selectively inhibited by ZK 62711 and M & B 22948, respectively. Theophylline and papaverine inhibited both activities. 2 Rat lung strips contracted by carbachol were relaxed by 4-(3-cyclopentyloxy-4-methoxyphenyl)-2-pyrrolidone (ZK 26711, EC25 = 7 x 10(-8)M) and 2-O-propoxyphenyl-8-azapurin-6-one (M & B 22948, EC25 = 5 x 10(-7)M) indicating relaxant properties of both cyclic AMP and cyclic GMP. 3 The antigen-induced histamine release from human basophils was inhibited by ZK 62711 (IC25 = 8 x 10(-7)M), whereas M & B 22948 had no effect. On the contrary, the release from rat mast cells was inhibited by M & B 22948 (IC25 = 10(-6)M), while ZK 62711 had no effect. 4 These data show an inhibitory effect of cyclic AMP on histamine release to be involved with basophils, whereas cyclic GMP is predominantly involved with mast cells. Is is suggested that the antianaphylactic properties of cyclic nucleotide phosphodiesterase inhibitors are mainly linked to the increase of cyclic GMP.

Frossard, N.; Landry, Y.; Pauli, G.; Ruckstuhl, M.

1981-01-01

212

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

213

Cyclic Nucleotide Signaling in Polycystic Kidney Disease  

PubMed Central

Increased levels of 3’–5’-cyclic adenosine monophosphate (cAMP) stimulate cell proliferation and fluid secretion in polycystic kidney disease (PKD). Since hydrolytic capacity of phosphodiesterases (PDE) far exceeds maximum rate of synthesis by adenylyl cyclases (AC), cellular levels of cAMP are more sensitive to PDE inhibition than to AC activity changes. We have used enzymatic, western blot, immunohistochemistry, PCR and biochemical assays to study activity and expression of PDE families and isoforms and expression of downstream effectors of cAMP signaling in wildtype and PKD rat and mouse kidneys. The results indicate: 1) Species specific differences in PDE expression; higher PDE activity in kidneys from mice compared to rats; higher contribution of PDE1, relative to PDE4 and PDE3, to total PDE activity of kidney lysate and lower PDE1, PDE3 and PDE4 activities in murine cystic compared to wildtype kidneys. 2) Reduced levels of several PDE1, PDE3 and PDE4 proteins despite mRNA upregulation, possibly due to increased protein degradation. 3) Increased cGMP levels in polycystic kidneys, suggesting in vivo downregulation of PDE1 activity. 4) Additive stimulatory effect of cAMP and cGMP on cystogenesis in vitro. 5) Upregulation of cAMP-dependent protein kinase (PKA) subunits I? and II?, PKare, CREB-1 mRNA, and CREM, ATF-1 and ICER proteins in cystic compared to wildtype kidneys. In summary, the results of this study suggest that alterations in cyclic nucleotide catabolism may render the cystic epithelium particularly susceptible to factors acting on Gs coupled receptors, account at least in part for the upregulation of cyclic nucleotide signaling in PKD, and contribute substantially to the progression of this disease.

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

2013-01-01

214

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.

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

2007-01-01

215

Model for Cyclically Astable Third Sound Resonance  

SciTech Connect

Third sound in a circular resonator is capable of rich behavior due to the coincidence of several characteristics: a high quality factor; the capability for wave-induced circulation changes; vortex pinning on the substrate; and the Doppler shifting of modes. One dimensional models for each of these components have previously been used to reproduce highly nonlinear third sound CW lineshapes using a steady-state approximation. We now include oscillator transients to account for cyclical amplitude modulations of third sound recently observed under conditions of a drive force where both the amplitude and frequency are fixed.

Ellis, F. M.; Carbone, Ian; Dang, Hoan [Department of Physics, Wesleyan Unversity, Middletown, CT 06459 (United States)

2006-09-07

216

Cyclic nucleotide permeability through unopposed connexin hemichannels.  

PubMed

Cyclic adenosine monophosphate (cAMP) is a well-known intracellular and intercellular second messenger. The membrane permeability of such molecules has potential importance for autocrine-like or paracrine-like delivery. Here experiments have been designed to demonstrate whether gap junction hemichannels, composed of connexins, are a possible entrance pathway for cyclic nucleotides into the interior of cells. HeLa cells stably expressing connexin43 (Cx43) and connexin26 (Cx26) were used to study the cyclic nucleotide permeability of gap junction hemichannels. For the detection of cAMP uptake, the cells were transfected using the cyclic nucleotide-modulated channel from sea urchin sperm (SpIH) as the cAMP sensor. SpIH derived currents (I m) were recorded in whole-cell/perforated patch clamp configuration. Perfusion of the cells in an external K(+) aspartate(-) (KAsp) solution containing 500 ?M cAMP and no extracellular Ca(2) (+), yielded a five to sevenfold increase in the I m current level. The SpIH current increase was associated with detectable hemichannel current activity. Depolarization of cells in Ca(2) (+)-free NaCl perfusate with 500 ?M cAMP also induced a SpIH current increase. Elevating extracellular Ca(2) (+) to mM levels inhibited hemichannel activity. Perfusion with a depolarizing KAsp solution containing 500 ?M cAMP and 2 mM Ca(2) (+) did not increase SpIH currents. The addition of the gap junction blocker carbenoxolone to the external solution inhibited cAMP uptake. Both cell depolarization and lowered extracellular Ca(2) (+) increase the open probability of non-junctional hemichannels. Accordingly, the SpIH current augmentation was induced by the uptake of extracellular cAMP via open membrane hemichannels in Cx43 and Cx26 expressing cells. The data presented here show that hemichannels of Cx43 and Cx26 are permeable to cAMP, and further the data suggest that hemichannels are, in fact, a potential pathway for cAMP mediated cell-to-cell signaling. PMID:23760880

Valiunas, Virginijus

2013-06-06

217

[Conformational analysis of cyclic dipeptides: I].  

PubMed

Conformational analysis of two pairs of synthetic cyclodipeptides formed by interaction of both side chain functional groups [Formula: see text] and of the main and side chains [Formula: see text] was achieved by the method of molecular mechanics. The energetically optimal conformational states of the molecules under study were determined. It was shown that the conformational motility of cyclic system of the compounds under study depends on the relative arrangement of the amide groups and the number of atoms in the cycle. PMID:19060935

Arkhipova, S F; Artem'ev, I V; Goriacheva, E A; Pletnev, V Z

218

Notch root crack closure under cyclic inelasticity  

NASA Astrophysics Data System (ADS)

Aluminum alloy sheet coupons with a central hole were tested in fatigue under specially designed programmed load sequences. Electron microscopy of the fatigue fracture surfaces showed striation mode fatigue crack extension up to more than a millimeter before onset of rapid failure. Crack opening stress was determined from striation patterns. Under variable amplitude loading and conditions of notch root cyclic inelasticity, crack opening stress exhibits noticeable hysteresis. The hysteresis is attributed to a difference between crack closure and opening stresses. A linear model of this phenomenon appears to describe observed behavior.

Sunder, R.

1993-07-01

219

A Cyclic Germadicarbene ("Germylone") from Germyliumylidene.  

PubMed

By employing the chelate dicarbene 1, the new chlorogermyliumylidene complex 2 could be synthesized and isolated in 95% yield. Dechlorination of 2 with sodium naphthalenide furnishes the unique cyclic germadicarbene 3 which could be isolated in 45% yield. Compound 3 is the first isolable Ge(0) complex with a single germanium atom stabilized by a dicarbene. Its molecular structure is in accordance with DFT calculations which underline the peculiar electronic structure of 3 with two lone pairs of electrons at the Ge atom. PMID:23517068

Xiong, Yun; Yao, Shenglai; Tan, Gengwen; Inoue, Shigeyoshi; Driess, Matthias

2013-03-25

220

Dogbone geometry for recirculating accelerators.  

National Technical Information Service (NTIS)

Most scenarios for accelerating muons require recirculating acceleration. A racetrack shape for the accelerator requires particles with lower energy in early passes to traverse almost the same length of arc as particles with the highest energy. This extra...

S. Berg Johnstone Summers

2001-01-01

221

Twisted waveguide accelerating structure.  

SciTech Connect

A hollow waveguide with a uniform cross section may be used for accelerating charged particles if the phase velocity of an accelerating mode is equal to or less than the free space speed of light. Regular straight hollow waveguides have phase velocities of propagating electromagnetic waves greater than the free-space speed of light. if the waveguide is twisted, the phase velocities of the waveguide modes become slower. The twisted waveguide structure has been modeled and computer simulated in 3-D electromagnetic solvers to show the slow-wave properties for the accelerating mode.

Kang, Y. W.

2000-08-15

222

Advanced Accelerator Concepts  

NASA Astrophysics Data System (ADS)

Current particle accelerators rely on conventional or superconducting radio frequency cavities to accelerate beams of protons or electrons for nuclear and particle research and for medical and materials science studies. New methods for achieving larger accelerating gradients have been proposed and are being studied. These include the use of high power lasers, laser driven plasmas, wake fields generated by intense low energy beams, and millimeter wavelength EM structures. The studies to date, and the prospects for practical applications of these new ideas will be discussed.

Siemann, Robert

1998-04-01

223

Cyclic oxidation behavior of palladium-modified aluminide coating  

Microsoft Academic Search

(Ni,Pd)Al coating prepared by low-pressure pack cementation on the nickel-base superalloy IN738 predeposited Pd-20 wt.% Ni alloy, and their cyclic oxidation behavior was investigated by TGA, XRD, SEM\\/EDS and optical microscopy at 1050 °C. The (Ni,Pd)Al coatings show better cyclic oxidation resistance than simple aluminide coatings compared from the cyclic oxidation kinetics and the microstructure degradation of the two types

M. J Li; X. F Sun; H. R Guan; X. X Jiang; Z. Q Hu

2003-01-01

224

Interpretation of tandem mass spectra obtained from cyclic nonribosomal peptides.  

PubMed

Natural and non-natural cyclic peptides are a crucial component in drug discovery programs because of their considerable pharmaceutical properties. Cyclosporin, microcystins, and nodularins are all notable pharmacologically important cyclic peptides. Because these biologically active peptides are often biosynthesized nonribosomally, they often contain nonstandard amino acids, thus increasing the complexity of the resulting tandem mass spectrometry data. In addition, because of the cyclic nature, the fragmentation patterns of many of these peptides showed much higher complexity when compared to related counterparts. Therefore, at the present time it is still difficult to annotate cyclic peptides MS/MS spectra. In this current work, an annotation program was developed for the annotation and characterization of tandem mass spectra obtained from cyclic peptides. This program, which we call MS-CPA is available as a web tool (http://lol.ucsd.edu/ms-cpa_v1/Input.py). Using this program, we have successfully annotated the sequence of representative cyclic peptides, such as seglitide, tyrothricin, desmethoxymajusculamide C, dudawalamide A, and cyclomarins, in a rapid manner and also were able to provide the first-pass structure evidence of a newly discovered natural product based on predicted sequence. This compound is not available in sufficient quantities for structural elucidation by other means such as NMR. In addition to the development of this cyclic annotation program, it was observed that some cyclic peptides fragmented in unexpected ways resulting in the scrambling of sequences. In summary, MS-CPA not only provides a platform for rapid confirmation and annotation of tandem mass spectrometry data obtained with cyclic peptides but also enables quantitative analysis of the ion intensities. This program facilitates cyclic peptide analysis, sequencing, and also acts as a useful tool to investigate the uncommon fragmentation phenomena of cyclic peptides and aids the characterization of newly discovered cyclic peptides encountered in drug discovery programs. PMID:19413302

Liu, Wei-Ting; Ng, Julio; Meluzzi, Dario; Bandeira, Nuno; Gutierrez, Marcelino; Simmons, Thomas L; Schultz, Andrew W; Linington, Roger G; Moore, Bradley S; Gerwick, William H; Pevzner, Pavel A; Dorrestein, Pieter C

2009-06-01

225

Multiple Cyclic Nucleotide Phosphodiesterases in Human Trabecular Meshwork Cells  

Microsoft Academic Search

METHODS. Radioimmunoassay of acetylated acid extracts was used to determine changes in cyclic adenosine monophosphate (cAMP) and cyclic quanosine monophosphate (cGMP) in human tra- becular meshwork cells treated with phosphodiesterase isoform selective inhibitors. Cyclic nucle- otide phosphodiesterase activities were measured using the two-step radioisotope procedure (Thompson). Enzyme activities in the supernatant of human cells were fractionated using anion- exchange chromatography.

Ling Zhou; William J. Thompson; David E. Potter

1999-01-01

226

Synthesis of cyclic oligodeoxyribonucleotides via the 'filtration' approach.  

PubMed Central

The synthesis of cyclic di-, tri-, tetra-, penta- and hexa-thymidylic acids (16; n = 2, 3, 4, 5 and 6) and the cyclic hexadeoxyribonucleotide [d(CpCpTpApGpGp)], via the "filtration" approach, is reported. Some of the physical properties of the cyclic oligonucleotides are discussed, and their susceptibility to digestion in the presence of phosphorylytic enzymes has been studied. Images

Rao, M V; Reese, C B

1989-01-01

227

Potential synthetic lubricants: Esters of C 18 -saturated cyclic acids  

Microsoft Academic Search

A series of 16 esters of C18-saturated cyclic acids (HCal) were prepared, and partial evaluation showed that several have qualities that recommend them\\u000a as potential low-temp lubricants. Starting materials used were primary, straight, and branched chain alcohols C4–C7; perfluoro alcohols; phenol; cyclohexanol; and C18-saturated cyclic alcohols prepared from cyclic acids. Viscosities were measured at ?40, 100, and 210F. Their viscosity

J. P. Friedrich; E. W. Bell; L. E. Gast

1965-01-01

228

Cyclic hardening in copper described in terms of combined monotonic and cyclic stress-strain curves  

Microsoft Academic Search

Hardening of polycrystalline copper subjected to tension-compression loading cycles in the plastic region is discussed with reference to changes in flow stress determined from equations describing dislocation glide. It is suggested that hardening is as a result of the accumulation of strain on a monotonic stress-strain curve. On initial loading, the behaviour is monotonic. On stress reversal, a characteristic cyclic

H. D. Chandler

1995-01-01

229

Accelerating the Whirlpool Hash Function Using Parallel Table Lookup and Fast Cyclical Permutation  

Microsoft Academic Search

Hash functions are an important building block in almost all security applications. In the past few years, there have been\\u000a major advances in the cryptanalysis of hash functions, especially the MDx family, and it has become important to select new\\u000a hash functions for next-generation security applications. One of the potential candidates is Whirlpool, an AES-based hash\\u000a function. Whirlpool adopts a

Yedidya Hilewitz; Yiqun Lisa Yin; Ruby B. Lee

2008-01-01

230

Statistical Investigation into the Accelerating Cyclical Dynamics Among Gold, Dollar and U.S. Interest Rate  

Microsoft Academic Search

\\u000a Based on time-series decomposition, HP filter and cycle locating procedure, the paper extracts the concrete cycle information\\u000a from gold, USexchange rate, and US interest rate time series, on all four durations of the past 30 years. (In this paper the US exchange rate, and US interest rate time series, on all four durations of the past 30 years. (In this

Nan Yang; Jieyi He

231

Cyclic Process as a Tool for Considering Evolution  

NASA Astrophysics Data System (ADS)

Evolution is the process. The primary question is which tools we use to consider the process. In this work, basing on the original results of investigation of the intrinsic bistability in quantum systems, the concept of the cyclic process is developed for qualitative and quantitative consideration of processes as following: Everything that happens is the process of changing; the process is the cyclic process of ``... -> seed -> plant -> seed ->...'' type; the cyclic process is formed by two complement phase transitions of ``seed -> plant'' and ``plant -> seed'' type; the cyclic process is the manifestation of self-consistent interaction of interdependent two-state system, environment, and radiation, so that the whole Universe is involved in each process; the cyclic process can be described qualitatively and quantitatively by a real cubic equation with four generalized dimensionless real parameters, provided that one of the parameters undertakes cyclic change of its value and all four parameters belong to limited interdependent intervals to maintain cyclic process. Using the cyclic process approach as a powerful tool a variety of issues is considered. Preference of evolution, extinction, adaptation, and relation between microscopic structure and macroscopic behavior of the system are addressed. Seeing the evolution is the most transcending seeing of existence. The cyclic process approach is suggested to be a corner stone for scientific approach to seeing evolution.

Bondarenko, Victor

2009-03-01

232

Dependence of the excitability of pituitary cells on cyclic nucleotides.  

PubMed

Cyclic 3',5'-adenosine monophosphate and cyclic 3',5'-guanosine monophosphate are intracellular (second) messengers that are produced from the nucleotide triphosphates by a family of enzymes consisting of adenylyl and guanylyl cyclases. These enzymes are involved in a broad array of signal transduction pathways mediated by the cyclic nucleotide monophosphates and their kinases, which control multiple aspects of cell function through the phosphorylation of protein substrates. We review the findings and working hypotheses on the role of the cyclic nucleotides and their kinases in the control of electrical activity of the endocrine pituitary cells and the plasma membrane channels involved in this process. PMID:22564128

Stojilkovic, S S; Kretschmannova, K; Tomi?, M; Stratakis, C A

2012-09-01

233

Role of ecdysone, pupariation factors, and cyclic AMP in formation and tanning of the puparium of the fleshfly Sarcophaga bullata.  

PubMed

Two pupariation factors, anterior retraction factor (ARF) and puparium tanning factor (PTF), are absent from the hemolymph of larvae at the time of tanning accelerated by ARF/PTF, cyclic AMP, or dopamine. ARF and PTF are not involved in derepression of dopa decarboxylase (aromatic L-amino-acid decarboxylase, aromatic L-amino-acid carboxy-lyase, EC 4.1.1.28) synthesis initiated by ecdysone. Tanning is entirely inhibited by injection of two transcriptional inhibitors, actinomycin and BrdUrd, and two translational inhibitors, puromycin and cycloheximide. Retraction activity is more severely inhibited by the transcriptional than by the translational inhibitors. A tanning response is initiated by cyclic AMP in the presence of the transcriptional but not the translational inhibitors. Dihydric tanning substances (dopa, dopamine) initiate tanning in the presence of both types of inhibitors. Release of ARF and PTF from the central nervous system is inhibited by the four inhibitors. ARF totally reverses the inhibitory effects on retraction, whereas PTF does not reverse inhibition of tanning. These data are interpreted to mean that PTF is concerned with the regulation of two components of the tanning response: (i) acceleration of synthesis of a particular protein (associated with the tyrosine hydroxylation complex), and (ii) activation via cyclic AMP of a component of the tyrosine hydroxylating system. PMID:16592458

Seligman, M; Blechl, A; Blechl, J; Herman, P; Fraenkel, G

1977-10-01

234

Acceleration cueing simulation device  

US Patent & Trademark Office Database

An acceleration cueing simulation device is disclosed for applying sustai, as well as dynamic, acceleration forces to a trainee pilot as he operates an aircraft simulator. The acceleration cueing device comprises a pair of Helmholtz coils for generating a uniform magnetic field; an aircraft control device for generating a control data signal which is responsive to simulated flight maneuvers performed by the trainee pilot; and a computer system for producing a plurality of digital logic signals which are in response to the control data signal. The plurality of digital logic signals, when converted to analog signals, will energize a plurality of coils which are embedded in a suit and a helmet worn by the trainee pilot. When the trainee pilot is within the magnetic field generated by the Helmholtz coils, the coils embedded within the suit and the helmet provide a plurality of simulated acceleration forces which are exerted upon the trainee pilot.

1981-01-13

235

Far field acceleration.  

National Technical Information Service (NTIS)

Far fields are propagating electromagnetic waves far from their source, boundary surfaces, and free charges. The general principles governing the acceleration of charged particles by far fields are reviewed. A survey of proposed field configurations is gi...

R. C. Fernow

1995-01-01

236

Accelerated testing of batteries.  

National Technical Information Service (NTIS)

Three methods of evaluating accelerated battery test data are described. Criteria for each method are used to determine the minimum test matrix required for accurate predictions. Other test methods involving high current discharge and real time techniques...

S. C. Levy P. Bro

1992-01-01

237

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

238

Acceleration Recorder Device.  

National Technical Information Service (NTIS)

The patent application describes a device for use in measuring peak acceleration (g) levels experienced by munitions during rough handling, ballistic launching or at terminal impact. The device is a self-contained mechanical concept based on the predictab...

L. D. Post

1982-01-01

239

Rare Isotope Accelerators  

NASA Astrophysics Data System (ADS)

The next frontier for low-energy nuclear physics involves experimentation with accelerated beams of short-lived radioactive isotopes. A new facility, the Rare Isotope Accelerator (RIA), is proposed to produce large amount of these rare isotopes and post-accelerate them to energies relevant for studies in nuclear physics, astrophysics and the study of fundamental interactions at low energy. The basic science motivation for this facility will be introduced. The general facility layout, from the 400 kW heavy-ion superconducting linac used for production of the required isotopes to the novel production and extraction schemes and the highly efficient post-accelerator, will be presented. Special emphasis will be put on a number of technical breakthroughs and recent R&D results that enable this new facility.

Savard, Guy

2002-04-01

240

Introduction to Acceleration Mechanisms.  

National Technical Information Service (NTIS)

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, ...

R. B. Palmer

1987-01-01

241

Accelerated Corrosion Testing.  

National Technical Information Service (NTIS)

Available methods for accelerated testing of corrosion behavior yield results which are not sufficiently accurate or reliable for predicting the service life of aircraft components and materials which degrade or fail due to environmental attack. Research ...

M. Khobaib

1982-01-01

242

Accelerating Translational Research  

Cancer.gov

Accelerating Translational Research Coordinating and facilitating translational research initiatives across the NCI and the cancer research community. NCI Translational Science Meetings NCI Translates - July 28-29, 2011 NCI Translates - 2009 NCI Translates

243

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

244

Inductive Plasma Accelerator Development.  

National Technical Information Service (NTIS)

The work described in the report comprises: (a) Theoretical studies of the performance of an electromagnetic induction plasma accelerator for radiation-cooled applications, and for pulsed operation. (b) The improvement of pre-existing instrumentation for ...

G. Fonda-Bonardi R. Rosen

1968-01-01

245

Broadband Accelerator Control Network.  

National Technical Information Service (NTIS)

A broadband data communications network has been implemented at BNL for control of the Alternating Gradient Synchrotron (AG) proton accelerator, using commercial CATV hardware, dual coaxial cables as the communications medium, and spanning 2.0 km. A 4 MHz...

J. Skelly T. Clifford R. Frankel

1983-01-01

246

Effects of Cyclic Hydraulic Pressure on Osteocytes  

PubMed Central

Bone is able to adapt its composition and structure in order to suit its mechanical environment. Osteocytes, bone cells embedded in the calcified matrix, are believed to be the mechanosensors and responsible for orchestrating the bone remodeling process. Recent in vitro studies have shown that osteocytes are able to sense and respond to substrate strain and fluid shear. However the capacity of osteocytes to sense cyclic hydraulic pressure (CHP) associated with physiological mechanical loading is not well understood. In this study, we subjected osteocyte-like MLO-Y4 cells to controlled CHP of 68 kPa at 0.5 Hz, and investigated the effects of CHP on intracellular calcium concentration, cytoskeleton organization, mRNA expression of genes related to bone remodeling, and osteocyte apoptosis. We found that osteocytes were able to sense CHP and respond by increased intracellular calcium concentration, altered microtubule organization, a time-dependent increase in COX-2 mRNA level and RANKL/OPG mRNA ratio, and decreased apoptosis. These findings support the hypothesis that loading induced cyclic hydraulic pressure in bone serves as a mechanical stimulus to osteocytes and may play a role in regulating bone remodeling in vivo.

Liu, Chao; Zhao, Yan; Cheung, Wing-Yee; Gandhi, Ronak; Wang, Liyun; You, Lidan

2010-01-01

247

Radioiodination of aryl-alkyl cyclic sulfates.  

PubMed

Among the currently available positron emitters suitable for Positron Emission Tomography (PET), (124)I has the longest physical half-life (4.2 days). The long half-life and well-investigated behavior of iodine in vivo makes (124)I very attractive for pharmacological studies. In this communication, we describe a simple yet effective method for the synthesis of novel (124)I labeled compounds intended for PET imaging of arylsulfatase activity in vivo. Arylsulfatases have important biological functions, and genetic deficiencies of such functions require pharmacological replacement, the efficacy of which must be properly and non-invasively evaluated. These enzymes, even though their natural substrates are mostly of aliphatic nature, hydrolyze phenolic sulfates to phenol and sulfuric acid. The availability of [(124)I]iodinated substrates is expected to provide a PET-based method for measuring their activity in vivo. The currently available methods of synthesis of iodinated arylsulfates usually require either introducing of a protected sulfate ester early in the synthesis or introduction of sulfate group at the end of synthesis in a separate step. The described method gives the desired product in one step from an aryl-alkyl cyclic sulfate. When treated with iodide, the source cyclic sulfate opens with substitution of iodide at the alkyl center and gives the desired arylsulfate monoester. PMID:23135631

Mushti, Chandra; Papisov, Mikhail I Papisov I

2012-11-07

248

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

249

Superplastic deformation induced by cyclic hydrogen charging  

SciTech Connect

Deformation under the combined action of external stress and cyclic hydrogen charging/discharging is studied in a model material, titanium. Cyclic charging with hydrogen is carried out at 860 deg. C, which repeatedly triggers the transformation between hydrogen-lean {alpha}-Ti and hydrogen-rich {beta}-Ti. Due to bias from the externally applied tensile stress, the internal mismatch strains produced by this isothermal {alpha}-{beta} transformation accumulate preferentially along the loading axis. These strain increments are linearly proportional to the applied stress, i.e., flow is ideally Newtonian, at small stress levels (below {approx}2 MPa). Therefore, after multiple chemical cycles, a tensile engineering strain of 100% is achieved without fracture, with an average strain rate of 10{sup -5} s{sup -1}, which demonstrates for the first time that superplastic elongations can be achieved by chemical cycling. The effect of hydrogen partial pressure, cycle time, and external stress on the value of the superplastic strain increments is experimentally measured and discussed in light of a diffusional phase transformation model. Special attention is paid to understanding the two contributions to the internal mismatch strains from the phase transformation and lattice swelling.

Choe, Heeman; Schuh, Christopher A.; Dunand, David C. [School of Advanced Materials Engineering, Kookmin University, Chungneung-dong, Songbuk-ku, Seoul 136-702 (Korea, Republic of); Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States)

2008-05-15

250

Collective field accelerator  

DOEpatents

A collective field accelerator which operates with a vacuum diode and utilizes a grooved cathode and a dielectric anode that operates with a relativistic electron beam with a .nu./.gamma. of .about. 1, and a plurality of dielectric lenses having an axial magnetic field thereabout to focus the collectively accelerated electrons and ions which are ejected from the anode. The anode and lenses operate as unoptimized r-f cavities which modulate and focus the beam.

Luce, John S. (Livermore, CA)

1978-01-01

251

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

252

CEBAF Accelerator Achievements  

NASA Astrophysics Data System (ADS)

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.

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

2011-05-01

253

APT accelerator. Topical report  

Microsoft Academic Search

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

G. Lawrence; D. Rusthoi

1995-01-01

254

Laser Plasma Accelerators  

NASA Astrophysics Data System (ADS)

The continuing development of powerful laser systems has permitted to extend the interaction of laser beams with matter far into the relativistic domain, and to demonstrate new approaches for producing energetic particle beams. The extremely large electric fields, with amplitudes exceeding the TV/m level, that are produced in plasma medium are of relevance particle acceleration. Since the value of this longitudinal electric field, 10,000 times larger than those produced in conventional radio-frequency cavities, plasma accelerators appear to be very promising for the development of compact accelerators. The incredible progresses in the understanding of laser plasma interaction physic, allows an excellent control of electron injection and acceleration. Thanks to these recent achievements, laser plasma accelerators deliver today high quality beams of energetic radiation and particles. These beams have a number of interesting properties such as shortness, brightness and spatial quality, and could lend themselves to applications in many fields, including medicine, radio-biology, chemistry, physics and material science,security (material inspection), and of course in accelerator science.

Malka, Victor

255

Cyclical Recovery Improves Labor Market Situation  

Microsoft Academic Search

Recovery continued over the summer and into early fall without accelerating. Exports remain the driving force for increased capacity utilization and a brightening investment climate. Continued lively domestic demand gives the upturn a broader base but, together with disappointing net receipts from summer tourism, acts as a drag on the current external account. Having passed its trough about a year

Georg M. Busch

1994-01-01

256

The APT Accelerator.*  

NASA Astrophysics Data System (ADS)

The accelerator for the Accelerator Production of Tritium (APT) project is a high-power RF linac designed to produce a 100-mA CW proton beam at an energy of 1300 MeV. A heavy-metal target produces large quantities of spallation neutrons, which are slowed to thermal energies and captured in a feed material to make tritium. The baseline accelerator design consists of a 75-keV proton injector, a 7-MeV radio-frequency quadrupole (RFQ), a 100-MeV coupled-cavity drift-tube linac (CCDTL), and a 1300-MeV side-coupled linac (SCL). The RFQ operates at a frequency of 350 MHz, while the CCDTL and SCL operate at 700-MHz. A quadrupole-magnet transport system conveys the 1300-MeV beam to production target/blanket assemblies where beam expanders using non-linear magnetic elements transform the linac output distribution into large-area rectangular distributions having a nearly uniform density. All the linac accelerating structures use conventional water-cooled copper technology. The SCL section is based on the well-proven 800-MeV LANSCE high-duty-factor linac at Los Alamos. The CCDTL is a new hybrid accelerating structure that combines the best features of the conventional drift-tube linac and the coupled-cavity linac to provide efficient and stable acceleration in the intermediate velocity range. Approximately 263 1-MW CW klystrons are needed to drive the 130-MW proton beam. The total ac-power requirement for the APT plant is about 438 MW, most of which is needed for the accelerator. An advanced-technology option is being considered that would replace the conventional SCL with a superconducting RF linac composed of sequences of 4-cell elliptical-type cavities. This option would reduce the electric power consumption significantly and would provide increased operational flexibility. * Work supported by the US Department of Energy.

Lawrence, George P.

1996-05-01

257

Energy Stabilization of Electrostatic Accelerators  

Microsoft Academic Search

Electrostatic accelerators, such as the Van de Graaf generator, are among the most established and well-developed particle accelerators. One of the key issues in the maturation of these accelerators has been the development of methods used to stabilize the energies of the particles they produce. Energy Stabilization of Electrostatic Accelerators presents a comprehensive overview of the key methods of stabilizing

J. Takács

1997-01-01

258

Plasma-based accelerator structures  

SciTech Connect

Plasma-based accelerators have the ability to sustain extremely large accelerating gradients, with possible high-energy physics applications. This dissertation further develops the theory of plasma-based accelerators by addressing three topics: the performance of a hollow plasma channel as an accelerating structure, the generation of ultrashort electron bunches, and the propagation of laser pulses is underdense plasmas.

Schroeder, Carl B.

1999-12-01

259

Severe combined immune deficiency presenting with cyclic hematopoiesis  

Microsoft Academic Search

At age 2 months a male infant presented with a cyclic clinical syndrome every 14–21 days that included pharyngeal aphthous ulcers, high fever, lymphadenopathy, pallor, and malaise. Serial blood studies indicated cycling of all blood cell elements, compatible with a diagnosis of cyclic hematopoiesis (CH). He also manifested a progressively severe immune deficiency, not described before in human CH. When

Anne K. Junker; Man-Chiu Poon; David I. Hoar; Paul C. J. Rogers

1991-01-01

260

Cyclic and Tangential Polygons 1: Extending a Familiar Concept  

ERIC Educational Resources Information Center

This article "opens up" the study of the relationship between quadrilaterals and circles to two sets of quadrilaterals--those that can be drawn either inside (cyclic) or outside (tangential) a circle (or both). Of course, "all" triangles are both cyclic and tangential. Or, to use the traditional Euclidean language for triangles, a unique…

Lopez-Real, Francis

2002-01-01

261

ON INFINITE p-GROUPS WITH CYCLIC SUBGROUPS  

NASA Astrophysics Data System (ADS)

For each odd prime p, continuum many nonisomorphic simple groups are constructed having isomorphic subgroup lattices and having the property that every proper subgroup is a cyclic p-group. Also constructed is a periodic group of infinite width where every proper subgroup is cyclic. The proofs are based on papers by A. Yu. Ol'shanski?.Figures: 2. Bibliography: 6 titles.

Deryabina, G. S.

1985-02-01

262

Role of Cyclic Nucleotides in the Regulation of Lymphocyte Transformation.  

National Technical Information Service (NTIS)

Studies were conducted to define the roles of cyclic-AMP (cAMP) and cyclic-CMP (cGMP) in lymphocyte mitogenesis. The lymphocyte mitogens staphylococcal enterotoxin B(SEB), concanavalin-A (CON-A), phytohemagglutinin (PHA), and endotoxin, did not stimulate ...

F. R. DeRubertis

1975-01-01

263

Cyclical productivity in a model of labor hoarding  

Microsoft Academic Search

This paper develops a dynamic model of labor hoarding to explain two empirical facts, the cyclical behavior of total factor productivity and the dynamic correlations of sectoral productivity with aggregate variables. The model features convex costs of adjusting the labor force, which induce firms to vary the intensity of labor utilization over the cycle. In particular, cyclical variations in labor

Argia M. Sbordone

1996-01-01

264

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. ...

265

Gonadotropin level abnormalities in women with cyclic mastalgia  

Microsoft Academic Search

Objectives: Women with cyclic mastalgia seem to be at risk of fibrocystic breast disease and\\/or breast cancer. We studied the relationships between mastalgia and hormone levels throughout the menstrual cycle. Study design: Ostensibly healthy women were monitored during a sum of 326 cycles. A case-control study compared personal and hormonal variables of 30 women experiencing cyclic mastalgia with those of

René Ecochard; Henri Marret; Muriel Rabilloud; Hans Boehringer; Claudine Mathieu; Jean-François Guerin

2001-01-01

266

Cyclic creep and anelastic relaxation analysis of an ODS superalloy  

Microsoft Academic Search

This paper documents the effect of stress and temperature on the cyclic minimum strain rate at two different loading frequencies for the oxide dispersion strengthened (ODS) superalloy, INCONEL* MA 6000. The apparent stress exponent and activation energy for cyclic creep at both frequencies studied are shown to be greater than values observed for static creep. The large values of the

Vincent C. Nardone; William L. Kimmerle; John K. Tien

1986-01-01

267

Cyclical variation in paroxysmal supraventricular tachycardia in women  

Microsoft Academic Search

SummaryBackground Paroxysmal supraventricular tachycardia (SVT) in premenopausal women is often judged to be related to anxiety, and may be associated with the menstrual cycle. The aim of this study was to determine whether a cyclical variation of episodes of SVT exists and to correlate such variation with cyclical variation in plasma ovarian hormones.Methods 26 women (mean age 36 [SD 8])

G. M. C Rosano; F Leonardo; F De Luca; P. M Sarrel; C. M Beale; P Collins

1996-01-01

268

Yawing of wind turbines with blade cyclic-pitch variation  

Microsoft Academic Search

The control system horizontal axis wind turbine is discussed. It incorporates two features: the application of blade cyclic pitch variation adopted from rotorcraft technology, and the use of yaw angle control, not only for wind direction following, but also for rotor speed or torque control. Cyclic pitch variation in a two-bladed rotor relieves the blades of all the gyroscopic and

K. H. Hohenemser; A. H. P. Swift; D. A. Peters

1981-01-01

269

Unified construction algorithm of network coding in cyclic networks  

Microsoft Academic Search

Network coding in cyclic networks may have better performance than network coding in acyclic networks with regard to the multi-unicast scenarios. Harvey et al. showed that network coding in cyclic networks can be strictly better than fractional routing in conservative networks which have widely practical scenarios such as P2P networks. Hence, we motivated investigating how to achieve that better performance

Jiaqing Huang; Liang Wang; Tiyuan Zhang; Hui Li

2009-01-01

270

Efficient tracking of cyclic human motion by component motion  

Microsoft Academic Search

A set of techniques are presented for Bayesian tracking of cyclic human motion based on decomposing a complex cyclic motion into component motions. Phases of the component motions are defined and two different mechanisms for coupling the phases are described: importance sampling and an observation model. The intensity of coupling is adaptively adjusted during tracking such that strong coupling is

Cheng Chang; Rashid Ansari; Ashfaq Khokhar

2004-01-01

271

Cyclic AMP, the Microtubule-Microfilament System, and Cancer  

Microsoft Academic Search

Additional evidence is presented for the previously proposed existence in normal fibroblasts of a cyclic AMP-dependent network of microtubules and microfilaments, which is connected with cell membrane elements on one end and with nuclear structures on the other and whose disorganization leads to malignant transformation. In the presence of cyclic AMP derivatives sufficient to promote integrity of this network, cell

Theodore T. Puck

1977-01-01

272

Directed cyclic Hamiltonian cycle systems of the complete symmetric digraph  

Microsoft Academic Search

In this paper, we prove that directed cyclic hamiltonian cycle systems of the complete symmetric digraph, K n, exist if and only if n 2 (mod4) and n 6= 2p with p prime and 1. We also show that directed cyclic hamiltonian cycle systems of the complete symmetric digraph minus a set of n\\/2 vertex-independent digons, (Kn I) , exist

Heather Jordon; Joy Morris

2009-01-01

273

Cyclic electron transport in C3 plants: fact or artefact?  

Microsoft Academic Search

The phenomenon of cyclic electron transport was first characterized in higher plant chloroplasts 50 years ago, yet there is still a debate about whether or not this is a physiological process. The recent isolation of mutants that appear to lack cyclic electron transport, as well as new data providing functional evidence for its occur- rence, support the notion that this

Giles N. Johnson

2005-01-01

274

A cyclic operating policy for batch distillation — Theory and practice  

Microsoft Academic Search

This paper sets out a cyclic operation policy for batch distillation with repeated filling and dumping of the reflux drum. The cyclic policy has several advantages compared to conventional schemes; it achieves the maximum attainable separation in the column; there is a minimal need for control and it is less sensitive to disturbances and therefore safer to operate. For small

E. Sørensen; M. Prenzler

1997-01-01

275

Adenosine 3',5'-cyclic monophosphate in Vibrio cholerae.  

PubMed Central

The extracellular concentration of cyclic adenosine 3',5'-monophosphate (AMP) of three different strains of Vibrio cholerae growing in syncase medium were measured. Cyclic AMP secreted by V. cholerae 569B varied widely, with different carbon sources. Mutant 13, which produced little or no toxin, released half the amount of cyclic AMP as the wild type. The release of less cyclic AMP into the medium by mutant 13 may be accounted for by the lower activity of adenylate cyclase observed. High glucose (3%) in the culture medium reduced the concentration of cyclic AMP both in wild type and mutant 13. Reduction of cyclic AMP levels at high concentrations of glucose (3%) occurred without change of adenylate cyclase activity. The release of enterotoxin to the medium varied with carbon sources but was independent of conditions which reduced the cyclic AMP both within the cell and the medium. Neither adenylate cyclase activity nor toxin production was reduced by an increase concentration of glucose in wild-type V. cholerae, whereas cyclic AMP levels were reduced by sixfold. A lower activity of the adenylate cyclase was observed in a mutant of V. cholerae which produced no detectable toxin. Thus, a correlation exists between toxin production and adenylate cyclase activity in V. cholerae.

Ganguly, U; Greenough, W B

1975-01-01

276

THE DISCRETE FOURIER TRANSFORM AND CYCLIC CONVOLUTION ON INTEGRAL LATTICES  

Microsoft Academic Search

A discrete Fourier transform and a cyclic convolution are constructed on an arbitrary integral lattice. The construction includes as a special case the usual discrete Fourier transform and the usual cyclic convolution. Applications to questions of interpolation of functions and digital signal processing are considered. Methods in the spectral theory of automorphic functions are used to investigate questions in approximation

V A Bykovski?

1989-01-01

277

Lithium Is an Ineffective Therapy for Human Cyclic Hematopoiesis  

Microsoft Academic Search

Cyclic hematopoiesis is a rare disease in man in which severe neutropenia recurs at 21 -day intervals with asso- ciated illness. Because lithium carbonate therapy has been shown to eliminate cyclic hematopoiesis in grey collie dogs, we examined the effects of lithium treatment on five C YCLIC HEMATOPOJESIS (CH) is a rare dis- ease in man; there is a closely

W. P. Hammond; B. Berman; D. G. Wright; D. C. Dale

1983-01-01

278

Multiple-part cyclic hoist scheduling using a sieve method  

Microsoft Academic Search

The paper proposes an algorithm for generating optimal cyclic schedules of hoist moves in a printed circuit board electroplating facility where transportation of parts between workstations is performed by a computer-controlled hoist. The objective of the scheduling problem is to maximize the throughput rate. Unlike many previous algorithms which consider 1-part cyclic schedules, the proposed algorithm provides an exact solution

Vladimir Kats; Eugene Levner; Leonid Meyzin

1999-01-01

279

Laser acceleration with open waveguides  

SciTech Connect

A unified framework based on solid-state open waveguides is developed to overcome all three major limitations on acceleration distance and hence on the feasibility of two classes of laser acceleration. The three limitations are due to laser diffraction, acceleration phase slippage, and damage of waveguide structure by high power laser. The two classes of laser acceleration are direct-field acceleration and ponderomotive-driven acceleration. Thus the solutions provided here encompass all mainstream approaches for laser acceleration, either in vacuum, gases or plasmas.

Xie, Ming

1999-03-01

280

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.

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

2002-01-01

281

Cyclic-stress-strain behavior of rubber  

SciTech Connect

Rubber in general exhibits non-linear viscoelastic behavior. One manifestation of this non-linearity is a variation in the dynamic moduli with strain amplitude. However, a closer examination of the dependence of dynamic moduli on strain suggests that for engineering problems, a linear viscoelastic treatment may provide an adequate representation of the constitutive behavior of rubber, provided the moduli are evaluated at the strain range and loading frequency of interest. This presentation describes an experimental study into the suitability and limitations of a simple linear viscoelastic model used in several large deformation finite element computer codes. The procedure was to obtain the cyclic stress-strain behavior of a rubber suitable for use in a load bearing application and compare the results with the stress-strain response predicted by the finite element code NIKE2D. This code was developed at Lawrence Livermore National Laboratory to study the finite strain response of solids subjected to axisymetric or plane strain deformation.

Lesuer, D.R.; Cornell, R.H.; Santor, S.D.

1982-02-12

282

Cyclic feature analysis, design and exploitation  

NASA Astrophysics Data System (ADS)

In this research project, we characterized the n-th order cyclostationarity properties of general types of LPI signals and used the characterizations to investigate and develop methods for both secure communication and interception. For secure communication, this includes means for reduction of strength of' and elimination of, cyclic features that could be exploited by an interceptor. Signal design for LPI communication was considered from the viewpoints of both the communicator's reception task and the interceptor's reception task. For interception, the characterizations were used to propose feature sets and discrimination rules for signal classification and identification. The basic approach to characterizing n-th order cyclostationarity properties of signals was extended and generalized from the recently developed theory of 2nd-order cyclostationarity, in which spectral characterizations play a crucial role.

Gardner, William A.; Spooner, Chad M.

1994-09-01

283

The prognosis of cyclical vomiting syndrome  

PubMed Central

AIMS—The medium term prognosis of cyclical vomiting syndrome (CVS) was studied to determine the proportion of affected individuals who had gone on to develop headaches fulfilling the International Headache Society criteria for migraine.?METHODS—Twenty six (76%) of 34 CVS sufferers identified from the authors' clinical records were traced, and all agreed to participate. Each child was matched to a control, and telephone interviews were conducted using a standardised questionnaire.?RESULTS—Thirteen (50%) of the subjects had continuing CVS and/or migraine headaches while the remainder were currently asymptomatic. The prevalence of past or present migraine headaches in subjects (46%) was significantly higher than in the control population (12%).?CONCLUSION—Results support the concept that CVS is closely related to migraine.??

Dignan, F; Symon, D; AbuArafeh, I; Russell, G

2001-01-01

284

Linear induction accelerators  

SciTech Connect

The development of linear induction accelerators has been motivated by applications requiring high-pulsed currents of charged particles at voltages exceeding the capability of single-stage, diode-type accelerators and at currents too high for rf accelerators. In principle, one can accelerate charged particles to arbitrarily high voltages using a multi-stage induction machine, but the 50-MeV, 10-kA Advanced Test Accelerator (ATA) at LLNL is the highest voltage machine in existence at this time. The advent of magnetic pulse power systems makes sustained operation at high-repetition rates practical, and this capability for high-average power is very likely to open up many new applications of induction machines in the future. This paper surveys the US induction linac technology with primary emphasis on electron machines. A simplified description of how induction machines couple energy to the electron beam is given, to illustrate many of the general issues that bound the design space of induction linacs.

Briggs, R.J.

1986-06-01

285

Advanced accelerator theory development  

SciTech Connect

A new accelerator technology, the dielectric wall accelerator (DWA), is potentially an ultra compact accelerator/pulsed power driver. This new accelerator relies on three new components: the ultra-high gradient insulator, the asymmetric Blumlein and low jitter switches. In this report, we focused our attention on the first two components of the DWA system the insulators and the asymmetric Blumlein. First, we sought to develop the necessary design tools to model and scale the behavior of the high gradient insulator. To perform this task we concentrated on modeling the discharge processes (i.e., initiation and creation of the surface discharge). In addition, because these high gradient structures exhibit favorable microwave properties in certain accelerator configurations, we performed experiments and calculations to determine the relevant electromagnetic properties. Second, we performed circuit modeling to understand energy coupling to dynamic loads by the asymmetric Blumlein. Further, we have experimentally observed a non-linear coupling effect in certain asymmetric Blumlein configurations. That is, as these structures are stacked into a complete module, the output voltage does not sum linearly and a lower than expected output voltage results. Although we solved this effect experimentally, we performed calculations to understand this effect more fully to allow better optimization of this DWA pulse-forming line system.

Sampayan, S.E.; Houck, T.L.; Poole, B.; Tishchenko, N.; Vitello, P.A.; Wang, I.

1998-02-09

286

Microelectromechanical acceleration-sensing apparatus  

SciTech Connect

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

287

Occurrence and function of cyclic nucleotides in blood vessels.  

PubMed

The literature concerned with studies of the occurrence and function of the cyclic nucleotides in blood vessels is reviewed. Emphasis is placed on the critical evaluation of the evidence which relates to the hypothesis that cyclic nucleotides meditate the effects of drugs and neurotransmitters on vascular contractility. The hypothesis that cyclic AMP mediates vasodilation, especially that induced by beta-adrenergic relaxation, is supported by many experimental approaches, but it is concluded that the evidence remains unconvincing based on the criteria established for such a mediator role. Possible sites of action of cyclic AMP are discussed. The demonstrated action of cyclic AMP on vascular membrane electrophysiology and calcium ion pumps are reviewed as possible causes of relaxation. The role of both nucleotides in vascular disease, especially hypertension is discussed. Finally the needs for further research in this area are suggested. PMID:174765

Namm, D H; Leader, J P

1976-01-01

288

Opposite effects of cyclic GMP and cyclic AMP on Ca2+ current in single heart cells  

Microsoft Academic Search

The slow inward Ca2+ current, ICa, is fundamental in the initiation of cardiac contraction and neurohormonal regulation of cardiac function1. It is increased by beta-adrenergic agonists, which stimulate synthesis of cyclic AMP (cAMP) and cAMP-dependent phosphorylation2-4. The neurotransmitter acetylcholine reduces ICa5-7 by an unknown mechanism8,9. There is strong evidence that acetylcholine reduces ICa by decreasing adenylate cyclase activity7, but cGMP

H. Criss Hartzell; Rodolphe Fischmeister

1986-01-01

289

Accelerator Technology Program  

NASA Astrophysics Data System (ADS)

Highlights of major projects in the Accelerator Technology Division of the Los Alamos National Laboratory are presented. The first section deals with the Fusion Materials Irradiation Test Facility's 2-MeV accelerator on which tests began in May, as scheduled. Then, activities are reported on beam dynamics, inertial fusion, structure development, the racetrack microtron, the CERN high-energy physics experiment NA-12, and LAMPF II. The Proton Storage Ring is discussed next, with emphasis on the computer control system, diagnostics interfacing, and theoretical support. Other sections summarize progress on a portable radiographic linac, developments on the klystron code, and on permanent magnets. Activities of the Theory and Simulation Group are outlined next, followed by discussion of the oscillator experiment and the energy-recovery experiment in the free electron laser project. The last section reports on the accelerator test stand.

Jameson, R. A.

1984-07-01

290

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

PubMed

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

2013-09-06

291

Stoichiometry and structural effect of the cyclic nucleotide binding to cyclic AMP receptor protein.  

PubMed

Cyclic AMP receptor protein (CRP) is a homodimeric protein, which is activated by cAMP binding to function as a transcriptional regulator of many genes in prokaryotes. Until now, the actual number of cAMP molecules that can be bound by CRP in solution has been ambiguous. In this work, we performed a nuclear magnetic resonance study on CRP to investigate the stoichiometry of cyclic nucleotide binding to CRP. A series of (1)H-(15)N heteronuclear single quantum coherence (HSQC) spectra of the protein in the absence and in the presence of cAMP or cGMP were analyzed. The addition of cAMP to CRP induced a biphasic spectral change up to 4 equivalents, whereas the cGMP addition made a monophasic change up to 2 equivalents. Altogether, the results not only established for the first time that CRP possesses two cyclic AMP-binding sites in each monomer, even in a solution without DNA, but also suggest that the syn-cAMP binding sites of the CRP dimer can be formed by an allosteric conformational change of the protein upon the binding of two anti-cAMPs at the N-terminal domain. In addition, a residue-specific inspection of the spectral changes provides some new structural information about the cAMP-induced allosteric activation of CRP. PMID:11781328

Won, Hyung-Sik; Lee, Tae-Woo; Park, Sang-Ho; Lee, Bong-Jin

2002-01-07

292

Cyclic and radial variation of ultrasonic backscatter from flowing porcine blood  

NASA Astrophysics Data System (ADS)

The ultrasonic backscattering from flowing blood was investigated using several hemodynamic parameters and a physiological parameter. Acceleration was hypothesized to enhance the aggregation of red blood cells (RBCs), and this is the first time that acceleration is suggested and experimentally verified as having an effect on aggregation of RBC. Two interesting phenomena, the 'Black Hole (BH)' phenomenon and the 'Bright Collapsing Ring (BCR)' phenomenon, were observed under pulsatile flow in B-mode cross sectional images. The BH phenomenon describes a dark hypoechoic hole at the center of the tube surrounded by a bright hyperechoic zone in B-mode cross sectional images, and the BCR phenomenon describes the appearance of a bright hyperechoic ring at the periphery of the tube at early systole and its convergence from the periphery to the center of the tube, finally collapsing as flow develops. Doppler power variation was observed only from porcine whole blood, which led to a conclusion that the ultrasonic backscattering was mainly dependent on the RBC aggregation under steady and pulsatile flow. The pattern of the cyclic variation of the Doppler power to have a maximum power at peak systole was mainly due to the enhanced rouleaux formation by acceleration. The BCR phenomenon was observed from the cyclic variation pattern of the Doppler power at different radial positions; the Doppler power peak was observed at early systole at the periphery of the tube and lagged the flow as close from the periphery to the center of the tube. The BCR phenomenon from porcine whole blood in a mock flow loop was further examined in real time in B-mode images under pulsatile flow. At low hematocrit of 12%, no BCR phenomenon was discernable although it was observed at higher hematocrits. The pattern of the nonlinear relationship between echogenicity and hematocrit varied with radial positions. The BH phenomenon was also observed under certain hemodynamic conditions and varied over a pulsatile cycle. The BCR phenomenon was also observed from human carotid arteries from 10 subjects only in the harmonic images. In order to better understand these phenomena, the cyclic and radial variation of echogenicity under oscillatory flow was measured and the results showed a different pattern from that under pulsatile flow. (Abstract shortened by UMI.)

Paeng, Dong-Guk

293

Analysis of cyclic creep and rupture. Part 2: calculation of cyclic reference stresses and ratcheting interaction diagrams  

Microsoft Academic Search

Part 1 gives the basis for the use of cyclic reference stresses for high temperature design and assessment. The methodology relies on elastic–plastic calculations for limit loads, ratcheting and shakedown. In this paper we use a commercial non-linear finite element code for these calculations. Two fairly complex and realistic geometries with cyclic loads are analysed, namely a pipe elbow and

P. Carter

2005-01-01

294

Acceleration of metal plates  

SciTech Connect

High-explosive charges have been used to accelerate stainless steel plates to velocities of 6-7 km/s. A two-stage system has been used in which the first stage is a plane-wave detonating system that accelerates the plate down a short barrel. The second stage consists of a hollow cylindrical charge through which the moving plate passes. After an adjustable delay this charge is detonated on the outer circumference of the entry side of the charge. Flash radiographs and witness plates show no breakup in the first stage but bowing and frequent breakup in the second stage. 6 figs.

Marsh, S.P.; McQueen, R.G.; Tan, T.H.

1989-01-01

295

Accelerated molecular dynamics methods  

SciTech Connect

The molecular dynamics method, although extremely powerful for materials simulations, is limited to times scales of roughly one microsecond or less. On longer time scales, dynamical evolution typically consists of infrequent events, which are usually activated processes. This course is focused on understanding infrequent-event dynamics, on methods for characterizing infrequent-event mechanisms and rate constants, and on methods for simulating long time scales in infrequent-event systems, emphasizing the recently developed accelerated molecular dynamics methods (hyperdynamics, parallel replica dynamics, and temperature accelerated dynamics). Some familiarity with basic statistical mechanics and molecular dynamics methods will be assumed.

Perez, Danny [Los Alamos National Laboratory

2011-01-04

296

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

297

Accelerator technology program  

NASA Astrophysics Data System (ADS)

Highlights in beam dynamics, accelerator inertial fusion, radio frequency structure development, the racetrack microtron, CERN high energy physics experiment NA-12, and high flux radiographic linac study are reported. Selected proton Storage Ring activities and an update on the free electron laser are discussed. The fusion materials irradiation test facility work and progress on the klystron development project and on the gyrocon project are examined. The activities of the newly formed theory and simulation group are outlined. Activities concerning the accelerator test stand for the neutral particle beam program are outlined.

Jameson, R. A.

1984-05-01

298

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

299

Particle acceleration in Blazars  

NASA Astrophysics Data System (ADS)

Understanding the variable emission of blazars observed with gamma-ray telescopes and Fermi has become a major challenge for theoretical models of particle acceleration. Here, we introduce a novel time-dependent emission model in which the maximum energy of particles is determined from a balance between Fermi type I and II acceleration energy gains and radiative energy losses, allowing for an explanation of both the characteristic spectral energy distribution of blazars and their intrinsic sub-hour variability. Additionally, we can determine the physical condition of the emitting plasma concerning its turbulence and typical shock speeds.

Weidinger, Matthias; Spanier, Felix

2011-06-01

300

Two-beam accelerator  

SciTech Connect

In the two-beam accelerator (TBA) concept, an electron linear accelerator structure is established in which two beams propagate. One is an intense low energy beam that is made to undergo free electron lasing to produce microwaves. These microwaves are then coupled to another part of the structure where they act to produce a high longitudinal electric gradient that is used to accelerate a second relatively low intensity electron beam to very high energies. The TBA was originally suggested by Sessler as a possible means for economically achieving linear collider energies of 100 GeV and above. Although still in a conceptual stage, the TBA is an inherently plausible concept that combines the free electron laser (FEL) with several well-known technologies - high current induction linacs, microwave waveguides, and traveling-wave linac structures - in a novel and interesting way. Two characteristics of the TBA that make it a particularly suitable candidate for achieving high energies are its ability to operate at higher frequencies than typical present-day linacs (say 30 GHz as compared with 3 GHz), and to be an efficient means for delivering power to a hitherto unattainable high-gradient structure (say 250 MV/m) that the higher frequency makes possible. These high accelerating gradients will permit much shorter linac structures for a given energy.

Selph, F.B.

1984-09-01

301

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

302

Plasma based accelerators  

NASA Astrophysics Data System (ADS)

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.

1987-05-01

303

Acceleration of convergence  

SciTech Connect

Acceleration of the convergence of approximate operator iteration schemes is discussed. Algorithms based on both residual minimization and use of conjugate vector spaces are presented. It is shown that both give dramatic improvement, at very low computational cost, in the iterative solution of radiative transfer problems in the presence of scattering. 13 refs., 7 figs.

Auer, L.

1990-01-01

304

COLLECTIVE PHENOMENA IN ACCELERATORS  

Microsoft Academic Search

Recent years have witnessed the development of accelerators of ever-larger current, both peak and average, as well as a proliferation of storage rings of ever-greater luminosity. Consequently, there is considerable interest in and growing concern with, the phenomena which limit beam currents and beam densities, namely, the collective modes of behavior of relativistic particle beams. Furthermore, it has been demonstrated

Sessler; Andrew M

1972-01-01

305

European particle accelerator conference  

SciTech Connect

This book contains the following topics: The LEP project, Superconducting RF cavities for accelerator application, Commissioning of super-ACO, Pulsed high-power beams, RF Power sources, Astrid, A storage ring for ions and electrons, Linear collider studies in Europe.

Tazzari, S.

1988-01-01

306

Medical proton accelerator facility.  

PubMed

This paper presents a specialized medical accelerator facility designed for proton radiation therapy and for production of short-lived nuclide-labelled radiopharmaceuticals. General features of the facility structure, the choice of principles of beam delivery, physical and technical problems connected with clinical work, and biomedical research are discussed. PMID:2846478

Khoroshkov, V S; Goldin, L L

1988-10-01

307

Commissioning the GTA accelerator  

Microsoft Academic Search

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

O. R. Sander; W. H. Atkins; G. O. Bolme; S. Bowling; S. Brown; R. Cole; J. D. Gilpatrick; R. Garnett; F. W. Guy; W. B. Ingalls; K. F. Johnson; D. Kerstiens; C. Little; R. A. Lohsen; S. Lloyd; W. P. Lysenko; C. T. Mottershead; G. Neuschaefer; J. Power; D. P. Rusthoi; Sandoval D. P. Stevens R. R. Jr; G. Vaughn; E. A. Wadlinger; V. Yuan; R. Connolly; R. Weiss; K. Saadatmand

1992-01-01

308

Commissioning the GTA accelerator  

Microsoft Academic Search

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

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

1992-01-01

309

The Physics Hypertextbook: Acceleration  

NSDL National Science Digital Library

This resource offers support in understanding equations related to acceleration and includes several problems for numerical practice. Scroll to the bottom for a list of links to additional engaging and innovative activities for high school students. This is part of an online textbook in introductory physics.

Elert, Glenn

2006-10-19

310

Acceleration of cheese ripening  

Microsoft Academic Search

The characteristic aroma, flavour and texture of cheese develop during ripening of the cheese curd through the action of numerous enzymes derived from the cheese milk, the coagulant, starter and non-starter bacteria. Ripening is a slow and consequently an expensive process that is not fully predictable or controllable. Consequently, there are economic and possibly technological incentives to accelerate ripening. The

P. F. Fox; J. M. Wallace; S. Morgan; C. M. Lynch; E. J. Niland; J. Tobin

1996-01-01

311

The neutrino electron accelerator  

SciTech Connect

It is shown that a wake of electron plasma oscillations can be created by the nonlinear ponderomotive force of an intense neutrino flux. The electrons trapped in the plasma wakefield will be accelerated to high energies. Such processes may be important in supernovas and pulsars. {copyright} {ital 1998 American Institute of Physics.}

Shukla, P.K. [Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Stenflo, L. [Department of Plasma Physics, Umea University, S-90187 Umea (Sweden); Bingham, R. [Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX (United Kingdom); Bethe, H.A. [Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Dawson, J.M. [Department of Physics, University of California, Los Angeles, California 90024 (United States); Mendonca, J.T. [Department of Physics, University of Lisbon, 1096 Lisbon (Portugal)

1998-01-01

312

Accelerated Testing Technology.  

National Technical Information Service (NTIS)

The report, in two volumes, is devoted to an investigation into the state-of-the-art of methods for reducing the time and expense associated with life testing, particularly as it relates to parts. The areas investigated are divided into accelerated testin...

W. Yurkowsky R. E. Schafer J. M. Finkelstein

1967-01-01

313

Incineration by accelerator.  

National Technical Information Service (NTIS)

The use MOX fuel allows to hope a stabilization of plutonium production around 500 tons for the French park. In return, the flow of minor actinides is increased to several tons. INCA (INCineration by Accelerator), dedicated instrument, would allow to tran...

M. Cribier G. FIoni R. Legrain F. Lelievre S. Leray

1997-01-01

314

Accelerating Gifted Children  

ERIC Educational Resources Information Center

To have young children disconnected from school is not in their best interest. Yet, some bright students feel disconnected because the curriculum is well below their readiness level. For academically gifted students, acceleration is an effective-and cost-effective-way of meeting their learning and social needs. We hope the Nation Deceived report…

Colangelo, Nicholas; Assouline, Susan G.

2005-01-01

315

EFFECTS OF CYCLIC FLEXURAL FATIGUE ON PORCINE BIOPROSTHETIC HEART VALVE HETEROGRAFT BIOMATERIALS  

PubMed Central

While 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. While 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 the present 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. 10×106, 25×106 and 50×106 cycle levels were used, with resulting changes in flexural stiffness and collagen structure assessed. Results indicated that flexural rigidity was markedly reduced after only 10×106 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 10×106 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 towards the need for the development of chemical fixation technologies that minimize flexure induced damage to extend porcine heterograft biomaterial durability.

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

2009-01-01

316

Cyclic AMP-elevating agents prevent oligodendroglial excitotoxicity.  

PubMed

Previously, we have demonstrated that cells of the oligodendroglial lineage express non-NMDA glutamate receptor genes and are damaged by kainate-induced Ca2+ influx via non-NMDA glutamate receptor channels, representing oligodendroglial excitotoxicity. We find in the present study that agents that elevate intracellular cyclic AMP prevent oligodendroglial excitotoxicity. After oligodendrocyte-like cells, differentiated from the CG-4 cell line established from rat oligodendrocyte type-2 astrocyte progenitor cells, were exposed to 2 mM kainate for 24 h, cell death was evaluated by measuring activity of lactate dehydrogenase released into the culture medium. Released lactate dehydrogenase increased about threefold when exposed to 2 mM kainate. Kainate-induced cell death was prevented by one of the following agents: adenylate cyclase activator (forskolin), cyclic AMP analogues (dibutyryl cyclic AMP and 8-bromo-cyclic AMP), and cyclic AMP phosphodiesterase inhibitors (3-isobutyl-1-methylxanthine, pentoxifylline, propentofylline, and ibudilast). Simultaneous addition of both forskolin and phosphodiesterase inhibitors prevented the kainate-induced cell death in an additive manner. A remarkable increase in Ca2+ influx (approximately 5.5-fold) also was induced by kainate. The cyclic AMP-elevating agents caused a partial suppression of the kainate-induced increase in Ca2+ influx, leading to a less prominent response of intracellular Ca2+ concentration to kainate. The suppressing effect of forskolin on the kainate-induced Ca2+ influx was partially reversed by H-89, an inhibitor of cyclic AMP-dependent protein kinase. In contrast to this, okadaic acid, an inhibitor of protein phosphatases 1 and 2A, brought about a decrease in the kainate-induced Ca2+ influx. We therefore concluded that cyclic AMP-elevating agents prevented oligodendroglial excitotoxicity by cyclic AMP-dependent protein kinase-dependent protein phosphorylation, resulting in decreased kainate-induced Ca2+ influx. PMID:9603206

Yoshioka, A; Shimizu, Y; Hirose, G; Kitasato, H; Pleasure, D

1998-06-01

317

Predicting the conformational states of cyclic tetrapeptides.  

PubMed

Biologically active cyclic tetrapeptides, usually found among fungi metabolites, exhibit phytotoxic or cytostatic activities that are likely to be governed by specific conformations adopted in solution. For conformational studies and drug design, there is a strong interest in using fast and reliable methods to determine correctly the conformational population of cyclotetrapeptides. We show here that standard molecular mechanics computational approach gives satisfactory results. The method was validated step by step by experimental data either obtained after synthesis and NMR analysis, or found in the literature. The cyclo(Gly)(4), cyclo(Ala)(4), cyclo(Sar)(4), and cyclo(SarGly)(2) peptides were used to evaluate the prediction of the peptide backbone conformation, and the detailed conformational analysis of tentoxin, a natural phytotoxic cyclotetrapeptide in which N-alkylated peptide bonds alternate with regular secondary ones, was used to validate the computation of conformers proportions. From the knowledge of an initial cyclic primary structure and of the D or L configuration of the amino acids, we show that it is possible to determine the exact orientation of carbonyl groups and to predict the nature of conformers present in solution. The proportion of each conformer can be inferred from a statistical thermodynamics approach by using the potential energy values of each conformer, computed by molecular mechanics methods with the TRIPOS force field, which allowed us to account for the solvent. The solvent contribution was processed by two different methods according to the nature of the interactions: whether through the dielectric constant introduced in the electrostatic potential, when interaction with solute molecules are weak or negligible, or through the computation of free energy of solvation using the algorithm SILVERWARE for solvents explicitly interacting with the solute. When applied to tentoxin, this conformational analysis yielded results in very good agreement with the experimental data reported by Pinet et al. (Biopolymers, 1995, Vol. 36, pp. 135-152), on both the nature of existing conformers and their relative proportions, whatever the nature of the considered solvent. PMID:12833263

Loiseau, Nicolas; Gomis, Jean-Marie; Santolini, Jérôme; Delaforge, Marcel; André, François

2003-07-01

318

Stacked insulator induction accelerator gaps  

SciTech Connect

Stacked insulators, with alternating layers of insulating material and conducting film, have been shown to support high surface electrical field stresses. We have investigated the application of the stacked insulator technology to the design of induction accelerator modules for the Relativistic-Klystron Two-Beam Accelerator program. The rf properties of the accelerating gaps using stacked insulators, particularly the impedance at frequencies above the beam pipe cutoff frequency, are investigated. Low impedance is critical for Relativistic-Klystron Two-Beam Accelerator applications where a high current, bunched beam is trsnsported through many accelerating gaps. An induction accelerator module designs using a stacked insulator is presented.

Houck, T.I.; Westenskow, G.A.; Kim, J.S.; Eylon, S.; Henestroza, E.; Yu, S.S.; Vanecek, D.

1997-05-01

319

Accelerator Markup Language and the Universal Accelerator Parser.  

National Technical Information Service (NTIS)

A major obstacle to collaboration on accelerator projects has been the sharing of lattice description files between modeling codes. To address this problem, a lattice description format called Accelerator Markup Language (AML) has been created. AML is bas...

A. Wolski D. Sagan D. A. Bates F. Schmidt M. Forster N. J. Walker

2006-01-01

320

Predicted and observed cyclic performance of piles in calcareous sand  

SciTech Connect

The performance of small-scale model piles jacked into calcareous sand and tested under cyclic axial loadings is presented in this paper. The calcareous sand beds used for the tests have been prepared from reconstituted soil that has been consolidated under different overburden pressures using a test vessel of special design. The study is focused on the accumulation of permanent displacement of the piles under both uniform and nonuniform amplitude cyclic loadings. A numerical analysis is employed to predict the cyclic behavior of the model piles, using input parameters derived from the experimental results. Comparisons between the measured and predicted results show reasonable agreement.

Al-Douri, R.H.; Poulos, H.G. (Univ. of Sydney (Australia))

1995-01-01

321

Water clusters on Cu(110): Chain versus cyclic structures  

NASA Astrophysics Data System (ADS)

Water clusters are assembled and imaged on Cu(110) by using a scanning tunneling microscope. Water molecules are arranged along the Cu row to form ``ferroelectric'' zigzag chains of trimer to hexamer. The trimer prefers the chain form to a cyclic one in spite of the reduced number of hydrogen bonds, highlighting the crucial role of the water-substrate interaction in the clustering of adsorbed water molecules. On the other hand, the cyclic form with maximal hydrogen bonds becomes more favorable for the tetramer, indicating the crossover from chain to cyclic configurations as the constituent number increases.

Kumagai, T.; Okuyama, H.; Hatta, S.; Aruga, T.; Hamada, I.

2011-01-01

322

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.

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

2013-01-01

323

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

324

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

PubMed

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

2013-10-21

325

Differential effects of cyclic uniaxial stretch on human mesenchymal stem cell into skeletal muscle cell.  

PubMed

Both fetal and adult skeletal muscle cells are continually being subjected to biomechanical forces. Biomechanical stimulation during cell growth affects proliferation, differentiation and maturation of skeletal muscle cells. Bone marrow-derived hMSCs [human MSCs (mesenchymal stem cells)] can differentiate into a variety of cell types, including skeletal muscle cells that are potentially a source for muscle regeneration. Our investigations involved a 10% cyclic uniaxial strain at 1 Hz being applied to hMSCs grown on collagen-coated silicon membranes with or without IGF-I (insulin-like growth factor-I) for 24 h. Results obtained from morphological studies confirmed the rearrangement of cells after loading. Comparison of MyoD and MyoG mRNA levels between test groups showed that mechanical loading alone can initiate myogenic differentiation. Furthermore, comparison of Myf5, MyoD, MyoG and Myf6 mRNA levels between test groups showed that a combination of mechanical loading and growth factor results in the highest expression of myogenic genes. These results indicate that cyclic strain may be useful in myogenic differentiation of stem cells, and can accelerate the differentiation of hMSCs into MSCs in the presence of growth factor. PMID:22681392

Haghighipour, Nooshin; Heidarian, Saeide; Shokrgozar, Mohammad Ali; Amirizadeh, Naser

2012-07-01

326

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

PubMed

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

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

2002-05-22

327

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.

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

2002-01-01

328

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

329

?-Defensins: cyclic peptides with endless potential.  

PubMed

?-Defensins, the only cyclic peptides of animal origin, have been isolated from the leukocytes of rhesus macaques and baboons. Their biogenesis is unusual because each peptide is an 18-residue chimera formed by the head-to-tail splicing of nonapeptides derived from two separate precursors. ?-Defensins have multiple arginines and a ladder-like tridisulfide array spanning their two antiparallel ?-strands. Human ?-defensin genes contain a premature stop codon that prevents effective translation of the needed precursors; consequently, these peptides are not present in human leukocytes. Synthetic ?-defensins with sequences that correspond to those encoded within the human pseudogenes are called retrocyclins. Retrocyclin-1 inhibits the cellular entry of HIV-1, HSV, and influenza A virus. The rhesus ?-defensin RTD-1 protects mice from an experimental severe acute respiratory syndrome coronavirus infection, and retrocyclin-1 protects mice from infection by Bacillus anthracis spores. The small size, unique structure, and multiple host defense activities of ?-defensins make them intriguing potential therapeutic agents. PMID:22700960

Lehrer, Robert I; Cole, Alex M; Selsted, Michael E

2012-06-14

330

Understanding cyclical thrombocytopenia: a mathematical modeling approach.  

PubMed

Cyclical thrombocytopenia (CT) is a rare hematological disease characterized by periodic oscillations in the platelet count. Although first reported in 1936, the pathogenesis and an effective therapy remain to be identified. Since besides fluctuations in platelet levels the patients hematological profile have been consistently normal, a destabilization of a peripheral control mechanism might play an important role in the genesis of this disorder. In this paper, we investigate through computer simulations the mechanisms underlying the platelet oscillations observed in CT. First, we collected the data published in the last 40 years and quantified the significance of the platelet fluctuations using Lomb-Scargle periodograms. Our analysis reveals that the incidence of the statistically significant periodic data is equally distributed in men and women. The mathematical model proposed in this paper captures the essential features of hematopoiesis and successfully duplicates the characteristics of CT. With the same parameter changes, the model is able to fit the platelet counts and to qualitatively reproduce the TPO oscillations (when data is available). Our results indicate that a variation in the megakaryocyte maturity, a slower relative growth rate of megakaryocytes, as well as an increased random destruction of platelets are the critical elements generating the platelet oscillations in CT. PMID:18191155

Apostu, Raluca; Mackey, Michael C

2007-11-29

331

Cyclic Damage in Steel Experiencing Seismic Loading  

NASA Astrophysics Data System (ADS)

During the mid 1990s earthquakes in Northridge, California, and Kobe, Japan, illustrated a lack of understanding of the behaviour of structural steels exposed to seismic loads. Under this type of load regime, structural steel members are subjected to fully plastic load cycles and unexpectedly brittle failures may result. A method for determining the accumulation of damage through cyclic pre-straining is proposed. Toughness, as defined by the area under the true stress strain curve, is used as an indicator of the level of damage that the steel has suffered and from this some idea of its remaining capacity to further deform can be determined. Observations during the testing of these samples have indicated that there is a transition in the failure mode from a fatigue type failure, with a progressively growing crack, to an overload failure, in which the steel fails due to a lack of ability to further deform. Similar transitions have been noted by other researchers in the field. Analysis of the test results seems to show differences in the damage accumulation behaviour that may be used to identify when this transition in failure modes may occur.

Seal, C. K.; Hodgson, M. A.; Ferguson, W. G.

332

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

333

Equilibrium polymerization of cyclic carbonate oligomers  

NASA Astrophysics Data System (ADS)

A model of the polymerization of ring oligomers of bisphenol A polycarbonate (BPA-PC) is used to investigate the influence of dimensionality (2D or 3D), density and temperature on the size distribution of the polymer chains. The polymerization step is catalyzed by a single active particle, conserves the number and type of the chemical bonds, and occurs without a significant gain in either potential energy or configurational entropy. Monte Carlo and molecular dynamics simulations show that polymerization of cyclic oligomers occurs readily at high density and is driven by the entropy associated with the distribution of interparticle bonds. Polymerization competes at lower densities with long range diffusion, which favors small molecular species, and is prevented if the system is sufficiently dilute. Polymerization occurs in 2D via a weakly first order transition as a function of density and is characterized by low hysteresis and large fluctuations in the size of polymer chains. Polymerization occurs more readily in 3D than in 2D, and is favored by increasing temperature, as expected for an entropy-driven process.

Ballone, P.; Jones, R. O.

2001-08-01

334

Acceleration of /sup 14/C beams in electrostatic accelerators  

SciTech Connect

Operational problems in the production and acceleration of /sup 14/C beams for nuclear structure research in Los Alamos National Laboratory's Van de Graaff accelerators are discussed. Methods for the control of contamination in ion sources, accelerators and personnel are described. Sputter source target fabrication techniques and the relative beam production efficiencies of various types of bound particulate carbon sputter source targets are presented.

Rowton, L.J.; Tesmer, J.R.

1981-01-01

335

Mass spectrometry with accelerators.  

PubMed

As one in a series of articles on Canadian contributions to mass spectrometry, this review begins with an outline of the history of accelerator mass spectrometry (AMS), noting roles played by researchers at three Canadian AMS laboratories. After a description of the unique features of AMS, three examples, (14)C, (10)Be, and (129)I are given to illustrate the methods. The capabilities of mass spectrometry have been extended by the addition of atomic isobar selection, molecular isobar attenuation, further ion acceleration, followed by ion detection and ion identification at essentially zero dark current or ion flux. This has been accomplished by exploiting the techniques and accelerators of atomic and nuclear physics. In 1939, the first principles of AMS were established using a cyclotron. In 1977 the selection of isobars in the ion source was established when it was shown that the (14)N(-) ion was very unstable, or extremely difficult to create, making a tandem electrostatic accelerator highly suitable for assisting the mass spectrometric measurement of the rare long-lived radioactive isotope (14)C in the environment. This observation, together with the large attenuation of the molecular isobars (13)CH(-) and (12)CH?2(-) during tandem acceleration and the observed very low background contamination from the ion source, was found to facilitate the mass spectrometry of (14)C to at least a level of (14)C/C ~ 6 × 10(-16), the equivalent of a radiocarbon age of 60,000 years. Tandem Accelerator Mass Spectrometry, or AMS, has now made possible the accurate radiocarbon dating of milligram-sized carbon samples by ion counting as well as dating and tracing with many other long-lived radioactive isotopes such as (10)Be, (26)Al, (36)Cl, and (129)I. The difficulty of obtaining large anion currents with low electron affinities and the difficulties of isobar separation, especially for the heavier mass ions, has prompted the use of molecular anions and the search for alternative methods of isobar separation. These techniques are discussed in the latter part of the review. PMID:22031277

Litherland, A E; Zhao, X-L; Kieser, W E

2010-12-23

336

Particle Acceleration in Pulsar Magnetospheres.  

National Technical Information Service (NTIS)

The structure of pulsar magnetospheres and the acceleration mechanism for charged particles in the magnetosphere was studied, using a pulsar model which required large acceleration of the particles near the surface of the star. A theorem was developed whi...

K. B. Baker

1978-01-01

337

Accelerator operation management using objects.  

National Technical Information Service (NTIS)

Conflicts over control of shared devices or resources in an accelerator control system, and problems that can occur due to applications performing conflicting operations, are usually resolved by accelerator operators. For these conflicts to be detected by...

H. Nishimura C. Timossi M. Valdez

1995-01-01

338

New Accelerated Corrosion Test Methods.  

National Technical Information Service (NTIS)

A project which established accelerated corrosion test methods for conventional Al and new AlLi alloys and surface protection schemes is described. New accelerated testing methods will allow the selection of material and protection schemes with increased ...

U. Koch T. Hack

1991-01-01

339

Photonic Acceleration in Astrophysics  

NASA Astrophysics Data System (ADS)

Gamma Ray Bursts (GRB) deliver very high intensity photons with energies from 10 keV to over 100 MeV at a irradiance of 10^30 (30 km/R)^2 Watt/cm^2. This is in the nonlinear QED regime and the induced wakefield is close to the Schwinger field (E ~^16 V/cm). Protons and electrons can be accelerated in such a strong field to 10^21 eV/km in the vicinity of the GRB source. The maximum acceleration is limited by the critical Schwinger field times the length of the field: q ( E (= 10^16.5 V/cm) ( L ((1000 km) = 10^24 eV. Trains of such wakefields are expected in the outflow of photons from GRB's, which gives a Chapman-Kolmogorov type power energy spectrum [Chandrasekhar, 1953; Mima et al. 1991], which is close to a Bremsstrahlung-type spectrum, f(E) = E^-a (a = 1). Some of the accelerated protons can have energies as high as 10^23 eV. The secondary pions and their daughters (neutrinos) that may be produced in-situ near the acceleration site of the GRB can have energies around 10^22 eV (= 1.6 ( 10^10 erg). The neutrino flux from the semi-daily occurrence of GRB's (with energy output of ~ 10^52 erg can provide a flux of high intensity EHE neutrinos in the universe as a function of the acceleration efficiency coefficient (k): I( (E ( 10^21 eV) = 5k (10^52 eV)/(1.6 ( 10^10 erg)/4(pi)R^2/day = 1 /km^2 yr (for k = 1% *). *(cf. Laser wakefield experiments with Petawatt indicated k = 5 ~ 10% for protons [M. Key, 1999].) A compact photonic acceleration mechanism is thus suggested as a candidate for the origin of extremely high energy cosmic rays (EECR). Observed characteristics of EECR beyond energies of several 1019 eV pose a number of challenges and opportunities for physics and astrophysics. Foremost among them is the apparent defiance or violation of the proton energy cutoff of Greisen-Zatsepin-Kuzmin (GZK). The other is the apparent correlation in some of ECR events. And the most important is the difficulty to accelerate particles by the conventional Fermi mechanism to reach such high energies. We suggest that the intense photon flux emanating from a gamma ray burst is capable of yielding a sufficiently robust and rugged plasma structure suitable to accelerate protons and other charged particles to extreme high energies ( ~ 10^22 eV) over thousands of kilometers in the GRB atmosphere. Photon flux above a certain threshold can self-modulate in the plasma to create longitudinal (as well as transverse) structures that help snowplow and accelerate charged particles. The sustained large flux of photons maintains the acceleration by successive flux to repeat the process once a particular class of photons give up energies to particles and red-shift. The decrease of plasma density away from the GRB further facilitates this process, providing ever greater coherence (acceleration) length. The stochastic repetition of this process yields a power-law energy spectrum with an exponent of -1. Such compact prompt intense acceleration of protons in the vicinity of GRB manifests through neutrinos (by proton-proton or proton-photon collisions near GRB). These neutrinos can propagate over a cosmological distance without decay or loss until reaching and colliding with relic neutrinos in our Super-Cluster (Virgo), eventually converting themselves into EECR particles such as protons and photons of energies of ~ 10^20 eV. The estimated neutrino energy flux and spectrum are consistent with observation and have a number of implications on EHECR, cosmological origin, and neutrino physics. Other high field astronomical sites such as the core and jets of Active Galactic Nuclei can have lesser but similar accelerations.

Takahashi, Yoshiyuki

2000-04-01

340

Progress on laser plasma accelerators  

SciTech Connect

Several laser plasma accelerator schemes are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA). Theory indicates that a very high acceleration gradient, of order 1 GeV/m, can exist in the plasma wave driven by the beating lasers. Experimental results obtained on the PBWA experiment at UCLA confirms this. Parameters related to the PBWA as an accelerator system are derived, among them issues concerning the efficiency and the laser power and energy requirements are discussed.

Chen, P.

1986-04-01

341

Incidence of cyclical bleeding after laparoscopic supracervical hysterectomy  

Microsoft Academic Search

Study objectiveThe aim of the study was to estimate the incidence of cyclical bleeding after laparoscopic supracervical hysterectomy (LSH) when the uterus is amputated at or below the level of internal cervical os.

Ali Ghomi; Jeff Hantes; E. C. Lotze

2005-01-01

342

Mathematical Model for Predicting Cyclic Voltammograms of Electronically Conductive Polypyrrole.  

National Technical Information Service (NTIS)

Polypyrrole is an attractive polymer for use as a high-energy-density secondary battery because of its potential as an inexpensive, lightweight, and noncorrosive electrode material. A mathematical model to simulate cyclic voltammograms for polypyrrole is ...

T. Yeu T. V. Nguyen R. E. White

1987-01-01

343

Circadian Rhythms in Catecholamine Metabolites and Cyclic Nucleotide Production.  

National Technical Information Service (NTIS)

Circadian rhythms in noradrenergic (NE) and dopaminergic (DA) metabolites and in cyclic nucleotide production were measured in discrete regions of rat brain. A circadian rhythm was found in the concentration of the NE metabolite, 3-methoxy-4-hydroxyphenyl...

M. S. Kafka M. A. Benedito R. H. Roth L. K. Steele W. W. Wolfe

1986-01-01

344

Production of Reactive Oxygen Species by Polyhalogenated Cyclic Hydrocarbons (PCH).  

National Technical Information Service (NTIS)

The results of this research strongly support the hypothesis that polyhalogenated cyclic hydrocarbons (PCH) induce production of reactive oxygen species which may contribute to many of the toxic manifestations associated with these xenobiotics. A non-inva...

S. J. Stohs

1992-01-01

345

Life Prediction Modeling Based on Cyclic Damage Accumulation.  

National Technical Information Service (NTIS)

A high temperature, low cycle fatigue life prediction method was developed. This method, Cyclic Damage Accumulation (CDA), was developed for use in predicting the crack initiation lifetime of gas turbine engine materials, where initiation was defined as a...

R. S. Nelson

1988-01-01

346

Cyclic Inelastic Deformation and Fatigue Life Behaviour of Notched Components.  

National Technical Information Service (NTIS)

Cyclic inelastic deformation response and fatigue notch factor are presented and discussed for two metals of contrasting stress-strain behaviour (an aluminum alloy 2024-T351 and a mild steel SAE 1015). Thin circular or elliptical notched plates fabricated...

B. N. Leis C. V. B. Gowda T. H. Topper

1974-01-01

347

Cyclic Voltammetry of Polysulfide (Thiokol) Prepolymers and Related Compounds.  

National Technical Information Service (NTIS)

The cyclic voltammetry of polysulfide prepolymers and related monomeric sulfur compounds was examined at a gold wire electrode. Electrode processes were assigned to the polysulfide prepolymers on the basis of those occurring in the model compounds. It was...

W. Mazurek

1983-01-01

348

7 CFR 1412.53 - Counter-cyclical payment provisions.  

Code of Federal Regulations, 2012 CFR

...AND COUNTER-CYCLICAL PROGRAM AND AVERAGE CROP REVENUE ELECTION PROGRAM FOR THE 2008 AND SUBSEQUENT CROP YEARS Financial Considerations Including...Secretary, or (ii) For the 2008 and 2009 crop years the following rates: (A)...

2012-01-01

349

Evaluation of Cyclic Behavior of Aircraft Turbine Disk Alloys.  

National Technical Information Service (NTIS)

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 fo...

H. G. Pop V. Shahani

1978-01-01

350

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

351

Accelerator research studies  

NASA Astrophysics Data System (ADS)

The Accelerator Research Studies program at the University of Maryland, sponsored by the Department of Energy under grant number DE-FG05-91ER-40642, is currently in the first year of a three-year funding cycle. The program consists of the following three tasks: TASK 1, Study of Transport and Longitudinal Compression of Intense, High-Brightness Beams; TASK 2, Study of Collective Ion Acceleration by Intense Electron Beams and Pseudospark Produced High Brightness Electron Beams; TASK 3, Study of a Gyroklystron High-power Microwave Source for Linear Colliders. In this report we document the progress that has been made during the past year for each of the three tasks.

352

D-2 acceleration characterization  

NASA Astrophysics Data System (ADS)

During the second German Spacelab Mission D-2, extensive onboard measurements of the residual acceleration were performed. The payload was equipped with accelerometer packages distributed over the entire Spacelab module. The microgravity measurement assembly (MMA) was the core system comprising fixed mounted as well as mobile sensor packages. Additional autonomous accelerometer systems were mounted within the payload elements MEDEA and Werkstofflabor. On-board video recording has been performed to correlate the measured accelerations to mission events. The D-2 microgravity characterization program also included numerical calculations to predict low frequency effects due to atmospheric drag, tidal force, and spacecraft rotation. Results of characteristic quiet mission phases show that the microgravity level is essentially below the requirements defined for the space station. Other results of some other mission phases revealed that a wealth can be done by improving payload design and operation to improve the microgravity quality of Spacelab missions.

Hamacher, Hans; Bluemel, U.

1994-07-01

353

Electron acceleration above thunderclouds  

NASA Astrophysics Data System (ADS)

The acceleration of electrons results in observable electromagnetic waves which can be used for remote sensing. Here, we make use of ˜4 Hz-66 MHz radio waves emitted by two consecutive intense positive lightning discharges to investigate their impact on the atmosphere above a thundercloud. It is found that the first positive lightning discharge initiates a sprite where electrons are accelerated during the exponential growth and branching of the sprite streamers. This preconditioned plasma above the thundercloud is subsequently exposed to a second positive lightning discharge associated with a bouncing-wave discharge. This discharge process causes a re-brightening of the existing sprite streamers above the thundercloud and initiates a subsequent relativistic electron beam.

Füllekrug, Martin; Kolmasova, Ivana; Santolik, Ondrej; Farges, Thomas; Bór, József; Bennett, Alec; Parrot, Michel; Rison, William; Zanotti, Ferruccio; Arnone, Enrico; Mezentsev, Andrew; Lan, Radek; Uhlir, Ludek; Harrison, Giles; Soula, Serge; van der Velde, Oscar; Pinçon, Jean-Louis; Helling, Christiane; Diver, Declan

2013-09-01

354

Electron acceleration above thunderclouds  

NASA Astrophysics Data System (ADS)

The acceleration of electrons results in observable electromagnetic waves which can be used for remote sensing. Here, we make use of ?4 Hz–66 MHz radio waves emitted by two consecutive intense positive lightning discharges to investigate their impact on the atmosphere above a thundercloud. It is found that the first positive lightning discharge initiates a sprite where electrons are accelerated during the exponential growth and branching of the sprite streamers. This preconditioned plasma above the thundercloud is subsequently exposed to a second positive lightning discharge associated with a bouncing-wave discharge. This discharge process causes a re-brightening of the existing sprite streamers above the thundercloud and initiates a subsequent relativistic electron beam.

Füllekrug, Martin; Kolmasova, Ivana; Santolik, Ondrej; Farges, Thomas; Bór, József; Bennett, Alec; Parrot, Michel; Rison, William; Zanotti, Ferruccio; Arnone, Enrico; Mezentsev, Andrew; Lan, Radek; Uhlir, Ludek; Harrison, Giles; Soula, Serge; van der Velde, Oscar; Pinçon, Jean-Louis; Helling, Christiane; Diver, Declan

2013-09-01

355

Photon acceleration from rest  

SciTech Connect

In this paper we present a new mechanism for generating coherent radiation from a laser-ionized gas-filled capacitor array. The scheme directly converts a static electric field of wave number {ital k}{sub 0} into coherent radiation pulses. The physical mechanism is analogous to photon acceleration in plasma waves, and in this sense, photons are accelerated from zero frequency (zero energy) to a frequency {omega}{sup 2}{sub {ital p}}/2{ital k}{sub 0}{ital c}. The frequency (energy) of the photons is controlled by the gas pressure and/or capacitor spacing and has broad tunability over several orders of magnitude. We calculate the output frequency and power and compare theoretical predictions to 2D PIC simulations. {copyright} 1995 {ital American Institute of Physics}.

Katsouleas, T.; Lai, C.H. [Department of Electrical Engineering-Electrophysics, University of Southern California Los Angeles, California 90089 (United States); Dawson, J.M.; Mori, W.B. [UCLA Department of Electrical Engineering, Los Angeles, California 90024 (United States)

1995-06-01

356

Accelerator research studies  

SciTech Connect

The Accelerator Research Studies program at the University of Maryland, sponsored by the Department of Energy under grant number DE-FG05-91ER40642, is currently in the second year of a three-year funding cycle. The program consists of the following three tasks: TASK A, Study of Transport and Longitudinal Compression of Intense, High-Brightness Beams,'' (P.I., M. Reiser); TASK B, Study of Collective Ion Acceleration by Intense Electron Beams and Pseudospark Produced High Brightness Electron Beams,'' (Co-P.I.'s, W.W. Destler, M. Reiser, M.J. Rhee, and C.D. Striffler); TASK C, Study of a Gyroklystron High-Power Microwave Source for Linear Colliders,'' (Co-P.I.'s, V.L. Granatstein, W. Lawson, M. Reiser, and C.D. Striffler). In this report we document the progress that has been made during the past year for each of the three tasks.

Not Available

1993-01-01

357

Self-Accelerated Universe  

NASA Astrophysics Data System (ADS)

It is widely believed that the large redshifts for distant supernovae are due to the vacuum energy dominance, which is responsible for the anti-gravitation effect. A tacit assumption is that particles move along geodesics for the background metric. This is in the same spirit as the consensus regarding the uniform Galilean motion of a free electron. However, apart from the Galilean solution, there is a self-accelerated solution to the Lorentz-Dirac equation governing the behavior of a radiating electron. Likewise, a runaway solution to the entire system of equations, both gravitation and matter equations of motion including, may exist, which provides an alternative explanation for the accelerated expansion of the Universe.

Kosyakov, B. P.

358

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

359

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

360

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

361

Accelerator research studies  

SciTech Connect

The Accelerator Research Studies program at the University of Maryland, sponsored by the Department of Energy under grant number DE-FG05-91ER40642, is currently in the first year of a three-year funding cycle. The program consists of the following three tasks: TASK A, Study of Transport and Longitudinal Compression of Intense, High-Brightness Beams, TASK B, Study of Collective Ion Acceleration by Intense Electron Beams and Pseudospark Produced High Brightness Electron Beams; TASK C, Study of a Gyroklystron High-power Microwave Source for Linear Colliders. In this report we document the progress that has been made during the past year for each of the three tasks.

Not Available

1992-01-01

362

Advanced medical accelerator design  

SciTech Connect

This report describes the design of an advanced medical facility dedicated to charged particle radiotherapy and other biomedical applications of relativistic heavy ions. Project status is reviewed and some technical aspects discussed. Clinical standards of reliability are regarded as essential features of this facility. Particular emphasis is therefore placed on the control system and on the use of technology which will maximize operational efficiency. The accelerator will produce a variety of heavy ion beams from helium to argon with intensities sufficient to provide delivered dose rates of several hundred rad/minute over large, uniform fields. The technical components consist of a linac injector with multiple PIG ion sources, a synchrotron and a versatile beam delivery system. An overview is given of both design philosophy and selected accelerator subsystems. Finally, a plan of the facility is described.

Alonso, J.R.; Elioff, T.; Garren, A.

1982-11-01

363

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

364

Future accelerators and experiments  

SciTech Connect

This article describes the status of major new accelerator projects and prospects as of mid 1988. It looks at hadron colliders and electron positron colliders. The author looks both at the technology of the machines, and how it will have to be developed for future devices, and the effort required to extract the important physics information from the resulting reaction cascades which are exected to come out of these devices.

Richter, B.

1993-08-01

365

Frontiers of accelerator instrumentation  

SciTech Connect

New technology has permitted significant performance improvements of established instrumentation techniques including beam position and profile monitoring. Fundamentally new profile monitor strategies are required for the next generation of accelerators, especially linear colliders (LC). Beams in these machines may be three orders of magnitude smaller than typical beams in present colliders. In this paper we review both the present performance levels achieved by conventional systems and present some new ideas for future colliders.

Ross, M.

1992-08-01

366

Accelerated plate tectonics.  

PubMed

The concept of a stressed elastic lithospheric plate riding on a viscous asthenosphere is used to calculate the recurrence interval of great earthquakes at convergent plate boundaries, the separation of decoupling and lithospheric earthquakes, and the migration pattern of large earthquakes along an arc. It is proposed that plate motions accelerate after great decoupling earthquakes and that most of the observed plate motions occur during short periods of time, separated by periods of relative quiescence. PMID:17799689

Anderson, D L

1975-03-21

367

Photonic Acceleration in Astrophysics  

Microsoft Academic Search

Gamma Ray Bursts (GRB) deliver very high intensity photons with energies from 10 keV to over 100 MeV at a irradiance of 10^30 (30 km\\/R)^2 Watt\\/cm^2. This is in the nonlinear QED regime and the induced wakefield is close to the Schwinger field (E ~^16 V\\/cm). Protons and electrons can be accelerated in such a strong field to 10^21 eV\\/km

Yoshiyuki Takahashi

2000-01-01

368

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

369

New techniques for particle accelerators  

SciTech Connect

A review is presented of the new techniques which have been proposed for use in particle accelerators. Attention is focused upon those areas where significant progress has been made in the last two years--in particular, upon two-beam accelerators, wakefield accelerators, and plasma focusers. 26 refs., 5 figs., 1 tab.

Sessler, A.M.

1990-06-01

370

Accelerator operation management using objects  

Microsoft Academic Search

Conflicts over control of shared devices or resources in an accelerator control system, and problems that can occur due to applications performing conflicting operations, are usually resolved by accelerator operators. For these conflicts to be detected by the control system, a model of accelerator operation must be available to the system. We present a design for an operation management system

H. Nishimura; C. Timossi; M. Valdez

1995-01-01

371

Superconducting cavities for particle accelerators  

Microsoft Academic Search

RF Superconductivity has become an important technology for particle accelerators for high energy physics, nuclear physics, and free electron lasers. More than 100 MVolts of Superconducting RF (SRF) cavities have been installed in accelerators for heavy ions and operated at gradients of 2-3 MV\\/m in excess of 105 hours. More than 500 MVolts are installed in electron accelerators and operated

H. Padamsee

1992-01-01

372

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

373

Cyclic Diguanylate Regulates Vibrio cholerae Virulence Gene Expression  

Microsoft Academic Search

The cyclic dinucleotide second messenger cyclic diguanylate (c-diGMP) has been implicated in regulation of cell surface properties in several bacterial species, including Vibrio cholerae. Expression of genes required for V. cholerae biofilm formation is activated by an increased intracellular c-diGMP concentration. The response regulator VieA, which contains a domain responsible for degradation of c-diGMP, is required to maintain a low

Anna D. Tischler; Andrew Camilli

2005-01-01

374

Cyclic stress–strain response of textured Zircaloy4  

Microsoft Academic Search

In this paper, the cyclic stress–strain response of textured Zircaloy-4 is investigated at room temperature in an incremental step test using fully reversed tension–compression loading under strain control. The material exhibits an asymmetry of stress response in both rolling and transverse directions, and the corresponding cyclic stress–strain curves can be expressed by a power law relation. Furthermore, phenomenological friction and

Cong Li; Shihao Ying; Baoluo Shen; Shaoyu Qiu; Xuyu Ling; Yanfeng Wang; Qian Peng

2003-01-01

375

Constitutive modeling of metals under nonproportional cyclic loading  

Microsoft Academic Search

A two-surface kinematic hardening model for the stress-strain response of metals under nonproportional tension-torsion cyclic loading is developed and verified with critical experiments. In this model, both the yield and limit surfaces are assumed to be ellipses in the two-dimensional stress plane to account for anisotropic cyclic hardening. Areas of the yield and limit surfaces are changed in order to

S. H. Doong; D. F. Socie

1991-01-01

376

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

377

Creep and damage accumulation in orthotropic composites under cyclic loading  

Microsoft Academic Search

Experimental results and theoretical prediction of the response of glassfiber-reinforced polyester under quasi-static, static (creep), and cyclic (fatigue) loading are presented. The nonlinear strain component at static loading and the strain amplitude rate at cyclic off-axis loading of an orthotropic composite are shown to follow the associated flow rule with a single-parameter quadratic potential function. The influence of fatigue damage

V. Tamužs; J. Andersons; K. Aniskevich; J. Jansons; J. Korsgaard

1998-01-01

378

Cyclic creep and anelastic relaxation analysis of an ODS superalloy  

Microsoft Academic Search

This paper documents the effect of stress and temperature on the cyclic minimum strain rate at two different loading frequencies\\u000a for the oxide dispersion strengthened (ODS) superalloy, INCONEL* MA 6000. The apparent stress exponent and activation energy\\u000a for cyclic creep at both frequencies studied are shown to be greater than values observed for static creep. The large values\\u000a of the

Vincent C. Nardone; William L. Kimmerle; John K. Tien

1986-01-01

379

Modulation of human cutaneous reflexes during rhythmic cyclical arm movement  

Microsoft Academic Search

The organization and pattern of cutaneous reflex modulation is unknown during rhythmic cyclical movements of the human upper\\u000a limbs. On the assumption that these cyclic arm movements are central pattern generator (CPG) driven as has been suggested\\u000a for leg movements such as walking, we hypothesized that cutaneous reflex amplitude would be independent of electromyographic\\u000a (EMG) muscle activation level during rhythmic

E. Paul Zehr; Romeo Chua

2000-01-01

380

Asymmetrical trajectory formation in cyclic forearm movements in man  

Microsoft Academic Search

Predictions of the minimum-jerk model for a human cyclic motion were given in terms of asymmetry in movement trajectories. A detailed kinematic analysis of cyclic forearm motion, i.e., extension\\/flexion movements around the elbow joint in a horizontal plane ranging in frequency from 2–5.5 Hz, was made to examine the validity of the predictions. The kinematics of the trajectories were described

H. Nagasaki

1991-01-01

381

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

382

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

2011-10-20

383

Cell accelerated cryoablation simulation.  

PubMed

Tumor cryoablation is a clinical procedure where supercooled probes are used to destroy cancerous lesions. Cryoablation is a safe and effective palliative treatment for skeletal metastases, providing immediate and long term pain relief, increasing mobility and improving quality of life. Ideally, lesions are encompassed by an ice ball and frozen to a sufficiently low temperature to ensure cell death. "Lethal ice" is the term used to describe regions within the ice ball where cell death occurs. Failure to achieve lethal ice in all portions of a lesion may explain the high recurrence rate currently observed. Tracking growth of lethal ice is critical to success of percutaneous ablations, however, no practical methods currently exist for non-invasive temperature monitoring. Physicians lack planning tools which provide accurate estimation of the ice formation. Simulation of ice formation, while possible, is computationally demanding and too time consuming to be of clinical utility. We developed the computational framework for the simulation, acceleration strategies for multicore Intel x86 and IBM Cell architectures, and performed preliminary validation of the simulation. Our results demonstrate that the streaming SIMD implementation has better performance and scalability. Both accelerated and non-accelerated algorithms demonstrate good agreement between simulation and manually identified ice ball boundaries in phantom and patient images. Our results show promise for the development of novel cryoablation planning tools with real-time monitoring capability for clinical use. PMID:19854531

Blezek, Daniel J; Carlson, David G; Cheng, Lionel T; Christensen, Jared A; Callstrom, Matthew R; Erickson, Bradley J

2009-10-24

384

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

385

ACCELERATION INTEGRATING MEANS  

DOEpatents

An acceleration responsive device is described. A housing has at one end normally open electrical contacts and contains a piston system with a first part of non-magnetic material having metering orifices in the side walls for forming an air bearing between it and the walls of the housing; this first piston part is normally held against the other end of the housing from the noted contacts by a second piston or reset part. The reset part is of partly magnetic material, is separable from the flrst piston part, and is positioned within the housing intermediate the contacts and the first piston part. A magnet carried by the housing imposes a retaining force upon the reset part, along with a helical compression spring that is between the reset part and the end with the contacts. When a predetermined acceleration level is attained, the reset part overcomes the bias or retaining force provided by the magnet and the spring'' snaps'' into a depression in the housing adjacent the contacts. The first piston part is then free to move toward the contacts with its movement responsive tc acceleration forces and the metering orifices. (AEC)

Wilkes, D.F.

1961-08-29

386

Effect of Cyclic Precalcification of Nanotubular TiO 2 Layer on the Bioactivity of Titanium Implant.  

PubMed

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 80°C and saturated Ca(OH)2 solution at 100°C 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

2013-08-29

387

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 80°C and saturated Ca(OH)2 solution at 100°C 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.

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

2013-01-01

388

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.

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

2011-01-01

389

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

390

Role of nitrogen in the cyclic deformation behavior of duplex stainless steels  

Microsoft Academic Search

The role of nitrogen in the cyclic deformation behavior of duplex stainless steels (DSS) has been studied under fully reversed total-strain amplitude. The cyclic hardening-softening curves show that cyclic stress levels become lower with increasing nitrogen content. The cyclic softening becomes more evident with increasing nitrogen content. It can be attributed to the greater strength of austenite than that of

Hyong Jik Lee; Chong Soo Lee; Young Won Chang

2005-01-01

391

Detection of nonstationarities in geological time series: Wavelet transform of chaotic and cyclic sequences  

Microsoft Academic Search

Wavelet analysis is used to detect and localize unconformities, events, or chaotic and periodic-cyclic sequences in marine sedimentary successions. Computer modeling using a single nonlinear algorithm provides a quantitative approach to a better understanding of chaotic, cyclic and monotonous sedimentation, and the preservation of unconformities. To model cyclic and chaotic sequences, we consider nonlinear and cyclic fluctuations in the rate

Andreas Prokoph; Franz Barthelmes

1996-01-01

392

Effects of ethanol–unleaded gasoline blends on cyclic variability and emissions in an SI engine  

Microsoft Academic Search

One important design goal for spark-ignited engines is to minimize cyclic variability. A small amount of cyclic variability (slow burns) can produce undesirable engine vibrations. On the other hand, a larger amount of cyclic variability (incomplete burns) leads to an increase in hydrocarbon consumption and emissions. This paper investigates the effects of using ethanol–unleaded gasoline blends on cyclic variability and

M. A. Ceviz; F. Yüksel

2005-01-01

393

Cyclic adenosine monophosphate (cAMP)-specific phosphodiesterase is functional in bovine mammary gland  

Microsoft Academic Search

Previous studies have shown that using nonspecific phosphodiesterase (PDE) inhibitors such as caffeine improved milk production, supporting the premise that modulation of intracellular concentration of cyclic nu- cleotides (cyclic AMP, cyclic guanosine 3'-5'-monophos- phate) is involved. Intracellular cyclic nucleotides are degraded by the PDE enzyme family. The contribution of type IV PDE (PDE4) in the secretion of casein has been

V. Dostaler-Touchette; F. Bédard; C. Guillemette; F. Pothier; P. Y. Chouinard; F. J. Richard

2009-01-01

394

Dynamic unconfined compression of articular cartilage under a cyclic compressive load  

Microsoft Academic Search

To study the effect of dynamic mechanical force on cartilage metabolism, many investigators have applied a cyclic compressive load to cartilage disc explants in vitro. The most frequently used in vitro testing protocol has been the cyclic unconfined compression of articular cartilage in a bath of culture medium. Cyclic compression has been achieved by applying either a prescribed cyclic displacement

J. K. Suh

1996-01-01

395

Effects of Laboratory Heating, Cyclic Pore Pressure, and Cyclic Loading on Fracture Properties of Asphalt Mixture. Summary.  

National Technical Information Service (NTIS)

In this project, researchers evaluated several laboratory conditioning procedures on granite, limestone, and/or hydrated lime mixtures. They investigated three procedures, alone and in combinations - heat oxidation conditioning (HOC), cyclic pore pressure...

C. Kho G. Lopp J. Zou M. Isola R. Roque S. Chun

2012-01-01

396

Regulation of cyclic GMP, cyclic AMP and lactate dehydrogenase by putative neurotransmitters in the C6 rat glioma cell line  

Microsoft Academic Search

In C6 cells norepinephrine and dopamine caused transient increases in cyclic GMP and cyclic AMP, as well as an induction of lactate dehydrogenase. All of these responses were blocked by l-propranolol, suggesting mediation by a ..beta..-receptor. Phentolamine potentiated the NE-increased cAMP levels by 5-fold when NE was used at suboptimal doses, suggesting the presence of ..cap alpha..-adrenergic receptors in C6

Jane E. Bottenstein; Jean de Vellis

1978-01-01

397

Regulation of cyclic GMP, cyclic amp and lactate dehydrogenase by putative neutrotransmitters in the C6 rat glioma cell line  

Microsoft Academic Search

In C6 cells norepinephrine and dopamine caused transient increases in cyclic GMP and cyclic AMP, as well as an induction of lactate dehydrogenase. All of these responses were blocked by 1-propranolol, suggesting mediation by a ..beta..-receptor. Phentolamine potentiated the NE-increased cAMP levels by 5-fold when NE was used at suboptimal doses, suggesting the presence of ..cap alpha..-adrenergic receptors in C6

J. E. Bottenstein; J. de Vellis

1977-01-01

398

The Characteristics of Cyclical and Non-Cyclical Mastalgia: A Prospective Study using a Modified McGill Pain Questionnaire  

Microsoft Academic Search

Breast pain (mastalgia) is a common condition (usually classified as cyclical or non-cyclical) the characteristics of which have never been studied using a standardized pain instrument. We have modified the short form of the McGill Pain Questionnaire (SF-MPQ) for the measurement of mastalgia, and have administered it to 271 women with breast pain and without breast cancer. The mean pain-rating

Seema A. Khan; A. Vania Apkarian

2002-01-01

399

Recent Advances in Plasma Acceleration  

ScienceCinema

The costs and the time scales of colliders intended to reach the energy frontier are such that it is important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators a drive beam, either laser or particle, produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultra-high accelerating fields over a substantial length to achieve a significant energy gain. More than 42 GeV energy gain was achieved in an 85 cm long plasma wakefield accelerator driven by a 42 GeV electron drive beam in the Final Focus Test Beam (FFTB) Facility at SLAC. Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of {approx}52 GV/m. This effectively doubles their energy, producing the energy gain of the 3 km long SLAC accelerator in less than a meter for a small fraction of the electrons in the injected bunch. Prospects for a drive-witness bunch configuration and high-gradient positron acceleration experiments planned for the SABER facility will be discussed.

400

Muon Acceleration - RLA and FFAG  

SciTech Connect

Various acceleration schemes for muons are presented. The overall goal of the acceleration systems: large acceptance acceleration to 25 GeV and 'beam shaping' can be accomplished by various fixed field accelerators at different stages. They involve three superconducting linacs: a single pass linear Pre-accelerator followed by a pair of multi-pass Recirculating Linear Accelerators (RLA) and finally a non-scaling FFAG ring. The present baseline acceleration scenario has been optimized to take maximum advantage of appropriate acceleration scheme at a given stage. The solenoid based Pre-accelerator offers very large acceptance and facilitates correction of energy gain across the bunch and significant longitudinal compression trough induced synchrotron motion. However, far off-crest acceleration reduces the effective acceleration gradient and adds complexity through the requirement of individual RF phase control for each cavity. The RLAs offer very efficient usage of high gradient superconducting RF and ability to adjust path-length after each linac pass through individual return arcs with uniformly periodic FODO optics suitable for chromatic compensation of emittance dilution with sextupoles. However, they require spreaders/recombiners switchyards at both linac ends and significant total length of the arcs. The non-scaling Fixed Field Alternating Gradient (FFAG) ring combines compactness with very large chromatic acceptance (twice the injection energy) and it allows for large number of passes through the RF (at least eight, possibly as high as 15).

Alex Bogacz

2011-10-01

401

Recent Advances in Plasma Acceleration  

SciTech Connect

The costs and the time scales of colliders intended to reach the energy frontier are such that it is important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators a drive beam, either laser or particle, produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultra-high accelerating fields over a substantial length to achieve a significant energy gain. More than 42 GeV energy gain was achieved in an 85 cm long plasma wakefield accelerator driven by a 42 GeV electron drive beam in the Final Focus Test Beam (FFTB) Facility at SLAC. Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of {approx}52 GV/m. This effectively doubles their energy, producing the energy gain of the 3 km long SLAC accelerator in less than a meter for a small fraction of the electrons in the injected bunch. Prospects for a drive-witness bunch configuration and high-gradient positron acceleration experiments planned for the SABER facility will be discussed.

Hogan, Mark

2007-03-19

402

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

403

Ca2+ Current is Regulated by Cyclic GMP-Dependent Protein Kinase in Mammalian Cardiac Myocytes  

Microsoft Academic Search

Regulation of cardiac contraction by neurotransmitters and hormones is often correlated with regulation of the L-type Ca2+-channel current (ICa) through the opposite actions of two second messengers, cyclic AMP and cyclic GMP. While cyclic AMP stimulation of ICa is mediated by the activation of cyclic AMP-dependent protein kinase, inhibition of ICa by cyclic GMP in frog heart is largely mediated

Pierre-Francois Mery; Suzanne M. Lohmann; Ulrich Walter; Rodolphe Fischmeister

1991-01-01

404

Reduction of cyclic AMP levels by light and by cone degeneration  

Microsoft Academic Search

Dark-adapted retinas or whole eyes of 13-line ground squirrels (Citellus tridecemlineatus) and western fence lizards (Sceloporus occidentalis) contain higher levels of cyclic AMP than of cyclic GMP. In these cone-dominant retinas, light reduces cyclic AMP content selectively. Freezing of dark- or light-adapted retinas or eyes also reduces cyclic AMP content, with only minimal changes in cyclic GMP levels. In addition,

Debora B. Farber; Dennis W. Souza; David G. Chase; Richard N. Lolley

405

VLHC accelerator physics  

SciTech Connect

A six-month design study for a future high energy hadron collider was initiated by the Fermilab director in October 2000. The request was to study a staged approach where a large circumference tunnel is built that initially would house a low field ({approx}2 T) collider with center-of-mass energy greater than 30 TeV and a peak (initial) luminosity of 10{sup 34} cm{sup -2}s{sup -1}. The tunnel was to be scoped, however, to support a future upgrade to a center-of-mass energy greater than 150 TeV with a peak luminosity of 2 x 10{sup 34} cm{sup -2} sec{sup -1} using high field ({approx} 10 T) superconducting magnet technology. In a collaboration with Brookhaven National Laboratory and Lawrence Berkeley National Laboratory, a report of the Design Study was produced by Fermilab in June 2001. 1 The Design Study focused on a Stage 1, 20 x 20 TeV collider using a 2-in-1 transmission line magnet and leads to a Stage 2, 87.5 x 87.5 TeV collider using 10 T Nb{sub 3}Sn magnet technology. The article that follows is a compilation of accelerator physics designs and computational results which contributed to the Design Study. Many of the parameters found in this report evolved during the study, and thus slight differences between this text and the Design Study report can be found. The present text, however, presents the major accelerator physics issues of the Very Large Hadron Collider as examined by the Design Study collaboration and provides a basis for discussion and further studies of VLHC accelerator parameters and design philosophies.

Michael Blaskiewicz et al.

2001-11-01

406

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.

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

407

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

408

Laser plasma accelerators  

SciTech Connect

This review article highlights the tremendous evolution of the research on laser plasma accelerators which has, in record time, led to the production of high quality electron beams at the GeV level, using compact laser systems. I will describe the path we followed to explore different injection schemes and I will present the most significant breakthrough which allowed us to generate stable, high peak current and high quality electron beams, with control of the charge, of the relative energy spread and of the electron energy.

Malka, V. [Laboratoire d'Optique Appliquee, ENSTA-ParisTech, CNRS, Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France)

2012-05-15

409

Kinematics: Speed, Velocity & Acceleration  

NSDL National Science Digital Library

The following resource is a NFL sponsored, National Science Foundation funded program intended to teach students about scientific concepts by using the popular sport of Football. Each lesson is accompanied by an informative and fast paced video. In this lesson, students will explore kinematics on the playing field. NSF-funded scientists Tony Schmitz from the University of Florida and John Ziegert of Clemson University explain how the kinematic concepts of position, velocity and acceleration can be used to define how a running back moves.

2010-01-01

410

Thomas Jefferson National Accelerator  

NSDL National Science Digital Library

Thomas Jefferson National Accelerator Facility (Jefferson Lab) is funded by the Office of Science for the United States Department of Energy (DoE) with strong support from the City of Newport News, the Commonwealth of Virginia, and the United States Congress. As a user facility for scientists worldwide, its primary mission is to conduct basic research of the atomâÂÂs nucleus at the quark level. The page features information of different scientific programs, public connections and information on the Jefferson Lab in its working form.

2009-04-06

411

Acceleration in Weyl geometry  

NASA Astrophysics Data System (ADS)

We study homogeneous and isotropic cosmologies in a Weyl spacetime. We show that the field equations can be reduced to the Einstein equations with a two-fluid source and analyze the qualitative, asymptotic behavior of the models. Assuming an interaction of the two fluids we impose conditions so that the solutions of the corresponding dynamical system remain in the physically acceptable phase space. We show that in Weyl integrable spacetime, the corresponding scalar field acts as a phantom field and therefore, it may give rise to a late accelerated expansion of the Universe.

Miritzis, J.

2013-08-01

412

Roles of imposed cyclic strain amplitude and cyclic strain rate on the stress relaxation behaviour of pre-strained eutectic Sn3.5Ag solder joints  

Microsoft Academic Search

Purpose – To understand the roles of service-related parameters, such as imposed cyclic strain amplitude and cyclic strain rate, on the stress relaxation behaviour of eutectic Sn-Ag solder joints. Design\\/methodology\\/approach – Cyclic shear straining with associated stress relaxation at the shear strain extremes imposed was carried out on pre-strained eutectic Sn-Ag solder joints with various cyclic shear straining conditions. Results

H. Rhee; K. N. Subramanian

2006-01-01

413

Cyclic nucleotide phosphodiesterases in Drosophila melanogaster.  

PubMed

Cyclic nucleotide PDEs (phosphodiesterases) are important enzymes that regulate intracellular levels of cAMP and cGMP. In the present study, we identify and characterize novel PDEs in the genetic model, Drosophila melanogaster. The Drosophila genome encodes five novel PDE genes in addition to dunce. Predicted PDE sequences of Drosophila show highly conserved critical domains when compared with human PDEs. Thus PDE-encoding genes of D. melanogaster are CG14940-PDE1C, CG8279-PDE6beta, CG5411-PDE8A, CG32648-PDE9 and CG10231-PDE11. Reverse transcriptase-PCRs of adult tissues reveal widespread expression of PDE genes. Drosophila Malpighian (renal) tubules express all the six PDEs: Drosophila PDE1, dunce (PDE4), PDE6, PDE8, PDE9 and PDE11. Antipeptide antibodies were raised against PDE1, PDE6, PDE9 and PDE11. Verification of antibody specificity by Western blotting of cloned and expressed PDE constructs allowed the immunoprecipitation studies of adult Drosophila lysates. Biochemical characterization of immunoprecipitated endogenous PDEs showed that PDE1 is a dual-specificity PDE (Michaelis constant Km for cGMP: 15.3+/-1 microM; Km cAMP: 20.5+/-1.5 microM), PDE6 is a cGMP-specific PDE (Km cGMP: 37+/-13 microM) and PDE11 is a dual-specificity PDE (Km cGMP: 6+/-2 microM; Km cAMP: 18.5+/-5.5 microM). Drosophila PDE1, PDE6 and PDE11 display sensitivity to vertebrate PDE inhibitors, zaprinast (IC50 was 71+/-39 microM for PDE1, 0.65+/-0.015 microM for PDE6 and 1.6+/-0.5 microM for PDE11) and sildenafil (IC50 was 1.3+/-0.9 microM for PDE1, 0.025+/-0.005 microM for PDE6 and 0.12+/-0.06 microM for PDE11). We provide the first characterization of a cGMP-specific PDE and two dual-specificity PDEs in Drosophila, and show a high degree of similarity in structure and function between human and Drosophila PDEs. PMID:15673286

Day, Jonathan P; Dow, Julian A T; Houslay, Miles D; Davies, Shireen-A

2005-05-15

414

Cyclic nucleotide phosphodiesterases in Drosophila melanogaster  

PubMed Central

Cyclic nucleotide PDEs (phosphodiesterases) are important enzymes that regulate intracellular levels of cAMP and cGMP. In the present study, we identify and characterize novel PDEs in the genetic model, Drosophila melanogaster. The Drosophila genome encodes five novel PDE genes in addition to dunce. Predicted PDE sequences of Drosophila show highly conserved critical domains when compared with human PDEs. Thus PDE-encoding genes of D. melanogaster are CG14940-PDE1C, CG8279-PDE6?, CG5411-PDE8A, CG32648-PDE9 and CG10231-PDE11. Reverse transcriptase–PCRs of adult tissues reveal widespread expression of PDE genes. Drosophila Malpighian (renal) tubules express all the six PDEs: Drosophila PDE1, dunce (PDE4), PDE6, PDE8, PDE9 and PDE11. Antipeptide antibodies were raised against PDE1, PDE6, PDE9 and PDE11. Verification of antibody specificity by Western blotting of cloned and expressed PDE constructs allowed the immunoprecipitation studies of adult Drosophila lysates. Biochemical characterization of immunoprecipitated endogenous PDEs showed that PDE1 is a dual-specificity PDE (Michaelis constant Km for cGMP: 15.3±1 ?M; Km cAMP: 20.5±1.5 ?M), PDE6 is a cGMP-specific PDE (Km cGMP: 37±13 ?M) and PDE11 is a dual-specificity PDE (Km cGMP: 6±2 ?M; Km cAMP: 18.5±5.5 ?M). Drosophila PDE1, PDE6 and PDE11 display sensitivity to vertebrate PDE inhibitors, zaprinast (IC50 was 71±39 ?M for PDE1, 0.65±0.015 ?M for PDE6 and 1.6±0.5 ?M for PDE11) and sildenafil (IC50 was 1.3±0.9 ?M for PDE1, 0.025±0.005 ?M for PDE6 and 0.12±0.06 ?M for PDE11). We provide the first characterization of a cGMP-specific PDE and two dual-specificity PDEs in Drosophila, and show a high degree of similarity in structure and function between human and Drosophila PDEs.

2005-01-01

415

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.

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

2012-01-01

416

Domain vector accelerator (DVA): A query accelerator for relational operations  

Microsoft Academic Search

A fast method is described for performing relational operations and, in particular, for an equijoin between two relations that stand in a one-to-many relationship. The method is based on a bit-vector technique called domain vector acceleration (DVA). The approach to join acceleration is described and compared analytically with two other join accelerators, hybrid-hash join and join indices. Results show that

William Perrizo; James Gustafson; Daniel Thureen; David Wenberg; William Davidson

1991-01-01

417

Transverse electron resonance accelerator  

SciTech Connect

Transverse (to the velocity, v, of the particles to be accelerated) electron oscillations are generated in high (e.g. solid) density plasmas by either an electromagnetic wave or by the field of charged particles traveling parallel to v. The generating field oscillates with frequency ..omega.. = ..omega../sub p/, where ..omega../sub p/ is the plasma frequency. The plasma is confined to a sequence of microstructures with typical dimensions of d approx. = 2..pi..c/..omega../sub p/, allowing the generating fields to penetrate. Since ..omega../sub p/ is now high, the time scales, T, are correspondingly reduced. The microstructures are allowed to explode after t = T, until then they are confined by ion inertia. As a result of resonance, the electric field, E, inside the microstructures can exceed the generating field E/sub L/. The generating force is proportional to E/sub L/ (as opposed to E/sub L//sup 2/). Phase matching of particles is possible by appropriate spacing of the microstructures or by a gas medium. The generating beam travels outside the plasma, filamentation is not a problem. The mechanism is relatively insensitive to the exact shape and position of the microstructures. This device contains features of various earlier proposed acceleration mechanisms and may be considered as the limiting case of several of those for small d, T and high E.

Csonka, P.L.

1985-01-01

418

Accelerating the loop expansion  

SciTech Connect

This thesis introduces a new non-perturbative technique into quantum field theory. To illustrate the method, I analyze the much-studied phi/sup 4/ theory in two dimensions. As a prelude, I first show that the Hartree approximation is easy to obtain from the calculation of the one-loop effective potential by a simple modification of the propagator that does not affect the perturbative renormalization procedure. A further modification then susggests itself, which has the same nice property, and which automatically yields a convex effective potential. I then show that both of these modifications extend naturally to higher orders in the derivative expansion of the effective action and to higher orders in the loop-expansion. The net effect is to re-sum the perturbation series for the effective action as a systematic ''accelerated'' non-perturbative expansion. Each term in the accelerated expansion corresponds to an infinite number of terms in the original series. Each term can be computed explicitly, albeit numerically. Many numerical graphs of the various approximations to the first two terms in the derivative expansion are given. I discuss the reliability of the results and the problem of spontaneous symmetry-breaking, as well as some potential applications to more interesting field theories. 40 refs.

Ingermanson, R.

1986-07-29

419

Broadband accelerator control network  

SciTech Connect

A broadband data communications network has been implemented at BNL for control of the Alternating Gradient Synchrotron (AG) proton accelerator, using commercial CATV hardware, dual coaxial cables as the communications medium, and spanning 2.0 km. A 4 MHz bandwidth Digital Control channel using CSMA-CA protocol is provided for digital data transmission, with 8 access nodes available over the length of the RELWAY. Each node consists of an rf modem and a microprocessor-based store-and-forward message handler which interfaces the RELWAY to a branch line implemented in GPIB. A gateway to the RELWAY control channel for the (preexisting) AGS Computerized Accelerator Operating system has been constructed using an LSI-11/23 microprocessor as a device in a GPIB branch line. A multilayer communications protocol has been defined for the Digital Control Channel, based on the ISO Open Systems Interconnect layered model, and a RELWAY Device Language defined as the required universal language for device control on this channel.

Skelly, J.; Clifford, T.; Frankel, R.

1983-01-01

420

Obesity accelerates thymic aging  

PubMed Central

As the expanding obese population grows older, their successful immunologic aging will be critical to enhancing the health span. Obesity increases risk of infections and cancer, suggesting adverse effects on immune surveillance. Here, we report that obesity compromises the mechanisms regulating T-cell generation by inducing premature thymic involution. Diet-induced obesity reduced thymocyte counts and significantly increased apoptosis of developing T-cell populations. Obesity accelerated the age-related reduction of T-cell receptor (TCR) excision circle bearing peripheral lymphocytes, an index of recently generated T cells from thymus. Consistent with reduced thymopoiesis, dietary obesity led to reduction in peripheral naive T cells with increased frequency of effector-memory cells. Defects in thymopoiesis in obese mice were related with decrease in the lymphoid-primed multipotent progenitor (Lin?Sca1+Kit+ Flt3+) as well as common lymphoid progenitor (Lin?Sca1+CD117loCD127+) pools. The TCR spectratyping analysis showed that obesity compromised V-? TCR repertoire diversity. Furthermore, the obesity induced by melanocortin 4 receptor deficiency also constricted the T-cell repertoire diversity, recapitulating the thymic defects observed with diet-induced obesity. In middle-aged humans, progressive adiposity with or without type 2 diabetes also compromised thymic output. Collectively, these findings establish that obesity constricts T-cell diversity by accelerating age-related thymic involution.

Yang, Hyunwon; Youm, Yun-Hee; Vandanmagsar, Bolormaa; Rood, Jennifer; Kumar, K. Ganesh; Butler, Andrew A.

2009-01-01

421

Cyclic creep and anelastic relaxation analysis of an ODS superalloy  

NASA Astrophysics Data System (ADS)

This paper documents the effect of stress and temperature on the cyclic minimum strain rate at two different loading frequencies for the oxide dispersion strengthened (ODS) superalloy, INCONEL* MA 6000. The apparent stress exponent and activation energy for cyclic creep at both frequencies studied are shown to be greater than values observed for static creep. The large values of the stress exponent and activation energy for cyclic creep are proposed to result from anelastic strain storage delaying nonrecoverable creep during the on-load portion of the cyclic creep loading, such that the “effective stress” driving nonrecoverable creep is only a small fraction of the applied stress. In addition, the temperature dependence of the anelastic relaxation that occurs during the off-load portion of the cyclic creep loading is determined. The activation energy found for the relaxation process is equal to about one-half that for self-diffusion in nickel. A mechanism of localized climb of dislocations over the oxide dispersoids present in INCONEL MA 6000 is postulated to account for the observed activation energy of the relaxation process.

Nardone, Vincent C.; Kimmerle, William L.; Tien, John K.

1986-09-01

422

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 1–7 targeted to the androgen response element (ARE) and the estrogen response element (ERE) were synthesized in 12–17% 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 1–7 and 9–11 were determined, revealing remarkably varying levels of cytotoxicity.

2012-01-01

423

Topological chaos, braiding and bifurcation of almost-cyclic sets.  

PubMed

In certain two-dimensional time-dependent flows, the braiding of periodic orbits provides a way to analyze chaos in the system through application of the Thurston-Nielsen classification theorem (TNCT). We expand upon earlier work that introduced the application of the TNCT to braiding of almost-cyclic sets, which are individual components of almost-invariant sets [Stremler et al., "Topological chaos and periodic braiding of almost-cyclic sets," Phys. Rev. Lett. 106, 114101 (2011)]. In this context, almost-cyclic sets are periodic regions in the flow with high local residence time that act as stirrers or "ghost rods" around which the surrounding fluid appears to be stretched and folded. In the present work, we discuss the bifurcation of the almost-cyclic sets as a system parameter is varied, which results in a sequence of topologically distinct braids. We show that, for Stokes' flow in a lid-driven cavity, these various braids give good lower bounds on the topological entropy over the respective parameter regimes in which they exist. We make the case that a topological analysis based on spatiotemporal braiding of almost-cyclic sets can be used for analyzing chaos in fluid flows. Hence, we further develop a connection between set-oriented statistical methods and topological methods, which promises to be an important analysis tool in the study of complex systems. PMID:23278070

Grover, Piyush; Ross, Shane D; Stremler, Mark A; Kumar, Pankaj

2012-12-01

424

Topological chaos, braiding and bifurcation of almost-cyclic sets  

NASA Astrophysics Data System (ADS)

In certain two-dimensional time-dependent flows, the braiding of periodic orbits provides a way to analyze chaos in the system through application of the Thurston-Nielsen classification theorem (TNCT). We expand upon earlier work that introduced the application of the TNCT to braiding of almost-cyclic sets, which are individual components of almost-invariant sets [Stremler et al., ``Topological chaos and periodic braiding of almost-cyclic sets,'' Phys. Rev. Lett. 106, 114101 (2011)]. In this context, almost-cyclic sets are periodic regions in the flow with high local residence time that act as stirrers or ``ghost rods'' around which the surrounding fluid appears to be stretched and folded. In the present work, we discuss the bifurcation of the almost-cyclic sets as a system parameter is varied, which results in a sequence of topologically distinct braids. We show that, for Stokes' flow in a lid-driven cavity, these various braids give good lower bounds on the topological entropy over the respective parameter regimes in which they exist. We make the case that a topological analysis based on spatiotemporal braiding of almost-cyclic sets can be used for analyzing chaos in fluid flows. Hence, we further develop a connection between set-oriented statistical methods and topological methods, which promises to be an important analysis tool in the study of complex systems.

Grover, Piyush; Ross, Shane D.; Stremler, Mark A.; Kumar, Pankaj

2012-12-01

425

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

426

Sequences and cyclicities in the upper Rotliegende of the Netherlands  

SciTech Connect

A regional study of released well and core data from the Netherlands on- and offshore territory, performed by InterGeos, has revealed the preservation of supersequences, sequences, and short-term cyclicities in upper Rotliegende deposits. These have always been interpreted as formed in an inland basin, disconnected from marine influence. Sequences and cyclicities are reflected in vertical sections by correlatable alternations of lithofacies, which can be observed in cores and wireline logs. The lithofacies shifts, which often show a marked periodicity, are interpreted as caused by climatic fluctuations. This implies that sequence stratigraphic methods can be used also in the southern Permian basin, even though direct marine influence is dubious. Supersequences, sequences, and cyclicities each have specific applications in Rotliegende exploration. Supersequences serve best for rough regional correlation and prediction of sand and clay. Sequences are suited for detailed regional or field correlation and studies of the detailed distribution of (un) favorable lithofacies, e.g., within a field. the correlation of sequences has revealed that existing lithostratigraphy is diachronous in character. Short-term cycles can be used to make estimates of net sedimentation rates and sequence durations, because the periods of these Milankovitch cycles are known. Short-term cyclicities are preserved better in the desert red beds of the rotliegende than in coastal plain deposits such as the Carboniferous, where they are overprinted heavily by longer term cyclicities.

Kouwe, W. (InterGeos, Leiderdorp (Netherlands))

1993-09-01

427

Controlled Cyclic Stretch Bioreactor for Tissue-Engineered Heart Valves  

PubMed Central

A tissue-engineered heart valve (TEHV) represents the ultimate valve replacement, especially for juvenile patients given its growth potential. To date, most TEHV bioreactors have been developed based on pulsed flow of culture medium through the valve lumen to induce strain in the leaflets. Using a strategy for controlled cyclic stretching of tubular constructs reported previously, we developed a controlled cyclic stretch bioreactor for TEHVs that leads to improved tensile and compositional properties. The TEHV is mounted inside a latex tube, which is then cyclically pressurized with culture medium. The root and leaflets stretch commensurately with the latex, the stretching being dictated by the stiffer latex and thus controllable. Medium is also perfused through the lumen at a slow rate in a flow loop to provide nutrient delivery. Fibrin-based TEHVs prepared with human dermal fibroblasts were subjected to three weeks of cyclic stretching with incrementally increasing strain amplitude. The TEHV possessed the tensile stiffness and stiffness anisotropy of leaflets from sheep pulmonary valves and could withstand cyclic pulmonary pressures with similar distension as for a sheep pulmonary artery.

Syedain, Zeeshan H.; Tranquillo, Robert T.

2009-01-01

428

Laser acceleration and its future.  

PubMed

Laser acceleration is based on the concept to marshal collective fields that may be induced by laser. In order to exceed the material breakdown field by a large factor, we employ the broken-down matter of plasma. While the generated wakefields resemble with the fields in conventional accelerators in their structure (at least qualitatively), it is their extreme accelerating fields that distinguish the laser wakefield from others, amounting to tiny emittance and compact accelerator. The current research largely falls on how to master the control of acceleration process in spatial and temporal scales several orders of magnitude smaller than the conventional method. The efforts over the last several years have come to a fruition of generating good beam properties with GeV energies on a table top, leading to many applications, such as ultrafast radiolysis, intraoperative radiation therapy, injection to X-ray free electron laser, and a candidate for future high energy accelerators. PMID:20228616

Tajima, Toshiki

2010-01-01

429

Magnetic Insulation for Electrostatic Accelerators  

SciTech Connect

The voltage gradient which can be sustained between electrodes without electrical breakdowns is usually one of the most important parameters in determining the performance which can be obtained in an electrostatic accelerator. We have recently proposed a technique which might permit reliable operation of electrostatic accelerators at higher electric field gradients, perhaps also with less time required for the conditioning process in such accelerators. The idea is to run an electric current through each accelerator stage so as to produce a magnetic field which envelopes each electrode and its electrically conducting support structures. Having the magnetic field everywhere parallel to the conducting surfaces in the accelerator should impede the emission of electrons, and inhibit their ability to acquire energy from the electric field, thus reducing the chance that local electron emission will initiate an arc. A relatively simple experiment to assess this technique is being planned. If successful, this technique might eventually find applicability in electrostatic accelerators for fusion and other applications.

Grisham, L. R. [Princeton Plasma Physics Laboratory, P. O. Box 451, Princeton, New Jersey 08543 (United States)

2011-09-26

430

Coherent multimoded dielectric wakefield accelerators.  

SciTech Connect

There has recently been a study of the potential uses of multimode dielectric structures for wakefield acceleration [1]. This technique is based on adjusting the wakefield modes of the structure to constructively interfere at certain delays with respect to the drive bunch, thus providing an accelerating gradient enhancement over single mode devices. In this report we examine and attempt to clarify the issues raised by this work in the light of the present state of the art in wakefield acceleration.

Power, J.

1998-07-16

431

Plasma acceleration of particle beams  

SciTech Connect

Plasmas, being fully ionized gases, are immune from electrical breakdown and so can support ultra-high accelerating fields (order GeV/cm) in the form of relativistic plasma waves. Several schemes to excite these waves and use them for particle acceleration are reviewed in this article. These include the beat wave accelerator (laser driven) and the plasma wakefield transformer (particle beam driven). In addition, the possible use of plasmas to provide strong final focusing of beams (the plasma lens) is described.

Katsouleas, T.; Dawson, J. M.

1989-04-05

432

Status of the FMIT accelerator  

SciTech Connect

The linear accelerator being designed and constructed for the Fusion Materials Irradiation Test (FMIT) facility also has great utility as an R and D program that will provide operating information on large, continuous-wave, high-intensity particle accelerators now being considered for various applications, including electronuclear breeding for fuel, power, or tritium production. A 5-MeV FMIT prototype accelerator is under construction at Los Alamos, with operation to 2 MeV planned in early 1983.

Jameson, R.A.

1982-01-01

433

Modern electron accelerators for radiography  

SciTech Connect

Over the past dozen years or so there have been significant advances in electron accelerators designed specifically for radiography of hydrodynamic experiments. Accelerator technology has evolved to accomodate the radiographers' contitiuing quest for multiple images in t h e and space:, improvements in electron beam quality have resulted in smaller radiographic spot sizes for better resolution, while higher radiation do% now provides imprcwed penetration of large, dense objects. Inductive isolation and acceleration techniques have played a ley rob in these advances.

Ekdahl, C. A. (Carl A.)

2001-01-01

434

IFMIF accelerator conceptual design activities  

SciTech Connect

A Conceptual Design Evaluation (CDE) for the International Fusion Materials Irradiation Facility (IFMIF) began in 1997 and will be completed in 1998, as an international program of the IEA involving the European Community, Japan, Russia and the United States. The IFMIF accelerator system, comprising two 125 mA, 40 MeV deuterium accelerators operating at 175 MHz, is a key element of the IFMIF facility. The objectives and accomplishments of the CDE accelerator studies are outlined.

Jameson, R.A. [Los Alamos National Lab., NM (United States); Lagniel, J.M. [CEA Saclay (France); Sugimoto, M. [JAERI (Japan); Kein, H.; Piaszczyk, C.; Tiplyakov, V.

1998-12-31

435

Design of a reluctance accelerator  

SciTech Connect

Linear electromagnetic accelerators have many potential uses, in space or at-sea and industrial applications. Many of these uses require that the accelerator be exposed to hostile environments such as might be found in pace or underwater. One type of accelerator, the reluctance accelerator, has advantages in these hostile environments because its armature operates without sliding contacts or flexible cables. This device has electrical turns only in the stator. The armature consists of one or more slugs of ferromagnetic material. The reluctance accelerator exhibits the same good controllability as synchronous accelerators. They have seen little use, however, because they are relatively difficult to design. This paper describes the design of a reluctance accelerator and discusses the methods used in its design. It also discusses the methods of control of the accelerator and its predicted performance. Because this device contains iron and is therefore very nonlinear, it was necessary to employ a finite element (FEA) code (TEXMAP) in order to determine the forces developed by the accelerator and to determine the inductance of the winding at various stroke positions.

Bresie, D.A.; Andrews, J.A. (Texas Univ., Austin, TX (United States). Center for Electromechanics)

1991-01-01

436

Accelerators for research and applications  

SciTech Connect

The newest particle accelerators are almost always built for extending the frontiers of research, at the cutting edge of science and technology. Once these machines are operating and these technologies mature, new applications are always found, many of which touch our lives in profound ways. The evolution of accelerator technologies will be discussed, with descriptions of accelerator types and characteristics. The wide range of applications of accelerators will be discussed, in fields such as nuclear science, medicine, astrophysics and space-sciences, power generation, airport security, materials processing and microcircuit fabrication. 13 figs.

Alonso, J.R.

1990-06-01

437

RNA-Based Fluorescent Biosensors for Live Cell Imaging of Second Messengers Cyclic di-GMP and Cyclic AMP-GMP.  

PubMed

Cyclic dinucleotides are an important class of signaling molecules that regulate a wide variety of pathogenic responses in bacteria, but tools for monitoring their regulation in vivo are lacking. We have designed RNA-based fluorescent biosensors for cyclic di-GMP and cyclic AMP-GMP by fusing the Spinach aptamer to variants of a natural GEMM-I riboswitch. In live cell imaging experiments, these biosensors demonstrate fluorescence turn-on in response to cyclic dinucleotides, and they were used to confirm in vivo production of cyclic AMP-GMP by the enzyme DncV. PMID:23488798

Kellenberger, Colleen A; Wilson, Stephen C; Sales-Lee, Jade; Hammond, Ming C

2013-03-21

438

Cyclic tensile strain upregulates collagen synthesis in isolated tendon fascicles  

SciTech Connect

Mechanical stimulation has been implicated as an important regulatory factor in tendon homeostasis. In this study, a custom-designed tensile loading system was used to apply controlled mechanical stimulation to isolated tendon fascicles, in order to examine the effects of 5% cyclic tensile strain at 1 Hz on cell proliferation and matrix synthesis. Sample viability and gross structural composition were maintained over a 24 h loading period. Data demonstrated no statistically significant differences in cell proliferation or glycosaminoglycan production, however, collagen synthesis was upregulated with the application of cyclic tensile strain over the 24 h period. Moreover, a greater proportion of the newly synthesised matrix was retained within the sample after loading. These data provide evidence of altered anabolic activity within tendon in response to mechanical stimuli, and suggest the importance of cyclic tensile loading for the maintenance of the collagen hierarchy within tendon.

Screen, Hazel R.C. [Medical Engineering Division and IRC in Biomedical Materials, Department of Engineering, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom)]. E-mail: H.R.C.Screen@qmul.ac.uk; Shelton, Julia C. [Medical Engineering Division and IRC in Biomedical Materials, Department of Engineering, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Bader, Dan L. [Medical Engineering Division and IRC in Biomedical Materials, Department of Engineering, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Lee, David A. [Medical Engineering Division and IRC in Biomedical Materials, Department of Engineering, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom)

2005-10-21

439

Morita Base Change in Hopf-Cyclic (Co)Homology  

NASA Astrophysics Data System (ADS)

In this paper, we establish the invariance of cyclic (co)homology of left Hopf algebroids under the change of Morita equivalent base algebras. The classical result on Morita invariance for cyclic homology of associative algebras appears as a special example of this theory. In our main application we consider the Morita equivalence between the algebra of complex-valued smooth functions on the classical 2-torus and the coordinate algebra of the noncommutative 2-torus with rational parameter. We then construct a Morita base change left Hopf algebroid over this noncommutative 2-torus and show that its cyclic (co)homology can be computed by means of the homology of the Lie algebroid of vector fields on the classical 2-torus.

El Kaoutit, Laiachi; Kowalzig, Niels

2013-06-01

440

Cyclicity in the fossil record mirrors rock outcrop area  

PubMed Central

In a recent article, Rohde & Muller (Rohde & Muller 2005 Nature 434, 208–210) identified a strong 62?Myr cyclicity in the history of marine diversity through the Phanerozoic. The data they presented were highly convincing, yet they were unable to explain what process might have generated this pattern. A significant correlation between observed genus-level diversity (after removal of long-term trends) and the amount of marine sedimentary rock measured at a surface outcrop in Western Europe is demonstrated. This suggests that cyclicity originates from long-term changes in sedimentary depositional and erosional regimes, and raises the strong possibility that the cyclicity apparent in the record of marine fossils is not a biological signal but a sampling signal.

Smith, Andrew B; McGowan, Alistair J

2005-01-01

441

Development of a viscoelastic continuum damage model for cyclic loading  

NASA Astrophysics Data System (ADS)

A previously developed spectrum model for linear viscoelastic behavior of solids is used to describe the rate-dependent damage growth of a time dependent material under cyclic loading. Through the use of the iterative solution of a special Volterra integral equation, the cyclic strain history is described. The spectrum-based model is generalized for any strain rate and any uniaxial load history to formulate the damage function. Damage evolution in the body is described through the use of a rate-type evolution law which uses a pseudo strain to express the viscoelastic constitutive equation with damage. The resulting damage function is used to formulate a residual strength model. The methodology presented is demonstrated by comparing the peak values of the computed cyclic strain history as well as the residual strength model predictions to the experimental data of a polymer matrix composite.

Sullivan, R. W.

2008-12-01

442

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

443

Lectures in accelerator theory  

SciTech Connect

Lecture I deals with the behavior of particles in the nonlinear field arising from the electromagnetic interaction of colliding beams. The case treated, that of counter-rotating proton beams crossing each other at a non-zero angle, has the simple feature that the force between the beam is one dimensional. In lecture II, an analysis of the development of traveling waves on particle beams is presented. The situation studied is that of a uniform beam current in a circular accelerator and the excitation for the coherent motion is induced by the resistivity of the vacuum chamber wall. Finally, in lecture III, a description of the current accumulation process used at the proton storage rings at CERN (The ISR) is given. Particle pulses of rather low average current are injected and stored along the length and width of the vacuum chamber. The efficiency is very high and large currents (over 40 amperes) have been achieved.

Month, M

1980-01-01

444

Understanding projectile acceleration.  

PubMed

Throwing and catching balls or other objects is a generally highly practiced skill; however, conceptual as well as perceptual understanding of the mechanics that underlie this skill is surprisingly poor. In 5 experiments, we investigated conceptual and perceptual understanding of simple ballistic motion. Paper-and-pencil tests revealed that up to half of all participants mistakenly believed that a ball would continue to accelerate after it left the thrower's hand. Observers also showed a remarkable tolerance for anomalous trajectory shapes. Perceptual judgments based on graphics animations replicated these erroneous beliefs for shallow release angles. Observers' tolerance for anomalies tended to decrease with their distance from the actor. The findings are at odds with claims of the naive physics literature that liken intuitive understanding to Aristotelian or medieval physics theories. Instead, observers seem to project their intentions to the ball itself (externalization) or even feel that they have power over the ball when it is still close. PMID:10811172

Hecht, H; Bertamini, M

2000-04-01

445

The accelerating universe  

NASA Astrophysics Data System (ADS)

From keV electrons in the aurorae to Ultra High Energy Cosmic Rays in unidentified "Zevatrons", the cosmos shows a perverse, yet pervasive, proclivity to select a tiny minority of particles and boost them to high energy. The mechanisms involved can be traced back to the ideas of Faraday, Fermi and Alfvén though we are learning that the details are idiosyncratic to the many environments that we have explored. Much can be learned from comparing and contrasting particle acceleration in laboratory, interplanetary, interstellar and intergalactic locations. As it celebrates its centenary, cosmic ray physics, has assumed a new importance in solving one of the greatest problems consuming its illustrious scion - elementary particle physics - namely the nature of dark matter.

Blandford, Roger

2013-02-01

446

The SSC linear accelerator  

SciTech Connect

The SSC linear accelerator will generate a 25 mA, 600 MeV, H-beam with transverse normalized rms emittance less than 0.3 {pi} mm{center_dot}mrad in 9.6 ps pulses at a 10 Hz repetition rate. The Linac will ultimately have to operate with an availability for Collider filling in excess of 98%. In addition, the Linac will provide beams to service the Test Beams facility and may be delivering beam to a Proton Radiotherapy Facility. This paper presents an overview of the status of design, procurement, fabrication, civil construction, foreign contributions and commissioning plans, and directs the reader to additional details available in other presentations to this Conference.

Funk, L.W.

1993-05-01

447

Muon Collider Progress: Accelerators  

SciTech Connect

A muon collider would be a powerful tool for exploring the energy-frontier with leptons, and would complement the studies now under way at the LHC. Such a device would offer several important benefits. Muons, like electrons, are point particles so the full center-of-mass energy is available for particle production. Moreover, on account of their higher mass, muons give rise to very little synchrotron radiation and produce very little beamstrahlung. The first feature permits the use of a circular collider that can make efficient use of the expensive rf system and whose footprint is compatible with an existing laboratory site. The second feature leads to a relatively narrow energy spread at the collision point. Designing an accelerator complex for a muon collider is a challenging task. Firstly, the muons are produced as a tertiary beam, so a high-power proton beam and a target that can withstand it are needed to provide the required luminosity of ~1 × 10{sup 34} cm{sup –2}s{sup –1}. Secondly, the beam is initially produced with a large 6D phase space, which necessitates a scheme for reducing the muon beam emittance (“cooling”). Finally, the muon has a short lifetime so all beam manipulations must be done very rapidly. The Muon Accelerator Program, led by Fermilab and including a number of U.S. national laboratories and universities, has undertaken design and R&D activities aimed toward the eventual construction of a muon collider. Design features of such a facility and the supporting R&D program are described.

Zisman, Michael S.

2011-09-10

448

Accelerating ESL Students' Reading Progress With Accelerated Reader  

Microsoft Academic Search

This study examines the benefits of the Accelerated Reader program on ESL fourth and fifth grade students in a school in rural Western North Carolina. The study involved ten ESL fourth and fifth graders who had approximately forty-five minutes of time for free reading daily. The Accelerated Reader program was encouraged through the use of incentives. Monthly test reports were

Jeanne M. McGlinn; Amy Parrish

2002-01-01

449

DARHT II Scaled Accelerator Tests on the ETA II Accelerator.  

National Technical Information Service (NTIS)

The DARHT II accelerator at LANL is preparing a series of preliminary tests at the reduced voltage of 7.8 MeV. The transport hardware between the end of the accelerator and the final target magnet was shipped to LLNL and installed on ETA II. Using the ETA...

J. T. Weir E. M. Anaya G. J. Caporaso F. W. Chambers

2005-01-01

450

CAS CERN Accelerator School. Third advanced accelerator physics course. Proceedings.  

National Technical Information Service (NTIS)

The third version of the CERN Accelerator School's (CAS) advanced course on General Accelerator Physics was given at Uppsala University from 18-29 September, 1989. Its syllabus was based on the previous courses held in Oxford, 1985 and Berlin, 1987 whose ...

S. Turner

1990-01-01

451

CAS CERN Accelerator School: Fourth general accelerator physics course. Proceedings.  

National Technical Information Service (NTIS)

The fourth CERN Accelerator School (CAS) basic course on General Accelerator Physics was given at KFA, Juelich, from 17 to 28 September 1990. Its syllabus was based on the previous similar courses held at Gif-sur-Yvette in 1984, Aarhus 1986, and Salamanca...

S. Turner

1991-01-01

452

Cyclic Plane Strain Compression Tests on Dense Granular Materials  

NASA Astrophysics Data System (ADS)

A series of cyclic plane strain compression tests are performed under drained condition on dense Toyoura sand and compacted Chiba gravel, by using small-scale and large-scale apparatuses, respectively. Comparisons are made with results from monotonic loading tests. Local strain distributions are calculated by conducting image analyses of digital photographs taken at different stages of loading during each test. Based on these results, strain localization properties of dense granular materials are discussed, in particular focusing on possible effects of cyclic loading history.

Koseki, Junichi; Karimi, Job Munene; Tsutsumi, Yukika; Maqbool, Sajjad; Sato, Takeshi

453

Monotonic and cyclic fatigue properties of automotive aluminum alloys  

SciTech Connect

Monotonic and strain-controlled fatigue tests were conducted on 2014-T6, 6061-T6 and 7175-T73 hand-forgings, 5052-H32 and 6061-T6 sheet, and a 1983/84 production Chevrolet Corvette upper-control-arm-pivot shaft (UCAPS) cold-forged from 5454-H12 and 6061-T4 rolled rod (the 6061 UCAPS was artificially-aged to the -T6 temper, after forging). Various monotonic and cyclic fatigue stress-strain material properties are presented. The responses of the various alloys and product-forms in terms of cyclic hardening or softening are described.

Wong, W.A.

1984-01-01

454

BCYCLIC: A PARALLEL BLOCK TRIDIAGONAL MATRIX CYCLIC SOLVER  

SciTech Connect

A block tri-diagonal matrix is factored with minimal fill-in using a cyclic reduction algorithm that is easily parallelized. Storage of the factored blocks allows the application of the inverse to multiple right-hand sides which may not be known at factorization time. Scalability with the number of block rows is achieved with cyclic reduction, while scalability with the block size is achieved using multithreaded routines (OPENMP, GotoBLAS) for block matrix manipulation. This dual scalability is a noteworthy feature of this new solver, as well as its ability to handle arbitrary block row and processor numbers. Comparisons with other parallel block solvers are presented.

Hirshman, Steven Paul [ORNL; Lynch, Vickie E [ORNL; Perumalla, Kalyan S [ORNL; Sanchez, Raul [ORNL

2010-01-01

455

What does cyclicity on amplitude-integrated EEG mean?  

PubMed

In the context of amplitude-integrated electroencephalography (aEEG), the term 'sleep-wake cycling' (SWC), which is frequently used by clinicians and researchers, should be changed to 'cyclicity'. SWC is a technical term that refers to the biological pattern of alternating sleeping and waking states, which is difficult to define with only aEEG and no physical parameters. Additionally, the absence of cyclicity on aEEG is a more robust reflection of the sequence of the suppressed background patterns of an aEEG following cerebral injury or dysfunction than are sleep/wake states. PMID:22441113

Kidokoro, H; Inder, T; Okumura, A; Watanabe, K

2012-03-22

456

Mesoscale modeling of molecular machines: Cyclic dynamics and hydrodynamical fluctuations  

NASA Astrophysics Data System (ADS)

Proteins acting as molecular machines can undergo cyclic internal conformational motions that are coupled to ligand binding and dissociation events. In contrast to their macroscopic counterparts, nanomachines operate in a highly fluctuating environment, which influences their operation. To bridge the gap between detailed microscopic and simple phenomenological descriptions, a mesoscale approach, which combines an elastic network model of a machine with a particle-based mesoscale description of the solvent, is employed. The time scale of the cyclic hinge motions of the machine prototype is strongly affected by hydrodynamical coupling to the solvent.

Cressman, Andrew; Togashi, Yuichi; Mikhailov, Alexander S.; Kapral, Raymond

2008-05-01

457

Cyclic peptide alkaloids from the bark of Discaria americana.  

PubMed

The isolation and structure determination of cyclic peptide alkaloids, discarine-M and discarine-N, along with seven known cyclic peptide alkaloids, adouetine-Y', franganine, frangulanine, discarines-A, -B, -C, and -D from the root bark of Discaria americana are described. Structures were determined spectroscopically, especially using 2D NMR spectroscopic analysis. The crude methanol extract, the basic ether extract, and the alkaloids 6 and 7 also weakly inhibited growth of gram-negative and gram-positive bacteria. PMID:15081298

Giacomelli, Sandro R; Maldaner, Graciela; Gonzaga, Wellington A; Garcia, Claudia M; da Silva, Ubiratan F; Dalcol, Ionara I; Morel, Ademir F

2004-04-01

458

The Cyclic AMP Phenotype of Fragile X and Autism  

PubMed Central

Cyclic AMP (cAMP) is a second messenger involved in many processes including mnemonic processing and anxiety. Memory deficits and anxiety are noted in the phenotype of fragile X (FX), the most common heritable cause of mental retardation and autism. Here we review reported observations of altered cAMP cascade function in FX and autism. Cyclic AMP is a potentially useful biochemical marker to distinguish autism comorbid with FX from autism per se and the cAMP cascade may be a viable therapeutic target for both FX and autism.

Kelley, Daniel J; Bhattacharyya, Anita; Lahvis, Garet P; Yin, Jerry CP; Malter, Jim; Davidson, Richard J

2008-01-01

459

Metabolism of Adenosine 3?,5?-Cyclic Monophosphate and Induction of Fruiting Bodies in Coprinus macrorhizus  

PubMed Central

The adenyl cyclase and phosphodiesterase metabolizing adenosine 3?,5?-cyclic monophosphate (cyclic AMP) were detected in mycelia of strains of Coprinus macrorhizus which form fruiting bodies, but not in those of strains which do not form fruiting bodies. The adenyl cyclase synthesized cyclic AMP from adenosine triphosphate. The phosphodiesterase degr[UNK]ded cyclic AMP to adenosine-5?-monophosphate and was inhibited by adenosine-3?-monophosphate, theophylline, and caffeine. The strains which form fruiting bodies incorporated and metabolized cyclic AMP, but strains which do not form fruiting bodies did not. The possible participation of cyclic AMP in the induction of fruiting bodies is discussed.

Uno, Isao; Ishikawa, Tatsuo

1973-01-01

460

Acceleration Profile for Minimum Injury  

Microsoft Academic Search

For specified initial velocity and stopping distance, the acceleration-distance profile has a major influence on the extent of the injuries sustained by a human subject. Many trauma research and automotive and aircraft safety design considerations involve this relationship. The existence, uniqueness, and form of an acceleration profile which provides a minimum severity index are established in this paper. The profile

Robert F. Deery; David D. McNelis

1970-01-01

461

Inductively Coupled Discharge Plasma Accelerator  

Microsoft Academic Search

Summary form only given. Electromagnetic acceleration for generating an electrically neutral, high flux plasma beam and a system for carrying out this method are studied for the semiconductor etching process having no charging damage and space missions. In the capacitively coupled discharge plasma accelerator, a certain amount of electrode sputtering is inevitable from the ion bombardment flux. This causes serious

V. N. Volynets; Yu. N. Tolmachev; V. G. Pashkovsky; Jinwoo Yoo

2005-01-01

462

Ferroelectric Based Technologies for Accelerators  

Microsoft Academic Search

Ferroelectrics have unique intrinsic properties that make them extremely attractive for high-energy accelerator applications. Low loss ferroelectric materials can be used as key elements in RF tuning and phase shifting components to provide fast, electronic control. These devices are under development for different accelerator applications for the X, Ka and L-frequency bands. The exact design of these devices depends on

A. Kanareykin; E. Nenasheva; S. Kazakov; A. Kozyrev; A. Tagantsev; V. Yakovlev; C. Jing

2009-01-01

463

Laser technologies for laser accelerators  

Microsoft Academic Search

This paper presents a partial summary of work completed on a DOE contract entitled ``Laser Technologies for Laser Accelerators.'' Luminosities of 1032 cm-2 sec-1 force 1 TeV laser accelerators to be driven by ~10 MW of output laser power. Consequently, laser system efficiency, cost, and transport geometries for the optical beams are of critical importance. In this paper the laser

Dennis Lowenthal; Jack Slater

1985-01-01

464

Deconstructing the Accelerated Reader Program  

ERIC Educational Resources Information Center

|Teacher implementation of the Accelerated Reader Program is as widespread as it is diverse in terms of classroom and campus application. This manuscript highlights the findings of an informal, pilot study that examined four categories regarding the Accelerated Reader Program. The categories include: (1) assessment; (2) aesthetics and text…

Groce, Robin D.; Groce, Eric C.

2005-01-01

465

The Argument Against Accelerated Reader.  

ERIC Educational Resources Information Center

|Addresses a concern that integrating packaged technology (such as Accelerated Reader) is taking precedence over maintaining theoretically sound instructional practices. Addresses several arguments against the use and effectiveness of the Accelerated Reader program. Challenges educators to read the results and analysis of the National Assessment…

Biggers, Deborah

2001-01-01

466

Deconstructing the Accelerated Reading Program  

Microsoft Academic Search

Teacher implementation of the Accelerated Reader Program is as widespread as it is diverse in terms of classroom and campus application. This manuscript highlights the findings of an informal, pilot study that examined four categories regarding the Accelerated Reader Program. They are: 1) assessment, 2) aesthetics and text interaction, 3) motivation, and 4) book selection.

Robin D. Groce; Eric C. Groce

2005-01-01

467

Accelerator search for cosmic SIMPs  

Microsoft Academic Search

We give limits on the contribution to the cosmic dark matter density of neutral, stable, strongly interacting massive particles (SIMPs). The limits are inferred from an accelerator mass spectrometry (AMS) experiment at the Purdue Rare Isotope Measurement Laboratory (PRIME Lab). The experiment accelerated nuclei of both gold and iron. The “SIMP signal” would be discovery of nuclei of these elements

V. Teplitz; D. Javorsek; E. Fischbach; R. Mohapatra

2003-01-01

468

New directions in linear accelerators  

SciTech Connect

Current work on linear particle accelerators is placed in historical and physics contexts, and applications driving the state of the art are discussed. Future needs and the ways they may force development are outlined in terms of exciting R and D challenges presented to today's accelerator designers. 23 references, 7 figures.

Jameson, R.A.

1984-01-01

469

Natural Acceleration: Supporting Creative Trajectories  

ERIC Educational Resources Information Center

|"Natural acceleration" happens through an internal fire that burns to learn and may transcend school boundaries. Based on their passionate interests and connections with a domain, children who hunger for domain understandings outside school curricula require different types of acceleration, motivated by these interests. The lifeworks, domains,…

Cohen, LeoNora M.

2011-01-01

470

Accelerated Corrosion Expert Simulator (ACES)  

Microsoft Academic Search

This paper describes a complete vehicle corrosion simulation and modeling tool called ACES (Accelerated Corrosion Expert Simulator) that has a high degree of correlation to actual accelerated corrosion durability test (ACDT) data. The system imports existing 3-D geometric models of full vehicles. An integrity check is conducted to determine if there are missing or improper entities or properties and a

C. Thomas Savell; I. Carl Handsy; Pete Ault; Larry Thompson; Robert M. Hathaway; David A. Lamb

471

Report on accelerated corrosion studies  

Microsoft Academic Search

Sandia National Laboratories (SNL) conducted accelerated atmospheric corrosion testing for the U.S. Consumer Product Safety Commission (CPSC) to help further the understanding of the development of corrosion products on conductor materials in household electrical components exposed to environmental conditions representative of homes constructed with problem drywall. The conditions of the accelerated testing were chosen to produce corrosion product growth that

Curtis Dale Mowry; Sarah Jill Glass; Neil Robert Sorensen

2011-01-01

472

Development of an Electromagnetic Accelerator.  

National Technical Information Service (NTIS)

A hypervelocity launcher is described which can accelerate projectiles with diameters between 0.1 and 1 mm to velocities in the range of 20 km/s. This launcher was developed to simulate micrometeorid impact; and consists of a coaxial accelerator and a com...

P. Lell H. Kuczera E. Igenbergs

1978-01-01

473

On relativistic diffusive shock acceleration  

NASA Astrophysics Data System (ADS)

The efficiency of the diffusive particle acceleration in non-relativistic and relativistic astrophysical shocks is reviewed and evaluated. We dicsuss the properties of these shocks and we present Monte Carlo simulations studying the relativistic shocks efficiency in accelerating particles (i.e. protons or electrons) in astrophysical regions such as Super Novae, Active Galactic Nuclei and Gamma Ray Bursts.

Meli, A.; Mastichiadis, A.

474

Application of Accelerators in Materials Science and Technology.  

NASA Astrophysics Data System (ADS)

Use of accelerators for beam treatment is modern and perspective direction in materials research and a new effective no-waste and resource-saving process for manucfacture of materials and it's products. Application of relativistic electron beam treatment successfully compete in economy and productivity with other sources of concenrated energy, such as lasers. In principle, it permits to get also structural states of metal, which are impossible to get by methods of conventional heat treatment. Different examples of structural and phase transformations at low dose in automotive and electric, which obtain in first, and its application to technological processes is discribe. The interest and important applications of heavy ion beams is investigation of irradiation creep. The experiments carried out directly during irradiation yield completely new physical information on the nature of radiation effects in comparisation with postradiation tests. Systematic experimental investigation of radiation creep rate from frequency of cyclic irradiation have been provided, in first.

Gofman, Yury

1997-05-01

475

Cyclic GMP from the surrounding somatic cells regulates cyclic AMP and meiosis in the mouse oocyte  

PubMed Central

Summary Mammalian oocytes are arrested in meiotic prophase by an inhibitory signal from the surrounding somatic cells in the ovarian follicle. In response to luteinizing hormone (LH), which binds to receptors on the somatic cells, the oocyte proceeds to second metaphase, where it can be fertilized. Here we investigate how the somatic cells regulate the prophase-to-metaphase transition in the oocyte, and show that the inhibitory signal from the somatic cells is cGMP. Using FRET-based cyclic nucleotide sensors in follicle-enclosed mouse oocytes, we find that cGMP passes through gap junctions into the oocyte, where it inhibits the hydrolysis of cAMP by the phosphodiesterase PDE3A. This inhibition maintains a high concentration of cAMP and thus blocks meiotic progression. LH reverses the inhibitory signal by lowering cGMP levels in the somatic cells (from ?2 ?M to ?80 nM at 1 hour after LH stimulation) and by closing gap junctions between the somatic cells. The resulting decrease in oocyte cGMP (from ?1 ?M to ?40 nM) relieves the inhibition of PDE3A, increasing its activity by ?5-fold. This causes a decrease in oocyte cAMP (from ?700 nM to ?140 nM), leading to the resumption of meiosis.

Norris, Rachael P.; Ratzan, William J.; Freudzon, Marina; Mehlmann, Lisa M.; Krall, Judith; Movsesian, Matthew A.; Wang, Huanchen; Ke, Hengming; Nikolaev, Viacheslav O.; Jaffe, Laurinda A.

2009-01-01

476

Energy Stabilization of Electrostatic Accelerators  

NASA Astrophysics Data System (ADS)

Electrostatic accelerators, such as the Van de Graaf generator, are among the most established and well-developed particle accelerators. One of the key issues in the maturation of these accelerators has been the development of methods used to stabilize the energies of the particles they produce. Energy Stabilization of Electrostatic Accelerators presents a comprehensive overview of the key methods of stabilizing the energy of ions produced by electrostatic accelerators. After giving comprehensive background information on the subject, it explains the basis of high voltage generation, covering both the Van de Graaf charge transfer and the Crockcroft Walton voltage multiplier principle. This is followed by a description of the various methods used to detect the fluctuation in the energy of the accelerated ions. The later chapters describe the various ways used to stabilize the energy of the ions, gradually leading the reader to models of more complicated multi-loop stabilizers, composed from the simple models derived in the previous chapters. Some of the information on the mathematical modeling of physical phenomena applied in the stabilization has not been published before. Also featured is a whole chapter devoted to the problem of modulating the energy of the ions to a predetermined way. Energy Stabilization of Electrostatic Accelerators has been written with the accelerator designer and user in mind, but will also prove extremely useful to researchers and graduate students engaged in accelerator-based research, both pure and applied, whose interests lie in improving accelerator performance. It assumes only a basic knowledge of feedback and control system theory and Laplace transformation, which makes it readily understandable for any readers with physics and electronic engineering backgrounds.

Takács, J.

1997-12-01

477

A Fundamental Theorem on Particle Acceleration  

SciTech Connect

A fundamental theorem on particle acceleration is derived from the reciprocity principle of electromagnetism and a rigorous proof of the theorem is presented. The theorem establishes a relation between acceleration and radiation, which is particularly useful for insightful understanding of and practical calculation about the first order acceleration in which energy gain of the accelerated particle is linearly proportional to the accelerating field.

Xie, Ming

2003-05-01

478

Acceleration: Still an Option for the Gifted.  

ERIC Educational Resources Information Center

|In response to an article (Hany, 2001) discouraging the practice of acceleration through grade skipping for gifted students, this article defends acceleration as one option for gifted students, describes use of acceleration in Germany including early school entrance, individual grade skipping, acceleration in one subject, and acceleration in…

Heinbokel, Annette

2002-01-01

479

Effects of constant and cyclic heat stress on muscle metabolism and meat quality of broiler breast fillet and thigh meat.  

PubMed

This study investigated the effects of constant and cyclic heat stress on muscle metabolism and meat quality of broiler breast fillet and thigh meat from 4 to 6 wk of age. Male Arbor Acres (AA) broilers (n = 270, 4 wk old) were raised under different temperature conditions: standard (temperature was 23°C); constant high temperature (temperature was 34°C); and cyclic high temperature (temperature was 36°C from 1000 h to 1600 h and 23°C from 1600 h to 1000 h). On d 42, broilers were stunned and sampled. The results showed that chronic high temperature significantly decreased the proportion of breast muscle and significantly increased the proportion of thigh muscle (P < 0.05). The moisture concentration was significantly higher in the breast muscle of the birds exposed to constant high temperature (P < 0.05), whereas the protein content was significantly lower (P < 0.05) and fat deposition was significantly higher (P < 0.05) in the breast muscle of the birds exposed to constant or diurnal cyclic high temperature than those grown under standard temperature. The breast and thigh muscle of the birds grown under constant high temperature had significantly higher lightness, cook loss, and shear force (P < 0.05) and significantly lower initial pH (pH(i)), ultimate pH (pH(u)), and redness compared with those grown under standard temperature (P < 0.05). The pH(i), pH(u), and redness were significantly lower (P < 0.05) while the lightness and shear force were significantly higher for the breast muscle of the chickens raised under diurnal cyclic high temperature (P < 0.05) than those grown under standard temperature. In contrast, lightness and yellowness of thigh muscle were significantly higher (P < 0.05) in the chickens grown under diurnal cyclic high temperature than under standard temperature. Breast and thigh muscle of broilers exposed to constant high temperature produced higher (P < 0.05) lactic acid and pyruvate kinase activities than those exposed to the standard temperature. These results indicated that chronic heat stress significantly increased lactate production, reduced meat pH value by accelerating meat glycolysis, and eventually reduced meat quality. PMID:23091152

Zhang, Z Y; Jia, G Q; Zuo, J J; Zhang, Y; Lei, J; Ren, L; Feng, D Y

2012-11-01

480

The cyclical unity of Catullus 61 to 68  

Microsoft Academic Search

Catullus 61 to 68 have not received the attention they deserve. Critics have either analysed the poems in isolation or attempted superficial and selective examinations of the group as a whole. By scrutinizing the poet's use of recurrent vocabulary in poems 61 to 68, it is possible to see a definite cyclic progression throughout the poems, and a clear development

Michael Phillip Parker

1991-01-01

481

The Cyclical Unity of Catullus 61 to 68  

Microsoft Academic Search

Caiullus 61 to 68 have not received the attention they deserve. Critics have either analysed the poems in isolation or attempted superficial and selective examinations of the group as a whole. By scrutinizing the poet's use of recurrent vocabulary in poems 61 to 68. it is possible to see a definite cyclic progression throughout the poems. and a clear development

Michael Phillip Parker

1991-01-01

482

The Cyclic Behavior of the U.S. Lodging Industry  

Microsoft Academic Search

A recently constructed data series suggests that the hotel industry has experienced two rather large building booms from 1969 to 1994. By contrast, hotel demand seems to move closely with the United States economy, at a much higher cyclic frequency. Occupancy and room rental rates follow the slower movements in supply. A structural model is estimated over this series which

William C. Wheaton; Lawrence Rossoff

1998-01-01

483

Transition textures induced by cyclic phase transformation in titanium sheet  

Microsoft Academic Search

It has been known that when a phase transformation takes place in a metal, there is frequently an orientation relationship between the parent and product phase. Very limited work on the transformation texture induced by cyclic [alpha] [yields] [beta] [yields] [alpha] transformation in [alpha]-titanium and its alloys has been reported in recent years. The present work was undertaken to determine

Z. S. Zhu; J. L. Gu; N. P. Chen

1995-01-01

484

Cyclic phase change in a cylindrical thermal energy storage capsule  

Microsoft Academic Search

This paper is concerned with a practical melting\\/freezing problem in conjunction with the more realistic case of a cyclic phase change thermal energy storage device. In this model the phase change medium is encapsulated in long cylindrical tubes, the surface temperature of which is allowed to vary sinusoidally with time about the discrete freezing temperature. Initial temperature of the medium

M. Hasan; A. S. Mujumdar; M. E. Weber

1983-01-01

485

Cyclic neutropenia—Unusual cause of acute abdomen  

Microsoft Academic Search

Cyclic neutropenia, a rare blood disorder, may be complicated by spontaneous necrosis of the cecum and ascending colon. We describe one such case, where a staged surgical approach achieved a successful outcome. The importance of recognition of this disorder is stressed, since this allows both performance of appropriate surgery and consultation with hematologic colleagues.

T. O'Hanrahan; P. Dark; M. H. Irving

1991-01-01

486

Cyclic aza-peptide integrin ligand synthesis and biological activity.  

PubMed

Aza-peptides are obtained by replacement of the ?-C-atom of one or more amino acids by a nitrogen atom in a peptide sequence. Introduction of aza-residues into peptide sequences may result in unique structural and pharmacological properties, such that aza-scanning may be used to probe structure-activity relationships. In this study, a general approach for the synthesis of cyclic aza-peptides was developed by modification of strategies for linear aza-peptide synthesis and applied in the preparation of cyclic aza-pentapeptides containing the RGD (Arg-Gly-Asp) sequence. Aza-amino acid scanning was performed on the cyclic RGD-peptide Cilengitide, cyclo[R-G-D-f-N(Me)V] 1, and its parent peptide cyclo(R-G-D-f-V) 2, potent antagonists of the ?v?3, ?v?5, and ?5?1 integrin receptors, which play important roles in human tumor metastasis and tumor-induced angiogenesis. Although incorporation of the aza-residues resulted generally in a loss of binding affinity, cyclic aza-peptides containing aza-glycine retained nanomolar activity toward the ?v?3 receptor. PMID:22582818

Spiegel, Jochen; Mas-Moruno, Carlos; Kessler, Horst; Lubell, William D

2012-06-04

487

Product gas reservoirs for cyclic char burning engines and gasifiers  

Microsoft Academic Search

A cyclic char fuel burning power reactor (CFR) is described, comprising: at least one combined means for compressing and expanding gases, each comprising: an internal combustion engine (ICE) mechanism comprising a variable volume chamber (VVC) for compressing and expanding gases, and driv