Electron microscopy and diffraction of ordering in Ni-W alloys

International Nuclear Information System (INIS)

Mishra, N.S.

1995-01-01

Electron microscopy and diffraction studies of ordering in stoichiometric Ni-20%W and off-stoichiometric Ni-15%W alloys have been carried out. The specimens of Ni-20%W were first 1,398 K for 4 h and then quenched rapidly into water. Short range order (SRO) spots were observed at {1 1/2 0}* positions. Two hitherto unknown metastable phases: D 2h 25 -Ni 2 W and D0 22 -Ni 3 W were observed in the diffraction patterns. Long range order (LRO) transformations were studied at 1,103 and 1,213 K. Kinetics and mechanism of transformations have been identified. Ni-15%W specimens were solution treated at 1,523 K for 1 h followed by quenching in water. SRO spots similar to those found in Ni-20%W were observed in this alloy as well. The transition to LRO was studied at 1,093 K. Distinct Ni 4 W precipitates could be observed after 5 h of annealing at this temperature. After 100 h of annealing precipitates were found to grow into faceted shape coherent with the disordered matrix. After prolonged annealing for over 150 h the Ni 4 W precipitates began to lose coherency by the generation of misfit dislocations. The microstructural observations have been compared for the stoichiometric and off-stoichiometric alloys

Application of the cluster variation method to ordering in an interstitital solid solution

DEFF Research Database (Denmark)

Pekelharing, Marjon I.; Böttger, Amarante; Somers, Marcel A. J.

1999-01-01

The tetrahedron approximation of the cluster variation method (CVM) was applied to describe the ordering on the fcc interstitial sublattice of gamma-Fe[N] and gamma'-Fe4N1-x. A Lennard-Jones potential was used to describe the dominantly strain-induced interactions, caused by misfitting of the N...... atoms in the interstitial octahedral sites. The gamma-Fe[N]/gamma'-Fe4N1-x miscibility gap, short range ordering (SRO), and long-range ordering (LRO) of nitrogen in gamma-Fe[N] and gamma'-Fe4N1-x, respectively, and lattice parameters of gamma and gamm' were calculated. For the first time, N distribution...... parameters,as calculated by CVM, were compared directly to Mössbauer data for specific surroundings of Fe atoms....

Far-UV Spectral Mapping of Lunar Composition, Porosity, and Space Weathering: LRO Lyman Alpha Mapping Project (LAMP)

Science.gov (United States)

Retherford, K. D.; Greathouse, T. K.; Mandt, K.; Gladstone, R.; Liu, Y.; Hendrix, A. R.; Hurley, D.; Cahill, J. T.; Stickle, A. M.; Egan, A.; Kaufmann, D. E.; Grava, C.; Pryor, W. R.

2016-12-01

Far ultraviolet reflectance measurements of the Moon, icy satellites, comets, and asteroids obtained within the last decade have ushered in a new era of scientific advancement for UV surface investigations. The Lunar Reconnaissance Orbiter (LRO) Lyman Alpha Mapping Project (LAMP) has demonstrated an innovative nightside observing technique, putting a new light on permanently shadowed regions (PSRs) and other features on the Moon. Dayside far-UV albedo maps complement the nightside data, and LRO's polar orbit and high data downlink capabilities enable searches for diurnal variations in spectral signals. We'll discuss the strengths of the far-UV reflectance imaging spectroscopy technique with respect to several new LAMP results. Detections of water frost and hydration signatures near 165 nm, for example, provide constraints on composition that complement infrared spectroscopy, visible imaging, neutron spectroscopy, radar, and other techniques. At far-UV wavelengths a relatively blue spectral slope is diagnostic of space weathering, which is opposite of the spectral reddening indicator of maturity at wavelengths longward of 180 nm. By utilizing natural diffuse illumination sources on the nightside the far-UV technique is able to identify relative increases in porosity within the PSRs, and provides an additional tool for determining relative surface ages. Prospects for future studies are further enabled by a new, more sensitive dayside operating mode enacted during the present LRO mission extension.

The Phospholipid:Diacylglycerol Acyltransferase Lro1 Is Responsible for Hepatitis C Virus Core-Induced Lipid Droplet Formation in a Yeast Model System.

Directory of Open Access Journals (Sweden)

Shingo Iwasa

Full Text Available Chronic infection with the hepatitis C virus frequently induces steatosis, which is a significant risk factor for liver pathogenesis. Steatosis is characterized by the accumulation of lipid droplets in hepatocytes. The structural protein core of the virus induces lipid droplet formation and localizes on the surface of the lipid droplets. However, the precise molecular mechanisms for the core-induced formation of lipid droplets remain elusive. Recently, we showed that the expression of the core protein in yeast as a model system could induce lipid droplet formation. In this study, we probed the cellular factors responsible for the formation of core-induced lipid-droplets in yeast cells. We demonstrated that one of the enzymes responsible for triglyceride synthesis, a phospholipid:diacylglycerol acyltransferase (Lro1, is required for the core-induced lipid droplet formation. While core proteins inhibit Lro1 degradation and alter Lro1 localization, the characteristic localization of Lro1 adjacent to the lipid droplets appeared to be responsible for the core-induced lipid droplet formation. RNA virus genomes have evolved using high mutation rates to maintain their ability to replicate. Our observations suggest a functional relationship between the core protein with hepatocytes and yeast cells. The possible interactions between core proteins and the endoplasmic reticulum membrane affect the mobilization of specific proteins.

Temporal Variability of Lunar Exospheric Helium During January 2012 from LRO/LAMP

OpenAIRE

Feldman, Paul D.; Hurley, Dana M.; Retherford, Kurt D.; Gladstone, G. Randall; Stern, S. Alan; Pryor, Wayne; Parker, Joel Wm.; Kaufmann, David E.; Davis, Michael W.; Versteeg, Maarten; team, LAMP

2012-01-01

We report observations of the lunar helium exosphere made between December 29, 2011, and January 26, 2012, with the Lyman Alpha Mapping Project (LAMP) ultraviolet spectrograph on NASA's Lunar Reconnaissance Orbiter Mission (LRO). The observations were made of resonantly scattered He I 584 from illuminated atmosphere against the dark lunar surface on the dawn side of the terminator. We find no or little variation of the derived surface He density with latitude but day-to-day variations that li...

Magnetic short range order in Gd

International Nuclear Information System (INIS)

Child, H.R.

1976-01-01

Quasielastic neutron scattering has been used to investigate magnetic short range order in Gd for 80 0 K 0 K. Short range order exists throughout this range from well below T/sub C/ = 291 0 K to well above it and can be reasonably well described by an anisotropic Orstein-Zernike form for chi

LRO-LAMP failsafe door-open performance: improving FUV measurements of dayside lunar hydration

Science.gov (United States)

Davis, Michael W.; Greathouse, Thomas K.; Kaufmann, David E.; Retherford, Kurt D.; Versteeg, Maarten H.

2017-08-01

The Lunar Reconnaissance Orbiter's (LRO) Lyman Alpha Mapping Project (LAMP) is a lightweight (6.1 kg), lowpower (4.5 W), ultraviolet spectrograph based on the Alice instruments aboard the European Space Agency's Rosetta spacecraft and NASA's New Horizons spacecraft. Its primary job is to identify and localize exposed water frost in permanently shadowed regions (PSRs) near the Moon's poles, and to characterize landforms and albedos in PSRs. LRO launched on June 18, 2009 and reached lunar orbit four days later. LAMP operated with its failsafe door closed for its first seven years in flight. The failsafe door was opened in October 2016 to increase light throughput during dayside operations at the expense of no longer having the capacity to take further dark observations and slightly more operational complexity to avoid saturating the instrument. This one-time irreversible operation was approved after extensive review, and was conducted flawlessly. The increased throughput allows measurement of dayside hydration in one orbit, instead of averaging multiple orbits together to reach enough signal-to-noise. The new measurement mode allows greater time resolution of dayside water migration for improved investigations into the source and loss processes on the lunar surface. LAMP performance and optical characteristics after the failsafe door opening are described herein, including the new effective area, wavelength solution, and resolution.

Magnetic short-range order in Gd

International Nuclear Information System (INIS)

Child, H.R.

1978-01-01

The magnetic short-range order in a ferromagnetic, isotopically enriched 160 Gd metal single crystal has been investigated by quasielastic scattering of 81-meV neutrons. Since Gd behaves as an S-state ion in the metal, little anisotropy is expected in its magnetic behavior. However, the data show that there is anisotropic short-range order present over a large temperature interval both above and below T/sub C/. The data have been analyzed in terms of an Ornstein-Zernike Lorentzian form with anisotropic correlation ranges. These correlation ranges as deduced from the observed data behave normally above T/sub C/ but seem to remain constant over a fairly large interval below T/sub C/ before becoming unobservable at lower temperatures. These observations suggest that the magnetic ordering in Gd may be a more complicated phenomenon than first believed

Unitarity corrections to short-range order long-range rapidity correlations

CERN Document Server

Capella, A

1978-01-01

Although the effective hadronic forces have short range in rapidity space, one nevertheless expects long-range dynamical correlations induced by unitarity constraints. This paper contains a thorough discussion of long-range rapidity correlations in high-multiplicity events. In particular, the authors analyze in detail the forward- backward multiplicity correlations, measured recently in the whole CERN ISR energy range. They find from these data that the normalized variance of the number n of exchanged cut Pomerons, ((n/(n)-1)/sup 2/) , is most probably in the range 0.32 to 0.36. They show that such a number is obtained from Reggeon theory in the eikonal approximation. The authors also predict a very specific violation of local compensation of charge in multiparticle events: The violation should appear in the fourth-order zone correlation function and is absent in the second-order correlation function, the only one measured until now. (48 refs).

The Lunar Orbiter Laser Altimeter (LOLA) on NASA's Lunar Reconnaissance Orbiter (LRO) mission

Science.gov (United States)

Riris, H.; Cavanaugh, J.; Sun, X.; Liiva, P.; Rodriguez, M.; Neuman, G.

2017-11-01

The Lunar Orbiter Laser Altimeter (LOLA) instrument [1-3] on NASA's Lunar Reconnaissance Orbiter (LRO) mission, launched on June 18th, 2009, from Kennedy Space Center, Florida, will provide a precise global lunar topographic map using laser altimetry. LOLA will assist in the selection of landing sites on the Moon for future robotic and human exploration missions and will attempt to detect the presence of water ice on or near the surface, which is one of the objectives of NASA's Exploration Program. Our present knowledge of the topography of the Moon is inadequate for determining safe landing areas for NASA's future lunar exploration missions. Only those locations, surveyed by the Apollo missions, are known with enough detail. Knowledge of the position and characteristics of the topographic features on the scale of a lunar lander are crucial for selecting safe landing sites. Our present knowledge of the rest of the lunar surface is at approximately 1 km kilometer level and in many areas, such as the lunar far side, is on the order of many kilometers. LOLA aims to rectify that and provide a precise map of the lunar surface on both the far and near side of the moon. LOLA uses short (6 ns) pulses from a single laser through a Diffractive Optical Element (DOE) to produce a five-beam pattern that illuminates the lunar surface. For each beam, LOLA measures the time of flight (range), pulse spreading (surface roughness), and transmit/return energy (surface reflectance). LOLA will produce a high-resolution global topographic model and global geodetic framework that enables precise targeting, safe landing, and surface mobility to carry out exploratory activities. In addition, it will characterize the polar illumination environment, and image permanently shadowed regions of the lunar surface to identify possible locations of surface ice crystals in shadowed polar craters.

Medium-range dielectric order in systems with collectivized electrons

International Nuclear Information System (INIS)

Ismagilov, A.M.; Kopaev, Yu.V.

1993-01-01

The problem of formation of a medium-range dielectric order (on a scale much larger than the interatomic one) due to electron-electron correlations and to scattering by an impurity in a system near a phase transition into a long-range order state is solved by a microscopic approach. It is shown that for a weak impurity potential the effect of medium-range order formation is stronger than the effect of long-range order suppression related to scattering by an impurity. The influence of medium-range order on the one-particle excitation spectrum and on the density of states is considered. It is found that since the medium-range order in a system is due to correlations of electron and hole states open-quotes coupledclose quotes by a continuous set of inhomogeneity vectors (in contrast to the long-range order formed on a discrete set of such vectors), the density of states varies on an energy scale determined by the mean absolute value of these vectors. Therefore in a system undergoing phase transition into an inhomogeneous state with the modulus q 0 of inhomogeneity vectors the medium-range order forms in the density of states a pseudogap of scale length v F q 0 (v F is the Fermi velocity). This distinguishes such a system substantially from one, which tends to a phase transition into a homogeneous state (q 0 ≡0), where the medium-range order forms a pseudogap of scale length v F /ξ much-lt v F q 0 (ξ is the correlation length). The possible role of medium dielectric order effects in high-T c superconductors is discussed. 30 refs., 6 figs

The Wavelength Dependence of the Lunar Phase Curve as Seen by the LRO LAMP

Science.gov (United States)

Liu, Y.; Retherford, K. D.; Greathouse, T. K.; Hendrix, A. R.; Mandt, K.; Gladstone, R.; Cahill, J. T.; Egan, A.; Kaufmann, D. E.; Grava, C.; Pryor, W. R.

2016-12-01

The Lunar Reconnaissance Orbiter (LRO) Lyman Alpha Mapping Project (LAMP) provides global coverage of both nightside and dayside of the Moon in the far ultraviolet (FUV) wavelengths. The nightside observations use roughly uniform diffuse illumination sources from interplanetary medium Lyman-α sky glow and UV-bright stars so that traditional photometric corrections do not apply. In contrast, the dayside observations use sunlight as its illumination source where bidirectional reflectance is measured. The bidirectional reflectance is dependent on the incident, emission, and phase angles as well as the soil properties. Thus the comparisons of dayside mapping and nightside mapping techniques offer a method for cross-comparing the photometric correction factors because the observations are made under different lighting and viewing conditions. Specifically, the nightside data well constrain the single-scattering coefficient. We'll discuss the wavelength dependence of the lunar phase curve as seen by the LAMP instrument in dayside data. Our preliminary results indicate that the reflectance in the FUV wavelengths decreases with the increasing phase angles from 0° to 90°, similar to the phase curve in the UV-visible wavelengths as studied by Hapke et al. (2012) using LRO wide angle camera (WAC) data, among other visible-wavelength lunar studies. Particularly, we'll report how coherent backscattering and shadow hiding contribute to the opposition surge, given the fact that the albedo at FUV wavelengths is extremely low and thus multiple scattering is significantly less important. Finally, we'll report the derived Hapke parameters at FUV wavelengths for our study areas.

Magnetic short range order and the exchange coupling in magnets

International Nuclear Information System (INIS)

Antropov, V.P.

2006-01-01

We discuss our recent results of time-dependent density functional simulations of magnetic properties of Fe and Ni at finite temperatures. These results indicated that a strong magnetic short range order is responsible for the magnetic properties of elementary Ni and any itinerant magnet in general. We demonstrated that one can use the value of the magnetic short range order parameter to produce new quantitative classification of magnets. We also discuss the nature of the exchange coupling and its connection with the short range order. The spin-wave like propagating and diffusive excitations in paramagnetic localized systems with small short range order have been predicted while in the itinerant systems the short range order is more complicated. The possible smallness of the quantum factor in the itinerant magnets with short range order is discussed

Measurements of short-range ordering in Ni3Al

International Nuclear Information System (INIS)

Okamoto, J.K.; Ahn, C.C.

1992-01-01

This paper reports on extended electron energy-loss fine structure (EXELFS) that has been used to measure short-range ordering in Ni 3 Al. Films of fcc Ni 3 Al with suppressed short-range order synthesized by vacuum evaporation of Ni 3 Al onto room temperature substrates. EXELFS data were taken from both Al K and Ni L 23 edges. The development of short-range order was observed after the samples were annealed for various times at temperatures below 350 degrees C. Upon comparison with ab initio planewave EXELFS calculations, it was found that the Warren-Cowley short-range order parameter a(1nn) changed by about -0.1 after 210 minutes of annealing at 150 degrees C

Ni3Ga - an investigation of ordering kinetics by residual resistometry

International Nuclear Information System (INIS)

Semenova, Olga

2005-01-01

Order-disorder transformations in the compound Ni 3 Ga with L1 2 superstructure were investigated by residual electrical resistometry during isochronal and isothermal step-annealing treatments. Resistivity measurements after several isochronal annealing treatments at rising and falling temperatures in the range at 293-800 K showed a complex annealing behavior of Ni 3 Ga. The first registration of a slight atomic mobility was identified already at 380 K, followed by the second step in atomic mobility observed between 500 and 650 K and attributed to a change in the degree of long range order (LRO) in the structure. Measurements at isothermal annealing have been performed after isothermal step treatments between 673 and 786 K also at rising and falling temperatures. The analysis of electrical resistivity curves allowed for conclusion that the order-disorder equilibrium in Ni 3 Ga is reached not in a single exponential process, but as a result of two processes with distinctly different rates. The ordering activation energies of both fast and slow processes in Ni 3 Ga were calculated. For the first, fast relaxation process an activation energy parameter was found equal to 1.47 eV; the second, slow process was characterized by an activation energy of 2.66 eV

Rapidly solidified long-range-ordered alloys

International Nuclear Information System (INIS)

Lee, E.H.; Koch, C.C.; Liu, C.T.

1981-01-01

The influence of rapid solidification processing on the microstructure of long-range-ordered alloys in the (Fe, Co, Ni) 3 V system has been studied by transmission electron microscopy. The main microstructural feature of the as-quenched alloys was a fine cell structure (approx. 300 nm diameter) decorated with carbide particles. This structure was maintained aftr annealing treatments which develop the ordered crystal structure. Other features of the microstructures both before and after annealing are presented and discussed. 6 figures

Intermediate-range order in lead metasilicate glass

Energy Technology Data Exchange (ETDEWEB)

Suzuya, Kentaro [Japan Atomic Energy Research Inst., Ako, Hyogo (Japan)]|[Argonne National Lab., IL (United States). Materials Science Div.; Price, D.L.; Saboungi, M.L. [Argonne National Lab., IL (United States). Materials Science Div.; Ohno, Hideo [Japan Atomic Energy Research Inst., Ako, Hyogo (Japan)

1997-03-01

The complementarity of anomalous X-ray scattering (AXS) and neutron diffraction (ND) techniques is used here to investigate the nature and origin of intermediate-range order in lead metasilicate glass. Both X-ray and neutron source factors reveal small peaks at low wave vector which are shown to be associated with intermediate-range order of the Pb-O network. The combination of AXS and ND is shown to be a powerful tool to correlate contributions from the different atom pairs to such a peak. The information thus derived is compared with results from alkali germanate glasses and with structural data on corresponding crystalline compounds.

LRO Lyman Alpha Mapping Project (LAMP) Far-UV Investigations of Lunar Composition, Porosity, and Space Weathering

Science.gov (United States)

Retherford, K. D.; Greathouse, T. K.; Mandt, K. E.; Gladstone, R.; Hendrix, A.; Cahill, J. T.; Liu, Y.; Grava, C.; Hurley, D.; Egan, A.; Kaufmann, D. E.; Raut, U.; Byron, B. D.; Magana, L. O.; Stickle, A. M.; Wyrick, D. Y.; Pryor, W. R.

2017-12-01

Far ultraviolet reflectance measurements of the Moon, icy satellites, comets, and asteroids have proven surprisingly useful for advancing our understanding of planetary surfaces. This new appreciation for planetary far-UV imaging spectroscopy is provided in large part thanks to nearly a decade of investigations with the Lunar Reconnaissance Orbiter (LRO) Lyman Alpha Mapping Project (LAMP). LAMP has demonstrated an innovative nightside observing technique, putting a new light on permanently shadowed regions (PSRs) and other features on the Moon. Dayside far-UV albedo maps complement the nightside data, enabling comparisons of direct and hemispheric (diffuse) illumination derived albedos. We'll discuss the strengths of the far-UV reflectance imaging spectroscopy technique with respect to several new LAMP results. Detections of water frost and hydration signatures near 165 nm, for example, provide constraints on composition that complement infrared spectroscopy, visible imaging, neutron spectroscopy, radar, and other techniques. LRO's polar orbit and high data downlink capabilities enable searches for diurnal variations in spectral signals. At far-UV wavelengths a relatively blue spectral slope is diagnostic of space weathering, which is opposite of the spectral reddening indicator of maturity at wavelengths longward of 180 nm. By utilizing natural diffuse illumination sources on the nightside the far-UV technique is able to identify relative increases in porosity within the PSRs, and provides an additional tool for determining relative surface ages. On October 6, 2016 LAMP enacted a new, more sensitive dayside operating mode that expands its ability to search for diurnally varying hydration signals associated with different regions and features.

Positional short-range order in the nematic phase of n BABAs

Science.gov (United States)

Usha Deniz, K.; Pepy, G.; Parette, G.; Keller, P.

1991-10-01

The positional short-range order, SRO ⊥, perpendicular to the nematic director n̂ has been studied in the fibre-type nematics, nBABAs, by neutron diffraction. SRO ⊥ is found to be dependent on other types of nematic short-range order but not on the orientational long-range order.

Amorphous photonic crystals with only short-range order.

Science.gov (United States)

Shi, Lei; Zhang, Yafeng; Dong, Biqin; Zhan, Tianrong; Liu, Xiaohan; Zi, Jian

2013-10-04

Distinct from conventional photonic crystals with both short- and long-range order, amorphous photonic crystals that possess only short-range order show interesting optical responses owing to their unique structural features. Amorphous photonic crystals exhibit unique light scattering and transport, which lead to a variety of interesting phenomena such as isotropic photonic bandgaps or pseudogaps, noniridescent structural colors, and light localization. Recent experimental and theoretical advances in the study of amorphous photonic crystals are summarized, focusing on their unique optical properties, artificial fabrication, bionspiration, and potential applications. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnetism and atomic short-range order in Ni-Rh alloys

Science.gov (United States)

Carnegie, D. W., Jr.; Claus, H.

1984-07-01

Low-field ac susceptibility measurements of Ni-Rh samples of various concentrations are presented. Giant effects of the metallurgical state on the magnetic ordering temperature are associated with changes in the degree of atomic short-range order. By careful control of this degree of short-range order, it is possible to demonstrate the existence of a spin-glass state in Ni-Rh alloys.

Microstructure and tensile properties of neutron-irradiated (FE061Ni039)3V ordered alloy

International Nuclear Information System (INIS)

Braski, D.N.

1982-01-01

Small tensile specimens of the (Fe 0 61 Ni 0 39 ) 3 V long-range-ordered alloy were irradiated in the ORR to 4 dpa at 523, 623, and 823 K and subsequently tested at the same respective temperatueres. The alloy remained ordered after irradiation at all three temperatures. Irradiation at 523 and 623 K increased the yield strength of the material by producing Frank loops in the microstructure and reduced the total elongation. The low strain hardening observed was attributed to planar slip and the absence of cross slip. Irradiation at 823 K embrittled the alloy. Premature failure was apparently initiated by helium bubbles on sigma phase boundaries which grew rapidly during the test to form microcracks. Fracture occurred after a microcrack propagated across grain boundaries that were weakened by helium and possible sulfur. New LRO alloys without sigma phase should perform better under neutron irradiation

Methods for studying short-range order in solid binary solutions

International Nuclear Information System (INIS)

Beranger, Gerard

1969-12-01

The short range order definition and its characteristic parameters are first recalled. The different methods to study the short range order are then examined: X ray diffusion, electrical resistivity, specific heat and thermoelectric power, neutron diffraction, electron spin resonance, study of thermodynamic and mechanical properties. The theory of the X ray diffraction effects due to short range order and the subsequent experimental method are emphasized. The principal results obtained from binary Systems, by the different experimental techniques, are reported and briefly discussed. The Au-Cu, Li-Mg, Au-Ni and Cu-Zn Systems are moreover described. (author) [fr

Bistatic Radar Observations of the Moon Using Mini-RF on LRO and the Arecibo Observatory

Science.gov (United States)

Patterson, G. W.; Stickle, A. M.; Turner, F. S.; Jensen, J. R.; Bussey, D. B. J.; Spudis, P.; Espiritu, R. C.; Schulze, R. C.; Yocky, D. A.; Wahl, D. E.;

Fluctuation microscopy: a probe of medium range order

International Nuclear Information System (INIS)

Treacy, M M J; Gibson, J M; Fan, L; Paterson, D J; McNulty, I

2005-01-01

Fluctuation microscopy is a hybrid diffraction-imaging technique that detects medium range order in amorphous materials by examining spatial fluctuations in coherent scattering. These fluctuations appear as speckle in images and diffraction patterns. The volume of material contributing to the speckle is determined by the point-spread function (the resolution) of the imaging optics and the sample thickness. The spatial periodicities being probed are related to the diffraction vector. Statistical analysis of the speckle allows the random and non-random (ordered) contributions to be discriminated. The image resolution that gives the maximum speckle contrast, as determined by the normalized variance of the image intensity, is determined by the characteristic length scale of the ordering. Because medium range ordering length scales can extend out to about the tenth coordination shell, fluctuation microscopy tends to be a low image resolution technique. This review presents the kinematical scattering theory underpinning fluctuation microscopy and a description of fluctuation electron microscopy as it has been employed in the transmission electron microscope for studying amorphous materials. Recent results using soft x-rays for studying nanoscale materials are also presented. We summarize outstanding issues and point to possible future directions for fluctuation microscopy as a technique

Short range order in FeCo-X alloys

International Nuclear Information System (INIS)

Fultz, B.

1988-01-01

Moessbauer spectrometry was used to study the kinetics of chemical ordering in FeCo and in FeCo alloyed with ternary solutes. With respect to the binary FeCo alloy, the kinetics of B2 ordering were slowed when 2% of 4d- or 5d-series ternary solute atoms were present, but 3p- and 3d-series ternary solutes had little effect on ordering kinetics. The relaxation of order around the ternary solute atoms could be discerned in Moessbauer spectra, and it seems that the development of B2 short range order is influenced by structural relaxations around the ternary solute atoms. Different thermal treatments were shown to cause different relaxations of and correlations, suggesting that Moessbauer spectrometry can be used to identify different kinetic paths of ordering in ternary alloys. (orig.)

Universal medium-range order of amorphous metal oxides.

Science.gov (United States)

Nishio, Kengo; Miyazaki, Takehide; Nakamura, Hisao

2013-10-11

We propose that the structure of amorphous metal oxides can be regarded as a dual-dense-random-packing structure, which is a superposition of the dense random packing of metal atoms and that of oxygen atoms. Our ab initio molecular dynamics simulations show that the medium-range order of amorphous HfO2, ZrO2, TiO2, In2O3, Ga2O3, Al2O3, and Cu2O is characterized by the pentagonal-bipyramid arrangement of metal atoms and that of oxygen atoms, and prove the validity of our dual-random-sphere-packing model. In other words, we find that the pentagonal medium-range order is universal independent of type of metal oxide.

Long-range order in canary song.

Science.gov (United States)

Markowitz, Jeffrey E; Ivie, Elizabeth; Kligler, Laura; Gardner, Timothy J

2013-01-01

Bird songs range in form from the simple notes of a Chipping Sparrow to the rich performance of the nightingale. Non-adjacent correlations can be found in the syntax of some birdsongs, indicating that the choice of what to sing next is determined not only by the current syllable, but also by previous syllables sung. Here we examine the song of the domesticated canary, a complex singer whose song consists of syllables, grouped into phrases that are arranged in flexible sequences. Phrases are defined by a fundamental time-scale that is independent of the underlying syllable duration. We show that the ordering of phrases is governed by long-range rules: the choice of what phrase to sing next in a given context depends on the history of the song, and for some syllables, highly specific rules produce correlations in song over timescales of up to ten seconds. The neural basis of these long-range correlations may provide insight into how complex behaviors are assembled from more elementary, stereotyped modules.

Long-range order in InAsSb

Science.gov (United States)

Jen, H. R.; Ma, K. Y.; Stringfellow, G. B.

1989-03-01

Results are presented of transmission electron diffraction (TED) observations, demonstrating, for the first time, a CuPt-type ordering in InAs(1-x)Sb(x) alloys, over a wide range of x values (from x = 0.22 to 0.88). The InAsSb alloys were prepared by OMVPE on (001) oriented undoped InSb or InAs substrates. The ordering-induced spots on the TED patterns show the highest intensity for x of about 0.5 and the lowest intensity toward each binary end compound. Only two of the four variants are formed during growth. In some areas, the degree of order for these two variants, 1/2(-1 1 1) and 1/2(1 -1 1), is equal, and in other areas, one variant dominates.

Rescue dose orders as an alternative to range orders: an evidence-based practice project.

Science.gov (United States)

Yi, Cassia

2015-06-01

Relief of pain is a fundamental aspect of optimal patient care. However, pain management in the inpatient setting is often constrained by concerns related to regulatory oversight, particularly with regard to the use of opioid dose range orders. These concerns can inadvertently result in the development of policies and practices that can negatively impact the health care team's ability to deliver optimal and individualized pain management. An evidence-based practice project was undertaken to address concerns about regulatory oversight of pain management processes by changing the way pain was managed in a large academic hospital setting. A novel pain management approach using rescue dose medications was established as an alternative to opioid dose range orders. The use of the rescue dose protocol was successfully implemented. Outcomes included an overall reduction in the administration of inappropriate intravenous opioids and opioid-acetaminophen combination medications, with a subsequent increase in single-entity first-line opioid analgesics. Rescue dose protocols may offer an alternative to opioid dose range orders as a means of effectively managing pain. Copyright © 2015 American Society of PeriAnesthesia Nurses. Published by Elsevier Inc. All rights reserved.

Target recognition of ladar range images using even-order Zernike moments.

Science.gov (United States)

Liu, Zheng-Jun; Li, Qi; Xia, Zhi-Wei; Wang, Qi

2012-11-01

Ladar range images have attracted considerable attention in automatic target recognition fields. In this paper, Zernike moments (ZMs) are applied to classify the target of the range image from an arbitrary azimuth angle. However, ZMs suffer from high computational costs. To improve the performance of target recognition based on small samples, even-order ZMs with serial-parallel backpropagation neural networks (BPNNs) are applied to recognize the target of the range image. It is found that the rotation invariance and classified performance of the even-order ZMs are both better than for odd-order moments and for moments compressed by principal component analysis. The experimental results demonstrate that combining the even-order ZMs with serial-parallel BPNNs can significantly improve the recognition rate for small samples.

Long range order in the ground state of two-dimensional antiferromagnets

International Nuclear Information System (INIS)

Neves, E.J.; Perez, J.F.

1985-01-01

The existence of long range order is shown in the ground state of the two-dimensional isotropic Heisenberg antiferromagnet for S >= 3/2. The method yields also long range order for the ground state of a larger class of anisotropic quantum antiferromagnetic spin systems with or without transverse magnetic fields. (Author) [pt

Modeling Illumination Conditions on the Moon: Applications to LRO-LAMP

Science.gov (United States)

Byron, B. D.; Mazarico, E. M.; Retherford, K. D.; Mandt, K. E.; Greathouse, T.; Gladstone, R.

2017-12-01

LRO-LAMP is a UV spectrograph which uses illumination from Lyman-α sky glow along with UV light from bright stars to image the dark, permanently shadowed regions (PSRs) of the lunar surface. Accurate modeling of this UV illumination is essential to creating albedo maps of the lunar surface, which can shed light on lunar regolith processes and help to constrain the distribution of water ice in polar PSRs. In this study, the variation in reflected intensity received by the LAMP detector was modeled for South Pole crater Amundsen using the illumination program IllumNG. Amundsen was chosen for study due to the PSR in its Northern side and its highly illuminated equator-facing slopes on the Southern wall. The model works by tracing a ray from each LAMP detector pixel along its boresight until the point where it intersects the lunar surface, and calculating the percentage of the total source flux visible above the horizon. In this study, the three main illumination sources used are the Sun, Interplanetary Lyman-α sky glow, and bright UV starlight in the On Band (130-155 nm) and Off Band (155-190 nm) wavelength ranges. The model also has the capability to calculate incident flux received at the surface, as well as intensity reflected from the surface and received by the LAMP detector along each boresight. The study found a noticeable variation in received intensity between six month stretches for the year of 2010. Over the period of January through July, about 6% more IPM Lyman-α flux was reflected from the surface of Amundsen than for July through December. For stellar flux in the On Band, a 13% difference in flux was reflected between the six month periods. In comparing the monthly intensity maps created by the model with LAMP measured monthly brightness maps, similar crater features are apparent. Though the model brightness is generally higher than the LAMP brightness, after accounting for albedo ( 0.05 for the South Pole region) the values are in closer agreement

Intermediate- and short-range order in phosphorus-selenium glasses

International Nuclear Information System (INIS)

Bytchkov, Aleksei; Hennet, Louis; Price, David L.; Miloshova, Mariana; Bychkov, Eugene; Kohara, Shinji

2011-01-01

State-of-the-art neutron and x-ray diffraction measurements have been performed to provide a definitive picture of the intermediate- and short-range structures of P x Se 1-x glasses spanning two glass regions, x 0.025-0.54 and 0.64-0.84. Liquid P 4 Se 3 and amorphous red P and Se were also measured. Detailed information was obtained about the development with increasing phosphorous concentration of intermediate-range order on the length scale ∼6 A ring , based on the behavior of the first sharp diffraction peak. Attention is also paid to the feature in the structure factor at 7.5 A ring -1 , identified in earlier numerical simulations, provides further evidence of the existence of molecular units. The real-space transforms yield a reliable statistical picture of the changing short-range order as x increases, using the information about types and concentrations of local structural units provided by previous NMR measurements to interpret the trends observed.

Characterization of the radiation environment of the inner heliosphere using LRO/CRaTER and EMMREM

Science.gov (United States)

Joyce, Colin J.

2016-08-01

I provide a characterization of the radiation environment of the inner heliosphere from mid-2009 to present using measurements made by the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) aboard the Lunar Reconnaissance Orbiter (LRO) and modelling provided by the Earth-Moon-Mars Radiation Environment Module (EMMREM). In the course of this study, I analyze solar energetic particle (SEP) radiation in the form of four major solar events that occurred during this time range as well as the evolution of galactic cosmic ray (GCR) modulation over a period in which relatively calm solar conditions have resulted in the highest GCR fluxes measured in the space age. Using CRaTER measurements taken during three major solar events that occurred in 2012, I demonstrate a validation of the online PREDICCS system (Predictions of radiation from REleASE, EMMREM, and Data Incorporating CRaTER, COSTEP, and other SEP measurements), which uses EMMREM to provide near real-time radiation modelling at the Earth, Moon and Mars, finding PREDICCS to be quite accurate in modelling the peak dose rates and total accumulated doses for major solar events. Having demonstrated the accuracy of PREDICCS/EMMREM in modelling SEP events, EMMREM is used to provide an analysis of the potential radiation hazard of the extreme solar event observed by STEREO A on 23 July 2012, an event which has drawn comparisons to the historic Carrington event due to the exceptional size and record speed of the interplanetary coronal mass ejection associated with it. Such an event might be viewed as something like a worst case scenario in terms of the threat of SEP radiation to astronauts, however the evidence shown here suggests that, with the benefit of heavy protective shielding, astronauts would not have been exposed to levels of radiation that approach NASA's permissible exposure limits. These findings add to a mounting set of evidence which suggests that, contrary to conventional wisdom, the largest radiation

Short, intermediate and long range order in amorphous ices

Science.gov (United States)

Martelli, Fausto; Torquato, Salvatore; Giovanbattista, Nicolas; Car, Roberto

Water exhibits polyamorphism, i.e., it exists in more than one amorphous state. The most common forms of glassy water are the low-density amorphous (LDA) and the high-density amorphous (HDA) ices. LDA, the most abundant form of ice in the Universe, transforms into HDA upon isothermal compression. We model the transformation of LDA into HDA under isothermal compression with classical molecular dynamics simulations. We analyze the molecular structures with a recently introduced scalar order metric to measure short and intermediate range order. In addition, we rank the structures by their degree of hyperuniformity, i.e.,the extent to which long range density fluctuations are suppressed. F.M. and R.C. acknowledge support from the Department of Energy (DOE) under Grant No. DE-SC0008626.

Incidence and transfer behaviors of high-order hot judder in passenger cars

OpenAIRE

Xu, Xinfu

2016-01-01

As one of the brake-induced noises and vibrations, hot judder is forced vibration, which is caused by unevenness of the brake disc due to the thermal mechanical interactions in wheel brakes. Brake disc unevenness is normally described and evaluated as the Disc Thickness Variation (DTV) and the disc’ Lateral Run-Out (LRO). DTV and LRO gener-ate Brake Pressure Variation (BPV) and Brake Torque Variation (BTV) in wheel brakes, which are transmitted to the driver and perceived by the driver as the...

Long range order and giant components of quantum random graphs

CERN Document Server

Ioffe, D

2006-01-01

Mean field quantum random graphs give a natural generalization of classical Erd\\H{o}s-R\\'{e}nyi percolation model on complete graph $G_N$ with $p =\\beta /N$. Quantum case incorporates an additional parameter $\\lambda\\geq 0$, and the short-long range order transition should be studied in the $(\\beta ,\\lambda)$-quarter plane. In this work we explicitly compute the corresponding critical curve $\\gamma_c$, and derive results on two-point functions and sizes of connected components in both short and long range order regions. In this way the classical case corresponds to the limiting point $(\\beta_c ,0) = (1,0)$ on $\\gamma_c$.

Modeling thermodynamics of Fe-N phases; characterisation of e-Fe2N1-z

DEFF Research Database (Denmark)

Pekelharing, M.I.; Böttger, A.; Somers, Marcel A.J.

1999-01-01

In order to arrive at modeling the thermodynamics of Fe-N phases, including long-range (LRO) and short-range ordering (SRO) of the N atoms, it is important to understand the role of N interstitially dissolved in an Fe-host lattice. The crystal structure of -Fe2N1-z consists of an h.c.p. iron...... sublattice and a hexagonal nitrogen sublattice formed by octahedral interstices of the Fe sublattice [1]. Two ground-state structures have been proposed for the ordered arrangement of the N atoms on their own sublattice [1], which were shown to be thermodynamically favourable [2]: configuration A for Fe2N1...... investigated with X-ray diffraction (XRD) and Mössbauer spectroscopy. A thermodynamic model accounting for the two configurations of LRO of the N atoms [2,3] was fitted to the N-absorption isotherm at 723 K and resulted in the occupancies of the sites of the nitrogen sublattice. A miscibility gap between...

Short range order in liquid pnictides

International Nuclear Information System (INIS)

Mayo, M; Makov, G; Yahel, E; Greenberg, Y

2013-01-01

Liquid pnictides have anomalous physical properties and complex radial distribution functions. The quasi-crystalline model of liquid structure is applied to interpret the three-dimensional structure of liquid pnictides. It is shown that all the column V elements can be characterized by a short range order lattice symmetry similar to that of the underlying solid, the A7 structure, which originates from a Peierls distorted simple cubic lattice. The evolution of the liquid structure down the column as well as its temperature and pressure dependence is interpreted by means of the effect of thermodynamic parameters on the Peierls distortion. Surprisingly, it is found that the Peierls effect increases with temperature and the nearest neighbour distances exhibit negative thermal expansion. (paper)

Self-organized molecular films with long-range quasiperiodic order.

Science.gov (United States)

Fournée, Vincent; Gaudry, Émilie; Ledieu, Julian; de Weerd, Marie-Cécile; Wu, Dongmei; Lograsso, Thomas

2014-04-22

Self-organized molecular films with long-range quasiperiodic order have been grown by using the complex potential energy landscape of quasicrystalline surfaces as templates. The long-range order arises from a specific subset of quasilattice sites acting as preferred adsorption sites for the molecules, thus enforcing a quasiperiodic structure in the film. These adsorption sites exhibit a local 5-fold symmetry resulting from the cut by the surface plane through the cluster units identified in the bulk solid. Symmetry matching between the C60 fullerene and the substrate leads to a preferred adsorption configuration of the molecules with a pentagonal face down, a feature unique to quasicrystalline surfaces, enabling efficient chemical bonding at the molecule-substrate interface. This finding offers opportunities to investigate the physical properties of model 2D quasiperiodic systems, as the molecules can be functionalized to yield architectures with tailor-made properties.

Short-range order in amorphous thin films of indium selenides

International Nuclear Information System (INIS)

Zakharov, V.P.; Poltavtsev, Yu.G.; Sheremet, G.P.

1982-01-01

A structure of the short-range order and a character of interatomic interactions in indium selenides Insub(1-x)Sesub(x) with 0.333 <= x <= 0.75, obtained in the form of amorphous films 0.05-0.80 μm thick are studied using electron diffraction method. It is found out that mostly tetrahedrical coordination of nearest neighbours in the vicinity of indium atoms is characteristic for studied amorphous films, and coordination of selenium atoms is different. Amorphous film with x=0.75 posesses a considereably microheterogeneous structure of the short-range order, which is characterized by the presence of microunclusions of amorphous selenium and atoms of indium, octohedrically coordinated by selenium atoms

Double scattering of light from Biophotonic Nanostructures with short-range order

Energy Technology Data Exchange (ETDEWEB)

Noh, Heeso; Liew, Seng Fatt; Saranathan, Vinodkumar; Prum, Richard O.; Mochrie, Simon G.J.; Dufresne, Eric R.; Cao, Hui (Yale)

2010-07-28

We investigate the physical mechanism for color production by isotropic nanostructures with short-range order in bird feather barbs. While the primary peak in optical scattering spectra results from constructive interference of singly-scattered light, many species exhibit secondary peaks with distinct characteristic. Our experimental and numerical studies show that these secondary peaks result from double scattering of light by the correlated structures. Without an analog in periodic or random structures, such a phenomenon is unique for short-range ordered structures, and has been widely used by nature for non-iridescent structural coloration.

Edge Singularities and Quasilong-Range Order in Nonequilibrium Steady States

Science.gov (United States)

De Nardis, Jacopo; Panfil, Miłosz

2018-05-01

The singularities of the dynamical response function are one of the most remarkable effects in many-body interacting systems. However in one dimension these divergences only exist strictly at zero temperature, making their observation very difficult in most cold atomic experimental settings. Moreover the presence of a finite temperature destroys another feature of one-dimensional quantum liquids: the real space quasilong-range order in which the spatial correlation functions exhibit power-law decay. We consider a nonequilibrium protocol where two interacting Bose gases are prepared either at different temperatures or chemical potentials and then joined. We show that the nonequilibrium steady state emerging at large times around the junction displays edge singularities in the response function and quasilong-range order.

Fluctuations in substitution type alloys and their analyses. Short-range order structures

International Nuclear Information System (INIS)

Iwasaki, Hiroshi; Ohshima, Ken-ichi

2010-01-01

This article is the fifth of the serial lecture, microstructures and fluctuations, in this magazine. The formula of X-ray diffuse scattering intensity was derived for binary alloys by introducing short-range order parameters. Diffuse scattering intensities for a single crystal Cu 3 Au were measured above critical temperature for ordering. The short-range parameters were obtained by a three-dimensional Fourier analysis. The long-range pair interaction between atoms was originated from the indirect screening interaction due to conduction electrons. A detailed study was made on short-range-order diffuse scattering from Cu 3 Au in the disordered state by electron diffraction. Fourfold splitting of the diffuse scattering was observed at 110 in the reciprocal lattice, and this result was attributed to the reflection of the form of the Fermi surface. The X-ray diffuse scattering intensity was measured at room temperature for disordered Cu-Pd alloys for the six composition of Pd. Twofold and fourfold splitting of diffuse scattering due to the short-range order (SRO) were observed at 100, 110 and equivalent positions respectively from alloys with more than 13.0at% Pd. The SRO parameters were determined from all the six alloys. For Cu-Pt alloys, the diffuse scattering originated from the correlation between Cu and Pt layers in direction was observed in addition to the one due to the reflection of the Fermi surface imaging. (author)

Single-ion and single-chain magnetism in triangular spin-chain oxides

Science.gov (United States)

Seikh, Md. Motin; Caignaert, Vincent; Perez, Olivier; Raveau, Bernard; Hardy, Vincent

2017-05-01

S r4 -xC axM n2Co O9 oxides (x =0 and x =2 ) are found to exhibit magnetic responses typical of single-chain magnets (SCMs) and single-ion magnets (SIMs), two features generally investigated in coordination polymers or complexes. The compound x =0 appears to be a genuine SCM, in that blocking effects associated with slow spin dynamics yield remanence and coercivity in the absence of long-range ordering (LRO). In addition, SIM signatures of nearly identical nature are detected in both compounds, coexisting with SCM in x =0 and with LRO in x =2 . It is also observed that a SCM response can be recovered in x =2 after application of magnetic field. These results suggest that purely inorganic systems could play a valuable role in the topical issue of the interplay among SIM, SCM, and LRO phenomena in low-dimensional magnetism.

Estimation of lunar FeO abundance based on imaging by LRO Diviner

International Nuclear Information System (INIS)

Tang, Xiao; Zhang, Xue-Wei; Chen, Yuan; Zhang, Xiao-Meng; Cai, Wei; Wu, Yun-Zhao; Luo, Xiao-Xing; Jiang, Yun; Xu, Ao-Ao; Wang, Zhen-Chao

2016-01-01

Understanding the abundance and distribution characteristics of FeO on the surface of the Moon is important for investigating its evolution. The current high resolution maps of the global FeO abundance are mostly produced with visible and near infrared reflectance spectra. The Christiansen Feature (CF) in mid-infrared has strong sensitivity to lunar minerals and correlates to major elements composing minerals. This paper investigates the possibility of mapping global FeO abundance using the CF values from the Diviner Lunar Radiometer Experiment aboard the Lunar Reconnaissance Orbiter (LRO) mission. A high correlation between the CF values and FeO abundances from the Apollo samples was found. Based on this high correlation, a new global map (±60°) of FeO was produced using the CF map. The results show that the global FeO average is 8.2 wt.%, the highland average is 4.7 wt.%, the global modal abundance is 5.4 wt.% and the lunar mare mode is 15.7 wt.%. These results are close to those derived from data provided by Clementine, the Lunar Prospector Gamma Ray Spectrometer (LP-GRS) and the Chang'e-1 Interference Imaging Spectrometer (IIM), demonstrating the feasibility of estimating FeO abundance based on the Diviner CF data. The near global FeO abundance map shows an enrichment of lunar major elements. (paper)

Directional and short-range ordering kinetics in metallic alloys, crystalline and amorphous

International Nuclear Information System (INIS)

Hillairet, J.

1985-01-01

This presentation describes the methods (resistometric and anelastic) based on analysis of stress-induced directional ordering and short-range ordering and their application to the study of metallic alloys, crystalline and amorphous. It focuses on the determination of the atomic mobility and point defect properties. It discusses also the structural information which can be gained by Zener relaxation studies about the order-disorder transition and self-induced directional ordering phenomena

The topological long range order in QCD. Applications to heavy ion collisions and cosmology

Directory of Open Access Journals (Sweden)

Zhitnitsky Ariel R.

2015-01-01

Full Text Available We argue that the local violation of P invariance in heavy ion collisions is a consequence of the long range topological order which is inherent feature of strongly coupled QCD. A similar phenomenon is known to occur in some topologically ordered condensed matter systems with a gap. We also discuss possible cosmological applications of this long range order in strongly coupled gauge theories. In particular, we argue that the de Sitter behaviour might be dynamically generated as a result of the long range order. In this framework the inflaton is an auxiliary field which effectively describes the dynamics of topological sectors in a gauge theory in the expanding universe, rather than a new dynamical degree of freedom.

Chemical and topological short-range order in metallic glasses

International Nuclear Information System (INIS)

Vincze, I.; Schaafsma, A.S.; Van der Woude, F.; Kemeny, T.; Lovas, A.

1980-10-01

Moessbauer spectroscopy is applied to the study of chemical short-range order in (Fe,Ni)B metallic glasses. It is found that the atomic arrangement in melt-quenched glasses closely resembles that of the crystalline counterparts (Fe 3 B is tetragonal, Ni 3 B is orthorombic). The distribution of transition metal atoms is not random at high Ni concentrations: Ni atoms prefer a neighbourhood with a higher boron coordination. (P.L.)

Ductile long range ordered alloys with high critical ordering temperature and wrought articles fabricated therefrom

Science.gov (United States)

Liu, Chain T.; Inouye, Henry

1979-01-01

Malleable long range ordered alloys having high critical ordering temperatures exist in the V(Fe, Co).sub.3 and V(Fe, Co, Ni).sub.3 systems. These alloys have the following compositions comprising by weight: 22-23% V, 14-30% Fe, and the remainder Co or Co and Ni with an electron density no more than 7.85. The maximum combination of high temperature strength, ductility and creep resistance are manifested in the alloy comprising by weight 22-23% V, 14-20% Fe and the remainder Co and having an atomic composition of V(Fe .sub.0.20-0.26 C Co.sub.0.74-0.80).sub.3. The alloy comprising by weight 22-23% V, 16-17% Fe and 60-62% Co has excellent high temperature properties. The alloys are fabricable into wrought articles by casting, deforming, and annealing for sufficient time to provide ordered structure.

Electron spin resonance for the detection of long-range spin nematic order

Science.gov (United States)

Furuya, Shunsuke C.; Momoi, Tsutomu

2018-03-01

Spin nematic phase is a quantum magnetic phase characterized by a quadrupolar order parameter. Since the quadrupole operators are directly coupled to neither the magnetic field nor the neutron, currently, it is an important issue to develop a method for detecting the long-range spin nematic order. In this paper, we propose that electron spin resonance (ESR) measurements enable us to detect the long-range spin nematic order. We show that the frequency of the paramagnetic resonance peak in the ESR spectrum is shifted by the ferroquadrupolar order parameter together with other quantities. The ferroquadrupolar order parameter is extractable from the angular dependence of the frequency shift. In contrast, the antiferroquadrupolar order parameter is usually invisible in the frequency shift. Instead, the long-range antiferroquadrupolar order yields a characteristic resonance peak in the ESR spectrum, which we call a magnon-pair resonance peak. This resonance corresponds to the excitation of the bound magnon pair at the wave vector k =0 . Reflecting the condensation of bound magnon pairs, the field dependence of the magnon-pair resonance frequency shows a singular upturn at the saturation field. Moreover, the intensity of the magnon-pair resonance peak shows a characteristic angular dependence and it vanishes when the magnetic field is parallel to one of the axes that diagonalize the weak anisotropic interactions. We confirm these general properties of the magnon-pair resonance peak in the spin nematic phase by studying an S =1 bilinear-biquadratic model on the square lattice in the linear flavor-wave approximation. In addition, we argue applications to the S =1/2 frustrated ferromagnets and also the S =1/2 orthogonal dimer spin system SrCu2(BO3)2, both of which are candidate materials of spin nematics. Our theory for the antiferroquadrupolar ordered phase is consistent with many features of the magnon-pair resonance peak experimentally observed in the low

Long-range dipolar order and dispersion forces in polar liquids

Science.gov (United States)

Besford, Quinn Alexander; Christofferson, Andrew Joseph; Liu, Maoyuan; Yarovsky, Irene

2017-11-01

Complex solvation phenomena, such as specific ion effects, occur in polar liquids. Interpretation of these effects in terms of structure and dispersion forces will lead to a greater understanding of solvation. Herein, using molecular dynamics, we probe the structure of polar liquids through specific dipolar pair correlation functions that contribute to the potential of mean force that is "felt" between thermally rotating dipole moments. It is shown that unique dipolar order exists at separations at least up to 20 Å for all liquids studied. When the structural order is compared with a dipolar dispersion force that arises from local co-operative enhancement of dipole moments, a strong agreement is found. Lifshitz theory of dispersion forces was compared with the structural order, where the theory is validated for all liquids that do not have significant local dipole correlations. For liquids that do have significant local dipole correlations, specifically liquid water, Lifshitz theory underestimates the dispersion force by a factor of 5-10, demonstrating that the force that leads to the increased structure in liquid water is missed by Lifshitz theory of van der Waals forces. We apply similar correlation functions to an ionic aqueous system, where long-range order between water's dipole moment and a single chloride ion is found to exist at 20 Å of separation, revealing a long-range perturbation of water's structure by an ion. Furthermore, we found that waters within the 1st, 2nd, and 3rd solvation shells of a chloride ion exhibit significantly enhanced dipolar interactions, particularly with waters at larger distances of separation. Our results provide a link between structures, dispersion forces, and specific ion effects, which may lead to a more robust understanding of solvation.

Medium-range order of magnetic amorphous alloys containing rare earth metals

International Nuclear Information System (INIS)

Boucher, B.

1989-01-01

The influence of nuclear order and surface layers on the magnetic order and the existence of two characteristic lengths (ξ=2π/k∼10 3 A or 10 A) have been established. The principal conclusions of theorists: concerning the abscence of infinite ferromagnetic clusters and the correlated spin glass or ferromagnet with wandering axis models are verified. The published results seem to indicate the existence of a critical temperature. The role of 3d ions in the magnetic ordering has not been extensively studied; it seems that the presence of 3d ions leads smaller correlation lengths. The Lorentzian scattering term correspond not only to spin waves but also to a static order. The origin of the L 3/2 scattering term observed in severals cases is discussed. It would be very useful to carry out measurements at lower q values so as to obtain more detailed informations concerning the nuclear or magnetic medium range order

Neutron diffraction study of the magnetic long-range order in Tb

DEFF Research Database (Denmark)

Dietrich, O.W.; Als-Nielsen, Jens Aage

1967-01-01

Like other heavy rare-earth metals, Tb exhibits a magnetic phase with a spiral structure. This appears within the temperature region from 216 to 226deg K between the ferromagnetic phase and the paramagnetic phase. The transition between ferromagnetic and spiral structure is of first order and imp...... at 216deg K to 20.7deg at 226deg K. The temperature variation of the transverse magnetostriction has also been measured and was found to vary approximately in proportion to the square of the magnetic long-range order....

Atmospheric radiation modeling of galactic cosmic rays using LRO/CRaTER and the EMMREM model with comparisons to balloon and airline based measurements

Science.gov (United States)

Joyce, C. J.; Schwadron, N. A.; Townsend, L. W.; deWet, W. C.; Wilson, J. K.; Spence, H. E.; Tobiska, W. K.; Shelton-Mur, K.; Yarborough, A.; Harvey, J.; Herbst, A.; Koske-Phillips, A.; Molina, F.; Omondi, S.; Reid, C.; Reid, D.; Shultz, J.; Stephenson, B.; McDevitt, M.; Phillips, T.

2016-09-01

We provide an analysis of the galactic cosmic ray radiation environment of Earth's atmosphere using measurements from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) aboard the Lunar Reconnaissance Orbiter (LRO) together with the Badhwar-O'Neil model and dose lookup tables generated by the Earth-Moon-Mars Radiation Environment Module (EMMREM). This study demonstrates an updated atmospheric radiation model that uses new dose tables to improve the accuracy of the modeled dose rates. Additionally, a method for computing geomagnetic cutoffs is incorporated into the model in order to account for location-dependent effects of the magnetosphere. Newly available measurements of atmospheric dose rates from instruments aboard commercial aircraft and high-altitude balloons enable us to evaluate the accuracy of the model in computing atmospheric dose rates. When compared to the available observations, the model seems to be reasonably accurate in modeling atmospheric radiation levels, overestimating airline dose rates by an average of 20%, which falls within the uncertainty limit recommended by the International Commission on Radiation Units and Measurements (ICRU). Additionally, measurements made aboard high-altitude balloons during simultaneous launches from New Hampshire and California provide an additional comparison to the model. We also find that the newly incorporated geomagnetic cutoff method enables the model to represent radiation variability as a function of location with sufficient accuracy.

EXAFS, Determination of Short Range Order and Local Structures in Materials

NARCIS (Netherlands)

Koningsberger, D.C.; Prins, R.

1981-01-01

Extended X-ray Absorption Fine Structure (EXAFS) is a powerful method of determining short range order and local structures in materials using X-ray photons produced by a synchrotron light source, or in-house by a high intensity rotating anode X-ray generator. The technique has provided valuable

Magnetic susceptibility as a method of investigation of short-range order in strongly nonstoichiometric carbides

International Nuclear Information System (INIS)

Nazarova, S.Z.; Gusev, A.I.

2001-01-01

Magnetic susceptibility in disordered and ordered carbides of transition metals (M = Ti, Zr, Hf, Nb, Ta) was studied, the results are generalized. It was ascertained that the change in carbide susceptibility induced by deviation from stoichiometry stems from specific features of electronic spectra of the compounds. The use of magnetic susceptibility for determining structural disorder-order transitions is discussed. It is shown that change in the contribution made by orbital paramagnetism, resulting from short-range order formation, is the reason of decrease in susceptibility of nonstoichiometric carbides during the ordering. Experimentally obtained data on susceptibility permitted evaluating short- and far-range order parameters in NbC y , TaC y , TiC y and HfC y carbides [ru

Short-range order in InSb amorphized under ion bombardment

International Nuclear Information System (INIS)

Pavlov, P.V.; Tetel'baum, D.I.; Gerasimov, A.I.

1979-01-01

The investigation of short-range order is carried out in polycrystal InSb films, irradiated with Ne + ions with E=150 keV and with the 2x10 15 ion/cm 2 dose. The data are obtained testifying to the film amorphization, the cause of which is the defect storage but not the local melting. Stability of the obtained amorphous phase at the room temperature is noted

In-situ radiation response of nickel--molybdenum alloys in an HVEM

International Nuclear Information System (INIS)

Carpenter, R.W.; Kenik, E.A.

1977-01-01

Experimental research has shown that perturbations of lattice periodicity caused by certain types of discrete precipitation or spinodal decomposition will suppress radiation-induced void swelling. The reported results extend this study to the Ni--Mo alloy system, in which certain alloy compositions contain short- or long-range order (SRO or LRO) and consequently modulations of the lattice periodicity

Short range order and phase separation in Ti-rich Ti-Al alloys

International Nuclear Information System (INIS)

Liew, H.J.

1999-01-01

of the reaction over a range of scales, from the atomic level on which order occurs through to large scale precipitates. Ti-15at%Al displays a phase separation mechanism involving both ordering and chemical phase decomposition which occurs in a time and temperature range that is readily accessible experimentally. Hence this alloy is an appropriate model system on which to conduct fundamental investigations into a complex decomposition mechanism and its kinetics. Both experimental and modelling results show that short range order develops rapidly in the alloy, and is followed by the formation and growth of congruent long range ordered regions of DO 19 structure. At a later stage composition variations form and increase in amplitude through a spinodal mechanism. From these findings, it cannot be ruled out that the observed decomposition sequence is due solely to the kinetics of ordering being more rapid than those of chemical phase separation. However, there are some indications which suggest that a thermodynamic criterion is operating, such that the onset of chemical phase separation occurs only after ordering has been achieved to some extent. The observed mechanism is fully consistent in appearance with the class of reactions known as conditional spinodals. (author)

Impurity-induced staggered polarization and antiferromagnetic order in spin-12 Heisenberg two-leg ladder compound SrCu2O3: Extensive Cu NMR and NQR studies

Science.gov (United States)

Ohsugi, S.; Tokunaga, Y.; Ishida, K.; Kitaoka, Y.; Azuma, M.; Fujishiro, Y.; Takano, M.

1999-08-01

We report characteristics of impurity-induced staggered polarization (IISP) and antiferromagnetic long-range order (AF-LRO) in the gapped spin-1/2 Heisenberg two-leg ladder compound SrCu2O3 (Sr123). We have carried out comprehensive NMR and NQR investigations on three impurity-doped systems, Sr(Cu1-xMx)2O3 (M=Zn, Ni) with xIISP along the leg was found to be much longer than ξ0/a in x=0.001 and 0.005. The notable result is that ξs/a that was found to be T independent is scaled to mean distances DAV=1/(2x) between the Zn and Ni impurities and DAV=1/x between the La impurities. When DAV=500 for x=0.001 (Zn doping), ξs/a~50 is estimated. The significantly broadened NQR spectrum has provided unambiguous evidence for the AF-LRO in the Zn and Ni doping (x=0.01 and 0.02). Rather uniform AF moments at the middle Cu sites between the impurities are estimated to be about 0.04μB at 1.4 K along the a axis. By assuming that exponential decay constants of AF moments are equivalent to ξs/a's for the IISP, the size of an AF moment next to the impurity is deduced as SAF~1/4. We propose that these exponential distributions of IISP and AF moments along the two-leg suggest that an interladder interaction is in a weakly coupled quasi-one-dimensional (WC-Q1D) regime. The formula of TN=J0exp(-DAV/(ξs/a)) based on the WC-Q1D model explains TN(exp)=3 K (x=0.01) and 5.8 K (x=0.02) quantitatively and predicts to be as small as TN=0.09 K for x=0.001 using J0=2000 K. On the other hand, there is no evidence of AF-LRO for the La doping (x=0.02 and 0.03) down to 1.4 K, nevertheless their ξs/a's are almost equivalent to those in the Zn and Ni doping (x=0.01 and 0.02). We remark that the Q1D-IISP is dramatically enhanced by the interladder interaction even though so weak, once the impurity breaks up the quantum coherence in the short-range resonating valence bond (RVB) state with the gap. On the one hand, we propose that TN is determined by a strength of the interladder interaction and a size

The 120° Ordered Phase of Triangular Lattice Antiferromagnetic Heisenberg Model with Long Range Couplings

International Nuclear Information System (INIS)

Zhan-Hai, Dong

2009-01-01

In order to look for the 120° order phase of triangular lattice Heisenberg antiferromagnet with long range couplings, the Hamiltonian is diagonalized with the Bogoliubov transformation within linear spin-wave approximation. It is found that when the long range spin couplings are taken into account, the transformation is valid only for certain regions in the spin coupling parameter space. These regions just correspond to the 120° (or Néel) ordered phase, which is very different from square lattice in terms of shape, size and topological property

Magnetic quasi-long-range ordering in nematic systems due to competition between higher-order couplings

Science.gov (United States)

Žukovič, Milan; Kalagov, Georgii

2018-05-01

Critical properties of the two-dimensional X Y model involving solely nematic-like terms of the second and third orders are investigated by spin-wave analysis and Monte Carlo simulation. It is found that, even though neither of the nematic-like terms alone can induce magnetic ordering, their coexistence and competition leads to an extended phase of the magnetic quasi-long-range-order phase, wedged between the two nematic-like phases induced by the respective couplings. Thus, except for the multicritical point, at which all the phases meet, for any finite value of the coupling parameters ratio there are two phase transition: one from the paramagnetic phase to one of the two nematic-like phases followed by another one at lower temperatures to the magnetic phase. The finite-size scaling analysis indicates that the phase transitions between the magnetic and nematic-like phases belong to the Ising and three-state Potts universality classes. Inside the competition-induced algebraic magnetic phase, the spin-pair correlation function is found to decay even much more slowly than in the standard X Y model with purely magnetic interactions. Such a magnetic phase is characterized by an extremely low vortex-antivortex pair density attaining a minimum close to the point at which the two couplings are of about equal strength.

Study of the effect of short ranged ordering on the magnetism in FeCr alloys

Energy Technology Data Exchange (ETDEWEB)

Jena, Ambika Prasad, E-mail: apjena@bose.res.in [Department of Condensed Matter and Materials Science, S N Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake City, Kolkata 700098 (India); Sanyal, Biplab, E-mail: biplab.sanyal@physics.uu.se [Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden); Mookerjee, Abhijit, E-mail: abhijit.mookerjee61@gmail.com [Department of Condensed Matter and Materials Science, S N Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake City, Kolkata 700098 (India)

2014-01-15

For the study of magnetism in systems where the local environment plays an important role, we propose a marriage between the Monte Carlo simulation and Zunger's special quasi-random structures. We apply this technique on disordered FeCr alloys and show that our estimates of the transition temperature is in good agreement with earlier experiments. - Highlights: • The magnetism in FeCr is sensitively depended on the ordering of the atoms : disordered or with short ranged ordering. • This work uses the SQS technique suggested by Zunger has been used to generate various degrees of short range ordering in FeCr. • The electronic structure and pair energies have been obatined from first principles ASR and Lichtenstein methods. • The effect of chemical ordering on magnetic ordering is studied in detail. • Only those situations where the chemical ordering is complete have been studied.

Study of the effect of short ranged ordering on the magnetism in FeCr alloys

International Nuclear Information System (INIS)

Jena, Ambika Prasad; Sanyal, Biplab; Mookerjee, Abhijit

2014-01-01

For the study of magnetism in systems where the local environment plays an important role, we propose a marriage between the Monte Carlo simulation and Zunger's special quasi-random structures. We apply this technique on disordered FeCr alloys and show that our estimates of the transition temperature is in good agreement with earlier experiments. - Highlights: • The magnetism in FeCr is sensitively depended on the ordering of the atoms : disordered or with short ranged ordering. • This work uses the SQS technique suggested by Zunger has been used to generate various degrees of short range ordering in FeCr. • The electronic structure and pair energies have been obatined from first principles ASR and Lichtenstein methods. • The effect of chemical ordering on magnetic ordering is studied in detail. • Only those situations where the chemical ordering is complete have been studied

Influence of short range chemical order on density of states in α-ZrNi

International Nuclear Information System (INIS)

Duarte Junior, J.

1986-01-01

Calculations of the density of electronic states for amorphous alloys of ZrNi and ZrCu with different chemical order degrees, in order to verify the effect of chemical ordering on this property, are presented. The results obtained for ZrCu shown that the density of states at Fermi level do not vary significantly with the ordering. The results for ZrNi shown that the introduction of short range chemical order can decrease significantly the density of states at Fermi level, leading to better agreement with experimental results. (M.C.K.) [pt

Polyamorphism and substructure of short-range order in amorphous boron films

International Nuclear Information System (INIS)

Palatnik, L.S.; Nechitajlo, A.A.; Koz'ma, A.A.

1981-01-01

The structure and substructure of boron amorphous films are studied in detail. Amorphous condensate of Bsup(a) boron is built of the same (but only disorientedly located) 12 B icosahedrons as boron crystalline modifications: B 105 -equilibrium β-rhombic, metastable: B 50 -tetragonal, B 12 -α-rhombohedral Coordination number for Bsup(a) (Z 1 =6.4) is lower than in B 105 (Z 1 =6.6) but higher than in B 50 modification (Z 1 =6.1). In crystalline modifications B 105 , B 50 , B 12 coordination numbers ω in first coordination spheres of icosahedrons are equal to ν 105 =6+4.6=10.6; ν 50 =10+3=14; ν 12 =6 respectively. Both amorphous modifications of boron Bsub(1)sup(a) and Bsub(15)sup(a) are analogs to B 50 in respect of the short-range order of icosahedron location. The difference between them is in ''substructure'' of short-range order: part of boron atoms (approximately 12%) do not occupy the vertices (so that vacancies appear) and enter the emptinesses between icosahedrons. In other words, the structure B 50 is the model basis of both amorphous phases [ru

Short-range second order screened exchange correction to RPA correlation energies

Science.gov (United States)

Beuerle, Matthias; Ochsenfeld, Christian

2017-11-01

Direct random phase approximation (RPA) correlation energies have become increasingly popular as a post-Kohn-Sham correction, due to significant improvements over DFT calculations for properties such as long-range dispersion effects, which are problematic in conventional density functional theory. On the other hand, RPA still has various weaknesses, such as unsatisfactory results for non-isogyric processes. This can in parts be attributed to the self-correlation present in RPA correlation energies, leading to significant self-interaction errors. Therefore a variety of schemes have been devised to include exchange in the calculation of RPA correlation energies in order to correct this shortcoming. One of the most popular RPA plus exchange schemes is the second order screened exchange (SOSEX) correction. RPA + SOSEX delivers more accurate absolute correlation energies and also improves upon RPA for non-isogyric processes. On the other hand, RPA + SOSEX barrier heights are worse than those obtained from plain RPA calculations. To combine the benefits of RPA correlation energies and the SOSEX correction, we introduce a short-range RPA + SOSEX correction. Proof of concept calculations and benchmarks showing the advantages of our method are presented.

Long-range order between the planets in the Solar system

DEFF Research Database (Denmark)

Bohr, Jakob; Olsen, Kasper

2010-01-01

The Solar System is investigated for positional correlations between the planets using a logarithmic distance scale. The pair correlation function for the logarithm of the semimajor axis shows a regular distribution with 5-7 consecutive peaks, and the Fourier transform hereof shows reciprocal peaks...... the number of data points is small. The pair correlation function of the permutated planets lacks the sequence of equidistant peaks and its Fourier transform has no second order peak. This analysis demonstrates the existence of longer ranged correlations in the Solar System....

Structure of the short-range atomic order of WO3 amorphous films

International Nuclear Information System (INIS)

Olevskij, S.S.; Sergeev, M.S.; Tolstikhina, A.L.; Avilov, A.S.; Shkornyakov, S.M.; Semiletov, S.A.

1984-01-01

To study the causes of electrochromism manifestation in thin tungsten oxide films, the structure of WO 3 amorphous films has been investigated. The films were obtained by three different methods: by W(CO) 6 tungsten carbonyl pyrolysis, by high-frequency ion-plasma sputtering of a target prepared by WO 3 powder sintering, and by WO 3 powder thermal evaporation. Monocrystalline wafers of silicon and sodium chloride were used as substrates. The structure of short-range order in WO 3 amorphous films varies versus, the method of preparation in compliance with the type of polyhedral elements, (WO 6 , WO 5 ) and with the character of their packing (contacts via edges or vertices). Manifestation of electroc ro mism in WO 3 films prepared by varions methods and having different structure of short-range order is supposed to be realized through various mechanisms. One cannot exclude a potential simultaneous effect of the two coloration mechanisms

Short- and medium-range order in a Zr73Pt27 glass: Experimental and simulation studies

International Nuclear Information System (INIS)

Wang, S.Y.; Wang, C.Z.; Li, M.Z.; Huang, L.; Ott, R.T.; Kramer, M.J.; Sordelet, D.J.; Ho, K.M.

2008-01-01

The structure of a Zr 73 Pt 27 metallic glass, which forms a Zr 5 Pt 3 (Mn 5 Si 3 -type) phase having local atomic clusters with distorted icosahedral coordination during the primary crystallization, has been investigated by means of x-ray diffraction and combining ab initio molecular-dynamics (MD) and reverse Monte Carlo (RMC) simulations. The ab initio MD simulation provides an accurate description of short-range structural and chemical ordering in the glass. A three-dimensional atomistic model of 18?000 atoms for the glass structure has been generated by the RMC method utilizing both the structure factor S(k) from x-ray diffraction experiment and the partial pair-correlation functions from ab initio MD simulation. Honeycutt and Andersen index and Voronoi cell analyses, respectively, were used to characterize the short- and medium-range order in the atomistic structure models generated by ab initio MD and RMC simulations. The ab initio results show that an icosahedral type of short-range order is predominant in the glass state. Furthermore, analysis of the atomic model from the constrained RMC simulations reveals that the icosahedral-like clusters are packed in arrangements having higher-order correlations, thus establishing medium-range topological order up to two or three cluster shells.

Intermediate-range chemical ordering of cations in molten RbCl-AgCl

Energy Technology Data Exchange (ETDEWEB)

Tahara, S. [Department of Physics and Earth Sciences, Faculty of Science, University of the Ryukyus, Okinawa 903-0213 (Japan); Research and Utilization Division, Japan Synchrotron Radiation Research Institute (JASRI, SPring-8), Hyogo 679-5198 (Japan); Kawakita, Y. [J-PARC Center, Japan Atomic Energy Agency (JAEA), Ibaraki 319-1195 (Japan); Shimakura, H. [Faculty of Pharmacy, Niigata University of Pharmacy and Applied Life Sciences, Niigata 956-8603 (Japan); Ohara, K. [Research and Utilization Division, Japan Synchrotron Radiation Research Institute (JASRI, SPring-8), Hyogo 679-5198 (Japan); Fukami, T. [Department of Physics and Earth Sciences, Faculty of Science, University of the Ryukyus, Okinawa 903-0213 (Japan); Takeda, S. [Department of Physics, Faculty of Sciences, Kyushu University, Fukuoka 812-8581 (Japan)

2015-07-28

A first sharp diffraction peak (FSDP) is observed in the X-ray total structure factor of a molten mixture of RbCl-AgCl, while both pure melts of RbCl and AgCl do not exhibit FSDP individually. Molecular dynamics simulations were performed to investigate the origin of the FSDP with the polarizable ion model (PIM). Coexistence of covalent Ag–Cl and ionic Rb–Cl bonds leads the system to evolve intermediate range ordering, which is simulated by introducing the induced polarization in different ways between Ag–Cl with fully polarizable treatment based on Vashishta-Raman potential and Rb–Cl with suppression over-polarization in the nearest neighbor contribution based on Born-Meyer potential. The partial structure factors for both the Ag–Ag and Rb–Rb correlations, S{sub AgAg}(Q) and S{sub RbRb}(Q), show a positive contribution to the FSDP, while S{sub AgRb}(Q) for the Ag–Rb correlation exhibits a negative contribution, indicating that Ag and Rb ions are distributed in an alternating manner within the intermediate-range length scale. The origin of the intermediate-range chemical ordering of cations can be ascribed to the preferred direction of the dipole moments of anions in the PIM.

Intermediate-range chemical ordering of cations in molten RbCl-AgCl

International Nuclear Information System (INIS)

Tahara, S.; Kawakita, Y.; Shimakura, H.; Ohara, K.; Fukami, T.; Takeda, S.

2015-01-01

A first sharp diffraction peak (FSDP) is observed in the X-ray total structure factor of a molten mixture of RbCl-AgCl, while both pure melts of RbCl and AgCl do not exhibit FSDP individually. Molecular dynamics simulations were performed to investigate the origin of the FSDP with the polarizable ion model (PIM). Coexistence of covalent Ag–Cl and ionic Rb–Cl bonds leads the system to evolve intermediate range ordering, which is simulated by introducing the induced polarization in different ways between Ag–Cl with fully polarizable treatment based on Vashishta-Raman potential and Rb–Cl with suppression over-polarization in the nearest neighbor contribution based on Born-Meyer potential. The partial structure factors for both the Ag–Ag and Rb–Rb correlations, S AgAg (Q) and S RbRb (Q), show a positive contribution to the FSDP, while S AgRb (Q) for the Ag–Rb correlation exhibits a negative contribution, indicating that Ag and Rb ions are distributed in an alternating manner within the intermediate-range length scale. The origin of the intermediate-range chemical ordering of cations can be ascribed to the preferred direction of the dipole moments of anions in the PIM

Surface and finite size effect on fluctuations dynamics in nanoparticles with long-range order

Science.gov (United States)

Morozovska, A. N.; Eliseev, E. A.

2010-02-01

The influence of surface and finite size on the dynamics of the order parameter fluctuations and critical phenomena in the three-dimensional (3D)-confined systems with long-range order was not considered theoretically. In this paper, we study the influence of surface and finite size on the dynamics of the order parameter fluctuations in the particles of arbitrary shape. We consider concrete examples of the spherical and cylindrical ferroic nanoparticles within Landau-Ginzburg-Devonshire phenomenological approach. Allowing for the strong surface energy contribution in micro and nanoparticles, the analytical expressions derived for the Ornstein-Zernike correlator of the long-range order parameter spatial-temporal fluctuations, dynamic generalized susceptibility, relaxation times, and correlation radii discrete spectra are different from those known for bulk systems. Obtained analytical expressions for the correlation function of the order parameter spatial-temporal fluctuations in micro and nanosized systems can be useful for the quantitative analysis of the dynamical structural factors determined from magnetic resonance diffraction and scattering spectra. Besides the practical importance of the correlation function for the analysis of the experimental data, derived expressions for the fluctuations strength determine the fundamental limits of phenomenological theories applicability for 3D-confined systems.

Evolution of short range order in Ar: Liquid to glass and solid transitions-A computational study

Science.gov (United States)

Shor, Stanislav; Yahel, Eyal; Makov, Guy

2018-04-01

The evolution of the short range order (SRO) as a function of temperature in a Lennard-Jones model liquid with Ar parameters was determined and juxtaposed with thermodynamic and kinetic properties obtained as the liquid was cooled (heated) and transformed between crystalline solid or glassy states and an undercooled liquid. The Lennard-Jones system was studied by non-equilibrium molecular dynamics simulations of large supercells (approximately 20000 atoms) rapidly cooled or heated at selected quenching rates and at constant pressure. The liquid to solid transition was identified by discontinuities in the atomic volume and molar enthalpy; the glass transition temperature range was identified from the temperature dependence of the self-diffusion. The SRO was studied within the quasi-crystalline model (QCM) framework and compared with the Steinhardt bond order parameters. Within the QCM it was found that the SRO evolves from a bcc-like order in the liquid through a bct-like short range order (c/a=1.2) in the supercooled liquid which persists into the glass and finally to a fcc-like ordering in the crystalline solid. The variation of the SRO that results from the QCM compares well with that obtained with Steinhardt's bond order parameters. The hypothesis of icosahedral order in liquids and glasses is not supported by our results.

Influence of short range ordering and clustering on transport properties

International Nuclear Information System (INIS)

Vigier, G.; Pelletier, J.M.

1982-01-01

The influence of short range ordering and clustering phenomena on the electrical resistivity p and the thermopower S is investigated both theoretically and experimentally. According to the considered alloys either increases or decreases of transport properties may be observed when deviations from a random distribution of solute atoms occur. These observations are explained with a model based on free electrons and Born approximations the importance of the potential choice is underlined; two kinds of description of the structure factor are investigated. A good semiquantitative agreement is obtained between computed results and experimental observations

Finite temperature CPN-1 model and long range Neel order

International Nuclear Information System (INIS)

Ichinose, Ikuo; Yamamoto, Hisashi.

1989-09-01

We study in d space-dimensions the finite temperature behavior of long range Neel order (LRNO) in CP N-1 model as a low energy effective field theory of the antiferromagnetic Heisenberg model. For d≤1, or d≤2 at any nonzero temperature, LRNO disappears, in agreement with Mermin-Wagner-Coleman's theorem. For d=3 in the weak coupling region, LRNO exists below the critical temperature T N (Neel temperature). T N decreases as the interlayer coupling becomes relatively weak compared with that within Cu-O layers. (author)

Free Space Laser Communication Experiments from Earth to the Lunar Reconnaissance Orbiter in Lunar Orbit

Science.gov (United States)

Sun, Xiaoli; Skillman, David R.; Hoffman, Evan D.; Mao, Dandan; McGarry, Jan F.; Zellar, Ronald S.; Fong, Wai H; Krainak, Michael A.; Neumann, Gregory A.; Smith, David E.

2013-01-01

Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. The experiments used 4096-ary pulse position modulation (PPM) for the laser pulses during one-way LRO Laser Ranging (LR) operations. Reed-Solomon forward error correction codes were used to correct the PPM symbol errors due to atmosphere turbulence and pointing jitter. The signal fading was measured and the results were compared to the model.

Polarization control of high order harmonics in the EUV photon energy range.

Science.gov (United States)

Vodungbo, Boris; Barszczak Sardinha, Anna; Gautier, Julien; Lambert, Guillaume; Valentin, Constance; Lozano, Magali; Iaquaniello, Grégory; Delmotte, Franck; Sebban, Stéphane; Lüning, Jan; Zeitoun, Philippe

2011-02-28

We report the generation of circularly polarized high order harmonics in the extreme ultraviolet range (18-27 nm) from a linearly polarized infrared laser (40 fs, 0.25 TW) focused into a neon filled gas cell. To circularly polarize the initially linearly polarized harmonics we have implemented a four-reflector phase-shifter. Fully circularly polarized radiation has been obtained with an efficiency of a few percents, thus being significantly more efficient than currently demonstrated direct generation of elliptically polarized harmonics. This demonstration opens up new experimental capabilities based on high order harmonics, for example, in biology and materials science. The inherent femtosecond time resolution of high order harmonic generating table top laser sources renders these an ideal tool for the investigation of ultrafast magnetization dynamics now that the magnetic circular dichroism at the absorption M-edges of transition metals can be exploited.

Range-separated time-dependent density-functional theory with a frequency-dependent second-order Bethe-Salpeter correlation kernel

Energy Technology Data Exchange (ETDEWEB)

Rebolini, Elisa, E-mail: elisa.rebolini@kjemi.uio.no; Toulouse, Julien, E-mail: julien.toulouse@upmc.fr [Laboratoire de Chimie Théorique, Sorbonne Universités, UPMC Univ Paris 06, CNRS, 4 place Jussieu, F-75005 Paris (France)

2016-03-07

We present a range-separated linear-response time-dependent density-functional theory (TDDFT) which combines a density-functional approximation for the short-range response kernel and a frequency-dependent second-order Bethe-Salpeter approximation for the long-range response kernel. This approach goes beyond the adiabatic approximation usually used in linear-response TDDFT and aims at improving the accuracy of calculations of electronic excitation energies of molecular systems. A detailed derivation of the frequency-dependent second-order Bethe-Salpeter correlation kernel is given using many-body Green-function theory. Preliminary tests of this range-separated TDDFT method are presented for the calculation of excitation energies of the He and Be atoms and small molecules (H{sub 2}, N{sub 2}, CO{sub 2}, H{sub 2}CO, and C{sub 2}H{sub 4}). The results suggest that the addition of the long-range second-order Bethe-Salpeter correlation kernel overall slightly improves the excitation energies.

EXAFS study of short range order in Fe-Zr amorphous alloys

International Nuclear Information System (INIS)

Fernandez-Gubieda, M.L.; Gorria, P.; Barandiaran, J.M.; Barquin, L.F.

1995-01-01

Room temperature X-ray absorption spectra on Fe K-edge have been performed in Fe 100-x-y Zr x B y and Fe 86 Zr 7 Cu 1 B 6 alloys (x=7, 7.7, 9; y=0, 2, 4, 6). Fe-Fe coordination number and interatomic distances do not change in any sample. However, small changes in the Fe-Zr short range order, which could explain the evolution of the magnetic properties, have been observed. (orig.)

Long range ordered alloys modified by addition of niobium and cerium

International Nuclear Information System (INIS)

Liu, C.T.

1987-01-01

A long range ordered alloy composition is described consisting essentially of iron, nickel, cobalt, vanadium and a ductility enhancing metal, having the nominal composition (Fe, Ni,Co)/sub 3/(V,M) where M is the ductility enhancing metal selected from the group Ti, Zr, Hf and mixtures thereof. Effective amounts of creep property enhance elements selected from the group cerium, niobium and mixtures thereof sufficient to enhance creep properties in the resulting alloy without adversely affecting the fabrication of the alloy

Shiga toxin induces membrane reorganization and formation of long range lipid order

DEFF Research Database (Denmark)

Solovyeva, Vita; Johannes, Ludger; Simonsen, Adam Cohen

2015-01-01

membrane reordering. When Shiga toxin was added above the lipid chain melting temperature, the toxin interaction with the membrane induced rearrangement and clustering of Gb3 lipids that resulted in the long range order and alignment of lipids in gel domains. The toxin induced redistribution of Gb3 lipids...... inside gel domains is governed by the temperature at which Shiga toxin was added to the membrane: above or below the phase transition. The temperature is thus one of the critical factors controlling lipid organization and texture in the presence of Shiga toxin. Lipid chain ordering imposed by Shiga toxin...... binding can be another factor driving the reconstruction of lipid organization and crystallization of lipids inside gel domains....

Direct separation of short range order in intermixed nanocrystalline and amorphous phases

International Nuclear Information System (INIS)

Frenkel, Anatoly I.; Kolobov, Alexander V.; Robinson, Ian K.; Cross, Julie O.; Maeda, Yoshihito; Bouldin, Charles E.

2002-01-01

Diffraction anomalous fine-structure (DAFS) and extended x-ray absorption fine-structure (EXAFS) measurements were combined to determine short range order (SRO) about a single atomic type in a sample of mixed amorphous and nanocrystalline phases of germanium. EXAFS yields information about the SRO of all Ge atoms in the sample, while DAFS determines the SRO of only the ordered fraction. We determine that the first-shell distance distribution is bimodal; the nanocrystalline distance is the same as the bulk crystal, to within 0.01(2) A ring , but the mean amorphous Ge-Ge bond length is expanded by 0.076(19) Angstrom. This approach can be applied to many systems of mixed amorphous and nanocrystalline phases

The LRO Diviner Foundation Dataset: A Comprehensive Temperature Record of the Moon

Science.gov (United States)

Sefton-Nash, E.; Aye, K. M.; Williams, J. P.; Greenhagen, B. T.; Sullivan, M.; Paige, D. A.

2014-12-01

The Diviner Lunar Radiometer Experiment aboard NASA's Lunar Reconnaissance Orbiter (LRO) has been systematically mapping the thermal state of the Moon at a mean rate of >1400 observations/second since July 2009. Diviner measures solar reflectance and infrared radiance in 9 spectral channels with bandpasses from 0.3 - 400 μm. With more than 5 years of continuous data, complete spatial coverage of the lunar surface is achieved multiple times and coverage of local solar time enables the diurnal curve to be well-resolved for a given subsolar point. The Diviner Foundation Dataset (FDS) represents a coordinated effort to recalibrate raw data to improve quality, and produce a definitive and comprehensive set of products for use by the lunar science community. We present the contents and organization of the FDS, background on the enhanced processing pipeline, show how it is retrieved from NASA's Planetary Data System, and demonstrate its use with common mapping & analysis tools. The FDS comprises level 1 Reduced Data Records (RDRs) and level 2/3 Gridded Data Records (GDRs). We produce new RDRs using improved calibration algorithms that remove instrument artifacts and improve accuracy of measured radiance, particularly for polar data in permanently shadowed regions. GDRs are built using a per-orbit gridding scheme, and data are sourced from a database constructed by modeling the effective field-of-view for each observation. Notable gridded products available for lunar science include: 1) Globally mapped brightness temperatures for all channels in tiled cylindrical and polar stereographic map projections, 2) Global hourly temperature snapshots - maps of bolometric temperature binned into 1 hour intervals of local time, 3) Topographic products (elevation, slope and azimuth) for each map tile, that represent the terrain model used to process the data, and 4) Accompanying gridded maps of auxiliary quantities such as emission angle, local solar time, error etc…, for filtering

Order of current variance and diffusivity in the rate one totally asymmetric zero range process

NARCIS (Netherlands)

Balázs, M.; Komjáthy, J.

2008-01-01

We prove that the variance of the current across a characteristic is of order t 2/3 in a stationary constant rate totally asymmetric zero range process, and that the diffusivity has order t 1/3. This is a step towards proving universality of this scaling behavior in the class of one-dimensional

Determination of thermodynamical coefficients for Mo-W alloys according to short-range order parameters

International Nuclear Information System (INIS)

Erokhin, L.N.; Mokrov, A.P.; Shivrin, O.N.; Khanina, N.I.

1986-01-01

A method is proposed for determining thermodynamical coefficients according to short-range order parameters. The method approbation for Mo-W alloys has shown a good agreement between the thermodynamical and diffusion data. The Mo-W system in the concentration range under study is close to the ideal one. The calculated relative error of determination of interdiffusion coefficients in alloys of the Mo-W system does not exceed 16%

Distinct Short-Range Order Is Inherent to Small Amorphous Calcium Carbonate Clusters (<2 nm)

Energy Technology Data Exchange (ETDEWEB)

Sun, Shengtong [Physical Chemistry, University of Konstanz, Universitätsstrasse 10 78457 Konstanz Germany; School of Chemical Engineering, State Key Laboratory of Chemical Engineering, Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 130 Meilong Road Shanghai 200237 P.R. China; Chevrier, Daniel M. [Department of Chemistry and Institute for Research in Materials, Dalhousie University, Halifax Nova Scotia B3H 4R2 Canada; Zhang, Peng [Department of Chemistry and Institute for Research in Materials, Dalhousie University, Halifax Nova Scotia B3H 4R2 Canada; Gebauer, Denis [Physical Chemistry, University of Konstanz, Universitätsstrasse 10 78457 Konstanz Germany; Cölfen, Helmut [Physical Chemistry, University of Konstanz, Universitätsstrasse 10 78457 Konstanz Germany

2016-09-09

Amorphous intermediate phases are vital precursors in the crystallization of many biogenic minerals. While inherent short-range orders have been found in amorphous calcium carbonates (ACCs) relating to different crystalline forms, it has never been clarified experimentally whether such orders already exist in very small clusters less than 2 nm in size. Here, we studied the stability and structure of 10,12-pentacosadiynoic acid (PCDA) protected ACC clusters with a core size of ca. 1.4 nm consisting of only seven CaCO₃ units. Ligand concentration and structure are shown to be key factors in stabilizing the ACC clusters. More importantly, even in such small CaCO₃ entities, a proto-calcite short-range order can be identified but with a relatively high degree of disorder that arises from the very small size of the CaCO₃ core. Our findings support the notion of a structural link between prenucleation clusters, amorphous intermediates, and final crystalline polymorphs, which appears central to the understanding of polymorph selection.

Short range order of Mg-Cd-alloys during the transition from the solid to the molten state

International Nuclear Information System (INIS)

Boos, A.; Steeb, S.

1977-01-01

Recently a method was published for the determination of short range order parameters in binary melts and also a method for the determination of the concentration of different structures which form such a melt. These methods are used in the present work to evaluate the atomic structure of Mg-Cd-melts and to reval the changes in short range order during the melting process. (orig.) [de

Short-range order of amorphous FeNiB alloy after neutron irradiation

International Nuclear Information System (INIS)

Miglierini, M.; Sitek, J.; Baluch, S.; Cirak, J.; Lipka, J.

1990-01-01

Transmission Moessbauer spectroscopy was used to study irradiation-induced changes in the short-range order of an amorphous Fe 80-x Ni x B 20 alloy. Neutron irradiation led to an increase of the width of a hyperfine field distribution implying atomic rearrangement towards disordering. Changes in a mean value of a HFD and Moessbauer line areas can be associated with a reorientation of spins due to radiation damage. (orig.)

Choosing order of operations to accelerate strip structure analysis in parameter range

Science.gov (United States)

Kuksenko, S. P.; Akhunov, R. R.; Gazizov, T. R.

2018-05-01

The paper considers the issue of using iteration methods in solving the sequence of linear algebraic systems obtained in quasistatic analysis of strip structures with the method of moments. Using the analysis of 4 strip structures, the authors have proved that additional acceleration (up to 2.21 times) of the iterative process can be obtained during the process of solving linear systems repeatedly by means of choosing a proper order of operations and a preconditioner. The obtained results can be used to accelerate the process of computer-aided design of various strip structures. The choice of the order of operations to accelerate the process is quite simple, universal and could be used not only for strip structure analysis but also for a wide range of computational problems.

Dale Sayers Festschrift

International Nuclear Information System (INIS)

Stern, Edward A.

2007-01-01

This Festschrift is in honor of Dale Sayers who passed away in November 2004. Dale played a pivotal role in initiating the modern era of X-ray Absorption Fine Structure (XAFS) 35 years ago. The prehistory of XAFS before the modern era consisted of 40 years of confusion caused by Kronig's two different theories of the extended XAFS (EXAFS), the Short-Range Order (SRO) and Long-Range Order (LRO) theories. Dale's PhD thesis on EXAFS led to the idea of a Fourier transform to definitely prove that SRO is the correct theory and then to the development of XAFS as a structure determination technique

Neutron diffraction study on the medium and short-range order of ternary chalcogenide glasses

Czech Academy of Sciences Publication Activity Database

Neov, S.; Gerasimova, I.; Skordeva, E.; Arsova, D.; Pamukchieva, V.; Mikula, Pavol; Lukáš, Petr; Sonntag, R.

1999-01-01

Roč. 34, - (1999), s. 3669-3676 ISSN 0022-2461 R&D Projects: GA ČR GV202/97/K038 Keywords : neutron diffraction * short-range order * chalcogenide glasses Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.786, year: 1999

Polariton Chimeras: Bose-Einstein Condensates with Intrinsic Chaoticity and Spontaneous Long-Range Ordering

Science.gov (United States)

Gavrilov, S. S.

2018-01-01

The system of cavity polaritons driven by a plane electromagnetic wave is found to undergo the spontaneous breaking of spatial symmetry, which results in a lifted phase locking with respect to the driving field and, consequently, in the possibility of internal ordering. In particular, periodic spin and intensity patterns arise in polariton wires; they exhibit strong long-range order and can serve as media for signal transmission. Such patterns have the properties of dynamical chimeras: they are formed spontaneously in perfectly homogeneous media and can be partially chaotic. The reported new mechanism of chimera formation requires neither time-delayed feedback loops nor nonlocal interactions.

A first-principles study of short range order in Cu-Zn

International Nuclear Information System (INIS)

Slutter, M.; Turchi, P.E.A.; Johnson, D.D.; Nicholson, D.M.; Stocks, G.M.; Pinski, F.J.

1990-01-01

Recently, measurements of short-range order (SRO) diffuse neutron scattering intensity have been performed on quenched Cu-Zn alloys with 22.4 to 31.1 atomic percent (a/o) Zn, and pair interactions were obtained by inverse Monte Carlo simulation. These results are compared to SRO intensities and effective pair interactions obtained from first-principles electronic structure calculations. The theoretical SRO intensities were calculated with the cluster variation method (CVM) in the tetrahedron-octahedron approximation with first-principles pain interactions as input. More generally, phase stability in the Cu-Zn alloy system is discussed, using ab-initio energetic properties

Study of short range order in alloy of glassy metals and effect of neutron irradiation on them

International Nuclear Information System (INIS)

Habibi, S.; Banaee, N.; Salman, M.; Gupta, A.; Principi, G.

2000-04-01

In this paper, we have studied a series of glassy metals with composition Fe 78-x Ni x Si 8 B 14 with x=0, 15, 25,38,53, 58. We have used Moessbauer spectroscopy to get information about short range order and local structure in these alloys. The specimens are exposed to neutron irradiation to perturb local structure and their short range order. The hyperfine parameters obtained from spectra before and after n-irradiation and are compared

Crossover phenomena in the critical range near magnetic ordering transition

Science.gov (United States)

Köbler, U.

2018-05-01

Among the most important issues of Renormalization Group (RG) theory are crossover events and relevant (or non-relevant) interactions. These terms are unknown to atomistic theories but they will be decisive for future field theories of magnetism. In this experimental study the importance of these terms for the critical dynamics above and below magnetic ordering transition is demonstrated on account of new analyses of published data. When crossover events are overlooked and critical data are fitted by a single power function of temperature over a temperature range including a crossover event, imprecise critical exponents result. The rather unsystematic and floating critical exponents reported in literature seem largely to be due to this problem. It is shown that for appropriate data analyses critical exponents are obtained that are to a good approximation rational numbers. In fact, rational critical exponents can be expected when spin dynamics is controlled by the bosons of the continuous magnetic medium (Goldstone bosons). The bosons are essentially magnetic dipole radiation generated by the precessing spins. As a result of the here performed data analyses, critical exponents for the magnetic order parameter of β = 1/2, 1/3, 1/4 and 1/6 are obtained. For the critical paramagnetic susceptibility the exponents are γ = 1 and γ = 4/3.

Changes in structure of the short-range order of the InP melt when heated

International Nuclear Information System (INIS)

Glazov, V.M.; Dovletov, K.; Nashel'skij, A.Ya.; Mamedov, M.M.

1977-01-01

An investigation of the temperature dependence of the InP viscosity has indicated an ''after-melting'' effect similar to that observed in other A 3 V 5 compounds having a sphalerite structure. The termodynamic parameters of the viscous flow of indium phosphide melt have been calculated, and a suggestion has been made on the loosening of the short-range order structure of the melt during the period preceding solidification. With the similarity in the behaviour of InP and of A 3 Sb compound melts as a basis, a suggestion has been put forward that the influence of the thermal dissociation upon the character of the changes in the short-range order structure directly after transition from the solid to the liquid phase is negligible

Interlayer exchange coupling in Er|Tb superlattices mediated by short range incommensurate Er order

International Nuclear Information System (INIS)

Pfuhl, E; Brueckel, T; Voigt, J; Mattauch, S; Korolkov, D

2010-01-01

We study the magnetic correlations in Er|Tb superlattices by means of off-specular scattering of polarized neutrons. We show here the co-existence of inhomogeneous magnetic states: i) ferromagnetic order of moments within the Tb layers below 230 K (FM), correlation length of about 10 bilayer, ii) an incommensurate modulated magnetic order, restricted to single Er layers and iii) antiferromagnetic coupling of ferromagnetic layers below 70K (AFC). Polarised off-specular neutron scattering under grazing incidence reveals that i) magnetic fluctuations appear when the sample is cooled below 70 K, ii) these fluctuations lead to AFC, when the sample is cooled to 10 K, which iii) persists, when the sample is subsequently heated up to 45 K, while the order is not present during the cooling cycle. Also the short range incommensurate order changes accordingly, implying that the magnetic order in the Er layers mediates the interlayer coupling between ferromagnetic Tb layers.

Short range order of selenite glasses

Czech Academy of Sciences Publication Activity Database

Neov, S.; Gerasimova, I.; Yordanov, S.; Lakov, L.; Mikula, Pavol; Lukáš, Petr

1999-01-01

Roč. 40, č. 2 (1999), s. 111-112 ISSN 0031-9090 R&D Projects: GA AV ČR KSK1010104 Keywords : short range * selenite glasses Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.822, year: 1999

Anomalous X-ray scattering studies of short-, intermediate- and extended-range order in glasses

International Nuclear Information System (INIS)

Price, D.L.; Saboungi, M.L.; Armand, P.; Cox, D.E.

1998-01-01

The authors present the formalism of anomalous x-ray scattering as applied to partial structure analysis of disordered materials, and give an example of how the technique has been applied, together with that of neutron diffraction, to investigate short-, intermediate- and extended-range order in vitreous germania and rubidium germanate

Coexisting Kondo singlet state with antiferromagnetic long-range order: A possible ground state for Kondo insulators

International Nuclear Information System (INIS)

Zhang Guangming; Yu Lu

2000-04-01

The ground-state phase diagram of a half-filled anisotropic Kondo lattice model is calculated within a mean-field theory. For small transverse exchange coupling J perpendicular perpendicular c1 , the ground state shows an antiferromagnetic long-range order with finite staggered magnetizations of both localized spins and conduction electrons. When J perpendicular > J perpendicular c2 , the long-range order is destroyed and the system is in a disordered Kondo singlet state with a hybridization gap. Both ground states can describe the low-temperature phases of Kondo insulating compounds. Between these two distinct phases, there may be a coexistent regime as a result of the balance between local Kondo screening and magnetic interactions. (author)

Tuning anomalous Hall conductivity in L1[sub 0] FePt films by long range chemical ordering

KAUST Repository

Chen, M.; Shi, Z.; Xu, W. J.; Zhang, Xixiang; Du, J.; Zhou, S. M.

2011-01-01

For L10 FePt films, the anomalous Hall conductivity σ xy=-a σxx-b, where a=a0f(T), b=b 0f(T), and f (T) is the temperature dependence factor of the spontaneous magnetization. With increasing chemical long range ordering S, a0 changes its sign accompanied by a reduction of its magnitude and b0 increases monotonically. The spin-orbit coupling strength is suggested to increase with increasing S. As an approach, the long range chemical ordering can be used to control the anomalous Hall effect in ferromagnetic alloy films. © 2011 American Institute of Physics.

Tuning anomalous Hall conductivity in L1[sub 0] FePt films by long range chemical ordering

KAUST Repository

Chen, M.

2011-02-24

For L10 FePt films, the anomalous Hall conductivity σ xy=-a σxx-b, where a=a0f(T), b=b 0f(T), and f (T) is the temperature dependence factor of the spontaneous magnetization. With increasing chemical long range ordering S, a0 changes its sign accompanied by a reduction of its magnitude and b0 increases monotonically. The spin-orbit coupling strength is suggested to increase with increasing S. As an approach, the long range chemical ordering can be used to control the anomalous Hall effect in ferromagnetic alloy films. © 2011 American Institute of Physics.

On the number of free energy extremums of a solid solution with two long-range order parameters

International Nuclear Information System (INIS)

Dateshidze, N.A.; Ratishvili, I.G.

1977-01-01

The free energy of ordering f.c.c. lattice solid solution is investigated. The ordering is regarded as homogeneous in the whole bulk of the crystal (i.e. resistant towards formation of antiphase domains). It is described by one of the appropriate distribution functions which contains two long-range order parameters. The calculations have revealed the extrema of the free energy function, and their shape and behaviour upon variations of temperature are analyzed. It is shown that under certain circumstances the system can display more than one minimum of free energy within the ordered phase

Structural evolution on medium-range-order during the fragile-strong transition in Ge_1_5Te_8_5

International Nuclear Information System (INIS)

Wei, Shuai; Stolpe, Moritz; Gross, Oliver; Hembree, William; Hechler, Simon; Bednarcik, Jozef; Busch, Ralf; Lucas, Pierre

2017-01-01

Using synchrotron X-ray scattering, we investigate liquid Ge_1_5Te_8_5 spanning a wide temperature range from near T_g to the melt, and demonstrate that the density anomaly and fragile-strong transition are not only related to short-range-order (SRO) structural change (e.g. Peierls-like distortion), but also accompanied by a remarkable development of medium-range-order (MRO). The latter manifests as an emerging pre-peak in total structure factor S(Q) and atomic pair correlations on the length scale of ∼8 Å in the real space G(r) function. The results highlight the role of medium-range structural ordering in the evolution of the configurational entropy which, according to the Adam-Gibbs theory, can be linked to the fragile-strong transition (FS-transition). Based on the relation between structure and liquid dynamics, the FS-transitions at high pressures are examined in terms of experimental data and the Ehrenfest relation. This work identifies the length scale for the atomic correlations in MRO structural evolutions and presents a structural approach to exploring liquid dynamics, which may be useful for investigating relevant phase-change alloys.

Short-range order and local conservation of quantum numbers in multiparticle production

International Nuclear Information System (INIS)

Le Bellac, M.

1976-01-01

These lectures discuss the implications of the hypotheses of short-range order (SRO) and local conservation of quantum numbers (LCQN) for multiple production of elementary particles at high energies. The consequences of SRO for semi-inclusive correlations and the distribution of rapidity gaps are derived, essentially in the framework of the cluster model. Then the experimental status of local conservation of charge and transverse momentum is reviewed. Finally, by making use of the unitarity relation, it is shown that LCQN has important consequences for the elastic amplitude. The derivation is given both in a model-independent way, and in specific multiperiheral models. (Author)

Thermodynamics and Long-Range Order of Nitrogen in γ'-Fe4N1-x

NARCIS (Netherlands)

Kooi, Bart J.; Somers, Marcel A.J.; Mittemeijer, Eric J.

1996-01-01

Models are given for the description of the chemical potential of nitrogen in γ'-Fe4N1-x. In previous work, γ'-Fe4N1-x was treated as a (sub)regular solution, thereby assuming that the N atoms are distributed randomly on the sites of their own sublattice. However, in γ'-Fe4N1-x, long-range ordering

Monte Carlo simulation of atomic short range order and cluster formation in two dimensional model alloys

International Nuclear Information System (INIS)

Rojas T, J.; Instituto Peruano de Energia Nuclear, Lima; Manrique C, E.; Torres T, E.

2002-01-01

Using monte Carlo simulation have been carried out an atomistic description of the structure and ordering processes in the system Cu-Au in a two-dimensional model. The ABV model of the alloy is a system of N atoms A and B, located in rigid lattice with some vacant sites. In the model we assume pair wise interactions between nearest neighbors with constant ordering energy J = 0,03 eV. The dynamics was introduced by means of a vacancy that exchanges of place with any atom of its neighbors. The simulations were carried out in a square lattice with 1024 and 4096 particles, using periodic boundary conditions to avoid border effects. We calculate the first two parameters of short range order of Warren-Cowley as function of the concentration and temperature. It was also studied the probabilities of formation of different atomic clusters that consist of 9 atoms as function of the concentration of the alloy and temperatures in a wide range of values. In some regions of temperature and concentration it was observed compositional and thermal polymorphism

Impact of medium-range order on the glass transition in liquid Ni-Si alloys

Science.gov (United States)

Lü, Y. J.; Entel, P.

2011-09-01

We study the thermophysical properties and structure of liquid Ni-Si alloys using molecular dynamics simulations. The liquid Ni-5% and 10%Si alloys crystallize to form the face-centered cubic (Ni) at 900 and 850 K, respectively, and the glass transitions take place in Ni-20% and 25%Si alloys at about 700 K. The temperature-dependent self-diffusion coefficients and viscosities exhibit more pronounced non-Arrhenius behavior with the increase of Si content before phase transitions, indicating the enhanced glass-forming ability. These appearances of thermodynamic properties and phase transitions are found to closely relate to the medium-range order clusters with the defective face-centered cubic structure characterized by both local translational and orientational order. This locally ordered structure tends to be destroyed by the addition of more Si atoms, resulting in a delay of nucleation and even glass transition instead.

Electron irradiation effect on short-range ordering in Cu-Al and Ag-Al alloys

International Nuclear Information System (INIS)

Kulish, N.P.; Mel'nikova, N.A.; Petrenko, P.V.; Ryabishchuk, A.L.; Tatarov, A.A.

1990-01-01

Method of X-ray diffuse scattering is used to study short-range order variation in Cu-Al and Ag-Al alloys under radiation effect and the following heat treatment. Irradiation was carried out at -40 deg C by 1.6 MeV electrons, fluence of 5x10 7 cm -2 and 0.5 MeV gamma-rays, the dose being 10 7 pH

Local coordination and medium range order in molten trivalent metal chlorides: The role of screening by the chlorine component

International Nuclear Information System (INIS)

Pastore, G.; Tosi, M.P.

1995-11-01

Earlier work has identified the metal ion size R M as a relevant parameter in determining the evolution of the liquid structure of trivalent metal chlorides across the series from LaCl 3 (R M approx. 1.4 A) to AlCl 3 (R M approx. 0.8 A). Here we highlight the structural role of the chlorines by contrasting the structure of fully equilibrated melts with that of disordered systems obtained by quenching the chlorine component. Main attention is given to how the suppression of screening of the polyvalent ions by the chlorines changes trends in the local liquid structure (first neighbour coordination and partial radial distribution functions) and in the intermediate range order (first sharp diffraction peak in the partial structure factors). The main microscopic consequences of structural quenching of the chlorine component are a reduction in short range order and an enhancement of intermediate range order in the metal ion component, as well as the suppression of a tendency to molecular-type states at the lower end of the range of R M . (author). 23 refs, 6 figs

Formation and transformation of a short range ordered iron carbonate precursor

DEFF Research Database (Denmark)

Dideriksen, Knud; Frandsen, Cathrine; Bovet, Nicolas

2015-01-01

(II) with varying pH produced broad peaks in X-ray diffraction and contained dominantly Fe and CO3 when probed with X-ray photoelectron spectroscopy. Reduced pair distribution function (PDF) analysis shows only peaks corresponding to interatomic distances below 15Å, reflecting a material with no long range...... structural order. Moreover, PDF peak positions differ from those for known iron carbonates and hydroxides. Mössbauer spectra also deviate from those expected for known iron carbonates and suggest a less crystalline structure. These data show that a previously unidentified iron carbonate precursor phase...... formed. Its coherent scattering domains determined from PDF analysis are slightly larger than for amorphous calcium carbonate, suggesting that the precursor could be nanocrystalline. Replica exchange molecular dynamics simulations of Fe-carbonate polynuclear complexes yield PDF peak positions that agree...

Short-range order in the quantum XXZ honeycomb lattice material BaCo2(PO4)2

Science.gov (United States)

Nair, Harikrishnan S.; Brown, J. M.; Coldren, E.; Hester, G.; Gelfand, M. P.; Podlesnyak, A.; Huang, Q.; Ross, K. A.

2018-04-01

We present observations of highly frustrated quasi-two-dimensional (2D) magnetic correlations in the honeycomb lattice layers of the Seff =1 /2 compound γ -BaCo2(PO4)2 (γ -BCPO). Specific heat shows a broad peak comprised of two weak kink features at TN 1˜6 K and TN 2˜3.5 K, the relative weights of which can be modified by sample annealing. Neutron powder diffraction measurements reveal short range quasi-2D order that is established below TN 1 and TN 2, at which two separate, incompatible, short range magnetic orders onset: commensurate antiferromagnetic correlations with correlation length ξc=60 ±2 Å (TN 1) and in quasi-2D helical domains with ξh=350 ±11 Å (TN 2). The ac magnetic susceptibility response lacks frequency dependence, ruling out spin freezing. Inelastic neutron scattering data on γ -BCPO is compared with linear spin wave theory, and two separate parameter regions of the XXZ J1-J2-J3 model with ferromagnetic nearest-neighbor exchange J1 are favored, both near regions of high classical degeneracy. High energy coherent excitations (˜10 meV) persist up to at least 40 K, suggesting strong in-plane correlations persist above TN. These data show that γ -BCPO is a rare highly frustrated, quasi-2D Seff =1 /2 honeycomb lattice material which resists long range magnetic order and spin freezing.

Temperature-modulated annealing of c-plane sapphire for long-range-ordered atomic steps

International Nuclear Information System (INIS)

Yatsui, Takashi; Kuribara, Kazunori; Sekitani, Tsuyoshi; Someya, Takao; Yoshimoto, Mamoru

2016-01-01

High-quality single-crystalline sapphire is used to prepare various semiconductors because of its thermal stability. Here, we applied the tempering technique, which is well known in the production of chocolate, to prepare a sapphire substrate. Surprisingly, we successfully realised millimetre-range ordering of the atomic step of the sapphire substrate. We also obtained a sapphire atomic step with nanometre-scale uniformity in the terrace width and atomic-step height. Such sapphire substrates will find applications in the preparation of various semiconductors and devices. (paper)

Atomic size effects on local coordination and medium range order in molten trivalent metal chlorides

International Nuclear Information System (INIS)

Tatlipinar, H.; Akdeniz, Z.; Pastore, G.

1992-08-01

Structural correlations in molten trivalent metal chlorides are evaluated as functions of the metal ion size R M across the range from LaCl 3 (R M approx. 1.4 A) to AlCl 3 (R M approx. 0.8 A), using a charged soft-sphere model and the hypernetted chain approximation. Main attention is given to trends in the local liquid structure (partial radial distribution functions, coordination numbers and bond lengths) and in the intermediate range order (first sharp diffraction peak in the number-number and partial structure factors). The trend towards fourfold local coordination of the metal ions, the stabilization of their first-neighbour chlorine cage and the growth of medium range order are found to proceed in parallel as the size of the metal ion is allowed to decrease at constant number density and temperature. A tendency to molecular-type local structure and liquid-vapour phase separation is found within the hypernetted chain scheme at small metal ion sizes corresponding to AlCl 3 and is emphasized by decreasing the number density of the fluid. The predicted molecular units are rather strongly distorted Al 2 Cl 6 dimers, in agreement with observation. The calculated structural trends for other trichlorides are compared with diffraction and transport data. (author). 17 refs, 8 figs, 1 tab

Stability of medium range order in Al-based metallic glass compacted by severe plastic deformation

Energy Technology Data Exchange (ETDEWEB)

Kovács, Zs.; Henits, P. [Department of Materials Physics, Eötvös University, P.O.B. 32, H-1518 Budapest (Hungary); Varga, L.K. [Research Institute for Solid state Physics and Optics, Hungarian Academy of Sciences, P.O.B. 49, H-1525 Budapest (Hungary); Schafler, E. [Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, A-1090 Vienna (Austria); Révész, Á., E-mail: reveszadam@ludens.elte.hu [Department of Materials Physics, Eötvös University, P.O.B. 32, H-1518 Budapest (Hungary)

2013-06-05

Highlights: ► High pressure torsion has been applied to produce low-porosity bulk Al-based amorphous specimens. ► The compacted disks possess higher hardness than the original glass. ► Mechanical and thermal impacts have only minor effects on the glassy structure. ► Medium range order is an inherent feature of the amorphous state. -- Abstract: High pressure torsion has successfully been applied to produce low-porosity, bulk specimens from Al-based metallic glass ribbons (Al{sub 85}Y{sub 8}Ni{sub 5}Co{sub 2}, Al{sub 85}Ce{sub 8}Ni{sub 5}Co{sub 2} and Al{sub 85}Gd{sub 8}Ni{sub 5}Co{sub 2}). The compacted disks possess higher hardness than the original glass and have substantial glass fraction with nanocrystalline precipitations. Mechanical and thermal impacts have only minor effects on the glassy structure as demonstrated by the stability of the X-ray diffraction halo positions. Unchanged halos reveal that medium range order is a key characteristic of the amorphous state.

Off-diagonal long-range order, cycle probabilities, and condensate fraction in the ideal Bose gas.

Science.gov (United States)

Chevallier, Maguelonne; Krauth, Werner

2007-11-01

We discuss the relationship between the cycle probabilities in the path-integral representation of the ideal Bose gas, off-diagonal long-range order, and Bose-Einstein condensation. Starting from the Landsberg recursion relation for the canonic partition function, we use elementary considerations to show that in a box of size L3 the sum of the cycle probabilities of length k>L2 equals the off-diagonal long-range order parameter in the thermodynamic limit. For arbitrary systems of ideal bosons, the integer derivative of the cycle probabilities is related to the probability of condensing k bosons. We use this relation to derive the precise form of the pik in the thermodynamic limit. We also determine the function pik for arbitrary systems. Furthermore, we use the cycle probabilities to compute the probability distribution of the maximum-length cycles both at T=0, where the ideal Bose gas reduces to the study of random permutations, and at finite temperature. We close with comments on the cycle probabilities in interacting Bose gases.

Effect of short-range ordering on the electrical conductivity and superconducting properties of Nb6C5 single crystals

International Nuclear Information System (INIS)

Utkina, T.G.

1995-01-01

Niobium carbide, NbC x , belongs to the family of so called interstital phases. Metal atoms form a face-centered cubic lattice, whose octahedral interstices are occupied by carbon atoms. The fraction (1 - x) of interstices remain vacant, and this determines the nonstoichiometry of these phases: most of them are characterized by a wide homogeneity range, 0.70 m ≅ 3308 - 3886 K). In contrast, the metalloid atoms exhibit high mobility at relatively low temperatures. For compositions close to Nb 6 C 5 (0.81 O-D ≅ 1300 K. The presence of vacancies in the carbon sublattice considerably affects the physical properties of carbides, which depend not only on total vacancy concentration but also on their distribution, i.e., on the degree of ordering (both short-range and long-range order) in the metalloid sublattice. The purpose of this work is to study the effects of such ordering on the superconducting properties of Nb 6 C 5 single crystals

Experimental observations of transient phases during long-range ordering to Ni4Mo in a Ni-Mo-Fe-Cr alloy

International Nuclear Information System (INIS)

Tawancy, H.M.; Aboelfotoh, M.O.

1987-01-01

Experimental observations are reported of transient phases which form during long-range ordering to Ni 4 Mo (f.c.c. → Dl/sub a/ superlattice) in the quaternary alloy Ni-19.2 at% Mo-1.2 at% Fe-1.06 at% Cr using electron diffraction. In the early stages of ordering during isothermal annealing, diffuse intensity maxima centered at the short-range order reflections (1 1/2 O)/sub f.c.c./ and along /sub f.c.c./ directions are observed. Subsequently, a DO 22 superlattice is generated from the short-range order state. The coexistence of the DO 22 , Pt 2 Mo-type, and Dl/sub a/ superlattices is observed in this alloy system which indicates that these three superlattices have similar energy. With continued annealing, both the DO 22 and Pt 2 Mo-type superlattices have similar energy. With continued annealing, both the DO 22 and Pt 2 Mo-type superlattices disappear, indicating that they are transient phases. These results are not inconsistent with the theoretical treatments of ordered alloys which are based on an Ising model with pairwise atomic interactions. (author)

Observation of field-induced long-range order in disordered Sr14Cu24O41

International Nuclear Information System (INIS)

Ohsugi, S.; Matsumoto, S.; Kitaoka, Y.; Matsuda, M.; Uehara, M.; Nagata, T.; Akimitsu, J.

2004-01-01

Field-induced magnetic order in a structural disordered single-crystal Sr 14 Cu 24 O 41 (Sr 14 -B) has been observed in the Cu-nuclear magnetic resonance (NMR) measurements for the ladder sites below 20 K under the magnetic field H∼11 T. For the Zhang Rice (ZR) sites in the chains, the spectrum splits below 20 K due to an appearance of the internal field, whereas that of less disordered Sr 14 -A does not. This gives an evidence of three-dimensional (3D) long-range (LR) ordering in Sr 14 -B below T N ∼20 K under H∼11 T

Long-range string orders and topological quantum phase transitions in the one-dimensional quantum compass model.

Science.gov (United States)

Wang, Hai Tao; Cho, Sam Young

2015-01-14

In order to investigate the quantum phase transition in the one-dimensional quantum compass model, we numerically calculate non-local string correlations, entanglement entropy and fidelity per lattice site by using the infinite matrix product state representation with the infinite time evolving block decimation method. In the whole range of the interaction parameters, we find that four distinct string orders characterize the four different Haldane phases and the topological quantum phase transition occurs between the Haldane phases. The critical exponents of the string order parameters β = 1/8 and the cental charges c = 1/2 at the critical points show that the topological phase transitions between the phases belong to an Ising type of universality classes. In addition to the string order parameters, the singularities of the second derivative of the ground state energies per site, the continuous and singular behaviors of the Von Neumann entropy and the pinch points of the fidelity per lattice site manifest that the phase transitions between the phases are of the second-order, in contrast to the first-order transition suggested in previous studies.

Deuterium short-range order in Pd0.975Ag0.025D0.685 by diffuse neutron scattering

DEFF Research Database (Denmark)

Blaschko, O.; Klemencic, R.; Fratzl, P.

1983-01-01

By diffuse neutron scattering the D short-range order in a Pd0.975Ag0.025D0.685 crystal was investigated at 50 and 70K. The results are compared with the D ordering in the PdDx system previously investigated, and it is shown that the isointensity contours around the (1/2,1,0) point are similar...

A nonrecursive order N preconditioned conjugate gradient: Range space formulation of MDOF dynamics

Science.gov (United States)

Kurdila, Andrew J.

1990-01-01

While excellent progress has been made in deriving algorithms that are efficient for certain combinations of system topologies and concurrent multiprocessing hardware, several issues must be resolved to incorporate transient simulation in the control design process for large space structures. Specifically, strategies must be developed that are applicable to systems with numerous degrees of freedom. In addition, the algorithms must have a growth potential in that they must also be amenable to implementation on forthcoming parallel system architectures. For mechanical system simulation, this fact implies that algorithms are required that induce parallelism on a fine scale, suitable for the emerging class of highly parallel processors; and transient simulation methods must be automatically load balancing for a wider collection of system topologies and hardware configurations. These problems are addressed by employing a combination range space/preconditioned conjugate gradient formulation of multi-degree-of-freedom dynamics. The method described has several advantages. In a sequential computing environment, the method has the features that: by employing regular ordering of the system connectivity graph, an extremely efficient preconditioner can be derived from the 'range space metric', as opposed to the system coefficient matrix; because of the effectiveness of the preconditioner, preliminary studies indicate that the method can achieve performance rates that depend linearly upon the number of substructures, hence the title 'Order N'; and the method is non-assembling. Furthermore, the approach is promising as a potential parallel processing algorithm in that the method exhibits a fine parallel granularity suitable for a wide collection of combinations of physical system topologies/computer architectures; and the method is easily load balanced among processors, and does not rely upon system topology to induce parallelism.

A NEUTRON DIFFRACTION DETERMINATION OF SHORT RANGE ORDER IN A Ni63.7Zr36.3 GLASS

OpenAIRE

Bellissent , R.; Bigot , J.; Calvayrac , Y.; Lefebvre , S.; Quivy , A.

1985-01-01

A precise determination of the three partial structure factors for the eutectic composition Ni63.7Zr36.3 has been carried out using neutron diffraction on three isotopically substituted glasses. The use of a "zero alloy" yields a direct determination of the Bhatia-Thornton structure factor SCC. Evidence for the existence of strong chemical short-range order and a clear size effect is obtained. Due to this chemical order, the partial structure factors cannot be consistent with the ones calcula...

Effect of medium range order on pulsed laser crystallization of amorphous germanium thin films

Energy Technology Data Exchange (ETDEWEB)

Li, T. T., E-mail: li48@llnl.gov; Bayu Aji, L. B.; Heo, T. W.; Kucheyev, S. O.; Campbell, G. H. [Materials Science Division, Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551 (United States); Santala, M. K. [Mechanical, Industrial, and Manufacturing Engineering, Oregon State University, 204 Rogers Hall, Corvallis, Oregon 97331 (United States)

2016-05-30

Sputter deposited amorphous Ge thin films had their nanostructure altered by irradiation with high-energy Ar{sup +} ions. The change in the structure resulted in a reduction in medium range order (MRO) characterized using fluctuation electron microscopy. The pulsed laser crystallization kinetics of the as-deposited versus irradiated materials were investigated using the dynamic transmission electron microscope operated in the multi-frame movie mode. The propagation rate of the crystallization front for the irradiated material was lower; the changes were correlated to the MRO difference and formation of a thin liquid layer during crystallization.

Effect of medium range order on pulsed laser crystallization of amorphous germanium thin films

International Nuclear Information System (INIS)

Li, T. T.; Bayu Aji, L. B.; Heo, T. W.; Kucheyev, S. O.; Campbell, G. H.; Santala, M. K.

2016-01-01

Sputter deposited amorphous Ge thin films had their nanostructure altered by irradiation with high-energy Ar"+ ions. The change in the structure resulted in a reduction in medium range order (MRO) characterized using fluctuation electron microscopy. The pulsed laser crystallization kinetics of the as-deposited versus irradiated materials were investigated using the dynamic transmission electron microscope operated in the multi-frame movie mode. The propagation rate of the crystallization front for the irradiated material was lower; the changes were correlated to the MRO difference and formation of a thin liquid layer during crystallization.

Spectral properties of an extended Hubbard ladder with long range anti-ferromagnetic order

Science.gov (United States)

Yang, Chun; Feiguin, Adrian

We study the spectral properties of a Hubbard ladder with anti-ferromagnetic long range order by introducing a staggered Heisenberg interaction that decays algebraically. Unlike an alternating field or the t -Jz model, our problem preserves both SU (2) and translational invariance. We solve the problem with the time-dependent density matrix renormalization group and analyze the binding between holons and spinons and the structure of the elementary excitations. We discuss the implications in the context of the 2D Hubbard model at, and away from half-filling by using cluster perturbation theory (CPT). AF acknowledges the U.S. Department of Energy, Office of Basic Energy Sciences, for support under Grant DE-SC0014407.

Does quasi-long-range order in the two-dimensional XY model really survive weak random phase fluctuations?

International Nuclear Information System (INIS)

Mudry, Christopher; Wen Xiaogang

1999-01-01

Effective theories for random critical points are usually non-unitary, and thus may contain relevant operators with negative scaling dimensions. To study the consequences of the existence of negative-dimensional operators, we consider the random-bond XY model. It has been argued that the XY model on a square lattice, when weakly perturbed by random phases, has a quasi-long-range ordered phase (the random spin wave phase) at sufficiently low temperatures. We show that infinitely many relevant perturbations to the proposed critical action for the random spin wave phase were omitted in all previous treatments. The physical origin of these perturbations is intimately related to the existence of broadly distributed correlation functions. We find that those relevant perturbations do enter the Renormalization Group equations, and affect critical behavior. This raises the possibility that the random XY model has no quasi-long-range ordered phase and no Kosterlitz-Thouless (KT) phase transition

Natural gels: crystal-chemistry of short range ordered components in Al, Fe, and Si systems

International Nuclear Information System (INIS)

Ildefonse, Ph.; Calas, G.

1997-01-01

In this review, the most important inorganic natural gels are presented: opal, aluminosilicate (allophanes) and hydrous iron oxides and silicates. It is demonstrated that natural gels are ordered at the atomic scale. In allophanes, Al is distributed between octahedral and tetrahedral sites. The amount of Al increases as Al/Si ratio decreases. Si-rich allophane have a local structure around Al and Si very different of that is known in kaolinite or halloysite. Transformation of Si-rich allophanes to crystallized minerals implies dissolution-recrystallization processes. On the contrary, in iron silicate with Fe/Si = 0.72, Si and Fe environments are close to those found in nontronite. The gel transformation to Fe-smectite may occur by long range ordering during ageing. In ferric silicate gels, the similarity of local structure around Fe in poorly ordered precursors and what is known in crystallized minerals suggests a solid transformation during ageing. This difference between iron and aluminium is mainly due to the ability of Al to enter both tetrahedral and octahedral sites, while the affinity of iron for octahedral sites is higher at low temperature

Short-range order studies in nonstoichiometric transition metal carbides and nitrides by neutron diffuse scattering

International Nuclear Information System (INIS)

Priem, Thierry

1988-01-01

Short-range order in non-stoichiometric transition metal carbides and nitrides (TiN 0.82 , TiC 0.64 , TiC 0.76 , NbC 0.73 and NbC 0.83 ) was investigated by thermal neutron diffuse scattering on G4-4 (L.L.B - Saclay) and D10 (I.L.L. Grenoble) spectrometers. From experimental measurements, we have found that metalloid vacancies (carbon or nitrogen) prefer the f.c.c. third neighbour positions. Ordering interaction energies were calculated within the Ising model framework by three approximations: mean field (Clapp and Moss formula), Monte-Carlo simulation, Cluster variation Method. The energies obtained by the two latter methods are very close, and in qualitative agreement with theoretical values calculated from the band structure. Theoretical phase diagrams were calculated from these ordering energies for TiN x and TiC x ; three ordered structures were predicted, corresponding to compositions Ti 6 N 5 Ti 2 C and Ti 3 C 2 . On the other hand, atomic displacements are induced by vacancies. The metal first neighbours were found to move away from a vacancy, whereas the second neighbours move close to it. Near neighbour atomic displacements were theoretically determined by the lattice statics formalism with results in good agreement with experiment. (author) [fr

Two-way laser ranging and time transfer experiments between LOLA and an Earth-based satellite laser ranging station

Science.gov (United States)

Mao, D.; Sun, X.; Neumann, G. A.; Barker, M. K.; Mazarico, E. M.; Hoffman, E.; Zagwodzki, T. W.; Torrence, M. H.; Mcgarry, J.; Smith, D. E.; Zuber, M. T.

2017-12-01

Satellite Laser Ranging (SLR) has established time-of-flight measurements with mm precision to targets orbiting the Earth and the Moon using single-ended round-trip laser ranging to passive optical retro-reflectors. These high-precision measurements enable advances in fundamental physics, solar system dynamics. However, the received signal strength suffers from a 1/R4 decay, which makes it impractical for measuring distances beyond the Moon's orbit. On the other hand, for a two-way laser transponder pair, where laser pulses are both transmitted to and received from each end of the laser links, the signal strength at both terminals only decreases by 1/R2, thus allowing a greater range of distances to be covered. The asynchronous transponder concept has been previously demonstrated by a test in 2005 between the Mercury Laser Altimeter (MLA) aboard the MESSENGER (MErcury Surface, Space ENvironment, Geochemistry, and Ranging) spacecraft and NASA's Goddard Geophysical and Astronomical Observatory (GGAO) at a distance of ˜0.16 AU. In October 2013, regular two-way transponder-type range measurements were obtained over 15 days between the Lunar Laser Communication Demonstration (LLCD) aboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft and NASA's ground station at White Sands, NM. The Lunar Orbiter Laser Altimeter (LOLA) aboard the Lunar Reconnaissance Orbiter (LRO) provides us a unique capability to test time-transfer beyond near Earth orbit. Here we present results from two-way transponder-type experiments between LOLA and GGAO conducted in March 2014 and 2017. As in the time-transfer by laser link (T2L2) experiments between a ground station and an earth-orbiting satellite, LOLA and GGAO ranged to each other simultaneously in these two-way tests at lunar distance. We measured the time-of-flight while cross-referencing the spacecraft clock to the ground station time. On May 4th, 2017, about 20 minutes of two-way measurements were collected. The

Development of ductile long-range ordered alloys for fusion reactor systems

International Nuclear Information System (INIS)

Liu, C.T.

1979-01-01

A series of Fe-base ordered alloys with compositions (Fe,Ni,Co) 3 V are developed for fusion reactor applications. The alloys from cubic ordered structure similar to AuCu 3 below their critical ordering temperature. The alloys in the ordered state are ductile with elongation in excess of 35% at room temperture. Tensile tests of the ordered alloys at elevated temperatures indicate an unusually attractive mechanical behavior. Their strength, instead of decreasing as with conventional alloys, increases with temperature because of ordering effects. As a result, the ordered alloys are much stronger than 316 stainless steel, particularly at elevated temperatures

Correlation of optical energy gap with the nearest neighbour short range order in amorphous V2O5 films

International Nuclear Information System (INIS)

Dhawan, Sahil; Vedeshwar, Agnikumar G; Tandon, R P

2011-01-01

The optical and structural properties of well characterized vacuum-evaporated amorphous V 2 O 5 films were studied in the thickness range 5-500 nm. The structural analyses show that V-O, O-O and V-V nearest neighbour distances defining the short range order vary nonlinearly with film thickness. The optical absorption shows thickness-dependent energy gap (E g ) and the nonlinear behaviour of thickness-dependent E g is similar to that of nearest neighbour distance with film thickness. The E g correlates linearly very well with all the three nearest neighbour distances. The variation of E g with film thickness is attributed to the residual stress in the film which causes the changes in short range order. The change in E g corresponding to the change in V-O distance was found to be 35 eV nm -1 . This change is almost three times of that with V-V distance.

Moessbauer Study of the Ball Milling Disordering Process of FeAl Intermetallic Compounds

International Nuclear Information System (INIS)

Oleszak, Dariusz; Bruna, Pere; Crespo, Daniel; Pradell, Trinitat

2005-01-01

Structural changes during ball milling of ordered Fe50Al50 intermetallic compounds were studied. X-Ray diffraction allowed the computation of a Long Range Order parameter (LRO) which dropped to zero after a short milling time. The initial B2 ordered structure gradually transforms into a disordered BCC structure, with a final crystallite size of about 25 nm. Moessbauer spectroscopy was used for obtaining a Chemical Short Range Order parameter (CSRO). Using a semiempirical n-body noncentral potential a model of the partially disordered B2 structure was built allowing computing the distribution of Quadrupole Splitting during the disordering process. Comparison between experimental and simulated Moessbauer spectra shows a maximum of disorder in the system for 5h milling, related to the highest value of the lattice spacing and the broader quadrupole hyperfine distribution. However, after milling for times longer than 5h, there is a change on the behavior of the experimental data that cannot be explained by the simple disordering process

Dynamic magnetic susceptibility of systems with long-range magnetic order

International Nuclear Information System (INIS)

Vannette, Matthew Dano

2009-01-01

The utility of the TDR as an instrument in the study of magnetically ordered materials has been expanded beyond the simple demonstration purposes. Results of static applied magnetic field dependent measurements of the dynamic magnetic susceptibility, ?, of various ferromagnetic (FM) and antiferromagnetic (AFM) materials showing a range of transition temperatures (1-800 K) are presented. Data was collected primarily with a tunnel diode resonator (TDR) at different radio-frequencies (∼10-30 MHz). In the vicinity of TC local moment ferromagnets show a very sharp, narrow peak in ? which is suppressed in amplitude and shifted to higher temperatures as the static bias field is increased. Unexpectedly, critical scaling analysis fails for these data. It is seen that these data are frequency dependent, however there is no simple method whereby measurement frequency can be changed in a controllable fashion. In contrast, itinerant ferromagnets show a broad maximum in ? well below TC which is suppressed and shifts to lower temperatures as the dc bias field is increased. The data on itinerant ferromagnets is fitted to a semi-phenomenological model that suggests the sample response is dominated by the uncompensated minority spins in the conduction band. Concluding remarks suggest possible scenarios to achieve frequency resolved data using the TDR as well as other fields in which the apparatus may be exploited.

Communication: Anomalous temperature dependence of the intermediate range order in phosphonium ionic liquids

International Nuclear Information System (INIS)

Hettige, Jeevapani J.; Kashyap, Hemant K.; Margulis, Claudio J.

2014-01-01

In a recent article by the Castner and Margulis groups [Faraday Discuss. 154, 133 (2012)], we described in detail the structure of the tetradecyltrihexylphosphonium bis(trifluoromethylsulfonyl)-amide ionic liquid as a function of temperature using X-ray scattering, and theoretical partitions of the computationally derived structure function. Interestingly, and as opposed to the case in most other ionic-liquids, the first sharp diffraction peak or prepeak appears to increase in intensity as temperature is increased. This phenomenon is counter intuitive as one would expect that intermediate range order fades as temperature increases. This Communication shows that a loss of hydrophobic tail organization at higher temperatures is counterbalanced by better organization of polar components giving rise to the increase in intensity of the prepeak

Laser Ranging in Solar System: Technology Developments and New Science Measurement Capabilities

Science.gov (United States)

Sun, X.; Smith, D. E.; Zuber, M. T.; Mcgarry, J.; Neumann, G. A.; Mazarico, E.

2015-12-01

Laser Ranging has played a major role in geodetic studies of the Earth over the past 40 years. The technique can potentially be used in between planets and spacecrafts within the solar system to advance planetary science. For example, a direct measurement of distances between planets, such as Mars and Venus would make significant improvements in understanding the dynamics of the whole solar system, including the masses of the planets and moons, asteroids and their perturbing interactions, and the gravity field of the Sun. Compared to the conventional radio frequency (RF) tracking systems, laser ranging is potentially more accurate because it is much less sensitive to the transmission media. It is also more efficient because the laser beams are much better focused onto the targets than RF beams. However, existing laser ranging systems are all Earth centric, that is, from ground stations on Earth to orbiting satellites in near Earth orbits or lunar orbit, and to the lunar retro-reflector arrays deployed by the astronauts in the early days of lunar explorations. Several long distance laser ranging experiments have been conducted with the lidar in space, including a two-way laser ranging demonstration between Earth and the Mercury Laser Altimeter (MLA) on the MESSENGER spacecraft over 24 million km, and a one way laser transmission and detection experiment over 80 million km between Earth and the Mars Orbiting Laser Altimeter (MOLA) on the MGS spacecraft in Mars orbit. A one-way laser ranging operation has been carried out continuously from 2009 to 2014 between multiple ground stations to LRO spacecraft in lunar orbit. The Lunar Laser Communication Demonstration (LLCD) on the LADEE mission has demonstrated that a two way laser ranging measurements, including both the Doppler frequency and the phase shift, can be obtained from the subcarrier or the data clocks of a high speed duplex laser communication system. Plans and concepts presently being studied suggest we may be

Thermal ageing and short-range ordering of Alloy 690 between 350 and 550 °C

Energy Technology Data Exchange (ETDEWEB)

Mouginot, Roman, E-mail: roman.mouginot@aalto.fi [Aalto University School of Engineering, Department of Mechanical Engineering, Otakaari 4, 02150 Espoo (Finland); Sarikka, Teemu [Aalto University School of Engineering, Department of Mechanical Engineering, Otakaari 4, 02150 Espoo (Finland); Heikkilä, Mikko [University of Helsinki, Laboratory of Inorganic Chemistry, A.I.Virtasen Aukio 1, 00560 Helsinki (Finland); Ivanchenko, Mykola; Ehrnstén, Ulla [VTT Technical Research Centre of Finland LTD, Kemistintie 3, 02150 Espoo (Finland); Kim, Young Suk; Kim, Sung Soo [Korea Atomic Energy Research Institute, Daedeok-Daero, 989-111, Yuseong, Daejeon, 34057 (Korea, Republic of); Hänninen, Hannu [Aalto University School of Engineering, Department of Mechanical Engineering, Otakaari 4, 02150 Espoo (Finland)

2017-03-15

Thermal ageing of Alloy 690 triggers an intergranular (IG) carbide precipitation and is known to promote an ordering reaction causing lattice contraction. It may affect the long-term primary water stress corrosion cracking (PWSCC) resistance of pressurized water reactor (PWR) components. Four conditions of Alloy 690 (solution annealed, cold-rolled and/or heat-treated) were aged between 350 and 550 °C for 10 000 h and characterized. Although no direct observation of ordering was made, variations in hardness and lattice parameter were attributed to the formation of short-range ordering (SRO) in all conditions with a peak level at 420 °C, consistent with the literature. Prior heat treatment induced ordering before thermal ageing. At higher temperatures, stress relaxation, recrystallization and α-Cr precipitation were observed in the cold-worked samples, while a disordering reaction was inferred in all samples based on a decrease in hardness. IG precipitation of M{sub 23}C{sub 6} carbides increased with increasing ageing temperature in all conditions, as well as diffusion-induced grain boundary migration (DIGM). - Highlights: • SRO was suggested in Alloy 690 with 9.18 wt% Fe after thermal ageing at 350, 420 and 475 °C. • Prior thermal treatment promoted SRO before ageing. • Cold work led to recrystallization and precipitation of α-Cr upon ageing at 550 °C. • Thermal ageing promoted IG precipitation of Cr-rich M{sub 23}C{sub 6} carbides and DIGM.

Absence of Long-Range Order in a Triangular Spin System with Dipolar Interactions

Science.gov (United States)

Keleş, Ahmet; Zhao, Erhai

2018-05-01

The antiferromagnetic Heisenberg model on the triangular lattice is perhaps the best known example of frustrated magnets, but it orders at low temperatures. Recent density matrix renormalization group (DMRG) calculations find that the next nearest neighbor interaction J2 enhances the frustration, and it leads to a spin liquid for J2/J1∈(0.08 ,0.15 ). In addition, a DMRG study of a dipolar Heisenberg model with longer range interactions gives evidence for a spin liquid at a small dipole tilting angle θ ∈[0 ,1 0 ° ). In both cases, the putative spin liquid region appears to be small. Here, we show that for the triangular lattice dipolar Heisenberg model, a robust quantum paramagnetic phase exists in a surprisingly wide region, θ ∈[0 ,5 4 ° ) , for dipoles tilted along the lattice diagonal direction. We obtain the phase diagram of the model by functional renormalization group (RG), which treats all magnetic instabilities on equal footing. The quantum paramagnetic phase is characterized by a smooth continuous flow of vertex functions and spin susceptibility down to the lowest RG scale, in contrast to the apparent breakdown of RG flow in phases with stripe or spiral order. Our finding points to a promising direction to search for quantum spin liquids in ultracold dipolar molecules.

Large magnetoelectric coupling in magnetically short-range ordered Bi₅Ti₃FeO₁₅ film.

Science.gov (United States)

Zhao, Hongyang; Kimura, Hideo; Cheng, Zhenxiang; Osada, Minoru; Wang, Jianli; Wang, Xiaolin; Dou, Shixue; Liu, Yan; Yu, Jianding; Matsumoto, Takao; Tohei, Tetsuya; Shibata, Naoya; Ikuhara, Yuichi

2014-06-11

Multiferroic materials, which offer the possibility of manipulating the magnetic state by an electric field or vice versa, are of great current interest. However, single-phase materials with such cross-coupling properties at room temperature exist rarely in nature; new design of nano-engineered thin films with a strong magneto-electric coupling is a fundamental challenge. Here we demonstrate a robust room-temperature magneto-electric coupling in a bismuth-layer-structured ferroelectric Bi₅Ti₃FeO₁₅ with high ferroelectric Curie temperature of ~1000 K. Bi₅Ti₃FeO₁₅ thin films grown by pulsed laser deposition are single-phase layered perovskit with nearly (00l)-orientation. Room-temperature multiferroic behavior is demonstrated by a large modulation in magneto-polarization and magneto-dielectric responses. Local structural characterizations by transmission electron microscopy and Mössbauer spectroscopy reveal the existence of Fe-rich nanodomains, which cause a short-range magnetic ordering at ~620 K. In Bi₅Ti₃FeO₁₅ with a stable ferroelectric order, the spin canting of magnetic-ion-based nanodomains via the Dzyaloshinskii-Moriya interaction might yield a robust magneto-electric coupling of ~400 mV/Oe·cm even at room temperature.

Study of long-range orders of hard-core bosons coupled to cooperative normal modes in two-dimensional lattices

Science.gov (United States)

Ghosh, A.; Yarlagadda, S.

2017-09-01

Understanding the microscopic mechanism of coexisting long-range orders (such as lattice supersolidity) in strongly correlated systems is a subject of immense interest. We study the possible manifestations of long-range orders, including lattice-supersolid phases with differently broken symmetry, in a two-dimensional square lattice system of hard-core bosons (HCBs) coupled to archetypal cooperative/coherent normal-mode distortions such as those in perovskites. At strong HCB-phonon coupling, using a duality transformation to map the strong-coupling problem to a weak-coupling one, we obtain an effective Hamiltonian involving nearest-neighbor, next-nearest-neighbor, and next-to-next-nearest-neighbor hoppings and repulsions. Using stochastic series expansion quantum Monte Carlo, we construct the phase diagram of the system. As coupling strength is increased, we find that the system undergoes a first-order quantum phase transition from a superfluid to a checkerboard solid at half-filling and from a superfluid to a diagonal striped solid [with crystalline ordering wave vector Q ⃗=(2 π /3 ,2 π /3 ) or (2 π /3 ,4 π /3 )] at one-third filling without showing any evidence of supersolidity. On tuning the system away from these commensurate fillings, checkerboard supersolid is generated near half-filling whereas a rare diagonal striped supersolid is realized near one-third filling. Interestingly, there is an asymmetry in the extent of supersolidity about one-third filling. Within our framework, we also provide an explanation for the observed checkerboard and stripe formations in La2 -xSrxNiO4 at x =1 /2 and x =1 /3 .

Relation between Feynman Cycles and Off-Diagonal Long-Range Order

International Nuclear Information System (INIS)

Ueltschi, Daniel

2006-01-01

The usual order parameter for Bose-Einstein condensation involves the off-diagonal correlation function of Penrose and Onsager, but an alternative is Feynman's notion of infinite cycles. We present a formula that relates both order parameters. We discuss its validity with the help of rigorous results and heuristic arguments. The conclusion is that infinite cycles do not always represent the Bose condensate

Short-Range-Order for fcc-based Binary Alloys Revisited from Microscopic Geometry

Science.gov (United States)

Yuge, Koretaka

2018-04-01

Short-range order (SRO) in disordered alloys is typically interpreted as competition between chemical effect of negative (or positive) energy gain by mixing constituent elements and geometric effects comes from difference in effective atomic radius. Although we have a number of theoretical approaches to quantitatively estimate SRO at given temperatures, it is still unclear to systematically understand trends in SRO for binary alloys in terms of geometric character, e.g., effective atomic radius for constituents. Since chemical effect plays significant role on SRO, it has been believed that purely geometric character cannot capture the SRO trends. Despite these considerations, based on the density functional theory (DFT) calculations on fcc-based 28 equiatomic binary alloys, we find that while conventional Goldschmidt or DFT-based atomic radius for constituents have no significant correlation with SRO, atomic radius for specially selected structure, constructed purely from information about underlying lattice, can successfully capture the magnitude of SRO. These facts strongly indicate that purely geometric information of the system plays central role to determine characteristic disordered structure.

Short-Range-Order Mineral Physical Protection On Black Carbon Stabilization

Science.gov (United States)

Liang, B.; Weng, Y. T.; Wang, C. C.; Song, Y. F.; Lehmann, J.; Wang, C. H.

2015-12-01

Soil organic matter is one of the largest reservoirs in global carbon cycle, and black carbon (BC) represents a chemical resistant component. Black C plays an important role in global climate change. Generally considered recalcitrant due to high aromaticity, the reactive surface and functional groups of BC are crucial for carbon sequestration in soils. Mineral sorption and physical protection is an important mechanism for BC long term stabilization and sequestration in environments. Previous studies on mineral protection of BC were limited to analysis techniques in two-dimensions, for example, by SEM, TEM, and NanoSIMS. Little is known about the scope of organo-mineral association, the in-situ distribution and forms of minerals, and the ultimate interplay of BC and minerals. The aim of this study is to investigate the three-dimensional interaction of organic C and minerals in submicron scale using synchrotron-based Transmission X-ray Microcopy (TXM) and Fourier-Transform Infrared Spectroscopy (FTIR). Abundant poorly-crystallined nano-minerals particles were observed. These short-range-order (SRO) minerals also aggregate into clusters and sheets, and form envelops-like structures on the surface of BC. On top of large surface contact area, the intimate interplay between BC and minerals reinforces the stability of both organic C and minerals, resulting from chemical bonding through cation bridging and ligand exchange. The mineral protection enhances BC stabilization and sequestration and lowers its bioavailability in environment. The results suggest that mineral physical protection for BC sequestration may be more important than previous understanding.

Structural and magnetic properties of two branches of the tripod-kagome-lattice family A2R3Sb3O14 (A = Mg, Zn; R = Pr, Nd, Gd, Tb, Dy, Ho, Er, Yb)

Science.gov (United States)

Dun, Z. L.; Trinh, J.; Lee, M.; Choi, E. S.; Li, K.; Hu, Y. F.; Wang, Y. X.; Blanc, N.; Ramirez, A. P.; Zhou, H. D.

2017-03-01

We present a systematic study of the structural and magnetic properties of two branches of the rare-earth tripod-kagome-lattice (TKL) family A2R3Sb3O14 (A = Mg, Zn; R = Pr, Nd, Gd, Tb, Dy, Ho, Er, Yb; here, we use abbreviation A-R, as in MgPr for Mg2Pr3Sb3O14 ), which complements our previously reported work on MgDy, MgGd, and MgEr [Z. L. Dun et al., Phys. Rev. Lett. 116, 157201 (2016), 10.1103/PhysRevLett.116.157201]. The present susceptibility (χdc, χac) and specific-heat measurements reveal various magnetic ground states, including the nonmagnetic singlet state for MgPr, ZnPr; long-range orderings (LROs) for MgGd, ZnGd, MgNd, ZnNd, and MgYb; a long-range magnetic charge ordered state for MgDy, ZnDy, and potentially for MgHo; possible spin-glass states for ZnEr, ZnHo; the absence of spin ordering down to 80 mK for MgEr, MgTb, ZnTb, and ZnYb compounds. The ground states observed here bear both similarities as well as striking differences from the states found in the parent pyrochlore systems. In particular, while the TKLs display a greater tendency towards LRO, the lack of LRO in MgHo, MgTb, and ZnTb can be viewed from the standpoint of a balance among spin-spin interactions, anisotropies, and non-Kramers nature of single-ion state. While substituting Zn for Mg changes the chemical pressure, and subtly modifies the interaction energies for compounds with larger R ions, this substitution introduces structural disorder and modifies the ground states for compounds with smaller R ions (Ho, Er, Yb).

Investigation into short-range order, electric conductivity and optical absorption edge of indium selenide thin amorphous films

International Nuclear Information System (INIS)

Bilyj, M.N.; Didyk, G.V.; Stetsiv, Ya.I.; Yurechko, R.Ya.

1980-01-01

Thin amorphous films of InSe have been obtained by the method of discrete vacuum evaporation of about 10 -2 Pa. The short-range order is investigated according to the radial distribution curves. The temperature and film thickness are shown to affect the character of conductivity. The width of the forbidden band determined by the fundamental absorption edge is found to depend on the time of film annealing

Electronic structure of disordered alloys - I: self-consistent cluster CPA incorporating off-diagonal disorder and short-range order

International Nuclear Information System (INIS)

Kumar, V.; Mookerjee, A.; Srivastava, V.K.

1980-09-01

We have developed here a self-consistent coherent potential approximation generalized to take into account effect of clusters. Off-diagonal disorder and short-range order are taken into account. A graphical method married to the recursion technique, enables us to work on realistic three-dimensional lattices. Calculations are shown for a binary alloy on a diamond lattice. (author)

Loss of long-range magnetic order in a nanoparticle assembly due to random anisotropy

International Nuclear Information System (INIS)

Binns, C; Howes, P B; Baker, S H; Marchetto, H; Potenza, A; Steadman, P; Dhesi, S S; Roy, M; Everard, M J; Rushforth, A

2008-01-01

We have used soft x-ray photoemission electron microscopy (XPEEM) combined with x-ray magnetic circular dichroism (XMCD) and DC SQUID (superconducting quantum interference device) magnetometry to probe the magnetic ground state in Fe thin films produced by depositing size-selected gas-phase Fe nanoparticles with a diameter of 1.7 nm (∼200 atoms) onto Si substrates. The depositions were carried out in ultrahigh vacuum conditions and thicknesses of the deposited film in the range 5-50 nm were studied. The magnetometry data are consistent with the film forming a correlated super-spin glass with a magnetic correlation length ∼5 nm. The XPEEM magnetic maps from the cluster-assembled films were compared to those for a conventional thin Fe film with a thickness of 20 nm produced by a molecular beam epitaxy (MBE) source. Whereas a normal magnetic domain structure is observed in the conventional MBE thin film, no domain structure could be observed in any of the nanoparticle films down to the resolution limit of the XMCD based XPEEM (100 nm) confirming the ground state indicated by the magnetometry measurements. This observation is consistent with the theoretical prediction that an arbitrarily weak random anisotropy field will destroy long-range magnetic order

Stochastic reduced-order model for an automotive vehicle in presence of numerous local elastic modes in the low-frequency range

OpenAIRE

Arnoux , A.; Batou , Anas; Soize , Christian; Gagliardini , L.

2012-01-01

International audience; This paper is devoted to the construction of a stochastic reduced-order model for dynamical structures having a high modal density in the low-frequency range, such as an automotive vehicle. This type of structure is characterized by the fact that it exhibits, in the low-frequency range, not only the classical global elastic modes but also numerous local elastic modes which cannot easily be separated from the global elastic modes. An approach has recently been proposed ...

Concentration and temperature dependence of short-range order in Ni-Ta solid solution using X-ray diffraction method

International Nuclear Information System (INIS)

Khwaja, F.A.; Alam, A.

1980-09-01

Diffuse X-ray scattering investigations about the existence of short-range order (SRO) have been carried out in the Ni-Ta system for different concentrations and annealing temperatures. It is observed that the values of the SRO parameters for the first co-ordination shell have anomalously large negative values for all the samples studied. These values of the α 1 depend upon the annealing temperatures and the concentration of Ta atoms in the Ni-Ta system. The results of the theoretical predictions of the ordering potential obtained using the formulae of the electronic theory of SRO, confirm the existence of very strong attractive correlation between the atoms of the different species in this system. (author)

BeP2: a tetrahedral structure of type order-disorder which obeys a coordination rule for short-range order

International Nuclear Information System (INIS)

L'Haridon, P.; David, J.; Lang, J.; Parthe, E.

1976-01-01

Single-crystal studies on BeP 2 indicate that this compound possesses an OD structure. The substructure has a tetragonal unit cell with: a = 3.546 A, c = 15.01 A, Z = 4, space group: I4 1 /amd. The final R factor has a value of 0.033. The atom sites in this substructure correspond to the sites of diamond if the latter is described with a tetragonal cell, where a = (2/sup 1/2//a/sub diamond/ and c = 3a/sub diamond/. A short-range order governs the occupation of these sites with Be and P atoms. Each Be has four tetrahedral P neighbors and every P has two Be and two P neighbors. Consideration of the maxima on the diffuse streaks between the sharp reflectins of the substructure leads to an intermediate unit cell with a = 7.09 A and c = 30.02 A. Coordination considerations allow a structure proposal to be formulated for this intermediate structure which is triclinic but pseudotetragonal. The true unit cell is also pseudotetragonal with a = 7.09 A and c = N . 15.01 A, where N is a large integer

Short range charge/orbital ordering in La1-xSrxMn1-zBzO3 (B Cu,Zn) manganites

International Nuclear Information System (INIS)

Popovic, Z V; Cantarero, A; Thijssen, W H A; Paunovic, N; Dohcevic-Mitrovic, Z; Sapina, F

2005-01-01

We have measured the reflectivity spectra of La 1-x Sr x Mn 1-z B z O 3 (B = Cu, Zn; 0.17 ≤ x ≤ 0.30; 0 ≤ z ≤ 0.10) manganites over wide frequency (100-4000 cm -1 ) and temperature (80-300 K) ranges. Besides the previously observed infrared active modes or mode pairs at about 160 cm -1 (external mode), 350 cm -1 (bond bending mode) and 590 cm -1 (bond stretching mode), we have clearly observed two additional phonon modes at about 645 and 720 cm -1 below the temperature T 1 (T 1 C ), which coincides with the phase transition temperature when the system transforms from ferromagnetic metallic into a ferromagnetic insulator state. This transition is related to the formation of short range charge/orbitally ordered domains. The temperature T 1 of the phase transition is dependent on the doping concentration and for optimally doped samples we have found that T 1 ∼(0.93 ± 0.02) T C . Electrical resistivity and magnetization measurements versus temperature and magnetic field support the short range charge/orbital ordering scenario

Toward Monte Carlo simulation of general cases of static muon spin relaxation in disordered magnetic materials: long-range magnetic order in alloys

International Nuclear Information System (INIS)

Noakes, D.R.

2001-01-01

Monte Carlo simulations of zero-field (ZF) muon spin relaxation (μSR) functions generated by long-range-ordered states with disorder are presented, for the completely static limit. Understanding of this is necessary before Monte Carlo simulation of the effect of short-range magnetic ordering on μSR in spin glasses can begin. Alloy disorder, controlled by the magnetic ion concentration parameter f m , and partial ordering of each moment, controlled by the order parameter f o , are considered. Qualitatively different behavior is seen depending on whether the dense moment, perfect-order limit ( f m =1, f o =1) field at the muon site is non-zero, or cancels (as can happen in high-symmetry materials). Around the edges of the two-dimensional ( f m ,f o ) parameter space, four limit cases with qualitatively different behavior are identified: (A) f o →0, the random frozen spin glass for arbitrary magnetic ion concentration; (B) f o →1, nearly perfect magnetic ordering in a alloy of arbitrary magnetic ion concentration; (C) f m →0, magnetic order developing (as f o increases) in a dilute magnetic alloy; (D) f m →1, magnetic order developing (as f o increases) in a dense magnetic material. Case A was discussed in a previous publication. The results for case D answer the question of how the Gaussian Kubo-Toyabe relaxation function for perfect disorder develops into an oscillating function as magnetic order develops in a material. Case C indicates that the effects of magnetic ordering in the dilute moment limit produce only subtle effects in ZF-μSR spectra that would be difficult to unambiguously identify as due to ordering in a real-world experiment. Case B generates complicated multi-frequency behavior

Higher Order Analysis of Turbulent Changes Found in the ELF Range Electric Field Plasma Before Major Earthquakes

Science.gov (United States)

Kosciesza, M.; Blecki, J. S.; Parrot, M.

2014-12-01

We report the structure function analysis of changes found in electric field in the ELF range plasma turbulence registered in the ionosphere over epicenter region of major earthquakes with depth less than 40 km that took place during 6.5 years of the scientific mission of the DEMETER satellite. We compare the data for the earthquakes for which we found turbulence with events without any turbulent changes. The structure functions were calculated also for the Polar CUSP region and equatorial spread F region. Basic studies of the turbulent processes were conducted with use of higher order spectra and higher order statistics. The structure function analysis was performed to locate and check if there are intermittent behaviors in the ionospheres plasma over epicenter region of the earthquakes. These registrations are correlated with the plasma parameters measured onboard DEMETER satellite and with geomagnetic indices.

Isolation of a new two-dimensional honeycomb carbonato-bridged copper(II) complex exhibiting long-range ferromagnetic ordering.

Science.gov (United States)

Majumder, Arpi; Choudhury, Chirantan Roy; Mitra, Samiran; Rosair, Georgina M; El Fallah, M Salah; Ribas, Joan

2005-04-28

Atmospheric CO2 fixation by an aqueous solution containing Cu(ClO4)2.6H2O and 4-aminopyridine (4-apy) yields a novel example of a two-dimensional mu3-CO3 bridged copper(II) complex {[Cu(4-apy)2]3(mu3-CO3)2(ClO4)2.(1/2)CH3OH}n that has been characterized by IR, UV and X-ray crystallography; preliminary magnetic measurements show that complex exhibits long-range ordered ferromagnetic coupling.

Seismic-Acoustic Active Range Monitoring for Characterizing Low-Order Ordnance Detonation

National Research Council Canada - National Science Library

Anderson, Thomas S; Weale, Jason C

2006-01-01

.... The Distributed Sources focus area strives to characterize the level of contamination in range environments attributed to ordnance residue for the purpose of range management and environmental remediation...

Optimization of planar metallic nonrefracting transmission-grating profiles for M/sup th/-order intensity maximization in the soft x-ray range

International Nuclear Information System (INIS)

Tatchyn, R.; Csonka, P.L.; Lindau, I.

1982-01-01

In this paper, we derive the thickness profiles of metallic transmission-grating bars which maximize either the power throughput into the m/sup th/ diffracted order or the ratio of the m/sup th/-order diffracted power to the total output power (in the soft x-ray range). The derivation is performed for both general and symmetric bar shapes and for the two physically important cases of continuous gratings and gratings with integral bars. The solutions derived are shown to be valid for cases where the optical constants are generalized to be functions of position in a direction perpendicular to the grating bars. Examples of some optimum profiles for gold in the soft x-ray range are computed on the basis of the presented analysis and tabulated for convenient reference. 18 references

Short-to-Medium-Range Order and Atomic Packing in Zr48Cu36Ag8Al8 Bulk Metallic Glass

Directory of Open Access Journals (Sweden)

Yong Xu

2016-10-01

Full Text Available Due to its excellent glass-forming ability (GFA, the Zr48Cu36Al8Ag8 bulk metallic glass (BMG is of great importance in glass transition investigations and new materials development. However, due to the lack of detailed structural information, the local structure and atomic packing of this alloy is still unknown. In this work, synchrotron measurement and reverse Monte Carlo simulation are performed on the atomic configuration of a Zr-based bulk metallic glass. The local structure is characterized in terms of bond pairs and Voronoi tessellation. It is found that there are mainly two types of bond pairs in the configuration, as the body-centered cubic (bcc-type and icosahedral (ico-type bond pairs. On the other hand, the main polyhedra in the configuration are icosahedra and the bcc structure. That is, the bcc-type bond pairs, together with the ico-type bond pairs, form the bcc polyhedra, introducing the distortion in bcc clusters in short range. However, in the medium range, the atoms formed linear or planar structures, other than the tridimensional clusters. That is, the medium-range order in glass is of 1D or 2D structure, suggesting the imperfect ordered packing feature.

Path-Integral Monte Carlo Determination of the Fourth-Order Virial Coefficient for a Unitary Two-Component Fermi Gas with Zero-Range Interactions.

Science.gov (United States)

Yan, Yangqian; Blume, D

2016-06-10

The unitary equal-mass Fermi gas with zero-range interactions constitutes a paradigmatic model system that is relevant to atomic, condensed matter, nuclear, particle, and astrophysics. This work determines the fourth-order virial coefficient b_{4} of such a strongly interacting Fermi gas using a customized ab initio path-integral Monte Carlo (PIMC) algorithm. In contrast to earlier theoretical results, which disagreed on the sign and magnitude of b_{4}, our b_{4} agrees within error bars with the experimentally determined value, thereby resolving an ongoing literature debate. Utilizing a trap regulator, our PIMC approach determines the fourth-order virial coefficient by directly sampling the partition function. An on-the-fly antisymmetrization avoids the Thomas collapse and, combined with the use of the exact two-body zero-range propagator, establishes an efficient general means to treat small Fermi systems with zero-range interactions.

Temperature dependence of the short-range order parameter and the concentration dependence of the order disorder temperature for Ni-Pt and Ni-Fe systems in the improved statistical pseudopotential approximation

International Nuclear Information System (INIS)

Khwaja, F.A.

1980-08-01

The calculations for the temperature dependence of the first shell short-range order (SRO) parameter for Ni 3 Fe using the cubic approximation of Tahir Kheli, and the concentration dependence of order-disorder temperature Tsub(c) for Ni-Fe and Ni-Pt systems using the linear approximation, have been carried out in the framework of pseudopotential theory. It is shown that the cubic approximation yields a good agreement between the theoretical prediction of the α 1 and the experimental data. Results for the concentration dependence of the Tsub(c) show that improvements in the statistical pseudo-potential approach are essential to achieve a good agreement with experiment. (author)

Doping-induced quantum crossover in Er2Ti2 -xSnxO7

Science.gov (United States)

Shirai, M.; Freitas, R. S.; Lago, J.; Bramwell, S. T.; Ritter, C.; Živković, I.

2017-11-01

We present the results of the investigation of magnetic properties of the Er2Ti2 -xSnxO7 series. For small doping values, the ordering temperature decreases linearly with x , while the moment configuration remains the same as in the x =0 parent compound. Around x =1.7 doping level, we observe a change in the behavior, where the ordering temperature starts to increase and new magnetic Bragg peaks appear. For the first time, we present evidence of a long-range order (LRO) in Er2Sn2O7 (x =2.0 ) below TN=130 mK. It is revealed that the moment configuration corresponds to a Palmer-Chalker type with a value of the magnetic moment significantly renormalized compared to x =0 . We discuss our results in the framework of a possible quantum phase transition occurring close to x =1.7 .

Short- and long-range polar order contributions to the Ferroelectric phase of Ca.sup.2+./sup. doped SrTiO.sub.3./sub.

Czech Academy of Sciences Publication Activity Database

Markovin, P.A.; Trepakov, Vladimír; Guzhva, M.E.; Razdobarin, A.G.; Tagantsev, A. K.; Andreev, D. A.; Dejneka, Alexandr

2016-01-01

Roč. 3, č. 11 (2016), s. 1-12, č. článku 115705. ISSN 2053-1591 R&D Projects: GA ČR GA15-13778S Institutional support: RVO:68378271 Keywords : quantum paraelectrics * impurities and defects * low-temperature polar state * ferroelectric phase * long-range order * short-range Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.068, year: 2016

Quantifying the information in the long-range order of words: semantic structures and universal linguistic constraints.

Science.gov (United States)

Montemurro, Marcelo A

2014-06-01

We review some recent progress on the characterisation of long-range patterns of word use in language using methods from information theory. In particular, two levels of structure in language are considered. The first level corresponds to the patterns of words usage over different contextual domains. A direct application of information theory to quantify the specificity of words across different sections of a linguistic sequence leads to a measure of semantic information. Moreover, a natural scale emerges that characterises the typical size of semantic structures. Since the information measure is made up of additive contributions from individual words, it is possible to rank the words according to their overall weight in the total information. This allows the extraction of keywords most relevant to the semantic content of the sequence without any prior knowledge of the language. The second level considered is the complex structure of correlations among words in linguistic sequences. The degree of order in language can be quantified by means of the entropy. Reliable estimates of the entropy were obtained from corpora of texts from several linguistic families by means of lossless compression algorithms. The value of the entropy fluctuates across different languages since it depends on linguistic organisation at various levels. However, when a measure of relative entropy that specifically quantifies the degree of word ordering in language is estimated, it presents an almost constant value over all the linguistic families studied. This suggests that the entropy of word ordering is a novel quantitative linguistic universal. Copyright © 2013 Elsevier Ltd. All rights reserved.

The interplay of long-range magnetic order and single-ion anisotropy in rare earth nickel germanides

International Nuclear Information System (INIS)

Islam, Z.

1999-01-01

This dissertation is concerned with the interplay of long-range order and anisotropy in the tetragonal RNi 2 Ge 2 (R = rare earth) family of compounds. Microscopic magnetic structures were studied using both neutron and x-ray resonant exchange scattering (XRES) techniques. The magnetic structures of Tb, Dy, Eu and Gd members have been determined using high-quality single-crystal samples. This work has correlated a strong Fermi surface nesting to the magnetic ordering in the RNi 2 Ge 2 compounds. Generalized susceptibility, χ 0 (q), calculations found nesting to be responsible for both incommensurate ordering wave vector in GdNi 2 Ge 2 , and the commensurate structure in EuNi 2 Ge 2 . A continuous transition from incommensurate to commensurate magnetic structures via band filling is predicted. The surprisingly higher T N in EuNi 2 Ge 2 than that in GdNi 2 Ge 2 is also explained. Next, all the metamagnetic phases in TbNi 2 Ge 2 with an applied field along the c axis have been characterized with neutron diffraction measurements. A mixed phase model for the first metamagnetic structure consisting of fully-saturated as well as reduced-moment Tb ions is presented. The moment reduction may be due to moment instability which is possible if the exchange is comparable to the low-lying CEF level splitting and the ground state is a singlet. In such a case, certain Tb sites may experience a local field below the critical value needed to reach saturation

Fungal biomineralization of montmorillonite and goethite to short-range-ordered minerals

Science.gov (United States)

Li, Huan; Hu, Shuijin; Polizzotto, Matthew L.; Chang, Xiaoli; Shen, Qirong; Ran, Wei; Yu, Guanghui

2016-10-01

Highly reactive nano-scale minerals, e.g., short-range-ordered minerals (SROs) and other nanoparticles, play an important role in soil carbon (C) retention. Yet, the mechanisms that govern biomineralization from bulk minerals to highly reactive nano-scale minerals remain largely unexplored, which critically hinders our efforts toward managing nano-scale minerals for soil C retention. Here we report the results from a study that explores structural changes during Aspergillus fumigatus Z5 transformation of montmorillonite and goethite to SROs. We examined the morphology and structure of nano-scale minerals, using high-resolution transmission electron microscopy, time-resolved solid-state 27Al and 29Si NMR, and Fe K-edge X-ray absorption fine structure spectroscopy combined with two dimensional correlation spectroscopy (2D COS) analysis. Our results showed that after a 48-h cultivation of montmorillonite and goethite with Z5, new biogenic intracellular and extracellular reactive nano-scale minerals with a size of 3-5 nm became abundant. Analysis of 2D COS further suggested that montmorillonite and goethite were the precursors of the dominant biogenic nano-scale minerals. Carbon 1s near edge X-ray absorption fine structure (NEXAFS) spectra and their deconvolution results demonstrated that during fungus Z5 growth, carboxylic C (288.4-289.1 eV) was the dominant organic group, accounting for approximately 34% and 59% in the medium and aggregates, respectively. This result suggested that high percentage of the production of organic acids during the growth of Z5 was the driving factor for structural changes during biomineralization. This is, to the best of our knowledge, the first report of the structural characterization of nano-scale minerals by 2D COS, highlighting its potential to elucidate biomineralization pathways and thus identify the precursors of nano-scale minerals.

Orbit Determination for the Lunar Reconnaissance Orbiter Using an Extended Kalman Filter

Science.gov (United States)

Slojkowski, Steven; Lowe, Jonathan; Woodburn, James

2015-01-01

Since launch, the FDF has performed daily OD for LRO using the Goddard Trajectory Determination System (GTDS). GTDS is a batch least-squares (BLS) estimator. The tracking data arc for OD is 36 hours. Current operational OD uses 200 x 200 lunar gravity, solid lunar tides, solar radiation pressure (SRP) using a spherical spacecraft area model, and point mass gravity for the Earth, Sun, and Jupiter. LRO tracking data consists of range and range-rate measurements from: Universal Space Network (USN) stations in Sweden, Germany, Australia, and Hawaii. A NASA antenna at White Sands, New Mexico (WS1S). NASA Deep Space Network (DSN) stations. DSN data was sparse and not included in this study. Tracking is predominantly (50) from WS1S. The OD accuracy requirements are: Definitive ephemeris accuracy of 500 meters total position root-mean-squared (RMS) and18 meters radial RMS. Predicted orbit accuracy less than 800 meters root sum squared (RSS) over an 84-hour prediction span.

Microwave absorption measurements in the complex perovskite Pb(Fe{sub 0.5}Ta{sub 0.5})O{sub 3}: Detection of short-range orderly regions

Energy Technology Data Exchange (ETDEWEB)

Alvarez, G., E-mail: memodin@yahoo.com [Seccion de Estudios de Posgrado e Investigacion, ESFM-IPN, U.P. Adolfo Lopez Mateos Edificio 9, Av. Instituto Politecnico Nacional S/N, San Pedro Zacatenco, Mexico DF 07738 (Mexico); Montiel, H. [Departamento de Tecnociencias, Centro de Ciencias Aplicadas y Desarrollo Tecnologico de la Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, Mexico DF 04510 (Mexico); Castellanos, M.A. [Facultad de Quimica, Universidad Nacional Autonoma de Mexico, Cd. Universitaria, Mexico DF 04510 (Mexico); Heiras, J. [Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Km. 107, Carretera Tijuana Ensenada, Ensenada, Baja California 22860 (Mexico); Zamorano, R. [Seccion de Estudios de Posgrado e Investigacion, ESFM-IPN, U.P. Adolfo Lopez Mateos Edificio 9, Av. Instituto Politecnico Nacional S/N, San Pedro Zacatenco, Mexico DF 07738 (Mexico)

2011-10-17

Highlights: {yields} LFMA spectra showed straight lines with positive slope and non-hysteretic traces. {yields} The spectral changes for the plot of the slope vs. temperature give evidence of the formation of iron clusters. {yields} These small orderly regions of iron ions generate short-range magnetic correlations, and that they produce changes in dynamics of microwave absorption. - Abstract: An electron paramagnetic resonance (EPR) study of the complex perovskite Pb(Fe{sub 0.5}Ta{sub 0.5})O{sub 3} (PFT) at X-band (8.8-9.8 GHz) is presented. The EPR spectra show a single broad line in the 300-480 K temperature range, attributable to Fe{sup 3+} (S = 5/2) ions. The temperature dependence of the EPR parameters: the peak-to-peak linewidth ({Delta}H{sub pp}), the resonance field (H{sub res}) and the integrated intensity (I{sub EPR}), suggests the existence of short-range magnetic correlations; which are associated with the presence of small orderly regions of iron ions in B-sites of the perovskites-type structure, and that they give origin to formation of iron clusters. Low-field microwave absorption (LFMA) is used to give further knowledge on this material; where this technique also gives evidence of these short-range orderly regions.

The role of medium range order on phase transitions in chain silicates upon compression

International Nuclear Information System (INIS)

Serghiou, G; Chopelas, A; Boehler, R

2004-01-01

Raman spectroscopic measurements of the tetrahedrally coordinated crystal MnSiO 3 (rhodonite) in an argon pressure medium show that it becomes amorphous above 33 GPa. This observation consolidates our findings and explanation for the global structural trends exhibited by the extended chain silicate family AA'BO 3 (AA': Mg, Ca, Mn, Fe; B: Si) upon compression. In particular, crystals of this family are made of two types of building blocks coined P and C. Those crystals comprised solely of P blocks transform to dense higher coordinated crystalline phases; those comprised of P and C blocks, such as MnSiO 3 rhodonite, become amorphous; whereas those comprised solely of C blocks show both crystalline and amorphous regions upon compression. The reason that this medium range order length scale (building block scale) classification is correlated with the type of transitions taking place upon compression is due to the instability of C blocks and C-P interfaces with respect to P blocks and P-P interfaces at high pressures

Short-range order analysis and some physical properties of InxSe1-x glasses

International Nuclear Information System (INIS)

El-Kabany, N.

2012-01-01

Bulk In x Se 1-x (with x=5-25 at%) glasses were prepared using the melt-quench technique. Short range order(SRO) was examined by the X-ray diffraction using Cu(k α ) radiation in the wave vector interval 0.28≤k≤6.5 A 0-1 .The SRO parameters have been obtained from the radial distribution function. The inter-atomic distance obtained from the first and second peak are r 1 =0.263 and r 2 =0.460 nm, which is equivalent In-Se and Se-Se bond length. The fundamental structural unit for the studied glasses is In 2 Se 3 pyramid. Using the differential scanning calorimetry (DSC), the crystallization mechanism of In x Se 1-x chalcogenide glass has been studied. The glass transition activation energy (E g ) is 289±0.3 kj/mol.There is a correlation amongst the glass forming ability, bond strength and the number of lone pair electrons. The utility of the Gibbs-Di Marzio relation was achieved by estimating T g theoretically.

Extensive disordering in long-range-ordered Cu3Au induced by severe plastic deformation studied by transmission electron microscopy

International Nuclear Information System (INIS)

Rentenberger, C.; Karnthaler, H.P.

2008-01-01

Bulk nanocrystalline materials can be made by severe plastic deformation. In L1 2 long-range-ordered alloys, this leads to extensive disordering which influences the highly improved properties of these nanocrystalline alloys. Transmission electron microscopy methods were applied to Cu 3 Au; both diffraction contrast images and diffraction patterns reveal that disordering takes place locally. It is concluded that in addition to disordering by the refinement of the grown-in antiphase boundary domains, the formation of antiphase boundary tubes is a prominent process of disordering. The latter is facilitated by the fact that, unlike dislocations, antiphase boundary tubes can be stored at a very high density without causing long-range stresses. The local disordering indicates that the nanocrystalline structure nucleates inhomogeneously in the highly strained disordered regions

Higher order moments of the matter distribution in scale-free cosmological simulations with large dynamic range

Science.gov (United States)

Lucchin, Francesco; Matarrese, Sabino; Melott, Adrian L.; Moscardini, Lauro

1994-01-01

We calculate reduced moments (xi bar)(sub q) of the matter density fluctuations, up to order q = 5, from counts in cells produced by particle-mesh numerical simulations with scale-free Gaussian initial conditions. We use power-law spectra P(k) proportional to k(exp n) with indices n = -3, -2, -1, 0, 1. Due to the supposed absence of characteristic times or scales in our models, all quantities are expected to depend on a single scaling variable. For each model, the moments at all times can be expressed in terms of the variance (xi bar)(sub 2), alone. We look for agreement with the hierarchical scaling ansatz, according to which ((xi bar)(sub q)) proportional to ((xi bar)(sub 2))(exp (q - 1)). For n less than or equal to -2 models, we find strong deviations from the hierarchy, which are mostly due to the presence of boundary problems in the simulations. A small, residual signal of deviation from the hierarchical scaling is however also found in n greater than or equal to -1 models. The wide range of spectra considered and the large dynamic range, with careful checks of scaling and shot-noise effects, allows us to reliably detect evolution away from the perturbation theory result.

The interplay of long-range magnetic order and single-ion anisotropy in rare earth nickel germanides

Energy Technology Data Exchange (ETDEWEB)

Islam, Z.

1999-05-10

This dissertation is concerned with the interplay of long-range order and anisotropy in the tetragonal RNi{sub 2}Ge{sub 2} (R = rare earth) family of compounds. Microscopic magnetic structures were studied using both neutron and x-ray resonant exchange scattering (XRES) techniques. The magnetic structures of Tb, Dy, Eu and Gd members have been determined using high-quality single-crystal samples. This work has correlated a strong Fermi surface nesting to the magnetic ordering in the RNi{sub 2}Ge{sub 2} compounds. Generalized susceptibility, {chi}{sub 0}(q), calculations found nesting to be responsible for both incommensurate ordering wave vector in GdNi{sub 2}Ge{sub 2}, and the commensurate structure in EuNi{sub 2}Ge{sub 2}. A continuous transition from incommensurate to commensurate magnetic structures via band filling is predicted. The surprisingly higher T{sub N} in EuNi{sub 2}Ge{sub 2} than that in GdNi{sub 2}Ge{sub 2} is also explained. Next, all the metamagnetic phases in TbNi{sub 2}Ge{sub 2} with an applied field along the c axis have been characterized with neutron diffraction measurements. A mixed phase model for the first metamagnetic structure consisting of fully-saturated as well as reduced-moment Tb ions is presented. The moment reduction may be due to moment instability which is possible if the exchange is comparable to the low-lying CEF level splitting and the ground state is a singlet. In such a case, certain Tb sites may experience a local field below the critical value needed to reach saturation.

Neutron scattering studies of the coexistence of long-range magnetic order and superconductivity in Dy12Mo6S8 and Tb12Mo6S8

International Nuclear Information System (INIS)

Thomlinson, W.; Shirane, G.; Moncton, D.E.; Ishikawa, M.; Fischer, O.

1978-10-01

Both Dy 1 2 Mo 6 S 8 and Tb 1 2 Mo 6 S 8 are superconducting below T/sub c/ = 2.05 K. Neutron scattering studies show that these compounds in zero applied magnetic field develop long-range antiferromagnetic order (greater than 300 A) at T/sub M/ = 0.4 K and T/sub M/ = 1.0 K, respectively, which does not destroy the superconducting state. Magnetization measurements at temperatures below T/sub M/ suggest the development of ferromagnetic order as the applied magnetic field increases. In the case of Tb 1 2 Mo 6 S 8 the neutron data show long-range ferromagnetic order developing for H greater than or equal to H/sub c2/ = 1.9 kOe where H/sub c2/ is the upper critical field for superconductivity. However, for Dy 1 2 Mo 6 S 8 long-range ferromagnetic order begins to develop at H = 200 Oe, a field much less than H/sub c2/ = 1.2 kOe. As the ferromagnetic intensity increases, the antiferromagnetic intensity decreases. Between H = 200 Oe and H = 1.2 kOe both ferromagnetic and antiferromagnetic order occur with the sample in the superconducting state

High-energy X-ray study of short range order and phase transformations in titanium-vanadium

International Nuclear Information System (INIS)

Ramsteiner, I.B.

2005-01-01

This work presents a study of configurational correlations and phase transformations in the binary alloy Ti-V, using high-energy X-ray diffraction. The experiments have been performed at the European Synchrotron Radiation Facility (ESRF) in Grenoble. The high-energy (60-100 keV) technique developed recently allows in-situ measurements on bulk material in transmission geometry. The first part of the thesis discusses multiple scattering effects which might occur with this method. These effects are experimentally verified and discussed. Special emphasis is put on the questions, whether they affect the results obtained with this method, and how they can be avoided. Understanding alloys on the most fundamental level requires knowledge about the atomic interaction potentials. Competing with entropy, these potentials determine the configurational short range order in a disordered alloy, which generates together with static and dynamic distortions the diffuse scattering. The thesis presents measurements and calculations of the diffuse scattering patterns of Ti-V. The calculations, taking into account configurational correlations, static distortions induced by atomic size mismatch and thermal diffuse scattering, agree with the experimental data. Structural transformations in Ti-V are carefully characterized using high-energy x-ray diffraction in combination with the complementary transmission electron microscopy (TEM). While the first technique allows to study the phenomena in-situ and time-resolved, TEM yields real space images and chemical information about the phases. Ti-V near the equiatomic composition is a beta-Ti-alloy. The body centered cubic beta phase is retained at room temperature by fast quenching. Aging the material below the phase transformation temperature, however, leads to the precipitation of hexagonal alpha titanium. Another transformation process confusing earlier works is identified as TiC formation from carbon impurities in the material. In addition

The Lunar Reconnaissance Orbiter, a Planning Tool for Missions to the Moon

Science.gov (United States)

Keller, J. W.; Petro, N. E.

2017-12-01

The Lunar Reconnaissance Orbiter Mission was conceived as a one year exploration mission to pave the way for a return to the lunar surface, both robotically and by humans. After a year in orbit LRO transitioned to a science mission but has operated in a duel role of science and exploration ever since. Over the years LRO has compiled a wealth of data that can and is being used for planning future missions to the Moon by NASA, other national agencies and by private enterprises. While collecting this unique and unprecedented data set, LRO's science investigations have uncovered new questions that motivate new missions and targets. Examples include: when did volcanism on the Moon cease, motivating a sample return mission from an irregular mare patch such as Ina-D; or, is there significant water ice sequestered near the poles outside of the permanently shaded regions? In this presentation we will review the data products, tools and maps that are available for mission planning, discuss how the operating LRO mission can further enhance future missions, and suggest new targets motivated by LRO's scientific investigations.

Short Range-Ordered Minerals: Insight into Aqueous Alteration Processes on Mars

Science.gov (United States)

Ming, Douglas W.; Morris, R. V.; Golden, D. C.

2011-01-01

Short range-ordered (SRO) aluminosilicates (e.g., allophane) and nanophase ferric oxides (npOx) are common SRO minerals derived during aqueous alteration of basaltic materials. NpOx refers to poorly crystalline or amorphous alteration products that can be any combination of superparamagnetic hematite and/or goethite, akaganeite, schwertmannite, ferrihydrite, iddingsite, and nanometer-sized ferric oxide particles that pigment palagonitic tephra. Nearly 30 years ago, SRO phases were suggested as alteration phases on Mars based on similar spectral properties for altered basaltic tephra on the slopes of Mauna Kea in Hawaii and Martian bright regions measured by Earth-based telescopes. Detailed characterization of altered basaltic tephra on Mauna Kea have identified a variety of alteration phases including allophane, npOx, hisingerite, jarosite, alunite, hematite, goethite, ferrihydrite, halloysite, kaolinite, smectite, and zeolites. The presence of npOx and other Fe-bearing minerals (jarosite, hematite, goethite) was confirmed by the M ssbauer Spectrometer onboard the Mars Exploration Rovers. Although the presence of allophane has not been definitely identified on Mars robotic missions, chemical analysis by the Spirit and Opportunity rovers and thermal infrared spectral orbital measurements suggest the presence of allophane or allophane-like phases on Mars. SRO phases form under a variety of environmental conditions on Earth ranging from cold and arid to warm and humid, including hydrothermal conditions. The formation of SRO aluminosilicates such as allophane (and crystalline halloysite) from basaltic material is controlled by several key factors including activity of water, extent of leaching, Si activity in solution, and available Al. Generally, a low leaching index (e.g., wet-dry cycles) and slightly acidic to alkaline conditions are necessary. NpOx generally form under aqueous oxidative weathering conditions, although thermal oxidative alteration may occasional be

Octacyanoniobate(IV)-based molecular magnets revealing 3D long-range order

International Nuclear Information System (INIS)

Pelka, R; Balanda, M; Pinkowicz, D; Drath, O; Nitek, W; Sieklucka, B; Rams, M; Majcher, A

2011-01-01

Isostructural series of chemical formula {[M II (pirazol) 4 ] 2 [Nb IV (CN) 8 ]· 4H 2 O} n (M II = Mn (1), Fe (2), Co (3), Ni (4)) has been obtained by the self-assembly technique. Its unique crystallographic structure consists in the formation of a 3D extended network of magnetic centers braced by geometrically identical cyanido bridges. Magnetic measurements reveal the transitions to the 3D order at temperatures 23.7, 8.3, 5.9, 13.4 K for 1, 2, 3, and 4, respectively. The character of order is demonstrated to be ferrimagnetic for 1 and 2 and ferromagnetic for 3 and 4. The mean-field approach is used to determine the corresponding exchange coupling constants. The observed interactions are discussed within the magnetic orbital model.

Octacyanoniobate(IV)-based molecular magnets revealing 3D long-range order

Science.gov (United States)

Pełka, R.; Pinkowicz, D.; Drath, O.; Bałanda, M.; Rams, M.; Majcher, A.; Nitek, W.; Sieklucka, B.

2011-07-01

Isostructural series of chemical formula {[MII(pirazol)4]2[NbIV(CN)8]· 4H2O}n (MII = Mn (1), Fe (2), Co (3), Ni (4)) has been obtained by the self-assembly technique. Its unique crystallographic structure consists in the formation of a 3D extended network of magnetic centers braced by geometrically identical cyanido bridges. Magnetic measurements reveal the transitions to the 3D order at temperatures 23.7, 8.3, 5.9, 13.4 K for 1, 2, 3, and 4, respectively. The character of order is demonstrated to be ferrimagnetic for 1 and 2 and ferromagnetic for 3 and 4. The mean-field approach is used to determine the corresponding exchange coupling constants. The observed interactions are discussed within the magnetic orbital model.

Is cell survival a determinant of the in situ response of 9L tumours

International Nuclear Information System (INIS)

Wheeler, K.T.; Wallen, C.A.

1980-01-01

The influence of growth rate, location, size and potential lethal damage (PLD) recovery on the cellular radiosensitivity and the tumour response was studied in 9L/Ro and 9L/SF rat tumours. The median day of death of rats bearing the intracerebral (i.c.) 9L/Ro tumours was 16-18 days; for i.c. 9L/SF tumours it was 23-25 days. The doubling time of 9L/Ro cells was slightly faster than for 9L/SF cells both in culture and in the brain. The cellular radiosensitivity of both i.c. tumour cell sublines was identical. However, subcutaneous (s.c.) 9L/Ro tumour cells were more resistant. There was no evidence of a substantial hypoxic fraction in either site. When i.c. 9L/Ro and 9L/SF tumours of similar size were treated with fractionated doses of BCNU, X-rays or combinations of the two, the responses of the two tumours were essentially identical. The rate of recovery from radiation-induced PLD was identical in the two sublines and the two sites. Increase in life-span of rats bearing i.c. 9L/Ro tumours appeared to be correlated with the tumour cell kill measured after completion of PLD recovery rather than with the tumour cell kill determined immediately after irradiation. (author)

Autonomous Target Ranging Techniques

DEFF Research Database (Denmark)

Jørgensen, Peter Siegbjørn; Jørgensen, John Leif; Denver, Troelz

2003-01-01

of this telescope, a fast determination of the range to and the motion of the detected targets are important. This is needed in order to prepare the future observation strategy for each target, i.e. when is the closest approach where imaging will be optimal. In order to quickly obtain such a determination two...... ranging strategies are presented. One is an improved laser ranger with an effective range with non-cooperative targets of at least 10,000 km, demonstrated in ground tests. The accuracy of the laser ranging will be approximately 1 m. The laser ranger may furthermore be used for trajectory determination...... of nano-gravity probes, which will perform direct mass measurements of selected targets. The other is triangulation from two spacecraft. For this method it is important to distinguish between detection and tracking range, which will be different for Bering since different instruments are used...

Application of long-range ordering in the synthesis of a nanoscale Ni2 (Cr,Mo) superlattice with high strength and high ductility

International Nuclear Information System (INIS)

Tawancy, H.M.; Aboelfotoh, M.O.

2009-01-01

We demonstrate that bulk nanoscale materials with high strength and high ductility can be synthesized by using long-range ordering in certain alloy systems. In the case of a Ni-18.6 atomic % Mo-15.1 atomic % Cr, a bulk nanoscale superlattice of Ni 2 (Cr,Mo) isomorphous with Pt 2 Mo has been synthesized by thermal aging at 700 deg. C. The superlattice is shown to have high strength and high ductility as well as high thermal stability. Although the yield strength is nearly doubled in the ordered state exceeding 800 MPa, the material is found to maintain about 70% of its initial tensile ductility corresponding to 42% engineering strain. This behavior has been related to the crystallography of the ordering transformation. Although most of the slip systems of the parent face-centered cubic lattice are suppressed by ordering, most of the twinning systems remain energetically favorable. Therefore, deformation in the ordered state is found to predominantly occur by twinning rather than by slip giving rise to the observed combination of high strength and high ductility

Enss' theory in long range scattering: Second order hyperbolic and parabolic operators

International Nuclear Information System (INIS)

Muthuramalingam, P.

1984-01-01

We prove asymptotic completeness using Enss' method for h 0 (P)+Wsub(S)(Q)+Wsub(L)(Q) where h 0 :Rsup(n) -> R is a polynomial of degree 2 with lim vertical strokeh 0 (zeta)vertical stroke +/nabla h 0 (zeta)vertical stroke = infinite, Wsub(S) a short range potential and Wsub(L) a smooth long range potential. (orig.)

Short-range order in ab initio computer generated amorphous and liquid Cu–Zr alloys: A new approach

International Nuclear Information System (INIS)

Galván-Colín, Jonathan; Valladares, Ariel A.; Valladares, Renela M.; Valladares, Alexander

2015-01-01

Using ab initio molecular dynamics and a new approach based on the undermelt-quench method we generated amorphous and liquid samples of Cu x Zr 100−x (x=64, 50, 36) alloys. We characterized the topology of our resulting structures by means of the pair distribution function and the bond-angle distribution; a coordination number distribution was also calculated. Our results for both amorphous and liquids agree well with experiment. Dependence of short-range order with the concentration is reported. We found that icosahedron-like geometry plays a major role whenever the alloys are Cu-rich or Zr-rich disregarding if the samples are amorphous or liquid. The validation of these results, in turn would let us calculate other properties so far disregarded in the literature

Octacyanoniobate(IV)-based molecular magnets revealing 3D long-range order

Energy Technology Data Exchange (ETDEWEB)

Pelka, R; Balanda, M [Institute of Physics PAN, Radzikowskiego 152, 31-342, Krakow (Poland); Pinkowicz, D; Drath, O; Nitek, W; Sieklucka, B [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Rams, M; Majcher, A, E-mail: robert.pelka@ifj.edu.pl [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland)

2011-07-06

Isostructural series of chemical formula {l_brace}[M{sup II}(pirazol){sub 4}]{sub 2}[Nb{sup IV}(CN){sub 8}]{center_dot} 4H{sub 2}O{r_brace}{sub n} (M{sup II} = Mn (1), Fe (2), Co (3), Ni (4)) has been obtained by the self-assembly technique. Its unique crystallographic structure consists in the formation of a 3D extended network of magnetic centers braced by geometrically identical cyanido bridges. Magnetic measurements reveal the transitions to the 3D order at temperatures 23.7, 8.3, 5.9, 13.4 K for 1, 2, 3, and 4, respectively. The character of order is demonstrated to be ferrimagnetic for 1 and 2 and ferromagnetic for 3 and 4. The mean-field approach is used to determine the corresponding exchange coupling constants. The observed interactions are discussed within the magnetic orbital model.

Absence of magnetic long-range order in Y2CrSbO7 : Bond-disorder-induced magnetic frustration in a ferromagnetic pyrochlore

Science.gov (United States)

Shen, L.; Greaves, C.; Riyat, R.; Hansen, T. C.; Blackburn, E.

2017-09-01

The consequences of random nonmagnetic-ion dilution for the pyrochlore family Y2(M 1 -xN x)2O7 (M = magnetic ion, N = nonmagnetic ion) have been investigated. As a first step, we experimentally examine the magnetic properties of Y2CrSbO7 (x =0.5 ), in which the magnetic sites (Cr3 +) are percolative. Although the effective Cr-Cr spin exchange is ferromagnetic, as evidenced by a positive Curie-Weiss temperature, ΘCW ≃19.5 K , our high-resolution neutron powder diffraction measurements detect no sign of magnetic long-range order down to 2 K. In order to understand our observations, we construct a lattice model to numerically study the bond disorder introduced by the ionic size mismatch between M and N , which reveals that the bond disorder percolates at xb ≃0.23 , explaining the absence of magnetic long-range order. This model could be applied to a series of frustrated magnets with a pyrochlore sublattice, for example, the spinel compound Zn (Cr1 -xGax )2O4 , wherein a Néel to spin glass phase transition occurs between x =0.2 and 0.25 [Lee et al., Phys. Rev. B 77, 014405 (2008), 10.1103/PhysRevB.77.014405]. Our study stresses the non-negligible role of bond disorder on magnetic frustration, even in ferromagnets.

Long-Range Order and Fractality in the Structure and Organization of Eukaryotic Genomes

Science.gov (United States)

Polychronopoulos, Dimitris; Tsiagkas, Giannis; Athanasopoulou, Labrini; Sellis, Diamantis; Almirantis, Yannis

2014-12-01

The late Professor J.S. Nicolis always emphasized, both in his writings and in presentations and discussions with students and friends, the relevance of a dynamical systems approach to biology. In particular, viewing the genome as a "biological text" captures the dynamical character of both the evolution and function of the organisms in the form of correlations indicating the presence of a long-range order. This genomic structure can be expressed in forms reminiscent of natural languages and several temporal and spatial traces l by the functioning of dynamical systems: Zipf laws, self-similarity and fractality. Here we review several works of our group and recent unpublished results, focusing on the chromosomal distribution of biologically active genomic components: Genes and protein-coding segments, CpG islands, transposable elements belonging to all major classes and several types of conserved non-coding genomic elements. We report the systematic appearance of power-laws in the size distribution of the distances between elements belonging to each of these types of functional genomic elements. Moreover, fractality is also found in several cases, using box-counting and entropic scaling.We present here, for the first time in a unified way, an aggregative model of the genomic dynamics which can explain the observed patterns on the grounds of known phenomena accompanying genome evolution. Our results comply with recent findings about a "fractal globule" geometry of chromatin in the eukaryotic nucleus.

Short- and medium-range order of atomic structure and electronic properties of arsenic salinide and sulphide amorphous films

International Nuclear Information System (INIS)

Sarsembinov, Sh.Sh.; Prikhodko, O.Yu.; Ryaguzov, A.P.; Maksimova, S.Ya.; Ushanov, V.Zh.

2004-01-01

Full text: The relationship between short- and medium-range order of atomic structure and electronic properties is the object of invariable attention of disordered matter physics. This problem is the most important for non-crystalline semiconductors, and specifically for chalcogenide glassy semiconductors (ChGS) films due to low co-ordination of atoms, which leads to lability of their structure. In this report we present results of atomic structure, electric, optical properties and carrier drift investigation in amorphous films of As 2 Se 3 and As 2 S 3 prepared by thermal evaporation in a vacuum (TE films) and by RF ion-plasma sputtering (RF films). These techniques strongly differing in the conditions of substance vaporization and condensation atoms on a substrate. The short- and medium-range order of the films atomic structure has been studied by X-ray diffraction analysis using the CuKα radiation (λ=1.5418 Angstrom) and by Raman spectroscopy. Raman spectra were measured at room temperature on Perkin-Elmer Spectrum GX Raman FT-IR Spectrometer (180 deg. backscattering). Vibrational modes were excited vertically polarized light of DPY Nd:YAG laser (1.064 μm). The radii of the first and second coordination spheres, number of the nearest neighbours of As and Se (S) atoms in the first coordination sphere, dimension of the medium-range order domain and 'quasi-period' in that region have been determined for the studied samples. The identification of the structural units in matrix of the film has been carried out, too. It is established that the films prepared by different methods have differences in the parameters of short- and medium range orders. It follows from the comparative analysis of Raman spectra that spectrum of RF films is significantly more complex than that of glass and TE films. The matrix of RF films contains, along with the structural units AsSe 3/2 (AsS 3/2 ) inherent in TE films and glass, other structural units with As and Se (S) excess. It may be

Dilatometry of nonstoichiometric titanium carbide in the range of order-disorder phase transformation

International Nuclear Information System (INIS)

Karpov, A.V.; Kobyakov, V.P.; Chernomorskaya, E.A.

1995-01-01

Method of dilatometry was used for investigation of TiC x (0.49 x in ordered and disordered states, as well as on transformation heat were obtained. Increase of bond strength in result of carbon atom ordering in carbon sublattice was noted. 14 refs., 6 figs

Two-Step Cycle for Producing Multiple Anodic Aluminum Oxide (AAO) Films with Increasing Long-Range Order.

Science.gov (United States)

Choudhary, Eric; Szalai, Veronika

2016-01-01

Nanoporous anodic aluminum oxide (AAO) membranes are being used for an increasing number of applications. However, the original two-step anodization method in which the first anodization is sacrificial to pre-pattern the second is still widely used to produce them. This method provides relatively low throughput and material utilization as half of the films are discarded. An alternative scheme that relies on alternating anodization and cathodic delamination is demonstrated that allows for the fabrication of several AAO films with only one sacrificial layer thus greatly improving total aluminum to alumina yield. The thickness for which the cathodic delamination performs best to yield full, unbroken AAO sheets is around 85 μm. Additionally, an image analysis method is used to quantify the degree of long-range ordering of the unit cells in the AAO films which was found to increase with each successive iteration of the fabrication cycle.

Probabilistic Risk Assessment (PRA): A Practical and Cost Effective Approach

Science.gov (United States)

Lee, Lydia L.; Ingegneri, Antonino J.; Djam, Melody

2006-01-01

The Lunar Reconnaissance Orbiter (LRO) is the first mission of the Robotic Lunar Exploration Program (RLEP), a space exploration venture to the Moon, Mars and beyond. The LRO mission includes spacecraft developed by NASA Goddard Space Flight Center (GSFC) and seven instruments built by GSFC, Russia, and contractors across the nation. LRO is defined as a measurement mission, not a science mission. It emphasizes the overall objectives of obtaining data to facilitate returning mankind safely to the Moon in preparation for an eventual manned mission to Mars. As the first mission in response to the President's commitment of the journey of exploring the solar system and beyond: returning to the Moon in the next decade, then venturing further into the solar system, ultimately sending humans to Mars and beyond, LRO has high-visibility to the public but limited resources and a tight schedule. This paper demonstrates how NASA's Lunar Reconnaissance Orbiter Mission project office incorporated reliability analyses in assessing risks and performing design tradeoffs to ensure mission success. Risk assessment is performed using NASA Procedural Requirements (NPR) 8705.5 - Probabilistic Risk Assessment (PRA) Procedures for NASA Programs and Projects to formulate probabilistic risk assessment (PRA). As required, a limited scope PRA is being performed for the LRO project. The PRA is used to optimize the mission design within mandated budget, manpower, and schedule constraints. The technique that LRO project office uses to perform PRA relies on the application of a component failure database to quantify the potential mission success risks. To ensure mission success in an efficient manner, low cost and tight schedule, the traditional reliability analyses, such as reliability predictions, Failure Modes and Effects Analysis (FMEA), and Fault Tree Analysis (FTA), are used to perform PRA for the large system of LRO with more than 14,000 piece parts and over 120 purchased or contractor

Short-range order in ab initio computer generated amorphous and liquid Cu–Zr alloys: A new approach

Energy Technology Data Exchange (ETDEWEB)

Galván-Colín, Jonathan, E-mail: jgcolin@ciencias.unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, México, D.F. 04510, México (Mexico); Valladares, Ariel A., E-mail: valladar@unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, México, D.F. 04510, México (Mexico); Valladares, Renela M.; Valladares, Alexander [Facultad de Ciencias, Universidad Nacional Autónoma de México, Apartado Postal 70-542, México, D.F. 04510, México (Mexico)

2015-10-15

Using ab initio molecular dynamics and a new approach based on the undermelt-quench method we generated amorphous and liquid samples of Cu{sub x}Zr{sub 100−x} (x=64, 50, 36) alloys. We characterized the topology of our resulting structures by means of the pair distribution function and the bond-angle distribution; a coordination number distribution was also calculated. Our results for both amorphous and liquids agree well with experiment. Dependence of short-range order with the concentration is reported. We found that icosahedron-like geometry plays a major role whenever the alloys are Cu-rich or Zr-rich disregarding if the samples are amorphous or liquid. The validation of these results, in turn would let us calculate other properties so far disregarded in the literature.

Short-range order in alloys of nickel with the elements of group VIII of the periodic table

International Nuclear Information System (INIS)

Khwaja, F.A.

1981-08-01

Experimental measurements of the diffuse X-ray scattering intensity were performed on alloys of Ni with Rh and Os. The atomic short-range order (SRO) parameters αsub(i) and the size-effect parameters βsub(i) were calculated from these measurements. It is established that SRO and size-effect exist in Ni-Rh and Ni-Os alloys analogously as in a few other alloys of Ni with the elements of group VIII of the periodic table. The experimental data was interpreted theoretically by calculating the interaction energies from the pseudo-potentials and the effective valencies of the individual components of the systems studied. It was found that theoretically calculated values of the interaction energies for these alloys are inconsistent with the experimentally determined sign of the SRO parameter. (author)

Long-range ordering of III-V semiconductor nanostructures by shallowly buried dislocation networks

International Nuclear Information System (INIS)

Coelho, J; Patriarche, G; Glas, F; Saint-Girons, G; Sagnes, I

2004-01-01

We account for lateral orderings of III-V nanostructures resulting from a GaAs/InAs/InGaAs/GaAs sequence grown on GaAs by metallorganic vapour phase epitaxy at two different temperatures. For both samples, the ordering is induced by the stress field of a periodic dislocation network (DN) shallowly buried and parallel to the surface. This DN is a grain boundary (GB) that forms, between a thin GaAs layer (on which growth was performed) and a GaAs substrate joined together by wafer bonding, in order to accommodate a tilt and a twist between these two crystals; both these misorientations are imposed in a controlled manner. This GB is composed of a one-dimensional network of mixed dislocations and of a one-dimensional network of screw dislocations. For both samples, the nanostructures observed by transmission electron microscopy (TEM) and atomic force microscopy are ordered by the underlying DN observed by TEM since they have same dimensions and orientations as the cells of the DN

Effects of short-range order on electronic properties of Zr-Ni glasses as seen from low-temperature specific heat

Science.gov (United States)

Kroeger, D. M.; Koch, C. C.; Scarbrough, J. O.; McKamey, C. G.

1984-02-01

Measurements of the low-temperature specific heat Cp of liquid-quenched Zr-Ni glasses for a large number of compositions in the range from 55 to 74 at.% Zr revealed an unusual composition dependence of the density of states at the Fermi level, N(EF). Furthermore, for some compositions the variation of Cp near the superconducting transition temperature Tc indicated the presence of two superconducting phases, i.e., two superconducting transitions were detected. Comparison of the individual Tc's in phase-separated samples to the composition dependence of Tc for all of the samples suggests that amorphous phases with compositions near 60 and 66.7 at.% Zr occur. We discuss these results in terms of an "association model" for liquid alloys (due to Sommer), in which associations of unlike atoms with definite stoichiometries are assumed to exist in equilibrium with unassociated atoms. We conclude that in the composition range studied, associate clusters with the compositions Zr3Ni2 and Zr2Ni occur. In only a few cases are the clusters sufficiently large, compared with the superconducting coherence length, for separate superconducting transitions to be observed. The variation of N(EF) with composition is discussed, as well as the effects of this chemical short-range ordering on the crystallization behavior and glass-forming tendency.

Application of long-range ordering in the synthesis of a nanoscale Ni{sub 2} (Cr,Mo) superlattice with high strength and high ductility

Energy Technology Data Exchange (ETDEWEB)

Tawancy, H.M. [Center for Engineering Research, Research Institute, King Fahd University of Petroleum and Minerals, P.O. Box 1639, Dhahran 31261 (Saudi Arabia)], E-mail: tawancy@kfupm.edu.sa; Aboelfotoh, M.O. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7909 (United States)

2009-01-25

We demonstrate that bulk nanoscale materials with high strength and high ductility can be synthesized by using long-range ordering in certain alloy systems. In the case of a Ni-18.6 atomic % Mo-15.1 atomic % Cr, a bulk nanoscale superlattice of Ni{sub 2}(Cr,Mo) isomorphous with Pt{sub 2}Mo has been synthesized by thermal aging at 700 deg. C. The superlattice is shown to have high strength and high ductility as well as high thermal stability. Although the yield strength is nearly doubled in the ordered state exceeding 800 MPa, the material is found to maintain about 70% of its initial tensile ductility corresponding to 42% engineering strain. This behavior has been related to the crystallography of the ordering transformation. Although most of the slip systems of the parent face-centered cubic lattice are suppressed by ordering, most of the twinning systems remain energetically favorable. Therefore, deformation in the ordered state is found to predominantly occur by twinning rather than by slip giving rise to the observed combination of high strength and high ductility.

Exploring the Inner Solar System During IPA

Science.gov (United States)

Weir, H. M.; Stockman, S. A.; Carter, B. L.; Bleacher, L. V.

2008-12-01

During 2009, the International Year of Astronomy, both the MESSENGER mission to Mercury and the Lunar Reconnaissance Orbiter (LRO) mission to orbit the Moon will use key mission milestones to engage the public. For the MESSENGER mission key millstones will be the release to the public of data from the Oct 6th 2008, flyby and the Sept 29th 2009 third and last Mercury flyby before MESSENGER orbits Mercury in 2011. IYA activities will include participating in 365 Days of Astronomy podcasts, making the second flyby data publicly available and exciting the public with images from the third flyby. The data from the first flyby can be seen in a variety of locations across the country on Science on a Sphere. During IYA, the MESSENGER mission will also be reaching a wide variety of audiences through social media networking such as Facebook and Twitter. Informal education communities will be able to include Mercury data in their IYA programming through the distribution of MESSENGER data through the NASA Museum Alliance. The LRO mission will return the public's attention to our nearest neighbor, the Moon, in 2009. As a result, the public will see high resolution images of the Moon never seen before. LRO will also engage the public in the lunar observation program. Starting in early 2009, LRO and Lunar CRater Observation and Sensing Satellite (LCROSS) will be launched, and will continue their science missions throughout IYA. The public will be encouraged to make observations of the Moon during critical maneuvers for the LRO and LCROSS missions, including the LCROSS encounter, impacting the Moon which will occur in 2009. These events will help shift the public's attention to the Moon, and highlight the role our nearest neighbor plays in helping scientists learn about the early history of our Solar System. In addition to viewing LRO images and observing the Moon, the public can learn about the Moon, LRO, LCROSS, and past lunar missions virtually via the "Return to the Moon Hall

Relationship between Magnetic Anisotropy below Pseudogap Temperature and Short-Range Antiferromagnetic Order in High-Temperature Cuprate Superconductor

Science.gov (United States)

Morinari, Takao

2018-06-01

The central issue in high-temperature cuprate superconductors is the pseudogap state appearing below the pseudogap temperature T*, which is well above the superconducting transition temperature. In this study, we theoretically investigate the rapid increase of the magnetic anisotropy below the pseudogap temperature detected by the recent torque-magnetometry measurements on YBa2Cu3Oy [Y. Sato et al., 10.1038/nphys4205" xlink:type="simple">Nat. Phys. 13, 1074 (2017)]. Applying the spin Green's function formalism including the Dzyaloshinskii-Moriya interaction arising from the buckling of the CuO2 plane, we obtain results that are in good agreement with the experiment and find a scaling relationship. Our analysis suggests that the characteristic temperature associated with the magnetic anisotropy, which coincides with T*, is not a phase transition temperature but a crossover temperature associated with the short-range antiferromagnetic order.

Short-range order in Fe-based metallic glasses: Wide-angle X-ray scattering studies

International Nuclear Information System (INIS)

Babilas, Rafał; Hawełek, Łukasz; Burian, Andrzej

2014-01-01

The local atomic structure of the Fe 80 B 20 , Fe 70 Nb 10 B 20 and Fe 62 Nb 8 B 30 glasses prepared in the form of ribbons has been studied by wide-angle X-ray scattering. Structural information about the amorphous ribbons has been derived from analysis of the radial distribution functions using the least-squares curve-fitting method. The obtained structural parameters indicate that Fe–Fe, Fe–B, Fe–Nb and Nb–B contributions are involved in the near-neighbor coordination spheres. The possible similarities of the local atomic arrangement in the investigated glasses and the crystalline Fe 3 B, Fe 23 B 6 and bcc Fe structures are also discussed. - Graphical abstract: Pair distribution functions (a) and best-fit model and experimental radial distribution functions for Fe 80 B 20 (b), Fe 70 Nb 10 B 20 (c) and Fe 62 Nb 8 B 30 (d) metallic glasses. - Highlights: • The short-range ordering in the Fe-based metallic glasses is presented. • The results of RDF function have been analyzed using the least-squares method. • The Fe–Fe, Fe–B, Fe–Nb or Nb–B contributions are involved in coordination spheres. • The structural unit is distorted triangular prism containing B, Fe or Nb atoms. • Similarities of atomic arrangement in glassy and crystalline structures are discussed

Ordered and Unordered Top-K Range Reporting in Large Data Sets

DEFF Research Database (Denmark)

Afshani, Peyman; Brodal, Gerth Stølting; Zeh, Norbert

2011-01-01

We study the following problem: Given an array A storing N real numbers, preprocess it to allow fast reporting of the K smallest elements in the subarray A[i, j] in sorted order, for any triple (i, j,K) with 1 ≤ i ≤ j ≤ N and 1 ≤ K ≤ j − i + 1. We are interested in scenarios where the array A is ...

Effect of crystalline electric fields and long-range magnetic order on superconductivity in rare earth alloys and compounds

International Nuclear Information System (INIS)

McCallum, R.W.

1977-01-01

The behavior of rare earth ions in a superconducting matrix has been studied in two distinct regimes. First, the effects of crystal field splitting of the 4f levels of a magnetic rare earth ion in the alloy system (LaPr)Sn 3 were investigated in the limit of low Pr 3+ concentration. In this system the rare earth impurity ions occupy random La sites in the crystal lattice. Second, the interaction of long-range magnetic order and superconductivity was explored in the ternary rare earth molybdenum chalcogenide systems. In these compounds the rare earth ions occupy periodic lattice sites in contrast to the random distribution of magnetic ions in dilute impurity alloy systems such as (LaPr)Sn 3

Effects of short-range order on electronic properties of Zr-Ni glasses as seen from low-temperature specific heat

International Nuclear Information System (INIS)

Kroeger, D.M.; Koch, C.C.; Scarbrough, J.O.; McKamey, C.G.

1984-01-01

Measurements of the low-temperature specific heat C/sub p/ of liquid-quenched Zr-Ni glasses for a large number of compositions in the range from 55 to 74 at. % Zr revealed an unusual composition dependence of the density of states at the Fermi level, N(E/sub F/). Furthermore, for some compositions the variation of C/sub p/ near the superconducting transition temperature T/sub c/ indicated the presence of two superconducting phases, i.e., two superconducting transitions were detected. Comparison of the individual T/sub c/'s in phase-separated samples to the composition dependence of T/sub c/ for all of the samples suggests that amorphous phases with compositions near 60 and 66.7 at. % Zr occur. We discuss these results in terms of an ''association model'' for liquid alloys (due to Sommer), in which associations of unlike atoms with definite stoichiometries are assumed to exist in equilibrium with unassociated atoms. We conclude that in the composition range studied, associate clusters with the compositions Zr 3 Ni 2 and Zr 2 Ni occur. In only a few cases are the clusters sufficiently large, compared with the superconducting coherence length, for separate superconducting transitions to be observed. The variation of N(E/sub F/) with composition is discussed, as well as the effects of this chemical short-range ordering on the crystallization behavior and glass-forming tendency

Mixed hyperfine interaction - a tool to investigate the short range order and the strange magnetic behaviour of amorphous Fe-based binary alloys

International Nuclear Information System (INIS)

Fries, S.M.; Crummenauer, J.; Gonser, U.; Schaaf, P.; Chien, C.L.

1989-01-01

The Moessbauer study of the mixed magnetic dipole and electric quadrupole interaction in the paramagnetic state of amorphous Fe-Zr and Fe-Hf alloys is presented. Strong evidence for chemical short range order of the iron-pure alloys is found. The hyperfine parameters of the iron-rich alloys are marked by a complex applied field and temperature dependence, suggesting a not negligible spin-correlation well above Tc. (orig.)

Heredity of medium-range order structure from melts to the microstructure of Ni-Cr-W superalloy

Energy Technology Data Exchange (ETDEWEB)

Gao, Zhongtang; Hu, Rui; Wang, Jun; Li, Jinshan [Northwestern Polytechnical University, State Key Laboratory of Solidification Processing, Xi' an (China)

2015-07-15

The structure factor S(Q), intensities and pair distribution function g(r) of liquid Ni-Cr-W superalloy at different temperatures have been measured by a high-temperature X-ray diffractometer. Coordination N{sub min}, correlation radius r{sub c}, the nearest atomic distance r{sub 1}, solidification microstructure and compression performance have been studied. The results show that a pre-peak exists on the structure factor curve at the liquidus temperature, and a fine structure of equiaxed, globular and non-dendritic primary grains can be achieved by casting the alloy at liquidus temperature. Liquid structure feature of Ni-Cr-W superalloy is found to depend on temperature. During the solidification, some structural information carried by the medium-range order (MRO) structure is inherited from the melt to the microstructure, which is beneficial for grain refinement. The maximum yield strength measured from typical microstructure of the equiaxed and non-dendritic grains at 1400 C is 543 MPa. The results show that refinement and non-dendritic grain is beneficial to the improvement of the yield strength. (orig.)

A 1-V 60-μW 85-dB dynamic range continuous-time third-order sigma-delta modulator

International Nuclear Information System (INIS)

Li Yuanwen; Qi Da; Dong Yifeng; Xu Jun; Ren Junyan

2009-01-01

A 1-V third order one-bit continuous-time (CT) EA modulator is presented. Designed in the SMIC mixed-signal 0.13-μm CMOS process, the modulator utilizes active RC integrators to implement the loop filter. An efficient circuit design methodology for the CT ΣΔ modulator is proposed and verified. Low power dissipation is achieved through the use of two-stage class A/AB amplifiers. The presented modulator achieves 81.4-dB SNDR and 85-dB dynamic range in a 20-kHz bandwidth with an over sampling ratio of 128. The total power consumption of the modulator is only 60 μW from a 1-V power supply and the prototype occupies an active area of 0.12 mm 2 . (semiconductor integrated circuits)

Metabolic link between phosphatidylethanolamine and triacylglycerol metabolism in the yeast Saccharomyces cerevisiae.

Science.gov (United States)

Horvath, Susanne E; Wagner, Andrea; Steyrer, Ernst; Daum, Günther

2011-12-01

In the yeast Saccharomyces cerevisiae triacylglycerols (TAG) are synthesized by the acyl-CoA dependent acyltransferases Dga1p, Are1p, Are2p and the acyl-CoA independent phospholipid:diacylglycerol acyltransferase (PDAT) Lro1p which uses phosphatidylethanolamine (PE) as a preferred acyl donor. In the present study we investigated a possible link between TAG and PE metabolism by analyzing the contribution of the four different PE biosynthetic pathways to TAG formation, namely de novo PE synthesis via Psd1p and Psd2p, the CDP-ethanolamine (CDP-Etn) pathway and lyso-PE acylation by Ale1p. In cells grown on the non-fermentable carbon source lactate supplemented with 5mM ethanolamine (Etn) the CDP-Etn pathway contributed most to the cellular TAG level, whereas mutations in the other pathways displayed only minor effects. In cki1∆dpl1∆eki1∆ mutants bearing defects in the CDP-Etn pathway both the cellular and the microsomal levels of PE were markedly decreased, whereas in other mutants of PE biosynthetic routes depletion of this aminoglycerophospholipid was less pronounced in microsomes. This observation is important because Lro1p similar to the enzymes of the CDP-Etn pathway is a component of the ER. We conclude from these results that in cki1∆dpl1∆eki1∆ insufficient supply of PE to the PDAT Lro1p was a major reason for the strongly reduced TAG level. Moreover, we found that Lro1p activity was markedly decreased in cki1∆dpl1∆eki1∆, although transcription of LRO1 was not affected. Our findings imply that (i) TAG and PE syntheses in the yeast are tightly linked; and (ii) TAG formation by the PDAT Lro1p strongly depends on PE synthesis through the CDP-Etn pathway. Moreover, it is very likely that local availability of PE in microsomes is crucial for TAG synthesis through the Lro1p reaction. Copyright © 2011 Elsevier B.V. All rights reserved.

On the long-range order of Lieb-Mattis model of quantum antiferromagnet

International Nuclear Information System (INIS)

Gochev, I.G.; Tonchev, N.S.

1991-09-01

The spontaneous magnetization m and the root-mean-square order parameter m 0 of the Lieb-Mattis model for arbitrary temperature and spin values s are obtained. For the ratio r(T,s)=m/m 0 the value r(T,s)=√3 is found. (author). 8 refs

Multiple-Zone Diffractive Optic Element for Laser Ranging Applications

Science.gov (United States)

Ramos-Izquierdo, Luis A.

2011-01-01

A diffractive optic element (DOE) can be used as a beam splitter to generate multiple laser beams from a single input laser beam. This technology has been recently used in LRO s Lunar Orbiter Laser Altimeter (LOLA) instrument to generate five laser beams that measure the lunar topography from a 50-km nominal mapping orbit (see figure). An extension of this approach is to use a multiple-zone DOE to allow a laser altimeter instrument to operate over a wider range of distances. In particular, a multiple-zone DOE could be used for applications that require both mapping and landing on a planetary body. In this case, the laser altimeter operating range would need to extend from several hundred kilometers down to a few meters. The innovator was recently involved in an investigation how to modify the LOLA instrument for the OSIRIS asteroid mapping and sample return mission. One approach is to replace the DOE in the LOLA laser beam expander assembly with a multiple-zone DOE that would allow for the simultaneous illumination of the asteroid with mapping and landing laser beams. The proposed OSIRIS multiple-zone DOE would generate the same LOLA five-beam output pattern for high-altitude topographic mapping, but would simultaneously generate a wide divergence angle beam using a small portion of the total laser energy for the approach and landing portion of the mission. Only a few percent of the total laser energy is required for approach and landing operations as the return signal increases as the inverse square of the ranging height. A wide divergence beam could be implemented by making the center of the DOE a diffractive or refractive negative lens. The beam energy and beam divergence characteristics of a multiple-zone DOE could be easily tailored to meet the requirements of other missions that require laser ranging data. Current single-zone DOE lithographic manufacturing techniques could also be used to fabricate a multiple-zone DOE by masking the different DOE zones during

A medium range order structural connection to the configurational heat capacity of borate-silicate mixed glasses.

Science.gov (United States)

Liu, Hao; Smedskjaer, Morten M; Tao, Haizheng; Jensen, Lars R; Zhao, Xiujian; Yue, Yuanzheng

2016-04-28

It has been reported that the configurational heat capacity (C(p,conf)) first increases and then becomes saturated with increasing B2O3/SiO2 ratio in borate-silicate mixed glasses. Through Raman spectroscopy measurements, we have, in this work, found an implication for the intermediate range order (IRO) structural connection to the composition dependence of the C(p,conf) of borate-silicate mixed glasses. In the silica-rich compositions, the C(p,conf) rapidly increases with increasing B2O3 content. This is attributed to the increase of the content of the B-O-Si network units ([B2Si2O8](2-)) and 6-membered borate rings with 1 or 2 B(4). In the boron-rich compositions, the C(p,conf) is almost constant, independent of the increase in the B2O3/SiO2 ratio. This is likely attributed to the counteraction between the decrease of the fraction of two types of metaborate groups and the increase of the fraction of other borate superstructural units (particularly 6-membered borate rings). The overall results suggest that the glasses containing more types of superstructural units have a larger C(p,conf).

Order Management - Today's focus

DEFF Research Database (Denmark)

Barfod, Ari

1996-01-01

Small and mid-range companies throughout the world have moved towards customer-specific production during the last few years, but often, the order flow has not changed to meet new demands. Customer orders pass through a laarge number of departments, such as sales, construction, pre...... to the final product.In the paper, a new method for improving order flow is presented, including an extended use of activity chain models....

Building on the Cornerstone: Destinations for Nearside Sample Return

Science.gov (United States)

Lawrence, S. J.; Jolliff, B. L.; Draper, D.; Stopar, J. D.; Petro, N. E.; Cohen, B. A.; Speyerer, E. J.; Gruener, J. E.

2016-01-01

Discoveries from LRO (Lunar Reconnaissance Orbiter) have transformed our knowledge of the Moon, but LRO's instruments were originally designed to collect the measurements required to enable future lunar surface exploration. Compelling science questions and critical resources make the Moon a key destination for future human and robotic exploration. Lunar surface exploration, including rovers and other landed missions, must be part of a balanced planetary science and exploration portfolio. Among the highest planetary exploration priorities is the collection of new samples and their return to Earth for more comprehensive analysis than can be done in-situ. The Moon is the closest and most accessible location to address key science questions through targeted sample return. The Moon is the only other planet from which we have contextualized samples, yet critical issues need to be addressed: we lack important details of the Moon's early and recent geologic history, the full compositional and age ranges of its crust, and its bulk composition.

All-optical 1st- and 2nd-order differential equation solvers with large tuning ranges using Fabry-Pérot semiconductor optical amplifiers.

Science.gov (United States)

Chen, Kaisheng; Hou, Jie; Huang, Zhuyang; Cao, Tong; Zhang, Jihua; Yu, Yuan; Zhang, Xinliang

2015-02-09

We experimentally demonstrate an all-optical temporal computation scheme for solving 1st- and 2nd-order linear ordinary differential equations (ODEs) with tunable constant coefficients by using Fabry-Pérot semiconductor optical amplifiers (FP-SOAs). By changing the injection currents of FP-SOAs, the constant coefficients of the differential equations are practically tuned. A quite large constant coefficient tunable range from 0.0026/ps to 0.085/ps is achieved for the 1st-order differential equation. Moreover, the constant coefficient p of the 2nd-order ODE solver can be continuously tuned from 0.0216/ps to 0.158/ps, correspondingly with the constant coefficient q varying from 0.0000494/ps(2) to 0.006205/ps(2). Additionally, a theoretical model that combining the carrier density rate equation of the semiconductor optical amplifier (SOA) with the transfer function of the Fabry-Pérot (FP) cavity is exploited to analyze the solving processes. For both 1st- and 2nd-order solvers, excellent agreements between the numerical simulations and the experimental results are obtained. The FP-SOAs based all-optical differential-equation solvers can be easily integrated with other optical components based on InP/InGaAsP materials, such as laser, modulator, photodetector and waveguide, which can motivate the realization of the complicated optical computing on a single integrated chip.

Co-existence of long-range order and spin fluctuation in a new geometric frustration series M2(OH)3Cl

International Nuclear Information System (INIS)

Zheng, X.G.; Hagihala, Masato; Toriyi, Takato

2007-01-01

Recently, we observed the co-existence of a long-range magnetic order and spin fluctuation in a clean compound of clinoatacamite, Cu 2 (OH) 3 Cl (PRL95 (2005) 057201). The present work reports magnetic studies on other compounds of this transition metal series M 2 (OH) 3 Cl, where M represents three-dimensional (3D)-electron magnetic ions of Co 2+ , Fe 2+ , etc., respectively. The present study shows that this co-existence is a common feature of the M 2 Cl(OH) 3 series, no matter whether it is anti-ferromagnetic, as in the case of Fe 2 (OH) 3 Cl (T N =15 K), or ferromagnetic, as in the case of Co 2 (OH) 3 Cl (T C =10.5 K). These compounds show a 3D network of corner-sharing tetrahedrons for the magnetic ions. The tetrahedron is slightly tilted with roughly 10% longer distance between the M-M bonded by Cl than those bonded by O and this distortion is suspected to be responsible for the partial order. This research suggests that the transition metal hydroxyhalide M 2 Cl(OH) 3 series are new geometric frustration system on tetrahedral lattice for d-electron spins

Short range charge/orbital ordering in La{sub 1-x}Sr{sub x}Mn{sub 1-z}B{sub z}O{sub 3} (B Cu,Zn) manganites

Energy Technology Data Exchange (ETDEWEB)

Popovic, Z V [Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia (Spain); Cantarero, A [Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia (Spain); Thijssen, W H A [Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia (Spain); Paunovic, N [Centre for Solid State Physics and New Materials, Institute of Physics, PO Box 68, 11080 Belgrade/Zemun (Serbia and Montenegro); Dohcevic-Mitrovic, Z [Centre for Solid State Physics and New Materials, Institute of Physics, PO Box 68, 11080 Belgrade/Zemun (Serbia and Montenegro); Sapina, F [Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia (Spain)

2005-01-19

We have measured the reflectivity spectra of La{sub 1-x}Sr{sub x}Mn{sub 1-z}B{sub z}O{sub 3} (B = Cu, Zn; 0.17 {<=} x {<=} 0.30; 0 {<=} z {<=} 0.10) manganites over wide frequency (100-4000 cm{sup -1}) and temperature (80-300 K) ranges. Besides the previously observed infrared active modes or mode pairs at about 160 cm{sup -1} (external mode), 350 cm{sup -1} (bond bending mode) and 590 cm{sup -1} (bond stretching mode), we have clearly observed two additional phonon modes at about 645 and 720 cm{sup -1} below the temperature T{sub 1} (T{sub 1}range charge/orbitally ordered domains. The temperature T{sub 1} of the phase transition is dependent on the doping concentration and for optimally doped samples we have found that T{sub 1} {approx}(0.93 {+-} 0.02) T{sub C}. Electrical resistivity and magnetization measurements versus temperature and magnetic field support the short range charge/orbital ordering scenario.

The search for Ar in the lunar atmosphere using the Lunar Reconnaissance Orbiter's LAMP instrument.

Science.gov (United States)

Cook, J. C.; Stern, S. A.; Feldman, P. D.; Gladstone, R.; Retherford, K. D.; Greathouse, T. K.; Grava, C.

2014-12-01

The Apollo 17 mass spectrometer, LACE, first measured mass 40 particles in the lunar atmosphere, and over a nine-month period, detected variations correlated with the lunar day (Hoffman et al., 1973, LPSC, 4, 2865). LACE detected a high particle density at dusk (0.6-1.0x104 cm-3), decreasing through the lunar night to a few hundred cm-3, then increasing rapidly before dawn to levels 2-4 times greater than at dusk. No daytime measurements were made due to instrument saturation. Given the LACE measurements' periodic nature, and the Ar abundance in lunar regolith samples (Kaiser, 1972, EPSL, 13, 387), it was concluded that mass 40 was likely due to Ar. Benna et al. (2014, LPSC, 45, 1535) recently reported that the Neutral Mass Spectrometer (NMS) aboard LADEE also detected Ar (mass 40) with similar diurnal profiles. We report on UV spectra of the lunar atmosphere as obtained by the Lunar Reconnaissance Orbiter (LRO). Aboard LRO is the UV-spectrograph, LAMP (Lyman Alpha Mapping Project), spanning the spectral range 575 to 1965 Å. LAMP is typically oriented toward the surface and has been mapping the Moon since September 2009. LAMP also observes the tenuous lunar atmosphere when the surface is in darkness, but the atmospheric column below LRO is illuminated. We have previously used nadir oriented twilight observations to examine the sparse lunar atmosphere (Feldman et al., 2012, Icarus, 221, 854; Cook et al., 2013, Icarus, 225, 681; Stern et al., 2013, Icarus, 226, 1210; Cook & Stern 2014, Icarus, 236, 48). In Cook et al., 2013, we reported an upper limit for Ar of 2.3x104 cm-3. Since then, we have collected additional data and refined our search method by focusing on the regions (near equator) and local times (dawn and dusk) where Ar has been reported previously. We have carefully considered effective area calibration and g-factor accuracies and find these to be unlikely explanations for the order of magnitude differences. We will report new results, which provide much

Lunar geodesy and cartography: a new era

Science.gov (United States)

Duxbury, Thomas; Smith, David; Robinson, Mark; Zuber, Maria T.; Neumann, Gregory; Danton, Jacob; Oberst, Juergen; Archinal, Brent; Glaeser, Philipp

The Lunar Reconnaissance Orbiter (LRO) ushers in a new era in precision lunar geodesy and cartography. LRO was launched in June, 2009, completed its Commissioning Phase in Septem-ber 2009 and is now in its Primary Mission Phase on its way to collecting high precision, global topographic and imaging data. Aboard LRO are the Lunar Orbiter Laser Altimeter (LOLA -Smith, et al., 2009) and the Lunar Reconnaissance Orbiter Camera (LROC -Robinson, et al., ). LOLA is a derivative of the successful MOLA at Mars that produced the global reference surface being used for all precision cartographic products. LOLA produces 5 altimetry spots having footprints of 5 m at a frequency of 28 Hz, significantly bettering MOLA that produced 1 spot having a footprint of 150 m at a frequency of 10 Hz. LROC has twin narrow angle cameras having pixel resolutions of 0.5 meters from a 50 km orbit and a wide-angle camera having a pixel resolution of 75 m and in up to 7 color bands. One of the two NACs looks to the right of nadir and the other looks to the left with a few hundred pixel overlap in the nadir direction. LOLA is mounted on the LRO spacecraft to look nadir, in the overlap region of the NACs. The LRO spacecraft has the ability to look nadir and build up global coverage as well as looking off-nadir to provide stereo coverage and fill in data gaps. The LROC wide-angle camera builds up global stereo coverage naturally from its large field-of-view overlap from orbit to orbit during nadir viewing. To date, the LROC WAC has already produced global stereo coverage of the lunar surface. This report focuses on the registration of LOLA altimetry to the LROC NAC images. LOLA has a dynamic range of tens of km while producing elevation data at sub-meter precision. LOLA also has good return in off-nadir attitudes. Over the LRO mission, multiple LOLA tracks will be in each of the NAC images at the lunar equator and even more tracks in the NAC images nearer the poles. The registration of LOLA

Absence of a long-range ordered magnetic ground state in Pr3Rh4Sn13 studied through specific heat and inelastic neutron scattering

Science.gov (United States)

Nair, Harikrishnan S.; Ogunbunmi, Michael O.; Ghosh, S. K.; Adroja, D. T.; Koza, M. M.; Guidi, T.; Strydom, A. M.

2018-04-01

Signatures of absence of a long-range ordered magnetic ground state down to 0.36 K are observed in magnetic susceptibility, specific heat, thermal/electrical transport and inelastic neutron scattering data of the quasi-skutterudite compound Pr3Rh4Sn13 which crystallizes in the Yb3Rh4Sn13-type structure with a cage-like network of Sn atoms. In this structure, Pr3+ occupies a lattice site with D 2d point symmetry having a ninefold degeneracy corresponding to J  =  4. The magnetic susceptibility of Pr3Rh4Sn13 shows only a weak temperature dependence below 10 K otherwise remaining paramagnetic-like in the range, 10 K-300 K. From the inelastic neutron scattering intensity of Pr3Rh4Sn13 recorded at different temperatures, we identify excitations at 4.5(7) K, 5.42(6) K, 10.77(5) K, 27.27(5) K, 192.28(4) K and 308.33(3) K through a careful peak analysis. However, no signatures of long-range magnetic order are observed in the neutron data down to 1.5 K, which is also confirmed by the specific heat data down to 0.36 K. A broad Schottky-like peak is recovered for the magnetic part of the specific heat, C 4f, which suggests the role of crystal electric fields of Pr3+ . A crystalline electric field model consisting of 7 levels was applied to C 4f which leads to the estimation of energy levels at 4.48(2) K, 6.94(4) K, 11.23(8) K, 27.01(5) K, 193.12(6) K and 367.30(2) K. The CEF energy levels estimated from the heat capacity analysis are in close agreement with the excitation energies seen in the neutron data. The Sommerfeld coefficient estimated from the analysis of magnetic specific heat is γ = 761(6) mJ K-2 mol-Pr which suggests the formation of heavy itinerant quasi-particles in Pr3Rh4Sn13. Combining inelastic neutron scattering results, analysis of the specific heat data down to 0.36 K, magnetic susceptibility and, electrical and thermal transport, we establish the absence of long-range ordered magnetic ground state in Pr3Rh4Sn13.

Structure of short-range-ordered iron(III)-precipitates formed by iron(II) oxidation in water containing phosphate, silicate, and calcium

Science.gov (United States)

Voegelin, A.; Frommer, J.; Vantelon, D.; Kaegi, R.; Hug, S. J.

2009-04-01

The oxidation of Fe(II) in water leads to the formation of Fe(III)-precipitates that strongly affect the fate of nutrients and contaminants in natural and engineered systems. Examples include the cycling of As in rice fields irrigated with As-rich groundwater or the treatment of drinking water for As removal. Knowledge of the types of Fe(III)-precipitates forming in such systems is essential for the quantitative modeling of nutrient and contaminant dynamics and for the optimization of water purification techniques on the basis of a mechanistic understanding of the relevant biogeochemical processes. In this study, we investigated the local coordination of Fe, P, and Ca in Fe(III)-precipitates formed by aeration of synthetic Fe(II)-containing groundwater with variable composition (pH 7, 2-30 mg/L Fe(II), 2-20 mg/L phosphate-P, 2-20 mg/L silicate-Si, 8 mM Na-bicarbonate or 2.5 mM Ca-&1.5 mM Mg-bicarbonate). After 4 hours of oxidation, Fe(III)-precipitates were collected on 0.2 µm nylon filters and dried. The precipitates were analyzed by Fe K-edge EXAFS (XAS beamline, ANKA, Germany) and by P and Ca K-edge XANES spectroscopy (LUCIA beamline, SLS, Switzerland). The Fe K-edge EXAFS spectra indicated that local Fe coordination in the precipitates systematically shifted with water composition. As long as water contained P, mainly short-range-ordered Fe(III)-phosphate formed (with molar P/Fe ~0.5). In the absence of P, Fe(III) precipitated as hydrous ferric oxide at high Si/Fe>0.5, as ferrihydrite at intermediate Si/Fe, and mainly as lepidocrocite at Si/Fe<0.2. Analysis of the EXAFS by shell-fitting indicated that Fe(III)-phosphates mainly contained mono- or oligomeric (edge- or corner-sharing) Fe and that the linkage between neighboring Fe(III)-octahedra changed from predominantly edge-sharing in Si-rich hydrous ferric oxide to edge- and corner-sharing in ferrihydrite. Electron microscopic data showed that changes in local precipitate structure were systematically

Phase transition type change in order-order and order-disorder transformations of LaH2+c-like superstoichiometric dihydrides

International Nuclear Information System (INIS)

Ratishvili, I.G.

1999-01-01

Phase transformations in metal-hydrogen systems associated with the ordering processes in the subsystem of interstitial hydrogen atoms are considered. It is shown that in a particular class of superstoichiometric rare-earth dihydrides, where the ordering subsystem is characterized by two long-range-order parameters η 1 , η 2 and the energy parameter p 0 (1) (p) ≤ c ≤ c 0 (2) (p), it becomes discontinuous outside of this region. Dependence of critical concentrations c 0 (1) and c 0 (2) upon the energy parameter p is deduced. It is shown, as well, that there exists a second sequence of critical concentrations, c 1 (1) (p) and c 1 (2) (p), denoting the boundaries between the regions of continuous and discontinuous order-disorder transformations. (orig.)

Correlation between short-range order, optical properties and UV-absorption ability in tellurate glasses; Poster M7

Energy Technology Data Exchange (ETDEWEB)

Burger, H; Tews, W; Vogel, W; Kozhukharov, V [Jena Univ. (Germany)

1989-01-01

Tellurate glasses, with as second components Al[sub 2]O[sub 3], PbO, PbF[sub 2], PbCl[sub 2], PbBr[sub 2], PbSO[sub 4], ZnO, B[sub 2]O[sub 3], P[sub 2]O[sub 5], Li[sub 2]O, Na[sub 2]O, K[sub 2]O, MgO and BaO as well as some glasses from ternary TeO[sub 2]-P[sub 2]O[sub 5]-RO systems (R is Pb, Ba and Zn ions), have been investigated. Transmittance spectra in UV and VIS region of some selected glasses have been measured. A correlation between optical properties and UV absorption edge of the transmittance have been done. Using p[sup 31]-NMR spectroscopy the structural changes on short-range level order are studied. A strong influence on the refraction and dispersion values as well as UV-absorption ability of the glasses is established. For p[sup 31] -NMR spectroscopy investigations of crystalline phosphotellurites and related phosphotellurite glasses the TeO[sub 2]-P[sub 2]O[sub 5B]aO ternary system have been chosen. (author).

Grain Refinement by Authigenic Inoculation Inherited from the Medium-Range Order Structure of Ni-Cr-W Superalloy

Science.gov (United States)

Gao, Zhongtang; Hu, Rui; Guo, Wei; Zhang, Chuanwei

2018-05-01

The combination of liquidus casting and thermal control solidification furnace was applied to obtain a fine-grained ingot. A rapid quenching method and x-ray diffraction measurement were used to investigate the effect of authigenic inoculation on grain refinement. The structure factor S( Q) of liquid Ni -Cr-W superalloy at 1400 °C (Liquidus temperature) and bright-field image of the microstructures quenched from 1400 °C have been measured by the high-temperature x-ray diffractometer and the transmission electron microscopy (TEM), respectively. The results show that a pre-peak exists on a S( Q) curve at the liquidus temperature. The clusters of atom in rapidly quenched microstructures obtained by isothermal heat treatment at 1400 °C were studied using TEM. Meanwhile, the effect of isothermal different temperatures on rapidly quenched microstructures was studied. The results also show that there are only the globular, equiaxed grains distributed in the solidification structure. These particles are inherited from the medium-range order structure, which is beneficial for grain refinement. The normalized work-hardening rate-strain curve indicates the work-hardening rate of fine grain is higher than that of conventional grain at the same temperature and the same deformation.

Photoinduced ultrafast charge-order melting: Charge-order inversion and nonthermal effects

International Nuclear Information System (INIS)

Veenendaal, Michel van

2016-01-01

The effect of photoexcitation is studied for a system with checkerboard charge order induced by displacements of ligands around a metal site. The motion of the ligands is treated classically and the electronic charges are simplified to two-level molecular bond charges. The calculations are done for a checkerboard charge-ordered system with about 100 000 ligand oscillators coupled to a fixed-temperature bath. The initial photoexcitation is followed by a rapid decrease in the charge-order parameter within 50–100 femtoseconds while leaving the correlation length almost unchanged. Depending on the fluence, a complete melting of the charge order occurs in less than a picosecond. While for low fluences, the system returns to its original state, for full melting, it recovers to its broken-symmetry state leading to an inversion of the charge order. Finally, for small long-range interactions, recovery can be slow due to domain formation.

Experimental demonstration of fractional-order oscillators of orders 2.6 and 2.7

KAUST Repository

Elwakil, A.S.; Agambayev, Agamyrat; Allagui, A.; Salama, Khaled N.

2017-01-01

The purpose of this work is to provide an experimental demonstration for the development of sinusoidal oscillations in a fractional-order Hartley-like oscillator. Solid-state fractional-order electric double-layer capacitors were first fabricated using graphene-percolated P(VDF-TrFE-CFE) composite structure, and then characterized by using electrochemical impedance spectroscopy. The devices exhibit the fractional orders of 0.6 and 0.74 respectively (using the model Zc=Rs+1/(jω)αCα), with the corresponding pseudocapacitances of approximately 93nFsec−0.4 and 1.5nFsec−0.26 over the frequency range 200kHz–6MHz (Rs < 15Ω). Then, we verified using these fractional-order devices integrated in a Hartley-like circuit that the fractional-order oscillatory behaviors are of orders 2.6 and 2.74.

Experimental demonstration of fractional-order oscillators of orders 2.6 and 2.7

KAUST Repository

Elwakil, A.S.

2017-02-07

The purpose of this work is to provide an experimental demonstration for the development of sinusoidal oscillations in a fractional-order Hartley-like oscillator. Solid-state fractional-order electric double-layer capacitors were first fabricated using graphene-percolated P(VDF-TrFE-CFE) composite structure, and then characterized by using electrochemical impedance spectroscopy. The devices exhibit the fractional orders of 0.6 and 0.74 respectively (using the model Zc=Rs+1/(jω)αCα), with the corresponding pseudocapacitances of approximately 93nFsec−0.4 and 1.5nFsec−0.26 over the frequency range 200kHz–6MHz (Rs < 15Ω). Then, we verified using these fractional-order devices integrated in a Hartley-like circuit that the fractional-order oscillatory behaviors are of orders 2.6 and 2.74.

Coexistence of short- and long-range ferromagnetic order in nanocrystalline Fe2Mn1−xCuxAl (x=0.0, 0.1 and 0.3) synthesized by high-energy ball milling

International Nuclear Information System (INIS)

Thanh, Tran Dang; Nanto, Dwi; Tuyen, Ngo Thi Uyen; Nan, Wen-Zhe; Yu, YiKyung; Tartakovsky, Daniel M.; Yu, S.C.

2015-01-01

In this work, we prepared nanocrystalline Fe 2 Mn 1−x Cu x Al (x=0.0, 0.1 and 0.3) powders by the high energy ball milling technique, and then studied their critical properties. Our analysis reveals that the increase of Cu-doping concentration (up to x=0.3) in these powders leads to a gradual increase of the ferromagnetic–paramagnetic transition temperature from 406 to 452 K. The Banerjee criterion suggests that all the samples considered undergo a second-order phase transition. A modified Arrott plot and scaling analysis indicate that the critical exponents (β=0.419 and 0.442, γ=1.082 and 1.116 for x=0.0 and 0.1, respectively) are located in between those expected for the 3D-Heisenberg and the mean-field models; the values of β=0.495 and γ=1.046 for x=0.3 sample are very close to those of the mean-field model. These features reveal the coexistence of the short- and long-range ferromagnetic order in the nanocrystalline Fe 2 Mn 1−x Cu x Al powders. Particularly, as the concentration of Cu increases, values of the critical exponent shift towards those of the mean-field model. Such results prove the Cu doping favors establishing a long-range ferromagnetic order. - Highlights: • Fe 2 Mn 1−x Cu x Al nanocrystals were prepared by a high energy ball milling method. • A coexistence of the short- and long-range FM order in the nanocrystals. • Cu doping favors establishing a long-range FM order in the nanocrystals. • All the ΔS m (T, H) data are followed a universal master curve

Genus Ranges of 4-Regular Rigid Vertex Graphs.

Science.gov (United States)

Buck, Dorothy; Dolzhenko, Egor; Jonoska, Nataša; Saito, Masahico; Valencia, Karin

2015-01-01

A rigid vertex of a graph is one that has a prescribed cyclic order of its incident edges. We study orientable genus ranges of 4-regular rigid vertex graphs. The (orientable) genus range is a set of genera values over all orientable surfaces into which a graph is embedded cellularly, and the embeddings of rigid vertex graphs are required to preserve the prescribed cyclic order of incident edges at every vertex. The genus ranges of 4-regular rigid vertex graphs are sets of consecutive integers, and we address two questions: which intervals of integers appear as genus ranges of such graphs, and what types of graphs realize a given genus range. For graphs with 2 n vertices ( n > 1), we prove that all intervals [ a, b ] for all a genus ranges. For graphs with 2 n - 1 vertices ( n ≥ 1), we prove that all intervals [ a, b ] for all a genus ranges. We also provide constructions of graphs that realize these ranges.

Z-Contrast STEM Imaging of Long-Range Ordered Structures in Epitaxially Grown CoPt Nanoparticles

Directory of Open Access Journals (Sweden)

Kazuhisa Sato

2013-01-01

Full Text Available We report on atomic structure imaging of epitaxial L10 CoPt nanoparticles using chemically sensitive high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM. Highly ordered nanoparticles formed by annealing at 973 K show single-variant structure with perpendicular c-axis orientation, while multivariant ordered domains are frequently observed for specimens annealed at 873 K. It was found that the (001 facets of the multivariant particles are terminated by Co atoms rather than by Pt, presumably due to the intermediate stage of atomic ordering. Coexistence of single-variant particles and multivariant particles in the same specimen film suggests that the interfacial energy between variant domains be small enough to form such structural domains in a nanoparticle as small as 4 nm in diameter.

Multiple order reflections in crystal neutron monochromators

International Nuclear Information System (INIS)

Fulfaro, R.

1976-01-01

A study of the higher order reflections in neutron crystal monochromators was made in order to obtain, for the IEA single crystal spectrometer, the operation range of 1,0eV to 0,01eV. Two crystals were studied, an Al(III) near 1,0eV and a Ge(III) in lower energies. For the Ge(III) case the higher order contaminations in the reflected beam were determined using as standard the gold total neutron cross section and performing the crystal reflectivity calculation for several orders of reflection. The knowledge of the contamination for each order as a function of neutron wavelength allows the optimization of the filter thickness in order to avoid higher order neutrons. The Ge(III) crystal was used because its second order reflections are theoretically forbidden, giving an advantage on other crystals, since measurements can be made until 0.02eV directly without filters. In the energy range 0.02 to 0.01eV, order contaminations higher than the second are present, therefore, either quartz filters are employed or calculated corrections are applied to the experimental data. The Al(III) crystal was used in order to estimate the second order contamination effect, in the iridium resonance measurements, at E 0 = 0.654eV. In that region, approximations can be made and it was not necessary to make the crystal reflectivity calculation for the filters thickness optimization. Since only the second order affects the results in that region, tellurium was used for the filtration, because this element has a resonance in the range of neutrons with energy 4E [pt

Atom-vacancy ordering and magnetic susceptibility of nonstoichiometric hafnium carbide

International Nuclear Information System (INIS)

Gusev, A.I.; Zyryanova, A.N.

1999-01-01

Experimental results on magnetic susceptibility of nonstoichiometric hafnium carbide HfC y (0.6 0.71 , HfC 0.78 and HfC 0.83 in the range of 870-930 K the anomalies are revealed which are associated with superstructure short-range ordering in a non-metallics sublattice. It is shown that a short-range order in HfC 0.71 and HfC 0.78 carbides corresponds to Hf 3 C 2 ordered phase, and in HfC 0.83 carbide - to Hf 6 C 5 ordered phase. HfC 0.78 carbide is found to possesses zero magnetic susceptibility in temperature range 910-980 K [ru

Specific heat and magnetic susceptibility vs long range order in V3Ga

International Nuclear Information System (INIS)

Junod, A.; Fluekiger, R.; Treyvaud, A.; Muller, J.

1976-01-01

A new technique of studying the magnetic susceptibility together with the specific heat and the superconducting transition of typical A15-type compounds in different ordering states enables us to consistently isolate the spin paramagnetism. Satisfactory results are obtained for V 3 Ga and these are compared with data on V 3 Au and Nb 3 (Au-Pt). (author)

Absence of magnetic long range order in Ba3ZnRu2O9. A spin-liquid candidate in the S = 3/2 dimer lattice

International Nuclear Information System (INIS)

Terasaki, Ichiro; Igarashi, Taichi; Nagai, Takayuki

2017-01-01

We have discovered a novel candidate for a spin liquid state in a ruthenium oxide composed of dimers of S = 3/2 spins of Ru 5+ , Ba 3 ZnRu 2 O 9 . This compound lacks a long range order down to 37 mK, which is a temperature 5000-times lower than the magnetic interaction scale of around 200 K. Partial substitution for Zn can continuously vary the magnetic ground state from an antiferromagnetic order to a spin-gapped state through the liquid state. This indicates that the spin-liquid state emerges from a delicate balance of inter- and intra-dimer interactions, and the spin state of the dimer plays a vital role. This unique feature should realize a new type of quantum magnetism. (author)

On Dynamic Range Limitations of CMOS Current Conveyors

DEFF Research Database (Denmark)

Bruun, Erik

1999-01-01

frequency band and for the situation where the conveyor is used over the full bandwidth achievable. Finally, the optimisation of the current input range is related to the distortion characteristics and it is pointed out that to a first order approximation the distortion is independent of the current range.......This paper is concerned with the dynamic range of continuous time CMOS current mode circuits. As a representative current mode device a class AB current conveyor is examined. First, the voltage input range of the high impedance Y input is investigated. Next, the current input range of the low...... impedance X input is investigated. It is compared to the thermal noise in the X to Z signal path in order to evaluate the dynamic range, and the dependencies of the dynamic range on the supply voltage and the transistor lay-out is derived, both for the situation where the conveyor is used over a narrow...

Range-separated density-functional theory for molecular excitation energies

International Nuclear Information System (INIS)

Rebolini, E.

2014-01-01

Linear-response time-dependent density-functional theory (TDDFT) is nowadays a method of choice to compute molecular excitation energies. However, within the usual adiabatic semi-local approximations, it is not able to describe properly Rydberg, charge-transfer or multiple excitations. Range separation of the electronic interaction allows one to mix rigorously density-functional methods at short range and wave function or Green's function methods at long range. When applied to the exchange functional, it already corrects most of these deficiencies but multiple excitations remain absent as they need a frequency-dependent kernel. In this thesis, the effects of range separation are first assessed on the excitation energies of a partially-interacting system in an analytic and numerical study in order to provide guidelines for future developments of range-separated methods for excitation energy calculations. It is then applied on the exchange and correlation TDDFT kernels in a single-determinant approximation in which the long-range part of the correlation kernel vanishes. A long-range frequency-dependent second-order correlation kernel is then derived from the Bethe-Salpeter equation and added perturbatively to the range-separated TDDFT kernel in order to take into account the effects of double excitations. (author)

Hydrothermal stability investigation of micro- and mesoporous silica containing long-range ordered cobalt oxide clusters by XAS.

Science.gov (United States)

Liu, Liang; Wang, David K; Kappen, Peter; Martens, Dana L; Smart, Simon; Diniz da Costa, João C

2015-07-15

This work investigates the hydrothermal stability of cobalt doped silica materials with different Co/Si molar ratios (0, 0.05, 0.10, and 0.25). The resultant materials were characterized by N2 sorption and chemical structures by Raman and X-ray absorption spectroscopy before and after a harsh hydrothermal exposure (550 °C, 75 mol% vapour and 40 h). The cobalt silica materials showed a lower surface area loss from 48% to 12% with increasing Co/Si molar ratio from 0.05 to 0.25 and relatively maintaining their pore size distribution, while pure silica exhibited significant surface area reduction (80%) and pore size broadening. For low cobalt loading sample (Co/Si = 0.05), the cobalt was highly dispersed in the silica network in a tetrahedral coordination with oxygen and a small proportion of Co-Co interaction in the second shell. Long range order Co3O4 was observed when Co/Si molar ratio increased to 0.10 and 0.25. The hydrothermal exposure did not affect the local cobalt environments and no cobalt-silicon interaction was observed by X-ray absorption spectroscopy. The hydrothermal stability of the silica matrix was attributed to the physical barrier of cobalt oxide in opposing densification and silica mobility under harsh hydrothermal conditions.

Lunar Reconnaissance Orbiter Lunar Workshops for Educators, Year 1 Report

Science.gov (United States)

Jones, A. P.; Hsu, B. C.; Bleacher, L.; Shaner, A. J.; Dalton, H.

2011-12-01

This past summer, the Lunar Reconnaissance Orbiter (LRO) sponsored a series of weeklong professional development workshops designed to educate and inspire grade 6-12 science teachers: the Lunar Workshops for Educators. Participants learned about lunar science and exploration, gained tools to help address common student misconceptions about the Moon, heard some of the latest research results from LRO scientists, worked with LRO data, and learned how to bring these data to their students using hands-on activities aligned with grade 6-12 National Science Education Standards and Benchmarks. Where possible, the workshops also included tours of science facilities or field trips intended to help the teachers better understand mission operations or geologic processes relevant to the Moon. The workshops were very successful. Participants demonstrated an improved understanding of lunar science concepts in post-workshop assessments (as compared to identical pre-assessments) and a greater understanding of how to access and productively share data from LRO with their students and provide them with authentic research experiences. Participant feedback on workshop surveys was also enthusiastically positive. 5 additional Lunar Workshops for Educators will be held around the country in the summer of 2012. For more information and to register, visit http://lunar.gsfc.nasa.gov/lwe/index.html.

Short, intermediate and mesoscopic range order in sulfur-rich binary glasses

International Nuclear Information System (INIS)

Bychkov, E.; Miloshova, M.; Price, D.L.; Benmore, C.J.; Lorriaux, A.

2006-01-01

Pulsed neutron and high-energy X-ray diffraction, small-angle neutron scattering, Raman spectroscopy and DSC were used to study structural changes on the short, intermediate and mesoscopic range scale for sulfur-rich AsS x (x (ge) 1.5) and GeS x (x (ge) 2) glasses. Two structural regions were found in the both systems. (1) Between stoichiometric (As 2 S 3 and GeS 2 ) and 'saturated' (AsS 2.2 and GeS 2.7 ) compositions, excessive sulfur atoms form sulfur dimers and/or short chains, replacing bridging sulfur in corner-sharing AsS 3/2 and GeS 4/2 units. (2) Above the 'saturated' compositions at (As) x system) appear in the glass network. The glasses become phase separated with the domains of 20-50 (angstrom), presumably enriched with sulfur rings. The longer chains Sn are not stable and crystallize to c-S 8 on ageing of a few days to several months, depending on composition.

Chemical short range order and magnetic correction in liquid manganese–gallium zero alloy

Energy Technology Data Exchange (ETDEWEB)

Grosdidier, B. [Laboratoire de Chimie Physique – Approche Multi-Echelle des Milieux Complexes, Institut Jean Bariol, Université de Lorraine, Institut de Chimie, Physique et Matériaux, 1 Bd Arago, 57078 Metz Cedex 3 (France); Ben Abdellah, A. [Laboratoire de Chimie Physique – Approche Multi-Echelle des Milieux Complexes, Institut Jean Bariol, Université de Lorraine, Institut de Chimie, Physique et Matériaux, 1 Bd Arago, 57078 Metz Cedex 3 (France); Innovation and Management of Industrial Systems, Abdelmalek Essaadi University, College of Sciences and Techniques of Tangier , P.O. Box 416, Postal code 90000, Tangier (Morocco); Université Internationale de Rabat, Parc Technopolis Rabat-Shore, 11100 Sala El Jadida (Morocco); Osman, S.M., E-mail: osm@squ.edu.om [Physics Department, College of Science, Sultan Qaboos University, P.O. Box 36, Postal Code 123, Al-Khod, Muscat (Oman); Ataati, J. [Innovation and Management of Industrial Systems, Abdelmalek Essaadi University, College of Sciences and Techniques of Tangier, P.O. Box 416, Postal code 90000, Tangier (Morocco); Gasser, J.G. [Laboratoire de Chimie Physique – Approche Multi-Echelle des Milieux Complexes, Institut Jean Bariol, Université de Lorraine, Institut de Chimie, Physique et Matériaux, 1 Bd Arago, 57078 Metz Cedex 3 (France)

2015-12-15

The Mn{sub 66}Ga{sub 34} alloy at this particular composition is known to be zero alloy in which the linear combination of the two neutron scattering lengths weighted by the atomic compositions vanish. Thus for this specific concentration, the effect of the partial structure factors S{sub NN} and S{sub NC} is cancelled by a weighted term, which value is zero. Then the measured total structure factor S(q) gives directly the concentration–concentration structure factor S{sub CC}(q). We present here the first experimental results of neutron diffraction on the Mn{sub 66}Ga{sub 34} “null matrix alloy” at 1050 °C. The main peak of the experimental S{sub CC}(q) gives a strong evidence of a hetero-atomic chemical order in this coordinated alloy. This order also appears in real space radial distribution function which is calculated by the Fourier transform of the structure factor. The degree of hetero-coordination is discussed together with other manganese-polyvalent alloys. However manganese also shows abnormal magnetic scattering in the alloy structure factor which must be corrected. This correction gives an experimental information on the mean effective spin of manganese in this liquid alloy. We present the first critical theoretical calculations of the magnetic correction factor in Mn–Ga zero-alloy based on our accurate experimental measurements of S{sub CC}(q).

Growth of epitaxially oriented Ag nanoislands on air-oxidized Si(1 1 1)-(7 × 7) surfaces: Influence of short-range order on the substrate

International Nuclear Information System (INIS)

Roy, Anupam; Bhattacharjee, K.; Ghatak, J.; Dev, B.N.

2012-01-01

Clean Si(1 1 1)-(7 × 7) surfaces, followed by air-exposure, have been investigated by reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). Fourier transforms (FTs) of STM images show the presence of short-range (7 × 7) order on the air-oxidized surface. Comparison with FTs of STM images from a clean Si(1 1 1)-(7 × 7) surface shows that only the 1/7th order spots are present on the air-oxidized surface. The oxide layer is ∼2-3 nm thick, as revealed by cross-sectional transmission electron microscopy (XTEM). Growth of Ag islands on these air-oxidized Si(1 1 1)-(7 × 7) surfaces has been investigated by in situ RHEED and STM and ex situ XTEM and scanning electron microscopy. Ag deposition at room temperature leads to the growth of randomly oriented Ag islands while preferred orientation evolves when Ag is deposited at higher substrate temperatures. For deposition at 550 °C face centered cubic Ag nanoislands grow with a predominant epitaxial orientation [11 ¯ 0] Ag ||[11 ¯ 0] Si , (1 1 1) Ag || (1 1 1) Si along with its twin [1 ¯ 10] Ag ||[11 ¯ 0] Si , (1 1 1) Ag || (1 1 1) Si , as observed for epitaxial growth of Ag on Si(1 1 1) surfaces. The twins are thus rotated by a 180° rotation of the Ag unit cell about the Si[1 1 1] axis. It is intriguing that Ag nanoislands follow an epitaxial relationship with the Si(1 1 1) substrate in spite of the presence of a 2-3 nm thick oxide layer between Ag and Si. Apparently the short-range order on the oxide surface influences the crystallographic orientation of the Ag nanoislands.

One-dimensional long-range percolation: A numerical study

Science.gov (United States)

Gori, G.; Michelangeli, M.; Defenu, N.; Trombettoni, A.

2017-07-01

In this paper we study bond percolation on a one-dimensional chain with power-law bond probability C /rd +σ , where r is the distance length between distinct sites and d =1 . We introduce and test an order-N Monte Carlo algorithm and we determine as a function of σ the critical value Cc at which percolation occurs. The critical exponents in the range 0 values for Cc are compared with a known exact bound, while the critical exponent ν is compared with results from mean-field theory, from an expansion around the point σ =1 and from the ɛ -expansion used with the introduction of a suitably defined effective dimension deff relating the long-range model with a short-range one in dimension deff. We finally present a formulation of our algorithm for bond percolation on general graphs, with order N efficiency on a large class of graphs including short-range percolation and translationally invariant long-range models in any spatial dimension d with σ >0 .

Higher-order glass-transition singularities in systems with short-ranged attractive potentials

International Nuclear Information System (INIS)

Goetze, W; Sperl, M

2003-01-01

Within the mode-coupling theory for the evolution of structural relaxation, the A 4 -glass-transition singularities are identified for systems of particles interacting with a hard-sphere repulsion complemented by different short-ranged potentials: Baxter's singular potential regularized by a large-wavevector cut-off, a model for the Asakura-Oosawa depletion attraction, a triangular potential, a Yukawa attraction, and a square-well potential. The regular potentials yield critical packing fractions, critical Debye-Waller factors, and critical amplitudes very close to each other. The elastic moduli and the particle localization lengths for corresponding states of the Yukawa system and the square-well system may differ by up to 20 and 10%, respectively

Electronically Tunable Fully Integrated Fractional-Order Resonator

KAUST Repository

Tsirimokou, Georgia

2017-03-20

A fully integrated implementation of a parallel fractional-order resonator which employs together a fractional order capacitor and a fractional-order inductor is proposed in this paper. The design utilizes current-controlled Operational Transconductance Amplifiers as building blocks, designed and fabricated in AMS 0:35m CMOS process, and based on a second-order approximation of a fractional-order differentiator/ integrator magnitude optimized in the range 10Hz–700Hz. An attractive benefit of the proposed scheme is its electronic tuning capability.

Electronically Tunable Fully Integrated Fractional-Order Resonator

KAUST Repository

Tsirimokou, Georgia; Psychalinos, Costas; Elwakil, Ahmed S.; Salama, Khaled N.

2017-01-01

A fully integrated implementation of a parallel fractional-order resonator which employs together a fractional order capacitor and a fractional-order inductor is proposed in this paper. The design utilizes current-controlled Operational Transconductance Amplifiers as building blocks, designed and fabricated in AMS 0:35m CMOS process, and based on a second-order approximation of a fractional-order differentiator/ integrator magnitude optimized in the range 10Hz–700Hz. An attractive benefit of the proposed scheme is its electronic tuning capability.

Infinitely robust order and local order-parameter tulips in Apollonian networks with quenched disorder

Science.gov (United States)

Kaplan, C. Nadir; Hinczewski, Michael; Berker, A. Nihat

2009-06-01

For a variety of quenched random spin systems on an Apollonian network, including ferromagnetic and antiferromagnetic bond percolation and the Ising spin glass, we find the persistence of ordered phases up to infinite temperature over the entire range of disorder. We develop a renormalization-group technique that yields highly detailed information, including the exact distributions of local magnetizations and local spin-glass order parameters, which turn out to exhibit, as function of temperature, complex and distinctive tulip patterns.

Ground-state properties of ordered, partially ordered, and random Cu-Au and Ni-Pt alloys

DEFF Research Database (Denmark)

Ruban, Andrei; Abrikosov, I. A.; Skriver, Hans Lomholt

1995-01-01

We have studied the ground-state properties of ordered, partially ordered, and random Cu-Au and Ni-Pt alloys at the stoichiometric 1/4, 1/2, and 3/4 compositions in the framework of the multisublattice single-site (SS) coherent potential approximation (CPA). Charge-transfer effects in the random ...... for the ordered alloys are in good agreement with experimental data. For all the alloys the calculated ordering energy and the equilibrium lattices parameters are found to be almost exact quadratic functions of the long-range-order parameter....... and the partially ordered alloys are included in the screened impurity model. The prefactor in the Madelung energy is determined by the requirement that the total energy obtained in direct SS CPA calculations should equal the total energy given by the Connolly-Williams expansion based on Green’s function...

Effect of high-temperature quenching on the magnetostructural transformations and the long-range atomic order of Ni–Mn–Sn and Ni–Mn–Sb metamagnetic shape memory alloys

International Nuclear Information System (INIS)

Sánchez-Alarcos, V.; Pérez-Landazábal, J.I.; Recarte, V.; Lucia, I.; Vélez, J.; Rodríguez-Velamazán, J.A.

2013-01-01

The influence of high-temperature thermal treatments on the martensitic transformation and the magnetic properties of Ni–Mn–Sn and Ni–Mn–Sb metamagnetic shape memory alloys have been investigated by calorimetric and magnetic measurements. Contrary to Ni–Mn–Ga and Ni–Mn–In systems, the martensitic transformation and Curie temperatures of Ni–Mn–Sn and Ni–Mn–Sb alloys are found to be unaffected by the increasing quenching temperature. Neutron diffraction measurements confirm the null effect of quenching on the next-nearest-neighbors atomic order due to the negligible L2 1 atomic disorder achieved with high-temperature annealings. The analysis of long-range order also suggests that no L2 1 –B2 ordering transition takes place in the studied alloys, thus indicating an unusually high stability of the L2 1 structure. The obtained results show that the magnetostructural properties of Ni–Mn–Sn and Ni–Mn–Sb alloys cannot be properly tuned by means of standard thermal treatments

Nanoporous anodic aluminum oxide with a long-range order and tunable cell sizes by phosphoric acid anodization on pre-patterned substrates

Science.gov (United States)

Surawathanawises, Krissada; Cheng, Xuanhong

2014-01-01

Nanoporous anodic aluminum oxide (AAO) has been explored for various applications due to its regular cell arrangement and relatively easy fabrication processes. However, conventional two-step anodization based on self-organization only allows the fabrication of a few discrete cell sizes and formation of small domains of hexagonally packed pores. Recent efforts to pre-pattern aluminum followed with anodization significantly improve the regularity and available pore geometries in AAO, while systematic study of the anodization condition, especially the impact of acid composition on pore formation guided by nanoindentation is still lacking. In this work, we pre-patterned aluminium thin films using ordered monolayers of silica beads and formed porous AAO in a single-step anodization in phosphoric acid. Controllable cell sizes ranging from 280 nm to 760 nm were obtained, matching the diameters of the silica nanobead molds used. This range of cell size is significantly greater than what has been reported for AAO formed in phosphoric acid in the literature. In addition, the relationships between the acid concentration, cell size, pore size, anodization voltage and film growth rate were studied quantitatively. The results are consistent with the theory of oxide formation through an electrochemical reaction. Not only does this study provide useful operational conditions of nanoindentation induced anodization in phosphoric acid, it also generates significant information for fundamental understanding of AAO formation. PMID:24535886

Measuring the relativistic perigee advance with satellite laser ranging

CERN Document Server

Iorio, L; Pavlis, E C

2002-01-01

The pericentric advance of a test body by a central mass is one of the classical tests of general relativity. Today, this effect is measured with radar ranging by the perihelion shift of Mercury and other planets in the gravitational field of the Sun, with a relative accuracy of the order of 10 sup - sup 2 -10 sup - sup 3. In this paper, we explore the possibility of a measurement of the pericentric advance in the gravitational field of Earth by analysing the laser-ranged data of some orbiting, or proposed, laser-ranged geodetic satellites. Such a measurement of the perigee advance would place limits on hypothetical, very weak, Yukawa-type components of the gravitational interaction with a finite range of the order of 10 sup 4 km. Thus, we show that, at the present level of knowledge of the orbital perturbations, the relative accuracy, achievable with suitably combined orbital elements of LAGEOS and LAGEOS II, is of the order of 10 sup - sup 3. With the corresponding measured value of (2 + 2 gamma - beta)/3, ...

Prediction of Lunar Reconnaissance Orbiter Reaction Wheel Assembly Angular Momentum Using Regression Analysis

Science.gov (United States)

DeHart, Russell

2017-01-01

This study determines the feasibility of creating a tool that can accurately predict Lunar Reconnaissance Orbiter (LRO) reaction wheel assembly (RWA) angular momentum, weeks or even months into the future. LRO is a three-axis stabilized spacecraft that was launched on June 18, 2009. While typically nadir-pointing, LRO conducts many types of slews to enable novel science collection. Momentum unloads have historically been performed approximately once every two weeks with the goal of maintaining system total angular momentum below 70 Nms; however flight experience shows the models developed before launch are overly conservative, with many momentum unloads being performed before system angular momentum surpasses 50 Nms. A more accurate model of RWA angular momentum growth would improve momentum unload scheduling and decrease the frequency of these unloads. Since some LRO instruments must be deactivated during momentum unloads and in the case of one instrument, decontaminated for 24 hours there after a decrease in the frequency of unloads increases science collection. This study develops a new model to predict LRO RWA angular momentum. Regression analysis of data from October 2014 to October 2015 was used to develop relationships between solar beta angle, slew specifications, and RWA angular momentum growth. The resulting model predicts RWA angular momentum using input solar beta angle and mission schedule data. This model was used to predict RWA angular momentum from October 2013 to October 2014. Predictions agree well with telemetry; of the 23 momentum unloads performed from October 2013 to October 2014, the mean and median magnitude of the RWA total angular momentum prediction error at the time of the momentum unloads were 3.7 and 2.7 Nms, respectively. The magnitude of the largest RWA total angular momentum prediction error was 10.6 Nms. Development of a tool that uses the models presented herein is currently underway.

Short-range order in irradiated diamonds

International Nuclear Information System (INIS)

Agafonov, S.S.; Glazkov, V.P.; Nikolaenko, V.A.; Somenkov, V.A.

2005-01-01

Structural changes in irradiated diamond with a change in its density were studied. Natural diamond powders with average particle size from 14-20 μm to 0.5 mm, irradiated in beryllium block of the MR reactor up to a fluence of 1.51 x 10 21 were used as samples. Using the neutron-diffraction method, it has been established that, when density in irradiated diamonds varies, a transition from a diamond-like amorphous structure to a graphite-like structure occurs. The transition occurs at a density ρ ∼ 2.7-2.9 g/cm 3 and is accompanied by a sharp change in resistivity [ru

Short range order in amorphous polycondensates

Energy Technology Data Exchange (ETDEWEB)

Lamers, C.; Richter, D.; Schweika, W. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Festkoerperforschung; Batoulis, J.; Sommer, K. [Bayer AG, Leverkusen (Germany); Cable, J.W. [Oak Ridge National Lab., TN (United States); Shapiro, S.M. [Brookhaven National Lab., Upton, NY (United States)

1992-12-01

The static coherent structure factors S(Q) of the polymer glass Bisphenol-A-Polycarbonate and its chemical variation Bisphenol-A- Polyctherkctone- both in differently deuterated versions- have been measured by spin polarized neutron scattering. The method of spin polarization analysis provided an experimental separation of coherent and incoherent scattering and a reliable intensity calibration. Results are compared to structure factors calculated for model structures which were obtained by ``amorphous cell`` computer simulations. In general reasonable agreement is found between experiment and simulation; however, certain discrepancies hint at an insufficient structural relaxation in the amorphous cell method. 15 refs, 1 fig, 1 tab.

Short range order of selenite glasses

Czech Academy of Sciences Publication Activity Database

Neov, Dimitar; Gerasimova, I.; Yordanov, S.; Lakov, L.; Mikula, Pavol; Lukáš, Petr; Dimitriev, Y.

1999-01-01

Roč. 40, č. 2 (1999), s. 111-112 ISSN 0031-9090 R&D Projects: GA ČR GV202/97/K038; GA AV ČR KSK1048601 Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.822, year: 1999

Visual Control of Robots Using Range Images

Directory of Open Access Journals (Sweden)

Fernando Torres

2010-08-01

Full Text Available In the last years, 3D-vision systems based on the time-of-flight (ToF principle have gained more importance in order to obtain 3D information from the workspace. In this paper, an analysis of the use of 3D ToF cameras to guide a robot arm is performed. To do so, an adaptive method to simultaneous visual servo control and camera calibration is presented. Using this method a robot arm is guided by using range information obtained from a ToF camera. Furthermore, the self-calibration method obtains the adequate integration time to be used by the range camera in order to precisely determine the depth information.

Order of wetting transitions in electrolyte solutions.

Science.gov (United States)

Ibagon, Ingrid; Bier, Markus; Dietrich, S

2014-05-07

For wetting films in dilute electrolyte solutions close to charged walls we present analytic expressions for their effective interface potentials. The analysis of these expressions renders the conditions under which corresponding wetting transitions can be first- or second-order. Within mean field theory we consider two models, one with short- and one with long-ranged solvent-solvent and solvent-wall interactions. The analytic results reveal in a transparent way that wetting transitions in electrolyte solutions, which occur far away from their critical point (i.e., the bulk correlation length is less than half of the Debye length) are always first-order if the solvent-solvent and solvent-wall interactions are short-ranged. In contrast, wetting transitions close to the bulk critical point of the solvent (i.e., the bulk correlation length is larger than the Debye length) exhibit the same wetting behavior as the pure, i.e., salt-free, solvent. If the salt-free solvent is governed by long-ranged solvent-solvent as well as long-ranged solvent-wall interactions and exhibits critical wetting, adding salt can cause the occurrence of an ion-induced first-order thin-thick transition which precedes the subsequent continuous wetting as for the salt-free solvent.

A comparison of zero-order, first-order, and Monod biotransformation models

International Nuclear Information System (INIS)

Bekins, B.A.; Warren, E.; Godsy, E.M.

1998-01-01

Under some conditions, a first-order kinetic model is a poor representation of biodegradation in contaminated aquifers. Although it is well known that the assumption of first-order kinetics is valid only when substrate concentration, S, is much less than the half-saturation constant, K S , this assumption is often made without verification of this condition. The authors present a formal error analysis showing that the relative error in the first-order approximation is S/K S and in the zero-order approximation the error is K S /S. They then examine the problems that arise when the first-order approximation is used outside the range for which it is valid. A series of numerical simulations comparing results of first- and zero-order rate approximations to Monod kinetics for a real data set illustrates that if concentrations observed in the field are higher than K S , it may be better to model degradation using a zero-order rate expression. Compared with Monod kinetics, extrapolation of a first-order rate to lower concentrations under-predicts the biotransformation potential, while extrapolation to higher concentrations may grossly over-predict the transformation rate. A summary of solubilities and Monod parameters for aerobic benzene, toluene, and xylene (BTX) degradation shows that the a priori assumption of first-order degradation kinetics at sites contaminated with these compounds is not valid. In particular, out of six published values of K S for toluene, only one is greater than 2 mg/L, indicating that when toluene is present in concentrations greater than about a part per million, the assumption of first-order kinetics may be invalid. Finally, the authors apply an existing analytical solution for steady-state one-dimensional advective transport with Monod degradation kinetics to a field data set

Conformal invariance in the long-range Ising model

Directory of Open Access Journals (Sweden)

Miguel F. Paulos

2016-01-01

Full Text Available We consider the question of conformal invariance of the long-range Ising model at the critical point. The continuum description is given in terms of a nonlocal field theory, and the absence of a stress tensor invalidates all of the standard arguments for the enhancement of scale invariance to conformal invariance. We however show that several correlation functions, computed to second order in the epsilon expansion, are nontrivially consistent with conformal invariance. We proceed to give a proof of conformal invariance to all orders in the epsilon expansion, based on the description of the long-range Ising model as a defect theory in an auxiliary higher-dimensional space. A detailed review of conformal invariance in the d-dimensional short-range Ising model is also included and may be of independent interest.

Conformal Invariance in the Long-Range Ising Model

CERN Document Server

Paulos, Miguel F; van Rees, Balt C; Zan, Bernardo

2016-01-01

We consider the question of conformal invariance of the long-range Ising model at the critical point. The continuum description is given in terms of a nonlocal field theory, and the absence of a stress tensor invalidates all of the standard arguments for the enhancement of scale invariance to conformal invariance. We however show that several correlation functions, computed to second order in the epsilon expansion, are nontrivially consistent with conformal invariance. We proceed to give a proof of conformal invariance to all orders in the epsilon expansion, based on the description of the long-range Ising model as a defect theory in an auxiliary higher-dimensional space. A detailed review of conformal invariance in the d-dimensional short-range Ising model is also included and may be of independent interest.

Conformal invariance in the long-range Ising model

Energy Technology Data Exchange (ETDEWEB)

Paulos, Miguel F. [CERN, Theory Group, Geneva (Switzerland); Rychkov, Slava, E-mail: slava.rychkov@lpt.ens.fr [CERN, Theory Group, Geneva (Switzerland); Laboratoire de Physique Théorique de l' École Normale Supérieure (LPTENS), Paris (France); Faculté de Physique, Université Pierre et Marie Curie (UPMC), Paris (France); Rees, Balt C. van [CERN, Theory Group, Geneva (Switzerland); Zan, Bernardo [Institute of Physics, Universiteit van Amsterdam, Amsterdam (Netherlands)

2016-01-15

We consider the question of conformal invariance of the long-range Ising model at the critical point. The continuum description is given in terms of a nonlocal field theory, and the absence of a stress tensor invalidates all of the standard arguments for the enhancement of scale invariance to conformal invariance. We however show that several correlation functions, computed to second order in the epsilon expansion, are nontrivially consistent with conformal invariance. We proceed to give a proof of conformal invariance to all orders in the epsilon expansion, based on the description of the long-range Ising model as a defect theory in an auxiliary higher-dimensional space. A detailed review of conformal invariance in the d-dimensional short-range Ising model is also included and may be of independent interest.

High Dynamic Range Imaging Using Multiple Exposures

Science.gov (United States)

Hou, Xinglin; Luo, Haibo; Zhou, Peipei; Zhou, Wei

2017-06-01

It is challenging to capture a high-dynamic range (HDR) scene using a low-dynamic range (LDR) camera. This paper presents an approach for improving the dynamic range of cameras by using multiple exposure images of same scene taken under different exposure times. First, the camera response function (CRF) is recovered by solving a high-order polynomial in which only the ratios of the exposures are used. Then, the HDR radiance image is reconstructed by weighted summation of the each radiance maps. After that, a novel local tone mapping (TM) operator is proposed for the display of the HDR radiance image. By solving the high-order polynomial, the CRF can be recovered quickly and easily. Taken the local image feature and characteristic of histogram statics into consideration, the proposed TM operator could preserve the local details efficiently. Experimental result demonstrates the effectiveness of our method. By comparison, the method outperforms other methods in terms of imaging quality.

Coexistence of short- and long-range ferromagnetic order in nanocrystalline Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al (x=0.0, 0.1 and 0.3) synthesized by high-energy ball milling

Energy Technology Data Exchange (ETDEWEB)

Thanh, Tran Dang, E-mail: thanhxraylab@yahoo.com [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam); Nanto, Dwi [Physics Education, Syarif Hidayatullah States Islamic University, Jakarta 15412 (Indonesia); Tuyen, Ngo Thi Uyen [Department of Natural Science, Nha Trang Pedagogic College, Nguyen Chanh, Nha Trang, Khanh Hoa (Viet Nam); Nan, Wen-Zhe [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Yu, YiKyung [Department of Mechanical and Aerospace Engineering, University of California, San Diego, CA 92093-0411 (United States); Tartakovsky, Daniel M., E-mail: dmt@ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, CA 92093-0411 (United States); Yu, S.C., E-mail: scyu@cbnu.ac.kr [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam)

2015-11-15

In this work, we prepared nanocrystalline Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al (x=0.0, 0.1 and 0.3) powders by the high energy ball milling technique, and then studied their critical properties. Our analysis reveals that the increase of Cu-doping concentration (up to x=0.3) in these powders leads to a gradual increase of the ferromagnetic–paramagnetic transition temperature from 406 to 452 K. The Banerjee criterion suggests that all the samples considered undergo a second-order phase transition. A modified Arrott plot and scaling analysis indicate that the critical exponents (β=0.419 and 0.442, γ=1.082 and 1.116 for x=0.0 and 0.1, respectively) are located in between those expected for the 3D-Heisenberg and the mean-field models; the values of β=0.495 and γ=1.046 for x=0.3 sample are very close to those of the mean-field model. These features reveal the coexistence of the short- and long-range ferromagnetic order in the nanocrystalline Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al powders. Particularly, as the concentration of Cu increases, values of the critical exponent shift towards those of the mean-field model. Such results prove the Cu doping favors establishing a long-range ferromagnetic order. - Highlights: • Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al nanocrystals were prepared by a high energy ball milling method. • A coexistence of the short- and long-range FM order in the nanocrystals. • Cu doping favors establishing a long-range FM order in the nanocrystals. • All the ΔS{sub m}(T, H) data are followed a universal master curve.

Total Eclipse of the Ballpark: Connecting Space and Sports

Science.gov (United States)

Wasser, Molly; Petro, Noah; Jones, Andrea; Bleacher, Lora; Keller, John; Wes Patterson, G.

2018-01-01

The anticipation and excitement surrounding the total solar eclipse of 2017 provided astronomy educators with an incredible platform to share space science with huge audiences. The Public Engagement Team for NASA’s Lunar Reconnaissance Orbiter (LRO) took advantage of this opportunity to share lunar science with the public by highlighting the often-overlooked central player in the eclipse – the Moon. As the sole planetary science representatives on NASA’s Science Mission Directorate eclipse leadership team, the LRO team had limited resources to conduct national public outreach. In order to increase our reach, we found success in partnerships.In early 2017, we began working with Minor League Baseball (MiLB) teams across the path of totality on August eclipse events. These partnerships proved fruitful for both parties. While MiLB is a national organization, each team is deeply rooted in its community. This proved essential as each of our four main MiLB partners handled event logistics, provided facilities, connected NASA Subject Matter Experts (SMEs) with local media, and drew in captive crowds. With this tactic, a handful of NASA representatives were able to reach nearly 30,000 people. In turn, LRO provided engaging educational content relevant to the context, SMEs to guide the eclipse viewing experience, eclipse glasses, and safety information. Our participation drew in an audience who would not typically attend baseball games while we were able to reach individuals who would not normally attend a science event. In addition, the eclipse inspired one team, the Salem-Keizer Volcanoes from Salem, OR, to make baseball history by holding the first ever eclipse delay in professional sports.In this talk, we will present on the benefits of the partnership, offer lessons learned, and suggest ways to get involved for the 2024 eclipse – and all the baseball seasons in between.

Parametric Control on Fractional-Order Response for Lü Chaotic System

KAUST Repository

Moaddy, K; Radwan, A G; Salama, Khaled N.; Momani, S; Hashim, I

2013-01-01

This paper discusses the influence of the fractional order parameter on conventional chaotic systems. These fractional-order parameters increase the system degree of freedom allowing it to enter new domains and thus it can be used as a control for such dynamical systems. This paper investigates the behaviour of the equally-fractional-order Lü chaotic system when changing the fractional-order parameter and determines the fractional-order ranges for chaotic behaviour. Five different parameter values and six fractional-order cases are discussed through this paper. Unlike the conventional parameters, as the fractional-order increases the system response begins with stability, passing by chaotic behaviour then reaches periodic response. As the system parameter α increases, a shift in the fractional order is required to maintain chaotic response.Therefore, the range of chaotic response can be expanded or minimized by controlling the fractional-order parameter. The non-standard finite difference method is used to solve the fractional-order Lü chaotic system numerically to validate these responses.

Parametric Control on Fractional-Order Response for Lü Chaotic System

KAUST Repository

Moaddy, K

2013-04-10

This paper discusses the influence of the fractional order parameter on conventional chaotic systems. These fractional-order parameters increase the system degree of freedom allowing it to enter new domains and thus it can be used as a control for such dynamical systems. This paper investigates the behaviour of the equally-fractional-order Lü chaotic system when changing the fractional-order parameter and determines the fractional-order ranges for chaotic behaviour. Five different parameter values and six fractional-order cases are discussed through this paper. Unlike the conventional parameters, as the fractional-order increases the system response begins with stability, passing by chaotic behaviour then reaches periodic response. As the system parameter α increases, a shift in the fractional order is required to maintain chaotic response.Therefore, the range of chaotic response can be expanded or minimized by controlling the fractional-order parameter. The non-standard finite difference method is used to solve the fractional-order Lü chaotic system numerically to validate these responses.

Long-range ferromagnetic order induced by a donor impurity band exchange in SnO{sub 2}:Er{sup 3+} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Aragón, F. H.; Coaquira, J. A. H. [Núcleo de Física Aplicada, Institute of Physics, University of Brasília, Brasília DF 70910-900 (Brazil); Chitta, V. A. [Instituto de Física, Universidade de São Paulo, São Paulo, SP 05508-000 (Brazil); Hidalgo, P. [Faculdade Gama-FGA, Sector Central Gama, Universidade de Brasília, Brasília, DF72405-610 (Brazil); Brito, H. F. [Instituto de Química, Universidade de São Paulo, São Paulo, SP 05508-000 (Brazil)

2013-11-28

In this work, the structural and magnetic properties of Er-doped SnO{sub 2} (SnO{sub 2}:Er) nanoparticles are reported. The SnO{sub 2}:Er nanoparticles have been synthesized by a polymer precursor method with Er content from 1.0% to 10.0%. X-ray diffraction results indicate the formation of only the rutile-type structure in all samples. The estimated mean crystallite size shows a decrease from ∼10 to ∼4 nm when the Er content is increased from 1.0% to 10.0%. The particle size values have been corroborated by transmission electron microscopy technique. The thermal dependence of the magnetization is consistent with the 3+ oxidation state of erbium ions for all samples. A strong paramagnetic-like behavior coexisting with a ferromagnetic phase has been determined for samples with Er content below 5.0%. Above this concentration, only a paramagnetic behavior has been determined. Isothermal magnetization curves are consistent with the occurrence of long-range ferromagnetic order mediated by donor electrons forming bound magnetic polarons which overlap to produce a spin-split impurity band.

Long range order and hydrogen bonding in liquid methanol: A Monte Carlo simulation

Energy Technology Data Exchange (ETDEWEB)

Shilov, I.Y.; Rode, B.M. [Department of Theoretical Chemistry, Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck (Austria); Durov, V.A. [Department of Physical Chemistry, Faculty of Chemistry, Lomonosov Moscow State University, Moscow (Russian Federation)

1999-02-01

A Monte Carlo simulation of liquid methanol was performed in NVT ensemble at 298 K using a cubic simulation box containing 500 molecules. Long-range correlations in the liquid are discussed on the basis of site-site radial distribution functions. Hydrogen bonding and topological structure of the methanol aggregates were evaluated in detail, namely the number of linked molecules, formation of branches and cyclic structures. The necessity of larger simulation boxes for a full structural description and thermodynamic characterization of hydrogen-bonded liquids is clearly established by the results. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Measuring the relativistic perigee advance with satellite laser ranging

International Nuclear Information System (INIS)

Iorio, Lorenzo; Ciufolini, Ignazio; Pavlis, Erricos C

2002-01-01

The pericentric advance of a test body by a central mass is one of the classical tests of general relativity. Today, this effect is measured with radar ranging by the perihelion shift of Mercury and other planets in the gravitational field of the Sun, with a relative accuracy of the order of 10 -2 -10 -3 . In this paper, we explore the possibility of a measurement of the pericentric advance in the gravitational field of Earth by analysing the laser-ranged data of some orbiting, or proposed, laser-ranged geodetic satellites. Such a measurement of the perigee advance would place limits on hypothetical, very weak, Yukawa-type components of the gravitational interaction with a finite range of the order of 10 4 km. Thus, we show that, at the present level of knowledge of the orbital perturbations, the relative accuracy, achievable with suitably combined orbital elements of LAGEOS and LAGEOS II, is of the order of 10 -3 . With the corresponding measured value of (2 + 2γ - β)/3, by using η = 4β - γ - 3 from lunar laser ranging, we could get an estimate of the PPN parameters γ and β with an accuracy of the order of 10 -2 -10 -3 . Nevertheless, these accuracies would be substantially improved in the near future with the new Earth gravity field models by the CHAMP and GRACE missions. The use of the perigee of LARES (LAser RElativity Satellite), with a suitable combination of orbital residuals including also the node and the perigee of LAGEOS II, would also further improve the accuracy of the proposed measurement

Ordering effects in nonstoichiometric titanium carbide

International Nuclear Information System (INIS)

Lipatnikov, V.N.; Zueva, L.V.; Gusev, A.I.; Kottar, A.

2000-01-01

The effect of nonstoichiometry and ordering on crystalline structure and specific electric resistance (ρ) of TiC y (0.52≤y≤0.98) is studied within the temperature range of 300-1100 K. It is shown that the titanium carbide ordering in the areas 0.52≤y≤0.55, 0.56≤y≤0.58 and 0.62≤y≤0.68 leads to formation of the Ti 2 C cubic and trigonal ordered phase and the Ti 3 C 2 rhombic ordered phase correspondingly. Availability of hysteresis on the ρ(T) dependences in the area of the disorder-order reversible equilibrium transition points out to the fact that the TiC y ↔Ti 2 C and TiC y ↔Ti 3 C 2 transformations are the first order phase transitions [ru

Nuclear magnetic ordering in silver

International Nuclear Information System (INIS)

Lefmann, K.

1995-12-01

Nuclear antiferromagnetic ordering has been observed by neutron diffraction in a single crystal of 109 Ag. The critical temperature is found to 700 pK, and the critical field is 100 μT. From the paramagnetic phase a second order phase transition leads into a type-I 1-k structure with long range order. The experiments have taken place at the Hahn-Meitner Institut in Berlin in collaboration with the low Temperature Laboratory in Helsinki, the Niels Bohr Institute in Copenhagen, and Risoe National Laboratory, Roskilde. The present report is a Ph.D. thesis which has been successfully defended at the Niels Bohr Institute. Besides the results of the nuclear ordering experiments the thesis contains a description of the theoretical background for nuclear magnetism and a review of earlier nuclear ordering experiments as well as theoretical work. The principles for studying polarized nuclei with use of polarized and unpolarized neutrons are presented, as well as the results of such experiments. (au) 11 tabs., 59 ills., 143 refs

A nanoscale ordered materials diffractometer for the SNS

International Nuclear Information System (INIS)

Neuefeind, Joerg; Chipley, Kenneth K.; Tulk, Chris A.; Simonson, J. Michael; Winokur, Michael J.

2006-01-01

The Nanoscale Ordered Materials Diffractometer (NOMAD) is one of five neutron scattering instruments being managed within the Spallation Neutron Source (SNS) Instruments-Next Generation (SING) project. NOMAD is designed as a high-flux, medium-resolution diffractometer using a large bandwidth of neutron energies and extensive detector coverage to perform structural determinations of local order in crystalline and amorphous materials. The instrument will enable studies of a large variety of samples ranging from liquids, solutions, glasses, polymers, and nanocrystalline materials to long-range ordered crystals and will allow unprecedented access to high-resolution pair distribution functions, small-contrast isotope substitution experiments, small sample sizes, and parametric studies. Project completion for the instrument is anticipated in 2010 and a review of the design status will be given

Corrosion resistance of Ni-Cr-Mo alloys. Chemical composition and metallurgical condition's effects

International Nuclear Information System (INIS)

Zadorozne, N.S.; Rebak, Raul B.

2009-01-01

Ni-Cr-Mo alloys offer an outstanding corrosion resistance in a wide variety of highly-corrosive environments. This versatility is due to the excellent performance of nickel in hot alkaline solutions and the beneficial effect of chromium and molybdenum in oxidizing and reducing conditions, respectively. Alloy C-22 (22 % Cr-13 % Mo-3% W) is a well known versatile member of this family. Due to its excellent corrosion resistance in a wide variety of environments, Alloy C-22 has been selected for the fabrication of the corrosion-resistant outer shell of the high-level nuclear waste container. The increasing demand of the industry for corrosion resistant alloys with particular properties of corrosion and mechanical resistance has led to the development of new alloys. Alloy C-22HS (Ni-21 % Cr-17 % Mo) is a new high-strength corrosion resistant material recently developed and introduced into the market. This alloy provides a corrosion resistance comparable with that of other C-type alloys, and it can also be age hardened to effectively double its yield strength. HASTELLOY HYBRID-BC1 (Ni-22 % Mo-15 % Cr) is a new development intended for filling the gap between Ni-Mo and Ni-Cr-Mo alloys. This novel alloy is able to withstand HCl and H 2 SO 4 , even in the presence of dissolved oxygen and other oxidizing species. Its resistance to chloride-induced pitting corrosion, crevice corrosion and stress corrosion cracking is also remarkable. Thermal aging of Ni-Cr-Mo alloys leads to microstructure changes depending on the temperature range and exposure time at temperature. A Long Range Ordering (LRO) reaction can occur in the range of 350 C degrees to 600 C degrees, producing an ordered Ni 2 (Cr,Mo) phase. This ordering reaction does not seem to affect the corrosion resistance and produces only a slight loss in ductility. LRO transformation is homogeneous and has proven to be useful to fabricate the age-hard enable Alloy C22-HS. Tetrahedral Close Packed (TCP) phases, like μ, σ and

Long-range antigravity

Energy Technology Data Exchange (ETDEWEB)

Macrae, K.I.; Riegert, R.J. (Maryland Univ., College Park (USA). Center for Theoretical Physics)

1984-10-01

We consider a theory in which fermionic matter interacts via long-range scalar, vector and tensor fields. In order not to be in conflict with experiment, the scalar and vector couplings for a given fermion must be equal, as is natural in a dimensionally reduced model. Assuming that the Sun is not approximately neutral with respect to these new scalar-vector charges, and if the couplings saturate the experimental bounds, then their strength can be comparable to that of gravity. Scalar-vector fields of this strength can compensate for a solar quadrupole moment contribution to Mercury's anomalous perihelion precession.

Long-range antigravity

International Nuclear Information System (INIS)

Macrae, K.I.; Riegert, R.J.

1984-01-01

We consider a theory in which fermionic matter interacts via long-range scalar, vector and tensor fields. In order not to be in conflict with experiment, the scalar and vector couplings for a given fermion must be equal, as is natural in a dimensionally reduced model. Assuming that the Sun is not approximately neutral with respect to these new scalar-vector charges, and if the couplings saturate the experimental bounds, then their strength can be comparable to that of gravity. Scalar-vector fields of this strength can compensate for a solar quadrupole moment contribution to Mercury's anomalous perihelion precession. (orig.)

Long range correlations in condensed matter

International Nuclear Information System (INIS)

Bochicchio, R.C.

1990-01-01

Off diagonal long range order (ODLRO) correlations are strongly related with the generalized Bose-Einstein condensation. Under certain boundary conditions, one implies the other. These phenomena are of great importance in the description of quantum situations with a macroscopic manifestation (superfluidity, superconductivity, etc.). Since ion pairs are not bosons, the definition of ODLRO is modified. The information contained with the 2-particle propagator (electron pairs) and the consequences that lead to pairs statistics are shown in this presentation. The analogy between long range correlations and fluids is also analyzed. (Author). 17 refs

Eye safe laser range finders

International Nuclear Information System (INIS)

Snir, M.; Margaliot, M.; Amitzi, A.

2004-01-01

During the 1970's, Ruby (Q switched) laser based range finders with a wavelength of 694nm were first used. These lasers operated in a pulse mode within the visible light range and produced a risk for the eye retina. The laser beam striking the macula could damage the eye and might cause blindness. Over the years, Nd:YAG (Q switched) lasers were developed (operating at 1064nm) for range finding and designation uses. The wavelength of these lasers, operating in the near Infra-Red range (invisible), is also focused tightly on the retina. The human eye does not respond to the invisible light so there is no natural protection (eye blink reflex) as in the visible light. The operation of these lasers worldwide, especially when the laser beam is exposed, causes occasional eye accidents. Another risk is stemming from the use of observation systems with a high optical gain, in the laser operation areas, which enlarge the range of risk quite significantly. Therefore, research and development efforts were invested in order to introduce eye safe lasers. One of the solutions for this problem is presented in following document

Power peak in vicinity of WWER-440 control assembly

International Nuclear Information System (INIS)

Mikus, J.

2002-01-01

This paper presents information concerning the WWER-440 local power peaking problem induced by a control assembly and corresponding investigation possibilities on the light-water zero-power reactor LR-O at the Nuclear Research Institute Rez plc. Brief description of the disposable CA model, experimental arrangement and conditions on the LR-O reactor, preparation of the relevant measurements in the WWER-440 type cores with CA model, as well as some preliminary results of the fission density distribution obtained in a core without boron and with fuel assemblies having profiled enrichment are mentioned too (Author)

Structure of ordered and disordered α-brass

International Nuclear Information System (INIS)

Mu''ller, S.; Zunger, Alex

2001-01-01

Alloys of copper and zinc (brass) have been widely used since Neolithic times due to the discovery that unlike regular copper this alloy can be worked ''cold'' around a 3:1 copper-to-zinc ratio. While it is now known that the as-grown system is a disordered fcc solid solution, no 3:1 ordered phase has yet been directly observed even though the negative mixing enthalpy of the disordered alloy suggests ordering tendencies. Moreover, neutron scattering experiments have been deduced that this disordered alloy contains peculiar chains of Zn atoms. We have expressed the first-principles calculated total energy of general Cu-Zn fcc-lattice configurations using a mixed-space cluster expansion. Application of Monte Carlo--simulated annealing to this generalized Ising-like Hamiltonian produces the predicted low-temperature ground state as well as finite-temperature phase diagram and short-range order. We find (i) that at low temperature the disordered fcc alloy will order into the DO 23 structure, (ii) the high-temperature short-range order in close agreement with experiment, and (iii) chains of Zn atoms in the [001] direction, as seen experimentally. Furthermore, our model allows a detailed study of the influence and importance of strain on the phase stability

A general range-separated double-hybrid density-functional theory.

Science.gov (United States)

Kalai, Cairedine; Toulouse, Julien

2018-04-28

A range-separated double-hybrid (RSDH) scheme which generalizes the usual range-separated hybrids and double hybrids is developed. This scheme consistently uses a two-parameter Coulomb-attenuating-method (CAM)-like decomposition of the electron-electron interaction for both exchange and correlation in order to combine Hartree-Fock exchange and second-order Møller-Plesset (MP2) correlation with a density functional. The RSDH scheme relies on an exact theory which is presented in some detail. Several semi-local approximations are developed for the short-range exchange-correlation density functional involved in this scheme. After finding optimal values for the two parameters of the CAM-like decomposition, the RSDH scheme is shown to have a relatively small basis dependence and to provide atomization energies, reaction barrier heights, and weak intermolecular interactions globally more accurate or comparable to range-separated MP2 or standard MP2. The RSDH scheme represents a new family of double hybrids with minimal empiricism which could be useful for general chemical applications.

Graphene: A partially ordered non-periodic solid

International Nuclear Information System (INIS)

Wei, Dongshan; Wang, Feng

2014-01-01

Molecular dynamics simulations were performed to study the structural features of graphene over a wide range of temperatures from 50 to 4000 K using the PPBE-G potential [D. Wei, Y. Song, and F. Wang, J. Chem. Phys. 134, 184704 (2011)]. This potential was developed by force matching the Perdew-Burke-Ernzerhof (PBE) exchange correlation functional and has been validated previously to provide accurate potential energy surface for graphene at temperatures as high as 3000 K. Simulations with the PPBE‑G potential are the best available approximation to a direct Car-Parrinello Molecular Dynamics study of graphene. One advantage of the PBE-G potential is to allow large simulation boxes to be modeled efficiently so that properties showing strong finite size effects can be studied. Our simulation box contains more than 600 000 C atoms and is one of the largest graphene boxes ever modeled. With the PPBE-G potential, the thermal-expansion coefficient is negative up to 4000 K. With a large box and an accurate potential, the critical exponent for the scaling properties associated with the normal-normal and height-height correlation functions was confirmed to be 0.85. This exponent remains constant up to 4000 K suggesting graphene to be in the deeply cooled regime even close to the experimental melting temperature. The reduced peak heights in the radial distribution function of graphene show an inverse power law dependence to distance, which indicates that a macroscopic graphene sheet will lose long-range crystalline order as predicted by the Mermin-Wagner instability. Although graphene loses long-range translational order, it retains long range orientational order as indicated by its orientational correlation function; graphene is thus partially ordered but not periodic

Range distribution of heavy ions in multi-elemental targets

International Nuclear Information System (INIS)

Wang Keming; Shandong Univ., Jinan; Liu Xiju; Wang Yihua; Liu Jitian; Shi Borong; Chen Huanchu

1989-01-01

Some results of range distribution on Hg + implanted NaSBN and CeSBN crystals are given. A computer program is written based on the angular diffusion model by Biersack to calculate the mean projected range and range straggling. For comparison, other published experimental data are also included. The comparison between experimental and theoretical values indicates that the measured projected ranges are in good agreement with those predicted by the Biersack model within experimental error, and a marked improvement in range stragglings is obtained after considering the second order energy loss. (author)

Chaos in a fractional-order Roessler system

International Nuclear Information System (INIS)

Zhang Weiwei; Zhou Shangbo; Li Hua; Zhu Hao

2009-01-01

The dynamic behaviors in the fractional-order Roessler equations were numerically studied. Basic properties of the system have been analyzed by means of Lyapunov exponents and bifurcation diagrams. The parameter and the derivative order ranges used were relatively broad. Regular motions (including period-3 motion) and chaotic motions were examined. The chaotic motion identified was validated by the positive Lyapunov exponent.

Coordination of storage lipid synthesis and membrane biogenesis: evidence for cross-talk between triacylglycerol metabolism and phosphatidylinositol synthesis.

Science.gov (United States)

Gaspar, Maria L; Hofbauer, Harald F; Kohlwein, Sepp D; Henry, Susan A

2011-01-21

Despite the importance of triacylglycerols (TAG) and steryl esters (SE) in phospholipid synthesis in cells transitioning from stationary-phase into active growth, there is no direct evidence for their requirement in synthesis of phosphatidylinositol (PI) or other membrane phospholipids in logarithmically growing yeast cells. We report that the dga1Δlro1Δare1Δare2Δ strain, which lacks the ability to synthesize both TAG and SE, is not able to sustain normal growth in the absence of inositol (Ino(-) phenotype) at 37 °C especially when choline is present. Unlike many other strains exhibiting an Ino(-) phenotype, the dga1Δlro1Δare1Δare2Δ strain does not display a defect in INO1 expression. However, the mutant exhibits slow recovery of PI content compared with wild type cells upon reintroduction of inositol into logarithmically growing cultures. The tgl3Δtgl4Δtgl5Δ strain, which is able to synthesize TAG but unable to mobilize it, also exhibits attenuated PI formation under these conditions. However, unlike dga1Δlro1Δare1Δare2Δ, the tgl3Δtgl4Δtgl5Δ strain does not display an Ino(-) phenotype, indicating that failure to mobilize TAG is not fully responsible for the growth defect of the dga1Δlro1Δare1Δare2Δ strain in the absence of inositol. Moreover, synthesis of phospholipids, especially PI, is dramatically reduced in the dga1Δlro1Δare1Δare2Δ strain even when it is grown continuously in the presence of inositol. The mutant also utilizes a greater proportion of newly synthesized PI than wild type for the synthesis of inositol-containing sphingolipids, especially in the absence of inositol. Thus, we conclude that storage lipid synthesis actively influences membrane phospholipid metabolism in logarithmically growing cells.

Intermediate-range order in mesoporous silicas investigated by a high-energy X-ray diffraction technique

International Nuclear Information System (INIS)

Wakihara, Toru; Fan, Wei; Ogura, Masaru; Okubo, Tatsuya; Kohara, Shinji; Sankar, Gopinathan

2008-01-01

We perform a high-energy X-ray diffraction study comparing bulk amorphous silica with MCM-41 and SBA-15 that are representative mesoporous silicas prepared in basic and acidic conditions, respectively. It is revealed that mesoporous silicas, especially SBA-15, have less ordered structures and contain larger fractions of three- and four-membered rings than does bulk amorphous silica. (author)

Nuclear magnetic ordering in silver

Energy Technology Data Exchange (ETDEWEB)

Lefmann, K

1995-12-01

Nuclear antiferromagnetic ordering has been observed by neutron diffraction in a single crystal of {sup 109}Ag. The critical temperature is found to 700 pK, and the critical field is 100 {mu}T. From the paramagnetic phase a second order phase transition leads into a type-I 1-k structure with long range order. The experiments have taken place at the Hahn-Meitner Institut in Berlin in collaboration with the low Temperature Laboratory in Helsinki, the Niels Bohr Institute in Copenhagen, and Risoe National Laboratory, Roskilde. The present report is a Ph.D. thesis which has been successfully defended at the Niels Bohr Institute. Besides the results of the nuclear ordering experiments the thesis contains a description of the theoretical background for nuclear magnetism and a review of earlier nuclear ordering experiments as well as theoretical work. The principles for studying polarized nuclei with use of polarized and unpolarized neutrons are presented, as well as the results of such experiments. (au) 11 tabs., 59 ills., 143 refs.

Applications of the KKR-DCA: A Finite-Temperature Density Functional Theory to Predict Chemical Short-Range Order Effects in Disordered Metallic Alloys

Science.gov (United States)

Biava, D. A.; Johnson, D. D.

2009-03-01

Short-range order (SRO) is ubiquitous in metallic alloys, affecting changes in their electronic, thermodynamic, mechanical, magnetic, and structural properties. For example, SRO is responsible for the yield-strength anomalies observed in Cu-Al at high temperatures, i.e., the materials is more resistant to dislocation motion at high temperature than it is at room temperature. Within the Korringa-Kohn-Rostorker (KKR) electronic-structure method, we present results using the dynamical cluster approximations (DCA) to obtain the temperature-dependent SRO in disordered alloys. We obtain the KKR-DCA SRO energetics versus local neighbor SRO parameters and minimize it at fixed temperature to predict the SRO. We show that the calculated SRO at fixed temperature compares well with available experimental results, and then correlate the results to the electronic structure. We discuss how an accurate analytic estimate can be made for the SRO in most metals due to the dependence of the grand potential on SRO.

Short-range order parameters in amorphous YBaS4X7(X-S, SE, TE) films

International Nuclear Information System (INIS)

Hajiyev, E.S.

2005-01-01

Full text : Electron scattering intensity curves from amorphous YbAs 4 X 7 (X-S, SE, TE) films have ben obtained by the transmission electron diffraction (TED) method with rotation sector before screen up. The energy of electrons was 100 keV. Amorphous samples were crystallized and the composition of the products were measured by TED. The atomic radial distribution function has been calculated by the Fourier synthesis of intensities in the TED of amorphous YbAs 4 X 7 (X-S, SE, TE) films. The interatomic average distances of As - S (Se, Te) and As-Yb + 2 and partial coordination numbers have been estimated in these thilms. Based on these numbers, chemical orders in these films differ. This difference is due to differing topological order in the amorphous YbAs 4 X 7 (X-S, SE, TE) films

Narrow resonances and short-range interactions

International Nuclear Information System (INIS)

Gelman, Boris A.

2009-01-01

Narrow resonances in systems with short-range interactions are discussed in an effective field theory (EFT) framework. An effective Lagrangian is formulated in the form of a combined expansion in powers of a momentum Q 0 | 0 --a resonance peak energy. At leading order in the combined expansion, a two-body scattering amplitude is the sum of a smooth background term of order Q 0 and a Breit-Wigner term of order Q 2 (δε) -1 which becomes dominant for δε 3 . Such an EFT is applicable to systems in which short-distance dynamics generates a low-lying quasistationary state. The EFT is generalized to describe a narrow low-lying resonance in a system of charged particles. It is shown that in the case of Coulomb repulsion, a two-body scattering amplitude at leading order in a combined expansion is the sum of a Coulomb-modified background term and a Breit-Wigner amplitude with parameters renormalized by Coulomb interactions.

The influence of chromium additions on order and ductility in Fe3Al intermetallic

International Nuclear Information System (INIS)

Morris, D.G.; Dadras, M.; Morris, M.A.

1993-01-01

It has previously been shown that the addition of Cr to the Fe 3 Al alloy can lead to improvements in ductility. Initial interpretations of this effect were based on changes in the fault energies and dislocation configurations, but recently the influence of environmental attack has been invoked. In the present study the role of Cr and other elemental additions on the state of order, dislocation dissociations and configurations, and on ductility has been examined under conditions where environmental attack should not be important. The addition of Cr is shown to have only a minor affect on ordering kinetics, fault energies and dislocation configurations. However, for the alloys generally considered, containing 28% Al, it is shown that the ordered state and microstructure depends sensitively on the precise composition and heat treatments given. In particular, small amounts of solute elements such as B can lead to the appearance of two-phase ordered-disordered microstructures over a wide temperature range, to the appearance of imperfect long range and short range order, and to major changes in the kinetics of ordering and disordering. The mechanical properties achieved are shown to depend critically on the extent and distribution of disorder (the long range order parameter, the extent of short range order, the presence and distribution of thick disordered domain walls) and this factor may explain much of the variability in properties reported between similar alloys. By way of example, the presence of short range order will confine dislocations to well-defined shear planes, concentrating shear and inducing early failure; disordered domain walls will dissociate superdislocations thereby spreading shear homogeneously; the ordered domains/disordered walls morphology will lead to particle-dispersion hardening. (orig.)

Long-range interaction of anisotropic systems

KAUST Repository

Zhang, Junyi

2015-02-01

The first-order electrostatic interaction energy between two far-apart anisotropic atoms depends not only on the distance between them but also on their relative orientation, according to Rayleigh-Schrödinger perturbation theory. Using the first-order interaction energy and the continuum model, we study the long-range interaction between a pair of parallel pristine graphene sheets at zero temperature. The asymptotic form of the obtained potential density, &epsi:(D) &prop: ?D ?3 ?O(D?4), is consistent with the random phase approximation and Lifshitz theory. Accordingly, neglectance of the anisotropy, especially the nonzero first-order interaction energy, is the reason why the widely used Lennard-Jones potential approach and dispersion corrections in density functional theory give a wrong asymptotic form ε(D) &prop: ?D?4. © EPLA, 2015.

Long-range interaction of anisotropic systems

KAUST Repository

Zhang, Junyi; Schwingenschlö gl, Udo

2015-01-01

The first-order electrostatic interaction energy between two far-apart anisotropic atoms depends not only on the distance between them but also on their relative orientation, according to Rayleigh-Schrödinger perturbation theory. Using the first-order interaction energy and the continuum model, we study the long-range interaction between a pair of parallel pristine graphene sheets at zero temperature. The asymptotic form of the obtained potential density, &epsi:(D) &prop: ?D ?3 ?O(D?4), is consistent with the random phase approximation and Lifshitz theory. Accordingly, neglectance of the anisotropy, especially the nonzero first-order interaction energy, is the reason why the widely used Lennard-Jones potential approach and dispersion corrections in density functional theory give a wrong asymptotic form ε(D) &prop: ?D?4. © EPLA, 2015.

Distance Ranging Based on Quantum Entanglement

International Nuclear Information System (INIS)

Xiao Jun-Jun; Han Xiao-Chun; Zeng Gui-Hua; Fang Chen; Zhao Jian-Kang

2013-01-01

In the quantum metrology, applications of quantum techniques based on entanglement bring in some better performances than conventional approaches. We experimentally investigate an application of entanglement in accurate ranging based on the second-order coherence in the time domain. By a fitting algorithm in the data processing, the optimization results show a precision of ±200 μm at a distance of 1043.3m. In addition, the influence of jamming noise on the ranging scheme is studied. With some different fitting parameters, the result shows that the proposed scheme has a powerful anti-jamming capability for white noise

XY model with higher-order exchange.

Science.gov (United States)

Žukovič, Milan; Kalagov, Georgii

2017-08-01

An XY model, generalized by inclusion of up to an infinite number of higher-order pairwise interactions with an exponentially decreasing strength, is studied by spin-wave theory and Monte Carlo simulations. At low temperatures the model displays a quasi-long-range-order phase characterized by an algebraically decaying correlation function with the exponent η=T/[2πJ(p,α)], nonlinearly dependent on the parameters p and α that control the number of the higher-order terms and the decay rate of their intensity, respectively. At higher temperatures the system shows a crossover from the continuous Berezinskii-Kosterlitz-Thouless to the first-order transition for the parameter values corresponding to a highly nonlinear shape of the potential well. The role of topological excitations (vortices) in changing the nature of the transition is discussed.

First-principles theory of short-range order in size-mismatched metal alloys: Cu-Au, Cu-Ag, and Ni-Au

International Nuclear Information System (INIS)

Wolverton, C.; Ozolins, V.; Zunger, A.

1998-01-01

We describe a first-principles technique for calculating the short-range order (SRO) in disordered alloys, even in the presence of large anharmonic atomic relaxations. The technique is applied to several alloys possessing large size mismatch: Cu-Au, Cu-Ag, Ni-Au, and Cu-Pd. We find the following: (i) The calculated SRO in Cu-Au alloys peaks at (or near) the left-angle 100 right-angle point for all compositions studied, in agreement with diffuse scattering measurements. (ii) A fourfold splitting of the X-point SRO exists in both Cu 0.75 Au 0.25 and Cu 0.70 Pd 0.30 , although qualitative differences in the calculated energetics for these two alloys demonstrate that the splitting in Cu 0.70 Pd 0.30 may be accounted for by T=0 K energetics while T≠0 K configurational entropy is necessary to account for the splitting in Cu 0.75 Au 0.25 . Cu 0.75 Au 0.25 shows a significant temperature dependence of the splitting, in agreement with recent in situ measurements, while the splitting in Cu 0.70 Pd 0.30 is predicted to have a much smaller temperature dependence. (iii) Although no measurements exist, the SRO of Cu-Ag alloys is predicted to be of clustering type with peaks at the left-angle 000 right-angle point. Streaking of the SRO peaks in the left-angle 100 right-angle and left-angle 1 (1) /(2) 0 right-angle directions for Ag- and Cu-rich compositions, respectively, is correlated with the elastically soft directions for these compositions. (iv) Even though Ni-Au phase separates at low temperatures, the calculated SRO pattern in Ni 0.4 Au 0.6 , like the measured data, shows a peak along the left-angle ζ00 right-angle direction, away from the typical clustering-type left-angle 000 right-angle point. (v) The explicit effect of atomic relaxation on SRO is investigated and it is found that atomic relaxation can produce significant qualitative changes in the SRO pattern, changing the pattern from ordering to clustering type, as in the case of Cu-Ag. copyright 1998 The American

Order and disorder in the local and long-range structure of the spin-glass pyrochlore, Tb{sub 2}Mo{sub 2}O{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Jiang, Yu; Huq, Ashfia; Booth, Corwin H.; Ehlers, Georg; Greedan, John E.; Gardner, Jason S.

2011-02-11

To understand the origin of the spin-glass state in molybdate pyrochlores, the structure of Tb{sub 2}Mo{sub 2}O{sub 7} is investigated using two techniques: the long-range lattice structure was measured using neutron powder diffraction (NPD), and local structure information was obtained from the extended x-ray absorption fine structure (EXAFS) technique. While the long-range structure appears generally well ordered, enhanced mean-squared site displacements on the O(1) site and the lack of temperature dependence of the strongly anisotropic displacement parameters for both the Mo and O(1) sites indicate some disorder exists. Likewise, the local structure measurements indicate some Mo-Mo and Tb-O(1) nearest-neighbor disorder exists, similar to that found in the related spin-glass pyrochlore, Y{sub 2}Mo{sub 2}O{sub 7}. Although the freezing temperature in Tb{sub 2}Mo{sub 2}O{sub 7}, 25 K, is slightly higher than in Y{sub 2}Mo{sub 2}O{sub 7}, 22 K, the degree of local pair distance disorder is actually less in Tb{sub 2}Mo{sub 2}O{sub 7}. This apparent contradiction is considered in light of the interactions involved in the freezing process.

Ordering Dynamics in Neuron Activity Pattern Model: An Insight to Brain Functionality.

Directory of Open Access Journals (Sweden)

Jasleen Gundh

Full Text Available We study the domain ordering kinetics in d = 2 ferromagnets which corresponds to populated neuron activities with both long-ranged interactions, V(r ∼ r-n and short-ranged interactions. We present the results from comprehensive Monte Carlo (MC simulations for the nonconserved Ising model with n ≥ 2, interaction range considering near and far neighbors. Our model results could represent the long-ranged neuron kinetics (n ≤ 4 in consistent with the same dynamical behaviour of short-ranged case (n ≥ 4 at far below and near criticality. We found that emergence of fast and slow kinetics of long and short ranged case could imitate the formation of connections among near and distant neurons. The calculated characteristic length scale in long-ranged interaction is found to be n independent (L(t ∼ t1/(n-2, whereas short-ranged interaction follows L(t ∼ t1/2 law and approximately preserve universality in domain kinetics. Further, we did the comparative study of phase ordering near the critical temperature which follows different behaviours of domain ordering near and far critical temperature but follows universal scaling law.

The Large Scale Distribution of Water Ice in the Polar Regions of the Moon

Science.gov (United States)

Jordan, A.; Wilson, J. K.; Schwadron, N.; Spence, H. E.

2017-12-01

For in situ resource utilization, one must know where water ice is on the Moon. Many datasets have revealed both surface deposits of water ice and subsurface deposits of hydrogen near the lunar poles, but it has proved difficult to resolve the differences among the locations of these deposits. Despite these datasets disagreeing on how deposits are distributed on small scales, we show that most of these datasets do agree on the large scale distribution of water ice. We present data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO), LRO's Lunar Exploration Neutron Detector (LEND), the Neutron Spectrometer on Lunar Prospector (LPNS), LRO's Lyman Alpha Mapping Project (LAMP), LRO's Lunar Orbiter Laser Altimeter (LOLA), and Chandrayaan-1's Moon Mineralogy Mapper (M3). All, including those that show clear evidence for water ice, reveal surprisingly similar trends with latitude, suggesting that both surface and subsurface datasets are measuring ice. All show that water ice increases towards the poles, and most demonstrate that its signature appears at about ±70° latitude and increases poleward. This is consistent with simulations of how surface and subsurface cold traps are distributed with latitude. This large scale agreement constrains the origin of the ice, suggesting that an ancient cometary impact (or impacts) created a large scale deposit that has been rendered locally heterogeneous by subsequent impacts. Furthermore, it also shows that water ice may be available down to ±70°—latitudes that are more accessible than the poles for landing.

Look Ahead: Long-Range Learning Plans

Science.gov (United States)

Weinstein, Margery

2010-01-01

Faced with an unsteady economy and fluctuating learning needs, planning a learning strategy designed to last longer than the next six months can be a tall order. But a long-range learning plan can provide a road map for success. In this article, four companies (KPMG LLP, CarMax, DPR Construction, and EMC Corp.) describe their learning plans, and…

Long-range displacive to short-range order-disorder crossover in weakly concentrated KTa.sub.y./sub.Nb.sub.1-y./sub.O.sub.3./sub..

Czech Academy of Sciences Publication Activity Database

Trepakov, V. A.; Prosandeev, V. A.; Savinov, Maxim; Galinetto, P.; Samoggia, G.; Kapphan, S.; Jastrabík, Lubomír; Boatner, L. A.

2002-01-01

Roč. 41, 11B (2002), s. 7176-7178 ISSN 0021-4922 R&D Projects: GA MŠk LN00A015 Institutional research plan: CEZ:AV0Z1010914 Keywords : incipient ferroelectrics * impurity effects * multiscale ordering Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.280, year: 2002

Lunar Reconnaissance Orbiter Lunar Workshops for Educators

Science.gov (United States)

Jones, A. P.; Hsu, B. C.; Hessen, K.; Bleacher, L.

2012-12-01

The Lunar Workshops for Educators (LWEs) are a series of weeklong professional development workshops, accompanied by quarterly follow-up sessions, designed to educate and inspire grade 6-12 science teachers, sponsored by the Lunar Reconnaissance Orbiter (LRO). Participants learn about lunar science and exploration, gain tools to help address common student misconceptions about the Moon, find out about the latest research results from LRO scientists, work with data from LRO and other lunar missions, and learn how to bring these data to their students using hands-on activities aligned with grade 6-12 National Science Education Standards and Benchmarks and through authentic research experiences. LWEs are held around the country, primarily in locations underserved with respect to NASA workshops. Where possible, workshops also include tours of science facilities or field trips intended to help participants better understand mission operations or geologic processes relevant to the Moon. Scientist and engineer involvement is a central tenant of the LWEs. LRO scientists and engineers, as well as scientists working on other lunar missions, present their research or activities to the workshop participants and answer questions about lunar science and exploration. This interaction with the scientists and engineers is consistently ranked by the LWE participants as one of the most interesting and inspiring components of the workshops. Evaluation results from the 2010 and 2011 workshops, as well as preliminary analysis of survey responses from 2012 participants, demonstrated an improved understanding of lunar science concepts among LWE participants in post-workshop assessments (as compared to identical pre-assessments) and a greater understanding of how to access and effectively share LRO data with students. Teachers reported increased confidence in helping students conduct research using lunar data, and learned about programs that would allow their students to make authentic

Elastic properties and short-range structural order in mixed network former glasses.

Science.gov (United States)

Wang, Weimin; Christensen, Randilynn; Curtis, Brittany; Hynek, David; Keizer, Sydney; Wang, James; Feller, Steve; Martin, Steve W; Kieffer, John

2017-06-21

Elastic properties of alkali containing glasses are of great interest not only because they provide information about overall structural integrity but also they are related to other properties such as thermal conductivity and ion mobility. In this study, we investigate two mixed-network former glass systems, sodium borosilicate 0.2Na 2 O + 0.8[xBO 1.5 + (1 - x)SiO 2 ] and sodium borogermanate 0.2Na 2 O + 0.8[xBO 1.5 + (1 - x)GeO 2 ] glasses. By mixing network formers, the network topology can be changed while keeping the network modifier concentration constant, which allows for the effect of network structure on elastic properties to be analyzed over a wide parametric range. In addition to non-linear, non-additive mixed-glass former effects, maxima are observed in longitudinal, shear and Young's moduli with increasing atomic number density. By combining results from NMR spectroscopy and Brillouin light scattering with a newly developed statistical thermodynamic reaction equilibrium model, it is possible to determine the relative proportions of all network structural units. This new analysis reveals that the structural characteristic predominantly responsible for effective mechanical load transmission in these glasses is a high density of network cations coordinated by four or more bridging oxygens, as it provides for establishing a network of covalent bonds among these cations with connectivity in three dimensions.

Interaction range perturbation theory for three-particle problem

International Nuclear Information System (INIS)

Simenog, I.V.; Shapoval, D.V.

1988-01-01

The limit of zero interaction range is correctly defined for a system of three spinless particles and three particles in a doublet state. The scattering amplitude is expanded with respect to the interaction range r, and the corrections of order r ln r, r, and r 2 ln2 r are found. An explicit model-independent asymptotic expression is obtained for the scattering amplitude in terms of the scattering length, and its accuracy is established

Neutron diffraction studies on ordered and disordered materials

International Nuclear Information System (INIS)

Krishna, P.S.R

2016-01-01

Knowledge of the symmetry and distribution of atoms in the unit cell and the bonding between atoms is the key point for understanding, designing and manipulating chemical behavior or physical properties of novel materials for technological applications. This could be achieved using diffraction techniques. At the Dhruva national facility, BARC, Mumbai, a Powder diffractometer (PD2) and a High-Q diffractometer (HQD) are in operation for more than 2 decades. PD2 and HQD are equipped with banks of 5 and 10 position sensitive detectors (PSD) respectively, to cover the Q-ranges 9.4 Å -1 and 15 Å -1 respectively. The resolutions (Δd/d) of these instruments are 0.8% (λ = 1.24 Å) and 2.5% (λ = 0.78 Å). We report about the studies of changes in the long range order in crystalline materials as a function of temperature and/or composition as well as short and intermediate range orders studied in amorphous materials on these diffractometers in recent years. PD2 has been extensively used in the structural/phase transition studies of ferroics, multiferroics, nanoferrites along with magnetic structure determinations. On the other hand, HQD has been extensively used to understand the short and intermediate range order in network glasses like chalcogenides, H-bonded alcohols, Telluride glasses etc. We will be discussing the recent structural results obtained on many of these crystalline systems, glasses and molecular fluids on both of these diffractometers. (author)

Short-range order of germanium selenide glass

Indian Academy of Sciences (India)

Carlo (RMC) simulations are useful to compute the partial pair distribution ... recent times,13 the sorption ability of Ge20Se80 thin films, ... and the structural configuration is adjusted so as to mini- ... it is accepted with probability exp(−(χ2 n − χ2.

Physical Metallurgy, Weldability, and in-Service Performance of Nickel-Chromium Filler Metals Used in Nuclear Power Systems

Science.gov (United States)

Young, George A.; Etien, Robert A.; Hackett, Micah J.; Tucker, Julie D.; Capobianco, Thomas E.

Wrought Alloy 690 is well established for corrosion resistant nuclear applications but development continues to improve the weldability of a filler metal that retains the corrosion resistance and phase stability of the base metal. High alloy Ni-Cr filler metals are prone to several types of welding defects and new alloys are emerging for commercial use. This paper uses experimental and computational methods to illustrate key differences among welding consumables. Results show that solidification segregation is critical to understanding the weldability and environmentally-assisted cracking resistance of these alloys. Primary water stress corrosion cracking tests show a marked decrease in crack growth rates near 21 wt. % Cr at the grain boundary. While filler metals with 21-29 wt.% grain boundary Cr show similar PWSCC resistance, the higher alloyed grades are more prone to solidification cracking. Modeling and aging studies indicate that in some filler metals minor phase formation (e.g., Laves and σ) and long range order (LRO) must be assessed to ensure adequate weldability and inservice performance.

Constant Load SCC Initiation Response of Alloy 22 (UNS N06022), Titanium Grade 7 and Stainless Steels at 1050C

International Nuclear Information System (INIS)

Young, L.M.; Catlin, G.M.; Andresen, P.L.; Gordon, G.M.

2002-01-01

This paper provides an update on research addressing the effects of material condition and applied stress on stress corrosion cracking (SCC) in waste package and drip shield materials for the Yucca Mountain Project. Time-to-failure experiments are being performed on smooth bar tensile specimens in a hot, concentrated, mixed-salt solution chosen to simulate concentrated Yucca Mountain water. The effects of applied stress, welding, surface finish, shot peening, cold work, crevicing, and aging treatment are being investigated for Alloy 22 (UNS N06022). Aging treatments were designed to produce topologically close-packed phases (TCP) and long-range ordering (LRO) and are under investigation as worse-case scenarios for possible microstructures in Alloy 22 (UNS N06022). Titanium Grade 7 and 3 16NG stainless steel are included in the matrix, as they are identified for drip shield and waste package components, respectively. Sensitized 304SS specimens are included in the test matrix to provide benchmark data. This research complements high-resolution crack-growth-rate experiments currently being performed in a parallel research project

Order-disorder in olivine minerals by synchrotron X-ray absorption near-edge structure (Xane) spectroscopy at the Mg, Fe and Ca K edges

Energy Technology Data Exchange (ETDEWEB)

Wu, Z.; Marcelli, A.; Cibin, G. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Mottana, A. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Rome Univ. Roma Tre, Rome (Italy). Dipt. di Scienze Geologiche; Paris, E.; Giuli, G [INFM, Camerino Univ., Camerino, MC (Italy). Dipt. di Scienze della Terra

1999-07-01

In this paper, are presented new, high-resolution experimental spectra at the Mg and Fe K edges for the two Fe-Mg end members F o and F a, and for three other olivines. Two are the Ca end members of the family, namely monticellite (Mtc: CaMgSiO4) and kirschsteinite (Krs: CaFeSiO4). The main purpose of this work is to investigate the effects of Mg, Fe, and Ca partition in the Pbnm (or {alpha}) olivine structure on the electronic properties, as well as the relationships that exist between chemical substitutions and features occurring in Xanes spectra. One wants to explore the relationships that intervene between LRO, as determined by XRD, and SRO, as determined by Xanes, on the endmembers and on a well-known intermediate member as well, and deduce from it a model for the behavior of the entire olivine solid-solution system.

Order-disorder in olivine minerals by synchrotron X-ray absorption near-edge structure (Xane) spectroscopy at the Mg, Fe and Ca K edges

International Nuclear Information System (INIS)

Wu, Z.; Marcelli, A.; Cibin, G.; Mottana, A.; Rome Univ. Roma Tre, Rome; Paris, E.; Giuli, G.

1999-01-01

In this paper, are presented new, high-resolution experimental spectra at the Mg and Fe K edges for the two Fe-Mg endmembers F o and F a, and for three other olivines. Two are the Ca endmembers of the family, namely monticellite (Mtc: CaMgSiO4) and kirschsteinite (Krs: CaFeSiO4). The main purpose of this work is to investigate the effects of Mg, Fe, and Ca partition in the Pbnm (or α) olivine structure on the electronic properties, as well as the relationships that exist between chemical substitutions and features occurring in Xanes spectra. One wants to explore the relationships that intervene between LRO, as determined by XRD, and SRO, as determined by Xanes, on the endmembers and on a well-known intermediate member as well, and deduce from it a model for the behavior of the entire olivine solid-solution system

Simultaneous diagonal and off-diagonal order in the Bose-Hubbard Hamiltonian

International Nuclear Information System (INIS)

Scalettar, R.T.; Batrouni, G.G.; Kampf, A.P.; Zimanyi, G.T.

1995-01-01

The Bose-Hubbard model exhibits a rich phase diagram consisting both of insulating regimes where diagonal long-range (solid) order dominates as well as conducting regimes where off-diagonal long-range order (superfluidity) is present. In this paper we describe the results of quantum Monte Carlo calculations of the phase diagram, both for the hard- and soft-core cases, with a particular focus on the possibility of simultaneous superfluid and solid order. We also discuss the appearance of phase separation in the model. The simulations are compared with analytic calculations of the phase diagram and spin-wave dispersion

Sodium ordering and the control of magnetism in sodium cobaltate

International Nuclear Information System (INIS)

Morris, D.J.P.; Roger, M.; Tennant, D.A.; Goff, J.P.; Gutmann, M.J.; Hoffmann, J.-U.; Prabhakaran, D.; Shannon, N.; Lake, B.; Deen, P.P.

2007-01-01

The long-range three-dimensional ordering of Na + ions was studied in a sample of composition Na 0.75 CoO 2 using single-crystal neutron diffraction. Large-scale numerical simulations reveal the ordering principle for this system, the formation of multi-vacancy charged droplets then order long range, and the structure factors from these defect clusters are in good agreement with the observed neutron diffraction intensities. The electrostatic potential is found to be the dominant factor in determining the sodium ordering and its associated distortion field. The superstructures induce a periodic potential in the CoO 2 , giving potential wells that are larger than the single-particle hopping frequency and so able to localize holes. The results readily explain many of the observed electrical and magnetic properties, including the three dimensionality of the magnetic excitations

Local atomic order of a metallic glass made visible by scanning tunneling microscopy

Science.gov (United States)

Luo, Yuansu; Samwer, Konrad

2018-06-01

Exploring the atomic level structure in amorphous materials by STM becomes extremely difficult due to the localized electronic states. Here we carried out STM studies on a quasi-low-dimensional film of metallic glass Zr65Cu27.5Al7.5 which is ‘ultrathin’ compared with the localization length and/or the length scale of short range order. The local electronic structure must appear more inherent, having states at E f available for tip-sample tunneling current. To enhance imaging contrasts between long-range and short-range orders, the highly oriented pyrolytic graphite was chosen as substrate, so that the structural heterogeneity arising from competition between the glass former ability and the epitaxy can be ascertained. A chemical order predicted for this system was observed in atomic ordered regimes (1–2 monolayers), accompanied with a superstructure with the period Zr–Cu(Al)–Zr along three hexagonal axes. The result implies a chemical short range order in disordered regimes, where polyhedral clusters are dominant with the solute atom Cu(Al) in the center. An attempt for the structural modelling was made based on high resolution STM images, giving icosahedral order on the surface and different Voronoi clusters in 3D space.

Monte Carlo simulations on marker grouping and ordering.

Science.gov (United States)

Wu, J; Jenkins, J; Zhu, J; McCarty, J; Watson, C

2003-08-01

Four global algorithms, maximum likelihood (ML), sum of adjacent LOD score (SALOD), sum of adjacent recombinant fractions (SARF) and product of adjacent recombinant fraction (PARF), and one approximation algorithm, seriation (SER), were used to compare the marker ordering efficiencies for correctly given linkage groups based on doubled haploid (DH) populations. The Monte Carlo simulation results indicated the marker ordering powers for the five methods were almost identical. High correlation coefficients were greater than 0.99 between grouping power and ordering power, indicating that all these methods for marker ordering were reliable. Therefore, the main problem for linkage analysis was how to improve the grouping power. Since the SER approach provided the advantage of speed without losing ordering power, this approach was used for detailed simulations. For more generality, multiple linkage groups were employed, and population size, linkage cutoff criterion, marker spacing pattern (even or uneven), and marker spacing distance (close or loose) were considered for obtaining acceptable grouping powers. Simulation results indicated that the grouping power was related to population size, marker spacing distance, and cutoff criterion. Generally, a large population size provided higher grouping power than small population size, and closely linked markers provided higher grouping power than loosely linked markers. The cutoff criterion range for achieving acceptable grouping power and ordering power differed for varying cases; however, combining all situations in this study, a cutoff criterion ranging from 50 cM to 60 cM was recommended for achieving acceptable grouping power and ordering power for different cases.

Computerized provider order entry systems.

Science.gov (United States)

2001-01-01

Computerized provider order entry (CPOE) systems are designed to replace a hospital's paper-based ordering system. They allow users to electronically write the full range of orders, maintain an online medication administration record, and review changes made to an order by successive personnel. They also offer safety alerts that are triggered when an unsafe order (such as for a duplicate drug therapy) is entered, as well as clinical decision support to guide caregivers to less expensive alternatives or to choices that better fit established hospital protocols. CPOE systems can, when correctly configured, markedly increase efficiency and improve patient safety and patient care. However, facilities need to recognize that currently available CPOE systems require a tremendous amount of time and effort to be spent in customization before their safety and clinical support features can be effectively implemented. What's more, even after they've been customized, the systems may still allow certain unsafe orders to be entered. Thus, CPOE systems are not currently a quick or easy remedy for medical errors. ECRI's Evaluation of CPOE systems--conducted in collaboration with the Institute for Safe Medication Practices (ISMP)--discusses these and other related issues. It also examines and compares CPOE systems from three suppliers: Eclipsys Corp., IDX Systems Corp., and Siemens Medical Solutions Health Services Corp. Our testing focuses primarily on the systems' interfacing capabilities, patient safeguards, and ease of use.

6th Conference on Non-integer Order Calculus and Its Applications

CERN Document Server

Łukaniszyn, Marian; Stanisławski, Rafał

2015-01-01

This volume presents selected aspects of non-integer, or fractional order systems, whose analysis, synthesis and applications have increasingly become a real challenge for various research communities, ranging from science to engineering. The spectrum of applications of the fractional order calculus has incredibly expanded, in fact it would be hard to find a science/engineering-related subject area where the fractional calculus had not been incorporated. The content of the fractional calculus is ranged from pure mathematics to engineering implementations and so is the content of this volume. The volume is subdivided into six parts, reflecting particular aspects of the fractional order calculus. The first part contains a single invited paper on a new formulation of fractional-order descriptor observers for fractional-order descriptor continous LTI systems. The second part provides new elements to the mathematical theory of fractional-order systems. In the third part of this volume, a bunch of new results in ap...

Order Aggressiveness and Order Book Dynamics

OpenAIRE

Anthony D. Hall; Nikolaus Hautsch

2004-01-01

In this paper, we study the determinants of order aggressiveness and traders' order submission strategy in an open limit order book market. Using order book data from the Australian Stock Exchange, we model traders' aggressiveness in market trading, limit order trading as well as in order cancellations on both sides of the market using a six-dimensional autoregressive intensity model. The information revealed by the open order book plays an important role in explaining the degree of order agg...

Finite-range-scaling analysis of metastability in an Ising model with long-range interactions

International Nuclear Information System (INIS)

Gorman, B.M.; Rikvold, P.A.; Novotny, M.A.

1994-01-01

We apply both a scalar field theory and a recently developed transfer-matrix method to study the stationary properties of metastability in a two-state model with weak, long-range interactions: the Nx∞ quasi-one-dimensional Ising model. Using the field theory, we find the analytic continuation f of the free energy across the first-order transition, assuming that the system escapes the metastable state by the nucleation of noninteracting droplets. We find that corrections to the field dependence are substantial, and, by solving the Euler-Lagrange equation for the model numerically, we have verified the form of the free-energy cost of nucleation, including the first correction. In the transfer-matrix method, we associate with the subdominant eigenvectors of the transfer matrix a complex-valued ''constrained'' free-energy density f α computed directly from the matrix. For the eigenvector with an associated magnetization most strongly opposed to the applied magnetic field, f α exhibits finite-range scaling behavior in agreement with f over a wide range of temperatures and fields, extending nearly to the classical spinodal. Some implications of these results for numerical studies of metastability are discussed

Topography of the Lunar Poles and Application to Geodesy with the Lunar Reconnaissance Orbiter

Science.gov (United States)

Mazarico, Erwan; Neumann, Gregory A.; Rowlands, David D.; Smith, David E.; Zuber, Maria T.

2012-01-01

The Lunar Orbiter Laser Altimeter (LOLA) [1] onboard the Lunar Reconnaissance Orbiter (LRO) [2] has been operating continuously since July 2009 [3], accumulating approx.5.4 billion measurements from 2 billion on-orbit laser shots. LRO s near-polar orbit results in very high data density in the immediate vicinity of the lunar poles, which are each sampled every 2h. With more than 10,000 orbits, high-resolution maps can be constructed [4] and studied [5]. However, this requires careful processing of the raw data, as subtle errors in the spacecraft position and pointing can lead to visible artifacts in the final map. In other locations on the Moon, ground tracks are subparallel and longitudinal separations are typically a few hundred meters. Near the poles, the track intersection angles can be large and the inter-track spacing is small (above 80 latitude, the effective resolution is better than 50m). Precision Orbit Determination (POD) of the LRO spacecraft [6] was performed to satisfy the LOLA and LRO mission requirements, which lead to a significant improvement in the orbit position knowledge over the short-release navigation products. However, with pixel resolutions of 10 to 25 meters, artifacts due to orbit reconstruction still exist. Here, we show how the complete LOLA dataset at both poles can be adjusted geometrically to produce a high-accuracy, high-resolution maps with minimal track artifacts. We also describe how those maps can then feedback to the POD work, by providing topographic base maps with which individual LOLA altimetric measurements can be contributing to orbit changes. These direct altimetry constraints improve accuracy and can be used more simply than the altimetric crossovers [6].

Inertial-range structure of Gross–Pitaevskii turbulence within a spectral closure approximation

International Nuclear Information System (INIS)

Yoshida, Kyo; Arimitsu, Toshihico

2013-01-01

The inertial-range structure of turbulence obeying the Gross–Pitaevskii equation, the equation of motion for quantum fluids, is analyzed by means of a spectral closure approximation. It is revealed that, for the energy-transfer range, the spectrum of the order parameter field ψ obeys k −2 law for k ≪ k * and k −1 law for k ≫ k * , where k * is the wavenumber where the characteristic timescales associated with linear and nonlinear terms are of the same order. It is also shown that, for the particle-number-transfer range, the spectrum obeys k −1 law for k ≪ k *, n and k −1/3 law for k ≫ k *,n , where k *,n is the wavenumber corresponding to k * in the particle-number-transfer range. (paper)

A second-order class-D audio amplifier

OpenAIRE

Cox, Stephen M.; Tan, M.T.; Yu, J.

2011-01-01

Class-D audio amplifiers are particularly efficient, and this efficiency has led to their ubiquity in a wide range of modern electronic appliances. Their output takes the form of a high-frequency square wave whose duty cycle (ratio of on-time to off-time) is modulated at low frequency according to the audio signal. A mathematical model is developed here for a second-order class-D amplifier design (i.e., containing one second-order integrator) with negative feedback. We derive exact expression...

Dynamic range extension of BPM at the NSLS

International Nuclear Information System (INIS)

Bordoley, M.

1993-01-01

In order to overcome range limitations, the existing Beam Position Monitor (BPM) receiver was modified, extending the dynamic range from 35 dB to 60 dB. The modifications include the insertion of an RF PIN attenuator, RF amplifier, and control circuitry in line with the RF link to add an extra 25dB to the existing AGC loop. This stand alone 25dB RF gain control stage is integrated into the present system without any change to the existing receiver

Cilia are required for asymmetric nodal induction in the sea urchin embryo.

Science.gov (United States)

Tisler, Matthias; Wetzel, Franziska; Mantino, Sabrina; Kremnyov, Stanislav; Thumberger, Thomas; Schweickert, Axel; Blum, Martin; Vick, Philipp

2016-08-23

Left-right (LR) organ asymmetries are a common feature of metazoan animals. In many cases, laterality is established by a conserved asymmetric Nodal signaling cascade during embryogenesis. In most vertebrates, asymmetric nodal induction results from a cilia-driven leftward fluid flow at the left-right organizer (LRO), a ciliated epithelium present during gastrula/neurula stages. Conservation of LRO and flow beyond the vertebrates has not been reported yet. Here we study sea urchin embryos, which use nodal to establish larval LR asymmetry as well. Cilia were found in the archenteron of embryos undergoing gastrulation. Expression of foxj1 and dnah9 suggested that archenteron cilia were motile. Cilia were polarized to the posterior pole of cells, a prerequisite of directed flow. High-speed videography revealed rotating cilia in the archenteron slightly before asymmetric nodal induction. Removal of cilia through brief high salt treatments resulted in aberrant patterns of nodal expression. Our data demonstrate that cilia - like in vertebrates - are required for asymmetric nodal induction in sea urchin embryos. Based on these results we argue that the anterior archenteron represents a bona fide LRO and propose that cilia-based symmetry breakage is a synapomorphy of the deuterostomes.

Pyrolytic Graphite as a Tunable Second order Neutron Filter

International Nuclear Information System (INIS)

Adib, M.

2009-01-01

A study has been carried out on the neutron transmission through pyrolytic graphite (PG) crystals in order to check its applicability as an efficient tunable second order neutron filter. The neutron transmission have been calculated as a function of neutron wavelengths in the range from 0.01 nm up to 0.7 nm at various PG mosaic spread, thickness and orientation of its c-axis with respect to the beam direction The Computer package Graphite has been used to provide the required calculation. It was shown that highly aligned (10 FWHM on mosaic spread) PG crystal ∼2 cm thick, may be tuned for optimum scattering of 2 second order neutrons within some favorable wavelength intervals in the range between 0.112 and 0.425 nm by adjusting the crystal in an appropriate orientation. .However, a less quality and thinner PG was found to almost eliminate 2 second order neutrons at only tuned values of wavelength corresponding to the poison of the triple intersection points of the curves (hkl) ± and (00l)

Order aggressiveness and order book dynamics

DEFF Research Database (Denmark)

Hall, Anthony D.; Hautsch, Nikolaus

2006-01-01

In this paper, we study the determinants of order aggressiveness and traders’ order submission strategy in an open limit order book market. Applying an order classification scheme, we model the most aggressive market orders, limit orders as well as cancellations on both sides of the market...... employing a six-dimensional autoregressive conditional intensity model. Using order book data from the Australian Stock Exchange, we find that market depth, the queued volume, the bid-ask spread, recent volatility, as well as recent changes in both the order flow and the price play an important role...... in explaining the determinants of order aggressiveness. Overall, our empirical results broadly confirm theoretical predictions on limit order book trading. However, we also find evidence for behavior that can be attributed to particular liquidity and volatility effects...

Mixed-order phase transition in a colloidal crystal

Science.gov (United States)

Alert, Ricard; Tierno, Pietro; Casademunt, Jaume

2017-12-01

Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid-solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field H. At the transition field Hs, the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length ξ∝|H2-Hs2|-1/2. Mean-field critical exponents are predicted, since the upper critical dimension of the transition is du=2. Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions.

Mixed-order phase transition in a colloidal crystal.

Science.gov (United States)

Alert, Ricard; Tierno, Pietro; Casademunt, Jaume

2017-12-05

Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid-solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field [Formula: see text] At the transition field [Formula: see text], the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length [Formula: see text] Mean-field critical exponents are predicted, since the upper critical dimension of the transition is [Formula: see text] Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions.

A statistical-thermodynamic model for ordering phenomena in thin film intermetallic structures

International Nuclear Information System (INIS)

Semenova, Olga; Krachler, Regina

2008-01-01

Ordering phenomena in bcc (110) binary thin film intermetallics are studied by a statistical-thermodynamic model. The system is modeled by an Ising approach that includes only nearest-neighbor chemical interactions and is solved in a mean-field approximation. Vacancies and anti-structure atoms are considered on both sublattices. The model describes long-range ordering and simultaneously short-range ordering in the thin film. It is applied to NiAl thin films with B2 structure. Vacancy concentrations, thermodynamic activity profiles and the virtual critical temperature of order-disorder as a function of film composition and thickness are presented. The results point to an important role of vacancies in near-stoichiometric and Ni-rich NiAl thin films

Pathogenicity gene variations within the order Entomophthorales

DEFF Research Database (Denmark)

Grell, Morten Nedergaard; Jensen, Annette Bruun; Lange, Lene

Fungi within the order Entomophthorales (subphylum Entomophthoromycotina) are obligate biotrophic pathogens of arthropods with a remarkable narrow host range. Infection takes place through the cuticle when conidia hit a susceptible host, facilitated by enzymatic and mechanical mechanisms. In the ...... pathogenicity genes within genera Entomophthora and Pandora, using fungal genomic DNA originating from field-collected, infected insect host species of dipteran (flies, mosquitoes) or hemipteran (aphid) origin.......Fungi within the order Entomophthorales (subphylum Entomophthoromycotina) are obligate biotrophic pathogens of arthropods with a remarkable narrow host range. Infection takes place through the cuticle when conidia hit a susceptible host, facilitated by enzymatic and mechanical mechanisms......, conidia are produced and discharged when humidity gets high—usually during night. In an earlier secretome study of field-collected grain aphids (Sitobion avenae) infected with entomophthoralean fungi, a number of pathogenesis-related, secreted enzymes were discovered (Fungal Genetics and Biology 2011, vol...

Higher Order and Fractional Diffusive Equations

Directory of Open Access Journals (Sweden)

D. Assante

2015-07-01

Full Text Available We discuss the solution of various generalized forms of the Heat Equation, by means of different tools ranging from the use of Hermite-Kampé de Fériet polynomials of higher and fractional order to operational techniques. We show that these methods are useful to obtain either numerical or analytical solutions.

Range distributions in multiply implanted targets

International Nuclear Information System (INIS)

Kostic, S.; Jimenez-Rodriguez, J.J.; Karpuzov, D.S.; Armour, D.G.; Carter, G.; Salford Univ.

1984-01-01

Range distributions in inhomogeneous binary targets have been investigated both theoretically and experimentally. Silicon single crystal targets [(111) orientation] were implanted with 40 keV Pb + ions to fluences in the range from 5x10 14 to 7.5x10 16 cm -2 prior to bombardment with 80 keV Kr + ions to a fluence of 5x10 15 cm -2 . The samples were analysed using high resolution Rutherford backscattering before and after the krypton implantation in order to determine the dependence of the krypton distribution on the amount of lead previously implanted. The theoretical analysis was undertaken using the formalism developed in [1] and the computer simulation was based on the MARLOWE code. The agreement between the experimental, theoretical and computational krypton profiles is very good and the results indicate that accurate prediction of ranges profiles in inhomogeneous binary targets is possible using available theoretical and computational treatments. (orig.)

A high dynamic range pulse counting detection system for mass spectrometry.

Science.gov (United States)

Collings, Bruce A; Dima, Martian D; Ivosev, Gordana; Zhong, Feng

2014-01-30

A high dynamic range pulse counting system has been developed that demonstrates an ability to operate at up to 2e8 counts per second (cps) on a triple quadrupole mass spectrometer. Previous pulse counting detection systems have typically been limited to about 1e7 cps at the upper end of the systems dynamic range. Modifications to the detection electronics and dead time correction algorithm are described in this paper. A high gain transimpedance amplifier is employed that allows a multi-channel electron multiplier to be operated at a significantly lower bias potential than in previous pulse counting systems. The system utilises a high-energy conversion dynode, a multi-channel electron multiplier, a high gain transimpedance amplifier, non-paralysing detection electronics and a modified dead time correction algorithm. Modification of the dead time correction algorithm is necessary due to a characteristic of the pulse counting electronics. A pulse counting detection system with the capability to count at ion arrival rates of up to 2e8 cps is described. This is shown to provide a linear dynamic range of nearly five orders of magnitude for a sample of aprazolam with concentrations ranging from 0.0006970 ng/mL to 3333 ng/mL while monitoring the m/z 309.1 → m/z 205.2 transition. This represents an upward extension of the detector's linear dynamic range of about two orders of magnitude. A new high dynamic range pulse counting system has been developed demonstrating the ability to operate at up to 2e8 cps on a triple quadrupole mass spectrometer. This provides an upward extension of the detector's linear dynamic range by about two orders of magnitude over previous pulse counting systems. Copyright © 2013 John Wiley & Sons, Ltd.

Development of the full range vange vacuum gauge

International Nuclear Information System (INIS)

Oh, B. H.; In, S. R.; Jung, K. S.; Jeong, S. H.

2001-01-01

The pirani, enning end full range gauges developed during this study had made good characteristics compared with the measured results of customized other gauges, and this results show the possibility of developing the gauges by ourselves in Korea. In order to make a competition with the customized gauges of other countries, it is necessary to upgrade several points to have good characteristics over the large range of the pressure. The new effort will be made in developing the full scale gauge in the next year

Two-dimensional melting of colloids with long-range attractive interactions.

Science.gov (United States)

Du, Di; Doxastakis, Manolis; Hilou, Elaa; Biswal, Sibani Lisa

2017-02-22

The solid-liquid melting transition in a two-dimensional (2-D) attractive colloidal system is visualized using superparamagnetic colloids that interact through a long-range isotropic attractive interaction potential, which is induced using a high-frequency rotating magnetic field. Various experiments, supported by Monte Carlo simulations, are carried out over a range of interaction potentials and densities to determine structure factors, Lindermann parameters, and translational and orientational order parameters. The system shows a first-order solid-liquid melting transition. Simulations and experiments suggest that dislocations and disclinations simultaneously unbind during melting. This is in direct contrast with reports of 2-D melting of paramagnetic particles that interact with a repulsive interaction potential.

Ab initio molecular dynamics model for density, elastic properties and short range order of Co-Fe-Ta-B metallic glass thin films

International Nuclear Information System (INIS)

Hostert, C; Music, D; Schneider, J M; Bednarcik, J; Keckes, J; Kapaklis, V; Hjörvarsson, B

2011-01-01

Density, elastic modulus and the pair distribution function of Co-Fe-Ta-B metallic glasses were obtained by ab initio molecular dynamics simulations and measured for sputtered thin films using x-ray reflectivity, nanoindentation and x-ray diffraction using high energy photons. The computationally obtained density of 8.19 g cm -3 for Co 43 Fe 20 Ta 5.5 B 31.5 and 8.42 g cm -3 for Co 45.5 Fe 24 Ta 6 B 24.5 , as well as the Young’s moduli of 273 and 251 GPa, respectively, are consistent with our experiments and literature data. These data, together with the good agreement between the theoretical and the experimental pair distribution functions, indicate that the model established here is useful to describe the density, elasticity and short range order of Co-Fe-Ta-B metallic glass thin films. Irrespective of the investigated variation in chemical composition, (Co, Fe)-B cluster formation and Co-Fe interactions are identified by density-of-states analysis. Strong bonds within the structural units and between the metallic species may give rise to the comparatively large stiffness. (paper)

Medium range order and structural relaxation in As–Se network glasses through FSDP analysis

International Nuclear Information System (INIS)

Golovchak, R.; Lucas, P.; Oelgoetz, J.; Kovalskiy, A.; York-Winegar, J.; Saiyasombat, Ch; Shpotyuk, O.; Feygenson, M.; Neuefeind, J.; Jain, H.

2015-01-01

Synchrotron X-ray diffraction and neutron scattering studies are performed on As–Se glasses in two states: as-prepared (rejuvenated) and aged for ∼27 years. The first sharp diffraction peak (FSDP) obtained from the structure factor data as a function of composition and temperature indicates that the cooperative processes that are responsible for structural relaxation do not affect FSDP. The results are correlated with the composition dependence of the complex heat capacity of the glasses and concentration of different structural fragments in the glass network. The comparison of structural information shows that density fluctuations, which were thought previously to have a significant contribution to FSDP, have much smaller effect than the cation–cation correlations, presence of ordered structural fragments or cage molecules. - Highlights: • Aged and non-aged As–Se glasses are studied with XRD and neutron scattering. • Compositional and temperature dependences of FSDP are analyzed. • FSDP parameters are correlated with (non)isothermal structural relaxation data

Medium range order and structural relaxation in As–Se network glasses through FSDP analysis

Energy Technology Data Exchange (ETDEWEB)

Golovchak, R., E-mail: holovchakr@apsu.edu [Department of Physics and Astronomy, Austin Peay State University, Clarksville, TN 37044 (United States); Lucas, P. [Department of Materials Science and Engineering, University of Arizona, Tucson, AZ 85712 (United States); Oelgoetz, J.; Kovalskiy, A.; York-Winegar, J. [Department of Physics and Astronomy, Austin Peay State University, Clarksville, TN 37044 (United States); Saiyasombat, Ch [Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015-3195 (United States); Shpotyuk, O. [Institute of Physics, Jan Dlugosz University of Czestochowa, al. Armii Krajowej 13/15, Czestochowa 42200 (Poland); Feygenson, M.; Neuefeind, J. [Chemical and Engineering Materials Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Jain, H. [Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015-3195 (United States)

2015-03-01

Synchrotron X-ray diffraction and neutron scattering studies are performed on As–Se glasses in two states: as-prepared (rejuvenated) and aged for ∼27 years. The first sharp diffraction peak (FSDP) obtained from the structure factor data as a function of composition and temperature indicates that the cooperative processes that are responsible for structural relaxation do not affect FSDP. The results are correlated with the composition dependence of the complex heat capacity of the glasses and concentration of different structural fragments in the glass network. The comparison of structural information shows that density fluctuations, which were thought previously to have a significant contribution to FSDP, have much smaller effect than the cation–cation correlations, presence of ordered structural fragments or cage molecules. - Highlights: • Aged and non-aged As–Se glasses are studied with XRD and neutron scattering. • Compositional and temperature dependences of FSDP are analyzed. • FSDP parameters are correlated with (non)isothermal structural relaxation data.

Mixed-order phase transition in a one-dimensional model.

Science.gov (United States)

Bar, Amir; Mukamel, David

2014-01-10

We introduce and analyze an exactly soluble one-dimensional Ising model with long range interactions that exhibits a mixed-order transition, namely a phase transition in which the order parameter is discontinuous as in first order transitions while the correlation length diverges as in second order transitions. Such transitions are known to appear in a diverse classes of models that are seemingly unrelated. The model we present serves as a link between two classes of models that exhibit a mixed-order transition in one dimension, namely, spin models with a coupling constant that decays as the inverse distance squared and models of depinning transitions, thus making a step towards a unifying framework.

Effect of mesoscale ordering on the density of States of polymeric semiconductors.

Science.gov (United States)

Gemünden, Patrick; Poelking, Carl; Kremer, Kurt; Daoulas, Kostas; Andrienko, Denis

2015-06-01

A multiscale simulation scheme, which incorporates both long-range conformational disorder and local molecular ordering, is proposed for predicting large-scale morphologies and charge transport properties of polymeric semiconductors. Using poly(3-hexylthiophene) as an example, it is illustrated how the energy landscape and its spatial correlations evolve with increasing degree of structural order in mesophases with amorphous, uniaxial, and biaxial nematic ordering. It is shown that the formation of low-lying energy states in more ordered systems is mostly due to larger (on average) conjugation lengths and not due to electrostatic interactions. The proposed scheme is general and can be applied to a wide range of polymeric organic materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Range of Microbial Risks in Food Processing

NARCIS (Netherlands)

Zwietering, M.H.; Straver, J.M.; Asselt, van E.D.

2016-01-01

Foodborne illnesses can be caused by a wide range of microorganisms. Data analysis can help to determine which microorganisms give the highest contribution to the number of foodborne illnesses. This helps to decide which pathogen(s) to focus on in order to reduce the number of illnesses. The same

The Ranges Of Subauroral Geomagnetic Field Elements | Rabiu ...

African Journals Online (AJOL)

Nigeria Journal of Pure and Applied Physics ... An anomaly in seasonal response of range at high solar activity is observed on disturbed condition. ... apart from the anomaly - maintain the order e>j>d of seasonal variation which is in agreement with the popular equinoctial maximum observed in geomagnetic activity.

Dynamic range studies of the RCA streak tube in the LLL streak camera

International Nuclear Information System (INIS)

Thomas, S.W.; Phillips, G.E.

1979-01-01

As indicated by tests on several cameras, the dynamic range of the Lawrence Livermore Laboratory streak-camera system appears to be about two orders of magnitude greater than those reported for other systems for 10- to 200-ps pulses. The lack of a fine mesh grid in the RCA streak tube used in these cameras probably contributes to a lower system dynamic noise and therefore raises the dynamic range. A developmental tube with a mesh grid was tested and supports this conjecture. Order-of-magnitude variations in input slit width do not affect the spot size on the phosphor or the dynamic range of the RCA tube. (author)

Quantum phase transition in strongly correlated many-body system

Science.gov (United States)

You, Wenlong

in the Ising model, and then we say long range order (LRO) exists in the system. LRO plays a key role in determining the ordered-disorder transition. Thereby, we investigate two-dimensional 120° orbital-only model to present how to extract the information of LRO in a pedagogical manner, by applying the reflection positivity method introduced by Dyson, Lieb, and Simon. We rigorously establish the existence of an anti-ferromagnetic like transverse orbital long-range order in the so called two-dimensional 120° model at zero temperature. Next we consider possible pairings in the family of FeAs-based ReO1--xFxFeAs (Re=La, Nd, Ce, Pr, etc.) high-temperature superconductors. We build some identities based on a two-orbital model, and obtained some constraints on a few possible pairings. We also establish the sufficient conditions for the coexistence of two superconducting orders, and we propose the most favorable pairings around half filling according to physical consideration. In chapter 3, we present a quantum solvation process with solvent of fermion character based on the one-dimensional asymmetric t-J-Jz model. The model is experimental realizable in optical lattices and exhibits rich physics. In this work, we show that there exist two types of phase separations, one is driven by potential energy while the other by kinetic energy. In between, solvation process occurs. Analytically, we are able to obtain some rigorous results to understand the underlying physics. Numerically, we perform exact diagonalization and density matrix renormalization group calculations, accompanied by detailed finite size analysis. In chapter 4, we explore several characterizations of QPT points. As distinguished from the methods in condensed-matter physics, we give much attention to understand QPT from the quantum information (QI) point of view. The perspective makes a new bridge between these two fields. It no only can facilitate the understanding of condensed-matter physics, but also

Ferro electricity from magnetic order by neutron measurement

International Nuclear Information System (INIS)

Kenzelmann, M.

2009-01-01

Magnetic insulators with competing exchange interactions can give rise to strong fluctuations and qualitatively new ground states. The proximity of such systems to quantum critical points can lead to strong cross-coupling between magnetic long-range order and the nuclear lattice. Case in point is a new class of multiferroic materials in which the magnetic and ferroelectric order parameters are directly coupled, and a magnetic field can suppress or switch the electric polarization [1]. Our neutron measurements reveal that ferro electricity is induced by magnetic order and emerges only if the magnetic structure creates a polar axis [2-5]. Our measurements provide evidence that commensurate magnetic order can produce ferro electricity with large electric polarization [6]. The spin dynamics and the field-temperature phase diagram of the ordered phases provide evidence that competing ground states are essential for ferro electricity. (author)

High speed, wide dynamic range analog signal processing for avalanche photodiode

CERN Document Server

Walder, J P; Pangaud, P

2000-01-01

A wide dynamic range multi-gain analog transimpedance amplifier integrated circuit has been developed for avalanche photodiode signal processing. The 96 dB input dynamic range is divided into four ranges of 12-bits each in order to provide 40 MHz analog sampled data to a 12-bits ADC. This concept which has been integrated in both BiCMOS and full complementary bipolar technology along with fitted design techniques will be presented.

High speed, wide dynamic range analog signal processing for avalanche photodiode

International Nuclear Information System (INIS)

Walder, J.P.; El Mamouni, Houmani; Pangaud, Patrick

2000-01-01

A wide dynamic range multi-gain analog transimpedance amplifier integrated circuit has been developed for avalanche photodiode signal processing. The 96 dB input dynamic range is divided into four ranges of 12-bits each in order to provide 40 MHz analog sampled data to a 12-bits ADC. This concept which has been integrated in both BiCMOS and full complementary bipolar technology along with fitted design techniques will be presented

High speed, wide dynamic range analog signal processing for avalanche photodiode

Energy Technology Data Exchange (ETDEWEB)

Walder, J.P. E-mail: walder@in2p3.fr; El Mamouni, Houmani; Pangaud, Patrick

2000-03-11

A wide dynamic range multi-gain analog transimpedance amplifier integrated circuit has been developed for avalanche photodiode signal processing. The 96 dB input dynamic range is divided into four ranges of 12-bits each in order to provide 40 MHz analog sampled data to a 12-bits ADC. This concept which has been integrated in both BiCMOS and full complementary bipolar technology along with fitted design techniques will be presented.

Self-ordered, controlled structure nanoporous membranes using constant current anodization.

Science.gov (United States)

Lee, Kwan; Tang, Yun; Ouyang, Min

2008-12-01

We report a constant current (CC) based anodization technique to fabricate and control structure of mechanically stable anodic aluminum oxide (AAO) membranes with a long-range ordered hexagonal nanopore pattern. For the first time we show that interpore distance (Dint) of a self-ordered nanopore feature can be continuously tuned over a broad range with CC anodization and is uniquely defined by the conductivity of sulfuric acid as electrolyte. We further demonstrate that this technique can offer new degrees of freedom for engineering planar nanopore structures by fine tailoring the CC based anodization process. Our results not only facilitate further understanding of self-ordering mechanism of alumina membranes but also provide a fast, simple (without requirement of prepatterning or preoxide layer), and flexible methodology for controlling complex nanoporous structures, thus offering promising practical applications in nanotechnology.

Lunar Exploration Island, NASA’s Return to the Moon in Second Life

Science.gov (United States)

Ireton, F. M.; Bleacher, L.; Day, B.; Hsu, B. C.; Mitchell, B. K.

2009-12-01

Second Life is a metaverse—a massively multi-user virtual world (MMVR) community. With over 9 million users worldwide, there are 40,000-50,000 users on line at any one time. Second Life hosts over 200 educational and institutional simulation locations termed “islands” or sims that are developed by users providing support for education and business endeavors. On-line tools are provided to construct structures and landforms simulating a real world in a virtual three-dimensional environment. Users develop a persona and are seen on screen as a human figure or avatar. Avatars move in Second Life by walking, flying, or teleporting and interact with other users via text or voice chat. This poster details the design and creation of the Second Life exhibit hall for NASA’s Lunar Precursor Robotics Program and the LRO/LCROSS missions. The hall has been placed on the Lunar Exploration Island (LEI) in Second Life. Avatars enter via teleportation to an orientation room with information about the project, a simulator map, and other information. A central hall of flight houses exhibits pertaining to the LRO/ LCROSS missions and includes full size models of the two spacecraft and launch vehicle. Storyboards with information about the missions interpret the exhibits while links to external websites provide further information on the missions, both spacecraft instrument suites, and EPO directed to support the missions. The sim includes several sites for meetings, a conference amphitheater with a stage and screen for video links such as live broadcasts of conferences and speakers. A link is provided to NASATV for live viewing LRO/LCROSS launch and impact activities and other NASA events. Recently visitors have viewed the Hubble servicing mission and several shuttle launches as well as the LRO/LCROSS launch. Lunar Exploration Island in Second Life

Rocky Flats Plant Live-Fire Range Risk Analysis Report

Energy Technology Data Exchange (ETDEWEB)

Nicolosi, S.L.; Rodriguez, M.A.

1994-04-01

The objective of the Live-Fire Range Risk Analysis Report (RAR) is to provide an authorization basis for operation as required by DOE 5480.16. The existing Live-Fire Range does not have a safety analysis-related authorization basis. EG&G Rocky Flats, Inc. has worked with DOE and its representatives to develop a format and content description for development of an RAR for the Live-Fire Range. Development of the RAR is closely aligned with development of the design for a baffle system to control risks from errant projectiles. DOE 5480.16 requires either an RAR or a safety analysis report (SAR) for live-fire ranges. An RAR rather than a SAR was selected in order to gain flexibility to more closely address the safety analysis and conduct of operation needs for a live-fire range in a cost-effective manner.

The microstructure of spontaneously ordered GaInP2 alloy

International Nuclear Information System (INIS)

Sinha, K.; Mascarenhas, A.; Alonso, R.G.; Horner, G.S.; Bertness, K.A.; Kurtz, S.R.; Olson, J.M.

1994-01-01

Polarized photoluminescence, photoluminescence excitation, piezomodulated reflectivity, and resonance Raman techniques have been employed to probe the electronic structure of GaInP 2 alloys exhibiting Cu--Pt ordering. The ordering induced band gap reduction and the crystal field splitting of the valence bands have been studied for samples exhibiting various degrees of ordering. Our studies provide evidence for a distribution of order parameters in spontaneously ordered GaInP 2 , in contrast to earlier works, which assume that uniformly ordered domains are embedded in a perfectly disordered matrix. Furthermore, the band gap reduction and the crystal field splitting obtained from our experiments are in good agreement with a theoretical model relating these quantities to the long range order parameter in the sample

Coherent change detection and interferometric ISAR measurements in the folded compact range

Energy Technology Data Exchange (ETDEWEB)

Sorensen, K.W.

1996-08-01

A folded compact range configuration has been developed ant the Sandia National Laboratories` compact range antenna and radar-cross- section measurement facility as a means of performing indoor, environmentally-controlled, far-field simulations of synthetic aperture radar (SAR) measurements of distributed target samples (i.e. gravel, sand, etc.). The folded compact range configuration has previously been used to perform coherent-change-detection (CCD) measurements, which allow disturbances to distributed targets on the order of fractions of a wavelength to be detected. This report describes follow-on CCD measurements of other distributed target samples, and also investigates the sensitivity of the CCD measurement process to changes in the relative spatial location of the SAR sensor between observations of the target. Additionally, this report describes the theoretical and practical aspects of performing interferometric inverse-synthetic-aperture-radar (IFISAR) measurements in the folded compact range environment. IFISAR measurements provide resolution of the relative heights of targets with accuracies on the order of a wavelength. Several examples are given of digital height maps that have been generated from measurements performed at the folded compact range facility.

Modulated ordering Nb-H alloys

International Nuclear Information System (INIS)

Kajitani, T.; Brun, T.O.; Mueller, M.H.; Birnbaum, H.K.; Makenas, B.J.

1979-01-01

Ordering reactions in α' and β-NbH alloys have been investigated using elastic theory. The α'-β and β-lambda phase transformations are driven by the elastic interaction in the niobium lattice distorted by the protons on the t-site interstitials. The β phase is shown to have a three dimensional structure. The fundamental period of the long range modulation along the c-axis in the lambda-phase, an incommensurated β phase, is approximately 5 lattice constants

Lateral Order and Self-Organized Morphology of Diblock Copolymer Micellar Films

Directory of Open Access Journals (Sweden)

Jiun-You Liou

2018-05-01

Full Text Available We report the lateral order and self-organized morphology of diblock copolymer polystyrene-block-poly(2-vinylpyridine, P(S-b-2VP, and micelles on silicon substrates (SiOx/Si. These micellar films were prepared by spin coating from polymer solutions of varied concentration of polymer in toluene onto SiOx/Si, and were investigated with grazing-incidence small-angle X-ray scattering (GISAXS and an atomic force microscope (AFM. With progressively increased surface coverage with increasing concentration, loosely packed spherical micelles, ribbon-like nanostructures, and a second layer of spherical micelles were obtained sequentially. Quantitative analysis and simulations of the micellar packing demonstrates that the spatial ordering of the loosely packed spherical micelles altered from short-range order to hexagonal order when the micellar coverage increased from small to moderate densities of the covered surface. At large densities, anisotropic fusion between spherical micelles caused the ribbon-like nanostructures to have a short-range spatial order; the ordering quality of the second layer was governed by the rugged surface of the underlying layer because the valleys between the ribbon-like nanostructures allowed for further deposition of spherical micelles.

The amblyopic deficit for 2nd order processing: Generality and laterality.

Science.gov (United States)

Gao, Yi; Reynaud, Alexandre; Tang, Yong; Feng, Lixia; Zhou, Yifeng; Hess, Robert F

2015-09-01

A number of previous reports have suggested that the processing of second-order stimuli by the amblyopic eye (AE) is defective and that the fellow non-amblyopic eye (NAE) also exhibits an anomaly. Second-order stimuli involve extra-striate as well as striate processing and provide a means of exploring the extent of the cortical anomaly in amblyopia using psychophysics. We use a range of different second-order stimuli to investigate how general the deficit is for detecting second-order stimuli in adult amblyopes. We compare these results to our previously published adult normative database using the same stimuli and approach to determine the extent to which the detection of these stimuli is defective for both amblyopic and non-amblyopic eye stimulation. The results suggest that the second-order deficit affects a wide range of second-order stimuli, and by implication a large area of extra-striate cortex, both dorsally and ventrally. The NAE is affected only in motion-defined form judgments, suggesting a difference in the degree to which ocular dominance is disrupted in dorsal and ventral extra-striate regions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Default settings of computerized physician order entry system order sets drive ordering habits.

Science.gov (United States)

Olson, Jordan; Hollenbeak, Christopher; Donaldson, Keri; Abendroth, Thomas; Castellani, William

2015-01-01

Computerized physician order entry (CPOE) systems are quickly becoming ubiquitous, and groups of orders ("order sets") to allow for easy order input are a common feature. This provides a streamlined mechanism to view, modify, and place groups of related orders. This often serves as an electronic equivalent of a specialty requisition. A characteristic, of these order sets is that specific orders can be predetermined to be "preselected" or "defaulted-on" whenever the order set is used while others are "optional" or "defaulted-off" (though there is typically the option is to "deselect" defaulted-on tests in a given situation). While it seems intuitive that the defaults in an order set are often accepted, additional study is required to understand the impact of these "default" settings in an order set on ordering habits. This study set out to quantify the effect of changing the default settings of an order set. For quality improvement purposes, order sets dealing with transfusions were recently reviewed and modified to improve monitoring of outcome. Initially, the order for posttransfusion hematocrits and platelet count had the default setting changed from "optional" to "preselected." The default settings for platelet count was later changed back to "optional," allowing for a natural experiment to study the effect of the default selections of an order set on clinician ordering habits. Posttransfusion hematocrit values were ordered for 8.3% of red cell transfusions when the default order set selection was "off" and for 57.4% of transfusions when the default selection was "preselected" (P default order set selection was "optional," increased to 59.4% when the default was changed to "preselected" (P default selection was returned to "optional." The posttransfusion platelet count rates during the two "optional" periods: 7.0% versus 7.5% - were not statistically different (P = 0.620). Default settings in CPOE order sets can significantly influence physician selection of

Bioinspired Nanocomposite Hydrogels with Highly Ordered Structures.

Science.gov (United States)

Zhao, Ziguang; Fang, Ruochen; Rong, Qinfeng; Liu, Mingjie

2017-12-01

In the human body, many soft tissues with hierarchically ordered composite structures, such as cartilage, skeletal muscle, the corneas, and blood vessels, exhibit highly anisotropic mechanical strength and functionality to adapt to complex environments. In artificial soft materials, hydrogels are analogous to these biological soft tissues due to their "soft and wet" properties, their biocompatibility, and their elastic performance. However, conventional hydrogel materials with unordered homogeneous structures inevitably lack high mechanical properties and anisotropic functional performances; thus, their further application is limited. Inspired by biological soft tissues with well-ordered structures, researchers have increasingly investigated highly ordered nanocomposite hydrogels as functional biological engineering soft materials with unique mechanical, optical, and biological properties. These hydrogels incorporate long-range ordered nanocomposite structures within hydrogel network matrixes. Here, the critical design criteria and the state-of-the-art fabrication strategies of nanocomposite hydrogels with highly ordered structures are systemically reviewed. Then, recent progress in applications in the fields of soft actuators, tissue engineering, and sensors is highlighted. The future development and prospective application of highly ordered nanocomposite hydrogels are also discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lunar Reconnaissance Orbiter Camera (LROC) instrument overview

Science.gov (United States)

Robinson, M.S.; Brylow, S.M.; Tschimmel, M.; Humm, D.; Lawrence, S.J.; Thomas, P.C.; Denevi, B.W.; Bowman-Cisneros, E.; Zerr, J.; Ravine, M.A.; Caplinger, M.A.; Ghaemi, F.T.; Schaffner, J.A.; Malin, M.C.; Mahanti, P.; Bartels, A.; Anderson, J.; Tran, T.N.; Eliason, E.M.; McEwen, A.S.; Turtle, E.; Jolliff, B.L.; Hiesinger, H.

2010-01-01

The Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) and Narrow Angle Cameras (NACs) are on the NASA Lunar Reconnaissance Orbiter (LRO). The WAC is a 7-color push-frame camera (100 and 400 m/pixel visible and UV, respectively), while the two NACs are monochrome narrow-angle linescan imagers (0.5 m/pixel). The primary mission of LRO is to obtain measurements of the Moon that will enable future lunar human exploration. The overarching goals of the LROC investigation include landing site identification and certification, mapping of permanently polar shadowed and sunlit regions, meter-scale mapping of polar regions, global multispectral imaging, a global morphology base map, characterization of regolith properties, and determination of current impact hazards.

Free piston linear generator in comparison to other range-extender technologies

OpenAIRE

Virsik, Roman; Heron, Alex

2013-01-01

The free piston linear generator is a new range-extender technology. It converts chemical energy into electrical energy by means of a combustion process and linear generator. Thereby the technology aims to have better properties than other range extenders. Therefore this publication deals with the explanation of the concept and the characteristics of a free piston linear generator and a comparison to other technologies. In order to compare the range extender systems, fuel cells, micro gas tur...

Perturbation theory for short-range weakly-attractive potentials in one dimension

Energy Technology Data Exchange (ETDEWEB)

Amore, Paolo, E-mail: paolo.amore@gmail.com [Facultad de Ciencias, CUICBAS, Universidad de Colima, Bernal Díaz del Castillo 340, Colima, Colima (Mexico); Fernández, Francisco M., E-mail: fernande@quimica.unlp.edu.ar [INIFTA (UNLP, CONICET), Division Química Teórica, Blvd. 113 S/N, Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina)

2017-03-15

We have obtained the perturbative expressions up to sixth order for the energy of the bound state in a one dimensional, arbitrarily weak, short range finite well, applying a method originally developed by Gat and Rosenstein Ref. [1]. The expressions up to fifth order reproduce the results already known in the literature, while the sixth order had not been calculated before. As an illustration of our formulas we have applied them to two exactly solvable problems and to a nontrivial problem.

High-temperature absorbed dose measurements in the megagray range

International Nuclear Information System (INIS)

Balian, P.; Ardonceau, J.; Zuppiroli, L.

1988-01-01

Organic conductors of the tetraselenotetracene family have been tested as ''high-temperature'' absorbed dose dosimeters. They were heated up to 120 0 C and irradiated at this temperature with 1-MeV electrons in order to simulate, in a short time, a much longer γ-ray irradiation. The electric resistance increase of the crystal can be considered a good measurement of the absorbed dose in the range 10 6 Gy to a few 10 8 Gy and presumably one order of magnitude more. This dosimeter also permits on-line (in-situ) measurements of the absorbed dose without removing the sensor from the irradiation site. The respective advantages of organic and inorganic dosimeters at these temperature and dose ranges are also discussed. In this connection, we outline new, but negative, results concerning the possible use of silica as a high-temperature, high-dose dosimeter. (author)

High-order nonlinear optical processes in ablated carbon-containing materials: Recent approaches in development of the nonlinear spectroscopy using harmonic generation in the extreme ultraviolet range

Science.gov (United States)

Ganeev, R. A.

2017-08-01

The nonlinear spectroscopy using harmonic generation in the extreme ultraviolet range became a versatile tool for the analysis of the optical, structural and morphological properties of matter. The carbon-contained materials have shown the advanced properties among other studied species, which allowed both the definition of the role of structural properties on the nonlinear optical response and the analysis of the fundamental features of carbon as the attractive material for generation of coherent short-wavelength radiation. We review the studies of the high-order harmonic generation by focusing ultrashort pulses into the plasmas produced during laser ablation of various organic compounds. We discuss the role of ionic transitions of ablated carbon-containing molecules on the harmonic yield. We also show the similarities and distinctions of the harmonic and plasma spectra of organic compounds and graphite. We discuss the studies of the generation of harmonics up to the 27th order (λ = 29.9 nm) of 806 nm radiation in the boron carbide plasma and analyze the advantages and disadvantages of this target compared with the ingredients comprising B4C (solid boron and graphite) by comparing plasma emission and harmonic spectra from three species. We also show that the coincidence of harmonic and plasma emission wavelengths in most cases does not cause the enhancement or decrease of the conversion efficiency of this harmonic.

Structural and Mechanical Hysteresis at the Order-Order Transition of Block Copolymer Micellar Crystals

Directory of Open Access Journals (Sweden)

Theresa A. LaFollette

2011-01-01

Full Text Available Concentrated solutions of a water-soluble block copolymer (PEO20-(PPO70-(PEO20 show a thermoreversible transition from a liquid to a gel. Over a range of concentration there also exists an order-order transition (OOT between cubically-packed spherical micelles and hexagonally-packed cylindrical micelles. This OOT displays a hysteresis between the heating and cooling transitions that is observed at both the macroscale through rheology and nanoscale through small angle neutron scattering (SANS. The hysteresis is caused by the persistence of the cubically-packed spherical micelle phase into the hexagonally-packed cylindrical micelle phase likely due to the hindered realignment of the spherical micelles into cylindrical micelles and then packing of the cylindrical micelles into a hexagonally-packed cylindrical micelle phase. This type of hysteresis must be fully characterized, and possibly avoided, for these block copolymer systems to be used as templates in nanocomposites.

Higher-order Skyrme hair of black holes

Science.gov (United States)

Gudnason, Sven Bjarke; Nitta, Muneto

2018-05-01

Higher-order derivative terms are considered as replacement for the Skyrme term in an Einstein-Skyrme-like model in order to pinpoint which properties are necessary for a black hole to possess stable static scalar hair. We find two new models able to support stable black hole hair in the limit of the Skyrme term being turned off. They contain 8 and 12 derivatives, respectively, and are roughly the Skyrme-term squared and the so-called BPS-Skyrme-term squared. In the twelfth-order model we find that the lower branches, which are normally unstable, become stable in the limit where the Skyrme term is turned off. We check this claim with a linear stability analysis. Finally, we find for a certain range of the gravitational coupling and horizon radius, that the twelfth-order model contains 4 solutions as opposed to 2. More surprisingly, the lowest part of the would-be unstable branch turns out to be the stable one of the 4 solutions.

Summary of the results from the lunar orbiter laser altimeter after seven years in lunar orbit

Science.gov (United States)

Smith, David E.; Zuber, Maria T.; Neumann, Gregory A.; Mazarico, Erwan; Lemoine, Frank G.; Head, James W., III; Lucey, Paul G.; Aharonson, Oded; Robinson, Mark S.; Sun, Xiaoli; Torrence, Mark H.; Barker, Michael K.; Oberst, Juergen; Duxbury, Thomas C.; Mao, Dandan; Barnouin, Olivier S.; Jha, Kopal; Rowlands, David D.; Goossens, Sander; Baker, David; Bauer, Sven; Gläser, Philipp; Lemelin, Myriam; Rosenburg, Margaret; Sori, Michael M.; Whitten, Jennifer; Mcclanahan, Timothy

2017-02-01

In June 2009 the Lunar Reconnaissance Orbiter (LRO) spacecraft was launched to the Moon. The payload consists of 7 science instruments selected to characterize sites for future robotic and human missions. Among them, the Lunar Orbiter Laser Altimeter (LOLA) was designed to obtain altimetry, surface roughness, and reflectance measurements. The primary phase of lunar exploration lasted one year, following a 3-month commissioning phase. On completion of its exploration objectives, the LRO mission transitioned to a science mission. After 7 years in lunar orbit, the LOLA instrument continues to map the lunar surface. The LOLA dataset is one of the foundational datasets acquired by the various LRO instruments. LOLA provided a high-accuracy global geodetic reference frame to which past, present and future lunar observations can be referenced. It also obtained high-resolution and accurate global topography that were used to determine regions in permanent shadow at the lunar poles. LOLA further contributed to the study of polar volatiles through its unique measurement of surface brightness at zero phase, which revealed anomalies in several polar craters that may indicate the presence of water ice. In this paper, we describe the many LOLA accomplishments to date and its contribution to lunar and planetary science.

Summary of the Results from the Lunar Orbiter Laser Altimeter after Seven Years in Lunar Orbit

Science.gov (United States)

Smith, David E.; Zuber, Maria T.; Neumann, Gregory A.; Mazarico, Erwan; Lemoine, Frank G.; Head, James W., III; Lucey, Paul G.; Aharonson, Oded; Robinson, Mark S.; Sun, Xiaoli;

Parametric study of the fractional-order Chen-Lee system

International Nuclear Information System (INIS)

Tam, L.M.; Tou, W.M.S.

2008-01-01

The dynamics of fractional-order systems have attracted a great deal of attention in recent years. In this paper, the effects of parameter changes on the dynamics of the fractional-order Chen-Lee system were studied numerically. The parameter ranges used were relatively broad. The order used for the system was fixed at 2.7 (q 1 = q 2 = q 3 = 0.9). The system displays rich dynamic behaviors, such as a fixed point, periodic motion (including period-3 motion), chaotic motion, and transient chaos. The chaotic motion identified was validated by the confirmation of a positive Lyapunov exponent. Period-doubling routes to chaos in the fractional-order Chen-Lee system were also found

Parametric study of the fractional-order Chen-Lee system

Energy Technology Data Exchange (ETDEWEB)

Tam, L.M. [Department of Electromechanical Engineering, Faculty of Science and Technology, University of Macau, Av. Padre Tomas Pereira S.J., Taipa, Macau (China)], E-mail: fstlmt@umac.mo; Tou, W.M.S. [Department of Electromechanical Engineering, Faculty of Science and Technology, University of Macau, Av. Padre Tomas Pereira S.J., Taipa, Macau (China)

2008-08-15

The dynamics of fractional-order systems have attracted a great deal of attention in recent years. In this paper, the effects of parameter changes on the dynamics of the fractional-order Chen-Lee system were studied numerically. The parameter ranges used were relatively broad. The order used for the system was fixed at 2.7 (q{sub 1} = q{sub 2} = q{sub 3} = 0.9). The system displays rich dynamic behaviors, such as a fixed point, periodic motion (including period-3 motion), chaotic motion, and transient chaos. The chaotic motion identified was validated by the confirmation of a positive Lyapunov exponent. Period-doubling routes to chaos in the fractional-order Chen-Lee system were also found.

Generalized Bragg-Williams model for the size-dependent order-disorder transition of bimetallic nanoparticles

International Nuclear Information System (INIS)

Li, Y J; Qi, W H; Wang, M P; Liu, J F; Xiong, S Y; Huang, B Y

2011-01-01

Considering the different effects of exterior atoms (face, edge and corner atoms), the Bragg-Williams model is generalized to account for the size, shape and composition-dependent order-disorder transition of bimetallic nanoparticles (NPs) with B 2 , L1 0 and L1 2 ordered structures. The results show that the order-disorder temperatures T C,p are different for different shapes even in the identical particle size. The order of order-disorder temperatures of different shapes varies for different sizes. The long-range order parameter decreases with the increase in temperature in all size ranges and decreases smoothly in large sizes, but drops dramatically in small sizes. Moreover, it is also found that the order-disorder temperature of bimetallic NPs rises with increasing particle sizes and decreases with a deviation from the ideal compositions. The present predictions are consistent with the available literature results, indicating its capability in predicting other order-disorder transition phenomena of bimetallic NPs.

Order parameter fluctuations and collective modes in superconductors

International Nuclear Information System (INIS)

Carlson, R.V.

1975-06-01

Measurements of the frequency and wave vector dependence of the pair-field susceptibility and the dynamical structure factor of homogeneous, short mean free path aluminum films have been carried out. These measurements critically probe the dynamical nature of order parameter fluctuations in the vicinity of the superconducting phase transition. Two important results are found. The first is that at temperatures higher than the transition temperature of the aluminum film, the fluctuations of the order parameter can be described by a diffusive time-dependent generalization of the Ginzburg-Landau equation. Detailed comparison of the data to the results of theoretical calculations of Scalapino, and Shenoy and Lee is carried out. Except in the immediate vicinity of the transition, there is excellent agreement with the theories. A major discrepancy between theory and experiment does exist in the vicinity of the superconducting transition, in that the pair relaxation frequency falls well below the theoretical predictions. Possible explanations of this behavior are discussed. Below the transition temperature measurements of the structure factor (Fourier transform of the order parameter-order parameter correlation function) provide the first clear cut demonstration of the existence of a propagating, low frequency, order parameter collective mode which appears as a finite frequency peak in the structure factor. This mode has been identified with fluctuations in the phase of the order parameter and has a linear dispersion relation over the range in which it is observed. A detailed comparison to some of the theoretical explanations is made, with the conclusion that at this time, existing theories do not adequately explain the behavior of the mode over the range of temperature and magnetic field in which it is observed. (4 figures, 4 tables, 86 references) (U.S.)

A short-range ensemble prediction system for southern Africa

CSIR Research Space (South Africa)

Park, R

2012-10-01

Full Text Available system for southern Africa R PARK, WA LANDMAN AND F ENGELBRECHT CSIR, PO Box 395, Pretoria, South Africa, 0001 Email: xxxxxxxxxxxxxx@csir.co.za ? www.csir.co.za INTRODUCTION This research has been conducted in order to develop a short-range ensemble... stream_source_info Park_2012.pdf.txt stream_content_type text/plain stream_size 7211 Content-Encoding ISO-8859-1 stream_name Park_2012.pdf.txt Content-Type text/plain; charset=ISO-8859-1 A short-range ensemble prediction...

Memory and long-range correlations in chess games

Science.gov (United States)

Schaigorodsky, Ana L.; Perotti, Juan I.; Billoni, Orlando V.

2014-01-01

In this paper we report the existence of long-range memory in the opening moves of a chronologically ordered set of chess games using an extensive chess database. We used two mapping rules to build discrete time series and analyzed them using two methods for detecting long-range correlations; rescaled range analysis and detrended fluctuation analysis. We found that long-range memory is related to the level of the players. When the database is filtered according to player levels we found differences in the persistence of the different subsets. For high level players, correlations are stronger at long time scales; whereas in intermediate and low level players they reach the maximum value at shorter time scales. This can be interpreted as a signature of the different strategies used by players with different levels of expertise. These results are robust against the assignation rules and the method employed in the analysis of the time series.

Alternative separation of exchange and correlation energies in range-separated density-functional perturbation theory

DEFF Research Database (Denmark)

Cornaton, Y.; Stoyanova, A.; Jensen, Hans Jørgen Aagaard

2013-01-01

of the noninteracting Kohn-Sham one. When second-order corrections to the density are neglected, the energy expression reduces to a range-separated double-hybrid (RSDH) type of functional, RSDHf, where "f" stands for "full-range integrals" as the regular full-range interaction appears explicitly in the energy...

Buckling instability in ordered bacterial colonies

Science.gov (United States)

Boyer, Denis; Mather, William; Mondragón-Palomino, Octavio; Orozco-Fuentes, Sirio; Danino, Tal; Hasty, Jeff; Tsimring, Lev S.

2011-04-01

Bacterial colonies often exhibit complex spatio-temporal organization. This collective behavior is affected by a multitude of factors ranging from the properties of individual cells (shape, motility, membrane structure) to chemotaxis and other means of cell-cell communication. One of the important but often overlooked mechanisms of spatio-temporal organization is direct mechanical contact among cells in dense colonies such as biofilms. While in natural habitats all these different mechanisms and factors act in concert, one can use laboratory cell cultures to study certain mechanisms in isolation. Recent work demonstrated that growth and ensuing expansion flow of rod-like bacteria Escherichia coli in confined environments leads to orientation of cells along the flow direction and thus to ordering of cells. However, the cell orientational ordering remained imperfect. In this paper we study one mechanism responsible for the persistence of disorder in growing cell populations. We demonstrate experimentally that a growing colony of nematically ordered cells is prone to the buckling instability. Our theoretical analysis and discrete-element simulations suggest that the nature of this instability is related to the anisotropy of the stress tensor in the ordered cell colony.

Buckling instability in ordered bacterial colonies

International Nuclear Information System (INIS)

Boyer, Denis; Mather, William; Mondragón-Palomino, Octavio; Danino, Tal; Hasty, Jeff; Orozco-Fuentes, Sirio; Tsimring, Lev S

2011-01-01

Bacterial colonies often exhibit complex spatio-temporal organization. This collective behavior is affected by a multitude of factors ranging from the properties of individual cells (shape, motility, membrane structure) to chemotaxis and other means of cell–cell communication. One of the important but often overlooked mechanisms of spatio-temporal organization is direct mechanical contact among cells in dense colonies such as biofilms. While in natural habitats all these different mechanisms and factors act in concert, one can use laboratory cell cultures to study certain mechanisms in isolation. Recent work demonstrated that growth and ensuing expansion flow of rod-like bacteria Escherichia coli in confined environments leads to orientation of cells along the flow direction and thus to ordering of cells. However, the cell orientational ordering remained imperfect. In this paper we study one mechanism responsible for the persistence of disorder in growing cell populations. We demonstrate experimentally that a growing colony of nematically ordered cells is prone to the buckling instability. Our theoretical analysis and discrete-element simulations suggest that the nature of this instability is related to the anisotropy of the stress tensor in the ordered cell colony

Chemical bonding and structural ordering of cations in silicate glasses

International Nuclear Information System (INIS)

Calas, G.; Cormier, L.; Galoisy, L.; Ramos, A.; Rossano, St.

1997-01-01

The specific surrounding of cations in multicomponent silicate glasses is briefly presented. Information about interatomic distances and site geometry may be gained by using spectroscopic methods among which x-ray absorption spectroscopy may be used for the largest number of glass components. Scattering of x-rays and neutrons may also be used to determine the importance of medium range order around specific cations. All the existing data show that cations occur in sites with a well-defined geometry, which are in most cases connected to the silicate polymeric network. Medium range order has been detected around cations such as Ti, Ca and Ni, indicating that these elements have an heterogeneous distribution within the glassy matrix. (authors)

Research on long-range grating interferometry with nanometer resolution

International Nuclear Information System (INIS)

Chu, Xingchun; Zhao, Shanghong; Lü, Haibao

2008-01-01

Grating interferometry that features long range and nanometer resolution is presented. The optical system was established based on a single long metrology grating. The large fringe multiplication was achieved by properly selecting two high-order diffraction beams to form a fringe pattern. The fringe pattern collected by a linear array was first tailored to a few multiples of fringes in order to suppress the effect of the energy leakage on phase-extracting precision when the fast Fourier transform (FFT) algorithm was used to calculate its phase. Thus, the phase-extracting precision of a tailored fringe pattern by FFT was greatly improved. Based on this, a novel subdividing method, which exploited the time-shift property of FFT, was developed to subdivide the fringe with large multiple and high accuracy. Numerical results show that the system resolution reaches 1 nm. The experimental results obtained against a capacitive sensor in the sub-mm range show that the measurement precision of the system is less than 10 nm. (technical design note)

Order-fractal transitions in abstract paintings

Energy Technology Data Exchange (ETDEWEB)

Calleja, E.M. de la, E-mail: elsama79@gmail.com [Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, 91501-970, Porto Alegre, RS (Brazil); Cervantes, F. [Department of Applied Physics, CINVESTAV-IPN, Carr. Antigua a Progreso km.6, Cordemex, C.P.97310, Mérida, Yucatán (Mexico); Calleja, J. de la [Department of Informatics, Universidad Politécnica de Puebla, 72640 (Mexico)

2016-08-15

In this study, we determined the degree of order for 22 Jackson Pollock paintings using the Hausdorff–Besicovitch fractal dimension. Based on the maximum value of each multi-fractal spectrum, the artworks were classified according to the year in which they were painted. It has been reported that Pollock’s paintings are fractal and that this feature was more evident in his later works. However, our results show that the fractal dimension of these paintings ranges among values close to two. We characterize this behavior as a fractal-order transition. Based on the study of disorder-order transition in physical systems, we interpreted the fractal-order transition via the dark paint strokes in Pollock’s paintings as structured lines that follow a power law measured by the fractal dimension. We determined self-similarity in specific paintings, thereby demonstrating an important dependence on the scale of observations. We also characterized the fractal spectrum for the painting entitled Teri’s Find. We obtained similar spectra for Teri’s Find and Number 5, thereby suggesting that the fractal dimension cannot be rejected completely as a quantitative parameter for authenticating these artworks. -- Highlights: •We determined the degree of order in Jackson Pollock paintings using the Hausdorff–Besicovitch dimension. •We detected a fractal-order transition from Pollock’s paintings between 1947 and 1951. •We suggest that Jackson Pollock could have painted Teri’s Find.

Microstructure of ordered (Co078Fe022)3V alloy

International Nuclear Information System (INIS)

Braski, D.N.; Carpenter, R.W.; Bentley, J.

1981-05-01

The (Co 0 78 Fe 0 22 ) 3 V alloy belongs to a class of long-range-ordered alloys that are being developed for elevated-temperature applications. The microstructure after quenching and after subsequent aging at temperatures between 973 and 1073 0 K has been characterized by analytical electron microscopy. Short-range order (SRO) and small VC matrix precipitate particles were observed in the as-quenched material. At 973 0 K VC precipitated discontinuously in grain boundaries and on extrinsic stacking faults. Aging at 1073 0 K precipitated VC in grain boundaries and on extrinsic stacking faults, and produced intrinsic stacking faults that were precipitate-free. Ordered domains grew upon aging at rates proportional to t/sup 1/2/; the activation energy for growth was 222 +- 20 J/mol. Thermal antiphase boundaries (APBs) had isotropic energies and (a/2) displacement vectors. Intrinsic and extrinsic stacking faults also serve as APBs, with displacement vectors of (a/6) and (a/3) , respectively

Reduced-Order Computational Model for Low-Frequency Dynamics of Automobiles

Directory of Open Access Journals (Sweden)

A. Arnoux

2013-01-01

Full Text Available A reduced-order model is constructed to predict, for the low-frequency range, the dynamical responses in the stiff parts of an automobile constituted of stiff and flexible parts. The vehicle has then many elastic modes in this range due to the presence of many flexible parts and equipment. A nonusual reduced-order model is introduced. The family of the elastic modes is not used and is replaced by an adapted vector basis of the admissible space of global displacements. Such a construction requires a decomposition of the domain of the structure in subdomains in order to control the spatial wave length of the global displacements. The fast marching method is used to carry out the subdomain decomposition. A probabilistic model of uncertainties is introduced. The parameters controlling the level of uncertainties are estimated solving a statistical inverse problem. The methodology is validated with a large computational model of an automobile.

On the Origin of Charge Order in RuCl3

Science.gov (United States)

Berlijn, Tom

RuCl3 has been proposed to be a spin-orbit assisted Mott insulator close to the Kitaev-spin-liquid ground state, an exotic state of matter that could protect information in quantum computers. Recent STM experiments [M. Ziatdinov et al, Nature Communications (in press)] however, show the presence of a puzzling short-range charge order in this quasi two dimensional material. Understanding the nature of this charge order may provide a pathway towards tuning RuCl3 into the Kitaev-spin-liquid ground state. Based on first principles calculations I investigate the possibility that the observed charge order is caused by a combination of short-range magnetic correlations and strong spin-orbit coupling. From a general perspective such a mechanism could offer the exciting possibility of probing local magnetic correlations with standard STM. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

Assessing Influences on Perceived Training Transfer: An Investigation of Perceptions of Air Force Logistics Readiness Officer Technical School Graduates

National Research Council Canada - National Science Library

Hobbs, Sarah E

2005-01-01

.... This research specifically investigates how influences/attitudes/beliefs of LRO technical school graduates regarding their training influence their perceptions about the transfer of such training back to the job...

Fast long-range connections in transportation networks

International Nuclear Information System (INIS)

Palhares Viana, Matheus; Fontoura Costa, Luciano da

2011-01-01

Multidimensional scaling is applied in order to visualize an analogue of the small-world effect implied by edges having different displacement velocities in transportation networks. Our findings are illustrated for two real-world systems, namely the London urban network (streets and underground) and the US highway network enhanced by some of the main US airlines routes. We also show that the travel time in these two networks is drastically changed by attacks targeting the edges with large displacement velocities. - Highlights: → Multidimensional scaling used to visualize the effects of fast long-range connections. → Fast long-range connections are important to decrease the average travel time. → The average travel time diverges quickly when the network is under target attacks.

Linear models of coregionalization for multivariate lattice data: Order-dependent and order-free cMCARs.

Science.gov (United States)

MacNab, Ying C

2016-08-01

This paper concerns with multivariate conditional autoregressive models defined by linear combination of independent or correlated underlying spatial processes. Known as linear models of coregionalization, the method offers a systematic and unified approach for formulating multivariate extensions to a broad range of univariate conditional autoregressive models. The resulting multivariate spatial models represent classes of coregionalized multivariate conditional autoregressive models that enable flexible modelling of multivariate spatial interactions, yielding coregionalization models with symmetric or asymmetric cross-covariances of different spatial variation and smoothness. In the context of multivariate disease mapping, for example, they facilitate borrowing strength both over space and cross variables, allowing for more flexible multivariate spatial smoothing. Specifically, we present a broadened coregionalization framework to include order-dependent, order-free, and order-robust multivariate models; a new class of order-free coregionalized multivariate conditional autoregressives is introduced. We tackle computational challenges and present solutions that are integral for Bayesian analysis of these models. We also discuss two ways of computing deviance information criterion for comparison among competing hierarchical models with or without unidentifiable prior parameters. The models and related methodology are developed in the broad context of modelling multivariate data on spatial lattice and illustrated in the context of multivariate disease mapping. The coregionalization framework and related methods also present a general approach for building spatially structured cross-covariance functions for multivariate geostatistics. © The Author(s) 2016.

Maintaining Limited-Range Connectivity Among Second-Order Agents

Science.gov (United States)

2016-07-07

we consider ad-hoc networks of robotic agents with double integrator dynamics. For such networks, the connectivity maintenance problems are: (i) do...connectivity-maintaining controls in a distributed fashion? The proposed solution is based on three contributions. First, we define and characterize...hoc networks of mobile autonomous agents. This loose ter- minology refers to groups of robotic agents with limited mobility and communica- tion

Ranging behavior relates to welfare indicators pre- and post-range access in commercial free-range broilers.

Science.gov (United States)

Taylor, Peta S; Hemsworth, Paul H; Groves, Peter J; Gebhardt-Henrich, Sabine G; Rault, Jean-Loup

2018-06-01

Little is known about the effect of accessing an outdoor range on chicken welfare. We tracked individual ranging behavior of 538 mixed-sex Ross 308 chickens on a commercial farm across 4 flocks in winter and summer. Before range access, at 17 to 19 d of age, and post-range access, at 30 to 33 and 42 to 46 d of age in winter and summer flocks respectively, welfare indicators were measured on chickens (pre-range: winter N = 292; summer N = 280; post-range: winter N = 131; summer N = 140), including weight, gait score, dermatitis and plumage condition. Post-ranging autopsies were performed (winter: N = 170; summer: N = 60) to assess breast burn, leg health, and ascites. Fewer chickens accessed the range in winter flocks (32.5%) than summer flocks (82.1%). Few relationships between welfare and ranging were identified in winter, likely due to minimal ranging and the earlier age of post-ranging data collection compared to summer flocks. In summer flocks prior to range access, chickens that accessed the range weighed 4.9% less (P = 0.03) than chickens that did not access the range. Pre-ranging weight, gait score, and overall plumage cover predicted the amount of range use by ranging chickens in summer flocks (P ranging behavior. In summer flocks post-range access, ranging chickens weighed 12.8% less than non-ranging chickens (P range visits were associated with lower weight (P range was associated with lower weight (P range in summer is partly related to changes in broiler chicken welfare. Further investigations are required to determine causation.

A high performance totally ordered multicast protocol

Science.gov (United States)

Montgomery, Todd; Whetten, Brian; Kaplan, Simon

1995-01-01

This paper presents the Reliable Multicast Protocol (RMP). RMP provides a totally ordered, reliable, atomic multicast service on top of an unreliable multicast datagram service such as IP Multicasting. RMP is fully and symmetrically distributed so that no site bears un undue portion of the communication load. RMP provides a wide range of guarantees, from unreliable delivery to totally ordered delivery, to K-resilient, majority resilient, and totally resilient atomic delivery. These QoS guarantees are selectable on a per packet basis. RMP provides many communication options, including virtual synchrony, a publisher/subscriber model of message delivery, an implicit naming service, mutually exclusive handlers for messages, and mutually exclusive locks. It has commonly been held that a large performance penalty must be paid in order to implement total ordering -- RMP discounts this. On SparcStation 10's on a 1250 KB/sec Ethernet, RMP provides totally ordered packet delivery to one destination at 842 KB/sec throughput and with 3.1 ms packet latency. The performance stays roughly constant independent of the number of destinations. For two or more destinations on a LAN, RMP provides higher throughput than any protocol that does not use multicast or broadcast.

Relation between birth order and interpersonal styles

Directory of Open Access Journals (Sweden)

Mauro de Oliveira Magalhães

2009-10-01

Full Text Available Interpersonal style is an aspect of personality related to the particular way individuals participate and gain influence in social contexts. It has its origin in childhood’s first social interactions within the family group. It is suggested that the individual position in the family structure, namely birth order, is an important variable in this process. The present study investigated combined effects of sex and birth order on interpersonal style. A sample of 435 college students (196 men and 239 women with ranging in age from 18 to 40 years (M = 23,3 answered the BASIS-A (Basic Adlerian Scales of Interpersonal Styles and a brief demographic questionnaire. Interactions between sex and birth order were found. Lastborn women showed greater tendency to search for success and social approval than firstborn women and lastborn men. Among men, lastborn revealed less need for social approval compared to firstborn and only children. First born men showed a higher need to attend social conventions and obtain success. The interaction between sex and birth order was relevant for the understanding of personality development in the context of family relations.   Keywords: birth order; interpersonal styles; personality.

Short-range correlations in an extended time-dependent mean-field theory

International Nuclear Information System (INIS)

Madler, P.

1982-01-01

A generalization is performed of the time-dependent mean-field theory by an explicit inclusion of strong short-range correlations on a level of microscopic reversibility relating them to realistic nucleon-nucleon forces. Invoking a least action principle for correlated trial wave functions, equations of motion for the correlation functions and the single-particle model wave function are derived in lowest order of the FAHT cluster expansion. Higher order effects as well as long-range correlations are consider only to the extent to which they contribute to the mean field via a readjusted phenomenological effective two-body interaction. The corresponding correlated stationary problem is investigated and appropriate initial conditions to describe a heavy ion reaction are proposed. The singleparticle density matrix is evaluated

Ordering due to disorder in frustrated quantum magnetic system

International Nuclear Information System (INIS)

Yildirim, T.

1999-01-01

The phenomenon of order by disorder in frustrated magnetic systems is reviewed. Disorder (thermal or quantum fluctuations) may sometimes give rise to long range ordering in systems with frustration, where one must often consider the selection among classically degenerate ground states which are not equivalent by any symmetry. The lowest order effects of quantum fluctuations in such frustrated systems usually resolves the continues degeneracy of the ground state manifold into discrete Ising-type degeneracy. A unique ground state selection out of this Ising degenerate manifold then occurs due to higher order effects of quantum fluctuations. For systems such as face-centered cubic and body-centered tetragonal antiferromagnets where the number of Ising parameters to describe the ground state manifold is not macroscopic, we show that quantum fluctuations choose a unique ground state at the first order in 1/S

Recoil range distribution measurement in 20Ne + 181Ta reaction

International Nuclear Information System (INIS)

Tripathi, R.; Sudarshan, K.; Goswami, A.; Guin, R.; Reddy, A.V.R.

2005-01-01

In order to investigate linear momentum transfer in various transfer channels in 20 Ne + 181 Ta, recoil range distribution measurements have been carried out at E lab = 180 MeV, populating significant number of l-waves above l crit

Dielectric characterization of materials at microwave frequency range

Directory of Open Access Journals (Sweden)

J. de los Santos

2003-01-01

Full Text Available In this study a coaxial line was used to connect a microwave-frequency Network Analyzer and a base moving sample holder for dielectric characterization of ferroelectric materials in the microwave range. The main innovation of the technique is the introduction of a special sample holder that eliminates the air gap effect by pressing sample using a fine pressure system control. The device was preliminary tested with alumina (Al2O3 ceramics and validated up to 2 GHz. Dielectric measurements of lanthanum and manganese modified lead titanate (PLTM ceramics were carried out in order to evaluate the technique for a high permittivity material in the microwave range. Results showed that such method is very useful for materials with high dielectric permittivities, which is generally a limiting factor of other techniques in the frequency range from 50 MHz to 2 GHz.

The Ames Vertical Gun Range

Science.gov (United States)

Karcz, J. S.; Bowling, D.; Cornelison, C.; Parrish, A.; Perez, A.; Raiche, G.; Wiens, J.-P.

2016-01-01

The Ames Vertical Gun Range (AVGR) is a national facility for conducting laboratory- scale investigations of high-speed impact processes. It provides a set of light-gas, powder, and compressed gas guns capable of accelerating projectiles to speeds up to 7 km s(exp -1). The AVGR has a unique capability to vary the angle between the projectile-launch and gravity vectors between 0 and 90 deg. The target resides in a large chamber (diameter approximately 2.5 m) that can be held at vacuum or filled with an experiment-specific atmosphere. The chamber provides a number of viewing ports and feed-throughs for data, power, and fluids. Impacts are observed via high-speed digital cameras along with investigation-specific instrumentation, such as spectrometers. Use of the range is available via grant proposals through any Planetary Science Research Program element of the NASA Research Opportunities in Space and Earth Sciences (ROSES) calls. Exploratory experiments (one to two days) are additionally possible in order to develop a new proposal.

Short-range order clustering in BCC Fe-Mn alloys induced by severe plastic deformation

Science.gov (United States)

Shabashov, V. A.; Kozlov, K. A.; Sagaradze, V. V.; Nikolaev, A. L.; Lyashkov, K. A.; Semyonkin, V. A.; Voronin, V. I.

2018-03-01

The effect of severe plastic deformation, namely, high-pressure torsion (HPT) at different temperatures and ball milling (BM) at different time intervals, has been investigated by means of Mössbauer spectroscopy in Fe100-xMnx (x = 4.1, 6.8, 9) alloys. Deformation affects the short-range clustering (SRC) in BCC lattice. Two processes occur: destruction of SRC by moving dislocations and enhancement of the SRC by migration of non-equilibrium defects. Destruction of SRC prevails during HPT at 80-293 K; whereas enhancement of SRC dominates at 473-573 K. BM starts enhancing the SRC formation at as low as 293 K due to local heating at impacts. The efficiency of HPT in terms of enhancing SRC increases with increasing temperature. The authors suppose that at low temperatures, a significant fraction of vacancies are excluded from enhancing SRC because of formation of mobile bi- and tri-vacancies having low efficiency of enhancing SRC as compared to that of mono vacancies. Milling of BCC Fe100-xMnx alloys stabilises the BCC phase with respect to α → γ transition at subsequent isothermal annealing because of a high degree of work hardening and formation of composition inhomogeneity.

On the Fluctuations that Order and Frustrate Liquid Water

OpenAIRE

Limmer, David

2013-01-01

At ambient conditions, water sits close to phase coexistence with its crystal. More so than in many other materials, this fact is manifested in the fluctuations that maintain a large degree of local order in the liquid. These fluctuations and how they result in long-ranged order, or its absence, are emergent features of many interacting molecules. Their study therefore requires using the tools of statistical mechanics for their their systematic understanding. In this dissertation we develop s...

Cosmological perturbation theory at three-loop order

Energy Technology Data Exchange (ETDEWEB)

Blas, Diego [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Garny, Mathias; Konstandin, Thomas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2013-09-15

We analyze the dark matter power spectrum at three-loop order in standard perturbation theory of large scale structure. We observe that at late times the loop expansion does not converge even for large scales (small momenta) well within the linear regime, but exhibits properties compatible with an asymptotic series. We propose a technique to restore the convergence in the limit of small momentum, and use it to obtain a perturbative expansion with improved convergence for momenta in the range where baryonic acoustic oscillations are present. Our results are compared with data from N-body simulations at different redshifts, and we find good agreement within this range.

Cosmological perturbation theory at three-loop order

International Nuclear Information System (INIS)

Blas, Diego; Garny, Mathias; Konstandin, Thomas

2013-09-01

We analyze the dark matter power spectrum at three-loop order in standard perturbation theory of large scale structure. We observe that at late times the loop expansion does not converge even for large scales (small momenta) well within the linear regime, but exhibits properties compatible with an asymptotic series. We propose a technique to restore the convergence in the limit of small momentum, and use it to obtain a perturbative expansion with improved convergence for momenta in the range where baryonic acoustic oscillations are present. Our results are compared with data from N-body simulations at different redshifts, and we find good agreement within this range.

Wind energy and electricity prices. Exploring the 'merit order effect'

International Nuclear Information System (INIS)

Morthost, P.E.; Ray, S.; Munksgaard, J.; Sinner, A.F.

2010-04-01

This report focuses on the effect of wind energy on the electricity price in the power market. As the report will discuss, adding wind into the power mix has a significant influence on the resulting price of electricity, the so called merit order effect (MOE). The merit order effect has been quantified and discussed in many scientific publications. This report ends the first phase of a study on the MOE, evaluating the impact of EWEA's 2020 scenarios on future European electricity prices. The basic principles of the merit order effect are provided in the first part of the document. The literature review itself contains methods and tools not only to quantify the merit order effect but also in order to forecast its future range and volume.

A dynamic range upgrade for neutron backscattering spectroscopy

International Nuclear Information System (INIS)

Cook, J.C.; Petry, W.; Heidemann, A.; Barthelemy, J.F.

1992-01-01

We report on an instrumental development of the cold neutron backscattering spectrometer IN10 at the Institut Laue-Langevin which has led to a significant increase in its dynamic range. Thermal expansion of a variety of neutron monochromator crystals is used instead of a mechanical oscillation of the monochromator, yielding an increase in the energy transfer range by nearly two orders of magnitude in an elastic wave vector transfer range of 0.07≤Q (A -1 )≤2.0. Using this new configuration, first inelastic measurements have been performed using the (200) reflections from KCl and NaCl monochromators with crystal temperatures between 80 K and 700 K. The thermal expansion of these crystals in this temperature range gives rise to energy transfer ranges (neutron energy gain) of -16<ℎω(μeV)<+83 for KCl and -530<ℎω(μeV)<-420 for NaCl with energy resolution (FWHM) of around 0.6 and 1.4 μeV for KCl and NaCl respectively. These figures represent the highest energy resolution currently available at these energy and wave vector transfers. (orig.)

Effective quantum theories with short- and long-range forces

International Nuclear Information System (INIS)

Koenig, Sebastian

2013-01-01

At low energies, nonrelativistic quantum systems are essentially governed by their wave functions at large distances. For this reason, it is possible to describe a wide range of phenomena with short- or even finite-range interactions. In this thesis, we discuss several topics in connection with such an effective description and consider, in particular, modifications introduced by the presence of additional long-range potentials. In the first part we derive general results for the mass (binding energy) shift of bound states with angular momentum L ≥ 1 in a periodic cubic box in two and three spatial dimensions. Our results have applications to lattice simulations of hadronic molecules, halo nuclei, and Feshbach molecules. The sign of the mass shift can be related to the symmetry properties of the state under consideration. We verify our analytical results with explicit numerical calculations. Moreover, we discuss the case of twisted boundary conditions that arise when one considers moving bound states in finite boxes. The corresponding finite-volume shifts in the binding energies play an important role in the study of composite-particle scattering on the lattice, where they give rise to topological correction factors. While the above results are derived under the assumption of a pure finite-range interaction - and are still true up to exponentially small correction in the short-range case - in the second part we consider primarily systems of charged particles, where the Coulomb force determines the long-range part of the potential. In quantum systems with short-range interactions, causality imposes nontrivial constraints on low-energy scattering parameters. We investigate these causality constraints for systems where a long-range Coulomb potential is present in addition to a short-range interaction. The main result is an upper bound for the Coulomb-modified effective range parameter. We discuss the implications of this bound to the effective feld theory (EFT) for

Development of wide range charge integration application specified integrated circuit for photo-sensor

Energy Technology Data Exchange (ETDEWEB)

Katayose, Yusaku, E-mail: katayose@ynu.ac.jp [Department of Physics, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, Kanagawa 240-8501 (Japan); Ikeda, Hirokazu [Institute of Space and Astronautical Science (ISAS)/Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Tanaka, Manobu [National Laboratory for High Energy Physics, KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Shibata, Makio [Department of Physics, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, Kanagawa 240-8501 (Japan)

2013-01-21

A front-end application specified integrated circuit (ASIC) is developed with a wide dynamic range amplifier (WDAMP) to read-out signals from a photo-sensor like a photodiode. The WDAMP ASIC consists of a charge sensitive preamplifier, four wave-shaping circuits with different amplification factors and Wilkinson-type analog-to-digital converter (ADC). To realize a wider range, the integrating capacitor in the preamplifier can be changed from 4 pF to 16 pF by a two-bit switch. The output of a preamplifier is shared by the four wave-shaping circuits with four gains of 1, 4, 16 and 64 to adapt the input range of ADC. A 0.25-μm CMOS process (of UMC electronics CO., LTD) is used to fabricate the ASIC with four-channels. The dynamic range of four orders of magnitude is achieved with the maximum range over 20 pC and the noise performance of 0.46 fC + 6.4×10{sup −4} fC/pF. -- Highlights: ► A front-end ASIC is developed with a wide dynamic range amplifier. ► The ASIC consists of a CSA, four wave-shaping circuits and pulse-height-to-time converters. ► The dynamic range of four orders of magnitude is achieved with the maximum range over 20 pC.

Numerical simulation on range of high-energy electron moving in accelerator target

International Nuclear Information System (INIS)

Shao Wencheng; Sun Punan; Dai Wenjiang

2008-01-01

In order to determine the range of high-energy electron moving in accelerator target, the range of electron with the energy range of 1 to 100 MeV moving in common target material of accelerator was calculated by Monte-Carlo method. Comparison between the calculated result and the published data were performed. The results of Monte-Carlo calculation are in good agreement with the published data. Empirical formulas were obtained for the range of high-energy electron with the energy range of 1 to 100 MeV in common target material by curve fitting, offering a series of referenced data for the design of targets in electron accelerator. (authors)

Hopf bifurcation and chaos in a third-order phase-locked loop

Science.gov (United States)

Piqueira, José Roberto C.

2017-01-01

Phase-locked loops (PLLs) are devices able to recover time signals in several engineering applications. The literature regarding their dynamical behavior is vast, specifically considering that the process of synchronization between the input signal, coming from a remote source, and the PLL local oscillation is robust. For high-frequency applications it is usual to increase the PLL order by increasing the order of the internal filter, for guarantying good transient responses; however local parameter variations imply structural instability, thus provoking a Hopf bifurcation and a route to chaos for the phase error. Here, one usual architecture for a third-order PLL is studied and a range of permitted parameters is derived, providing a rule of thumb for designers. Out of this range, a Hopf bifurcation appears and, by increasing parameters, the periodic solution originated by the Hopf bifurcation degenerates into a chaotic attractor, therefore, preventing synchronization.

Investigation of interstitial atom ordering in energetically nonequivalent positions

CERN Document Server

Tashmetov, M Y; Mukhtarova, N N

2002-01-01

By X-ray and neutron diffraction methods the ordered structures of carbon atoms in complex carbide Ti sub 1 sub - sub x V sub x C sub 0 sub . sub 6 have been investigated. The one-phase samples have been prepared with cubic structure such as NaCl (space group Fm3m) by solid-phase vacuum sintering at 2070 K. The cubic ordered structure (sp.gr. Fd3d) with double parameter of the elementary cell in comparison with the initial one was formed after annealing the samples at 873 K (80 hours). The long-range order parameter (eta) is less than maximal in the investigated samples. It is established that at 980-1000 K the cubic ordered structure (sp.gr. Fd3m) transforms to the trigonal ordered structure (sp.gr. R3m; sp.gr. P3 sub 1 21). (author)

Higher-order terms in the nuclear-energy-density functional

International Nuclear Information System (INIS)

Carlsson, B. G.; Borucki, M.; Dobaczewski, J.

2009-01-01

One of the current projects at the Department of Physics in the University of Jyvaeskylae is to explore more general forms of the Skyrme energy-density functional (EDF). The aim is to find new phenomenological terms which are sensitive to experimental data. In this context we have extended the Skyrme functional by including terms which contain higher orders of derivatives allowing for a better description of finite range effects. This was done by employing an expansion in derivatives in a spherical-tensor formalism [1] motivated by ideas of the density-matrix expansion. The resulting functionals have different number of free parameters depending on the order in derivatives and assumed symmetries, see Fig. 1. The usual Skyrme EDF is obtained as a second order expansion while we keep terms up to sixth order.(author)

Charge orders in organic charge-transfer salts

International Nuclear Information System (INIS)

Kaneko, Ryui; Valentí, Roser; Tocchio, Luca F; Becca, Federico

2017-01-01

Motivated by recent experimental suggestions of charge-order-driven ferroelectricity in organic charge-transfer salts, such as κ -(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl, we investigate magnetic and charge-ordered phases that emerge in an extended two-orbital Hubbard model on the anisotropic triangular lattice at 3/4 filling. This model takes into account the presence of two organic BEDT-TTF molecules, which form a dimer on each site of the lattice, and includes short-range intramolecular and intermolecular interactions and hoppings. By using variational wave functions and quantum Monte Carlo techniques, we find two polar states with charge disproportionation inside the dimer, hinting to ferroelectricity. These charge-ordered insulating phases are stabilized in the strongly correlated limit and their actual charge pattern is determined by the relative strength of intradimer to interdimer couplings. Our results suggest that ferroelectricity is not driven by magnetism, since these polar phases can be stabilized also without antiferromagnetic order and provide a possible microscopic explanation of the experimental observations. In addition, a conventional dimer-Mott state (with uniform density and antiferromagnetic order) and a nonpolar charge-ordered state (with charge-rich and charge-poor dimers forming a checkerboard pattern) can be stabilized in the strong-coupling regime. Finally, when electron–electron interactions are weak, metallic states appear, with either uniform charge distribution or a peculiar 12-site periodicity that generates honeycomb-like charge order. (paper)

Local order in molten Sesub(1-x)Tesub(x)

International Nuclear Information System (INIS)

Bellissent, R.; Tourand, G.

1980-04-01

In this paper a study of the short range order and of the coordination number in liquid Selenium-Tellurium systems is presented. The first part deals with neutron diffraction measurements of the structure factors of liquid Sesub(1-x)Tesub(x) in the whole concentration range, at 475 C, performed at EL3 reactor in Saclay using a 640 cell multidetector. From these data the radial distribution functions have been calculated. In a second part a structural model based on random chains for Selenium and on a quasicrystalline behavior of Tellurium is presented. For Se-rich melts it is assumed that Tellurium enters the Selenium chains by substitution. In the Te-rich range it is assumed that the local order is represented by substituted SeTe chains in a Tellurium matrix. This model provides with a good representation of the various structure factors. Moreover the coordination number for each concentration in the model has been calculated and the results are consistent with the experimental data. The 2 fold coordination of Se and the 3 valency of Te in the liquid state are emphasized and they can be associated with the metallisation of liquid Tellurium whereas Selenium remains a semiconductor

Design and analysis of fractional order seismic transducer for displacement and acceleration measurements

Science.gov (United States)

Veeraian, Parthasarathi; Gandhi, Uma; Mangalanathan, Umapathy

2018-04-01

Seismic transducers are widely used for measurement of displacement, velocity, and acceleration. This paper presents the design of seismic transducer in the fractional domain for the measurement of displacement and acceleration. The fractional order transfer function for seismic displacement and acceleration transducer are derived using Grünwald-Letnikov derivative. Frequency response analysis of fractional order seismic displacement transducer (FOSDT) and fractional order seismic acceleration transducer (FOSAT) are carried out for different damping ratio with the different fractional order, and the maximum dynamic measurement range is identified. The results demonstrate that fractional order seismic transducer has increased dynamic measurement range and less phase distortion as compared to the conventional seismic transducer even with a lower damping ratio. Time response of FOSDT and FOSAT are derived analytically in terms of Mittag-Leffler function, the effect of fractional behavior in the time domain is evaluated from the impulse and step response. The fractional order system is found to have significantly reduced overshoot as compared to the conventional transducer. The fractional order seismic transducer design proposed in this paper is illustrated with a design example for FOSDT and FOSAT. Finally, an electrical equivalent of FOSDT and FOSAT is considered, and its frequency response is found to be in close agreement with the proposed fractional order seismic transducer.

Determination of astaxanthin in Haematococcus pluvialis by first-order derivative spectrophotometry.

Science.gov (United States)

Liu, Xiao Juan; Juan, Liu Xiao; Wu, Ying Hua; Hua, Wu Ying; Zhao, Li Chao; Chao, Zhao Li; Xiao, Su Yao; Yao, Xiao Su; Zhou, Ai Mei; Mei, Zhou Ai; Liu, Xin; Xin, Liu

2011-01-01

A highly selective, convenient, and precise method, first-order derivative spectrophotometry, was applied for the determination of astaxanthin in Haematococcus pluvialis. Ethyl acetate and ethanol (1:1, v/v) were found to be the best extraction solvent tested due to their high efficiency and low toxicity compared with nine other organic solvents. Astaxanthin coexisting with chlorophyll and beta-carotene was analyzed by first-order derivative spectrophotometry in order to optimize the conditions for the determination of astaxanthin. The results show that when detected at 432 nm, the interfering substances could be eliminated. The dynamic linear range was 2.0-8.0 microg/mL, with a correlation coefficient of 0.9916. The detection threshold was 0.41 microg/mL. The RSD for the determination of astaxanthin was in the range of 0.01-0.06%; the results of recovery test were 98.1-108.0%. The statistical analysis between first-order derivative spectrophotometry and HPLC by T-testing did not exceed their critical values, revealing no significant differences between these two methods. It was proved that first-order derivative spectrophotometry is a rapid and convenient method for the determination of astaxanthin in H. pluvialis that can eliminate the negative effect resulting from the coexistence of astaxanthin with chlorophyll and beta-carotene.

Ranging Behaviour of Commercial Free-Range Laying Hens.

Science.gov (United States)

Chielo, Leonard Ikenna; Pike, Tom; Cooper, Jonathan

2016-04-26

In this study, the range use and behaviour of laying hens in commercial free-range flocks was explored. Six flocks were each visited on four separate days and data collected from their outdoor area (divided into zones based on distance from shed and available resources). These were: apron (0-10 m from shed normally without cover or other enrichments); enriched belt (10-50 m from shed where resources such as manmade cover, saplings and dust baths were provided); and outer range (beyond 50 m from shed with no cover and mainly grass pasture). Data collection consisted of counting the number of hens in each zone and recording behaviour, feather condition and nearest neighbour distance (NND) of 20 birds per zone on each visit day. In addition, we used techniques derived from ecological surveys to establish four transects perpendicular to the shed, running through the apron, enriched belt and outer range. Number of hens in each 10 m × 10 m quadrat was recorded four times per day as was the temperature and relative humidity of the outer range. On average, 12.5% of hens were found outside. Of these, 5.4% were found in the apron; 4.3% in the enriched zone; and 2.8% were in the outer range. This pattern was supported by data from quadrats, where the density of hens sharply dropped with increasing distance from shed. Consequently, NND was greatest in the outer range, least in the apron and intermediate in the enriched belt. Hens sampled in outer range and enriched belts had better feather condition than those from the apron. Standing, ground pecking, walking and foraging were the most commonly recorded activities with standing and pecking most likely to occur in the apron, and walking and foraging more common in the outer range. Use of the outer range declined with lower temperatures and increasing relative humidity, though use of apron and enriched belt was not affected by variation in these measures. These data support previous findings that outer range areas tend to be

Precision and broadband frequency swept laser source based on high-order modulation-sideband injection-locking.

Science.gov (United States)

Wei, Fang; Lu, Bin; Wang, Jian; Xu, Dan; Pan, Zhengqing; Chen, Dijun; Cai, Haiwen; Qu, Ronghui

2015-02-23

A precision and broadband laser frequency swept technique is experimentally demonstrated. Using synchronous current compensation, a slave diode laser is dynamically injection-locked to a specific high-order modulation-sideband of a narrow-linewidth master laser modulated by an electro-optic modulator (EOM), whose driven radio frequency (RF) signal can be agilely, precisely controlled by a frequency synthesizer, and the high-order modulation-sideband enables multiplied sweep range and tuning rate. By using 5th order sideband injection-locking, the original tuning range of 3 GHz and tuning rate of 0.5 THz/s is multiplied by 5 times to 15 GHz and 2.5 THz/s respectively. The slave laser has a 3 dB-linewidth of 2.5 kHz which is the same to the master laser. The settling time response of a 10 MHz frequency switching is 2.5 µs. By using higher-order modulation-sideband and optimized experiment parameters, an extended sweep range and rate could be expected.

Molecular Design of Branched and Binary Molecules at Ordered Interfaces

Energy Technology Data Exchange (ETDEWEB)

Genson, Kirsten Larson [Iowa State Univ., Ames, IA (United States)

2005-01-01

This study examined five different branched molecular architectures to discern the effect of design on the ability of molecules to form ordered structures at interfaces. Photochromic monodendrons formed kinked packing structures at the air-water interface due to the cross-sectional area mismatch created by varying number of alkyl tails and the hydrophilic polar head group. The lower generations formed orthorhombic unit cell with long range ordering despite the alkyl tails tilted to a large degree. Favorable interactions between liquid crystalline terminal groups and the underlying substrate were observed to compel a flexible carbosilane dendrimer core to form a compressed elliptical conformation which packed stagger within lamellae domains with limited short range ordering. A twelve arm binary star polymer was observed to form two dimensional micelles at the air-water interface attributed to the higher polystyrene block composition. Linear rod-coil molecules formed a multitude of packing structures at the air-water interface due to the varying composition. Tree-like rod-coil molecules demonstrated the ability to form one-dimensional structures at the air-water interface and at the air-solvent interface caused by the preferential ordering of the rigid rod cores. The role of molecular architecture and composition was examined and the influence chemically competing fragments was shown to exert on the packing structure. The amphiphilic balance of the different molecular series exhibited control on the ordering behavior at the air-water interface and within bulk structures. The shell nature and tail type was determined to dictate the preferential ordering structure and molecular reorganization at interfaces with the core nature effect secondary.

Dynamics of a two-dimensional order-disorder transition

International Nuclear Information System (INIS)

Sahni, P.S.; Dee, G.; Gunton, J.D.; Phani, M.; Lebowitz, J.L.; Kalos, M.

1981-01-01

We present results of a Monte Carlo study of the time development of a two-dimensional order-disorder model binary alloy following a quench to low temperature from a disordered, high-temperature state. The behavior is qualitatively quite similar to that seen in a recent study of a three-dimensional system. The structure function exhibits a scaling of the form K 2 (t)S(k,t) = G(k/K(t)) where the moment K(t) decreases with time approximately like t/sup -1/2/. If one interprets this moment as being inversely proportional to the domain size, the characteristic domain growth rate is proportional to t/sup -1/2/. Additional insight into this time evolution is obtained from studying the development of the short-range order, as well as from monitoring the growth of a compact ordered domain embedded in a region of opposite order. All these results are consistent with the picture of domain growth as proposed by Lifshitz and by Cahn and Allen

Magnetic order and Kondo effect in the Anderson-lattice model

International Nuclear Information System (INIS)

Bernhard, B.H.; Aguiar, C.; Kogoutiouk, I.; Coqblin, B.

2007-01-01

The Anderson-lattice model has been extensively developed to account for the properties of many anomalous rare-earth compounds and in particular for the competition between the Kondo effect and an antiferromagnetic (AF) phase in a cubic lattice. Here we apply the higher-order decoupling of the equations of motion for the Green Functions (GF) introduced in [H.G. Luo, S.J. Wang, Phys. Rev. B 62 (2000) 1485]. We obtain an improved description of the phase diagram, where the AF phase subsists in a smaller range of the model parameters. As higher-order GF are included in the chain of equations, we are able to calculate directly the local spin-flip correlation function † ↓ d † ↑ f ↑ d ↓ >. As a further improvement to the previous approximation of [B.H. Bernhard, C. Aguiar, B. Coqblin, Physica B 378-380 (2006) 712], we obtain a reduced range of existence for the AF phase for the symmetric half-filled case and then we discuss the competition between the AF order and the Kondo effect as a function of the band filling

Long-range interaction between heterogeneously charged membranes.

Science.gov (United States)

Jho, Y S; Brewster, R; Safran, S A; Pincus, P A

2011-04-19

Despite their neutrality, surfaces or membranes with equal amounts of positive and negative charge can exhibit long-range electrostatic interactions if the surface charge is heterogeneous; this can happen when the surface charges form finite-size domain structures. These domains can be formed in lipid membranes where the balance of the different ranges of strong but short-ranged hydrophobic interactions and longer-ranged electrostatic repulsion result in a finite, stable domain size. If the domain size is large enough, oppositely charged domains in two opposing surfaces or membranes can be strongly correlated by the electrostatic interactions; these correlations give rise to an attractive interaction of the two membranes or surfaces over separations on the order of the domain size. We use numerical simulations to demonstrate the existence of strong attractions at separations of tens of nanometers. Large line tensions result in larger domains but also increase the charge density within the domain. This promotes correlations and, as a result, increases the intermembrane attraction. On the other hand, increasing the salt concentration increases both the domain size and degree of domain anticorrelation, but the interactions are ultimately reduced due to increased screening. The result is a decrease in the net attraction as salt concentration is increased. © 2011 American Chemical Society

Charge ordering in the rare earth manganates: the experimental situation

International Nuclear Information System (INIS)

Rao, C.N.R.; Cheetham, A.K.; Raveau, Bernard

2000-01-01

Charge-ordered phases of rare earth manganates are novel manifestations arising from interactions between the charge carriers and phonons, giving rise to the localization of carriers at specific sites in the lattice below a certain temperature. Accompanying this phenomenon, the Mn 3+ (e g ) orbitals and the associated lattice distortions also exhibit long range ordering (orbital ordering). What makes the manganates even more interesting is the occurrence of complex spin ordering related to anisotropic magnetic interactions. In this article, we discuss the emerging scenario of charge-ordered rare earth manganates in the light of specific case studies and highlight some of the new experimental findings related to spin, orbital and charge ordering. We also examine features such as the charge stripes and phase separation found experimentally in these materials, and discuss the factors that affect charge-ordering such as the size of A-site cations and magnetic and electric fields, as well as isotopic and chemical substitutions. (author)

A wide dynamic range BF3 neutron monitor with front-end electronics based on a logarithmic amplifier

International Nuclear Information System (INIS)

Ferrarini, M.; Varoli, V.; Favalli, A.; Caresana, M.; Pedersen, B.

2010-01-01

This paper describes a wide dynamic range neutron monitor based on a BF 3 neutron detector. The detector is used in current mode, and front-end electronics based on a logarithmic amplifier are used in order to have a measurement capability ranging over many orders of magnitude. The system has been calibrated at the Polytechnic of Milan, CESNEF, with an AmBe neutron source, and has been tested in a pulsed field at the PUNITA facility at JRC, Ispra. The detector has achieved a dynamic range of over 6 orders of magnitude, being able to measure single neutron pulses and showing saturation-free response for a reaction rate up to 10 6 s -1 . It has also proved effective in measuring the PUNITA facility pulse integral fluence.

Ranging Behaviour of Commercial Free-Range Laying Hens

Directory of Open Access Journals (Sweden)

Leonard Ikenna Chielo

2016-04-01

Full Text Available In this study, the range use and behaviour of laying hens in commercial free-range flocks was explored. Six flocks were each visited on four separate days and data collected from their outdoor area (divided into zones based on distance from shed and available resources. These were: apron (0–10 m from shed normally without cover or other enrichments; enriched belt (10–50 m from shed where resources such as manmade cover, saplings and dust baths were provided; and outer range (beyond 50 m from shed with no cover and mainly grass pasture. Data collection consisted of counting the number of hens in each zone and recording behaviour, feather condition and nearest neighbour distance (NND of 20 birds per zone on each visit day. In addition, we used techniques derived from ecological surveys to establish four transects perpendicular to the shed, running through the apron, enriched belt and outer range. Number of hens in each 10 m × 10 m quadrat was recorded four times per day as was the temperature and relative humidity of the outer range. On average, 12.5% of hens were found outside. Of these, 5.4% were found in the apron; 4.3% in the enriched zone; and 2.8% were in the outer range. This pattern was supported by data from quadrats, where the density of hens sharply dropped with increasing distance from shed. Consequently, NND was greatest in the outer range, least in the apron and intermediate in the enriched belt. Hens sampled in outer range and enriched belts had better feather condition than those from the apron. Standing, ground pecking, walking and foraging were the most commonly recorded activities with standing and pecking most likely to occur in the apron, and walking and foraging more common in the outer range. Use of the outer range declined with lower temperatures and increasing relative humidity, though use of apron and enriched belt was not affected by variation in these measures. These data support previous findings that outer range

L_p- and S_{p,q}^rB-discrepancy of (order 2) digital nets

OpenAIRE

Markhasin, Lev

2014-01-01

Dick proved that all order $2$ digital nets satisfy optimal upper bounds of the $L_2$-discrepancy. We give an alternative proof for this fact using Haar bases. Furthermore, we prove that all digital nets satisfy optimal upper bounds of the $S_{p,q}^r B$-discrepancy for a certain parameter range and enlarge that range for order $2$ digitals nets. $L_p$-, $S_{p,q}^r F$- and $S_p^r H$-discrepancy is considered as well.

Time-dependent Second Order Scattering Theory for Weather Radar with a Finite Beam Width

Science.gov (United States)

Kobayashi, Satoru; Tanelli, Simone; Im, Eastwood; Ito, Shigeo; Oguchi, Tomohiro

2006-01-01

Multiple scattering effects from spherical water particles of uniform diameter are studied for a W-band pulsed radar. The Gaussian transverse beam-profile and the rectangular pulse-duration are used for calculation. An second-order analytical solution is derived for a single layer structure, based on a time-dependent radiative transfer theory as described in the authors' companion paper. When the range resolution is fixed, increase in footprint radius leads to increase in the second order reflectivity that is defined as the ratio of the second order return to the first order one. This feature becomes more serious as the range increases. Since the spaceborne millimeter-wavelength radar has a large footprint radius that is competitive to the mean free path, the multiple scattering effect must be taken into account for analysis.

Bendable, low-loss Topas fibers for the terahertz frequency range

DEFF Research Database (Denmark)

Nielsen, Kristian; Rasmussen, Henrik K.; Adam, Aurèle J.L.

2009-01-01

structure proves that the fiber is single-moded over a wide frequency range, and we see the onset of higher-order modes at high frequencies as well as indication of microporous guiding at low frequencies and high porosity of the fiber. Transmission spectroscopy demonstrates low-loss propagation (

Super-ranging. A new ranging strategy in European badgers.

Directory of Open Access Journals (Sweden)

Aoibheann Gaughran

Full Text Available We monitored the ranging of a wild European badger (Meles meles population over 7 years using GPS tracking collars. Badger range sizes varied seasonally and reached their maximum in June, July and August. We analysed the summer ranging behaviour, using 83 home range estimates from 48 individuals over 6974 collar-nights. We found that while most adult badgers (males and females remained within their own traditional social group boundaries, several male badgers (on average 22% regularly ranged beyond these traditional boundaries. These adult males frequently ranged throughout two (or more social group's traditional territories and had extremely large home ranges. We therefore refer to them as super-rangers. While ranging across traditional boundaries has been recorded over short periods of time for extraterritorial mating and foraging forays, or for pre-dispersal exploration, the animals in this study maintained their super-ranges from 2 to 36 months. This study represents the first time such long-term extra-territorial ranging has been described for European badgers. Holding a super-range may confer an advantage in access to breeding females, but could also affect local interaction networks. In Ireland & the UK, badgers act as a wildlife reservoir for bovine tuberculosis (TB. Super-ranging may facilitate the spread of disease by increasing both direct interactions between conspecifics, particularly across social groups, and indirect interactions with cattle in their shared environment. Understanding super-ranging behaviour may both improve our understanding of tuberculosis epidemiology and inform future control strategies.

Automation of orders in taxi service

OpenAIRE

Simčič, Matej

2012-01-01

Automation is rapidly growing in the last years. The advantages it brings are cost reduction, faster and better performance of tasks that would be otherwise done by humas. It began in the manufacturing industry and later expanded to other sectors. Today's technology allows the implementation of automation in a wide range of areas. The thesis deals with the implementation of a system that allows automated ordering of a taxi. The system consists of four components. They are two mobile app...

Establishing a Near Term Lunar Farside Gravity Model via Inexpensive Add-on Navigation Payload

Science.gov (United States)

Folta, David; Mesarch, Michael; Miller, Ronald; Bell, David; Jedrey, Tom; Butman, Stanley; Asmar, Sami

2007-01-01

The Space Communications and Navigation, Constellation Integration Project (SCIP) is tasked with defining, developing, deploying and operating an evolving multi-decade communications and navigation (C/N) infrastructure including services and subsystems that will support both robotic and human exploration activities at the Moon. This paper discusses an early far side gravitational mapping service and related telecom subsystem that uses an existing spacecraft (WIND) and the Lunar Reconnaissance Orbiter (LRO) to collect data that would address several needs of the SCIP. An important aspect of such an endeavor is to vastly improve the current lunar gravity model while demonstrating the navigation and stationkeeping of a relay spacecraft. We describe a gravity data acquisition activity and the trajectory design of the relay orbit in an Earth-Moon L2 co-linear libration orbit. Several phases of the transfer from an Earth-Sun to the Earth-Moon region are discussed along with transfers within the Earth-Moon system. We describe a proposed, but not integrated, add-on to LRO scheduled to be launched in October of 2008. LRO provided a real host spacecraft against which we designed the science payload and mission activities. From a strategic standpoint, LRO was a very exciting first flight opportunity for gravity science data collection. Gravity Science data collection requires the use of one or more low altitude lunar polar orbiters. Variations in the lunar gravity field will cause measurable variations in the orbit of a low altitude lunar orbiter. The primary means to capture these induced motions is to monitor the Doppler shift of a radio signal to or from the low altitude spacecraft, given that the signal is referenced to a stable frequency reference. For the lunar far side, a secondary orbiting radio signal platform is required. We provide an in-depth look at link margins, trajectory design, and hardware implications. Our approach posed minimum risk to a host mission while

Working for the New Order

DEFF Research Database (Denmark)

Lund, Joachim

Damned if you do - damned if you don't. During the Second World War, the collaboration dilemma regarding Europe's business life came to the forefront as business leaders were faced with the necessity of cooperating with the German enemy in order to maintain production and essing a wide range......, Europe's business life contributed substantially to the Nazi German war effort. It was working for the oachim Lund is an historian, Ph.D. and Associate Professor at the Centre for European Cultural Studies, Copenhagen Business School. He is the author of a number of books and articles on Denmark...

A Novel Sigma-Delta Modulator with Fractional-Order Digital Loop Integrator

Directory of Open Access Journals (Sweden)

Chi Xu

2017-01-01

Full Text Available This paper proposes using a fractional-order digital loop integrator to improve the robust stability of Sigma-Delta modulator, thus extending the integer-order Sigma-Delta modulator to a non-integer-order (fractional-order one in the Sigma-Delta ADC design field. The proposed fractional-order Sigma-Delta modulator has reasonable noise characteristics, dynamic range, and bandwidth; moreover the signal-to-noise ratio (SNR is improved remarkably. In particular, a 2nd-order digital loop integrator and a digital PIλDμ controller are combined to work as the fractional-order digital loop integrator, which is realized using FPGA; this will reduce the ASIC analog circuit layout design and chip testing difficulties. The parameters of the proposed fractional-order Sigma-Delta modulator are tuned by using swarm intelligent algorithm, which offers opportunity to simplify the process of tuning parameters and further improve the noise performance. Simulation results are given and they demonstrate the efficiency of the proposed fractional-order Sigma-Delta modulator.

Third-order nonlinear optical properties of thin sputtered gold films

Science.gov (United States)

Xenogiannopoulou, E.; Aloukos, P.; Couris, S.; Kaminska, E.; Piotrowska, A.; Dynowska, E.

2007-07-01

Au films of thickness ranging between 5 and 52 nm were prepared by sputtering on quartz substrates and their third-order nonlinear optical response was investigated by Optical Kerr effect (OKE) and Z-scan techniques using 532 nm, 35 ps laser pulses. All prepared films were characterized by XRD, AFM and UV-VIS-NIR spectrophotometry while their third-order susceptibility χ(3) was measured and found to be of the order of 10 -9 esu. The real and imaginary parts of the third-order susceptibility were found in very good agreement with experimental results and theoretical predictions reported by Smith et al. [D.D. Smith, Y. Yoon, R.W. Boyd, Y.K. Cambell, L.A. Baker, R.M. Crooks, M. George, J. Appl. Phys. 86 (1999) 6200].

Birth Order, Sibling IQ Differences, and Family Relations.

Science.gov (United States)

Pfouts, Jane H.

The differential impact of birth order and IQ on sibling roles were examined with particular interest focused on achievement outcomes. Subjects were a stratified sample of 37 pairs of near-in-age siblings, all within the normal range in personality and IQ, but differing significantly in scores on the Slosson IQ Test. Results indicate that when the…

Radiation ordering in quenched alloys observed 'in situ' in the high voltage microscope

International Nuclear Information System (INIS)

Tendeloo, G. van; Landuyt, J. van; Amelinckx, S.

1979-01-01

Different alloys with a face centered cubic disordered structure have been electron irradiated in the quenched or short range order state under direct observation in a high voltage electron microscope. Ordering due to 1 MeV irradiation has been observed in Au 4 MN, Ni 4 Mo and Cu 3 Pd. Care has been taken to avoid ordering due to the thermal effect of the electron beam. It has been demonstrated that although similar states of order can be achieved by thermal and irradiation ordering, the path followed can be different. (author)

Suppression of the long-range magnetic order in Pb{sub 3}(Mn{sub 1−x}Fe{sub x}){sub 7}O{sub 15} upon substitution of Fe for Mn

Energy Technology Data Exchange (ETDEWEB)

Volkov, N.V. [Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036 (Russian Federation); Eremin, E.V., E-mail: eev@iph.krasn.ru [Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036 (Russian Federation); Bayukov, O.A.; Sablina, K.A. [Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036 (Russian Federation); Solov’ev, L.A. [Institute of Chemistry and Chemical Technology, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660049 (Russian Federation); Velikanov, D.A.; Mikhashenok, N.V.; Osetrov, E.I. [Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036 (Russian Federation); Schefer, J.; Keller, L. [Laboratory for Neutron Scattering, ETH Zurich and Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Boehm, M. [Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble, Cedex 9 (France)

2013-09-15

Structure and magnetic properties of Pb{sub 3}(Mn{sub 1−x}Fe{sub x}){sub 7}O{sub 15} single crystals with x=0–0.2 grown by spontaneous crystallization from solution in melt have been investigated. All the crystals belong to the hexagonal space group P6{sub 3}/mcm. The magnetic properties appeared to be strongly dependent on the iron doping level. At small (x=0.05) dopant concentrations, the value of magnetization and Neel temperature T{sub N} decrease insignificantly (T{sub N}=70 K). With increasing x, the three-dimensional magnetic ordering does not occur and temperature dependences of magnetization at x≥0.1 exhibit spin-glass-like features in the low-temperature region. - Highlights: • In the first time the single crystals of Pb{sub 3}(Mn{sub 1−x}Fe{sub x}){sub 7}O{sub 15} were grown. • The valence and locations of iron ions in crystal were determined. • Suppression of the long-range magnetic order in Pb{sub 3}(Mn{sub 1−x}Fe{sub x}){sub 7}O{sub 15} was discovered.

Electron diffraction study of the sillenites Bi12SiO20, Bi25FeO39 and Bi25InO39: Evidence of short-range ordering of oxygen-vacancies in the trivalent sillenites

Directory of Open Access Journals (Sweden)

Craig A. Scurti

2014-08-01

Full Text Available We present an electron diffraction study of three sillenites, Bi12SiO20, Bi25FeO39, and Bi25InO39 synthesized using the solid-state method. We explore a hypothesis, inspired by optical studies in the literature, that suggests that trivalent sillenites have additional disorder not present in the tetravalent compounds. Electron diffraction patterns of Bi25FeO39 and Bi25InO39 show streaks that confirm deviations from the ideal sillenite structure. Multi-slice simulations of electron-diffraction patterns are presented for different perturbations to the sillenite structure - partial substitution of the M site by Bi3+, random and ordered oxygen-vacancies, and a frozen-phonon model. Although comparison of experimental data to simulations cannot be conclusive, we consider the streaks as evidence of short-range ordered oxygen-vacancies.

On the energy emission by a Kerr black hole in the superradiant range

International Nuclear Information System (INIS)

Curir, A.

1985-01-01

A new redefined ''Unruh vacuum'' has been used in order to obtain the thermal Hawkin emission in a Kerr geometry in the superradiant range. It is also shown that a new type of vacuum is needed to obtain the global emission from a rotating black hole in the superradiant range. The formula describing such global emission is given. (orig.)

Kinetically Inhibited Order in a Diamond-Lattice Antiferromagnet

International Nuclear Information System (INIS)

MacDougall, Gregory J.; Gout, Delphine J.; Zarestky, Jerel L.; Ehlers, Georg; Podlesnyak, Andrey A.; McGuire, Michael A.; Mandrus, David; Nagler, Stephen E.

2011-01-01

Frustrated magnetic systems exhibit highly degenerate ground states and strong fluctuations, often leading to new physics. An intriguing example of current interest is the antiferromagnet on a diamond lattice, realized physically in the A-site spinel materials. This is a prototypical system in three dimensions where frustration arises from competing interactions rather than purely geometric constraints, and theory suggests the possibility of novel order at low temperature. Here we present a comprehensive single crystal neutron scattering study CoAl2O4, a highly frustrated A-site spinel. We observe strong diffuse scattering that peaks at wavevectors associated with Neel ordering. Below the temperature T*=6.5K, there is a dramatic change in elastic scattering lineshape accompanied by the emergence of well-defined spin-wave excitations. T* had previously been associated with the onset of glassy behavior. Our new results suggest instead that in fact T* signifies a first-order phase transition, but with true long-range order inhibited by the kinetic freezing of domain walls. This scenario might be expected to occur widely in frustrated systems containing first-order phase transitions and is a natural explanation for existing reports of anomalous glassy behavior in other materials.

Effects of mobility on ordering dynamics

International Nuclear Information System (INIS)

Baronchelli, Andrea; Pastor-Satorras, Romualdo

2009-01-01

Models of ordering dynamics allow us to understand natural systems in which an initially disordered population homogenizes some traits via local interactions. The simplest of these models, with wide applications ranging from evolutionary to social dynamics, are the Voter and Moran processes, usually defined in terms of static or randomly mixed individuals that interact with a neighbor to copy or modify a discrete trait. Here we study the effects of diffusion in Voter/Moran processes by proposing a generalization of ordering dynamics in a metapopulation framework, in which individuals are endowed with mobility and diffuse through a spatial structure represented as a graph of patches upon which interactions take place. We show that diffusion dramatically affects the time to reach the homogeneous state, independently of the underlying network's topology, while the final consensus emerges through different local/global mechanisms, depending on the mobility strength. Our results highlight the crucial role played by mobility in ordering processes and set up a general framework that allows its effect to be studied on a large class of models, with implications in the understanding of evolutionary and social phenomena. (letter)

Disentangling neighbors and extended range density oscillations in monatomic amorphous semiconductors.

Science.gov (United States)

Roorda, S; Martin, C; Droui, M; Chicoine, M; Kazimirov, A; Kycia, S

2012-06-22

High energy x-ray diffraction measurements of pure amorphous Ge were made and its radial distribution function (RDF) was determined at high resolution, revealing new information on the atomic structure of amorphous semiconductors. Fine structure in the second peak in the RDF provides evidence that a fraction of third neighbors are closer than some second neighbors; taking this into account leads to a narrow distribution of tetrahedral bond angles, (8.5 ± 0.1)°. A small peak which appears near 5 Å upon thermal annealing shows that some ordering in the dihedral bond-angle distribution takes place during structural relaxation. Extended range order is detected (in both a-Ge and a-Si) which persists to beyond 20 Å, and both the periodicity and its decay length increase upon thermal annealing. Previously, the effect of structural relaxation was only detected at intermediate range, involving reduced tetrahedral bond-angle distortions. These results enhance our understanding of the atomic order in continuous random networks and place significantly more stringent requirements on computer models intending to describe these networks, or their alternatives which attempt to describe the structure in terms of an arrangement of paracrystals.

Numerical simulation of range and backscattering for keV protons incident on random targets

International Nuclear Information System (INIS)

Robinson, J.E.; Agamy, S.

1975-01-01

Using a Monte-Carlo technique, projected range distributions and backscattering coefficients have been calculated for keV protons normally incident on heavy targets. For an incident reduced energy range of 1 less than epsilon 0 less than 20, both the projected range distributions and backscattering coefficients have been found to be in good agreement with a third order Edgeworth range approximation. Backscattered energy and angular distributions have also been calculated and are compared to available theoretical and experimental data. (4 figs.) (U.S.)

Determination of thorium in the range of low concentrations

International Nuclear Information System (INIS)

Hill, R.; Lieser, K.H.

1992-01-01

Methods for the determination of Th in the range of low concentrations are compiled and discussed. Application of spectrophotometry and voltammetry is investigated. Spectrophotometry is applicable down to concentrations of the order of 0.1 μg/l as long as the ratio U:Th is low. Voltammetric determination of Th is not possible in the presence of Al. (orig.)

Local order dependent impurity levels in alloy semiconductors

International Nuclear Information System (INIS)

Silva, C.E.T.G. da; Ecole Normale Superieure, 75 - Paris

1981-01-01

We develop a one band/may sites model for an isoelectronic impurity in a semiconductor alloy. The cluster-Bethe-lattice approximation is used to study the dependence of the impurity energy level upon the short range order (SRO) of the alloy. The Kikuchi parametrization is used to describe the latter. We take into account diagonal disorder only, with possible off-diagonal relaxation around the impurity site. All the inequivalent clusters of the impurity site and its first nearest neighbours are considered, thus including the important short range alloy potential fluctuations. Results are presented for the local density of impurity states, for different degrees of SRO in the alloy. (Author) [pt

Modified spin-wave theory with ordering vector optimization: frustrated bosons on the spatially anisotropic triangular lattice

Energy Technology Data Exchange (ETDEWEB)

Hauke, Philipp [ICFO-Institut de Ciencies Fotoniques, Meditarranean Technology Park, E-08860 Castelldefels, Barcelona (Spain); Roscilde, Tommaso [Laboratoire de Physique, Ecole Normale Superieure de Lyon, 46 Allee d' Italie, F-69007 Lyon (France); Murg, Valentin; Ignacio Cirac, J; Schmied, Roman, E-mail: Philipp.Hauke@icfo.e [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany)

2010-05-15

We investigate a system of frustrated hardcore bosons, modeled by an XY antiferromagnet on the spatially anisotropic triangular lattice, using Takahashi's modified spin-wave (MSW) theory. In particular, we implement ordering vector optimization on the ordered reference state of MSW theory, which leads to significant improvement of the theory and accounts for quantum corrections to the classically ordered state. The MSW results at zero temperature compare favorably to exact diagonalization (ED) and projected entangled-pair state (PEPS) calculations. The resulting zero-temperature phase diagram includes a one-dimensional (1D) quasi-ordered phase, a 2D Neel ordered phase and a 2D spiraling ordered phase. Strong indications coming from the ED and PEPS calculations, as well as from the breakdown of MSW theory, suggest that the various ordered or quasi-ordered phases are separated by spin-liquid phases with short-range correlations, in analogy to what has been predicted for the Heisenberg model on the same lattice. Within MSW theory, we also explore the finite-temperature phase diagram. In agreement with the Berezinskii-Kosterlitz-Thouless (BKT) theory, we find that zero-temperature long-range-ordered phases turn into quasi-ordered phases (up to a BKT transition temperature), while zero-temperature quasi-ordered phases become short-range correlated at finite temperature. These results show that, despite its simplicity, MSW theory is very well suited to describing ordered and quasi-ordered phases of frustrated XY spins (or, equivalently, of frustrated lattice bosons) both at zero and finite temperatures. While MSW theory, just as other theoretical methods, cannot describe spin-liquid phases, its breakdown provides a fast and reliable method for singling out Hamiltonians that may feature these intriguing quantum phases. We thus suggest a tool for guiding our search for interesting systems whose properties are necessarily studied with a physical quantum simulator

COM-LOC: A Distributed Range-Free Localization Algorithm in Wireless Networks

NARCIS (Netherlands)

Dil, B.J.; Havinga, Paul J.M.; Marusic, S; Palaniswami, M; Gubbi, J.; Law, Y.W.

2009-01-01

This paper investigates distributed range-free localization in wireless networks using a communication protocol called sum-dist which is commonly employed by localization algorithms. With this protocol, the reference nodes flood the network in order to estimate the shortest distance between the

Topological order and thermal equilibrium in polariton condensates

Science.gov (United States)

Caputo, Davide; Ballarini, Dario; Dagvadorj, Galbadrakh; Sánchez Muñoz, Carlos; de Giorgi, Milena; Dominici, Lorenzo; West, Kenneth; Pfeiffer, Loren N.; Gigli, Giuseppe; Laussy, Fabrice P.; Szymańska, Marzena H.; Sanvitto, Daniele

2018-02-01

The Berezinskii-Kosterlitz-Thouless phase transition from a disordered to a quasi-ordered state, mediated by the proliferation of topological defects in two dimensions, governs seemingly remote physical systems ranging from liquid helium, ultracold atoms and superconducting thin films to ensembles of spins. Here we observe such a transition in a short-lived gas of exciton-polaritons, bosonic light-matter particles in semiconductor microcavities. The observed quasi-ordered phase, characteristic for an equilibrium two-dimensional bosonic gas, with a decay of coherence in both spatial and temporal domains with the same algebraic exponent, is reproduced with numerical solutions of stochastic dynamics, proving that the mechanism of pairing of the topological defects (vortices) is responsible for the transition to the algebraic order. This is made possible thanks to long polariton lifetimes in high-quality samples and in a reservoir-free region. Our results show that the joint measurement of coherence both in space and time is required to characterize driven-dissipative phase transitions and enable the investigation of topological ordering in open systems.

Exact extreme-value statistics at mixed-order transitions.

Science.gov (United States)

Bar, Amir; Majumdar, Satya N; Schehr, Grégory; Mukamel, David

2016-05-01

We study extreme-value statistics for spatially extended models exhibiting mixed-order phase transitions (MOT). These are phase transitions that exhibit features common to both first-order (discontinuity of the order parameter) and second-order (diverging correlation length) transitions. We consider here the truncated inverse distance squared Ising model, which is a prototypical model exhibiting MOT, and study analytically the extreme-value statistics of the domain lengths The lengths of the domains are identically distributed random variables except for the global constraint that their sum equals the total system size L. In addition, the number of such domains is also a fluctuating variable, and not fixed. In the paramagnetic phase, we show that the distribution of the largest domain length l_{max} converges, in the large L limit, to a Gumbel distribution. However, at the critical point (for a certain range of parameters) and in the ferromagnetic phase, we show that the fluctuations of l_{max} are governed by novel distributions, which we compute exactly. Our main analytical results are verified by numerical simulations.

Aeroelastic simulation using CFD based reduced order models

International Nuclear Information System (INIS)

Zhang, W.; Ye, Z.; Li, H.; Yang, Q.

2005-01-01

This paper aims at providing an accurate and efficient method for aeroelastic simulation. System identification is used to get the reduced order models of unsteady aerodynamics. Unsteady Euler codes are used to compute the output signals while 3211 multistep input signals are utilized. LS(Least Squares) method is used to estimate the coefficients of the input-output difference model. The reduced order models are then used in place of the unsteady CFD code for aeroelastic simulation. The aeroelastic equations are marched by an improved 4th order Runge-Kutta method that only needs to compute the aerodynamic loads one time at every time step. The computed results agree well with that of the direct coupling CFD/CSD methods. The computational efficiency is improved 1∼2 orders while still retaining the high accuracy. A standard aeroelastic computing example (isogai wing) with S type flutter boundary is computed and analyzed. It is due to the system has more than one neutral points at the Mach range of 0.875∼0.9. (author)

Topological order and thermal equilibrium in polariton condensates.

Science.gov (United States)

Caputo, Davide; Ballarini, Dario; Dagvadorj, Galbadrakh; Sánchez Muñoz, Carlos; De Giorgi, Milena; Dominici, Lorenzo; West, Kenneth; Pfeiffer, Loren N; Gigli, Giuseppe; Laussy, Fabrice P; Szymańska, Marzena H; Sanvitto, Daniele

2018-02-01

The Berezinskii-Kosterlitz-Thouless phase transition from a disordered to a quasi-ordered state, mediated by the proliferation of topological defects in two dimensions, governs seemingly remote physical systems ranging from liquid helium, ultracold atoms and superconducting thin films to ensembles of spins. Here we observe such a transition in a short-lived gas of exciton-polaritons, bosonic light-matter particles in semiconductor microcavities. The observed quasi-ordered phase, characteristic for an equilibrium two-dimensional bosonic gas, with a decay of coherence in both spatial and temporal domains with the same algebraic exponent, is reproduced with numerical solutions of stochastic dynamics, proving that the mechanism of pairing of the topological defects (vortices) is responsible for the transition to the algebraic order. This is made possible thanks to long polariton lifetimes in high-quality samples and in a reservoir-free region. Our results show that the joint measurement of coherence both in space and time is required to characterize driven-dissipative phase transitions and enable the investigation of topological ordering in open systems.

Radio frequency (RF) time-of-flight ranging for wireless sensor networks

International Nuclear Information System (INIS)

Thorbjornsen, B; White, N M; Brown, A D; Reeve, J S

2010-01-01

Position information of nodes within wireless sensor networks (WSNs) is often a requirement in order to make use of the data recorded by the sensors themselves. On deployment the nodes normally have no prior knowledge of their position and thus a locationing mechanism is required to determine their positions. In this paper, we describe a method to determine the point-to-point range between sensor nodes as part of the locationing process. A two-way time-of-flight (TOF) ranging scheme is presented using narrow-band RF. The frequency difference between the transceivers involved with the point-to-point measurement is used to obtain a sub-clock TOF phase offset measurement in order to achieve high resolution TOF measurements. The ranging algorithm has been developed and prototyped on a TI CC2430 development kit with no additional hardware being required. Performance results have been obtained for the line-of-sight (LOS), non-line-of-sight (NLOS) and indoor conditions. Accuracy is typically better than 7.0 m RMS for the LOS condition over 250.0 m and 15.8 m RMS for the NLOS condition over 120.0 m using a 100 sample average. Indoor accuracy is measured to 1.7 m RMS using a 1000 sample average over 8.0 m. Ranging error is linear and does not increase with the increased transmitter–receiver distance. Our TOA ranging scheme demonstrates a novel system where resolution and accuracy are time dependent in comparison with alternative frequency-dependent methods using narrow-band RF

Analytically calculated post-Keplerian range and range-rate perturbations: the solar Lense-Thirring effect and BepiColombo

Science.gov (United States)

Iorio, Lorenzo

2018-05-01

We analytically calculate the time series for the perturbations Δ ρ \\left(t\\right), Δ \\dot{ρ }\\left(t\\right) induced by a general disturbing acceleration A on the mutual range ρ and range-rate \\dot{ρ } of two test particles A, B orbiting the same spinning body. We apply it to the general relativistic Lense-Thirring effect, due to the primary's spin S, and the classical perturbation arising from its quadrupole mass moment J2 for arbitrary orbital geometries and orientation of the source's symmetry axis {\\hat{S}}. The Earth-Mercury range and range-rate are nominally affected by the Sun's gravitomagnetic field to the 10 m, 10-3 cm s-1 level, respectively, during the extended phase (2026-2028) of the forthcoming BepiColombo mission to Mercury whose expected tracking accuracy is of the order of ≃0.1 m, 2 × 10-4 cm s-1. The competing signatures due to the solar quadrupole J_2^{\\odot }, if modelled at the σ _{J_2^{\\odot }}˜eq 10^{-9} level of the latest planetary ephemerides INPOP17a, are nearly 10 times smaller than the relativistic gravitomagnetic effects. The position and velocity vectors \\boldsymbol {r}, \\boldsymbol {v} of Mercury and Earth are changed by the solar Lense-Thirring effect by about 10 m, 1.5 m and 10-3 cm s-1, 10-5 cm s-1, respectively, over 2 yr; neglecting such shifts may have an impact on long-term integrations of the inner Solar system dynamics over ˜Gyr time-scales.

Stimulating Public Interest in Lunar Exploration and Enhancing Science Literacy Through Library Programs

Science.gov (United States)

Shipp, S.; Nelson, B.; Stockman, S.; Weir, H.; Carter, B.; Bleacher, L.

2008-07-01

Libraries are vibrant learning places, seeking partners in science programming. LPI's Explore! program offers a model for public engagement in lunar exploration in libraries, as shown by materials created collaboratively with the LRO E/PO team.

Ferromagnetism and spin glass ordering in transition metal alloys (invited)

Science.gov (United States)

Crane, S.; Carnegie, D. W., Jr.; Claus, H.

1982-03-01

Magnetic properties of transition metal alloys near the percolation threshold are often complicated by metallurgical effects. Alloys like AuFe, VFe, CuNi, RhNi, and PdNi are in general not random solid solutions but have various degrees of atomic clustering or short-range order (SRO), depending on the heat treatment. First, it is shown how the magnetic ordering temperature of these alloys varies with the degree of clustering or SRO. Second, by systematically changing this degree of clustering or SRO, important information can be obtained about the magnetic phase diagram. In all these alloys below the percolation limit, the onset of ferromagnetic order is probably preceded by a spin glass-type ordering. However, details of the magnetic phase diagram near the critical point can be quite different alloy systems.

Using Elementary Mechanics to Estimate the Maximum Range of ICBMs

Science.gov (United States)

Amato, Joseph

2018-01-01

North Korea's development of nuclear weapons and, more recently, intercontinental ballistic missiles (ICBMs) has added a grave threat to world order. The threat presented by these weapons depends critically on missile range, i.e., the ability to reach North America or Europe while carrying a nuclear warhead. Using the limited information available…

van der Waals forces in density functional theory: Perturbational long-range electron-interaction corrections

International Nuclear Information System (INIS)

Angyan, Janos G.; Gerber, Iann C.; Savin, Andreas; Toulouse, Julien

2005-01-01

Long-range exchange and correlation effects, responsible for the failure of currently used approximate density functionals in describing van der Waals forces, are taken into account explicitly after a separation of the electron-electron interaction in the Hamiltonian into short- and long-range components. We propose a 'range-separated hybrid' functional based on a local density approximation for the short-range exchange-correlation energy, combined with a long-range exact exchange energy. Long-range correlation effects are added by a second-order perturbational treatment. The resulting scheme is general and is particularly well adapted to describe van der Waals complexes, such as rare gas dimers