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1

Physics Meets Philosophy at the Planck Scale  

NASA Astrophysics Data System (ADS)

Preface; 1. Introduction Craig Callendar and Nick Huggett; Part I. Theories of Quantum Gravity and their Philosophical Dimensions: 2. Spacetime and the philosophical challenge of quantum gravity Jeremy Butterfield and Christopher Isham; 3. Naive quantum gravity Steven Weinstein; 4. Quantum spacetime: what do we know? Carlo Rovelli; Part II. Strings: 5. Reflections on the fate of spacetime Edward Witten; 6. A philosopher looks at string theory Robert Weingard; 7. Black holes, dumb holes, and entropy William G. Unruh; Part III. Topological Quantum Field Theory: 8. Higher-dimensional algebra and Planck scale physics John C. Baez; Part IV. Quantum Gravity and the Interpretation of General Relativity: 9. On general covariance and best matching Julian B. Barbour; 10. Pre-Socratic quantum gravity Gordon Belot and John Earman; 11. The origin of the spacetime metric: Bell's 'Lorentzian Pedagogy' and its significance in general relativity Harvey R. Brown and Oliver Pooley; Part IV. Quantum Gravity and the Interpretation of Quantum Mechanics: 12. Quantum spacetime without observers: ontological clarity and the conceptual foundations of quantum gravity Sheldon Goldstein and Stefan Teufel; 13. On gravity's role in quantum state reduction Roger Penrose; 14. Why the quantum must yield to gravity Joy Christian.

Callender, Craig; Huggett, Nick

2001-04-01

2

Observable proton decay from Planck scale physics  

NASA Astrophysics Data System (ADS)

In the Standard Model, no dim-5 ?B?0 operators exist, so that Planck-scale-induced proton decay amplitudes are suppressed by at least 1/MP?2. If the Standard Model is augmented by a light, color-nonsinglet boson, then O(1/MP?) proton-decay amplitudes are possible. These always conserve B+L, so that the dominant decay modes are p??+? and p??+?+?-, where ?+=?+ or K+.

Barr, S. M.; Calmet, Xavier

2012-12-01

3

Planck scale physics and testability in SU(5) supergravity GUT  

NASA Astrophysics Data System (ADS)

Unification scale threshold corrections in minimal SU(5) supergravity grand unification are discussed. A probe of the underlying theory is outlined, where low energy measurements can in principle measure the effects of Planck scale (1/MPl) terms. A bound relating the strong coupling constant to the mass scales associated with proton decay and supersymmetry is derived including uncertainties associated with the high energy scale.

Ring, D.; Urano, S.; Arnowitt, R.

1995-12-01

4

Beyond the Planck Scale  

SciTech Connect

I outline motivations for believing that important quantum gravity effects lie beyond the Planck scale at both higher energies and longer distances and times. These motivations arise in part from the study of ultra-high energy scattering, and also from considerations in cosmology. I briefly summarize some inferences about such ultra-planckian physics, and clues we might pursue towards the principles of a more fundamental theory addressing the known puzzles and paradoxes of quantum gravity.

Giddings, Steven B. [Department of Physics, University of California, Santa Barbara, CA 93106 PH-TH, CERN, 1211 Geneve 23 (Switzerland)

2009-12-15

5

Probing the Planck scale with proton decay  

Microsoft Academic Search

We advocate the idea that proton decay may probe physics at the Planck scale instead of the GUT scale. This is possible because supersymmetric theories have dimension-5 operators that can induce proton decay at dangerous rates, even with R-parity conservation. These operators are expected to be suppressed by the same physics that explains the fermion masses and mixings. We present

Roni Harnik; Daniel T. Larson; Hitoshi Murayama; Marc Thormeier

2005-01-01

6

Probing the Planck Scale with Proton Decay  

Microsoft Academic Search

We advocate the idea that proton decay may probe physics at the Planck scale instead of the GUT scale. This is possible because supersymmetric theories have dimension-5 operators that can induce proton decay at dangerous rates, even with R-parity conservation. These operators are expected to be suppressed by the same physics that explains the fermion masses and mixings. We present

Roni Harnik; Daniel T. Larson; Hitoshi Murayama; Marc Thormeier

2004-01-01

7

Acceleration radiation and the Planck scale  

SciTech Connect

A uniformly accelerating observer perceives the Minkowski vacuum state as a thermal bath of radiation. We point out that this field-theory effect can be derived, for any dimension higher than two, without actually invoking very high energy physics. This supports the view that this phenomenon is robust against Planck-scale physics and, therefore, should be compatible with any underlying microscopic theory.

Agullo, Ivan; Navarro-Salas, Jose; Olmo, Gonzalo J.; Parker, Leonard [Department of Physics, University of Maryland, College Park, MD 20742 (United States) and Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC. Facultad de Fisica, Universidad de Valencia, Burjassot-46100, Valencia (Spain); Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC. Facultad de Fisica, Universidad de Valencia, Burjassot-46100, Valencia (Spain); Perimeter Institute, 31 Caroline Street N, Waterloo, Ontario N2L 2Y5 (Canada) and Physics Department, University of Wisconsin-Milwaukee, P. O. Box 413, Milwaukee, WI 53201 (United States); Physics Department, University of Wisconsin-Milwaukee, P. O. Box 413, Milwaukee, WI 53201 (United States)

2008-05-15

8

Proton Decay and the Planck Scale  

Microsoft Academic Search

Even without Grand Unification, proton decay can be a powerful probe of physics at the highest energy scales. Supersymmetric theories with conserved R-parity contain Planck-suppressed dimension 5 operators that give important contributions to nucleon decay. These operators are likely controlled by flavor physics, which means current and near future proton decay experiments might yield clues about the fermion mass spectrum.

Daniel T. Larson

2005-01-01

9

Proton Decay and the Planck Scale  

Microsoft Academic Search

Even without Grand Unification, proton decay can be a powerful probe of physics at the highest energy scales. Supersymmetric theories with conserved R-parity contain Planck-suppressed dimension 5 operators that give important contributions to nucleon decay. These operators are likely controlled by flavor physics, which means current and near future proton decay experiments might yield clues about the fermion mass spectrum.

Daniel T. Larson

2004-01-01

10

Proton Decay and the Planck Scale  

Microsoft Academic Search

Even without grand unification, proton decay can be a powerful probe of physics at the highest energy scales. Supersymmetric theories with conserved R-parity contain Planck-suppressed dimension 5 operators that give important contributions tonucleon decay. These operators are likely controlled by flavor physics, which means current and near future proton decay experiments might yield clues about the fermion mass spectrum. I

Daniel T. Larson; Daniel T

2004-01-01

11

Phenomenology of a realistic accelerating universe using only planck-scale physics  

PubMed

Modern data are showing increasing evidence that the Universe is accelerating. So far, all attempts to account for the acceleration have required some fundamental dimensionless quantities to be extremely small. We show how a class of scalar field models (which may emerge naturally from superstring theory) can account for acceleration which starts in the present epoch with all the potential parameters O(1) in Planck units. PMID:11017213

Albrecht; Skordis

2000-03-01

12

Is there an imprint of Planck-scale physics on inflationary cosmology?  

NASA Astrophysics Data System (ADS)

We study the effects of the trans-Planckian dispersion relation on the spectrum of the primordial density perturbations during inflation. In contrast to the earlier analyses, we do not assume any specific form of the dispersion relation and allow the initial state of the field to be arbitrary. We obtain the spectrum of vacuum fluctuations of the quantum field by considering a scalar field satisfying the linear wave equation with higher spatial derivative terms propagating in the de Sitter spacetime. We show that the power spectrum does not strongly depend on the dispersion relation and that the form of the dispersion relation does not play a significant role in obtaining the corrections to the scale invariant spectrum. We also show that the signatures of the deviations from the flat scale-invariant spectrum from the CMBR observations due to quantum gravitational effects cannot be differentiated from the standard inflationary scenario with an arbitrary initial state.

Shankaranarayanan, S.

2003-01-01

13

Proton Decay and the Planck Scale  

SciTech Connect

Even without grand unification, proton decay can be a powerful probe of physics at the highest energy scales. Supersymmetric theories with conserved R-parity contain Planck-suppressed dimension 5 operators that give important contributions tonucleon decay. These operators are likely controlled by flavor physics, which means current and near future proton decay experiments might yield clues about the fermion mass spectrum. I present a thorough analysis of nucleon partial lifetimes in supersymmetric one-flavon Froggatt-Nielsen models with a single U(1)_X family symmetry which is responsible for the fermionic mass spectrum as well as forbidding R-parity violating interactions. Many of the models naturally lead to nucleon decay near present limits without any reference to grand unification.

Larson, Daniel T.

2004-10-02

14

The Fermilab Holometer: Probing the Planck Scale  

NASA Astrophysics Data System (ADS)

Experimentally probing the Planck scale can offer insights into understanding a quantum origin of spacetime. The Fermilab Holometer team will look for a new noise source arising from the Planck scale by using the precision of power-recycled Michelson interferometers. The two nested 40 meter interferometers may have a characteristic power spectral density based on the conjectured frequency independent Planckian noise. By cross-correlating the dark port signal of two nearby interferometers, we can rule out conventional noise sources that are not common to both devices. A common source of noise could be from the underlying spacetime itself. A positive result will lead to insights in theories of an emergent quantum spacetime. The Holometer team has finished construction and begun scientific commissioning. First results of the experiment are expected in Spring 2015.

Kamai, Brittany; Chou, A.; Evans, M.; Glass, H.; Gustafson, R.; Hogan, C. J.; Lanza, R.; McCuller, L.; Meyer, S.; Richardson, J.; Sippel, A.; Steffen, J.; Stoughton, C.; Tomlin, R.; Volk, J.; Waldman, S.; Weiss, R.; Wester, W.; Holometer, Fermilab

2013-01-01

15

Max Planck Institute for Gravitational Physics  

NSDL National Science Digital Library

This expansive Web site features the Max Planck Institute for Gravitational Physics' research dealing primarily with geometric analysis and gravitation, astrophysical relativity, quantum gravity and unified theories, and laser interferometry and gravitational wave astronomy. After learning about the Institute's origins in 1995, researchers can find out about the institute's intense efforts and hardships in developing a consistent theory of quantum gravity as well as its investigation in gravitational radiation and causal structures. The site provides visitors with downloads to many published articles as well as links to two free access electronic review journals: _Living Reviews in Relativity_ and _Living Reviews in Solar Physics_. While some content is not in English, all visitors can find valuable information about research in gravitational physics.

16

Holographic Noise in Michelson Interferometers: A Direct Experimental Probe of Unification at the Planck Scale  

ScienceCinema

Classical spacetime and quantum mass-energy form the basis of all of physics. They become inconsistent at the Planck scale, 5.4 times 10^{-44} seconds, which may signify a need for reconciliation in a unified theory. Although proposals for unified theories exist, a direct experimental probe of this scale, 16 orders of magnitude above Tevatron energy, has seemed hopelessly out of reach. However in a particular interpretation of holographic unified theories, derived from black hole evaporation physics, a world assembled out of Planck-scale waves displays effects of unification with a new kind of uncertainty in position at the Planck diffraction scale, the geometric mean of the Planck length and the apparatus size. In this case a new phenomenon may measurable, an indeterminacy of spacetime position that appears as noise in interferometers. The colloquium will discuss the theory of the effect, and our plans to build a holographic interferometer at Fermilab to measure it.

17

Holographic Noise in Michelson Interferometers: A Direct Experimental Probe of Unification at the Planck Scale  

SciTech Connect

Classical spacetime and quantum mass-energy form the basis of all of physics. They become inconsistent at the Planck scale, 5.4 times 10{sup -44} seconds, which may signify a need for reconciliation in a unified theory. Although proposals for unified theories exist, a direct experimental probe of this scale, 16 orders of magnitude above Tevatron energy, has seemed hopelessly out of reach. However in a particular interpretation of holographic unified theories, derived from black hole evaporation physics, a world assembled out of Planck-scale waves displays effects of unification with a new kind of uncertainty in position at the Planck diffraction scale, the geometric mean of the Planck length and the apparatus size. In this case a new phenomenon may measurable, an indeterminacy of spacetime position that appears as noise in interferometers. The colloquium will discuss the theory of the effect, and our plans to build a holographic interferometer at Fermilab to measure it.

Hogan, Craig

2009-07-22

18

Holographic Noise in Michelson Interferometers: A Direct Experimental Probe of Unification at the Planck Scale  

ScienceCinema

Classical spacetime and quantum mass-energy form the basis of all of physics. They become inconsistent at the Planck scale, 5.4 times 10{sup -44} seconds, which may signify a need for reconciliation in a unified theory. Although proposals for unified theories exist, a direct experimental probe of this scale, 16 orders of magnitude above Tevatron energy, has seemed hopelessly out of reach. However in a particular interpretation of holographic unified theories, derived from black hole evaporation physics, a world assembled out of Planck-scale waves displays effects of unification with a new kind of uncertainty in position at the Planck diffraction scale, the geometric mean of the Planck length and the apparatus size. In this case a new phenomenon may measurable, an indeterminacy of spacetime position that appears as noise in interferometers. The colloquium will discuss the theory of the effect, and our plans to build a holographic interferometer at Fermilab to measure it.

19

Predictive description of Planck-scale-induced spacetime fuzziness  

NASA Astrophysics Data System (ADS)

Several approaches to the quantum-gravity problem predict that spacetime should be “fuzzy,” but so far these approaches have been unable to provide a crisp physical characterization of this notion. An intuitive picture of spacetime fuzziness has been proposed on the basis of semiheuristic arguments and, in particular, involves an irreducible Planck-scale contribution to the uncertainty of the energy of a particle. These arguments also inspired a rather active phenomenological program that looks for the blurring of images of distant astrophysical sources that would result from such energy uncertainties. Here we report the first ever physical characterization of spacetime fuzziness derived constructively within a quantum picture of spacetime, the one provided by spacetime noncommutativity. Our results confirm earlier heuristic arguments suggesting that spacetime fuzziness, while irrelevantly small on terrestrial scales, could be observably large for propagation of particles over cosmological distances. However, we find no Planck-scale-induced lower bound on the uncertainty of the energy of particles; we observe that this changes how we should picture a quantum spacetime, and it also imposes a reanalysis of the associated phenomenology.

Amelino-Camelia, Giovanni; Astuti, Valerio; Rosati, Giacomo

2013-04-01

20

Two-point functions with an invariant Planck scale and thermal effects  

SciTech Connect

Nonlinear deformations of relativistic symmetries at the Planck scale are usually addressed in terms of modified dispersion relations. We explore here an alternative route by directly deforming the two-point functions of an underlying field theory. The proposed deformations depend on a length parameter (Planck length) and preserve the basic symmetries of the corresponding theory. We also study the physical consequences implied by these modifications at the Planck scale by analyzing the response function of an accelerated detector in Minkowski space, an inertial one in de Sitter space, and also in a black hole spacetime.

Agullo, Ivan; Navarro-Salas, Jose; Olmo, Gonzalo J.; Parker, Leonard [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC. Facultad de Fisica, Universidad de Valencia, Burjassot-46100, Valencia (Spain); Perimeter Institute for Theoretical Physics, Waterloo, Ontario, N2L 2Y5 (Canada); Physics Department, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States)

2008-06-15

21

Testing Planck-Scale Gravity with Accelerators  

NASA Astrophysics Data System (ADS)

Quantum or torsion gravity models predict unusual properties of space-time at very short distances. In particular, near the Planck length, around 10-35m, empty space may behave as a crystal, singly or doubly refractive. However, this hypothesis remains uncheckable for any direct measurement, since the smallest distance accessible in experiment is about 10-19m at the LHC. Here I propose a laboratory test to measure the space refractivity and birefringence induced by gravity. A sensitivity from 10-31m down to the Planck length could be reached at existent GeV and future TeV energy lepton accelerators using laser Compton scattering. There are already experimental hints for gravity signature at distances approaching the Planck length by 5-7 orders of magnitude, derived from SLC and HERA data.

Gharibyan, Vahagn

2012-10-01

22

Testing Planck-scale gravity with accelerators.  

PubMed

Quantum or torsion gravity models predict unusual properties of space-time at very short distances. In particular, near the Planck length, around 10(-35)??m, empty space may behave as a crystal, singly or doubly refractive. However, this hypothesis remains uncheckable for any direct measurement, since the smallest distance accessible in experiment is about 10(-19)??m at the LHC. Here I propose a laboratory test to measure the space refractivity and birefringence induced by gravity. A sensitivity from 10(-31)??m down to the Planck length could be reached at existent GeV and future TeV energy lepton accelerators using laser Compton scattering. There are already experimental hints for gravity signature at distances approaching the Planck length by 5-7 orders of magnitude, derived from SLC and HERA data. PMID:23083234

Gharibyan, Vahagn

2012-10-04

23

Planck scale still safe from stellar images  

Microsoft Academic Search

The recent paper of Lieu and Hillman [1] that a possible, (birefringence\\u000alike) phase difference ambiguity coming from Planck effects would alter stellar\\u000aimages of distant sources is questioned. Instead for {\\\\em division of\\u000awavefront} interference and diffraction phenomena, initial (lateral) coherence\\u000ais developed simply by propagation of rays (cf. van Cittert-Zernike theorem).\\u000aThis case is strongly immune to quantum

D. H. Coule; Hampshire Terrace

2003-01-01

24

Is a tabletop search for Planck scale signals feasible?  

NASA Astrophysics Data System (ADS)

Quantum gravity theory is untested experimentally. Could it be tested with tabletop experiments? While the common feeling is pessimistic, a detailed inquiry shows it possible to sidestep the onerous requirement of localization of a probe on the Planck length scale. I suggest a tabletop experiment which, given state-of-the-art ultrahigh vacuum and cryogenic technology, could already be sensitive enough to detect Planck scale signals. The experiment combines a single photon’s degree of freedom with that of a macroscopic probe to test Wheeler’s conception of “quantum foam,” the assertion that on length scales of the Planck order, spacetime is no longer a smooth manifold. The scheme makes few assumptions beyond energy and momentum conservations, and is not based on a specific quantum gravity scheme.

Bekenstein, Jacob D.

2012-12-01

25

Inflation with a Planck-scale frequency cutoff  

Microsoft Academic Search

The implementation of a Planck-scale high frequency and short wavelength cutoff in quantum theories on expanding backgrounds may have potentially nontrivial implications, such as the breaking of local Lorentz invariance and the existence of a yet unknown mechanism for the creation of vacuum modes. In scenarios where inflation begins close to the cutoff scale, these effects could have observable consequences

Jens C. Niemeyer; Jens C

2001-01-01

26

Planck mission: challenges and expectations for cosmology and particle physics .  

NASA Astrophysics Data System (ADS)

The Planck satellite of the European Space Agency, scheduled to be launched on May 14th, 2009, is designed to observe the microwave sky with unprecedented frequency coverage, sensitivity and angular resolution, in order to provide the most accurate measurement of the anisotropies in the Cosmic Microwave Background. We review here the present status of the mission as well as the future milestones, give the main remarks on the forthcoming phase of data acquisition, analysis and interpretation, focusing on the leadership that Italian scientists and institutions represented for the entire Planck collaboration in the instrumental study, design, construction, and data analysis of one of the two instruments on board, the Low Frequency Instrument \\citep{mandolesi_etal_2004}. We describe the main scientific expectations and challenges for cosmology and particle physics, represented by this mission.

Baccigalupi, C.

27

Max Planck Institute for Extraterrestrial Physics: X-Ray Astronomy  

NSDL National Science Digital Library

This website features the latest space science news, research activities, projects, and laboratories of the Max Planck Institute for Extraterrestrial Physics' X-Ray Astronomy group. Visitors can view images and read clear summaries of its research in the areas of galactic and extragalactic astronomy. Researchers can learn about the group's instrumental techniques using soft and hard X-rays such as imaging with Wolter telescopes and multi-wire proportional counters. In the Data Center, visitors can explore the group's data analysis software and user data archives. The site provides links to its innumerable collaborators.

28

Inflation with a Planck-scale frequency cutoff  

SciTech Connect

The implementation of a Planck-scale high frequency and short wavelength cutoff in quantum theories on expanding backgrounds may have potentially nontrivial implications, such as the breaking of local Lorentz invariance and the existence of a yet unknown mechanism for the creation of vacuum modes. In scenarios where inflation begins close to the cutoff scale, these effects could have observable consequences as trans-Planckian modes are redshifted to cosmological scales. In close analogy with similar studies of Hawking radiation, a simple theory of a minimally coupled scalar field in de Sitter space is studied, with a high frequency cutoff imposed by a nonlinear dispersion relation. Under certain conditions the model predicts deviations from the standard inflationary scenario. We also comment on the difficulties in generalizing fluid models of Hawking radiation to cosmological space-times.

Niemeyer, Jens C.

2001-06-15

29

Inflation with a Planck-scale frequency cutoff  

NASA Astrophysics Data System (ADS)

The implementation of a Planck-scale high frequency and short wavelength cutoff in quantum theories on expanding backgrounds may have potentially nontrivial implications, such as the breaking of local Lorentz invariance and the existence of a yet unknown mechanism for the creation of vacuum modes. In scenarios where inflation begins close to the cutoff scale, these effects could have observable consequences as trans-Planckian modes are redshifted to cosmological scales. In close analogy with similar studies of Hawking radiation, a simple theory of a minimally coupled scalar field in de Sitter space is studied, with a high frequency cutoff imposed by a nonlinear dispersion relation. Under certain conditions the model predicts deviations from the standard inflationary scenario. We also comment on the difficulties in generalizing fluid models of Hawking radiation to cosmological space-times.

Niemeyer, Jens C.

2001-06-01

30

Trapped Bose–Einstein condensates with Planck-scale induced deformation of the energy–momentum dispersion relation  

NASA Astrophysics Data System (ADS)

We show that harmonically trapped Bose–Einstein condensates can be used to constrain Planck-scale physics. In particular we prove that a Planck-scale induced deformation of the Minkowski energy–momentum dispersion relation ?E??1mcp/2Mp produces a shift in the condensation temperature Tc of about ?Tc/Tc0?10?6?1 for typical laboratory conditions. Such a shift allows to bound the deformation parameter up to |?1|?104. Moreover we show that it is possible to enlarge ?Tc/Tc0 and improve the bound on ?1 lowering the frequency of the harmonic trap. Finally we compare the Planck-scale induced shift in Tc with similar effects due to interboson interactions and finite size effects.

Briscese, F.

2012-11-01

31

The Fractal Universe: From the Planck to the Hubble Scale  

Microsoft Academic Search

We examine the fractal structure of the physical universe from the large\\u000ascale to the smallest scale, including the phenomenon of fractal scaling. This\\u000ais explained in terms of a stochastic underpinning for the laws of physics. A\\u000apicture in pleasing agreement with experiment and observation at all scales\\u000aemerges, very much in the spirit of Wheeler's \\

B. G. Sidharth; B. M. Birla; Adarsh Nagar

1999-01-01

32

Planck-scale nonthermal correlations in a noncommutative geometry inspired Vaidya black hole  

NASA Astrophysics Data System (ADS)

Using the noncommutative geometry inspired Vaidya metric obtained in terms of coordinate coherent states and also utilizing the generalized uncertainty principle (GUP), we show that the nonthermal nature of the Hawking spectrum leads to Planck-scale nonthermal correlations between emitted modes of evaporation. Our analysis thus exhibits that owing to self-gravitational effects plus noncommutativity and GUP influences, information can emerge in the form of Planck-scale correlated emissions from the black hole.

Mehdipour, S. Hamid

2012-05-01

33

Quantum symmetry, the cosmological constant and Planck-scale phenomenology  

Microsoft Academic Search

We present a simple algebraic mechanism for the emergence of deformations of Poincaré symmetries in the low-energy limit of quantum theories of gravity. The deformations, called kappa-Poincaré algebras, are parametrized by a dimensional parameter proportional to the Planck mass, and imply modified energy momentum relations of a type that may be observable in near future experiments. Our analysis assumes that

Giovanni Amelino-Camelia; Lee Smolin; Artem Starodubtsev

2004-01-01

34

Scale problem in wormhole physics  

SciTech Connect

Wormhole physics from the quantum thoery of gravity coupled to the second-rank antisymmetric tensor or Goldstone-boson fields leads to an effective potential for these fields. The cosmological energy-density bound is shown to put an upper bound on the cosmological constant which wormhole physics can make zero. This upper bound, of order 10/sup 11/ GeV, is far smaller than the Planck scale and barely compatible with the possible cosmological constant arising from grand unified theories. In addition, the effect of wormholes on the axion for the strong /ital CP/ problem is discussed.

Kim, J. E.; Lee, K.

1989-07-03

35

Deformed boost transformations that saturate at the Planck scale  

Microsoft Academic Search

We derive finite boost transformations based on the Lorentz sector of the bicross-product-basis ?-Poincaré Hopf algebra. We emphasize the role of these boost transformations in a recently-proposed new relativistic theory, and their relevance for experimental studies presently being planned. We find that when the (dimensionful) deformation parameter is identified with the Planck length, which together with the speed-of-light constant has

N. R. Bruno; G. Amelino-Camelia; J. Kowalski-Glikman

2001-01-01

36

Dynamical Effects of the Neutrino Gravitational Clustering at Planck Angular Scales  

NASA Astrophysics Data System (ADS)

We study the cosmic microwave background (CMB) anisotropy induced by the nonlinear perturbations in the massive neutrino density associated with the nonlinear gravitational clustering process. By using N-body simulations, we compute the imprint left by gravitational clustering on the CMB anisotropy power spectrum for all nonlinear scales, taking into account the time evolution of all nonlinear density perturbations, for a flat, cold, hot dark matter model with cosmological constant (ACHDM) consistent with large-scale structure data and the latest CMB measurements with different neutrino fractions f? corresponding to a neutrino total mass in the range allowed by the neutrino oscillation and double beta decay experiments. We find that the nonlinear time-varying potential induced by the gravitational clustering process generates metric perturbations, leading to a decrease in the CMB anisotropy power spectrum of amplitude ?T/T~10-6 for angular resolutions between ~4' and 20', depending on the cluster mass scale and the neutrino fraction f?. We find a better consistency between the CMB angular power spectrum derived from BOOMERANG data and that derived from MAXIMA-1 and DASI and a slight reduction of the errors on most of the cosmological parameters when the nonlinear effects induced by the gravitational clustering are taken into account. Our results show that, for a neutrino fraction in agreement with that indicated by astroparticle and nuclear physics experiments, and a cosmological accreting mass comparable with the mass of known clusters, the angular resolution and sensitivity of the CMB anisotropy measurements from the Planck satellite will allow the detection of the dynamical effects of gravitational clustering. In addition, including the nonlinear aspects of the neutrino gravitational clustering allows reduction in the errors on ns and ?. This work has been performed within the framework of the Planck LFI activities.

Popa, L. A.; Burigana, C.; Mandolesi, N.

2002-11-01

37

Proceedings of the XXVI SLAC Summer Institute on Particle Physics: Gravity from the Hubble Length to the Planck Length  

SciTech Connect

The XXVI SLAC Summer Institute on Particle Physics was held from August 3 to August 14, 1998. The topic, ''Gravity--from the Hubble Length to the Planck Length,'' brought together 179 physicists from 13 countries. The lectures in this volume cover the seven-day school portion of the Institute, which took us from the largest scales of the cosmos, to the Planck length at which gravity might be unified with the other forces of nature. Lectures by Robert Wagoner, Clifford Will, and Lynn Cominsky explored the embedding of gravity into general relativity and the confrontation of this idea with experiments in the laboratory and astrophysical settings. Avishai Deckel discussed observations and implications of the large-scale structure of the universe, and Tony Tyson presented the gravitational lensing effect and its use in the ongoing search for signatures of the unseen matter of the cosmos. The hunt for the wave nature of gravity was presented by Sam Finn and Peter Saulson, and Joe Polchinski showed us what gravity might look like in the quantum limit at the Planck scale. The lectures were followed by afternoon discussion sessions, where students could further pursue questions and topics with the day's lecturers. The Institute concluded with a three-day topical conference covering recent developments in theory and experiment from around the world of elementary particle physics and cosmology; its proceedings are also presented in this volume.

Deporcel, Lilian

2001-04-02

38

Mesoscopic superposition and sub-Planck-scale structure in molecular wave packets  

SciTech Connect

We demonstrate the possibility of realizing sub-Planck-scale structures in the mesoscopic superposition of molecular wave packets involving vibrational levels. The time evolution of the wave packet, taken here as the SU(2) coherent state of the Morse potential describing hydrogen iodide molecules, produces macroscopic-quantum-superposition-like states, responsible for the above phenomenon. We investigate the phase-space dynamics of the coherent state through the Wigner function approach and identify the interference phenomena behind the sub-Planck-scale structures. The optimal parameter ranges are specified for observing these features.

Ghosh, Suranjana; Banerji, J.; Panigrahi, P. K. [Physical Research Laboratory, Navrangpura, Ahmedabad-380 009 (India); Chiruvelli, Aravind [University of Massachusetts at Boston, Boston, Massachusetts 02125-3393 (United States)

2006-01-15

39

TeV-scale B - L model with a flat Higgs potential at the Planck scale: In view of the hierarchy problem  

NASA Astrophysics Data System (ADS)

The recent discovery of a Higgs-like particle at around 126 GeV has provided a big hint towards the origin of the Higgs potential. In particular, the running quartic coupling vanishes near the Planck scale, which indicates a possible link between the physics in the electroweak and Planck scales. Motivated by this and the hierarchy problem, we investigate a possibility that the Higgs has a flat potential at the Planck scale. In particular, we study the renormalization group analysis of the B - L (baryon number minus lepton number) extension of the standard model [1,2] with classical conformality. The B - L symmetry is radiatively broken at the TeV scale via the Coleman-Weinberg mechanism. The electroweak symmetry breaking is triggered by a radiatively generated scalar mixing so that its scale, 246 GeV, is dynamically related to the B - L breaking scale at the TeV level. The Higgs boson mass is given at the border of the stability bound, which is lowered by a few GeV from the standard model by the effect of the B - L gauge interaction.

Iso, Satoshi; Orikasa, Yuta

2013-02-01

40

Quantum dynamics via Planck-scale-stepped action-carrying 'Graph Paths'  

SciTech Connect

A divergence-free, parameter-free, path-based discrete-time quantum dynamics is designed to not only enlarge the achievements of general relativity and the standard particle model, by approximations at spacetime scales far above Planck scale while far below Hubble scale, but to allow tackling of hitherto inaccessible questions. ''Path space'' is larger than and precursor to Hilbert-space basis. The wave-function-propagating paths are action-carrying structured graphs-cubic and quartic structured vertices connected by structured ''fermionic'' or ''bosonic'' ''particle'' and ''nonparticle'' arcs. A Planck-scale path step determines the gravitational constant while controlling all graph structure. The basis of the theory's (zero-rest-mass) elementary-particle Hilbert space (which includes neither gravitons nor scalar bosons) resides in particle arcs. Nonparticle arcs within a path are responsible for energy and rest mass.

Chew, Geoffrey F.

2003-05-05

41

Passage of Time in a Planck Scale Rooted Local Inertial Structure  

NASA Astrophysics Data System (ADS)

It is argued that the "problem of time" in quantum gravity necessitates a refinement of the local inertial structure of the world, demanding a replacement of the usual Minkowski line element by a (4+2n)-dimensional pseudo-Euclidean line element, with the extra 2n being the number of internal phase space dimensions of the observed system. In the refined structure, the inverse of the Planck time takes over the role of observer-independent conversion factor usually played by the speed of light, which now emerges as an invariant but derivative quantity. In the relativistic theory based on the refined structure, energies and momenta turn out to be invariantly bounded from above, and lengths and durations similarly bounded from below, by their respective Planck scale values. Along the external timelike world-lines, the theory naturally captures the "flow of time" as a genuinely structural attribute of the world. The theory also predicts expected deviations — suppressed quadratically by the Planck energy — from the dispersion relations for free fields in the vacuum. The deviations from the special relativistic Doppler shifts predicted by the theory are also suppressed quadratically by the Planck energy. Nonetheless, in order to estimate the precision required to distinguish the theory from special relativity, an experiment with a binary pulsar emitting TeV range ?-rays is considered in the context of the predicted deviations from the second-order shifts.

Christian, Joy

42

Twisting of Quantum Differentials and¶the Planck Scale Hopf Algebra  

Microsoft Academic Search

:   We show that the crossed modules and bicovariant differential calculi on two Hopf algebras related by a cocycle twist are\\u000a in 1-1 correspondence. In particular, for quantum groups which are cocycle deformation-quantisations of classical groups the\\u000a calculi are obtained as deformation-quantisations of the classical ones. As an application, we classify all bicovariant differential\\u000a calculi on the Planck scale Hopf

Shahn Majid; Robert Oeckl

1999-01-01

43

The Planck mass and the Chandrasekhar limit  

Microsoft Academic Search

The Planck mass is often assumed to play a role only at the extremely high energy scales where quantum gravity becomes important. However, this mass plays a role in any physical system that involves gravity, quantum mechanics, and relativity. We examine the role of the Planck mass in determining the maximum mass of white dwarf stars.

David Garfinkle

2009-01-01

44

Planck Intermediate Paper: Physics Of The Hot Gas In The Coma Cluster  

NASA Astrophysics Data System (ADS)

We present the data analysis of the Coma Cluster observed via Sunyaev-Zeldovich effect with the Planck satellite. Being a low redshift massive hot clusters, its angular size is so extended that Planck can resolve it spatially. Thanks to its great sensitivity, Planck is capable, for the first time, to detect SZ emission up to r 3-4 t R500. This allow us to study the pressure distribution of the Intracluster Medium to the outermost cluster regions, not yet achieved by any other instrument. We test the validity of some pressure models proposed to described the pressure distribution in clusters. In particular we find that the Arnuad et al. pressure profile for merging systems provides a good fit of the data only at rPlanck image shows two abrupt variations of the y signal located at approx 33 arcmin to the west and to the south east with respect to the cluster center. Using Planck y profiles extracted from corresponding sectors we verified that both abrupt variations are compatible with the presence of discontinuities of in the underlying density profile and we find pressure jumps of 4.5 and 4.9 in the west and south east, respectively. Finally, we find that the y and radio-synchrotron signals are quasi-linearly correlated on Mpc-scales with very small intrinsic scatter. This implies either that the energy density of cosmic-ray electrons is relatively constant throughout the cluster, or that the magnetic fields fall off much slower with radius than previously thought.

Mazzotta, Pasquale; Planck Collaboration

2012-05-01

45

Insensitivity of Hawking radiation to an invariant Planck-scale cutoff  

SciTech Connect

A disturbing aspect of Hawking's derivation of black hole radiance is the need to invoke extreme conditions for the quantum field that originates the emitted quanta. It is widely argued that the derivation requires the validity of the conventional relativistic field theory to arbitrarily high, trans-Planckian scales. We stress in this note that this is not necessarily the case if the question is presented in a covariant way. We point out that Hawking radiation is immediately robust against an invariant Planck-scale cutoff. This important feature of Hawking radiation is relevant for a quantum gravity theory that preserves, in some way, the Lorentz symmetry.

Agullo, Ivan [Physics Department, University of Wisconsin-Milwaukee, P.O.Box 413, Milwaukee, Wisconsin 53201 (United States); Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC, Facultad de Fisica, Universidad de Valencia, Burjassot-46100, Valencia (Spain); Navarro-Salas, Jose [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC, Facultad de Fisica, Universidad de Valencia, Burjassot-46100, Valencia (Spain); Olmo, Gonzalo J. [Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain); Parker, Leonard [Physics Department, University of Wisconsin-Milwaukee, P.O.Box 413, Milwaukee, Wisconsin 53201 (United States)

2009-08-15

46

A Vlasov-Fokker-Planck code for high energy density physics  

SciTech Connect

OSHUN is a parallel relativistic 2D3P Vlasov-Fokker-Planck code, developed primarily to study electron transport and instabilities pertaining to laser-produced-including laser-fusion-plasmas. It incorporates a spherical harmonic expansion of the electron distribution function, where the number of terms is an input parameter that determines the angular resolution in momentum-space. The algorithm employs the full 3D electromagnetic fields and a rigorous linearized Fokker-Planck collision operator. The numerical scheme conserves energy and number density. This enables simulations for plasmas with temperatures from MeV down to a few eV and densities from less than critical to more than solid. Kinetic phenomena as well as electron transport physics can be recovered accurately and efficiently.

Tzoufras, M., E-mail: m.tzoufras1@physics.ox.ac.uk [Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Bell, A.R. [Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Norreys, P.A. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Tsung, F.S. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)

2011-07-20

47

A Vlasov-Fokker-Planck code for high energy density physics  

NASA Astrophysics Data System (ADS)

OSHUN is a parallel relativistic 2D3P Vlasov-Fokker-Planck code, developed primarily to study electron transport and instabilities pertaining to laser-produced—including laser-fusion—plasmas. It incorporates a spherical harmonic expansion of the electron distribution function, where the number of terms is an input parameter that determines the angular resolution in momentum-space. The algorithm employs the full 3D electromagnetic fields and a rigorous linearized Fokker-Planck collision operator. The numerical scheme conserves energy and number density. This enables simulations for plasmas with temperatures from MeV down to a few eV and densities from less than critical to more than solid. Kinetic phenomena as well as electron transport physics can be recovered accurately and efficiently.

Tzoufras, M.; Bell, A. R.; Norreys, P. A.; Tsung, F. S.

2011-07-01

48

Conjecture on the physical implications of the scale anomaly  

SciTech Connect

Murray Gell-Mann, after co-inventing QCD, recognized the interplay of the scale anomaly, the renormalization group, and the origin of the strong scale, {Lambda}{sub QCD}. I tell a story, then elaborate this concept, and for the sake of discussion, propose a conjecture that the physical world is scale invariant in the classical, {h_bar}, limit. This principle has implications for the dimensionality of space-time, the cosmological constant, the weak scale, and Planck scale.

Hill, Christopher T.; /Fermilab

2005-10-01

49

The Y SZ-YX Scaling Relation as Determined from Planck and Chandra  

NASA Astrophysics Data System (ADS)

Sunyaev-Zeldovich (SZ) clusters surveys, such as Planck, the South Pole Telescope, and the Atacama Cosmology Telescope, will soon be publishing several hundred SZ-selected systems. The key ingredient required to transport the mass calibration from current X-ray-selected cluster samples to these SZ systems is the Y SZ-YX scaling relation. We constrain the amplitude, slope, and scatter of the Y SZ-YX scaling relation using SZ data from Planck and X-ray data from Chandra. We find a best-fit amplitude of ln (D 2 A Y SZ/CYX ) = -0.202 ± 0.024 at the pivot point CYX = 8 × 10-5 Mpc2. This corresponds to a Y SZ/YX ratio of 0.82 ± 0.024, in good agreement with X-ray expectations after including the effects of gas clumping. The slope of the relation is ? = 0.916 ± 0.032, consistent with unity at ?2.3?. We are unable to detect intrinsic scatter, and find no evidence that the scaling relation depends on cluster dynamical state.

Rozo, Eduardo; Vikhlinin, Alexey; More, Surhud

2012-11-01

50

THE Y {sub SZ}-Y{sub X} SCALING RELATION AS DETERMINED FROM PLANCK AND CHANDRA  

SciTech Connect

Sunyaev-Zeldovich (SZ) clusters surveys, such as Planck, the South Pole Telescope, and the Atacama Cosmology Telescope, will soon be publishing several hundred SZ-selected systems. The key ingredient required to transport the mass calibration from current X-ray-selected cluster samples to these SZ systems is the Y {sub SZ}-Y{sub X} scaling relation. We constrain the amplitude, slope, and scatter of the Y {sub SZ}-Y{sub X} scaling relation using SZ data from Planck and X-ray data from Chandra. We find a best-fit amplitude of ln (D {sup 2} {sub A} Y {sub SZ}/CY{sub X} ) = -0.202 {+-} 0.024 at the pivot point CY{sub X} = 8 Multiplication-Sign 10{sup -5} Mpc{sup 2}. This corresponds to a Y {sub SZ}/Y{sub X} ratio of 0.82 {+-} 0.024, in good agreement with X-ray expectations after including the effects of gas clumping. The slope of the relation is {alpha} = 0.916 {+-} 0.032, consistent with unity at Almost-Equal-To 2.3{sigma}. We are unable to detect intrinsic scatter, and find no evidence that the scaling relation depends on cluster dynamical state.

Rozo, Eduardo; More, Surhud [Kavli Institute for Cosmological Physics, Chicago, IL 60637 (United States); Vikhlinin, Alexey [Space Research Institute (IKI), Profsoyuznaya 84/32, Moscow 117810 (Russian Federation)

2012-11-20

51

Max-Planck-Institut fuer Kernphysik. Jahresbericht 1993. (Max-Planck Institute for Nuclear Physics. Annual report 1993).  

National Technical Information Service (NTIS)

Research in the fields of nuclear physics and particle physics focusses on experimental investigations into the structure of hadrons, hadron interactions, and the relation between the hadronic properties and nuclearphysics phenomena. The experimental and ...

R. Repnow J. Kiko

1994-01-01

52

PREFACE: DICE 2012 : Spacetime Matter Quantum Mechanics - from the Planck scale to emergent phenomena  

NASA Astrophysics Data System (ADS)

Presented in this volume are the Invited Lectures and the Contributed Papers of the Sixth International Workshop on Decoherence, Information, Complexity and Entropy - DICE 2012, held at Castello Pasquini, Castiglioncello (Tuscany), 17-21 September 2012. These proceedings may document to the interested public and to the wider scientific community the stimulating exchange of ideas at the meeting. The number of participants has been steadily growing over the years, reflecting an increasing attraction, if not need, of such conference. Our very intention has always been to bring together leading researchers, advanced students, and renowned scholars from various areas, in order to stimulate new ideas and their exchange across the borders of specialization. In this way, the series of meetings successfully continued from the beginning with DICE 20021, followed by DICE 20042, DICE 20063, DICE 20084, and DICE 20105, Most recently, DICE 2012 brought together more than 120 participants representing more than 30 countries worldwide. It has been a great honour and inspiration to have Professor Yakir Aharonov (Tel Aviv) with us, who presented the opening Keynote Lecture 'The two-vector quantum formalism'. With the overarching theme 'Spacetime - Matter - Quantum Mechanics - from the Planck scale to emergent phenomena', the conference took place in the very pleasant and inspiring atmosphere of Castello Pasquini - in beautiful surroundings, overlooking a piece of Tuscany's coast. The 5-day program covered these major topics: Quantum Mechanics, Foundations and Quantum-Classical Border Quantum-Classical Hybrids and Many-Body Systems Spectral Geometry, Path Integrals and Experiments Quantum -/- Gravity -/- Spacetime Quantum Mechanics on all Scales? A Roundtable Discussion under the theme 'Nuovi orizzonti nella ricerca scientifica. Ci troviamo di fronte ad una rivoluzione scientifica?' formed an integral part of the program. With participation of E Del Giudice (INFN & Università di Milano), F Guerra (Università 'La Sapienza', Roma) and G Vitiello (Università di Salerno), this event traditionally dedicated to the public drew a large audience involved in lively discussions until late. The workshop was organized by L Diósi (Budapest), H-T Elze (Pisa, chair), L Fronzoni (Pisa), J J Halliwell (London), E Prati (Milano) and G Vitiello (Salerno), with most essential help from our conference secretaries L Fratino, N Lampo, I Pozzana, and A Sonnellini, all students from Pisa, and from our former secretaries M Pesce-Rollins and L Baldini. Several institutions and sponsors supported the workshop and their representatives and, in particular, the citizens of Rosignano/Castiglioncello are deeply thanked for the generous help and kind hospitality: Comune di Rosignano - A Franchi (Sindaco di Rosignano), S Scarpellini (Segreteria sindaco), L Benini (Assessore ai lavori pubblici), M Pia (Assessore all' urbanistica) REA Rosignano Energia Ambiente s.p.a. - F Ghelardini (Presidente della REA), E Salvadori and C Peccianti (Segreteria) Associazione Armunia - A Nanni (Direttore), G Mannari (Programmazione), C Perna, F Bellini, M Nannerini, P Bruni and L Meucci (Tecnici). Special thanks go to G Mannari and her collaborators for advice and great help in all the practical matters that had to be dealt with, in order to run the meeting at Castello Pasquini smoothly Funds made available by Università di Pisa, Domus Galilaeana (Pisa), Centro Interdisciplinare per lo Studio dei Sistemi Complessi - CISSC (Pisa), Dipartimento di Ingegneria Industriale (Università di Salerno), Istituto Italiano per gli Studi Filosofici - IISF (Napoli), Solvay Italia SA (Rosignano), Institute of Physics Publishing - IOP (Bristol), Springer Verlag (Heidelberg), and Hungarian Scientific Research Fund OTKA are gratefully acknowledged. Last, but not least, special thanks are due to Laura Pesce (Vitrium Galleria, San Vincenzo) for the exposition of her artwork 'arte e scienza' at Castello Pasquini during the conference. The papers submitted in the wake of the conference have been edited by

Diósi, Lajos; Elze, Hans-Thomas; Fronzoni, Leone; Halliwell, Jonathan; Prati, Enrico; Vitiello, Giuseppe; Yearsley, James

2013-06-01

53

Hopf algebras for physics at the Planck scale  

Microsoft Academic Search

Applies ideas of non-commutative geometry to reformulate the classical and quantum mechanics of a particle moving on a homogeneous spacetime. The reformulation maintains an interesting symmetry between observables and states in the form of a Hopf algebra structure. In the simplest example both the dynamics and quantum mechanics are completely determined by the Hopf algebra consideration. The simplest example is

S. Majid

1988-01-01

54

Planck-scale Lorentz violation constrained by Ultra-High-Energy Cosmic Rays  

NASA Astrophysics Data System (ADS)

We investigate the consequences of higher dimension Lorentz violating, CPT even kinetic operators that couple standard model fields to a non-zero vector field in an Effective Field Theory framework. Comparing the ultra-high energy cosmic ray spectrum reconstructed in the presence of such terms with data from the Pierre Auger observatory allows us to establish two sided bounds on the coefficients of the mass dimension five and six operators for the proton and pion. Our bounds imply that for both protons and pions, the energy scale of Lorentz symmetry breaking must be well above the Planck scale. In particular, the dimension five operators are constrained at the level of 10-3MPlanck-1. The magnitude of the dimension six proton coefficient is bounded at the level of 10-6MPlanck-2 except in a narrow range where the pion and proton coefficients are both negative and nearly equal. In this small area, the magnitude of the dimension six proton coefficient must only be below 10-3MPlanck-2. Constraints on the dimension six pion coefficient are found to be much weaker, but still below MPlanck-2.

Maccione, Luca; Taylor, Andrew M.; Mattingly, David M.; Liberati, Stefano

2009-04-01

55

No-scale F-SU(5) in the light of the LHC, Planck and XENON  

NASA Astrophysics Data System (ADS)

We take stock of the no-scale F-SU(5) model's experimental status and prospects in the light of results from LHC, Planck, and XENON100. Given that no conclusive evidence for light supersymmetry (SUSY) has emerged from the \\sqrt{s} = 7, 8 TeV collider searches, the present work is focused on exploring and clarifying the precise nature of the high-mass cutoff enforced on this model at the point where the stau and neutralino mass degeneracy becomes so tight that cold dark matter relic density observations cannot be satisfied. This hard upper boundary on the model's mass scale constitutes a top–down theoretical mandate for a comparatively light (and testable) SUSY spectrum which does not excessively stress natural resolution of the gauge hierarchy problem. The overlap between the resulting model boundaries and the expected sensitivities of the future 14 TeV LHC and XENON 1-Ton direct detection SUSY/dark matter experiments is described.

Li, Tianjun; Maxin, James A.; Nanopoulos, Dimitri V.; Walker, Joel W.

2013-11-01

56

The Emergence of a Root Metaphor in Modern Physics: Max Planck's "Quantum" Metaphor.  

ERIC Educational Resources Information Center

Uses metaphorical analysis to determine whether or not Max Planck invented the quantum postulate. Demonstrates how metaphorical analysis can be used to analyze the rhetoric of revolutionary texts in science. Concludes that, in his original 1900 quantum paper, Planck considered the quantum postulate to be important, but not revolutionary. (PA)

Johnson-Sheehan, Richard D.

1997-01-01

57

The Emergence of a Root Metaphor in Modern Physics: Max Planck's "Quantum" Metaphor.  

ERIC Educational Resources Information Center

|Uses metaphorical analysis to determine whether or not Max Planck invented the quantum postulate. Demonstrates how metaphorical analysis can be used to analyze the rhetoric of revolutionary texts in science. Concludes that, in his original 1900 quantum paper, Planck considered the quantum postulate to be important, but not revolutionary. (PA)|

Johnson-Sheehan, Richard D.

1997-01-01

58

Planck-scale modifications to electrodynamics characterized by a spacelike symmetry-breaking vector  

NASA Astrophysics Data System (ADS)

In the study of Planck-scale (“quantum-gravity-induced”) violations of Lorentz symmetry, an important role was played by the deformed-electrodynamics model introduced by Myers and Pospelov. Its reliance on conventional effective quantum field theory, and its description of symmetry-violation effects simply in terms of a four-vector with a nonzero component only in the time direction, rendered it an ideal target for experimentalists and a natural concept-testing ground for many theorists. At this point however the experimental limits on the single Myers-Pospelov parameter, after improving steadily over these past few years, are “super-Planckian”; i.e. they take the model out of actual interest from a conventional quantum-gravity perspective. In light of this we here argue that it may be appropriate to move on to the next level of complexity, still with vectorial symmetry violation but adopting a generic four-vector. We also offer a preliminary characterization of the phenomenology of this more general framework, sufficient to expose a rather significant increase in complexity with respect to the original Myers-Pospelov setup. Most of these novel features are linked to the presence of spatial anisotropy, which is particularly pronounced when the symmetry-breaking vector is spacelike, and they are such that they reduce the bound-setting power of certain types of observations in astrophysics.

Gubitosi, Giulia; Genovese, Giuseppe; Amelino-Camelia, Giovanni; Melchiorri, Alessandro

2010-07-01

59

Planck-scale modifications to electrodynamics characterized by a spacelike symmetry-breaking vector  

SciTech Connect

In the study of Planck-scale ('quantum-gravity-induced') violations of Lorentz symmetry, an important role was played by the deformed-electrodynamics model introduced by Myers and Pospelov. Its reliance on conventional effective quantum field theory, and its description of symmetry-violation effects simply in terms of a four-vector with a nonzero component only in the time direction, rendered it an ideal target for experimentalists and a natural concept-testing ground for many theorists. At this point however the experimental limits on the single Myers-Pospelov parameter, after improving steadily over these past few years, are 'super-Planckian'; i.e. they take the model out of actual interest from a conventional quantum-gravity perspective. In light of this we here argue that it may be appropriate to move on to the next level of complexity, still with vectorial symmetry violation but adopting a generic four-vector. We also offer a preliminary characterization of the phenomenology of this more general framework, sufficient to expose a rather significant increase in complexity with respect to the original Myers-Pospelov setup. Most of these novel features are linked to the presence of spatial anisotropy, which is particularly pronounced when the symmetry-breaking vector is spacelike, and they are such that they reduce the bound-setting power of certain types of observations in astrophysics.

Gubitosi, Giulia; Amelino-Camelia, Giovanni; Melchiorri, Alessandro [Dipartimento di Fisica, Universita di Roma 'La Sapienza' and Sezione Roma1 INFN, Piazzale Aldo Moro 2, 00185 Roma (Italy); Genovese, Giuseppe [Dipartimento di Matematica, Universita di Roma 'La Sapienza' and Sezione Roma1 INFN, Piazzale Aldo Moro 2, 00185 Roma (Italy)

2010-07-15

60

Quantum averages from Gaussian random fields at the Planck length scale  

NASA Astrophysics Data System (ADS)

We show that the mathematical formalism of quantum mechanics can be interpreted as a method for approximation of classical (measure-theoretic) averages of functions f : L2(R3) --> R. These are classical physical variables in our model with hidden variables - Prequantum Classical Statistical Field Theory (PCSFT). In this paper we provide a simple stochastic picture of such a quantum approximation procedure. In the probabilistic terms this is nothing else than the approximative method for computation of averages for functions of random variables. Since in PCSFT the space of hidden variables is L2(R3), the role of a classical random variable is played by a random field. In PCSFT we consider Gaussian random fields representing random fluctuations at the prequantum length scale. Quantum mechanical expression for the average (given by the von Neumann trace formula) is obtained through moving from the prequantum length scale to the quantum one (the scale at that we are able to perform measurements).

Khrennikov, Andrei

2008-05-01

61

Parameter extraction by Planck for a cold dark matter model with broken scale invariance and cosmological constant  

NASA Astrophysics Data System (ADS)

We consider a class of spatially flat cold dark matter (CDM) models, with a cosmological constant and a broken-scale-invariant (BSI) step-like primordial spectrum of adiabatic perturbations, previously found to be in very good agreement with observations. Performing a Fisher matrix analysis, we show that, in the case of a large gravitational wave (GW) contribution, some free parameters (defining the step) of our BSI model can be extracted with remarkable accuracy by the Planck satellite, thanks to the polarization anisotropy measurements. Further, cosmological parameters can still be found with very good precision, despite a larger number of free parameters than in the simplest inflationary models.

Lesgourgues, Julien; Prunet, Simon; Polarski, David

1999-02-01

62

Probing Planck's Law at Home  

ERIC Educational Resources Information Center

|We report on the physics around an incandescent lamp. Using a consumer-grade digital camera, we combine electrical and optical measurements to explore Planck's law of black-body radiation. This simple teaching experiment is successfully used to measure both Stefan's and Planck's constants. Our measurements lead to a strikingly accurate value for…

Bonnet, I.; Gabelli, J.

2010-01-01

63

String Theory and its Applications - TASI 2010 From meV to the Planck Scale  

NASA Astrophysics Data System (ADS)

Overview. 1. Introduction to gauge/gravity duality / J. Polchinski. 2. TASI lectures on holographic space-time, SUSY, and gravitational effective field theory / T. Banks -- LHC physics. 3. Fundamentals of LHC experiments / J. Nielsen. 4. Theoretical particle physics at hadron colliders: an introduction / M. J. Strassler -- String model building, landscape and phenomenology. 5. TASI lectures: particle physics from perturbative and non-perturbative effects in D-Braneworlds / M. Cvetic and J. Halverson. 6. Supergravity and string vacua in various dimensions / W. Taylor. 7. TASI lectures on complex structures / F. Denef. 8. Supersymmetry from the top down / M. Dine -- AdS/CFT applications. 9. The landscape of the Hubbard model / S. Sachdev. 10. Holography for strongly coupled media / D. T. Son. 11. Collisions in anti-de Sitter space, conformal symmetry, and holographic superconductors / S. S. Gubser. 12. Emergence of supersymmetry, gauge theory and string theory in condensed matter systems / S.-S. Lee. 13. Lectures on holographic non-Fermi liquids and quantum phase transitions / N. Iqbal, H. Liu and M. Mezei. 14. The fluid/gravity correspondence / S. Minwalla, V. E. Hubeny and M. Rangamani.

Dine, Michael; Banks, Thomas; Sachdev, Subir

64

Activities report of the Max-Planck Institute of Nuclear Physics  

NASA Astrophysics Data System (ADS)

The research work in the field of nuclear physics comprises: (1) technical developments on tandem accelerators, the Heidelberg Heavy ion postaccelerator, the Heildelberg Heavy ion test storage ring, and a source for polarized alkali ions; (2) experimental work on, the development of detectors and experimental set-ups, solids and microstructures, giant resonances and continuum excitations, nuclear spectroscopy, mechanisms of nuclear reactions, fusion and fission, atomic physics and interaction of charged particles with matter, and medium and high energy physics; and (3) theoretical work on a statistical model of nuclei, reactions and solids, nuclear reactions at high energies, many-particles, quantum chromodynamics, and nuclear beta and double beta decay. In the field of cosmophysics, research activities were performed on meteorites and lunar rocks, the gallium solar neutrino experiment, comets, the PHOBOS project, interplanetary and interstellar dust, planetary atmospheres, interstellar medium and cosmic rays, molecular collisions, nuclear geology and geochemistry, and archaeometry.

Klapdor, H. V.; Jessberger, E. K.

65

Development of the Fokker-Planck Equation and its solutions for modeling transport of conservative and reactive solutes in physically heterogeneous media  

Microsoft Academic Search

When a scale-dependent fractal dispersivity is introduced in the convective-dispersive equation of transport in subsurface flow, the Fokker-Planck equation (FPE), also known as the second diffusion equation, is derived. Similarity solutions of the one-dimensional FPE, subject to a Dirac delta function input, are also presented. The similarity solution is shown to function as a kernel in the convolution integral to

Ninghu Su

1995-01-01

66

Development of the Fokker-Planck equation and its solutions for modeling transport of conservative and reactive solutes in physically heterogeneous media  

Microsoft Academic Search

When a scale-dependent fractal dispersivity is introduced in the convective-dispersive equation of transport in subsurface flow, the Fokker-Planck equation (FPE), also known as the second diffusion equation, is derived. Similarity solutions of the one-dimensional FPE, subject to a Dirac delta function input, are also presented. The similarity solution is shown to function as a kernel in the convolution integral to

Ninghu Su

1995-01-01

67

Planck early results. I. The Planck mission  

Microsoft Academic Search

The European Space Agency's Planck satellite was launched on 14 May 2009, and has been surveying the sky stably and continuously since 13 August 2009. Its performance is well in line with expectations, and it will continue to gather scientific data until the end of its cryogenic lifetime. We give an overview of the history of Planck in its first

P. A. R. Ade; N. Aghanim; M. Arnaud; M. Ashdown; J. Aumont; C. Baccigalupi; M. Baker; A. Balbi; A. J. Banday; R. B. Barreiro; J. G. Bartlett; E. Battaner; K. Benabed; K. Bennett; A. Benoît; J.-P. Bernard; M. Bersanelli; R. Bhatia; J. J. Bock; A. Bonaldi; J. R. Bond; J. Borrill; T. Bradshaw; M. Bremer; M. Bucher; C. Burigana; R. C. Butler; P. Cabella; C. M. Cantalupo; B. Cappellini; J.-F. Cardoso; R. Carr; M. Casale; A. Catalano; L. Cayón; A. Challinor; A. Chamballu; J. Charra; R.-R. Chary; L.-Y. Chiang; C. Chiang; P. R. Christensen; D. L. Clements; S. Colombi; F. Couchot; A. Coulais; B. P. Crill; G. Crone; M. Crook; F. Cuttaia; L. Danese; O. D'Arcangelo; R. D. Davies; R. J. Davis; P. de Bernardis; J. de Bruin; G. de Gasperis; A. de Rosa; G. de Zotti; J. Delabrouille; J.-M. Delouis; F.-X. Désert; J. Dick; C. Dickinson; K. Dolag; H. Dole; S. Donzelli; O. Doré; U. Dörl; M. Douspis; X. Dupac; G. Efstathiou; T. A. Enßlin; H. K. Eriksen; F. Finelli; S. Foley; O. Forni; P. Fosalba; M. Frailis; E. Franceschi; M. Freschi; T. C. Gaier; S. Galeotta; J. Gallegos; B. Gandolfo; K. Ganga; M. Giard; G. Giardino; G. Gienger; Y. Giraud-Héraud; J. González-Nuevo; K. M. Górski; S. Gratton; A. Gregorio; A. Gruppuso; G. Guyot; J. Haissinski; F. K. Hansen; D. Harrison; G. Helou; S. Henrot-Versillé; C. Hernández-Monteagudo; D. Herranz; S. R. Hildebrandt; E. Hivon; M. Hobson; A. Hornstrup; W. Hovest; R. J. Hoyland; K. M. Huffenberger; A. H. Jaffe; T. Jagemann; W. C. Jones; J. J. Juillet; M. Juvela; P. Kangaslahti; E. Keihänen; R. Keskitalo; T. S. Kisner; R. Kneissl; L. Knox; M. Krassenburg; H. Kurki-Suonio; G. Lagache; A. Lähteenmäki; J.-M. Lamarre; A. E. Lange; A. Lasenby; R. J. Laureijs; C. R. Lawrence; S. Leach; J. P. Leahy; R. Leonardi; C. Leroy; P. B. Lilje; M. Linden-Vørnle; M. López-Caniego; S. Lowe; P. M. Lubin; J. F. Macías-Pérez; T. Maciaszek; C. J. MacTavish; B. Maffei; D. Maino; N. Mandolesi; R. Mann; M. Maris; E. Martínez-González; S. Masi; M. Massardi; S. Matarrese; F. Matthai; P. Mazzotta; A. McDonald; P. R. Meinhold; A. Melchiorri; J.-B. Melin; L. Mendes; A. Mennella; C. Mevi; R. Miniscalco; S. Mitra; M.-A. Miville-Deschênes; A. Moneti; L. Montier; G. Morgante; N. Morisset; D. Mortlock; D. Munshi; A. Murphy; P. Naselsky; P. Natoli; C. B. Netterfield; H. U. Nørgaard-Nielsen; F. Noviello; D. Novikov; I. Novikov; I. J. O'Dwyer; I. Ortiz; S. Osborne; P. Osuna; C. A. Oxborrow; F. Pajot; R. Paladini; B. Partridge; F. Pasian; T. Passvogel; G. Patanchon; D. Pearson; T. J. Pearson; O. Perdereau; L. Perotto; F. Piacentini; M. Piat; E. Pierpaoli; S. Plaszczynski; P. Platania; E. Pointecouteau; G. Polenta; N. Ponthieu; L. Popa; T. Poutanen; G. Prézeau; S. Prunet; J.-L. Puget; J. P. Rachen; W. T. Reach; R. Rebolo; M. Reinecke; J.-M. Reix; C. Renault; S. Ricciardi; T. Riller; I. Ristorcelli; G. Rocha; C. Rosset; M. Rowan-Robinson; J. A. Rubiño-Martín; B. Rusholme; E. Salerno; M. Sandri; D. Santos; G. Savini; B. M. Schaefer; D. Scott; M. D. Seiffert; P. Shellard; A. Simonetto; G. F. Smoot; C. Sozzi; J.-L. Starck; J. Sternberg; F. Stivoli; V. Stolyarov; R. Stompor; L. Stringhetti; R. Sudiwala; R. Sunyaev; J.-F. Sygnet; D. Tapiador; J. A. Tauber; D. Tavagnacco; D. Taylor; L. Terenzi; D. Texier; L. Toffolatti; M. Tomasi; J.-P. Torre; M. Tristram; J. Tuovinen; M. Türler; M. Tuttlebee; G. Umana; L. Valenziano; J. Valiviita; J. Varis; L. Vibert; P. Vielva; F. Villa; N. Vittorio; L. A. Wade; B. D. Wandelt; C. Watson; S. D. M. White; M. White; A. Wilkinson; D. Yvon; A. Zacchei; A. Zonca

2011-01-01

68

Planck scale physics and Bogoliubov spaces in a Bose-Einstein condensate  

NASA Astrophysics Data System (ADS)

We analyze the consequences caused by a deformed dispersion relation, suggested in several quantum gravity models, upon a bosonic gas. Concerning the ground state of the Bogoliubov space of this system, we deduce the corrections in the pressure, the speed of sound, and the corresponding healing length. Indeed, we prove that the corrections in the relevant thermodynamic properties associated with the ground state, define a non-trivial function of the density of particles and the deformation parameters, allowing us to constrain, in principle, the form of the modified energy-momentum dispersion relation.

Castellanos, E.

2013-08-01

69

Development of Physics Self-Efficacy Scale  

NASA Astrophysics Data System (ADS)

In this article, we describe development of a Physics Self-Efficacy Scale (PSES) that is a self-administered measure to assess physics self-efficacy beliefs regarding one's ability to successfully perform physics tasks in physics classroom. The scale is initially composed of 56 items prepared following a brief scrutiny of relating literature on self-efficacy. It was initially administered 30 physics teacher candidates and was also examined by 6 experts of physics education, then ambiguous or incomprehensible 6 items were dismissed. This PSES was tested on 558 undergraduate students all completed fundamental physics courses. Cronbach's Alpha reliability coefficient of the PSES was calculated as 0.94. The final version of the PSES contained 30 items with 5 dimensions namely, 1. Self-efficacy towards solving physics problems, 2. Self-efficacy towards physics laboratory, 3. Self-efficacy towards learning physics, 4. Self-efficacy towards application of physics knowledge and 5. Self-efficacy towards memorizing physics knowledge.

Çali?kan, Serap; Selçuk, Gamze S.; Erol, Mustafa

2007-04-01

70

Validation Studies of the Physical Activity Scale  

Cancer.gov

Validation Studies of the Physical Activity Scale Aadahl et al. 2007 See reference #74 Methods Relation between self-reported physical activity level and VO2max (l/min) using linear regression analyses with covariates sex, age and bodyweight Sample 57

71

Multiple Scales in Solid State Physics  

Microsoft Academic Search

The quest for an accurate simulations of the physical world, most vividly expressed in the vision of Laplace's daemon [1], is almost as old as quantitative science. Naturally, such a simulation requires the knowledge of all the relevant physical\\u000a laws, i.e., a Theory of Everything. For the phenomena involving scales larger than an atomic nucleus and smaller than a star,

Erik Koch; Eva Pavarini

72

Planck's Energy Constant  

NASA Astrophysics Data System (ADS)

Planck's proportionality constant ``h'' is not an action constant. Re-examination of Planck's work has revealed the numerical value for his famous constant ``h'' is actually an energy constant.* Planck's energy constant is the mean energy of a single oscillation of electromagnetic energy, namely 6.626 X 10-34 J/osc. The misinterpretation of Planck's constant resulted from an inadvertent mathematical procedure in his 1901 black-body derivation. Planck's energy constant is found in his original (1897) quantum relationship: E a ? tm where energy (``E'') is proportional to the product of a constant (``a'', energy per oscillation), the frequency (``?''), and the measurement time (``tm''). Planck's inadvertence fixed the measurement time variable ``tm'' at a value of one second, and multiplied it by his constant ``a'', resulting in the product ``h'' which Planck proposed as the ``quantum of action''. Planck's black-body derivation and condensed quantum formula E = h? were never knowingly premised on one second time intervals, however. Subsequent development of quantum mechanics thus took place against the back drop of a hidden assumption. Numerous paradoxes, problems and a lack of reality resulted. Recognition of Planck's energy constant provides a richer and more realistic interpretation of quantum mechanics. *Brooks, JHJ, ``Hidden Variables: The Elementary Quantum of Light'', The Nature of Light: What are Photons? III, Proc. of SPIE Vol. 7421, 74210T-3, 2009. )

Brooks, Juliana

2010-02-01

73

THE PHYSICAL BASIS OF ZERO-POINT ENERGY? Planck's Constant from Hubble's Constant: Cosmological Origin of Terrestrial ZPF & Zitterbewegung  

Microsoft Academic Search

In a Newtonian model of e.g. the Bohr atom, it is physically incorrect to omit the aggregate forces from all electrostatic charges (monopole potential (with or without retarded potentials)) in the visible universe. Though the standard hypotheses of cosmic homogeneity\\/isotropy imply such forces have a zero-mean, they also have a non-zero variance! It is known since Fényes (1952) & Nelson

Robert W. Bass; Dean Zes

74

Microfluidics: Fluid physics at the nanoliter scale  

NASA Astrophysics Data System (ADS)

Microfabricated integrated circuits revolutionized computation by vastly reducing the space, labor, and time required for calculations. Microfluidic systems hold similar promise for the large-scale automation of chemistry and biology, suggesting the possibility of numerous experiments performed rapidly and in parallel, while consuming little reagent. While it is too early to tell whether such a vision will be realized, significant progress has been achieved, and various applications of significant scientific and practical interest have been developed. Here a review of the physics of small volumes (nanoliters) of fluids is presented, as parametrized by a series of dimensionless numbers expressing the relative importance of various physical phenomena. Specifically, this review explores the Reynolds number Re, addressing inertial effects; the Péclet number Pe, which concerns convective and diffusive transport; the capillary number Ca expressing the importance of interfacial tension; the Deborah, Weissenberg, and elasticity numbers De, Wi, and El, describing elastic effects due to deformable microstructural elements like polymers; the Grashof and Rayleigh numbers Gr and Ra, describing density-driven flows; and the Knudsen number, describing the importance of noncontinuum molecular effects. Furthermore, the long-range nature of viscous flows and the small device dimensions inherent in microfluidics mean that the influence of boundaries is typically significant. A variety of strategies have been developed to manipulate fluids by exploiting boundary effects; among these are electrokinetic effects, acoustic streaming, and fluid-structure interactions. The goal is to describe the physics behind the rich variety of fluid phenomena occurring on the nanoliter scale using simple scaling arguments, with the hopes of developing an intuitive sense for this occasionally counterintuitive world.

Squires, Todd M.; Quake, Stephen R.

2005-10-01

75

The Planck Surveyor mission: astrophysical prospects  

SciTech Connect

Although the Planck Surveyor mission is optimized to map the cosmic microwave background anisotropies, it will also provide extremely valuable information on astrophysical phenomena. We review our present understanding of Galactic and extragalactic foregrounds relevant to the mission and discuss on one side, Planck{close_quote}s impact on the study of their properties and, on the other side, to what extent foreground contamination may affect Planck{close_quote}s ability to accurately determine cosmological parameters. Planck{close_quote}s multifrequency surveys will be unique in their coverage of large areas of the sky (actually, of the full sky); this will extend by two or more orders of magnitude the flux density interval over which mm/sub-mm counts of extragalactic sources can be determined by instruments already available (like SCUBA) or planned for the next decade (like the LSA-MMA or the space mission FIRST), which go much deeper but over very limited areas. Planck will thus provide essential complementary information on the epoch-dependent luminosity functions. Bright radio sources will be studied over a poorly explored frequency range where spectral signatures, essential to understand the physical processes that are going on, show up. The Sunyaev-Zeldovich effect, with its extremely rich information content, will be observed in the direction of a large number of rich clusters of Galaxies. Thanks again to its all sky coverage, Planck will provide unique information on the structure and on the emission properties of the interstellar medium in the Galaxy. At the same time, the foregrounds are unlikely to substantially limit Planck{close_quote}s ability to measure the cosmological signals. Even measurements of polarization of the primordial Cosmic Microwave background fluctuations appear to be feasible. {copyright} {ital 1999 American Institute of Physics.}

De Zotti, Gianfranco; Toffolatti, Luigi [Osservatorio Astronomico di Padova, Vicolo dellOsservatorio 5, I-35122 Padova (Italy)] Toffolatti, Luigi [Dep. de Fisica, Universidad de Oviedo, c.le Calvo Sotelo s/n, E-33007 Oviedo (Spain)] Argueso, Francisco [Dep. de Matematicas, Universidad de Oviedo, c.le Calvo Sotelo s/n, E-33007 Oviedo (Spain)] Davies, Rodney D. [Nuffield Radio Astron. Lab., University of Manchester, Jodrell Bank, Macclesfield Cheshire SK11 9DL (United Kingdom)] Smoot, George F. [LBNL, SSL, Physics Department, University of California, Berkeley, California 94720 (United States); Vittorio, Nicola [Universita di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Roma (Italy)] Partridge, R. Bruce [Haverford College, Haverford, Pennsylvania 19041-1392 (United States)

1999-05-01

76

Physics in space-time with scale-dependent metrics  

NASA Astrophysics Data System (ADS)

We construct three-dimensional space R?3 with the scale-dependent metric and the corresponding Minkowski space-time M?,?4 with the scale-dependent fractal (DH) and spectral (DS) dimensions. The local derivatives based on scale-dependent metrics are defined and differential vector calculus in R?3 is developed. We state that M?,?4 provides a unified phenomenological framework for dimensional flow observed in quite different models of quantum gravity. Nevertheless, the main attention is focused on the special case of flat space-time M1/3,14 with the scale-dependent Cantor-dust-like distribution of admissible states, such that DH increases from DH=2 on the scale ??0 to DH=4 in the infrared limit ??0, where ?0 is the characteristic length (e.g. the Planck length, or characteristic size of multi-fractal features in heterogeneous medium), whereas DS?4 in all scales. Possible applications of approach based on the scale-dependent metric to systems of different nature are briefly discussed.

Balankin, Alexander S.

2013-10-01

77

The Planck Radiation Functions.  

ERIC Educational Resources Information Center

Blackbody radiation is used as an example to illustrate that oversimplification in teaching quantum ideas can result in later misunderstanding. Although textbooks give Planck's distribution function in terms of wavelength, there are actually 12 different radiation functions. Some of the more interesting ones are given and discussed. (JN)

Larsen, Russell D.

1985-01-01

78

A review of axion inflation in the era of Planck  

NASA Astrophysics Data System (ADS)

Because the inflationary mechanism is extremely sensitive to UV-physics, the construction of theoretically robust models of inflation provides a unique window on Planck scale physics. We review efforts to use an axion with a shift symmetry to ensure a prolonged slow-roll background evolution. The symmetry dictates which operators are allowed, and these in turn determine the observational predictions of this class of models, which include observable gravitational waves (potentially chiral), oscillations in all primordial correlators, specific deviations from scale invariance and Gaussianity and primordial black holes. We discuss the constraints on this class of models in light of the recent Planck results and comment on future perspectives. The shift symmetry is very useful in models of large-field inflation, which typically have monomial potentials, but it cannot explain why two or more terms in the potential are fine-tuned against each other, as needed for typical models of small-field inflation. Therefore some additional symmetries or fine tuning will be needed if forthcoming experiments will constrain the tensor-to-scalar ratio to be r ? 0.01.

Pajer, Enrico; Peloso, Marco

2013-11-01

79

Localizability and the planck mass  

SciTech Connect

The author combines the assumption of environmental decoherence, as the mechanism generating the classical (i.e. no quantum interferences) nature of spacetime, with the limit on its other classical feature, point-like continuity, namely Planck length. As a result, quantum extended objects with masses larger than Planck mass have to derive their quantum behavior from long-range correlations; objects with masses smaller than Planck mass cannot display classical behavior.

Ne`eman, Y. [Tel-Aviv Univ. (Israel). Sackler Faculty of Exact Sciences]|[Univ. of Texas, Austin, TX (United States). Center for Particle Physics

1993-06-01

80

Model of cosmology and particle physics at an intermediate scale  

SciTech Connect

We propose a model of cosmology and particle physics in which all relevant scales arise in a natural way from an intermediate string scale. We are led to assign the string scale to the intermediate scale M{sub *}{approx}10{sup 13} GeV by four independent pieces of physics: electroweak symmetry breaking; the {mu} parameter; the axion scale; and the neutrino mass scale. The model involves hybrid inflation with the waterfall field N being responsible for generating the {mu} term, the right-handed neutrino mass scale, and the Peccei-Quinn symmetry breaking scale. The large scale structure of the Universe is generated by the lightest right-handed sneutrino playing the role of a coupled curvaton. We show that the correct curvature perturbations may be successfully generated providing the lightest right-handed neutrino is weakly coupled in the seesaw mechanism, consistent with sequential dominance.

Bastero-Gil, M. [Centre of Theoretical Physics, University of Sussex, Falmer, Brighton, BN1 9QJ (United Kingdom); Di Clemente, V. [Department of Theoretical Physics, University of Oxford, 1, Keble Road, Oxford OX1 3NP (United Kingdom); King, S. F. [Department of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ (United Kingdom)

2005-05-15

81

Semiconductor Device Scaling: Physics, Transport, and the Role of Nanowires  

Microsoft Academic Search

Nanoelectronics generally refers to nanometer scale devices, and to circuits and architectures which are composed of these devices. Continued scaling of the devices into the nanometer range leads to enhanced information processing systems. Generally, this scaling has arisen from three major sources, one of which is reduction of the physical gate length of individual transistors. Until recently, this has also

D. K. Ferry; R. Akis; A. Cummings; M. J. GilbertT; S. M. Ramey

2006-01-01

82

Neutrino anisotropies after Planck  

NASA Astrophysics Data System (ADS)

We present new constraints on the rest-frame sound speed, ceff2, and the viscosity parameter, cvis2, of the cosmic neutrino background from the recent measurements of the cosmic microwave background anisotropies provided by the Planck satellite. While broadly consistent with the expectations of ceff2=cvis2=1/3 in the standard scenario, the Planck data set hints at a higher value of the viscosity parameter, with cvis2=0.60±0.18 at 68% C.L., and a lower value of the sound speed, with ceff2=0.304±0.013 at 68% C.L. We find a correlation between the neutrino parameters and the lensing amplitude of the temperature power spectrum AL. When the latter parameter is allowed to vary, we find a better consistency with the standard model with cvis2=0.51±0.22, ceff2=0.311±0.019, and AL=1.08±0.18 at 68% C.L. This result indicates that the anomalous large value of AL measured by Planck could be connected to nonstandard neutrino properties. Including additional data sets from baryon acoustic oscillation surveys and the Hubble Space Telescope constraint on the Hubble constant, we obtain cvis2=0.40±0.19, ceff2=0.319±0.019, and AL=1.15±0.17 at 68% C.L.; including the lensing power spectrum, we obtain cvis2=0.50±0.19, ceff2=0.314±0.015, and AL=1.025±0.076 at 68% C.L. Finally, we investigate further degeneracies between the clustering parameters and other cosmological parameters.

Gerbino, Martina; Di Valentino, Eleonora; Said, Najla

2013-09-01

83

Planck Length and Cosmology  

NASA Astrophysics Data System (ADS)

We show that an unification of quantum mechanics and general relativity implies that there is a fundamental length in Nature in the sense that no operational procedure would be able to measure distances shorter than the Planck length. Furthermore we give an explicit realization of an old proposal by Anderson and Finkelstein who argued that a fundamental length in nature implies unimodular gravity. Finally, using hand waving arguments we show that a minimal length might be related to the cosmological constant which, if this scenario is realized, is time dependent.

Calmet, Xavier

84

Change and Hope in Physics  

Microsoft Academic Search

Physics = Ideas + Analyses. Newton reconciled Kepler's laws, Einstein's GR reconciled action at a distance. Our Planck Scale Statistics (see v3 and v4 of [1]) is a change that reconciles gravity with quantum physics simply. It does what a change should do and I will answer your questions again. It completes TOE, so what? There should not be any

Shantilal Goradia

2009-01-01

85

Planck pre-launch status: The Planck mission  

Microsoft Academic Search

The European Space Agency's Planck satellite, launched on 14 May 2009, is the third-generation space experiment in the field of cosmic microwave background (CMB) research. It will image the anisotropies of the CMB over the whole sky, with unprecedented sensitivity ({{Delta T}over T} 2 × 10-6) and angular resolution ( 5 arcmin). Planck will provide a major source of information

J. A. Tauber; N. Mandolesi; J.-L. Puget; T. Banos; M. Bersanelli; F. R. Bouchet; R. C. Butler; J. Charra; G. Crone; J. Dodsworth; G. Efstathiou; R. Gispert; G. Guyot; A. Gregorio; J. J. Juillet; J.-M. Lamarre; R. J. Laureijs; C. R. Lawrence; H. U. Nørgaard-Nielsen; T. Passvogel; J. M. Reix; D. Texier; L. Vibert; A. Zacchei; P. A. R. Ade; N. Aghanim; B. Aja; E. Alippi; L. Aloy; P. Armand; M. Arnaud; A. Arondel; A. Arreola-Villanueva; E. Artal; E. Artina; A. Arts; M. Ashdown; J. Aumont; M. Azzaro; A. Bacchetta; C. Baccigalupi; M. Baker; M. Balasini; A. Balbi; A. J. Banday; G. Barbier; R. B. Barreiro; M. Bartelmann; P. Battaglia; E. Battaner; K. Benabed; J.-L. Beney; R. Beneyton; K. Bennett; A. Benoit; J.-P. Bernard; P. Bhandari; R. Bhatia; M. Biggi; R. Biggins; G. Billig; Y. Blanc; H. Blavot; J. J. Bock; A. Bonaldi; R. Bond; J. Bonis; J. Borders; J. Borrill; L. Boschini; F. Boulanger; J. Bouvier; M. Bouzit; R. Bowman; E. Bréelle; T. Bradshaw; M. Braghin; M. Bremer; D. Brienza; D. Broszkiewicz; C. Burigana; M. Burkhalter; P. Cabella; T. Cafferty; M. Cairola; S. Caminade; P. Camus; C. M. Cantalupo; B. Cappellini; J.-F. Cardoso; R. Carr; A. Catalano; L. Cayón; M. Cesa; M. Chaigneau; A. Challinor; A. Chamballu; J. P. Chambelland; M. Charra; L.-Y. Chiang; G. Chlewicki; P. R. Christensen; S. Church; E. Ciancietta; M. Cibrario; R. Cizeron; D. Clements; B. Collaudin; J.-M. Colley; S. Colombi; A. Colombo; F. Colombo; O. Corre; F. Couchot; B. Cougrand; A. Coulais; P. Couzin; B. Crane; B. Crill; M. Crook; D. Crumb; F. Cuttaia; U. Dörl; P. da Silva; R. Daddato; C. Damasio; L. Danese; G. D'Aquino; O. D'Arcangelo; K. Dassas; R. D. Davies; W. Davies; R. J. Davis; P. de Bernardis; D. de Chambure; G. de Gasperis; M. L. de La Fuente; P. de Paco; A. de Rosa; G. de Troia; G. de Zotti; M. Dehamme; J. Delabrouille; J.-M. Delouis; F.-X. Désert; G. di Girolamo; C. Dickinson; E. Doelling; K. Dolag; I. Domken; M. Douspis; D. Doyle; S. Du; D. Dubruel; C. Dufour; C. Dumesnil; X. Dupac; P. Duret; C. Eder; A. Elfving; T. A. Enßlin; K. English; H. K. Eriksen; P. Estaria; M. C. Falvella; F. Ferrari; F. Finelli; A. Fishman; S. Fogliani; S. Foley; A. Fonseca; G. Forma; O. Forni; P. Fosalba; J.-J. Fourmond; M. Frailis; C. Franceschet; E. Franceschi; S. François; M. Frerking; M. F. Gómez-Reñasco; K. M. Górski; T. C. Gaier; S. Galeotta; K. Ganga; J. García Lázaro; A. Garnica; M. Gaspard; E. Gavila; M. Giard; G. Giardino; G. Gienger; Y. Giraud-Heraud; J.-M. Glorian; M. Griffin; A. Gruppuso; L. Guglielmi; D. Guichon; B. Guillaume; P. Guillouet; J. Haissinski; F. K. Hansen; J. Hardy; D. Harrison; A. Hazell; M. Hechler; V. Heckenauer; D. Heinzer; R. Hell; S. Henrot-Versillé; C. Hernández-Monteagudo; D. Herranz; J. M. Herreros; V. Hervier; A. Heske; A. Heurtel; S. R. Hildebrandt; R. Hills; E. Hivon; M. Hobson; D. Hollert; W. Holmes; A. Hornstrup; W. Hovest; R. J. Hoyland; G. Huey; K. M. Huffenberger; N. Hughes; U. Israelsson; B. Jackson; A. Jaffe; T. R. Jaffe; T. Jagemann; N. C. Jessen; J. Jewell; W. Jones; M. Juvela; J. Kaplan; P. Karlman; F. Keck; E. Keihänen; M. King; T. S. Kisner; P. Kletzkine; R. Kneissl; J. Knoche; L. Knox; T. Koch; M. Krassenburg; H. Kurki-Suonio; A. Lähteenmäki; G. Lagache; E. Lagorio; P. Lami; J. Lande; A. Lange; F. Langlet; R. Lapini; M. Lapolla; A. Lasenby; M. Le Jeune; J. P. Leahy; M. Lefebvre; F. Legrand; G. Le Meur; R. Leonardi; B. Leriche; C. Leroy; P. Leutenegger; S. M. Levin; P. B. Lilje; C. Lindensmith; M. Linden-Vørnle; A. Loc; Y. Longval; P. M. Lubin; T. Luchik; I. Luthold; J. F. Macias-Perez; T. Maciaszek; C. MacTavish; S. Madden; B. Maffei; C. Magneville; D. Maino; A. Mambretti; B. Mansoux; D. Marchioro; M. Maris; F. Marliani; J.-C. Marrucho; J. Martí-Canales; E. Martínez-González; A. Martín-Polegre; P. Martin; C. Marty; W. Marty; S. Masi; M. Massardi; S. Matarrese; F. Matthai; P. Mazzotta; A. McDonald; P. McGrath; A. Mediavilla; P. R. Meinhold; J.-B. Mélin; F. Melot; L. Mendes; A. Mennella; C. Mervier; L. Meslier; M. Miccolis; M.-A. Miville-Deschenes; A. Moneti; D. Montet; L. Montier; J. Mora; G. Morgante; G. Morigi; G. Morinaud; N. Morisset; D. Mortlock; S. Mottet; J. Mulder; D. Munshi; A. Murphy; P. Murphy; P. Musi; J. Narbonne; P. Naselsky; A. Nash; F. Nati; P. Natoli; B. Netterfield; J. Newell; M. Nexon; C. Nicolas; P. H. Nielsen; N. Ninane; F. Noviello; D. Novikov; I. Novikov; I. J. O'Dwyer; P. Oldeman; P. Olivier; L. Ouchet; C. A. Oxborrow; L. Pérez-Cuevas; L. Pagan; C. Paine; F. Pajot; R. Paladini; F. Pancher; J. Panh; G. Parks; P. Parnaudeau; B. Partridge; B. Parvin; J. P. Pascual; F. Pasian; D. P. Pearson; T. Pearson; M. Pecora; O. Perdereau; L. Perotto; F. Perrotta; F. Piacentini; M. Piat; E. Pierpaoli; O. Piersanti; E. Plaige; S. Plaszczynski; P. Platania; E. Pointecouteau; G. Polenta; N. Ponthieu; L. Popa; G. Poulleau; T. Poutanen

2010-01-01

86

Scaling and Renormalization in Statistical Physics  

Microsoft Academic Search

This text provides a thoroughly modern graduate-level introduction to the theory of critical behavior. Beginning with a brief review of phase transitions in simple systems and of mean field theory, the text then goes on to introduce the core ideas of the renormalization group. Following chapters cover phase diagrams, fixed points, cross-over behavior, finite-size scaling, perturbative renormalization methods, low-dimensional systems,

John Cardy

1996-01-01

87

Validation Studies of the Physical Activity Scale (PAS)  

Cancer.gov

Validation Studies of the Physical Activity Scale (PAS) Aadahl et al. 2003 See reference #61 Methods Relation between PAS and 4 d of accelerometry (CSA 7164) and physical activity diary in 40 volunteer men (Spearman rank-order correlation) Sample 40

88

Psychometric Properties of the Commitment to Physical Activity Scale  

ERIC Educational Resources Information Center

Objective: To assess psychometric properties of the Commitment to Physical Activity Scale (CPAS). Methods: Girls in third to fifth grades (n = 932) completed the CPAS before and after a physical activity intervention. Psychometric measures included internal consistency, factor analysis, and concurrent validity. Results: Three CPAS factors emerged:…

DeBate, Rita DiGioacchino; Huberty, Jennifer; Pettee, Kelley

2009-01-01

89

PAQ database: Physical Activity Scale for the Elderly (PASE)  

Cancer.gov

Physical Activity Scale for the Elderly (PASE) In: Pereira MA, FitzGerald SJ, Gregg EW, Joswiak ML, Ryan WJ, Suminski RR, Utter AC, Zmuda JM. A collection of Physical Activity Questionnaires for health-related research. Med Sci Sports Exerc 1997 Jun;29(6

90

Determining Planck's Constant with LEDs  

NSDL National Science Digital Library

This resource, created by Dean Zollman of Kansas State University, discusses plank's constant and how it can be determined with the use of a light emitting diode (LED). Additionally, it discusses the Planck relation, Planck's constant and threshold voltage, accepted values and provides a complete analysis of these methods. Each section includes a detailed description and contains the mathematical equations to better explain the theories. This resource is a part of the "Visual Quantum Mechanics Project."

Zollman, Dean

2009-03-26

91

Dust emission of the Milky Way and Magellanic Clouds with PLANCK  

NASA Astrophysics Data System (ADS)

Observations of the dust emission in the Far-IR have made tremendous progress over the past 30 years, starting with airborne and ground-based instruments, which were quickly made obsolete by satellite observations. Simultaneously, balloon-borne experiments allowed us to track the dust emission up to the sub-mm domain, at angular resolutions comparable to that of IRAS. Most recently, the advent of the Herschel Space Observatory and of the Planck satellite has fully opened the FIR-mm observation window. I will review some of the recent Planck results related to the physics of large dust grains in our galaxy and the nearby Large and Small Magellanic Clouds. These results largely confirm those obtained with earlier missions. In particular that the dust SED is flatter than expected and shows variations with wavelength and potentially with dust temperature, environment and metalicity. These results indicate that the FIR-submm emission of thermal dust is complex and variable. The possible reasons for that, such as the presence of very cold dust, spinning dust, the mechanical structure of dust grains, the aggregation of dust particles will be discussed. I will also discuss the use of the Planck data to trace total gas column density in our galaxy, which evidences the existence of an elusive ``Dark-Gas'' component not traced by the available large-scale gas surveys. Finally, I will talk about the prospect of dust polarization measurements with Planck and what they will bring to our understanding of dust physics and magnetic structure of the ISM. These themes are not only important to our understanding of dust properties in distant galaxies, but also to the removal of galactic foreground emission for CMB cosmology.

Bernard, Jean-Philippe

2012-07-01

92

Physical Phenomena and Length Scales Governing the Behaviour of Wildfires: A Case for Physical Modelling  

Microsoft Academic Search

This paper is an overview of the physical mechanisms and length scales governing the propagation of wildfires. One of the\\u000a objectives is to identify the physical and mathematical constraints in the modelling of wildfires when using a “fully” physical\\u000a approach. The literature highlights two regimes in the propagation of surface fires, i.e. wind-driven fires and plume-dominated\\u000a fires, which are governed

Dominique Morvan

2011-01-01

93

The physical basis of glacier volume-area scaling  

USGS Publications Warehouse

Ice volumes are known for only a few of the roughly 160,000 glaciers worldwide but are important components of many climate and sea level studies which require water flux estimates. A scaling analysis of the mass and momentum conservation equations shows that glacier volumes can be related by a power law to more easily observed glacier surface areas. The relationship requires four closure choices for the scaling behavior of glacier widths, slopes, side drag and mass balance. Reasonable closures predict a volume-area scaling exponent which is consistent with observations, giving a physical and practical basis for estimating ice volumes. Glacier volume is insensitive to perturbations in the mass balance scaling, but changes in average accumulation area ratios reflect significant changes in the scaling of both mass balance and ice volume. Copyright 1997 by the American Geophysical Union.

Bahr, D. B.; Meier, M. F.; Peckham, S. D.

1997-01-01

94

Large-Scale Physical Separation of Depleted Uranium from Soil.  

National Technical Information Service (NTIS)

Dry physical separation processes were tested at large-pilot scale (1,000 kg soil batches) at Yuma Proving Ground (YPG) to evaluate this technique for removal of depleted uranium (DU) metal from soil. Two sample locations, the Catch Box and the Buried DU ...

C. Griggs J. Ballard M. Wynter S. L. Larson V. F. Medina

2012-01-01

95

Linear Scale-Space Theory from Physical Principles  

Microsoft Academic Search

In the past decades linear scale-space theory was derived on the basis of various axiomatics. In this paper we revisit these axioms and show that they merely coincide with the following physical principles, namely that the image domain is a Galilean space, that the total energy exchange between a region and its surrounding is preserved under linear filtering and that

Alfons H. Salden; Bart M. ter Haar Romeny; Max A. Viergever

1998-01-01

96

Physical Process Time and Space Scales Related to River Restoration  

Microsoft Academic Search

River restoration studies need to consider stream dynamics, evolution, rates of adjustment, and relative effects of various human disturbances. The history of stream channel adjustment typically needs to be investigated over a time scale of decades to centuries to include the time before human disturbance. An investigation of historical change will help with understanding the processes of physical change, how

T. Randle; J. Boutry

2005-01-01

97

2D VARIABLY SATURATED FLOWS: PHYSICAL SCALING AND BAYESIAN ESTIMATION  

EPA Science Inventory

A novel dimensionless formulation for water flow in two-dimensional variably saturated media is presented. It shows that scaling physical systems requires conservation of the ratio between capillary forces and gravity forces. A direct result of this finding is that for two phys...

98

Poisson-Boltzmann-Nernst-Planck model  

PubMed Central

The Poisson–Nernst–Planck (PNP) model is based on a mean-field approximation of ion interactions and continuum descriptions of concentration and electrostatic potential. It provides qualitative explanation and increasingly quantitative predictions of experimental measurements for the ion transport problems in many areas such as semiconductor devices, nanofluidic systems, and biological systems, despite many limitations. While the PNP model gives a good prediction of the ion transport phenomenon for chemical, physical, and biological systems, the number of equations to be solved and the number of diffusion coefficient profiles to be determined for the calculation directly depend on the number of ion species in the system, since each ion species corresponds to one Nernst–Planck equation and one position-dependent diffusion coefficient profile. In a complex system with multiple ion species, the PNP can be computationally expensive and parameter demanding, as experimental measurements of diffusion coefficient profiles are generally quite limited for most confined regions such as ion channels, nanostructures and nanopores. We propose an alternative model to reduce number of Nernst–Planck equations to be solved in complex chemical and biological systems with multiple ion species by substituting Nernst–Planck equations with Boltzmann distributions of ion concentrations. As such, we solve the coupled Poisson–Boltzmann and Nernst–Planck (PBNP) equations, instead of the PNP equations. The proposed PBNP equations are derived from a total energy functional by using the variational principle. We design a number of computational techniques, including the Dirichlet to Neumann mapping, the matched interface and boundary, and relaxation based iterative procedure, to ensure efficient solution of the proposed PBNP equations. Two protein molecules, cytochrome c551 and Gramicidin A, are employed to validate the proposed model under a wide range of bulk ion concentrations and external voltages. Extensive numerical experiments show that there is an excellent consistency between the results predicted from the present PBNP model and those obtained from the PNP model in terms of the electrostatic potentials, ion concentration profiles, and current–voltage (I–V) curves. The present PBNP model is further validated by a comparison with experimental measurements of I–V curves under various ion bulk concentrations. Numerical experiments indicate that the proposed PBNP model is more efficient than the original PNP model in terms of simulation time.

Zheng, Qiong; Wei, Guo-Wei

2011-01-01

99

Poisson-Boltzmann-Nernst-Planck model  

NASA Astrophysics Data System (ADS)

The Poisson-Nernst-Planck (PNP) model is based on a mean-field approximation of ion interactions and continuum descriptions of concentration and electrostatic potential. It provides qualitative explanation and increasingly quantitative predictions of experimental measurements for the ion transport problems in many areas such as semiconductor devices, nanofluidic systems, and biological systems, despite many limitations. While the PNP model gives a good prediction of the ion transport phenomenon for chemical, physical, and biological systems, the number of equations to be solved and the number of diffusion coefficient profiles to be determined for the calculation directly depend on the number of ion species in the system, since each ion species corresponds to one Nernst-Planck equation and one position-dependent diffusion coefficient profile. In a complex system with multiple ion species, the PNP can be computationally expensive and parameter demanding, as experimental measurements of diffusion coefficient profiles are generally quite limited for most confined regions such as ion channels, nanostructures and nanopores. We propose an alternative model to reduce number of Nernst-Planck equations to be solved in complex chemical and biological systems with multiple ion species by substituting Nernst-Planck equations with Boltzmann distributions of ion concentrations. As such, we solve the coupled Poisson-Boltzmann and Nernst-Planck (PBNP) equations, instead of the PNP equations. The proposed PBNP equations are derived from a total energy functional by using the variational principle. We design a number of computational techniques, including the Dirichlet to Neumann mapping, the matched interface and boundary, and relaxation based iterative procedure, to ensure efficient solution of the proposed PBNP equations. Two protein molecules, cytochrome c551 and Gramicidin A, are employed to validate the proposed model under a wide range of bulk ion concentrations and external voltages. Extensive numerical experiments show that there is an excellent consistency between the results predicted from the present PBNP model and those obtained from the PNP model in terms of the electrostatic potentials, ion concentration profiles, and current-voltage (I-V) curves. The present PBNP model is further validated by a comparison with experimental measurements of I-V curves under various ion bulk concentrations. Numerical experiments indicate that the proposed PBNP model is more efficient than the original PNP model in terms of simulation time.

Zheng, Qiong; Wei, Guo-Wei

2011-05-01

100

Poisson-Boltzmann-Nernst-Planck model  

SciTech Connect

The Poisson-Nernst-Planck (PNP) model is based on a mean-field approximation of ion interactions and continuum descriptions of concentration and electrostatic potential. It provides qualitative explanation and increasingly quantitative predictions of experimental measurements for the ion transport problems in many areas such as semiconductor devices, nanofluidic systems, and biological systems, despite many limitations. While the PNP model gives a good prediction of the ion transport phenomenon for chemical, physical, and biological systems, the number of equations to be solved and the number of diffusion coefficient profiles to be determined for the calculation directly depend on the number of ion species in the system, since each ion species corresponds to one Nernst-Planck equation and one position-dependent diffusion coefficient profile. In a complex system with multiple ion species, the PNP can be computationally expensive and parameter demanding, as experimental measurements of diffusion coefficient profiles are generally quite limited for most confined regions such as ion channels, nanostructures and nanopores. We propose an alternative model to reduce number of Nernst-Planck equations to be solved in complex chemical and biological systems with multiple ion species by substituting Nernst-Planck equations with Boltzmann distributions of ion concentrations. As such, we solve the coupled Poisson-Boltzmann and Nernst-Planck (PBNP) equations, instead of the PNP equations. The proposed PBNP equations are derived from a total energy functional by using the variational principle. We design a number of computational techniques, including the Dirichlet to Neumann mapping, the matched interface and boundary, and relaxation based iterative procedure, to ensure efficient solution of the proposed PBNP equations. Two protein molecules, cytochrome c551 and Gramicidin A, are employed to validate the proposed model under a wide range of bulk ion concentrations and external voltages. Extensive numerical experiments show that there is an excellent consistency between the results predicted from the present PBNP model and those obtained from the PNP model in terms of the electrostatic potentials, ion concentration profiles, and current-voltage (I-V) curves. The present PBNP model is further validated by a comparison with experimental measurements of I-V curves under various ion bulk concentrations. Numerical experiments indicate that the proposed PBNP model is more efficient than the original PNP model in terms of simulation time.

Zheng Qiong [Department of Mathematics, Michigan State University, East Lansing, Michigan 48824 (United States); Wei Guowei [Department of Mathematics, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824 (United States)

2011-05-21

101

Poisson-Boltzmann-Nernst-Planck model.  

PubMed

The Poisson-Nernst-Planck (PNP) model is based on a mean-field approximation of ion interactions and continuum descriptions of concentration and electrostatic potential. It provides qualitative explanation and increasingly quantitative predictions of experimental measurements for the ion transport problems in many areas such as semiconductor devices, nanofluidic systems, and biological systems, despite many limitations. While the PNP model gives a good prediction of the ion transport phenomenon for chemical, physical, and biological systems, the number of equations to be solved and the number of diffusion coefficient profiles to be determined for the calculation directly depend on the number of ion species in the system, since each ion species corresponds to one Nernst-Planck equation and one position-dependent diffusion coefficient profile. In a complex system with multiple ion species, the PNP can be computationally expensive and parameter demanding, as experimental measurements of diffusion coefficient profiles are generally quite limited for most confined regions such as ion channels, nanostructures and nanopores. We propose an alternative model to reduce number of Nernst-Planck equations to be solved in complex chemical and biological systems with multiple ion species by substituting Nernst-Planck equations with Boltzmann distributions of ion concentrations. As such, we solve the coupled Poisson-Boltzmann and Nernst-Planck (PBNP) equations, instead of the PNP equations. The proposed PBNP equations are derived from a total energy functional by using the variational principle. We design a number of computational techniques, including the Dirichlet to Neumann mapping, the matched interface and boundary, and relaxation based iterative procedure, to ensure efficient solution of the proposed PBNP equations. Two protein molecules, cytochrome c551 and Gramicidin A, are employed to validate the proposed model under a wide range of bulk ion concentrations and external voltages. Extensive numerical experiments show that there is an excellent consistency between the results predicted from the present PBNP model and those obtained from the PNP model in terms of the electrostatic potentials, ion concentration profiles, and current-voltage (I-V) curves. The present PBNP model is further validated by a comparison with experimental measurements of I-V curves under various ion bulk concentrations. Numerical experiments indicate that the proposed PBNP model is more efficient than the original PNP model in terms of simulation time. PMID:21599038

Zheng, Qiong; Wei, Guo-Wei

2011-05-21

102

Reactor Physics Methods and Analysis Capabilities in SCALE  

SciTech Connect

The TRITON sequence of the SCALE code system provides a powerful, robust, and rigorous approach for performing reactor physics analysis. This paper presents a detailed description of TRITON in terms of its key components used in reactor calculations. The ability to accurately predict the nuclide composition of depleted reactor fuel is important in a wide variety of applications. These applications include, but are not limited to, the design, licensing, and operation of commercial/research reactors and spent-fuel transport/storage systems. New complex design projects such as next-generation power reactors and space reactors require new high-fidelity physics methods, such as those available in SCALE/TRITON, that accurately represent the physics associated with both evolutionary and revolutionary reactor concepts as they depart from traditional and well-understood light water reactor designs.

Mark D. DeHart; Stephen M. Bowman

2011-05-01

103

Physical scales in the Wigner-Boltzmann equation  

PubMed Central

The Wigner–Boltzmann equation provides the Wigner single particle theory with interactions with bosonic degrees of freedom associated with harmonic oscillators, such as phonons in solids. Quantum evolution is an interplay of two transport modes, corresponding to the common coherent particle-potential processes, or to the decoherence causing scattering due to the oscillators. Which evolution mode will dominate depends on the scales of the involved physical quantities. A dimensionless formulation of the Wigner–Boltzmann equation is obtained, where these scales appear as dimensionless strength parameters. A notion called scaling theorem is derived, linking the strength parameters to the coupling with the oscillators. It is shown that an increase of this coupling is equivalent to a reduction of both the strength of the electric potential, and the coherence length. Secondly, the existence of classes of physically different, but mathematically equivalent setups of the Wigner–Boltzmann evolution is demonstrated.

Nedjalkov, M.; Selberherr, S.; Ferry, D.K.; Vasileska, D.; Dollfus, P.; Querlioz, D.; Dimov, I.; Schwaha, P.

2013-01-01

104

Large-scale simulations of complex physical systems  

SciTech Connect

Scientific computing has become a tool as vital as experimentation and theory for dealing with scientific challenges of the twenty-first century. Large scale simulations and modelling serve as heuristic tools in a broad problem-solving process. High-performance computing facilities make possible the first step in this process - a view of new and previously inaccessible domains in science and the building up of intuition regarding the new phenomenology. The final goal of this process is to translate this newly found intuition into better algorithms and new analytical results.In this presentation we give an outline of the research themes pursued at the Scientific Computing Laboratory of the Institute of Physics in Belgrade regarding large-scale simulations of complex classical and quantum physical systems, and present recent results obtained in the large-scale simulations of granular materials and path integrals.

Belic, A. [Scientific Computing Laboratory, Institute of Physics, Pregrevica 118, 11080 Belgrade (Serbia and Montenegro)

2007-04-23

105

Physical Origins of Statistical Scale Invariance or Scaling in Peak Flows in Real River Networks  

NASA Astrophysics Data System (ADS)

For nearly forty years, regional flood frequency analyses in unnested and in nested basins have shown that annual peak-flow quantiles can be related to drainage areas as power laws that arise from the property of scale invariance. This empirical feature has instigated a basic hydrologic question: Can power laws be obtained from physical processes governing rainfall-runoff transformations on real channel networks? There has been steady progress in answering this question since 1990. A physical understanding of peak flow scaling requires the time scales of individual rainfall-runoff events as a first step before going to longer time scales. We have used data from two Agriculture Research Service (ARS) experimental basins in the United States to test the physical basis of scaling in peak flows. The first basin is Goodwin Creek in Mississippi (21 km2), and the second one is Walnut Gulch in Arizona (150 km2). We have tested the hypothesis that scaling parameters of individual flood events on Goodwin Creek vary from one event to the next due to the effect of temporal rainfall variability. On the Walnut Gulch, we have tested the hypothesis that scaling in peak flows for short duration rainfall events is controlled by the river network topological and geometric configuration and the downstream hydraulic-geometric properties. Based on these results we present a gauging strategy to investigate peak flow scaling in the 1100 km2 Whitewater basin in Kansas.

Mantilla, R.; Gupta, V. K.; Furey, P.

2005-12-01

106

Physics of Multi-scale Convection In The Earth's Mantle  

NASA Astrophysics Data System (ADS)

We investigate the physics of multi-scale convection in the Earth's mantle, character- ized by the coexistence of large-scale mantle circulation associated plate tectonics and small-scale sublithospheric convection. Several basic scaling laws are derived, using a series of 2-D numerical modeling and 3-D linear stability analyses, for the following three distinct phases of sublithospheric convection: (1) onset of convection, (2) lay- ered convection in the upper mantle, and (3) breakdown of layered convection. First, the onset of convection with temperature-dependent viscosity is studied with 2-D con- vection models. A robust scaling law for onset time is derived by a nonlinear scaling analysis based on the concept of the differential Rayleigh number. Next, the planform of sublithospheric convection is studied by a 3-D linear stability analysis of longitu- dinal rolls in the presence of vertical shear. Finally, the temporal and spatial evolu- tion of sublithospheric convection is studied by 2-D whole-mantle convection models with temperature- and depth-dependent viscosity and an endothermic phase transition. Scaling laws for the breakdown of layered convection as well as the strength of con- vection are derived as a function of viscosity layering, the phase buoyancy parameter, and the thermal Rayleigh number. All of these scaling laws are combined to delineate possible dynamic regimes beneath evolving lithosphere.

Korenaga, J.; Jordan, T. H.

107

Planck early results. VIII. ESZ sample. (Planck+, 2011)  

NASA Astrophysics Data System (ADS)

We present the first all-sky sample of galaxy clusters detected blindly by the Planck satellite through the Sunyaev-Zeldovich (SZ) effect from its six highest frequencies. This early SZ (ESZ) sample is comprised of 189 candidates, which have a high signal-to-noise ratio ranging from 6 to 29. Its high reliability (purity above 95%) is further ensured by an extensive validation process based on Planck internal quality assessments and by external cross-identification and follow-up observations. Planck provides the first measured SZ signal for about 80% of the 169 previously-known ESZ clusters. Planck furthermore releases 30 new cluster candidates, amongst which 20 meet the ESZ signal-to-noise selection criterion. At the submission date, twelve of the 20 ESZ candidates were confirmed as new clusters, with eleven confirmed using XMM-Newton snapshot observations, most of them with disturbed morphologies and low luminosities. The ESZ clusters are mostly at moderate redshifts (86% with z below 0.3) and span more than a decade in mass, up to the rarest and most massive clusters with masses above 1x1015M?. (1 data file).

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Baker, M.; Balbi, A.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Bennett, K.; Benoit, A.; Bernard, J.-P.; Bersanelli, M.; Bhatia, R.; Bock, J. J.; Bonaldi, A.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Bradshaw, T.; Bremer, M.; Bucher, M.; Burigana, C.; Butler, R. C.; Cabella, P.; Cantalupo, C. M.; Cappellini, B.; Cardoso, J.-F.; Carr, R.; Casale, M.; Catalano, A.; Cayon, L.; Challinor, A.; Chamballu, A.; Charra, J.; Chary, R.-R.; Chiang, L.-Y.; Chiang, C.; Christensen, P. R.; Clements, D. L.; Colombi, S.; Couchot, F.; Coulais, A.; Crill, B. P.; Crone, G.; Crook, M.; Cuttaia, F.; Danese, L.; D'Arcangelo, O.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Bruin, J.; de Gasperis, G.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Desert, F.-X.; Dick, J.; Dickinson, C.; Dolag, K.; Dole, H.; Donzelli, S.; Dore, O.; Doerl, U.; Douspis, M.; Dupac, X.; Efstathiou, G.; Ensslin, T. A.; Eriksen, H. K.; Finelli, F.; Foley, S. ., Forni O., Fosalba P., Frailis M., Franceschi E., Freschi M., Gaier T.C., Galeotta S., Gallegos J., Gandolfo B., Ganga K., Giard M., Giardino G., Gienger G., Giraud-Heraud Y., Gonzalez J., Gonzalez-Nuevo J., Gorski K.M., Gratton S., Gregorio A., Gruppuso A., Guyot G., Haissinski J., Hansen F.K., Harrison D., Helou G., Henrot-Versille S., Hernandez-Monteagudo C., Herranz D., Hildebrandt S.R., Hivon E., Hobson M., Holmes W.A., Hornstrup A., Hovest W., Hoyland R.J., Huffenberger K.M., Jaffe A.H., Jagemann T., Jones W.C., Juillet J.J., Juvela M., Kangaslahti P., Keihaenen E., Keskitalo R., Kisner T.S., Kneissl R., Knox L., Krassenburg M., Kurki-Suonio H., Lagache G., Laehteenmaeki A., Lamarre J.-M., Lange A.E., Lasenby A., Laureijs R.J., Lawrence C.R., Leach S., Leahy J.P., Leonardi R., Leroy C., Lilje P.B., Linden-Vornle M., Lopez-Caniego M., Lowe S., Lubin P.M., Macias-Perez J.F., Maciaszek T., Mactavish C.J., Maffei B., Maino D., Mandolesi N., Mann R., Maris M., Martinez-Go nzalez E., Masi S., Massardi M., Matarrese S., Matthai F., Mazzotta P., McDonald A., McGehee P., Meinhold P.R., Melchiorri A., Melin J.-B., Mendes L., Mennella A., Mevi C., Miniscalco R., Mitra S., Miville-Deschenes M.-A., Moneti A., Montier L., Morgante G., Morisset N., Mortlock D., Munshi D., Murphy A., Naselsky P., Natoli P., Netterfield C.B., Norgaard-Nielsen H.U., Noviello F., Novikov D., Novikov I., O'dwyer I.J., Ortiz I., Osborne S., Osuna P., Oxborrow C.A., Pajot F., Paladini R., Partridge B., Pasian F., Passvogel T., Patanchon G., Pearson D., Pearson T.J., Perdereau O., Perotto L., Perrotta F., Piacentini F., Piat M., Pierpaoli E., Plaszczynski S., Platania P., Pointecouteau E., Polenta G., Ponthieu N., Popa L., Poutanen T., Prezeau G., Prunet S., Puget J.-L., Rachen J.P., Reach W.T., Rebolo R., Reinecke M., Reix J.-M., Renault C., Ricciardi S., Riller T., Ristorcelli I., Rocha G., Rosset C., Rowan-Robinson M., Rubino-Martin J.A., Rusholme B., Salerno E., Sandri M., Santos D., Savini G., Schaefer B.M., Scott D., Seiffert M.D., Shellard P., Simonetto A., Smoot G.F., Sozzi C., Starck J.-L., Sternberg J., Stivoli F., Stolyarov V., Stompor R., Stringhetti L., Sudiwala R., Sunyaev R., Sygnet J.-F., Tapiador D., Tauber J.A., Tavagnacco D., Taylor D., Terenzi L., Texier D., Toffolatti L., Tomasi M., Torre J.-P., Tristram M., Tuovinen J., Tuerler M., Tuttlebee M., Umana G., Valenziano L., Valiviita J., Varis J., Vibert L., Vielva P., Villa F., Vittorio N., Wade L.A., Wandelt B.D., Watson C., White S.D.M., White M., Wilkinson A., Yvon D., Zacchei A., Zonca A.

2012-02-01

108

Planck early results. II. The thermal performance of Planck  

Microsoft Academic Search

The performance of the Planck instruments in space is enabled by their low operating temperatures, 20 K for LFI and 0.1 K for HFI, achieved through a combination of passive radiative cooling and three active mechanical coolers. The scientific requirement for very broad frequency coverage led to two detector technologies with widely different temperature and cooling needs. Active coolers could

P. A. R. Ade; N. Aghanim; M. Arnaud; M. Ashdown; J. Aumont; C. Baccigalupi; M. Baker; A. Balbi; A. J. Banday; R. B. Barreiro; E. Battaner; K. Benabed; A. Benoît; J.-P. Bernard; M. Bersanelli; P. Bhandari; R. Bhatia; J. J. Bock; A. Bonaldi; J. R. Bond; J. Borders; J. Borrill; B. Bowman; T. Bradshaw; E. Bréelle; M. Bucher; C. Burigana; R. C. Butler; P. Cabella; C. M. Cantalupo; B. Cappellini; J.-F. Cardoso; A. Catalano; L. Cayón; A. Challinor; A. Chamballu; J. P. Chambelland; J. Charra; M. Charra; L.-Y. Chiang; C. Chiang; P. R. Christensen; D. L. Clements; B. Collaudin; S. Colombi; F. Couchot; A. Coulais; B. P. Crill; M. Crook; F. Cuttaia; C. Damasio; L. Danese; R. D. Davies; R. J. Davis; P. de Bernardis; G. de Gasperis; A. de Rosa; J. Delabrouille; J.-M. Delouis; F.-X. Désert; K. Dolag; S. Donzelli; O. Doré; U. Dörl; M. Douspis; X. Dupac; G. Efstathiou; T. A. Enßlin; H. K. Eriksen; C. Filliard; F. Finelli; S. Foley; O. Forni; P. Fosalba; J.-J. Fourmond; M. Frailis; E. Franceschi; S. Galeotta; K. Ganga; E. Gavila; M. Giard; G. Giardino; Y. Giraud-Héraud; J. González-Nuevo; K. M. Górski; S. Gratton; A. Gregorio; A. Gruppuso; G. Guyot; D. Harrison; G. Helou; S. Henrot-Versillé; C. Hernández-Monteagudo; D. Herranz; S. R. Hildebrandt; E. Hivon; M. Hobson; A. Hornstrup; W. Hovest; R. J. Hoyland; K. M. Huffenberger; U. Israelsson; A. H. Jaffe; W. C. Jones; M. Juvela; E. Keihänen; R. Keskitalo; T. S. Kisner; R. Kneissl; L. Knox; H. Kurki-Suonio; G. Lagache; J.-M. Lamarre; P. Lami; A. Lasenby; R. J. Laureijs; A. Lavabre; C. R. Lawrence; S. Leach; R. Lee; R. Leonardi; C. Leroy; P. B. Lilje; M. López-Caniego; P. M. Lubin; J. F. Macías-Pérez; T. Maciaszek; C. J. MacTavish; B. Maffei; D. Maino; N. Mandolesi; R. Mann; M. Maris; E. Martínez-González; S. Masi; S. Matarrese; F. Matthai; P. Mazzotta; P. McGehee; P. R. Meinhold; A. Melchiorri; F. Melot; L. Mendes; A. Mennella; M.-A. Miville-Deschênes; A. Moneti; L. Montier; J. Mora; G. Morgante; N. Morisset; D. Mortlock; D. Munshi; A. Murphy; P. Naselsky; A. Nash; P. Natoli; C. B. Netterfield; D. Novikov; I. Novikov; I. J. O'Dwyer; S. Osborne; F. Pajot; F. Pasian; G. Patanchon; D. Pearson; O. Perdereau; L. Perotto; F. Perrotta; F. Piacentini; M. Piat; S. Plaszczynski; P. Platania; E. Pointecouteau; G. Polenta; N. Ponthieu; T. Poutanen; G. Prézeau; M. Prina; S. Prunet; J.-L. Puget; J. P. Rachen; R. Rebolo; M. Reinecke; C. Renault; S. Ricciardi; T. Riller; I. Ristorcelli; G. Rocha; C. Rosset; J. A. Rubiño-Martín; B. Rusholme; M. Sandri; D. Santos; G. Savini; B. M. Schaefer; D. Scott; M. D. Seiffert; P. Shellard; G. F. Smoot; J.-L. Starck; P. Stassi; F. Stivoli; V. Stolyarov; R. Stompor; R. Sudiwala; J.-F. Sygnet; J. A. Tauber; L. Terenzi; L. Toffolatti; M. Tomasi; J.-P. Torre; M. Tristram; J. Tuovinen; L. Valenziano; L. Vibert; P. Vielva; F. Villa; N. Vittorio; A. Wilkinson; B. D. Wandelt; C. Watson; S. D. M. White; P. Wilson; D. Yvon; A. Zacchei; B. Zhang; A. Zonca

2011-01-01

109

Planck Visualization Project: Seeing and Hearing the CMB  

NASA Astrophysics Data System (ADS)

The Planck Education and Public Outreach collaborators at the University of California, Santa Barbara and Purdue University have prepared a variety of materials to present the science goals of the Planck Mission to the public. Here we present our interactive simulation of the Cosmic Microwave Background, in which the user can change the ingredients of the universe and hear the different harmonics. We also present how we derive information about the early universe from the power spectrum of the CMB by using the physics of music for the public.

Van Der Veen, Jatila; Lubin, P. M.; 2; Alper, B.; 3; Smith, W.; 4; McGee, R.; 5; US Planck Collaboration

2011-01-01

110

Physical scale modelling of adhered spill plume entrainment  

Microsoft Academic Search

This work provides new experimental data to characterise entrainment of air into adhered thermal spill plumes using physical scale modelling. For the two-dimensional plume, the rate of entrainment with respect to height of rise is approximately half that of an equivalent two-dimensional balcony spill plume. For the three-dimensional plume, the rate of entrainment appears to be linked to the plume

Roger Harrison; Michael Spearpoint

2010-01-01

111

Spectator field models in light of spectral index after Planck  

NASA Astrophysics Data System (ADS)

We revisit spectator field models including curvaton and modulated reheating scenarios, specifically focusing on their viability in the new Planck era, based on the derived expression for the spectral index in general spectator field models. Importantly, the recent Planck observations give strong preference to a red-tilted power spectrum, while the spectator field models tend to predict a scale-invariant one. This implies that, during inflation, either (i) the Hubble parameter varies significantly as in chaotic inflation, or (ii) a scalar potential for the spectator field has a relatively large negative curvature. Combined with the tight constraint on the non-Gaussianity, the Planck data provides us with rich implications for various spectator field models.

Kobayashi, Takeshi; Takahashi, Fuminobu; Takahashi, Tomo; Yamaguchi, Masahide

2013-10-01

112

The Goddard multi-scale modeling system with unified physics  

NASA Astrophysics Data System (ADS)

Recently, a multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (1) a cloud-resolving model (CRM), (2) a regional-scale model, the NASA unified Weather Research and Forecasting Model (WRF), and (3) a coupled CRM-GCM (general circulation model, known as the Goddard Multi-scale Modeling Framework or MMF). The same cloud-microphysical processes, long- and short-wave radiative transfer and land-surface processes are applied in all of the models to study explicit cloud-radiation and cloud-surface interactive processes in this multi-scale modeling system. This modeling system has been coupled with a multi-satellite simulator for comparison and validation with NASA high-resolution satellite data. This paper reviews the development and presents some applications of the multi-scale modeling system, including results from using the multi-scale modeling system to study the interactions between clouds, precipitation, and aerosols. In addition, use of the multi-satellite simulator to identify the strengths and weaknesses of the model-simulated precipitation processes will be discussed as well as future model developments and applications.

Tao, W.-K.; Anderson, D.; Chern, J.; Entin, J.; Hou, A.; Houser, P.; Kakar, R.; Lang, S.; Lau, W.; Peters-Lidard, C.; Li, X.; Matsui, T.; Rienecker, M.; Schoeberl, M. R.; Shen, B.-W.; Shi, J. J.; Zeng, X.

2009-08-01

113

A Goddard Multi-Scale Modeling System with Unified Physics  

NASA Astrophysics Data System (ADS)

Recently, a multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (1) a cloud-resolving model (CRM), (2) a regional-scale model, the NASA unified Weather Research and Forecasting Model (WRF), and (3) a coupled CRM-GCM (general circulation model, known as the Goddard Multi-scale Modeling Framework or MMF). The same cloud-microphysical processes, long- and short-wave radiative transfer and land-surface processes are applied in all of the models to study explicit cloud-radiation and cloud-surface interactive processes in this multi-scale modeling system. This modeling system has been coupled with a multi-satellite simulator for comparison and validation with NASA high-resolution satellite data. This paper reviews the development and presents some applications of the multi-scale modeling system, including results from using the multi-scale modeling system to study the interactions between clouds, precipitation, and aerosols. In addition, use of the multi-satellite simulator to identify the strengths and weaknesses of the model-simulated precipitation processes will be discussed as well as future model developments and applications.

Tao, W.; Chern, J.; Matsui, T.; Li, X.; Peters-Lidard, C. D.; Zeng, X.; Shen, B.; Shi, J. J.; Lang, S.

2009-12-01

114

Microphysics in Multi-scale Modeling Systems with Unified Physics  

NASA Astrophysics Data System (ADS)

A multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (1) a cloud-resolving model (Goddard Cumulus Ensemble model, GCE model), (2) a regional scale model (a NASA unified weather research and forecast, WRF), (3) a coupled CRM and global model (Goddard Multi-scale Modeling Framework, MMF), and (4) a land modeling system. The same microphysical processes, long and short wave radiative transfer and land processes and the explicit cloud-radiation, and cloud-land surface interactive processes are applied in this multi-scale modeling system. This modeling system has been coupled with a multi-satellite simulator to use NASA high-resolution satellite data to identify the strengths and weaknesses of cloud and precipitation processes simulated by the model. In this talk, a review of developments and applications of the multi-scale modeling system will be presented. In particular, the microphysics development and its performance for the multi-scale modeling systems will be presented

Tao, W.; Chern, J.; Lang, S.

2011-12-01

115

Microphysics in Multi-scale Modeling System with Unified Physics  

NASA Astrophysics Data System (ADS)

Recently, a multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (1) a cloud-resolving model (Goddard Cumulus Ensemble model, GCE model), (2) a regional scale model (a NASA unified weather research and forecast, WRF), (3) a coupled CRM and global model (Goddard Multi-scale Modeling Framework, MMF), and (4) a land modeling system. The same microphysical processes, long and short wave radiative transfer and land processes and the explicit cloud-radiation, and cloud-land surface interactive processes are applied in this multi-scale modeling system. This modeling system has been coupled with a multi-satellite simulator to use NASA high-resolution satellite data to identify the strengths and weaknesses of cloud and precipitation processes simulated by the model. In this talk, a review of developments and applications of the multi-scale modeling system will be presented. In particular, the microphysics development and its performance for the multi-scale modeling system will be presented.

Tao, W.-K.

2012-04-01

116

Effective cosmological constant from TeV-scale physics  

SciTech Connect

It has been suggested previously that the observed cosmological constant {Lambda} corresponds to the remnant vacuum energy density of dynamical processes taking place at a cosmic age set by the mass scale M{approx}E{sub ew} of ultramassive particles with electroweak interactions. Here, a simple modification of the nondissipative dynamic equations of q-theory is presented, which produces a remnant vacuum energy density (effective cosmological constant) of the correct order of magnitude. Combined with the observed value of {Lambda}, a first estimate of the required value of the energy scale E{sub ew} ranges from 3 to 9 TeV, depending on the number of species of ultramassive particles and assuming a dissipative coupling constant of order unity. If correct, this estimate implies the existence of new TeV-scale physics beyond the standard model.

Klinkhamer, F. R. [Institute for Theoretical Physics, University of Karlsruhe, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany)

2010-10-15

117

The theory of scale relativity  

SciTech Connect

In this paper, the authors' discussion on the relative character of all scales in nature and on the explicit dependence of physical laws on scale in quantum physics, the authors apply the principle of relativity to scale transformations. This principle, in combination with its breaking above the Einstein-de Broglie wavelength and time, leads to the demonstration of the existence of a universal, absolute and impassable scale in nature, which is invariant under dilation. This lower limit to all lengths is identified with the Planck scale, which now plays for scale the same role as is played by light velocity for motion. The authors get new scale transformations of a Lorentzian form and generalize the de Broglie and Heisenberg relations. As a consequence the high energy length and mass scales now decouple, energy and momentum tending to infinity when resolution tends to the Planck scale, which thus plays the role of the previous zero point. This theory solves the problem of divergence of charge and mass (self-energy) in electrodynamics, implies that the four fundamental couplings (including gravitation) converge at the Planck energy, improves the agreement of GUT predictions with experimental results, and allows one to get precise estimates of the values of the fundamental coupling constants.

Nottale, L. (CNRS, Dept. d'Astrophysique Extragalactique et de Cosmologie, Observatoire de Paris-Meudon, F-92195 Meudon Cedex (France))

1992-08-10

118

Impact of inconsistent density scaling on physical analogue models of continental margin scale salt tectonics  

NASA Astrophysics Data System (ADS)

The influence of inaccuracies in density scaling on the structural evolution of physical analogue experiments of salt systems has been debated, and is here investigated considering a gravity spreading example. Plane strain finite element numerical analysis was used to systematically evaluate the impact of changes in density scaling on buoyancy force, sediment strength, and pressure gradient. A range of densities typical of natural systems (including compacting sediment) and physical analogue experiments was included. A fundamental shift in the structure of the salt-sediment system, from diapir-minibasin pairs to expulsion rollover, was observed when sediment and salt densities were altered from values typical of physical experiments (1600 and 990 kg/m3) to those most often found in nature (1900-2300 and 2150 kg/m3). Experiments equivalent to physical analogue models but with reduced sediment density showed diapir-minibasin pair geometry, persisting to sediment densities of ˜1300 kg/m3. Salt burial by pre-kinematic sediments was found to suppress diapir formation for thicknesses greater than ˜750 m (0.75 cm at the laboratory scale). The relative importance of disproportionately high buoyancy force, low sediment strength, and pressure gradient in physical experiments was investigated by isolating each of these scaling errors in turn. Buoyancy was found to be most influential in the development of diapir-minibasin pairs versus expulsion rollover geometry. Finally, we demonstrate that dry physical analogue experiments with sediment density reduced to ˜1140 kg/m3 (achievable through mixing with hollow glass beads) would provide a reasonable approximation of submarine salt systems in nature (including water load and hydrostatic pore fluid pressure).

Allen, Janice; Beaumont, Christopher

2012-08-01

119

Astrophysical Data Transmission in Planck Units  

NASA Astrophysics Data System (ADS)

``Data Communication and Net Working'' by Forouzan expresses (an informatics equivalent of statistics) that N (data rate or bits/second) divided by r (number of data elements per signal or log2L) is the baud rate. For N = 10^43 Planck times per second, and L = 10^90, the number of photons in the universe, the baud rate is more than 10^40, so high a signal rate for the carriers of the attractive and repulsive pulses that we, the observers, would think that gravity is continuous, and not probabilistic. Any potential slight correction to the above as it may apply to the case, or its application to smaller baryon number (10^79) would not change the above implicit message, considering the order of magnitudes involved. This communicative aspect of gravity, and our postulation, slight modification to the inverse square law, in [1] that the probability of an interaction between two particles is inversely proportional to the square of their separations in integer number of Planck lengths, are mutually supplementary and complimentary, portraying two ducks that, not only walk like ducks, but also talk like ducks. Therefore, they are ducks. Refer to: [1] Goradia, Shantilal http://www.arXiv.org/pdf/physics/0210040v4.

Goradia, Shantilal

2008-10-01

120

Planck early results. XVI. The Planck view of nearby galaxies  

Microsoft Academic Search

The all-sky coverage of the Planck Early Release Compact Source Catalogue (ERCSC) provides an unsurpassed survey of galaxies at submillimetre (submm) wavelengths, representing a major improvement in the numbers of galaxies detected, as well as the range of far-IR\\/submm wavelengths over which they have been observed. We here present the first results on the properties of nearby galaxies using these

P. A. R. Ade; N. Aghanim; M. Arnaud; M. Ashdown; J. Aumont; C. Baccigalupi; A. Balbi; A. J. Banday; R. B. Barreiro; J. G. Bartlett; E. Battaner; K. Benabed; A. Benoît; J.-P. Bernard; M. Bersanelli; R. Bhatia; J. J. Bock; A. Bonaldi; J. R. Bond; J. Borrill; M. Bucher; C. Burigana; P. Cabella; J.-F. Cardoso; A. Catalano; L. Cayón; A. Challinor; A. Chamballu; R.-R. Chary; L.-Y. Chiang; P. R. Christensen; D. L. Clements; S. Colombi; F. Couchot; A. Coulais; B. P. Crill; F. Cuttaia; L. Danese; R. D. Davies; R. J. Davis; P. de Bernardis; G. de Gasperis; A. de Rosa; G. de Zotti; J. Delabrouille; J.-M. Delouis; F.-X. Désert; C. Dickinson; H. Dole; S. Donzelli; O. Doré; U. Dörl; M. Douspis; X. Dupac; G. Efstathiou; T. A. Enßlin; F. Finelli; O. Forni; M. Frailis; E. Franceschi; S. Galeotta; K. Ganga; M. Giard; G. Giardino; Y. Giraud-Héraud; J. González-Nuevo; K. M. Górski; S. Gratton; A. Gregorio; A. Gruppuso; F. K. Hansen; D. Harrison; G. Helou; S. Henrot-Versillé; D. Herranz; S. R. Hildebrandt; E. Hivon; M. Hobson; W. A. Holmes; W. Hovest; R. J. Hoyland; K. M. Huffenberger; A. H. Jaffe; W. C. Jones; M. Juvela; E. Keihänen; R. Keskitalo; T. S. Kisner; R. Kneissl; L. Knox; H. Kurki-Suonio; G. Lagache; A. Lähteenmäki; J.-M. Lamarre; A. Lasenby; R. J. Laureijs; C. R. Lawrence; S. Leach; R. Leonardi; M. Linden-Vørnle; M. López-Caniego; P. M. Lubin; J. F. Macías-Pérez; C. J. MacTavish; S. Madden; B. Maffei; D. Maino; N. Mandolesi; R. Mann; M. Maris; E. Martínez-González; S. Masi; S. Matarrese; F. Matthai; P. Mazzotta; A. Melchiorri; L. Mendes; A. Mennella; M.-A. Miville-Deschênes; A. Moneti; L. Montier; G. Morgante; D. Mortlock; D. Munshi; A. Murphy; P. Naselsky; P. Natoli; C. B. Netterfield; H. U. Nørgaard-Nielsen; F. Noviello; D. Novikov; I. Novikov; S. Osborne; F. Pajot; B. Partridge; F. Pasian; G. Patanchon; M. Peel; O. Perdereau; L. Perotto; F. Perrotta; F. Piacentini; M. Piat; S. Plaszczynski; E. Pointecouteau; G. Polenta; N. Ponthieu; T. Poutanen; G. Prézeau; S. Prunet; J.-L. Puget; W. T. Reach; R. Rebolo; M. Reinecke; C. Renault; S. Ricciardi; T. Riller; I. Ristorcelli; G. Rocha; C. Rosset; M. Rowan-Robinson; J. A. Rubiño-Martín; B. Rusholme; M. Sandri; G. Savini; D. Scott; M. D. Seiffert; P. Shellard; G. F. Smoot; J.-L. Starck; F. Stivoli; V. Stolyarov; R. Sudiwala; J.-F. Sygnet; J. A. Tauber; L. Terenzi; L. Toffolatti; M. Tomasi; J.-P. Torre; M. Tristram; J. Tuovinen; M. Türler; G. Umana; L. Valenziano; J. Varis; P. Vielva; F. Villa; N. Vittorio; L. A. Wade; B. D. Wandelt; D. Yvon; A. Zacchei; A. Zonca

2011-01-01

121

Rereading Langer's influential 1937 JWKB paper: the unnecessary Langer transformation; the two planck's  

NASA Astrophysics Data System (ADS)

After making the 'Langer transformation', r = ex, ?(r) = ex/2u(x), Langer found the first-order JWKB hydrogen radial wavefunction to be as if the centrifugal potential were planck2(l + 1/2)2/(2r2), thereby 'justifying' the substitution suggested by Kramers and known to get, in first order, the correct rl + 1 behavior at the origin, the correct phase shift and the exact energy levels. There have been many extensions of the Kramers-Langer substitution: to get the exact origin behavior at any pre-specified higher order; to show that no substitution is necessary at infinite order; to replace planck2l(l + 1) by L2 + planckL, with L set equal to lplanck at the end. Recently, it was discovered that Langer's JWKB solution in x was exactly equivalent to a JWKB solution in r for r-1/2?(r): namely the Langer transformation was irrelevant. How can there be many seemingly incompatible JWKB expansions to solve one equation? The key is the ambiguous treatment of planck: in the radial kinetic energy, planck is the expansion parameter; in the centrifugal potential, planck is implicit, passive and not expanded. By designating the implicit plancki by its own symbol, one sees immediately how the different JWKB expansions correspond to different partitions of the centrifugal potential between expansion planck and implicit plancki and therefore solve different equations. The different expansions represent the same physical solution only when plancki = planck. Moreover, in the two-planck notation, 'the generalization' of the Kramers-Langer substitution is made transparently simple: \\hbar ^2l(l+1)\\rightarrow \\hbar _i^2(l+1/2)^2-\\hbar ^2/4. That is, the implicit planck2i/4 that completes the square is compensated by the expansion -planck2/4 that modifies the second-order JWKB wavefunction directly and higher orders indirectly.

Koike, Tatsuya; Silverstone, Harris J.

2009-12-01

122

Quasicontinuum Fokker-Planck equation  

NASA Astrophysics Data System (ADS)

Building on the work [C. R. Doering, P. S. Hagan, and P. Rosenau, Phys. Rev. A 36, 985 (1987)] we present a regularized Fokker-Planck equation for discrete-state systems with more accurate short-time behavior than its standard, Kramers-Moyal counterpart. This regularization leads to a quasicontinuum Fokker-Planck equation with several key features: it preserves crucial aspects of state-space discreteness ordinarily lost in the standard Kramers-Moyal expansion; it is well posed, and it is more amenable to analytical and numerical tools currently available for continuum systems. In order to expose the basic idea underlying the regularization, it suffices for us to focus on two simple problems—the chemical reaction kinetics of a one-component system and a two-dimensional symmetric random walk on a square lattice. We then describe the path to applying this approach to more complex, discrete-state stochastic systems.

Alexander, Francis J.; Rosenau, Philip

2010-04-01

123

Planck scale inflationary spectra from quantum gravity  

SciTech Connect

We derive the semiclassical evolution of massless minimally coupled scalar matter in the de Sitter space-time from the Born-Oppenheimer reduction of the Wheeler-DeWitt equation. We show that the dynamics of trans-Planckian modes can be cast in the form of an effective modified dispersion relation and that high energy corrections in the power spectrum of the cosmic microwave background radiation produced during inflation remain very small if the initial state is the Bunch-Davies vacuum.

Alberghi, Gian Luigi [Dipartimento di Fisica, Universita di Bologna, and I.N.F.N., Sezione di Bologna, via Irnerio 46, 40126 Bologna (Italy); Department of Astronomy, University of Bologna, via Ranzani 1, 40127 Bologna (Italy); Casadio, Roberto; Tronconi, Alessandro [Dipartimento di Fisica, Universita di Bologna, and I.N.F.N., Sezione di Bologna, via Irnerio 46, 40126 Bologna (Italy)

2006-11-15

124

Planck scale inflationary spectra from quantum gravity  

NASA Astrophysics Data System (ADS)

We derive the semiclassical evolution of massless minimally coupled scalar matter in the de Sitter space-time from the Born-Oppenheimer reduction of the Wheeler-DeWitt equation. We show that the dynamics of trans-Planckian modes can be cast in the form of an effective modified dispersion relation and that high energy corrections in the power spectrum of the cosmic microwave background radiation produced during inflation remain very small if the initial state is the Bunch-Davies vacuum.

Alberghi, Gian Luigi; Casadio, Roberto; Tronconi, Alessandro

2006-11-01

125

Planck scale inflationary spectra from quantum gravity  

Microsoft Academic Search

We derive the semiclassical evolution of massless minimally coupled scalar matter in the de Sitter space-time from the Born-Oppenheimer reduction of the Wheeler-DeWitt equation. We show that the dynamics of trans-Planckian modes can be cast in the form of an effective modified dispersion relation and that high energy corrections in the power spectrum of the cosmic microwave background radiation produced

Gian Luigi Alberghi; Roberto Casadio; Alessandro Tronconi

2006-01-01

126

Role of the subgrid-scale physical processes in supermodelling  

NASA Astrophysics Data System (ADS)

The basic ides of supermodelling is in overcoming deficits of existing models by combining them together to improve our ability of climate simulations and prediction. However, in order to exploit this method better, we have to pay special attention to the common defects of the current climate models. Representation of subgrid-scale physical processes is such a particular example. . The present talk presents the author's point of view on representation of subgrid-scale processes in the above general question in mind. The focus of the talk will be on interplay between traditional parameterizations and recently proposed superparameterization (also often called "multiscale modelling"), but it also covers the issues of downscaling as well as possibilities of introducing mesh-refinement approaches into the context of subgrid-scale modelling. The author's main perspective is that the subgrid-scale parameterization should not be considered as a distinguished approach in contrast to explicit (more direct) modelling, such as superparameterization, but a hierarchy of modelling approaches should be constructed by taking various intermediate approaches. The mass-flux convection parameterization is taken as an example in order to make this point. It will be shown that at the most basic level, the mass-flux parameterization is equivalent to a finite-volume numerical approach, though various additional approximations and hypotheses must be introduced in order to arrive at a classical mass-flux parameterization. At the mathematical level, the multiresolution analysis based on wavelet provides a basic source of inspirations for developing this general perspective. From this perspective, the issue of parameterization is considered as "compression" of a full explicit model in the same sense as the wavelet can be used for the image compression. This perspective also leads to a concept of compression of physics. Compression of cloud microphysics would be the most urgent issue considering its vast complexity as well as its crucial importance in climate feedbacks.

Yano, J.

2011-12-01

127

Fully Kinetic Fokker-Planck Model of Thermal Smoothing in Nonuniform Laser-Target Interactions  

SciTech Connect

Using a fully kinetic 2D Fokker-Planck model, the generation and evolution of ion density perturbations from nonuniform laser deposition in a plasma slab have been studied. It is found that significant smoothing of the ion density perturbations from nonuniform optically smoothed single beam laser deposition can be achieved on hydrodynamic times scales over a range of scale sizes. In addition, it is observed that the Fokker-Planck model predicts more smoothing than the hydrodynamic Spitzer model.

Keskinen, M. J. [Charged Particle Physics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States)

2009-07-31

128

Physically-sound scaling laws for snow avalanche impact pressure  

NASA Astrophysics Data System (ADS)

Estimating the force on obstacles stemming from snow avalanches is a non trivial task in avalanche-flow regimes at low velocity for which inertia does not prevail. In addition to the gravity force -proportional to the weight of the undisturbed incoming flow- that takes place at low velocity, extra forces induced by friction for granular snow avalanches, or by some possible viscosity effects for more fluid-like snow avalanches, should be considered. We discuss here the case of a wall-like obstacle overflowed by a granular snow avalanche. Recent small-scale discrete numerical simulations and laboratory tests with granular flows have allowed developing and validating an analytical model to predict the force on the wall. This model shows that the force is the sum of the inertial force, the gravity force of the undisturbed flow and an additional contribution caused by the presence of a stagnant zone formed upstream of the wall and co-existing with an inertial zone above. The model is used to derive a physically-sound scaling law giving the pressure relative to the typical inertial force of the undisturbed flow as a function of the Froude number. Rheological properties of the granular flowing material such as the typical friction angles of the granular material as well as the restitution coefficient of granules are included in the proposed scaling law. With appropriate values of those rheological properties for flowing granular snow, the scaling law can be used to interpret existing pressure data from full-scale snow avalanches and can be cross-compared to classical approaches used in snow avalanche engineering.

Faug, T.; Chanut, B.; Caccamo, P.; Naaim, M.

2012-04-01

129

Scaling relations between numerical simulations and physical systems they represent  

NASA Astrophysics Data System (ADS)

The dynamical equations describing the evolution of a physical system generally have a freedom in the choice of units, where different choices correspond to different physical systems that are described by the same equations. Since there are three basic physical units, of mass, length and time, there are up to three free parameters in such a rescaling of the units, Nf? 3. In Newtonian hydrodynamics, for example, there are indeed usually three free parameters, Nf= 3. If, however, the dynamical equations contain a universal dimensional constant, such as the speed of light in vacuum c or the gravitational constant G, then the requirement that its value remains the same imposes a constraint on the rescaling, which reduces its number of free parameters by one, to Nf= 2. This is the case, for example, in magnetohydrodynamics or special relativistic hydrodynamics, where c appears in the dynamical equations and forces the length and time units to scale by the same factor, or in Newtonian gravity where the gravitational constant G appears in the equations. More generally, when there are Nudc independent (in terms of their units) universal dimensional constants, then the number of free parameters is Nf= max (0, 3 -Nudc). When both gravity and relativity are included, there is only one free parameter (Nf= 1, as both G and c appear in the equations so that Nudc= 2), and the units of mass, length and time must all scale by the same factor. The explicit rescalings for different types of systems are discussed and summarized here. Such rescalings of the units also hold for discrete particles, e.g. in N-body or particle-in-cell simulations. They are very useful when numerically investigating a large parameter space or when attempting to fit particular experimental results, by significantly reducing the required number of simulations.

Granot, Jonathan

2012-04-01

130

Planck pre-launch status: The Planck-LFI programme  

NASA Astrophysics Data System (ADS)

This paper provides an overview of the Low Frequency Instrument (LFI) programme within the ESA Planck mission. The LFI instrument has been developed to produce high precision maps of the microwave sky at frequencies in the range 27-77 GHz, below the peak of the cosmic microwave background (CMB) radiation spectrum. The scientific goals are described, ranging from fundamental cosmology to Galactic and extragalactic astrophysics. The instrument design and development are outlined, together with the model philosophy and testing strategy. The instrument is presented in the context of the Planck mission. The LFI approach to ground and inflight calibration is described. We also describe the LFI ground segment. We present the results of a number of tests demonstrating the capability of the LFI data processing centre (DPC) to properly reduce and analyse LFI flight data, from telemetry information to calibrated and cleaned time ordered data, sky maps at each frequency (in temperature and polarization), component emission maps (CMB and diffuse foregrounds), catalogs for various classes of sources (the Early Release Compact Source Catalogue and the Final Compact Source Catalogue). The organization of the LFI consortium is briefly presented as well as the role of the core team in data analysis and scientific exploitation. All tests carried out on the LFI flight model demonstrate the excellent performance of the instrument and its various subunits. The data analysis pipeline has been tested and its main steps verified. In the first three months after launch, the commissioning, calibration, performance, and verification phases will be completed, after which Planck will begin its operational life, in which LFI will have an integral part.

Mandolesi, N.; Bersanelli, M.; Butler, R. C.; Artal, E.; Baccigalupi, C.; Balbi, A.; Banday, A. J.; Barreiro, R. B.; Bartelmann, M.; Bennett, K.; Bhandari, P.; Bonaldi, A.; Borrill, J.; Bremer, M.; Burigana, C.; Bowman, R. C.; Cabella, P.; Cantalupo, C.; Cappellini, B.; Courvoisier, T.; Crone, G.; Cuttaia, F.; Danese, L.; D'Arcangelo, O.; Davies, R. D.; Davis, R. J.; de Angelis, L.; de Gasperis, G.; de Rosa, A.; de Troia, G.; de Zotti, G.; Dick, J.; Dickinson, C.; Diego, J. M.; Donzelli, S.; Dörl, U.; Dupac, X.; Enßlin, T. A.; Eriksen, H. K.; Falvella, M. C.; Finelli, F.; Frailis, M.; Franceschi, E.; Gaier, T.; Galeotta, S.; Gasparo, F.; Giardino, G.; Gomez, F.; Gonzalez-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Hansen, F.; Hell, R.; Herranz, D.; Herreros, J. M.; Hildebrandt, S.; Hovest, W.; Hoyland, R.; Huffenberger, K.; Janssen, M.; Jaffe, T.; Keihänen, E.; Keskitalo, R.; Kisner, T.; Kurki-Suonio, H.; Lähteenmäki, A.; Lawrence, C. R.; Leach, S. M.; Leahy, J. P.; Leonardi, R.; Levin, S.; Lilje, P. B.; López-Caniego, M.; Lowe, S. R.; Lubin, P. M.; Maino, D.; Malaspina, M.; Maris, M.; Marti-Canales, J.; Martinez-Gonzalez, E.; Massardi, M.; Matarrese, S.; Matthai, F.; Meinhold, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Morgante, G.; Morigi, G.; Morisset, N.; Moss, A.; Nash, A.; Natoli, P.; Nesti, R.; Paine, C.; Partridge, B.; Pasian, F.; Passvogel, T.; Pearson, D.; Pérez-Cuevas, L.; Perrotta, F.; Polenta, G.; Popa, L. A.; Poutanen, T.; Prezeau, G.; Prina, M.; Rachen, J. P.; Rebolo, R.; Reinecke, M.; Ricciardi, S.; Riller, T.; Rocha, G.; Roddis, N.; Rohlfs, R.; Rubiño-Martin, J. A.; Salerno, E.; Sandri, M.; Scott, D.; Seiffert, M.; Silk, J.; Simonetto, A.; Smoot, G. F.; Sozzi, C.; Sternberg, J.; Stivoli, F.; Stringhetti, L.; Tauber, J.; Terenzi, L.; Tomasi, M.; Tuovinen, J.; Türler, M.; Valenziano, L.; Varis, J.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L.; White, M.; White, S.; Wilkinson, A.; Zacchei, A.; Zonca, A.

2010-09-01

131

Development of scales to assess children's perceptions of friend and parental influences on physical activity  

Microsoft Academic Search

BACKGROUND: Many children do not meet physical activity guidelines. Parents and friends are likely to influence children's physical activity but there is a shortage of measures that are able to capture these influences. METHODS: A new questionnaire with the following three scales was developed: 1) Parental influence on physical activity; 2) Motives for activity with friends scale; and 3) Physical

Russell Jago; Kenneth R Fox; Angie S Page; Rowan Brockman; Janice L Thompson

2009-01-01

132

A multi-scale modeling system with unified physics  

NASA Astrophysics Data System (ADS)

A multiscale oceanic/atmospheric modeling system with unified physics, the Global/Regional Integrated Modeling system (GRIMs), has been created for use in numerical weather prediction, seasonal simulations, and climate researches from global to regional scales. The development and applications of the model system are carried out by the Korean modeling community, taking advantage of both operational and research applications. This talk outlines the history of the GRIMs, its current capabilities, and plans for its future development and applications, providing a summary useful to present and future users. An example of real-time forecasts using the GRIMS for medium-range forecasts will be demonstrated. Application of this model to climate studies will also be presented.

Hong, Song-You

2013-04-01

133

The Physical Activity Scale for the Elderly (PASE) Questionnaire; Does It Predict Physical Health?  

PubMed Central

A lack of physical activity is common in older adults. With the increasing Canadian senior population, identifying the minimum amount of physical activity required to maintain the health of older adults is essential. This study determined whether relationships existed between the Physical Activity Scale for the Elderly (PASE) questionnaire scores and health-related measurements in community-dwelling older adults who were meal delivery volunteers. Based on observed relationships between PASE scores and health parameters, the study attempted to predict an optimal PASE score that would ensure health parameters fell in desired ranges for older adults. 297 community-dwelling older adults (61.3% female) 60–88 years (72.1 ± 6.5) completed the PASE and were measured for body composition, cardiovascular and blood parameters, flexibility, and handgrip strength. Significant regression models using PASE were produced for the health-related measures, but the relationships were not meaningful due to low predictive capacity. However, correlational data suggested that a minimum PASE score of ~140 for males and ~120 for females predicted a favorable waist circumference. In conclusion, findings demonstrated that PASE scores cannot be used to predict healthy physical measures, although the relationships between PASE and WC could be used to encourage older adults to become more physically active.

Logan, Samantha L.; Gottlieb, Benjamin H.; Maitland, Scott B.; Meegan, Dan; Spriet, Lawrence L.

2013-01-01

134

Millikan's measurement of Planck's constant  

NASA Astrophysics Data System (ADS)

Robert Millikan is famous for measuring the charge of the electron. His result was better than any previous measurement and his method established that there was a fundamental unit of charge, or charge quantization. He is less well-known for his measurement of Planck's constant, although, as discussed below, he is often mistakenly given credit for providing significant evidence in support of Einstein's photon theory of light.1 His Nobel Prize citation was "for his work on the elementary electric charge of electricity and the photoelectric effect," an indication of the significance of his work on the photoelectric effect.

Franklin, Allan

2013-09-01

135

Fast Algorithms for Numerical, Conservative, and Entropy Approximations of the Fokker–Planck–Landau Equation  

Microsoft Academic Search

We present fast numerical algorithms to solve the nonlinear Fokker–Planck–Landau equation in 3D velocity space. The discretization of the collision operator preserves the properties required by the physical nature of the Fokker–Planck–Landau equation, such as the conservation of mass, momentum, and energy, the decay of the entropy, and the fact that the steady states are Maxwellians. At the end of

C. Buet; S. Cordier; P. Degond; M. Lemou

1997-01-01

136

Planck early results. XXII. The submillimetre properties of a sample of Galactic cold clumps  

Microsoft Academic Search

We perform a detailed investigation of sources from the Cold Cores Catalogue of Planck Objects (C3PO). Our goal is to probe the reliability of the detections, validate the separation between warm and cold dust emission components, provide the first glimpse at the nature, internal morphology and physical characterictics of the Planck-detected sources. We focus on a sub-sample of ten sources

P. A. R. Ade; N. Aghanim; M. Arnaud; M. Ashdown; J. Aumont; C. Baccigalupi; A. Balbi; A. J. Banday; R. B. Barreiro; J. G. Bartlett; E. Battaner; K. Benabed; A. Benoît; J.-P. Bernard; M. Bersanelli; R. Bhatia; J. J. Bock; A. Bonaldi; J. R. Bond; J. Borrill; F. Boulanger; M. Bucher; C. Burigana; P. Cabella; C. M. Cantalupo; J.-F. Cardoso; A. Catalano; L. Cayón; A. Challinor; A. Chamballu; L.-Y. Chiang; P. R. Christensen; D. L. Clements; S. Colombi; F. Couchot; A. Coulais; B. P. Crill; F. Cuttaia; L. Danese; R. D. Davies; P. de Bernardis; G. de Gasperis; A. de Rosa; G. de Zotti; J. Delabrouille; J.-M. Delouis; F.-X. Désert; C. Dickinson; Y. Doi; S. Donzelli; O. Doré; U. Dörl; M. Douspis; X. Dupac; G. Efstathiou; T. A. Enßlin; E. Falgarone; F. Finelli; O. Forni; M. Frailis; E. Franceschi; S. Galeotta; K. Ganga; M. Giard; G. Giardino; Y. Giraud-Héraud; J. González-Nuevo; K. M. Górski; S. Gratton; A. Gregorio; A. Gruppuso; F. K. Hansen; D. Harrison; G. Helou; S. Henrot-Versillé; D. Herranz; S. R. Hildebrandt; E. Hivon; M. Hobson; W. A. Holmes; W. Hovest; R. J. Hoyland; K. M. Huffenberger; N. Ikeda; A. H. Jaffe; W. C. Jones; M. Juvela; E. Keihänen; R. Keskitalo; T. S. Kisner; Y. Kitamura; R. Kneissl; L. Knox; H. Kurki-Suonio; G. Lagache; J.-M. Lamarre; A. Lasenby; R. J. Laureijs; C. R. Lawrence; S. Leach; R. Leonardi; C. Leroy; M. Linden-Vørnle; M. López-Caniego; P. M. Lubin; J. F. Macías-Pérez; C. J. MacTavish; B. Maffei; J. Malinen; N. Mandolesi; R. Mann; M. Maris; D. J. Marshall; P. Martin; E. Martínez-González; S. Masi; S. Matarrese; F. Matthai; P. Mazzotta; P. McGehee; A. Melchiorri; L. Mendes; A. Mennella; C. Meny; S. Mitra; M.-A. Miville-Deschênes; A. Moneti; L. Montier; G. Morgante; D. Mortlock; D. Munshi; A. Murphy; P. Naselsky; F. Nati; P. Natoli; C. B. Netterfield; H. U. Nørgaard-Nielsen; F. Noviello; D. Novikov; I. Novikov; S. Osborne; L. Pagani; F. Piacentini; R. Paladini; F. Pasian; G. Patanchon; V.-M. Pelkonen; O. Perdereau; L. Perotto; F. Perrotta; M. Piat; S. Plaszczynski; E. Pointecouteau; G. Polenta; N. Ponthieu; T. Poutanen; G. Prézeau; S. Prunet; J.-L. Puget; W. T. Reach; R. Rebolo; M. Reinecke; C. Renault; S. Ricciardi; T. Riller; I. Ristorcelli; G. Rocha; C. Rosset; M. Rowan-Robinson; J. A. Rubiño-Martín; B. Rusholme; M. Sandri; D. Santos; G. Savini; D. Scott; M. D. Seiffert; G. F. Smoot; J.-L. Starck; F. Stivoli; V. Stolyarov; R. Sudiwala; J.-F. Sygnet; J. A. Tauber; L. Terenzi; L. Toffolatti; M. Tomasi; J.-P. Torre; V. Toth; M. Tristram; J. Tuovinen; G. Umana; L. Valenziano; P. Vielva; F. Villa; N. Vittorio; L. A. Wade; B. D. Wandelt; N. Ysard; D. Yvon; A. Zacchei; A. Zonca

2011-01-01

137

On the coherence of WMAP and Planck temperature maps  

NASA Astrophysics Data System (ADS)

The recent data release of ESA's Planck mission together with earlier Wilkinson Microwave Anisotropy Probe (WMAP) releases provide the first opportunity to compare high-resolution full sky cosmic microwave background (CMB) temperature anisotropy maps. To quantify the coherence of these maps beyond the power spectrum, we introduce Generalized Phases in the sense of SO(3), unit vectors in the 2? + 1 dimensional representation spaces. For an isotropic Gaussian distribution, Generalized Phases point to random directions and if there is non-Gaussianity, they represent most of the non-Gaussian information. The alignment of these unit vectors from two maps can be characterized by their angle, 0° expected for full coherence, and 90° for random vectors. We analyse maps from both missions with the same mask and Nside = 512 resolution, and compare both power spectra and Generalized Phases. We find excellent agreement of the Generalized Phases of Planck Spectral Matching Independent Component Analysis map with that of the WMAP Q, V, W maps, rejecting the null hypothesis of no correlations at 5? for ? < 700, ? < 900 and ? < 1100, respectively, except perhaps for ? < 10. Using foreground reduced maps for WMAP increases the phase-coherence. The observed coherence angles can be explained with a simple assumption of Gaussianity and a WMAP noise model neglecting Planck noise, except for low-intermediate ? values there is a slight, but significant offset, depending on the WMAP band. On the same scales WMAP power spectrum is about 2.6 per cent higher at a very high significance, while at higher ? ranges there appears to be no significant bias. Using our theoretical tools, we predict the phase alignment of Planck with a hypothetical perfect noiseless CMB experiment, finding decoherence at ? ? 2900; below this value Planck can be used most efficiently to constrain non-Gaussianity.

Kovács, András; Carron, Julien; Szapudi, István

2013-10-01

138

Scale relativity and fractal space-time: Applications to quantum physics, cosmology and chaotic systems  

Microsoft Academic Search

The theory of scale relativity is a new approach to the problem of the origin of fundamental scales and of scaling laws in physics, that consists of generalizing Einstein's principle of relativity (up to now applied to motion laws) to scale transformations. Namely, we redefine space-time resolutions as characterizing the state of scale of the reference system and require that

L. Nottale

1996-01-01

139

Predicted Planck extragalactic point-source catalogue  

Microsoft Academic Search

An estimation of the number and amplitude (in flux) of the extragalactic point sources that will be observed by the Planck Mission is presented in this paper. The study is based on the Mexican Hat wavelet formalism introduced by Cayón et al. Simulations at Planck observing frequencies are analysed, taking into account all the possible cosmological, Galactic and extragalactic emissions

P. Vielva; E. Martínez-González; L. Cayón; J. M. Diego; J. L. Sanz; L. Toffolatti

2001-01-01

140

Planck early results. II. The thermal performance of Planck  

NASA Astrophysics Data System (ADS)

The performance of the Planck instruments in space is enabled by their low operating temperatures, 20 K for LFI and 0.1 K for HFI, achieved through a combination of passive radiative cooling and three active mechanical coolers. The scientific requirement for very broad frequency coverage led to two detector technologies with widely different temperature and cooling needs. Active coolers could satisfy these needs; a helium cryostat, as used by previous cryogenic space missions (IRAS, COBE, ISO, Spitzer, AKARI), could not. Radiative cooling is provided by three V-groove radiators and a large telescope baffle. The active coolers are a hydrogen sorption cooler (<20 K), a 4He Joule-Thomson cooler (4.7 K), and a 3He-4He dilution cooler (1.4 K and 0.1 K). The flight system was at ambient temperature at launch and cooled in space to operating conditions. The HFI bolometer plate reached 93 mK on 3 July 2009, 50 days after launch. The solar panel always faces the Sun, shadowing the rest of Planck, andoperates at a mean temperature of 384 K. At the other end of the spacecraft, the telescope baffle operates at 42.3 K and the telescope primary mirror operates at 35.9 K. The temperatures of key parts of the instruments are stabilized by both active and passive methods. Temperature fluctuations are driven by changes in the distance from the Sun, sorption cooler cycling and fluctuations in gas-liquid flow, and fluctuations in cosmic ray flux on the dilution and bolometer plates. These fluctuations do not compromise the science data.

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Baker, M.; Balbi, A.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoît, A.; Bernard, J.-P.; Bersanelli, M.; Bhandari, P.; Bhatia, R.; Bock, J. J.; Bonaldi, A.; Bond, J. R.; Borders, J.; Borrill, J.; Bouchet, F. R.; Bowman, B.; Bradshaw, T.; Bréelle, E.; Bucher, M.; Burigana, C.; Butler, R. C.; Cabella, P.; Camus, P.; Cantalupo, C. M.; Cappellini, B.; Cardoso, J.-F.; Catalano, A.; Cayón, L.; Challinor, A.; Chamballu, A.; Chambelland, J. P.; Charra, J.; Charra, M.; Chiang, L.-Y.; Chiang, C.; Christensen, P. R.; Clements, D. L.; Collaudin, B.; Colombi, S.; Couchot, F.; Coulais, A.; Crill, B. P.; Crook, M.; Cuttaia, F.; Damasio, C.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Gasperis, G.; de Rosa, A.; Delabrouille, J.; Delouis, J.-M.; Désert, F.-X.; Dolag, K.; Donzelli, S.; Doré, O.; Dörl, U.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Filliard, C.; Finelli, F.; Foley, S.; Forni, O.; Fosalba, P.; Fourmond, J.-J.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Gavila, E.; Giard, M.; Giardino, G.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Guyot, G.; Harrison, D.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Hoyland, R. J.; Huffenberger, K. M.; Israelsson, U.; Jaffe, A. H.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knox, L.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lami, P.; Lasenby, A.; Laureijs, R. J.; Lavabre, A.; Lawrence, C. R.; Leach, S.; Lee, R.; Leonardi, R.; Leroy, C.; Lilje, P. B.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maciaszek, T.; MacTavish, C. J.; Maffei, B.; Maino, D.; Mandolesi, N.; Mann, R.; Maris, M.; Martínez-González, E.; Masi, S.; Matarrese, S.; Matthai, F.; Mazzotta, P.; McGehee, P.; Meinhold, P. R.; Melchiorri, A.; Melot, F.; Mendes, L.; Mennella, A.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Mora, J.; Morgante, G.; Morisset, N.; Mortlock, D.; Munshi, D.; Murphy, A.; Naselsky, P.; Nash, A.; Natoli, P.; Netterfield, C. B.; Novikov, D.; Novikov, I.; O'Dwyer, I. J.; Osborne, S.; Pajot, F.; Pasian, F.; Patanchon, G.; Pearson, D.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Plaszczynski, S.; Platania, P.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Poutanen, T.; Prézeau, G.; Prina, M.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Rebolo, R.; Reinecke, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Schaefer, B. M.; Scott, D.; Seiffert, M. D.; Shellard, P.; Smoot, G. F.; Starck, J.-L.; Stassi, P.; Stivoli, F.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Torre, J.-P.; Tristram, M.; Tuovinen, J.; Valenziano, L.; Vibert, L.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; Watson, C.; White, S. D. M.; Wilkinson, A.; Wilson, P.; Yvon, D.; Zacchei, A.; Zhang, B.; Zonca, A.

2011-12-01

141

Developing a Rasch Measurement Physical Fitness Scale for Hong Kong Primary School-Aged Students  

Microsoft Academic Search

The main purpose of this study was to develop a Rasch Measurement Physical Fitness Scale (RMPFS) based on physical fitness indicators routinely used in Hong Kong primary schools. A total of 9,439 records of students' performances on physical fitness indicators, retrieved from the database of a Hong Kong primary school, were used to develop the Rasch scale. Following a series

Zi Yan; Trevor G. Bond

2011-01-01

142

WMAP Observations of Planck ESZ Clusters  

NASA Astrophysics Data System (ADS)

We examine the Sunyaev-Zeldovich (SZ) effect in the seven year Wilkinson Microwave Anisotropy Probe (WMAP) data by cross-correlating it with the Planck Early-release Sunyaev-Zeldovich catalog. Our analysis proceeds in two parts. We first perform a stacking analysis in which the filtered WMAP data are averaged at the locations of the 175 Planck clusters. We then perform a regression analysis to compare the mean amplitude of the SZ signal, Y 500, in the WMAP data to the corresponding amplitude in the Planck data. The aggregate Planck clusters are detected in the seven year WMAP data with a signal-to-noise ratio of 16.3. In the regression analysis, we find that the SZ amplitude measurements agree to better than 25%: a = 1.23 ± 0.18 for the fit Y^{wmap}_{500} = aY^{planck}_{500}.

Ma, Yin-Zhe; Hinshaw, Gary; Scott, Douglas

2013-07-01

143

Development and validation of a physical self-efficacy scale  

Microsoft Academic Search

Conducted 6 studies, involving 861 undergraduates, to develop an individual-difference measure of physical self-efficacy with adequate psychometric properties. Factor analysis of 90 test items identified 2 underlying dimensions within a global measure of physical self-efficacy: Perceived Physical Ability and Physical Self-Presentation Confidence. Ss with positive perceptions of their physical competence outperformed Ss with poorer self-regard on 3 tasks involving the

Richard M. Ryckman; Michael A. Robbins; Billy Thornton; Peggy Cantrell

1982-01-01

144

A unified physical scaling law for tokamak energy confinement  

Microsoft Academic Search

From the equations which describe local transport in a turbulent plasma the scaling of the local diffusivity with the plasma parameters can be established. It is shown that, by appropriate choices of time and length scales for the turbulence, the scaling of the global energy confinement can be cast in two limiting forms: a short and a long wavelength scaling.

J. P. Christiansen; J. G. Cordey; K. Thomsen

1990-01-01

145

Continuous-scale physical functional performance in healthy older adults: A validation study  

Microsoft Academic Search

Objective: The continuous-scale physical functional performance test (CS-PFP) is an original instrument designed to provide a comprehensive, in-depth measure of physical function that reflects abilities in several separate physical domains. It is based on a concept of physical function as the integration of physiological capacity, physical performance, and psychosocial factors.Setting: The test was administered under standard conditions in a hospital

M. Elaine Cress; David M. Buchner; Kent A. Questad; Peter C. Esselman; Barbara J. deLateur; Robert S. Schwartz

1996-01-01

146

A review of Vlasov-Fokker-Planck numerical modeling of inertial confinement fusion plasma  

NASA Astrophysics Data System (ADS)

The interaction of intense lasers with solid matter generates a hot plasma state that is well described by the Vlasov-Fokker-Planck equation. Accurate and efficient modeling of the physics in these scenarios is highly pertinent, because it relates to experimental campaigns to produce energy by inertial confinement fusion on facilities such as the National Ignition Facility. Calculations involving the Vlasov-Fokker-Planck equation are computationally intensive, but are crucial to proper understanding of a wide variety of physical effects and instabilities in inertial fusion plasmas. In this topical review, we will introduce the background physics related to Vlasov-Fokker-Planck simulation, and then proceed to describe results from numerical simulation of inertial fusion plasma in a pedagogical manner by discussing some key numerical algorithm developments that enabled the research to take place. A qualitative comparison of the techniques is also given.

Thomas, A. G. R.; Tzoufras, M.; Robinson, A. P. L.; Kingham, R. J.; Ridgers, C. P.; Sherlock, M.; Bell, A. R.

2012-02-01

147

Physical modeling and analysis of rain and clouds by anisotropic scaling multiplicative processes  

Microsoft Academic Search

We argue that the basic properties of rain and cloud fields (particularly their scaling and intermittency) are best understood in terms of coupled (anisotropic and scaling) cascade processes. We show how such cascades provide a framework not only for theoretically and empirically investigating these fields, but also for constructing physically based stochastic models. This physical basis is provided by cascade

Daniel Schertzer; Shaun Lovejoy

1987-01-01

148

Massively Parallel Fokker-Planck Calculations  

Microsoft Academic Search

The Fokker-Planck package FPPAC, which solves the complete nonlinear multispecies Fokker-Planck collision operator for a plasma in two-dimensional velocity space, has been rewritten for the Connection Machine 2. This has involved allocation of variables either to the front end or the CM2, minimization of data flow, and replacement of Cray-optimized algorithms with ones suitable for a massively parallel architecture. Coding

Arthur A. Mirin

1990-01-01

149

What is the energy scale of the physics responsible for neutrino masses?  

Microsoft Academic Search

The observed tiny but non-zero neutrino masses are often interpreted as evidence for new physics at energy scales above 1010 TeV. This statement is based on several assumptions, including (a) neutrinos are Ma-jorana fermions, (b) the physics responsible for neutrino masses is not very weakly coupled, and (c) the new physics sector - responsible for lepton number breaking - couples

André de Gouvêa; James Jenkins

2008-01-01

150

Developing a Rasch Measurement Physical Fitness Scale for Hong Kong Primary School-Aged Students  

ERIC Educational Resources Information Center

|The main purpose of this study was to develop a Rasch Measurement Physical Fitness Scale (RMPFS) based on physical fitness indicators routinely used in Hong Kong primary schools. A total of 9,439 records of students' performances on physical fitness indicators, retrieved from the database of a Hong Kong primary school, were used to develop the…

Yan, Zi; Bond, Trevor G.

2011-01-01

151

Evolving desiderata for validating engineered-physics systems without full-scale testing  

SciTech Connect

Theory and principles of engineered-physics designs do not change over time, but the actual engineered product does evolve. Engineered components are prescient to the physics and change with time. Parts are never produced exactly as designed, assembled as designed, or remain unperturbed over time. For this reason, validation of performance may be regarded as evolving over time. Desired use of products evolves with time. These pragmatic realities require flexibility, understanding, and robustness-to-ignorance. Validation without full-scale testing involves engineering, small-scale experiments, physics theory and full-scale computer-simulation validation. We have previously published an approach to validation without full-scale testing using information integration, small-scale tests, theory and full-scale simulations [Langenbrunner et al. 2008]. This approach adds value, but also adds complexity and uncertainty due to inference. We illustrate a validation example that manages evolving desiderata without full-scale testing.

Langenbrunner, James R [Los Alamos National Laboratory; Booker, Jane M [Los Alamos National Laboratory; Hemez, Francois M [Los Alamos National Laboratory; Ross, Timothy J [Los Alamos National Laboratory

2010-01-01

152

Planck focal plane instruments: advanced modelization and combined analysis  

NASA Astrophysics Data System (ADS)

This thesis is the result of my work as research fellow at IASF-MI, Milan section of the Istituto di Astrofisica Spaziale e Fisica Cosmica, part of INAF, Istituto Nazionale di Astrofisica. This work started in January 2006 in the context of the PhD school program in Astrophysics held at the Physics Department of Universita' degli Studi di Milano under the supervision of Aniello Mennella. The main topic of my work is the software modelling of the Low Frequency Instrument (LFI) radiometers. The LFI is one of the two instruments on-board the European Space Agency Planck Mission for high precision measurements of the anisotropies of the Cosmic Microwave Background (CMB). I was also selected to participate at the International Doctorate in Antiparticles Physics, IDAPP. IDAPP is funded by the Italian Ministry of University and Research (MIUR) and coordinated by Giovanni Fiorentini (Universita' di Ferrara) with the objective of supporting the growing collaboration between the Astrophysics and Particles Physics communities. It is an international program in collaboration with the Paris PhD school, involving Paris VI, VII and XI Universities, leading to a double French-Italian doctoral degree title. My work was performed with the co-tutoring of Jean-Michel Lamarre, Instrument Scientist of the High Frequency Instrument (HFI), the bolometric instrument on-board Planck. Thanks to this collaboration I had the opportunity to work with the HFI team for four months at the Paris Observatory, so that the focus of my activity was broadened and included the study of cross-correlation between HFI and LFI data. Planck is the first CMB mission to have on-board the same satellite very different detection technologies, which is a key element for controlling systematic effects and improve measurements quality.

Zonca, Andrea; Mennella, Aniello

2012-08-01

153

Can basin land use effects on physical characteristics of streams be determined at broad geographic scales?  

USGS Publications Warehouse

The environmental setting (e.g., climate, topography, geology) and land use affect stream physical characteristics singly and cumulatively. At broad geographic scales, we determined the importance of environmental setting and land use in explaining variation in stream physical characteristics. We hypothesized that as the spatial scale decreased from national to regional, land use would explain more of the variation in stream physical characteristics because environmental settings become more homogeneous. At a national scale, stepwise linear regression indicated that environmental setting was more important in explaining variability in stream physical characteristics. Although statistically discernible, the amount of variation explained by land use was not remarkable due to low partial correlations. At level II ecoregion spatial scales (southeastern USA plains, central USA plains, and a combination of the western Cordillera and the western interior basins and ranges), environmental setting variables were again more important predictors of stream physical characteristics, however, as the spatial scale decreased from national to regional, the portion of variability in stream physical characteristics explained by basin land use increased. Development of stream habitat indicators of land use will depend upon an understanding of relations between stream physical characteristics and environmental factors at multiple spatial scales. Smaller spatial scales will be necessary to reduce the confounding effects of variable environmental settings before the effects of land use can be reliably assessed. ?? Springer Science+Business Media B.V. 2006.

Goldstein, R. M.; Carlisle, D. M.; Meador, M. R.; Short, T. M.

2007-01-01

154

Strength Physics at Nano-scale and Application of Optical Interferometry  

Microsoft Academic Search

\\u000a The theoretical basis of the physical mesomechanical approach of strength physics is described. Based on a fundamental principle\\u000a of physics known as local symmetry, this approach is capable of describing deformation and fracture comprehensively, and applicable\\u000a to any scale level. It is thus useful to describe strength physics at the nano\\/microscopic without relying on phenomenology.\\u000a An optical interferometric technique capable

Sanichiro Yoshida

155

Growth index after the Planck results  

NASA Astrophysics Data System (ADS)

The growth index ?L was proposed to investigate the possible deviation from the standard ?CDM model and Einstein’s gravity theory in a dynamical perspective. Recently, thanks to the measurement of the cosmic growth rate via the redshift-space distortion, one can understand the evolution of the density contrast through f?8(z), where f(z)=dln??/dln?a is the growth rate of matter and ?8(z) is the rms amplitude of the density contrast ? at the comoving 8h-1Mpc scale. In this paper, we use the redshift-space distortion data points to study the growth index on the bases of Einstein’s gravity theory and a modified gravity theory under the assumption of f=?m(a)?L. The cosmic background evolution is fixed by the cosmic observations from the type Ia supernovae SNLS3 data, cosmic microwave background radiation data from Planck, and baryon acoustic oscillations. Via the Markov Chain Monte Carlo method, we find the following ?L values for Einstein’s gravity with a cosmological constant (w=const) dark energy and a modified gravity theory in the 1, 2, and 3? regions, respectively: 0.675-0.0662-0.120-0.155+0.0611+0.129+0.178, 0.745-0.0819-0.146-0.190+0.0755+0.157+0.205, and 0.555-0.0167-0.0373-0.0516+0.0193+0.0335+0.0436. In Einstein’s gravity theory, the values of the growth index ?L show an almost 2? deviation from the theoretical prediction of 6/11 for the ?CDM model. However, in the modified gravity framework, a deviation from Einstein’s relativity is not detected in the 1? region. This implies that the currently available cosmic observations do not predict an alternative modified gravity theory beyond the ?CDM model under Einstein’s gravity, but that the simple assumption of f=?m?L should be improved.

Xu, Lixin

2013-10-01

156

Focus on Particle Physics at the TeV Scale  

Microsoft Academic Search

The present research in particle physics has been progressing very quickly in recent decades thanks to the effort of a large and motivated community of experimentalists and theorists. According to an oversimplified scheme, the experimental effort goes along two main lines which we could broadly identify as the 'high-intensity' (or 'high-luminosity') and the 'high-energy' roads. The former includes high-precision and

Antonio Ereditato; Takaaki Kajita; Antonio Masiero

2007-01-01

157

Innovative dimensional metrology of meso-scale physics targets.  

SciTech Connect

For Indirect-drive inertial confinement fusion (ICF) ignition at the National Ignition Facility (NIF): (1) Shock timing measurement and predictive capabilities must be accurate to - 100 ps. (2) Ablator burn through measurement and predictive capabilities must be accurate to -5%. How accurate are our present capabilities? As a first step, we are using planar ablator samples in 'square pulse' Omega halfraum experiments to validate our measurement and predictive capabilities and our understanding of indirect-drive ablator physics issues.

Sebring, R. J. (Robert J.); Reinovsky, R. E. (Robert E.); Edwards, J. M. (John M.); Nobile, A. (Arthur), Jr.; Anderson, W. E. (Wallace E.); Olson, R. E. (Richard E.)

2002-01-01

158

The Planck-ATCA Coeval Observations project: the faint sample  

NASA Astrophysics Data System (ADS)

The Planck-ATCA Coeval Observations (PACO) project collected data between 4.5 and 40 GHz for 482 sources selected within the Australia Telescope 20 GHz (AT20G) catalogue and observed with the Australia Telescope Compact Array. Observations were done almost simultaneously with the Planck satellite, in the period between 2009 July and 2010 August. In this paper, we present and discuss the data for the complete sample of 159 sources with SAT20G > 200 mJy in the South Ecliptic Pole region. The Planck Early Release Compact Source Catalogue (ERCSC) contains 57 of our sources. A comparison between the PACO catalogue and the ERCSC confirms that the reliability of the latter is better than 95 per cent. The missing ERCSC sources are typically associated with the Large Magellanic Cloud, the Milky Way or are otherwise extended. The spectral analysis of the PACO faint catalogue shows a spectral steepening of the sources at high frequencies, confirming the results obtained from the PACO bright sample. A comparison with AT20G measurements, carried out, on average, a few years earlier, has demonstrated that, on these time-scales, our sources show a rather high variability with an rms amplitude of ?40 per cent at 20 GHz. The source spectral properties are found not to vary substantially with flux density, except for an increase in the fraction of steep spectrum sources at fainter flux densities. Our data also allow us to extend by a factor of ?5 downwards in flux density the source counts at ?33 and ?40 GHz obtained from the ERCSC. This allows us to substantially improve our control on the contribution of unresolved extragalactic sources to the power spectrum of small-scale fluctuations in cosmic microwave background maps.

Bonavera, Laura; Massardi, Marcella; Bonaldi, Anna; González-Nuevo, Joaquin; de Zotti, Gianfranco; Ekers, Ronald D.

2011-09-01

159

Management of the Herschel/Planck Programme  

NASA Astrophysics Data System (ADS)

The development of the Herschel and Planck Programme, the largest scientific space programme of the European Space Agency (ESA), has culminated in May 2009 with the successful launch of the Herschel and Planck satellites onboard an Ariane 5 from the European Spaceport in Kourou. Both satellites are operating flawlessly since then and the scientific payload instruments provide world-class science. The Herschel/Planck Programme is a multi national cooperation with the managerial lead being taken by the European Space Agency with the major contributions from European industry for the spacecraft development and from scientific institutes, organized in five international consortia, for the payload instruments. The overall programme complexity called for various, adapted, management approaches to resolve technical and programmatic difficulties. Some of the management experiences of over a decade needed to realize such a satellite programme will be presented giving the lessons learnt for future programmes with the similar complexities.

Passvogel, Thomas; Crone, Gerald

2010-07-01

160

Straight-edge diffraction of Planck radiation  

SciTech Connect

The irradiance diffraction profile of a straight edge is given as a Taylor series in powers of the distance from the geometrical shadow boundary to any point in the profile for monochromatic radiation. The coefficients of the series, which are obtained as simple analytic expressions, are proportional to the real part of a complex number whose phase cycles through a complete period every eight terms in the series. Integration of this series over a Planck distribution of radiation yields the power series for the Planck profile; this derived series has a finite radius of convergence. The asymptotic series for the Planck profile far from the shadow boundary and beyond the radius of convergence of its power series is obtained by analytic continuation of the power series with the aid of a Barnes type of integral representation.

Mohr, Peter J. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8420 (United States); Shirley, Eric L. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8441 (United States)

2006-11-15

161

Planck satellite to be presented to media  

NASA Astrophysics Data System (ADS)

Planck will make the most accurate maps yet of the microwave background radiation that fills space. It will be sensitive to temperature variations of a few millionths of a degree and will map the full sky in nine wavelengths. The immediate outcome of the Big Bang and the initial conditions for the evolution in the universe’s structure are the primary target of this important mission. From the results, a great deal more will be learnt not only about the nature and amount of dark matter, the ‘missing mass’ of the universe, but also about the nature of dark energy and the expansion of the universe itself. To address such challenging objectives, Planck will need to operate at very low, stable temperatures. Once in space, its detectors will have to be cooled to temperature levels close to absolute zero (-273.15ºC), ranging from -253ºC to only a few tenths of a degree above absolute zero. The Planck spacecraft thus has to be a marvel of cryotechnology. After integration, Planck will start a series of tests that will continue into early-2008. It will be launched by end-July 2008 in a dual-launch configuration with Herschel, ESA’s mission to study the formation of galaxies, stars and planetary systems in the infrared. Interested media are invited to fill in the reply form below. Note to editors The Planck spacecraft was built by AAS Cannes, the prime contractor, leading a consortium of industrial partners with the AAS industry branch in Turin, Italy, responsible for the satellite’s service module. ESA and the Danish National Space Centre (Copenhagen, Denmark) are responsible for the hardware provision of Planck’s telescope mirrors, manufactured by EADS Astrium (Friedrichshafen, Germany). AAS Cannes is also responsible for the payload module, the platform that hosts the telescope and the two onboard instruments, HFI and LFI. The instruments themselves are being supplied by a consortium of scientists and institutes led by the Institut d'Astrophysique Spatiale at Orsay (France) in the case of HFI, and by the Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF) in Bologna (Italy) in that of LFI. There are also numerous subcontractors spread throughout Europe, with several more in the USA. For further information, please contact: ESA Media Relations Office Tel: +33(0)1.53.69.7155 Fax: +33(0)1.53.69.7690 Press event programme 1 February 2007, 10:00 am Alcatel Alenia Space 100 Boulevard du Midi, Cannes (France) 10:00 - 10:05 - Opening address, by Patrick Maute - Head of Optical Observation and Science Programmes - Alcatel Alenia Space, and by Jacques Louet - Head of Science Projects - ESA 10:05 - 10:15 - Herschel/Planck Mission overview, by Thomas Passvogel - Planck Project Manager - ESA 10:15 - 10:25 - Planck satellite, by Jean-Jacques Juillet - Programme Manager - Alcatel Alenia Space 10:25 - 10:35 - The scientific mission, by Jan Tauber - Planck Project Scientist - ESA 10:35 - 10:45 - The High-Frequency Instrument, by Jean-Loup Puget - HFI Principal Investigator 10:45 - 10:55 - The Low-Frequency Instrument, by Reno Mandolesi - LFI Principal Investigator 10:55 - 11:05 - Special guest - Nobel prize winner G.F. Smoot 11:05 - 11:25 - Questions and answers 11:25 - 12:35 - Visit of the integration room to see Planck spacecraft and face-to-face interviews 12:45 - 14:30 - Lunch hosted by Alcatel Alenia Space.

2007-01-01

162

Number theory as the ultimate physical theory  

Microsoft Academic Search

At the Planck scale doubt is cast on the usual notion of space-time and one cannot think about elementary particles. Thus,\\u000a the fundamental entities of which we consider our Universe to be composed cannot be particles, fields or strings. In this\\u000a paper the numbers are considered as the fundamental entities. We discuss the construction of the corresponding physical theory.\\u000a A

Igor V. Volovich

2010-01-01

163

Scaling of IFR propagation physics with beam/channel parameters  

NASA Astrophysics Data System (ADS)

The equations of motion of beam and channel particles are analyzed in the ion focused regime. Using the paraxial approximation and assuming only transverse electro-magnetostatic interactions between beam and channel particles for the equations of motion (the same equations solved in the BUCKSHOT code) are written in non-dimensional form and scaling relations are derived for propagation parameters, magnetic erosion, and evaporation. These relations are very useful in doing parameter studies with a limited number of computer simulations.

Shokair, I. R.

1992-05-01

164

Can Basin Land Use Effects on Physical Characteristics of Streams Be Determined at Broad Geographic Scales?  

Microsoft Academic Search

The environmental setting (e.g., climate, topography, geology) and land use affect stream physical characteristics singly\\u000a and cumulatively. At broad geographic scales, we determined the importance of environmental setting and land use in explaining\\u000a variation in stream physical characteristics. We hypothesized that as the spatial scale decreased from national to regional,\\u000a land use would explain more of the variation in stream

Robert M. Goldstein; Daren M. Carlisle; Michael R. Meador; Terry M. Short

2007-01-01

165

Watt balance experiments for the determination of the Planck constant and the redefinition of the kilogram  

NASA Astrophysics Data System (ADS)

Since 1889 the international prototype of the kilogram has served as the definition of the unit of mass in the International System of Units (SI). It is the last material artefact to define a base unit of the SI, and it influences several other base units. This situation is no longer acceptable in a time of ever increasing measurement precision. It is therefore planned to redefine the unit of mass by fixing the numerical value of the Planck constant. At the same time three other base units, the ampere, the kelvin and the mole, will be redefined. As a first step, the kilogram redefinition requires a highly accurate determination of the Planck constant in the present SI system, with a relative uncertainty of the order of 1 part in 108. The most promising experiment for this purpose, and for the future realization of the kilogram, is the watt balance. It compares mechanical and electrical power and makes use of two macroscopic quantum effects, thus creating a relationship between a macroscopic mass and the Planck constant. In this paper the background for the choice of the Planck constant for the kilogram redefinition is discussed and the role of the Planck constant in physics is briefly reviewed. The operating principle of watt balance experiments is explained and the existing experiments are reviewed. An overview is given of all presently available experimental determinations of the Planck constant, and it is shown that further investigation is needed before the redefinition of the kilogram can take place. This article is based on a lecture given at the International School of Physics ‘Enrico Fermi’, Course CLXXXV: Metrology and Physical Constants, held in Varenna on 17-27 July 2012. It will also be published in the proceedings of the school, edited by E Bava, M Kühne and A M Rossi (IOS Press, Amsterdam and SIF, Bologna).

Stock, M.

2013-02-01

166

On the statistical significance of the bulk flow measured by the Planck satellite  

NASA Astrophysics Data System (ADS)

A recent analysis of data collected by the Planck satellite detected a net dipole at the location of X-ray selected galaxy clusters, corresponding to a large-scale bulk flow extending at least to z ~ 0.18, the median redshift of the cluster sample. The amplitude of this flow, as measured with Planck, is consistent with earlier findings based on data from the Wilkinson Microwave Anisotropy Probe (WMAP). However, the uncertainty assigned to the dipole by the Planck team is much larger than that found in the WMAP studies, leading the authors of the Planck study to conclude that the observed bulk flow is not statistically significant. Here, we show that two of the three implementations of random sampling used in the error analysis of the Planck study lead to systematic overestimates in the uncertainty of the measured dipole. Random simulations of the sky do not take into account that the actual realization of the sky leads to filtered data that have a 12% lower root-mean-square dispersion than the average simulation. Using rotations around the Galactic pole (the Z axis), increases the uncertainty of the X and Y components of the dipole and artificially reduces the significance of the dipole detection from 98-99% to less than 90% confidence. When either effect is taken into account, the corrected errors agree with those obtained using random distributions of clusters on Planck data, and the resulting statistical significance of the dipole measured by Planck is consistent with that of the WMAP results.

Atrio-Barandela, F.

2013-09-01

167

Large-Scale Integration of Human Genetic and Physical Maps  

PubMed Central

Genetic maps are used routinely in family-based linkage studies to identify the rough location of genes that influence human traits and diseases. Unlike physical maps, genetic maps are based on the amount of recombination occurring between adjacent loci rather than the actual number of bases separating them. Genetic maps are constructed by statistically characterizing the number of crossovers observed in parental meioses leading to the transmission of alleles to their offspring. Considerations such as the number of meioses observed, the heterozygosity and physical distance between the loci studied, and the statistical methods used can impact the construction and reliability of a genetic map. As is well known, poorly constructed genetic maps can have adverse effects on linkage mapping studies. With the availability of sequence-based maps, as well as genetic maps generated by different researchers (such as those generated by the Marshfield and deCODE groups), one can investigate the compatibility and properties of different maps. We have integrated information from the most current human genome sequence data (UCSC genome assembly Human July 2003) as well as 8399 microsatellite markers used in the Marshfield and deCODE maps to reconcile the these maps. Our efforts resulted in updated sex-specific genetic maps.

Nievergelt, Caroline M.; Smith, Douglas W.; Kohlenberg, J. Bradley; Schork, Nicholas J.

2004-01-01

168

The Effects of Cloud-Scale Physics Variability on Convection  

NASA Astrophysics Data System (ADS)

Convective momentum transport is highly variable in both space and time, but this variability is currently not captured adequately in climate model parameterizations. Many processes with a large effect on global circulation, namely ENSO, are highly sensitive to convection representations. We investigate the effects of uncertainty in the simulation of several key convective processes on the variability of the mean climate. A two-track strategy is developed to investigate stochastic variability, with one track examining idealized parametric spectra and the other track examining more realistic spectra. The climate response to perturbations of these parameters is simulated using version 4 of NCAR's Community Climate System Model. In the idealized experiments, the constant parameters in the representations have been replaced with variable parameters, perturbed by white and red noise about the standard value within the ranges cited in literature. Model diagnostic tools are utilized in the analysis of the results to investigate the effects on large-scale phenomena. Our analysis focuses on sub-seasonal and inter-seasonal events, such as the Madden Julian Oscillation. While maintaining energy balance, the experiments indicate basin and sub-continental scale changes in distributions of convective activity. Furthermore we intend to utilize realistic spectra of perturbations, while constraining parameters based on the results of cloud resolving model data. This more realistic treatment of convection, allowing key convective parameters to vary between synoptic systems, is expected to improve global circulation and the simulation of ENSO.

Nolan, L.; Collins, W.

2011-12-01

169

The feedback on physical appearance scale (FOPAS): Questionnaire development and psychometric evaluation  

Microsoft Academic Search

The development and initial validation of a measure designed to assess physical appearance-related verbal and nonverbal external feedback are described. The factor structure of the Feedback on Physical Appearance Scale (FOPAS) was replicable across two samples that completed the measure based on different instructional protocols. Reliability and convergence with measures of body image, eating disturbance, and global psychological functioning were

Stacey Tantleff-Dunn; J. Kevin Thompson; Michael E. Dunn

1995-01-01

170

Developing an Attitude Scale for the Profession of Physical Education Teaching (ASPPET)  

ERIC Educational Resources Information Center

In this study, the development of a Likert-type attitude scale for the profession of physical education teaching (ASPPET) was aimed. The group of the study was consisted of totally 556 pre-service physical education teachers. In order to determine the structural validity of ASPPET, an exploratory and confirmative factor analyses were performed. A…

Unlu, Huseyin

2011-01-01

171

Nuclear Physics from QCD: The Anticipated Impact of Exa-Scale Computing  

SciTech Connect

I discuss highlights in the progress that is being made toward calculating processes of importance in nuclear physics from QCD using high performance computing. As exa-scale computing resources are expected to become available around 2017, I present current estimates of the computational resources required to accomplish central goals of nuclear physics.

Savage, Martin J. [Department of Physics, University of Washington, Seattle, WA 98195-1560 (United States)

2011-05-23

172

Using Rasch modeling to re-evaluate three scales related to physical activity: enjoyment, perceived benefits and perceived barriers  

Microsoft Academic Search

Studies suggest that enjoyment, perceived bene- fits and perceived barriers may be important mediators of physical activity. However, the psychometric properties of these scales have not been assessed using Rasch modeling. The purpose of this study was to use Rasch modeling to evaluate the properties of three scales com- monly used in physical activity studies: the Physical Activity Enjoyment Scale,

K. C. Heesch; L. C. Masse; A. L. Dunn

2006-01-01

173

Fast algorithms for numerical, conservative, and entropy approximations of the Fokker-Planck-Landau equation  

SciTech Connect

We present fast numerical algorithms to solve the nonlinear Fokker-Planck-Landau equation in 3D velocity space. The discretization of the collision operator preserves the properties required by the physical nature of the Fokker-Planck-Landau equation, such as the conservation of mass, momentum, and energy, the decay of the entropy, and the fact that the steady states are Maxwellians. At the end of this paper, we give numerical results illustrating the efficiency of these fast algorithms in terms of accuracy and CPU time. 20 refs., 7 figs.

Buet, C. [CEA-CEL-V, Villeneuve Saint Georges (France); Cordier [Universite de Paris VI, Paris (France); Degond, P.; Lemou, M. [Universite Paul Sabatier, Toulouse (France)

1997-05-15

174

Validity, Reliability, and Invariance of the Situational Motivation Scale (SIMS) Across Diverse Physical Activity Contexts  

Microsoft Academic Search

This research assessed the reliability, presence of a proposed simplex pattern (construct validity), factorial validity, and multisample invariance of the Situ- ational Motivation Scale (SIMS; Guay, Vallerand, & Blanchard, 2000). In Study 1, data were collected from three physical activity samples. After establishing internal consistencies for all scales, bivariate and interfactor correlations were calculated and the results supported a simplex

Martyn Standage; Joan L. Duda; Keven A. Prusak

2003-01-01

175

Scaling in Condensed Matter Physics: the Kondo Problem, Aggregation, and the Random-Field Ising Model  

Microsoft Academic Search

Scaling concepts are applied to three problems in condensed matter physics. The N -orbital, single impurity Kondo problem is shown to be equivalent to an N -state Potts model in one dimension with inverse-square interactions. Using renormalization techniques, it is found that the peak in the static magnetic susceptibility at finite N develops into a discontinuity as Ntoinfty. A scaling

Madeleine Patrice Gelband

1987-01-01

176

An ultra-low-power physics package for a chip-scale atomic clock  

Microsoft Academic Search

We report the design and measured thermal and mechanical performance of an ultra-low-power physics package for a chip-scale atomic clock (CSAC). This physics package enables communications and navigation systems that require a compact, low-power atomic frequency standard. The physics package includes a unique combination of thermal isolation, mechanical stability and robustness, and small package volume. We have demonstrated temperature control

Mark J. Mescher; R. Lutwak; Mathew Varghese

2005-01-01

177

Seismic-Scale Rock Physics of Methane Hydrate  

SciTech Connect

We quantify natural methane hydrate reservoirs by generating synthetic seismic traces and comparing them to real seismic data: if the synthetic matches the observed data, then the reservoir properties and conditions used in synthetic modeling might be the same as the actual, in-situ reservoir conditions. This approach is model-based: it uses rock physics equations that link the porosity and mineralogy of the host sediment, pressure, and hydrate saturation, and the resulting elastic-wave velocity and density. One result of such seismic forward modeling is a catalogue of seismic reflections of methane hydrate which can serve as a field guide to hydrate identification from real seismic data. We verify this approach using field data from known hydrate deposits.

Amos Nur

2009-01-08

178

Technologies for large-scale physical mapping of human chromosomes  

SciTech Connect

Since its inception 6 years ago, the Human Genome Project has made rapid progress towards its ultimate goal of developing the complete sequence of all human chromosomes. This progress has been made possible through the development of automated devices by laboratories throughout the world that aid the molecular biologist in various phases of the project. The initial phase involves the generation of physical and genetic maps of each chromosome. This task is nearing completion at a low resolution level with several instances of very high detailed maps being developed for isolated chromosomes. In support of the initial mapping thrust of this program, the robotics and automation effort at Los Alamos National Laboratory has developed DNA gridding technologies along with associated database and user interface systems. This paper will discuss these systems in detail and focus on the formalism developed for subsystems which allow for facile system integration.

Beugelsdijk, T.J.

1994-12-01

179

Testing the Applicability of Nernst-Planck Theory in Ion Channels: Comparisons with Brownian Dynamics Simulations  

Microsoft Academic Search

The macroscopic Nernst-Planck (NP) theory has often been used for predicting ion channel currents in recent years, but the validity of this theory at the microscopic scale has not been tested. In this study we systematically tested the ability of the NP theory to accurately predict channel currents by combining and comparing the results with those of Brownian dynamics (BD)

Chen Song; Ben Corry; Jörg Langowski

2011-01-01

180

Discrete-ordinate method of solution of Fokker-Planck equations with nonlinear coefficients  

NASA Astrophysics Data System (ADS)

A discrete-ordinate method [J. Comput. Phys. 55, 313 (1984)] based on nonclassical polynomials is applied to the solution of a large class of Fokker-Planck equations with nonlinear coefficients. These Fokker-Planck equations arise in the description of nonequilibrium processes in reactive systems, laser systems, and model systems with bistable potentials. This subject has received considerable attention in recent years in connection with stochastic processes in physics, cooperative phenomena, and synergetics. The present approach is based on an eigenfunction expansion of the time-dependent probability density function. A discrete-ordinate method is employed in a numerical calculation of the eigenvalues and corresponding eigenfunctions of the Fokker-Planck operator. A general procedure for determining the eigenvalue spectrum of such Fokker-Planck operators with the discrete-ordinate method based on nonclassical polynomials, constructed so as to give rapid convergence of the eigenvalues, is described. The method is applied to several systems which include a model problem for which an analytic solution is known, a model with a triple-well potential in the Schrödinger equation equivalent to the Fokker-Planck equation, and to a model for the the trans-gauche isomerization of n-butane in carbon tetrachloride. The present methods for studying eigenvalue and boundary-value problems should be applicable to a wide variety of problems in addition to those presented here.

Blackmore, R.; Shizgal, B.

1985-03-01

181

How Measuring the Planck Constant gets to an Electronic Kilogram Standard  

SciTech Connect

The best measurement of the Planck constant is now derived from the watt balance method. This method measures mechanical power, in reference units of the kilogram (artifact mass standard), second (atomic clocks), and meter (lasers), in ratio to electrical power, in reference units of the volt (Josephson effect) and ohm (quantum Hall effect). Of these reference standards, only the kilogram is still an artifact standard. Thus a high precision measurement of the Planck constant is equivalent to monitoring the SI kilogram artifact, and may be used to redefine the kilogram. This talk will summarize the complexity of making a Planck constant measurement, where there are interesting aspects of basic physics that appear when the ultimate precision of the standards laboratory is applied to obtain an uncertainty of 20 parts in a billion.

Steiner, Richard

2007-08-01

182

The development and validation of the pictorial motivation scale in physical activity  

Microsoft Academic Search

The purpose of the present research was to report the validation of the pictorial motivation scale in English. This scale\\u000a is designed for adolescents and adults with an intellectual disability who are unable to independently read a questionnaire.\\u000a The scale has a picture and phrase depicting 16 items related to participation in sport and physical activity; four for each\\u000a of

Greg Reid; Robert J. Vallerand; Carole Poulin; Peter Crocker

2009-01-01

183

Axion hot dark matter bounds after Planck  

NASA Astrophysics Data System (ADS)

We use cosmological observations in the post-Planck era to derive limits on thermally produced cosmological axions. In the early universe such axions contribute to the radiation density and later to the hot dark matter fraction. We find an upper limit ma < 0.67 eV at 95% C.L. after marginalising over the unknown neutrino masses, using CMB temperature and polarisation data from Planck and WMAP respectively, the halo matter power spectrum extracted from SDSS-DR7, and the local Hubble expansion rate H0 released by the Carnegie Hubble Program based on a recalibration of the Hubble Space Telescope Key Project sample. Leaving out the local H0 measurement relaxes the limit somewhat to 0.86 eV, while Planck+WMAP alone constrain the axion mass to 1.01 eV, the first time an upper limit on ma has been obtained from CMB data alone. Our axion limit is therefore not very sensitive to the tension between the Planck-inferred H0 and the locally measured value. This is in contrast with the upper limit on the neutrino mass sum, which we find here to range from ? m? < 0.27 eV at 95% C.L. combining all of the aforementioned observations, to 0.84 eV from CMB data alone.

Archidiacono, Maria; Hannestad, Steen; Mirizzi, Alessandro; Raffelt, Georg; Wong, Yvonne Y. Y.

2013-10-01

184

Sub-Planck structures and Quantum Metrology  

Microsoft Academic Search

The significance of sub-Planck structures in relation to quantum metrology is explored, in close contact with experimental setups. It is shown that an entangled cat state can enhance the accuracy of parameter estimations. The possibilty of generating this state, in dissipative systems has also been demonstrated. Thereafter, the quantum Cramer-Rao bound for phase estimation through a pair coherent state is

Prasanta K. Panigrahi; Abhijeet Kumar; Utpal Roy; Suranjana Ghosh

2011-01-01

185

Planck blackbody emissive power in particulate media  

Microsoft Academic Search

Modifications of the Planck blackbody intensity and emissive power are proposed due to the modifications of the photon energy transport velocity and the density of states in particulate media. These modifications result from the multiple scattering of photons. These modifications affect the heat flux and temperature predictions in particulate media. Results show that current methods of predicting heat flux and

Ravi Prasher

2005-01-01

186

Planck/LFI DPC Software Integration plan  

NASA Astrophysics Data System (ADS)

A very spread software project needs to be well defined through software integration and development plan to avoid extra work in the pipeline creation phase. Here we will describe the rationale in the case of the Planck/LFI DPC project and what was designed and developed to build the integration environment.

Zacchei, A.; Vuerli, C.; Lama, N.; Pasian, F.

2004-07-01

187

On the Fokker-Planck-Boltzmann equation  

Microsoft Academic Search

We consider the Boltzmann equation perturbed by Fokker-Planck type operator. To overcome the lack of strong a priori estimates and to define a meaningful collision operator, we introduce a notion of renormalized solution which enables us to establish stability results for sequences of solutions and global existence for the Cauchy problem with large data. The proof of stability and existence

R. J. DiPerna; P.-L. Lions

1988-01-01

188

Max-Planck-Institut für Radioastronomie  

NASA Astrophysics Data System (ADS)

Founded in 1966, the Max-Planck-Institut für Radioastronomie in Bonn is one of the centers for radio astronomical research in Germany. Main fields of research include the interstellar medium of our own and external galaxies, cosmic magnetic fields, pulsars, star formation, late stages of stellar evolution, active galactic nuclei, theoretical high-energy astrophysics, and observational cosmology. ...

Murdin, P.

2000-11-01

189

Upscaling Physics-based Models to Estimate Catchment Scale Effects of Localised Tree Planting  

NASA Astrophysics Data System (ADS)

Much of our knowledge about the changes in hydrology related to land use and land management is limited to the very small scale (e.g. changes in water retention properties, interception and runoff processes); however, we are generally most interested in the associated changes in flow regime at the catchment scale. A key methodological challenge is therefore how to upscale information about local scale changes. We present a model upscaling procedure that aims to quantify the changes in peak flows at multiple scales related to localised tree planting. The procedure divides the catchment into a number of hydrological response units, which are each classified based on soil types and land management. For each hydrological response unit, a physics-based model is developed, incorporating our understanding of hydrological processes and properties. The outputs from these physics-based models are used to train simpler “meta-models”, which are then incorporated into a semi-distributed catchment model. In this way, our understanding of local changes in physical properties can be incorporated into a more flexible and computationally efficient catchment scale conceptual model. This procedure previously performed well when supported by a multi-scale monitoring programme for a 12km2 catchment. The applicability of the procedure is now examined for a 260km2 catchment without supporting multi-scale monitoring. Without local data, physics-based models are developed a priori using information from the literature and qualitative field observations. We explore the significance of the uncertainties due to this lack of data and also uncertainties related to the upscaling procedure itself, particularly examining the identifiability of the predicted effects at multiple scales. Based on our findings we comment on the strengths and limitations of physics-based modelling and the upscaling procedure in terms of ability to predict catchment-scale impacts of local land management interventions.

Ballard, C. E.; Bulygina, N.; McIntyre, N.; Wheater, H. S.

2010-12-01

190

Planck new results: Anomalous Microwave Emission from Galactic clouds  

NASA Astrophysics Data System (ADS)

Planck data, combined with multi-frequency data, has allowed accurate spectra from the radio to far infra-red to be constructed for bright regions in our Galaxy. Spectra for the Perseus and Rho Ophiuchi molecular clouds show strong evidence for Anomalous Microwave Emission (AME) at frequencies 10-100 GHz. The residual spectra, after subtraction of the free-free, CMB and thermal dust components, represent the most precise spectra of AME to date. They show a peaked spectral shape, with a peak at ~30 GHz, as expected from electric dipole radiation from small spinning dust grains. A plausible physical model for the spinning dust can provide a good fit to the data, where the higher density molecular gas accounts for most of the AME, while the lower density atomic gas appears to play a minor role. A search for new AME regions with the Planck data has revealed a number of new candidates showing excess emission at 20-60 GHz. We make a first statistical analysis of AME and non-AME Galactic clouds. We show that a significant fraction of this new sample shows evidence of AME. The emissivity of the AME is comparable to previous detections and is shown to be tightly correlated with thermal dust tracers in the sub-mm and IR. We investigate correlations of derived parameters with the AME emissivity to investigate the nature of the spinning dust.

Davis, Richard; Dickinson, Clive

2012-07-01

191

Inferring physical protein contacts from large-scale purification data of protein complexes.  

PubMed

Recent large-scale data sets of protein complex purifications have provided unprecedented insights into the organization of cellular protein complexes. Several computational methods have been developed to detect co-complexed proteins in these data sets. Their common aim is the identification of biologically relevant protein complexes. However, much less is known about the network of direct physical protein contacts within the detected protein complexes. Therefore, our work investigates whether direct physical contacts can be computationally derived by combining raw data of large-scale protein complex purifications. We assess four established scoring schemes and introduce a new scoring approach that is specifically devised to infer direct physical protein contacts from protein complex purifications. The physical contacts identified by the five methods are comprehensively benchmarked against different reference sets that provide evidence for true physical contacts. Our results show that raw purification data can indeed be exploited to determine high-confidence physical protein contacts within protein complexes. In particular, our new method outperforms competing approaches at discovering physical contacts involving proteins that have been screened multiple times in purification experiments. It also excels in the analysis of recent protein purification screens of molecular chaperones and protein kinases. In contrast to previous findings, we observe that physical contacts inferred from purification experiments of protein complexes can be qualitatively comparable to binary protein interactions measured by experimental high-throughput assays such as yeast two-hybrid. This suggests that computationally derived physical contacts might complement binary protein interaction assays and guide large-scale interactome mapping projects by prioritizing putative physical contacts for further experimental screens. PMID:21451165

Schelhorn, Sven-Eric; Mestre, Julián; Albrecht, Mario; Zotenko, Elena

2011-03-30

192

The patient knows best: significant change in the physical component of the Multiple Sclerosis Impact Scale (MSIS-29 physical)  

PubMed Central

Aim The aims of this study were to determine the reliability, responsiveness and minimally important change score of the Multiple Sclerosis Impact Scale (MSIS)?29 physical using the Expanded Disability Status Scale (EDSS) as an anchor measure. Methods 214 patients with multiple sclerosis (MS) (EDSS 0–8.5) had concurrent MSIS?29 and EDSS assessments at baseline and at up to 4?years of follow?up. Results 116 patients had unchanged EDSS scores. Stability of the MSIS?29 physical (mean change 0.1 points) was better in the 85 patients with EDSS 0–5.0 than in the 31 patients with EDSS 5.5–8.5 in whom the MSIS?29 physical score fell by 8?points, a response shift phenomenon. A floor effect for the MSIS?29 was observed in 5% of stable patients at both time points. 98 patients experienced EDSS change with moderately strong statistically significant correlations between change scores in the EDSS and the MSIS?29 physical (r?=?0.523, p<0.0001). Effect sizes for MSIS?29 physical change were moderate to large. Using receiver operating characteristic curves, the MSIS?29 change score which produced a combination of optimal sensitivity and specificity was chosen for both EDSS ranges. For EDSS range 5.5–8, a change score of 8 had a sensitivity of 87% and specificity of 67%. For EDSS 0–5.0, a change score of 7 had a sensitivity of 78% and a specificity of 51%. Conclusions The MSIS?29 physical performs well over time, and is suitable for use in trials; a minimal change score of 8?points in the MSIS?29 is clinically significant.

Costelloe, Lisa; O'Rourke, Killian; Kearney, Hugh; McGuigan, Christopher; Gribbin, Lisa; Duggan, Marguerite; Daly, Leslie; Tubridy, Niall; Hutchinson, Michael

2007-01-01

193

Construct validity of the physical Education State Anxiety Scale: a multitrait-multimethod approach.  

PubMed

The present study investigated the construct validity of the Physical Education State Anxiety Scale with the employment of multitrait-multimethod analysis with regard to responses of the Competitive State Anxiety Inventory-2. 233 high school students (Mage = 13.6 yr., SD=.9) completed the Physical Education State Anxiety Scale and an adapted physical education version of Competitive State Anxiety Inventory-2. Examination of fit indices and anxiety dimensions' correlations indicated satisfactory convergent validity (significant difference in chi2 and CFI emerged). Convergent validities were higher than correlations among other variables suggesting fairly good discriminant validity; however, the fit indices of the confirmatory factor analyses showed relatively low discriminant validity (nonsignificant delta chi2 and a small CFI difference emerged). Present findings provide evidence on the construct validity of the adapted version and suggest it can be used with high school students to assess state anxiety in physical education. PMID:19235397

Barkoukis, Vassilis; Tsorbatzoudis, Haralambos; Grouios, George

2008-12-01

194

Gyrokinetic Fokker-Planck Collision Operator  

SciTech Connect

The gyrokinetic linearized exact Fokker-Planck collision operator is obtained in a form suitable for plasma gyrokinetic equations, for arbitrary mass ratio. The linearized Fokker-Planck operator includes both the test-particle and field-particle contributions, and automatically conserves particles, momentum, and energy, while ensuring non-negative entropy production. Finite gyroradius effects in both field-particle and test-particle terms are evaluated. When implemented in gyrokinetic simulations, these effects can be precomputed. The field-particle operator at each time step requires the evaluation of a single two-dimensional integral, and is not only more accurate, but appears to be less expensive to evaluate than conserving model operators.

Li, B.; Ernst, D. R. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2011-05-13

195

Lattice Fokker Planck for dilute polymer dynamics.  

PubMed

We show that the actual diffusive dynamics, governing the momentum relaxation of a polymer molecule, and described by a Fokker-Planck equation, may be replaced by a BGK-type relaxation dynamics without affecting the slow (Smoluchowski) dynamics in configuration space. Based on the BGK-type description, we present a lattice-Boltzmann (LB) based direct discretization approach for the phase-space description of inertial polymer dynamics. We benchmark this formulation by determining the bulk rheological properties for both steady and time-dependent shear and extensional flows at moderate to large Weissenberg numbers. Finally, we compare the usefulness of the different discrete velocity models, typically used in the LB framework, for solving diffusive dynamics based on the Fokker-Planck equation. PMID:23944577

Singh, Shiwani; Subramanian, Ganesh; Ansumali, Santosh

2013-07-02

196

Local Fractional Fokker-Planck Equation  

Microsoft Academic Search

New kind of differential equations, called local fractional differential\\u000aequations, has been proposed for the first time. They involve local fractional\\u000aderivatives introduced recently. Such equations appear to be suitable to deal\\u000awith phenomena taking place in fractal space and time. A local fractional\\u000aanalog of Fokker-Planck equation has been derived starting from the\\u000aChapman-Kolmogorov condition. Such an equation is

Kiran M. Kolwankar; Anil D. Gangal

1998-01-01

197

External ear abnormalities in existing scales for minor physical anomalies: are they enough?  

PubMed

The pattern of external ear abnormalities in patients with schizophrenia and bipolar disorder was studied. Sixty-seven male patients having schizophrenia (n=30) and bipolar disorder (n=37) were examined using a scale constructed for the study. Stepwise logistic regression analysis showed that 'prominent crux of helix' and 'ear lobe crease' could differentiate between schizophrenia and bipolar disorder. These external ear abnormalities need further characterization and consideration for possible inclusion in scales that assess minor physical anomalies. PMID:22406391

Praharaj, Samir Kumar; Sarkar, Sukanto; Sinha, Vinod Kumar

2012-03-09

198

Planck/LFI Pipeline -- The Demonstration Model  

NASA Astrophysics Data System (ADS)

LFI is one of the two instruments installed on board Planck, the M3 mission of the ESA Horizon 2000+ program, the main goal of which is to produce maps of the CMB (Cosmic Microwave Background) with an unprecedented combination of angular resolution, sensitivity, spatial coverage, and frequency range. The Demonstration Model (DM) is the second version of the LFI DPC pipeline, built on top of the BBM (Bread-Board Model), released in July 2002. The DM has been integrated at DPC using the Process Coordinator and FITS files for standard data exchange; in the future, instead of using FITS files, the pipeline will be compliant with the Planck DMC (Data Management Component) standard. The DM goal is to demonstrate that the current pipeline is able to handle the foreseen LFI data flow and to perform an end-to-end processing of the data, from telemetry to the production of the scientific results. The DM development was mainly concentrated on understanding and removing systematic effects; at the moment the pipeline is able to detect and remove all systematic effects which are understood and modeled within the Planck simulation pipeline, such as thermal fluctuations, 1/f noise, the side-lobe effects, beam distortion, and so on.

Pasian, F.; Zacchei, A.; Vuerli, C.; Maino, D.; Baccigalupi, C.

2005-12-01

199

Brief scales to assess physical activity and sedentary equipment in the home  

PubMed Central

Background Sedentary behaviors such as TV viewing are associated with childhood obesity, while physical activity promotes healthy weight. The role of the home environment in shaping these behaviors among youth is poorly understood. The study purpose was to examine the reliability of brief parental proxy-report and adolescent self-report measures of electronic equipment and physical activity equipment in the home and to assess the construct validity of these scales by examining their relationship to physical activity, sedentary behavior, and weight status of children and adolescents. Methods Participants were adolescents (n = 189; mean age = 14.6), parents of adolescents (n = 171; mean age = 45.0), and parents of younger children (n = 116; parents mean age = 39.6; children's mean age = 8.3) who completed two surveys approximately one month apart. Measures included a 21-item electronic equipment scale (to assess sedentary behavior facilitators in the home, in the child or adolescent's bedroom, and portable electronics) and a 14-item home physical activity equipment scale. Home environment factors were examined as correlates of children's and adolescents' physical activity, sedentary behavior, and weight status after adjusting for child age, sex, race/ethnicity, household income, and number of children in the home. Results Most scales had acceptable test-retest reliability (intraclass correlations were .54 - .92). Parent and adolescent reports were correlated. Electronic equipment in adolescents' bedrooms was positively related to sedentary behavior. Activity equipment in the home was inversely associated with television time in adolescents and children, and positively correlated with adolescents' physical activity. Children's BMI z-score was positively associated with having a television in their bedroom. Conclusions The measures of home electronic equipment and activity equipment were similarly reliable when reported by parents and by adolescents. Home environment attributes were related to multiple obesity-related behaviors and to child weight status, supporting the construct validity of these scales.

2010-01-01

200

Development of Four Self-Report Measures of Job Stressors and Strain: Interpersonal Conflict at Work Scale, Organizational Constraints Scale, Quantitative Workload Inventory, and Physical Symptoms Inventory  

Microsoft Academic Search

Despite the widespread use of self-report measures of both job-related stressors and strains, relatively few carefully developed scales for which validity data exist are available. In this article, we discuss 3 job stressor scales (Interpersonal Conflict at Work Scale, Organizational Constraints Scale, and Quantitative Workload Inventory) and 1 job strain scale (Physical Symptoms Inventory). Using meta-analysis, we combined the results

Paul E. Spector; Steve M. Jex

1998-01-01

201

Affective Response to Physical Activity: Testing for Measurement Invariance of the Physical Activity Affect Scale across Active and Non-Active Individuals  

ERIC Educational Resources Information Center

|Affective responses to physical activity are assumed to play a role in exercise initiation and maintenance. The Physical Activity Affect Scale measures four dimensions of an individual's affective response to exercise. Group differences in the interpretation of scale items can impact the interpretability of mean differences, underscoring the need…

Carpenter, Laura C.; Tompkins, Sara Anne; Schmiege, Sarah J.; Nilsson, Renea; Bryan, Angela

2010-01-01

202

Computing generalized Langevin equations and generalized Fokker-Planck equations  

PubMed Central

The Mori–Zwanzig formalism is an effective tool to derive differential equations describing the evolution of a small number of resolved variables. In this paper we present its application to the derivation of generalized Langevin equations and generalized non-Markovian Fokker–Planck equations. We show how long time scales rates and metastable basins can be extracted from these equations. Numerical algorithms are proposed to discretize these equations. An important aspect is the numerical solution of the orthogonal dynamics equation which is a partial differential equation in a high dimensional space. We propose efficient numerical methods to solve this orthogonal dynamics equation. In addition, we present a projection formalism of the Mori–Zwanzig type that is applicable to discrete maps. Numerical applications are presented from the field of Hamiltonian systems.

Darve, Eric; Solomon, Jose; Kia, Amirali

2009-01-01

203

A multi-scale approach to the physics of ion beam cancer therapy  

NASA Astrophysics Data System (ADS)

We are developing a multi-scale approach to understanding the physics related to ion/proton-beam cancer therapy and the calculation of the probability of DNA damage as a result of irradiation of tumours with energetic ions (up to 430 MeV/u). This approach is inclusive with respect to different scales, starting from the long scale, defined by the ion stopping, followed by a smaller scale, defined by secondary electrons and radicals, and ending with the shortest scale, defined by interactions of secondaries with the DNA. We present calculations of the probabilities of single and double strand breaks of DNA and suggest a way to further elaborate on such calculations.

Solov'yov, A. V.; Surdutovich, E.; Scifoni, E.; Mishustin, I.; Greiner, W.

2008-12-01

204

Evaluation of Social Cognitive Scaling Response Options in the Physical Activity Domain  

ERIC Educational Resources Information Center

|The purpose of this study was to compare the reliability, variability, and predictive validity of two common scaling response formats (semantic differential, Likert-type) and two numbers of response options (5-point, 7-point) in the physical activity domain. Constructs of the theory of planned behavior were chosen in this analysis based on its…

Rhodes, Ryan E.; Matheson, Deborah Hunt; Mark, Rachel

2010-01-01

205

Validation Studies of the Physical Activity Scale for the Elderly (PASE)  

Cancer.gov

Validation Studies of the Physical Activity Scale for the Elderly (PASE) Harada et al. 2001 Bonnefoy et al. 2001 Washburn et al. 1999 Washburn et al. 1999 Washburn et al. 1993 Harada et al. 2001 See reference #23 Methods Relationship between PASE and

206

Retrospective Assessment of Childhood Sexual and Physical Abuse: A Comparison of Scaled and Behaviorally Specific Approaches  

ERIC Educational Resources Information Center

This study compared retrospective reports of childhood sexual and physical abuse as assessed by two measures: the Childhood Trauma Questionnaire (CTQ), which uses a Likert-type scaling approach, and the Computer Assisted Maltreatment Inventory (CAMI), which employs a behaviorally specific means of assessment. Participants included 1,195…

DiLillo, David; Fortier, Michelle A.; Hayes, Sarah A.; Trask, Emily; Perry, Andrea R.; Messman-Moore, Terri; Fauchier, Angele; Nash, Cindy

2006-01-01

207

Scaling physics and material science applications on a massively parallel Blue Gene\\/L system  

Microsoft Academic Search

Blue Gene\\/L represents a new way to build supercomputers, using a large number of low power processors, together with multiple integrated interconnection networks. Whether real applications can scale to tens of thousands of processors (on a machine like Blue Gene\\/L) has been an open question. In this paper, we describe early experience with several physics and material science applications on

George Almasi; Gyan Bhanot; Alan Gara; Manish Gupta; James C. Sexton; Bob Walkup; Vasily V. Bulatov; Andrew W. Cook; Bronis R. de Supinski; James N. Glosli; Jeffrey A. Greenough; Francois Gygi; Alison Kubota; Steve Louis; Thomas E. Spelce; Frederick H. Streitz; Peter L. Williams; Robert K. Yates; Charles Archer; José E. Moreira; Charles A. Rendleman

2005-01-01

208

Introduction to SCALE-UP : Student-Centered Activities for Large Enrollment University Physics  

Microsoft Academic Search

SCALE-UP is an extension of the highly successful IMPEC project (Integrated Math, Physics, Engineering, and Chemistry), one of NC State's curricular reform efforts undertaken as part of the SUCCEED coalition. Basically, we are utilizing the interactive, collaboratively based instruction that worked so well in smaller class settings and finding ways to economically accommodate classes of up to 100 students. Relative

Robert J. Beichner; Jeffery M. Saul; Rhett J. Allain; Duane L. Deardorff; David S. Abbott

2000-01-01

209

Relation of Physical Form to Spatial Knowledge in Large-Scale Virtual Environments  

ERIC Educational Resources Information Center

|This study used a desktop virtual environmental simulation of 18 large-scale residential environments to test effects of plan layout complexity, physical differentiation, and gender on acquired spatial knowledge. One hundred sixty people (95 males and 65 females) were assigned at random to the different conditions. After a learning phase,…

Cubukcu, Ebru; Nasar, Jack L.

2005-01-01

210

Physical Education Teacher Attitudes toward Fitness Tests Scale: Cross-Revalidation and Modification  

Microsoft Academic Search

This study aimed to provide further evidence of validity and reliability for the Physical Education Teacher Attitudes toward Fitness Tests Scale (PETAFTS), which consisted of affective and cognitive domains. There were two subdomains in the affective domain (i.e., enjoyment of implementing fitness tests and enjoyment of using test results) and one domain in the cognitive domain (i.e., beliefs in the

Xiaofen D. Keating; Jianmin Guan; Robert H. Ferguson; Li Chen; Dwan M. Bridges

2008-01-01

211

Long-term stability of NIST chip-scale atomic clock physics packages  

Microsoft Academic Search

We discuss the long-term stability of the NIST chip-scale atomic clock (CSAC) physics packages. We identify the major factors that currently limit the frequency stability of our CSAC packages after 100 s. The requirements for the stability of the vapor cell and laser temperature, local magnetic field, and local oscillator output power are evaluated. Due to the small size of

S. Knappe; V. Gerginov; V. Shah; A. Brannon; L. Hollberg; J. Kitching

2007-01-01

212

Relation of Physical Form to Spatial Knowledge in Large-Scale Virtual Environments  

ERIC Educational Resources Information Center

This study used a desktop virtual environmental simulation of 18 large-scale residential environments to test effects of plan layout complexity, physical differentiation, and gender on acquired spatial knowledge. One hundred sixty people (95 males and 65 females) were assigned at random to the different conditions. After a learning phase,…

Cubukcu, Ebru; Nasar, Jack L.

2005-01-01

213

Validation Studies of the Physical Activity Scale for the Elderly (PASE)  

Cancer.gov

Validation Studies of the Physical Activity Scale for the Elderly (PASE) Dinger et al. 2004 See reference #79 Methods PASE compared to accelerometry (Spearman correlations) Sample 43 female, 23 male subjects (age = 75.7 ± 7.9 years Summary Results Actigraph

214

MOLECULAR ENVIRONMENTS OF 51 PLANCK COLD CLUMPS IN THE ORION COMPLEX  

SciTech Connect

A mapping survey of 51 Planck cold clumps projected on the Orion complex was performed with J = 1-0 lines of {sup 12}CO and {sup 13}CO with the 13.7 m telescope at the Purple Mountain Observatory. The mean column densities of the Planck gas clumps range from 0.5 to 9.5 Multiplication-Sign 10{sup 21} cm{sup -2}, with an average value of (2.9 {+-} 1.9) Multiplication-Sign 10{sup 21} cm{sup -2}. The mean excitation temperatures of these clumps range from 7.4 to 21.1 K, with an average value of 12.1 {+-} 3.0 K and the average three-dimensional velocity dispersion {sigma}{sub 3D} in these molecular clumps is 0.66 {+-} 0.24 km s{sup -1}. Most of the clumps have {sigma}{sub NT} larger than or comparable to {sigma}{sub Therm}. The H{sub 2} column density of the molecular clumps calculated from molecular lines correlates with the aperture flux at 857 GHz of the dust emission. By analyzing the distributions of the physical parameters, we suggest that turbulent flows can shape the clump structure and dominate their density distribution on large scales, but not function on small scales due to local fluctuations. Eighty-two dense cores are identified in the molecular clumps. The dense cores have an average radius and local thermal equilibrium (LTE) mass of 0.34 {+-} 0.14 pc and 38{sup +5}{sub -30} M{sub Sun }, respectively. The structures of low column density cores are more affected by turbulence, while the structures of high column density cores are more affected by other factors, especially by gravity. The correlation of velocity dispersion versus core size is very weak for the dense cores. The dense cores are found to be most likely gravitationally bounded rather than pressure confined. The relationship between M{sub vir} and M{sub LTE} can be well fitted with a power law. The core mass function here is much flatter than the stellar initial mass function. The lognormal behavior of the core mass distribution is most likely determined by internal turbulence.

Liu Tie; Wu Yuefang; Zhang Huawei, E-mail: liutiepku@gmail.com, E-mail: ywu@pku.edu.cn [Department of Astronomy, Peking University, 100871 Beijing (China)

2012-09-15

215

Molecular Environments of 51 Planck Cold Clumps in the Orion Complex  

NASA Astrophysics Data System (ADS)

A mapping survey of 51 Planck cold clumps projected on the Orion complex was performed with J = 1-0 lines of 12CO and 13CO with the 13.7 m telescope at the Purple Mountain Observatory. The mean column densities of the Planck gas clumps range from 0.5 to 9.5 × 1021 cm-2, with an average value of (2.9 ± 1.9) × 1021 cm-2. The mean excitation temperatures of these clumps range from 7.4 to 21.1 K, with an average value of 12.1 ± 3.0 K and the average three-dimensional velocity dispersion ?3D in these molecular clumps is 0.66 ± 0.24 km s-1. Most of the clumps have ?NT larger than or comparable to ?Therm. The H2 column density of the molecular clumps calculated from molecular lines correlates with the aperture flux at 857 GHz of the dust emission. By analyzing the distributions of the physical parameters, we suggest that turbulent flows can shape the clump structure and dominate their density distribution on large scales, but not function on small scales due to local fluctuations. Eighty-two dense cores are identified in the molecular clumps. The dense cores have an average radius and local thermal equilibrium (LTE) mass of 0.34 ± 0.14 pc and 38+5 - 30 M?, respectively. The structures of low column density cores are more affected by turbulence, while the structures of high column density cores are more affected by other factors, especially by gravity. The correlation of velocity dispersion versus core size is very weak for the dense cores. The dense cores are found to be most likely gravitationally bounded rather than pressure confined. The relationship between M vir and M LTE can be well fitted with a power law. The core mass function here is much flatter than the stellar initial mass function. The lognormal behavior of the core mass distribution is most likely determined by internal turbulence.

Liu, Tie; Wu, Yuefang; Zhang, Huawei

2012-09-01

216

Full Linearized Fokker-Planck Collisions in Neoclassical and Gyrokinetic Transport Simulations  

NASA Astrophysics Data System (ADS)

The full linearized Fokker-Planck collision operator has been implemented in the drift-kinetic code NEO and the effects on multi-species neoclassical transport are studied. Fast numerical algorithms for treatment of the field particle operator that can accurately treat the disparate velocity scales that arise for multi-species plasmas are presented and compared. The method is Eulerian-based and uses a Legendre series expansion in pitch angle and a novel Laguerre spectral method in energy, which is introduced to ameliorate the rapid numerical precision loss that occurs for traditional Laguerre spectral methods. With NEO, the physical accuracy and limitations of commonly-used model collision operators, such as the Connor and Hirshman-Sigmar operators, as well as models with ad hoc momentum restoring terms, are studied, and the effects on neoclassical impurity poloidal flows and neoclassical transport for experimental parameters are explored. Extension of the method for use in linear gyrokinetic stability calculations of the highly-collisional plasma edge is also explored.

Belli, E. A.; Candy, J.

2011-11-01

217

Fokker-Planck equation in mirror research  

SciTech Connect

Open confinement systems based on the magnetic mirror principle depend on the maintenance of particle distributions that may deviate substantially from Maxwellian distributions. Mirror research has therefore from the beginning relied on theoretical predictions of non-equilibrium rate processes obtained from solutions to the Fokker-Planck equation. The F-P equation plays three roles: Design of experiments, creation of classical standards against which to compare experiment, and predictions concerning mirror based fusion power systems. Analytical and computational approaches to solving the F-P equation for mirror systems will be reviewed, together with results and examples that apply to specific mirror systems, such as the tandem mirror.

Post, R.F.

1983-08-11

218

The stability of polysiloxanes incorporating nano-scale physical property modifiers  

NASA Astrophysics Data System (ADS)

Reported here is the synthesis and subsequent characterization of the physical and chemical properties of novel polysiloxane elastomers modified with a series of polyhedraloligomericsilsequioxane (POSS) molecular silicas. The physical properties of the formulated nanocomposite systems have been characterized with a combination of dynamic mechanical analysis (DMA), broadband dielectric spectroscopy (BDS) and confocal Raman microscopy. The results of the physical property characterization demonstrate that the incorporation of low levels (1-4% by wt.) of POSS particles into the polysiloxane network leads to significant improvements in the mechanical properties of the elastomer and significantly alters the motional chain dynamics of the system as a whole. The results of studies performed to assess the long-term stability of these novel nanocomposite systems have demonstrated that POSS physical property modifiers can significantly alter the thermal stability of polysiloxane elastomers. Physically dispersed POSS has also been shown in some cases to be both mobile and disruptive within the polysiloxane networks, agglomerating into domains on a micron scale and migrating to the surface of the elastomers. This work demonstrates both the potential of POSS nanoparticles as physical property modifiers and describes the effects of POSS on the physical and chemical stability of polysiloxane systems.

Lewicki, James P.; Patel, Mogon; Morrell, Paul; Liggat, John; Murphy, Julian; Pethrick, Richard

2008-04-01

219

Teleportation fidelity as a probe of sub-Planck phase-space structure  

SciTech Connect

We investigate the connection between sub-Planck structure in the Wigner function and the output fidelity of continuous-variable teleportation protocols. When the teleporting parties share a two-mode squeezed state as an entangled resource, high fidelity in the output state requires a squeezing large enough that the smallest sub-Planck structures in an input pure state are teleported faithfully. We formulate this relationship, which leads to an explicit relation between the fine-scale structure in the Wigner function and large-scale extent of the Wigner function, and we treat specific examples, including coherent, number, and random states and states produced by chaotic dynamics. We generalize the pure-state results to teleportation of mixed states.

Scott, A.J. [Centre for Quantum Computer Technology and Centre for Quantum Dynamics, Griffith University, Brisbane, Qld 4111 (Australia)], E-mail: andrew.scott@griffith.edu.au; Caves, Carlton M. [Department of Physics and Astronomy, MSC07-4220, University of New Mexico, Albuquerque, NM 87131-0001 (United States); Department of Physics, University of Queensland, Brisbane, Qld 4072 (Australia)], E-mail: caves@info.phys.unm.edu

2008-11-15

220

Quasilinear simulation of auroral kilometric radiation by a relativistic Fokker-Planck code  

SciTech Connect

An intense terrestrial radiation called the auroral kilometric radiation (AKR) is believed to be generated by cyclotron maser instability. We study a quasilinear evolution of this instability by means of a two-dimensional relativistic Fokker-Planck code which treats waves and distributions self-consistently, including radiation loss and electron source and sink. We compare the distributions and wave amplitude with spacecraft observations to elucidate physical processes involved. 3 refs., 1 fig.

Matsuda, Y.

1991-01-01

221

Rosseland and Planck mean and multi-group opacities of weakly non-ideal Flibe plasma  

Microsoft Academic Search

In this article we investigate the physics and develop a theoretical model to perform computations of the Rosseland and Planck mean and multi-group opacities of weakly non-ideal Flibe plasma generated in the inertial fusion energy chamber. Ionization equilibrium and partition functions of all Flibe plasma species are modelled considering the plasma environmental influence (non-ideal effects) on the electronic structure in

Mofreh R Zaghloul

2007-01-01

222

Magnetic dipole and quadrupole response of nuclei, supernova physics and in-medium vector meson scaling  

NASA Astrophysics Data System (ADS)

The relevance of magnetic dipole and quadrupole strength distributions for the physics of a type II supernova are discussed. A recently developed high-resolution, large solid-angle system for the detection of 180° electron scattering at the superconducting Darmstadt electron linear accelerator (S-DALINAC) is introduced which represents a unique tool for the study of low-multipolarity magnetic transitions. First results discussed include the modification of the M1 strength in complex nuclei by meson exchange currents, the overall quenching of M2 strength and possible tests of in-medium vector meson scaling (Brown-Rho scaling) by selected magnetic form factors.

Lüttge, C.; von Neumann-Cosel, P.; Neumeyer, F.; Richter, A.

1996-02-01

223

Using Rasch Modeling to Re-Evaluate Three Scales Related to Physical Activity: Enjoyment, Perceived Benefits and Perceived Barriers  

ERIC Educational Resources Information Center

|Studies suggest that enjoyment, perceived benefits and perceived barriers may be important mediators of physical activity. However, the psychometric properties of these scales have not been assessed using Rasch modeling. The purpose of this study was to use Rasch modeling to evaluate the properties of three scales commonly used in physical

Heesch, K. C.; Masse, L. C.; Dunn, A. L.

2006-01-01

224

Physical properties and multi-scale seismic anisotropy in the crust surrounding the San Andreas Fault near Parkfield, California  

Microsoft Academic Search

In this thesis I present my contribution to understanding the physical nature of the crust in and near the San Andreas Fault by studying the physical processes controlling shear velocity anisotropy at a variety of scales. To study shear velocity anisotropy at the scale of the brittle crust (˜15km), I study crustal earthquakes occurring beneath high quality three-component seismic stations

Naomi L. Boness

2006-01-01

225

Physical Habitat and Fish Assemblage Relationships with Landscape Variables at Multiple Spatial Scales in Wadeable Iowa Streams  

Microsoft Academic Search

Landscapes in Iowa and other midwestern states have been profoundly altered by conversion of native prairies to agriculture. We analyzed landscape data collected at multiple spatial scales to explore relationships with reach-scale physical habitat and fish assemblage data from 93 randomly selected sites on second- through fifth-order wadeable Iowa streams. Ordination of sites by physical habitat showed significant gradients of

David C. Rowe; Clay L. Pierce; Thomas F. Wilton

2009-01-01

226

MAPU: Max-Planck Unified database of organellar, cellular, tissue and body fluid proteomes  

Microsoft Academic Search

Mass spectrometry (MS)-based proteomics has become a powerful technology to map the protein composition of organelles, cell types and tissues. In our department, a large-scale effort to map these proteomes is complemented by the Max-Planck Unified (MAPU) proteome database. MAPU contains several body fluid proteomes; including plasma, urine, and cerebrospinal fluid. Cell lines have been mapped to a depth of

Yanling Zhang; Yong Zhang; Jun Adachi; Jesper V. Olsen; Rong Shi; Gustavo De Souza; Erica Pasini; Leonard J. Foster; Boris Macek; Alexandre Zougman; Chanchal Kumar; Jacek R. Wisniewski; Jan Wang; Matthias Mann

2007-01-01

227

Planck early results. XV. Spectral energy distributions and radio continuum spectra of northern extragalactic radio sources  

NASA Astrophysics Data System (ADS)

Spectral energy distributions (SEDs) and radio continuum spectra are presented for a northern sample of 104 extragalactic radio sources, based on the Planck Early Release Compact Source Catalogue (ERCSC) and simultaneous multifrequency data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous observations ranging from radio to gamma-rays. This is the first extensive frequency coverage in the radio and millimetre domains for an essentially complete sample of extragalactic radio sources, and it shows how the individual shocks, each in their own phase of development, shape the radio spectra as they move in the relativistic jet. The SEDs presented in this paper were fitted with second and third degree polynomials to estimate the frequencies of the synchrotron and inverse Compton (IC) peaks, and the spectral indices of low and high frequency radio data, including the Planck ERCSC data, were calculated. SED modelling methods are discussed, with an emphasis on proper, physical modelling of the synchrotron bump using multiple components. Planck ERCSC data also suggest that the original accelerated electron energy spectrum could be much harder than commonly thought, with power-law indexaround 1.5 instead of the canonical 2.5. The implications of this are discussed for the acceleration mechanisms effective in blazar shocks. Furthermore in many cases the Planck data indicate that gamma-ray emission must originate in the same shocks that produce the radio emission. Tables 1 and 4, Figs. 18-121 are available in electronic form at http://www.aanda.org

Planck Collaboration; Aatrokoski, J.; Ade, P. A. R.; Aghanim, N.; Aller, H. D.; Aller, M. F.; Angelakis, E.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoît, A.; Berdyugin, A.; Bernard, J.-P.; Bersanelli, M.; Bhatia, R.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Bucher, M.; Burigana, C.; Burrows, D. N.; Cabella, P.; Capalbi, M.; Cappellini, B.; Cardoso, J.-F.; Catalano, A.; Cavazzuti, E.; Cayón, L.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chiang, L.-Y.; Christensen, P. R.; Clements, D. L.; Colafrancesco, S.; Colombi, S.; Couchot, F.; Coulais, A.; Cutini, S.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Gasperis, G.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Dickinson, C.; Dole, H.; Donzelli, S.; Doré, O.; Dörl, U.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Fuhrmann, L.; Galeotta, S.; Ganga, K.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Giard, M.; Giardino, G.; Giglietto, N.; Giommi, P.; Giordano, F.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Harrison, D.; Henrot-Versillé, S.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hovest, W.; Hoyland, R. J.; Huffenberger, K. M.; Jaffe, A. H.; Juvela, M.; Keihänen, E.; Keskitalo, R.; King, O.; Kisner, T. S.; Kneissl, R.; Knox, L.; Krichbaum, T. P.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Laureijs, R. J.; Lavonen, N.; Lawrence, C. R.; Leach, S.; Leonardi, R.; León-Tavares, J.; Linden-Vørnle, M.; Lindfors, E.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Mann, R.; Maris, M.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Matthai, F.; Max-Moerbeck, W.; Mazziotta, M. N.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Michelson, P. F.; Mingaliev, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Monte, C.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, A.; Naselsky, P.; Natoli, P.; Nestoras, I.; Netterfield, C. B.; Nieppola, E.; Nilsson, K.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; O'Dwyer, I. J.; Osborne, S.; Pajot, F.; Partridge, B.; Pasian, F.; Patanchon, G.; Pavlidou, V.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Perri, M.; Perrotta, F.; Piacentini, F.; Piat, M.; Plaszczynski, S.; Platania, P.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Poutanen, T.; Prézeau, G.; Procopio, P.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Rainò, S.; Reach, W. T.; Readhead, A.; Rebolo, R.; Reeves, R.; Reinecke, M.; Reinthal, R.; Renault, C.; Ricciardi, S.; Richards, J.; Riller, T.; Riquelme, D.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Saarinen, J.; Sandri, M.; Savolainen, P.; Scott, D.; Seiffert, M. D.; Sievers, A.; Sillanpää, A.; Smoot, G. F.; Sotnikova, Y.; Starck, J.-L.; Stevenson, M.; Stivoli, F.; Stolyarov, V.; Sudiwala, R.; Sygnet, J.-F.; Takalo, L.; Tammi, J.; Tauber, J. A.; Terenzi, L.; Thompson, D. J.; Toffolatti, L.; Tomasi, M.; Tornikoski, M.; Torre, J.-P.; Tosti, G.; Tramacere, A.; Tristram, M.; Tuovinen, J.; Türler, M.; Turunen, M.; Umana, G.; Ungerechts, H.; Valenziano, L.; Valtaoja, E.; Varis, J.; Verrecchia, F.; Vielva, P.; Villa, F.; Vittorio, N.; Wandelt, B. D.; Wu, J.; Yvon, D.; Zacchei, A.; Zensus, J. A.; Zhou, X.; Zonca, A.

2011-12-01

228

Testing modified gravity with Planck: The case of coupled dark energy  

NASA Astrophysics Data System (ADS)

The Planck collaboration has recently published maps of the cosmic microwave background (CMB) radiation, in good agreement with a ?CDM model, a fit especially valid for multipoles ?>40. We explore here the possibility that dark energy is dynamical and gravitational attraction between dark matter particles is effectively different from the standard one in general relativity: this is the case of coupled dark energy models, where dark matter particles feel the presence of a fifth force, larger than gravity by a factor 2?2, defining an effective gravitational constant Geff=G(1+2?2). We investigate constraints on the strength of the coupling ? in view of Planck data. Interestingly, we show that a nonzero coupling is compatible with data and find a likelihood peak at ?=0.036±0.016 [Planck+WMAPpolarization(WP)+baryonicacousticoscillations(BAO)] (compatible with zero at 2.2?). The significance of the peak increases to ?=0.066±0.018 [Planck+WP+HubbleSpaceTelescope(HST)] (around 3.6? from zero coupling) when Planck is combined to HST data by . This peak comes mostly from the small difference between the Hubble parameter determined with CMB measurements and the one coming from astrophysics measurements and is already present in the combination with BAO. Future observations and further tests of current observations are needed to determine whether the discrepancy is due to systematics in any of the data sets. Our aim here is not to claim new physics but rather to show that a clear understanding of such tension has a considerable impact on dark energy models: it can be used to provide information on dynamical dark energy and modified gravity, allowing us to test the strength of an effective fifth force.

Pettorino, Valeria

2013-09-01

229

The development of a physical education state anxiety scale: a preliminary study.  

PubMed

The aim of the present study was to develop a measure of state anxiety for school physical education. The Physical Education State Anxiety Scale was designed to assess the basic anxiety dimensions plus the related cognitive processes. High school students (n = 631) completed the scale just prior to a test on two track and field tasks, in order to create a stressful condition. Data from the sample were randoml y split in two and subjected to exploratory and confirmatory factor analyses, which supported the proposed three-factor structure of Worry, Cognitive Processes, and Somatic Anxiety. Internal consistency coefficients were acceptable. Moderate correlations among the subscale scores supported its construct validity. Results provide preliminary evidence for validity and reliability. PMID:15773702

Barkoukis, Vassilis; Tsorbatzoudis, Haralambos; Grouios, George; Rodafinos, Aggelos

2005-02-01

230

PREDICTING WILDLAND FIRE BEHAVIOR AND EMISSIONS USING A FINE-SCALE PHYSICAL MODEL  

Microsoft Academic Search

A physical fine-scale two-phase model has been developed for the purpose of determining wildland fire behavior and emissions. The situation modeled corresponds to a spreading wildfire driven by wind through a fuel bed of combustible elements. The numerical model solves a set of time-dependent conservation Equations for both phases (the gas and the vegetation elements) coupled through exchange terms. It

B. Porterie; J. L. Consalvi; A. Kaiss; J. C. Loraud

2005-01-01

231

Mitigation of scaling in heat exchangers by physical water treatment using zinc and tourmaline  

Microsoft Academic Search

This paper presents a study on the mitigation of calcium carbonate scaling in a double-pipe heat exchanger by physical water treatment (PWT) using zinc and tourmaline as catalytic materials. Artificially-hardened water at 300 mgL?1 was utilized as the fluid medium to form fouling deposits. The cooling water (i.e., hard water) velocity was varied from 0.3 to 0.8 ms?1. The inlet temperatures were

Leonard D. Tijing; Mi-Hwa Yu; Chae-Hwa Kim; Altangerel Amarjargal; Young Chan Lee; Dong-Hwan Lee; Dong-Won Kim; Cheol Sang Kim

2011-01-01

232

Development of a physically based runoff routing model and its application at regional scale  

NASA Astrophysics Data System (ADS)

Adequate description of surface water transport is of critical importance for a land surface model to provide spatiotemporal distribution of available water resource, which is a key driver of sustainable management under current and future climate. Most existing runoff transport models are limited to applications over a certain range of scales. For instance, highly distributed runoff routing models require detailed information which is usually not globally available. Most global routing models oversimplify important physical processes limiting their accuracy at small scales. We aim to develop a physically based runoff routing model which is applicable across local, regional and global scales. Within each spatial unit, runoff is first routed as overland flow routing across hillslopes, then through a "tributary sub-network" before discharging into the main channel. The spatial units are then linked via routing through the main channel network. All model parameters are physically-based except two which are obtained through calibration.. We applied this model to the Columbia River Basin, USA at 1/16th, 1/8th, 1/4th, 1/2nd and 1 degree resolutions. The model results were validated against naturalized streamflow at 15 major gauge stations, and compared with two other widely used routing models, the River Transport Model (RTM) contained in the Community Land Model (CLM) and the Variable Infiltration Capability (VIC) routing model. The performance of this routing framework is shown to be superior to the RTM, and comparable with the VIC routing model.

Li, H.; Wigmosta, M. S.; Wu, H.; Huang, M.; Ke, Y.; Coleman, A.; Leung, L.

2011-12-01

233

Bayesian Inference Based on Stationary Fokker-Planck Sampling  

Microsoft Academic Search

A novel formalism for Bayesian learning in the context of complex inference models is proposed. The method is based on the use of the stationary Fokker-Planck (SFP) approach to sample from the posterior density. Stationary Fokker-Planck sampling generalizes the Gibbs sampler algorithm for arbitrary and unknown conditional densities. By the SFP procedure, approximate analytical expressions for the conditionals and marginals

Arturo Berrones

2010-01-01

234

A Validation and Reliability Study of the Physical Activity and Healthy Food Efficacy Scale for Children (PAHFE)  

ERIC Educational Resources Information Center

|The purpose of this study was to obtain validity evidence for the Physical Activity and Healthy Food Efficacy Scale for Children (PAHFE). Construct validity evidence identifies four subscales: Goal-Setting for Physical Activity, Goal-Setting for Healthy Food Choices, Decision-Making for Physical Activity, and Decision-Making for Healthy Food…

Perry, Christina M.; De Ayala, R. J.; Lebow, Ryan; Hayden, Emily

2008-01-01

235

A Validation and Reliability Study of the Physical Activity and Healthy Food Efficacy Scale for Children (PAHFE)  

ERIC Educational Resources Information Center

The purpose of this study was to obtain validity evidence for the Physical Activity and Healthy Food Efficacy Scale for Children (PAHFE). Construct validity evidence identifies four subscales: Goal-Setting for Physical Activity, Goal-Setting for Healthy Food Choices, Decision-Making for Physical Activity, and Decision-Making for Healthy Food…

Perry, Christina M.; De Ayala, R. J.; Lebow, Ryan; Hayden, Emily

2008-01-01

236

Physical properties of a two-component system at the Fermi and Sharvin length scales  

NASA Astrophysics Data System (ADS)

Previously, we have reported the measurement of various physical properties at the Fermi and Sharvin length scales in pure elements (1-component systems). In the present study, the evolution of physical properties is mapped in a 2-component system at these length scales, using Au-Ag alloys. These alloys are well known to have complete solubility in each other at all compositions in the bulk and an ideal system to vary the surface energy of the alloy simply by changing the alloy composition. At sample sizes where surface effects dominate (less than ~2-3 nm), varying the alloy composition is found to cause dramatic changes in force required to rupture the bonds (strength) as well as atomic cohesion (modulus) and can be directly attributed to segregation of higher surface energy Au from the lower surface energy Ag. In other words, the Au-Ag system with complete solubility in the bulk exhibits segregation at these length scales. This breakdown of bulk solubility rules for alloying (the so-called Hume-Rothery rules) even in near-ideal solid solutions has consequences for future atomic-scale devices.

Armstrong, Jason N.; Gande, Eric M.; Vinti, John W.; Hua, Susan Z.; Deep Chopra, Harsh

2012-11-01

237

Crocodile head scales are not developmental units but emerge from physical cracking.  

PubMed

Various lineages of amniotes display keratinized skin appendages (feathers, hairs, and scales) that differentiate in the embryo from genetically controlled developmental units whose spatial organization is patterned by reaction-diffusion mechanisms (RDMs). We show that, contrary to skin appendages in other amniotes (as well as body scales in crocodiles), face and jaws scales of crocodiles are random polygonal domains of highly keratinized skin, rather than genetically controlled elements, and emerge from a physical self-organizing stochastic process distinct from RDMs: cracking of the developing skin in a stress field. We suggest that the rapid growth of the crocodile embryonic facial and jaw skeleton, combined with the development of a very keratinized skin, generates the mechanical stress that causes cracking. PMID:23196908

Milinkovitch, Michel C; Manukyan, Liana; Debry, Adrien; Di-Poï, Nicolas; Martin, Samuel; Singh, Daljit; Lambert, Dominique; Zwicker, Matthias

2012-11-29

238

Max Planck Institute for Chemical Ecology  

NSDL National Science Digital Library

The Max Planck Institute for Chemical Ecology is based in Germany and their work encompasses a wide range of inquiry into the relationships between everything from bugs and symbiotic bacteria to odor activation in drosophila. Visitors can wander through the News area to get a sense of the ongoing research projects and overall mission. In the Institute area visitors can learn the basics of chemical ecology, the management of the Institute and their cooperative agreements with other like-minded organizations. The Departments area contains information about separate research groups, which are focused on entomology, bioorganic chemistry, biochemistry, and molecular ecology. Scientists and others will want to look over the Publications area, as it contains hundreds of research papers which can be searched by department, year, or citation number. Finally, visitors can also search available job openings.

239

Planck & Herschel unveil extreme submillimeter structures  

NASA Astrophysics Data System (ADS)

Planck is the first FIR/sub-mm all sky survey with the sensitivity required to systematically identify the rarest, most luminous high-redshift sub-mm sources on the sky, either strongly gravitationally lensed galaxies, or the joint FIR/sub-mm emission from multiple intense starbursts as expected for the most massive, most rapidly collapsing dark-matter environments in the early Universe. We use a color selection to identify a population of 500 bright, high-fidelity Planck high-z candidates, 180 of which we are now following up with Herschel/SPIRE, including an extraordinary allocation of ``Must Do'' Director's Discretionary Time. All of our sources have typical SPIRE colors of high-z galaxies, and the redshifts of several have already been confirmed spectroscopically. We will use Spitzer/IRAC to identify and analyze the stellar counterparts of 35 of these sources, aided (but not replaced) by existing and scheduled ground-based optical/NIR photometry. This will allow us to measure photometric redshifts, stellar masses, star formation histories and stellar ages of these sources. We will search for candidate member galaxies of nascent galaxy clusters, and prepare detailed spectroscopic follow-up. At what cosmic epoch did massive galaxy clusters form most of their stars? Will we find that star formation is more or less vigorous in these galaxies compared to galaxies in the field? Is the upper end of the ``red sequence'' already in place? These are only some of the questions that IRAC will help us address.

Dole, Herve; Chary, Ranga-Ram; Montier, Ludovic; Lagache, Guilaine; Beelen, Alexandre; Welikala, Niraj; Puget, Jean-Loup; Giard, Martin; Pointecouteau, Etienne; Omont, Alain; Guery, David; Nesvabda, Nicole; Chary, Ranga; Scott, Douglas; Le Floc'h, Emeric; Frye, Brenda; Soucail, Genevieve

2012-12-01

240

Planck's High Temperature Catastrophe in Observational Astronomy:- (NASA proves Planck wrong)  

NASA Astrophysics Data System (ADS)

Planck's black body radiation law ( IP=c1 ?^51e^c2?T -1) predicts that a hotter body (higher T) should always emit more intensely than a colder body (lower T) throughout the entire EMR spectrum. However, space age infrared astronomy contradicts this prediction! It is now known that as observation moves from the visible to the near-, mid- and far infrared; increasingly cold celestial objects come into view while hotter ones fade and disappear (http://coolcosmos.ipac.caltech.edu/cosmicclassroom/irtutori al/irregions.html). Were Planck's law valid, the hottest stars would never disappear; and colder objects would not be detected. This can only be described as a high temperature catastrophe (BAPS, April Meeting 2008, H12.3, St Louis, MO) for Planck's law! On the other hand, Gall's black body radiation law ( IG=?T^6b^2?e^-?Tb) (http://sites.google.com/site/purefieldphysics) predicts that as wavelength increases, there is a crossover point above which a colder object will emit more intensely than a hotter one. Hence colder objects will appear and hotter ones will eventually disappear from view. The crossover point for black bodies at 6000K and 100K is 12.066 microns. These calculations with Gall's law are in overall agreement with observational infrared astronomy.

Gall, Clarence A.

2009-03-01

241

Bayesian physical reconstruction of initial conditions from large-scale structure surveys  

NASA Astrophysics Data System (ADS)

We present a fully probabilistic, physical model of the non-linearly evolved density field, as probed by realistic galaxy surveys. Our model is valid in the linear and mildly non-linear regimes and uses second-order Lagrangian perturbation theory to connect the initial conditions with the final density field. Our parameter space consists of the 3D initial density field and our method allows a fully Bayesian exploration of the sets of initial conditions that are consistent with the galaxy distribution sampling the final density field. A natural by-product of this technique is an optimal non-linear reconstruction of the present density and velocity fields, including a full propagation of the observational uncertainties. A test of these methods on simulated data mimicking the survey mask, selection function and galaxy number of the Sloan Digital Sky Survey Data Release 7 main sample shows that this physical model gives accurate reconstructions of the underlying present-day density and velocity fields on scales larger than ˜6 Mpc h-1. Our method naturally and accurately reconstructs non-linear features corresponding to three-point and higher order correlation functions such as walls and filaments. Simple tests of the reconstructed initial conditions show statistical consistency with the Gaussian simulation inputs. Our test demonstrates that statistical approaches based on physical models of the large-scale structure distribution are now becoming feasible for realistic current and future surveys.

Jasche, Jens; Wandelt, Benjamin D.

2013-06-01

242

The Disablement in the Physically Active Scale, Part II: The Psychometric Properties of an Outcomes Scale for Musculoskeletal Injuries  

PubMed Central

Abstract Context: Outcomes assessment is an integral part of ensuring quality in athletic training, but few generic instruments have been specifically designed to measure disablement in the physically active. Objective: To assess the psychometric properties of the Disablement in the Physically Active Scale (DPA), a patient-report, generic outcomes instrument. Design: Observational study. Setting: We collected data in 5 settings with competitive and recreational athletes. Participants entered into the study at 3 distinct points: (1) when healthy and (2) after an acute injury, or (3) after a persistent injury. Patients or Other Participants: Measures were obtained from 368 baseline participants (202 females, 166 males; age ?=? 20.1 ± 3.8 years), 54 persistent participants (32 females, 22 males; age ?=? 22.0 ± 8.3 years), and 28 acutely injured participants (8 females, 20 males; age ?=? 19.8 ± 1.90 years). Main Outcome Measure(s): We assessed internal consistency with a Cronbach ? and test-retest reliability with intraclass correlation (2,1) values. The scale's factor structure was assessed with a hierarchical confirmatory factor analysis. Concurrent validity was assessed with a Pearson correlation. Responsiveness was calculated using a receiver operating characteristic curve and a minimal clinically important difference value. Results: The Cronbach ? scores for the DPA were 0.908 and 0.890 in acute and persistent groups, respectively. The intraclass correlation (2,1) value of the DPA was 0.943 (95% confidence interval ?=? 0.885, 0.972). The fit indices values were 1.89, 0.852, 0.924, 0.937, and 0.085 (90% confidence interval ?=? 0.066, 0.103) for the minimum sample discrepancy divided by degrees of freedom, goodness-of-fit index, Tucker-Lewis Index, comparative fit index, and root mean square error of approximation, respectively. The DPA scores accounted for 51% to 56.4% of the variation in global functioning scores. The area under the curve was statistically significant, and the minimally clinically important difference values were established. Conclusions: The DPA is a reliable, valid, and responsive instrument.

Vela, Luzita I.; Denegar, Craig R.

2010-01-01

243

Particle Physics on Ice: Constraints on Neutrino Interactions Far above the Weak Scale  

SciTech Connect

Ultrahigh energy cosmic rays and neutrinos probe energies far above the weak scale. Their usefulness might appear to be limited by astrophysical uncertainties; however, by simultaneously considering up- and down-going events, one may disentangle particle physics from astrophysics. We show that present data from the AMANDA experiment in the South Pole ice already imply an upper bound on neutrino cross sections at energy scales that will likely never be probed at man-made accelerators. The existing data also place an upper limit on the neutrino flux valid for any neutrino cross section. In the future, similar analyses of IceCube data will constrain neutrino properties and fluxes at the O(10%) level.

Anchordoqui, Luis A.; Goldberg, Haim [Department of Physics, Northeastern University, Boston, Massachusetts 02115 (United States); Feng, Jonathan L. [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)

2006-01-20

244

Connecting LHC signals with deep physics at the TeV scale and baryogenesis  

NASA Astrophysics Data System (ADS)

We address in this dissertation two primary questions aimed at deciphering collider signals at the Large Hadron Collider (LHC) to give a deep and concrete understanding of the TeV scale physics and to interpret the origin of baryon asymmetry in our universe. We are at a stage of exploring new physics at the terascale which is responsible for the electroweak symmetry breaking (EWSB) in the Standard Model (SM) of particle physics. The LHC, which begins its operation this year, will break us into such a new energy frontier and seek for the possible signals of new physics. Theorists have come up with many possible models beyond SM to explain the origin of EWSB. However, how we will determine the underlying physics from LHC data is still an open question. In the first part of this dissertation, we consider several examples to connect the expected LHC signals to the underlying physics in a completely model independent way. We first explore the Randall-Sundrum (RS) scenario, and use the collider signals of first Kaluza-Klein (KK) excitations of gluons to discriminate several commonly considered theories which attempt to render RS consistent with precision electroweak data. We then investigate top compositeness. We derive a bound for the energy scale of right handed top compositeness from top pair production at the Tevatron, and we find that the cross section to produce four tops will be greatly amplified by 3 orders of magnitude. We next consider the possibilities that the gauge symmetry in the underlying theory is violated in the incomplete theory that we can reconstruct from the LHC observables. We derive a model independent bound on the scale of new physics from unitarity of the S-matrix if we observe a new massive vector boson with nonzero axial couplings to fermions at LHC. Finally, we derive a generalized Landau-Yang theorem and apply it to the Z' decay into two Z bosons. We show that there is a phase shift in the azimuthal angle distribution in the normalized differential cross section and the anomalous coupling of Z'-Z-Z can be discriminated from the regular one at the 3s level when both Z bosons decay leptonically at the LHC. The origin of baryon asymmetry of the Universe (BAU) remains an important, unsolved problem for particle physics and cosmology, and is one of the motivations to search for possible new physics beyond SM. In the second part of this dissertation, we attempt to account for the baryon number generation in our universe through some novel mechanisms. We first systematically investigate models of baryogenesis from spontaneously Lorentz violating background (SLVB). We find that the sphaleron transitions will generate a nonzero B+L asymmetry in the presence of SLVB and we identify two scenarios of interest. We then consider the possibilities to generate a baryon asymmetry through an earlier time phase transition and address the question whether or not we can still test the baryogenesis mechanism at LHC/ILC if the electroweak phase transition is not strongly first order. We find a general framework and realize this idea in the top flavor model. We show that the realistic baryon density can be achieved in the natural parameter space of topflavor model.

Shu, Jing

245

Description of a Turbulent Cascade by a Fokker-Planck Equation  

Microsoft Academic Search

From experimental data of a turbulent free jet we calculate the joint probability distribution p\\\\(v1,L1;v2,L2\\\\) for two velocity increments v1,v2 of different length scales L1,L2. We present experimental evidence that the conditional probability distribution p\\\\(v2,L2 \\\\| v1,L1\\\\) obeys a Fokker-Planck equation. We calculate the corresponding drift and diffusion coefficients and discuss their relationship to universal behavior in the scaling region

R. Friedrich; J. Peinke

1997-01-01

246

Instrument development and validation of Perceived Physical Activity Self-Efficacy Scale for adolescents.  

PubMed

Thorough evaluation and systematic instrumentation about self-efficacy related to physical activity (PA) in adolescents is necessary to determine efficacy and effectiveness of intervention on PA behavior. The purpose of this report was to investigate the psychometric properties of a perceived self-efficacy scale for PA. In the observational cross-sectional cohort design, an 11-item Perceived Physical Activity Self-Efficacy Scale was evaluated in a sample of 206 racially diverse adolescents at a Midwestern U.S. public middle school. Participants: The convenience sample included 105 boys and 101 girls from sixth to eighth grade: 47.1% of the participants were European American, 19.4% were African American, and 18% were "other" races and "multi-racial." The University Institutional Review Board provided approval for conducting the study. The same instruments were delivered to participants on two separate occasions, 2 weeks apart. The results from this study revealed satisfactory internal consistency with Cronbach's alpha coefficient of .86, and test-retest reliability of .61. Confirmatory factor analysis (CFA) showed a one-factor structure with modest fit. However, the self-efficacy was not related to PA and known-group technique was not supported. The study measure demonstrated satisfactory reliability and construct validity through CFA. PMID:21469540

Wu, Tsu-Yin; Robbins, Lorraine B; Hsieh, Hsing-Fang

2011-01-01

247

New multigroup Monte Carlo scattering algorithm suitable for neutral- and charged-particle Boltzmann and Fokker-Planck calculations  

SciTech Connect

Morel (1981) has developed multigroup Legendre cross sections suitable for input to standard discrete ordinates transport codes for performing charged-particle Fokker-Planck calculations in one-dimensional slab and spherical geometries. Since the Monte Carlo neutron transport code, MORSE, uses the same multigroup cross section data that discrete ordinates codes use, it was natural to consider whether Fokker-Planck calculations could be performed with MORSE. In order to extend the unique three-dimensional forward or adjoint capability of MORSE to Fokker-Planck calculations, the MORSE code was modified to correctly treat the delta-function scattering of the energy operator, and a new set of physically acceptable cross sections was derived to model the angular operator. Morel (1979) has also developed multigroup Legendre cross sections suitable for input to standard discrete ordinates codes for performing electron Boltzmann calculations. These electron cross sections may be treated in MORSE with the same methods developed to treat the Fokker-Planck cross sections. The large magnitude of the elastic scattering cross section, however, severely increases the computation or run time. It is well-known that approximate elastic cross sections are easily obtained by applying the extended transport (or delta function) correction to the Legendre coefficients of the exact cross section. An exact method for performing the extended transport cross section correction produces cross sections which are physically acceptable. Sample calculations using electron cross sections have demonstrated this new technique to be very effective in decreasing the large magnitude of the cross sections.

Sloan, D.P.

1983-05-01

248

Modified dispersion relations and black hole physics  

SciTech Connect

A modified formulation of the energy-momentum relation is proposed in the context of doubly special relativity. We investigate its impact on black hole physics. It turns out that such a modification will give corrections to both the temperature and the entropy of black holes. In particular, this modified dispersion relation also changes the picture of Hawking radiation greatly when the size of black holes approaches the Planck scale. It can prevent black holes from total evaporation, as a result providing a plausible mechanism to treat the remnant of black holes as a candidate for dark matter.

Ling Yi; Li Xiang [Center for Gravity and Relativity, Department of Physics, Nanchang University, 330047 (China); CCAST (World Laboratory), P.O. Box 8730, Beijing 100080 (China); Hu Bo [Center for Gravity and Relativity, Department of Physics, Nanchang University, 330047 (China)

2006-04-15

249

Determining Planck's Constant Using a Light-emitting Diode.  

ERIC Educational Resources Information Center

|Describes a method for making a simple, inexpensive apparatus which can be used to determine Planck's constant. Provides illustrations of a circuit diagram using one or more light-emitting diodes and a BASIC computer program for simplifying calculations. (RT)|

Sievers, Dennis; Wilson, Alan

1989-01-01

250

Update on minimal supersymmetric hybrid inflation in light of PLANCK  

NASA Astrophysics Data System (ADS)

The minimal supersymmetric (or F-term) hybrid inflation is defined by a unique renormalizable superpotential, fixed by a U(1) R-symmetry, and it employs a canonical Kähler potential. The inflationary potential takes into account both radiative and supergravity corrections, as well as an important soft supersymmetry breaking term, with a mass coefficient in the range (0.1-10) TeV. The latter term assists in obtaining a scalar spectral index ns close to 0.96, as strongly suggested by the PLANCK and WMAP 9 yr measurements. The minimal model predicts that the tensor-to-scalar r is extremely tiny, of order 10-12, while the spectral index running, |dns/dlnk|˜10-4. If inflation is associated with the breaking of a local U(1 symmetry, the corresponding symmetry breaking scale M is (0.7-1.6)?1015 GeV with ns?0.96. This scenario is compatible with the bounds on M from cosmic strings, formed at the end of inflation from B-L symmetry breaking. We briefly discuss non-thermal leptogenesis which is readily implemented in this class of models.

Pallis, Constantinos; Shafi, Qaisar

2013-10-01

251

The Development of a Student's Behaviors' Self-Evaluation Scale (SBSS) in Multicultural Physical Education Class Settings  

ERIC Educational Resources Information Center

The purpose of this study is to develop and validate the structural validity and reliability of a student's behaviors' self-evaluation scale (SBSS) in the physical education class. The SBSS was created in order to evaluate the effect of a physical education program in the context of the multicultural composition of the student population in the…

Kellis I.; Vernadakis N.; Albanidis E.; Derri V.; Kourtesses T.

2010-01-01

252

The Development of a Student's Behaviors' Self-Evaluation Scale (SBSS) in Multicultural Physical Education Class Settings  

ERIC Educational Resources Information Center

|The purpose of this study is to develop and validate the structural validity and reliability of a student's behaviors' self-evaluation scale (SBSS) in the physical education class. The SBSS was created in order to evaluate the effect of a physical education program in the context of the multicultural composition of the student population in the…

Kellis I.; Vernadakis N.; Albanidis E.; Derri V.; Kourtesses T.

2010-01-01

253

Poisson-Nernst-Planck equations for simulating biomolecular diffusion-reaction processes I: Finite element solutions  

SciTech Connect

In this paper we developed accurate finite element methods for solving 3-D Poisson-Nernst-Planck (PNP) equations with singular permanent charges for simulating electrodiffusion in solvated biomolecular systems. The electrostatic Poisson equation was defined in the biomolecules and in the solvent, while the Nernst-Planck equation was defined only in the solvent. We applied a stable regularization scheme to remove the singular component of the electrostatic potential induced by the permanent charges inside biomolecules, and formulated regular, well-posed PNP equations. An inexact-Newton method was used to solve the coupled nonlinear elliptic equations for the steady problems; while an Adams-Bashforth-Crank-Nicolson method was devised for time integration for the unsteady electrodiffusion. We numerically investigated the conditioning of the stiffness matrices for the finite element approximations of the two formulations of the Nernst-Planck equation, and theoretically proved that the transformed formulation is always associated with an ill-conditioned stiffness matrix. We also studied the electroneutrality of the solution and its relation with the boundary conditions on the molecular surface, and concluded that a large net charge concentration is always present near the molecular surface due to the presence of multiple species of charged particles in the solution. The numerical methods are shown to be accurate and stable by various test problems, and are applicable to real large-scale biophysical electrodiffusion problems.

Lu Benzhuo [State Key Laboratory of Scientific and Engineering Computing, Institute of Computational Mathematics and Scientific/Engineering Computing, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190 (China); Holst, Michael J. [Department of Mathematics, University of California San Diego, La Jolla, CA 92093 (United States); Center for Theoretical Biological Physics, University of California San Diego, La Jolla, CA 92093 (United States); Andrew McCammon, J. [Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093 (United States); Center for Theoretical Biological Physics, University of California San Diego, La Jolla, CA 92093 (United States); Department of Pharmacology, University of California San Diego, La Jolla, CA 92093 (United States); Zhou, Y.C., E-mail: yzhou@math.colostate.ed [Department of Mathematics, Colorado State University, Fort Collins, CO 80523 (United States)

2010-09-20

254

Poisson-Nernst-Planck Equations for Simulating Biomolecular Diffusion-Reaction Processes I: Finite Element Solutions  

PubMed Central

In this paper we developed accurate finite element methods for solving 3-D Poisson-Nernst-Planck (PNP) equations with singular permanent charges for electrodiffusion in solvated biomolecular systems. The electrostatic Poisson equation was defined in the biomolecules and in the solvent, while the Nernst-Planck equation was defined only in the solvent. We applied a stable regularization scheme to remove the singular component of the electrostatic potential induced by the permanent charges inside biomolecules, and formulated regular, well-posed PNP equations. An inexact-Newton method was used to solve the coupled nonlinear elliptic equations for the steady problems; while an Adams-Bashforth-Crank-Nicolson method was devised for time integration for the unsteady electrodiffusion. We numerically investigated the conditioning of the stiffness matrices for the finite element approximations of the two formulations of the Nernst-Planck equation, and theoretically proved that the transformed formulation is always associated with an ill-conditioned stiffness matrix. We also studied the electroneutrality of the solution and its relation with the boundary conditions on the molecular surface, and concluded that a large net charge concentration is always present near the molecular surface due to the presence of multiple species of charged particles in the solution. The numerical methods are shown to be accurate and stable by various test problems, and are applicable to real large-scale biophysical electrodiffusion problems.

Lu, Benzhuo; Holst, Michael J.; McCammon, J. Andrew; Zhou, Y. C.

2010-01-01

255

Max Planck Institute for Plant Breeding Research  

NSDL National Science Digital Library

The Max Planck Institute for Plant Breeding Research is committed to a number of research goals, one of which is "to determine whether and how a detailed understanding of molecular mechanisms defined in model plant species can be used to rationally manipulate selected traits in crop plants." The Institute was founded in 1928 as part of the Kaiser-Willhelm-Gesellschaft and the first director, Edwin Baur, was interested in creating breeding programs with fruits and berries, though the Institute's scope has expanded since then. Visitors to the homepage should start by clicking on the News section. Here they can peruse recent releases from the Institute on how plants use mobile proteins to defend themselves against bacteria and the evolutionary "dead end" of powdery mildew. Scholars and others will want to click on the Reports and Publications area to look at some recent scholarly works and annual reports from 2009, 2006, and 2003. Moving on, the Public Outreach area contains a nice photo gallery and additional publications.

2012-04-06

256

Physical descriptions of the bacterial nucleoid at large scales, and their biological implications  

NASA Astrophysics Data System (ADS)

Recent experimental and theoretical approaches have attempted to quantify the physical organization (compaction and geometry) of the bacterial chromosome with its complement of proteins (the nucleoid). The genomic DNA exists in a complex and dynamic protein-rich state, which is highly organized at various length scales. This has implications for modulating (when not directly enabling) the core biological processes of replication, transcription and segregation. We overview the progress in this area, driven in the last few years by new scientific ideas and new interdisciplinary experimental techniques, ranging from high space- and time-resolution microscopy to high-throughput genomics employing sequencing to map different aspects of the nucleoid-related interactome. The aim of this review is to present the wide spectrum of experimental and theoretical findings coherently, from a physics viewpoint. In particular, we highlight the role that statistical and soft condensed matter physics play in describing this system of fundamental biological importance, specifically reviewing classic and more modern tools from the theory of polymers. We also discuss some attempts toward unifying interpretations of the current results, pointing to possible directions for future investigation.

Benza, Vincenzo G.; Bassetti, Bruno; Dorfman, Kevin D.; Scolari, Vittore F.; Bromek, Krystyna; Cicuta, Pietro; Cosentino Lagomarsino, Marco

2012-07-01

257

PROSPECTS FOR COLLIDERS AND COLLIDER PHYSICS TO THE 1 PEV ENERGY SCALE  

SciTech Connect

A review is given of the prospects for future colliders and collider physics at the energy frontier. A proof-of-plausibility scenario is presented for maximizing the authors progress in elementary particle physics by extending the energy reach of hadron and lepton colliders as quickly and economically as might be technically and financially feasible. The scenario comprises 5 colliders beyond the LHC--one each of e{sup +}e{sup {minus}} and hadron colliders and three {mu}{sup +}{mu}{sup {minus}} colliders--and is able to hold to the historical rate of progress in the log-energy reach of hadron and lepton colliders, reaching the 1 PeV constituent mass scale by the early 2040's. The technical and fiscal requirements for the feasibility of the scenario are assessed and relevant long-term R and D projects are identified. Considerations of both cost and logistics seem to strongly favor housing most or all of the colliders in the scenario in a new world high energy physics laboratory.

KING,B.J.

2000-05-05

258

Planck early results. XIV. ERCSC validation and extreme radio sources  

Microsoft Academic Search

Planck's all-sky surveys at 30-857 GHz provide an unprecedented opportunity to follow the radio spectra of a large sample of extragalactic sources to frequencies 2-20 times higher than allowed by past, large-area, ground-based surveys. We combine the results of the Planck Early Release Compact Source Catalog (ERCSC) with quasi-simultaneous ground-based observations as well as archival data at frequencies below or

P. A. R. Ade; N. Aghanim; E. Angelakis; M. Arnaud; M. Ashdown; J. Aumont; C. Baccigalupi; A. Balbi; A. J. Banday; R. B. Barreiro; J. G. Bartlett; E. Battaner; K. Benabed; A. Benoît; J.-P. Bernard; M. Bersanelli; R. Bhatia; A. Bonaldi; L. Bonavera; J. R. Bond; J. Borrill; M. Bucher; C. Burigana; P. Cabella; B. Cappellini; J.-F. Cardoso; A. Catalano; L. Cayón; A. Challinor; A. Chamballu; R.-R. Chary; X. Chen; L.-Y. Chiang; P. R. Christensen; D. L. Clements; S. Colombi; F. Couchot; A. Coulais; B. P. Crill; F. Cuttaia; L. Danese; R. D. Davies; R. J. Davis; P. de Bernardis; G. de Gasperis; A. de Rosa; G. de Zotti; J. Delabrouille; J.-M. Delouis; F.-X. Désert; C. Dickinson; S. Donzelli; O. Doré; U. Dörl; M. Douspis; X. Dupac; G. Efstathiou; T. A. Enßlin; F. Finelli; O. Forni; M. Frailis; E. Franceschi; L. Fuhrmann; S. Galeotta; K. Ganga; M. Giard; G. Giardino; Y. Giraud-Héraud; J. González-Nuevo; K. M. Górski; S. Gratton; A. Gregorio; A. Gruppuso; D. Harrison; S. Henrot-Versillé; D. Herranz; S. R. Hildebrandt; E. Hivon; M. Hobson; W. A. Holmes; W. Hovest; R. J. Hoyland; K. M. Huffenberger; M. Huynh; A. H. Jaffe; M. Juvela; E. Keihänen; R. Keskitalo; T. S. Kisner; R. Kneissl; L. Knox; T. P. Krichbaum; H. Kurki-Suonio; G. Lagache; A. Lähteenmäki; J.-M. Lamarre; A. Lasenby; R. J. Laureijs; N. Lavonen; C. R. Lawrence; S. Leach; J. P. Leahy; R. Leonardi; J. León-Tavares; M. Linden-Vørnle; M. López-Caniego; P. M. Lubin; J. F. Macías-Pérez; B. Maffei; D. Maino; N. Mandolesi; R. Mann; M. Maris; F. Marleau; E. Martínez-González; S. Masi; M. Massardi; S. Matarrese; F. Matthai; A. Melchiorri; L. Mendes; A. Mennella; M.-A. Miville-Deschênes; A. Moneti; L. Montier; G. Morgante; D. Mortlock; D. Munshi; A. Murphy; P. Naselsky; P. Natoli; I. Nestoras; C. B. Netterfield; E. Nieppola; H. U. Nørgaard-Nielsen; F. Noviello; D. Novikov; I. Novikov; S. Osborne; F. Pajot; R. Paladini; B. Partridge; F. Pasian; G. Patanchon; T. J. Pearson; O. Perdereau; L. Perotto; F. Perrotta; F. Piacentini; M. Piat; E. Pierpaoli; S. Plaszczynski; P. Platania; E. Pointecouteau; G. Polenta; N. Ponthieu; T. Poutanen; G. Prézeau; P. Procopio; S. Prunet; J.-L. Puget; J. P. Rachen; W. T. Reach; R. Rebolo; M. Reinecke; C. Renault; S. Ricciardi; T. Riller; D. Riquelme; I. Ristorcelli; G. Rocha; C. Rosset; M. Rowan-Robinson; J. A. Rubiño-Martín; B. Rusholme; A. Sajina; M. Sandri; P. Savolainen; D. Scott; M. D. Seiffert; A. Sievers; G. F. Smoot; Y. Sotnikova; J.-L. Starck; F. Stivoli; V. Stolyarov; R. Sudiwala; J.-F. Sygnet; J. Tammi; J. A. Tauber; L. Terenzi; L. Toffolatti; M. Tomasi; M. Tornikoski; J.-P. Torre; M. Tristram; J. Tuovinen; M. Türler; M. Turunen; G. Umana; H. Ungerechts; L. Valenziano; J. Varis; P. Vielva; F. Villa; N. Vittorio; A. Wilkinson; B. D. Wandelt; D. Yvon; A. Zacchei; J. A. Zensus; A. Zonca

2011-01-01

259

THE VARIATIONAL FORMULATION OF THE FOKKER-PLANCK EQUATION  

Microsoft Academic Search

The Fokker-Planck equation, or forward Kolmogorov equation, describes the evolu- tion of the probability density for a stochastic process associated with an Ito stochastic differential equation. It pertains to a wide variety of time-dependent systems in which randomness plays a role. In this paper, we are concerned with Fokker-Planck equations for which the drift term is given by the gradient

RICHARD JORDAN; DAVID KINDERLEHRER; FELIX OTTO

1999-01-01

260

Numerical solution of the space fractional Fokker–Planck equation  

Microsoft Academic Search

The traditional second-order Fokker–Planck equation may not adequately describe the movement of solute in an aquifer because of large deviation from the dynamics of Brownian motion. Densities of ?-stable type have been used to describe the probability distribution of these motions. The resulting governing equation of these motions is similar to the traditional Fokker–Planck equation except that the order ?

F. Liu; V. Anh; I. Turner

2004-01-01

261

Real Planck distribution for a complex Q-boson gas  

Microsoft Academic Search

We discuss the energy-density distribution for a gas of q-bosons with complex deformation parameter by exploiting a new q-complex oscillator algebra in which both the number operator and the energy eigenvalues are real. The corresponding Planck distribution generalizes the results obtained for a real q-boson gas, including Wien's and Stephan's laws, and the role of an effective Planck constant depending

P. Angelopoulou; S. Baskoutas; L. DeFalco; A. Jannussis; R. Mignani; A. Sotiropoulou

1994-01-01

262

Planck early results. XXV. Thermal dust in nearby molecular clouds  

Microsoft Academic Search

Planck allows unbiased mapping of Galactic sub-millimetre and millimetre emission from the most diffuse regions to the densest parts of molecular clouds. We present an early analysis of the Taurus molecular complex, on line-of-sight-averaged data and without component separation. The emission spectrum measured by Planck and IRAS can be fitted pixel by pixel using a single modified blackbody. Some systematic

A. Abergel; P. A. R. Ade; N. Aghanim; M. Arnaud; M. Ashdown; J. Aumont; C. Baccigalupi; A. Balbi; A. J. Banday; R. B. Barreiro; J. G. Bartlett; E. Battaner; K. Benabed; A. Benoît; J.-P. Bernard; M. Bersanelli; R. Bhatia; J. J. Bock; A. Bonaldi; J. R. Bond; J. Borrill; F. Boulanger; M. Bucher; C. Burigana; P. Cabella; J.-F. Cardoso; A. Catalano; L. Cayón; A. Challinor; A. Chamballu; L.-Y. Chiang; C. Chiang; P. R. Christensen; D. L. Clements; S. Colombi; F. Couchot; A. Coulais; B. P. Crill; F. Cuttaia; L. Danese; R. D. Davies; R. J. Davis; P. de Bernardis; G. de Gasperis; A. de Rosa; G. de Zotti; J. Delabrouille; J.-M. Delouis; F.-X. Désert; C. Dickinson; K. Dobashi; S. Donzelli; O. Doré; U. Dörl; M. Douspis; X. Dupac; G. Efstathiou; T. A. Enßlin; H. K. Eriksen; F. Finelli; O. Forni; M. Frailis; E. Franceschi; S. Galeotta; K. Ganga; M. Giard; G. Giardino; Y. Giraud-Héraud; J. González-Nuevo; K. M. Górski; S. Gratton; A. Gregorio; A. Gruppuso; V. Guillet; F. K. Hansen; D. Harrison; S. Henrot-Versillé; D. Herranz; S. R. Hildebrandt; E. Hivon; M. Hobson; W. A. Holmes; W. Hovest; R. J. Hoyland; K. M. Huffenberger; A. H. Jaffe; A. Jones; W. C. Jones; M. Juvela; E. Keihänen; R. Keskitalo; T. S. Kisner; R. Kneissl; L. Knox; H. Kurki-Suonio; G. Lagache; J.-M. Lamarre; A. Lasenby; R. J. Laureijs; C. R. Lawrence; S. Leach; R. Leonardi; C. Leroy; M. Linden-Vørnle; M. López-Caniego; P. M. Lubin; J. F. Macías-Pérez; C. J. MacTavish; B. Maffei; N. Mandolesi; R. Mann; M. Maris; D. J. Marshall; P. Martin; E. Martínez-González; S. Masi; S. Matarrese; F. Matthai; P. Mazzotta; P. McGehee; P. R. Meinhold; A. Melchiorri; L. Mendes; A. Mennella; S. Mitra; M.-A. Miville-Deschênes; A. Moneti; L. Montier; G. Morgante; D. Mortlock; D. Munshi; A. Murphy; P. Naselsky; P. Natoli; C. B. Netterfield; H. U. Nørgaard-Nielsen; F. Noviello; D. Novikov; I. Novikov; S. Osborne; F. Pajot; R. Paladini; F. Pasian; G. Patanchon; O. Perdereau; L. Perotto; F. Perrotta; F. Piacentini; M. Piat; S. Plaszczynski; E. Pointecouteau; G. Polenta; N. Ponthieu; T. Poutanen; G. Prézeau; S. Prunet; J.-L. Puget; W. T. Reach; R. Rebolo; M. Reinecke; C. Renault; S. Ricciardi; T. Riller; I. Ristorcelli; G. Rocha; C. Rosset; J. A. Rubiño-Martín; B. Rusholme; M. Sandri; D. Santos; G. Savini; D. Scott; M. D. Seiffert; P. Shellard; G. F. Smoot; J.-L. Starck; F. Stivoli; V. Stolyarov; R. Sudiwala; J.-F. Sygnet; J. A. Tauber; L. Terenzi; L. Toffolatti; M. Tomasi; J.-P. Torre; M. Tristram; J. Tuovinen; G. Umana; L. Valenziano; L. Verstraete; P. Vielva; F. Villa; N. Vittorio; L. A. Wade; B. D. Wandelt; D. Yvon; A. Zacchei; A. Zonca

2011-01-01

263

Bayesian Inference Based on Stationary Fokker-Planck Sampling  

Microsoft Academic Search

A novel formalism for Bayesian learning in the context of complex inference\\u000amodels is proposed. The method is based on the use of the Stationary\\u000aFokker--Planck (SFP) approach to sample from the posterior density. Stationary\\u000aFokker--Planck sampling generalizes the Gibbs sampler algorithm for arbitrary\\u000aand unknown conditional densities. By the SFP procedure approximate analytical\\u000aexpressions for the conditionals and marginals

Arturo Berrones; Centro de Innovacion; Tecnolog ´ õa

2009-01-01

264

Physical controls of near-surface soil moisture across varying spatial scales in an agricultural landscape during SMEX02  

Microsoft Academic Search

Understanding of near-surface soil moisture variability at different spatial scales and associated dominant physical controls is limited. In the past, soil moisture dynamics studies have been conducted extensively at different spatial scales using both in situ and remote sensing (RS) data in the subhumid Southern Great Plains region, which has mostly pasture and range land cover with rolling topography. Compared

Champa Joshi; Binayak P. Mohanty

2010-01-01

265

Subgrid scale physics in a turbulent boundary layer flow under varying convective stability conditions: an a-priori study  

Microsoft Academic Search

Using data sets collected during the Lake Atmosphere Turbulent Exchanges (LATEX, convectively unstable conditions) and the Snow Horizontal Array Turbulence Study (SnoHATS, convectively stable conditions) field experimental campaigns, we study the impact of this convective stability on the physics of small scale turbulence in the atmospheric boundary layer flow and the implications for modeling the subgrid scales stresses and fluxes

Elie Bou-Zeid; Nikki Vercauteren; Chad Higgins; Hendrik Huwald; Marc B. Parlange; Charles Meneveau

2009-01-01

266

Evaluating introductory physics classes in light of the ABET criteria: An example from the SCALE-UP Project  

Microsoft Academic Search

The Student-Centered Activities for Large Enrollment University Physics (SCALE-UP) project at North Carolina State University (NCSU) is developing a curriculum to promote learning through in-class group activities in introductory physics classes up to 100 students. We are currently in Phase II of the project using a specially designed multimedia classroom for 54 students to teach the introductory physics course for

Jeffery M. Saul; Duane L. Deardorff; David S. Abbott; Rhett J. Allain; Robert J. Beichner

2000-01-01

267

Kinematical evidence for physically different classes of large-scale coronal EUV waves  

NASA Astrophysics Data System (ADS)

Context. Large-scale wavelike disturbances have been observed in the solar corona in the EUV range since more than a decade. The physical nature of these so-called "EIT waves" is still being debated controversially. The two main contenders are on the one hand MHD waves and/or shocks, and on the other hand magnetic reconfiguration in the framework of an expanding CME. There is a lot of observational evidence backing either one or the other scenario, and no single model has been able to reproduce all observational constraints, which are partly even contradictory. This suggests that there may actually exist different classes of coronal waves that are caused by distinct physical processes. Then, the problems in interpreting coronal waves would be mainly caused by mixing together different physical processes. Aims: We search for evidence for physically different classes of large-scale coronal EUV waves. Methods: Kinematics is the most important characteristic of any moving disturbance, hence we focus on this aspect of coronal waves. Identifying distinct event classes requires a large event sample, which is up to now only available from SOHO/EIT. We analyze the kinematics of a sample of 176 EIT waves. In order to check if the results are severely affected by the low cadence of EIT, we complement this with high-cadence data for 17 events from STEREO/EUVI. In particular, we focus on the wave speeds and their evolution. Results: Based on their kinematical behavior, we find evidence for three distinct populations of coronal EUV waves: initially fast waves (v ? 320 km s-1) that show pronounced deceleration (class 1 events), waves with moderate (v ? 170-320 km s-1) and nearly constant speeds (class 2), and slow waves (v ? 130 km s-1) showing a rather erratic behavior (class 3). Conclusions: The kinematical behavior of the fast decelerating disturbances is consistent with nonlinear large-amplitude waves or shocks that propagate faster than the ambient fast-mode speed and subsequently slow down due to decreasing amplitude. The waves with moderate speeds are consistent with linear waves moving at the local fast-mode speed. Thus both populations can be explained in terms of the wave/shock model. The slow perturbations with erratic behavior, on the other hand, are not consistent with this scenario. These disturbances could well be due to magnetic reconfiguration.

Warmuth, A.; Mann, G.

2011-08-01

268

Scale Development for Measuring and Predicting Adolescents' Leisure Time Physical Activity Behavior  

PubMed Central

The aim of this study was to develop a scale for assessing and predicting adolescents’ physical activity behavior in Spain and Luxembourg using the Theory of Planned Behavior as a framework. The sample was comprised of 613 Spanish (boys = 309, girls = 304; M age =15.28, SD =1.127) and 752 Luxembourgish adolescents (boys = 343, girls = 409; M age = 14.92, SD = 1.198), selected from students of two secondary schools in both countries, with a similar socio-economic status. The initial 43-items were all scored on a 4-point response format using the structured alternative format and translated into Spanish, French and German. In order to ensure the accuracy of the translation, standardized parallel back-translation techniques were employed. Following two pilot tests and subsequent revisions, a second order exploratory factor analysis with oblimin direct rotation was used for factor extraction. Internal consistency and test-retest reliabilities were also tested. The 4-week test-retest correlations confirmed the items’ time stability. The same five factors were obtained, explaining 63.76% and 63.64% of the total variance in both samples. Internal consistency for the five factors ranged from ? = 0.759 to ? = 0. 949 in the Spanish sample and from ? = 0.735 to ? = 0.952 in the Luxembourgish sample. For both samples, inter-factor correlations were all reported significant and positive, except for Factor 5 where they were significant but negative. The high internal consistency of the subscales, the reported item test-retest reliabilities and the identical factor structure confirm the adequacy of the elaborated questionnaire for assessing the TPB-based constructs when used with a population of adolescents in Spain and Luxembourg. The results give some indication that they may have value in measuring the hypothesized TPB constructs for PA behavior in a cross-cultural context. Key points When using the structured alternative format, weak internal consistency was obtained. Rephrasing the items and scoring items on a Likert-type scale enhanced greatly the subscales reliability. Identical factorial structure was extracted for both culturally different samples. The obtained factors, namely perceived physical competence, parents’ physical activity, perceived resources support, attitude toward physical activity and perceived parental support were hypothesized as for the original TPB constructs.

Ries, Francis; Romero Granados, Santiago; Arribas Galarraga, Silvia

2009-01-01

269

Scale development for measuring and predicting adolescents' leisure time physical activity behavior.  

PubMed

The aim of this study was to develop a scale for assessing and predicting adolescents' physical activity behavior in Spain and Luxembourg using the Theory of Planned Behavior as a framework. The sample was comprised of 613 Spanish (boys = 309, girls = 304; M age =15.28, SD =1.127) and 752 Luxembourgish adolescents (boys = 343, girls = 409; M age = 14.92, SD = 1.198), selected from students of two secondary schools in both countries, with a similar socio-economic status. The initial 43-items were all scored on a 4-point response format using the structured alternative format and translated into Spanish, French and German. In order to ensure the accuracy of the translation, standardized parallel back-translation techniques were employed. Following two pilot tests and subsequent revisions, a second order exploratory factor analysis with oblimin direct rotation was used for factor extraction. Internal consistency and test-retest reliabilities were also tested. The 4-week test-retest correlations confirmed the items' time stability. The same five factors were obtained, explaining 63.76% and 63.64% of the total variance in both samples. Internal consistency for the five factors ranged from ? = 0.759 to ? = 0. 949 in the Spanish sample and from ? = 0.735 to ? = 0.952 in the Luxembourgish sample. For both samples, inter-factor correlations were all reported significant and positive, except for Factor 5 where they were significant but negative. The high internal consistency of the subscales, the reported item test-retest reliabilities and the identical factor structure confirm the adequacy of the elaborated questionnaire for assessing the TPB-based constructs when used with a population of adolescents in Spain and Luxembourg. The results give some indication that they may have value in measuring the hypothesized TPB constructs for PA behavior in a cross-cultural context. Key pointsWhen using the structured alternative format, weak internal consistency was obtained. Rephrasing the items and scoring items on a Likert-type scale enhanced greatly the subscales reliability.Identical factorial structure was extracted for both culturally different samples.The obtained factors, namely perceived physical competence, parents' physical activity, perceived resources support, attitude toward physical activity and perceived parental support were hypothesized as for the original TPB constructs. PMID:24149606

Ries, Francis; Romero Granados, Santiago; Arribas Galarraga, Silvia

2009-12-01

270

Nicholas Metropolis Award for Outstanding Doctoral Thesis Work in Computational Physics Talk: Understanding Nano-scale Electronic Systems via Large-scale Computation  

NASA Astrophysics Data System (ADS)

Nano-scale physical phenomena and processes, especially those in electronics, have drawn great attention in the past decade. Experiments have shown that electronic and transport properties of functionalized carbon nanotubes are sensitive to adsorption of gas molecules such as H2, NO2, and NH3. Similar measurements have also been performed to study adsorption of proteins on other semiconductor nano-wires. These experiments suggest that nano-scale systems can be useful for making future chemical and biological sensors. Aiming to understand the physical mechanisms underlying and governing property changes at nano-scale, we start off by investigating, via first-principles method, the electronic structure of Pd-CNT before and after hydrogen adsorption, and continue with coherent electronic transport using non-equilibrium Green’s function techniques combined with density functional theory. Once our results are fully analyzed they can be used to interpret and understand experimental data, with a few difficult issues to be addressed. Finally, we discuss a newly developed multi-scale computing architecture, OPAL, that coordinates simultaneous execution of multiple codes. Inspired by the capabilities of this computing framework, we present a scenario of future modeling and simulation of multi-scale, multi-physical processes.

Cao, Chao

2009-03-01

271

An AHP-derived method for mapping the physical vulnerability of coastal areas at regional scales  

NASA Astrophysics Data System (ADS)

Assessing coastal vulnerability to climate change at regional scales is now mandatory in France since the adoption of recent laws to support adaptation to climate change. However, there is presently no commonly recognised method to assess accurately how sea level rise will modify coastal processes in the coming decades. Therefore, many assessments of the physical component of coastal vulnerability are presently based on a combined use of data (e.g. digital elevation models, historical shoreline and coastal geomorphology datasets), simple models and expert opinion. In this study, we assess the applicability and usefulness of a multi-criteria decision-mapping method (the analytical hierarchy process, AHP) to map physical coastal vulnerability to erosion and flooding in a structured way. We apply the method in two regions of France: the coastal zones of Languedoc-Roussillon (north-western Mediterranean, France) and the island of La Réunion (south-western Indian Ocean), notably using the regional geological maps. As expected, the results show not only the greater vulnerability of sand spits, estuaries and low-lying areas near to coastal lagoons in both regions, but also that of a thin strip of erodible cliffs exposed to waves in La Réunion. Despite gaps in knowledge and data, the method is found to provide a flexible and transportable framework to represent and aggregate existing knowledge and to support long-term coastal zone planning through the integration of such studies into existing adaptation schemes.

Le Cozannet, G.; Garcin, M.; Bulteau, T.; Mirgon, C.; Yates, M. L.; Méndez, M.; Baills, A.; Idier, D.; Oliveros, C.

2013-05-01

272

BLISS-CNR-Pisa: a flexible laser for small scale test experiments on fusion oriented physics  

SciTech Connect

By the year 2010 a new laser will be operational at the CNR Campus in Pisa. The laser system will deliver two beams each one providing 1-ns 50-joule pulses of high optical quality and full control of phase. The major feature of the system is its spectral and time shape flexibility ranging from narrowband single mode operation to broadband operation with pulse tailoring. According to previous experiments and recent simulations, these features could critically determine the laser-pellet coupling in the different approaches to laser fusion. The physics involved in the different coupling processes is still not fully investigated experimentally. The BLISS laser, combined with the rest of the ILIL experimental facility, including ultrafast optical probing, time resolved optical X-ray diagnostics and particle detection could contribute to this investigation with ad hoc small scale experiments. The main features of the innovative BLISS laser front end for broadband operation are shown, together with the amplification chain and the main features of the experimental installation. Data from simulations providing a useful input for future experiments are also presented. BLISS is expected to contribute to the preparatory phase of the large scale European HiPER project.

Ciricosta, O. [Intense Laser Irradiation Laboratory, IPCF, Consiglio Nazionale delle Ricerche, Pisa (Italy); Dipartimento di Fisica, Universita di Pisa (Italy); Labate, L.; Gizzi, L. A. [Intense Laser Irradiation Laboratory, IPCF, Consiglio Nazionale delle Ricerche, Pisa (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Pisa (Italy); Atzeni, S.; Schiavi, A. [Dipartimento di Energetica, Universita di Roma 'La Sapienza' (Italy); Barbini, A.; Vaselli, M.; Giulietti, A. [Intense Laser Irradiation Laboratory, IPCF, Consiglio Nazionale delle Ricerche, Pisa (Italy); Batani, D.; Benocci, R. [Dipartimento di Fisica, Universita di Milano Bicocca, Milano (Italy); Cornolti, F.; Giulietti, D. [Dipartimento di Fisica, Universita di Pisa (Italy); Galimberti, M. [Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot (United Kingdom); Gaudio, P.; Martellucci, S.; Richetta, M. [Dipartimento di Scienze e Tecnologie Fisiche ed Energetiche, Universita di Roma (Italy)

2010-02-02

273

Ion flux through membrane channels--an enhanced algorithm for the Poisson-Nernst-Planck model.  

PubMed

A novel algorithmic scheme for numerical solution of the 3D Poisson-Nernst-Planck model is proposed. The algorithmic improvements are universal and independent of the detailed physical model. They include three major steps: an adjustable gradient-based step value, an adjustable relaxation coefficient, and an optimized segmentation of the modeled space. The enhanced algorithm significantly accelerates the speed of computation and reduces the computational demands. The theoretical model was tested on a regular artificial channel and validated on a real protein channel-alpha-hemolysin, proving its efficiency. PMID:18381632

Dyrka, Witold; Augousti, Andy T; Kotulska, Malgorzata

2008-09-01

274

Characterizing scale- and location-dependent correlation of water retention parameters with soil physical properties using wavelet techniques.  

PubMed

Understanding the correlation between soil hydraulic parameters and soil physical properties is a prerequisite for the prediction of soil hydraulic properties from soil physical properties. The objective of this study was to examine the scale- and location-dependent correlation between two water retention parameters (alpha and n) in the van Genuchten (1980) function and soil physical properties (sand content, bulk density [Bd], and organic carbon content) using wavelet techniques. Soil samples were collected from a transect from Fuxin, China. Soil water retention curves were measured, and the van Genuchten parameters were obtained through curve fitting. Wavelet coherency analysis was used to elucidate the location- and scale-dependent relationships between these parameters and soil physical properties. Results showed that the wavelet coherence between alpha and sand content was significantly different from red noise at small scales (8-20 m) and from a distance of 30 to 470 m. Their wavelet phase spectrum was predominantly out of phase, indicating negative correlation between these two variables. The strong negative correlation between alpha and Bd existed mainly at medium scales (30-80 m). However, parameter n had a strong positive correlation only with Bd at scales between 20 and 80 m. Neither of the two retention parameters had significant wavelet coherency with organic carbon content. These results suggested that location-dependent scale analyses are necessary to improve the performance for soil water retention characteristic predictions. PMID:18948482

Shu, Qiaosheng; Liu, Zuoxin; Si, Bingcheng

2008-10-23

275

Minimal Fokker-Planck Theory for the Thermalization of Mesoscopic Subsystems  

NASA Astrophysics Data System (ADS)

We explore a minimal paradigm for thermalization, consisting of two weakly coupled, low dimensional, nonintegrable subsystems. As demonstrated for Bose-Hubbard trimers, chaotic ergodicity results in a diffusive response of each subsystem, insensitive to the details of the drive exerted on it by the other. This supports the hypothesis that thermalization can be described by a Fokker-Planck equation. We also observe, however, that Levy-flight type anomalies may arise in mesoscopic systems, due to the wide range of time scales that characterize ‘sticky’ dynamics.

Tikhonenkov, Igor; Vardi, Amichay; Anglin, James R.; Cohen, Doron

2013-02-01

276

Use of Plot Scale Observations to gauge the applicability of Physically-Based Models  

NASA Astrophysics Data System (ADS)

Catchment hydrologic modeling efforts should be initiated with a comparison between a perceptual model of how the basin functions, and what processes the numerical hydrologic model represents. The majority of recent attention in literature has been focused on using this process to inform conceptual model structures aimed at predicting streamflow from precipitation events. However, this method may also be used to assess the applicability of physically-based models when lumped parameter models are insufficient for research questions. Physically-based models are chosen over lumped parameter conceptual models for their ability to provide detailed spatial information on soil moisture, ephemeral streamflow, and differential snow melt. A plot scale study was conducted in a 0.02 km2 headwater catchment to build a perceptual model of the Tree Line (TL) Experimental Catchment within the Dry Creek Experimental Watershed (DCEW) in the semi-arid foothills north of Boise, ID. Overland flow, through flow, and radiation flux measurements were taken in addition to existing weather station variables (air temperature, relative humidity, wind speed and direction, snow depth, and soil moisture) for the 2011 water year. The 2011 water year is typical of this study site and is characterized by a shallow snowpack that lasts from the late fall to early spring and includes several rain-on-snow events. A soil storage field capacity threshold in the upper highly conductive soil (approximately 145 mm) must be crossed before lateral flow is observed. The total soil storage threshold for lateral flow slowly increases from 253 mm during a December rain-on-snow event, to 269 mm during the spring melt event as deeper, less conductive soils wet up. Lateral flow primarily takes place as overland flow and as concentrated flow paths at the soil-bedrock interface, which are controlled by bedrock topography. Results suggest that the watershed models used in TL need to account for unsaturated soil storage, the development of a shallow hillslope saturated zone, and lateral flow at the soil-bedrock interface. Both the snowmelt model and the watershed model need to account for commonly observed aspect differences in vegetation and insolation. Future work will assess the applicability of the coupled physically-based snowmelt model (SNOBAL) and physically-based watershed model (PIHM) to the 26.9 km2 DCEW.

Kormos, P. R.; McNamara, J. P.; Marks, D. G.; Flores, A. N.; Marshall, H.; Boe, E.

2011-12-01

277

The fat, the twisted and the strangely beautiful (in physics beyond the standard model)  

NASA Astrophysics Data System (ADS)

The standard model of particle physics has been a very successful effective theory, describing physics below the electroweak scale. Despite its successes, the theory has several shortcomings. Examples for this are the hierarchy problem and electroweak symmetry breaking, the flavor hierarchies, the strong CP problem, etc. The standard model also lacks an explanation of dark matter and dark energy, not to mention gravity itself. Many of the problems just mentioned can be solved by introducing new physics beyond the standard model at a scale much lower than the Planck scale. Many of the well motivated scenarios for new physics have signals that are accessible to upcoming experiments such as the LHC. In this thesis I present some of the possible models of physics beyond the SM and also discuss signals of such models at ongoing and planned experiments. The Fat Higgs is a supersymmetric model of a composite Higgs. Thanks to exact results in supersymmetry, a simple UV completion can be identified. Unification of gauge couplings is possible despite the fact that the theory is strongly coupled below the Planck scale. Twisted Split Fermions is a novel extra dimensional framework for addressing the strong CP problem in conjunction with an explanation for the flavor hierarchies. A well motivated supersymmetric framework of unification may involve large flavor changing transitions form b to s that are related to the maximal atmospheric neutrino mixing. In certain cases, correlations between various observable may be identified. Ambitious U(1)X flavor models may solve many of the flavor issues of the SM. These supersymmetric models allow for proton decay suppressed by the Planck scale, which may be observed in the next generation of nucleon decay experiments. The finite density phase of QCD is calculable at high densities where the coupling is strong. In supersymmetric QCD at finite density, exact result may be obtained at lower densities where the coupling is strong. Despite their differences, the two theories share some qualitative features.

Harnik, Ron

278

Planck intermediate results. IX. Detection of the Galactic haze with Planck  

NASA Astrophysics Data System (ADS)

Using precise full-sky observations from Planck, and applying several methods of component separation, we identify and characterise the emission from the Galactic "haze" at microwave wavelengths. The haze is a distinct component of diffuse Galactic emission, roughly centered on the Galactic centre, and extends to | b | ~ 35-50° in Galactic latitude and | l | ~ 15-20° in longitude. By combining the Planck data with observations from the Wilkinson Microwave Anisotropy Probe, we were able to determine the spectrum of this emission to high accuracy, unhindered by the strong systematic biases present in previous analyses. The derived spectrum is consistent with power-law emission with a spectral index of -2.56 ± 0.05, thus excluding free-free emission as the source and instead favouring hard-spectrum synchrotron radiation from an electron population with a spectrum (number density per energy) dN/dE ? E-2.1. At Galactic latitudes | b | < 30°, the microwave haze morphology is consistent with that of the Fermi gamma-ray "haze" or "bubbles", while at b ~ -50° we have identified an edge in the microwave haze that is spatially coincident with the edge in the gamma-ray bubbles. Taken together, this indicates that we have a multi-wavelength view of a distinct component of our Galaxy. Given both the very hard spectrum and the extended nature of the emission, it is highly unlikely that the haze electrons result from supernova shocks in the Galactic disk. Instead, a new astrophysical mechanism for cosmic-ray acceleration in the inner Galaxy is implied.

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoît, A.; Bernard, J.-P.; Bersanelli, M.; Bonaldi, A.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Burigana, C.; Cabella, P.; Cardoso, J.-F.; Catalano, A.; Cayón, L.; Chary, R.-R.; Chiang, L.-Y.; Christensen, P. R.; Clements, D. L.; Colombo, L. P. L.; Coulais, A.; Crill, B. P.; Cuttaia, F.; Danese, L.; D'Arcangelo, O.; Davis, R. J.; de Bernardis, P.; de Gasperis, G.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Dickinson, C.; Diego, J. M.; Dobler, G.; Dole, H.; Donzelli, S.; Doré, O.; Dörl, U.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giardino, G.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Harrison, D.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Jaffe, T. R.; Jagemann, T.; Jewell, J.; Jones, W. C.; Juvela, M.; Keihänen, E.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lawrence, C. R.; Leach, S.; Leonardi, R.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Matthai, F.; Mazzotta, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Mitra, S.; Moneti, A.; Montier, L.; Morgante, G.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Natoli, P.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Pajot, F.; Paladini, R.; Paoletti, D.; Partridge, B.; Pearson, T. J.; Perdereau, O.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G. W.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Rebolo, R.; Reinecke, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Savini, G.; Schaefer, B. M.; Scott, D.; Smoot, G. F.; Spencer, L.; Stivoli, F.; Sudiwala, R.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Türler, M.; Umana, G.; Valenziano, L.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; White, M.; Yvon, D.; Zacchei, A.; Zonca, A.

2013-06-01

279

Fokker-Planck modeling of spherical inertial electrostatic, virtual-cathode fusion systems  

NASA Astrophysics Data System (ADS)

The spherical IEC fusion concept takes advantage of the potential well generated by an Inner spherical cathode (physical or virtual), biased negatively to several kV with respect to a concentric outer grounded boundary, to focus ions inwards and form a dense central core where fusion may occur. However, defocusing of the ion beams due to ion-ion collisions may prevent a satisfactory energy balance in the system. This research concentrates on spherically-symmetric virtual-cathode IEC devices, in which a spherical cloud of electrons, confined a la Penning trap, creates the ion-confining electrostatic well. A bounce-averaged Fokker-Planck model (BAFP) has been constructed to analyze the ion physics in optimistic conditions (i.e., spherically uniform electrostatic well, no collisional interaction between ions and electrons, single ion species). BAFP employs implicit time advancing. To improve particle and energy conservation, the Fokker- Planck collision operator is discretized using a novel energy-conservative difference scheme. The dense algebraic problem that results from the implicit formulation is solved efficiently using multigrid preconditioned Jacobian free Krylov iterative techniques. Results show that steady-state solutions of the bounce-averaged Fokker-Planck equation in which the Maxwellian ion population---absolutely confined in the electrostatic well---is dominant correspond to lowest ion recirculation powers (and hence highest fusion energy gains). Also, it is shown that the square-well assumption---used ubiquitously in previous analytical estimates of IEC fusion energy gain limits---is in fact a pessimistic one, and that more realistic parabolic-like wells are much more efficient operating regimes with fusion power to ion input power ratios >100 have been identified.

Chacon de La Rosa, Luis

2000-11-01

280

Improved alumina scale adhesion of electron beam physical vapor deposited Dy/Hf-doped ?-NiAl coatings  

NASA Astrophysics Data System (ADS)

The cyclic oxidation behavior of Dy/Hf-doped ?-NiAl coatings produced by electron beam physical vapor deposition (EB-PVD) was investigated. For the undoped NiAl coating, numerous voids were formed at the alumina scale/coating interface and large rumpling developed in the scale, leading to premature oxide spallation. The addition of Dy and Hf both improved scale adhesion and the alumina scale grown on the NiAl-Hf coating showed better adhesion than that on the NiAl-Dy coating, although the suppressing effect on interfacial void formation and the scale rumpling resistance were stronger in the NiAl-Dy coating. It is proposed that the segregation of Dy and Hf ions at the scale/coating interfaces not only prevent interfacial sulfur segregation but also may directly enhance interfacial adhesion by participating in bonding across the interfaces, and this strengthening effect is relatively stronger for Hf ionic segregation.

Li, Dongqing; Guo, Hongbo; Peng, Hui; Gong, Shengkai; Xu, Huibin

2013-10-01

281

The physics of non-volcanic tremor: insights from laboratory-scale earthquakes  

NASA Astrophysics Data System (ADS)

Due to his extensive early experience in field structural geology, Luigi Burlini's experimental research was always aimed at using laboratory techniques and simulations to improve our understanding of the physics of natural rock deformation. Here we present an example of collaborative work from the later part of his scientific career in which the main goal was unravelling the physics of non-volcanic tremor in subduction zones. This was achieved by deforming typical source rocks (serpentinites) under conditions (300 MPa and 600oC) that approach those expected in nature (up to 1 GPa and 500oC). The main technical challenge was to capture deformation-induced microseismicity (in the form of acoustic emissions) released under such extreme conditions by means of in-situ transducers designed to work at only modest temperatures (up to 200oC). The main scientific challenges were (1) to link the acoustic emission output to specific physical processes, such as cracking, fluid flow or fluid-crack interactions, by means of waveform and microstructural analysis; and (2) to extrapolate the laboratory acoustic emission signals (kHz to MHz frequency) associated with mm to cm-scale processes, to natural seismicity (0.1-1 Hz frequency) associated with km-scale rock volumes by means of frequency scaling (Aki and Richards, 1980). Episodic tremor and slip (ETS) has been correlated with rupture phenomena in subducting oceanic lithosphere at 30 to 45 km depth, where high Vp/Vs ratios, suggestive of high-fluid pressure, have also been observed. ETS, by accommodating slip in the down-dip portion of the subduction zone, may trigger megathrust earthquakes up-dip in the locked section. In our experiments we measured the output of acoustic emissions during heating of serpentinite samples to beyond their equilibrium dehydration temperature. Experiments were performed on cores samples 15 mm in diameter by 30 mm long under hydrostatic stresses of 200 or 300 MPa in a Paterson high-pressure/high-temperature, internally-heated gas apparatus. Acoustic emission (AE) output was recorded via two piezoelectric transducers embedded within the sample end caps and a third remote transducer located outside the pressure vessel. Drained and undrained experimental conditions were achieved by placing either permeable or impermeable ceramic discs at the samples ends. At 200 MPa, serpentinite dehydrates to talc + olivine + water around 5000C. Associated microseismicity, in the form of high-energy AE events, was confined to a narrow temperature interval just above the equilibrium dehydration temperature. This temperature overstep is expected, and is due to the heating rate in our experiments being much higher than for equilibrium studies. The high-energy AE events were characterised by very long durations, which is typical of a cascade of multiple, overlapping, shorter events that cannot be individually discriminated. Under drained conditions, the serpentinite samples showed a clear volume reduction following dehydration and subsequent compaction. By contrast, under undrained conditions, the samples maintained the same dimensions, but lost weight, implying that no compaction occurred during dehydration. Our results therefore demonstrate conclusively that seismicity can be generated by dehydration reactions even in the absence of a deviatoric stress. This observation is consistent with recent finding that tremor activity in nature has a strong tidal periodicity, indicating that tidal forces modulate slip velocity and suggesting near lithostatic fluid pressures at hypocentral depths. Furthermore, we suggest that the cascades of events that follow the onset of dehydration may well be related to the low-amplitude long-duration seismic events (seismic tremor) that characterize the seismic activity in subduction zones and that has been tentatively interpreted as being caused by dehydration of the subducting slab. Our laboratory observations support this hypothesis, since our low-amplitude, long-duration events were correlated with outflow of water from the samples through the p

di Toro, G.; Meredith, P.

2012-04-01

282

Effects of Land Use, Physical Habitat Type, and Stream Geomorphic Type at Multiple Spatial Scales on Fish Community Diversity  

Microsoft Academic Search

Twenty-five independent stream reaches in northwestern Vermont, USA spanning a range of geomorphic conditions were surveyed to determine the effects of land use and physical habitat on fish community diversity at multiple spatial scales including watershed, local riparian, and in-stream. Watershed-scale parameters were evaluated using a geographic information system (GIS) and the Soil and Water Assessment Tool (SWAT) watershed modeling

C. M. Cianfrani; S. P. Sullivan; W. C. Hession; M. C. Watzin

2006-01-01

283

Pore-scaling Modeling of Physical Property Changes During CO2 Injection into Sandstone  

NASA Astrophysics Data System (ADS)

Carbon dioxide is a green-house gas and is believed to be an important factor in global warming and climate change. Many countries around the world are working on reducing and sequestrating CO2 to follow international regulations. One of promising area for CO2 sequestration is the storage in geological formation. To accurately determine the performance of geological injection and storage, quantification and monitoring of the physical property changes are essential. In this paper, we are presenting a new approach for the monitoring of CO2 sequestration in sandstone using pore-scale simulation techniques. The method consists of three steps: 1) acquisition of high-resolution pore microstructures by X-ray micro-tomography; 2) CO2 injection simulation using lattice-Boltzmann (LB) two-phase flow simulation; and 3) FEM property simulations (electrical and elastic) at different CO2 saturations during the injection. We use three different sandstone samples: sand-pack, Berea sandstone, and B2 sandstone from offshore of Korea. The porosity of the sand-pack is 42% and that of two sandstone samples is around 17%. The digital pore structures were obtained by X-ray micro-tomography with a spatial resolution of 2 micron. The LB two-phase flow simulation is then conducted by injecting CO2 into fully water-saturated samples and gives a realistic movement of CO2 in the pore structure. At each CO2 saturation, electrical and elastic properties are determined by pore-scale FEM simulation techniques. The electrical conductivity decreases almost linearly as CO2 saturations increases; however, the P-wave velocity decrease more rapidly at the low CO2 saturation (up to 30%), than at higher saturation. S-wave velocity does not show any significant changes. The higher porosity rock shows more sensitivity to saturation changes. The modeling shows that we can have quantitative relations between physical properties and CO2 saturation, which can be used to determine injection performance and migration of CO2. However, the change in P-wave velocity is not very significant during CO2 injection, which indicates that the monitoring of CO2 sequestration by acoustic survey would be difficult. Our modeling technique can be a very effective tool for the characterizing of prospecting geological sequestration formation and determining an effective monitoring technique for specific sites. Acknowledgement: This research was funded by CO2 Storage in Marine Geological Structure Program of Ministry of Land, Transport, and Maritime Affairs of South Korea, Grant No. E10500109A060000121.

Keehm, Y.; Yoo, G.

2009-12-01

284

Issues and perspectives of physically-based ecohydrological modeling: crossing spatial and temporal scales  

NASA Astrophysics Data System (ADS)

The coupled, spatially-distributed dynamics of hydrological and vegetation have been extremely difficult to address quantitavely. The analyses are particularly challenging because of the spatially and temporally heterogeneous conditions within watersheds, especially when topographically complex landscapes are considered. Nonetheless, a better understanding of ecosystem functioning, and the improvement of our predictive skills are related to providing consistent simulations of hydrological, energy, and carbon fluxes in heterogeneous landscapes. A mechanistic ecohydrological model Tethys-Chloris is used to investigate these complex dynamics in two ecosystems characterized by cold climate and seasonal snow cover. A range of ecohydrological metrics is presented to highlight the model capabilities in reproducing hydrological and vegetation dynamics across spatial and temporal scales. A diverse set of observations is used to confirm the simulated dynamics. Satisfactory results are obtained without significant calibration efforts despite the large phase-space dimensionality of the model, the uncertainty of imposed boundary conditions, and limited data availability. The background rationale is that the structure of a physically-based/mechanistic model leads to a satisfactory performance with a narrow range of possible outcomes. This is possible because the physically-based (i.e., theoretically measurable) nature of the parameters implies narrower bounds of the values they can assume. The direct consequence is a narrower range of possible model results. Nonetheless, major uncertainties remain in simulating hydrological fluxes in subsurface, such as deep soil horizons as well as at the bedrock interface. While the simulated patterns mimic the outcome of hydrological dynamics with high realism, the lack of spatially distributed data prevents a more rigorous assessment; further community efforts are warranted to address the issue that hampers the development and thorough testing of process-based ecohydrological models. The consequences of a better characterization of watershed ecohydrology in guiding simulations in a simplified conceptual hydrological model are finally discussed.

Fatichi, S.

2011-12-01

285

Cat state, sub-Planck structure and weak measurement  

NASA Astrophysics Data System (ADS)

Heisenberg-limited and weak measurements are the two intriguing notions, used in recent times for enhancing the sensitivity of measurements in quantum metrology. Using a quantum cat state, endowed with sub-Planck structure, we connect these two novel concepts. It is demonstrated that these two phenomena manifest in complementary regimes, depending upon the degree of overlap between the mesoscopic states constituting the cat state under consideration. In particular, we find that when sub-Planck structure manifests, the imaginary weak value is obscured and vice versa.

Pan, Alok Kumar; Panigrahi, Prasanta Kumar

2013-08-01

286

AC-driven Brownian motors: A Fokker-Planck treatment  

NASA Astrophysics Data System (ADS)

We consider a model of AC-driven Brownian motors consisting of a classical particle which is placed in a potential that is periodic in space and time and which is coupled to a heat bath. The effects of fluctuations and dissipation are studied by a time-dependent Fokker-Planck equation. The approach lets us map the original stochastic problem onto a system of ordinary linear algebraic equations. The solution of the equations provides complete information about ratchet transport, avoiding the disadvantages of direct stochastic calculations such as long transients and large statistical fluctuations. The Fokker-Planck approach to dynamical ratchets opens the possibility for further generalizations.

Denisov, S.; Hänggi, P.; Mateos, J. L.

2009-07-01

287

Steamflooding Cold Lake oil reservoirs through a bottomwater zone: A scaled physical model study  

SciTech Connect

A series of experiments was conducted in one-eighth of a five-spot-pattern, high-pressure, scaled physical model to evaluate the potential of steamflooding oil-sand reservoirs through a bottomwater zone in Cold Lake, Alberta. During the experiments, steam was injected into the bottomwater zone at a constant rate until steam breakthrough occurred at the production well. The steam injection rate then was reduced to limit steam production. Results demonstrate that the process is influenced by the steam injection flow rate because of the important role played by gravity override. Increasing the steam injection rate beyond an optimum value results in decreased oil/steam ratios (OSR's) and reduced final oil recovery because steam channels to the production well. A delay in oil production was noticed in all experiments. A moving-heat-source, gravity-override, analytical model was used to investigate the mechanisms of reservoir heating in the presence of steam-gravity override. In addition, the thermal efficiency of the process, determined from the experiments and extrapolated to field conditions, was compared with prediction from Prats' thermal efficiency model. Prats' model predicted the measured thermal efficiency reasonably well at lower injection rates. As the injection rate increased, however, larger differences between Prats' model and the experiments were noticed.

Nasr, T.N.; Pierce, G.E. (Alberta Research Council, Edmonton (Canada))

1993-05-01

288

Boltzmann-Fokker-Planck Calculations Using Standard Discrete-Ordinates Codes.  

National Technical Information Service (NTIS)

The Boltzmann-Fokker-Planck (BFP) equation can be used to describe both neutral and charged-particle transport. Over the past several years, the author and several collaborators have developed methods for representing Fokker-Planck operators with standard...

J. E. Morel

1987-01-01

289

Post-16 Physics and Chemistry Uptake: Combining Large-Scale Secondary Analysis with In-Depth Qualitative Methods  

ERIC Educational Resources Information Center

Quantitative secondary analysis of large-scale data can be combined with in-depth qualitative methods. In this paper, we discuss the role of this combined methods approach in examining the uptake of physics and chemistry in post compulsory schooling for students in England. The secondary data analysis of the National Pupil Database (NPD) served…

Hampden-Thompson, Gillian; Lubben, Fred; Bennett, Judith

2011-01-01

290

Validation of the Perceptions of Teasing Scale (POTS) in a Preadolescent Sample: Associations With Attitudes Toward Physical Activity  

Microsoft Academic Search

This study investigated the construct validity of the Perceptions of Teasing Scale (POTS) in a sample of 381 preadolescent children (mean age = 10.8 years). Children completed the POTS and self-report measures of attitudes toward physical activity (PA). Anthropometric data were collected as a part of a standard school health assessment. Confirmatory factor analysis and structural equation modeling supported the

Chad D. Jensen; Ric G. Steele

2010-01-01

291

Promoting Leisure Physical Activity Participation among Adults with Intellectual Disabilities: Validation of Self-Efficacy and Social Support Scales  

ERIC Educational Resources Information Center

Background: Many individuals with intellectual disabilities are not sufficiently active for availing health benefits. Little is known about correlates of physical activity among this population on which to build health promotion interventions. Materials and Methods: We developed scales for measurement of self-efficacy and social support for…

Peterson, Jana J.; Peterson, N. Andrew; Lowe, John B.; Nothwehr, Faryle K.

2009-01-01

292

Comparison of integral equation and physical scale modeling of the electromagnetic responses of models with large conductivity contrasts  

Microsoft Academic Search

Acomparison is made between the results from two different approachestomodelinggeophysicalelectromagneticresponses: anumericalapproachbasedupontheelectric-fieldintegralequa- tion and the physical scale modeling approach. The particular implementation of the integral-equation solution was developed recently, and the comparison presented here is essentially a test of this new formulation. The implementation approximates the regionofanomalousconductivitybyameshofuniformcuboidal cells and approximates the total electric field within a cell by a linear combination

Colin G. Farquharson; Ken Duckworth; Douglas W. Oldenburg

2006-01-01

293

Fractional Fokker-Planck equation, solution, and application  

Microsoft Academic Search

Recently, Metzler et al. [Phys. Rev. Lett. 82, 3563 (1999)], introduced a fractional Fokker-Planck equation (FFPE) describing a subdiffusive behavior of a particle under the combined influence of external nonlinear force field, and a Boltzmann thermal heat bath. In this paper we present the solution of the FFPE in terms of an integral transformation. The transformation maps the solution of

E. Barkai

2001-01-01

294

Process systems and passivity via the Clausius-Planck inequality  

Microsoft Academic Search

In this paper we define a process system to be a system which has actions with the Clausius-Planck and conservation properties. We use standard and well established results derived from macroscopic thermodynamics to show that a process system has actions which satisfy the dissipation inequality. Furthermore, these actions have an inner product structure and a link between the thermodynamic theory

B. Erik Ydstie; Antonio A. Alonso

1997-01-01

295

Numerical Solution of the Extended Nernst–Planck Model  

Microsoft Academic Search

The main features of a numerical model aiming at predicting the drift of ions in an electrolytic solution upon a chemical potential gradient are presented. The mechanisms of ionic diffusion are described by solving the extended Nernst–Planck system of equations. The electrical coupling between the various ionic fluxes is accounted for by the Poisson equation. Furthermore, chemical activity effects are

E. Samson; J. Marchand

1999-01-01

296

Generalizations and extensions of the Fokker- Planck-Kolmogorov equations  

Microsoft Academic Search

In this paper, the classical Fokker-Planck-Kolmogorov equations are generalized to hold for conditional probability density functions of arbitrary random processes. Conditions are derived under which the generalized equations are of finite order both for one-dimensional and for vector random processes. An extension of the generalized equations which overcomes degeneracy occurring in the steady-state case is also presented.

R. Pawula

1967-01-01

297

Simplified Derivation of the Fokker-Planck Equation.  

ERIC Educational Resources Information Center

Presents an alternative derivation of the Fokker-Planck equation for the probability density of a random noise process, starting from the Langevin equation. The derivation makes use of the first two derivatives of the Dirac delta function. (Author/GA)

Siegman, A. E.

1979-01-01

298

Planck pre-launch status: Expected LFI polarisation capability  

Microsoft Academic Search

We present a system-level description of the Low Frequency Instrument (LFI) considered as a differencing polarimeter, and evaluate its expected performance. The LFI is one of the two instruments on board the ESA Planck mission to study the cosmic microwave background. It consists of a set of 22 radiometers sensitive to linear polarisation, arranged in orthogonally-oriented pairs connected to 11

J. P. Leahy; M. Bersanelli; O. D'Arcangelo; K. Ganga; S. M. Leach; A. Moss; E. Keihänen; R. Keskitalo; H. Kurki-Suonio; T. Poutanen; M. Sandri; D. Scott; J. Tauber; L. Valenziano; F. Villa; A. Wilkinson; A. Zonca; C. Baccigalupi; J. Borrill; R. C. Butler; F. Cuttaia; R. J. Davis; M. Frailis; E. Francheschi; S. Galeotta; A. Gregorio; R. Leonardi; N. Mandolesi; M. Maris; P. Meinhold; L. Mendes; A. Mennella; G. Morgante; G. Prezeau; G. Rocha; L. Stringhetti; L. Terenzi; M. Tomasi

2010-01-01

299

A nonlinear filter based on Fokker-Planck equation  

Microsoft Academic Search

In this paper, a nonlinear filter based on Fokker-Planck equation (FPE) is presented for applications involving long time durations in between measurement updates. A previously developed semianalytical meshless algorithm is used to obtain the transient FPE response of nonlinear systems in near real time. Use of eigenfunctions of the discretized FP operator as basis functions causes equation error in FPE

Mrinal Kumar; Suman Chakravorty

2010-01-01

300

Fokker-Planck transport in solid state accelerator concepts  

SciTech Connect

Particle transport in a crystalline solid under channeling conditions is considered by means of a Fokker-Planck description. The model includes electron multiple scattering, radiation damping and an accelerating electric field. Analytic solutions have been obtained using a harmonic potential model to describe the channeling forces. These solutions will be described.

Newberger, B.; Tajima, T.

1989-01-01

301

A statistical physics approach to scale-free networks and their behaviors  

NASA Astrophysics Data System (ADS)

This thesis studies five problems of network properties from a unified local-to-global viewpoint of statistical physics: (1) We propose an algorithm that allows the discovery of communities within graphs of arbitrary size, based on Kirchhoff theory of electric networks. Its time complexity scales linearly with the network size. We additionally show how this algorithm allows for the swift discovery of the community surrounding a given node without having to extract all the communities out of a graph. (2) We present a dynamical theory of opinion formation that takes explicitly into account the structure of the social network in which individuals are embedded. We show that the weighted fraction of the population that holds a certain opinion is a martingale. We show that the importance of a given node is proportional to its degree. We verify our predictions by simulations. (3) We show that, when the information transmissibility decays with distance, the epidemic spread on a scale-free network has a finite threshold. We test our predictions by measuring the spread of messages in an organization and by numerical experiments. (4) Suppose users can switch between two behaviors when entering a queueing system: one that never restarts an initial request and one that restarts infinitely often. We show the existence of two thresholds. When the system load is below the lower threshold, it is always better off to be impatient. When above, it is always better off to be patient. Between the two thresholds there exists a homogeneous Nash equilibrium with non-trivial properties. We obtain exact solutions for the two thresholds. (5) We study the endogenous dynamics of reputations in a system consisting of firms with long horizons that provide services with varying levels of quality, and customers who assign to them reputations on the basis of the quality levels that they experience when interacting with them. We show that the dynamics can lead to either well defined equilibria or persistent nonlinear oscillations in the number of customers visiting a firm, implying unstable reputations. We establish the stable criteria.

Wu, Fang

302

The development of the `P.E.T.¿ Scale for the measurement of Physical and Emotional Tormenting against animals in adolescents  

Microsoft Academic Search

The Physical and Emotional Tormenting Against Animals Scale (P.E.T.) is a new self-administered scale to measure physical and emotional abuse against animals among adolescents. This study is a first attempt to establish the reliability and validity of this newly developed scale with a non-clinical sample of 1396 Italian adolescents, aged 11-17 years.The scale measures different dimensions of animal abuse, ranging

Anna C. Baldry

2004-01-01

303

Scaled physical model studies of the steam drive process. First annual report, September 1977-September 1978  

SciTech Connect

Scaling laws of the heat transport mechanism in steam displacement processes are developed based upon an integral energy balance equation. Unlike the differential approach adopted by previous workers, the above scaling laws do not necessitate the use of any empirical correction factor as has been done in previous scaling calculations. The results provide a complete and consistent scale-down of the energy transport behavior, which is the critical mechanism for the success of a steam injection process. In the course of the study, the scaling problems associated with relative permeability and capillary pressure are also discussed. A method which has often been used in scaling nonthermal displacement processes is applied to reduce errors due to scaling in relative permeability. Both dimensional and inspectional analyses are applied to illustrate their use in steam processes. Scale-up laws appeared in the literature and those used in this study are compared and numerical examples are given.

Doscher, T M

1980-12-01

304

A multi-physics and multi-scale lumped parameter model of cardiac contraction of the left ventricle: a conceptual model from the protein to the organ scale.  

PubMed

In cardiovascular computational physiology the importance of understanding cardiac contraction as a multi-scale process is of paramount importance to understand causality across different scales. Within this study, a multi-scale and multi-physics model of the left ventricle that connects the process of cardiac excitation and contraction from the protein to the organ level is presented in a novel way. The model presented here includes the functional description of a cardiomyocyte (cellular scale), which explains the dynamic behaviour of the calcium concentration within the cell whilst an action potential develops. The cell domain is coupled to a domain that determines the kinetics of the sliding filament mechanism (protein level), which is at the basis of cardiac contraction. These processes are then linked to the generation of muscular force and from there to the generation of pressure inside the ventricle. This multi-scale model presents a coherent and unified way to describe cardiac contraction from the protein to the organ level. PMID:22921613

Bhattacharya-Ghosh, Benjamin; Schievano, Silvia; Díaz-Zuccarini, Vanessa

2012-08-24

305

A COMPREHENSIVE VIEW OF A STRONGLY LENSED PLANCK-ASSOCIATED SUBMILLIMETER GALAXY  

SciTech Connect

We present high-resolution maps of stars, dust, and molecular gas in a strongly lensed submillimeter galaxy (SMG) at z = 3.259. HATLAS J114637.9-001132 is selected from the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) as a strong lens candidate mainly based on its unusually high 500 {mu}m flux density ({approx}300 mJy). It is the only high-redshift Planck detection in the 130 deg{sup 2} H-ATLAS Phase-I area. Keck Adaptive Optics images reveal a quadruply imaged galaxy in the K band while the Submillimeter Array and the Jansky Very Large Array show doubly imaged 880 {mu}m and CO(1{yields}0) sources, indicating differentiated distributions of the various components in the galaxy. In the source plane, the stars reside in three major kpc-scale clumps extended over {approx}1.6 kpc, the dust in a compact ({approx}1 kpc) region {approx}3 kpc north of the stars, and the cold molecular gas in an extended ({approx}7 kpc) disk {approx}5 kpc northeast of the stars. The emissions from the stars, dust, and gas are magnified by {approx}17, {approx}8, and {approx}7 times, respectively, by four lensing galaxies at z {approx} 1. Intrinsically, the lensed galaxy is a warm (T{sub dust} {approx} 40-65 K), hyper-luminous (L{sub IR} {approx} 1.7 Multiplication-Sign 10{sup 13} L{sub Sun }; star formation rate (SFR) {approx}2000 M{sub Sun} yr{sup -1}), gas-rich (M{sub gas}/M{sub baryon} {approx} 70%), young (M{sub stellar}/SFR {approx} 20 Myr), and short-lived (M{sub gas}/SFR {approx} 40 Myr) starburst. With physical properties similar to unlensed z > 2 SMGs, HATLAS J114637.9-001132 offers a detailed view of a typical SMG through a powerful cosmic microscope.

Fu Hai; Cooray, A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Jullo, E. [Observatoire d'Astrophysique de Marseille-Provence, 38 rue Frederic Joliot-Curie, F-13388 Marseille (France); Bussmann, R. S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Ivison, R. J. [UK Astronomy Technology Centre, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Perez-Fournon, I. [Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain); Djorgovski, S. G.; Scoville, N.; Yan, L.; Riechers, D. A.; Bradford, M. [Department of Astronomy, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Aguirre, J. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Auld, R. [School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA (United Kingdom); Baes, M. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium); Baker, A. J. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Rd., Piscataway, NJ 08854 (United States); Cava, A. [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Clements, D. L. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Dannerbauer, H. [Institut fuer Astronomie, Universitaet Wien, Tuerkenschanzstrasse 17, A-1160 Wien (Austria); Dariush, A. [Physics Department, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom); De Zotti, G., E-mail: haif@uci.edu [INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova (Italy); and others

2012-07-10

306

The shape of the primordial power spectrum: A last stand before Planck data  

SciTech Connect

We present a minimally parametric reconstruction of the primordial power spectrum using the most recent cosmic microwave background and large-scale structure data sets. Our goal is to constrain the shape of the power spectrum while simultaneously avoiding strong theoretical priors and over-fitting of the data. We find no evidence for any departure from a power-law spectral index. We also find that an exact scale-invariant power spectrum is disfavored by the data, but this conclusion is weaker than the corresponding result assuming a theoretically-motivated power-law spectral index prior. The reconstruction shows that better data are crucial to justify the adoption of such a strong theoretical prior observationally. These results can be used to determine the robustness of our present knowledge when compared with forthcoming precision data from Planck.

Peiris, Hiranya V. [Institute of Astronomy and Kavli Institute for Cosmology, University of Cambridge, Cambridge CB3 0HA (United Kingdom); Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Verde, Licia [ICREA and Instituto de Ciencias del Cosmos, Universitat de Barcelona, Marti i Franques 1, 08028, Barcelona (Spain)

2010-01-15

307

MODELING THE SUNSPOT NUMBER DISTRIBUTION WITH A FOKKER-PLANCK EQUATION  

SciTech Connect

Sunspot numbers exhibit large short-timescale (daily-monthly) variation in addition to longer-timescale variation due to solar cycles. A formal statistical framework is presented for estimating and forecasting randomness in sunspot numbers on top of deterministic (including chaotic) models for solar cycles. The Fokker-Planck approach formulated assumes a specified long-term or secular variation in sunspot number over an underlying solar cycle via a driver function. The model then describes the observed randomness in sunspot number on top of this driver function. We consider a simple harmonic choice for the driver function, but the approach is general and can easily be extended to include other drivers which account for underlying physical processes and/or empirical features of the sunspot numbers. The framework is consistent during both solar maximum and minimum, and requires no parameter restrictions to ensure non-negative sunspot numbers. Model parameters are estimated using statistically optimal techniques. The model agrees both qualitatively and quantitatively with monthly sunspot data even with the simplistic representation of the periodic solar cycle. This framework should be particularly useful for solar cycle forecasters and is complementary to existing modeling techniques. An analytic approximation for the Fokker-Planck equation is presented, which is analogous to the Euler approximation, which allows for efficient maximum likelihood estimation of large data sets and/or when using difficult to evaluate driver functions.

Noble, P. L.; Wheatland, M. S., E-mail: p.noble@physics.usyd.edu.au [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia)

2011-05-01

308

Fokker-Planck description for the queue dynamics of large tick stocks  

NASA Astrophysics Data System (ADS)

Motivated by empirical data, we develop a statistical description of the queue dynamics for large tick assets based on a two-dimensional Fokker-Planck (diffusion) equation. Our description explicitly includes state dependence, i.e., the fact that the drift and diffusion depend on the volume present on both sides of the spread. “Jump” events, corresponding to sudden changes of the best limit price, must also be included as birth-death terms in the Fokker-Planck equation. All quantities involved in the equation can be calibrated using high-frequency data on the best quotes. One of our central findings is that the dynamical process is approximately scale invariant, i.e., the only relevant variable is the ratio of the current volume in the queue to its average value. While the latter shows intraday seasonalities and strong variability across stocks and time periods, the dynamics of the rescaled volumes is universal. In terms of rescaled volumes, we found that the drift has a complex two-dimensional structure, which is a sum of a gradient contribution and a rotational contribution, both stable across stocks and time. This drift term is entirely responsible for the dynamical correlations between the ask queue and the bid queue.

Garèche, A.; Disdier, G.; Kockelkoren, J.; Bouchaud, J.-P.

2013-09-01

309

A Physical-Experimental Model for Small-Scale Basaltic Vulcanian Eruptions  

NASA Astrophysics Data System (ADS)

In the last period of its summer 2001 flank activity Mt. Etna produced ash explosions not common at this basaltic volcano. The explosions took place at a new vent at 2550 m.a.s.l. and followed Strombolian and effusive activity. At first the ash erupted as a continuous, pulsing plume a few km high, occasionally undergoing small-scale, partial collapses. Afterward the frequency and intensity of the explosions decreased to isolated events, gradually fading to an end. Each explosion produced mostly wind-driven ash and subordinate blocks ballistically emplaced close to the vent. The final deposit is an ash layer 20 cm thick at 50 m from the vent. Both the ash and the blocks are poorly vesicular with a microcrystalline matrix. This type of activity, deposit, and products closely match, although on a smaller scale, those of Vulcanian explosions: hence we hypothesize that a similar mechanism of overpressurization of a magma plug was at work at Etna. Petrological observations indicate that the plug formed by gradual crystallization of the stagnant magma at the top and at the borders of the conduit after the Strombolian and effusive activity. In order to model the ash explosions we applied three independent techniques to estimate the overpressure in the exploding plug: 1) HP-HT shock tube experiments to determine the pressure differential required to fragment the plug material; 2) calculation of the overpressure generated by plug crystallization; 3) application of two physical models for vulcanian eruptions using the range of ballistic blocks. To measure the minimum pressure differential required to fragment them, we heat and pressurize cylindrical cores from the blocks at T up to 800-900° C and P up to 25 MPa inside a shock-tube apparatus, and then suddenly decompress them to ambient conditions. The pressure threshold varies strongly with sample porosity, from 22.5 MPa at 4% porosity to less that 5 MPa at 20%. Since these values came from the dense blocks that were not fragmented to ash, we assume the lower value as representative of the ash-forming magma. The ash from the explosions has 35 vol.% more microlites than that from Strombolian activity. Applying available models of crystallization-induced overpressurization and find that crystallization of 35 vol.% of microlites is enough to pressurize a basaltic magma to 4-6 MPa at a depth of 100 m ca.. Finally we use the range of ballistic blocks to estimate their exit velocity that, in turn, can be related to the pressure in the conduit. Using realistic values for the ejection angle, shape and density of the blocks, and other ambient conditions, the maximum range of 450 m for blocks of 60 cm corresponds to a muzzle velocity of 80 ms-1. Using this value as an input, two different models for vulcanian eruptions give an initial pressure of 4-6 MPa in the assumption that the volatile content of magma in the plug is in the order of 0.1 wt.%. This assumption is in agreement with petrological evidence that the plug formed by the accumulation of largely degassed magma. In our model, crystallization of 35 vol.% microlites in a magma with 0.1 wt.% of volatiles at a depth of 100 m increase the overpressure in the plug up to 4-6 MPa. At this point the fragmentation threshold is reached and an explosion occurs, ejecting blocks at speeds up to 80 ms-1. Notwithstanding the fact that other processes may contribute pressurizing the plug, we believe that the convergence of three independent methods under reasonable assumptions strongly supports our model.

Scarlato, P.; Taddeucci, J.; Spieler, O.; Kennedy, B.; Dingwell, D. B.; Pompilio, M.

2003-12-01

310

Dedicated hardware for linearly-scaling algorithms in condensed-matter physics  

Microsoft Academic Search

The locality of the interactions in a Hamiltonian model gives origin to the linearization of the algorithms expressing the calculation of the interactions. This specific property, often used in condensed matter physics, has originated approximate models which, although preserving most of the physical insights of the parent exact models, display attractive computational properties which has determined their use in several

Fabrizio Cleri; Alessandro Marongiu; Vittorio Rosato

2001-01-01

311

Physics on the Smallest Scales: An Introduction to Minimal Length Phenomenology  

ERIC Educational Resources Information Center

Many modern theories which try to unify gravity with the Standard Model of particle physics, such as e.g. string theory, propose two key modifications to the commonly known physical theories: the existence of additional space dimensions; the existence of a minimal length distance or maximal resolution. While extra dimensions have received a wide…

Sprenger, Martin; Nicolini, Piero; Bleicher, Marcus

2012-01-01

312

Physics on the Smallest Scales: An Introduction to Minimal Length Phenomenology  

ERIC Educational Resources Information Center

|Many modern theories which try to unify gravity with the Standard Model of particle physics, such as e.g. string theory, propose two key modifications to the commonly known physical theories: the existence of additional space dimensions; the existence of a minimal length distance or maximal resolution. While extra dimensions have received a wide…

Sprenger, Martin; Nicolini, Piero; Bleicher, Marcus

2012-01-01

313

On ENSO Physics  

Microsoft Academic Search

Two extended integrations of general circulation models (GCMs) are examined to determine the physical processes operating during an ENSO cycle. The first integration is from the Hamburg version of the ECMWF T21 atmospheric model forced with observed global sea surface temperatures (SST) over the period 1970-85. The second integration is from a Max Planck Institut model of the tropical Pacific

T. P. Barnett; M. Latif; E. Kirk; E. Roeckner

1991-01-01

314

Effects of Land Use, Physical Habitat Type, and Stream Geomorphic Type at Multiple Spatial Scales on Fish Community Diversity  

NASA Astrophysics Data System (ADS)

Twenty-five independent stream reaches in northwestern Vermont, USA spanning a range of geomorphic conditions were surveyed to determine the effects of land use and physical habitat on fish community diversity at multiple spatial scales including watershed, local riparian, and in-stream. Watershed-scale parameters were evaluated using a geographic information system (GIS) and the Soil and Water Assessment Tool (SWAT) watershed modeling software. Riparian vegetation was surveyed and classified in the field. In-stream physical characteristics were assessed using rapid geomorphic and rapid habitat assessments. Detailed in-stream geomorphic surveys and habitat assessments were also completed to provide quantitative data for each site. In-stream physical habitat was classified as having either predominantly pool-riffle type or comprised of multiple channel types. Fish were sampled using a bag seine at three to four locations selected to represent major flow habitats. Three fish community diversity measures were calculated: 1) Species richness (S); Shannon-Weaver Index (H'); and Simpson's Index (1/D). Analysis of variance (ANOVA), principal components analysis (PCA), and multiple regression were used to assess the relative importance of and the relationships between and among land use/physical habitat type and fish community diversity. Watershed scale land use was found to be a significant predictor of fish community diversity. Further, fish community diversity was higher for all three measures in streams with multiple channel types as compared to predominantly pool-riffle streams. Our results suggest that sampling strategies for fish (and potentially other biota) that focus on homogeneous reaches may underestimate diversity. In order to address these issues, comprehensive watershed management and restoration/protection plans should include assessment at multiple scales from a geomorphological, watershed, and ecological perspective.

Cianfrani, C. M.; Sullivan, S. P.; Hession, W. C.; Watzin, M. C.

2006-05-01

315

Upgrade of the CQL3D Fokker-Planck code  

NASA Astrophysics Data System (ADS)

Recent modifications of the bounce-averaged Collision-Quasilinear Fokker-Planck equation solver, CQL3D [1], are discussed. A fully-implicit 3D (2D-in-momentum, 1D-in-generalized radius) iterative solve using sparse matrix techniques provides for time-steps up to near the transport time, and can be used as the main option. The fully-relativistic nonlinear collisional operator is updated and tested. The radial transport module has been improved. Multi-species QL diffusion capability is added. Neutral particle analyzer synthetic diagnostic is modified. A non-symmetric up-down equilibrium capabilty is added. Example applications are given. Work on including finite-orbit-width effects is in progress and will also be discussed. [4pt] [1] R.W. Harvey and M. McCoy, ``The CQL3D Fokker Planck Code,'' www.compxco.com/cql3d.html

Petrov, Yu.; Harvey, R. W.; Prater, R.

2010-11-01

316

What if Planck's Universe isn't flat?  

NASA Astrophysics Data System (ADS)

Inflationary theory predicts that the observable Universe should be very close to flat, with a spatial-curvature parameter |?K|?10-4. The WMAP satellite currently constrains |?K|?0.01, and the Planck satellite will be sensitive to values near 10-3. Suppose that Planck were to find ?K?0 at this level. Would this necessarily be a serious problem for inflation? We argue that an apparent departure from flatness could be due either to a local (wavelength comparable to the observable horizon) inhomogeneity, or a truly superhorizon departure from flatness. If there is a local inhomogeneity, then secondary cosmic microwave background (CMB) anisotropies distort the CMB frequency spectrum at a level potentially detectable by a next-generation experiment. We discuss how these spectral distortions would complement constraints on the Grishchuk-Zel’dovich effect from the low-? CMB power spectrum in discovering the source of the departure from flatness.

Bull, Philip; Kamionkowski, Marc

2013-04-01

317

Mixed inflaton and spectator field models after Planck  

NASA Astrophysics Data System (ADS)

We investigate the possibility that the primordial perturbation has two sources: the inflaton and a spectator field, which is not dynamically important during inflation but which after inflation can contribute to the curvature perturbation. We derive the constraints on the model by using recent Planck results on the spectral index, tensor-to-scalar ratio and nonlinearity parameters fNL and ?NL for the cases with and without specifying the inflation and spectator models. If one chooses the spectator to be the curvaton with a quadratic potential, non-Gaussianities can be computed and imply restrictions on possible values of the ratio of the spectator-to-inflaton power R. We also consider a mixed curvaton and chaotic inflation model and show that even quartic chaotic inflation is still feasible in the context of mixed models even with Planck data.

Enqvist, Kari; Takahashi, Tomo

2013-10-01

318

Resurrecting power law inflation in the light of Planck results  

NASA Astrophysics Data System (ADS)

It is well known that a canonical scalar field with an exponential potential can drive power law inflation (PLI). However, the tensor-to-scalar ratio in such models turns out to be larger than the stringent limit set by recent Planck results. We propose a new model of power law inflation for which the scalar spectra index, the tensor-to-scalar ratio and the non-gaussianity parameter fNLequil are in excellent agreement with Planck results. Inflation, in this model, is driven by a non-canonical scalar field with an inverse power law potential. The Lagrangian for our model is structurally similar to that of a canonical scalar field and has a power law form for the kinetic term. A simple extension of our model resolves the graceful exit problem which usually afflicts models of power law inflation.

Unnikrishnan, Sanil; Sahni, Varun

2013-10-01

319

Subgrid scale physics in a turbulent boundary layer flow under varying convective stability conditions: an a-priori study  

NASA Astrophysics Data System (ADS)

Using data sets collected during the Lake Atmosphere Turbulent Exchanges (LATEX, convectively unstable conditions) and the Snow Horizontal Array Turbulence Study (SnoHATS, convectively stable conditions) field experimental campaigns, we study the impact of this convective stability on the physics of small scale turbulence in the atmospheric boundary layer flow and the implications for modeling the subgrid scales stresses and fluxes (of heat and moisture) in large eddy simulation. Results indicate that the subgrid scale turbulent Prandtl number increases significantly as the flow transitions from unstable to stable. Under all stabilities, the TKE and scalar variance dissipation estimated based on the structure functions are very good estimates of the flux of energy to the subgrid scales; however, under stable conditions, a significant fraction of the TKE flux is destroyed by buoyancy rather than by viscous dissipation. Finally, the effect of stability on the coefficients of 2 SGS models is shown to be better explained by the Ozmidov scale under stable conditions. Overall, these results indicate that subgrid scale modeling is not drastically affected by atmospheric stability and hence a unified approach is possible.

Bou-Zeid, Elie; Vercauteren, Nikki; Higgins, Chad; Huwald, Hendrik; Parlange, Marc B.; Meneveau, Charles

2009-11-01

320

Classification of Compact Submillimeter Sources in the Planck Archive  

NASA Astrophysics Data System (ADS)

The Planck satellite is a third-generation space-based cosmic microwave background (CMB) experiment with greater resolution and broader frequency range than its predecessors, COBE and WMAP. The completion of the first high-sensitivity submillimeter all-sky survey in April 2010 allows a unique opportunity to study the classes of astronomical sources that are foregrounds to the CMB. This project uses the Planck Early Release Compact Source Catalog (ERCSC) to classify compact objects, which have not previously been seen by IRAS. In an effort to avoid the effects of confusion from the high density of sources in the Galactic plane, we confine our study to |b|>20°. Due to the ~5 arcmin resolution of Planck data and resultant uncertainty in the positions of sources, we used WISE 12-µm and 24-µm data to determine accurate positions and an estimate of the far-infrared color temperature of the sources. Other catalogs, including Akari, IRAS, Sloan and 2MASS, were then searched to pinpoint the counterpart of the source and obtain their spectral energy distribution (SED). The SED was used to constrain the origin of the far-infrared emission and provide further clues as to the nature of the sources. Preliminary results show Planck ERCSC sources include planetary nebulae, star-forming galaxies, stars with surrounding dust, and cold stellar cores. Teachers and students from four schools are active participants in the data analysis process to bring authentic research into the classroom. This research was made possible through the NASA/IPAC Teacher Archive Research Project (NITARP) and was funded by NASA Astrophysics Data Program and Archive Outreach funds.

Johnson, Chelen H.; Border, C.; O'Connor, K.; Rothrock, D.; Chary, R.; Bingham, M.; Clark, M.; Ernst, M.; Gilbert, S.; Koop, S.; Maddaus, M.; Miller, I.; O'Bryan, A.; Ravelomanantsoa, T.; SanMiguel, D.; Schmidt, L.; Searls, E.; Tong, W.; Torres, O.; Zeidner, A.; NITARP

2013-01-01

321

Fokker-Planck models and globular cluster evolution  

Microsoft Academic Search

Numerical models for globular cluster evolution using the orbit averaged Fokker-Planck equation are compared with observations of the globular clusters M71 and NGC 6397. The first set of models studied includes a mass spectrum, a tidal boundary and allows for a central energy source from the formation, hardening and destruction of binaries formed in three-body interactions. These models are compared

Gordon Alan Drukier

1992-01-01

322

Orbit-averaged guiding-center Fokker-Planck operator  

Microsoft Academic Search

A general orbit-averaged guiding-center Fokker-Planck operator suitable for the numerical analysis of transport processes in axisymmetric magnetized plasmas is presented. The orbit-averaged guiding-center operator describes transport processes in a three-dimensional guiding-center invariant space: the orbit-averaged magnetic-flux invariant psi, the minimum-B pitch-angle coordinate xi0, and the momentum magnitude p.

A. J. Brizard; J. Decker; Y. Peysson; F.-X. Duthoit

2009-01-01

323

Critical Design Decisions of The Planck LFI Level 1 Software  

NASA Astrophysics Data System (ADS)

The PLANCK satellite with two on-board instruments, a Low Frequency Instrument (LFI) and a High Frequency Instrument (HFI) has been launched on May 14th with Ariane 5. The ISDC Data Centre for Astrophysics in Versoix, Switzerland has developed and maintains the Planck LFI Level 1 software for the Data Processing Centre (DPC) in Trieste, Italy. The main tasks of the Level 1 processing are to retrieve the daily available scientific and housekeeping (HK) data of the LFI instrument, the Sorption Cooler and the 4k Cooler data from Mission Operation Centre (MOC) in Darmstadt; to sort them by time and by type (detector, observing mode, etc...); to extract the spacecraft attitude information from auxiliary files; to flag the data according to several criteria; and to archive the resulting Time Ordered Information (TOI), which will then be used to produce maps of the sky in different spectral bands. The output of the Level 1 software are the TOI files in FITS format, later ingested into the Data Management Component (DMC) database. This software has been used during different phases of the LFI instrument development. We started to reuse some ISDC components for the LFI Qualification Model (QM) and we completely rework the software for the Flight Model (FM). This was motivated by critical design decisions taken jointly with the DPC. The main questions were: a) the choice of the data format: FITS or DMC? b) the design of the pipelines: use of the Planck Process Coordinator (ProC) or a simple Perl script? c) do we adapt the existing QM software or do we restart from scratch? The timeline and available manpower are also important issues to be taken into account. We present here the orientation of our choices and discuss their pertinence based on the experience of the final pre-launch tests and the start of real Planck LFI operations.

Morisset, N.; Rohlfs, R.; Türler, M.; Meharga, M.; Binko, P.; Beck, M.; Frailis, M.; Zacchei, A.

2010-12-01

324

Submillimetre analysis of a compact test range for Planck application  

Microsoft Academic Search

Compact Antenna Test-Ranges (CATR) represent a high standard of state-of-the-art test facilities with a fast and real time measurement capability up to the sub-millimeter range. Future scientific observation instruments of ESA such as the Planck and Herschel telescopes are working within this frequency ranges and require a high measurement accuracy for large antenna apertures. This present paper shows the first

J. Brossard; D. Dubruel; B. Buralli

2002-01-01

325

Derivative pricing with non-linear Fokker-Planck dynamics  

NASA Astrophysics Data System (ADS)

We examine how the Black-Scholes derivative pricing formula is modified when the underlying security obeys non-extensive statistics and Fokker-Planck dynamics. An unusual feature of such securities is that the volatility in the underlying Ito-Langevin equation depends implicitly on the actual market rate of return. This complicates most approaches to valuation. Here we show that progress is possible using variations of the Cox-Ross valuation technique.

Michael, Fredrick; Johnson, M. D.

2003-06-01

326

Orbit-averaged guiding-center Fokker-Planck operator  

SciTech Connect

A general orbit-averaged guiding-center Fokker-Planck operator suitable for the numerical analysis of transport processes in axisymmetric magnetized plasmas is presented. The orbit-averaged guiding-center operator describes transport processes in a three-dimensional guiding-center invariant space: the orbit-averaged magnetic-flux invariant {psi}, the minimum-B pitch-angle coordinate {xi}{sub 0}, and the momentum magnitude p.

Brizard, A. J. [Department of Chemistry and Physics, Saint Michael's College, Colchester, Vermont 05439 (United States); Decker, J.; Peysson, Y.; Duthoit, F.-X. [CEA, IRFM, Saint-Paul-lez-Durance F-13108 (France)

2009-10-15

327

Nonlinear Fokker-Planck Navier-Stokes systems  

Microsoft Academic Search

We consider Navier-Stokes equations coupled to nonlinear Fokker-Planck equations\\u000adescribing the probability distribution of particles interacting with fluids. We describe relations\\u000adetermining the coefficients of the stresses added in the fluid by the particles. These relations\\u000alink the added stresses to the kinematic effect of the fluid's velocity on particles and to the inter-\\u000aparticle interaction potential. In equations of

Peter Constantin

2005-01-01

328

A Fokker-Planck description for Parrondo's games  

NASA Astrophysics Data System (ADS)

We discuss in detail two recently proposed relations between the Parrondo"s games and the Fokker-Planck equation describing the flashing ratchet as the overdamped motion of a particle in a potential landscape. In both cases it is possible to relate exactly the probabilities of the games to the potential in which the overdamped particle moves. We will discuss under which conditions current-less potentials correspond to fair games and vie versa.

Toral, Raul; Amengual, Pau; Mangioni, Sergio

2003-05-01

329

Fokker-Planck equation for lattice deposition models  

NASA Astrophysics Data System (ADS)

An asymptotically exact Fokker-Planck equation for the height fluctuations of lattice deposition models is derived from a Van Kampen expansion of the master equation. Using an Edwards-Wilkinson-type model as an example, the solution of the equivalent Langevin equation reproduces the surface roughness and lateral height correlations obtained with kinetic Monte Carlo (KMC) simulations. Our discrete equations of motion thereby provide an exact analytic and computational alternative to KMC simulations of these models.

Baggio, Chiara; Vardavas, Raffaele; Vvedensky, Dimitri D.

2001-10-01

330

Herschel-ATLAS: Planck sources in the phase 1 fields  

NASA Astrophysics Data System (ADS)

We present the results of a cross-correlation of the Planck Early Release Compact Source catalogue (ERCSC) with the catalogue of Herschel-ATLAS sources detected in the phase 1 fields, covering 134.55°2. There are 28 ERCSC sources detected by Planck at 857 GHz in this area. As many as 16 of them are probably high Galactic latitude cirrus; 10 additional sources can be clearly identified as bright, low-z galaxies; one further source is resolved by Herschel as two relatively bright sources; and the last is resolved into an unusual condensation of low-flux, probably high-redshift point sources, around a strongly lensed Herschel-ATLAS source at z = 3.26. Our results demonstrate that the higher sensitivity and higher angular resolution H-ATLAS maps provide essential information for the interpretation of candidate sources extracted from Planck sub-mm maps. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA

Herranz, D.; González-Nuevo, J.; Clements, D. L.; De Zotti, G.; Lopez-Caniego, M.; Lapi, A.; Rodighiero, G.; Danese, L.; Fu, H.; Cooray, A.; Baes, M.; Bendo, G. J.; Bonavera, L.; Carrera, F. J.; Dole, H.; Eales, S.; Ivison, R. J.; Jarvis, M.; Lagache, G.; Massardi, M.; Micha?owski, M. J.; Negrello, M.; Rigby, E.; Scott, D.; Valiante, E.; Valtchanov, I.; Van der Werf, P.; Auld, R.; Buttiglione, S.; Dariush, A.; Dunne, L.; Hopwood, R.; Hoyos, C.; Ibar, E.; Maddox, S.

2013-01-01

331

What Planck does not tell us about inflation  

NASA Astrophysics Data System (ADS)

Planck data has not found the “smoking gun” of non-Gaussianity that would have necessitated consideration of inflationary models beyond the simplest canonical single-field scenarios. This raises the important question of what these results do imply for more general models, and in particular, multifield inflation. In this paper we revisit four ways in which two-field scenarios can behave differently from single-field models; two-field slow-roll dynamics, curvaton-type behavior, inflation ending on an inhomogeneous hypersurface and modulated reheating. We study the constraints that Planck data puts on these classes of behavior, focusing on the latter two which are the least studied in the recent literature. We show that these latter classes are almost equivalent, and extend their previous analyses by accounting for arbitrary evolution of the isocurvature mode which, in particular, places important limits on the Gaussian curvature of the reheating hypersurface. In general, however, we find that Planck bispectrum results only constrain certain regions of parameter space, leading us to conclude that inflation sourced by more than one scalar field remains an important possibility.

Elliston, Joseph; Mulryne, David; Tavakol, Reza

2013-09-01

332

Non-Gaussianity and Minkowski functionals: forecasts for Planck  

NASA Astrophysics Data System (ADS)

We study Minkowski functionals as probes of primordial non-Gaussianity in the cosmic microwave background, specifically for the estimate of the primordial `local' bi-spectrum parameter f_{_NL}, with instrumental parameters which should be appropriate for the Planck experiment. We use a maximum likelihood approach, which we couple with various filtering methods and test thoroughly for convergence. We included the effect of inhomogeneous noise as well as astrophysical biases induced by point sources and by the contamination from the Galaxy. We find that when Wiener filtered maps are used (rather than simply smoothed with Gaussian), the expected error on the measurement of f_{_NL} should be as small as ? f_{_NL} ˜eq 10 when combining the three channels at 100, 143 and 217 GHz in the Planck extended mission setup. This result is fairly insensitive to the non-homogeneous nature of the noise, at least for realistic hitmaps expected from Planck. We then estimate the bias induced on the measurement of f_{_NL} by point sources in those three channels. With the appropriate masking of the bright sources, this bias can be reduced to a negligible level in the 100 and 143 GHz channels. It remains significant in the 217 GHz channel, but can be corrected for. The Galactic foreground biases are quite important and present a complex dependence on sky coverage: making them negligible will depend strongly on the quality of the component separation methods.

Ducout, A.; Bouchet, F. R.; Colombi, S.; Pogosyan, D.; Prunet, S.

2013-03-01

333

Derivation of a Fokker-Planck equation for bunched beams  

SciTech Connect

This report investigates the derivation of the Fokker-Planck equation which is commonly used to evaluate the evolution with time of an ensemble of particles under the effect of external rf forces, cooling and forces of stochastic nature like intrabeam scattering. The conventional approach based on the classical work by Chandrasekhar is first exposed, where the phase delay and the momentum error of the particle are used. The method is then extended to the case the distribution function is expressed in terms of the amplitude of motion instead of the original rectilinear variables. The new Fokker-Planck equation is obtained with an averaging process over the phase distribution instead of the time-averaging as it was usually performed earlier, to avoid the appearance of a singularity behavior. The solution of the Fokker-Planck equation is chosen in the proper form which makes easier the evaluation of the beam lifetime in the presence of the separatrix of the rf buckets. Finally the numerical applications apply the Relativistic Heavy Ion Collider (RHIC).

Ruggiero, A.G.

1993-09-27

334

The state of the art of electrostatic discharge protection: physics, technology, circuits, design, simulation and scaling  

Microsoft Academic Search

This paper discusses state of the art electrostatic discharge (ESD) protection in advanced semiconductor technologies and emerging technologies. ESD physics, semiconductor process issues, device and circuit simulation, circuits, and devices are examined

Steven H. Voldman; Essex Junction

1998-01-01

335

The state of the art of electrostatic discharge protection: physics, technology, circuits, design, simulation, and scaling  

Microsoft Academic Search

This paper discusses state-of-the-art electrostatic discharge (ESD) protection in advanced semiconductor technologies and emerging technologies. ESD physics, semiconductor process issues, device and circuit simulation, circuits, and devices are examined

Steven H. Voldman

1999-01-01

336

Effect of finite computational domain on turbulence scaling law in both physical and spectral spaces  

NASA Astrophysics Data System (ADS)

The well-known translation between the power law of the energy spectrum and that of the correlation function or the second order structure function has been widely used in analyzing random data. Here, we show that the translation is valid only in proper scaling regimes. The regimes of valid translation are different for the correlation function and the structure function. Indeed, they do not overlap. Furthermore, in practice, the power laws exist only for a finite range of scales. We show that this finite range makes the translation inexact even in the proper scaling regime. The error depends on the scaling exponent. The current findings are applicable to data analysis in fluid turbulence and other stochastic systems.

Hou, Thomas Y.; Wu, Xiao-Hui; Chen, Shiyi; Zhou, Ye

1998-11-01

337

Dirac(-Pauli), Fokker-Planck equations and exceptional Laguerre polynomials  

SciTech Connect

Research Highlights: > Physical examples involving exceptional orthogonal polynomials. > Exceptional polynomials as deformations of classical orthogonal polynomials. > Exceptional polynomials from Darboux-Crum transformation. - Abstract: An interesting discovery in the last two years in the field of mathematical physics has been the exceptional X{sub l} Laguerre and Jacobi polynomials. Unlike the well-known classical orthogonal polynomials which start with constant terms, these new polynomials have lowest degree l = 1, 2, and ..., and yet they form complete set with respect to some positive-definite measure. While the mathematical properties of these new X{sub l} polynomials deserve further analysis, it is also of interest to see if they play any role in physical systems. In this paper we indicate some physical models in which these new polynomials appear as the main part of the eigenfunctions. The systems we consider include the Dirac equations coupled minimally and non-minimally with some external fields, and the Fokker-Planck equations. The systems presented here have enlarged the number of exactly solvable physical systems known so far.

Ho, Choon-Lin, E-mail: hcl@mail.tku.edu.tw [Department of Physics, Tamkang University, Tamsui 251, Taiwan (China)

2011-04-15

338

Planck constraints on Higgs modulated reheating of renormalization group improved inflation  

NASA Astrophysics Data System (ADS)

Within the framework of renormalization group improved inflationary cosmology motivated by asymptotically safe gravity, we study the dynamics of a scalar field which can be interpreted as the Higgs field. The background trajectories of this model can provide sufficient inflationary e-folds and a graceful exit to a radiation dominated phase. We study the possibility of generating primordial curvature perturbations through the Standard Model Higgs boson. This can be achieved under finely tuned parameter choices by making use of the modulated reheating mechanism. The primordial non-Gaussianity is expected to be sizable in this model. Though tightly constrained by the newly released Planck cosmic microwave background data, this model provides a potentially interesting connection between collider and early Universe physics.

Cai, Yi-Fu; Chang, Yu-Chiao; Chen, Pisin; Easson, Damien A.; Qiu, Taotao

2013-10-01

339

New velocity-space discretization for continuum kinetic calculations and Fokker-Planck collisions  

NASA Astrophysics Data System (ADS)

Numerical techniques for discretization of velocity space in continuum kinetic calculations are described. An efficient spectral collocation method is developed for the speed coordinate - the radius in velocity space - employing a novel set of non-classical orthogonal polynomials. For problems in which Fokker-Planck collisions are included, a common situation in plasma physics, a procedure is detailed to accurately and efficiently treat the field term in the collision operator (in the absence of gyrokinetic corrections). When species with disparate masses are included simultaneously, a careful extrapolation of the Rosenbluth potentials is performed. The techniques are demonstrated in several applications, including neoclassical calculations of the bootstrap current and plasma flows in a tokamak.

Landreman, Matt; Ernst, Darin R.

2013-06-01

340

Multi-Level iterative methods in computational plasma physics  

SciTech Connect

Plasma physics phenomena occur on a wide range of spatial scales and on a wide range of time scales. When attempting to model plasma physics problems numerically the authors are inevitably faced with the need for both fine spatial resolution (fine grids) and implicit time integration methods. Fine grids can tax the efficiency of iterative methods and large time steps can challenge the robustness of iterative methods. To meet these challenges they are developing a hybrid approach where multigrid methods are used as preconditioners to Krylov subspace based iterative methods such as conjugate gradients or GMRES. For nonlinear problems they apply multigrid preconditioning to a matrix-few Newton-GMRES method. Results are presented for application of these multilevel iterative methods to the field solves in implicit moment method PIC, multidimensional nonlinear Fokker-Planck problems, and their initial efforts in particle MHD.

Knoll, D.A.; Barnes, D.C.; Brackbill, J.U.; Chacon, L.; Lapenta, G.

1999-03-01

341

Studies of parallel algorithms for the solution of a Fokker-Planck equation  

SciTech Connect

The study of laser-created plasmas often requires the use of a kinetic model rather than a hydrodynamic one. This model change occurs, for example, in the hot spot formation in an ICF experiment or during the relaxation of colliding plasmas. When the gradients scalelengths or the size of a given system are not small compared to the characteristic mean-free-path, we have to deal with non-equilibrium situations, which can be described by the distribution functions of every species in the system. We present here a numerical method in plane or spherical 1-D geometry, for the solution of a Fokker-Planck equation that describes the evolution of stich functions in the phase space. The size and the time scale of kinetic simulations require the use of Massively Parallel Computers (MPP). We have adopted a message-passing strategy using Parallel Virtual Machine (PVM).

Deck, D. [Los Alamos National Lab., NM (United States); Samba, G. [CEA/CEL-V, Villeneuve St. Georges (France). Dept. de Mathematiques Appliquees

1995-11-01

342

Modeling for cardiac excitation propagation based on the Nernst-Planck equation and homogenization.  

PubMed

The bidomain model is a commonly used mathematical model of the electrical properties of the cardiac muscle that takes into account the anisotropy of both the intracellular and extracellular spaces. However, the equations contain self-contradiction such that the update of ion concentrations does not consider intracellular or extracellular ion movements due to the gradient of electric potential and the membrane charge as capacitive currents in spite of the fact that those currents are taken into account in forming Kirchhoff's first law. To overcome this problem, we start with the Nernst-Planck equation, the ionic conservation law, and the electroneutrality condition at the cellular level, and by introducing a homogenization method and assuming uniformity of variables at the microscopic scale, we derive rational bidomain equations at the macroscopic level. PMID:23848709

Okada, Jun-ichi; Sugiura, Seiryo; Hisada, Toshiaki

2013-06-06

343

Modeling for cardiac excitation propagation based on the Nernst-Planck equation and homogenization  

NASA Astrophysics Data System (ADS)

The bidomain model is a commonly used mathematical model of the electrical properties of the cardiac muscle that takes into account the anisotropy of both the intracellular and extracellular spaces. However, the equations contain self-contradiction such that the update of ion concentrations does not consider intracellular or extracellular ion movements due to the gradient of electric potential and the membrane charge as capacitive currents in spite of the fact that those currents are taken into account in forming Kirchhoff's first law. To overcome this problem, we start with the Nernst-Planck equation, the ionic conservation law, and the electroneutrality condition at the cellular level, and by introducing a homogenization method and assuming uniformity of variables at the microscopic scale, we derive rational bidomain equations at the macroscopic level.

Okada, Jun-ichi; Sugiura, Seiryo; Hisada, Toshiaki

2013-06-01

344

Adolescents' self-efficacy to overcome barriers to Physical Activity Scale.  

PubMed

This paper describes a revised measure of self-efficacy to overcome barriers to moderate and vigorous physical activity in a sample of 484 high school students in Toronto, Ontario. The students had a mean age of 15.3 years. Principal axis factoring with oblique rotation yielded five factors: self-efficacy to overcome internal, harassment, physical environment, social environment, and responsibilities barriers. Two problematic items were removed, which resulted in a 22-item measure. Subsequent analyses were conducted on responses to this shortened measure. Confirmatory factor analysis supported the five-factor model and demonstrated age- and sex-invariance. The subscales had good internal consistency reliability. Structural regressions demonstrated a strong relationship between the resulting factors and a physical activity measure (energy expenditure), showing predictive validity. PMID:23367813

Dwyer, John J M; Chulak, Tala; Maitland, Scott; Allison, Kenneth R; Lysy, Daria C; Faulkner, Guy E J; Sheeshka, Judy

2012-12-01

345

Construction of large-scale simulation codes using ALPAL (A Livermore Physics Applications Language)  

SciTech Connect

A Livermore Physics Applications Language (ALPAL) is a new computer tool that is designed to leverage the abilities and creativity of computational scientist. Some of the ways that ALPAL provides this leverage are: first, it eliminates many sources of errors; second, it permits building code modules with far greater speed than is otherwise possible; third, it provides a means of specifying almost any numerical algorithm; and fourth, it is a language that is close to a journal-style presentation of physics models and numerical methods for solving them. 13 refs., 9 figs.

Cook, G.

1990-10-01

346

Regionalization of meso-scale physically based nitrogen modeling outputs to the macro-scale by the use of regression trees  

NASA Astrophysics Data System (ADS)

In this paper, a method is presented to estimate excess nitrogen on large scales considering single field processes. The approach was implemented by using the physically based model J2000-S to simulate the nitrogen balance as well as the hydrological dynamics within meso-scale test catchments. The model input data, the parameterization, the results and a detailed system understanding were used to generate the regression tree models with GUIDE (Loh, 2002). For each landscape type in the federal state of Thuringia a regression tree was calibrated and validated using the model data and results of excess nitrogen from the test catchments. Hydrological parameters such as precipitation and evapotranspiration were also used to predict excess nitrogen by the regression tree model. Hence they had to be calculated and regionalized as well for the state of Thuringia. Here the model J2000g was used to simulate the water balance on the macro scale. With the regression trees the excess nitrogen was regionalized for each landscape type of Thuringia. The approach allows calculating the potential nitrogen input into the streams of the drainage area. The results show that the applied methodology was able to transfer the detailed model results of the meso-scale catchments to the entire state of Thuringia by low computing time without losing the detailed knowledge from the nitrogen transport modeling. This was validated with modeling results from Fink (2004) in a catchment lying in the regionalization area. The regionalized and modeled excess nitrogen correspond with 94%. The study was conducted within the framework of a project in collaboration with the Thuringian Environmental Ministry, whose overall aim was to assess the effect of agro-environmental measures regarding load reduction in the water bodies of Thuringia to fulfill the requirements of the European Water Framework Directive (Bäse et al., 2007; Fink, 2006; Fink et al., 2007).

Künne, A.; Fink, M.; Kipka, H.; Krause, P.; Flügel, W.-A.

2012-06-01

347

Inquiring Minds Want to Know: Progress Report on SCALE-UP Physics at Penn State Erie  

NASA Astrophysics Data System (ADS)

SCALE-UP (Student Centered Activities for Large Enrollment University Programs) is a ``studio'' approach to learning developed by Bob Beichner at North Carolina State University. SCALE-UP was adapted for teaching and learning in the introductory calculus-based mechanics course at Penn State Erie, The Behrend College, starting in Spring 2007. We are presently doing quantitative and qualitative research on using inquiry-based learning with first year college students, in particular how it effects female students and students from groups that are traditionally under-represented in STEM fields. Using field notes of observations of the classes, focus groups, and the collection of quantitative data, the feedback generated by the research is also being used to improve the delivery of the course, and in the planning of adopting SCALE-UP to the second semester course on electromagnetism in the Fall 2008 semester.

Hall, Jonathan

2008-03-01

348

Rasch calibration of physical activity self-efficacy and social support scale for persons with intellectual disabilities.  

PubMed

The purpose of this study was to investigate the construct validity of the Self-Efficacy/Social Support for Activity for persons with Intellectual Disability (SE/SS-AID) scales developed by Peterson, Peterson, Lowe, & Nothwehr (2009). A total of 146 participants with intellectual disabilities completed 6 self-efficacy (SE) items and 18 social support (SS) items. After applying the Rasch rating model, all SE items and 17 SS items fit the model and measured a single-construct. Thus, it was able to determine the item difficulty and person's level of SE and SS for physical activity by calculated logit scores. No items showed evidence for differential functioning by the level of intellectual disability. Model fit of SS subscales (e.g., staff, family, and peer) showed good-fit as well. In conclusion, SE and SS scales for physical activity can be measured more accurately for persons with intellectual disabilities by using the modified scales validated in this study. PMID:20363109

Lee, Miyoung; Peterson, Jana J; Dixon, Alicia

2010-04-02

349

Subgrid-scale physics under stable atmospheric stratification: the SnoHATS experiment  

NASA Astrophysics Data System (ADS)

Stably stratified atmospheric flows are usually characterized by weak and highly anisotropic turbulence, gravity waves, instabilities, and meandering motions that are not observed in neutral or convective atmospheric flows. These features complicate both modeling and measurements in stable atmospheric boundary layers. However, recent evidence suggests that the large eddy simulation (LES) technique yields better results under stable conditions than classic numerical simulations. Nevetheless, LES results remain quite sensitive to the modeling of the unresolved, subgrid scales of turbulence. To address some of the open questions related to the modeling of these small turbulent scales under stable conditions, the Snow Horizontal Array Turbulence Study (SnoHATS) field experimental campaign- was performed over an extensive glacier in Switzerland from February to April 2006. The snow cover provided stable stratification of the flow over long periods. Two horizontal arrays of vertically separated 3D sonic anemometers were deployed to allow two-dimensional filtering and computation of the full three-dimensional strain rate tensors. Results presented here indicate that the subgrid scales under stable conditions remain an important sink of variance and turbulent kinetic energy from the resolved scales and carry a significant portion of the fluxes when the filter scale is larger than the distance to the wall. Surprisingly, stability was not found to be important in determining the fraction of SGS fluxes (out of the total fluxes). Stress-strain alignment was observed to be similar to the alignment under neutral and unstable conditions and to the alignment in several other canonical flows. The coefficients of the Smagorinsky model vary considerably with stability; this variation of the coefficients for both momentum and heat is shown to be better explained by stability parameters based on the Ozmidov scale, rather than the Obukhov scale. These results indicate that subgrid scale modeling is not drastically affected by atmospheric stability and hence a unified approach is possible. Nevertheless, the presentation concludes with some other challenges for stable ABL simulations that are not encountered in the neutral or unstable ABL.

Bou-Zeid, E.; Higgins, C.; Huwald, H.; Meneveau, C.; Parlange, M. B.

2009-04-01

350

Physical controls on the scale-dependence of ensemble streamflow forecast dispersion  

Microsoft Academic Search

The accuracy of ensemble streamflow forecasts (ESFs) is impacted by the propagation of uncertainty associated with quantitative precipitation forecasts (QPFs) through the physical processes occurring in the basin. In this study, we consider consistent ESFs (i.e., observations and ensemble members are equally likely) and we study the effect of basin area (A) and antecedent rainfall (AR) on the ESF dispersion,

G. Mascaro; E. R. Vivoni; R. Deidda

2010-01-01

351

Large-Scale Simulations in Condensed Matter Physics THE Need for a Teraflop Computer  

Microsoft Academic Search

The introduction of vector processors {``supercomputers'' with a performance in the range of 109 floating point operations (1 GFLOP) per second} has had an enormous impact on computational condensed matter physics. The possibility of a substantially enhanced performance by massively parallel processors (``teraflop'' machines with 1012 floating point operations per second) will allow satisfactory treatment of a large range of

K. Binder

1992-01-01

352

Large-scale De Novo Prediction of Physical Protein-Protein Association*  

PubMed Central

Information about the physical association of proteins is extensively used for studying cellular processes and disease mechanisms. However, complete experimental mapping of the human interactome will remain prohibitively difficult in the near future. Here we present a map of predicted human protein interactions that distinguishes functional association from physical binding. Our network classifies more than 5 million protein pairs predicting 94,009 new interactions with high confidence. We experimentally tested a subset of these predictions using yeast two-hybrid analysis and affinity purification followed by quantitative mass spectrometry. Thus we identified 462 new protein-protein interactions and confirmed the predictive power of the network. These independent experiments address potential issues of circular reasoning and are a distinctive feature of this work. Analysis of the physical interactome unravels subnetworks mediating between different functional and physical subunits of the cell. Finally, we demonstrate the utility of the network for the analysis of molecular mechanisms of complex diseases by applying it to genome-wide association studies of neurodegenerative diseases. This analysis provides new evidence implying TOMM40 as a factor involved in Alzheimer's disease. The network provides a high-quality resource for the analysis of genomic data sets and genetic association studies in particular. Our interactome is available via the hPRINT web server at: www.print-db.org.

Elefsinioti, Antigoni; Sarac, Omer Sinan; Hegele, Anna; Plake, Conrad; Hubner, Nina C.; Poser, Ina; Sarov, Mihail; Hyman, Anthony; Mann, Matthias; Schroeder, Michael; Stelzl, Ulrich; Beyer, Andreas

2011-01-01

353

Toward a Multi-scale, Multi-moment Physics-based Validation Protocol in Computational Simulation  

Microsoft Academic Search

Predictive capability is the Holy Grail of contemporary computational physics. The quantitative comparison between experiments and simulations, i.e., meaningful code validation, remains its Achilles' heel. Although major advances in experimental and computational capabilities have brought simulation science to the threshold of an elevated standard for code validation, this threshold cannot be crossed without an array of tools for quantitatively comparing

J. Kamm; A. Davis; A. Mathews; W. Rider; K. Vixie; D. Sornette; P. Vorobieff

2002-01-01

354

Diagnostics for the laser fusion program--Plasma physics on the scale of microns and picoseconds  

Microsoft Academic Search

Diagnostic techniques are reviewed in the context of insights they provide to physical processes dominating the implosion of laser fusion targets. Specific examples chosen from recent experiments demonstrate that adequate diagnostic techniques, resolved to microns and picoseconds, have been developed for the demanding requirements of laser driven \\

DAVID T. ATTWOOD

1978-01-01

355

Theobroma cacao: A genetically integrated physical map and genome-scale comparative synteny analysis  

Technology Transfer Automated Retrieval System (TEKTRAN)

A comprehensive integrated genomic framework is considered a centerpiece of genomic research. In collaboration with the USDA-ARS (SHRS) and Mars Inc., the Clemson University Genomics Institute (CUGI) has developed a genetically anchored physical map of the T. cacao genome. Three BAC libraries contai...

356

IMPORTANCE OF PHYSICAL SCALING FACTORS TO BENTHIC MARINE INVERTEBRATE RECOLONIZATION OF LABORATORY MICROCOSMS  

EPA Science Inventory

Five laboratory studies of benthic macroinvertebrate recolonization were conducted for 6-wk periods to evaluate the effects of physical factors (i.e., microcosm size, seawater flow rates and sediment depth) on benthic community structure. esign variables included4 open-faced acry...

357

Atomic-Scale Investigation of Latent Fission Tracks in Fluorapatite: Physical Characteristics and Annealing Behavior  

Microsoft Academic Search

A JEOL JEM-2000FX analytical transmission electron microscope, equipped with a cold stage and anticontamination device, has been used to study the physical characteristics and annealing behavior of artificially induced fission tracks in fluorapatite. Near the atomic level, unetched fission tracks are not continuous, but are comprised of segments of extended damage that are separated by gaps of undamaged microstructure. From

Tracy Anne Paul

1993-01-01

358

Cosmic physics  

Microsoft Academic Search

Classical physics is determined by the scale on which matter can be handled in everyday use; quantum physics results from the study of the interaction of matter on this scale with matter on smaller scales; cosmic physics is the study of matter on much greater scales, and there are many properties of matter that are observable and significant only on

W H McCrea

1968-01-01

359

The hospital anxiety and depression scale questionnaire in physical danger and evaluation situations  

Microsoft Academic Search

In this article we analyze the variables of anxiety and depression in two different situations: a combat situation and taking an exam. We used the Hospital Anxiety and Depression Scale questionnaire with a sample of 621 subjects, divided in four groups, two groups of soldiers, one of them in situation of combat (SBH) and the other one on the military

José Soriano; Luis Salavert

1996-01-01

360

Expectations Test: Trauma Scales for Sexual Abuse, Physical Abuse, Exposure to Family Violence, and Posttraumatic Stress  

Microsoft Academic Search

Gully's 2000 Expectations Test was developed as a tool to use with children ages 4 through 17 to measure social information processing. Prior research suggested it could help identify abused and emotionally traumatized children. Results from regression analyses were used to develop four scales that could be calculated simply. Prior research demonstrated excellent interrater reliability for the variables from the

Kevin J. Gully

2003-01-01

361

Neocortical dynamics at multiple scales: EEG standing waves, statistical mechanics, and physical analogs.  

PubMed

The dynamic behavior of scalp potentials (EEG) is apparently due to some combination of global and local processes with important top-down and bottom-up interactions across spatial scales. In treating global mechanisms, we stress the importance of myelinated axon propagation delays and periodic boundary conditions in the cortical-white matter system, which is topologically close to a spherical shell. By contrast, the proposed local mechanisms are multiscale interactions between cortical columns via short-ranged non-myelinated fibers. A mechanical model consisting of a stretched string with attached nonlinear springs demonstrates the general idea. The string produces standing waves analogous to large-scale coherent EEG observed in some brain states. The attached springs are analogous to the smaller (mesoscopic) scale columnar dynamics. Generally, we expect string displacement and EEG at all scales to result from both global and local phenomena. A statistical mechanics of neocortical interactions (SMNI) calculates oscillatory behavior consistent with typical EEG, within columns, between neighboring columns via short-ranged non-myelinated fibers, across cortical regions via myelinated fibers, and also derives a string equation consistent with the global EEG model. PMID:21167841

Ingber, Lester; Nunez, Paul L

2010-12-16

362

Challenges in computational materials science: Multiple scales, multi-physics and evolving discontinuities  

Microsoft Academic Search

Novel experimental possibilities together with improvements in computer hardware as well as new concepts in computational mathematics and mechanics – in particular multiscale methods – are now, in principle, making it possible to derive and compute phenomena and material parameters at a macroscopic level from processes that take place one to several scales below. Because of this quest to analyse

René de Borst

2008-01-01

363

Conceptual and methodological frameworks for large scale and high resolution analysis of the physical flood susceptibility of buildings  

NASA Astrophysics Data System (ADS)

There are some approaches available for assessing flood damage to buildings and critical infrastructure. However, these methods up to now can hardly be adapted to a large scale because of lacking high resolution classification and characterisation approaches for the built structures. To overcome this obstacle, the paper presents, first, a conceptual framework for understanding physical flood susceptibility of buildings; and second, a methodological framework for its analysis. The latter ranges from automatic extraction of buildings mainly from remote sensing with their subsequent classification and characterisation to a systematic physical flood susceptibility assessment. The work shows the results of implementation and testing a respective methodology in a district of the city of Magangué, Magdalena River Colombia.

Blanco-Vogt, A.; Schanze, J.

2013-10-01

364

A Large-Scale Assessment of Introductory Physics Courses: Development of Laboratory Activities  

NASA Astrophysics Data System (ADS)

While there has long been a general consensus among science researchers and educators that practical work is an essential component of teaching science, there is little agreement about the purposes of undergraduate laboratory courses. The aims of these courses are often manifold and confusingly combined. As part of the reform taking place in the undergraduate physics curriculum at Texas Tech University, we aim to develop laboratory activities which promote students' understanding of the nature of measurement and uncertainty, while providing opportunities for students to apply learned concepts to new situations through experiment and observation. Our goal is to construct a laboratory curriculum which reflects science practice, and highlights the nature of science and the process of scientific inquiry. The activities are based on the probabilistic approach to measurement, and a modelling framework for physics teaching and learning. The development of these activities will be discussed; and examples from an introductory calculus-based laboratory course will be presented.

Pillay, Seshini

2010-03-01

365

Physical states and scaling properties of W gravities and W strings  

SciTech Connect

In this paper the authors discuss some physical aspects of W gravities and W strings. The authors identify global characteristics in W gravities (in addition to the usual Euler characteristic) and show how the dependence of the partition function on the various chemical potentials involves these quantities. The authors find the operators which create physical states in W{sub 3} and W{sub 4} gravities and discuss their relationship with screening operators. W strings are discussed in the framework of a natural way of coupling matter to W gravity, and the issues of extra dimensions and critical dimensions are clarified. The authors find a remarkable relationship between pure W gravities and ordinary gravity coupled to c {lt} 1 unitary minimal models.

Das, S.R.; Dhar, A.; Rama, S.K. (Tata Inst. of Fundamental Research, Homi Bhabha Road, Bombay 400 005 (IN))

1992-04-20

366

On the physical and logical topology design of large-scale optical networks  

Microsoft Academic Search

We consider the problem of designing a network of optical cross-connects (OXCs) to provide end-to-end lightpath services to large numbers of label switched routers (LSRs). We present a set of heuristic algorithms to address the combined problem of physical topology design (i.e., determine the number of OXCs required and the fiber links among them) and logical topology design (i.e., determine

Yufeng Xin; George N. Rouskas; Harry G. Perros

2003-01-01

367

Two lowland stream riffles – linkages between physical habitats and macroinvertebrates across multiple spatial scales  

Microsoft Academic Search

The physical structure of two riffles in a lowland Danish stream was studied and its importance for the composition and density\\u000a of the macroinvertebrate communities was evaluated. The two riffles were visually assessed to be very similar, but measurements\\u000a revealed that they differed in overall hydraulic conditions, stability, substratum composition and consolidation. Differences\\u000a affected abundance of both burrowing and surface

Morten Lauge Pedersen; Nikolai Friberg

2007-01-01

368

A Physical-Experimental Model for Small-Scale Basaltic Vulcanian Eruptions  

Microsoft Academic Search

In the last period of its summer 2001 flank activity Mt. Etna produced ash explosions not common at this basaltic volcano. The explosions took place at a new vent at 2550 m.a.s.l. and followed Strombolian and effusive activity. At first the ash erupted as a continuous, pulsing plume a few km high, occasionally undergoing small-scale, partial collapses. Afterward the frequency

P. Scarlato; J. Taddeucci; O. Spieler; B. Kennedy; D. B. Dingwell; M. Pompilio

2003-01-01

369

Architectural Exploration of Chip-Scale Photonic Interconnection Network Designs Using Physical-Layer Analysis  

Microsoft Academic Search

Chip-scale photonic interconnection networks have emerged as a promising technology solution that can address many of the scalability challenges facing the communication networks in next-generation high-performance multicore processors. Photonic interconnects can offer significantly higher bandwidth density, lower latencies, and better energy efficiency. Even though photonics exhibits these inherent advantages over electronics, the network designs that can successfully leverage these benefits

Johnnie Chan; Gilbert Hendry; Aleksandr Biberman; Keren Bergman

2010-01-01

370

Grad-Fokker-Planck plasma equations. I - Collision moments  

NASA Astrophysics Data System (ADS)

Following the method first developed by Grad (1969) for neutral gases, 13 moments are taken of the collision term in the Boltzmann-Fokker-Planck equation for a multispecies, multitemperature, hot plasma. An evaluation is made of the collision integrals for each colliding pair. These integrals yield, in particular, the rate of exchange of momentum and energy produced by collisions. It is pointed out that the set of integrals may be combined with moments of the remaining terms in the Boltzmann equation to give 13 moment equations for each species of particle. To complete the calculation, extensive use is made of the symbolic computer language REDUCE.

Broughan, K. A.

1982-06-01

371

On the higher order corrections to the Fokker Planck equation  

NASA Astrophysics Data System (ADS)

The Rayleigh model of nonlinear Brownian motion is revisited in which the heavy particle of mass M interacts with ideal gas molecules of mass m?M via instantaneous collisions. Using the van Kampen method of expansion of the master equation, nonlinear corrections to the Fokker Planck equation are obtained up to sixth order in the small parameter ?=m/M, improving earlier results. The role and origin of non-Gaussian statistics of the random force in the corresponding Langevin equation are also discussed.

Plyukhin, A. V.

2005-06-01

372

Monochromatic, Rosseland mean, and Planck mean opacity routine  

NASA Astrophysics Data System (ADS)

Several FORTRAN77 codes were developed to compute frequency-dependent, Rosseland and Planck mean opacities of gas and dust in protoplanetary disks. The opacities can be computed for an ensemble of dust grains having various compositions (ices, silicates, organics, etc), sizes, topologies (homogeneous/composite aggregates, homogeneous/layered/composite spheres, etc.), porosities, and dust-to-gas ratio. Several examples are available. In addition, a very fast opacity routine to be used in modeling of the radiative transfer in hydro simulations of disks is available upon request (10^8 routine calls require about 30s on Pentium 4 3.0GHz).

Semenov, D.

2006-11-01

373

Planck spectroscopy and quantum noise of microwave beam splitters.  

PubMed

We use a correlation function analysis of the field quadratures to characterize both the blackbody radiation emitted by a 50 ? load resistor and the quantum properties of two types of beam splitters in the microwave regime. To this end, we first study vacuum fluctuations as a function of frequency in a Planck spectroscopy experiment and then measure the covariance matrix of weak thermal states. Our results provide direct experimental evidence that vacuum fluctuations represent the fundamental minimum quantum noise added by a beam splitter to any given input signal. PMID:21230774

Mariantoni, M; Menzel, E P; Deppe, F; Araque Caballero, M A; Baust, A; Niemczyk, T; Hoffmann, E; Solano, E; Marx, A; Gross, R

2010-09-20

374

Integrating Delta Building Physics & Economics: Optimizing the Scale of Engineered Avulsions in the Mississippi River Delta  

NASA Astrophysics Data System (ADS)

Land loss in the Mississippi River Delta caused by subsidence and erosion has resulted in habitat loss, interference with human activities, and increased exposure of New Orleans and other settled areas to storm surge risks. Prior to dam and levee building and oil and gas production in the 20th century, the long term rates of land building roughly balanced land loss through subsidence. Now, however, sediment is being deposited at dramatically lower rates in shallow areas in and adjacent to the Delta, with much of the remaining sediment borne by the Mississippi being lost to the deep areas of the Gulf of Mexico. A few projects have been built in order to divert sediment from the river to areas where land can be built, and many more are under consideration as part of State of Louisiana and Federal planning processes. Most are small scale, although there have been some proposals for large engineered avulsions that would divert a significant fraction of the remaining available sediment (W. Kim, et al. 2009, EOS). However, there is debate over whether small or large diversions are the economically optimally and socially most acceptable size of such land building projects. From an economic point of view, the optimal size involves tradeoffs between scale economies in civil work construction, the relationship between depth of diversion and sediment concentration in river water, effects on navigation, and possible diminishing returns to land building at a single location as the edge of built land progresses into deeper waters. Because land building efforts could potentially involve billions of dollars of investment, it is important to gain as much benefit as possible from those expenditures. We present the result of a general analysis of scale economies in land building from engineered avulsions. The analysis addresses the question: how many projects of what size should be built at what time in order to maximize the amount of land built by a particular time? The analysis integrates three models: 1. coarse sediment diversion as a function of the width, depth, and timing of water diversions (using our field measurements of sediment concentration as a function of depth), 2. land building as a function of the location, water, and amount of sediment diverted, accounting for bathymetry, subsidence, and other factors, and 3. cost of building and operating the necessary civil works. Our statistical analysis of past diversions indicates existence of scale economies in width and scale of diseconomies in depth. The analysis explores general relationships between size, cost, and land building, and does not consider specific actual project proposals or locations. Sensitivity to assumptions about fine sediment capture, accumulation rates for organic material, and other inputs will be discussed.

Kenney, M. A.; Mohrig, D.; Hobbs, B. F.; Parker, G.

2011-12-01

375

The psychometric properties of the center for epidemiological studies-depression scale (ces-d) when used with adults with physical disabilities  

Microsoft Academic Search

Psychometric properties of the Center for Epidemiological Studies Depression Scale (CES-D) were examined in a sample of 790 adults with physical disabilities and compared to the responses obtained from non-disabled samples (Craig and Van Natta, 1976; Radloff, 1977). Findings suggested the CES-D is a valid measure of depressive symptoms among adults with physical disabilities. Scores on the CES-D scale were

Catherine P. Coyle; James J. Roberge

1992-01-01

376

Particle Physics in the Sky and Astrophysics Underground: Connecting the Universe's Largest and Smallest Scales  

NASA Astrophysics Data System (ADS)

Particles have tremendous potential as astronomical messengers, and conversely, studying the universe as a whole also teaches us about particle physics. This thesis encompasses both of these research directions. Many models predict a diffuse flux of high energy neutrinos from active galactic nuclei and other astrophysical sources. The "Astrophysics Underground" portion of this thesis describes a search for this neutrino flux performed by looking for very high energy upward-going muons using the Super-K detector. In addition to using particles to do astronomy, we can also use the universe itself as a particle physics lab. The "Particle Physics in the Sky" portion of this thesis focuses on extracting cosmological information from galaxy surveys. To overcome technical challenges faced by the latest galaxy surveys, we produced a comprehensive upgrade to mangle, a software package that processes the angular masks defining the survey area on the sky. We added dramatically faster algorithms and new useful features that are necessary for managing complex masks of current and next-generation galaxy surveys. With this software in hand, we utilized SDSS data to investigate the relation between galaxies and dark matter by studying relative bias, i.e., the relation between different types of galaxies. Separating galaxies by their luminosities and colors reveals a complicated picture: red galaxies are clustered more strongly than blue galaxies, with both the brightest and the faintest red galaxies showing the strongest clustering. Furthermore, red and blue galaxies tend to occupy different regions of space. In order to make precise measurements from the next generation of galaxy surveys, it will be essential to account for this complexity.

Swanson, Molly E. C.

2008-08-01

377

Primordial History of Vesta: Time Scale of Accretion and Physical Properties of the Proto-Core  

NASA Astrophysics Data System (ADS)

The importance of studying Vesta is linked to the presence of a differentiated internal structure, inferred by the spectral connection with HED meteorites (Keil et al.2002, Scott 2007, De Sanctis et al.2012). We simulate several scenarios of thermal and structural evolution of Vesta by using the thermal code we developed. By varying the delay-parameter ?td in the injection of 26Al in Vesta and the initial concentration of metallic and silicate components of the asteroid, we explore the primordial thermal history of Vesta and in particular we search for information about the physical properties of the proto-core.

Formisano, M.; Turrini, D.; Federico, C.; Capaccioni, F.

2012-09-01

378

Planck early results. IV. First assessment of the High Frequency Instrument in-flight performance  

NASA Astrophysics Data System (ADS)

The Planck High Frequency Instrument (HFI) is designed to measure the temperature and polarization anisotropies of the cosmic microwave background and Galactic foregrounds in six ~30% bands centered at 100, 143, 217, 353, 545, and 857 GHz at an angular resolution of 10' (100 GHz), 7' (143 GHz), and 5' (217 GHz and higher). HFI has been operating flawlessly since launch on 14 May 2009, with the bolometers reaching 100 mK the first week of July. The settings of the readout electronics, including bolometer bias currents, that optimize HFI's noise performance on orbit are nearly the same as the ones chosen during ground testing. Observations of Mars, Jupiter, and Saturn have confirmed that the optical beams and the time responses of the detection chains are in good agreement with the predictions of physical optics modeling and pre-launch measurements. The Detectors suffer from a high flux of cosmic rays due to historically low levels of solar activity. As a result of the redundancy of Planck's observation strategy, theremoval of a few percent of data contaminated by glitches does not significantly affect the instrumental sensitivity. The cosmic ray flux represents a significant and variable heat load on the sub-Kelvin stage. Temporal variation and the inhomogeneous distribution of the flux results in thermal fluctuations that are a probable source of low frequency noise. The removal of systematic effects in the time ordered data provides a signal with an average noise equivalent power that is 70% of the goal in the 0.6-2.5 Hz range. This is slightly higher than was achieved during the pre-launch characterization but better than predicted in the early phases of the project. The improvement over the goal is a result of the low level of instrumental background loading achieved by the optical and thermal design of the HFI. Corresponding author: J.-M. Lamarre, jean-michel.lamarre@obspm.fr

Planck HFI Core Team; Ade, P. A. R.; Aghanim, N.; Ansari, R.; Arnaud, M.; Ashdown, M.; Aumont, J.; Banday, A. J.; Bartelmann, M.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoît, A.; Bernard, J.-P.; Bersanelli, M.; Bhatia, R.; Bock, J. J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bradshaw, T.; Bréelle, E.; Bucher, M.; Camus, P.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Charra, J.; Charra, M.; Chary, R.-R.; Chiang, C.; Church, S.; Clements, D. L.; Colombi, S.; Couchot, F.; Coulais, A.; Cressiot, C.; Crill, B. P.; Crook, M.; de Bernardis, P.; Delabrouille, J.; Delouis, J.-M.; Désert, F.-X.; Dolag, K.; Dole, H.; Doré, O.; Douspis, M.; Efstathiou, G.; Eng, P.; Filliard, C.; Forni, O.; Fosalba, P.; Fourmond, J.-J.; Ganga, K.; Giard, M.; Girard, D.; Giraud-Héraud, Y.; Gispert, R.; Górski, K. M.; Gratton, S.; Griffin, M.; Guyot, G.; Haissinski, J.; Harrison, D.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Hildebrandt, S. R.; Hills, R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Huffenberger, K. M.; Jaffe, A. H.; Jones, W. C.; Kaplan, J.; Kneissl, R.; Knox, L.; Lagache, G.; Lamarre, J.-M.; Lami, P.; Lange, A. E.; Lasenby, A.; Lavabre, A.; Lawrence, C. R.; Leriche, B.; Leroy, C.; Longval, Y.; Macías-Pérez, J. F.; Maciaszek, T.; MacTavish, C. J.; Maffei, B.; Mandolesi, N.; Mann, R.; Mansoux, B.; Masi, S.; Matsumura, T.; McGehee, P.; Melin, J.-B.; Mercier, C.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Mortlock, D.; Murphy, A.; Nati, F.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; North, C.; Noviello, F.; Novikov, D.; Osborne, S.; Paine, C.; Pajot, F.; Patanchon, G.; Peacocke, T.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Piacentini, F.; Piat, M.; Plaszczynski, S.; Pointecouteau, E.; Pons, R.; Ponthieu, N.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Reach, W. T.; Renault, C.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rowan-Robinson, M.; Rusholme, B.; Santos, D.; Savini, G.; Schaefer, B. M.; Shellard, P.; Spencer, L.; Starck, J.-L.; Stassi, P.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sygnet, J.-F.; Tauber, J. A.; Thum, C.; Torre, J.-P.; Touze, F.; Tristram, M.; van Leeuwen, F.; Vibert, L.; Vibert, D.; Wade, L. A.; Wandelt, B. D.; White, S. D. M.; Wiesemeyer, H.; Woodcraft, A.; Yurchenko, V.; Yvon, D.; Zacchei, A.

2011-12-01

379

Physics on the smallest scales: an introduction to minimal length phenomenology  

NASA Astrophysics Data System (ADS)

Many modern theories which try to unify gravity with the Standard Model of particle physics, such as e.g. string theory, propose two key modifications to the commonly known physical theories: the existence of additional space dimensions; the existence of a minimal length distance or maximal resolution. While extra dimensions have received a wide coverage in publications over the last ten years (especially due to the prediction of micro black hole production at the Large Hadron Collider), the phenomenology of models with a minimal length is still less investigated. In a summer study project for bachelor students in 2010, we have explored some phenomenological implications of the potential existence of a minimal length. In this paper, we review the idea and formalism of a quantum gravity-induced minimal length in the generalized uncertainty principle framework as well as in the coherent state approach to non-commutative geometry. These approaches are effective models which can make model-independent predictions for experiments and are ideally suited for phenomenological studies. Pedagogical examples are provided to grasp the effects of a quantum gravity-induced minimal length. This paper is intended for graduate students and non-specialists interested in quantum gravity.

Sprenger, Martin; Nicolini, Piero; Bleicher, Marcus

2012-07-01

380

Scalings between Physical and their Observationally Related Quantities of Merger Remnants  

NASA Astrophysics Data System (ADS)

We present scaling relations between the virial velocity (V) and the one-dimensional central velocity dispersion (?0); the gravitational radius (Rv) and the effective radius (Re); and the total mass (M) and the luminous mass (ML) found in N-body simulations of binary mergers of spiral galaxies. These scalings are of the form V2 ? ?0?, Rv ? Re? and M? ML?. The particlar values obtained for {?,?,?} depend on the method of fitting used [ordinary least-squares (OLS) or orthogonal distance regression (ODR)], the assumed profile [de Vaucouleurs (deV) or Sérsic (S)], and the size of the radial interval where the fit is done. The ? and ? indexes turn out more sensitive to the fitting procedure, resulting for the OLS in a mean < ? >ols = 1.51% and < ? >ols= 0.69, while for the ODR < ? >odr=2.35 and < ? >odr=0.76. The ? index depends more on the adopted type of profile, with < ? >deV=0.13 and < ? >S=0.27. We conclude that dissipationless formed remnants of mergers have a strong breaking of structural and kinematical homology.

Aceves, H.; Velázquez, H.

2005-10-01

381

1/12-scale physical modeling experiments in support of tank 241-SY- 101 hydrogen mitigation  

SciTech Connect

Hanford tank 241-SY-101 is a 75-ft-dia double-shell tank that contains approximately 1.1 M gal of radioactive fuel reprocessing waste. Core samples have shown that the tank contents are separated into two main layers, a article laden supernatant liquid at the top of the tank and a more dense slurry on the bottom. Two additional layers may be present, one being a potentially thick sludge lying beneath the slurry at the bottom of the tank and the other being the crust that has formed on the surface of the supernatant liquid. The supernatant is more commonly referred to as the convective layer and the slurry as the non-convective layer. Accumulation of gas (partly hydrogen) in the non-convective layer is suspected to be the key mechanism behind the gas burp phenomena, and several mitigation schemes are being developed to encourage a more uniform gas release rate (Benegas 1992). To support the full-scale hydraulic mitigation test, scaled experiments were performed to satisfy two objectives: 1. provide an experimental database for numerical- model validation; 2. establish operating parameter values required to mobilize the settled solids and maintain the solids in suspension.

Fort, J.A.; Bamberger, J.A.; Bates, J.M.; Enderlin, C.W.; Elmore, M.R.

1993-01-01

382

Low-scale SUSY breaking and the (s)goldstino physics  

NASA Astrophysics Data System (ADS)

For a 4D N=1 supersymmetric model with a low SUSY breaking scale (f) and general Kahler potential K(?i,?j†) and superpotential W(?i) we study, in an effective theory approach, the relation of the goldstino superfield to the (Ferrara-Zumino) superconformal symmetry breaking chiral superfield X. In the presence of more sources of supersymmetry breaking, we verify the conjecture that the goldstino superfield is the (infrared) limit of X for zero-momentum and ??? (? is the effective cut-off scale). We then study the constraint X2=0, which in the one-field case is known to decouple a massive sgoldstino and thus provide an effective superfield description of the Akulov-Volkov action for the goldstino. In the presence of additional fields that contribute to SUSY breaking we identify conditions for which X2=0 remains valid, in the effective theory below a large but finite sgoldstino mass. The conditions ensure that the effective expansion (in 1/?) of the initial Lagrangian is not in conflict with the decoupling limit of the sgoldstino (1/m˜?/f, f

Antoniadis, I.; Ghilencea, D. M.

2013-05-01

383

Dependence and physical exercise: Spanish validation of the Exercise Dependence Scale-Revised (EDS-R).  

PubMed

The purpose of this study was to validate the Spanish version of the Exercise Dependence Scale-Revised (EDS-R). To achieve this goal, a sample of 531 sport center users was used and the psychometric properties of the EDS-R were examined through different analyses. The results supported both the first-order seven-factor model and the higher-order model (seven first-order factors and one second-order factor). The structure of both models was invariant across age. Correlations among the subscales indicated a related factor model, supporting construct validity of the scale. Alpha values over .70 (except for Reduction in Other Activities) and suitable levels of temporal stability were obtained. Users practicing more than three days per week had higher scores in all subscales than the group practicing with a frequency of three days or fewer. The findings of this study provided reliability and validity for the EDS-R in a Spanish context. PMID:21568198

Sicilia, Alvaro; González-Cutre, David

2011-05-01

384

MEASURING THE REDSHIFT DEPENDENCE OF THE COSMIC MICROWAVE BACKGROUND MONOPOLE TEMPERATURE WITH PLANCK DATA  

SciTech Connect

We study the capability of Planck data to constrain deviations of the cosmic microwave background (CMB) blackbody temperature from adiabatic evolution using the thermal Sunyaev-Zeldovich anisotropy induced by clusters of galaxies. We consider two types of data sets depending on how the cosmological signal is removed: using a CMB template or using the 217 GHz map. We apply two different statistical estimators, based on the ratio of temperature anisotropies at two different frequencies and on a fit to the spectral variation of the cluster signal with frequency. The ratio method is biased if CMB residuals with amplitude {approx}1 {mu}K or larger are present in the data, while residuals are not so critical for the fit method. To test for systematics, we construct a template from clusters drawn from a hydro-simulation included in the pre-launch Planck Sky Model. We demonstrate that, using a proprietary catalog of X-ray-selected clusters with measured redshifts, electron densities, and X-ray temperatures, we can constrain deviations of adiabatic evolution, measured by the parameter {alpha} in the redshift scaling T(z) = T{sub 0}(1 + z){sup 1-{alpha}}, with an accuracy of {sigma}{sub {alpha}} = 0.011 in the most optimal case and with {sigma}{sub {alpha}} = 0.018 for a less optimal case. These results represent a factor of 2-3 improvement over similar measurements carried out using quasar spectral lines and a factor 6-20 with respect to earlier results using smaller cluster samples.

De Martino, I.; Atrio-Barandela, F. [Fisica Teorica, Universidad de Salamanca, E-37008 Salamanca (Spain); Da Silva, A.; Martins, C. J. A. P. [Centro de Astrofisica da Universidade do Porto, Rua das Estrelas s/n, 4150-762 Porto (Portugal); Ebeling, H. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Kashlinsky, A. [SSAI and Observational Cosmology Laboratory, Code 665, Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kocevski, D., E-mail: ivan.demartino@usal.es, E-mail: atrio@usal.es, E-mail: asilva@astro.up.pt, E-mail: Carlos.Martins@astro.up.pt, E-mail: ebeling@ifa.hawaii.edu, E-mail: alexander.kashlinsky@nasa.gov, E-mail: kocevski@physics.ucdavis.edu [Department of Physics, University of California at Davis, 1 Shields Avenue, Davis, CA 95616 (United States)

2012-10-01

385

A Fokker-Planck based kinetic model for diatomic rarefied gas flows  

NASA Astrophysics Data System (ADS)

A Fokker-Planck based kinetic model is presented here, which also accounts for internal energy modes characteristic for diatomic gas molecules. The model is based on a Fokker-Planck approximation of the Boltzmann equation for monatomic molecules, whereas phenomenological principles were employed for the derivation. It is shown that the model honors the equipartition theorem in equilibrium and fulfills the Landau-Teller relaxation equations for internal degrees of freedom. The objective behind this approximate kinetic model is accuracy at reasonably low computational cost. This can be achieved due to the fact that the resulting stochastic differential equations are continuous in time; therefore, no collisions between the simulated particles have to be calculated. Besides, because of the devised energy conserving time integration scheme, it is not required to resolve the collisional scales, i.e., the mean collision time and the mean free path of molecules. This, of course, gives rise to much more efficient simulations with respect to other particle methods, especially the conventional direct simulation Monte Carlo (DSMC), for small and moderate Knudsen numbers. To examine the new approach, first the computational cost of the model was compared with respect to DSMC, where significant speed up could be obtained for small Knudsen numbers. Second, the structure of a high Mach shock (in nitrogen) was studied, and the good performance of the model for such out of equilibrium conditions could be demonstrated. At last, a hypersonic flow of nitrogen over a wedge was studied, where good agreement with respect to DSMC (with level to level transition model) for vibrational and translational temperatures is shown.

Gorji, M. Hossein; Jenny, Patrick

2013-06-01

386

A state estimation method with matching between a physical energy quantity and a decibel scaled noisy observation for a sound environmental system  

Microsoft Academic Search

A state estimation method for an energy stochastic system with a decibel observation mechanism is presented. The problem is to get a decibel-valued estimate of an energy state variable by using the decibel-valued noisy observation data, where the stochastic system of concern is physically driven on energy scale. The main attention is paid to matching between the physical energy principle

E. Uchino; M. Ohta; K. Hatakeyama

1992-01-01

387

Linear analysis of the momentum cooling Fokker-Planck equation  

SciTech Connect

In order to optimize the extraction scheme used to take antiprotons out of the accumulator, it is necessary to understand the basic processes involved. At present, six antiproton bunches per Tevatron store are removed sequentially by RF unstacking from the accumulator. The phase space dynamics of this process, with its accompanying phase displacement deceleration and phase space dilution of portions of the stack, can be modelled by numerical solution of the longitudinal equations of motion for a large number of particles. We have employed the tracking code ESME for this purpose. In between RF extractions, however, the stochastic cooling system is turned on for a short time, and we must take into account the effect of momentum stochastic cooling on the antiproton energy spectrum. This process is described by the Fokker-Planck equation, which models the evolution of the antiproton stack energy distribution by accounting for the cooling through an applied coherent drag force and the competing heating of the stack due to diffusion, which can arise from intra-beam scattering, amplifier noise and coherent (Schottky) effects. In this note we examine the aspects of the Fokker-Planck in the regime where the nonlinear terms due to Schottky effects are small. This discussion ultimately leads to solution of the equation in terms of an orthonormal set of functions which are closely related to the quantum simple-harmonic oscillator wave-functions. 5 refs.

Rosenzweig, J.B.

1989-05-04

388

Max Planck Institute for the History of Science  

NSDL National Science Digital Library

Based in Berlin, the Max Planck Institute for the History of Science (MPIWG) was established in 1994 as a research institute administered by the Max Planck Society. The researchers at the MPIWG ask questions that include "How did the fundamental scientific concepts (e.g. number, force, heredity, probability and practices (e.g. experiment, proof, classification) develop in specific historical contexts?" The materials on this site are divided into five primary sections, which include Resources, Staff, and Research. Visitors should click on over to the Resources area to get started with their exploration of the site. Here they will find resources that include Cuneiform Digital Library Initiative and the wonderful Machine Drawings 1200-1650 archive. This particular archive contains over 1,800 machine drawings that record the history of technical innovation and ingenuity. In the Research area, visitors will find information about ongoing investigations in fields that like Ideals and Practices of Rationality, Experimental Systems and Spaces of Knowledge, and Art and Knowledge in Pre-Modern Europe. The site is rounded out by the Staff area where interested parties can learn about scholars in residence at the Institute.

389

From Continuum Fokker-Planck Models to Discrete Kinetic Models  

PubMed Central

Two theoretical formalisms are widely used in modeling mechanochemical systems such as protein motors: continuum Fokker-Planck models and discrete kinetic models. Both have advantages and disadvantages. Here we present a “finite volume” procedure to solve Fokker-Planck equations. The procedure relates the continuum equations to a discrete mechanochemical kinetic model while retaining many of the features of the continuum formulation. The resulting numerical algorithm is a generalization of the algorithm developed previously by Fricks, Wang, and Elston through relaxing the local linearization approximation of the potential functions, and a more accurate treatment of chemical transitions. The new algorithm dramatically reduces the number of numerical cells required for a prescribed accuracy. The kinetic models constructed in this fashion retain some features of the continuum potentials, so that the algorithm provides a systematic and consistent treatment of mechanical-chemical responses such as load-velocity relations, which are difficult to capture with a priori kinetic models. Several numerical examples are given to illustrate the performance of the method.

Xing, Jianhua; Wang, Hongyun; Oster, George

2005-01-01

390

Cryogenic characterization of the Planck sorption cooler system flight model  

NASA Astrophysics Data System (ADS)

Two continuous closed-cycle hydrogen Joule-Thomson (J-T) sorption coolers have been fabricated and assembled by the Jet Propulsion Laboratory (JPL) for the European Space Agency (ESA) Planck mission. Each refrigerator has been designed to provide a total of ~ 1W of cooling power at two instrument interfaces: they directly cool the Planck Low Frequency Instrument (LFI) around 20K while providing a pre-cooling stage for a 4 K J-T mechanical refrigerator for the High Frequency Instrument (HFI). After sub-system level validation at JPL, the cryocoolers have been delivered to ESA in 2005. In this paper we present the results of the cryogenic qualification and test campaigns of the Nominal Unit on the flight model spacecraft performed at the CSL (Centre Spatial de Liège) facilities in 2008. Test results in terms of input power, cooling power, temperature, and temperature fluctuations over the flight allowable ranges for these interfaces are reported and analyzed with respect to mission requirements.

Morgante, G.; Pearson, D.; Melot, F.; Stassi, P.; Terenzi, L.; Wilson, P.; Hernandez, B.; Wade, L.; Gregorio, A.; Bersanelli, M.; Butler, C.; Mandolesi, N.

2009-12-01

391

The Qweak Experiment -- A search for new physics at the TeV Scale  

SciTech Connect

A new precision measurement of the parity violating analyzing power in longitudinally polarized electron scattering from the proton at very low Q^2 at an incident energy of 1.16 GeV is in the final stages of preparation for execution at Jefferson Laboratory (JLab). A 2200 hour measurement of the parity violating asymmetry in elastic electron-proton scattering at Q^2 = 0.03 (GeV/c)^2 employing 180 microamp of 85% polarized beam on a 0.35 m long liquid hydrogen target will determine the weak charge of the proton, Q_w = 1 - 4sin^2(theta_W), with 4% combined statistical and systematic errors. The Standard Model makes a firm prediction of Q_w, based on the `running' of the weak mixing angle sin^2(theta_W) from the Z-pole down to lower energies. Any significant deviation of sin^2(theta_W) from its Standard Model prediction at low Q^2 would constitute a signal of new physics. In the absence of new physics, the envisaged experiment will provide a 0.3% determination of sin^2(theta_W), making this a very competitive measurement of the weak mixing angle. Complementary to the present experiment is a measurement of the weak charge of the electron in parity violating Moller scattering at 11 GeV, currently under consideration, with the upgraded CEBAF at JLab. The objective of that experiment would be a measurement of sin2(theta_W) with a precision comparable to or better than any individual measurement at the Z-pole.

Willem T. H. van Oers

2007-08-21

392

An integrated framework for multi-scale multi-physics numerical modelling of interface evolution in welding  

NASA Astrophysics Data System (ADS)

The project Modelling of Interface evolution in advanced Welding (MIntWeld) is a 4-year international research project funded by the European Commission under their FP7 programme. Its main target is to develop a numerical toolbox which can be used to predict the evolution of interfaces during welding. There are various interfaces involving multiple phenomena and different spatial scales, which can be simulated using corresponding numerical modelling methods respectively. The modelling methods include quantum dynamics, molecular dynamics, phase field, phase field crystal, computational fluid dynamics, phase transformation and heat transfer, thermodynamics, continuum mechanics and life and defects prediction. Although each modelling method is based on different physical theories and involves different scales, they are not isolated. Therefore, this project aims to design a common framework which couples each model with the upstream and/or downstream model at the relevant neighbouring length scales. The data exchange framework which underpins the coupling of the models is described, and typical examples addressing the solution to the challenges faced, such as those of data interpolation between one discretisation of the computational domain and another, are discussed. Initial successes from the model-linking efforts of the authors are also presented.

Tong, M.; Liu, J.; Xie, Yu; Dong, H. B.; Davidchack, R. L.; Dantzig, J.; Ceresoli, D.; Marzari, N.; Cocks, A.; Zhao, C.; Richardson, I.; Kidess, A.; Kleijn, C.; Hoglund, L.; Wen, S. W.; Barnett, R.; Browne, D. J.

2012-07-01

393

Scale-free flow of life: on the biology, economics, and physics of the cell.  

PubMed

The present work is intended to demonstrate that most of the paradoxes, controversies, and contradictions accumulated in molecular and cell biology over many years of research can be readily resolved if the cell and living systems in general are re-interpreted within an alternative paradigm of biological organization that is based on the concepts and empirical laws of nonequilibrium thermodynamics. In addition to resolving paradoxes and controversies, the proposed re-conceptualization of the cell and biological organization reveals hitherto unappreciated connections among many seemingly disparate phenomena and observations, and provides new and powerful insights into the universal principles governing the emergence and organizational dynamics of living systems on each and every scale of biological organizational hierarchy, from proteins and cells to economies and ecologies. PMID:19416527

Kurakin, Alexei

2009-05-05

394

Detection of hidden structures for arbitrary scales in complex physical systems  

PubMed Central

Recent decades have experienced the discovery of numerous complex materials. At the root of the complexity underlying many of these materials lies a large number of contending atomic- and largerscale configurations. In order to obtain a more detailed understanding of such systems, we need tools that enable the detection of pertinent structures on all spatial and temporal scales. Towards this end, we suggest a new method that applies to both static and dynamic systems which invokes ideas from network analysis and information theory. Our approach efficiently identifies basic unit cells, topological defects, and candidate natural structures. The method is particularly useful where a clear definition of order is lacking, and the identified features may constitute a natural point of departure for further analysis.

Ronhovde, P.; Chakrabarty, S.; Hu, D.; Sahu, M.; Sahu, K. K.; Kelton, K. F.; Mauro, N. A.; Nussinov, Z.

2012-01-01

395

Scale-free flow of life: on the biology, economics, and physics of the cell  

PubMed Central

The present work is intended to demonstrate that most of the paradoxes, controversies, and contradictions accumulated in molecular and cell biology over many years of research can be readily resolved if the cell and living systems in general are re-interpreted within an alternative paradigm of biological organization that is based on the concepts and empirical laws of nonequilibrium thermodynamics. In addition to resolving paradoxes and controversies, the proposed re-conceptualization of the cell and biological organization reveals hitherto unappreciated connections among many seemingly disparate phenomena and observations, and provides new and powerful insights into the universal principles governing the emergence and organizational dynamics of living systems on each and every scale of biological organizational hierarchy, from proteins and cells to economies and ecologies.

Kurakin, Alexei

2009-01-01

396

Solutions of the Rice-Allnatt Equation for Two Choices of the Fokker-Planck Operator.  

National Technical Information Service (NTIS)

The Fokker-Planck operator that occurs naturally in the derivation of the Rice-Allnatt (RA) singlet kinetic equation is not the one actually used in the original solution of the RA equation. A simpler Fokker-Planck operator, being characterized by a const...

H. T. Davis M. O. Baleiko

1969-01-01

397

Max Planck Institute for Human Development and Education: Annual Report 1990.  

ERIC Educational Resources Information Center

The Max Planck Institute for Human Development and Education in Germany consists of four research centers dealing with the following topics: sociology and the study of the life course; development and socialization; psychology and human development; and school systems and instruction. This English-language annual report of the Planck Institute,…

Max-Planck-Institut fuer Bildungsforschung, Berlin (West Germany).

398

Max Planck Institute for Human Development and Education: Annual Report 1990.  

ERIC Educational Resources Information Center

|The Max Planck Institute for Human Development and Education in Germany consists of four research centers dealing with the following topics: sociology and the study of the life course; development and socialization; psychology and human development; and school systems and instruction. This English-language annual report of the Planck Institute,…

Max-Planck-Institut fuer Bildungsforschung, Berlin (West Germany).

399

Derivation of quantum mechanics from the Boltzmann equation for the Planck aether  

NASA Astrophysics Data System (ADS)

The Planck aether hypothesis assumes that space is densely filled with an equal number of locally interacting positive and negative Planck masses obeying an exactly nonrelativistic law of motion. The Planck masses can be described by a quantum mechanical two-component nonrelativistic operator field equation having the form of a two-component nonlinear Schrödinger equation, with a spectrum of quasiparticles obeying Lorentz invariance as a dynamic symmetry for energies small compared to the Planck energy. We show that quantum mechanics itself can be derived from the Newtonian mechanics of the Planck aether as an approximate solution of Boltzmann's equation for the locally interacting positive and negative Planck masses, and that the validity of the nonrelativistic Schrödinger equation depends on Lorentz invariance as a dynamic symmetry. We also show how the many-body Schrödinger wave function can be factorized into a product of quasiparticles of the Planck aether with separable quantum potentials. Finally, we present a possible explanation of wave function collapse as a kind of enhanced gravitational collapse in the presence of the negative Planck masses.

Winterberg, F.

1995-10-01

400

Planck early results. XV. Spectral energy distributions and radio continuum spectra of northern extragalactic radio sources  

Microsoft Academic Search

Spectral energy distributions (SEDs) and radio continuum spectra are presented for a northern sample of 104 extragalactic radio sources, based on the Planck Early Release Compact Source Catalogue (ERCSC) and simultaneous multifrequency data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous observations ranging from radio to gamma-rays. This is the first extensive

J. Aatrokoski; P. A. R. Ade; N. Aghanim; H. D. Aller; M. F. Aller; E. Angelakis; M. Arnaud; M. Ashdown; J. Aumont; C. Baccigalupi; A. Balbi; A. J. Banday; R. B. Barreiro; J. G. Bartlett; E. Battaner; K. Benabed; A. Benoît; A. Berdyugin; J.-P. Bernard; M. Bersanelli; R. Bhatia; A. Bonaldi; L. Bonavera; J. R. Bond; J. Borrill; M. Bucher; C. Burigana; D. N. Burrows; P. Cabella; M. Capalbi; B. Cappellini; J.-F. Cardoso; A. Catalano; E. Cavazzuti; L. Cayón; A. Challinor; A. Chamballu; R.-R. Chary; L.-Y. Chiang; P. R. Christensen; D. L. Clements; S. Colafrancesco; S. Colombi; F. Couchot; A. Coulais; S. Cutini; F. Cuttaia; L. Danese; R. D. Davies; R. J. Davis; P. de Bernardis; G. de Gasperis; A. de Rosa; G. de Zotti; J. Delabrouille; J.-M. Delouis; C. Dickinson; H. Dole; S. Donzelli; O. Doré; U. Dörl; M. Douspis; X. Dupac; G. Efstathiou; T. A. Enßlin; F. Finelli; O. Forni; M. Frailis; E. Franceschi; L. Fuhrmann; S. Galeotta; K. Ganga; F. Gargano; D. Gasparrini; N. Gehrels; M. Giard; G. Giardino; N. Giglietto; P. Giommi; F. Giordano; Y. Giraud-Héraud; J. González-Nuevo; K. M. Górski; S. Gratton; A. Gregorio; A. Gruppuso; D. Harrison; S. Henrot-Versillé; D. Herranz; S. R. Hildebrandt; E. Hivon; M. Hobson; W. A. Holmes; W. Hovest; R. J. Hoyland; K. M. Huffenberger; A. H. Jaffe; M. Juvela; E. Keihänen; R. Keskitalo; O. King; T. S. Kisner; R. Kneissl; L. Knox; T. P. Krichbaum; H. Kurki-Suonio; G. Lagache; A. Lähteenmäki; J.-M. Lamarre; A. Lasenby; R. J. Laureijs; N. Lavonen; C. R. Lawrence; S. Leach; R. Leonardi; J. León-Tavares; M. Linden-Vørnle; E. Lindfors; M. López-Caniego; P. M. Lubin; J. F. Macías-Pérez; B. Maffei; D. Maino; N. Mandolesi; R. Mann; M. Maris; E. Martínez-González; S. Masi; M. Massardi; S. Matarrese; F. Matthai; W. Max-Moerbeck; M. N. Mazziotta; P. Mazzotta; A. Melchiorri; L. Mendes; A. Mennella; P. F. Michelson; M. Mingaliev; S. Mitra; M.-A. Miville-Deschênes; A. Moneti; C. Monte; L. Montier; G. Morgante; D. Mortlock; D. Munshi; A. Murphy; P. Naselsky; P. Natoli; I. Nestoras; C. B. Netterfield; E. Nieppola; K. Nilsson; H. U. Nørgaard-Nielsen; F. Noviello; D. Novikov; I. Novikov; I. J. O'Dwyer; S. Osborne; F. Pajot; B. Partridge; F. Pasian; G. Patanchon; V. Pavlidou; T. J. Pearson; O. Perdereau; L. Perotto; M. Perri; F. Perrotta; F. Piacentini; M. Piat; S. Plaszczynski; P. Platania; E. Pointecouteau; G. Polenta; N. Ponthieu; T. Poutanen; G. Prézeau; P. Procopio; S. Prunet; J.-L. Puget; J. P. Rachen; S. Rainò; W. T. Reach; A. Readhead; R. Rebolo; R. Reeves; M. Reinecke; R. Reinthal; C. Renault; S. Ricciardi; J. Richards; T. Riller; D. Riquelme; I. Ristorcelli; G. Rocha; C. Rosset; M. Rowan-Robinson; J. A. Rubiño-Martín; B. Rusholme; J. Saarinen; M. Sandri; P. Savolainen; D. Scott; M. D. Seiffert; A. Sillanpää; G. F. Smoot; Y. Sotnikova; J.-L. Starck; M. Stevenson; F. Stivoli; V. Stolyarov; R. Sudiwala; J.-F. Sygnet; L. Takalo; J. A. Tauber; L. Terenzi; D. J. Thompson; L. Toffolatti; M. Tornikoski; J.-P. Torre; G. Tosti; A. Tramacere; M. Tristram; J. Tuovinen; M. Türler; M. Turunen; G. Umana; H. Ungerechts; L. Valenziano; E. Valtaoja; J. Varis; F. Verrecchia; P. Vielva; F. Villa; N. Vittorio; B. D. Wandelt; J. Wu; D. Yvon; A. Zacchei; J. A. Zensus; X. Zhou; A. Zonca

2011-01-01

401

Darboux transformations for (1+2)-dimensional Fokker-Planck equations with constant diffusion matrix  

SciTech Connect

We construct a Darboux transformation for (1+2)-dimensional Fokker-Planck equations with constant diffusion matrix. Our transformation is based on the two-dimensional supersymmetry formalism for the Schroedinger equation. The transformed Fokker-Planck equation and its solutions are obtained in explicit form.

Schulze-Halberg, Axel [Department of Mathematics and Actuarial Science, Indiana University Northwest, 3400 Broadway, Gary, Indiana 46408 (United States)

2012-10-15

402

Change and Hope in Physics  

NASA Astrophysics Data System (ADS)

Physics = Ideas + Analyses. Newton reconciled Kepler's laws, Einstein's GR reconciled action at a distance. Our Planck Scale Statistics (see v3 and v4 of [1]) is a change that reconciles gravity with quantum physics simply. It does what a change should do and I will answer your questions again. It completes TOE, so what? There should not be any fear about disappearance of challenges. It will create other challenges to occupy creative physicists meaningfully. Physicists score highest on GRE score with the exception of mechanical engineers. They will come up with ideas applicable to other sectors like energy and economy. Newton, also a gold mine executive, introduced annuity for life, an insurance feature of social security. Here, I try one bold suggestion to illustrate the point. Putting 10% tax on new housing permits would raise the price of each house in the USA by an average of 2 x 10^4 dollars generating a wealth of 2x10^12 dollars for existing 10^8 houses, encouraging people to stick to their houses, inviting investors to grab existing houses, discouraging new construction which goes against the sale of existing houses, and injecting two trillion dollars in the economy without creating a deficit budget. The hope is that this change would challenge other high GRE scorers to come up with additional ideas. It is imaginative minds that solve problems, not subjective knowledge. [1] http://www.arXiv.org/pdf/physics/0210040.

Goradia, Shantilal

2009-05-01

403

A tomographic physical phantom of the newborn child with real-time dosimetry. II. Scaling factors for calculation of mean organ dose in pediatric radiography  

SciTech Connect

Following the recent completion of a tomographic physical newborn dosimetry phantom with incorporated metal-oxide-semiconductor field effect transistor (MOSFET) dosimetry system, it was necessary to derive scaling factors in order to calculate organ doses in the physical phantom given point dose measurements via the MOSFET dosimeters (preceding article in this issue). In this study, we present the initial development of scaling factors using projection radiograph data. These point-to-organ dose scaling factors (SF{sub POD}) were calculated using a computational phantom created from the same data set as the physical phantom, but which also includes numerous segmented internal organs and tissues. The creation of these scaling factors is discussed, as well as the errors associated when using only point dose measurements to calculate mean organ doses and effective doses in physical phantoms. Scaling factors for various organs ranged from as low as 0.70 to as high as 1.71. Also, the ability to incorporate improvements in the computational phantom into the physical phantom using scaling factors is discussed. An comprehensive set of SF{sub POD} values is presented in this article for application in pediatric radiography of newborn patients.

Staton, Robert J.; Jones, A. Kyle; Lee, Choonik; Hintenlang, David E.; Arreola, Manuel M.; Williams, Jonathon L.; Bolch, Wesley E. [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, Florida 32611-8300 (United States); Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, Florida 32611-8300 and Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611-6131 (United States); Department of Radiology, University of Florida, Gainesville, Florida 32611-0374 (United States); Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, Florida 32611-8300 and Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611-6131 (United States)

2006-09-15

404

Three-dimensional flow patterns in a scaled, physical vocal fold model with a unilateral polyp  

NASA Astrophysics Data System (ADS)

Trauma to the vocal folds often causes the formation of polyps; affecting the efficiency of speech and making voice rough and breathy. The change in flow characteristics due to a unilateral polyp positioned on the medial surface of a 7.5 times life-size physical vocal fold model was investigated. Previously reported phase-averaged intraglottal particle image velocimetry (PIV) investigations in a coronal plane indicated significant variations in the flow behavior on different anterior offset planes relative to the polyp. Flow three-dimensionality was investigated by resolving the temporal evolution of the flow with laser Doppler velocimetry (LDV). Data were acquired superior to the glottal exit. Physiological values of Reynolds, Strouhal, and Euler numbers were matched. Results were compared to velocity fields generated by healthy vocal fold motion. The glottal jet trajectory, flow separation points, and the velocity distribution along the vocal fold walls were influenced. Thus, a polyp significantly disturbs and modifies the airflow through the vocal folds, which has implications on both the fluid-structure energy exchange and the sound production.

Seawright, Angela; Erath, Byron; Plesniak, Michael

2009-11-01

405

Bridging Lattice-Scale Physics and Continuum Field Theory with Quantum Monte Carlo Simulations  

NASA Astrophysics Data System (ADS)

We discuss designer Hamiltonians—lattice models tailored to be free from sign problems (“de-signed”) when simulated with quantum Monte Carlo (QMC) methods but which still host complex many-body states and quantum phase transitions of interest in condensed matter physics. We focus on quantum spin systems in which competing interactions lead to nonmagnetic ground states. These states and the associated quantum phase transitions can be studied in great detail, enabling direct access to universal properties and connections with low-energy effective quantum field theories. As specific examples, we discuss the transition from a Néel antiferromagnet to either a uniform quantum paramagnet or a spontaneously symmetry-broken valence-bond solid (VBS) in SU(2) and SU(N) invariant spin models. We also discuss anisotropic (XXZ) systems harboring topological Z2 spin liquids and the XY* transition. We briefly review recent progress on QMC algorithms, including ground-state projection in the valence-bond basis and direct computation of the Renyi variants of the entanglement entropy.

Kaul, Ribhu K.; Melko, Roger G.; Sandvik, Anders W.

2013-04-01

406

A Physically-based Model For Rainfall-triggered Landslides At A Regional Scale  

NASA Astrophysics Data System (ADS)

Rainfall has long been recognized as a major cause of landslides. Historical records have shown that large rainfall can generate hundreds of landslides over hundreds of square kilometers. Although a great body of work has documented the morphology and mechanics of individual slope failure, few studies have considered the process at basin and regional scale. A landslide model is integrated in the landscape evolution model CHILD and simulates rainfall-triggered events based on a geotechnical index, the factor of safety, which takes into account the slope, the soil effective cohesion and weight, the friction angle, the regolith thickness and the saturated thickness. The stat- urated thickness is represented by the wetness index developed in the TOPMODEL. The topography is represented by a Triangulated Irregular Network (TIN). The factor of safety is computed at each node of the TIN. If the factor of safety is lower than 1, a landslide is intiated at this node. The regolith is then moved downstream. We applied the model to the Fortore basin whose valley cuts the flysch terrain that constitute the framework of the so called "sub-Apennines" chain that is the most eastern part of the Southern Apennines (Italy). We will discuss its value according to its sensitivity to the used parameters and compare it to the actual data available for this basin.

Teles, V.; Capolongo, D.; Bras, R. L.

407

Towards a virtual lung: multi-scale, multi-physics modelling of the pulmonary system  

PubMed Central

The essential function of the lung, gas exchange, is dependent on adequate matching of ventilation and perfusion, where air and blood are delivered through complex branching systems exposed to regionally varying transpulmonary and transmural pressures. Structure and function in the lung are intimately related, yet computational models in pulmonary physiology usually simplify or neglect structure. The geometries of the airway and vascular systems and their interaction with parenchymal tissue have an important bearing on regional distributions of air and blood, and therefore on whole lung gas exchange, but this has not yet been addressed by modelling studies. Models for gas exchange have typically incorporated considerable detail at the level of chemical reactions, with little thought for the influence of structure. To date, relatively little attention has been paid to modelling at the cellular or subcellular level in the lung, or to linking information from the protein structure/interaction and cellular levels to the operation of the whole lung. We review previous work in developing anatomically based models of the lung, airways, parenchyma and pulmonary vasculature, and some functional studies in which these models have been used. Models for gas exchange at several spatial scales are briefly reviewed, and the challenges and benefits from modelling cellular function in the lung are discussed.

Burrowes, K.S; Swan, A.J; Warren, N.J; Tawhai, M.H

2008-01-01

408

Towards a virtual lung: multi-scale, multi-physics modelling of the pulmonary system.  

PubMed

The essential function of the lung, gas exchange, is dependent on adequate matching of ventilation and perfusion, where air and blood are delivered through complex branching systems exposed to regionally varying transpulmonary and transmural pressures. Structure and function in the lung are intimately related, yet computational models in pulmonary physiology usually simplify or neglect structure. The geometries of the airway and vascular systems and their interaction with parenchymal tissue have an important bearing on regional distributions of air and blood, and therefore on whole lung gas exchange, but this has not yet been addressed by modelling studies. Models for gas exchange have typically incorporated considerable detail at the level of chemical reactions, with little thought for the influence of structure. To date, relatively little attention has been paid to modelling at the cellular or subcellular level in the lung, or to linking information from the protein structure/interaction and cellular levels to the operation of the whole lung. We review previous work in developing anatomically based models of the lung, airways, parenchyma and pulmonary vasculature, and some functional studies in which these models have been used. Models for gas exchange at several spatial scales are briefly reviewed, and the challenges and benefits from modelling cellular function in the lung are discussed. PMID:18593661

Burrowes, K S; Swan, A J; Warren, N J; Tawhai, M H

2008-09-28

409

Probing for the Cosmological Parameters with Planck Measurement  

NASA Astrophysics Data System (ADS)

In this paper we investigate the constraints on the cosmological parameters, especially the equation of state of dynamical dark energy wDE, the inflationary parameters ns, ?s and r, the total neutrino mass ? m? and the curvature of the universe ?K, using the simulated data of future Planck measurement. First, we determine the cosmological parameters with the current observations, including ESSENCE (192 samples), Three-Year WMAP (WMAP3), Boomerang-2K2, CBI, VSA, ACBAR, SDSS LRG and 2dFGRS, and then we take the best-fit model as the fiducial model in the ensuing simulations. In the simulations we pay particular attention to the effects of the dynamical dark energy in the determination of the cosmological parameters. For this reason, in order to make our constraints more robust, we have added the simulated SNAP data to our simulations. Using the present data, we find that the Quintom dark energy model is mildly favored, while the ?CDM model remains a good fit. In the framework of the dynamical dark energy model, the constraints on the inflationary parameters, ? m? and ?K, become weak, compared with the constraints in the ?CDM model. Intriguingly, we find that the inflationary models with a "blue" tilt, which are excluded about 2? in the ?CDM model, are well within the 2? region with the presence of the dynamics of dark energy. The upper limits of neutrino mass are weakened by a factor of 2 (95% CL) — say, ? m? < 1.59 eV and ? m? < 1.53 eV for two forms of parametrization of the equation of state of dark energy. The flat universe is a good fit to the current data, namely |?K| < 0.03 (95% CL). With the simulated Planck and SNAP data, the dynamical dark energy model and the ?CDM model might be distinguished at the 4? confidence level. And the uncertainties of the inflationary parameters, ? m? and ?K, can be reduced significantly in the framework of the dynamical dark energy model. We also constrain the rotation angle ??, denoting the possible CPT violation, from the simulated Planck and CMBpol data and find that our results are much more stringent than the current constraint and will be used to verify the CPT symmetry with a higher precision.

Xia, Jun-Qing; Li, Hong; Zhao, Gong-Bo; Zhang, Xinmin

410

Scale anomaly as the origin of time  

NASA Astrophysics Data System (ADS)

We explore the problem of time in quantum gravity in a point-particle analogue model of scale-invariant gravity. If quantized after reduction to true degrees of freedom, it leads to a time-independent Schrödinger equation. As with the Wheeler-DeWitt equation, time disappears, and a frozen formalism that gives a static wavefunction on the space of possible shapes of the system is obtained. However, if one follows the Dirac procedure and quantizes by imposing constraints, the potential that ensures scale invariance gives rise to a conformal anomaly, and the scale invariance is broken. A behaviour closely analogous to renormalization-group (RG) flow results. The wavefunction acquires a dependence on the scale parameter of the RG flow. We interpret this as time evolution and obtain a novel solution of the problem of time in quantum gravity. We apply the general procedure to the three-body problem, showing how to fix a natural initial value condition, introducing the notion of complexity. We recover a time-dependent Schrödinger equation with a repulsive cosmological force in the `late-time' physics and we analyse the role of the scale invariant Planck constant. We suggest that several mechanisms presented in this model could be exploited in more general contexts.

Barbour, Julian; Lostaglio, Matteo; Mercati, Flavio

2013-05-01

411

Comparison between the abuse assessment screen and the revised conflict tactics scales for measuring physical violence during pregnancy  

PubMed Central

Study objective: Because of the promise of its ability to quickly identify cases of violence against women during pregnancy, the abuse assessment screen (AAS) should be the focus of numerous psychometric evaluations. This paper assesses its measurement accuracy compared with the revised conflict tactics scales (CTS2) used as standard. Design: Cross sectional study. Besides several ancillary questions, the AAS consists of three anchor questions about violence against pregnant women. These are inclusive, respectively covering lifetime, preceding 12 months, and pregnancy periods. These questions are the main focus of this article. The CTS2 physical aggression scale consists of 12 items divided into minor and severe subscales. A positive event is defined as having at least one positive item in the respective subscale. The 12 item score is also used. Setting and participants: The instruments were applied to 748 women, 24 to 72 hours after delivery in three major public sector maternity wards of Rio de Janeiro from March to September 2000. Main results: According to the CTS2, prevalences of minor and severe physical violence perpetrated against a pregnant woman are 18.4% (95% CI 15.7 to 21.4) and 7.6% (95% CI 5.8 to 9.8), respectively. Taking these subscales as standards, sensitivities are 31.9% (95% CI 24.9 to 40.3) and 61.4% (95% CI 47.6 to 74.0), respectively. Specificities are above 97%. Conclusion: These findings are somewhat worrying because the number of victims who are not identified and offered assistance is considerable. On a practical note, it would be sensible not to use the AAS as a stand alone screening tool until more evidence is gathered.

Reichenheim, M; Moraes, C

2004-01-01

412

Harmonic generation beyond the Strong-Field Approximation: the physics behind the short-wave-infrared scaling laws.  

PubMed

The physics of laser-mater interactions beyond the perturbative limit configures the field of extreme non-linear optics. Although most experiments have been done in the near infrared ( lambda physical grounds, provide a theoretical framework beyond the standard approximations and develop a compact approach that accounts for the correct scaling of the harmonic yield. PMID:19506639

Pérez-Hernández, J A; Roso, L; Plaja, L

2009-06-01

413

Max Planck Institute for the Studies of Societies  

NSDL National Science Digital Library

The Max Planck Institutes are some of the most well-respected academic research institutes in the world, and their Institute for the Study of Societies "builds a bridge between theory and policy by conducting basic research on the self-organization and governance of modern societies". Coordinating their research efforts with several other well-known institutes (such as the Center for European Studies at Harvard University), theprimary objective of the Institutes is to develop an empirically based theory of the governance of advanced industrial societies as they are immersed in the processes of economic globalization and internationalization. Full details of their work are available on the site, but academics and other interested parties will want to take a look at both their discussion papers and working papers, which are made available here as well.

414

Conservative differencing of the electron Fokker-Planck transport equation  

SciTech Connect

We need to extend the applicability and improve the accuracy of kinetic electron transport codes. In this paper, special attention is given to modelling of e-e collisions, including the dominant contributions arising from anisotropy. The electric field and spatial gradient terms are also considered. I construct finite-difference analogues to the Fokker-Planck integral-differential collision operator, which conserve the particle number, momentum and energy integrals (sums) regardless of the coarseness of the velocity zoning. Such properties are usually desirable, but are especially useful, for example, when there are spatial regions and/or time intervals in which the plasma is cool, so that the collision operator acts rapidly and the velocity distribution is poorly resolved, yet it is crucial that gross conservation properties be respected in hydro-transport applications, such as in the LASNEX code. Some points are raised concerning spatial differencing and time integration.

Langdon, A.B.

1981-01-12

415

Improved Fokker-Planck Equation for Resonance-Line Scattering  

NASA Astrophysics Data System (ADS)

A new Fokker-Planck equation is developed for treating resonance-line scattering, which is especially relevant to the treatment of Ly? in the early universe. It is a ``corrected'' form of the equation of Rybicki & Dell'Antonio that now obeys detailed balance, so the approach to thermal equilibrium is properly described. The new equation takes into account the energy changes due to scattering off moving particles, the recoil term of Basko, and stimulated scattering. One result is a surprising unification of the equation for resonance-line scattering and the Kompaneets equation. An improved energy exchange formula due to resonance-line scattering is derived. This formula is compared to previous formulas of Madau and coworkers and Chen & Miralda-Escudé.

Rybicki, George B.

2006-08-01

416

The Planck-LFI flight model ortho-mode transducers  

NASA Astrophysics Data System (ADS)

The Low Frequency Instrument (LFI) of the ESA Planck CMB mission is an array of 22 ultra sensitive pseudocorrelation radiometers working at 30, 44, and 70 GHz. LFI has been calibrated and delivered for integration with the satellite to the European Space Agency on November 2006. The aim of Planck is to measure the anisotropy and polarization of the Cosmic Background Radiation with a sensitivity and angular resolution never reached before over the full sky. LFI is intrinsically sensitive to polarization thanks to the use of Ortho-Mode Transducers (OMT) located between the feedhorns and the pseudo-correlation radiometers. The OMTs are microwave passive components that divide the incoming radiation into two linear orthogonal components. A set of 11 OMTs (2 at 30 GHz, 3 at 44 GHz, and 6 at 70 GHz) were produced and tested. This work describes the design, development and performance of the eleven Flight Model OMTs of LFI. The final design was reached after several years of development. At first, Elegant Bread Board OMTs were produced to investigate the manufacturing technology and design requirements. Then, a set of 3 Qualification Model (QM) OMTs were designed, manufactured and tested in order to freeze the design and the manufacturing technology for the flight units. Finally, the Flight Models were produced and tested. It is shown that all the OMT units have been accepted for flight and the electromagnetic performance is at least marginally compliant with the requirements. Mechanically, the units passed all the thermoelastic qualification tests after a reworking necessary after the QM campaign.

D'Arcangelo, O.; Simonetto, A.; Figini, L.; Pagana, E.; Villa, F.; Pecora, M.; Battaglia, P.; Bersanelli, M.; Butler, R. C.; Garavaglia, S.; Guzzi, P.; Mandolesi, N.; Sozzi, C.

2009-12-01

417

A Study of Trait Anhedonia in Non-Clinical Chinese Samples: Evidence from the Chapman Scales for Physical and Social Anhedonia  

PubMed Central

Background Recent studies suggest that anhedonia, an inability to experience pleasure, can be measured as an enduring trait in non-clinical samples. In order to examine trait anhedonia in a non-clinical sample, we examined the properties of a range of widely used questionnaires capturing anhedonia. Methods 887 young adults were recruited from colleges. All of them were administered a set of checklists, including Chapman Scale for Social Anhedonia (CRSAS) and the Chapman Scale for Physical Anhedonia Scale (CPAS), The Temporal Experience of Pleasure Scale(TEPS), and The Schizotypal Personality Questionnaire (SPQ). Results Males showed significantly higher level of physical (F?=?5.09, p<0.001) and social (F?=?4.38, p<0.005) anhedonia than females. As expected, indiv