Asymptotically scale-invariant occupancy of phase space makes the entropy Sq extensive
Tsallis, Constantino; Gell-Mann, Murray; Sato, Yuzuru
2005-01-01
Phase space can be constructed for N equal and distinguishable subsystems that could be probabilistically either weakly correlated or strongly correlated. If they are locally correlated, we expect the Boltzmann-Gibbs entropy SBG ≡ -k Σi pi ln pi to be extensive, i.e., SBG(N) ∝ N for N → ∞. In particular, if they are independent, SBG is strictly additive, i.e., SBG(N) = NSBG(1), ∀N. However, if the subsystems are globally correlated, we expect, for a vast class of systems, the entropy Sq ≡ k[1 - Σi pqi]/(q - 1) (with S1 = SBG) for some special value of q ≠ 1 to be the one which is extensive [i.e., Sq(N) ∝ N for N → ∞]. Another concept which is relevant is strict or asymptotic scale-freedom (or scale-invariance), defined as the situation for which all marginal probabilities of the N-system coincide or asymptotically approach (for N → ∞) the joint probabilities of the (N - 1)-system. If each subsystem is a binary one, scale-freedom is guaranteed by what we hereafter refer to as the Leibnitz rule, i.e., the sum of two successive joint probabilities of the N-system coincides or asymptotically approaches the corresponding joint probability of the (N - 1)-system. The kinds of interplay of these various concepts are illustrated in several examples. One of them justifies the title of this paper. We conjecture that these mechanisms are deeply related to the very frequent emergence, in natural and artificial complex systems, of scale-free structures and to their connections with nonextensive statistical mechanics. Summarizing, we have shown that, for asymptotically scale-invariant systems, it is Sq with q ≠ 1, and not SBG, the entropy which matches standard, clausius-like, prescriptions of classical thermodynamics. PMID:16230624
Generalized scale invariant theories
NASA Astrophysics Data System (ADS)
Padilla, Antonio; Stefanyszyn, David; Tsoukalas, Minas
2014-03-01
We present the most general actions of a single scalar field and two scalar fields coupled to gravity, consistent with second-order field equations in four dimensions, possessing local scale invariance. We apply two different methods to arrive at our results. One method, Ricci gauging, was known to the literature and we find this to produce the same result for the case of one scalar field as a more efficient method presented here. However, we also find our more efficient method to be much more general when we consider two scalar fields. Locally scale invariant actions are also presented for theories with more than two scalar fields coupled to gravity and we explain how one could construct the most general actions for any number of scalar fields. Our generalized scale invariant actions have obvious applications to early Universe cosmology and include, for example, the Bezrukov-Shaposhnikov action as a subset.
Quadratic Generalized Scale Invariance
NASA Astrophysics Data System (ADS)
Lovejoy, S.; Schertzer, D.; Addor, J. B.
Nearly twenty years ago, two of us argued that in order to account for the scaling strat- ification of the atmosphere, that an anisotropic "unified scaling model" of the atmo- sphere was required with elliptical dimension 23/9=2.555... "in between" the standard 3-D (small scale) and 2-D large scale model. This model was based on the formal- ism of generalized scale invariance (GSI). Physically, GSI is justified by arguing that various conserved fluxes (energy, buoyancy force variance etc.) should define the ap- propriate notion of scale. In a recent large scale satellite cloud image analysis, we directly confirmed this model by studying the isotropic (angle averaged) horizontal cloud statistics. Mathematically, GSI is based on a a group of scale changing opera- tors and their generators but to date, both analyses (primarily of cloud images) and nu- merical (multifractal) simulations, have been limited to the special case of linear GSI. This has shown that cloud texture can plausibly be associated with local linearizations. However realistic morphologies involve spatially avarying textures; the full non linear GSI is clearly necessary. In this talk, we first show that the observed angle averaged (multi)scaling statistics only give a realtively weak constraint on the nonlinear gner- ator: that the latter can be expressed by self-similar (isotropic) part, and a deviatoric part described (in two dimensions) by an arbitrary scalar potential which contains all the information about the cloud morphology. We then show (using a theorem due to Poincaré) how to reduce nonlinear GSI to linear GSI plus a nonlinear coordinate trans- formation numerically, using this to take multifractal GSI modelling to the next level of approximation: quadratic GSI. We show many examples of the coresponding simu- lations which include transitions from various morphologies (including cyclones) and we discuss the results in relation to satellite cloud images.
Scale invariance vs conformal invariance
NASA Astrophysics Data System (ADS)
Nakayama, Yu
2015-03-01
In this review article, we discuss the distinction and possible equivalence between scale invariance and conformal invariance in relativistic quantum field theories. Under some technical assumptions, we can prove that scale invariant quantum field theories in d = 2 space-time dimensions necessarily possess the enhanced conformal symmetry. The use of the conformal symmetry is well appreciated in the literature, but the fact that all the scale invariant phenomena in d = 2 space-time dimensions enjoy the conformal property relies on the deep structure of the renormalization group. The outstanding question is whether this feature is specific to d = 2 space-time dimensions or it holds in higher dimensions, too. As of January 2014, our consensus is that there is no known example of scale invariant but non-conformal field theories in d = 4 space-time dimensions under the assumptions of (1) unitarity, (2) Poincaré invariance (causality), (3) discrete spectrum in scaling dimensions, (4) existence of scale current and (5) unbroken scale invariance in the vacuum. We have a perturbative proof of the enhancement of conformal invariance from scale invariance based on the higher dimensional analogue of Zamolodchikov's c-theorem, but the non-perturbative proof is yet to come. As a reference we have tried to collect as many interesting examples of scale invariance in relativistic quantum field theories as possible in this article. We give a complementary holographic argument based on the energy-condition of the gravitational system and the space-time diffeomorphism in order to support the claim of the symmetry enhancement. We believe that the possible enhancement of conformal invariance from scale invariance reveals the sublime nature of the renormalization group and space-time with holography. This review is based on a lecture note on scale invariance vs conformal invariance, on which the author gave lectures at Taiwan Central University for the 5th Taiwan School on Strings and
Emerging universe from scale invariance
Del Campo, Sergio; Herrera, Ramón; Guendelman, Eduardo I.; Labraña, Pedro E-mail: guendel@bgu.ac.il E-mail: plabrana@ubiobio.cl
2010-06-01
We consider a scale invariant model which includes a R{sup 2} term in action and show that a stable ''emerging universe'' scenario is possible. The model belongs to the general class of theories, where an integration measure independent of the metric is introduced. To implement scale invariance (S.I.), a dilaton field is introduced. The integration of the equations of motion associated with the new measure gives rise to the spontaneous symmetry breaking (S.S.B) of S.I. After S.S.B. of S.I. in the model with the R{sup 2} term (and first order formalism applied), it is found that a non trivial potential for the dilaton is generated. The dynamics of the scalar field becomes non linear and these non linearities are instrumental in the stability of some of the emerging universe solutions, which exists for a parameter range of the theory.
Shift and Scale Invariant Preprocessor.
1981-12-01
1982 THESIS D V SHIFT AND SCALE INVARIANT ?PREPROCESSOR by Norman E. Huston, Jr. December 1981 0 Thesis Advisor: L. A. Wilson Approved for public...SCHOOL December 1981 Author: - . 4 ,/ A pp ro0ved by: rYY. ( Thesis Advisor Co-Ad isor Chairman, De artment of 4n n eing Dean of Science and...large range of problems/disciplines. Fields where it is particularly common include optical imagery, acoustic signal processing , radiology, radio
Scale invariance in road networks
NASA Astrophysics Data System (ADS)
Kalapala, Vamsi; Sanwalani, Vishal; Clauset, Aaron; Moore, Cristopher
2006-02-01
We study the topological and geographic structure of the national road networks of the United States, England, and Denmark. By transforming these networks into their dual representation, where roads are vertices and an edge connects two vertices if the corresponding roads ever intersect, we show that they exhibit both topological and geographic scale invariance. That is, we show that for sufficiently large geographic areas, the dual degree distribution follows a power law with exponent 2.2⩽α⩽2.4 , and that journeys, regardless of their length, have a largely identical structure. To explain these properties, we introduce and analyze a simple fractal model of road placement that reproduces the observed structure, and suggests a testable connection between the scaling exponent α and the fractal dimensions governing the placement of roads and intersections.
Scale-invariant growth processes in expanding space
NASA Astrophysics Data System (ADS)
Ali, Adnan; Ball, Robin C.; Grosskinsky, Stefan; Somfai, Ellák
2013-02-01
Many growth processes lead to intriguing stochastic patterns and complex fractal structures which exhibit local scale invariance properties. Such structures can often be described effectively by space-time trajectories of interacting particles, and their large scale behavior depends on the overall growth geometry. We establish an exact relation between statistical properties of structures in uniformly expanding and fixed geometries, which preserves the local scale invariance and is independent of other properties such as the dimensionality. This relation generalizes standard conformal transformations as the natural symmetry of self-affine growth processes. We illustrate our main result numerically for various structures of coalescing Lévy flights and fractional Brownian motions, including also branching and finite particle sizes. One of the main benefits of this approach is a full, explicit description of the asymptotic statistics in expanding domains, which are often nontrivial and random due to amplification of initial fluctuations.
Interacting scale invariant but nonconformal field theories
NASA Astrophysics Data System (ADS)
Nakayama, Yu
2017-03-01
There is a dilemma in constructing interacting scale invariant Euclidean field theories that are not conformal invariant. On one hand, scale invariance without conformal invariance seems more generic by requiring only a smaller symmetry. On the other hand, the existence of a nonconserved current with exact scaling dimension d -1 in d dimensions seems to require extra fine-tuning. To understand the competition better, we explore some examples without the reflection positivity. We show that a theory of elasticity (also known as Riva-Cardy theory) coupled with massless fermions in d =4 -ɛ dimensions does not possess an interacting scale invariant fixed point except for an unstable (and unphysical) one with an infinite coefficient of compression. We do, however, find interacting scale invariant but nonconformal field theories in gauge fixed versions of the Banks-Zaks fixed points in d =4 dimensions.
Scale Invariant Gravity - a Simple Formulation
NASA Astrophysics Data System (ADS)
Wesson, P. S.
1981-09-01
Using the Cosmological Principle as justification, it is suggested that the scale-invariant theory of gravity be based on a Conspiracy Hypothesis (CH). The CH says: The matter parameters of a system (mass, density, pressure, etc.), the "constants" of physics and the coordinates occur together in dimensionless combinations (η-numbers) in which the components may vary but in such a manner that the variations conspire to keep the -numbers constant. This hypothesis yields a formulation of the scale-invariant theory that is simpler than other versions of it in which the Newtonian gravitational parameter G is treated as a field variable (Dirac, Hoyle/Narlikar, Canuto et al.). This simple formulation of scale-invariant gravity agrees with a recent reformulation of the (Perfect) Cosmological Principle. It also agrees with observations that have been made to date, and the equations suggest several new tests that can possibly be carried out.
Cosmological constant in scale-invariant theories
Foot, Robert; Kobakhidze, Archil; Volkas, Raymond R.
2011-10-01
The incorporation of a small cosmological constant within radiatively broken scale-invariant models is discussed. We show that phenomenologically consistent scale-invariant models can be constructed which allow a small positive cosmological constant, providing certain relation between the particle masses is satisfied. As a result, the mass of the dilaton is generated at two-loop level. Another interesting consequence is that the electroweak symmetry-breaking vacuum in such models is necessarily a metastable ''false'' vacuum which, fortunately, is not expected to decay on cosmological time scales.
Scale invariant density perturbations from cyclic cosmology
NASA Astrophysics Data System (ADS)
Frampton, Paul Howard
2016-04-01
It is shown how quantum fluctuations of the radiation during the contraction era of a comes back empty (CBE) cyclic cosmology can provide density fluctuations which re-enter the horizon during the subsequent expansion era and at lowest order are scale invariant, in a Harrison-Zel’dovich-Peebles sense. It is necessary to be consistent with observations of large scale structure.
Broken Scale Invariance and Anomalous Dimensions
DOE R&D Accomplishments Database
Wilson, K. G.
1970-05-01
Mack and Kastrup have proposed that broken scale invariance is a symmetry of strong interactions. There is evidence from the Thirring model and perturbation theory that the dimensions of fields defined by scale transformations will be changed by the interaction from their canonical values. We review these ideas and their consequences for strong interactions.
Data series embedding and scale invariant statistics.
Michieli, I; Medved, B; Ristov, S
2010-06-01
Data sequences acquired from bio-systems such as human gait data, heart rate interbeat data, or DNA sequences exhibit complex dynamics that is frequently described by a long-memory or power-law decay of autocorrelation function. One way of characterizing that dynamics is through scale invariant statistics or "fractal-like" behavior. For quantifying scale invariant parameters of physiological signals several methods have been proposed. Among them the most common are detrended fluctuation analysis, sample mean variance analyses, power spectral density analysis, R/S analysis, and recently in the realm of the multifractal approach, wavelet analysis. In this paper it is demonstrated that embedding the time series data in the high-dimensional pseudo-phase space reveals scale invariant statistics in the simple fashion. The procedure is applied on different stride interval data sets from human gait measurements time series (Physio-Bank data library). Results show that introduced mapping adequately separates long-memory from random behavior. Smaller gait data sets were analyzed and scale-free trends for limited scale intervals were successfully detected. The method was verified on artificially produced time series with known scaling behavior and with the varying content of noise. The possibility for the method to falsely detect long-range dependence in the artificially generated short range dependence series was investigated.
NASA Astrophysics Data System (ADS)
Nishi, Sakine; Kobayashi, Tsutomu
2017-03-01
We propose a novel branch of the Galilean genesis scenario as an alternative to inflation, in which the Universe starts expanding from Minkowski in the asymptotic past with a gross violation of the null energy condition (NEC). This variant, described by several functions and parameters within the Horndeski scalar-tensor theory, shares the same background dynamics with the existing genesis models, but the nature of primordial quantum fluctuations is quite distinct. In some cases, tensor perturbations grow on superhorizon scales. The tensor power spectrum can be red, blue, or scale invariant, depending on the model, while scalar perturbations are nearly scale invariant. This is in sharp contrast to typical NEC-violating cosmologies, in which a blue tensor tilt is generated. Though the primordial tensor and scalar spectra are both nearly scale invariant as in the inflationary scenario, the consistency relation in our variant of Galilean genesis is nonstandard.
No fifth force in a scale invariant universe
NASA Astrophysics Data System (ADS)
Ferreira, Pedro G.; Hill, Christopher T.; Ross, Graham G.
2017-03-01
We revisit the possibility that the Planck mass is spontaneously generated in scale-invariant scalar-tensor theories of gravity, typically leading to a "dilaton." The fifth force, arising from the dilaton, is severely constrained by astrophysical measurements. We explore the possibility that nature is fundamentally scale invariant and argue that, as a consequence, the fifth-force effects are dramatically suppressed and such models are viable. We discuss possible obstructions to maintaining scale invariance and how these might be resolved.
Some topics on scale-invariant perturbations from noninflationary universe
NASA Astrophysics Data System (ADS)
Li, Mingzhe
In this paper, we review some topics on generations of scale-invariant primordial scalar and tensor perturbations in the early universe models different from inflation. The content includes generation of scale-invariant and Gaussian scalar perturbation in the ekpyrotic/cyclic universe, and production scale-invariant tensor perturbation in contracting universe. The main property of the models reviewed in this paper is the nonminimal couplings, include nonminimal couplings between the scalar fields and those to the gravity. By introducing these couplings, it is not difficult to achieve scale-invariances for the perturbations in the early universe models alternative to inflation.
Scale-Invariant Transition Probabilities in Free Word Association Trajectories
Costa, Martin Elias; Bonomo, Flavia; Sigman, Mariano
2009-01-01
Free-word association has been used as a vehicle to understand the organization of human thoughts. The original studies relied mainly on qualitative assertions, yielding the widely intuitive notion that trajectories of word associations are structured, yet considerably more random than organized linguistic text. Here we set to determine a precise characterization of this space, generating a large number of word association trajectories in a web implemented game. We embedded the trajectories in the graph of word co-occurrences from a linguistic corpus. To constrain possible transport models we measured the memory loss and the cycling probability. These two measures could not be reconciled by a bounded diffusive model since the cycling probability was very high (16% of order-2 cycles) implying a majority of short-range associations whereas the memory loss was very rapid (converging to the asymptotic value in ∼7 steps) which, in turn, forced a high fraction of long-range associations. We show that memory loss and cycling probabilities of free word association trajectories can be simultaneously accounted by a model in which transitions are determined by a scale invariant probability distribution. PMID:19826622
Scale invariance, conformality, and generalized free fields
Dymarsky, Anatoly; Farnsworth, Kara; Komargodski, Zohar; Luty, Markus A.; Prilepina, Valentina
2016-02-16
This paper addresses the question of whether there are 4D Lorentz invariant unitary quantum fi eld theories with scale invariance but not conformal invariance. We present an important loophole in the arguments of Luty-Polchinski-Rattazzi and Dymarsky-Komargodski-Schwimmer-Theisen that is the trace of the energy-momentum tensor T could be a generalized free field. In this paper we rule out this possibility. The key ingredient is the observation that a unitary theory with scale but not conformal invariance necessarily has a non-vanishing anomaly for global scale transformations. We show that this anomaly cannot be reproduced if T is a generalized free field unless the theory also contains a dimension-2 scalar operator. In the special case where such an operator is present it can be used to redefine ("improve") the energy-momentum tensor, and we show that there is at least one energy-momentum tensor that is not a generalized free field. In addition, we emphasize that, in general, large momentum limits of correlation functions cannot be understood from the leading terms of the coordinate space OPE. This invalidates a recent argument by Farnsworth-Luty-Prilepina (FLP). Finally, despite the invalidity of the general argument of FLP, some of the techniques turn out to be useful in the present context.
Computing with scale-invariant neural representations
NASA Astrophysics Data System (ADS)
Howard, Marc; Shankar, Karthik
The Weber-Fechner law is perhaps the oldest quantitative relationship in psychology. Consider the problem of the brain representing a function f (x) . Different neurons have receptive fields that support different parts of the range, such that the ith neuron has a receptive field at xi. Weber-Fechner scaling refers to the finding that the width of the receptive field scales with xi as does the difference between the centers of adjacent receptive fields. Weber-Fechner scaling is exponentially resource-conserving. Neurophysiological evidence suggests that neural representations obey Weber-Fechner scaling in the visual system and perhaps other systems as well. We describe an optimality constraint that is solved by Weber-Fechner scaling, providing an information-theoretic rationale for this principle of neural coding. Weber-Fechner scaling can be generated within a mathematical framework using the Laplace transform. Within this framework, simple computations such as translation, correlation and cross-correlation can be accomplished. This framework can in principle be extended to provide a general computational language for brain-inspired cognitive computation on scale-invariant representations. Supported by NSF PHY 1444389 and the BU Initiative for the Physics and Mathematics of Neural Systems,.
Noninflationary model with scale invariant cosmological perturbations
Peter, Patrick; Pinho, Emanuel J. C.; Pinto-Neto, Nelson
2007-01-15
We show that a contracting universe which bounces due to quantum cosmological effects and connects to the hot big-bang expansion phase, can produce an almost scale invariant spectrum of perturbations provided the perturbations are produced during an almost matter dominated era in the contraction phase. This is achieved using Bohmian solutions of the canonical Wheeler-DeWitt equation, thus treating both the background and the perturbations in a fully quantum manner. We find a very slightly blue spectrum (n{sub S}-1>0). Taking into account the spectral index constraint as well as the cosmic microwave background normalization measure yields an equation of state that should be less than {omega} < or approx. 8x10{sup -4}, implying n{sub S}-1{approx}O(10{sup -4}), and that the characteristic curvature scale of the Universe at the bounce is L{sub 0}{approx}10{sup 3}l{sub Pl}, a region where one expects that the Wheeler-DeWitt equation should be valid without being spoiled by string or loop quantum gravity effects. We have also obtained a consistency relation between the tensor-to-scalar ratio T/S and the scalar spectral index as T/S{approx}4.6x10{sup -2}{radical}(n{sub S}-1), leading to potentially measurable differences with inflationary predictions.
Scale invariance, conformality, and generalized free fields
Dymarsky, Anatoly; Farnsworth, Kara; Komargodski, Zohar; ...
2016-02-16
This paper addresses the question of whether there are 4D Lorentz invariant unitary quantum fi eld theories with scale invariance but not conformal invariance. We present an important loophole in the arguments of Luty-Polchinski-Rattazzi and Dymarsky-Komargodski-Schwimmer-Theisen that is the trace of the energy-momentum tensor T could be a generalized free field. In this paper we rule out this possibility. The key ingredient is the observation that a unitary theory with scale but not conformal invariance necessarily has a non-vanishing anomaly for global scale transformations. We show that this anomaly cannot be reproduced if T is a generalized free field unlessmore » the theory also contains a dimension-2 scalar operator. In the special case where such an operator is present it can be used to redefine ("improve") the energy-momentum tensor, and we show that there is at least one energy-momentum tensor that is not a generalized free field. In addition, we emphasize that, in general, large momentum limits of correlation functions cannot be understood from the leading terms of the coordinate space OPE. This invalidates a recent argument by Farnsworth-Luty-Prilepina (FLP). Finally, despite the invalidity of the general argument of FLP, some of the techniques turn out to be useful in the present context.« less
A Bayesian Analysis of Scale-Invariant Processes
2012-01-01
Analysis of Scale-Invariant Processes Jingfeng Wang, Rafael L. Bras, Veronica Nieves Georgia Tech Research Corporation Office of Sponsored Programs...processes Veronica Nieves , Jingfeng Wang, and Rafael L. Bras Citation: AIP Conf. Proc. 1443, 56 (2012); doi: 10.1063/1.3703620 View online: http...http://proceedings.aip.org/about/rights_permissions A Bayesian Analysis of Scale-Invariant Processes Veronica Nieves ∗, Jingfeng Wang† and Rafael L. Bras
Maximum entropy distributions of scale-invariant processes.
Nieves, Veronica; Wang, Jingfeng; Bras, Rafael L; Wood, Elizabeth
2010-09-10
Organizations of many variables in nature such as soil moisture and topography exhibit patterns with no dominant scales. The maximum entropy (ME) principle is proposed to show how these variables can be statistically described using their scale-invariant properties and geometric mean. The ME principle predicts with great simplicity the probability distribution of a scale-invariant process in terms of macroscopic observables. The ME principle offers a universal and unified framework for characterizing such multiscaling processes.
Scale invariance of subsurface flow patterns and its limitation
NASA Astrophysics Data System (ADS)
Hergarten, S.; Winkler, G.; Birk, S.
2016-05-01
Preferential flow patterns in the subsurface are of great importance for the availability and the quality of water resources. However, knowledge of their spatial structure is still behind their importance, so that understanding the nature of preferential flow patterns is a major issue in subsurface hydrology. Comparing the statistics of river catchment sizes and spring discharges, we found that the morphology of preferential subsurface flow patterns is probably scale invariant and similar to that of dendritic river networks. This result is not limited to karstic aquifers where the occurrence of dendritic structures has been known at least qualitatively for a long time. The scale invariance even seems to be independent of the lithology of the aquifer. However, scale invariance of river patterns seems to be only limited by the continental scale, while scale invariance of subsurface flow patterns breaks down at much smaller scales. The upper limit of scale invariance in subsurface flow patterns is highly variable. We found a range from thousands of square kilometers for limestone aquifers down to less than 1 km2 in the weathered zone and debris accumulations of crystalline rocks.
Broken scale invariance in time-dependent trapping potentials
NASA Astrophysics Data System (ADS)
Gharashi, Seyed Ebrahim; Blume, D.
2016-12-01
The response of a cold atom gas with contact interactions to a smoothly varying external harmonic confinement in the nonadiabatic regime is studied. The time variation of the angular frequency is varied such that the system is, for vanishing or infinitely strong contact interactions, scale invariant. The time evolution of the system with broken scale invariance (i.e., the time evolution of the system with finite interaction strength) is contrasted with that for a scale invariant system, which exhibits Efimovian-like expansion dynamics that is characterized by log-periodic oscillations with unique period and amplitude. It is found that the breaking of the scale invariance by the finiteness of the interactions leads to a time dependence of the oscillation period and amplitude. It is argued, based on analytical considerations for atomic gases of arbitrary size and numerical results for two one-dimensional particles, that the oscillation period approaches that of the scale-invariant system at large times. The role of the time-dependent contact in the expansion dynamics is analyzed.
Binary optical filters for scale invariant pattern recognition
NASA Technical Reports Server (NTRS)
Reid, Max B.; Downie, John D.; Hine, Butler P.
1992-01-01
Binary synthetic discriminant function (BSDF) optical filters which are invariant to scale changes in the target object of more than 50 percent are demonstrated in simulation and experiment. Efficient databases of scale invariant BSDF filters can be designed which discriminate between two very similar objects at any view scaled over a factor of 2 or more. The BSDF technique has considerable advantages over other methods for achieving scale invariant object recognition, as it also allows determination of the object's scale. In addition to scale, the technique can be used to design recognition systems invariant to other geometric distortions.
Tuning the cosmological constant, broken scale invariance, unitarity
Förste, Stefan; Manz, Paul
2016-06-10
We study gravity coupled to a cosmological constant and a scale but not conformally invariant sector. In Minkowski vacuum, scale invariance is spontaneously broken. We consider small fluctuations around the Minkowski vacuum. At the linearised level we find that the trace of metric perturbations receives a positive or negative mass squared contribution. However, only for the Fierz-Pauli combination the theory is free of ghosts. The mass term for the trace of metric perturbations can be cancelled by explicitly breaking scale invariance. This reintroduces fine-tuning. Models based on four form field strength show similarities with explicit scale symmetry breaking due to quantisation conditions.
Non-equilibrium scale invariance and shortcuts to adiabaticity in a one-dimensional Bose gas
Rohringer, W.; Fischer, D.; Steiner, F.; Mazets, I. E.; Schmiedmayer, J.; Trupke, M.
2015-01-01
We present experimental evidence for scale invariant behaviour of the excitation spectrum in phase-fluctuating quasi-1d Bose gases after a rapid change of the external trapping potential. Probing density correlations in free expansion, we find that the temperature of an initial thermal state scales with the spatial extension of the cloud as predicted by a model based on adiabatic rescaling of initial eigenmodes with conserved quasiparticle occupation numbers. Based on this result, we demonstrate that shortcuts to adiabaticity for the rapid expansion or compression of the gas do not induce additional heating. PMID:25867640
Ordered hierarchy versus scale invariance in sequence stratigraphy
NASA Astrophysics Data System (ADS)
Schlager, Wolfgang
2010-10-01
Sequence stratigraphy has been applied in a wide range of scales of time and space, from decimeter-thick layers formed within hours to kilometer-thick basin fills formed during hundreds of millions of years. The traditional approach to practice sequence stratigraphy in this wide range of scales is to subdivide the sediment piles into an ordered hierarchy of sequence cycles of different duration and different architecture. An alternative are scale-invariant models with fractal characteristics. Published data confirm two predictions of the ordered-hierarchy model: sequences of very short duration (<1 × 103 years) are parasequences bounded by flooding surfaces, very long sequences (>200 × 106 years) are symmetrical transgressive-regressive cycles. However, the sequence record in the range of 1 × 104-200 × 106 years, the principal domain of sequence stratigraphy, shows a rather irregular succession of sequences with variable symmetry and bounded by flooding surfaces or exposure surfaces. For these time scales, scale-invariant models are a good first approximation, particularly because the evidence for scale-invariance and randomness in the stratigraphic record is strong: Frequency spectra of sea-level change as well as rates of sedimentation and rates of accommodation change plotted against length of observation span show basic trends indistinguishable from random walk. These trends, combined with scale-invariant sequence models may be the most efficient tools for across-the-board predictions on sequences and for locating islands of order in the sequence record.
Scale-invariant entropy-based theory for dynamic ordering
Mahulikar, Shripad P. E-mail: spm@aero.iitb.ac.in; Kumari, Priti
2014-09-01
Dynamically Ordered self-organized dissipative structure exists in various forms and at different scales. This investigation first introduces the concept of an isolated embedding system, which embeds an open system, e.g., dissipative structure and its mass and/or energy exchange with its surroundings. Thereafter, scale-invariant theoretical analysis is presented using thermodynamic principles for Order creation, existence, and destruction. The sustainability criterion for Order existence based on its structured mass and/or energy interactions with the surroundings is mathematically defined. This criterion forms the basis for the interrelationship of physical parameters during sustained existence of dynamic Order. It is shown that the sufficient condition for dynamic Order existence is approached if its sustainability criterion is met, i.e., its destruction path is blocked. This scale-invariant approach has the potential to unify the physical understanding of universal dynamic ordering based on entropy considerations.
Gauge coupling unification in a classically scale invariant model
NASA Astrophysics Data System (ADS)
Haba, Naoyuki; Ishida, Hiroyuki; Takahashi, Ryo; Yamaguchi, Yuya
2016-02-01
There are a lot of works within a class of classically scale invariant model, which is motivated by solving the gauge hierarchy problem. In this context, the Higgs mass vanishes at the UV scale due to the classically scale invariance, and is generated via the Coleman-Weinberg mechanism. Since the mass generation should occur not so far from the electroweak scale, we extend the standard model only around the TeV scale. We construct a model which can achieve the gauge coupling unification at the UV scale. In the same way, the model can realize the vacuum stability, smallness of active neutrino masses, baryon asymmetry of the universe, and dark matter relic abundance. The model predicts the existence vector-like fermions charged under SU(3) C with masses lower than 1 TeV, and the SM singlet Majorana dark matter with mass lower than 2.6 TeV.
Manifestly scale-invariant regularization and quantum effective operators
NASA Astrophysics Data System (ADS)
Ghilencea, D. M.
2016-05-01
Scale-invariant theories are often used to address the hierarchy problem. However the regularization of their quantum corrections introduces a dimensionful coupling (dimensional regularization) or scale (Pauli-Villars, etc) which breaks this symmetry explicitly. We show how to avoid this problem and study the implications of a manifestly scale-invariant regularization in (classical) scale-invariant theories. We use a dilaton-dependent subtraction function μ (σ ) which, after spontaneous breaking of the scale symmetry, generates the usual dimensional regularization subtraction scale μ (⟨σ ⟩) . One consequence is that "evanescent" interactions generated by scale invariance of the action in d =4 -2 ɛ (but vanishing in d =4 ) give rise to new, finite quantum corrections. We find a (finite) correction Δ U (ϕ ,σ ) to the one-loop scalar potential for ϕ and σ , beyond the Coleman-Weinberg term. Δ U is due to an evanescent correction (∝ɛ ) to the field-dependent masses (of the states in the loop) which multiplies the pole (∝1 /ɛ ) of the momentum integral to give a finite quantum result. Δ U contains a nonpolynomial operator ˜ϕ6/σ2 of known coefficient and is independent of the subtraction dimensionless parameter. A more general μ (ϕ ,σ ) is ruled out since, in their classical decoupling limit, the visible sector (of the Higgs ϕ ) and hidden sector (dilaton σ ) still interact at the quantum level; thus, the subtraction function must depend on the dilaton only, μ ˜σ . The method is useful in models where preserving scale symmetry at quantum level is important.
Scale-invariant curvature fluctuations from an extended semiclassical gravity
Pinamonti, Nicola E-mail: siemssen@dima.unige.it; Siemssen, Daniel E-mail: siemssen@dima.unige.it
2015-02-15
We present an extension of the semiclassical Einstein equations which couple n-point correlation functions of a stochastic Einstein tensor to the n-point functions of the quantum stress-energy tensor. We apply this extension to calculate the quantum fluctuations during an inflationary period, where we take as a model a massive conformally coupled scalar field on a perturbed de Sitter space and describe how a renormalization independent, almost-scale-invariant power spectrum of the scalar metric perturbation is produced. Furthermore, we discuss how this model yields a natural basis for the calculation of non-Gaussianities of the considered metric fluctuations.
Scale invariance of subsurface flow patterns and its limitation
NASA Astrophysics Data System (ADS)
Hergarten, Stefan; Winkler, Gerfried; Birk, Steffen
2015-04-01
The morphology of river networks at the Earth's surface has been addressed in numerous studies. Numerical simulations of fluvial erosion processes and concepts of optimization have provided a rather comprehensive understanding about the scale invariance of river networks. Less is known about the structure of preferential flow patterns in the subsurface because these are only accessible by indirect measurements in most cases. As preferential flow patterns are crucial for all transport processes in the subsurface, unraveling their structure is a major challenge in subsurface hydrology. Transferring the idea of optimization from surface flow to subsurface flow it was recently suggested that preferential subsurface flow patterns should also have a dendritic, scale-invariant structure similar to that of river networks. In this study we analyzed the mean discharges of serval thousand springs with respect to scale invariance. For this purpose we reanalyzed a data set comprising about 17,000 springs from Spain already published in the literature and three new data sets from the Eastern Alps in Austria. We found that the probability density f(Q) of the discharge distribution can be described by a power law with an exponential cutoff, f(Q) ≈ Q-τe- QQc. The scaling exponent τ was found to be about 1.6, which is slightly larger than the exponent τ = 1.5 of river networks. In contrast to rivers, the distributions of the spring discharges are characterized by a significant cutoff at large discharges. This cutoff strongly depends on the lithology of the aquifers, while the scaling exponent τ ˜ 1.6 seems to be universal. The highest cutoff was found for limestones being one of the primary host rocks for karstic aquifers. We found Qc ˜ 6000 l/s for the limestones in the data set from Spain, suggesting a scale-invariant subsurface flow pattern up to catchment sizes of several thousand square kilometers. At the other edge, we found a cutoff at catchment sizes in the order of
Scale-Invariant Correlations in Dynamic Bacterial Clusters
NASA Astrophysics Data System (ADS)
Chen, Xiao; Dong, Xu; Be'er, Avraham; Swinney, Harry L.; Zhang, H. P.
2012-04-01
In Bacillus subtilis colonies, motile bacteria move collectively, spontaneously forming dynamic clusters. These bacterial clusters share similarities with other systems exhibiting polarized collective motion, such as bird flocks or fish schools. Here we study experimentally how velocity and orientation fluctuations within clusters are spatially correlated. For a range of cell density and cluster size, the correlation length is shown to be 30% of the spatial size of clusters, and the correlation functions collapse onto a master curve after rescaling the separation with correlation length. Our results demonstrate that correlations of velocity and orientation fluctuations are scale invariant in dynamic bacterial clusters.
Non scale-invariant density perturbations from chaotic extended inflation
NASA Technical Reports Server (NTRS)
Mollerach, Silvia; Matarrese, Sabino
1991-01-01
Chaotic inflation is analyzed in the frame of scalar-tensor theories of gravity. Fluctuations in the energy density arise from quantum fluctuations of the Brans-Dicke field and of the inflation field. The spectrum of perturbations is studied for a class of models: it is non scale-invarient and, for certain values of the parameters, it has a peak. If the peak appears at astrophysically interesting scales, it may help to reconcile the Cold Dark Matter scenario for structure formation with large scale observations.
Inconsistency of scale invariant curvature coupled to gravity
Zoller, D.
1990-01-01
We show that the scale invariant curvature action for paths, the point particle version of Polyakov's extrinsic curvature action for surfaces, does not couple consistently to gravity. Although the curvature action for paths yields a massless representation of the Poincare group with fixed helicity and so potentially provides a description of single photons and gravitons, the inconsistent coupling to gravity apparently suggests such a description is not viable. We present a physical interpretation of the inconsistency in terms of the non-localizability of the photon and point out a conceptual kinship between the local symmetry of the curvature theory and the local supersymmetry of a spinning particle or spinning string. 11 refs.
Inconsistency of scale-invariant curvature coupled to gravity
Zoller, D. )
1990-10-29
We show that the scale-invariant curvature action for paths, the point-particle version of Polyakov's extrinsic-curvature action for surfaces, does not couple consistently to gravity. The curvature action for paths yields a massless representation of the Poincare group with fixed helicity and so potentially provides a description of single photons and gravitons. We present a physical interpretation of the inconsistency in terms of the nonlocalizability of the photon and point out a conceptual kinship with the local supersymmetry of a spinning particle.
Inconsistency of scale-invariant curvature coupled to gravity
NASA Astrophysics Data System (ADS)
Zoller, D.
1990-10-01
We show that the scale-invariant curvature action for paths, the point-particle version of Polyakov's extrinsic-curvature action for surfaces, does not couple consistently to gravity. The curvature action for paths yields a massless representation of the Poincaré group with fixed helicity and so potentially provides a description of single photons and gravitons. We present a physical interpretation of the inconsistency in terms of the nonlocalizability of the photon and point out a conceptual kinship with the local supersymmetry of a spinning particle.
Non-scale-invariant density perturbations from chaotic extended inflation
Mollerach, S. ); Matarrese, S. )
1992-03-15
Chaotic inflation is analyzed in the frame of scalar-tensor theories of gravity. Fluctuations in the energy density arise from quantum fluctuations of the Brans-Dicke field and of the inflaton field. The spectrum of perturbations is studied for a class of models: it is non-scale-invariant and, for certain values of the parameters, it has a peak. If the peak appears at astrophysically interesting scales it may help to reconcile the cold-dark-matter scenario for structure formation with large-scale observations.
Scale Invariance in 2D BCS-BEC Crossover
NASA Astrophysics Data System (ADS)
Sensarma, Rajdeep; Taylor, Edward; Randeria, Mohit
2013-03-01
In 2D BCS-BEC crossover, the frequency of the breathing mode in a harmonic trap, as well as the lower edge of the radio frequency spectroscopy response, show remarkable scale-invariance throughout the crossover regime, i.e. they are independent of the coupling constant. Using functional integral methods, we study the behaviour of these quantities in the 2D BCS-BEC crossover and comment on the possible reasons for this scale independence. RS was supported by DAE, Govt. of India. MR was supported by NSF Grant No. DMR-1006532. ET was supported by NSERC and the Canadian Institute for Advanced Research.
Scale Invariance in Landscape Evolution Models Using Stream Power Laws
NASA Astrophysics Data System (ADS)
Kwang, J. S.; Parker, G.
2014-12-01
Landscape evolution models (LEM) commonly utilize stream power laws to simulate river incision with formulations such as E = KAmSn, where E is a vertical incision rate [L/T], K is an erodibility constant [L1-2m/T], A is an upstream drainage area [L2], S is a local channel gradient [-], and m and n are positive exponents that describe the basin hydrology. In our reduced complexity model, the landscape approached equilibrium by balancing an incision rate with a constant, uniform, vertical rock uplift rate at every location in the landscape. From our simulations, for a combination of m and n, the landscape exhibited scale invariance. That is, regardless of the size and scale of the basin, the relief and vertical structure of the landscape remained constant. Therefore, the relief and elevation profile of the landscape at equilibrium were only dependent on the coefficients for erodibility and uplift and an equation that described how upstream area, A, increased as the length of a stream increased. In our analytical 1D models, we utilized two equations that described upslope area, (a) A = Bl, where B is the profile width [L], and l is the stream length from the ridge [L] and (b) A = Clh, Hack's Law, where C is a constant [L2-h] and h is a positive exponent. With these equations, (a) m = n and (b) hm = n resulted in scale invariance. In our numerical 2D models, the relationship between A and l was inherent in the actual structure of the drainage network. From our numerical 2D results, scale invariance occurred when 2m = n. Additionally, using reasonable values from the literature for exponents, n, m and h, resulted in singularities at the ridges in the landscape, which caused truncation error. In consequence, the elevation of the ridge increased as the number of grid cells in the domain increased in the numerical model, and the model was unable to converge. These singularities at the ridges appeared when (a) m ≥ n and (b) hm ≥ n in the analytical model and 2m ≥ n in
Scale-invariant model of marine population dynamics.
Capitán, José A; Delius, Gustav W
2010-06-01
A striking feature of the marine ecosystem is the regularity in its size spectrum: the abundance of organisms as a function of their weight approximately follows a power law over almost ten orders of magnitude. We interpret this as evidence that the population dynamics in the ocean is approximately scale-invariant. We use this invariance in the construction and solution of a size-structured dynamical population model. Starting from a Markov model encoding the basic processes of predation, reproduction, maintenance respiration, and intrinsic mortality, we derive a partial integro-differential equation describing the dependence of abundance on weight and time. Our model represents an extension of the jump-growth model and hence also of earlier models based on the McKendrick-von Foerster equation. The model is scale-invariant provided the rate functions of the stochastic processes have certain scaling properties. We determine the steady-state power-law solution, whose exponent is determined by the relative scaling between the rates of the density-dependent processes (predation) and the rates of the density-independent processes (reproduction, maintenance, and mortality). We study the stability of the steady-state against small perturbations and find that inclusion of maintenance respiration and reproduction in the model has a strong stabilizing effect. Furthermore, the steady state is unstable against a change in the overall population density unless the reproduction rate exceeds a certain threshold.
Evaluation of Scaling Invariance Embedded in Short Time Series
Pan, Xue; Hou, Lei; Stephen, Mutua; Yang, Huijie; Zhu, Chenping
2014-01-01
Scaling invariance of time series has been making great contributions in diverse research fields. But how to evaluate scaling exponent from a real-world series is still an open problem. Finite length of time series may induce unacceptable fluctuation and bias to statistical quantities and consequent invalidation of currently used standard methods. In this paper a new concept called correlation-dependent balanced estimation of diffusion entropy is developed to evaluate scale-invariance in very short time series with length . Calculations with specified Hurst exponent values of show that by using the standard central moving average de-trending procedure this method can evaluate the scaling exponents for short time series with ignorable bias () and sharp confidential interval (standard deviation ). Considering the stride series from ten volunteers along an approximate oval path of a specified length, we observe that though the averages and deviations of scaling exponents are close, their evolutionary behaviors display rich patterns. It has potential use in analyzing physiological signals, detecting early warning signals, and so on. As an emphasis, the our core contribution is that by means of the proposed method one can estimate precisely shannon entropy from limited records. PMID:25549356
Evaluation of scaling invariance embedded in short time series.
Pan, Xue; Hou, Lei; Stephen, Mutua; Yang, Huijie; Zhu, Chenping
2014-01-01
Scaling invariance of time series has been making great contributions in diverse research fields. But how to evaluate scaling exponent from a real-world series is still an open problem. Finite length of time series may induce unacceptable fluctuation and bias to statistical quantities and consequent invalidation of currently used standard methods. In this paper a new concept called correlation-dependent balanced estimation of diffusion entropy is developed to evaluate scale-invariance in very short time series with length ~10(2). Calculations with specified Hurst exponent values of 0.2,0.3,...,0.9 show that by using the standard central moving average de-trending procedure this method can evaluate the scaling exponents for short time series with ignorable bias (≤0.03) and sharp confidential interval (standard deviation ≤0.05). Considering the stride series from ten volunteers along an approximate oval path of a specified length, we observe that though the averages and deviations of scaling exponents are close, their evolutionary behaviors display rich patterns. It has potential use in analyzing physiological signals, detecting early warning signals, and so on. As an emphasis, the our core contribution is that by means of the proposed method one can estimate precisely shannon entropy from limited records.
Vivo, Edoardo; Nicoli, Matteo; Cuerno, Rodolfo
2012-11-01
Among systems that display generic scale invariance, those whose asymptotic properties are anisotropic in space (strong anisotropy, SA) have received relatively less attention, especially in the context of kinetic roughening for two-dimensional surfaces. This is in contrast with their experimental ubiquity, e.g., in the context of thin-film production by diverse techniques. Based on exact results for integrable (linear) cases, here we formulate a SA ansatz that, albeit equivalent to existing ones borrowed from equilibrium critical phenomena, is more naturally adapted to the type of observables that are measured in experiments on the dynamics of thin films, such as one- and two-dimensional height structure factors. We test our ansatz on a paradigmatic nonlinear stochastic equation displaying strong anisotropy like the Hwa-Kardar equation [Phys. Rev. Lett. 62, 1813 (1989)], which was initially proposed to describe the interface dynamics of running sand piles. A very important role to elucidate its SA properties is played by an accurate (Gaussian) approximation through a nonlocal linear equation that shares the same asymptotic properties.
Analysis of scale-invariant slab avalanche size distributions
NASA Astrophysics Data System (ADS)
Faillettaz, J.; Louchet, F.; Grasso, J.-R.; Daudon, D.
2003-04-01
Scale invariance of snow avalanche sizes was reported for the first time in 2001 by Louchet et al. at the EGS conference, using both acoustic emission duration, and the surface of the crown step left at the top of the starting zone, where the former parameter characterises the size of the total avalanche flow, and the latter that of the starting zone. The present paper focuses on parameters of the second type, that are more directly related to precise release mechanisms, vz. the crown crack length L, the crown crack or slab depth H, the crown step surface HxL, the volume HxL^2 of the snow involved in the starting zone, and LxH^2 which is a measure of the stress concentration at the basal crack tip at failure. The analysis is performed on two data sets, from la Grande Plagne (GP) and Tignes (T) ski resorts. For both catalogs, cumulative distributions of L, H, HxL, HxL^2 and LxH^2 are shown to be roughly linear in a log-log plot. i.e. consistent with so-called scale invariant (or power law) distributions for both triggered and natural avalanches. Plateaus are observed at small sizes, and roll-offs at large sizes. The power law exponents for each of these quantities are roughly independent of the ski resort (GP or T) they come from. In contrast, exponents for natural events are significantly smaller than those for artificial ones. We analyse the possible reasons for the scale invariance of these quantities, for the possible "universality" of the exponents corresponding to a given triggering mode, and for the difference in exponents between triggered and natural events. The physical meaning of the observed roll-offs and plateaus is also discussed. The power law distributions analysed here provide the occurrence probability of an avalanche of a given (starting) volume in a given time period on a given area. A possible use of this type of distributions for snow avalanche hazard assessment is contemplated, as it is for earthquakes or rockfalls.
Generalized scale invariance, clouds and radiative transfer on multifractal clouds
Lovejoy, S.; Schertzer, D.
1995-09-01
Recent systematic satellite studies (LANDSAT, AVHRR, METEOSAT) of cloud radiances using (isotropic) energy spectra have displayed excellent scaling from at least about 300m to about 4000km, even for individual cloud pictures. At first sight, this contradicts the observed diversity of cloud morphology, texture and type. The authors argue that the explanation of this apparent paradox is that the differences are due to anisotropy, e.g. differential stratification and rotation. A general framework for anisotropic scaling expressed in terms of isotropic self-similar scaling and fractals and multifractals is needed. Schertzer and Lovejoy have proposed Generalized Scale Invariance (GSI) in response to this need. In GSI, the statistics of the large and small scales of system can be related to each other by a scale changing operator T{sub {lambda}} which depends only on the scale ratio {lambda}{sub i} there is no characteristic size. 3 refs., 1 fig.
Weyl current, scale-invariant inflation, and Planck scale generation
NASA Astrophysics Data System (ADS)
Ferreira, Pedro G.; Hill, Christopher T.; Ross, Graham G.
2017-02-01
Scalar fields, ϕi, can be coupled nonminimally to curvature and satisfy the general criteria: (i) the theory has no mass input parameters, including MP=0 ; (ii) the ϕi have arbitrary values and gradients, but undergo a general expansion and relaxation to constant values that satisfy a nontrivial constraint, K (ϕi)=constant; (iii) this constraint breaks scale symmetry spontaneously, and the Planck mass is dynamically generated; (iv) there can be adequate inflation associated with slow roll in a scale-invariant potential subject to the constraint; (v) the final vacuum can have a small to vanishing cosmological constant; (vi) large hierarchies in vacuum expectation values can naturally form; (vii) there is a harmless dilaton which naturally eludes the usual constraints on massless scalars. These models are governed by a global Weyl scale symmetry and its conserved current, Kμ. At the quantum level the Weyl scale symmetry can be maintained by an invariant specification of renormalized quantities.
Excitation of flow instabilities due to nonlinear scale invariance
Prasad Datta, Dhurjati; Sen, Sudip
2014-05-15
A novel route to instabilities and turbulence in fluid and plasma flows is presented in kinetic Vlasov-Maxwell model. New kind of flow instabilities is shown to arise due to the availability of new kinetic energy sources which are absent in conventional treatments. The present approach is based on a scale invariant nonlinear analytic formalism developed to address irregular motions on a chaotic attractor or in turbulence in a more coherent manner. We have studied two specific applications of this turbulence generating mechanism. The warm plasma Langmuir wave dispersion relation is shown to become unstable in the presence of these multifractal measures. In the second application, these multifractal measures are shown to induce naturally non-Gaussian, i.e., a stretched, Gaussian distribution and anomalous transport for tracer particles from the turbulent advection-diffusion transport equation in a Vlasov plasma flow.
Transport in fractal media: an effective scale-invariant approach.
Hernandez-Coronado, H; Coronado, M; Herrera-Hernandez, E C
2012-06-01
In this paper an advective-dispersion equation with scale-dependent coefficients is proposed for describing transport through fractals. This equation is obtained by imposing scale invariance and assuming that the porosity, the dispersion coefficient, and the velocity follow fractional power laws on the scale. The model incorporates the empirically found trends in highly heterogeneous media, regarding the dependence of the dispersivity on the scale and the dispersion coefficient on the velocity. We conclude that the presence of nontrivial fractal parameters produces anomalous dispersion, as expected, and that the presence of convective processes induces a reescalation in the concentration and shifts the tracer velocity to different values with respect to the nonfractal case.
Fisher information and the thermodynamics of scale-invariant systems
NASA Astrophysics Data System (ADS)
Hernando, A.; Vesperinas, C.; Plastino, A.
2010-02-01
We present a thermodynamic formulation for scale-invariant systems based on the minimization with constraints of the Fisher information measure. In such a way a clear analogy between these systems’ thermal properties and those of gases and fluids is seen to emerge in a natural fashion. We focus our attention on the non-interacting scenario, speaking thus of scale-free ideal gases (SFIGs) and present some empirical evidences regarding such disparate systems as electoral results, city populations and total citations in Physics journals, that seem to indicate that SFIGs do exist. We also illustrate the way in which Zipf’s law can be understood in a thermodynamical context as the surface of a finite system. Finally, we derive an equivalent microscopic description of our systems which totally agrees with previous numerical simulations found in the literature.
Classically Scale Invariant Inflation and (A)gravity
NASA Astrophysics Data System (ADS)
Farzinnia, Arsham
2016-07-01
In this talk, I present the minimal classically scale-invariant and CP-symmetric extension of the standard model, containing one additional complex gauge singlet and three flavors of right-handed Majorana neutrinos, incorporated within a renormalizable framework of gravity, consistent with these symmetries; the Agravity. I particularly focus on the slow-roll inflationary paradigm within this framework, by identifying the pseudo-Nambu-Goldstone boson of the (approximate) scale symmetry with the inflaton field, constructing its one-loop effective potential, computing the slow-roll parameters and the inflationary observables, and demonstrating the compatibility of the small field inflation scenario with the latest Planck collaboration data sets.a
Scale-invariant structure of size fluctuations in plants
Picoli, S.; Mendes, R. S.; Lenzi, E. K.; Malacarne, L. C.
2012-01-01
A wide range of physical and biological systems exhibit complex behaviours characterised by a scale-invariant structure of the fluctuations in their output signals. In the context of plant populations, scaling relationships are typically allometric. In this study, we analysed spatial variation in the size of maize plants (Zea Mays L.) grown in agricultural plots at constant densities and found evidence of scaling in the size fluctuations of plants. The findings indicate that the scaling of the probability distribution of spatial size fluctuation exhibits non-Gaussian behaviour compatible with a Lévy stable process. The scaling relationships were observed for spatial scales spanning three orders of magnitude. These findings should provide additional information for the selection and development of empirically accurate models of pattern formation in plant populations. PMID:22439105
Levels of complexity in scale-invariant neural signals
NASA Astrophysics Data System (ADS)
Ivanov, Plamen Ch.; Ma, Qianli D. Y.; Bartsch, Ronny P.; Hausdorff, Jeffrey M.; Nunes Amaral, Luís A.; Schulte-Frohlinde, Verena; Stanley, H. Eugene; Yoneyama, Mitsuru
2009-04-01
Many physical and physiological signals exhibit complex scale-invariant features characterized by 1/f scaling and long-range power-law correlations, indicating a possibly common control mechanism. Specifically, it has been suggested that dynamical processes, influenced by inputs and feedback on multiple time scales, may be sufficient to give rise to 1/f scaling and scale invariance. Two examples of physiologic signals that are the output of hierarchical multiscale physiologic systems under neural control are the human heartbeat and human gait. Here we show that while both cardiac interbeat interval and gait interstride interval time series under healthy conditions have comparable 1/f scaling, they still may belong to different complexity classes. Our analysis of the multifractal scaling exponents of the fluctuations in these two signals demonstrates that in contrast to the multifractal behavior found in healthy heartbeat dynamics, gait time series exhibit less complex, close to monofractal behavior. Further, we find strong anticorrelations in the sign and close to random behavior for the magnitude of gait fluctuations at short and intermediate time scales, in contrast to weak anticorrelations in the sign and strong positive correlation for the magnitude of heartbeat interval fluctuations—suggesting that the neural mechanisms of cardiac and gait control exhibit different linear and nonlinear features. These findings are of interest because they underscore the limitations of traditional two-point correlation methods in fully characterizing physiological and physical dynamics. In addition, these results suggest that different mechanisms of control may be responsible for varying levels of complexity observed in physiological systems under neural regulation and in physical systems that possess similar 1/f scaling.
Levels of complexity in scale-invariant neural signals.
Ivanov, Plamen Ch; Ma, Qianli D Y; Bartsch, Ronny P; Hausdorff, Jeffrey M; Nunes Amaral, Luís A; Schulte-Frohlinde, Verena; Stanley, H Eugene; Yoneyama, Mitsuru
2009-04-01
Many physical and physiological signals exhibit complex scale-invariant features characterized by 1/f scaling and long-range power-law correlations, indicating a possibly common control mechanism. Specifically, it has been suggested that dynamical processes, influenced by inputs and feedback on multiple time scales, may be sufficient to give rise to 1/f scaling and scale invariance. Two examples of physiologic signals that are the output of hierarchical multiscale physiologic systems under neural control are the human heartbeat and human gait. Here we show that while both cardiac interbeat interval and gait interstride interval time series under healthy conditions have comparable 1/f scaling, they still may belong to different complexity classes. Our analysis of the multifractal scaling exponents of the fluctuations in these two signals demonstrates that in contrast to the multifractal behavior found in healthy heartbeat dynamics, gait time series exhibit less complex, close to monofractal behavior. Further, we find strong anticorrelations in the sign and close to random behavior for the magnitude of gait fluctuations at short and intermediate time scales, in contrast to weak anticorrelations in the sign and strong positive correlation for the magnitude of heartbeat interval fluctuations-suggesting that the neural mechanisms of cardiac and gait control exhibit different linear and nonlinear features. These findings are of interest because they underscore the limitations of traditional two-point correlation methods in fully characterizing physiological and physical dynamics. In addition, these results suggest that different mechanisms of control may be responsible for varying levels of complexity observed in physiological systems under neural regulation and in physical systems that possess similar 1/f scaling.
Ballistic deposition on deterministic fractals: Observation of discrete scale invariance
NASA Astrophysics Data System (ADS)
Horowitz, Claudio M.; Romá, Federico; Albano, Ezequiel V.
2008-12-01
The growth of ballistic aggregates on deterministic fractal substrates is studied by means of numerical simulations. First, we attempt the description of the evolving interface of the aggregates by applying the well-established Family-Vicsek dynamic scaling approach. Systematic deviations from that standard scaling law are observed, suggesting that significant scaling corrections have to be introduced in order to achieve a more accurate understanding of the behavior of the interface. Subsequently, we study the internal structure of the growing aggregates that can be rationalized in terms of the scaling behavior of frozen trees, i.e., structures inhibited for further growth, lying below the growing interface. It is shown that the rms height (hs) and width (ws) of the trees of size s obey power laws of the form hs∝sν∥ and ws∝sν⊥ , respectively. Also, the tree-size distribution (ns) behaves according to ns˜s-τ . Here, ν∥ and ν⊥ are the correlation length exponents in the directions parallel and perpendicular to the interface, respectively. Also, τ is a critical exponent. However, due to the interplay between the discrete scale invariance of the underlying fractal substrates and the dynamics of the growing process, all these power laws are modulated by logarithmic periodic oscillations. The fundamental scaling ratios, characteristic of these oscillations, can be linked to the (spatial) fundamental scaling ratio of the underlying fractal by means of relationships involving critical exponents. We argue that the interplay between the spatial discrete scale invariance of the fractal substrate and the dynamics of the physical process occurring in those media is a quite general phenomenon that leads to the observation of logarithmic-periodic modulations of physical observables.
Scale-invariant gauge theories of gravity: Theoretical foundations
NASA Astrophysics Data System (ADS)
Lasenby, A. N.; Hobson, M. P.
2016-09-01
We consider the construction of gauge theories of gravity, focussing in particular on the extension of local Poincaré invariance to include invariance under local changes of scale. We work exclusively in terms of finite transformations, which allow for a more transparent interpretation of such theories in terms of gauge fields in Minkowski spacetime. Our approach therefore differs from the usual geometrical description of locally scale-invariant Poincaré gauge theory (PGT) and Weyl gauge theory (WGT) in terms of Riemann-Cartan and Weyl-Cartan spacetimes, respectively. In particular, we reconsider the interpretation of the Einstein gauge and also the equations of motion of matter fields and test particles in these theories. Inspired by the observation that the PGT and WGT matter actions for the Dirac field and electromagnetic field have more general invariance properties than those imposed by construction, we go on to present a novel alternative to WGT by considering an "extended" form for the transformation law of the rotational gauge field under local dilations, which includes its "normal" transformation law in WGT as a special case. The resulting "extended" Weyl gauge theory (eWGT) has a number of interesting features that we describe in detail. In particular, we present a new scale-invariant gauge theory of gravity that accommodates ordinary matter and is defined by the most general parity-invariant eWGT Lagrangian that is at most quadratic in the eWGT field strengths, and we derive its field equations. We also consider the construction of PGTs that are invariant under local dilations assuming either the "normal" or "extended" transformation law for the rotational gauge field, but show that they are special cases of WGT and eWGT, respectively.
Scale-invariant spectrum of Lee-Wick model in de Sitter spacetime
NASA Astrophysics Data System (ADS)
Myung, Yun Soo; Moon, Taeyoon
2015-02-01
We obtain a scale-invariant spectrum from the Lee-Wick model in de Sitter spacetime. This model is a fourth-order scalar theory whose mass parameter is determined by M2=2H2. The Harrison-Zel'dovich scale-invariant spectrum is obtained by Fourier transforming the propagator in position space as well as by computing the power spectrum directly. It shows clearly that the LW scalar theory provides a truly scale-invariant spectrum in whole de Sitter, while the massless scalar propagation in de Sitter shows a scale-invariant spectrum in the superhorizon region only.
Viscosity and scale invariance in the unitary Fermi gas
Enss, Tilman; Haussmann, Rudolf; Zwerger, Wilhelm
2011-03-15
We compute the shear viscosity of the unitary Fermi gas above the superfluid transition temperature, using a diagrammatic technique that starts from the exact Kubo formula. The formalism obeys a Ward identity associated with scale invariance which guarantees that the bulk viscosity vanishes identically. For the shear viscosity, vertex corrections and the associated Aslamazov-Larkin contributions are shown to be crucial to reproduce the full Boltzmann equation result in the high-temperature, low fugacity limit. The frequency dependent shear viscosity {eta}({omega}) exhibits a Drude-like transport peak and a power-law tail at large frequencies which is proportional to the Tan contact. The weight in the transport peak is given by the equilibrium pressure, in agreement with a sum rule due to Taylor and Randeria. Near the superfluid transition the peak width is of the order of 0.5T{sub F}, thus invalidating a quasiparticle description. The ratio {eta}/s between the static shear viscosity and the entropy density exhibits a minimum near the superfluid transition temperature whose value is larger than the string theory bound h/(4{pi}k{sub B}) by a factor of about seven.
Dark matter and leptogenesis linked by classical scale invariance
NASA Astrophysics Data System (ADS)
Khoze, Valentin V.; Plascencia, Alexis D.
2016-11-01
In this work we study a classically scale invariant extension of the Standard Model that can explain simultaneously dark matter and the baryon asymmetry in the universe. In our set-up we introduce a dark sector, namely a non-Abelian SU(2) hidden sector coupled to the SM via the Higgs portal, and a singlet sector responsible for generating Majorana masses for three right-handed sterile neutrinos. The gauge bosons of the dark sector are mass-degenerate and stable, and this makes them suitable as dark matter candidates. Our model also accounts for the matter-anti-matter asymmetry. The lepton flavour asymmetry is produced during CP-violating oscillations of the GeV-scale right-handed neutrinos, and converted to the baryon asymmetry by the electroweak sphalerons. All the characteristic scales in the model: the electro-weak, dark matter and the leptogenesis/neutrino mass scales, are generated radiatively, have a common origin and related to each other via scalar field couplings in perturbation theory.
Orthogonal design for scale invariant feature transform optimization
NASA Astrophysics Data System (ADS)
Ding, Xintao; Luo, Yonglong; Yi, Yunyun; Jie, Biao; Wang, Taochun; Bian, Weixin
2016-09-01
To improve object recognition capabilities in applications, we used orthogonal design (OD) to choose a group of optimal parameters in the parameter space of scale invariant feature transform (SIFT). In the case of global optimization (GOP) and local optimization (LOP) objectives, our aim is to show the operation of OD on the SIFT method. The GOP aims to increase the number of correctly detected true matches (NoCDTM) and the ratio of NoCDTM to all matches. In contrast, the LOP mainly aims to increase the performance of recall-precision. In detail, we first abstracted the SIFT method to a 9-way fixed-effect model with an interaction. Second, we designed a mixed orthogonal array, MA(64,23420,2), and its header table to optimize the SIFT parameters. Finally, two groups of parameters were obtained for GOP and LOP after orthogonal experiments and statistical analyses were implemented. Our experiments on four groups of data demonstrate that compared with the state-of-the-art methods, GOP can access more correct matches and is more effective against object recognition. In addition, LOP is favorable in terms of the recall-precision.
Scale Invariant Gabor Descriptor-Based Noncooperative Iris Recognition
NASA Astrophysics Data System (ADS)
Du, Yingzi; Belcher, Craig; Zhou, Zhi
2010-12-01
A new noncooperative iris recognition method is proposed. In this method, the iris features are extracted using a Gabor descriptor. The feature extraction and comparison are scale, deformation, rotation, and contrast-invariant. It works with off-angle and low-resolution iris images. The Gabor wavelet is incorporated with scale-invariant feature transformation (SIFT) for feature extraction to better extract the iris features. Both the phase and magnitude of the Gabor wavelet outputs were used in a novel way for local feature point description. Two feature region maps were designed to locally and globally register the feature points and each subregion in the map is locally adjusted to the dilation/contraction/deformation. We also developed a video-based non-cooperative iris recognition system by integrating video-based non-cooperative segmentation, segmentation evaluation, and score fusion units. The proposed method shows good performance for frontal and off-angle iris matching. Video-based recognition methods can improve non-cooperative iris recognition accuracy.
Scale-Invariant Hydrodynamics and Quantum Viscosity in Fermi Gases
NASA Astrophysics Data System (ADS)
Thomas, John
2015-05-01
An optically-trapped gas of spin 1/2-up and spin 1/2-down 6Li atoms, tuned near a collisional (Feshbach) resonance, provides a unique paradigm for testing predictions that cross interdisciplinary boundaries, from high temperature superconductors to nuclear matter. At resonance, the dilute atomic cloud becomes the most strongly interacting, non-relativistic fluid known: Shock waves are produced when two clouds collide. We observe scale-invariant hydrodynamic expansion of a resonantly interacting gas and determine the quantum shear viscosity η = α ℏn , with n the density, as a function of interaction strength and temperature, from nearly the ground state through the superfluid phase transition. We extract the local shear viscosity coefficient α from cloud-averaged data, using iterative methods borrowed from image processing, and observe previously hidden features, which are compared to recent predictions. In collaboration with Ethan Elliott and James Joseph, Physics Department, North Carolina State University. Supported by NSF, DOE, ARO, AFOSR.
Scale invariance of a diode-like tunnel junction
NASA Astrophysics Data System (ADS)
Cabrera, Hugo; Zanin, Danilo Andrea; de Pietro, Lorenzo Giuseppe; Michaels, Thomas; Thalmann, Peter; Ramsperger, Urs; Vindigni, Alessandro; Pescia, Danilo
2013-03-01
In Near Field-Emission SEM (NFESEM), electrostatic considerations favor a diode-like tunnel junction consisting of an atomic-sized source mounted at the apex of a thin wire placed at nanometric distances from a collector. The quantum mechanical tunnel process, instead, can provide a barrier toward miniaturization. In the first place, it deteriorates the generation of electrons by introducing non-linearities within the classically forbidden zone that exponentially increase with decreasing sizes. In addition, in the direct tunnelling regime, i.e. when the distance between emitter and collector d approaches the subnanometer range, a characteristic length appears, making the cross-over from the (almost) scale-invariant electric-field assisted regime to the essentially different STM-regime. We have observed that the experimental data relating the current I to the two experimental variables V (bias voltage between tip and collector) and d can be made (almost) collapse onto a ``scaling curve'' relating I to the single variable V .d-λ , λ being some exponent that depends solely on the geometry of the junction. This scaling property can be used to highlight non-linear aspects of the quantum mechanical tunnelling process.
Scale invariance implies conformal invariance for the three-dimensional Ising model.
Delamotte, Bertrand; Tissier, Matthieu; Wschebor, Nicolás
2016-01-01
Using the Wilson renormalization group, we show that if no integrated vector operator of scaling dimension -1 exists, then scale invariance implies conformal invariance. By using the Lebowitz inequalities, we prove that this necessary condition is fulfilled in all dimensions for the Ising universality class. This shows, in particular, that scale invariance implies conformal invariance for the three-dimensional Ising model.
Rotation and Scale Invariant Wavelet Feature for Content-Based Texture Image Retrieval.
ERIC Educational Resources Information Center
Lee, Moon-Chuen; Pun, Chi-Man
2003-01-01
Introduces a rotation and scale invariant log-polar wavelet texture feature for image retrieval. The underlying feature extraction process involves a log-polar transform followed by an adaptive row shift invariant wavelet packet transform. Experimental results show that this rotation and scale invariant wavelet feature is quite effective for image…
ERIC Educational Resources Information Center
Moses, Tim
2011-01-01
The purpose of this study was to consider the relationships of prediction, measurement, and scaling invariance when these invariances were simultaneously evaluated in psychometric test data. An approach was developed to evaluate prediction, measurement, and scaling invariance based on linear and nonlinear prediction, measurement, and scaling…
Scale-invariant radio jets and varying black hole spin
NASA Astrophysics Data System (ADS)
Mościbrodzka, M.; Falcke, H.; Noble, S.
2016-11-01
Context. Compact radio cores associated with relativistic jets are often observed in both active galactic nuclei and X-ray binaries. Their radiative properties follow some general scaling laws that primarily depend on their masses and accretion rates. However, it has been suggested that black hole spin can also strongly influence the power and radio flux of these. Aims: We attempt to estimate the dependency of the radio luminosity of steady jets launched by accretion disks on black hole mass, accretion rate, and spin using numerical simulations. Methods: We make use of three-dimensional general relativistic magnetohydrodynamical simulations of accretion disks around low-luminosity black holes in which the jet radio emission is produced by the jet sheath. Results: We find that the radio flux increases roughly by a factor of 6 as the black hole spin increases from a∗ ≈ 0 to a∗ = 0.98. This is comparable to the increase in accretion power with spin, meaning that the ratio between radio jet and accretion power hardly changes. Although our jet spine power scales as expected for the Blandford-Znajek process, the dependency of jet radio luminosity on the black hole spin is somewhat weaker. Also weakly rotating black holes can produce visible radio jets. The overall scaling of the radio emission with black hole mass and accretion rate is consistent with the scale-invariant analytical models used to explain the fundamental plane of black hole activity. Spin does not introduce a significant scatter in this model. Conclusions: The jet-sheath model can describe well-resolved accreting systems, such as Sgr A* and M 87, as well as the general scaling behavior of low-luminosity black holes. Hence the model should be applicable to a wide range of radio jets in sub-Eddington black holes. The black hole spin has an effect on the production of visible radio jet, but it may not be the main driver to produce visible radio jets. An extension of our findings to powerful quasars
General conditions for scale-invariant perturbations in an expanding universe
Geshnizjani, Ghazal; Kinney, William H.; Dizgah, Azadeh Moradinezhad E-mail: whkinney@buffalo.edu
2011-11-01
We investigate the general properties of expanding cosmological models which generate scale-invariant curvature perturbations in the presence of a variable speed of sound. We show that in an expanding universe, generation of a super-Hubble, nearly scale-invariant spectrum of perturbations over a range of wavelengths consistent with observation requires at least one of three conditions: (1) accelerating expansion, (2) a speed of sound faster than the speed of light, or (3) super-Planckian energy density.
The neural correlates of processing scale-invariant environmental sounds at birth.
Gervain, Judit; Werker, Janet F; Black, Alexis; Geffen, Maria N
2016-06-01
Sensory systems are thought to have evolved to efficiently represent the full range of sensory stimuli encountered in the natural world. The statistics of natural environmental sounds are characterized by scale-invariance: the property of exhibiting similar patterns at different levels of observation. The statistical structure of scale-invariant sounds remains constant at different spectro-temporal scales. Scale-invariance plays a fundamental role in how efficiently animals and human adults perceive acoustic signals. However, the developmental origins and brain correlates of the neural encoding of scale-invariant environmental sounds remain unexplored. Here, we investigate whether the human brain extracts the statistical property of scale-invariance. Synthetic sounds generated by a mathematical model to respect scale-invariance or violate it were presented to newborns. In alternating blocks, the two sound types were presented together in an alternating fashion, whereas in non-alternating blocks, only one type of sound was presented. Newborns' brain responses were measured using near-infrared spectroscopy. We found that scale-invariant and variable-scale sounds were discriminated by the newborn brain, as suggested by differential activation in the left frontal and temporal areas to alternating vs. non-alternating blocks. These results indicate that newborns already detect and encode scale-invariance as a characteristic feature of acoustic stimuli. This suggests that the mathematical principle of efficient coding of information guides the auditory neural code from the beginning of human development, a finding that may help explain how evolution has prepared the brain for perceiving the natural world.
Two-measure approach to breaking scale-invariance in a standard-model extension
NASA Astrophysics Data System (ADS)
Guendelman, Eduardo I.; Nishino, Hitoshi; Rajpoot, Subhash
2017-02-01
We introduce Weyl's scale-invariance as an additional global symmetry in the standard model of electroweak interactions. A natural consequence is the introduction of general relativity coupled to scalar fields à la Dirac, that includes the Higgs doublet and a singlet σ-field required for implementing global scale-invariance. We introduce a mechanism for 'spontaneous breaking' of scale-invariance by introducing a coupling of the σ-field to a new metric-independent measure Φ defined in terms of four scalars ϕi (i = 1 , 2 , 3 , 4). Global scale-invariance is regained by combining it with internal diffeomorphism of these four scalars. We show that once the global scale-invariance is broken, the phenomenon (a) generates Newton's gravitational constant GN and (b) triggers spontaneous symmetry breaking in the normal manner resulting in masses for the conventional fermions and bosons. In the absence of fine-tuning the scale at which the scale-symmetry breaks can be of order Planck mass. If right-handed neutrinos are also introduced, their absence at present energy scales is attributed to their mass terms tied to the scale where scale-invariance breaks.
Gu, Changgui; Coomans, Claudia P.; Hu, Kun; Scheer, Frank A. J. L.; Stanley, H. Eugene; Meijer, Johanna H.
2015-01-01
In healthy humans and other animals, behavioral activity exhibits scale invariance over multiple timescales from minutes to 24 h, whereas in aging or diseased conditions, scale invariance is usually reduced significantly. Accordingly, scale invariance can be a potential marker for health. Given compelling indications that exercise is beneficial for mental and physical health, we tested to what extent a lack of exercise affects scale invariance in young and aged animals. We studied six or more mice in each of four age groups (0.5, 1, 1.5, and 2 y) and observed an age-related deterioration of scale invariance in activity fluctuations. We found that limiting the amount of exercise, by removing the running wheels, leads to loss of scale-invariant properties in all age groups. Remarkably, in both young and old animals a lack of exercise reduced the scale invariance in activity fluctuations to the same level. We next showed that scale invariance can be restored by returning the running wheels. Exercise during the active period also improved scale invariance during the resting period, suggesting that activity during the active phase may also be beneficial for the resting phase. Finally, our data showed that exercise had a stronger influence on scale invariance than the effect of age. The data suggest that exercise is beneficial as revealed by scale-invariant parameters and that, even in young animals, a lack of exercise leads to strong deterioration in these parameters. PMID:25675516
Scale invariance in biology: coincidence or footprint of a universal mechanism?
Gisiger, T
2001-05-01
In this article, we present a self-contained review of recent work on complex biological systems which exhibit no characteristic scale. This property can manifest itself with fractals (spatial scale invariance), flicker noise or 1/f-noise where f denotes the frequency of a signal (temporal scale invariance) and power laws (scale invariance in the size and duration of events in the dynamics of the system). A hypothesis recently put forward to explain these scale-free phenomomena is criticality, a notion introduced by physicists while studying phase transitions in materials, where systems spontaneously arrange themselves in an unstable manner similar, for instance, to a row of dominoes. Here, we review in a critical manner work which investigates to what extent this idea can be generalized to biology. More precisely, we start with a brief introduction to the concepts of absence of characteristic scale (power-law distributions, fractals and 1/f-noise) and of critical phenomena. We then review typical mathematical models exhibiting such properties: edge of chaos, cellular automata and self-organized critical models. These notions are then brought together to see to what extent they can account for the scale invariance observed in ecology, evolution of species, type III epidemics and some aspects of the central nervous system. This article also discusses how the notion of scale invariance can give important insights into the workings of biological systems.
NASA Astrophysics Data System (ADS)
Patil, Sandeep Baburao; Sinha, G. R.
2016-07-01
India, having less awareness towards the deaf and dumb peoples leads to increase the communication gap between deaf and hard hearing community. Sign language is commonly developed for deaf and hard hearing peoples to convey their message by generating the different sign pattern. The scale invariant feature transform was introduced by David Lowe to perform reliable matching between different images of the same object. This paper implements the various phases of scale invariant feature transform to extract the distinctive features from Indian sign language gestures. The experimental result shows the time constraint for each phase and the number of features extracted for 26 ISL gestures.
Inflation and reheating in theories with spontaneous scale invariance symmetry breaking
NASA Astrophysics Data System (ADS)
Rinaldi, Massimiliano; Vanzo, Luciano
2016-07-01
We study a scale-invariant model of quadratic gravity with a nonminimally coupled scalar field. We focus on cosmological solutions and find that scale invariance is spontaneously broken and a mass scale naturally emerges. Before the symmetry breaking, the Universe undergoes an inflationary expansion with nearly the same observational predictions of Starobinsky's model. At the end of inflation, the Hubble parameter and the scalar field converge to a stable fixed point through damped oscillations and the usual Einstein-Hilbert action is recovered. The oscillations around the fixed point can reheat the Universe in various ways, and we study in detail some of these possibilities.
NASA Astrophysics Data System (ADS)
Patil, Sandeep Baburao; Sinha, G. R.
2017-02-01
India, having less awareness towards the deaf and dumb peoples leads to increase the communication gap between deaf and hard hearing community. Sign language is commonly developed for deaf and hard hearing peoples to convey their message by generating the different sign pattern. The scale invariant feature transform was introduced by David Lowe to perform reliable matching between different images of the same object. This paper implements the various phases of scale invariant feature transform to extract the distinctive features from Indian sign language gestures. The experimental result shows the time constraint for each phase and the number of features extracted for 26 ISL gestures.
Nonlocal matching condition and scale-invariant spectrum in bouncing cosmology
Chu, C.-S.; Furuta, K.; Lin, F.-L.
2006-05-15
In cosmological scenarios such as the pre-big bang scenario or the ekpyrotic scenario, a matching condition between the metric perturbations in the pre-big bang phase and those in the post big bang phase is often assumed. Various matching conditions have been considered in the literature. Nevertheless obtaining a scale-invariant CMB spectrum via a concrete mechanism remains impossible. In this paper, we examine this problem from the point of view of local causality. We begin with introducing the notion of local causality and explain how it constrains the form of the matching condition. We then prove a no-go theorem: independent of the details of the matching condition, a scale-invariant spectrum is impossible as long as the local causality condition is satisfied. In our framework, it is easy to show that a violation of local causality around the bounce is needed in order to give a scale-invariant spectrum. We study a specific scenario of this possibility by considering a nonlocal effective theory inspired by noncommutative geometry around the bounce and show that a scale-invariant spectrum is possible. Moreover we demonstrate that the magnitude of the spectrum is compatible with observations if the bounce is assumed to occur at an energy scale which is a few orders of magnitude below the Planckian energy scale.
NASA Astrophysics Data System (ADS)
Zhang, Wenqing; Qiu, Lu; Xiao, Qin; Yang, Huijie; Zhang, Qingjun; Wang, Jianyong
2012-11-01
By means of the concept of the balanced estimation of diffusion entropy, we evaluate the reliable scale invariance embedded in different sleep stages and stride records. Segments corresponding to waking, light sleep, rapid eye movement (REM) sleep, and deep sleep stages are extracted from long-term electroencephalogram signals. For each stage the scaling exponent value is distributed over a considerably wide range, which tell us that the scaling behavior is subject and sleep cycle dependent. The average of the scaling exponent values for waking segments is almost the same as that for REM segments (˜0.8). The waking and REM stages have a significantly higher value of the average scaling exponent than that for light sleep stages (˜0.7). For the stride series, the original diffusion entropy (DE) and the balanced estimation of diffusion entropy (BEDE) give almost the same results for detrended series. The evolutions of local scaling invariance show that the physiological states change abruptly, although in the experiments great efforts have been made to keep conditions unchanged. The global behavior of a single physiological signal may lose rich information on physiological states. Methodologically, the BEDE can evaluate with considerable precision the scale invariance in very short time series (˜102), while the original DE method sometimes may underestimate scale-invariance exponents or even fail in detecting scale-invariant behavior. The BEDE method is sensitive to trends in time series. The existence of trends may lead to an unreasonably high value of the scaling exponent and consequent mistaken conclusions.
Scaling and scale invariance of conservation laws in Reynolds transport theorem framework.
Haltas, Ismail; Ulusoy, Suleyman
2015-07-01
Scale invariance is the case where the solution of a physical process at a specified time-space scale can be linearly related to the solution of the processes at another time-space scale. Recent studies investigated the scale invariance conditions of hydrodynamic processes by applying the one-parameter Lie scaling transformations to the governing equations of the processes. Scale invariance of a physical process is usually achieved under certain conditions on the scaling ratios of the variables and parameters involved in the process. The foundational axioms of hydrodynamics are the conservation laws, namely, conservation of mass, conservation of linear momentum, and conservation of energy from continuum mechanics. They are formulated using the Reynolds transport theorem. Conventionally, Reynolds transport theorem formulates the conservation equations in integral form. Yet, differential form of the conservation equations can also be derived for an infinitesimal control volume. In the formulation of the governing equation of a process, one or more than one of the conservation laws and, some times, a constitutive relation are combined together. Differential forms of the conservation equations are used in the governing partial differential equation of the processes. Therefore, differential conservation equations constitute the fundamentals of the governing equations of the hydrodynamic processes. Applying the one-parameter Lie scaling transformation to the conservation laws in the Reynolds transport theorem framework instead of applying to the governing partial differential equations may lead to more fundamental conclusions on the scaling and scale invariance of the hydrodynamic processes. This study will investigate the scaling behavior and scale invariance conditions of the hydrodynamic processes by applying the one-parameter Lie scaling transformation to the conservation laws in the Reynolds transport theorem framework.
An Alternative to the ΛCDM Model: The Case of Scale Invariance
NASA Astrophysics Data System (ADS)
Maeder, Andre
2017-01-01
The hypothesis is made that, at large scales where general relativity may be applied, empty space is scale invariant. This establishes a relation between the cosmological constant and the scale factor λ of the scale-invariant framework. This relation brings major simplifications in the scale-invariant equations for cosmology, which contain a new term, depending on the derivative of the scale factor, that opposes gravity and produces an accelerated expansion. The displacements due to the acceleration term make a high contribution {{{Ω }}}λ to the energy density of the universe, satisfying an equation of the form {{{Ω }}}{{m}}+{{{Ω }}}{{k}}+{{{Ω }}}λ =1. The models do not demand the existence of unknown particles. There is a family of flat models with different density parameters {{{Ω }}}{{m}}< 1. Numerical integrations of the cosmological equations for different values of the curvature and density parameter k and {{{Ω }}}{{m}} are performed. The presence of even tiny amounts of matter in the universe tends to kill scale invariance. The point is that for {{{Ω }}}{{m}}=0.3 the effect is not yet completely killed. Models with non-zero density start explosively with a braking phase followed by a continuously accelerating expansion. Several observational properties are examined, in particular the distances, the m–z diagram, and the {{{Ω }}}{{m}} versus {{{Ω }}}λ plot. Comparisons with observations are also performed for the Hubble constant H0 versus {{{Ω }}}{{m}}, for the expansion history in the plot H(z)/(z+1) versus redshift z, and for the transition redshift from braking to acceleration. These first dynamical tests are satisfied by scale-invariant models, which thus deserve further study.
Zhang, Wenqing; Qiu, Lu; Xiao, Qin; Yang, Huijie; Zhang, Qingjun; Wang, Jianyong
2012-11-01
By means of the concept of the balanced estimation of diffusion entropy, we evaluate the reliable scale invariance embedded in different sleep stages and stride records. Segments corresponding to waking, light sleep, rapid eye movement (REM) sleep, and deep sleep stages are extracted from long-term electroencephalogram signals. For each stage the scaling exponent value is distributed over a considerably wide range, which tell us that the scaling behavior is subject and sleep cycle dependent. The average of the scaling exponent values for waking segments is almost the same as that for REM segments (∼0.8). The waking and REM stages have a significantly higher value of the average scaling exponent than that for light sleep stages (∼0.7). For the stride series, the original diffusion entropy (DE) and the balanced estimation of diffusion entropy (BEDE) give almost the same results for detrended series. The evolutions of local scaling invariance show that the physiological states change abruptly, although in the experiments great efforts have been made to keep conditions unchanged. The global behavior of a single physiological signal may lose rich information on physiological states. Methodologically, the BEDE can evaluate with considerable precision the scale invariance in very short time series (∼10^{2}), while the original DE method sometimes may underestimate scale-invariance exponents or even fail in detecting scale-invariant behavior. The BEDE method is sensitive to trends in time series. The existence of trends may lead to an unreasonably high value of the scaling exponent and consequent mistaken conclusions.
Shift- and scale-invariant recognition of contour objects with logarithmic radial harmonic filters.
Moya, A; Esteve-Taboada, J J; García, J; Ferreira, C
2000-10-10
The phase-only logarithmic radial harmonic (LRH) filter has been shown to be suitable for scale-invariant block object recognition. However, an important set of objects is the collection of contour functions that results from a digital edge extraction of the original block objects. These contour functions have a constant width that is independent of the scale of the original object. Therefore, since the energy of the contour objects decreases more slowly with the scale factor than does the energy of the block objects, the phase-only LRH filter has difficulties in the recognition tasks when these contour objects are used. We propose a modified LRH filter that permits the realization of a shift- and scale-invariant optical recognition of contour objects. The modified LRH filter is a complex filter that compensates the energy variation resulting from the scaling of contour objects. Optical results validate the theory and show the utility of the newly proposed method.
Scale-invariant scalar spectrum from the nonminimal derivative coupling with fourth-order term
NASA Astrophysics Data System (ADS)
Myung, Yun Soo; Moon, Taeyoon
2015-08-01
In this paper, an exactly scale-invariant spectrum of scalar perturbation generated during de Sitter spacetime is found from the gravity model of the nonminimal derivative coupling with fourth-order term. The nonminimal derivative coupling term generates a healthy (ghost-free) fourth-order derivative term, while the fourth-order term provides an unhealthy (ghost) fourth-order derivative term. The Harrison-Zel’dovich spectrum obtained from Fourier transforming the fourth-order propagator in de Sitter space is recovered by computing the power spectrum in its momentum space directly. It shows that this model provides a truly scale-invariant spectrum, in addition to the Lee-Wick scalar theory.
Void probability as a function of the void's shape and scale-invariant models
NASA Technical Reports Server (NTRS)
Elizalde, E.; Gaztanaga, E.
1991-01-01
The dependence of counts in cells on the shape of the cell for the large scale galaxy distribution is studied. A very concrete prediction can be done concerning the void distribution for scale invariant models. The prediction is tested on a sample of the CfA catalog, and good agreement is found. It is observed that the probability of a cell to be occupied is bigger for some elongated cells. A phenomenological scale invariant model for the observed distribution of the counts in cells, an extension of the negative binomial distribution, is presented in order to illustrate how this dependence can be quantitatively determined. An original, intuitive derivation of this model is presented.
A scale-invariant keypoint detector in log-polar space
NASA Astrophysics Data System (ADS)
Tao, Tao; Zhang, Yun
2017-02-01
The scale-invariant feature transform (SIFT) algorithm is devised to detect keypoints via the difference of Gaussian (DoG) images. However, the DoG data lacks the high-frequency information, which can lead to a performance drop of the algorithm. To address this issue, this paper proposes a novel log-polar feature detector (LPFD) to detect scale-invariant blubs (keypoints) in log-polar space, which, in contrast, can retain all the image information. The algorithm consists of three components, viz. keypoint detection, descriptor extraction and descriptor matching. Besides, the algorithm is evaluated in detecting keypoints from the INRIA dataset by comparing with the SIFT algorithm and one of its fast versions, the speed up robust features (SURF) algorithm in terms of three performance measures, viz. correspondences, repeatability, correct matches and matching score.
Observation of the Efimovian expansion in scale-invariant Fermi gases
NASA Astrophysics Data System (ADS)
Deng, Shujin; Shi, Zhe-Yu; Diao, Pengpeng; Yu, Qianli; Zhai, Hui; Qi, Ran; Wu, Haibin
2016-07-01
Scale invariance plays an important role in unitary Fermi gases. Discrete scaling symmetry manifests itself in quantum few-body systems such as the Efimov effect. Here, we report on the theoretical prediction and experimental observation of a distinct type of expansion dynamics for scale-invariant quantum gases. When the frequency of the harmonic trap holding the gas decreases continuously as the inverse of time t, the expansion of the cloud size exhibits a sequence of plateaus. The locations of these plateaus obey a discrete geometric scaling law with a controllable scale factor, and the expansion dynamics is governed by a log-periodic function. This marked expansion shares the same scaling law and mathematical description as the Efimov effect.
Bellay, Timothy; Klaus, Andreas; Seshadri, Saurav; Plenz, Dietmar
2015-07-07
Spontaneous fluctuations in neuronal activity emerge at many spatial and temporal scales in cortex. Population measures found these fluctuations to organize as scale-invariant neuronal avalanches, suggesting cortical dynamics to be critical. Macroscopic dynamics, though, depend on physiological states and are ambiguous as to their cellular composition, spatiotemporal origin, and contributions from synaptic input or action potential (AP) output. Here, we study spontaneous firing in pyramidal neurons (PNs) from rat superficial cortical layers in vivo and in vitro using 2-photon imaging. As the animal transitions from the anesthetized to awake state, spontaneous single neuron firing increases in irregularity and assembles into scale-invariant avalanches at the group level. In vitro spike avalanches emerged naturally yet required balanced excitation and inhibition. This demonstrates that neuronal avalanches are linked to the global physiological state of wakefulness and that cortical resting activity organizes as avalanches from firing of local PN groups to global population activity.
Inflation and reheating in scale-invariant scalar-tensor gravity
NASA Astrophysics Data System (ADS)
Tambalo, Giovanni; Rinaldi, Massimiliano
2017-04-01
We consider the scale-invariant inflationary model studied in Rinaldi and Vanzo (Phys Rev D 94: 024009, 2016). The Lagrangian includes all the scale-invariant operators that can be built with combinations of R, R2 and one scalar field. The equations of motion show that the symmetry is spontaneously broken after an arbitrarily long inflationary period and a fundamental mass scale is generated. Upon symmetry breaking, and in the Jordan frame, both Hubble function and the scalar field undergo damped oscillations that can eventually amplify Standard Model fields and reheat the Universe. In the present work, we study in detail inflation and the reheating mechanism of this model in the Einstein frame and we compare some of the results with the latest observational data.
Do scale-invariant fluctuations imply the breaking of de Sitter invariance?
NASA Astrophysics Data System (ADS)
Youssef, A.
2013-01-01
The quantization of the massless minimally coupled (mmc) scalar field in de Sitter spacetime is known to be a non-trivial problem due to the appearance of strong infrared (IR) effects. In particular, the scale-invariance of the CMB power-spectrum - certainly one of the most successful predictions of modern cosmology - is widely believed to be inconsistent with a de Sitter invariant mmc two-point function. Using a Cesaro-summability technique to properly define an otherwise divergent Fourier transform, we show in this Letter that de Sitter symmetry breaking is not a necessary consequence of the scale-invariant fluctuation spectrum. We also generalize our result to the tachyonic scalar fields, i.e. the discrete series of representations of the de Sitter group, that suffer from similar strong IR effects.
Reconstruction of a nonminimal coupling theory with scale-invariant power spectrum
Qiu, Taotao
2012-06-01
A nonminimal coupling single scalar field theory, when transformed from Jordan frame to Einstein frame, can act like a minimal coupling one. Making use of this property, we investigate how a nonminimal coupling theory with scale-invariant power spectrum could be reconstructed from its minimal coupling counterpart, which can be applied in the early universe. Thanks to the coupling to gravity, the equation of state of our universe for a scale-invariant power spectrum can be relaxed, and the relation between the parameters in the action can be obtained. This approach also provides a means to address the Big-Bang puzzles and anisotropy problem in the nonminimal coupling model within Jordan frame. Due to the equivalence between the two frames, one may be able to find models that are free of the horizon, flatness, singularity as well as anisotropy problems.
Producing a scale-invariant spectrum of perturbations in a Hagedorn phase of string cosmology.
Nayeri, Ali; Brandenberger, Robert H; Vafa, Cumrun
2006-07-14
We study the generation of cosmological perturbations during the Hagedorn phase of string gas cosmology. Using tools of string thermodynamics we provide indications that it may be possible to obtain a nearly scale-invariant spectrum of cosmological fluctuations on scales which are of cosmological interest today. In our cosmological scenario, the early Hagedorn phase of string gas cosmology goes over smoothly into the radiation-dominated phase of standard cosmology, without having a period of cosmological inflation.
NASA Technical Reports Server (NTRS)
Sohrab, Siavash H.; Piltch, Nancy (Technical Monitor)
2000-01-01
A scale-invariant model of statistical mechanics is applied to present invariant forms of mass, energy, linear, and angular momentum conservation equations in reactive fields. The resulting conservation equations at molecular-dynamic scale are solved by the method of large activation energy asymptotics to describe the hydro-thermo-diffusive structure of laminar premixed flames. The predicted temperature and velocity profiles are in agreement with the observations. Also, with realistic physico-chemical properties and chemical-kinetic parameters for a single-step overall combustion of stoichiometric methane-air premixed flame, the laminar flame propagation velocity of 42.1 cm/s is calculated in agreement with the experimental value.
Evidence of Discrete Scale Invariance in DLA and Time-to-Failure by Canonical Averaging
NASA Astrophysics Data System (ADS)
Johansen, A.; Sornette, D.
Discrete scale invariance, which corresponds to a partial breaking of the scaling symmetry, is reflected in the existence of a hierarchy of characteristic scales l0,l0λ,l0λ2,…, where λ is a preferred scaling ratio and l0 a microscopic cut-off. Signatures of discrete scale invariance have recently been found in a variety of systems ranging from rupture, earthquakes, Laplacian growth phenomena, "animals" in percolation to financial market crashes. We believe it to be a quite general, albeit subtle phenomenon. Indeed, the practical problem in uncovering an underlying discrete scale invariance is that standard ensemble averaging procedures destroy it as if it was pure noise. This is due to the fact, that while λ only depends on the underlying physics, l0 on the contrary is realization-dependent. Here, we adapt and implement a novel so-called "canonical" averaging scheme which re-sets the l0 of different realizations to approximately the same value. The method is based on the determination of a realization-dependent effective critical point obtained from, e.g., a maximum susceptibility criterion. We demonstrate the method on diffusion limited aggregation and a model of rupture.
Scale-invariant hidden local symmetry, topology change, and dense baryonic matter
NASA Astrophysics Data System (ADS)
Paeng, Won-Gi; Kuo, Thomas T. S.; Lee, Hyun Kyu; Rho, Mannque
2016-05-01
When scale symmetry is implemented into hidden local symmetry in low-energy strong interactions to arrive at a scale-invariant hidden local symmetric (HLS) theory, the scalar f0(500 ) may be interpreted as pseudo-Nambu-Goldstone (pNG) boson, i.e., dilaton, of spontaneously broken scale invariance, joining the pseudoscalar pNG bosons π and the matter fields V =(ρ ,ω ) as relevant degrees of freedom. Implementing the skyrmion-half-skyrmion transition predicted at large Nc in QCD at a density roughly twice the nuclear matter density found in the crystal simulation of dense skyrmion matter, we determine the intrinsically density-dependent "bare parameters" of the scale-invariant HLS Lagrangian matched to QCD at a matching scale ΛM. The resulting effective Lagrangian, with the parameters scaling with the density of the system, is applied to nuclear matter and dense baryonic matter relevant to massive compact stars by means of the double-decimation renormalization-group Vlow k formalism. We satisfactorily postdict the properties of normal nuclear matter and more significantly predict the equation of state of dense compact-star matter that quantitatively accounts for the presently available data coming from both the terrestrial and space laboratories. We interpret the resulting structure of compact-star matter as revealing how the combination of hidden-scale symmetry and hidden local symmetry manifests itself in compressed baryonic matter.
Apparent Low-Energy Scale Invariance in Two-Dimensional Fermi Gases
NASA Astrophysics Data System (ADS)
Taylor, Edward
2013-05-01
Strongly-interacting systems in two dimensions have occupied a central position in the study of quantum materials. From high temperature superconductors to the Hall effect in two-dimensional electron gases, strong quantum and thermal fluctuations conspire to make this an extremely rich yet poorly-understood regime to work in. Several remarkable and surprising recent experiments in ultracold atomic gases show us that there are puzzles to be understood even in the simplest nontrivial two-dimensional system: a dilute quantum gas with strong s-wave interactions. Amongst these is an experiment that finds an undamped breathing mode oscillating at twice the trap frequency over a wide range of parameters, behaviour nominally associated with scale invariance, even though scale invariance is strictly broken in this system by a finite s-wave scattering length. This apparent scale symmetry is all the more remarkable given that the mean-field BCS theory for the 2D gas predicts an exact low-energy scale invariance, relevant to the low-energy breathing mode, meaning that only quantum and thermal fluctuations can break this low-energy scale symmetry. Understanding why the symmetry breaking is so weak may give insight into how to make reliable theoretical predictions in systems with strong fluctuation effects, where there is no obvious small parameter from which a perturbation expansion can be formulated. Supported by NSF Grant No. DMR-1006532 (Mohit Randeria), NSERC, and the Canadian Institute for Advanced Research.
Anisotropic Scale Invariance Investigation of Drainage Areas Via Remotely Sensed Data
NASA Astrophysics Data System (ADS)
Beaulieu, A.; Gaonac'h, H.; Lovejoy, S.
Spatial and temporal scale invariance investigation is now widespread in geophysical fields and reveals in most cases the existence of scaling or multiscaling behaviour over a large range of scales. However, not much attention is being paid to the anisotropy present in the analyzed geological and geophysical fields while self-similarity is as- sumed most of the time. Theory and models omitting such anisotropy do not take appropriately in consideration the anisotropic dynamics of these natural processes. However, anisotropy is a common characteristics of geophysical dynamics present in the oceans, atmosphere and earth interior and surface. It often implies differential strat- ification and rotation when describing the texture and morphology of the phenomenon scale by scale. In order to account for scaling anisotropy, the formalism of generalized scale invariance (GSI) was developed. Investigation of remotely sensed images (Land- sat, Aster and ERS-1) over drainage areas such as in Ethiopia is conducted to assess the importance of anisotropic scale invariance between eroded (highly anisotropic) and non-eroded (nearly isotropic) areas. The various spectral regions covered by these different satellite images reveal distinct anisotropic intrinsic characteristics of the re- gions (topography, chemical composition, structural features) which need to be ana- lyzed scale by scale. Multifractal parameters are reconsidered in this new anisotropic framework.
ERIC Educational Resources Information Center
Dobbs, David E.
2010-01-01
This note develops and implements the theory of polynomial asymptotes to (graphs of) rational functions, as a generalization of the classical topics of horizontal asymptotes and oblique/slant asymptotes. Applications are given to hyperbolic asymptotes. Prerequisites include the division algorithm for polynomials with coefficients in the field of…
NASA Astrophysics Data System (ADS)
Schlager, Wolfgang
2015-04-01
In contrast to the realms of magmatism and metamorphism, most depositional processes can be observed directly at the earth's surface. Observation of sediment patterns advanced significantly with the advent of remote sensing and 3D reflection seismics. Remote sensing is particularly relevant for the present topic because it documents mainly Holocene sediments - the best objects to link depositional processes to products. Classic examples of scale-invariant geometry are channel-fan systems, i.e. river-delta and canyon-fan complexes. The underlying control in both instances is the energy-dispersion of a channeled stream of water that discharges in a body of still water. The resulting fan-shaped sediment accumulations are scale-invariant over 7 orders of magnitude in linear size. The Mesozoic-Cenozoic record shows comparable trends and patterns. Further examples of depositional scale-invariance include foresets of non-cohesive sediments and braided-channel deposits. Reefs and carbonate platforms offer an example of scale-invariance related to biotic growth. Shallow-water carbonate platforms rimmed by reefs or reef-rimmed atolls with deep lagoons are characteristic morphologies of tropical carbonate deposits. The structure has been compared to a bucket where stiff reef rims hold a pile of loose sediment. Remote sensing data from the Maldive, Chagos and Laccadive archipelagos of the Indian Ocean show that bucket structures are the dominant depositional pattern from meter-size reefs to archipelagos of hundreds of kilometers in diameter, i.e. over more than 4 orders of magnitude in linear size. Over 2.5 orders of magnitude, the bucket structures qualify as statistical fractals. Ecologic and hydrodynamic studies on modern reefs suggest that the bucket structure is a form of biotic self-organization: The edge position in a reef is favored over the center position because bottom shear is higher and the diffusive boundary layer between reef and water thinner. Thus, the reef
NASA Astrophysics Data System (ADS)
Nakayama, Yu
2017-02-01
We show that 11-dimensional supergravity in Euclidean signature admits an exact classical solution with isometry corresponding to a three-dimensional scale-invariant field theory without conformal invariance. We also construct the holographic renormalization group flow that connects the known UV conformal fixed point and the new scale-invariant but not conformal fixed point. In view of holography, the existence of such classical solutions suggests that the topologically twisted M2-brane gauge theory possesses a scale-invariant but not conformal phase.
NASA Astrophysics Data System (ADS)
Chen, Rui; Xu, Jing; Zhang, Song; Chen, Heping; Guan, Yong; Chen, Ken
2017-01-01
The accuracy of structured light measurement depends on delicate offline calibration. However, in some practical applications, the system is supposed to be reconfigured so frequently to track the target that an online calibration is required. To this end, this paper proposes a rapid and autonomous self-recalibration method. For the proposed method, first, the rotation matrix and the normalized translation vector are attained from the fundamental matrix; second, the scale factor is acquired based on scale-invariant registration such that the actual translation vector is obtained. Experiments have been conducted to verify the effectiveness of our proposed method and the results indicate a high degree of accuracy.
Conservation law for massive scale-invariant photons in Weyl-invariant gravity
NASA Astrophysics Data System (ADS)
Shukla, Aradhya; Abhinav, Kumar; Panigrahi, Prasanta K.
2016-12-01
It is demonstrated that a Stückelberg-type gauge theory, coupled to the scalar-tensor theory of gravity, is invariant under both gauge and Weyl transformations. Unlike the pure Stückelberg theory, this coupled Lagrangian has a genuine Weyl symmetry, with a non-vanishing current. The above is true in the Jordan frame, whereas in the Einstein frame, the same theory manifests as Proca theory in presence of pure gravity. It is found that broken scale invariance leads to simultaneous spontaneous breaking of the gauge symmetry.
Scale-Invariant Sparse PCA on High Dimensional Meta-elliptical Data.
Han, Fang; Liu, Han
2014-01-01
We propose a semiparametric method for conducting scale-invariant sparse principal component analysis (PCA) on high dimensional non-Gaussian data. Compared with sparse PCA, our method has weaker modeling assumption and is more robust to possible data contamination. Theoretically, the proposed method achieves a parametric rate of convergence in estimating the parameter of interests under a flexible semiparametric distribution family; Computationally, the proposed method exploits a rank-based procedure and is as efficient as sparse PCA; Empirically, our method outperforms most competing methods on both synthetic and real-world datasets.
Exact Scale Invariance in Mixing of Binary Candidates in Voting Model
NASA Astrophysics Data System (ADS)
Mori, Shintaro; Hisakado, Masato
2010-03-01
We introduce a voting model and discuss the scale invariance in the mixing of candidates. The Candidates are classified into two categories μ\\in \\{0,1\\} and are called as “binary” candidates. There are in total N=N0+N1 candidates, and voters vote for them one by one. The probability that a candidate gets a vote is proportional to the number of votes. The initial number of votes (“seed”) of a candidate μ is set to be sμ. After infinite counts of voting, the probability function of the share of votes of the candidate μ obeys gamma distributions with the shape exponent sμ in the thermodynamic limit Z0=N1s1+N0s0\\to ∞. Between the cumulative functions \\{xμ\\} of binary candidates, the power-law relation 1-x1 ˜ (1-x0)α with the critical exponent α=s1/s0 holds in the region 1-x0,1-x1≪ 1. In the double scaling limit (s1,s0)\\to (0,0) and Z0 \\to ∞ with s1/s0=α fixed, the relation 1-x1=(1-x0)α holds exactly over the entire range 0≤ x0,x1 ≤ 1. We study the data on horse races obtained from the Japan Racing Association for the period 1986 to 2006 and confirm scale invariance.
A scale-invariant cellular-automata model for distributed seismicity
NASA Technical Reports Server (NTRS)
Barriere, Benoit; Turcotte, Donald L.
1991-01-01
In the standard cellular-automata model for a fault an element of stress is randomly added to a grid of boxes until a box has four elements, these are then redistributed to the adjacent boxes on the grid. The redistribution can result in one or more of these boxes having four or more elements in which case further redistributions are required. On the average added elements are lost from the edges of the grid. The model is modified so that the boxes have a scale-invariant distribution of sizes. The objective is to model a scale-invariant distribution of fault sizes. When a redistribution from a box occurs it is equivalent to a characteristic earthquake on the fault. A redistribution from a small box (a foreshock) can trigger an instability in a large box (the main shock). A redistribution from a large box always triggers many instabilities in the smaller boxes (aftershocks). The frequency-size statistics for both main shocks and aftershocks satisfy the Gutenberg-Richter relation with b = 0.835 for main shocks and b = 0.635 for aftershocks. Model foreshocks occur 28 percent of the time.
Dimensionless, Scale Invariant, Edge Weight Metric for the Study of Complex Structural Networks
Colon-Perez, Luis M.; Spindler, Caitlin; Goicochea, Shelby; Triplett, William; Parekh, Mansi; Montie, Eric; Carney, Paul R.; Price, Catherine; Mareci, Thomas H.
2015-01-01
High spatial and angular resolution diffusion weighted imaging (DWI) with network analysis provides a unique framework for the study of brain structure in vivo. DWI-derived brain connectivity patterns are best characterized with graph theory using an edge weight to quantify the strength of white matter connections between gray matter nodes. Here a dimensionless, scale-invariant edge weight is introduced to measure node connectivity. This edge weight metric provides reasonable and consistent values over any size scale (e.g. rodents to humans) used to quantify the strength of connection. Firstly, simulations were used to assess the effects of tractography seed point density and random errors in the estimated fiber orientations; with sufficient signal-to-noise ratio (SNR), edge weight estimates improve as the seed density increases. Secondly to evaluate the application of the edge weight in the human brain, ten repeated measures of DWI in the same healthy human subject were analyzed. Mean edge weight values within the cingulum and corpus callosum were consistent and showed low variability. Thirdly, using excised rat brains to study the effects of spatial resolution, the weight of edges connecting major structures in the temporal lobe were used to characterize connectivity in this local network. The results indicate that with adequate resolution and SNR, connections between network nodes are characterized well by this edge weight metric. Therefore this new dimensionless, scale-invariant edge weight metric provides a robust measure of network connectivity that can be applied in any size regime. PMID:26173147
Bellay, Timothy; Klaus, Andreas; Seshadri, Saurav; Plenz, Dietmar
2015-01-01
Spontaneous fluctuations in neuronal activity emerge at many spatial and temporal scales in cortex. Population measures found these fluctuations to organize as scale-invariant neuronal avalanches, suggesting cortical dynamics to be critical. Macroscopic dynamics, though, depend on physiological states and are ambiguous as to their cellular composition, spatiotemporal origin, and contributions from synaptic input or action potential (AP) output. Here, we study spontaneous firing in pyramidal neurons (PNs) from rat superficial cortical layers in vivo and in vitro using 2-photon imaging. As the animal transitions from the anesthetized to awake state, spontaneous single neuron firing increases in irregularity and assembles into scale-invariant avalanches at the group level. In vitro spike avalanches emerged naturally yet required balanced excitation and inhibition. This demonstrates that neuronal avalanches are linked to the global physiological state of wakefulness and that cortical resting activity organizes as avalanches from firing of local PN groups to global population activity. DOI: http://dx.doi.org/10.7554/eLife.07224.001 PMID:26151674
The pseudo-conformal universe: scale invariance from spontaneous breaking of conformal symmetry
Hinterbichler, Kurt; Khoury, Justin E-mail: jkhoury@sas.upenn.edu
2012-04-01
We present a novel theory of the very early universe which addresses the traditional horizon and flatness problems of big bang cosmology and predicts a scale invariant spectrum of perturbations. Unlike inflation, this scenario requires no exponential accelerated expansion of space-time. Instead, the early universe is described by a conformal field theory minimally coupled to gravity. The conformal fields develop a time-dependent expectation value which breaks the flat space so(4,2) conformal symmetry down to so(4,1), the symmetries of de Sitter, giving perturbations a scale invariant spectrum. The solution is an attractor, at least in the case of a single time-dependent field. Meanwhile, the metric background remains approximately flat but slowly contracts, which makes the universe increasingly flat, homogeneous and isotropic, akin to the smoothing mechanism of ekpyrotic cosmology. Our scenario is very general, requiring only a conformal field theory capable of developing the appropriate time-dependent expectation values, and encompasses existing incarnations of this idea, specifically the U(1) model of Rubakov and the Galileon Genesis scenario. Its essential features depend only on the symmetry breaking pattern and not on the details of the underlying lagrangian. It makes generic observational predictions that make it potentially distinguishable from standard inflation, in particular significant non-gaussianities and the absence of primordial gravitational waves.
Do joint CMB and HST data support a scale invariant spectrum?
NASA Astrophysics Data System (ADS)
Benetti, Micol; Graef, Leila L.; Alcaniz, Jailson S.
2017-04-01
We combine current measurements of the local expansion rate, H0, and Big Bang Nucleosynthesis (BBN) estimates of helium abundance with the latest cosmic microwave background (CMB) data from the Planck Collaboration to discuss the observational viability of the scale invariant Harrison-Zeldovch-Peebles (HZP) spectrum. We also analyze some of its extensions, namely, HZP + YP and HZP + Neff, where YP is the primordial helium mass fraction and Neff is the effective number of relativistic degrees of freedom. We perform a Bayesian analysis and show that the latter model is favored with respect to the standard cosmology for values of Neff lying in the interval 3.70 ± 0.13 (1σ), which is currently allowed by some independent analyses.
Pumping-induced leakage in a bounded aquifer: An example of a scale-invariant phenomenon
Butler, J.J.; Tsou, M.-S.
2003-01-01
A new approach is presented for calculation of the volume of pumping-induced leakage entering an aquifer as a function of time. This approach simplifies the total leakage calculation by extending analytical-based methods developed for infinite systems to bounded aquifers of any size. The simplification is possible because of the relationship between drawdown and leakage in aquifers laterally bounded by impermeable formations. This relationship produces a scale-invariant total leakage; i.e., the volume of leakage as a function of time does not change with the size of the aquifer or with the location of the pumping well. Two examples and image well theory are used to demonstrate and prove, respectively, the generality of this interesting phenomenon.
Scale invariance of continuum size distribution upon irreversible growth of surface islands
NASA Astrophysics Data System (ADS)
Dubrovskii, V. G.; Sokolova, Zh. V.
2015-06-01
The continuum kinetic equation for irreversible heterogeneous growth of a surface island is ana-lyzed given a special form of the dependence of capture coefficient σ on size s and coverage of the surface Θ. It is shown that, if σ( s, Θ) = α(Θ)( a + s)β, the function α(Θ) is arbitrary, and 0 ≤ β ≤ 1, then the solutions of the continuum equation of the first order satisfy the hypothesis about the scale invariance of the size distribu-tion (scaling) in a single exceptional case—at ≤ = 1. The obtained results testify about the presence of a fun-damental relation of the scaling and linearity of the dependence σ( s). Problems about associations of distri-bution functions in continuum and discrete growth models and about application of the obtained solutions for modeling and interpretation of experimental data in different systems are discussed.
Real-time object tracking based on scale-invariant features employing bio-inspired hardware.
Yasukawa, Shinsuke; Okuno, Hirotsugu; Ishii, Kazuo; Yagi, Tetsuya
2016-09-01
We developed a vision sensor system that performs a scale-invariant feature transform (SIFT) in real time. To apply the SIFT algorithm efficiently, we focus on a two-fold process performed by the visual system: whole-image parallel filtering and frequency-band parallel processing. The vision sensor system comprises an active pixel sensor, a metal-oxide semiconductor (MOS)-based resistive network, a field-programmable gate array (FPGA), and a digital computer. We employed the MOS-based resistive network for instantaneous spatial filtering and a configurable filter size. The FPGA is used to pipeline process the frequency-band signals. The proposed system was evaluated by tracking the feature points detected on an object in a video.
Dark matter from a classically scale-invariant S U (3 )X
NASA Astrophysics Data System (ADS)
Karam, Alexandros; Tamvakis, Kyriakos
2016-09-01
In this work we study a classically scale-invariant extension of the Standard Model in which the dark matter and electroweak scales are generated through the Coleman-Weinberg mechanism. The extra S U (3 )X gauge factor gets completely broken by the vacuum expectation values of two scalar triplets. Out of the eight resulting massive vector bosons the three lightest are stable due to an intrinsic Z2×Z2' discrete symmetry and can constitute dark matter candidates. We analyze the phenomenological viability of the predicted multi-Higgs sector imposing theoretical and experimental constraints. We perform a comprehensive analysis of the dark matter predictions of the model solving numerically the set of coupled Boltzmann equations involving all relevant dark matter processes and explore the direct detection prospects of the dark matter candidates.
Automated Image Retrieval of Chest CT Images Based on Local Grey Scale Invariant Features.
Arrais Porto, Marcelo; Cordeiro d'Ornellas, Marcos
2015-01-01
Textual-based tools are regularly employed to retrieve medical images for reading and interpretation using current retrieval Picture Archiving and Communication Systems (PACS) but pose some drawbacks. All-purpose content-based image retrieval (CBIR) systems are limited when dealing with medical images and do not fit well into PACS workflow and clinical practice. This paper presents an automated image retrieval approach for chest CT images based local grey scale invariant features from a local database. Performance was measured in terms of precision and recall, average retrieval precision (ARP), and average retrieval rate (ARR). Preliminary results have shown the effectiveness of the proposed approach. The prototype is also a useful tool for radiology research and education, providing valuable information to the medical and broader healthcare community.
Scale invariance properties of the peak of the width function in topologically random networks
NASA Astrophysics Data System (ADS)
Agnese, Carmelo; Criminisi, Antonio; D'Asaro, Francesco
Some scaling properties of the topological width function for an infinite population of networks obeying the random model are analyzed. A Monte Carlo procedure is applied to generate width functions according to the hypothesis of topological randomness. The probability distributions of both peak and distance to peak of the topological width functions, conditioned (1) on the network diameter λ and (2) on λ and parameter β=[log(2μ-1)]/logλ, are studied. The parameter β can be considered a shape factor of the network; indeed, low β values describe elongated networks, while high β values refer to fan-like networks. Scale invariance for both random variables is established in the first case by using λ as a scale parameter. Also in the second case, scale invariance is observed for both the peak and the distance to peak of the topological width function; in particular, the invariance property for the peak involves a scaling function which is directly related to the shape factor β, allowing determination of the statistical similarity between random networks indexed by the same β. Then, a coarse-graining procedure is applied to a set of 15,000 width functions with λ=512 a scaling behavior of peaks of the original width function and aggregated ones is observed over a wide range of aggregation scales. Consequently, a statistical self-similarity for the peaks is also observed, which involved the same β-related scaling function. Finally, possible implication of the present results on the hydrologic response, at the basin scale, is discussed.
NASA Astrophysics Data System (ADS)
Tavares, Gustavo Marques
The Standard Model of particle physics describes all known elementary particles and their interactions. Despite its great experimental success, we know that the Standard Model is not a complete description of Nature and therefore new phenomena should be observed at higher energies. In the coming years the Large Hadron Collider will test the Standard Model by colliding protons with center of mass energies of up to 14 TeV providing some of the most stringent tests on the Standard Model. Experimental searches for Dark Matter provide a complementary program to test physics at the weak scale. In the near future new experimental data coming from direct detection experiments, and from satellites and telescopes will drastically improve our sensitivity to weak scale dark matter. This could lead to the first direct observation of dark matter, and thus of physics beyond the Standard Model. In this thesis I propose different extensions of the Standard Model and discuss their experimental consequences. I first discuss models for Axigluons, which are spin one particles in the adjoint representation of the SU(3) color gauge group. These models were motivated by the measurement of higher than predicted forward-backward asymmetry in top quark pair production at the Tevatron. I study different scenarios for Axigluon models that can explain the Tevatron result and explore their signatures at the Large Hadron Collider. Second I discuss the implications of ultraviolet scale invariance for the Standard Model, which has been advocated as a solution to the hierarchy problem. I show that in order to solve the hierarchy problem with scale invariance, new physics is required not far from the weak scale. In the last part of this thesis I propose a new model for dark matter, in which dark matter is charged under a hidden non-Abelian gauge group. This leads to modifications in the sensitivity of the usual experimental searches for dark matter in addition to distinct signatures in the Cosmic
SUPERFLUID VORTEX UNPINNING AS A COHERENT NOISE PROCESS, AND THE SCALE INVARIANCE OF PULSAR GLITCHES
Melatos, A.; Warszawski, L.
2009-08-01
The scale-invariant glitch statistics observed in individual pulsars (exponential waiting-time and power-law size distributions) are consistent with a critical self-organization process, wherein superfluid vortices pin metastably in macroscopic domains and unpin collectively via nearest-neighbor avalanches. Macroscopic inhomogeneity emerges naturally if pinning occurs at crustal faults. If, instead, pinning occurs at lattice sites and defects, which are macroscopically homogeneous, we show that an alternative, noncritical self-organization process operates, termed coherent noise, wherein the global Magnus force acts uniformly on vortices trapped in a range of pinning potentials and undergoing thermal creep. It is found that vortices again unpin collectively, but not via nearest-neighbor avalanches, and that, counterintuitively, the resulting glitch sizes are scale invariant, in accord with observational data. A mean-field analytic theory of the coherent noise process, supported by Monte Carlo simulations, yields a power-law size distribution, between the smallest and largest glitch, with exponent a in the range -2 {<=} a {<=} 0. When the theory is fitted to data from the nine most active pulsars, including the two quasi-periodic glitchers PSR J0537-6910 and PSR J0835-4510, it directly constrains the distribution of pinning potentials in the star, leading to two conclusions: (1) the potentials are broadly distributed, with the mean comparable to the standard deviation; and (2) the mean potential decreases with characteristic age. Fitting the theory to the data also constrains the pinned vortex fraction and the rate of thermal creep. An observational test is proposed to discriminate between nearest-neighbor avalanches and coherent noise: the latter process predicts a statistical excess of large glitches ('aftershocks') following a large glitch, whereas the former process does not. Its discriminatory power is discussed under various microphysical scenarios.
NASA Astrophysics Data System (ADS)
Schertzer, D. J.; Tchiguirinskaia, I.; Lovejoy, S.; Tuck, A.
2010-12-01
We discuss the claim of Lindborg et al (2009) that the spectrum power law E(k)≈k-3 on scales ≥600 km obtained with the help of commercial jetliner trajectory deviations (GASP and Mozaic databases) could not be brought into question by Lovejoy et al (2009), because this spectrum corresponds to a “well known theory of quasi-geostrophic turbulence developed by Charney (1971)”. Lindborg, et al (2009) also argued that “earlier limitations [of this theory] would have been relaxed in many of the modern models of atmospheric turbulence”. We show that both these statements are irrelevant and that generalized scale invariance (GSI, Schertzer and Lovejoy 1985) is rather indispensable to go beyond the quasi-geostrophic limitations, to go in fact from scale analysis to scaling analysis. This enables us to derive dynamical equations for the vorticity in an embedding space of (fractional) dimension D=2+Hz (0≤ Hz ≤1, 1- Hz measures the scaling stratification of atmospheric turbulence). These equations correspond to an interesting dynamical alternative to quasi-geostrophic approximation and turbulence. References: Charney, J. G. (1971). "Geostrophic Turbulence." J. Atmos. Sci 28: 1087. Lindborg, E., K. K. Tung, G. D. Nastrom, J. Y. N. Cho and K. S. Gage (2009). "Comment on "Reinterpreting aircraft measurements in anisotropic scaling turbulence" by lovejoy et al. (2009)." Atmos. Chem. Phys. Discuss. 9: 22331-22336. Lovejoy, S., A. F. Tuck, D. Schertzer and S. J. Hovde (2009). "Rinterpreting aircraft measurements in anisotropic scaling turbulence." Atmos. Chem. Phys. 9: 5007-5025. Schertzer, D. and S. Lovejoy (1985). "Generalised scale invariance in turbulent phenomena." Physico-Chemical Hydrodynamics Journal 6: 623-635.
Local scale-invariance of the 2 + 1 dimensional Kardar–Parisi–Zhang model
NASA Astrophysics Data System (ADS)
Kelling, Jeffrey; Ódor, Géza; Gemming, Sibylle
2017-03-01
Local scale-invariance theory is tested by extensive dynamical simulations of the driven dimer lattice gas model, describing the surface growth of the 2 + 1 dimensional Kardar–Parisi–Zhang surfaces. Very precise measurements of the universal autoresponse function enabled us to perform nonlinear fitting with the scaling forms, suggested by local scale-invariance (LSI). While the simple LSI ansatz does not seem to work, forms based on logarithmic extension of LSI provide satisfactory description of the full (measured) time evolution of the autoresponse function.
Turcotte, D.L. )
1991-03-01
Fractal statistics are the only statistics that are scale invariant. Examples in tectonics include distributions of faults, displacements on faults, distributions and permeabilities of fractures, and distributions of folds. Many aspects of sedimentology are also fractal including distributions of sedimentary sequences, variations in permeability, and shapes of boundaries. Since the underlying processes are likely to be scale invariant, it is reasonable to conclude that the number-size statistics of oil fields will be fractal. Log-normal statistics are often applied; they are not scale invariant. Two explanations for fractal statistics can be given. They may be the result of scale-invariant stochastic processes. Random walk (Brownian noise) is one example. Topography generally resembles Brownian noise, a power-law spectrum with fractal dimension D = 1.5. Alternatively fractal statistics can be the result of deterministic chaos. Turbulent flows are examples of deterministic chaos, the governing equations are deterministic but the resulting flows are statistical. Tectonic displacements can be shown to be the result of deterministic chaos; it is likely that erosion is another example.
NASA Technical Reports Server (NTRS)
Thompson, P. M.; Stein, G.
1980-01-01
The behavior of the closed loop eigenstructure of a linear system with output feedback is analyzed as a single parameter multiplying the feedback gain is varied. An algorithm is presented that computes the asymptotically infinite eigenstructure, and it is shown how a system with high gain feedback decouples into single input single ouput systems. Then a synthesis algorithm is presented which uses full state feedback to achieve a desired asymptotic eigenstructure.
NASA Technical Reports Server (NTRS)
Thompson, P. M.; Stein, G.
1980-01-01
The behavior of the closed loop eigenstructure of a linear system with output feedback is analyzed as a single parameter multiplying the feedback gain is varied. An algorithm is presented that computes the asymptotically infinite eigenstructure, and it is shown how a system with high gain, feedback decouples into single input, single output systems. Then a synthesis algorithm is presented which uses full state feedback to achieve a desired asymptotic eigenstructure.
Lee, Dong-Hoon; Lee, Do-Wan; Han, Bong-Soo
2016-01-01
The purpose of this study is an application of scale invariant feature transform (SIFT) algorithm to stitch the cervical-thoracic-lumbar (C-T-L) spine magnetic resonance (MR) images to provide a view of the entire spine in a single image. All MR images were acquired with fast spin echo (FSE) pulse sequence using two MR scanners (1.5 T and 3.0 T). The stitching procedures for each part of spine MR image were performed and implemented on a graphic user interface (GUI) configuration. Moreover, the stitching process is performed in two categories; manual point-to-point (mPTP) selection that performed by user specified corresponding matching points, and automated point-to-point (aPTP) selection that performed by SIFT algorithm. The stitched images using SIFT algorithm showed fine registered results and quantitatively acquired values also indicated little errors compared with commercially mounted stitching algorithm in MRI systems. Our study presented a preliminary validation of the SIFT algorithm application to MRI spine images, and the results indicated that the proposed approach can be performed well for the improvement of diagnosis. We believe that our approach can be helpful for the clinical application and extension of other medical imaging modalities for image stitching. PMID:27064404
Online fringe projection profilometry based on scale-invariant feature transform
NASA Astrophysics Data System (ADS)
Li, Hongru; Feng, Guoying; Yang, Peng; Wang, Zhaomin; Zhou, Shouhuan; Asundi, Anand
2016-08-01
An online fringe projection profilometry (OFPP) based on scale-invariant feature transform (SIFT) is proposed. Both rotary and linear models are discussed. First, the captured images are enhanced by "retinex" theory for better contrast and an improved reprojection technique is carried out to rectify pixel size while keeping the right aspect ratio. Then the SIFT algorithm with random sample consensus algorithm is used to match feature points between frames. In this process, quick response code is innovatively adopted as a feature pattern as well as object modulation. The characteristic parameters, which include rotation angle in rotary OFPP and rectilinear displacement in linear OFPP, are calculated by a vector-based solution. Moreover, a statistical filter is applied to obtain more accurate values. The equivalent aligned fringe patterns are then extracted from each frame. The equal step algorithm, advanced iterative algorithm, and principal component analysis are eligible for phase retrieval according to whether the object moving direction accords with the fringe direction or not. The three-dimensional profile of the moving object can finally be reconstructed. Numerical simulations and experimental results verified the validity and feasibility of the proposed method.
Physical Origins of Statistical Scale Invariance or Scaling in Peak Flows in Real River Networks
NASA Astrophysics Data System (ADS)
Mantilla, R.; Gupta, V. K.; Furey, P.
2005-12-01
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.
Self-organization of developing embryo using scale-invariant approach
2011-01-01
Background Self-organization is a fundamental feature of living organisms at all hierarchical levels from molecule to organ. It has also been documented in developing embryos. Methods In this study, a scale-invariant power law (SIPL) method has been used to study self-organization in developing embryos. The SIPL coefficient was calculated using a centro-axial skew symmetrical matrix (CSSM) generated by entering the components of the Cartesian coordinates; for each component, one CSSM was generated. A basic square matrix (BSM) was constructed and the determinant was calculated in order to estimate the SIPL coefficient. This was applied to developing C. elegans during early stages of embryogenesis. The power law property of the method was evaluated using the straight line and Koch curve and the results were consistent with fractal dimensions (fd). Diffusion-limited aggregation (DLA) was used to validate the SIPL method. Results and conclusion The fractal dimensions of both the straight line and Koch curve showed consistency with the SIPL coefficients, which indicated the power law behavior of the SIPL method. The results showed that the ABp sublineage had a higher SIPL coefficient than EMS, indicating that ABp is more organized than EMS. The fd determined using DLA was higher in ABp than in EMS and its value was consistent with type 1 cluster formation, while that in EMS was consistent with type 2. PMID:21635789
Are galaxy distributions scale invariant? A perspective from dynamical systems theory
NASA Astrophysics Data System (ADS)
McCauley, J. L.
2002-06-01
Unless there is an evidence for fractal scaling with a single exponent over distances 0.1<=r<=100h-1Mpc, then the widely accepted notion of scale invariance of the correlation integral for 0.1<=r<=10h-1Mpc must be questioned. The attempt to extract a scaling exponent /ν from the correlation integral /n(r) by plotting /log(n(r)) vs. /log(r) is unreliable unless the underlying point set is approximately monofractal. The extraction of a spectrum of generalized dimensions νq from a plot of the correlation integral generating function Gn(q) by a similar procedure is probably an indication that Gn(q) does not scale at all. We explain these assertions after defining the term multifractal, mutually inconsistent definitions having been confused together in the cosmology literature. Part of this confusion is traced to the confusion in interpreting a measure-theoretic formula written down by Hentschel and Procaccia in the dynamical systems theory literature, while other errors follow from confusing together entirely different definitions of multifractal from two different schools of thought. Most important are serious errors in data analysis that follow from taking for granted a largest term approximation that is inevitably advertised in the literature on both fractals and dynamical systems theory.
Hierarchical model of natural images and the origin of scale invariance.
Saremi, Saeed; Sejnowski, Terrence J
2013-02-19
The study of natural images and how our brain processes them has been an area of intense research in neuroscience, psychology, and computer science. We introduced a unique approach to studying natural images by decomposing images into a hierarchy of layers at different logarithmic intensity scales and mapping them to a quasi-2D magnet. The layers were in different phases: "cold" and ordered at large-intensity scales, "hot" and disordered at small-intensity scales, and going through a second-order phase transition at intermediate scales. There was a single "critical" layer in the hierarchy that exhibited long-range correlation similar to that found in the 2D Ising model of ferromagnetism at the critical temperature. We also determined the interactions between layers mapped from natural images and found mutual inhibition that generated locally "frustrated" antiferromagnetic states. Almost all information in natural images was concentrated in a few layers near the phase transition, which has biological implications and also points to the hierarchical origin of scale invariance in natural images.
NASA Astrophysics Data System (ADS)
Guo, Sheng; Huang, Weilin; Qiao, Yu
2017-01-01
Image representation and classification are two fundamental tasks toward version understanding. Shape and texture provide two key features for visual representation and have been widely exploited in a number of successful local descriptors, e.g., scale invariant feature transform (SIFT), local binary pattern descriptor, and histogram of oriented gradient. Unlike these gradient-based descriptors, this paper presents a simple yet efficient local descriptor, named local color contrastive descriptor (LCCD), which captures the contrastive aspects among local regions or color channels for image representation. LCCD is partly inspired by the neural science facts that color contrast plays important roles in visual perception and there exist strong linkages between color and shape. We leverage f-divergence as a robust measure to estimate the contrastive features between different spatial locations and multiple channels. Our descriptor enriches local image representation with both color and contrast information. Due to that LCCD does not explore any gradient information, individual LCCD does not yield strong performance. But we verified experimentally that LCCD can compensate strongly SIFT. Extensive experimental results on image classification show that our descriptor improves the performance of SIFT substantially by combination on three challenging benchmarks, including MIT Indoor-67 database, SUN397, and PASCAL VOC 2007.
Robust FFT-based scale-invariant image registration with image gradients.
Tzimiropoulos, Georgios; Argyriou, Vasileios; Zafeiriou, Stefanos; Stathaki, Tania
2010-10-01
We present a robust FFT-based approach to scale-invariant image registration. Our method relies on FFT-based correlation twice: once in the log-polar Fourier domain to estimate the scaling and rotation and once in the spatial domain to recover the residual translation. Previous methods based on the same principles are not robust. To equip our scheme with robustness and accuracy, we introduce modifications which tailor the method to the nature of images. First, we derive efficient log-polar Fourier representations by replacing image functions with complex gray-level edge maps. We show that this representation both captures the structure of salient image features and circumvents problems related to the low-pass nature of images, interpolation errors, border effects, and aliasing. Second, to recover the unknown parameters, we introduce the normalized gradient correlation. We show that, using image gradients to perform correlation, the errors induced by outliers are mapped to a uniform distribution for which our normalized gradient correlation features robust performance. Exhaustive experimentation with real images showed that, unlike any other Fourier-based correlation techniques, the proposed method was able to estimate translations, arbitrary rotations, and scale factors up to 6.
NASA Astrophysics Data System (ADS)
Wang, Xianmin; Li, Bo; Xu, Qizhi
2016-07-01
The anisotropic scale space (ASS) is often used to enhance the performance of a scale-invariant feature transform (SIFT) algorithm in the registration of synthetic aperture radar (SAR) images. The existing ASS-based methods usually suffer from unstable keypoints and false matches, since the anisotropic diffusion filtering has limitations in reducing the speckle noise from SAR images while building the ASS image representation. We proposed a speckle reducing SIFT match method to obtain stable keypoints and acquire precise matches for the SAR image registration. First, the keypoints are detected in a speckle reducing anisotropic scale space constructed by the speckle reducing anisotropic diffusion, so that speckle noise is greatly reduced and prominent structures of the images are preserved, consequently the stable keypoints can be derived. Next, the probabilistic relaxation labeling approach is employed to establish the matches of the keypoints then the correct match rate of the keypoints is significantly increased. Experiments conducted on simulated speckled images and real SAR images demonstrate the effectiveness of the proposed method.
Scale Invariant Feature Transform Technique for Weed Classification in Oil Palm Plantation
NASA Astrophysics Data System (ADS)
Hawari Ghazali, Kamarul; Marzuki Mustafa, Mohd.; Hussain, Aini; Razali, Saifudin
This study presents a new and robust technique using Scale Invariant Feature Transform (SIFT) for weed classification in oil palm plantation. The proposed SIFT classification technique was developed to overcome problem in real application of image processing such as varies of lighting densities, resolution and target range which contributed to classification accuracy. In this study, SIFT classification algorithm is used to extract a set of feature vectors to represent the input image. The set of feature vectors then can be used to classify weed. In general, the weeds can be classified as either broad or narrow. Based on this classification, a decision will be made to control the strategy of weed infestation in oil palm plantations. The effectiveness of the robust SIFT technique has been tested offline where the input images were captured under varies conditions such as different lighting effects, ambiguity resolution values, variable range of object and many sizes of weed which simulate the actual field conditions. The proposed SIFT resulted in over 95.7% accuracy of classification of weed in palm oil plantation.
Lee, Dong-Hoon; Lee, Do-Wan; Han, Bong-Soo
2016-01-01
The purpose of this study is an application of scale invariant feature transform (SIFT) algorithm to stitch the cervical-thoracic-lumbar (C-T-L) spine magnetic resonance (MR) images to provide a view of the entire spine in a single image. All MR images were acquired with fast spin echo (FSE) pulse sequence using two MR scanners (1.5 T and 3.0 T). The stitching procedures for each part of spine MR image were performed and implemented on a graphic user interface (GUI) configuration. Moreover, the stitching process is performed in two categories; manual point-to-point (mPTP) selection that performed by user specified corresponding matching points, and automated point-to-point (aPTP) selection that performed by SIFT algorithm. The stitched images using SIFT algorithm showed fine registered results and quantitatively acquired values also indicated little errors compared with commercially mounted stitching algorithm in MRI systems. Our study presented a preliminary validation of the SIFT algorithm application to MRI spine images, and the results indicated that the proposed approach can be performed well for the improvement of diagnosis. We believe that our approach can be helpful for the clinical application and extension of other medical imaging modalities for image stitching.
Discriminative phenomenological features of scale invariant models for electroweak symmetry breaking
NASA Astrophysics Data System (ADS)
Hashino, Katsuya; Kanemura, Shinya; Orikasa, Yuta
2016-01-01
Classical scale invariance (CSI) may be one of the solutions for the hierarchy problem. Realistic models for electroweak symmetry breaking based on CSI require extended scalar sectors without mass terms, and the electroweak symmetry is broken dynamically at the quantum level by the Coleman-Weinberg mechanism. We discuss discriminative features of these models. First, using the experimental value of the mass of the discovered Higgs boson h (125), we obtain an upper bound on the mass of the lightest additional scalar boson (≃ 543 GeV), which does not depend on its isospin and hypercharge. Second, a discriminative prediction on the Higgs-photon-photon coupling is given as a function of the number of charged scalar bosons, by which we can narrow down possible models using current and future data for the di-photon decay of h (125). Finally, for the triple Higgs boson coupling a large deviation (∼ + 70%) from the SM prediction is universally predicted, which is independent of masses, quantum numbers and even the number of additional scalars. These models based on CSI can be well tested at LHC Run II and at future lepton colliders.
Scale invariance and universality of force networks in static granular matter.
Ostojic, Srdjan; Somfai, Ellák; Nienhuis, Bernard
2006-02-16
Force networks form the skeleton of static granular matter. They are the key factor that determines mechanical properties such as stability, elasticity and sound transmission, which are important for civil engineering and industrial processing. Previous studies have focused on investigations of the global structure of external forces (the boundary condition) and on the probability distribution of individual contact forces. So far, however, precise knowledge of the disordered spatial structure of the force network has remained elusive. Here we report that molecular dynamics simulations of realistic granular packings reveal scale invariance of clusters of particles interacting by means of relatively strong forces. Despite visual variation, force networks for various values of the confining pressure and other parameters have identical scaling exponents and scaling function, thereby determining a universality class. Unexpectedly, the flat ensemble of force configurations (a simple generalization of equilibrium statistical mechanics) belongs to this universality class, whereas some widely studied simplified models do not. This implies that the elasticity of the grains and their geometrical disorder do not affect the universal mechanical properties.
Shortcuts to adiabaticity in classical and quantum processes for scale-invariant driving
NASA Astrophysics Data System (ADS)
Deffner, Sebastian; Jarzynski, Christopher; Del Campo, Adolfo
2014-03-01
All real physical processes in classical as well as in quantum devices operate in finite-time. For most applications, however, adiabatic, i.e. infinitely-slow processes, are more favorable, as these do not cause unwanted, parasitic excitations. A shortcut to adiabaticity is a driving protocol which reproduces in a short time the same final state that would result from an adiabatic process. A particular powerful technique to engineer such shortcuts is transitionless quantum driving by means of counterdiabatic fields. However, determining closed form expressions for the counterdiabatic field has generally proven to be a daunting task. In this paper, we introduce a novel approach, with which we find the explicit form of the counterdiabatic driving field in arbitrary scale-invariant dynamical processes, encompassing expansions and transport. Our approach originates in the formalism of generating functions, and unifies previous approaches independently developed for classical and quantum systems. We show how this new approach allows to design shortcuts to adiabaticity for a large class of classical and quantum, single-particle, non-linear, and many-body systems. SD and CJ acknowledge support from the National Science Foundation (USA) under grant DMR-1206971. This research is further supported by the U.S Department of Energy through the LANL/LDRD Program and a LANL J. Robert Oppenheimer fellowship (AdC).
Fast scale-invariant lateral lumbar vertebrae detection and segmentation in X-ray images.
Sa, Ruhan; Owens, William; Wiegand, Raymond; Chaudhary, Vipin; Sa, Ruhan; Owens, William; Wiegand, Raymond; Chaudhary, Vipin; Owens, William; Sa, Ruhan; Wiegand, Raymond; Chaudhary, Vipin
2016-08-01
Fully automatic localization of lumbar vertebrae from clinical X-ray images is very challenging due to the variation of X-ray quality, scale, contrast, number of visible vertebrae, etc. To overcome these challenges, we present a novel framework, where we accelerate a scale-invariant object detection method using Support Vector Machines (SVM) trained on Histogram of Oriented Gradients (HOG) features and segmenting a fine vertebra contour using Gradient Vector Flow (GVF) based snake model. Support Vector Machines trained on HOG features are now an object detection standard in many perception fields and have demonstrated good performance on medical images as well. However, the computational complexity and lack of robustness brought by rescaling the original images have prevented its applicability. The proposed multistage detection framework uses lower-level detection result to determine the rescaling regions to reduce the region of interest, thereby decreasing the execution time. We further refine the detection result by segmenting the contour of vertebra using GVF snake, where we use edge detection techniques to increase the robustness of the GVF snake. Finally, we experimentally demonstrate the effectiveness of this framework using a large set of clinical X-ray images.
NASA Astrophysics Data System (ADS)
Berry, M. V.
2005-01-01
By applying the technique of uniform asymptotic approximation to the oscillatory integrals representing tsunami wave profiles, the form of the travelling wave far from the source is calculated for arbitrary initial disturbances. The approximations reproduce the entire profiles very accurately, from the front to the tail, and their numerical computation is much faster than that of the oscillatory integrals. For one-dimensional propagation, the uniform asymptotics involve Airy functions and their derivatives; for two-dimensional propagation, the uniform asymptotics involve products of these functions. Separate analyses are required when the initial disturbance is specified as surface elevation or surface velocity as functions of position, and when these functions are even or odd. 'There was an awful rainbow once in heaven' (John Keats, 1820)
From genes to genomes: universal scale-invariant properties of microbial chromosome organisation.
Audit, Benjamin; Ouzounis, Christos A
2003-09-19
The availability of complete genome sequences for a large variety of organisms is a major advance in understanding genome structure and function. One attribute of genome structure is chromosome organisation in terms of gene localisation and orientation. For example, bacterial operons, i.e. clusters of co-oriented genes that form transcription units, enable functionally related genes to be expressed simultaneously. The description of genome organisation was pioneered with the study of the distribution of genes of the Escherichia coli partial genetic map before the full genome sequence was known. Deploying powerful techniques from circular statistics and signal processing, we revisit the issue of gene localisation and orientation using 89 complete microbial chromosomes from the eubacterial and archaeal domains. We demonstrate that there is no characteristic size pertinent to the description of chromosome structure, e.g. there does not exist any single length appropriate to describe gene clustering. Our results show that, for all 89 chromosomes, gene positions and gene orientations share a common form of scale-invariant correlations known as "long-range correlations" that we can reveal for distances from the gene length, up to the chromosome size. This observation indicates that genes tend to assemble and to co-orient over any scale of observation greater than a few kilobases. This unexpected property of chromosome structure can be portrayed as an operon-like organisation at all scales and implies that a complete scale range extending over more than three orders of magnitudes of chromosome segment lengths is necessary to properly describe prokaryotic genome organisation. We propose that this pattern results from the effects of the superhelical context on gene expression coupled with the structure and dynamics of the nucleoid, possibly accommodating the diverse gene expression profiles needed during the different stages of cellular life.
From elasticity to inelasticity in cancer cell mechanics: A loss of scale-invariance
NASA Astrophysics Data System (ADS)
Laperrousaz, B.; Drillon, G.; Berguiga, L.; Nicolini, F.; Audit, B.; Satta, V. Maguer; Arneodo, A.; Argoul, F.
2016-08-01
Soft materials such as polymer gels, synthetic biomaterials and living biological tissues are generally classified as viscoelastic or viscoplastic materials, because they behave neither as pure elastic solids, nor as pure viscous fluids. When stressed beyond their linear viscoelastic regime, cross-linked biopolymer gels can behave nonlinearly (inelastically) up to failure. In living cells, this type of behavior is more frequent because their cytoskeleton is basically made of cross-linked biopolymer chains with very different structural and flexibility properties. These networks have high sensitivity to stress and great propensity to local failure. But in contrast to synthetic passive gels, they can "afford" these failures because they have ATP driven reparation mechanisms which often allow the recovery of the original texture. A cell pressed in between two plates for a long period of time may recover its original shape if the culture medium brings all the nutrients for keeping it alive. When the failure events are too frequent or too strong, the reparation mechanisms may abort, leading to an irreversible loss of mechanical homeostasis and paving the way for chronic diseases such as cancer. To illustrate this discussion, we consider a model of immature cell transformation during cancer progression, the chronic myelogenous leukemia (CML), where the formation of the BCR-ABL oncogene results from a single chromosomal translocation t(9; 22). Within the assumption that the cell response to stress is scale invariant, we show that the power-law exponent that characterizes their mechanosensitivity can be retrieved from AFM force indentation curves. Comparing control and BCR-ABL transduced cells, we observe that in the later case, one month after transduction, a small percentage the cancer cells no longer follows the control cell power law, as an indication of disruption of the initial cytoskeleton network structure.
Scale-Invariance in the Spatial Development of Landslides in the Umbria Region (Italy)
NASA Astrophysics Data System (ADS)
Liucci, Luisa; Melelli, Laura; Suteanu, Cristian
2015-07-01
Understanding the spatial distribution of mass movements is a major issue in the management and forecasting of landslide risk. In this context, the present study examines the most widespread types of landslide in the Umbria region (central Italy), that is, slides and flows, in order to establish if it is possible to identify a well-defined structure in their spatial pattern. By using the landslide inventory map available for the area and by resorting to the principles of fractal theory, the scaling properties of the landslide sample were investigated. The application of the box-counting algorithm to the maps of landslide triggering points and landslide areas allowed for the identification of a clear scale-invariant structure. Two distinct types of fractal behaviour were recognized, separated by a scale value of 1 km and characterized by capacity dimensions of 1.35 and 1.76, in the ranges of 25 m-1 km and 1-16 km, respectively. The comparison between the scaling exponents obtained from a map of points and one of areas, and the elaboration of the cumulative frequency distributions of landslide areas supported the interpretation of this result: the higher capacity dimension describes the spatial distribution of landslides in the Umbria region, while the lower contains additional information about their geometries, suggesting that the latter also possess scaling properties. Based on the finding of two different types of behaviour of landslides in space, the hypothesis is discussed that the contribution of each causal factor (i.e., predisposing and triggering factors) to the occurrence of landslide events and to their spatial development could be different in the two scale ranges identified, depending on its spatial variability at local and regional scale. According to this hypothesis, factors with high local variability (i.e., topographic attributes) would mainly affect the assortment of landslide geometries, while those with high regional variability (e.g., rainfalls
Spontaneous breaking of scale invariance in a D = 3 U(N ) model with Chern-Simons gauge fields
Bardeen, William A.; Moshe, Moshe
2014-06-18
We study spontaneous breaking of scale invariance in the large N limit of three dimensional U(N )κ Chern-Simons theories coupled to a scalar field in the fundamental representation. When a λ6 ( Ø† · Ø)3 self interaction term is added to the action we find a massive phase at a certain critical value for a combination of the λ(6) and ’t Hooft’s λ = N/κ couplings. This model attracted recent attention since at finite κ it contains a singlet sector which is conjectured to be dual to Vasiliev’s higher spin gravity on AdS4. Our paper concentrates on the massive phasemore » of the 3d boundary theory. We discuss the advantage of introducing masses in the boundary theory through spontaneous breaking of scale invariance.« less
Spontaneous breaking of scale invariance in a D = 3 U(N ) model with Chern-Simons gauge fields
Bardeen, William A.; Moshe, Moshe
2014-06-18
We study spontaneous breaking of scale invariance in the large N limit of three dimensional U(N )_{κ} Chern-Simons theories coupled to a scalar field in the fundamental representation. When a λ_{6} ( Ø^{† }· Ø)^{3 }self interaction term is added to the action we find a massive phase at a certain critical value for a combination of the λ(6) and ’t Hooft’s λ = N/κ couplings. This model attracted recent attention since at finite κ it contains a singlet sector which is conjectured to be dual to Vasiliev’s higher spin gravity on AdS_{4}. Our paper concentrates on the massive phase of the 3d boundary theory. We discuss the advantage of introducing masses in the boundary theory through spontaneous breaking of scale invariance.
NASA Technical Reports Server (NTRS)
Elizalde, E.; Gaztanaga, E.
1992-01-01
The dependence of counts in cells on the shape of the cell for the large scale galaxy distribution is studied. A very concrete prediction can be done concerning the void distribution for scale invariant models. The prediction is tested on a sample of the CfA catalog, and good agreement is found. It is observed that the probability of a cell to be occupied is bigger for some elongated cells. A phenomenological scale invariant model for the observed distribution of the counts in cells, an extension of the negative binomial distribution, is presented in order to illustrate how this dependence can be quantitatively determined. An original, intuitive derivation of this model is presented.
Strongly first-order electroweak phase transition and classical scale invariance
NASA Astrophysics Data System (ADS)
Farzinnia, Arsham; Ren, Jing
2014-10-01
In this work, we examine the possibility of realizing a strongly first-order electroweak phase transition within the minimal classically scale-invariant extension of the standard model (SM), previously proposed and analyzed as a potential solution to the hierarchy problem. By introducing one complex gauge-singlet scalar and three (weak scale) right-handed Majorana neutrinos, the scenario was successfully rendered capable of achieving a radiative breaking of the electroweak symmetry (by means of the Coleman-Weinberg mechanism), inducing nonzero masses for the SM neutrinos (via the seesaw mechanism), presenting a pseudoscalar dark matter candidate (protected by the CP symmetry of the potential), and predicting the existence of a second CP-even boson (with suppressed couplings to the SM content) in addition to the 125 GeV scalar. In the present treatment, we construct the full finite-temperature one-loop effective potential of the model, including the resummed thermal daisy loops, and demonstrate that finite-temperature effects induce a first-order electroweak phase transition. Requiring the thermally driven first-order phase transition to be sufficiently strong at the onset of the bubble nucleation (corresponding to nucleation temperatures TN˜100-200 GeV) further constrains the model's parameter space; in particular, an O(0.01) fraction of the dark matter in the Universe may be simultaneously accommodated with a strongly first-order electroweak phase transition. Moreover, such a phase transition disfavors right-handed Majorana neutrino masses above several hundreds of GeV, confines the pseudoscalar dark matter masses to ˜1-2 TeV, predicts the mass of the second CP-even scalar to be ˜100-300 GeV, and requires the mixing angle between the CP-even components of the SM doublet and the complex singlet to lie within the range 0.2≲sinω ≲0.4. The obtained results are displayed in comprehensive exclusion plots, identifying the viable regions of the parameter space
NASA Astrophysics Data System (ADS)
Murase, M.
1996-01-01
with self-organization, has been thought to underlie `creative' aspects of biological phenomena such as the origin of life, adaptive evolution of viruses, immune recognition and brain function. It therefore must be surprising to find that the same principles will also underlie `non-creative' aspects, for example, the development of cancer and the aging of complex organisms. Although self-organization has extensively been studied in nonliving things such as chemical reactions and laser physics, it is undoubtedly true that the similar sources of the order are available to living things at different levels and scales. Several paradigm shifts are, however, required to realize how the general principles of natural selection can be extensible to non-DNA molecules which do not possess the intrinsic nature of self-reproduction. One of them is, from the traditional, genetic inheritance view that DNA (or RNA) molecules are the ultimate unit of heritable variations and natural selection at any organization level, to the epigenetic (nongenetic) inheritance view that any non-DNA molecule can be the target of heritable variations and molecular selection to accumulate in certain biochemical environment. Because they are all enriched with a β-sheet content, ready to mostly interact with one another, different denatured proteins like β-amyloid, PHF and prions can individually undergo self-templating or self-aggregating processes out of gene control. Other paradigm shifts requisite for a break-through in the etiology of neurodegenerative disorders will be discussed. As it is based on the scale-invariant principles, the present theory also predicts plausible mechanisms underlying quite different classes of disorders such as amyotrophic lateral sclerosis (ALS), atherosclerosis, senile cataract and many other symptoms of aging. The present theory, thus, provides the consistent and comprehensive account to the origin of aging by means of natural selection and self-organization.
NASA Astrophysics Data System (ADS)
Krumbholz, M.; Burchardt, S.; Tanner, D. C.; Koyi, H.
2012-04-01
Fracture dimensions and their spatial distribution are of primary importance in many fields of applied geology, e.g. they determine the quality of sites for the long-term storage of hazardous waste and fractured reservoirs for e.g. hydrocarbons, CO2 sequestration, and geothermal energy. Unfortunately, the observation of fracture systems is commonly limited by the outcrop size or the resolution of the measuring method. Fractures and fracture properties are often assumed to be scale-invariant, albeit within a certain range. Therefore, knowing the fractal dimension of fracture properties allows conclusions to be drawn from one particular scale to another. We investigated fracture trace lengths and patterns at map-, outcrop- and handspecimen scale, covering a large area in the Transscandinavian Igneous Belt. The dataset comprises 11 fracture maps at three different scales containing 8641 fracture trace lengths. Analysis of the fracture trace lengths was carried out using cumulative frequency distributions, while the fracture patterns were analysed with the standard box-counting technique. Combining the three analysed scales, our results indicate that the fracture trace lengths can be considered to be scale-invariant with a fractal dimension of about 1.8. In contrast, the fractal dimension at one particular scale could not be determined, probably due to censoring and truncation effects. Analyses with the box-counting method show that the fracture patterns, in contrast to fracture trace lengths, are not scale-invariant. The box-counting dimension increases with increasing scale. It is a measure of the complexity and maturity of a fracture system, which increases with scale. Consequently, the complexity of fracture pattern is scale-variant.
NASA Astrophysics Data System (ADS)
Ferraro, Marta; Furman, Nicolas; Liu, Yang; Mariani, Cristina; Rial, Diego
2006-01-01
This work is devoted to the study of the relation between intermittence and scale invariance. We find the conditions that a function in which both effects are present must satisfy, and we analyze the relation with characteristic scales. We present an efficient method that detects characteristic scales in different systems. Finally we develop a model that predicts the existence of intermittence and characteristic scales in the behavior of a financial index near a crash, and we apply the model to the analysis of several financial indices.
NASA Astrophysics Data System (ADS)
Mariani, Maria Cristina; Liu, Yang
2006-07-01
This work is devoted to the study of the relation between intermittence and scale invariance, and applications to the behavior of financial indices near a crash. We developed a numerical analysis that predicts the critical date of a financial index, and we apply the model to the analysis of several financial indices. We were able to obtain optimum values for the critical date, corresponding to the most probable date of the crash. We only used data from before the true crash date in order to obtain the predicted critical date. The good numerical results validate the model.
NASA Astrophysics Data System (ADS)
Ma, Haitao; Zhai, Xiaoping; Yan, Wei; Li, Yongsheng
2017-02-01
In this paper, we study the global well posedness of the 3D incompressible magnetohydrodynamic system with horizontal dissipation and horizontal magnetic diffusion in the scaling invariant Besov-Sobolev-type spaces. We first get a unique global solution to this system with small initial data by the classical Friedrich's regularization method. Then using a weighted Chemin-Lerner-type norm, we prove the system also can generate a global solution if the horizontal components of the initial data are small enough compared to the vertical components. In particular, our results imply the global large solutions with highly oscillating initial data.
NASA Astrophysics Data System (ADS)
Yu, Yongtao; Guan, Haiyan; Zai, Dawei; Ji, Zheng
2016-02-01
This paper proposes a rotation-and-scale-invariant method for detecting airplanes from high-resolution satellite images. To improve feature representation capability, a multi-layer feature generation model is created to produce high-order feature representations for local image patches through deep learning techniques. To effectively estimate airplane centroids, a Hough forest model is trained to learn mappings from high-order patch features to the probabilities of an airplane being present at specific locations. To handle airplanes with varying orientations, patch orientation is defined and integrated into the Hough forest to augment Hough voting. The scale invariance is achieved by using a set of scale factors embedded in the Hough forest. Quantitative evaluations on the images collected from Google Earth service show that the proposed method achieves a completeness, correctness, quality, and F1-measure of 0.968, 0.972, 0.942, and 0.970, respectively, in detecting airplanes with arbitrary orientations and sizes. Comparative studies also demonstrate that the proposed method outperforms the other three existing methods in accurately and completely detecting airplanes in high-resolution remotely sensed images.
Masotti, Matteo; Lanconelli, Nico; Campanini, Renato
2009-02-15
In this work, gray-scale invariant ranklet texture features are proposed for false positive reduction (FPR) in computer-aided detection (CAD) of breast masses. Two main considerations are at the basis of this proposal. First, false positive (FP) marks surviving our previous CAD system seem to be characterized by specific texture properties that can be used to discriminate them from masses. Second, our previous CAD system achieves invariance to linear/nonlinear monotonic gray-scale transformations by encoding regions of interest into ranklet images through the ranklet transform, an image transformation similar to the wavelet transform, yet dealing with pixels' ranks rather than with their gray-scale values. Therefore, the new FPR approach proposed herein defines a set of texture features which are calculated directly from the ranklet images corresponding to the regions of interest surviving our previous CAD system, hence, ranklet texture features; then, a support vector machine (SVM) classifier is used for discrimination. As a result of this approach, texture-based information is used to discriminate FP marks surviving our previous CAD system; at the same time, invariance to linear/nonlinear monotonic gray-scale transformations of the new CAD system is guaranteed, as ranklet texture features are calculated from ranklet images that have this property themselves by construction. To emphasize the gray-scale invariance of both the previous and new CAD systems, training and testing are carried out without any in-between parameters' adjustment on mammograms having different gray-scale dynamics; in particular, training is carried out on analog digitized mammograms taken from a publicly available digital database, whereas testing is performed on full-field digital mammograms taken from an in-house database. Free-response receiver operating characteristic (FROC) curve analysis of the two CAD systems demonstrates that the new approach achieves a higher reduction of FP marks
Min-Chun Yang; Woo Kyung Moon; Wang, Yu-Chiang Frank; Min Sun Bae; Chiun-Sheng Huang; Jeon-Hor Chen; Ruey-Feng Chang
2013-12-01
Computer-aided diagnosis (CAD) systems in gray-scale breast ultrasound images have the potential to reduce unnecessary biopsy of breast masses. The purpose of our study is to develop a robust CAD system based on the texture analysis. First, gray-scale invariant features are extracted from ultrasound images via multi-resolution ranklet transform. Thus, one can apply linear support vector machines (SVMs) on the resulting gray-level co-occurrence matrix (GLCM)-based texture features for discriminating the benign and malignant masses. To verify the effectiveness and robustness of the proposed texture analysis, breast ultrasound images obtained from three different platforms are evaluated based on cross-platform training/testing and leave-one-out cross-validation (LOO-CV) schemes. We compare our proposed features with those extracted by wavelet transform in terms of receiver operating characteristic (ROC) analysis. The AUC values derived from the area under the curve for the three databases via ranklet transform are 0.918 (95% confidence interval [CI], 0.848 to 0.961), 0.943 (95% CI, 0.906 to 0.968), and 0.934 (95% CI, 0.883 to 0.961), respectively, while those via wavelet transform are 0.847 (95% CI, 0.762 to 0.910), 0.922 (95% CI, 0.878 to 0.958), and 0.867 (95% CI, 0.798 to 0.914), respectively. Experiments with cross-platform training/testing scheme between each database reveal that the diagnostic performance of our texture analysis using ranklet transform is less sensitive to the sonographic ultrasound platforms. Also, we adopt several co-occurrence statistics in terms of quantization levels and orientations (i.e., descriptor settings) for computing the co-occurrence matrices with 0.632+ bootstrap estimators to verify the use of the proposed texture analysis. These experiments suggest that the texture analysis using multi-resolution gray-scale invariant features via ranklet transform is useful for designing a robust CAD system.
Zorick, Todd; Mandelkern, Mark A
2015-01-01
Electroencephalography (EEG) is typically viewed through the lens of spectral analysis. Recently, multiple lines of evidence have demonstrated that the underlying neuronal dynamics are characterized by scale-free avalanches. These results suggest that techniques from statistical physics may be used to analyze EEG signals. We utilized a publicly available database of fourteen subjects with waking and sleep stage 2 EEG tracings per subject, and observe that power-law dynamics of critical-state neuronal avalanches are not sufficient to fully describe essential features of EEG signals. We hypothesized that this could reflect the phenomenon of discrete scale invariance (DSI) in EEG large voltage deflections (LVDs) as being more prominent in waking consciousness. We isolated LVDs, and analyzed logarithmically transformed LVD size probability density functions (PDF) to assess for DSI. We find evidence of increased DSI in waking, as opposed to sleep stage 2 consciousness. We also show that the signatures of DSI are specific for EEG LVDs, and not a general feature of fractal simulations with similar statistical properties to EEG. Removing only LVDs from waking EEG produces a reduction in power in the alpha and beta frequency bands. These findings may represent a new insight into the understanding of the cortical dynamics underlying consciousness.
NASA Astrophysics Data System (ADS)
Paganelli, Chiara; Peroni, Marta; Riboldi, Marco; Sharp, Gregory C.; Ciardo, Delia; Alterio, Daniela; Orecchia, Roberto; Baroni, Guido
2013-01-01
Adaptive radiation therapy (ART) aims at compensating for anatomic and pathological changes to improve delivery along a treatment fraction sequence. Current ART protocols require time-consuming manual updating of all volumes of interest on the images acquired during treatment. Deformable image registration (DIR) and contour propagation stand as a state of the ART method to automate the process, but the lack of DIR quality control methods hinder an introduction into clinical practice. We investigated the scale invariant feature transform (SIFT) method as a quantitative automated tool (1) for DIR evaluation and (2) for re-planning decision-making in the framework of ART treatments. As a preliminary test, SIFT invariance properties at shape-preserving and deformable transformations were studied on a computational phantom, granting residual matching errors below the voxel dimension. Then a clinical dataset composed of 19 head and neck ART patients was used to quantify the performance in ART treatments. For the goal (1) results demonstrated SIFT potential as an operator-independent DIR quality assessment metric. We measured DIR group systematic residual errors up to 0.66 mm against 1.35 mm provided by rigid registration. The group systematic errors of both bony and all other structures were also analyzed, attesting the presence of anatomical deformations. The correct automated identification of 18 patients who might benefit from ART out of the total 22 cases using SIFT demonstrated its capabilities toward goal (2) achievement.
NASA Astrophysics Data System (ADS)
Soundrapandiyan, Rajkumar; Chandra Mouli, P. V. S. S. R.
2016-09-01
In this paper, a novel and robust rotation and scale invariant structuring elements based descriptor (RSSED) for pedestrian classification in infrared (IR) images is proposed. In addition, a segmentation method using difference of Gaussian (DoG) and horizontal intensity projection is proposed. The three major steps are moving object segmentation, feature extraction and classification of objects as pedestrian or non-pedestrian. The segmentation result is used to extract the RSSED feature descriptor. To extract features, the segmentation result is encoded using local directional pattern (LDP). This helps in the identification of local textural patterns. The LDP encoded image is further quantized adaptively to four levels. Finally the proposed RSSED is used to formalize the descriptor from the quantized image. Support vector machine is employed for classification of the moving objects in a given IR image into pedestrian and non-pedestrian classes. The segmentation results shows the robustness in extracting the moving objects. The classification results obtained from SVM classifier shows the efficacy of the proposed method.
Nouri, Hamideh; Anderson, Sharolyn; Sutton, Paul; Beecham, Simon; Nagler, Pamela; Jarchow, Christopher J; Roberts, Dar A
2017-04-15
This research addresses the question as to whether or not the Normalised Difference Vegetation Index (NDVI) is scale invariant (i.e. constant over spatial aggregation) for pure pixels of urban vegetation. It has been long recognized that there are issues related to the modifiable areal unit problem (MAUP) pertaining to indices such as NDVI and images at varying spatial resolutions. These issues are relevant to using NDVI values in spatial analyses. We compare two different methods of calculation of a mean NDVI: 1) using pixel values of NDVI within feature/object boundaries and 2) first calculating the mean red and mean near-infrared across all feature pixels and then calculating NDVI. We explore the nature and magnitude of these differences for images taken from two sensors, a 1.24m resolution WorldView-3 and a 0.1m resolution digital aerial image. We apply these methods over an urban park located in the Adelaide Parklands of South Australia. We demonstrate that the MAUP is not an issue for calculation of NDVI within a sensor for pure urban vegetation pixels. This may prove useful for future rule-based monitoring of the ecosystem functioning of green infrastructure.
NASA Technical Reports Server (NTRS)
Sohrab, Siavash H.; Pitch, Nancy (Technical Monitor)
1999-01-01
A scale-invariant statistical theory of fields is presented that leads to invariant definition of density, velocity, temperature, and pressure, The definition of Boltzmann constant is introduced as k(sub k) = m(sub k)v(sub k)c = 1.381 x 10(exp -23) J x K(exp -1), suggesting that the Kelvin absolute temperature scale is equivalent to a length scale. Two new state variables called the reversible heat Q(sub rev) = TS and the reversible work W(sub rev) = PV are introduced. The modified forms of the first and second law of thermodynamics are presented. The microscopic definition of heat (work) is presented as the kinetic energy due to the random (peculiar) translational, rotational, and pulsational motions. The Gibbs free energy of an element at scale Beta is identified as the total system energy at scale (Beta-1), thus leading to an invariant form of the first law of thermodynamics U(sub Beta) = Q(sub Beta) - W(sub Beta) +N(e3)U(sub Beta-1).
Zorick, Todd; Mandelkern, Mark A.
2015-01-01
Electroencephalography (EEG) is typically viewed through the lens of spectral analysis. Recently, multiple lines of evidence have demonstrated that the underlying neuronal dynamics are characterized by scale-free avalanches. These results suggest that techniques from statistical physics may be used to analyze EEG signals. We utilized a publicly available database of fourteen subjects with waking and sleep stage 2 EEG tracings per subject, and observe that power-law dynamics of critical-state neuronal avalanches are not sufficient to fully describe essential features of EEG signals. We hypothesized that this could reflect the phenomenon of discrete scale invariance (DSI) in EEG large voltage deflections (LVDs) as being more prominent in waking consciousness. We isolated LVDs, and analyzed logarithmically transformed LVD size probability density functions (PDF) to assess for DSI. We find evidence of increased DSI in waking, as opposed to sleep stage 2 consciousness. We also show that the signatures of DSI are specific for EEG LVDs, and not a general feature of fractal simulations with similar statistical properties to EEG. Removing only LVDs from waking EEG produces a reduction in power in the alpha and beta frequency bands. These findings may represent a new insight into the understanding of the cortical dynamics underlying consciousness. PMID:26696860
Nouri, Hamideh; Anderson, Sharolyn; Sutton, Paul; Beecham, Simon; Nagler, Pamela L.; Jarchow, Christopher J; Roberts, Dar A.
2017-01-01
This research addresses the question as to whether or not the Normalised Difference Vegetation Index (NDVI) is scale invariant (i.e. constant over spatial aggregation) for pure pixels of urban vegetation. It has been long recognized that there are issues related to the modifiable areal unit problem (MAUP) pertaining to indices such as NDVI and images at varying spatial resolutions. These issues are relevant to using NDVI values in spatial analyses. We compare two different methods of calculation of a mean NDVI: 1) using pixel values of NDVI within feature/object boundaries and 2) first calculating the mean red and mean near-infrared across all feature pixels and then calculating NDVI. We explore the nature and magnitude of these differences for images taken from two sensors, a 1.24 m resolution WorldView-3 and a 0.1 m resolution digital aerial image. We apply these methods over an urban park located in the Adelaide Parklands of South Australia. We demonstrate that the MAUP is not an issue for calculation of NDVI within a sensor for pure urban vegetation pixels. This may prove useful for future rule-based monitoring of the ecosystem functioning of green infrastructure.
The social brain: scale-invariant layering of Erdős-Rényi networks in small-scale human societies.
Harré, Michael S; Prokopenko, Mikhail
2016-05-01
The cognitive ability to form social links that can bind individuals together into large cooperative groups for safety and resource sharing was a key development in human evolutionary and social history. The 'social brain hypothesis' argues that the size of these social groups is based on a neurologically constrained capacity for maintaining long-term stable relationships. No model to date has been able to combine a specific socio-cognitive mechanism with the discrete scale invariance observed in ethnographic studies. We show that these properties result in nested layers of self-organizing Erdős-Rényi networks formed by each individual's ability to maintain only a small number of social links. Each set of links plays a specific role in the formation of different social groups. The scale invariance in our model is distinct from previous 'scale-free networks' studied using much larger social groups; here, the scale invariance is in the relationship between group sizes, rather than in the link degree distribution. We also compare our model with a dominance-based hierarchy and conclude that humans were probably egalitarian in hunter-gatherer-like societies, maintaining an average maximum of four or five social links connecting all members in a largest social network of around 132 people.
NASA Astrophysics Data System (ADS)
Hanel, R.; Thurner, S.; Tsallis, C.
2009-11-01
Extremization of the Boltzmann-Gibbs (BG) entropy S_{BG}=-kint dx p(x) ln p(x) under appropriate norm and width constraints yields the Gaussian distribution pG(x) ∝e-βx. Also, the basic solutions of the standard Fokker-Planck (FP) equation (related to the Langevin equation with additive noise), as well as the Central Limit Theorem attractors, are Gaussians. The simplest stochastic model with such features is N ↦∞ independent binary random variables, as first proved by de Moivre and Laplace. What happens for strongly correlated random variables? Such correlations are often present in physical situations as e.g. systems with long range interactions or memory. Frequently q-Gaussians, pq(x) ∝[1-(1-q)βx2]1/(1-q) [p1(x)=pG(x)] become observed. This is typically so if the Langevin equation includes multiplicative noise, or the FP equation to be nonlinear. Scale-invariance, e.g. exchangeable binary stochastic processes, allow a systematical analysis of the relation between correlations and non-Gaussian distributions. In particular, a generalized stochastic model yielding q-Gaussians for all (q ≠ 1) was missing. This is achieved here by using the Laplace-de Finetti representation theorem, which embodies strict scale-invariance of interchangeable random variables. We demonstrate that strict scale invariance together with q-Gaussianity mandates the associated extensive entropy to be BG.
NASA Astrophysics Data System (ADS)
Sonnino, Giorgio; Cardinali, Alessandro; Steinbrecher, Gyorgy; Peeters, Philippe; Sonnino, Alberto; Nardone, Pasquale
2013-12-01
We derive the expression of the reference distribution function for magnetically confined plasmas far from the thermodynamic equilibrium. The local equilibrium state is fixed by imposing the minimum entropy production theorem and the maximum entropy (MaxEnt) principle, subject to scale invariance restrictions. After a short time, the plasma reaches a state close to the local equilibrium. This state is referred to as the reference state. The aim of this Letter is to determine the reference distribution function (RDF) when the local equilibrium state is defined by the above mentioned principles. We prove that the RDF is the stationary solution of a generic family of stochastic processes corresponding to an universal Landau-type equation with white parametric noise. As an example of application, we consider a simple, fully ionized, magnetically confined plasmas, with auxiliary Ohmic heating. The free parameters are linked to the transport coefficients of the magnetically confined plasmas, by the kinetic theory.
NASA Astrophysics Data System (ADS)
Fu, Yi-Jia; Jiang, Chun; Lv, Chong; Wan, Feng; Sang, Hai-Bo; Xie, Bai-Song
2016-11-01
The Thomson backscatter spectra by an electron moving in the resonance acceleration regime are derived analytically and computed numerically in the simultaneous presence of a superintense laser field and a strong uniform magnetic field. The dependences of fundamental frequency of harmonic spectra on the laser intensity and magnetic resonance parameter are examined carefully. By calculating the emission of a single electron in a circularly polarized laser field of plane-wave form and a constant external magnetic field, the scale invariance of the radiation spectra is evident in terms of harmonic orders. The scaling law of backscattered spectra is exhibited remarkably for the laser intensity as well as for the initial axial momentum of the electron when the cyclotron frequency of the electron approaches the laser frequency. The results indicate that the magnetic resonance parameter plays an important role in the strength of emission. And the found rich features of backscattering spectra may be useful to the tunability of the radiation source.
Desbuquois, Rémi; Yefsah, Tarik; Chomaz, Lauriane; Weitenberg, Christof; Corman, Laura; Nascimbène, Sylvain; Dalibard, Jean
2014-07-11
We present a general "fit-free" method for measuring the equation of state (EoS) of a scale-invariant gas. This method, which is inspired from the procedure introduced by Ku et al. [Science 335, 563 (2012)] for the unitary three-dimensional Fermi gas, provides a general formalism which can be readily applied to any quantum gas in a known trapping potential, in the frame of the local density approximation. We implement this method on a weakly interacting two-dimensional Bose gas across the Berezinskii-Kosterlitz-Thouless transition and determine its EoS with unprecedented accuracy in the critical region. Our measurements provide an important experimental benchmark for classical-field approaches which are believed to accurately describe quantum systems in the weakly interacting but nonperturbative regime.
ERIC Educational Resources Information Center
Pottawattamie County School System, Council Bluffs, IA.
The 15 occupational clusters (transportation, fine arts and humanities, communications and media, personal service occupations, construction, hospitality and recreation, health occupations, marine science occupations, consumer and homemaking-related occupations, agribusiness and natural resources, environment, public service, business and office…
Asymptotically hyperbolic connections
NASA Astrophysics Data System (ADS)
Fine, Joel; Herfray, Yannick; Krasnov, Kirill; Scarinci, Carlos
2016-09-01
General relativity in four-dimensions can be equivalently described as a dynamical theory of {SO}(3)˜ {SU}(2)-connections rather than metrics. We introduce the notion of asymptotically hyperbolic connections, and work out an analogue of the Fefferman-Graham expansion in the language of connections. As in the metric setup, one can solve the arising ‘evolution’ equations order by order in the expansion in powers of the radial coordinate. The solution in the connection setting is arguably simpler, and very straightforward algebraic manipulations allow one to see how the unconstrained by Einstein equations ‘stress-energy tensor’ appears at third order in the expansion. Another interesting feature of the connection formulation is that the ‘counter terms’ required in the computation of the renormalised volume all combine into the Chern-Simons functional of the restriction of the connection to the boundary. As the Chern-Simons invariant is only defined modulo large gauge transformations, the requirement that the path integral over asymptotically hyperbolic connections is well-defined requires the cosmological constant to be quantised. Finally, in the connection setting one can deform the 4D Einstein condition in an interesting way, and we show that asymptotically hyperbolic connection expansion is universal and valid for any of the deformed theories.
NASA Astrophysics Data System (ADS)
Ghanmi, Hanen; Bargaoui, Zoubeida; Mallet, Cécile
2016-10-01
Usually, networks of daily rainfall raingauges have a higher spatial cover than tippet bucket raingauges networks. Consequently, it would be of high interest to make use of daily rainfall information to asses IDF curves for unobserved locations. The present work proposes achieving this goal by using the assumption of simple scaling invariance. Indeed, series observed over sufficiently long periods for 10 tippet bucket raingauge, allowed us to test the hypothesis of simple scaling of annual maximum rainfall intensities in northern Tunisia. This assumption, combined with Gumbel model of maximum rainfall intensities allowed us to develop a methodology to estimate IDF curves from the daily rainfall totals. In fact, a regionalization formula which involves the percentile 90% of the annual maximum daily rainfall was developed and validated. This regionalization formula applied to daily data of 25 rainfall stations in the sub area of Tunis region, combined with the assumption of simple scaling has enabled us to develop Intensity Duration Area Frequency (IDAF) curves for Tunis area.
NASA Astrophysics Data System (ADS)
Ho, Pei-Ming
2017-04-01
Following earlier works on the KMY model of black-hole formation and evaporation, we construct the metric for a matter sphere in gravitational collapse, with the back-reaction of pre-Hawking radiation taken into consideration. The mass distribution and collapsing velocity of the matter sphere are allowed to have an arbitrary radial dependence. We find that a generic gravitational collapse asymptote to a universal configuration which resembles a black hole but without horizon. This approach clarifies several misunderstandings about black-hole formation and evaporation, and provides a new model for black-hole-like objects in the universe.
Asymptotically flat multiblack lenses
NASA Astrophysics Data System (ADS)
Tomizawa, Shinya; Okuda, Taika
2017-03-01
We present an asymptotically flat and stationary multiblack lens solution with biaxisymmetry of U (1 )×U (1 ) as a supersymmetric solution in the five-dimensional minimal ungauged supergravity. We show that the spatial cross section of each degenerate Killing horizon admits different lens space topologies of L (n ,1 )=S3/Zn as well as a sphere S3. Moreover, we show that, in contrast to the higher-dimensional Majumdar-Papapetrou multiblack hole and multi-Breckenridge-Myers-Peet-Vafa (BMPV) black hole spacetime, the metric is smooth on each horizon even if the horizon topology is spherical.
Kawakami, Hayato; Mitsuda, Eiji; Nambu, Yasusada; Tomimatsu, Akira
2009-07-15
In considering the gravitational collapse of matter, it is an important problem to clarify what kind of conditions leads to the formation of naked singularity. For this purpose, we apply the 1+3 orthonormal frame formalism introduced by Uggla et al. to the spherically symmetric gravitational collapse of a perfect fluid. This formalism allows us to construct an autonomous system of evolution and constraint equations for scale-invariant dynamical variables normalized by the volume expansion rate of the timelike orthonormal frame vector. We investigate the asymptotic evolution of such dynamical variables towards the formation of a central singularity and present a conjecture that the steep spatial gradient for the normalized density function is a characteristic of the naked singularity formation.
Thermodynamics of Asymptotically Conical Geometries.
Cvetič, Mirjam; Gibbons, Gary W; Saleem, Zain H
2015-06-12
We study the thermodynamical properties of a class of asymptotically conical geometries known as "subtracted geometries." We derive the mass and angular momentum from the regulated Komar integral and the Hawking-Horowitz prescription and show that they are equivalent. By deriving the asymptotic charges, we show that the Smarr formula and the first law of thermodynamics hold. We also propose an analog of Christodulou-Ruffini inequality. The analysis can be generalized to other asymptotically conical geometries.
Asymptotic symmetries on Killing horizons
NASA Astrophysics Data System (ADS)
Koga, Jun-Ichirou
2001-12-01
We investigate asymptotic symmetries regularly defined on spherically symmetric Killing horizons in Einstein theory with or without the cosmological constant. These asymptotic symmetries are described by asymptotic Killing vectors, along which the Lie derivatives of perturbed metrics vanish on a Killing horizon. We derive the general form of the asymptotic Killing vectors and find that the group of asymptotic symmetries consists of rigid O(3) rotations of a horizon two-sphere and supertranslations along the null direction on the horizon, which depend arbitrarily on the null coordinate as well as the angular coordinates. By introducing the notion of asymptotic Killing horizons, we also show that local properties of Killing horizons are preserved not only under diffeomorphisms but also under nontrivial transformations generated by the asymptotic symmetry group. Although the asymptotic symmetry group contains the Diff(S1) subgroup, which results from supertranslations dependent only on the null coordinate, it is shown that the Poisson brackets algebra of the conserved charges conjugate to asymptotic Killing vectors does not acquire nontrivial central charges. Finally, by considering extended symmetries, we discuss the fact that unnatural reduction of the symmetry group is necessary in order to obtain the Virasoro algebra with nontrivial central charges, which is not justified when we respect the spherical symmetry of Killing horizons.
Asymptotically safe grand unification
NASA Astrophysics Data System (ADS)
Bajc, Borut; Sannino, Francesco
2016-12-01
Phenomenologically appealing supersymmetric grand unified theories have large gauge representations and thus are not asymptotically free. Their ultraviolet validity is limited by the appearance of a Landau pole well before the Planck scale. One could hope that these theories save themselves, before the inclusion of gravity, by generating an interacting ultraviolet fixed point, similar to the one recently discovered in non-supersymmetric gauge-Yukawa theories. Employing a-maximization, a-theorem, unitarity bounds, as well as positivity of other central charges we nonperturbatively rule out this possibility for a broad class of prime candidates of phenomenologically relevant supersymmetric grand unified theories. We also uncover candidates passing these tests, which have either exotic matter or contain one field decoupled from the superpotential. The latter class of theories contains a model with the minimal matter content required by phenomenology.
... working with laboratory animals or with powdered natural rubber latex gloves have developed occupational asthma. Occupational asthma ... spray painting, insulation installation and in manufacturing plastics, rubber and foam. These chemicals can cause occupational asthma ...
Occupancy in continuous habitat
Efford, Murray G.; Dawson, Deanna K.
2012-01-01
The probability that a site has at least one individual of a species ('occupancy') has come to be widely used as a state variable for animal population monitoring. The available statistical theory for estimation when detection is imperfect applies particularly to habitat patches or islands, although it is also used for arbitrary plots in continuous habitat. The probability that such a plot is occupied depends on plot size and home-range characteristics (size, shape and dispersion) as well as population density. Plot size is critical to the definition of occupancy as a state variable, but clear advice on plot size is missing from the literature on the design of occupancy studies. We describe models for the effects of varying plot size and home-range size on expected occupancy. Temporal, spatial, and species variation in average home-range size is to be expected, but information on home ranges is difficult to retrieve from species presence/absence data collected in occupancy studies. The effect of variable home-range size is negligible when plots are very large (>100 x area of home range), but large plots pose practical problems. At the other extreme, sampling of 'point' plots with cameras or other passive detectors allows the true 'proportion of area occupied' to be estimated. However, this measure equally reflects home-range size and density, and is of doubtful value for population monitoring or cross-species comparisons. Plot size is ill-defined and variable in occupancy studies that detect animals at unknown distances, the commonest example being unlimited-radius point counts of song birds. We also find that plot size is ill-defined in recent treatments of "multi-scale" occupancy; the respective scales are better interpreted as temporal (instantaneous and asymptotic) rather than spatial. Occupancy is an inadequate metric for population monitoring when it is confounded with home-range size or detection distance.
... Names Asthma - occupational exposure; Irritant-induced reactive airways disease Images Spirometry Respiratory system References Lemiere C, Vandenplas O. Occupational allergy and asthma. In: Adkinson NF Jr., Bochner ...
Asymptotic Parachute Performance Sensitivity
NASA Technical Reports Server (NTRS)
Way, David W.; Powell, Richard W.; Chen, Allen; Steltzner, Adam D.
2006-01-01
In 2010, the Mars Science Laboratory mission will pioneer the next generation of robotic Entry, Descent, and Landing systems by delivering the largest and most capable rover to date to the surface of Mars. In addition to landing more mass than any other mission to Mars, Mars Science Laboratory will also provide scientists with unprecedented access to regions of Mars that have been previously unreachable. By providing an Entry, Descent, and Landing system capable of landing at altitudes as high as 2 km above the reference gravitational equipotential surface, or areoid, as defined by the Mars Orbiting Laser Altimeter program, Mars Science Laboratory will demonstrate sufficient performance to land on 83% of the planet s surface. By contrast, the highest altitude landing to date on Mars has been the Mars Exploration Rover at 1.3 km below the areoid. The coupling of this improved altitude performance with latitude limits as large as 60 degrees off of the equator and a precise delivery to within 10 km of a surface target, will allow the science community to select the Mars Science Laboratory landing site from thousands of scientifically interesting possibilities. In meeting these requirements, Mars Science Laboratory is extending the limits of the Entry, Descent, and Landing technologies qualified by the Mars Viking, Mars Pathfinder, and Mars Exploration Rover missions. Specifically, the drag deceleration provided by a Viking-heritage 16.15 m supersonic Disk-Gap-Band parachute in the thin atmosphere of Mars is insufficient, at the altitudes and ballistic coefficients under consideration by the Mars Science Laboratory project, to maintain necessary altitude performance and timeline margin. This paper defines and discusses the asymptotic parachute performance observed in Monte Carlo simulation and performance analysis and its effect on the Mars Science Laboratory Entry, Descent, and Landing architecture.
Asymptotic dynamics of monopole walls
NASA Astrophysics Data System (ADS)
Cross, R.
2015-08-01
We determine the asymptotic dynamics of the U(N) doubly periodic BPS monopole in Yang-Mills-Higgs theory, called a monopole wall, by exploring its Higgs curve using the Newton polytope and amoeba. In particular, we show that the monopole wall splits into subwalls when any of its moduli become large. The long-distance gauge and Higgs field interactions of these subwalls are Abelian, allowing us to derive an asymptotic metric for the monopole wall moduli space.
Polynomial Asymptotes of the Second Kind
ERIC Educational Resources Information Center
Dobbs, David E.
2011-01-01
This note uses the analytic notion of asymptotic functions to study when a function is asymptotic to a polynomial function. Along with associated existence and uniqueness results, this kind of asymptotic behaviour is related to the type of asymptote that was recently defined in a more geometric way. Applications are given to rational functions and…
Asymptotic conditions and conserved quantities
Koul, R.K.
1990-01-01
Two problems have been investigated in this dissertation. The first one deals with the relationship between stationary space-times which are flat at null infinity and stationary space-times which are asymptotic flat at space-like infinity. It is shown that the stationary space-times which are asymptotically flat, in the Penrose sense, at null infinity, are asymptotically flat at space-like infinity in the Geroch sense and metric at space like infinity is at least C{sup 1}. In the converse it is shown that the stationary space-times which are asymptotically flat at space like infinity, in the Beig sense, are asymptotically flat at null infinity in the Penrose sense. The second problem addressed deals with the theories of arbitrary dimensions. The theories treated are the ones which have fiber bundle structure, outside some compact region. For these theories the criterion for the choice of the background metric is specified, and the boundary condition for the initial data set (q{sub ab}, P{sup ab}) is given in terms of the background metric. Having these boundary conditions it is shown that the symplectic structure and the constraint functionals are well defined. The conserved quantities associated with internal Killing vector fields are specified. Lastly the energy relative to a fixed background and the total energy of the theory have been given. It is also shown that the total energy of the theory is independent of the choice of the background.
ERIC Educational Resources Information Center
Occupational Outlook Quarterly, 2012
2012-01-01
When choosing a career, jobseekers often want to know which occupations offer the best prospects. Generally, occupations that have rapid job growth, many new jobs, or many job openings--and good wages--promise better opportunities. This paper shows how employment in particular occupations is projected to change from 2010 to 2020. It presents…
Asymptotic Rayleigh instantaneous unit hydrograph
Troutman, B.M.; Karlinger, M.R.
1988-01-01
The instantaneous unit hydrograph for a channel network under general linear routing and conditioned on the network magnitude, N, tends asymptotically, as N grows large, to a Rayleigh probability density function. This behavior is identical to that of the width function of the network, and is proven under the assumption that the network link configuration is topologically random and the link hydraulic and geometric properties are independent and identically distributed random variables. The asymptotic distribution depends only on a scale factor, {Mathematical expression}, where ?? is a mean link wave travel time. ?? 1988 Springer-Verlag.
Wedge locality and asymptotic commutativity
NASA Astrophysics Data System (ADS)
Soloviev, M. A.
2014-05-01
In this paper, we study twist deformed quantum field theories obtained by combining the Wightman axiomatic approach with the idea of spacetime noncommutativity. We prove that the deformed fields with deformation parameters of opposite sign satisfy the condition of mutual asymptotic commutativity, which was used earlier in nonlocal quantum field theory as a substitute for relative locality. We also present an improved proof of the wedge localization property discovered for the deformed fields by Grosse and Lechner, and we show that the deformation leaves the asymptotic behavior of the vacuum expectation values in spacelike directions substantially unchanged.
Asymptotic Normality of Quadratic Estimators.
Robins, James; Li, Lingling; Tchetgen, Eric; van der Vaart, Aad
2016-12-01
We prove conditional asymptotic normality of a class of quadratic U-statistics that are dominated by their degenerate second order part and have kernels that change with the number of observations. These statistics arise in the construction of estimators in high-dimensional semi- and non-parametric models, and in the construction of nonparametric confidence sets. This is illustrated by estimation of the integral of a square of a density or regression function, and estimation of the mean response with missing data. We show that estimators are asymptotically normal even in the case that the rate is slower than the square root of the observations.
Hitting Time Asymptotics for Hard-Core Interactions on Grids
NASA Astrophysics Data System (ADS)
Nardi, F. R.; Zocca, A.; Borst, S. C.
2016-01-01
We consider the hard-core model with Metropolis transition probabilities on finite grid graphs and investigate the asymptotic behavior of the first hitting time between its two maximum-occupancy configurations in the low-temperature regime. In particular, we show how the order-of-magnitude of this first hitting time depends on the grid sizes and on the boundary conditions by means of a novel combinatorial method. Our analysis also proves the asymptotic exponentiality of the scaled hitting time and yields the mixing time of the process in the low-temperature limit as side-result. In order to derive these results, we extended the model-independent framework in Manzo et al. (J Stat Phys 115(1/2):591-642, 2004) for first hitting times to allow for a more general initial state and target subset.
Lorentzian proper vertex amplitude: Asymptotics
NASA Astrophysics Data System (ADS)
Engle, Jonathan; Vilensky, Ilya; Zipfel, Antonia
2016-09-01
In previous work, the Lorentzian proper vertex amplitude for a spin-foam model of quantum gravity was derived. In the present work, the asymptotics of this amplitude are studied in the semiclassical limit. The starting point of the analysis is an expression for the amplitude as an action integral with action differing from that in the Engle-Pereira-Rovelli-Livine (EPRL) case by an extra "projector" term. This extra term scales linearly with spins only in the asymptotic limit, and is discontinuous on a (lower dimensional) submanifold of the integration domain in the sense that its value at each such point depends on the direction of approach. New tools are introduced to generalize stationary phase methods to this case. For the case of boundary data which can be glued to a nondegenerate Lorentzian 4-simplex, the asymptotic limit of the amplitude is shown to equal the single Feynman term, showing that the extra term in the asymptotics of the EPRL amplitude has been eliminated.
Asymptotic screened hydrogenic radial integrals
NASA Technical Reports Server (NTRS)
Olsgaard, D. A.; Khan, F.; Khandelwal, G. S.
1988-01-01
The usefulness of the screened hydrogenic model for the transitions of the helium sequence is studied. The screened hydrogenic radial dipole integral for discrete-discrete transitions from the initial state to the final state is asymptotically expanded to the lowest order such that the final quantum number n approaches infinity. The analytical expression obtained is in terms of confluent hypergeometric functions.
Ramugondo, Elelwani L
2015-10-02
Occupational consciousness refers to ongoing awareness of the dynamics of hegemony and recognition that dominant practices are sustained through what people do every day, with implications for personal and collective health. The emergence of the construct in post-apartheid South Africa signifies the country's ongoing struggle with negotiating long-standing dynamics of power that were laid down during colonialism, and maintained under black majority rule. Consciousness, a key component of the new terminology, is framed from post-colonial perspectives - notably work by Biko and Fanon - and grounded in the philosophy of liberation, in order to draw attention to continuing unequal intersubjective relations that play out through human occupation. The paper also draws important links between occupational consciousness and other related constructs, namely occupational possibilities, occupational choice, occupational apartheid, and collective occupation. The use of the term 'consciousness' in sociology, with related or different meanings, is also explored. Occupational consciousness is then advanced as a critical notion that frames everyday doing as a potentially liberating response to oppressive social structures. This paper advances theorizing as a scholarly practice in occupational science, and could potentially expand inter or transdisciplinary work for critical conceptualizations of human occupation.
Ramugondo, Elelwani L.
2015-01-01
Occupational consciousness refers to ongoing awareness of the dynamics of hegemony and recognition that dominant practices are sustained through what people do every day, with implications for personal and collective health. The emergence of the construct in post-apartheid South Africa signifies the country’s ongoing struggle with negotiating long-standing dynamics of power that were laid down during colonialism, and maintained under black majority rule. Consciousness, a key component of the new terminology, is framed from post-colonial perspectives – notably work by Biko and Fanon – and grounded in the philosophy of liberation, in order to draw attention to continuing unequal intersubjective relations that play out through human occupation. The paper also draws important links between occupational consciousness and other related constructs, namely occupational possibilities, occupational choice, occupational apartheid, and collective occupation. The use of the term ‘consciousness’ in sociology, with related or different meanings, is also explored. Occupational consciousness is then advanced as a critical notion that frames everyday doing as a potentially liberating response to oppressive social structures. This paper advances theorizing as a scholarly practice in occupational science, and could potentially expand inter or transdisciplinary work for critical conceptualizations of human occupation. PMID:26549984
Asymptotic controllability and optimal control
NASA Astrophysics Data System (ADS)
Motta, M.; Rampazzo, F.
We consider a control problem where the state must approach asymptotically a target C while paying an integral cost with a non-negative Lagrangian l. The dynamics f is just continuous, and no assumptions are made on the zero level set of the Lagrangian l. Through an inequality involving a positive number p and a Minimum Restraint FunctionU=U(x) - a special type of Control Lyapunov Function - we provide a condition implying that (i) the system is asymptotically controllable, and (ii) the value function is bounded by U/p. The result has significant consequences for the uniqueness issue of the corresponding Hamilton-Jacobi equation. Furthermore it may be regarded as a first step in the direction of a feedback construction.
Composite operators in asymptotic safety
NASA Astrophysics Data System (ADS)
Pagani, Carlo; Reuter, Martin
2017-03-01
We study the role of composite operators in the asymptotic safety program for quantum gravity. By including in the effective average action an explicit dependence on new sources, we are able to keep track of operators which do not belong to the exact theory space and/or are normally discarded in a truncation. Typical examples are geometric operators such as volumes, lengths, or geodesic distances. We show that this setup allows us to investigate the scaling properties of various interesting operators via a suitable exact renormalization group equation. We test our framework in several settings including quantum Einstein gravity, the conformally reduced Einstein-Hilbert truncation, and two-dimensional quantum gravity. Finally, we briefly argue that our construction paves the way to approach observables in the asymptotic safety program.
Asymptotic safety goes on shell
NASA Astrophysics Data System (ADS)
Benedetti, Dario
2012-01-01
It is well known in quantum field theory that the off-shell effective action depends on the gauge choice and field parametrization used in calculating it. Nevertheless, the typical scheme in which the scenario of asymptotically safe gravity is investigated is an off-shell version of the functional renormalization group equation. Working with the Einstein-Hilbert truncation as a test bed, we develop a new scheme for the analysis of asymptotically safe gravity in which the on-shell part of the effective action is singled out and we show that the beta function for the essential coupling has no explicit gauge dependence. In order to reach our goal, we introduce several technical novelties, including a different decomposition of the metric fluctuations, a new implementation of the ghost sector and a new cut-off scheme. We find a nontrivial fixed point, with a value of the cosmological constant that is independent of the gauge-fixing parameters.
On asymptotically lacunary invariant statistical equivalent set sequences
NASA Astrophysics Data System (ADS)
Pancaroglu, Nimet; Nuray, Fatih; Savas, Ekrem
2013-10-01
In this paper, we define asymptotically invariant equivalence, strongly asymptotically invariant equivalence, asymptotically invariant statistical equivalence, asymptotically lacunary invariant statistical equivalence, strongly asymptotically lacunary invariant equivalence, asymptotically lacunary invariant equivalence (Wijsman sense) for sequences of sets. Also we investigate some relations between asymptotically lacunary invariant statistical equivalence and asymptotically invariant statistical equivalence for sequences of sets. We introduce some notions and theorems as follows, asymptotically lacunary invariant statistical equivalence, strongly asymptotically lacunary invariant equivalence, asymptotically lacunary invariant equivalence (Wijsman sense) for sequences of sets.
Grammer, Leslie C
2016-05-01
Occupational rhinitis (OR) involves nasal congestion, rhinorrhea, nasal itching, and/or sneezing resulting from workplace exposures. OR can have a significant negative effect on quality of life and productivity. OR can be divided into allergic or nonallergic subgroups based on the underlying pathogenesis. Certain occupational exposures place employees at greater risk for developing disease. Primary treatment is avoidance of implicated exposures. Antihistamines, saline rinses, and nasal steroids may be useful. OR can coexist with occupational asthma, and rhinitis symptoms have been reported to precede those of the lower respiratory tract. OR is has both medical and socioeconomic implications.
Occupational health problems occur at work or because of the kind of work you do. These problems can include ... by exposure to radiation Exposure to germs in health care settings Good job safety and prevention practices ...
Rico-Rosillo, Guadalupe; Cambray-Gutiérrez, Julio César; Vega-Robledo, Gloria Bertha
2015-01-01
The occupational asthma is the most common form of lung disease caused by factors that are attributed to a specific working environment in industrialized countries. It causes variable limitation of airflow and/or hyper-responsiveness of the airway due to contact with specific agents present in an atmosphere of work and not to stimuli found out of this place. It is recognized more and more frequently, and many agents are capable of causing occupational asthma by different pathophysiological mechanisms. More than 400 agents causing occupational asthma are known and every year new triggers are detected. Numerous factors contribute to the pathogenesis of occupational asthma induced chemically, including immunological, non-immunological mechanisms of epithelial damage, airway remodeling, oxidative stress, neurogenic inflammation as well as genetic factors. The most important risk factors for occupational asthma include: atopy, smoking and genetic factors. The diagnosis is based on the clinical history, skin tests, immunological tests and functional studies. The fundamental treatment is removing the worker from exposure as soon as possible. The advance in the knowledge of the pathogenesis of occupational asthma will importantly influence in the prevention and the management of this disease.
The maximum drag reduction asymptote
NASA Astrophysics Data System (ADS)
Choueiri, George H.; Hof, Bjorn
2015-11-01
Addition of long chain polymers is one of the most efficient ways to reduce the drag of turbulent flows. Already very low concentration of polymers can lead to a substantial drag and upon further increase of the concentration the drag reduces until it reaches an empirically found limit, the so called maximum drag reduction (MDR) asymptote, which is independent of the type of polymer used. We here carry out a detailed experimental study of the approach to this asymptote for pipe flow. Particular attention is paid to the recently observed state of elasto-inertial turbulence (EIT) which has been reported to occur in polymer solutions at sufficiently high shear. Our results show that upon the approach to MDR Newtonian turbulence becomes marginalized (hibernation) and eventually completely disappears and is replaced by EIT. In particular, spectra of high Reynolds number MDR flows are compared to flows at high shear rates in small diameter tubes where EIT is found at Re < 100. The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement n° [291734].
Asymptotically Free Gauge Theories. I
DOE R&D Accomplishments Database
Wilczek, Frank; Gross, David J.
1973-07-01
Asymptotically free gauge theories of the strong interactions are constructed and analyzed. The reasons for doing this are recounted, including a review of renormalization group techniques and their application to scaling phenomena. The renormalization group equations are derived for Yang-Mills theories. The parameters that enter into the equations are calculated to lowest order and it is shown that these theories are asymptotically free. More specifically the effective coupling constant, which determines the ultraviolet behavior of the theory, vanishes for large space-like momenta. Fermions are incorporated and the construction of realistic models is discussed. We propose that the strong interactions be mediated by a "color" gauge group which commutes with SU(3)xSU(3). The problem of symmetry breaking is discussed. It appears likely that this would have a dynamical origin. It is suggested that the gauge symmetry might not be broken, and that the severe infrared singularities prevent the occurrence of non-color singlet physical states. The deep inelastic structure functions, as well as the electron position total annihilation cross section are analyzed. Scaling obtains up to calculable logarithmic corrections, and the naive lightcone or parton model results follow. The problems of incorporating scalar mesons and breaking the symmetry by the Higgs mechanism are explained in detail.
Asymptotic density and effective negligibility
NASA Astrophysics Data System (ADS)
Astor, Eric P.
In this thesis, we join the study of asymptotic computability, a project attempting to capture the idea that an algorithm might work correctly in all but a vanishing fraction of cases. In collaboration with Hirschfeldt and Jockusch, broadening the original investigation of Jockusch and Schupp, we introduce dense computation, the weakest notion of asymptotic computability (requiring only that the correct answer is produced on a set of density 1), and effective dense computation, where every computation halts with either the correct answer or (on a set of density 0) a symbol denoting uncertainty. A few results make more precise the relationship between these notions and work already done with Jockusch and Schupp's original definitions of coarse and generic computability. For all four types of asymptotic computation, including generic computation, we demonstrate that non-trivial upper cones have measure 0, building on recent work of Hirschfeldt, Jockusch, Kuyper, and Schupp in which they establish this for coarse computation. Their result transfers to yield a minimal pair for relative coarse computation; we generalize their method and extract a similar result for relative dense computation (and thus for its corresponding reducibility). However, all of these notions of near-computation treat a set as negligible iff it has asymptotic density 0. Noting that this definition is not computably invariant, this produces some failures of intuition and a break with standard expectations in computability theory. For instance, as shown by Hamkins and Miasnikov, the halting problem is (in some formulations) effectively densely computable, even in polynomial time---yet this result appears fragile, as indicated by Rybalov. In independent work, we respond to this by strengthening the approach of Jockusch and Schupp to avoid such phenomena; specifically, we introduce a new notion of intrinsic asymptotic density, invariant under computable permutation, with rich relations to both
Asymptotic safety, emergence and minimal length
NASA Astrophysics Data System (ADS)
Percacci, Roberto; Vacca, Gian Paolo
2010-12-01
There seems to be a common prejudice that asymptotic safety is either incompatible with, or at best unrelated to, the other topics in the title. This is not the case. In fact, we show that (1) the existence of a fixed point with suitable properties is a promising way of deriving emergent properties of gravity, and (2) there is a sense in which asymptotic safety implies a minimal length. In doing so we also discuss possible signatures of asymptotic safety in scattering experiments.
Every composition operator is (mean) asymptotically Toeplitz
NASA Astrophysics Data System (ADS)
Shapiro, Joel H.
2007-09-01
Nazarov and Shapiro recently showed that, while composition operators on the Hardy space H2 can only trivially be Toeplitz, or even "Toeplitz plus compact," it is an interesting problem to determine which of them can be "asymptotically Toeplitz." I show here that if "asymptotically" is interpreted in, for example, the Cesaro (C,[alpha]) sense ([alpha]>0), then every composition operator on H2 becomes asymptotically Toeplitz.
Asymptotic and Fredholm representations of discrete groups
NASA Astrophysics Data System (ADS)
Manuilov, V. M.; Mishchenko, A. S.
1998-10-01
A C^*-algebra servicing the theory of asymptotic representations and its embedding into the Calkin algebra that induces an isomorphism of K_1-groups is constructed. As a consequence, it is shown that all vector bundles over the classifying space B\\pi that can be obtained by means of asymptotic representations of a discrete group \\pi can also be obtained by means of representations of the group \\pi \\times {\\mathbb Z} into the Calkin algebra. A generalization of the concept of Fredholm representation is also suggested, and it is shown that an asymptotic representation can be regarded as an asymptotic Fredholm representation.
Asymptotic expansions in nonlinear rotordynamics
NASA Technical Reports Server (NTRS)
Day, William B.
1987-01-01
This paper is an examination of special nonlinearities of the Jeffcott equations in rotordynamics. The immediate application of this analysis is directed toward understanding the excessive vibrations recorded in the LOX pump of the SSME during hot-firing ground testing. Deadband, side force, and rubbing are three possible sources of inducing nonlinearity in the Jeffcott equations. The present analysis initially reduces these problems to the same mathematical description. A special frequency, named the nonlinear natural frequency, is defined and used to develop the solutions of the nonlinear Jeffcott equations as singular asymptotic expansions. This nonlinear natural frequency, which is the ratio of the cross-stiffness and the damping, plays a major role in determining response frequencies.
Asymptotic invariants of homotopy groups
NASA Astrophysics Data System (ADS)
Manin, Fedor
We study the homotopy groups of a finite CW complex X via constraints on the geometry of representatives of their elements. For example, one can measure the "size" of alpha ∈ pi n (X) by the optimal Lipschitz constant or volume of a representative. By comparing the geometrical structure thus obtained with the algebraic structure of the group, one can define functions such as growth and distortion in pin(X), analogously to the way that such functions are studied in asymptotic geometric group theory. We provide a number of examples and techniques for studying these invariants, with a special focus on spaces with few rational homotopy groups. Our main theorem characterizes those X in which all non-torsion homotopy classes are undistorted, that is, their volume distortion functions, and hence also their Lipschitz distortion functions, are linear.
An asymptotic model of the F layer
NASA Astrophysics Data System (ADS)
Oliver, W. L.
2012-01-01
A model of the F layer of the ionosphere is presented that consists of a bottomside asymptote that ignores transport and a topside asymptote that ignores chemistry. The asymptotes connect at the balance height dividing the chemistry and transport regimes. A combination of these two asymptotes produces a good approximation to the true F layer. Analogously, a model of F layer response to an applied vertical drift is presented that consists of two asymptotic responses, one that ignores transport and one that ignores chemistry. The combination of these asymptotic responses produces a good approximation to the response of the true F layer. This latter response is identical to the “servo” response of Rishbeth et al. (1978), derived from the continuity equation. The asymptotic approach bypasses the continuity equation in favor of “force balance” arguments and so replaces a differential equation with simpler algebraic equations. This new approach provides a convenient and intuitive mean for first-order estimates of the change in F layer peak height and density in terms of changes in neutral density, composition, temperature, winds, and electric fields. It is applicable at midlatitudes and at magnetically quiet times at high latitudes. Forensic inverse relations are possible but are not unique. The validity of the asymptotic relations is shown through numerical simulation.
Einstein-Yang-Mills theory: Asymptotic symmetries
NASA Astrophysics Data System (ADS)
Barnich, Glenn; Lambert, Pierre-Henry
2013-11-01
Asymptotic symmetries of the Einstein-Yang-Mills system with or without cosmological constant are explicitly worked out in a unified manner. In agreement with a recent conjecture, one finds a Virasoro-Kac-Moody type algebra not only in three dimensions but also in the four-dimensional asymptotically flat case.
On SLλ(I)-asymptotically statistical equivalent sequences
NASA Astrophysics Data System (ADS)
Gumus, Hafize; Savas, Ekrem
2012-09-01
This paper presents the notion of SLλ(I)-asymptotically statistical equivalence which is a natural combination of asymptotic I-equivalence and λ-statistical equivalence. We find its relation to I-asymptotically statistical convergence, strong λI-asymptotically equivalence and strong Cesàro I-asymptotically equivalence.
Guidotti, T.L.; Goldsmith, D.F.
1986-09-01
When cancer is possibly related to occupation, the family physician's task is to put the matter in perspective by educating the patient and carefully documenting the appearance of the tumor and the patient's work history. Occasionally, physicians are the first to recognize new associations between chemicals and cancer and can help to bring hazards under control.
ERIC Educational Resources Information Center
Morris, William R.
Although fiscal support for occupational programs in California Community Colleges is provided primarily by state and local district taxes, about ten percent of the total support is provided through federal sources. Federal regulations under the Vocational Education Act (VEA) require the recipients of federal funds to provide consultative,…
Detecting communities using asymptotical surprise
NASA Astrophysics Data System (ADS)
Traag, V. A.; Aldecoa, R.; Delvenne, J.-C.
2015-08-01
Nodes in real-world networks are repeatedly observed to form dense clusters, often referred to as communities. Methods to detect these groups of nodes usually maximize an objective function, which implicitly contains the definition of a community. We here analyze a recently proposed measure called surprise, which assesses the quality of the partition of a network into communities. In its current form, the formulation of surprise is rather difficult to analyze. We here therefore develop an accurate asymptotic approximation. This allows for the development of an efficient algorithm for optimizing surprise. Incidentally, this leads to a straightforward extension of surprise to weighted graphs. Additionally, the approximation makes it possible to analyze surprise more closely and compare it to other methods, especially modularity. We show that surprise is (nearly) unaffected by the well-known resolution limit, a particular problem for modularity. However, surprise may tend to overestimate the number of communities, whereas they may be underestimated by modularity. In short, surprise works well in the limit of many small communities, whereas modularity works better in the limit of few large communities. In this sense, surprise is more discriminative than modularity and may find communities where modularity fails to discern any structure.
Asymptotics of Simple Branching Populations
NASA Astrophysics Data System (ADS)
Huillet, Thierry; Kłopotowski, Andrzej; Porzio, Anna
1995-09-01
In this paper we study a simple deterministic tree structure: an initial individual generates a finite number of offspring, each of which has given integer valued lifetime, iterating the same procedure when dying. Three asymptotic distributions of this asynchronous deterministic branching procedure are considered: the generation distribution, the ability of individuals to generate offspring and the age distribution. Thermodynamic formalism is then developped to reveal the multifractal nature of the mass splitting associated to our process. On considère l'itération d'une structure déterministe arborescente selon laquelle un ancêtre engendre un nombre fini de descendants dont la durée de vie (à valeurs entières) est donnée. Dans un premier temps on s'intéresse aux trois distributions asymptotiques suivantes : répartition des générations, aptitude à engendrer des descendants et répartition selon l'âge. Ensuite nous développons le formalisme thermodynamique pour mettre en évidence le caractère multifractal de la scission d'une masse unitaire associée à cette arborescence.
Dynamics on Scale-Invariant Structures.
NASA Astrophysics Data System (ADS)
Christou, Alexis
Available from UMI in association with The British Library. Requires signed TDF. We investigate dynamical processes on random and regular fractals. The (static) problem of percolation in the semi -infinite plane introduces many pertinent ideas including real space renormalisation group (RSRG) fugacity transformations and scaling forms. We study the percolation probability to determine the surface critical behaviour and to establish exponent relations. The fugacity approach is generalised to study random walks on diffusion-limited aggregates (DLA). Using regular and random models, we calculate the walk dimensionality and demonstrate that it is consistent with a conjecture by Aharony and Stauffer. It is shown that the kinetically grown DNA is in a distinct dynamic universality class to lattice animals. Similarly, the speculation of Helman -Coniglio-Tsallis regarding diffusion on self-avoiding walks (SAWs) is shown to be incorrect. The results are corroborated by an exact enumeration analysis of the internal structure of SAWs. A 'spin' and field theoretic Hamiltonian formulation for the conformational and resistance properties of random walks is presented. We consider Gaussian random walks, SAWs, spiral SAWs and valence walks. We express resistive susceptibilities as correlation functions and hence epsilon-expansions are calculated for the resistance exponents. For SAWs, the local crosslinks are shown to be irrelevant and we calculate corrections to scaling. A scaling description is introduced into an equation -of-motion method in order to study spin wave damping in d-dimensional isotropic Heisenberg ferro-, antiferro- and ferri- magnets near p_{rm c} . Dynamic scaling is shown to be obeyed by the Lorentzian spin wave response function and lifetime. The ensemble of finite clusters and multicritical behaviour is also treated. In contrast, the relaxational dynamics of the dilute Anisotropic Heisenberg model is shown to violate conventional dynamic scaling near the percolation bicritical point but satisfies instead a singular scaling behaviour arising from activation of Bloch walls over percolation cluster energy barriers.
Chan-Yeung, M.; Grzybowski, S.
1976-01-01
Occupational asthma is probably much more common than is generally realized. Though many causes have been described, undoubtedly many more are yet to be recognized. One of the diagnostic difficulties lies in the fact that in most forms of this disease a late asthmatic reaction occurs in the evening rather than at work. The pathogenetic mechanisms differ in various forms of occupational asthma. In some, an immunologic mechanism is likely; in others, a "pharmacologic" action of the offending agent is implicated. Asthma due to inhalation of dusts of western red cedar, isocyanates, detergent enzymes and textiles is considered in detail. Periodic examination of workers at risk is of value for early diagnosis and prevention of irrversible airway obstruction. PMID:766943
Asymptotic unbounded root loci - Formulas and computation
NASA Technical Reports Server (NTRS)
Sastry, S. S.; Desoer, C. A.
1983-01-01
A new geometric way of computing the asymptotic behavior of unbounded root loci of a strictly proper linear time-invariant control system as loop gain goes to infinity is presented. Properties of certain restricted linear maps and nested restrictions of linear maps are developed, and formulas are obtained for the leading coefficient of the asymptotic values of the unbounded multivariable root loci are obtained in terms of eigenvalues of those maps. Published results and a certain simple null structure assumption are used to relate these asymptotic values to the structure at infinity of the Smith-McMillan form of the open loop transfer function. Explicit matrix formulas for the more abstract derived formulas are given and additional geometric insights are developed with orthogonal projections and singular value decomposition. Formulas for the pivots of the unbounded root loci are calculated and shown to have the same form as the coefficients of the unbounded asymptotic root loci.
On asymptotically generalized statistical equivalent set sequences
NASA Astrophysics Data System (ADS)
Savas, Ekrem
2013-10-01
In this paper we shall study the asymptotically λ-statistical equivalent (Wijsman sense) of multiple L. In addition to these definition, natural inclusion theorems shall also be presented. This approach has not been considered in any context before.
Occupational Therapy (For Parents)
... ON THIS TOPIC Who's Who in the Hospital Speech-Language Therapy Managing Home Health Care Physical Therapy Caring for a Seriously Ill Child Word! Occupational Therapist Word! Occupational Therapy Wheelchairs Going to an Occupational ...
Newman Taylor, A. J.
1988-01-01
Occupational asthma is important both as a potentially curable and preventable cause of asthma and as a model of adult onset asthma. It is induced by sensitization to a specific agent inhaled at work; for many of its causes, including inhaled proteins and the low molecular weight chemicals acid anhydrides and reactive dyes, it is probably IgE dependent. The risk of developing specific IgE and associated asthma is markedly increased in cigarette smokers, probably as a consequence of non-specific damage to the respiratory mucosa. Asthma caused by several agents, which include some of its most frequent causes, isocyanates, colophony and plicatic acid (Western Red Cedar) persists in some 50% of cases for years, and possibly indefinitely, after avoidance of exposure. The development of chronic symptomatic asthma seems particularly to occur in those with longer duration of symptomatic exposure. PMID:3074282
Chan-Yeung, M
1995-01-01
Many toxic compounds found in air emissions may induce bronchoconstriction. In the workplace, workers are exposed to these compounds, often in much higher concentrations. Some of these compounds act as sensitizers. Of these, some compounds induce asthma by producing specific IgE antibodies to the compound or its protein conjugate, while others induce asthma through yet unidentified immunologic mechanisms. Some compounds, when inhaled in high concentrations, act as irritants and produce bronchoconstriction probably by inducing acute airway inflammation. The latter condition is called Reactive Airways Dysfunction Syndrome (RADS) or irritant-induced asthma. Occupational asthma is an excellent model to study the pathogenesis and the natural history of adult onset asthma because the responsible agent can be identified, complete avoidance is possible, and exposure can be measured or estimated. PMID:8549481
Image processing occupancy sensor
Brackney, Larry J.
2016-09-27
A system and method of detecting occupants in a building automation system environment using image based occupancy detection and position determinations. In one example, the system includes an image processing occupancy sensor that detects the number and position of occupants within a space that has controllable building elements such as lighting and ventilation diffusers. Based on the position and location of the occupants, the system can finely control the elements to optimize conditions for the occupants, optimize energy usage, among other advantages.
Asymptotic wave propagation in excitable media.
Bernus, Olivier; Vigmond, Edward
2015-07-01
Wave shape and velocity are important issues in reaction-diffusion systems, and are often the result of competition in media with heterogeneous conduction properties. Asymptotic wave front propagation at maximal conduction velocity has been previously reported in the context of anisotropic cardiac tissue, but it is unknown whether this is a universal property of excitable tissues where conduction velocity can be locally modulated by mechanisms other than anisotropy. Here, we investigate the impact of conduction heterogeneities and boundary effects on wave propagation in excitable media. Following a theoretical analysis, we find that wave-front cusps occur where local velocity is reduced and that asymptotic wave fronts propagate at the maximal translational conduction velocity. Simulations performed in different reaction-diffusion systems, including cardiac tissue, confirm our theoretical findings. We conclude that this property can be found in a wide range of reaction-diffusion systems with excitable dynamics and that asymptotic wave-front shapes can be predicted.
Asymptotics of a horizontal liquid bridge
NASA Astrophysics Data System (ADS)
Haynes, M.; O'Brien, S. B. G.; Benilov, E. S.
2016-04-01
This paper uses asymptotic techniques to find the shape of a two dimensional liquid bridge suspended between two vertical walls. We model the equilibrium bridge shape using the Laplace-Young equation. We use the Bond number as a small parameter to deduce an asymptotic solution which is then compared with numerical solutions. The perturbation approach demonstrates that equilibrium is only possible if the contact angle lies within a hysteresis interval and the analysis relates the width of this interval to the Bond number. This result is verified by comparison with a global force balance. In addition, we examine the quasi-static evolution of such a two dimensional bridge.
Asymptotic stability of singularly perturbed differential equations
NASA Astrophysics Data System (ADS)
Artstein, Zvi
2017-02-01
Asymptotic stability is examined for singularly perturbed ordinary differential equations that may not possess a natural split into fast and slow motions. Rather, the right hand side of the equation is comprised of a singularly perturbed component and a regular one. The limit dynamics consists then of Young measures, with values being invariant measures of the fast contribution, drifted by the slow one. Relations between the asymptotic stability of the perturbed system and the limit dynamics are examined, and a Lyapunov functions criterion, based on averaging, is established.
Asymptotic theory of relativistic, magnetized jets
Lyubarsky, Yuri
2011-01-15
The structure of a relativistically hot, strongly magnetized jet is investigated at large distances from the source. Asymptotic equations are derived describing collimation and acceleration of the externally confined jet. Conditions are found for the transformation of the thermal energy into the fluid kinetic energy or into the Poynting flux. Simple scalings are presented for the jet collimation angle and Lorentz factors.
Asymptotic theory of relativistic, magnetized jets.
Lyubarsky, Yuri
2011-01-01
The structure of a relativistically hot, strongly magnetized jet is investigated at large distances from the source. Asymptotic equations are derived describing collimation and acceleration of the externally confined jet. Conditions are found for the transformation of the thermal energy into the fluid kinetic energy or into the Poynting flux. Simple scalings are presented for the jet collimation angle and Lorentz factors.
Lectures on renormalization and asymptotic safety
Nagy, Sandor
2014-11-15
A short introduction is given on the functional renormalization group method, putting emphasis on its nonperturbative aspects. The method enables to find nontrivial fixed points in quantum field theoretic models which make them free from divergences and leads to the concept of asymptotic safety. It can be considered as a generalization of the asymptotic freedom which plays a key role in the perturbative renormalization. We summarize and give a short discussion of some important models, which are asymptotically safe such as the Gross–Neveu model, the nonlinear σ model, the sine–Gordon model, and we consider the model of quantum Einstein gravity which seems to show asymptotic safety, too. We also give a detailed analysis of infrared behavior of such scalar models where a spontaneous symmetry breaking takes place. The deep infrared behavior of the broken phase cannot be treated within the framework of perturbative calculations. We demonstrate that there exists an infrared fixed point in the broken phase which creates a new scaling regime there, however its structure is hidden by the singularity of the renormalization group equations. The theory spaces of these models show several similar properties, namely the models have the same phase and fixed point structure. The quantum Einstein gravity also exhibits similarities when considering the global aspects of its theory space since the appearing two phases there show analogies with the symmetric and the broken phases of the scalar models. These results be nicely uncovered by the functional renormalization group method.
Layer tracking, asymptotics, and domain decomposition
NASA Technical Reports Server (NTRS)
Brown, D. L.; Chin, R. C. Y.; Hedstrom, G. W.; Manteuffel, T. A.
1991-01-01
A preliminary report is presented on the work on the tracking of internal layers in a singularly-perturbed convection-diffusion equation. It is shown why such tracking may be desirable, and it is also shown how to do it using domain decomposition based on asymptotic analysis.
On asymptotic properties of biharmonic Steklov eigenvalues
NASA Astrophysics Data System (ADS)
Liu, Genqian
2016-11-01
In this paper, by explicitly calculating the principal symbols of pseudodifferential operators, we establish two Weyl-type asymptotic formulas with sharp remainder estimates for the counting functions of the two classes of biharmonic Steklov eigenvalue problems of smooth bounded domains in a Riemannian manifold.
Asymptotic Distributions for Tests of Combined Significance.
ERIC Educational Resources Information Center
Becker, Betsy Jane
This paper discusses distribution theory and power computations for four common "tests of combined significance." These tests are calculated using one-sided sample probabilities or p values from independent studies (or hypothesis tests), and provide an overall significance level for the series of results. Noncentral asymptotic sampling…
Occupational Therapy Assistant.
ERIC Educational Resources Information Center
Ohio State Univ., Columbus. Center on Education and Training for Employment.
This document, which is designed for use in developing a tech prep competency profile for the occupation of occupational therapy assistant, lists technical competencies and competency builders for 16 units pertinent to the health technologies cluster in general as well as those specific to the occupation of occupational therapy assistant. The…
NASA Technical Reports Server (NTRS)
Bopp, Genie; Somers, Jeff; Granderson, Brad; Gernhardt, Mike; Currie, Nancy; Lawrence, Chuck
2010-01-01
Topics include occupant protection overview with a focus on crew protection during dynamic phases of flight; occupant protection collaboration; modeling occupant protection; occupant protection considerations; project approach encompassing analysis tools, injury criteria, and testing program development; injury criteria update methodology, unique effects of pressure suits and other factors; and a summary.
ERIC Educational Resources Information Center
Willett, Lynn H.
A survey was conducted to determine the need for health occupations personnel in the Moraine Valley Community College district, specifically to: (1) describe present employment for selected health occupations; (2) project health occupation employment to 1974; (3) identify the supply of applicants for the selected occupations; and (4) identify…
Occupations of Indonesian Graduates.
ERIC Educational Resources Information Center
Palmier, Leslie
1982-01-01
Analysis of 1978 occupational patterns of college graduates in Indonesia considers occupation type, government employment, pay level, degree, discipline, relevance of education to employment, and concentration of academic majors in certain occupations. No occupation was the preserve of any one subject. (MSE)
Brane model with two asymptotic regions
NASA Astrophysics Data System (ADS)
Lubo, Musongela
2005-02-01
Some brane models rely on a generalization of the Melvin magnetic universe including a complex scalar field among the sources. We argue that the geometric interpretation of Kip. S. Thorne of this geometry restricts the kind of potential a complex scalar field can display to keep the same asymptotic behavior. While a finite energy is not obtained for a Mexican hat potential in this interpretation, this is the case for a potential displaying a broken phase and an unbroken one. We use for technical simplicity and illustrative purposes an ad hoc potential which however shares some features with those obtained in some supergravity models. We construct a sixth dimensional cylindrically symmetric solution which has two asymptotic regions: the Melvin-like metric on one side and a flat space displaying a conical singularity on the other. The causal structure of the configuration is discussed. Unfortunately, gravity is not localized on the brane.
Asymptotics of Determinants of Bessel Operators
NASA Astrophysics Data System (ADS)
Basor, Estelle L.; Ehrhardt, Torsten
For aL∞(+)∩L1(+) the truncated Bessel operator Bτ(a) is the integral operator acting on L2[0,τ] with the kernel
The Asymptotic Safety Scenario in Quantum Gravity.
Niedermaier, Max; Reuter, Martin
2006-01-01
The asymptotic safety scenario in quantum gravity is reviewed, according to which a renormalizable quantum theory of the gravitational field is feasible which reconciles asymptotically safe couplings with unitarity. The evidence from symmetry truncations and from the truncated flow of the effective average action is presented in detail. A dimensional reduction phenomenon for the residual interactions in the extreme ultraviolet links both results. For practical reasons the background effective action is used as the central object in the quantum theory. In terms of it criteria for a continuum limit are formulated and the notion of a background geometry self-consistently determined by the quantum dynamics is presented. Self-contained appendices provide prerequisites on the background effective action, the effective average action, and their respective renormalization flows.
Asymptotic scaling in turbulent pipe flow.
McKeon, B J; Morrison, J F
2007-03-15
The streamwise velocity component in turbulent pipe flow is assessed to determine whether it exhibits asymptotic behaviour that is indicative of high Reynolds numbers. The asymptotic behaviour of both the mean velocity (in the form of the log law) and that of the second moment of the streamwise component of velocity in the outer and overlap regions is consistent with the development of spectral regions which indicate inertial scaling. It is shown that an 'inertial sublayer' in physical space may be considered as a spatial analogue of the inertial subrange in the velocity spectrum and such behaviour only appears for Reynolds numbers R+>5 x 10(3), approximately, much higher than was generally thought.
Brane model with two asymptotic regions
Lubo, Musongela
2005-02-15
Some brane models rely on a generalization of the Melvin magnetic universe including a complex scalar field among the sources. We argue that the geometric interpretation of Kip. S. Thorne of this geometry restricts the kind of potential a complex scalar field can display to keep the same asymptotic behavior. While a finite energy is not obtained for a Mexican hat potential in this interpretation, this is the case for a potential displaying a broken phase and an unbroken one. We use for technical simplicity and illustrative purposes an ad hoc potential which however shares some features with those obtained in some supergravity models. We construct a sixth dimensional cylindrically symmetric solution which has two asymptotic regions: the Melvin-like metric on one side and a flat space displaying a conical singularity on the other. The causal structure of the configuration is discussed. Unfortunately, gravity is not localized on the brane.
Asymptotic Dynamics of Attractive-Repulsive Swarms
NASA Astrophysics Data System (ADS)
Leverentz, Andrew J.; Topaz, Chad M.; Bernoff, Andrew J.
2009-01-01
We classify and predict the asymptotic dynamics of a class of swarming models. The model consists of a conservation equation in one dimension describing the movement of a population density field. The velocity is found by convolving the density with a kernel describing attractive-repulsive social interactions. The kernel's first moment and its limiting behavior at the origin determine whether the population asymptotically spreads, contracts, or reaches steady state. For the spreading case, the dynamics approach those of the porous medium equation. The widening, compactly supported population has edges that behave like traveling waves whose speed, density, and slope we calculate. For the contracting case, the dynamics of the cumulative density approach those of Burgers' equation. We derive an analytical upper bound for the finite blow-up time after which the solution forms one or more delta-functions.
Non-asymptotic Analysis of Bandlimited Functions
2012-01-12
Illustration of Theorem 10 with c = 1000 and n = 670. 44 References [1] Richard K. Miller, Anthony N. Michel, Ordinary Differential Equations, Dover ...Publications, Inc., 1982. [2] Yoel Shkolnisky, Mark Tygert, Vladimir Rokhlin, Approximation of Ban - dlimited Functions. [3] Andreas Glaser, Xiangtao Liu...A. Stegun, Handbook of Mathematical Functions with Formulas, Graphs and Mathematical Tables, Dover Publications, 1964. [22] M.V. Fedoryuk, Asymptotic
Asymptotic modal analysis and statistical energy analysis
NASA Technical Reports Server (NTRS)
Dowell, Earl H.
1988-01-01
Statistical Energy Analysis (SEA) is defined by considering the asymptotic limit of Classical Modal Analysis, an approach called Asymptotic Modal Analysis (AMA). The general approach is described for both structural and acoustical systems. The theoretical foundation is presented for structural systems, and experimental verification is presented for a structural plate responding to a random force. Work accomplished subsequent to the grant initiation focusses on the acoustic response of an interior cavity (i.e., an aircraft or spacecraft fuselage) with a portion of the wall vibrating in a large number of structural modes. First results were presented at the ASME Winter Annual Meeting in December, 1987, and accepted for publication in the Journal of Vibration, Acoustics, Stress and Reliability in Design. It is shown that asymptotically as the number of acoustic modes excited becomes large, the pressure level in the cavity becomes uniform except at the cavity boundaries. However, the mean square pressure at the cavity corner, edge and wall is, respectively, 8, 4, and 2 times the value in the cavity interior. Also it is shown that when the portion of the wall which is vibrating is near a cavity corner or edge, the response is significantly higher.
Asymptotic dynamics of the exceptional Bianchi cosmologies
NASA Astrophysics Data System (ADS)
Hewitt, C. G.; Horwood, J. T.; Wainwright, J.
2003-05-01
In this paper we give, for the first time, a qualitative description of the asymptotic dynamics of a class of non-tilted spatially homogeneous (SH) cosmologies, the so-called exceptional Bianchi cosmologies, which are of Bianchi type VI$_{-1/9}$. This class is of interest for two reasons. Firstly, it is generic within the class of non-tilted SH cosmologies, being of the same generality as the models of Bianchi types VIII and IX. Secondly, it is the SH limit of a generic class of spatially inhomogeneous $G_{2}$ cosmologies. Using the orthonormal frame formalism and Hubble-normalized variables, we show that the exceptional Bianchi cosmologies differ from the non-exceptional Bianchi cosmologies of type VI$_{h}$ in two significant ways. Firstly, the models exhibit an oscillatory approach to the initial singularity and hence are not asymptotically self-similar. Secondly, at late times, although the models are asymptotically self-similar, the future attractor for the vacuum-dominated models is the so-called Robinson-Trautman SH model instead of the vacuum SH plane wave models.
Asymptotically flat space-times: an enigma
NASA Astrophysics Data System (ADS)
Newman, Ezra T.
2016-07-01
We begin by emphasizing that we are dealing with standard Einstein or Einstein-Maxwell theory—absolutely no new physics has been inserted. The fresh item is that the well-known asymptotically flat solutions of the Einstein-Maxwell theory are transformed to a new coordinate system with surprising and (seemingly) inexplicable results. We begin with the standard description of (Null) asymptotically flat space-times described in conventional Bondi-coordinates. After transforming the variables (mainly the asymptotic Weyl tensor components) to a very special set of Newman-Unti (NU) coordinates, we find a series of relations totally mimicking standard Newtonian classical mechanics and Maxwell theory. The surprising and troubling aspect of these relations is that the associated motion and radiation does not take place in physical space-time. Instead these relations takes place in an unusual inherited complex four-dimensional manifold referred to as H-space that has no immediate relationship with space-time. In fact these relations appear in two such spaces, H-space and its dual space \\bar{H}.
Some asymptotic properties of duplication graphs
NASA Astrophysics Data System (ADS)
Raval, Alpan
2003-12-01
Duplication graphs are graphs that grow by duplication of existing vertices, and are important models of biological networks, including protein-protein interaction networks and gene regulatory networks. Three models of graph growth are studied: pure duplication growth, and two two-parameter models in which duplication forms one element of the growth dynamics. A power-law degree distribution is found to emerge in all three models. However, the parameter space of the latter two models is characterized by a range of parameter values for which duplication is the predominant mechanism of graph growth. For parameter values that lie in this “duplication-dominated” regime, it is shown that the degree distribution either approaches zero asymptotically, or approaches a nonzero power-law degree distribution very slowly. In either case, the approach to the true asymptotic degree distribution is characterized by a dependence of the scaling exponent on properties of the initial degree distribution. It is therefore conjectured that duplication-dominated, scale-free networks may contain identifiable remnants of their early structure. This feature is inherited from the idealized model of pure duplication growth, for which the exact finite-size degree distribution is found and its asymptotic properties studied.
Asymptotic form of the Kohn-Sham correlation potential
Joubert, D. P.
2007-07-15
The density-functional correlation potential of a finite system is shown to asymptotically approach a nonzero constant along a nodal surface of the energetically highest occupied orbital and zero everywhere else. This nonuniform asymptotic form of the correlation potential exactly cancels the nonuniform asymptotic behavior of the exact exchange potential discussed by Della Sala and Goerling [Phys. Rev. Lett. 89, 33003 (2002)]. The sum of the exchange and correlation potentials therefore asymptotically tends to -1/r everywhere, consistent with the asymptotic form of the Kohn-Sham potential as analyzed by Almbladh and von Barth [Phys. Rev. B 31, 3231 (1985)].
asymptoticMK: A Web-Based Tool for the Asymptotic McDonald-Kreitman Test.
Haller, Benjamin C; Messer, Philipp W
2017-03-24
The McDonald-Kreitman (MK) test is a widely used method for quantifying the role of positive selection in molecular evolution. One key shortcoming of this test lies in its sensitivity to the presence of slightly deleterious mutations, which can severely bias its estimates. An asymptotic version of the MK test was recently introduced that addresses this problem by evaluating polymorphism levels for different mutation frequencies separately, and then extrapolating a function fitted to that data. Here we present asymptoticMK, a web-based implementation of this asymptotic McDonald-Kreitman test. Our web service provides a simple R-based interface into which the user can upload the required data (polymorphism and divergence data for the genomic test region and a neutrally evolving reference region). The web service then analyzes the data and provides plots of the test results. This service is free to use, open-source, and available at http://benhaller.com/messerlab/asymptoticMK.html. We provide results from simulations to illustrate the performance and robustness of the asymptoticMK test under a wide range of model parameters.
Illinois Occupational Skill Standards: Occupational Therapy Cluster.
ERIC Educational Resources Information Center
Illinois Occupational Skill Standards and Credentialing Council, Carbondale.
This document, which is intended to serve as a guide for work force preparation program providers, details the Illinois occupational skill standards for programs preparing students for employment in jobs in occupational therapy. Agency partners involved in this project include: the Illinois State board of Education, Illinois Community College…
Occupational Clusters. Occupational Investigation Guide. First Edition.
ERIC Educational Resources Information Center
East Texas State Univ., Commerce. Occupational Curriculum Lab.
This occupational investigation guide contains learning activities for instruction in fifteen occupational clusters: (1) agribusiness and natural resources, (2) business and office, (3) communications and media, (4) construction, (5) consumer and homemaking, (6) environment, (7) fine arts and humanities, (8) health, (9) hospitality and recreation,…
Health Occupations Cluster Guide.
ERIC Educational Resources Information Center
Oregon State Dept. of Education, Salem.
Intended to assist the vocational teacher in designing and implementing a cluster program in health occupations, this guide suggests ideas for teaching the specific knowledge and skills that qualify students for entry-level employment in the health occupations field. The knowledge and skills are applicable to 12 occupations: dental assistant;…
Agricultural Occupations Handbook.
ERIC Educational Resources Information Center
Lark, Floyd J.; Henderson, Billie
This agricultural occupations handbook was developed from the Dictionary of Occupational Titles (DOT) and the U.S. Departments of Health, Education, and Welfare, and Labor publication, Vocational Education and Occupations. It includes the U.S. Office of Education coding for the instructional area of agriculture and the cluster coding for the…
Manual on Occupational Analysis.
ERIC Educational Resources Information Center
Hermann, Graham D.
This manual on occupational analysis, developed in Australia, is organized in three sections. The first section provides a framework for occupational analysis (OA) and a discussion of possible outputs from an OA from each of three phases: (1) determining the nature and scope of the occupational area; (2) developing a competencies list; and (3)…
Asymptotic modal analysis and statistical energy analysis
NASA Technical Reports Server (NTRS)
Dowell, Earl H.
1992-01-01
Asymptotic Modal Analysis (AMA) is a method which is used to model linear dynamical systems with many participating modes. The AMA method was originally developed to show the relationship between statistical energy analysis (SEA) and classical modal analysis (CMA). In the limit of a large number of modes of a vibrating system, the classical modal analysis result can be shown to be equivalent to the statistical energy analysis result. As the CMA result evolves into the SEA result, a number of systematic assumptions are made. Most of these assumptions are based upon the supposition that the number of modes approaches infinity. It is for this reason that the term 'asymptotic' is used. AMA is the asymptotic result of taking the limit of CMA as the number of modes approaches infinity. AMA refers to any of the intermediate results between CMA and SEA, as well as the SEA result which is derived from CMA. The main advantage of the AMA method is that individual modal characteristics are not required in the model or computations. By contrast, CMA requires that each modal parameter be evaluated at each frequency. In the latter, contributions from each mode are computed and the final answer is obtained by summing over all the modes in the particular band of interest. AMA evaluates modal parameters only at their center frequency and does not sum the individual contributions from each mode in order to obtain a final result. The method is similar to SEA in this respect. However, SEA is only capable of obtaining spatial averages or means, as it is a statistical method. Since AMA is systematically derived from CMA, it can obtain local spatial information as well.
Singular asymptotic expansions in nonlinear rotordynamics
NASA Technical Reports Server (NTRS)
Day, W. B.
1984-01-01
During hot firing ground testing of the Space Shuttle's Main Engine, vibrations of the liquid oxygen pump occur at frequencies which cannot be explained by the linear Jeffcott model of the rotor. The model becomes nonlinear after accounting for deadband, side forces, and rubbing. Two phenomena present in the numerical solutions of the differential equations are unexpected periodic orbits of the rotor and tracking of the nonlinear frequency. A multiple scale asymptotic expansion of the differential equations is used to give an analytic explanation of these characteristics.
Singular asymptotic expansions in nonlinear rotordynamics
NASA Technical Reports Server (NTRS)
Day, W. B.
1985-01-01
During hot firing ground testing of the Space shuttle's Main Engine, vibrations of the liquid oxygen pump occur at frequencies which cannot be explained by the linear Jeffcott model of the rotor. The model becomes nonlinear after accounting for deadband, side forces, and rubbing. Two phenomena present in the numerical solutions of the differential equations are unexpected periodic orbits of the rotor and tracking of the nonlinear frequency. A multiple scale asymptotic expansion of the differential equations is used to give an analytic explanation of these characteristics.
Asymptotics of loop quantum gravity fusion coefficients
NASA Astrophysics Data System (ADS)
Alesci, Emanuele; Bianchi, Eugenio; Magliaro, Elena; Perini, Claudio
2010-05-01
The fusion coefficients from SO(3) to SO(4) play a key role in the definition of spin foam models for the dynamics in loop quantum gravity. In this paper we give a simple analytic formula of the Engle-Pereira-Rovelli-Livine fusion coefficients. We study the large spin asymptotics and show that they map SO(3) semiclassical intertwiners into SU(2)L × SU(2)R semiclassical intertwiners. This non-trivial property opens the possibility for an analysis of the semiclassical behavior of the model.
Vacuum Potential and its Asymptotic Variation
NASA Astrophysics Data System (ADS)
Dahal, Pravin
2016-09-01
The possible form of existence of dark energy is explained and the relation for its asymptotic variation is given. This has two huge implications in the understanding of the Universe. The first is that the theory predicts that the Universe should be in negative pressure state in the very early period as required for inflation and spontaneous symmetry breaking. The second is that the theory gives the reasonable answer to the astrophysical evidence of dark energy dominating the Universe. The author is presenting his research in the nature of dark energy. Some of the work is submitted for publication in the journal and is currently under review.
The Two Isotropic Asymptotes of Fiber Composites,
1988-03-01
Voigt and Reuss models of summed stiffness and compliance. The compliance quasi-isotropic asymptote, which >’-:’ has evidently not been discussed in the...i,j,e)de o0 The resulting pseudo -isotropic compliance (series-model) Hooke’s law matrix is similar but not identical to Eq. (3): W(1) W(4) 0 a aIE...given by 1 W( ) 14) E : - Vc Wc 4W(5) 2[W(1) - W()] (8) c W() W(14 12 Direct formulas for the pseudo -isctrcpic moduli, in terms of the ply 1s natural
Asymptotic Theory for Nonparametric Confidence Intervals.
1982-07-01
distributions. Ann. Math Statist. 14, 56-62. 24. ROY, S.N. and POTTHOFF, R.F. (1958). Confidence bounds on vector analogues of the "ratio of the mean" and...fl c,~_________ 14L TITLE feed &MV) S. TYPE or REPORT a PeftOo COVx:REC Asympeocic Theory for Nonaparuetric Technical Report Confidence Intevals 6...S..C-0S78 UNCLASSIFIED TŗU *uuuuumuuumhhhhmhhhm_4 ASYMPTOTIC THEORY FOR NONPARAMETRIC CONFIDENCE INTERVALS by Peter W. Glynn TECHNICAL REPORT NO. 63
Occupational rhinitis: an update.
Stevens, Whitney W; Grammer, Leslie C
2015-01-01
Occupational rhinitis is characterized by nasal congestion, rhinorrhea, nasal itching, and/or sneezing that occur secondary to exposures in the workplace. This disease can be classified into allergic or nonallergic subgroups based upon the underlying disease pathogenesis as well as the type of causative agent. While the true prevalence of occupational rhinitis is unknown, there are certain professions and occupational exposures that place workers at a higher risk for developing the disease. Additionally, occupational rhinitis can be associated with occupational asthma and upper airway symptoms may precede those of the lower respiratory tract. Taken together, occupational rhinitis is an important disease for study given its medical as well as socioeconomic implications. This review will focus on the classification of occupational rhinitis as well the prevalence, diagnosis, and treatment strategies.
In this article, we consider the least-squares approach for estimating parameters of a spatial variogram and establish consistency and asymptotic normality of these estimators under general conditions. Large-sample distributions are also established under a sp...
Asymptotic behavior of a flat plate wake
NASA Technical Reports Server (NTRS)
Weygandt, James H.; Mehta, Rabindra D.
1989-01-01
An experimental study has been conducted to investigate the far-field, self-similar properties of a flat plate wake. A plane turbulent wake was generated at the trailing edge of a smooth splitter plate separating two legs of a Mixing Layer Wind Tunnel, with both initial boundary layers tripped. For the present study, both legs were operated at a free-steam velocity in the test section of 15 m/s, giving a Reynolds number based on wake momentum thickness of about 1750. Single profile measurements were obtained at five streamwise locations using a Pitot probe for the mean velocity measurements and a single cross-wire probe for the turbulence data, which included statistics up to third order. The mean flow data indicated a self-similar behavior beyond a streamwise distance equivalent to about 350 wake momentum thicknesses. However, the turbulence data show better collapse beyond a distance equivalent to about 500 momentum thicknesses, with all the measured peak Reynolds stresses achieving constant, asymptotic levels. The asymptotic mean flow behavior and peak primary stress levels agree well with theoretical predictions based on a constant eddy viscosity model. The present data also agree reasonably well with previous measurements, of which only one set extends into the self-similar region. Detailed comparisons with previous data are presented and discussed in this report.
Relaxing the parity conditions of asymptotically flat gravity
NASA Astrophysics Data System (ADS)
Compère, Geoffrey; Dehouck, François
2011-12-01
Four-dimensional asymptotically flat spacetimes at spatial infinity are defined from first principles without imposing parity conditions or restrictions on the Weyl tensor. The Einstein-Hilbert action is shown to be a correct variational principle when it is supplemented by an anomalous counterterm which breaks asymptotic translation, supertranslation and logarithmic translation invariance. Poincaré transformations as well as supertranslations and logarithmic translations are associated with finite and conserved charges which represent the asymptotic symmetry group. Lorentz charges as well as logarithmic translations transform anomalously under a change of regulator. Lorentz charges are generally nonlinear functionals of the asymptotic fields but reduce to well-known linear expressions when parity conditions hold. We also define a covariant phase space of asymptotically flat spacetimes with parity conditions but without restrictions on the Weyl tensor. In this phase space, the anomaly plays classically no dynamical role. Supertranslations are pure gauge and the asymptotic symmetry group is the expected Poincaré group.
Asymptotic behaviour of solutions of semilinear parabolic equations
Egorov, Yu V; Kondratiev, V A
2008-04-30
The asymptotic behaviour of solutions of a second-order semilinear parabolic equation is analyzed in a cylindrical domain that is bounded in the space variables. The dominant term of the asymptotic expansion of the solution as t{yields}+{infinity} is found. It is shown that the solution of this problem is asymptotically equivalent to the solution of a certain non-linear ordinary differential equation. Bibliography: 8 titles.
Numerical integration of asymptotic solutions of ordinary differential equations
NASA Technical Reports Server (NTRS)
Thurston, Gaylen A.
1989-01-01
Classical asymptotic analysis of ordinary differential equations derives approximate solutions that are numerically stable. However, the analysis also leads to tedious expansions in powers of the relevant parameter for a particular problem. The expansions are replaced with integrals that can be evaluated by numerical integration. The resulting numerical solutions retain the linear independence that is the main advantage of asymptotic solutions. Examples, including the Falkner-Skan equation from laminar boundary layer theory, illustrate the method of asymptotic analysis with numerical integration.
The Asymptotic Distribution of Mortality Rates in Competing Risks Analyses,
1979-12-01
For a sample of individuals from an animal or human population under observation in a clinical trial or life test, mortality rates are defined for...model, these mortality rates are shown to have an asymptotic normal distribution. An expression for the asymptotic correlation between a pair of... mortality rates is thus obtained and a necessary and sufficient condition for their asymptotic independence is investigated in some general situations with
Listing Occupational Carcinogens
Siemiatycki, Jack; Richardson, Lesley; Straif, Kurt; Latreille, Benoit; Lakhani, Ramzan; Campbell, Sally; Rousseau, Marie-Claude; Boffetta, Paolo
2004-01-01
The occupational environment has been a most fruitful one for investigating the etiology of human cancer. Many recognized human carcinogens are occupational carcinogens. There is a large volume of epidemiologic and experimental data concerning cancer risks in different work environments. It is important to synthesize this information for both scientific and public health purposes. Various organizations and individuals have published lists of occupational carcinogens. However, such lists have been limited by unclear criteria for which recognized carcinogens should be considered occupational carcinogens, and by inconsistent and incomplete information on the occupations and industries in which the carcinogenic substances may be found and on their target sites of cancer. Based largely on the evaluations published by the International Agency for Research on Cancer, and augmented with additional information, the present article represents an attempt to summarize, in tabular form, current knowledge on occupational carcinogens, the occupations and industries in which they are found, and their target organs. We have considered 28 agents as definite occupational carcinogens, 27 agents as probable occupational carcinogens, and 113 agents as possible occupational carcinogens. These tables should be useful for regulatory or preventive purposes and for scientific purposes in research priority setting and in understanding carcinogenesis. PMID:15531427
Inference for occupancy and occupancy dynamics
O'Connell, Allan F.; Bailey, Larissa L.; O'Connell, Allan F.; Nichols, James D.; Karanth, K. Ullas
2011-01-01
This chapter deals with the estimation of occupancy as a state variable to assess the status of, and track changes in, species distributions when sampling with camera traps. Much of the recent interest in occupancy estimation and modeling originated from the models developed by MacKenzie et al. (2002, 2003), although similar methods were developed independently (Azuma et al. 1990; Bayley and Petersen 2001; Nichols and Karanth, 2002; Tyre et al. 2003), all of which deal with species occurrence information and imperfect detection. Less than a decade after these publications, the modeling and estimation of species occurrence and occupancy dynamics have increased significantly. Special features of scientific journals have explored innovative uses of detection–nondetection data with occupancy models (Vojta 2005), and an entire volume has synthesized the use and application of occupancy estimation methods (MacKenzie et al. 2006). Reviews of the topical concepts, philosophical considerations, and various sampling designs that can be used for occupancy estimation are now readily available for a range of audiences (MacKenzie and Royle 2005; MacKenzie et al. 2006; Bailey et al. 2007; Royle and Dorazio 2008; Conroy and Carroll 2009; Kendall and White 2009; Hines et al. 2010; Link and Barker 2010). As a result, it would be pointless here to recast all that these publications have so eloquently articulated, but that said, a review of any scientific topic requires sufficient context and relevant background information, especially when relatively new methodologies and techniques such as occupancy estimation and camera traps are involved. This is especially critical in a digital age where new information is published at warp speed, making it increasingly difficult to stay abreast of theoretical advances and research developments.
Estimation of an Occupational Choice Model when Occupations Are Misclassified
ERIC Educational Resources Information Center
Sullivan, Paul
2009-01-01
This paper develops an empirical occupational choice model that corrects for misclassification in occupational choices and measurement error in occupation-specific work experience. The model is used to estimate the extent of measurement error in occupation data and quantify the bias that results from ignoring measurement error in occupation codes…
INFECTION AS OCCUPATIONAL RISK,
The percentage of the job-connected infectious diseases of the total number of occupational diseases has been subject to only minor fluctuations...since 1949. Of the occupational infections of medical personnel, tuberculosis and infectious hepatitis are the most important; among diseases that can be...importance in the recognition of an infectious disease as an occupational disease. The article discusses the sources of infection, the manner of
Green's function asymptotics and sharp interpolation inequalities
NASA Astrophysics Data System (ADS)
Zelik, S. V.; Ilyin, A. A.
2014-04-01
A general method is proposed for finding sharp constants for the embeddings of the Sobolev spaces H^m(\\mathscr{M}) on an n-dimensional Riemannian manifold \\mathscr{M} into the space of bounded continuous functions, where m\\gt n/2. The method is based on an analysis of the asymptotics with respect to the spectral parameter of the Green's function of an elliptic operator of order 2m whose square root has domain determining the norm of the corresponding Sobolev space. The cases of the n-dimensional torus {T}^n and the n-dimensional sphere {S}^n are treated in detail, as well as certain manifolds with boundary. In certain cases when \\mathscr{M} is compact, multiplicative inequalities with remainder terms of various types are obtained. Inequalities with correction terms for periodic functions imply an improvement for the well-known Carlson inequalities. Bibliography: 28 titles.
Loop Quantum Gravity and Asymptotically Flat Spaces
NASA Astrophysics Data System (ADS)
Arnsdorf, Matthias
2002-12-01
Remarkable progress has been made in the field of non-perturbative (loop) quantum gravity in the last decade or so and it is now a rigorously defined kinematical theory (c.f. [5] for a review and references). We are now at the stage where physical applications of loop quantum gravity can be studied and used to provide checks for the consistency of the quantisation programme. Equally, old fundamental problems of canonical quantum gravity such as the problem of time or the interpretation of quantum cosmology need to be reevaluated seriously. These issues can be addressed most profitably in the asymptotically flat sector of quantum gravity. Indeed, it is likely that we should obtain a quantum theory for this special case even if it is not possible to quantise full general relativity. The purpose of this summary is to advertise the extension of loop quantum gravity to this sector that was developed in [1]...
Nucleosynthesis in asymptotic giant branch stars
El Eid, Mounib F.
2014-05-09
The nucleosynthesis in asymptotic giant branch stars (briefly: AGB)is a challenging and fascinating subject in the theory of stellar evolution and important for observations as well. This is because about of half the heavy elements beyond iron are synthesized during thermal pulsation phases of these stars. Furthermore, the understanding of the production of the heavy elements and some light elements like carbon and fluorine represent a powerful tool to get more insight into the internal structure of these stars. The diversity of nuclear processing during the AGB phases may also motivate experimental activities in measuring important nuclear reactions. In this contribution, we emphasize several interesting feature of the nucleosynthesis in AGB stars which still needs further elaboration especially from theoretical point of view.
Universality and asymptotic scaling in drilling percolation
NASA Astrophysics Data System (ADS)
Grassberger, Peter
2017-01-01
We present simulations of a three-dimensional percolation model studied recently by K. J. Schrenk et al. [Phys. Rev. Lett. 116, 055701 (2016), 10.1103/PhysRevLett.116.055701], obtained with a new and more efficient algorithm. They confirm most of their results in spite of larger systems and higher statistics used in the present Rapid Communication, but we also find indications that the results do not yet represent the true asymptotic behavior. The model is obtained by replacing the isotropic holes in ordinary Bernoulli percolation by randomly placed and oriented cylinders, with the constraint that the cylinders are parallel to one of the three coordinate axes. We also speculate on possible generalizations.
Asymptotic Linear Stability of Solitary Water Waves
NASA Astrophysics Data System (ADS)
Pego, Robert L.; Sun, Shu-Ming
2016-12-01
We prove an asymptotic stability result for the water wave equations linearized around small solitary waves. The equations we consider govern irrotational flow of a fluid with constant density bounded below by a rigid horizontal bottom and above by a free surface under the influence of gravity neglecting surface tension. For sufficiently small amplitude waves, with waveform well-approximated by the well-known sech-squared shape of the KdV soliton, solutions of the linearized equations decay at an exponential rate in an energy norm with exponential weight translated with the wave profile. This holds for all solutions with no component in (that is, symplectically orthogonal to) the two-dimensional neutral-mode space arising from infinitesimal translational and wave-speed variation of solitary waves. We also obtain spectral stability in an unweighted energy norm.
The asymptotics of large constrained graphs
NASA Astrophysics Data System (ADS)
Radin, Charles; Ren, Kui; Sadun, Lorenzo
2014-05-01
We show, through local estimates and simulation, that if one constrains simple graphs by their densities ɛ of edges and τ of triangles, then asymptotically (in the number of vertices) for over 95% of the possible range of those densities there is a well-defined typical graph, and it has a very simple structure: the vertices are decomposed into two subsets V1 and V2 of fixed relative size c and 1 - c, and there are well-defined probabilities of edges, gjk, between vj ∈ Vj, and vk ∈ Vk. Furthermore the four parameters c, g11, g22 and g12 are smooth functions of (ɛ, τ) except at two smooth ‘phase transition’ curves.
Chiral fermions in asymptotically safe quantum gravity.
Meibohm, J; Pawlowski, J M
2016-01-01
We study the consistency of dynamical fermionic matter with the asymptotic safety scenario of quantum gravity using the functional renormalisation group. Since this scenario suggests strongly coupled quantum gravity in the UV, one expects gravity-induced fermion self-interactions at energies of the Planck scale. These could lead to chiral symmetry breaking at very high energies and thus to large fermion masses in the IR. The present analysis which is based on the previous works (Christiansen et al., Phys Rev D 92:121501, 2015; Meibohm et al., Phys Rev D 93:084035, 2016), concludes that gravity-induced chiral symmetry breaking at the Planck scale is avoided for a general class of NJL-type models. We find strong evidence that this feature is independent of the number of fermion fields. This finding suggests that the phase diagram for these models is topologically stable under the influence of gravitational interactions.
Rubidium-rich asymptotic giant branch stars.
García-Hernández, D A; García-Lario, P; Plez, B; D'Antona, F; Manchado, A; Trigo-Rodríguez, J M
2006-12-15
A long-debated issue concerning the nucleosynthesis of neutron-rich elements in asymptotic giant branch (AGB) stars is the identification of the neutron source. We report intermediate-mass (4 to 8 solar masses) AGB stars in our Galaxy that are rubidium-rich as a result of overproduction of the long-lived radioactive isotope (87)Rb, as predicted theoretically 40 years ago. This finding represents direct observational evidence that the (22)Ne(alpha,n)(25)Mg reaction must be the dominant neutron source in these stars. These stars challenge our understanding of the late stages of the evolution of intermediate-mass stars and would have promoted a highly variable Rb/Sr environment in the early solar nebula.
Nucleosynthesis in asymptotic giant branch stars
NASA Astrophysics Data System (ADS)
El Eid, Mounib F.
2014-05-01
The nucleosynthesis in asymptotic giant branch stars (briefly: AGB)is a challenging and fascinating subject in the theory of stellar evolution and important for observations as well. This is because about of half the heavy elements beyond iron are synthesized during thermal pulsation phases of these stars. Furthermore, the understanding of the production of the heavy elements and some light elements like carbon and fluorine represent a powerful tool to get more insight into the internal structure of these stars. The diversity of nuclear processing during the AGB phases may also motivate experimental activities in measuring important nuclear reactions. In this contribution, we emphasize several interesting feature of the nucleosynthesis in AGB stars which still needs further elaboration especially from theoretical point of view.
Global Asymptotic Behavior of Iterative Implicit Schemes
NASA Technical Reports Server (NTRS)
Yee, H. C.; Sweby, P. K.
1994-01-01
The global asymptotic nonlinear behavior of some standard iterative procedures in solving nonlinear systems of algebraic equations arising from four implicit linear multistep methods (LMMs) in discretizing three models of 2 x 2 systems of first-order autonomous nonlinear ordinary differential equations (ODEs) is analyzed using the theory of dynamical systems. The iterative procedures include simple iteration and full and modified Newton iterations. The results are compared with standard Runge-Kutta explicit methods, a noniterative implicit procedure, and the Newton method of solving the steady part of the ODEs. Studies showed that aside from exhibiting spurious asymptotes, all of the four implicit LMMs can change the type and stability of the steady states of the differential equations (DEs). They also exhibit a drastic distortion but less shrinkage of the basin of attraction of the true solution than standard nonLMM explicit methods. The simple iteration procedure exhibits behavior which is similar to standard nonLMM explicit methods except that spurious steady-state numerical solutions cannot occur. The numerical basins of attraction of the noniterative implicit procedure mimic more closely the basins of attraction of the DEs and are more efficient than the three iterative implicit procedures for the four implicit LMMs. Contrary to popular belief, the initial data using the Newton method of solving the steady part of the DEs may not have to be close to the exact steady state for convergence. These results can be used as an explanation for possible causes and cures of slow convergence and nonconvergence of steady-state numerical solutions when using an implicit LMM time-dependent approach in computational fluid dynamics.
... Ethics Occupational Therapy Assistants Advocacy & Policy New Evaluation Codes Learn how to use the new OT CPT® Evaluation codes correctly . Congressional Affairs AOTPAC Federal Regulatory Affairs Health ...
American Occupational Therapy Association
... Ethics Occupational Therapy Assistants Advocacy & Policy New Evaluation Codes Learn how to use the new OT CPT® Evaluation codes correctly . Congressional Affairs AOTPAC Federal Regulatory Affairs Health ...
Merler, E; Vineis, P; Alhaique, D; Miligi, L
1999-01-01
This article is a discussion of occupational cancer in Italy. The introduction provides the necessary context of Italian industrialization and occupational health regulation. This is followed by a review of Italian epidemiologic studies of occupational cancer risks considered in terms of relative measures of risk and attributable risk of carcinogenic agents or exposure circumstances. We attempt to establish the number of workers exposed to carcinogens in Italy and the intensity of their exposures. Finally, the Italian system of compensation for occupational cancer is discussed. Several cohort and case-control studies have addressed the issue of occupational risks, mostly among male workers. The results of these studies suggest that the growing incidence of and mortality by mesothelioma is explained by the widespread and intense exposure to asbestos in some Italian industrial settings. A high attributable risk of lung tumors among male populations in industrial areas of northern Italy is explained by occupational exposures. However, insufficient data are available for clear definition of the extent and intensity of occupational exposure to carcinogenic substances. In Italy, we must prioritize and maximize resources in occupational cancer epidemiology and revitalize the role of national institutions. Recent legislation has established new regulations on the handling of carcinogenic substances in industrial settings, a new list of occupational diseases, and a national registry of mesothelioma linked to asbestos exposure. These legislative changes are expected to have positive effects. PMID:10350509
Teacher's Guide to Occupational Orientation.
ERIC Educational Resources Information Center
National Evaluation Systems, Inc., Amherst, MA.
This guide is specifically designed to accompany materials developed for occupational orientation (particularly in Illinois) in the following five cluster areas: Applied biological and agricultural occupations; personal and public service occupations; health occupations; business, marketing, and management occupations; and industrial oriented…
Welding. Occupational Competency Analysis Profile.
ERIC Educational Resources Information Center
Ohio State Univ., Columbus. Vocational Instructional Materials Lab.
This Occupational Competency Analysis Profile (OCAP), which is one of a series of OCAPs developed to identify the skills that Ohio employers deem necessary to entering a given occupation/occupational area, lists the occupational, academic, and employability skills required of individuals entering the occupation of welder. The introduction explains…
Gaussian and mean curvatures for discrete asymptotic nets
NASA Astrophysics Data System (ADS)
Schief, W. K.
2017-04-01
We propose discretisations of Gaussian and mean curvatures of surfaces parametrised in terms of asymptotic coordinates and examine their relevance in the context of integrable discretisations of classical classes of surfaces and their underlying integrable systems. We also record discrete analogues of the classical relation between the Gaussian curvature of hyperbolic surfaces and the torsion of their asymptotic lines.
Scattering in an external electric field asymptotically constant in time
Adachi, Tadayoshi; Ishida, Atsuhide
2011-06-15
We show the asymptotic completeness for two-body quantum systems in an external electric field asymptotically non-zero constant in time. One of the main ingredients of this paper is to give some propagation estimates for physical propagators generated by time-dependent Hamiltonians which govern the systems under consideration.
Asymptotic expansions for the reciprocal of the gamma function
NASA Astrophysics Data System (ADS)
Withers, Christopher S.; Nadarajah, Saralees
2014-05-01
Asymptotic expansions are derived for the reciprocal of the gamma function. We show that the coefficients of the expansion are the same, up to a sign change, as the asymptotic expansions for the gamma function obtained by exponentiating the expansions of its logarithm due to Stirling and de Moivre. Expressions for the coefficients are given in terms of Bell polynomials.
Aschebrook-Kilfoy, Briseis; Ward, Mary H.; Valle, Curt T. Della; Friesen, Melissa C.
2014-01-01
Objectives Numerous occupational and environmental exposures have been shown to disrupt thyroid hormones, but much less is known about their relationships with thyroid cancer. Here we review the epidemiology studies of occupations and occupational exposures and thyroid cancer incidence to provide insight into preventable risk factors for thyroid cancer. Methods The published literature was searched using the Web of Knowledge database for all articles through August 2013 that had in their text “occupation” “job” ”employment” or “work” and “thyroid cancer”. After excluding 10 mortality studies and 4 studies with less than 5 exposed incident cases, we summarized the findings of 30 articles that examined thyroid cancer incidence in relation to occupations or occupational exposure. The studies were grouped by exposure/occupation category, study design, and exposure assessment approach. Where available, gender stratified results are reported. Results The most studied (19 of 30 studies) and the most consistent associations were observed for radiation-exposed workers and health care occupations. Suggestive, but inconsistent, associations were observed in studies of pesticide-exposed workers and agricultural occupations. Findings for other exposures and occupation groups were largely null. The majority of studies had few exposed cases and assessed exposure based on occupation or industry category, self-report, or generic (population-based) job exposure matrices. Conclusion The suggestive, but inconsistent findings for many of the occupational exposures reviewed here indicate that more studies with larger numbers of cases and better exposure assessment are necessary, particularly for exposures known to disrupt thyroid homeostasis. PMID:24604144
Asymptotic approximations to posterior distributions via conditional moment equations
Yee, J.L.; Johnson, W.O.; Samaniego, F.J.
2002-01-01
We consider asymptotic approximations to joint posterior distributions in situations where the full conditional distributions referred to in Gibbs sampling are asymptotically normal. Our development focuses on problems where data augmentation facilitates simpler calculations, but results hold more generally. Asymptotic mean vectors are obtained as simultaneous solutions to fixed point equations that arise naturally in the development. Asymptotic covariance matrices flow naturally from the work of Arnold & Press (1989) and involve the conditional asymptotic covariance matrices and first derivative matrices for conditional mean functions. When the fixed point equations admit an analytical solution, explicit formulae are subsequently obtained for the covariance structure of the joint limiting distribution, which may shed light on the use of the given statistical model. Two illustrations are given. ?? 2002 Biometrika Trust.
On the asymptotics of the α-Farey transfer operator
NASA Astrophysics Data System (ADS)
Kautzsch, J.; Kesseböhmer, M.; Samuel, T.; Stratmann, B. O.
2015-01-01
We study the asymptotics of iterates of the transfer operator for non-uniformly hyperbolic α-Farey maps. We provide a family of observables which are Riemann integrable, locally constant and of bounded variation, and for which the iterates of the transfer operator, when applied to one of these observables, is not asymptotic to a constant times the wandering rate on the first element of the partition α. Subsequently, sufficient conditions on observables are given under which this expected asymptotic holds. In particular, we obtain an extension theorem which establishes that, if the asymptotic behaviour of iterates of the transfer operator is known on the first element of the partition α, then the same asymptotic holds on any compact set bounded away from the indifferent fixed point.
Eigenvalue spectrum of the spheroidal harmonics: A uniform asymptotic analysis
NASA Astrophysics Data System (ADS)
Hod, Shahar
2015-06-01
The spheroidal harmonics Slm (θ ; c) have attracted the attention of both physicists and mathematicians over the years. These special functions play a central role in the mathematical description of diverse physical phenomena, including black-hole perturbation theory and wave scattering by nonspherical objects. The asymptotic eigenvalues {Alm (c) } of these functions have been determined by many authors. However, it should be emphasized that all the previous asymptotic analyzes were restricted either to the regime m → ∞ with a fixed value of c, or to the complementary regime | c | → ∞ with a fixed value of m. A fuller understanding of the asymptotic behavior of the eigenvalue spectrum requires an analysis which is asymptotically uniform in both m and c. In this paper we analyze the asymptotic eigenvalue spectrum of these important functions in the double limit m → ∞ and | c | → ∞ with a fixed m / c ratio.
Asymptotic Properties of Some Classes of Generalized Functions
NASA Astrophysics Data System (ADS)
Drozhzhinov, Yu N.; Zav'yalov, B. I.
1986-02-01
This paper studies the connection between the asymptotic and quasi-asymptotic properties at infinity of slowly increasing generalized functions with supports on the half-line and the asymptotic and quasi-asymptotic properties of the real parts of their Laplace and Fourier transforms in a neighborhood of the origin. The study is caried out in the scale of regularly varying self-similar functions. The results are applied to the study of the asymptotic properties of solutions of linear passive systems, and also to the study of the connection between Abel and Cesàro convergence (with respect to a self-similar weight) of the Fourier-Stieltjes series of nonnegative measures. Bibliography: 13 titles.
Large gauge symmetries and asymptotic states in QED
NASA Astrophysics Data System (ADS)
Gabai, Barak; Sever, Amit
2016-12-01
Large Gauge Transformations (LGT) are gauge transformations that do not vanish at infinity. Instead, they asymptotically approach arbitrary functions on the conformal sphere at infinity. Recently, it was argued that the LGT should be treated as an infinite set of global symmetries which are spontaneously broken by the vacuum. It was established that in QED, the Ward identities of their induced symmetries are equivalent to the Soft Photon Theorem. In this paper we study the implications of LGT on the S-matrix between physical asymptotic states in massive QED. In appose to the naively free scattering states, physical asymptotic states incorporate the long range electric field between asymptotic charged particles and were already constructed in 1970 by Kulish and Faddeev. We find that the LGT charge is independent of the particles' momenta and may be associated to the vacuum. The soft theorem's manifestation as a Ward identity turns out to be an outcome of not working with the physical asymptotic states.
OCCUPATION EDUCATION REQUIREMENTS ANALYSIS.
ERIC Educational Resources Information Center
GRIEST, JEANNE; MORSCH, WILLIAM C.
THE OCCUPATIONAL EDUCATION REQUIREMENTS ANALYSIS (OERA) SYSTEM IS A RESEARCH EFFORT DESIGNED TO DEVELOP A FEASIBLE METHOD OF PROJECTING VOCATIONAL EDUCATION REQUIREMENTS THAT WILL SATISFY LABOR MARKET NEEDS. THE OUTPUTS OF THE OERA WILL BE ANNUAL PROJECTIONS OF EMPLOYMENT DEMANDS IN OCCUPATIONS CLASSIFIED BY VOCATIONAL EDUCATION PROGRAMS. THESE…
Testosterone and Occupational Achievement.
ERIC Educational Resources Information Center
Dabbs, James M., Jr.
1992-01-01
Archival data on 4,462 military veterans linked higher levels of serum testosterone to lower-status occupations. A structural equation model was supported in which higher testosterone, mediated through lower intellectual ability, greater antisocial behavior, and lower education, leads away from white-collar occupations. Contains 49 references.…
Leadership and Occupational Stress
ERIC Educational Resources Information Center
Stickle, Fred E.; Scott, Kelly
2016-01-01
In a leadership position, it is important to understand what stress is and how it affects others. In an occupational setting, stressors vary according to personality types, gender, and occupational rank. The purpose of this manuscript is to review the foundations of stress and to explore how personality characteristics influence stress.…
Occupational asthma: a review.
Lombardo, L J; Balmes, J R
2000-01-01
Occupational asthma is the most common form of occupational lung disease in the developed world at the present time. In this review, the epidemiology, pathogenesis/mechanisms, clinical presentations, management, and prevention of occupational asthma are discussed. The population attributable risk of asthma due to occupational exposures is considerable. Current understanding of the mechanisms by which many agents cause occupational asthma is limited, especially for low-molecular-weight sensitizers and irritants. The diagnosis of occupational asthma is generally established on the basis of a suggestive history of a temporal association between exposure and the onset of symptoms and objective evidence that these symptoms are related to airflow limitation. Early diagnosis, elimination of exposure to the responsible agent, and early use of inhaled steroids may play important roles in the prevention of long-term persistence of asthma. Persistent occupational asthma is often associated with substantial disability and consequent impacts on income and quality of life. Prevention of new cases is the best approach to reducing the burden of asthma attributable to occupational exposures. Future research needs are identified. PMID:10931788
ERIC Educational Resources Information Center
Geneva Area City Schools, OH.
The booklet divides job titles, selected from the Dictionary of Occupational Titles, into 15 career clusters: agribusiness and natural resources, business and office education, communication and media, construction, consumer and home economics, fine arts and humanities, health occupations, hospitality and recreation, manufacturing, marine science,…
Counselling for Occupational Development
ERIC Educational Resources Information Center
Nwamuo, P. A.; Ugonna, C. E.
2015-01-01
The aim of the study was to ascertain the general attitude which senior secondary school students display towards counselling for occupational development while determining gender difference in students' attitude towards occupational information. It is also aimed at discovering whether these students seek vocational guidance in their choice of…
Cabinetmaker. Occupational Analysis Series.
ERIC Educational Resources Information Center
Chinien, Chris; Boutin, France
This document contains the analysis of the occupation of cabinetmaker, or joiner, that is accepted by the Canadian Council of Directors as the national standard for the occupation. The front matter preceding the analysis includes exploration of the development of the analysis, structure of the analysis, validation method, scope of the cabinetmaker…
[Market oriented occupational medicine].
Rurik, Imre; Cseh, Károly
2012-09-09
The history and the recent state of occupational medicine in Hungary, and its relation with governmental labor organizations are analyzed. In the past 20 years, large "socialist" factories were replaced by smaller companies employing fewer workers. They have been forced to establish contract with occupational health providers. Many of them offer primary care services, whereas family physicians having a board examination in occupational medicine are allowed to work in this field as well. The market of occupational medicine is less regulated, and ethical rules are not always considered. Undercutting prices is a common practice. The recent system could be improved by some regulations which should be respected. There is no reason to make rough changes establishing a new market for profit oriented insurance companies, and to allow employees and employers to work without specification neglecting international agreements. Occupational medicine should be supervised again by the health authorities instead of economists who have quite different, short-term priorities.
Occupational Infection in Korea
Ahn, Yeon-Soon; Jeong, Jae Sim
2010-01-01
Occupational infection is a human disease caused by work-associated exposure to microbial agents through human and environmental contact. According to the literature, occupational infection was the third leading cause of occupational disease (861 cases, 8.0%), and health care, agricultural, forestry, and fishery workers were risk groups in Korea. In addition, most high-risk groups have not been protected by workers' compensation, which could lead to underestimation of the exact spectrum and magnitude of the problem, and may also result in a lack of development and implementation of occupational infection management. Through a review of national guidelines and documentations on prevention and control of occupational infection, a management strategy would promote adherence to worker safety regulations if it is explicit with regard to the agent and mode of infection in each of the high-risk groups. PMID:21258592
Perspectives in Occupational Dermatology
Mathias, C. G. Toby; Maibach, Howard I.
1982-01-01
Because large surface areas of the skin are exposed directly to the environment, skin is an organ particularly vulnerable to occupationally induced disease. Statistics show that, excluding accidental injury, nearly half of all occupational illnesses occur in this organ; a fourth of all workers suffering from occupational skin disease lose an average of 10 to 12 workdays. The constant evolution of new industrial chemicals and methods of manufacture continue to bring new skin hazards and disease into the workplace. Occupational health physicians and practitioners, who usually have minimal training in dermatology, must diagnose and treat unfamiliar diseases in a setting of even less familiar, often overwhelming, technology. A thorough understanding of cutaneous defense mechanisms, clinical patterns of occupational skin disease and methods for establishing accurate diagnoses is essential. PMID:6219498
Occupations: Military--Civilian Occupational Source Book.
ERIC Educational Resources Information Center
Armed Forces Vocational Testing Group, Universal City, TX.
Information on enlisted military occupations is offered in the source book to arrive at a comprehensive statement of job tasks in the military service and their similarities to jobs in civilian life. Basic information about five areas of the U.S. military services (Army, Navy, Air Force, Marine Corps, and Coast Guard) focuses on their military…
The Occupations of Literacy: Occupational Therapy's Role
ERIC Educational Resources Information Center
Frolek Clark, Gloria
2016-01-01
Nationally, student proficiency in reading and writing is very low and requires ongoing focus from state and local agencies. With almost 25% of occupational therapists working in early intervention and school settings (AOTA, 2015), their role of facilitating literacy (e.g., reading, writing, speaking and listening) is critical. Occupational…
Scattering theory without large-distance asymptotics
NASA Astrophysics Data System (ADS)
Liu, Tong; Li, Wen-Du; Dai, Wu-Sheng
2014-06-01
In conventional scattering theory, to obtain an explicit result, one imposes a precondition that the distance between target and observer is infinite. With the help of this precondition, one can asymptotically replace the Hankel function and the Bessel function with the sine functions so that one can achieve an explicit result. Nevertheless, after such a treatment, the information of the distance between target and observer is inevitably lost. In this paper, we show that such a precondition is not necessary: without losing any information of distance, one can still obtain an explicit result of a scattering rigorously. In other words, we give an rigorous explicit scattering result which contains the information of distance between target and observer. We show that at a finite distance, a modification factor — the Bessel polynomial — appears in the scattering amplitude, and, consequently, the cross section depends on the distance, the outgoing wave-front surface is no longer a sphere, and, besides the phase shift, there is an additional phase (the argument of the Bessel polynomial) appears in the scattering wave function.
Extended Analytic Device Optimization Employing Asymptotic Expansion
NASA Technical Reports Server (NTRS)
Mackey, Jonathan; Sehirlioglu, Alp; Dynsys, Fred
2013-01-01
Analytic optimization of a thermoelectric junction often introduces several simplifying assumptionsincluding constant material properties, fixed known hot and cold shoe temperatures, and thermallyinsulated leg sides. In fact all of these simplifications will have an effect on device performance,ranging from negligible to significant depending on conditions. Numerical methods, such as FiniteElement Analysis or iterative techniques, are often used to perform more detailed analysis andaccount for these simplifications. While numerical methods may stand as a suitable solution scheme,they are weak in gaining physical understanding and only serve to optimize through iterativesearching techniques. Analytic and asymptotic expansion techniques can be used to solve thegoverning system of thermoelectric differential equations with fewer or less severe assumptionsthan the classic case. Analytic methods can provide meaningful closed form solutions and generatebetter physical understanding of the conditions for when simplifying assumptions may be valid.In obtaining the analytic solutions a set of dimensionless parameters, which characterize allthermoelectric couples, is formulated and provide the limiting cases for validating assumptions.Presentation includes optimization of both classic rectangular couples as well as practically andtheoretically interesting cylindrical couples using optimization parameters physically meaningful toa cylindrical couple. Solutions incorporate the physical behavior for i) thermal resistance of hot andcold shoes, ii) variable material properties with temperature, and iii) lateral heat transfer through legsides.
Early Asymptotic Giant Branch: Theory and Observations
NASA Astrophysics Data System (ADS)
Frantsman, Ju.
1995-08-01
While on the asymptotic giant branch (AGB), a star passes through two evolutionary phases: an early stage (E-AGB), and thermally pulsing AGB (TP-AGB). The theory of two AGB stages was developed more than a decade ago but till now some authors do not take into account the E-AGB phase in spite of the fact that E-AGB phase lasts for some stars considerably longer than the TP-AGB phase. The typical outcomes of such ignoration are shown in the report (wrong conclusions about the evolution of Large Magellanic Cloud, the mistakes in the determination of the ages of Magellanic Cloud clusters). The results are obtained using the "population simultaion" technique. The origin of some types of chemically peculiar stars is investigated (S-stars, faint carbon stars, carbon stars bluer and somewhat brighter than in the mean N-Type stars in the Magellanic Clouds). A suggestion is proposed that these stars are on the E-AGB evolutionary stage. They develop chemical peculiarities in the process of mass transfer in close binaries. It was assumed that during the TP-AGB phase, the primary (more massive) component, when being the carbon star, transfered the carbon enriched material by Roche-lobe overflow to the secondary component, which becomes the star with carbon overabundance. During the subsequent evolution the former secondary (and now after mass transfer carbon enriched) component reaches the E-AGB phase. The results of calculations are discussed and compared with observations.
Asymptotic methods for internal transonic flows
NASA Technical Reports Server (NTRS)
Adamson, T. C., Jr.; Messiter, A. F.
1989-01-01
For many internal transonic flows of practical interest, some of the relevant nondimensional parameters typically are small enough that a perturbation scheme can be expected to give a useful level of numerical accuracy. A variety of steady and unsteady transonic channel and cascade flows is studied with the help of systematic perturbation methods which take advantage of this fact. Asymptotic representations are constructed for small changes in channel cross-section area, small flow deflection angles, small differences between the flow velocity and the sound speed, small amplitudes of imposed oscillations, and small reduced frequencies. Inside a channel the flow is nearly one-dimensional except in thin regions immediately downstream of a shock wave, at the channel entrance and exit, and near the channel throat. A study of two-dimensional cascade flow is extended to include a description of three-dimensional compressor-rotor flow which leads to analytical results except in thin edge regions which require numerical solution. For unsteady flow the qualitative nature of the shock-wave motion in a channel depends strongly on the orders of magnitude of the frequency and amplitude of impressed wall oscillations or fluctuations in back pressure. One example of supersonic flow is considered, for a channel with length large compared to its width, including the effect of separation bubbles and the possibility of self-sustained oscillations. The effect of viscosity on a weak shock wave in a channel is discussed.
Burnout in occupational therapists.
Rogers, J C; Dodson, S C
1988-12-01
Burnout is a job-related condition involving feelings of emotional exhaustion, depersonalization, and reduced personal accomplishment. The Maslach Burnout Inventory (Maslach & Jackson, 1981a) is the instrument most widely used to measure job-related stress in human service professions, such as occupational therapy. This study explored the application of the Maslach Burnout Inventory for use with occupational therapists. The subjects were 99 registered occupational therapists residing in the southeastern United States. Mean scores lower than the aggregate occupational norms provided by the test's authors on the Emotional Exhaustion and Depersonalization subscales supported the need to develop specific norms for occupational therapists. Results of this study indicate that use of the aggregate norms would underestimate the level of experienced burnout. Correlational analyses delineated significant relationships between age and Emotional Exhaustion and Depersonalization, education and Emotional Exhaustion and Depersonalization, years of work as an occupational therapist and Depersonalization and Personal Accomplishment, years in the present position and Personal Accomplishment (intensity only), hours of direct patient contact and Emotional Exhaustion (intensity only), and hours of direct patient contact and Depersonalization (frequency only). These correlates of burnout furnish clues for understanding the development of work-related stress in occupational therapists.
Occupational cancer in Britain
Chen, Yiqun; Osman, John
2012-01-01
Although only a relatively small proportion of cancer is attributable to occupational exposure to carcinogenic agents, the estimated number of deaths due to occupational cancer is high when compared to other deaths due to work-related ill health and injury. However, risk from occupational exposure to carcinogens can be minimised through proportionate but effective risk management. The Health and Safety Executive (HSE) is the regulator of workplace health and safety in Great Britain. As part of its aim to reduce ill health arising from failures to control properly exposure to hazards at work, HSE commissioned the research presented elsewhere in this supplement to enable it to identify priorities for preventing occupational cancer. The research has shown that occupational cancer remains a key health issue and that low-level exposure of a large number of workers to carcinogens is important. The finding that a small number of carcinogens have been responsible for the majority of the burden of occupational cancer provides key evidence in the development of priorities for significant reduction of occupational cancer. Although the research presented in this supplement reflects the consequences of past exposures to carcinogens, occupational cancer remains a problem. The potential for exposure to the agents considered in this research is still present in the workplace and the findings are relevant to prevention of future disease. In this article, the principle approaches for risk reduction are described. It provides supporting information on some of the initiatives already being undertaken, or those being put in place, to reduce occupational cancer in Great Britain. The need also for systematic collection of exposure information and the importance of raising awareness and changing behaviours are discussed. PMID:22710673
Asymptotic Structure of Constrained Exponential Random Graph Models
NASA Astrophysics Data System (ADS)
Zhu, Lingjiong
2017-03-01
In this paper, we study exponential random graph models subject to certain constraints. We obtain some general results about the asymptotic structure of the model. We show that there exists non-trivial regions in the phase plane where the asymptotic structure is uniform and there also exists non-trivial regions in the phase plane where the asymptotic structure is non-uniform. We will get more refined results for the star model and in particular the two-star model for which a sharp transition from uniform to non-uniform structure, a stationary point and phase transitions will be obtained.
Coulomb string tension, asymptotic string tension, and the gluon chain
Greensite, Jeff; Szczepaniak, Adam P.
2015-02-01
We compute, via numerical simulations, the non-perturbative Coulomb potential and position-space ghost propagator in pure SU(3) gauge theory in Coulomb gauge. We find that that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.
Articular Contact Mechanics from an Asymptotic Modeling Perspective: A Review
Argatov, Ivan; Mishuris, Gennady
2016-01-01
In the present paper, we review the current state-of-the-art in asymptotic modeling of articular contact. Particular attention has been given to the knee joint contact mechanics with a special emphasis on implications drawn from the asymptotic models, including average characteristics for articular cartilage layer. By listing a number of complicating effects such as transverse anisotropy, non-homogeneity, variable thickness, nonlinear deformations, shear loading, and bone deformation, which may be accounted for by asymptotic modeling, some unsolved problems and directions for future research are also discussed. PMID:27847803
Asymptotic stability properties of linear Volterra integrodifferential equations.
NASA Technical Reports Server (NTRS)
Miller, R. K.
1971-01-01
The Liapunov stability properties of solution to a certain system of Volterra integrodifferential equations is studied. Various types of Liapunov stability are defined; the definitions are natural extensions of the corresponding notions for ordinary differential equations. Necessary and sufficient conditions, in general, for uniform stability and uniform asymptotic stability are obtained in the form of a theorem. Connections between the stability of the system studied and the stability properties of a related Volterra integrodifferential equation with infinite memory are examined. Sufficient conditions in order that the trivial solution to the system studied be stable, uniformly stable, asymptotically stable, or uniformly asymptotically stable are derived.
Uniform Asymptotic Expansion for the Incomplete Beta Function
NASA Astrophysics Data System (ADS)
Nemes, Gergő; Olde Daalhuis, Adri B.
2016-10-01
In [Temme N.M., Special functions. An introduction to the classical functions of mathematical physics, A Wiley-Interscience Publication, John Wiley & Sons, Inc., New York, 1996, Section 11.3.3.1] a uniform asymptotic expansion for the incomplete beta function was derived. It was not obvious from those results that the expansion is actually an asymptotic expansion. We derive a remainder estimate that clearly shows that the result indeed has an asymptotic property, and we also give a recurrence relation for the coefficients.
Occupational health in Yugoslavia.
Krstev, Srmena; Perunicic, Bogoljub; Vidakovic, Aleksandar
2002-01-01
Occupational health in Yugoslavia was once well organized in accordance with WHO declarations and ILO conventions and recommendations. Since the 1990s, the system has been disrupted by destruction of the former Yugoslavia, wars, refugees, changes in the economy, and NATO bombardment. Economic trends, main industries, and employment and unemployment conditions in Yugoslavia are presented. The organization of occupational health services, their tasks, and prevailing problems are discussed. Occupational diseases and relevant research and educational opportunities are described. The authors conclude by suggesting approaches to improving worker's health in the future.
[Occupational asthma in Hungary].
Endre, László
2015-05-10
Occupational asthma belongs to communicable diseases, which should be reported in Hungary. During a 24-year period between January 1990 and December 2013, 180 occupational asthma cases were reported in Hungary (52 cases between 1990 and 1995, 83 cases between 1996 and 2000, 40 cases between 2001 and 2006, and 5 cases between 2007 and 2013). These data are unusual, because according to the official report of the National Korányi Pulmonology Institute in Budapest, at least 14,000 new adult asthma cases were reported in every year between 2000 and 2012 in Hungary. Also, international data indicate that at least 2% of adult patients with asthma have occupational asthma and at least 50 out of 1 million employees develop occupational asthma in each year. In 2003, 631 new occupational asthma patients were reported in the United Kingdom, but only 7 cases in Hungary. Because it is unlikely that the occupational environment in Hungary is much better than anywhere else in the world, it seems that not all new occupational asthma cases are reported in Hungary. Of the 180 reported cases in Hungary, 55 were bakers or other workers in flour mills. There were 11 metal-workers, 10 health care assistants, 9 workers dealing with textiles (tailors, dressmakers, workers in textile industry) and 9 employees worked upon leather and animal fur. According to international data, the most unsafe profession is the animal keeper in scientific laboratories, but only 4 of them were reported as having occupational asthma during the studied 24 years in Hungary. Interestingly, 3 museologists with newly-diagnosed occupational asthma were reported in 2003, but not such cases occurred before or after that year. In this paper the Hungarian literature of occupational asthma is summarized, followed by a review on the classification, pathomechanism, clinical presentation, predisposing factors, diagnostics and therapeutic aspects of the disease. Epidemiological data of adult asthma in Hungary and data from
Galapon, Eric A; Martinez, Kay Marie L
2014-02-08
We obtain an exactification of the Poincaré asymptotic expansion (PAE) of the Hankel integral, [Formula: see text] as [Formula: see text], using the distributional approach of McClure & Wong. We find that, for half-integer orders of the Bessel function, the exactified asymptotic series terminates, so that it gives an exact finite sum representation of the Hankel integral. For other orders, the asymptotic series does not terminate and is generally divergent, but is amenable to superasymptotic summation, i.e. by optimal truncation. For specific examples, we compare the accuracy of the optimally truncated asymptotic series owing to the McClure-Wong distributional method with owing to the Mellin-Barnes integral method. We find that the former is spectacularly more accurate than the latter, by, in some cases, more than 70 orders of magnitude for the same moderate value of b. Moreover, the exactification can lead to a resummation of the PAE when it is exact, with the resummed Poincaré series exhibiting again the same spectacular accuracy. More importantly, the distributional method may yield meaningful resummations that involve scales that are not asymptotic sequences.
Kolmogorov turbulence by matched asymptotic expansions
NASA Astrophysics Data System (ADS)
Lundgren, Thomas S.
2003-04-01
The Kolmogorov [Dokl. Akad. Nauk. SSSR 30, 299 (1941), hereafter K41] inertial range theory is derived from first principles by analysis of the Navier-Stokes equation using the method of matched asymptotic expansions without assuming isotropy or homogeneity and the Kolmogorov (K62) [J. Fluid Mech. 13, 82 (1962)] refined theory is analyzed. This paper is an extension of Lundgren [Phys. Fluids 14, 638 (2002)], in which the second- and third-order structure functions were determined from the isotropic Karman-Howarth [Proc. R. Soc. London, Ser. A 164, 192 (1938)] equation. The starting point for the present analysis is an equation for the difference in velocity between two points, one of which is a Lagrangian fluid point and the second, slaved to the first by a fixed separation r, is not Lagrangian. The velocity difference, so defined, satisfies the Navier-Stokes equation with spatial variable r. The analysis is carried out in two parts. In the first part the physical hypothesis is made that the mean dissipation is independent of viscosity as viscosity tends to zero, as assumed in K41. This means that the mean dissipation is finite as Reynolds number tends to infinity and leads to the K41 inertial range results. In the second part this dissipation assumption is relaxed in an attempt to duplicate the K62 theory. While the K62 structure is obtained, there are restrictions, resulting from the analysis which shows that there can be no inertial range intermittency as Reynolds number tends to infinity, and therefore the mean dissipation has to be finite as Reynolds number tends to infinity, as assumed in part one. Reynolds number-dependent corrections to the K41 results are obtained in the form of compensating functions of r/λ, which tend to zero slowly like Rλ-2/3 as Rλ→∞.
Occupational Analysis and Training.
ERIC Educational Resources Information Center
Shears, Arthur E.
1985-01-01
A form of occupational analysis called DACUM (Developing a Curriculum) and its advantages in course development and performance assessment are discussed and specific suggestions on conducting a DACUM session are provided. (CT)
"Homosexual occupations" in Mesoamerica?
Murray, S O
1991-01-01
Data gathered among self-identified homosexual men in Guatemala City and Mexico City call into question the intrinsic connection between homosexuality and occupational choice posited by Whitam and Mathy (1986). Concentrations of homosexual men in some occupations can be explained as effects of discrimination and of the normal transmission through personal networks of information about job opportunities, and does not require recourse to any innate drive for homosexual men to be actors, hairdressers or interior decorators.
Asymptotic analysis of numerical wave propagation in finite difference equations
NASA Technical Reports Server (NTRS)
Giles, M.; Thompkins, W. T., Jr.
1983-01-01
An asymptotic technique is developed for analyzing the propagation and dissipation of wave-like solutions to finite difference equations. It is shown that for each fixed complex frequency there are usually several wave solutions with different wavenumbers and the slowly varying amplitude of each satisfies an asymptotic amplitude equation which includes the effects of smoothly varying coefficients in the finite difference equations. The local group velocity appears in this equation as the velocity of convection of the amplitude. Asymptotic boundary conditions coupling the amplitudes of the different wave solutions are also derived. A wavepacket theory is developed which predicts the motion, and interaction at boundaries, of wavepackets, wave-like disturbances of finite length. Comparison with numerical experiments demonstrates the success and limitations of the theory. Finally an asymptotic global stability analysis is developed.
Asymptotically anti-de Sitter spacetimes in topologically massive gravity
Henneaux, Marc; Martinez, Cristian; Troncoso, Ricardo
2009-04-15
We consider asymptotically anti-de Sitter spacetimes in three-dimensional topologically massive gravity with a negative cosmological constant, for all values of the mass parameter {mu} ({mu}{ne}0). We provide consistent boundary conditions that accommodate the recent solutions considered in the literature, which may have a slower falloff than the one relevant for general relativity. These conditions are such that the asymptotic symmetry is in all cases the conformal group, in the sense that they are invariant under asymptotic conformal transformations and that the corresponding Virasoro generators are finite. It is found that, at the chiral point |{mu}l|=1 (where l is the anti-de Sitter radius), allowing for logarithmic terms (absent for general relativity) in the asymptotic behavior of the metric makes both sets of Virasoro generators nonzero even though one of the central charges vanishes.
Asymptotics of 6j and 10j symbols
NASA Astrophysics Data System (ADS)
Freidel, Laurent; Louapre, David
2003-04-01
It is well known that the building blocks for state sum models of quantum gravity are given by 6j and 10j symbols. In this work, we study the asymptotics of these symbols by using their expressions as group integrals. We carefully describe the measure involved in terms of invariant variables and develop new technics in order to study their asymptotics. Using these technics, we compute the asymptotics of the various Euclidean and Lorentzian 6j symbols. Finally, we compute the asymptotic expansion of the 10j symbol which is shown to be non-oscillating, in agreement with a recent result of Baez et al. We discuss the physical origin of this behaviour and a way to modify the Barrett-Crane model in order to cure this disease.
Asymptotic expansions of Feynman integrals of exponentials with polynomial exponent
NASA Astrophysics Data System (ADS)
Kravtseva, A. K.; Smolyanov, O. G.; Shavgulidze, E. T.
2016-10-01
In the paper, an asymptotic expansion of path integrals of functionals having exponential form with polynomials in the exponent is constructed. The definition of the path integral in the sense of analytic continuation is considered.
An asymptotic model in acoustics: acoustic drift equations.
Vladimirov, Vladimir A; Ilin, Konstantin
2013-11-01
A rigorous asymptotic procedure with the Mach number as a small parameter is used to derive the equations of mean flows which coexist and are affected by the background acoustic waves in the limit of very high Reynolds number.
González, C A; Agudo, A
1999-01-01
The knowledge of specific problems of occupational cancer in Spain is scarce. The environment of the workplace has improved over the last few years after a long period distinguished by bad working conditions, incomplete legislation, and insufficient safety measures and control. It has been estimated that 3,083,479 workers (25.4% of employees) were exposed to carcinogens. The most common occupational exposures to carcinogenic agents were solar radiation, environmental tobacco smoke, silica, and wood dust. The highest number of employees were exposed to silica crystalline (404,729), diesel engine exhaust (274,321), rubber products (99,804), benzene (89,932), ethylene dibromide (81,336), agents used in furniture and cabinet making (72,068), and formaldehyde (71,189). The percentage of total cancer deaths attributed to occupational exposure was 4% (6% in men, 0.9% in women). Compared with other European countries, the incidence of lung cancer and leukemia in Spain are one of the lowest, but it is rapidly increasing. The incidence of urinary bladder and larynx cancer, on the contrary, are one of the highest. Few studies on occupational cancer have been conducted in Spain. The main problems are the availability of death certificates and the quality of the information on occupation in mortality of statistics. It is necessary to improve methods of assessment of exposures using expert hygienists and biologic markers of exposure and diseases. Reduction of cancer by limiting or avoiding exposure to known occupational carcinogens is still necessary. PMID:10350510
Quick asymptotic expansion aided by a variational principle
Hameiri, Eliezer
2013-02-15
It is shown how expanding asymptotically a variational functional can yield the asymptotic expansion of its Euler equation. The procedure is simple but novel and requires taking the variation of the expanded functional with respect to the leading order of the originally unknown function, even though the leading order of this function has already been determined in a previous order. An example is worked out that of a large aspect ratio tokamak plasma equilibrium state with relatively strong flows and high plasma beta.
Asymptotic-induced numerical methods for conservation laws
NASA Technical Reports Server (NTRS)
Garbey, Marc; Scroggs, Jeffrey S.
1990-01-01
Asymptotic-induced methods are presented for the numerical solution of hyperbolic conservation laws with or without viscosity. The methods consist of multiple stages. The first stage is to obtain a first approximation by using a first-order method, such as the Godunov scheme. Subsequent stages of the method involve solving internal-layer problems identified by using techniques derived via asymptotics. Finally, a residual correction increases the accuracy of the scheme. The method is derived and justified with singular perturbation techniques.
Asymptotic relation between Bell-inequality violations and entanglement distillability
Kwon, Younghun
2010-11-15
We investigate the asymptotic relation between violations of the Mermin-Belinskii-Klyshko inequality and the entanglement distillability of multipartite entangled states, as the number of parties increases. We in particular consider noisy multiqubit GHZ and so-called Duer states in the Mermin-Belinskii-Klyshko inequality, and show that, in the asymptotic limit of the number of parties, the violation of the inequality implies the distillability in almost all bipartitions.
Asymptotic Expansion in Enzyme Reactions with High Enzyme Concentrations
NASA Astrophysics Data System (ADS)
Bersani, Alberto Maria; Dell'Acqua, Guido
2010-09-01
In this paper we find a new asymptotic expansion valid in enzymatic reactions where the total amount of enzyme exceeds greatly the total amount of substrate. In such case it is well known that the Michelis-Menten approximation is no longer valid; therefore our asymptotic expansion is a new tool to approximate in a closed form the concentrations of the reactants in presence of an enzyme excess.
Globally uniformly asymptotical stabilisation of time-delay nonlinear systems
NASA Astrophysics Data System (ADS)
Cai, Xiushan; Han, Zhengzhi; Zhang, Wei
2011-07-01
Globally uniformly asymptotical stabilisation of nonlinear systems in feedback form with a delay arbitrarily large in the input is dealt with based on the backstepping approach in this article. The design strategy depends on the construction of a Lyapunov-Krasovskii functional. A continuously differentiable control law is obtained to globally uniformly asymptotically stabilise the closed-loop system. The simulation shows the effectiveness of the method.
NASA Astrophysics Data System (ADS)
Thieme, Horst R.
The concept of asymptotic proportionality and conditional asymptotic equality which is presented here aims at making global asymptotic stability statements for time-heterogeneous difference and differential equations. For such non-autonomous problems (apart from special cases) no prominent special solutions (equilibra, periodic solutions) exist which are natural candidates for the asymptotic behaviour of arbitrary solutions. One way out of this dilemma consists in looking for conditions under which any two solutions to the problem (with different initial conditions) behave in a similar or even the same way as time tends to infinity. We study a general sublinear difference equation in an ordered Banach space and, for illustration, time-heterogeneous versions of several well-known differential equations modelling the spread of gonorrhea in a heterogeneous population, the spread of a vector-borne infectious disease, and the dynamics of a logistically growing spatially diffusing population.
Occupational health in Singapore.
Koh, D; Jeyaratnam, J
1998-07-01
Singapore, a newly industrializing country in Southeast Asia, has a resident population of 3 million and a work force of 1.75 million. Most workers are employed in the manufacturing, services, and commerce sectors. Agricultural and mining activities are negligible. In 1996 the infant mortality rate was 3.8 per 1,000 live births and the life expectancy at birth was 77 years. In 1996 the total industrial accident rate was 2.7 per million man-hours worked and the severity rate was 353 industrial man-days lost per million man-hours worked. The shipbuilding and construction industries had the most frequent and most severe accidents. In the same year, 1,521 cases of occupational disease were notified to, and confirmed by, the Ministry of Labor. The majority of cases involved noise-induced hearing loss. There is substantial underreporting of cases. New cases that are expected to appear will be work-related illnesses such as musculoskeletal or psychosocial disorders. The principal occupational health legislation in Singapore is the Factories Act. Although it selectively targets workers at highest risk of developing occupational illness, its main limitation is the exclusion of nonfactory workers, who comprise 63% of the working population. Labor regulations are enforced by the Ministry of Labor. Workmen's compensation paid in 1995 amounted to S $46.6 million (U.S. $1=S $1.75). Education and training in occupational health is provided by employer federations, employee unions, and various government agencies. Occupational health is taught to medical students during their undergraduate training. Postgraduate-diploma and Masters programs in occupational medicine are also available. About 600 doctors in Singapore have some form of postgraduate training in occupational health. Health care for workers is offered either through the private sector or through government clinics and hospitals. Although Singapore has made great strides in protecting and promoting the health of its
[Somnology and occupational safety].
Dorokhov, V B
2013-01-01
Somnology has saved up enough great volume of objective knowledge of negative effects of a lack of the sleep, the raised drowsiness and sleep pathologies for health of people and occupational safety to formulate this knowledge in the accessible form for a society and acceptance by the state of acts and the organizational actions preventing these negative effects. The necessity of the salvation of these problems has led to occurrence of a new area of occupational sleep medicine, which problem is the analysis of influence of physiological mechanisms ofa sleep and functioning circadian systems on efficiency of professional activity and health of people. For a designation of the various items causing infringements of professional work use the term fatique. It is believed that fatigue development is connected with three major factors: deficiency of a sleep - defined by duration of previous wakefulness and a sleep, time-of-day and at last, task-related factors. Within the limits of approaches developed the occupational sleep medicine had been formulated the Fatigue Risk Management System. In the Russian literature there is a lack of the information on influence of mechanisms of a sleep on occupational safety, therefore the review will be interesting to a wide range of the experts dealing with the analysis of the human factor, health and an occupational safety
Size Matters: Individual Variation in Ectotherm Growth and Asymptotic Size
King, Richard B.
2016-01-01
Body size, and, by extension, growth has impacts on physiology, survival, attainment of sexual maturity, fecundity, generation time, and population dynamics, especially in ectotherm animals that often exhibit extensive growth following attainment of sexual maturity. Frequently, growth is analyzed at the population level, providing useful population mean growth parameters but ignoring individual variation that is also of ecological and evolutionary significance. Our long-term study of Lake Erie Watersnakes, Nerodia sipedon insularum, provides data sufficient for a detailed analysis of population and individual growth. We describe population mean growth separately for males and females based on size of known age individuals (847 captures of 769 males, 748 captures of 684 females) and annual growth increments of individuals of unknown age (1,152 males, 730 females). We characterize individual variation in asymptotic size based on repeated measurements of 69 males and 71 females that were each captured in five to nine different years. The most striking result of our analyses is that asymptotic size varies dramatically among individuals, ranging from 631–820 mm snout-vent length in males and from 835–1125 mm in females. Because female fecundity increases with increasing body size, we explore the impact of individual variation in asymptotic size on lifetime reproductive success using a range of realistic estimates of annual survival. When all females commence reproduction at the same age, lifetime reproductive success is greatest for females with greater asymptotic size regardless of annual survival. But when reproduction is delayed in females with greater asymptotic size, lifetime reproductive success is greatest for females with lower asymptotic size when annual survival is low. Possible causes of individual variation in asymptotic size, including individual- and cohort-specific variation in size at birth and early growth, warrant further investigation. PMID
Size Matters: Individual Variation in Ectotherm Growth and Asymptotic Size.
King, Richard B; Stanford, Kristin M; Jones, Peter C; Bekker, Kent
2016-01-01
Body size, and, by extension, growth has impacts on physiology, survival, attainment of sexual maturity, fecundity, generation time, and population dynamics, especially in ectotherm animals that often exhibit extensive growth following attainment of sexual maturity. Frequently, growth is analyzed at the population level, providing useful population mean growth parameters but ignoring individual variation that is also of ecological and evolutionary significance. Our long-term study of Lake Erie Watersnakes, Nerodia sipedon insularum, provides data sufficient for a detailed analysis of population and individual growth. We describe population mean growth separately for males and females based on size of known age individuals (847 captures of 769 males, 748 captures of 684 females) and annual growth increments of individuals of unknown age (1,152 males, 730 females). We characterize individual variation in asymptotic size based on repeated measurements of 69 males and 71 females that were each captured in five to nine different years. The most striking result of our analyses is that asymptotic size varies dramatically among individuals, ranging from 631-820 mm snout-vent length in males and from 835-1125 mm in females. Because female fecundity increases with increasing body size, we explore the impact of individual variation in asymptotic size on lifetime reproductive success using a range of realistic estimates of annual survival. When all females commence reproduction at the same age, lifetime reproductive success is greatest for females with greater asymptotic size regardless of annual survival. But when reproduction is delayed in females with greater asymptotic size, lifetime reproductive success is greatest for females with lower asymptotic size when annual survival is low. Possible causes of individual variation in asymptotic size, including individual- and cohort-specific variation in size at birth and early growth, warrant further investigation.
Asymptotics of bivariate generating functions with algebraic singularities
NASA Astrophysics Data System (ADS)
Greenwood, Torin
Flajolet and Odlyzko (1990) derived asymptotic formulae the coefficients of a class of uni- variate generating functions with algebraic singularities. Gao and Richmond (1992) and Hwang (1996, 1998) extended these results to classes of multivariate generating functions, in both cases by reducing to the univariate case. Pemantle and Wilson (2013) outlined new multivariate ana- lytic techniques and used them to analyze the coefficients of rational generating functions. After overviewing these methods, we use them to find asymptotic formulae for the coefficients of a broad class of bivariate generating functions with algebraic singularities. Beginning with the Cauchy integral formula, we explicity deform the contour of integration so that it hugs a set of critical points. The asymptotic contribution to the integral comes from analyzing the integrand near these points, leading to explicit asymptotic formulae. Next, we use this formula to analyze an example from current research. In the following chapter, we apply multivariate analytic techniques to quan- tum walks. Bressler and Pemantle (2007) found a (d + 1)-dimensional rational generating function whose coefficients described the amplitude of a particle at a position in the integer lattice after n steps. Here, the minimal critical points form a curve on the (d + 1)-dimensional unit torus. We find asymptotic formulae for the amplitude of a particle in a given position, normalized by the number of steps n, as n approaches infinity. Each critical point contributes to the asymptotics for a specific normalized position. Using Groebner bases in Maple again, we compute the explicit locations of peak amplitudes. In a scaling window of size the square root of n near the peaks, each amplitude is asymptotic to an Airy function.
Population Health and Occupational Therapy.
Braveman, Brent
2016-01-01
Occupational therapy practitioners play an important role in improving the health of populations through the development of occupational therapy interventions at the population level and through advocacy to address occupational participation and the multiple determinants of health. This article defines and explores population health as a concept and describes the appropriateness of occupational therapy practice in population health. Support of population health practice as evidenced in the official documents of the American Occupational Therapy Association and the relevance of population health for occupational therapy as a profession are reviewed. Recommendations and directions for the future are included related to celebration of the achievements of occupational therapy practitioners in the area of population health, changes to the Occupational Therapy Practice Framework and educational accreditation standards, and the importance of supporting, recognizing, rewarding, and valuing occupational therapy practitioners who assume roles in which direct care is not their primary function.
Kim, Kyoo Sang
2010-01-01
Occupational asthma (OA) is the leading occupational respiratory disease. Cases compensated as OA by the Korea Workers' Compensation and Welfare Service (COMWEL) (218 cases), cases reported by a surveillance system (286 cases), case reports by related scientific journals and cases confirmed by the Occupational Safety and Health Research Institute (OSHRI) over 15 yr from 1992 to 2006 were analyzed. Annual mean incidence rate was 1.6 by compensation and 3.5 by surveillance system, respectively. The trend appeared to increase according to the surveillance system. Incidence was very low compared with other countries. The most frequently reported causative agent was isocyanate followed by reactive dye in dyeing factories. Other chemicals, metals and dust were also found as causative agents. OA was underreported according to compensation and surveillance system data. In conclusion, a more effective surveillance system is needed to evaluate OA causes and distribution, and to effectively prevent newly developing OA. PMID:21258586
Coultas, D.B.; Samet, J.M. )
1992-06-01
The overall importance of occupational agents as a cause of lung cancer has been a controversial subject since the 1970s. A federal report, released in the late 1970s, projected a surprisingly high burden of occupational lung cancer; for asbestos and four other agents, from 61,000 to 98,000 cases annually were attributed to these agents alone. Many estimates followed, some much more conservative. For example, Doll and Peto estimated that 15% of lung cancer in men and 5% in women could be attributed to occupational exposures. A number of population-based case-control studies also provide relevant estimates. In a recent literature review, Vineis and Simonato cited attributable risk estimates for occupation and lung cancer that ranged from 4% to 40%; for asbestos alone, the estimates ranged from 1% to 5%. These estimates would be expected to vary across locations and over time. Nevertheless, these recent estimates indicate that occupation remains an important cause of lung cancer. Approaches to Prevention. Prevention of lung cancer mortality among workers exposed to agents or industrial processes that cause lung cancer may involve several strategies, including eliminating or reducing exposures, smoking cessation, screening, and chemo-prevention. For example, changes in industrial processes that have eliminated or reduced exposures to chloromethyl ethers and nickel compounds have provided evidence of reduced risk of lung cancer following these changes. Although occupational exposures are important causes of lung cancer, cigarette smoking is the most important preventable cause of lung cancer. For adults, the work site offers an important location to target smoking cessation efforts. In fact, the work site may be the only place to reach many smokers.
Lees, R. E. M.
1982-01-01
The skin and the respiratory tract are susceptible to sensitization by a wide range of substances encountered in the occupational environment. The responses of these two anatomical sites are discussed with particular attention to late and dual asthmatic reactions, which may cause diagnostic problems for the unwary. There are few data on the incidence and prevalence of occupational allergic reactions, but some estimated frequencies are given. Tables list the major industrial skin and respiratory sensitizing agents. The importance of a detailed history is stressed, as is the role of the family physician in identifying and documenting agents capable of sensitizing exposed workers. ImagesFig. 1Fig. 2 PMID:21286199
Cheng, Philip; Drake, Christopher
2016-03-01
Sleep and circadian rhythms significantly impact almost all aspects of human behavior and are therefore relevant to occupational sleep medicine, which is focused predominantly around workplace productivity, safety, and health. In this article, 5 main factors that influence occupational functioning are reviewed: (1) sleep deprivation, (2) disordered sleep, (3) circadian rhythms, (4) common medical illnesses that affect sleep and sleepiness, and (5) medications that affect sleep and sleepiness. Consequences of disturbed sleep and sleepiness are also reviewed, including cognitive, emotional, and psychomotor functioning and drowsy driving.
Black hole thermodynamics from a variational principle: asymptotically conical backgrounds
An, Ok Song; Cvetič, Mirjam; Papadimitriou, Ioannis
2016-03-14
The variational problem of gravity theories is directly related to black hole thermodynamics. For asymptotically locally AdS backgrounds it is known that holographic renormalization results in a variational principle in terms of equivalence classes of boundary data under the local asymptotic symmetries of the theory, which automatically leads to finite conserved charges satisfying the first law of thermodynamics. We show that this connection holds well beyond asymptotically AdS black holes. In particular, we formulate the variational problem for N = 2 STU supergravity in four dimensions with boundary conditions corresponding to those obeyed by the so called ‘subtracted geometries’. Wemore » show that such boundary conditions can be imposed covariantly in terms of a set of asymptotic second class constraints, and we derive the appropriate boundary terms that render the variational problem well posed in two different duality frames of the STU model. This allows us to define finite conserved charges associated with any asymptotic Killing vector and to demonstrate that these charges satisfy the Smarr formula and the first law of thermodynamics. Moreover, by uplifting the theory to five dimensions and then reducing on a 2-sphere, we provide a precise map between the thermodynamic observables of the subtracted geometries and those of the BTZ black hole. Finally, surface terms play a crucial role in this identification.« less
Black hole thermodynamics from a variational principle: asymptotically conical backgrounds
An, Ok Song; Cvetič, Mirjam; Papadimitriou, Ioannis
2016-03-14
The variational problem of gravity theories is directly related to black hole thermodynamics. For asymptotically locally AdS backgrounds it is known that holographic renormalization results in a variational principle in terms of equivalence classes of boundary data under the local asymptotic symmetries of the theory, which automatically leads to finite conserved charges satisfying the first law of thermodynamics. We show that this connection holds well beyond asymptotically AdS black holes. In particular, we formulate the variational problem for N = 2 STU supergravity in four dimensions with boundary conditions corresponding to those obeyed by the so called ‘subtracted geometries’. We show that such boundary conditions can be imposed covariantly in terms of a set of asymptotic second class constraints, and we derive the appropriate boundary terms that render the variational problem well posed in two different duality frames of the STU model. This allows us to define finite conserved charges associated with any asymptotic Killing vector and to demonstrate that these charges satisfy the Smarr formula and the first law of thermodynamics. Moreover, by uplifting the theory to five dimensions and then reducing on a 2-sphere, we provide a precise map between the thermodynamic observables of the subtracted geometries and those of the BTZ black hole. Finally, surface terms play a crucial role in this identification.
Conserved Charges in Asymptotically (Locally) AdS Spacetimes
NASA Astrophysics Data System (ADS)
Marolf, Donald; Kelly, William; Fischetti, Sebastian
When a physical system is complicated and nonlinear, global symmetries and the associated conserved quantities provide some of the most powerful analytic tools to understand its behavior. This is as true in theories with a dynamical spacetime metric as for systems defined on a fixed spacetime background. Chapter 17, 10.1007/978-3-642-41992-8_17 has already discussed the so-called Arnowitt-Deser-Misner (ADM) conserved quantities for asymptotically flat dynamical spacetimes, exploring in detail certain subtleties related to diffeomorphism invariance. In particular, it showed that the correct notion of global symmetry is given by the so-called asymptotic symmetries; equivalence classes of diffeomorphisms with the same asymptotic behavior at infinity. It was also noted that the notion of asymptotic symmetry depends critically on the choice of boundary conditions. Indeed, it is the imposition of boundary conditions that causes the true gauge symmetries to be only a subset of the full diffeomorphism group and thus allows the existence of nontrivial asymptotic symmetries at all.
Preheating in an asymptotically safe quantum field theory
NASA Astrophysics Data System (ADS)
Svendsen, Ole; Moghaddam, Hossein Bazrafshan; Brandenberger, Robert
2016-10-01
We consider reheating in a class of asymptotically safe quantum field theories recently studied in [D. F. Litim and F. Sannino, Asymptotic safety guaranteed, J. High Energy Phys. 12 (2014) 178; D. F. Litim, M. Mojaza, and F. Sannino, Vacuum stability of asymptotically safe gauge-Yukawa theories, J. High Energy Phys. 01 (2016) 081]. These theories allow for an inflationary phase in the very early universe. Inflation ends with a period of reheating. Since the models contain many scalar fields which are intrinsically coupled to the inflaton there is the possibility of parametric resonance instability in the production of these fields, and the danger that the induced curvature fluctuations will become too large. Here we show that the parametric instability indeed arises, and that hence the energy transfer from the inflaton condensate to fluctuating fields is rapid. Demanding that the curvature fluctuations induced by the parametrically amplified entropy modes do not exceed the upper observational bounds puts a lower bound on the number of fields which the model followed in [D. F. Litim and F. Sannino, Asymptotic safety guaranteed, J. High Energy Phys. 12 (2014) 178; D. F. Litim, M. Mojaza, and F. Sannino, Vacuum stability of asymptotically safe gauge-Yukawa theories, J. High Energy Phys. 01 (2016) 081] must contain. This bound also depends on the total number of e -foldings of the inflationary phase.
Scale-invariant cascades in turbulence and evolution
NASA Astrophysics Data System (ADS)
Guttenberg, Nicholas Ryan
In this dissertation, I present work addressing three systems which are traditionally considered to be unrelated: turbulence, evolution, and social organization. The commonality between these systems is that in each case, microscopic interaction rules give rise to an emergent behavior that in some way makes contact with the macroscopic scale of the problem. The open-ended evolution of complexity in evolving systems is analogous to the scale-free structure established in turbulent flows through local transportation of energy. In both cases, an invariance is required for the cascading behavior to occur, and in both cases the scale-free structure is built up from some initial scale from which the behavior is fed. In turbulence, I examine the case of two-dimensional turbulence in order to support the hypothesis that the friction factor and velocity profile of turbulent pipe flows depend on the turbulent energy spectrum in a way unpredicted by the classic Prandtl theory. By simulating two-dimensional flows in controlled geometries, either an inverse energy cascade or forward enstrophy cascade can be produced. The friction factor scaling of the flow changes depending on which cascade is present, in a way consistent with momentum transfer theory and roughness-induced criticality. In the problem of evolution, I show that open-ended growth of complexity can be obtained by ensuring that the evolutionary dynamics are invariant with respect to changes in complexity. Finite system size, finite point mutation rate, and fixed points in the fitness landscape can all interrupt this cascade behavior, producing an analogue to the integral scale of turbulence. This complexity cascade can exist both for competing and for symbiotic sets of organisms. Extending this picture to the qualitatively-different levels of organization of real lifeforms (viruses, unicellular, biofilms, multicellular) requires an understanding of how the processes of evolution themselves evolve. I show that a separation of spatial or temporal scales can enhance selection pressure on parameters that only matter several generations down the line. Because of this, I conclude that the prime candidates for the emergence of novel evolutionary mechanisms are biofilms and things living in oscillating environments. Finally, in the problem of social organization, I show that different types of control hierarchies - leaders or communal decision making - can emerge depending on the relationship between the environment in which members of the social group act and the development and exchange of information.
Scale-invariant properties of public-debt growth
NASA Astrophysics Data System (ADS)
Petersen, A. M.; Podobnik, B.; Horvatic, D.; Stanley, H. E.
2010-05-01
Public debt is one of the important economic variables that quantitatively describes a nation's economy. Because bankruptcy is a risk faced even by institutions as large as governments (e.g., Iceland), national debt should be strictly controlled with respect to national wealth. Also, the problem of eliminating extreme poverty in the world is closely connected to the study of extremely poor debtor nations. We analyze the time evolution of national public debt and find "convergence": initially less-indebted countries increase their debt more quickly than initially more-indebted countries. We also analyze the public debt-to-GDP ratio {\\cal R} , a proxy for default risk, and approximate the probability density function P({\\cal R}) with a Gamma distribution, which can be used to establish thresholds for sustainable debt. We also observe "convergence" in {\\cal R} : countries with initially small {\\cal R} increase their {\\cal R} more quickly than countries with initially large {\\cal R} . The scaling relationships for debt and {\\cal R} have practical applications, e.g. the Maastricht Treaty requires members of the European Monetary Union to maintain {\\cal R} < 0.6 .
USE OF SCALE INVARIANCE IN EVALUATING JUDGEMENT INDICATORS
Indicators are used to draw conclusions about ecological endpoints when these endpoints cannot be measured directly. In many cases, inference about an endpoint are only possible because assumptions have been made about the relationship between indicator and endpoint; we refer to ...
Classically scale invariant inflation, supermassive WIMPs, and adimensional gravity
NASA Astrophysics Data System (ADS)
Farzinnia, Arsham; Kouwn, Seyen
2016-03-01
We introduce a minimal and yet comprehensive framework with C P and classical scale symmetries in order to simultaneously address the hierarchy problem, neutrino masses, dark matter, and inflation. One complex gauge singlet scalar and three flavors of the right-handed Majorana neutrinos are added to the standard model content, facilitating the see-saw mechanism, among others. An adimensional theory of gravity (Agravity) is employed, allowing for the trans-Planckian field excursions. The weak and Planck scales are induced by the Higgs portal and the scalar nonminimal couplings, respectively, once a Coleman-Weinberg dynamically generated vacuum expectation value for the singlet scalar is obtained. All scales are free from any mutual quadratic destabilization. The C P symmetry prevents a decay of the pseudoscalar singlet, rendering it a suitable WIMPzilla dark matter candidate with the correct observational relic abundance. Identifying the pseudo-Nambu-Goldstone boson of the (approximate) scale symmetry with the inflaton field, the model accommodates successful slow-roll inflation, compatible with the observational data. We reach the conclusion that a pseudo-Nambu-Goldstone inflaton, within a classically scale-symmetric framework, yields lighter WIMPzillas.
Scale Invariant Impacts of Valley Fills on Hydrology
NASA Astrophysics Data System (ADS)
Zegre, N.; Miller, A. J.
2014-12-01
Mountaintop removal mining and valley fill (MTM/VF) is a dominant driver of land cover change, impacting 6.8% of the largely forested 4.86 million ha Appalachian coal fields region. Recent catastrophic flooding and documented biological impairment downstream of MTM/VF has drawn sharp criticism of this practice. Despite its extent, scale, and continued use since the 1970's, the impacts of MTM/VF on hydrology is poorly understood. The goal of this research is to quantify the hydrological impacts of this practice in a headwater and a mesoscale catchment at storm, seasonal, and annual timeframes. Results show a general trend in the conversion of forests to mines, and significant decreases in maximum streamflow and variability, and increases in base flow ratio attributed to valley fills and deep mine drainage. Decreases in variability are shown across spatial and temporal scales having important implications for water quantity and quality.
Occupational Orientation: Industrial Oriented Occupations. Experimental Curriculum Materials.
ERIC Educational Resources Information Center
Illinois State Office of Education, Springfield.
These experimental curriculum materials, for one of five clusters developed for the occupational orientation program in Illinois, contain teacher references and a series of learning activity packages (LAPs) designed to acquaint the student with the wide range of occupational choices available in the industrial oriented occupations field. The 30…
Holography of 3D asymptotically flat black holes
NASA Astrophysics Data System (ADS)
Fareghbal, Reza; Hosseini, Seyed Morteza
2015-04-01
We study the asymptotically flat rotating hairy black hole solution of a three-dimensional gravity theory which is given by taking the flat-space limit (zero cosmological constant limit) of new massive gravity. We propose that the dual field theory of the flat-space limit of new massive gravity can be described by a contracted conformal field theory which is invariant under the action of the BMS3 group. Using the flat/contracted conformal field theory correspondence, we construct a stress tensor which yields the conserved charges of the asymptotically flat black hole solution. We check that our expressions of the mass and angular momentum fit with the first law of black hole thermodynamics. Furthermore, by taking the appropriate limit of the Cardy formula in the parent conformal field theory, we find a Cardy-like formula which reproduces the Wald's entropy of the 3D asymptotically flat black hole.
Asymptotically Jλ -statistical equivalent sequences of weight g
NASA Astrophysics Data System (ADS)
Savaş, Ekrem
2016-08-01
This paper presents the following definition which is a natural combination of the definition for asymptotically equivalent of weight g, J -statistically limit, and λ - statistical convergence, where g :ℕ →[0 , ∞ ) is a function satisfying g (n) → ∞ and g(n) ↛ 0. The two nonnegative sequences x = (xk) and y = (yk) are said to be asymptotically Jg -statistical equivalent of weight g to multiple L provided that for every ɛ > 0, and δ > 0, {n ∈ℕ : 1/g (λn) |{k ∈In:|x/k yk -L | ≥ɛ }| ≥δ }∈J , (denoted by x ˜SλL(I) g y ) and simply asymptotically Jg -statistical equivalent of weight g if L = 1. In addition, we shall also present some inclusion theorems.
Revisiting r > g-The asymptotic dynamics of wealth inequality
NASA Astrophysics Data System (ADS)
Berman, Yonatan; Shapira, Yoash
2017-02-01
Studying the underlying mechanisms of wealth inequality dynamics is essential for its understanding and for policy aiming to regulate its level. We apply a heterogeneous non-interacting agent-based modeling approach, solved using iterated maps to model the dynamics of wealth inequality based on 3 parameters-the economic output growth rate g, the capital value change rate a and the personal savings rate s and show that for a < g the wealth distribution reaches an asymptotic shape and becomes close to the income distribution. If a > g, the wealth distribution constantly becomes more and more inegalitarian. We also show that when a < g, wealth is asymptotically accumulated at the same rate as the economic output, which also implies that the wealth-disposable income ratio asymptotically converges to s /(g - a) .
A new class of asymptotically non-chaotic vacuum singularities
Klinger, Paul
2015-12-15
The BKL conjecture, stated in the 1960s and early 1970s by Belinski, Khalatnikov and Lifschitz, proposes a detailed description of the generic asymptotic dynamics of spacetimes as they approach a spacelike singularity. It predicts complicated chaotic behaviour in the generic case, but simpler non-chaotic one in cases with symmetry assumptions or certain kinds of matter fields. Here we construct a new class of four-dimensional vacuum spacetimes containing spacelike singularities which show non-chaotic behaviour. In contrast with previous constructions, no symmetry assumptions are made. Rather, the metric is decomposed in Iwasawa variables and conditions on the asymptotic evolution of some of them are imposed. The constructed solutions contain five free functions of all space coordinates, two of which are constrained by inequalities. We investigate continuous and discrete isometries and compare the solutions to previous constructions. Finally, we give the asymptotic behaviour of the metric components and curvature.
Asymptotically free scaling solutions in non-Abelian Higgs models
NASA Astrophysics Data System (ADS)
Gies, Holger; Zambelli, Luca
2015-07-01
We construct asymptotically free renormalization group trajectories for the generic non-Abelian Higgs model in four-dimensional spacetime. These ultraviolet-complete trajectories become visible by generalizing the renormalization/boundary conditions in the definition of the correlation functions of the theory. Though they are accessible in a controlled weak-coupling analysis, these trajectories originate from threshold phenomena which are missed in a conventional perturbative analysis relying on the deep Euclidean region. We identify a candidate three-parameter family of renormalization group trajectories interconnecting the asymptotically free ultraviolet regime with a Higgs phase in the low-energy limit. We provide estimates of their low-energy properties in the light of a possible application to the standard model Higgs sector. Finally, we find a two-parameter subclass of asymptotically free Coleman-Weinberg-type trajectories that do not suffer from a naturalness problem.
Fracture Strength of Disordered Media: Universality, Interactions, and Tail Asymptotics
NASA Astrophysics Data System (ADS)
Manzato, Claudio; Shekhawat, Ashivni; Nukala, Phani K. V. V.; Alava, Mikko J.; Sethna, James P.; Zapperi, Stefano
2012-02-01
We study the asymptotic properties of fracture strength distributions of disordered elastic media by a combination of renormalization group, extreme value theory, and numerical simulation. We investigate the validity of the “weakest-link hypothesis” in the presence of realistic long-ranged interactions in the random fuse model. Numerical simulations indicate that the fracture strength is well-described by the Duxbury-Leath-Beale (DLB) distribution which is shown to flow asymptotically to the Gumbel distribution. We explore the relation between the extreme value distributions and the DLB-type asymptotic distributions and show that the universal extreme value forms may not be appropriate to describe the nonuniversal low-strength tail.
Stable parabolic Higgs bundles as asymptotically stable decorated swamps
NASA Astrophysics Data System (ADS)
Beck, Nikolai
2016-06-01
Parabolic Higgs bundles can be described in terms of decorated swamps, which we studied in a recent paper. This description induces a notion of stability of parabolic Higgs bundles depending on a parameter, and we construct their moduli space inside the moduli space of decorated swamps. We then introduce asymptotic stability of decorated swamps in order to study the behaviour of the stability condition as one parameter approaches infinity. The main result is the existence of a constant, such that stability with respect to parameters greater than this constant is equivalent to asymptotic stability. This implies boundedness of all decorated swamps which are semistable with respect to some parameter. Finally, we recover the usual stability condition of parabolic Higgs bundles as asymptotic stability.
Identifying Occupationally Specific Affective Behaviors.
ERIC Educational Resources Information Center
Pucel, David J.
1993-01-01
Data from two groups of cosmetology instructors (n=15) and two groups of machinist instructors (n=17) validated the Occupational Affective Behavior Analysis instrument as capable of identifying affective behaviors viewed as important to success in a given occupation. (SK)
Hospitality Occupations. Curriculum Guide.
ERIC Educational Resources Information Center
California State Dept. of Education, Sacramento. Bureau of Homemaking Education.
This curriculum guide on the hospitality occupations was developed to help secondary and postsecondary home economics teachers prepare individuals for entry-level jobs in the hospitality industry. The content is in seven sections. The first section presents organizational charts of a medium-size hotel, food and beverage division, housekeeping and…
Pharmacist. Occupational Simulation Kit.
ERIC Educational Resources Information Center
Parsley, Nancy
This career exploration instructional booklet on the pharmacist's occupation is one of several resulting from the rural southwestern Colorado CEPAC Project (Career Education Process of Attitude Change). Based on a job analysis and utilizing a programed instructional format, the following content is included: A brief description of two real…
Evaluating Occupational Programs.
ERIC Educational Resources Information Center
Long, James P.
1987-01-01
Stresses the importance of evaluating occupational programs on a regular basis. Offers a brief explanation of the approaches to program evaluation taken at the Dallas County Community College District (TX), South Puget Sound Community College (WA), and Triton College (IL). Offers a list of references on program evaluation. (CBC)
ERIC Educational Resources Information Center
Walraven, Catherine; And Others
These instructional materials consist of a series of curriculum worksheets that cover tasks to be mastered by students in health occupations cluster programs. Covered in the curriculum worksheets are diagnostic procedures; observing/recording/reporting/planning; safety; nutrition/elimination; hygiene/personal care/comfort;…
Cluster Guide. Accounting Occupations.
ERIC Educational Resources Information Center
Beaverton School District 48, OR.
Based on a recent task inventory of key occupations in the accounting cluster taken in the Portland, Oregon, area, this curriculum guide is intended to assist administrators and teachers in the design and implementation of high school accounting cluster programs. The guide is divided into four major sections: program organization and…
Occupational Diseases in Korea
Kim, Eun A
2010-01-01
Korea has industrialized since the 1970s. Pneumoconiosis in coal miners was the most common occupational disease in the 1970s to 1980s. With the industrialization, the use of many chemicals have increased since the 1970s. As a consequence, there were outbreaks of occupational diseases caused by poisonous chemicals, such as heavy metal poisoning, solvent poisoning and occupational asthma in the late 1980s and early 1990s with civil movement for democracy. Many actions have been taken for prevention by the government, employers and employees or unions. In the 1990s most chemical related diseases and pneumoconiosis have rapidly decreased due to improving work environment. In the late 1990s, cerebro-cardiovascular diseases related to job stress or work overloads have abruptly increased especially after the economic crisis in 1998. After the year 2000, musculoskeletal disorders became a major problem especially in assembly lines in the manufacturing industry and they were expanded to the service industry. Mental diseases related to job stress have increased. Infectious diseases increased in health care workers and afforestation workers. Occupational cancers are increasing because of their long latency, although the use of carcinogenic substances are reduced, limited, and even banned. PMID:21258589
Marketing Occupations. Cluster Guide.
ERIC Educational Resources Information Center
Oregon State Dept. of Education, Salem.
This cluster guide, which is designed to show teachers what specific knowledge and skills qualify high school students for entry-level employment (or postsecondary training) in marketing occupations, is organized into three sections: (1) cluster organization and implementation, (2) instructional emphasis areas, and (3) assessment. The first…
Occupational Burnout among Librarians.
ERIC Educational Resources Information Center
Haack, Mary; And Others
1984-01-01
Outlines stages of occupational burnout (enthusiasm, stagnation, frustration, apathy) and begins empirical assessment of burnout syndrome among librarians and other information professionals. Results of pilot survey conducted at one-day conference on reference service using two measures (Staff Burnout Scale for Health Professionals, projective…
ERIC Educational Resources Information Center
Noto, Jody
This curriculum guide consists of materials for use in presenting the second year of a two-year course in diversified occupations that is designed to teach job search and job-holding skills to disadvantaged and English as a second language (ESL) students. Addressed in the 24 units included in the course are the following topics: the purposes of…
Occupational Medical Surveillance Recommendations
1991-07-01
friendly, industrial chemical database which is updated jonstantly and. republished every three months. TOMES Plus contains MEDITEXT m , HAZARDTEXT DOT ...worker with an allergic sensitivity to the hazard (animal dander, isocyanate ). For these workers respirators frequently do not reduce exposure enough...Toxicology, Occupational Medicine and Environmental Series) Information System. TOMES Plus contains MEDITEXT , HAZARDTEXT , DOT Emergency Response
Occupational Clothing Curriculum.
ERIC Educational Resources Information Center
Fraser, Annette J.
Designed to provide individualized, hands-on experience for secondary or postsecondary students in gainful homemaking programs, this occupational clothing curriculum contains eight learning modules. The following topics are covered in the modules: plant production for the needle trades (needle trade structure and operation, terminology, history,…
Occupation and lymphoid neoplasms.
La Vecchia, C.; Negri, E.; D'Avanzo, B.; Franceschi, S.
1989-01-01
The relationship between occupation and exposure to a number of occupational agents and lymphoid neoplasms was investigated in a case-control study of 69 cases of Hodgkin's disease, 153 non-Hodgkin's lymphomas, 110 multiple myelomas and 396 controls admitted for acute diseases to a network of teaching and general hospitals in the greater Milan area. Among the cases, there was a significant excess of individuals ever occupied in agriculture and food processing: the multivariate relative risks (RR) were 2.1 (95% confidence interval, CI = 1.0-3.8) for Hodgkin's disease, 1.9 (95% CI = 1.2-3.0) for non-Hodgkin's lymphomas and 2.0 (95% CI = 1.1-3.5) for multiple myeloma. Significant trends for duration of exposure to herbicides were observed for lymphomas, but the association was stronger for overall occupation in agriculture than with the specific question of herbicide use. History of occupation in the chemical industry was more frequent among Hodgkin's disease (RR = 4.3, 95% CI = 1.4-10.2), and a significant trend in risk was observed between duration of exposure to benzene and other solvents and multiple myeloma. No significant relation was found between any of the lymphoid neoplasms considered and rubber, dye, painting, printing, tanning leather, photography, pharmaceuticals, wood, coal/gas and nuclear industries. PMID:2789947
Carozza, S E; Wrensch, M; Miike, R; Newman, B; Olshan, A F; Savitz, D A; Yost, M; Lee, M
2000-11-01
Lifetime job histories from a population-based, case-control study of gliomas diagnosed among adults in the San Francisco Bay area between August 1991 and April 1994 were evaluated to assess occupational risk factors. Occupational data for 476 cases and 462 controls were analyzed, with adjustment for age, gender, education, and race. Imprecise increased risks were observed for physicians and surgeons (odds ratio (OR) = 3.5, 95% confidence interval (CI): 0.7, 17.6), artists (OR = 1.9, 95% CI: 0.5, 6.5), foundry and smelter workers (OR = 2.6, 95% CI: 0.5, 13.1), petroleum and gas workers (OR = 4.9, 95% CI: 0.6, 42.2), and painters (OR = 1.6, 95% CI: 0.5, 4.9). Legal and social service workers, shippers, janitors, motor vehicle operators, and aircraft operators had increased odds ratios only with longer duration of employment. Physicians and surgeons, foundry and smelter workers, petroleum and gas workers, and painters showed increased risk for both astrocytic and nonastrocytic tumors. Artists and firemen had increased risk for astrocytic tumors only, while messengers, textile workers, aircraft operators, and vehicle manufacturing workers showed increased risk only for nonastrocytic tumors. Despite study limitations, including small numbers for many of the occupational groups, a high percentage of proxy respondents among cases, and lack of specific exposure information, associations were observed for several occupations previously reported to be at higher risk for brain tumors generally and gliomas specifically.
Occupational cancer in Britain
Van Tongeren, Martie; Jimenez, Araceli S; Hutchings, Sally J; MacCalman, Laura; Rushton, Lesley; Cherrie, John W
2012-01-01
To estimate the current occupational cancer burden due to past exposures in Britain, estimates of the number of exposed workers at different levels are required, as well as risk estimates of cancer due to the exposures. This paper describes the methods and results for estimating the historical exposures. All occupational carcinogens or exposure circumstances classified by the International Agency for Research on Cancer as definite or probable human carcinogens and potentially to be found in British workplaces over the past 20–40 years were included in this study. Estimates of the number of people exposed by industrial sector were based predominantly on two sources of data, the CARcinogen EXposure (CAREX) database and the UK Labour Force Survey. Where possible, multiple and overlapping exposures were taken into account. Dose–response risk estimates were generally not available in the epidemiological literature for the cancer–exposure pairs in this study, and none of the sources available for obtaining the numbers exposed provided data by different levels of exposure. Industrial sectors were therefore assigned using expert judgement to ‘higher'- and ‘lower'-exposure groups based on the similarity of exposure to the population in the key epidemiological studies from which risk estimates had been selected. Estimates of historical exposure prevalence were obtained for 41 carcinogens or occupational circumstances. These include exposures to chemicals and metals, combustion products, other mixtures or groups of chemicals, mineral and biological dusts, physical agents and work patterns, as well as occupations and industries that have been associated with increased risk of cancer, but for which the causative agents are unknown. There were more than half a million workers exposed to each of six carcinogens (radon, solar radiation, crystalline silica, mineral oils, non-arsenical insecticides and 2,3,7,8-tetrachlorodibenzo-p-dioxin); other agents to which a large
Data security in occupational health.
Damrongsak, Mantana; Brown, Kathleen C
2008-10-01
Occupational health nurses are increasingly using computer systems in the delivery of efficient, high-quality occupational health services. However, potential breaches in data security are posing more risks to these data systems. The purpose of this article is to address concerns related to data security in occupational health nursing. Occupational health nurses must protect the personal health information of employees by proactively developing methods to ensure data security.
Defining Occupational Illnesses and Injuries
1990-11-01
This technical report will discuss the definitions of occupational illnesses and injuries as established by the Occupational Safety and Health...Administration (OSHA). A systematic method for classifying an occupational event as either an illness or an injury will be presented. The Air Force is...required to collect occupational injury and illness data, to analyze collected data, and to establish preventive programs based upon any identified unsafe
Military Occupational Health Surveillance Program
1979-06-01
Responses were received from 37 HSC medical treatment facilities (100%) regarding their occupational health surveillance programs. The occupational ...personnel determined to be potentially exposed to occupational or job- related hazards, medical surveillance programs are limited, if available at all. An...exposed to occupational or job-related hazards would require more adequate staffing to provide the services. Identification of personnel at risk could be
Occupational protein contact dermatitis.
Barbaud, Annick; Poreaux, Claire; Penven, Emmanuelle; Waton, Julie
2015-01-01
Occupational contact dermatitis is generally caused by haptens but can also be induced by proteins causing mainly immunological contact urticaria (ICU); chronic hand eczema in the context of protein contact dermatitis (PCD). In a monocentric retrospective study, from our database, only 31 (0.41%) of patients with contact dermatitis had positive skin tests with proteins: 22 had occupational PCD, 3 had non-occupational PCD, 5 occupational ICU and 1 cook had a neutrophilic fixed food eruption (NFFE) due to fish. From these results and analysis of literature, the characteristics of PCD can be summarized as follows. It is a chronic eczematous dermatitis, possibly exacerbated by work, suggestive if associated with inflammatory perionyxix and immediate erythema with pruritis, to be investigated when the patient resumes work after a period of interruption. Prick tests with the suspected protein-containing material are essential, as patch tests have negative results. In case of multisensitisation revealed by prick tests, it is advisable to analyse IgE against recombinant allergens. A history of atopy, found in 56 to 68% of the patients, has to be checked for. Most of the cases are observed among food-handlers but PCD can also be due to non-edible plants, latex, hydrolysed proteins or animal proteins. Occupational exposure to proteins can thus lead to the development of ICU. Reflecting hypersensitivity to very low concentrations of allergens, investigating ICU therefore requires caution and prick tests should be performed with a diluted form of the causative protein-containing product. Causes are food, especially fruit peel, non-edible plants, cosmetic products, latex, animals.
Asymptotic Robustness Study of the Polychoric Correlation Estimation.
Jin, Shaobo; Yang-Wallentin, Fan
2017-03-01
Asymptotic robustness against misspecification of the underlying distribution for the polychoric correlation estimation is studied. The asymptotic normality of the pseudo-maximum likelihood estimator is derived using the two-step estimation procedure. The t distribution assumption and the skew-normal distribution assumption are used as alternatives to the normal distribution assumption in a numerical study. The numerical results show that the underlying normal distribution can be substantially biased, even though skewness and kurtosis are not large. The skew-normal assumption generally produces a lower bias than the normal assumption. Thus, it is worth using a non-normal distributional assumption if the normal assumption is dubious.
Asymptotic teleportation scheme as a universal programmable quantum processor.
Ishizaka, Satoshi; Hiroshima, Tohya
2008-12-12
We consider a scheme of quantum teleportation where a receiver has multiple (N) output ports and obtains the teleported state by merely selecting one of the N ports according to the outcome of the sender's measurement. We demonstrate that such teleportation is possible by showing an explicit protocol where N pairs of maximally entangled qubits are employed. The optimal measurement performed by a sender is the square-root measurement, and a perfect teleportation fidelity is asymptotically achieved for a large N limit. Such asymptotic teleportation can be utilized as a universal programmable processor.
Asymptotic entanglement transformation between W and GHZ states
Vrana, Péter; Christandl, Matthias
2015-02-15
We investigate entanglement transformations with stochastic local operations and classical communication in an asymptotic setting using the concepts of degeneration and border rank of tensors from algebraic complexity theory. Results well-known in that field imply that GHZ states can be transformed into W states at rate 1 for any number of parties. As a generalization, we find that the asymptotic conversion rate from GHZ states to Dicke states is bounded as the number of subsystems increases and the number of excitations is fixed. By generalizing constructions of Coppersmith and Winograd and by using monotones introduced by Strassen, we also compute the conversion rate from W to GHZ states.
Asymptotic traveling wave solution for a credit rating migration problem
NASA Astrophysics Data System (ADS)
Liang, Jin; Wu, Yuan; Hu, Bei
2016-07-01
In this paper, an asymptotic traveling wave solution of a free boundary model for pricing a corporate bond with credit rating migration risk is studied. This is the first study to associate the asymptotic traveling wave solution to the credit rating migration problem. The pricing problem with credit rating migration risk is modeled by a free boundary problem. The existence, uniqueness and regularity of the solution are obtained. Under some condition, we proved that the solution of our credit rating problem is convergent to a traveling wave solution, which has an explicit form. Furthermore, numerical examples are presented.
On the asymptotic distribution of block-modified random matrices
Arizmendi, Octavio; Nechita, Ion; Vargas, Carlos
2016-01-15
We study random matrices acting on tensor product spaces which have been transformed by a linear block operation. Using operator-valued free probability theory, under some mild assumptions on the linear map acting on the blocks, we compute the asymptotic eigenvalue distribution of the modified matrices in terms of the initial asymptotic distribution. Moreover, using recent results on operator-valued subordination, we present an algorithm that computes, numerically but in full generality, the limiting eigenvalue distribution of the modified matrices. Our analytical results cover many cases of interest in quantum information theory: we unify some known results and we obtain new distributions and various generalizations.
Uniform Asymptotics of Orthogonal Polynomials Arising from Coherent States
NASA Astrophysics Data System (ADS)
Dai, Dan; Hu, Weiying; Wang, Xiang-Sheng
2015-08-01
In this paper, we study a family of orthogonal polynomials {φ_n(z)} arising from nonlinear coherent states in quantum optics. Based on the three-term recurrence relation only, we obtain a uniform asymptotic expansion of φ_n(z) as the polynomial degree n tends to infinity. Our asymptotic results suggest that the weight function associated with the polynomials has an unusual singularity, which has never appeared for orthogonal polynomials in the Askey scheme. Our main technique is the Wang and Wong's difference equation method. In addition, the limiting zero distribution of the polynomials φ_n(z) is provided.
Asymptotic treatment of the Elenbaas-Heller equation
NASA Astrophysics Data System (ADS)
Kuiken, H. K.
1991-04-01
When the maximum temperatures within a high-pressure gas discharge arc are lower than the ionization temperature of the gas molecules by an order of magnitude, an asymptotic treatment of the temperature equation is possible. This is illustrated by means of the Elenbaas-Heller equation [e.g., M. F. Hoyaux, Arc Physics (Springer, Berlin, 1968), p. 36] for a nonradiating wall-stabilized arc. The asymptotics lead to a closed-form expression for the relationship between the arc current and the axis temperature. An expression for the heat loss per unit length is also given.
Asymptotic/numerical analysis of supersonic propeller noise
NASA Technical Reports Server (NTRS)
Myers, M. K.; Wydeven, R.
1989-01-01
An asymptotic analysis based on the Mach surface structure of the field of a supersonic helical source distribution is applied to predict thickness and loading noise radiated by high speed propeller blades. The theory utilizes an integral representation of the Ffowcs-Williams Hawkings equation in a fully linearized form. The asymptotic results are used for chordwise strips of the blade, while required spanwise integrations are performed numerically. The form of the analysis enables predicted waveforms to be interpreted in terms of Mach surface propagation. A computer code developed to implement the theory is described and found to yield results in close agreement with more exact computations.
Asymptotic falloff of local waveform measurements in numerical relativity
Pollney, Denis; Reisswig, Christian; Dorband, Nils; Schnetter, Erik; Diener, Peter
2009-12-15
We examine current numerical relativity computations of gravitational waves, which typically determine the asymptotic waves at infinity by extrapolation from finite (small) radii. Using simulations of a black hole binary with accurate wave extraction at r=1000M, we show that extrapolations from the near zone are self-consistent in approximating measurements at this radius, although with a somewhat reduced accuracy. We verify that {psi}{sub 4} is the dominant asymptotic contribution to the gravitational energy (as required by the peeling theorem) but point out that gauge effects may complicate the interpretation of the other Weyl components.
Current results on the asymptotics of dynamo models
NASA Astrophysics Data System (ADS)
Popova, H. P.
2016-06-01
Magnetic field generation and evolution models that are capable of describing a large body of observational material are currently available for different celestial bodies. Despite recent decades of great success in numerical magnetic hydrodynamics and in detailed research into some specific problems, asymptotic methods still have to be used to clarify the magnetic field generation mechanism in dynamo theory. In this review, current asymptotic methods are presented together with the results of their application to the simulation of solar, stellar, and galactic magnetic activities.
Asymptotic approach to special relativity compatible with a relativistic principle
Carmona, J. M.; Cortes, J. L.; Mazon, D.
2010-10-15
We propose a general framework to describe Planckian deviations from special relativity compatible with a relativistic principle. They are introduced as the leading corrections in an asymptotic approach to special relativity going beyond the energy power expansion of effective field theories. We discuss the conditions in which these Planckian effects might be experimentally observable in the near future, together with the nontrivial limits of applicability of this asymptotic approach that such a situation would produce, both at the very high (ultraviolet) and the very low (infrared) energy regimes.
Counting spanning trees on fractal graphs and their asymptotic complexity
NASA Astrophysics Data System (ADS)
Anema, Jason A.; Tsougkas, Konstantinos
2016-09-01
Using the method of spectral decimation and a modified version of Kirchhoff's matrix-tree theorem, a closed form solution to the number of spanning trees on approximating graphs to a fully symmetric self-similar structure on a finitely ramified fractal is given in theorem 3.4. We show how spectral decimation implies the existence of the asymptotic complexity constant and obtain some bounds for it. Examples calculated include the Sierpiński gasket, a non-post critically finite analog of the Sierpiński gasket, the Diamond fractal, and the hexagasket. For each example, the asymptotic complexity constant is found.
Vacuum energy in asymptotically flat 2 + 1 gravity
NASA Astrophysics Data System (ADS)
Miskovic, Olivera; Olea, Rodrigo; Roy, Debraj
2017-04-01
We compute the vacuum energy of three-dimensional asymptotically flat space based on a Chern-Simons formulation for the Poincaré group. The equivalent action is nothing but the Einstein-Hilbert term in the bulk plus half of the Gibbons-Hawking term at the boundary. The derivation is based on the evaluation of the Noether charges in the vacuum. We obtain that the vacuum energy of this space has the same value as the one of the asymptotically flat limit of three-dimensional anti-de Sitter space.
On the Asymptotics of Bessel Functions in the Fresnel Regime
2014-07-10
between the solutions u, v of (1) and the corresponding phase function is given by the formula α′(z) = W u2(z) + v2(z) , (8) with W the (constant...We introduce a version of the asymptotic expansions for Bessel functions Jν(z), Yν(z) that is valid whenever |z| > ν (which is deep in the Fresnel... function , and uses classical formulas to obtain an asymptotic expansion for this function ; this in turn leads to both an analytical tool and a nu
Masonry. Occupational Competency Analysis Profile.
ERIC Educational Resources Information Center
Ohio State Univ., Columbus. Vocational Instructional Materials Lab.
This Occupational Competency Analysis Profile (OCAP) for masonry occupations contains a competency list verified by expert workers and developed through a modified DACUM (Developing a Curriculum) involving business, industry, labor, and community agency representatives from Ohio. This OCAP identifies the occupational, academic, and employability…
Clarifying the Construct of Occupational Engagement for Occupational Therapy Practice.
Kennedy, Jennifer; Davis, Jane A
2017-04-01
Occupational engagement (OE) has been presented as a core construct in occupational therapy; however, its broad conceptualization and confounding definitions are problematic. Clarifying the construct of OE would help occupational therapists to explicate the nature of their practice. The purpose of this study was to explore occupational therapists' perspectives of the construct of OE. Qualitative descriptive methodology was used to collect data using semistructured interviews with nine practicing occupational therapists in the Greater Toronto Area. Qualitative content analysis, using an inductive approach, was employed to uncover emerging categories. Participants spoke about transitioning from therapeutic engagement to OE with a client by following a client's path of choice. The essential elements and influencers of OE were highlighted, and the relationship between OE and occupational performance was discussed. The findings provide an initial understanding of essential elements necessary to enable clients to initiate engagement in therapy and then, subsequently, in occupations of their choice.
Occupational Conversion Index; Enlisted/Officer/Civilian.
1997-03-01
This index is a compilation of DoD officer and enlisted occupational specialties and Civil Service ’white collar’ and ’blue collar’ occupations under...two similar occupational grouping structures. The first structure contains enlisted occupations, certain occupations in the General Schedule (GS...and a few wage board occupations. This index is intended to serve as an occupational coding structure, designed to group similar occupations from one
NASA Astrophysics Data System (ADS)
Ziesche, P.
2005-08-01
In part I [phys. stat. sol. (b) 241, 3544 (2004)] it has been shown, for the homogeneous electron gas, how the momentum distribution n(k) determines the geminal occupancy (k), which appears in the Kimball-Overhauser partial-wave analysis of the pair density g(r). The Fermi surface singularities of n(k) cause singularities in (k). These singularities determine the large-r asymptotics of the 1-matrix and of the pair density, respectively. Because the pair-density geminals are scattering states, their asymptotic behavior is characterized by phase shifts. Whereas the normalization sum rule of g(r) leads to a Friedel-like phase-shift sum rule [Phys. Rev. B 67, 233102 (2003)], the plasmon sum rule cannot be satisfied by Kimball-Overhauser geminals. Possibilities to cure this failure are discussed.
Asymptotic Learning of Alphanumeric Coding in Autobiographical Memory
ERIC Educational Resources Information Center
Martin, Maryanne; Jones, Gregory V.
2007-01-01
Studies of autobiographical memory have shown that observed levels of incidental learning are often relatively low. Do low levels of retention result simply from a low learning rate, or is learning also asymptotic? To address this question, it is necessary to trace performance over a large number of learning opportunities, and this was carried out…
Asymptotic Spectra Of Banded Quasi-Toeplitz Matrices
NASA Technical Reports Server (NTRS)
Beam, Richard; Warming, Robert
1995-01-01
Paper presents theoretical and numerical study of asymptotic spectra of eigenvalues of banded Toeplitz and quasi-Toeplitz matrices. Emphasis in study on non-normal banded Toeplitz and quasi-Toeplitz matrices of arbitrarily large order and relatively small bandwidth.
The Asymptotic Distribution of the Renyi Maximal Correlation
1990-10-01
functions of U and W with finite second moments. In this paper we derive the asymptotic distribution of the estimate of the Renyi correlation ... coefficient based on a sample of independent observations under the assumption that (U,W) are independent and assume only a finite number of values. (kr)
Asymptotic Analysis of Fiber-Reinforced Composites of Hexagonal Structure
NASA Astrophysics Data System (ADS)
Kalamkarov, Alexander L.; Andrianov, Igor V.; Pacheco, Pedro M. C. L.; Savi, Marcelo A.; Starushenko, Galina A.
2016-08-01
The fiber-reinforced composite materials with periodic cylindrical inclusions of a circular cross-section arranged in a hexagonal array are analyzed. The governing analytical relations of the thermal conductivity problem for such composites are obtained using the asymptotic homogenization method. The lubrication theory is applied for the asymptotic solution of the unit cell problems in the cases of inclusions of large and close to limit diameters, and for inclusions with high conductivity. The lubrication method is further generalized to the cases of finite values of the physical properties of inclusions, as well as for the cases of medium-sized inclusions. The analytical formulas for the effective coefficient of thermal conductivity of the fiber-reinforced composite materials of a hexagonal structure are derived in the cases of small conductivity of inclusions, as well as in the cases of extremely low conductivity of inclusions. The three-phase composite model (TPhM) is applied for solving the unit cell problems in the cases of the inclusions with small diameters, and the asymptotic analysis of the obtained solutions is performed for inclusions of small sizes. The obtained results are analyzed and illustrated graphically, and the limits of their applicability are evaluated. They are compared with the known numerical and asymptotic data in some particular cases, and very good agreement is demonstrated.
Asymptotics of surface-plasmon redshift saturation at subnanometric separations
NASA Astrophysics Data System (ADS)
Schnitzer, Ory; Giannini, Vincenzo; Craster, Richard V.; Maier, Stefan A.
2016-01-01
Many promising nanophotonics endeavors hinge upon the unique plasmonic properties of nanometallic structures with narrow nonmetallic gaps, which support superconcentrated bonding modes that singularly redshift with decreasing separations. In this Rapid Communication, we present a descriptive physical picture, complemented by elementary asymptotic formulas, of a nonlocal mechanism for plasmon redshift saturation at subnanometric gap widths. Thus, by considering the electron-charge and field distributions in the close vicinity of the metal-vacuum interface, we show that nonlocality is asymptotically manifested as an effective potential discontinuity. For bonding modes in the near-contact limit, the latter discontinuity is shown to be effectively equivalent to a widening of the gap. As a consequence, the resonance-frequency near-contact asymptotics are a renormalization of the corresponding local ones. Specifically, the renormalization furnishes an asymptotic plasmon-frequency lower bound that scales with the 1 /4 power of the Fermi wavelength. We demonstrate these remarkable features in the prototypical cases of nanowire and nanosphere dimers, showing agreement between our elementary expressions and previously reported numerical computations.
Cosmological attractors and asymptotic freedom of the inflaton field
Kallosh, Renata; Linde, Andrei
2016-06-28
We show that the inflaton coupling to all other fields is exponentially suppressed during inflation in the cosmological α-attractor models. In the context of supergravity, this feature is a consequence of the underlying hyperbolic geometry of the moduli space which has a flat direction corresponding to the inflaton field. A combination of these factors protects the asymptotic flatness of the inflaton potential.
Asymptotic behaviour of the stochastic Gilpin-Ayala competition models
NASA Astrophysics Data System (ADS)
Lian, Baosheng; Hu, Shigeng
2008-03-01
In this paper, we investigate a stochastic Gilpin-Ayala competition system, which is more general and more realistic than the classical Lotka-Volterra competition system.We discuss the asymptotic behaviour in detail of the stochastic Gilpin-Ayala competition system, and comparing the classical Lotka-Volterra with Gilpin-Ayala competition system, we find that the latter has better properties.
Asymptotically optimal feedback control for a system of linear oscillators
NASA Astrophysics Data System (ADS)
Ovseevich, Alexander; Fedorov, Aleksey
2013-12-01
We consider problem of damping of an arbitrary number of linear oscillators under common bounded control. We are looking for a feedback control steering the system to the equilibrium. The obtained control is asymptotically optimal: the ratio of motion time to zero with this control to the minimum one is close to 1, if the initial energy of the system is large.
Raj, A; Mayberry, J; Podas, T
2003-01-01
Gastric cancer is a cause of significant morbidity and mortality. There are several risk factors, with occupation emerging as one of these. There is considerable evidence that occupations in coal and tin mining, metal processing, particularly steel and iron, and rubber manufacturing industries lead to an increased risk of gastric cancer. Other "dusty" occupations—for example, wood processing, or work in high temperature environments have also been implicated but the evidence is not strong. The mechanism of pathogenesis of gastric cancer is unclear and the identification of causative agents can be difficult. Dust is thought to be a contributor to the pathological process, but well known carcinogens such as N-nitroso compounds have been detected in some environments. Further research on responsible agents is necessary and screening for detection of precursor gastric cancer lesions at the workplace merits consideration. PMID:12782770
Occupational Contact Dermatitis
2008-01-01
Occupational contact dermatitis accounts for 90% of all cases of work-related cutaneous disorders. It can be divided into irritant contact dermatitis, which occurs in 80% of cases, and allergic contact dermatitis. In most cases, both types will present as eczematous lesions on exposed parts of the body, notably the hands. Accurate diagnosis relies on meticulous history taking, thorough physical examination, careful reading of Material Safety Data Sheets to distinguish between irritants and allergens, and comprehensive patch testing to confirm or rule out allergic sensitization. This article reviews the pathogenesis and clinical manifestations of occupational contact dermatitis and provides diagnostic guidelines and a rational approach to management of these often frustrating cases. PMID:20525126
Occupational musculoskeletal disorders.
Peate, W F
1994-06-01
Musculoskeletal disorders of the workplace include the acute, cumulative and chronic injuries or illnesses of the soft tissues which are caused by mechanical stress, strain, sprain, vibration, inflammation, or irritation. The successful management of occupational musculoskeletal disorders must account for workplace conditions (ergonomics and work practices), psychosocial factors, diagnostic uncertainties, and the need for active modalities (exercises and a progressive increase in activities of daily living), rather than passive (bed rest and traction). Although most occupational musculoskeletal disorders respond to conservative measures such as ice or heat, protective devices such as, neutral splints for carpal tunnel syndrome, nonsteroidal anti-inflammatory drugs, and progressive strengthening, resolution may take months. Prevention is often more important than treatment, and may entail workplace revisions and special worker training. Worker selection programs--strength testing, pre-placement radiographs, and inquiries about prior low back pain--have poor predictive value.
Gomez, M R
1981-01-01
Health and safety regulation, training, and research were practically non-existent in Cuba before the Revolution in 1959. Since that time important advances have been made. Specialized inspectors, occupational physicians, and other such personnel are now trained in Cuba. An Occupational Health Institute, founded in 1976, provides training and specialized technical services, and conducts research. In 1978, a far reaching "Work Safety and Health Law" was enacted which defines the rights and responsibility of government agencies, workplace administrators, unions, and workers. Comprehensive control of toxic substances in workplaces, still at an early stage, is likely to increase in light of the new law, the growing availability of qualified personnel, and the mounting concern of public health authorities with the increasingly "developed" health profile of the population. PMID:7212141
Occupational cancer in Germany.
Brüske-Hohlfeld, I
1999-01-01
As in probably mostly all other European countries, the incidence of occupational cancer in Germany increased steadily after World War II. In 1994 about 1,600 cases of occupational cancer were compensated--more than ever before. More than half of these cases were lung cancer, most caused either by asbestos (n=545) or by ionizing radiation ((italic)n(/italic)=306). Other frequent target organs of asbestos were the pleura and the peritoneum with 495 cases of mesotheliomas. Asbestos was the single most important risk factor for occupational cancer, causing more than 1000 deaths per year. All other malignant diseases, such as bladder cancer, leukemia, angiosarcoma of the liver, adenocarcinoma of the nose or nasal sinuses, and skin cancer, were comparatively rare. Although primary exposure to ionizing radiation in uranium ore mining occurred in the 1950s and attributable lung cancers seem to be on the decline, this is not true for asbestos, where the peak incidence in lung cancer and mesothelioma has not been reached yet. Images Figure 2 PMID:10350508
NASA Astrophysics Data System (ADS)
Brown, David A.
1994-10-01
In the area of security and surveillance technologies, the problem of the arrival in Canada of illegal and undesirable ship and truck cargo loads is steadily increasing. As the volumes of cargo arrivals increase so do the Immigration and Customs problems related to the determination of the validity of those cargo contents. Of special concern to Immigration Control Authorities around the world is the emerging and increasing trend of illegal smuggling of human beings hidden inside of shipping containers. Beginning in 1992, Immigration Control Authorities in Canada observed an escalation of alien people smuggling through the use of cargo shipping containers arriving in the Port of Montreal. This paper will present to the audience the recently completed Immigration Canada Human Occupancy Detection project by explaining the design, development and testing of human occupancy detectors. The devices are designed to electronically detect the presence of persons hiding inside of shipping containers, without the requirement of opening the container doors. The human occupancy detection concepts are based upon the presence of carbon dioxide or other human waste characteristics commonly found inside of shipping containers.
Asymptotic analysis of laminated plates and shallow shells
NASA Astrophysics Data System (ADS)
Skoptsov, K. A.; Sheshenin, S. V.
2011-02-01
It was noted long ago [1] that the material strength theory develops both by improving computational methods and by widening the physical foundations. In the present paper, we develop a computational technique based on asymptotic methods, first of all, on the homogenization method [2, 3]. A modification of the homogenization method for plates periodic in the horizontal projection was proposed in [4], where the bending of a homogeneous plate with periodically repeating inhomogeneities on its surface was studied. A more detailed asymptotic analysis of elastic plates periodic in the horizontal projection can be found, e.g., in [5, 6]. In [6], three asymptotic approximations were considered, local problems on the periodicity cell were obtained for them, and the solvability of these problems was proved. In [7], it was shown that the techniques developed for plates periodic in the horizontal projection can also be used for laminated plates. In [7], this was illustrated by an example of asymptotic analysis of an isotropic plate symmetric with respect to the midplane. In what follows, these methods are generalized to the case of combined bending and extension of a longitudinal laminated plate up to the third approximation, which permits finding all components of the stress tensor. The study of the plate behavior is based on the method of homogenization of the three-dimensional problem of linear elasticity and does not use any hypotheses. It turns out that the Kirchhoff-Love hypothesis for the entire packet of layers is simply a consequence of the method in the zeroth approximation, and the bending stresses corresponding to the classical theory of laminated plates [8] are obtained in the first approximation. The successive approximations describe the behavior of the normal and the stress more precisely. In the present paper, the results obtained in [7] are refined, and the asymptotic solution is compared with the direct analysis of a laminated plate by the finite
Asymptotic conditions of motion for radiating charged particles
NASA Astrophysics Data System (ADS)
Anderson, James L.
1997-10-01
Approximate asymptotic conditions on the motion of compact, electrically charged particles are derived within the framework of general relativity using the Einstein-Infeld-Hoffmann (EIH) surface integral method. While superficially similar to the Abraham-Lorentz and Lorentz-Dirac equations, these conditions differ from them in several fundamental ways. They are not equations of motion in the usual sense but rather a set of conditions which these motions must obey asymptotically in the future of an initial starting time. And furthermore, they do not admit the runaway solutions of these other equations. As in the original EIH work, they are integrability conditions gotten from integrating the empty-space (i.e., sourceless) Einstein-Maxwell equations of general relativity over closed two-surfaces surrounding the sources of the fields appearing in these equations. No additional ad hoc assumptions, such as the form of a force law or the introduction of inertial reaction terms, are required for this purpose, nor is there a need for any infinite mass renormalizations such as are required in other derivations since all integrals are over surfaces and thus finite. In addition to being asymptotic, the conditions of motion derived here are also approximate and apply, as do the original EIH equations, only to slowly moving systems. A ``slowness'' parameter ɛ is identified as the ratio of the light travel time across the system divided by a characteristic time, e.g., a period. Use is made of both the method of matched asymptotic expansions and the method of multiple time scales to obtain an asymptotic expansion in ɛ and the expansion is carried to sufficiently high order ɛ7 to obtain the lowest-order radiation reaction terms. The resulting conditions of motion are shown to not allow runaway motions.
Asymptotic analysis of mathematical models for elastic composite media
NASA Astrophysics Data System (ADS)
Serkov, S. K.
The main subject of the thesis is the asymptotic analysis of models in mechanics of composite materials. It is based on the extension of the theory of the Polya-Szego tensors to the problems of homogenization and fracture. Such a technique allows one to obtain an asymptotic solution to a problem where most of numerical algorithms fail due to the presence of a singular perturbation. As a result of this work, a number of interesting effects have been found in optimization of composites and inverse problems of crack-inclusion interaction. Chapter 1 is an introductory chapter that contains the main definitions and bibliographical remarks. In Chapter 2 the Polya-Szego dipole tensors are employed for analysis of plane elasticity problems in non-homogeneous media. Classes of equivalence for defects (cavities and rigid inclusions) are specified for the Laplace and Navier operators: composite materials with defects of the same class have the same effective elastic moduli. Explicit asymptotic formulae for the effective compliance matrices of dilute composites are obtained. The problem of the optimal cavity shape is analyzed in Chapter 3. The analysis uses the Polya-Szego tensors calculated in Chapter 2. A new type of structure which is optimal for shear loading has been found. Properties of the optimal cavity are described. The crack-inclusion interaction problem considered in Chapter 4 has been solved by the asymptotic methods. An analysis of crack trajectories is performed in Chapter 5 for different types of defects and interface conditions. The algorithm employs the Polya-Szego tensors as integral characteristics describing the defect. Comparison with experimental data (Ceramic Centre, Bologna) is presented. In Chapter 6 we use the method of compound asymptotic expansions to treat the homogenization problem for thin-walled composites. The technique of boundary layer fields is employed to derive the junction condition in the region connecting thin walls. The asymptotic
Illis, W R; Swanson, G M; Satariano, E R; Schwartz, A G
1987-01-01
The utility of using latest occupational information as a summary of work history is assessed by comparing it to usual occupation and industry. We analyzed 5,734 complete occupational histories obtained by telephone interview as part of an ongoing occupational cancer surveillance study. Of these, 73.6 per cent reported the same usual occupation as latest occupation and 76.6 per cent the same usual industry as latest industry. Differences in match rates by race and sex, occupation and industry titles and categories suggest that bias may result in studies using latest occupation or industry as a summary measure of occupational exposures. PMID:3674253
Occupational arsine gas exposure.
Pullen-James, Shayla; Woods, Scott E.
2006-01-01
Arsine gas exposure is a rare occupational event and can be completely prevented with the use of appropriate protective gear. Exposure often occurs when arsine gas is generated while arsenic-containing crude ores or metals are treated with acid. Cases of toxicity require an index of suspicion and a good history. In particular, it should be in the differential diagnosis in patients who present acutely with red/bronze skin and hemoglobinuria. Treatment is supportive and may include transfusions and dialysis in severe cases. Clinical severity is proportionate to the level of exposure, and severity is directly related to the onset of symptoms. Images Figure 2 PMID:17225850
The occupational health audit.
Davis, R L
1976-02-01
The final report contains no magic or proprietary secrets. It is simply a logical review of what exists with an orderly recommendation of what should be done. To repeat -- many times the hardest part of any job is getting started. The purpose of this exercise is to provide a plan and a way to get started. This may seem like something so obvious that it is not needed. But a review of existing occupational health programs dispels that view. Five years after the enactment of the Occupational Safety and Health Act of 1970, hundreds of thousands of physical examinations are still being performed in a total vacuum; examinations whose contents bear little relationship to the hazards encountered. Countless laboratory determinations are being provided to personnel officers and plant managers who have absolutely no background in interpreting the meaning of those results. Millions of records are being meticulously kept with no goal in mind as to what purpose they should serve nor consideration for the privacy of individuals. In short, untold millions of dollars are being wasted while the things that should be done are left undone because, to quote, "the cost is too high." Often health professionals are employed by an organization because health crises have developed which force expert handling. The health professional enters chaos and is kept so busy answering fire-calls that there is no time for the orderly evaluation of needs and the development of operating routines required to prevent new crises from developing. Today's crises are being addressed while tomorrow's crises are developing out of routine situations. The health professional is not at fault; rather, executive management has failed to provide the necessary systems to meet its responsibilities. So long as this situation prevails, there is a need for someone to take the time to develop an orderly approach to occupational health surveillance. When such a condition exists, it is time to call in an independent auditor
The asymptotic convergence factor for a polygon under a perturbation
Li, X.
1994-12-31
Let Ax = b be a large system of linear equations, where A {element_of} C{sup NxN}, nonsingular and b {element_of} C{sup N}. A few iterative methods for solving have recently been presented in the case where A is nonsymmetric. Many of their algorithms consist of two phases: Phase I: estimate the extreme eigenvalues of A; Phase II: construct and apply an iterative method based on the estimates. For convenience, it is rewritten as an equivalent fixed-point form, x = Tx + c. Let {Omega} be a compact set excluding 1 in the complex plane, and let its complement in the extended complex plane be simply connected. The asymptotic convergence factor (ACF) for {Omega}, denoted by {kappa}({Omega}), measures the rate of convergence for the asymptotically optimal semiiterative methods for solving, where {sigma}(T) {contained_in} {Omega}.
Correspondence between Asymptotically Flat Spacetimes and Nonrelativistic Conformal Field Theories
Bagchi, Arjun
2010-10-22
We find a surprising connection between asymptotically flat spacetimes and nonrelativistic conformal systems in one lower dimension. The Bondi-Metzner-Sachs (BMS) group is the group of asymptotic isometries of flat Minkowski space at null infinity. This is known to be infinite dimensional in three and four dimensions. We show that the BMS algebra in 3 dimensions is the same as the 2D Galilean conformal algebra (GCA) which is of relevance to nonrelativistic conformal symmetries. We further justify our proposal by looking at a Penrose limit on a radially infalling null ray inspired by nonrelativistic scaling and obtain a flat metric. The BMS{sub 4} algebra is also discussed and found to be the same as another class of GCA, called semi-GCA, in three dimensions. We propose a general BMS-GCA correspondence. Some consequences are discussed.
Asymptotic inference in system identification for the atom maser.
Catana, Catalin; van Horssen, Merlijn; Guta, Madalin
2012-11-28
System identification is closely related to control theory and plays an increasing role in quantum engineering. In the quantum set-up, system identification is usually equated to process tomography, i.e. estimating a channel by probing it repeatedly with different input states. However, for quantum dynamical systems such as quantum Markov processes, it is more natural to consider the estimation based on continuous measurements of the output, with a given input that may be stationary. We address this problem using asymptotic statistics tools, for the specific example of estimating the Rabi frequency of an atom maser. We compute the Fisher information of different measurement processes as well as the quantum Fisher information of the atom maser, and establish the local asymptotic normality of these statistical models. The statistical notions can be expressed in terms of spectral properties of certain deformed Markov generators, and the connection to large deviations is briefly discussed.
On the asymptotic expansion of the Bergman kernel
NASA Astrophysics Data System (ADS)
Seto, Shoo
Let (L, h) → (M, o) be a polarized Kahler manifold. We define the Bergman kernel for H0(M, Lk), holomorphic sections of the high tensor powers of the line bundle L. In this thesis, we will study the asymptotic expansion of the Bergman kernel. We will consider the on-diagonal, near-diagonal and far off-diagonal, using L2 estimates to show the existence of the asymptotic expansion and computation of the coefficients for the on and near-diagonal case, and a heat kernel approach to show the exponential decay of the off-diagonal of the Bergman kernel for noncompact manifolds assuming only a lower bound on Ricci curvature and C2 regularity of the metric.
Asymptotically flat black holes in 2 +1 dimensions
NASA Astrophysics Data System (ADS)
Alkaç, Gökhan; Kilicarslan, Ercan; Tekin, Bayram
2016-04-01
Asymptotically flat black holes in 2 +1 dimensions are a rarity. We study the recently found black flower solutions (asymptotically flat black holes with deformed horizons), static black holes, rotating black holes and the dynamical black flowers (black holes with radiative gravitons) of the purely quadratic version of new massive gravity. We show how they appear in this theory and we also show that they are also solutions to the infinite order extended version of the new massive gravity, that is the Born-Infeld extension of new massive gravity with an amputated Einsteinian piece. The same metrics also solve the topologically extended versions of these theories, with modified conserved charges and the thermodynamical quantities, such as the Wald entropy. Besides these we find new conformally flat radiating type solutions to these extended gravity models. We also show that these metrics do not arise in Einstein's gravity coupled to physical perfect fluids.
Asymptotic state discrimination and a strict hierarchy in distinguishability norms
Chitambar, Eric; Hsieh, Min-Hsiu
2014-11-15
In this paper, we consider the problem of discriminating quantum states by local operations and classical communication (LOCC) when an arbitrarily small amount of error is permitted. This paradigm is known as asymptotic state discrimination, and we derive necessary conditions for when two multipartite states of any size can be discriminated perfectly by asymptotic LOCC. We use this new criterion to prove a gap in the LOCC and separable distinguishability norms. We then turn to the operational advantage of using two-way classical communication over one-way communication in LOCC processing. With a simple two-qubit product state ensemble, we demonstrate a strict majorization of the two-way LOCC norm over the one-way norm.
Asymptotically Lifshitz spacetimes with universal horizons in (1 +2 ) dimensions
NASA Astrophysics Data System (ADS)
Basu, Sayandeb; Bhattacharyya, Jishnu; Mattingly, David; Roberson, Matthew
2016-03-01
Hořava gravity theory possesses global Lifshitz space as a solution and has been conjectured to provide a natural framework for Lifshitz holography. We derive the conditions on the two-derivative Hořava gravity Lagrangian that are necessary for static, asymptotically Lifshitz spacetimes with flat transverse dimensions to contain a universal horizon, which plays a similar thermodynamic role as the Killing horizon in general relativity. Specializing to z =2 in 1 +2 dimensions, we then numerically construct such regular solutions over the whole spacetime. We calculate the mass for these solutions and show that, unlike the asymptotically anti-de Sitter case, the first law applied to the universal horizon is straightforwardly compatible with a thermodynamic interpretation.
Asymptotic densities of ballistic Lévy walks
NASA Astrophysics Data System (ADS)
Froemberg, D.; Schmiedeberg, M.; Barkai, E.; Zaburdaev, V.
2015-02-01
We propose an analytical method to determine the shape of density profiles in the asymptotic long-time limit for a broad class of coupled continuous-time random walks which operate in the ballistic regime. In particular, we show that different scenarios of performing a random-walk step, via making an instantaneous jump penalized by a proper waiting time or via moving with a constant speed, dramatically effect the corresponding propagators, despite the fact that the end points of the steps are identical. Furthermore, if the speed during each step of the random walk is itself a random variable, its distribution gets clearly reflected in the asymptotic density of random walkers. These features are in contrast with more standard nonballistic random walks.
The Massive Wave Equation in Asymptotically AdS Spacetimes
NASA Astrophysics Data System (ADS)
Warnick, C. M.
2013-07-01
We consider the massive wave equation on asymptotically AdS spaces. We show that the timelike F behaves like a finite timelike boundary, on which one may impose the equivalent of Dirichlet, Neumann or Robin conditions for a range of (negative) mass parameter which includes the conformally coupled case. We demonstrate well posedness for the associated initial-boundary value problems at the H 1 level of regularity. We also prove that higher regularity may be obtained, together with an asymptotic expansion for the field near F. The proofs rely on energy methods, tailored to the modified energy introduced by Breitenlohner and Freedman. We do not assume the spacetime is stationary, nor that the wave equation separates.
Asymptotic formulae for the zeros of orthogonal polynomials
NASA Astrophysics Data System (ADS)
Badkov, V. M.
2012-09-01
Let p_n(t) be an algebraic polynomial that is orthonormal with weight p(t) on the interval \\lbrack -1, 1 \\rbrack . When p(t) is a perturbation (in certain limits) of the Chebyshev weight of the first kind, the zeros of the polynomial p_n(\\cos\\tau) and the differences between pairs of (not necessarily consecutive) zeros are shown to satisfy asymptotic formulae as n\\to\\infty, which hold uniformly with respect to the indices of the zeros. Similar results are also obtained for perturbations of the Chebyshev weight of the second kind. First, some preliminary results on the asymptotic behaviour of the difference between two zeros of an orthogonal trigonometric polynomial, which are needed, are established. Bibliography: 15 titles.
Asymptotic Expansions, 1/Z Expansions, and the Critical Nuclear Charge
NASA Astrophysics Data System (ADS)
Drake, Gordon
2014-03-01
The quantum mechanical three-body problem defies analytic solution, and so computationally intensive approximation methods involving, for example, variational calculations with large correlated basis sets must be used. This talk will review recent work to explore the outer fringes of the quantum mechanical three-body problem for heliumlike atoms. Asymptotic expansions provide a surprisingly simple and accurate account of highly excited Rydberg states with high angular momentum. 1 / Z expansions, where Z is the nuclear charge, provide results for an entire isoelectronic sequence within a single calculation. Its radius of convergence is thought to be related to the critical nuclear charge Zc for a state to be bound. For Z
Asymptotic boundary conditions for dissipative waves: General theory
NASA Technical Reports Server (NTRS)
Hagstrom, Thomas
1990-01-01
An outstanding issue in the computational analysis of time dependent problems is the imposition of appropriate radiation boundary conditions at artificial boundaries. Accurate conditions are developed which are based on the asymptotic analysis of wave propagation over long ranges. Employing the method of steepest descents, dominant wave groups are identified and simple approximations to the dispersion relation are considered in order to derive local boundary operators. The existence of a small number of dominant wave groups may be expected for systems with dissipation. Estimates of the error as a function of domain size are derived under general hypotheses, leading to convergence results. Some practical aspects of the numerical construction of the asymptotic boundary operators are also discussed.
Asymptotic periodicity in networks of degrade-and-fire oscillators
NASA Astrophysics Data System (ADS)
Blumenthal, Alex; Fernandez, Bastien
2016-06-01
Networks of coupled degrade-and-fire (DF) oscillators are simple dynamical models of assemblies of interacting self-repressing genes. For mean-field interactions, which most mathematical studies have assumed so far, every trajectory must approach a periodic orbit. Moreover, asymptotic cluster distributions can be computed explicitly in terms of coupling intensity, and a massive collection of distributions collapses when this intensity passes a threshold. Here, we show that most of these dynamical features persist for an arbitrary coupling topology. In particular, we prove that, in any system of DF oscillators for which in and out coupling weights balance, trajectories with reasonable firing sequences must be asymptotically periodic, and periodic orbits are uniquely determined by their firing sequence. In addition to these structural results, illustrative examples are presented, for which the dynamics can be entirely described.
Asymptotic learning of alphanumeric coding in autobiographical memory.
Martin, Maryanne; Jones, Gregory V
2007-02-01
Studies of autobiographical memory have shown that observed levels of incidental learning are often relatively low. Do low levels of retention result simply from a low learning rate, or is learning also asymptotic? To address this question, it is necessary to trace performance over a large number of learning opportunities, and this was carried out in the context of the recent development of widespread texting behaviour. It was found that memory for the alphanumeric layout of a phone improved as a function of sending approximately the first 500 texts, but then the improvement stopped. The incidence of memory error was incompatible with a simple power-law relation but was modelled closely by an asymptotic relation. It is suggested that this pattern reflects a movement towards automaticity in the primary task which progressively closes down the possibility that incidental learning can occur.
Uniform asymptotic expansions of solutions of an inhomogeneous equation
NASA Astrophysics Data System (ADS)
Chen, Xinfu; Sadhu, Susmita
We treat a class of equations given by ɛ2u″(x)=u(x)(q(x,ɛ)-u(x)), u(-1)=α-, u(1)=α+, and obtain rigorous uniform asymptotic expansions of the solutions as ɛ→0. A key tool is a new formula of variation of constants that works for such quadratic equations. Included are solutions with one or more spikes. One example of this class of problems is a famous problem studied by Carrier and discussed formally by Bender and Orszag in the book "Advanced Mathematical Methods for Scientists and Engineers". In this paper we give the first rigorous derivation for the well-known asymptotics for that problem. Another more applied example is also covered by our theory.
Gravitational Two-Loop Counterterm Is Asymptotically Safe
NASA Astrophysics Data System (ADS)
Gies, Holger; Knorr, Benjamin; Lippoldt, Stefan; Saueressig, Frank
2016-05-01
Weinberg's asymptotic safety scenario provides an elegant mechanism to construct a quantum theory of gravity within the framework of quantum field theory based on a non-Gaussian fixed point of the renormalization group flow. In this work we report novel evidence for the validity of this scenario, using functional renormalization group techniques to determine the renormalization group flow of the Einstein-Hilbert action supplemented by the two-loop counterterm found by Goroff and Sagnotti. The resulting system of beta functions comprises three scale-dependent coupling constants and exhibits a non-Gaussian fixed point which constitutes the natural extension of the one found at the level of the Einstein-Hilbert action. The fixed point exhibits two ultraviolet attractive and one repulsive direction supporting a low-dimensional UV-critical hypersurface. Our result vanquishes the long-standing criticism that asymptotic safety will not survive once a "proper perturbative counterterm" is included in the projection space.
Geometric and asymptotic properties associated with linear switched systems
NASA Astrophysics Data System (ADS)
Chitour, Y.; Gaye, M.; Mason, P.
2015-12-01
Consider a continuous-time linear switched system on Rn associated with a compact convex set of matrices. When it is irreducible and its largest Lyapunov exponent is zero there always exists a Barabanov norm associated with the system. This paper deals with two types of issues: (a) properties of Barabanov norms such as uniqueness up to homogeneity and strict convexity; (b) asymptotic behavior of the extremal solutions of the linear switched system. Regarding Issue (a), we provide partial answers and propose four related open problems. As for Issue (b), we establish, when n = 3, a Poincaré-Bendixson theorem under a regularity assumption on the set of matrices. We then revisit a noteworthy result of N.E. Barabanov describing the asymptotic behavior of linear switched system on R3 associated with a pair of Hurwitz matrices { A , A + bcT }. After pointing out a gap in Barabanov's proof we partially recover his result by alternative arguments.
Hadronic Form Factors in Asymptotically Free Field Theories
DOE R&D Accomplishments Database
Gross, D. J.; Treiman, S. B.
1974-01-01
The breakdown of Bjorken scaling in asymptotically free gauge theories of the strong interactions is explored for its implications on the large q{sup 2} behavior of nucleon form factors. Duality arguments of Bloom and Gilman suggest a connection between the form factors and the threshold properties of the deep inelastic structure functions. The latter are addressed directly in an analysis of asymptotically free theories; and through the duality connection we are then led to statements about the form factors. For very large q{sup 2} the form factors are predicted to fall faster than any inverse power of q{sup 2}. For the more modest range of q{sup 2} reached in existing experiments the agreement with data is fairly good, though this may well be fortuitous. Extrapolations beyond this range are presented.
Non-Tikhonov asymptotic properties of cardiac excitability.
Biktashev, V N; Suckley, R
2004-10-15
Models of electric excitability of cardiac cells can be studied by singular perturbation techniques. To do this one should take into account parameters appearing in equations in nonstandard ways. The physical reason for this is near-perfect switch behavior of ionic current gates. This leads to a definition of excitability different from the currently accepted one. The asymptotic structure revealed by our analysis can be used to devise simplified caricature models, to obtain approximate analytical solutions, and to facilitate numerical simulations.
Asymptotics of Selberg-like integrals by lattice path counting
Novaes, Marcel
2011-04-15
We obtain explicit expressions for positive integer moments of the probability density of eigenvalues of the Jacobi and Laguerre random matrix ensembles, in the asymptotic regime of large dimension. These densities are closely related to the Selberg and Selberg-like multidimensional integrals. Our method of solution is combinatorial: it consists in the enumeration of certain classes of lattice paths associated to the solution of recurrence relations.
Evidence for asymptotic safety from lattice quantum gravity.
Laiho, J; Coumbe, D
2011-10-14
We calculate the spectral dimension for nonperturbative quantum gravity defined via Euclidean dynamical triangulations. We find that it runs from a value of ∼3/2 at short distance to ∼4 at large distance scales, similar to results from causal dynamical triangulations. We argue that the short-distance value of 3/2 for the spectral dimension may resolve the tension between asymptotic safety and the holographic principle.
Asymptotic Analysis of Ocean Bottom Reflected Acoustic Fields.
1984-05-01
dependence(e-i’t), the reflected spatial part of the acoustic pressure field P in a homogeneous medium due to a point source placed in that medium...reasonable to assume that the water colunm is homogeneous , especially for experiments which involve small source and receiver heights. In many abyssal plain...configuration, a homogeneous layer between two homo- eneous halfspaces. Using a modified uniform asymptotic method, Stickler and Ahluwalia[12] obtained
Asymptotic stability of nonlinear systems with unbounded delays
NASA Astrophysics Data System (ADS)
Tan, Man-Chun
2008-01-01
Some asymptotic stability criteria are derived for systems of nonlinear functional differential equations with unbounded delays. The criteria are described as matrix equations or matrix inequalities, which are computationally flexible and efficient. The theories are then applied to the stabilization of time-delay systems via standard feedback control (SFC) or time-delayed feedback control (DFC). Several examples are given to illustrate the results.
Asymptotic modeling of assemblies of thin linearly elastic plates
NASA Astrophysics Data System (ADS)
Licht, Christian
2007-12-01
We derive various models of assemblies of thin linearly elastic plates by abutting or superposition through an asymptotic analysis taking into account small parameters associated with the size and the stiffness of the adhesive. They correspond to the linkage of two Kirchhoff-Love plates by a mechanical constraint which strongly depends on the magnitudes of the previous parameters. To cite this article: C. Licht, C. R. Mecanique 335 (2007).
Exact asymptotic form for the {beta} function in quantum electrodynamics
Suslov, I. M.
2009-06-15
It is shown that the asymptotic form of the Gell-Mann-Low function in quantum electrodynamics can be determined exactly: {beta}(g) = g for g {sup {yields}} {infinity}, where g = e{sup 2} is the running fine-structure constant. This solves the problem of electrodynamics at small distances L (for which dependence g {infinity} L{sup -2} holds) and completely eliminates the problem of 'zero charge.'.
On an Asymptotically Consistent Unsteady Interacting Boundary Layer
NASA Technical Reports Server (NTRS)
Bartels, Robert E.
2007-01-01
This paper develops the asymptotic matching of an unsteady compressible boundary layer to an inviscid flow. Of particular importance is the velocity injection or transpiration boundary condition derived by this theory. It is found that in general the transpiration will contain a slope of the displacement thickness and a time derivative of a density integral. The conditions under which the second term may be neglected, and its consistency with the established results of interacting boundary layer are discussed.
Description of metastable states in the asymptotic line shape theory
NASA Astrophysics Data System (ADS)
Klimeshina, Tatyana E.; Rodimova, Olga B.
2014-11-01
A line-by-line calculation of the continuum absorption coefficient in the 1600 and 3600 cm-1 water vapor bands with the line wing shape corresponding to asymptotic line shape theory is presented. The calculation results agree closely with quasi-bound dimer absorption estimates made in the context of a dimer hypothesis. An examination of the classical part of the problem at hand enables the fraction of the quasi-bound dimers to be estimated.
Random walks models with intermediate fractional diffusion asymptotics
NASA Astrophysics Data System (ADS)
Saichev, Alexander I.; Utkin, Sergei G.
2004-05-01
Random walk process was investigated with PDF of random time intervals similar to fractional exponential law on small times and to regular exponential law on long times. Generalized fractional Kolmogorov-Feller equation was derived for such kind of process. Asymptotics of its PDF in the long time limit and for intermediate times were found. They obey standard diffusion law or fractional diffusion law respectively. Exact solutions of mentioned equations were numerically calculated, demonstrating crossover of fractional diffusion law into the linear one.
Reflections on a renaissance of occupation.
Whiteford, G; Townsend, E; Hocking, C
2000-02-01
At the close of the 20th century, there is a renaissance of occupation in occupational therapy and occupational science. Kielhofner (1992) offers an intraprofessional explanation that the growing interest in occupation recaptures occupational therapy's lost identity. An extraprofessional explanation is that postmodern ideas and social practices have helped to create a societal context in which a renaissance of occupation is welcome. Postmodernism raises questions and awareness of power, diversity, temporality, and situatedness in which normative ideas of occupation as paid work can be challenged. Since occupation is of primary concern to occupational therapy and occupational science, the authors reflect on postmodernism and its influence on a renaissance of occupation in these two fields. These reflections consider what such a renaissance means for occupational therapists and occupational scientists in the 21st century.
Modeling broadband poroelastic propagation using an asymptotic approach
Vasco, Donald W.
2009-05-01
An asymptotic method, valid in the presence of smoothly-varying heterogeneity, is used to derive a semi-analytic solution to the equations for fluid and solid displacements in a poroelastic medium. The solution is defined along trajectories through the porous medium model, in the manner of ray theory. The lowest order expression in the asymptotic expansion provides an eikonal equation for the phase. There are three modes of propagation, two modes of longitudinal displacement and a single mode of transverse displacement. The two longitudinal modes define the Biot fast and slow waves which have very different propagation characteristics. In the limit of low frequency, the Biot slow wave propagates as a diffusive disturbance, in essence a transient pressure pulse. Conversely, at low frequencies the Biot fast wave and the transverse mode are modified elastic waves. At intermediate frequencies the wave characteristics of the longitudinal modes are mixed. A comparison of the asymptotic solution with analytic and numerical solutions shows reasonably good agreement for both homogeneous and heterogeneous Earth models.
Asymptotic behavior of the warm inflation scenario with viscous pressure
Mimoso, Jose P.; Nunes, Ana; Pavon, Diego
2006-01-15
We analyze the dynamics of models of warm inflation with general dissipative effects. We consider phenomenological terms both for the inflaton decay rate and for viscous effects within matter. We provide a classification of the asymptotic behavior of these models and show that the existence of a late-time scaling regime depends not only on an asymptotic behavior of the scalar field potential, but also on an appropriate asymptotic behavior of the inflaton decay rate. There are scaling solutions whenever the latter evolves to become proportional to the Hubble rate of expansion regardless of the steepness of the scalar field exponential potential. We show from thermodynamic arguments that the scaling regime is associated with a power-law dependence of the matter-radiation temperature on the scale factor, which allows a mild variation of the temperature of the matter/radiation fluid. We also show that the late-time contribution of the dissipative terms alleviates the depletion of matter, and increases the duration of inflation.
Lectures on the asymptotic expansion of a Hermitian matrix integral
NASA Astrophysics Data System (ADS)
Mulase, Motohico
In these lectures three different methods of computing the asymptotic expansion of a Hermitian matrix integral is presented. The first one is a combinatorial method using Feynman diagrams. This leads us to the generating function of the reciprocal of the order of the automorphism group of a tiling of a Riemann surface. The second method is based on the classical analysis of orthogonal polynomials. A rigorous asymptotic method is established, and a special case of the matrix integral is computed in terms of the Riemann ζ-function. The third method is derived from a formula for the τ-function solution to the KP equations. This method leads us to a new class of solutions of the KP equations that are transcendental, in the sense that they cannot be obtained by the celebrated Krichever construction and its generalizations based on algebraic geometry of vector bundles on Riemann surfaces. In each case a mathematically rigorous way of dealing with asymptotic series in an infinite number of variables is established.
Asymptotic, multigroup flux reconstruction and consistent discontinuity factors
Trahan, Travis J.; Larsen, Edward W.
2015-05-12
Recent theoretical work has led to an asymptotically derived expression for reconstructing the neutron flux from lattice functions and multigroup diffusion solutions. The leading-order asymptotic term is the standard expression for flux reconstruction, i.e., it is the product of a shape function, obtained through a lattice calculation, and the multigroup diffusion solution. The first-order asymptotic correction term is significant only where the gradient of the diffusion solution is not small. Inclusion of this first-order correction term can significantly improve the accuracy of the reconstructed flux. One may define discontinuity factors (DFs) to make certain angular moments of the reconstructed flux continuous across interfaces between assemblies in 1-D. Indeed, the standard assembly discontinuity factors make the zeroth moment (scalar flux) of the reconstructed flux continuous. The inclusion of the correction term in the flux reconstruction provides an additional degree of freedom that can be used to make two angular moments of the reconstructed flux continuous across interfaces by using current DFs in addition to flux DFs. Thus, numerical results demonstrate that using flux and current DFs together can be more accurate than using only flux DFs, and that making the second angular moment continuous can be more accurate than making the zeroth moment continuous.
Asymptotic, multigroup flux reconstruction and consistent discontinuity factors
Trahan, Travis J.; Larsen, Edward W.
2015-05-12
Recent theoretical work has led to an asymptotically derived expression for reconstructing the neutron flux from lattice functions and multigroup diffusion solutions. The leading-order asymptotic term is the standard expression for flux reconstruction, i.e., it is the product of a shape function, obtained through a lattice calculation, and the multigroup diffusion solution. The first-order asymptotic correction term is significant only where the gradient of the diffusion solution is not small. Inclusion of this first-order correction term can significantly improve the accuracy of the reconstructed flux. One may define discontinuity factors (DFs) to make certain angular moments of the reconstructed fluxmore » continuous across interfaces between assemblies in 1-D. Indeed, the standard assembly discontinuity factors make the zeroth moment (scalar flux) of the reconstructed flux continuous. The inclusion of the correction term in the flux reconstruction provides an additional degree of freedom that can be used to make two angular moments of the reconstructed flux continuous across interfaces by using current DFs in addition to flux DFs. Thus, numerical results demonstrate that using flux and current DFs together can be more accurate than using only flux DFs, and that making the second angular moment continuous can be more accurate than making the zeroth moment continuous.« less
Holonomy spin foam models: asymptotic geometry of the partition function
NASA Astrophysics Data System (ADS)
Hellmann, Frank; Kaminski, Wojciech
2013-10-01
We study the asymptotic geometry of the spin foam partition function for a large class of models, including the models of Barrett and Crane, Engle, Pereira, Rovelli and Livine, and, Freidel and Krasnov. The asymptotics is taken with respect to the boundary spins only, no assumption of large spins is made in the interior. We give a sufficient criterion for the existence of the partition function. We find that geometric boundary data is suppressed unless its interior continuation satisfies certain accidental curvature constraints. This means in particular that most Regge manifolds are suppressed in the asymptotic regime. We discuss this explicitly for the case of the configurations arising in the 3-3 Pachner move. We identify the origin of these accidental curvature constraints as an incorrect twisting of the face amplitude upon introduction of the Immirzi parameter and propose a way to resolve this problem, albeit at the price of losing the connection to the SU(2) boundary Hilbert space. The key methodological innovation that enables these results is the introduction of the notion of wave front sets, and the adaptation of tools for their study from micro local analysis to the case of spin foam partition functions.
Surface terms, asymptotics and thermodynamics of the Holst action
NASA Astrophysics Data System (ADS)
Corichi, Alejandro; Wilson-Ewing, Edward
2010-10-01
We consider a first-order formalism for general relativity derived from the Holst action. This action is obtained from the standard Palatini-Hilbert form by adding a topological-like term and can be taken as the starting point for loop quantum gravity and spin foam models. The equations of motion derived from the Holst action are, nevertheless, the same as in the Palatini formulation. Here we study the form of the surface terms of the action for general boundaries as well as the symplectic current in the covariant formulation of the theory. Furthermore, we analyze the behavior of the surface terms in asymptotically flat spacetimes. We show that the contribution to the symplectic structure from the Holst term vanishes and one obtains the same asymptotic expressions as in the Palatini action. It then follows that the asymptotic Poincaré symmetries and conserved quantities such as energy, linear momentum and relativistic angular momentum found here are equivalent to those obtained from the standard Arnowitt, Deser and Misner formalism. Finally, we consider the Euclidean approach to black hole thermodynamics and show that the on-shell Holst action, when evaluated on some static solutions containing horizons, yields the standard thermodynamical relations.
Asymptotic normalization of mirror states and the effect of couplings
Titus, L. J.; Nunes, F. M.; Capel, P.
2011-09-15
Assuming that the ratio between asymptotic normalization coefficients of mirror states is model independent, charge symmetry can be used to indirectly extract astrophysically relevant proton capture reactions on proton-rich nuclei based on information on stable isotopes. The assumption has been tested for light nuclei within the microscopic cluster model. In this work we explore the Hamiltonian independence of the ratio between asymptotic normalization coefficients of mirror states when deformation and core excitation is introduced in the system. For this purpose we consider a phenomenological rotor+N model where the valence nucleon is subject to a deformed mean field and the core is allowed to excite. We apply the model to {sup 8}Li/{sup 8}B, {sup 13}C/{sup 13}N, {sup 17}O/{sup 17}F, {sup 23}Ne/{sup 23}Al, and {sup 27}Mg/{sup 27}P. Our results show that, for most studied cases, the ratio between asymptotic normalization coefficients of mirror states is independent of the strength and multipolarity of the couplings induced. The exception is for cases in which there is an s-wave coupled to the ground state of the core, the proton system is loosely bound, and the states have large admixture with other configurations. We discuss the implications of our results for novae.
Asymptotic Diffusion-Limit Accuracy of Sn Angular Differencing Schemes
Bailey, T S; Morel, J E; Chang, J H
2009-11-05
In a previous paper, Morel and Montry used a Galerkin-based diffusion analysis to define a particular weighted diamond angular discretization for S{sub n}n calculations in curvilinear geometries. The weighting factors were chosen to ensure that the Galerkin diffusion approximation was preserved, which eliminated the discrete-ordinates flux dip. It was also shown that the step and diamond angular differencing schemes, which both suffer from the flux dip, do not preserve the diffusion approximation in the Galerkin sense. In this paper we re-derive the Morel and Montry weighted diamond scheme using a formal asymptotic diffusion-limit analysis. The asymptotic analysis yields more information than the Galerkin analysis and demonstrates that the step and diamond schemes do in fact formally preserve the diffusion limit to leading order, while the Morel and Montry weighted diamond scheme preserves it to first order, which is required for full consistency in this limit. Nonetheless, the fact that the step and diamond differencing schemes preserve the diffusion limit to leading order suggests that the flux dip should disappear as the diffusion limit is approached for these schemes. Computational results are presented that confirm this conjecture. We further conjecture that preserving the Galerkin diffusion approximation is equivalent to preserving the asymptotic diffusion limit to first order.
Asymptotic accuracy of Bayesian estimation for a single latent variable.
Yamazaki, Keisuke
2015-09-01
In data science and machine learning, hierarchical parametric models, such as mixture models, are often used. They contain two kinds of variables: observable variables, which represent the parts of the data that can be directly measured, and latent variables, which represent the underlying processes that generate the data. Although there has been an increase in research on the estimation accuracy for observable variables, the theoretical analysis of estimating latent variables has not been thoroughly investigated. In a previous study, we determined the accuracy of a Bayes estimation for the joint probability of the latent variables in a dataset, and we proved that the Bayes method is asymptotically more accurate than the maximum-likelihood method. However, the accuracy of the Bayes estimation for a single latent variable remains unknown. In the present paper, we derive the asymptotic expansions of the error functions, which are defined by the Kullback-Leibler divergence, for two types of single-variable estimations when the statistical regularity is satisfied. Our results indicate that the accuracies of the Bayes and maximum-likelihood methods are asymptotically equivalent and clarify that the Bayes method is only advantageous for multivariable estimations.
Better band gaps with asymptotically corrected local exchange potentials
Singh, Prashant; Harbola, Manoj K.; Hemanadhan, M.; ...
2016-02-22
In this study, we formulate a spin-polarized van Leeuwen and Baerends (vLB) correction to the local density approximation (LDA) exchange potential [R. van Leeuwen and E. J. Baerends, Phys. Rev. A 49, 2421 (1994)] that enforces the ionization potential (IP) theorem following T. Stein et al. [Phys. Rev. Lett. 105, 266802 (2010)]. For electronic-structure problems, the vLB correction replicates the behavior of exact-exchange potentials, with improved scaling and well-behaved asymptotics, but with the computational cost of semilocal functionals. The vLB + IP correction produces a large improvement in the eigenvalues over those from the LDA due to correct asymptotic behaviormore » and atomic shell structures, as shown in rare-gas, alkaline-earth, zinc-based oxides, alkali halides, sulfides, and nitrides. In half-Heusler alloys, this asymptotically corrected LDA reproduces the spin-polarized properties correctly, including magnetism and half-metallicity. We also consider finite-sized systems [e.g., ringed boron nitride (B12N12) and graphene (C24)] to emphasize the wide applicability of the method.« less
Better band gaps with asymptotically corrected local exchange potentials
Singh, Prashant; Harbola, Manoj K.; Hemanadhan, M.; Mookerjee, Abhijit; Johnson, D. D.
2016-02-22
In this study, we formulate a spin-polarized van Leeuwen and Baerends (vLB) correction to the local density approximation (LDA) exchange potential [R. van Leeuwen and E. J. Baerends, Phys. Rev. A 49, 2421 (1994)] that enforces the ionization potential (IP) theorem following T. Stein et al. [Phys. Rev. Lett. 105, 266802 (2010)]. For electronic-structure problems, the vLB correction replicates the behavior of exact-exchange potentials, with improved scaling and well-behaved asymptotics, but with the computational cost of semilocal functionals. The vLB + IP correction produces a large improvement in the eigenvalues over those from the LDA due to correct asymptotic behavior and atomic shell structures, as shown in rare-gas, alkaline-earth, zinc-based oxides, alkali halides, sulfides, and nitrides. In half-Heusler alloys, this asymptotically corrected LDA reproduces the spin-polarized properties correctly, including magnetism and half-metallicity. We also consider finite-sized systems [e.g., ringed boron nitride (B_{12}N_{12}) and graphene (C_{24})] to emphasize the wide applicability of the method.
Environmental and occupational allergies.
Peden, David; Reed, Charles E
2010-02-01
Airborne allergens are the major cause of allergic rhinitis and asthma. Daily exposure comes from indoor sources, chiefly at home but occasionally at schools or offices. Seasonal exposure to outdoor allergens, pollens, and molds is another important source. Exposure to unusual substances at work causes occupational asthma, accounting for about 5% of asthma in adults. Indoor and outdoor air pollutants trigger airway inflammation and increase the severity of asthma. Diesel exhaust particles increase the production of IgE antibodies. Identification and reduction of exposure to allergens is a very important part of the management of respiratory allergic diseases. The first section of this chapter discusses domestic allergens, arthropods (mites and cockroaches), molds, and mammals (pets and mice). Indoor humidity and water damage are important factors in the production of mite and mold allergens, and discarded human food items are important sources of proliferation of cockroaches and mice. Means of identifying and reducing exposure are presented. The second section discusses outdoor allergens: pollens and molds. The particular plants or molds and the amount of exposure to these allergens is determined by the local climate, and local pollen and mold counts are available to determine the time and amount of exposure. Climate change is already having an important effect on the distribution and amount of outdoor allergens. The third section discusses indoor and outdoor air pollution and methods that individuals can take to reduce indoor pollution in addition to eliminating cigarette smoking. The fourth section discusses the diagnosis and management of occupational asthma.
Occupational Causes of Sarcoidosis
Newman, Kira L.; Newman, Lee S.
2012-01-01
Purpose of review Sarcoidosis, the multiorgan, granulomatous disease of unknown etiology, remains mysterious. Several important investigations in the past two years add to accumulating evidence for both occupational and environmental causes of granulomatous inflammation. Recent findings This review considers the most recent studies that contribute to the hypothesis that sarcoidosis occurs when individuals are exposed to foreign antigens and to inorganic particulates that promote inflammation. Major recent findings, such as those emerging from the study of World Trade Center responders, the study of nanoparticles, and cases of work-associated sarcoidosis support the probability that occupational, as well as environmental, exposures to inflammatory stimuli trigger sarcoidosis-like illness. Major recent studies of microbially-rich indoor environments, including moldy indoor workplaces and mycobacterially-contaminated settings, contribute to the evidence that a variety of microbial antigens serve as targets for the hypersensitivity immune response in an inflammatory milieu. Summary There is increasing evidence that sarcoidosis can occur in workplace settings in which there is exposure to both foreign antigens and inorganic triggers of inflammation that promote an exuberant granulomatous immune response. It is likely that sarcoidosis has more than one cause. PMID:22314258
Occupational injuries in Tehran.
Roudsari, Bahman Sayyar; Ghodsi, Mohammad
2005-01-01
As the first step in evaluation of the magnitude of the occupational injuries (OIs) in our community, we focused on hospital records of more than 8400 hospitalized trauma patients in six large university hospitals during 13 months of data gathering process. Fourteen percent of 8426 trauma patients had OIs (1180 cases) and 95% of them were male. Adults 19-39 years comprised 63% of the patients. Eleven percent of the patients were 18 years old or younger. Construction workers (26%), simple workers (26%), and industrial workers (17%) comprised nearly 70% of the OIs. Falls (39%) and striking by blunt objects (29%) were the most common mechanisms of injury. More than 60% of the patients did not have any type of insurance. A younger patient has a higher the probability of being uninsured. Head (49%) wrist and hand (46%) and knee and leg (36%) injuries were the most common regions injured. Additional community-based studies are needed to determine the risk of OIs among different occupational categories, as well as to identify the most vulnerable groups.
Graphic Communications. Occupational Competency Analysis Profile.
ERIC Educational Resources Information Center
Ohio State Univ., Columbus. Vocational Instructional Materials Lab.
This Occupational Competency Analysis Profile (OCAP), which is one of a series of OCAPs developed to identify the skills that Ohio employers deem necessary to entering a given occupation/occupational area, lists the occupational, academic, and employability skills required of individuals entering graphic communications occupations. The…
Precision Machining Technologies. Occupational Competency Analysis Profile.
ERIC Educational Resources Information Center
Ohio State Univ., Columbus. Vocational Instructional Materials Lab.
This Occupational Competency Analysis Profile (OCAP), which is one of a series of OCAPs developed to identify the skills that Ohio employers deem necessary to entering a given occupation/occupational area, lists the occupational, academic, and employability skills required of individuals entering the occupation of precision machinist. The…
Occupational Food Service Series. Duty Task List.
ERIC Educational Resources Information Center
Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.
This document contains the occupational duty/task lists for six occupations in the occupational food service series. Each occupation is divided into three to eight duties. A separate page for each duty in the occupation lists the tasks in that duty along with its code number and columns to indicate whether that particular duty has been taught and…
Instructional Support System--Occupational Education. Building Industries Occupations.
ERIC Educational Resources Information Center
Abramson, Theodore; And Others
The modules which make up the bulk of this report are the result of a two-week workshop at which thirteen building industries occupations teachers worked toward the development of a student outcome oriented curriculum. These modules are divided into the following occupational units: (1) carpentry (containing hand tools; portable power tools;…
On the Center of Mass of Asymptotically Hyperbolic Initial Data Sets
NASA Astrophysics Data System (ADS)
Cederbaum, Carla; Cortier, Julien; Sakovich, Anna
2016-06-01
We define the (total) center of mass for suitably asymptotically hyperbolic time-slices of asymptotically anti-de Sitter spacetimes in general relativity. We do so in analogy to the picture that has been consolidated for the (total) center of mass of suitably asymptotically Euclidean time-slices of asymptotically Minkowskian spacetimes (isolated systems). In particular, we unite -- an altered version of -- the approach based on Hamiltonian charges with an approach based on CMC-foliations near infinity. The newly defined center of mass transforms appropriately under changes of the asymptotic coordinates and evolves in the direction of an appropriately defined linear momentum under the Einstein evolution equations.
Asymptotic number of hairpins of saturated RNA secondary structures.
Clote, Peter; Kranakis, Evangelos; Krizanc, Danny
2013-12-01
In the absence of chaperone molecules, RNA folding is believed to depend on the distribution of kinetic traps in the energy landscape of all secondary structures. Kinetic traps in the Nussinov energy model are precisely those secondary structures that are saturated, meaning that no base pair can be added without introducing either a pseudoknot or base triple. In this paper, we compute the asymptotic expected number of hairpins in saturated structures. For instance, if every hairpin is required to contain at least θ=3 unpaired bases and the probability that any two positions can base-pair is p=3/8, then the asymptotic number of saturated structures is 1.34685[Symbol: see text]n (-3/2)[Symbol: see text]1.62178 (n) , and the asymptotic expected number of hairpins follows a normal distribution with mean [Formula: see text]. Similar results are given for values θ=1,3, and p=1,1/2,3/8; for instance, when θ=1 and p=1, the asymptotic expected number of hairpins in saturated secondary structures is 0.123194[Symbol: see text]n, a value greater than the asymptotic expected number 0.105573[Symbol: see text]n of hairpins over all secondary structures. Since RNA binding targets are often found in hairpin regions, it follows that saturated structures present potentially more binding targets than nonsaturated structures, on average. Next, we describe a novel algorithm to compute the hairpin profile of a given RNA sequence: given RNA sequence a 1,…,a n , for each integer k, we compute that secondary structure S k having minimum energy in the Nussinov energy model, taken over all secondary structures having k hairpins. We expect that an extension of our algorithm to the Turner energy model may provide more accurate structure prediction for particular RNAs, such as tRNAs and purine riboswitches, known to have a particular number of hairpins. Mathematica(™) computations, C and Python source code, and additional supplementary information are available at the website http://bioinformatics.bc.edu/clotelab/RNAhairpinProfile/ .
Asymptotic solutions of a fourth—order analogue for the Painlevé equations
NASA Astrophysics Data System (ADS)
Gaiur, I. Yu; Kudryashov, N. A.
2017-01-01
Asymptotic solutions of a fourth-order analogue for the Painlevé equations that is self-similar reduction of the modified Sawada-Kotera and Kaup-Kupershmidt equation is considered. The Boutroux variables of two types have been found which allows us to find asymptotic solutions of the equation in the neighbourhood of the infinity. It was shown that asymptotic of self-similar solution for the modified Sawada-Kotera and Kaup-Kupershmidt equations can be determined as solutions of autonomous differential equations. Asymptotic solutions expressed by elementary functions have been found too. Besides asymptotic solutions expressed by logarithmic derivative of two elliptic Weierstrass functions have been found. Connection between obtained asymptotic solutions and asymptotic solutions of the Sawada-Kotera and Kaup-Kupershmidt equations has been discussed.
An Exploration of the Role of Occupation in School-Based Occupational Therapy Practice
ERIC Educational Resources Information Center
Benson, Jeryl DiSanti
2010-01-01
The purpose of this study was to explore the role of occupation in school-based occupational therapy practice. The research questions were (1) How do school-based occupational therapists describe the role of occupation during intervention? (2) Which theories of occupation do school-based occupational therapists associate with their own practice?…
Going to an Occupational Therapist
... or spina bifida may need to use a wheelchair. An occupational therapist can help kids in wheelchairs come up with a plan to go through ... Parents MORE ON THIS TOPIC Word! Occupational Therapy Wheelchairs Going to a Physical Therapist Cerebral Palsy Contact ...
Electronics. Occupational Competency Analysis Profile.
ERIC Educational Resources Information Center
Ohio State Univ., Columbus. Vocational Instructional Materials Lab.
This Occupational Competency Analysis Profile (OCAP) contains a competency list verified by expert workers and developed through a modified DACUM (Developing a Curriculum) involving business, industry, labor, and community agency representatives from Ohio. This OCAP identifies the occupational, academic, and employability skills (competencies)…
CAREER GUIDE FOR DEMAND OCCUPATIONS.
ERIC Educational Resources Information Center
LEE, E.R.; WELCH, JOHN L.
THIS PUBLICATION UPDATES THE "CAREER GUIDE FOR DEMAND OCCUPATIONS" PUBLISHED IN 1959 AND PROVIDES COUNSELORS WITH INFORMATION ABOUT OCCUPATIONS IN DEMAND IN MANY AREAS WHICH REQUIRE PREEMPLOYMENT TRAINING. IT PRESENTS, IN COLUMN FORM, THE EDUCATION AND OTHER TRAINING USUALLY REQUIRED BY EMPLOYERS, HIGH SCHOOL SUBJECTS OF PARTICULAR PERTINENCE TO…
Career and Occupational Development Items.
ERIC Educational Resources Information Center
Education Commission of the States, Denver, CO. National Assessment of Educational Progress.
The career and occupational development items contained in this document are part of a kit consisting of four documents which bring together different types of items that measure a number of career and occupational development (COD) objectives developed by the National Assessment of Educational Progress (NAEP). (NAEP--which completed a national…
Suicide and Occupation: A Review.
ERIC Educational Resources Information Center
Bedeian, Arthur G.
1982-01-01
Examined the literature dealing with the relation of occupation to suicide for three occupational categories: health care providers, managerial and professional persons, and military and paramilitary personnel. Presents evidence relating to group differences in suicidal behavior. Considers theories explaining variations in incidence of suicide.…
Performance Specifications for Occupational Programs.
ERIC Educational Resources Information Center
Maryland State Dept. of Education, Baltimore. Div. of Career Technology and Adult Learning.
This document lists and discusses the development of Maryland's performance specifications for occupational programs. The introduction explains the process used to develop performance standards and specifications for 10 career cluster majors that were identified by a task force of educators and employers as high-demand occupational areas in…
Occupational hazards to hospital personnel
Patterson, W.B.; Craven, D.E.; Schwartz, D.A.; Nardell, E.A.; Kasmer, J.; Noble, J.
1985-05-01
Hospital personnel are subject to various occupational hazards. Awareness of these risks, compliance with basic preventive measures, and adequate resources for interventions are essential components of an occupational health program. Physical, chemical, and radiation hazards; important infectious risks; and psychosocial problems prevalent in hospital workers are reviewed. A rational approach to managing and preventing these problems is offered. 370 references.
New Roles for Occupational Instructors.
ERIC Educational Resources Information Center
Campbell, Dale F.
Changes in the future role of occupational instructors which will be brought about by advances in educational technology are illustrated by the description of the Advanced Instructional System (AIS), a complex approach to occupational training which permits large-scale application of individualized instruction through the use of computer-assisted…
Business Management Occupations: Skill Standards.
ERIC Educational Resources Information Center
Vocational Technical Education Consortium of States, Decatur, GA.
This report organizes the information provided by 77 individuals in business management occupations in 12 states into skills inventories for persons in these jobs. The skills inventories contain the following sections: (1) occupation-specific knowledge (communication, mathematics, science); (2) workplace behaviors (work ethics, interpersonal…
OCCUPATIONS IN ELECTRONIC COMPUTING SYSTEMS.
ERIC Educational Resources Information Center
Bureau of Employment Security (DOL), Washington, DC.
OCCUPATIONAL INFORMATION FOR USE IN THE PLACEMENT AND COUNSELING SERVICES OF THE AFFILIATED STATE EMPLOYMENT SERVICES IS PRESENTED IN THIS BROCHURE, ESENTIALLY AN UPDATING OF "OCCUPATIONS IN ELECTRONIC DATA-PROCESSING SYSTEMS," PUBLISHED IN 1959. JOB ANALYSES PROVIDED THE PRIMARY SOURCE OF DATA, BUT ADDITIONAL INFORMATION AND DATA WERE OBTAINED…
Business Financial Occupations: Skill Standards.
ERIC Educational Resources Information Center
Vocational Technical Education Consortium of States, Decatur, GA.
This report organizes the information provided by 71 individuals in finance-related occupations in 11 states into skills inventories for persons in these jobs. The skills inventories contain the following sections: (1) occupation-specific knowledge (communication, mathematics, science); (2) workplace behaviors (work ethics, interpersonal…
Eklund, Mona; Orban, Kristina; Argentzell, Elisabeth; Bejerholm, Ulrika; Tjörnstrand, Carina; Erlandsson, Lena-Karin; Håkansson, Carita
2017-01-01
Patterns of daily occupations (PDO) and occupational balance (OB) are recurring phenomena in the literature. Both are related with health and well-being, which makes them central in occupational therapy practice and occupational science. The aim was to review how PDO and OB are described in the literature, to propose a view of how the two constructs may be linked, and elaborate on how such a view may benefit occupational science and occupational therapy. The literature was analysed by latent and manifest content analysis and comparative analysis. The findings were summarized in a model, framing PDO as the more objective and OB as the more subjective result from an interaction between personal preferences and environmental influences. The proposed model does not assume a cause-effect relationship between the targeted constructs, rather a mutual influence and a joint reaction to influencing factors. Indicators of PDO and OB were identified, as well as tools for assessing PDO and OB. The authors propose that discerning PDO and OB as separate but interacting phenomena may be useful in developing a theoretical discourse in occupational science and enhancing occupational therapy practice. Although the scope of this study was limited, the proposed view may hopefully inspire further scrutiny of constructs.
The purpose of occupational medicine.
Raffle, P A
1975-01-01
The purposes of occupational medicine are described in terms of its clinical medical, environmental medical, research, and administrative content. Each of these components is essential in different proportions in comprehensive occupational health services for different industries, and can only be satisfactorily provided by occupational physicians and occupational health nurses who are an integral part of their organizations. Two-thirds of the working population in the United Kingdom are without the benefits of occupational medicine. The reorganization of the National Health Service and of local government presents the opportunity to extend occupational health services to many more workers who need them. It is suggested that area health authorities should provide occupational health services for all National Health Service staff and, on an agency basis, for local government and associated services, eventually extending to local industry. Such area health authority based services, merged with the Employment Medical Advisory Service, could conveniently then be part of the National Health Service, as recommended by the British Medical Association, the Society of Occupational Medicine, and the Medical Services Review Committee. PMID:1131336
Agricultural Occupations Program Planning Guide.
ERIC Educational Resources Information Center
Hemp, Paul E.; Mayer, Leon
The major program objectives of agricultural occupations courses are (1) to develop agricultural competencies needed by individuals engaged in or preparing to engage in production agriculture, and in agricultural occupations other than production agriculture; (2) to develop an understanding of the career opportunities in agriculture; (3) to…
64 FR 34625 - Occupational Exposure to Tuberculosis
Federal Register 2010, 2011, 2012, 2013, 2014
1999-06-28
... Tuberculosis AGENCY: Occupational Safety and Health Administration (OSHA), Department of Labor. ACTION: Notice..., 1997, OSHA published its proposed standard to regulate occupational exposure to tuberculosis (TB) (62... preliminary risk assessment for occupational exposure to tuberculosis. DATES: Comments and data...
75 FR 23834 - Occupational Information System
Federal Register 2010, 2011, 2012, 2013, 2014
2010-05-04
... ADMINISTRATION Occupational Information System AGENCY: Social Security Administration (SSA). ACTION: Request for... Recommendations for the Social Security Administration Occupational Information System, September 2009.'' The... to provide independent advice and recommendations on creating an occupational information...
DOE 2011 occupational radiation exposure
none,
2012-12-01
The U.S. Department of Energy (DOE) Office of Analysis within the Office of Health, Safety and Security (HSS) publishes the annual DOE Occupational Radiation Exposure Report to provide an overview of the status of radiation protection practices at DOE (including the National Nuclear Security Administration [NNSA]). The DOE 2011 Occupational Radiation Exposure Report provides an evaluation of DOE-wide performance regarding compliance with Title 10, Code of Federal Regulations (C.F.R.), Part 835, Occupational Radiation Protection dose limits and as low as reasonably achievable (ALARA) process requirements. In addition, the report provides data to DOE organizations responsible for developing policies for protection of individuals from the adverse health effects of radiation. The report provides a summary and an analysis of occupational radiation exposure information from the monitoring of individuals involved in DOE activities. The occupational radiation exposure information is analyzed in terms of aggregate data, dose to individuals, and dose by site over the past five years.
Achieving Quality in Occupational Health
NASA Technical Reports Server (NTRS)
O'Donnell, Michele (Editor); Hoffler, G. Wyckliffe (Editor)
1997-01-01
The conference convened approximately 100 registered participants of invited guest speakers, NASA presenters, and a broad spectrum of the Occupational Health disciplines representing NASA Headquarters and all NASA Field Centers. Centered on the theme, "Achieving Quality in Occupational Health," conferees heard presentations from award winning occupational health program professionals within the Agency and from private industry; updates on ISO 9000 status, quality assurance, and information technologies; workshops on ergonomics and respiratory protection; an overview from the newly commissioned NASA Occupational Health Assessment Team; and a keynote speech on improving women's health. In addition, NASA occupational health specialists presented 24 poster sessions and oral deliveries on various aspects of current practice at their field centers.
Polese, Luigi Gentile; Brackney, Larry
2015-05-19
An image-based occupancy sensor includes a motion detection module that receives and processes an image signal to generate a motion detection signal, a people detection module that receives the image signal and processes the image signal to generate a people detection signal, a face detection module that receives the image signal and processes the image signal to generate a face detection signal, and a sensor integration module that receives the motion detection signal from the motion detection module, receives the people detection signal from the people detection module, receives the face detection signal from the face detection module, and generates an occupancy signal using the motion detection signal, the people detection signal, and the face detection signal, with the occupancy signal indicating vacancy or occupancy, with an occupancy indication specifying that one or more people are detected within the monitored volume.
DOE 2012 occupational radiation exposure
none,
2013-10-01
The U.S. Department of Energy (DOE) Office of Analysis within the Office of Health, Safety and Security (HSS) publishes the annual DOE Occupational Radiation Exposure Report to provide an overview of the status of radiation protection practices at DOE (including the National Nuclear Security Administration [NNSA]). The DOE 2012 Occupational Radiation Exposure Report provides an evaluation of DOE-wide performance regarding compliance with Title 10, Code of Federal Regulations (C.F.R.), Part 835, Occupational Radiation Protection dose limits and as low as reasonably achievable (ALARA) process requirements. In addition, the report provides data to DOE organizations responsible for developing policies for protection of individuals from the adverse health effects of radiation. The report provides a summary and an analysis of occupational radiation exposure information from the monitoring of individuals involved in DOE activities. Over the past 5-year period, the occupational radiation exposure information is analyzed in terms of aggregate data, dose to individuals, and dose by site.
Occupational ergonomics in space
NASA Technical Reports Server (NTRS)
Stramler, J.
1992-01-01
Ergonomics is often defined simply as the study of work. Related or synonymous terms include human factors, human engineering, engineering psychology, and others. Occupational ergonomics is a term that has been proposed to describe the study of the working environment, including the physical consequences resulting from having an improperly designed workplace. The routine space working environment presents some problems not found in the typical Earthbound workplace. These include radiation, intravehicular contamination/pollution, temperature extremes, impact with other objects, limited psychosocial relationships, sensory deprivation, and reduced gravity. These are important workplace considerations, and may affect astronauts either directly at work or at some point during their life as a result of their work under these conditions. Some of the major issues associated with each of these hazards are presented.
[Chronic occupational metallic mercurialism].
Faria, Marcília de Araújo Medrado
2003-02-01
This is a review on current knowledge of chronic occupational mercurialism syndrome. Major scientific studies and reviews on clinical manifestation and physiopathology of mercury poisoning were evaluated. The search was complemented using Medline and Lilacs data. Erethism or neuropsychological syndrome, characterized by irritability, personality change, loss of self-confidence, depression, delirium, insomnia, apathy, loss of memory, headaches, general pain, and tremors, is seen after exposure to metallic mercury. Hypertension, renal disturbances, allergies and immunological conditions are also common. Mercury is found in many different work processes: industries, gold mining, and dentistry. As prevention measures are not often adopted there is an increasing risk of mercury poisoning. The disease has been under diagnosed even though 16 clinical forms of mercury poisoning are described by Brazilian regulations. Clinical diagnosis is important, especially because abnormalities in the central nervous, renal and immunological systems can be detected using current medical technology, helping to develop the knowledge and control measures for mercurialism.
Occupational cyanide poisoning
Amizet, Loic; Pruvot, Gauthier; Remy, Sophie; Kfoury, Michel
2011-01-01
Cyanide poisoning has existed for centuries. In most cases, cyanide is combined with other toxic substances; for example with carbon monoxide in fire smoke. Cases of pure cyanide poisoning are rare, and usually due to accidental exposure. Their treatment is based on oxygenation and the infusion of hydroxocobalamin. The seriousness of this type of poisoning calls for a rapid and specific response, which demonstrates the usefulness of non-hospital based medical treatment. The authors report here the case of a man who was the victim of occupational poisoning with sodium cyanide and who was treated at the workplace by fire-fighters and the Service Mobile d’Urgence et Reanimation emergency ambulance service. PMID:22674698
Occupational seafood allergy: a review
Jeebhay, M; Robins, T; Lehrer, S; Lopata, A
2001-01-01
BACKGROUND—Recent years have seen increased levels of production and consumption of seafood, leading to more frequent reporting of allergic reactions in occupational and domestic settings. This review focuses on occupational allergy in the fishing and seafood processing industry. REVIEW—Workers involved in either manual or automated processing of crabs, prawns, mussels, fish, and fishmeal production are commonly exposed to various constituents of seafood. Aerosolisation of seafood and cooking fluid during processing are potential occupational situations that could result in sensitisation through inhalation. There is great variability of aerosol exposure within and among various jobs with reported allergen concentrations ranging from 0.001 to 5.061(µg/m3). Occupational dermal exposure occurs as a result of unprotected handling of seafood and its byproducts. Occupational allergies have been reported in workers exposed to arthropods (crustaceans), molluscs, pisces (bony fish) and other agents derived from seafood. The prevalence of occupational asthma ranges from 7% to 36%, and for occupational protein contact dermatitis, from 3% to 11%. These health outcomes are mainly due to high molecular weight proteins in seafood causing an IgE mediated response. Cross reactivity between various species within a major seafood grouping also occurs. Limited evidence from dose-response relations indicate that development of symptoms is related to duration or intensity of exposure. The evidence for atopy as a risk factor for occupational sensitisation and asthma is supportive, whereas evidence for cigarette smoking is limited. Disruption of the intact skin barrier seems to be an important added risk factor for occupational protein contact dermatitis. CONCLUSION—The range of allergic disease associated with occupational exposure to crab is well characterised, whereas for other seafood agents the evidence is somewhat limited. There is a need for further epidemiological
Exploring central opacity and asymptotic scenarios in elastic hadron scattering
NASA Astrophysics Data System (ADS)
Fagundes, D. A.; Menon, M. J.; Silva, P. V. R. G.
2016-02-01
In the absence of a global description of the experimental data on elastic and soft diffractive scattering from the first principles of QCD, model-independent analyses may provide useful phenomenological insights for the development of the theory in the soft sector. With that in mind, we present an empirical study on the energy dependence of the ratio X between the elastic and total cross sections; a quantity related to the evolution of the hadronic central opacity. The dataset comprises all the experimental information available on proton-proton and antiproton-proton scattering in the c.m. energy interval 5 GeV-8 TeV. Generalizing previous works, we discuss four model-independent analytical parameterizations for X, consisting of sigmoid functions composed with elementary functions of the energy and three distinct asymptotic scenarios: either the standard black disk limit or scenarios above or below that limit. Our two main conclusions are the following: (1) although consistent with the experimental data, the black disk does not represent an unique solution; (2) the data reductions favor a semi-transparent scenario, with asymptotic average value for the ratio X bar = 0.30 ± 0.12. In this case, within the uncertainty, the asymptotic regime may already be reached around 1000 TeV. We present a comparative study of the two scenarios, including predictions for the inelastic channel (diffraction dissociation) and the ratio associated with the total cross-section and the elastic slope. Details on the selection of our empirical ansatz for X and physical aspects related to a change of curvature in this quantity at 80-100 GeV, indicating the beginning of a saturation effect, are also presented and discussed.
New developments in occupational dermatology.
Diepgen, Thomas L
2016-09-01
Occupational skin diseases according to BK No. 5101 - "severe or recurrent skin diseases which have forced the person to discontinue all occupational activities that caused or could cause the development, worsening, or recurrence of the disease" - is the most commonly reported notifiable occupational diseases in Germany. Following the optimization of measures of primary, secondary, and tertiary prevention, today most individuals affected are able to continue their profession. With the revision of the German ordinance on occupational diseases (BKV) in January 2015, skin cancer caused by UV irradiation was added to the list of occupational diseases. The new occupational disease (BK) 5103 is defined as "squamous cell carcinoma or multiple actinic keratoses of the skin caused by natural UV irradiation". In this context, "multiple" signifies the occurrence of either more than five individual actinic keratosis lesions over the course of 12 months or the presence of field cancerization of > 4 cm(2) . In the following review, important aspects of this new occupational disease will be highlighted and discussed.
The end of occupational therapy.
Crabtree, J L
1998-03-01
In this article, I propose that the unique end, or goal, of occupational therapy is to help persons with performance deficits of any kind make and express meaning through organized human performance, which I call occupation. To support this thesis, I show that, too often, philosophers, psychologists, and others who have studied meaning do not see human performance as a crucial way of making and expressing meaning. This article challenges the assumption that meaning making is only a cognitive process in which language is its primary expression and shows that the nature of humans is to make meaning through occupation. Furthermore, this article reveals why occupational therapy should emphasize human performance and its role in meaning making. Finally, I propose that occupation is properly defined as intentional human performance organized in number and kind to meet the demands of self-maintenance and identity in the family and community. I justify this definition and discuss the likely therapeutic nature of occupation and examples of the end, or goal, of occupational therapy.
Asymptotic safety and Kaluza-Klein gravitons at the LHC
Gerwick, Erik; Litim, Daniel; Plehn, Tilman
2011-04-15
We study Drell-Yan production at the LHC in low-scale quantum gravity models with extra dimensions. Asymptotic safety implies that the ultraviolet behavior of gravity is dictated by a fixed point. We show how the energy dependence of Newton's coupling regularizes the gravitational amplitude using a renormalization group improvement. We study LHC predictions and find that Kaluza-Klein graviton signals are well above standard model backgrounds. This leaves a significant sensitivity to the energy scale {Lambda}{sub T} where the gravitational couplings crossover from classical to fixed point scaling.
A model independent description of the deutron asymptotic D state
NASA Astrophysics Data System (ADS)
Ericson, T. E. O.; Rosa-Clot, M.
1982-04-01
The asymptotic deutron D state is shown to result nearly model-independently from iterated OPEP yielding a predicted value η = (0.02633 ± 0.00035). Alternatively the result leads to a determination of the πN coupling constant [ f2 = (0.0792 ± 0.0012 )]. Attention is drawn to the implications for the size of quark bags. Analogous considerations of the deutron quadrupole moment permit the first direct determination of its non-potential part from experiment ΔQ = (0.005 ± 0.004) fm 2.